Recording device, recording method, and recording unit

One disclosed aspect of the embodiments relates to a recording device, a recording method, and a recording unit.

There are known recording devices that record images by repeatedly executing recording scanning in which ink discharge is performed, where a recording unit that has a discharge port array in which multiple discharge orifices that discharge ink are arrayed, is relatively moved over an increment region of a recording medium. There has conventionally been demand for reduction in recording time on the recording medium regarding such recording devices. Japanese Patent Laid-Open No. 10-44519 describes using a recording unit, in which there are provided two recording parts, one to the left side and one to the right, in the scanning direction, to realize reduction in this recording time. Each recording part has multiple discharge orifice rows that discharge ink of multiple colors. Further described therein is discharging ink at the left side of the recording medium in the scanning direction only from the left-side recording part, and discharging ink at the right side of the recording medium in the scanning direction only from the right-side recording part. Accordingly, recording time can be reduced, since recording can be completed without the recording unit having to be scanned over the entire region from a position at the left edge portion of the recording medium to a corresponding position at the right edge portion of the recording medium.

Now, in a case of using the above-described recording unit to record the left and right sides of the recording medium in the scanning direction, using the respective left and right side recording parts, image quality at the boundary between the region recorded by the left-side recording part and the region recorded by the right-side recording part may deteriorate. In light of this point, Japanese Patent Laid-Open No. 10-44519 suppresses this deterioration in image quality by both the left-side recording part and the right-side recording part sharing recording of the middle portion in the scanning direction of the recording medium.

However, it has been found that, in a case of using a recording unit such as described above, with the recording part at one side and the recording part at the other side sharing recording of the middle portion in the scanning direction of the recording medium, unevenness in the recording may be conspicuous. This unevenness is due to discharge characteristics of the recording parts in images recorded by ink with a low lightness, depending on the array of discharge orifice rows within the recording unit.

In a case where there is difference in discharge characteristics among discharge orifice rows discharging ink of the same color provided to the recording part at one side and the recording part at the other side, due to manufacturing error, the image color will differ between a region recorded by the ink from one recording part and a region recorded by the ink from the other recording part. For example, in a case where there are differences in discharge characteristics, such as the discharge amount of the ink being greater at a discharge orifice row provided to one recording part as compared to a discharge orifice row provided to the other recording part, the region of the image recorded by the discharge orifice row provided to the one recording part (hereinafter referred to as “one region”) will be darker than the region of the image recorded by the discharge orifice row provided to the other recording part (hereinafter referred to as “other region”). The greater the difference in lightness between the recording medium and the ink is, the more conspicuous this change in color is.

Even in such a case, even if there is change in discharge amount due to difference in discharge characteristics between discharge orifice rows, occurring among regions on the recording medium, when using ink with a high lightness such as yellow ink for example, change in lightness between one region and the other region is inconspicuous. Normally, the color of the recording medium being used has a lightness higher than that of the ink, such as white or the like, so the difference in lightness is smaller as compared to ink with a low lightness. Accordingly, even if there is change in the discharge amount due to difference in discharge characteristics, the difference in lightness at one region and the difference in lightness at the other region do not vary that much. Accordingly, change in lightness between one region and the other region is inconspicuous.

However, with regard to black ink, for example, that has a low lightness, the difference in lightness at one region and the difference in lightness at the other region may vary greatly, since the lightness difference between the recording medium and the ink is great. Accordingly, there may be cases where change in lightness between one region and the other region is conspicuous.

Even in a case of using ink with a low lightness, the change in lightness due to difference discharge characteristics can be made less conspicuous, by making the width of the portion shared by the recording part at one side and the recording part at the other side sharing recording, in the scanning direction of the recording medium, to be longer. The image recorded in the region shared by the recording part at one side and the recording part at the other side will be recorded at a color having a density between that of the color of the image in the region recorded only by one recording part and that of the color of the image in the region recorded only by the other recording part. Accordingly, the longer the width of the portion shared by the recording part at one side and the recording part at the other side sharing recording in the scanning direction is, the more gradual the change in lightness is between the region recorded by only one recording part and the region recorded by only the other recording part, and this less conspicuous.

Now, in a case where the layout order of multiple discharge orifice rows in the scanning direction is the same among the recording parts, the width in the scanning direction can be made longer for the region where shared recording is performed by the discharge orifice rows for ink with low lightness, by making the scanning range of the recording unit longer. This enables the above-described change in lightness to be made inconspicuous. However, the amount of time required per scan becomes longer in this case due to the longer scanning range of the recording unit, consequently taking longer to complete recording on the recording medium. Further, a larger movable range for the recording unit needs to be provided within the recording device to realizing the longer scanning range of the recording unit, which leads to increased size of the recording device.

It has been found desirable to provide a recording device that enables making change in lightness inconspicuous even if change in discharge amount occurs due to change in discharge characteristics among recording parts, without making the scanning range of the recording unit longer.

A recording device includes: a recording unit, a scanning unit, and a recording control unit. The recording unit includes a first recording part where there are provided at least a first discharge orifice row where a plurality of discharge orifices that discharge a first ink are arrayed in a predetermined direction, and a second discharge orifice row where a plurality of discharge orifices that discharge a second ink of a different color from the first ink are arrayed in the predetermined direction, and a second recording part where there are provided at least a third discharge orifice row where a plurality of discharge orifices that discharge the first ink are arrayed in the predetermined direction, and a fourth discharge orifice row where a plurality of discharge orifices that discharge the second ink are arrayed in the predetermined direction. The first recording part and the second recording part are separated from each other in an intersecting direction that intersects the predetermined direction. The scanning unit is configured to perform recording scanning by moving the recording unit. The recording control unit is configured to, in a same recording scan by the scanning unit, perform recording of a region on the recording medium in the intersecting direction, including one edge of the recording medium, by only the first recording part, perform recording of a region on the recording medium in the intersecting direction, including the other edge of the recording medium, by only the second recording part, and perform recording of a region on the recording medium between the region recorded only by the first recording part and the region recorded only by the second recording part in the intersecting direction, by both the first recording part and the second recording part. The second ink has a higher lightness than the first ink. A distance between the first discharge orifice row and the third discharge orifice row in the intersecting direction is a first distance, and a distance between the second discharge orifice row and the fourth discharge orifice row in the intersecting direction is a second distance that is longer than the first distance.

Further features of the disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

FIG. 1 is a schematic diagram illustrating the internal configuration of a recording device according to an embodiment.

FIG. 2 is a diagram for describing a recording control system according to an embodiment.

FIG. 3 is a flowchart illustrating procedures of image processing according to an embodiment.

FIGS. 4A and 4B are schematic diagrams illustrating distribution patterns according to an embodiment.

FIG. 5 is a diagram illustrating lightness difference between inks and recording medium used in an embodiment.

FIGS. 6A and 6B are diagrams illustrating in detail a recording unit used in an embodiment.

FIG. 7 is a diagram for describing a recording system according to an embodiment.

FIG. 8 is a diagram schematically illustrating change in lightness in a case of applying an embodiment.

FIG. 9 is a diagram for describing a recording unit used in a comparative embodiment.

FIG. 10 is a diagram for describing a recording system according to a comparative embodiment.

FIG. 11 is a diagram schematically illustrating change in lightness in a case of applying a comparative embodiment.

FIG. 12 is a diagram for describing a recording system according to a comparative embodiment.

FIG. 13 is a diagram schematically illustrating change in lightness in a case of applying a comparative embodiment.

FIG. 14 is a diagram illustrating a recording unit used in an embodiment.

FIG. 15 is a diagram for describing a recording system according to an embodiment.

FIGS. 16A and 16B are diagrams illustrating distribution patterns according to an embodiment.

FIG. 17 is a diagram schematically illustrating change in lightness when applying an embodiment.

First Embodiment

A first embodiment will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram illustrating the internal configuration of an ink-jet recording device 310 according to an embodiment.

The ink-jet recording device (hereinafter also referred to as “printer”, “recording device”, and “image recording device”) 310 according to the present embodiment has a recording unit 101 . The recording unit 101 has a recording head 102 L and a recording head 102 R, the recording heads 102 L and 102 R being held by a single holding part 103 . The recording heads 102 L and 102 R each have one discharge orifice row each for discharging black ink, cyan ink, magenta ink, and yellow ink, which will be described in detail later. A recording medium 106 that is almost white is used in the present embodiment, which will also be described in detail later.

It can be seen from FIG. 1 that the recording heads 102 L and 102 R are at the same position in the Y direction and separated from each other in the X direction. Although the recording unit 101 is described here with the recording heads 102 L and 102 R being situated at the same position in the Y direction, this is not restrictive. The recording heads 102 L and 102 R may be provided at positions offset in the Y direction, as long as configured with a recording region corresponding to discharge orifice rows discharging ink of the respective colors partially overlapping in the Y direction, such that at least a partial region on the recording medium 106 can be recorded by both of the recording heads 102 L and 102 R in the same scan.

The recording unit 101 is capable of reciprocally moving relative to the recording medium 106 , in the X direction (intersecting direction) along a guide rail 104 provided extending in the X direction. The recording medium 106 is conveyed in the Y direction (conveyance direction) by rotating a conveyance roller 105 . The recording medium 106 is supported by a platen 107 provided at a position facing the recording unit 101 while the recording unit 101 is being scanned or the recording medium 106 is being conveyed. The ink-jet recording device 310 according to the present embodiment completes recording on the entire region of the recording medium 106 by repeatedly performing recording operations where the recording unit 101 is scanned in the X direction, and conveyance operations of the recording medium 106 in the Y direction by the conveyance roller 105 .

Using the recording unit 101 having two recording heads 102 L and 102 R enables recording to be performed with reduced recording time as compared to using a conventional single recording head. The reason is that the recording unit does not have to move from one end of the recording medium in the X direction to the other end, as with conventional arrangements. In a case of using the recording unit 101 such as described above, the entire region of the recording medium 106 in the X direction can be recorded by moving the above-described recording unit 101 such that at least one of two discharge orifice rows of the same color ink provided to each of the recording heads 102 L and 102 R faces the recording medium 106 . In this case, of the two discharge orifice rows discharging ink of the same color in the recording heads 102 L and 102 R, the region to the left in the X direction on the recording medium 106 is recorded by the discharge orifice row within the recording head 102 L alone, and the region to the right in the X direction by the discharge orifice row within the recording head 102 R alone. Further, shared recording of a region at the middle in the X direction is performed by both the discharge orifice row in the recording head 102 L and the discharge orifice row in the recording head 102 R. This recording control will be described in detail later.

FIG. 2 is a block diagram illustrating a schematic configuration of a recording control system according to the present embodiment. The recording control system according to the present embodiment is made up of the printer 310 illustrated in FIG. 1 , and a personal computer (hereinafter “PC”) 300 serving as a host device thereof.

The PC 300 is configured having the following components. A central processing unit (CPU) 301 executes processing following programs held in random access memory (RAM) 302 or a hard disk drive (HDD) 303 serving as storage. The RAM 302 is volatile memory, and temporarily stores programs and data. The HDD 303 is nonvolatile memory, and also stores programs and data. A data transfer interface 304 controls exchange of data with the printer 310 in the present embodiment. Examples of connection standards that can be used for this data exchange include USB, IEEE 1394, and IEEE 802. A keyboard and mouse interface 305 is an interface that controls human interface devices (HIDs) such as keyboards, mice, etc., by which the user can perform input. A display interface 306 controls display performed at a display unit (omitted from illustration).

On the other hand, the printer 310 is configured having the following components. A CPU 311 executes later-described processing following programs held in RAM 312 or read-only memory (ROM) 313 . The RAM 312 is volatile memory, and temporarily stores programs and data. The ROM 313 is nonvolatile memory, and can store table data and programs used in later-described processing. A data transfer interface 314 controls exchange of data with the PC 300 .

A left head controller 315 L and a right head controller 315 R respectively supply recording data to the recording head 102 L and recording head 102 R illustrated in FIG. 1 , and also control discharge operations of each of the recording heads 102 L and 102 R (discharge control). Specifically, the left head controller 315 L may have a configuration of reading control parameters and recording data from a predetermined address of the RAM 312 . Upon the CPU 311 writing control parameters and recording data to this predetermined address of the RAM 312 , processing is activated by the left head controller 315 L, and ink discharge is performed from the recording head 102 L. This is the same regarding the right head controller 315 R, in when the CPU 311 writes control parameters and recording data to a predetermined address of the RAM 312 , processing is activated by the right head controller 315 R, and ink discharge is performed from the recording head 102 R.

Data Processing Procedures

FIG. 3 is a flowchart of processing for generating recording data used for recording, executed by the CPU 311 following a control program according to the present embodiment. Note that this control program is stored in the ROM 313 beforehand.

When RGB data in RGB format is acquired at the recording device 310 from the PC 300 , color conversion processing is first performed in step S 801 , to convert the RGB data into ink color data corresponding to the colors of inks used for recording. This color conversion processing generates ink color data represented in 8-bit 256-color information that sets the lightness for each of multiple pixels. The present embodiment uses black ink, cyan ink, magenta ink, and yellow ink in the present embodiment as described above, so ink color data is generated by color conversion processing in step S 801 that corresponds to each of the black ink, cyan ink, magenta ink, and yellow ink. Different processing may be executed as appropriate for the color conversion processing, or a three-dimensional look-up table (3D-LUT) stipulating the correspondence between RGB values and CMYK values that is stored in the ROM 313 beforehand for example, or further, tetrahedral interpolation may be performed.

Next, in step S 802 , tone correction processing where tone values indicated by ink color data for each of the CMYK values are corrected, and tone correction data where the CMYK values are expressed in the form of 8-bit 256-color information is generated. A one-dimensional look-up table (1D-LUT), stipulating the correspondence between ink color data corresponding to each color ink before correction and tone correction data corresponding to each color ink after correction, or the like, may be used in this tone correction processing, for example. Note that the 1D-LUT is stored in the ROM 313 beforehand.

In step S 803 , quantization processing is performed where the tone correction data is quantized, and quantization data (image data) expressed in the form of 1-bit binary information, setting discharge/non-discharge of ink for each color corresponding to each pixel, is generated. Various conventionally-known types of processing, such as error diffusion, dithering, etc., may be applied to the quantization processing.

Next, in step S 804 , distribution processing is performed where, of the quantization data corresponding to each ink color, and quantization data corresponding to the region at the middle of the recording medium in the X direction, where shared recording is to be performed, is distributed to the recording head 102 L and recording head 102 R. Further, the logical sum is obtained in this distribution processing for quantization data distributed to the recording head 102 L and quantization data corresponding to the region at the left side of the recording medium in the X direction where shared recording is not performed, thereby generating distribution data corresponding to the recording head 102 L, in which is set discharge/non-discharge of ink of each color from the recording head 102 L as to the recording medium, regarding each pixel. In the same way, the logical sum is obtained for quantization data distributed to the recording head 102 R and quantization data corresponding to the region at the right side of the recording medium in the X direction where shared recording is not performed, thereby generating distribution data corresponding to the recording head 102 R, in which is set discharge/non-discharge of ink of each color from the recording head 102 R as to the recording medium, regarding each pixel. This left-right recording head distribution processing will be described later.

Then in step S 805 L, the distribution data corresponding to the recording head 102 L is distributed to multiple scans (passes) performed over the same unit region on the recording medium, and recording data for the recording head 102 L, used for discharging ink from the recording head 102 L in each of the multiple scans, is generated. In the same way, in step S 805 R, the distribution data corresponding to the recording head 102 L is distributed to multiple scans, and recording data for the recording head 102 R, used for discharging ink from the recording head 102 R in each of the multiple scans, is generated. Discharging operations for discharging from the recording heads 102 L and 102 R are executed according to the recording data for the recording heads 102 L and 102 R generated in steps S 805 L and S 805 R. Note that the processing in steps S 805 L and S 805 R can be carried out by using multiple mask patterns having layouts of recording-permitted pixels regarding which recording is permitted, and recording-non-permitted pixels regarding which recording is not permitted, corresponding to multiple scans, for example. These multiple mask patterns are stored in the ROM 313 beforehand.

Although an arrangement where multiple scans are performed as to one unit region has been described, a unit region may be scanned just once. In this case, the processing in steps S 805 L and S 805 R can be omitted. Also, although an arrangement has been described here where the CPU 311 in the printer 310 performs all of the processing from step S 801 through steps S 805 L and S 805 R, the CPU 301 in the PC 300 may perform part or all of the processing from step S 801 through steps S 805 L and S 805 R.

FIGS. 4A and 4B are schematic diagrams illustrating an example of distribution patterns used in the left-right head distribution processing in step S 804 in the present embodiment. FIG. 4A corresponds to a certain color, and is a diagram schematically illustrating a distribution pattern for distributing quantization data corresponding to an image in a region at the middle of the recording medium in the X direction, where shared recording by two discharge orifice rows provided to the recording heads 102 L and 102 R, to the discharge orifice row provided to the recording head 102 L. FIG. 4B corresponds to the same certain color, and is a diagram schematically illustrating a distribution pattern for distributing the quantization data to the discharge orifice row provided to the recording head 102 R. Note that these distribution patterns are stored in the ROM 313 beforehand.

To simplify explanation here, description will be made regarding an arrangement where the region at the middle in the X direction where shared recording is performed is a region that has a size of 14 pixels in the X direction. Accordingly, the distribution patterns illustrated in FIGS. 4A and 4B , corresponding to the discharge orifice rows provided to the recording heads 102 L and 102 R, also have a size of 14 pixels in the X direction. Note however, that the size of the region at the middle in the X direction where shared recording is performed differs in size depending on what color ink the discharge orifice rows discharge in the present embodiment, which will be described later. Advantages of the present embodiment can be yielded in such cases as well, as long as the distribution patterns satisfy later-described conditions.

The distribution patterns illustrated in FIGS. 4A and 4B are configured with an 8-pixel size in the Y direction as a repetition unit, and the left-right head distribution processing is completed as to the entirety of the region where shared recording is to be performed, by repeatedly using these distribution patterns in the Y direction. In the distribution patterns illustrated in FIGS. 4A and 4B , the black pixels indicate pixels regarding which discharging of ink is permitted in a case where ink discharge is set by the quantization data. On the other hand, the white pixels indicate pixels regarding which discharging of ink is not permitted, even in a case where ink discharge is set by the quantization data.

It can be seen from FIGS. 4A and 4B that the distribution pattern corresponding to the discharge orifice row provided to the recording head 102 L used in the present embodiment, and the distribution pattern corresponding to the discharge orifice row provided to the recording head 102 R have ink discharge permitted at mutually exclusive and complementary positions. Accordingly, left-right head distribution processing can be performed so that in a case where quantization data instructing discharge of ink to all pixels is acquired as the quantization data corresponding to the region where shared recording is to be performed, for example, ink is discharged just once, from either one or the other of a discharge orifice row in the recording head 102 L and a discharge orifice row in the recording head 102 R, at all pixels within this region.

Further, it can be seen from FIGS. 4A and 4B that the distribution pattern corresponding to the discharge orifice row in the recording head 102 L and the distribution pattern corresponding to the discharge orifice row in the recording head 102 R, used in the present embodiment, each have half of the total number of pixels permitted to discharge ink, regardless of the position in the X direction on the recording medium. Accordingly, in a case of using the distribution patterns illustrated in FIGS. 4A and 4B , the distribution ratio of quantization data to the discharge orifice row of the recording head 102 L and of quantization data to the discharge orifice row of the recording head 102 R is 50% each in the region where shared recording is performed. Thus, the total of the distribution ratio of quantization data to the discharge orifice row of the recording head 102 L and of quantization data to the discharge orifice row of the recording head 102 R is 100% in the region where shared recording is performed as well, so the discharge amount of ink as to the region where shared recording is performed is not greatly different from the discharge amount desirable for the regions where shared recording is not performed.

The data processing procedures such as described above are used in the present embodiment to generate recording data used for recording based on acquired RGB data, and to control ink discharge from the recording unit 101 following the recording data.

Composition of Ink

The compositions of the cyan ink, magenta ink, yellow ink, and black ink, used in the present embodiment, will each be described in detail. Note that in the following description, “parts” and “%” are to be understood to be “parts by mass” and “% by mass”, unless specifically stated otherwise.

1. Cyan Ink

The cyan ink used in the present embodiment contains C.I. Direct Blue 199, which is a dye, as a color material. Specifically, the cyan ink used in the present embodiment is prepared by blending and agitating the following components, followed by filtration under pressure using a micro-filter.

C.I. Direct Blue 199 3% Diethylene Glycol 10%  Isopropyl Alcohol 2% Urea 5% Acetylenol EH (Manufactured by 1% Kawaken Fine Chemicals Co., Ltd.) Ion-exchanged water 79%

2. Magenta Ink

The magenta ink used in the present embodiment contains C.I. Acid Red 289, which is a dye, as a color material. Specifically, the magenta ink used in the present embodiment is prepared by blending and agitating the following components, followed by filtration under pressure using a micro-filter.

C.I. Acid Red 289 3% Diethylene Glycol 10%  Isopropyl Alcohol 2% Urea 5% Acetylenol EH (Manufactured by 1% Kawaken Fine Chemicals Co., Ltd.) Ion-exchanged water 79%

3. Yellow Ink

The yellow ink used in the present embodiment contains C.I. Direct Yellow 86, which is a dye, as a color material. Specifically, the yellow ink used in the present embodiment is prepared by blending and agitating the following components, followed by filtration under pressure using a micro-filter.

C.I. Direct Yellow 86 3% Diethylene Glycol 10%  Isopropyl Alcohol 2% Urea 5% Acetylenol EH (Manufactured by 1% Kawaken Fine Chemicals Co., Ltd.) Ion-exchanged water 79%

4. Black Ink

The black ink used in the present embodiment contains C.I. Direct Black 154, which is a dye, as a color material. Specifically, the black ink used in the present embodiment is prepared by blending and agitating the following components, followed by filtration under pressure using a micro-filter.

It can be seen from the above that of the inks used in the present embodiment, the cyan ink, magenta ink, and yellow ink, which are color ink, contain acetylenol EH. On the other hand, the black ink does not contain acetylenol EH.

Now, acetylenol EH is a type of acetylene glycol surfactant, and aids in improving the permeability of ink. The fixability of color ink according to the present embodiment as to the recording embodiment is improved by containing acetylenol EH, which improves permeability as to the recording medium and speeds up the permeation speed.

On the other hand, in a case where the permeation speed of ink is increased, a phenomenon may occur where the ink spreads following fibers of the recording medium after having been deposited thereupon. This phenomenon leads to so-called “feathering”, where ink spreads on the recording medium. Feathering particularly leads to poor image quality in the case of recording character images and fine-line images. Accordingly, since black ink is often used in recording character images and fine-line images, the black ink according to the present embodiment does not contain acetylenol EH, thereby suppressing occurrence of feathering by keeping the permeability low.

Difference in Lightness Between Ink and Recording Medium

Comparing images where ink with high lightness and ink with low lightness are each applied to a recording medium shows that the change in lightness between regions recorded by the recording heads 102 L and 102 R is conspicuous in the ink with low lightness. In a case where there is difference in discharge characteristics between the two discharge orifice rows discharging ink of the same color in the recording heads 102 L and 102 R, due to manufacturing error or the like, the amount of discharge will differ between the two. In a case where the amount of discharge increases/decreases at one of the discharge orifice rows, the lightness after fixation is lower/higher.

Now, giving thought to ink with a low lightness (e.g., black ink) and ink with a high lightness (e.g., yellow ink), and a recording medium that has a higher lightness than normally-used ink (e.g., a white recording medium), the difference in lightness between the ink and recording medium is greater for the ink with the low lightness. Accordingly, in a case where there is difference in discharge amount between the two discharge orifice rows in the recording heads 102 L and 102 R, due to difference in discharge characteristics at one of the recording heads 102 L and 102 R, the difference in lightness between the recording medium and fixed ink in the region recorded by the discharge orifice row in the recording head 102 L alone, and the difference in lightness between the recording medium and fixed ink in the region recorded by the discharge orifice row in the recording head 102 R alone, will be greater the lower the lightness of the ink is. Accordingly, the difference in lightness at the region recorded by the recording head 102 L and the difference in lightness at the region recorded by the recording head 102 R is greater the lower the lightness of the ink is, so change in lightness between the regions is more conspicuous.

In light of the above, the layout order of discharge orifice rows in the recording heads 102 L and 102 R that discharge the inks is decided based on the lightness of each ink being used in the present embodiment, which will be described later. FIG. 5 is a diagram illustrating measurement results of the lightness of the inks used in the present embodiment, and of the surface of the recording medium.

Measurements showed that the lightness L* of the recording medium was 95, which is a high value, the surface of the recording medium being almost white. On the other hand, the lightness L* of the black ink, cyan ink, magenta ink, and yellow ink was 5, 45, 50, and 90, respectively. Further, the lightness difference ΔL* between the black ink, cyan ink, magenta ink, and yellow ink and the surface of the recording medium was 90, 50, 45, and 5, respectively. It can thus be seen that of the inks used in the present embodiment, the ink of which the change in lightness between the regions described above is most conspicuous is the black ink that has the lowest lightness.

Details of Recording Unit

The recording unit 101 used in the present embodiment can make the above-described change in lightness inconspicuous for ink with low lightness, by arrangement of the array in the X direction of multiple discharge orifice rows discharging ink of multiple colors in the recording head 102 L, and arrangement of the array in the X direction of multiple discharge orifice rows discharging ink of multiple colors in the recording head 102 R, without increasing the recording time or size of the recording device. Specifically, the present embodiment uses a recording unit where the distance between discharge orifice rows in the recording heads 102 L and 102 R discharging ink with low lightness is shorter than the distance between discharge orifice rows in the recording heads 102 L and 102 R discharging ink with high lightness.

FIGS. 6A and 6B are diagrams illustrating the recording unit 101 used in the present embodiment in detail. FIG. 6A schematically illustrates the recording unit 101 from below in the vertical direction as to the XY plane. FIG. 6B schematically illustrates the recording unit 101 as viewed from the Y direction.

The recording head 102 L and the recording head 102 R in the recording unit 101 according to the present embodiment are separated by a distance W 5 in the X direction. The recording head 102 L has four discharge orifice rows 111 C, 111 M, 111 Y, and 111 K, in the order of discharge orifice row 111 C that discharges cyan ink, discharge orifice row 111 M that discharges magenta ink, discharge orifice row 111 Y that discharges yellow ink, and discharge orifice row 111 K that discharges black ink, from the left side in the X direction. On the other hand, the recording head 102 R has four discharge orifice rows 112 C, 112 M, 112 Y, and 112 K, in the order of discharge orifice row 112 K that discharges black ink, discharge orifice row 112 C that discharges cyan ink, discharge orifice row 112 M that discharges magenta ink, and discharge orifice row 112 Y that discharges yellow ink, from the left side in the X direction.

Note that the four discharge orifice rows 111 C, 111 M, 111 Y, and 111 K in the recording head 102 L are laid out separated from each other by a same distance d. In the same way, the four discharge orifice rows 112 C, 112 M, 112 Y, and 112 K in the recording head 102 R are laid out separated from each other by the same distance d. The eight discharge orifice rows each have multiple discharge orifices (omitted from illustration) that discharge ink, arrayed in the Y direction (predetermined direction).

The discharge orifices within each discharge orifice row in the recording head 102 L are connected to an ink tank accommodating the respective ink, via channels omitted from illustration. In detail, the discharge orifices arrayed in the discharge orifice row 111 C are connected to an ink tank 108 C accommodating cyan ink, the discharge orifices arrayed in the discharge orifice row 111 M are connected to an ink tank 108 M accommodating magenta ink, the discharge orifices arrayed in the discharge orifice row 111 Y are connected to an ink tank 108 Y accommodating yellow ink, and the discharge orifices arrayed in the discharge orifice row 111 K are connected to an ink tank 108 K accommodating black ink. In the same way, in the recording head 102 R the discharge orifices arrayed in the discharge orifice row 112 C are connected to an ink tank 109 C accommodating cyan ink, the discharge orifices arrayed in the discharge orifice row 112 M are connected to an ink tank 109 M accommodating magenta ink, the discharge orifices arrayed in the discharge orifice row 112 Y are connected to an ink tank 109 Y accommodating yellow ink, and the discharge orifices arrayed in the discharge orifice row 112 K are connected to an ink tank 109 K accommodating black ink.

Although an arrangement has been described here where the discharge orifice rows in the recording head 102 L and the discharge orifice rows in the recording head 102 R that discharge ink of the same color are connected to different ink tanks, discharge orifice rows that discharge ink of the same color may be connected to the same single tank. Regardless of whether different ink tanks are used or the same ink tank is used, providing the ink tank(s) at the middle of the holding part 103 in the X direction enables the recording unit 101 to be reduced in size. However, if reduction in size is not an issue, and two different ink tanks are to be used, a design may be made where the middle portions of the respective ink heads and the ink tanks in the X direction generally agree, for example.

Now, the distance in the X direction between two discharge orifice rows that discharge ink of the same color in the present embodiment will be described for each of the colors. In order to simplify description, the width in the X direction of the discharge orifice rows, and the width in the X direction of regions at the edges within the recording heads where no discharge orifice rows are formed, will be disregarded.

First, with regard to the cyan ink, the discharge orifice row 111 C is situated the fourth from the right side in the X direction within the recording head 102 L, and the discharge orifice row 112 C is situated the second from the left side in the X direction within the recording head 102 R. Accordingly, distance W_C 1 in the X direction between the discharge orifice row 111 C and discharge orifice row 112 C is a distance that can be calculated by Expression (1-1).

W _ C 1= W 5+3× d+ 1× d=W 5+4 d   Expression (1-1)

Now, the term “3×d” in Expression (1-1) is a term corresponding to the fact that there are three discharge orifice rows to the right of the discharge orifice row 111 C in the X direction within the recording head 102 L. The term “1×d” in Expression (1-1) is a term corresponding to the fact that there is one discharge orifice row to the left of the discharge orifice row 112 C in the X direction within the recording head 102 R.

In the same way, with regard to the magenta ink, the discharge orifice row 111 M is situated the third from the right side in the X direction within the recording head 102 L, and the discharge orifice row 112 M is situated the third from the left side in the X direction within the recording head 102 R. Accordingly, distance W_M 1 in the X direction between the discharge orifice row 111 M and discharge orifice row 112 M is a distance that can be calculated by Expression (1-2).

W _ M 1= W 5+2× d+ 2× d=W 5+4 d   Expression (1-2)

Also, with regard to the yellow ink, the discharge orifice row 111 Y is situated the second from the right side in the X direction within the recording head 102 L, and the discharge orifice row 112 Y is situated the fourth from the left side in the X direction within the recording head 102 R. Accordingly, distance W_Y 1 in the X direction between the discharge orifice row 111 Y and discharge orifice row 112 Y is a distance that can be calculated by Expression (1-3).

W _ Y 1= W 5+1× d+ 3× d=W 5+4 d   Expression (1-3)

Further, with regard to the black ink, the discharge orifice row 111 K is situated the first from the right side in the X direction within the recording head 102 L, and the discharge orifice row 112 K is situated the first from the left side in the X direction within the recording head 102 R. Accordingly, distance W_K 1 in the X direction between the discharge orifice row 111 K and discharge orifice row 112 K is a distance that can be calculated by Expression (1-4).

W _ K 1= W 5+0× d+ 0× d=W 5  Expression (1-4)

It can thus be seen from Expressions (1-1), (1-2), (1-3), and (1-4), that in the recording unit 101 used in the present embodiment, the discharge orifice rows are arranged such that the distance W_K 1 (W 5 ) between the discharge orifice rows 111 K and 112 K that discharge black ink is shorter than the distance W_C 1 between the discharge orifice rows 111 C and 112 C that discharge cyan ink, the distance W_M 1 between the discharge orifice rows 111 M and 112 M that discharge magenta ink, and the distance W_Y 1 between the discharge orifice rows 111 Y and 112 Y that discharge yellow ink, which are all (W 5 +4d). Thus, the multiple discharge orifice rows that discharge multiple colors of ink are arrayed in the multiple recording heads such that the distance between discharge orifice rows discharging ink with low lightness is shorter than the distance between discharge orifice rows discharging ink with high lightness in the recording unit according to the present embodiment.

Recording Control of Recording Unit

Next, a mechanism will be described in detail which can make the change in lightness inconspicuous for ink that has great difference in lightness as to the surface of the recording medium, without increasing the recording time or size of the recording device, by using the recording unit illustrated in FIGS. 6A and 6B . FIG. 7 is a diagram for describing the way in which recording is performed on the recording medium 106 using the recording unit 101 according to the present embodiment. Of the two recording units 101 illustrated in FIG. 7 , the recording unit 101 situated at the left side in the X direction and drawn using dashed lines schematically illustrates the scan start position of the recording unit 101 when scanning the recording unit 101 from the left side toward the right side in the X direction, while the recording unit 101 situated at the right side in the X direction and drawn using solid lines schematically illustrates the scan end position of the recording unit 101 . In order to simplify description, just the four discharge orifice rows of the discharge orifice rows 111 K and 112 K that discharge black ink, having the lowest lightness, and the discharge orifice rows 111 Y and 112 Y that discharge yellow ink, having the highest lightness, will be described.

The recording unit 101 according to the present embodiment is scanned over a range from where the discharge orifice row situated at the right edge portion of the recording head 102 L in the X direction is at a position facing an edge position X 1 at the left edge of the recording medium 106 in the X direction, to where the discharge orifice row situated at the left edge portion of the recording head 102 R in the X direction is at a position facing an edge position X 2 at the right edge of the recording medium 106 in the X direction. The recording unit 101 can be scanned over this range by the recording unit 101 being moved by a distance ΔX 1 . Thus, according to the present embodiment, the recording unit does not have to be moved over the entire region from one edge of the recording medium in the X direction to the other edge as in conventional arrangements, so recording can be performed with reduced recording time.

Hereinafter, a position on the recording medium in the X direction that the discharge orifice row 112 K within the recording head 102 R faces at the scan start position of the recording unit 101 will be defined as position X 3 , and a position on the recording medium in the X direction that the discharge orifice row 112 Y within the recording head 102 R faces will be defined as position X 5 . Also, a position on the recording medium in the X direction that the discharge orifice row 111 K within the recording head 102 L faces at the scan end position of the recording unit 120 will be defined as position X 4 , and a position on the recording medium in the X direction that the discharge orifice row 111 Y within the recording head 102 L faces will be defined as position X 6 .

It can be seen from FIG. 7 that, in a case of scanning the recording unit 101 for the distance ΔX 1 , the discharge orifice row 112 K for black ink in the recording head 102 R cannot face a region on the recording medium 106 to the left side of the position X 3 in the X direction. Accordingly, black ink can only be discharged from the discharge orifice row 111 K in the recording head 102 L to the region A 1 on the recording medium 106 from the edge position X 1 to the position X 3 . It can similarly be seen that the discharge orifice row 111 K for black ink in the recording head 102 L cannot face a region on the recording medium 106 to the right side of the position X 4 in the X direction. Accordingly, black ink can only be discharged from the discharge orifice row 112 K in the recording head 102 R to the region A 3 on the recording medium 106 from the position X 4 to the edge position X 2 . The region A 2 on the recording medium 106 from positions X 3 to X 4 can be faced by both the discharge orifice row 111 K in the recording head 102 L and the discharge orifice row 112 K in the recording head 102 R while scanning the recording unit 101 over the distance ΔX 1 .

In light of this point, black ink is not discharged from the discharge orifice row 112 K as to the region A 1 on the recording medium 106 ; black ink is discharged to the region A 1 only from the discharge orifice row 111 K in the present embodiment. Also, black ink is not discharged from the discharge orifice row 111 K as to the region A 3 on the recording medium 106 ; black ink is discharged to the region A 3 only from the discharge orifice row 112 K. Further, black ink is discharged to the region A 2 on the recording medium 106 from both the discharge orifice row 111 K and the discharge orifice row 112 K.

On the other hand, it can be seen from FIG. 7 that, in a case of scanning the recording unit 101 for the distance ΔX 1 , the discharge orifice row 112 Y for yellow ink in the recording head 102 R cannot face a region on the recording medium 106 to the left side of the position X 5 in the X direction. Accordingly, yellow ink can only be discharged from the discharge orifice row 111 Y in the recording head 102 L to the region A 4 on the recording medium 106 from the edge position X 1 to the position X 5 . Note that position X 5 is a position further to the right side in the X direction than the position X 3 . Accordingly, the distance of the region A 4 in the X direction is longer than the distance of the region A 1 in the X direction.

It can similarly be seen that the discharge orifice row 111 Y for yellow ink in the recording head 102 L cannot face a region on the recording medium 106 to the right side of the position X 6 in the X direction while scanning the recording unit 101 over the distance ΔX 1 . Accordingly, yellow ink can only be discharged from the discharge orifice row 112 Y in the recording head 102 R to the region A 6 on the recording medium 106 from the position X 6 to the edge position X 2 . Note that position X 6 is a position further to the left side in the X direction than the position X 4 . Accordingly, the distance of the region A 6 in the X direction is longer than the distance of the region A 3 in the X direction.

The region A 5 on the recording medium 106 from positions X 5 to X 6 can be faced by both the discharge orifice row 111 Y in the recording head 102 L and the discharge orifice row 112 Y in the recording head 102 R while scanning the recording unit 101 over the distance ΔX 1 . Position X 5 is situated further to the right side in the X direction than position X 3 , and position X 6 is situated further to the left side in the X direction than position X 4 , so the width of region A 5 in the X direction is shorter than the width of the region A 2 in the X direction.

In light of this point, yellow ink is not discharged from the discharge orifice row 112 Y as to the region A 4 on the recording medium 106 in the present embodiment; yellow ink is discharged to the region A 4 only from the discharge orifice row 111 Y. Also, yellow ink is not discharged from the discharge orifice row 111 Y as to the region A 6 on the recording medium 106 ; yellow ink is discharged to the region A 6 only from the discharge orifice row 112 Y. Further, yellow ink is discharged to the region A 5 on the recording medium 106 from both the discharge orifice row 111 Y and the discharge orifice row 112 Y.

Further, controlling discharge of black ink from the discharge orifice rows 111 K and 112 K, and discharge of yellow ink from the discharge orifice rows 111 Y and 112 Y, while scanning the recording unit 101 over the distance ΔX 1 , enables the entire region of the recording medium 106 to be recorded while shortening the recording time. Further, with regard to black ink that has a low lightness, the region A 1 where recording is performed by the discharge orifice row 111 K alone and the region A 3 where recording is performed by the discharge orifice row 112 K alone can be placed further apart. Accordingly, even in a case where discharge characteristics are different at one of the discharge orifice row 111 K and discharge orifice row 112 K, the change in lightness between the region A 1 and the region A 3 can be made to be inconspicuous.

FIG. 8 is a diagram for describing change in lightness in a case where difference in discharge characteristics has occurred at one of the recording head 102 L and recording head 102 R, and that the amount of discharge from discharge orifice rows in the recording head 102 L has become greater than the amount of discharge from discharge orifice rows in the recording head 102 R. A case is illustrated here where the degree of difference in discharge characteristics occurring among the discharge orifice rows is around the same for each color. The horizontal axis represents the position on the recording medium and the vertical axis represents the relative lightness of images recorded by each of black ink and yellow ink. In the present embodiment, the aforementioned relative lightness of an image is obtained by recording the entire region in the X direction by ink of a single color, calculating the difference in lightness between the image of ink of one color and the recording medium in each region, and obtaining the ratio in difference in lightness at each position as to an average of the difference in lightness.

FIG. 8 illustrates the relative lightness of images recorded by black ink using solid lines, and the relative lightness of images recorded by yellow ink using dashed lines. FIG. 8 also assumes a case where the generated recording data is such that the amount of discharge for both black ink and yellow ink would be the same regardless the position on the recording medium in the X direction, had there been no difference in discharge characteristics. Although the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink actually are different, FIG. 8 illustrates the relative lightness shifted in the lightness direction so that the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink agree, for sake of simplifying description.

First, the change in lightness of the images recorded by the yellow ink will be described. Yellow ink is discharged to the region A 4 from edge position X 1 to position X 5 by the discharge orifice row 111 Y alone, as described above. The discharge orifice row 111 Y has a greater discharge amount. Accordingly, the relative lightness D_Y 1 of the image recorded in the region A 4 by the yellow ink is a relatively low value.

On the other hand, yellow ink is discharged to the region A 6 from position X 6 to edge position X 2 by the discharge orifice row 112 Y alone. The discharge orifice row 112 Y has a smaller discharge amount. Accordingly, the relative lightness D_Y 2 of the image recorded in the region A 6 by the yellow ink is a relatively high value.

Yellow ink is discharged to the region A 5 from position X 5 to position X 6 by both the discharge orifice row 111 Y that has a greater discharge amount and the discharge orifice row 112 Y that has a smaller discharge amount, in a shared manner. Accordingly, the relative lightness of the image recorded in the region A 5 by the yellow ink is a value around the middle between D_Y 1 and D_Y 2 .

Now, the difference in lightness as to the recording medium is small since the lightness of yellow ink is high. Accordingly, a relative lightness difference D_Y 2 −D_Y 1 , which is the difference between the relative lightness D_Y 1 in region A 4 and the relative lightness D_Y 2 in region A 6 also is relatively smaller. Thus, although the distance between the region A 4 where the image with the low relative lightness D_Y 1 is recorded and the region A 6 where the image with the high relative lightness D_Y 2 is recorded is short, the relative lightness difference D_Y 2 −D_Y 1 is small, so the change in lightness in the X direction is gradual. Accordingly, change in lightness of yellow ink is inconspicuous.

Next, the change in lightness of the images recorded by the black ink will be described. Black ink is discharged to the region A 1 from edge position X 1 to position X 3 by the discharge orifice row 111 K alone, as described above. The discharge orifice row 111 K has a greater discharge amount. Accordingly, the relative lightness D_K 1 of the image recorded in the region A 1 by the black ink is a relatively low value.

On the other hand, black ink is discharged to the region A 3 from position X 4 to edge position X 2 by the discharge orifice row 112 K alone. The discharge orifice row 112 K has a smaller discharge amount. Accordingly, the relative lightness D_K 2 of the image recorded in the region A 3 by the black ink is a relatively high value.

Black ink has a lower lightness than yellow ink, so the difference in lightness of black ink as to the recording medium is greater as compared to that of yellow ink. Accordingly, the relative lightness D_K 1 is greater than the relative lightness D_Y 1 , and the relative lightness D_K 2 is smaller than the relative lightness D_Y 2 .

Black ink is discharged to the region A 2 from position X 3 to position X 4 by both the discharge orifice row 111 K that has a greater discharge amount and the discharge orifice row 112 K that has a smaller discharge amount. Accordingly, the relative lightness of the image recorded in the region A 2 by the black ink is a value around the middle between D_K 1 and D_K 2 .

As described above, the difference in lightness as to the recording medium is great, since the lightness of black ink is low. Accordingly, a relative lightness difference D_K 2 −D_K 1 , which is the difference between the relative lightness D_K 1 in region A 1 and the relative lightness D_K 2 in region A 3 also is relatively great. However, the distance between the region A 1 where the image with the low relative lightness D_K 1 is recorded and the region A 3 where the image with the high relative lightness D_K 2 is recorded can be made to be longer than that of the yellow ink. Further, an image having a value around the middle between D_K 1 and D_K 2 can be recorded between region A 1 and region A 3 . Accordingly, although the relative lightness difference D_K 2 −D_K 1 between region A 1 and region A 3 is great, so the change in lightness in the X direction can be made to be gradual. Consequently, an image can be obtained where change in lightness is inconspicuous regarding the black ink as well.

Next, a mechanism will be described which can make the change in lightness due to difference in discharge characteristics inconspicuous, without increasing the recording time or size of the recording device, by using the recording unit and recording method according to the present embodiment. This description will be made by referencing two comparative embodiments, and comparing the recording unit and recording method according to these comparative embodiments with the recording unit and recording method according to the present embodiment.

FIG. 9 is a diagram illustrating a recording unit 120 used in the first and second comparative embodiments. A recording head 124 L and recording head 124 R are provided within the recording unit 120 according to the first and second comparative embodiments, separated from each other by the distance W 5 in the X direction, in the same way as in the recording unit 101 illustrated in FIG. 6A . The recording heads 124 L and 124 R are held by a single holding part 123 .

The recording head 124 L according to the first comparative embodiment has four discharge orifice rows 121 C, 121 M, 121 Y, and 121 K, in the order of discharge orifice row 121 C that discharges cyan ink, discharge orifice row 121 M that discharges magenta ink, discharge orifice row 121 Y that discharges yellow ink, and discharge orifice row 121 K that discharges black ink, from the left side in the X direction. On the other hand, the recording head 124 R has four discharge orifice rows 122 C, 122 M, 122 Y, and 122 K, in the order of discharge orifice row 122 C that discharges cyan ink, discharge orifice row 122 M that discharges magenta ink, discharge orifice row 122 Y that discharges yellow ink, and discharge orifice row 122 K that discharges black ink, from the left side in the X direction. The discharge orifice rows in the recording heads 124 L and 124 R are laid out separated from each other by a same distance d in the X direction, the same as in the present embodiment.

Next, the distance in the X direction between the two discharge orifice rows that discharge ink of each color according to the first and second comparative embodiments will be described in the same way as with the present embodiment. First, with regard to the cyan ink, the discharge orifice row 121 C is situated the fourth from the right side in the X direction within the recording head 124 L, and the discharge orifice row 122 C is situated the first from the left side in the X direction within the recording head 124 R. Accordingly, distance W_C 2 in the X direction between the discharge orifice row 121 C and discharge orifice row 122 C is a distance that can be calculated by Expression (2-1).

W _ C 2= W 5+3× d+ 0× d=W 5+3 d   Expression (2-1)

Now, the term “3×d” in Expression (2-1) is a term corresponding to the fact that there are three discharge orifice rows to the right of the discharge orifice row 121 C in the X direction within the recording head 124 L. The term “0×d” in Expression (2-1) is a term corresponding to the fact that there are no discharge orifice rows to the left of the discharge orifice row 122 C in the X direction within the recording head 124 R.

Similarly, with regard to the magenta ink, the discharge orifice row 121 M is situated the third from the right side in the X direction within the recording head 124 L, and the discharge orifice row 122 M is situated the second from the left side in the X direction within the recording head 124 R. Accordingly, distance W_M 2 in the X direction between the discharge orifice row 121 M and discharge orifice row 122 M is a distance that can be calculated by Expression (2-2).

W _ M 2= W 5+2× d+ 1× d=W 5+3 d   Expression (2-2)

Also, with regard to the yellow ink, the discharge orifice row 121 Y is situated the second from the right side in the X direction within the recording head 124 L, and the discharge orifice row 122 Y is situated the third from the left side in the X direction within the recording head 124 R. Accordingly, distance W_Y 2 in the X direction between the discharge orifice row 121 Y and discharge orifice row 122 Y is a distance that can be calculated by Expression (2-3).

W _ Y 2= W 5+1× d+ 2× d=W 5+3 d   Expression (2-3)

Further, with regard to the black ink, the discharge orifice row 121 K is situated the first from the right side in the X direction within the recording head 124 L, and the discharge orifice row 122 K is situated the fourth from the left side in the X direction within the recording head 124 R. Accordingly, distance W_K 2 in the X direction between the discharge orifice row 121 K and discharge orifice row 122 K is a distance that can be calculated by Expression (2-4).

W _ K 2= W 5+0× d+ 3× d=W 5+3 d   Expression (2-4)

It can thus be seen from Expressions (2-1), (2-2), (2-3), and (2-4), that in the recording unit 120 used in the first and second comparative embodiments illustrated in FIG. 9 , the discharge orifice rows are arranged such the distance W_C 2 between the discharge orifice rows 121 C and 122 C that discharge cyan ink, the distance W_M 2 between the discharge orifice rows 121 M and 122 M that discharge magenta ink, the distance W_Y 2 between the discharge orifice rows 121 Y and 122 Y that discharge yellow ink, and the distance W_K 2 between the discharge orifice rows 121 K and 122 K that discharge black ink, are equal to each other (W 5 +3d).

1. First Comparative Example

FIG. 10 is a diagram for describing the way in which recording is performed on the recording medium 106 using the recording unit 120 according to the first comparative embodiment. Of the two recording units 120 illustrated in FIG. 9 , the recording unit 120 situated at the left side in the X direction and drawn using dashed lines schematically illustrates the scan start position of the recording unit 120 when scanning the recording unit 120 from the left side toward the right side, while the recording unit 120 situated at the right side in the X direction and drawn using solid lines schematically illustrates the scan end position of the recording unit 120 . In order to simplify description, just the four discharge orifice rows of the discharge orifice rows 121 K and 122 K that discharge black ink, having the lowest lightness, and the discharge orifice rows 121 Y and 122 Y that discharge yellow ink, having the highest lightness, will be described.

The recording unit 120 according to the first comparative embodiment is scanned over a range from where the discharge orifice row situated at the right edge portion of the recording head 124 L in the X direction is at a position facing an edge position X 1 at the left edge of the recording medium 106 in the X direction, to where the discharge orifice row situated at the left edge portion of the recording head 124 R in the X direction is at a position facing an edge position X 2 at the right edge of the recording medium 106 in the X direction. The recording unit 101 can be scanned over this range by the recording unit 101 being moved by a distance ΔX 1 , in the same way as the present embodiment illustrated in FIG. 7 .

Hereinafter, a position on the recording medium in the X direction that the discharge orifice row 122 K within the recording head 124 R faces at the scan start position of the recording unit 120 will be defined as position X 13 , and a position on the recording medium in the X direction that the discharge orifice row 122 Y within the recording head 124 R faces will be defined as position X 15 . Also, a position on the recording medium in the X direction that the discharge orifice row 121 K within the recording head 124 L faces at the scan end position of the recording unit 120 will be defined as position X 14 , and a position on the recording medium in the X direction that the discharge orifice row 121 Y within the recording head 124 L faces will be defined as position X 16 .

It can be seen from FIG. 10 that, in a case of scanning the recording unit 120 for the distance ΔX 1 , the discharge orifice row 122 K for black ink in the recording head 124 R cannot face a region on the recording medium 106 to the left side of the position X 13 in the X direction. Accordingly, black ink can only be discharged from the discharge orifice row 121 K in the recording head 124 L to the region B 1 on the recording medium 106 from the edge position X 1 to the position X 13 . It can similarly be seen that the discharge orifice row 121 K for black ink in the recording head 124 L cannot face a region on the recording medium 106 to the right side of the position X 14 in the X direction. Accordingly, black ink can only be discharged from the discharge orifice row 122 K in the recording head 124 R to the region B 3 on the recording medium 106 from the position X 14 to the edge position X 2 . The region B 2 on the recording medium 106 from positions X 13 to X 14 can be faced by both the discharge orifice row 121 K in the recording head 124 L and the discharge orifice row 122 K in the recording head 124 R while scanning the recording unit 120 over the distance ΔX 1 .

In the first comparative example, black ink is not discharged from the discharge orifice row 122 K as to the region B 1 on the recording medium 106 ; black ink is discharged to the region B 1 only from the discharge orifice row 121 K. Also, black ink is not discharged from the discharge orifice row 121 K as to the region B 3 on the recording medium 106 ; black ink is discharged to the region B 3 only from the discharge orifice row 122 K. Further, ink is discharged to the region B 2 on the recording medium 106 from both the discharge orifice row 121 K and the discharge orifice row 122 K.

On the other hand, in a case of scanning the recording unit 120 for the distance ΔX 1 , the discharge orifice row 122 Y for yellow ink in the recording head 124 R cannot face a region on the recording medium 106 to the left side of the position X 15 in the X direction. Accordingly, yellow ink can only be discharged from the discharge orifice row 121 Y in the recording head 124 L to the region B 4 on the recording medium 106 from the edge position X 1 to the position X 15 . It can similarly be seen that the discharge orifice row 121 Y for yellow ink in the recording head 124 L cannot face a region on the recording medium 106 to the right side of the position X 16 in the X direction while scanning the distance ΔX 1 . Accordingly, yellow ink can only be discharged from the discharge orifice row 122 Y in the recording head 124 R to the region B 6 on the recording medium 106 from the position X 16 to the edge position X 2 .

The region B 5 on the recording medium 106 from positions X 15 to X 16 can be faced by both the discharge orifice row 121 Y in the recording head 124 L and the discharge orifice row 122 Y in the recording head 124 R while scanning the recording unit 120 over the distance ΔX 1 . Accordingly, in the first comparative embodiment, yellow ink is not discharged from the discharge orifice row 122 Y as to the region B 4 on the recording medium 106 ; ink is discharged to the region B 4 only from the discharge orifice row 121 Y. Also, yellow ink is not discharged from the discharge orifice row 121 Y as to the region B 6 on the recording medium 106 ; ink is discharged to the region B 6 only from the discharge orifice row 122 Y. Further, ink is discharged to the region B 5 on the recording medium 106 from both the discharge orifice row 121 Y and the discharge orifice row 122 Y.

Comparing the first comparative embodiment with the present embodiment, the scan end position is no different between the recording unit 120 and the recording unit 101 , and the order of array of discharge orifice rows within the recording head 124 L is no different from that in the recording head 102 L. Accordingly, the position X 14 is actually the same position as the position X 4 , and the position X 16 as the position X 6 .

On the other hand, while the scan start position is no different between the recording unit 120 and the recording unit 101 , the order of array of discharge orifice rows within the recording head 124 L is different from that in the recording head 102 L. Specifically, while the discharge orifice row 122 K is situated the first from the right side in the X direction out of the four discharge orifice rows within the recording head 124 R, and the discharge orifice row 122 Y is situated the second from the right side in the X direction, the discharge orifice row 112 K is situated the fourth from the right side in the X direction out of the four discharge orifice rows within the recording head 102 R, and the discharge orifice row 112 Y is situated the first from the right side in the X direction. Thus, it can be seen that position X 13 is situated further to the right in the X direction than position X 3 , and position X 15 is situated further to the left in the X direction than position X 5 .

Accordingly, it can be seen that the region B 2 from position X 13 to position X 14 in the first comparative example is narrower in width than the region A 2 from position X 3 to position X 4 in the present embodiment. In the same way, it can be seen that the region B 5 from position X 15 to position X 16 in the first comparative example is broader in width than the region A 5 from the position X 5 to position X 6 in the present embodiment.

According to the first comparative embodiment, the recording unit only needs to be scanned by the distance ΔX 1 to record the entire region of the recording medium 106 in the X direction, so increase in the recording time and size of the recording device can be suppressed, the same as in the present embodiment. However, the present embodiment is further capable if suitably suppressing change in lightness in the X direction of black ink that has low lightness, as compared to the first comparative embodiment.

FIG. 11 is a diagram for describing change in lightness in a case where difference in discharge characteristics has occurred at one of the recording head 124 L and recording head 124 R, and that the amount of discharge from discharge orifice rows in the recording head 124 L has become greater than the amount of discharge from discharge orifice rows in the recording head 124 R. A case is illustrated here where the degree of difference in discharge characteristics occurring among the discharge orifice rows is around the same for each color. The horizontal axis represents the position on the recording medium and the vertical axis represents the relative lightness of images recorded by each of black ink and yellow ink. In the first comparative embodiment, the aforementioned relative lightness of an image is obtained by recording the entire region in the X direction by ink of a single color, calculating the difference in lightness between the image of ink of one color and the recording medium in each region, and obtaining the ratio in difference in lightness at each position as to an average of the difference in lightness.

FIG. 11 illustrates the relative lightness of images recorded by black ink using solid lines, and the relative lightness of images recorded by yellow ink using dashed lines. FIG. 11 also assumes a case where the generated recording data is such that the amount of discharge for both black ink and yellow ink would be the same regardless the position on the recording medium in the X direction, had there been no difference in discharge characteristics. Although the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink actually are different, FIG. 11 illustrates the relative lightness shifted in the lightness direction so that the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink agree, for the sake of simplifying description.

It can be seen from the comparison between change in lightness in the first comparative embodiment illustrated in FIG. 11 and change in lightness in the present embodiment illustrated in FIG. 8 that the relative lightness of the images recorded in the regions B 1 through B 6 is no different from the relative lightness of the images recorded in the regions A 1 through A 6 . However, the change in lightness of black ink in regions B 1 through B 3 is sharper than the change in lightness of black ink in regions A 1 through A 3 illustrated in FIG. 8 . The reason is that the region B 2 where shared recording is performed by the discharge orifice row 121 K and discharge orifice row 122 K according to the first comparative embodiment is narrower in width than the region A 2 where shared recording is performed by the discharge orifice row 111 K and discharge orifice row 112 K according to the present embodiment, as described above.

Specifically, in the first comparative embodiment, the distance between region B 3 where an image is recorded in the low relative lightness D_K 1 and B 3 where an image is recorded in the high relative lightness D_K 2 in the first comparative embodiment is shorter than the distance between region A 1 and region A 3 in the present embodiment, and also, the width of the region B 2 in the X direction where an image is recorded having relative lightness around the middle between D_K 1 and D_K 2 is shorter than the region A 2 . On the other hand, the relative lightness differences D_K 1 and D_K 2 are no different from those in the present embodiment. As a result, the change in lightness from regions B 1 to B 3 in the first comparative embodiment is sharper than the change in lightness from regions A 1 to A 3 in the present embodiment, and may be conspicuous.

As described above, change in lightness in the X direction of black ink of which the lightness is low can be made more gradual in the present embodiment, as compared to the first comparative embodiment. Consequently, this change in lightness can be made to be inconspicuous.

2. Second Comparative Embodiment

FIG. 12 is a diagram for describing the way in which recording is performed on the recording medium 106 using the recording unit 120 according to the second comparative embodiment. Of the two recording units 120 illustrated in FIG. 9 , the recording unit 120 situated at the left side in the X direction and drawn using dashed lines schematically illustrates the scan start position of the recording unit 120 when scanning the recording unit 120 from the left side toward the right side, while the recording unit 120 situated at the right side in the X direction and drawn using solid lines schematically illustrates the scan end position of the recording unit 120 .

The recording unit 120 according to the second comparative embodiment performs recording in which the recording unit 120 is scanned by a distance ΔX 2 that is longer than the distance ΔX 1 in the present embodiment and first comparative embodiment. This distance ΔX 2 is equivalent to the scanning distance of the recording unit 120 necessary to make the width in a region C 2 where shared recording is performed by the discharge orifice row 121 K and discharge orifice row 122 K the same length as the width of the region A 2 where the discharge orifice row 111 K and discharge orifice row 112 K perform shared recording. This point will be described later in detail.

Hereinafter, a position on the recording medium in the X direction that the discharge orifice row 122 K within the recording head 124 R faces at the scan start position of the recording unit 120 will be defined as position X 23 , and a position on the recording medium in the X direction that the discharge orifice row 122 Y within the recording head 124 R faces will be defined as position X 25 . Further, a position on the recording medium in the X direction that the discharge orifice row 121 K within the recording head 124 L faces at the scan end position of the recording unit 120 will be defined as position X 24 , and a position on the recording medium in the X direction that the discharge orifice row 121 Y within the recording head 124 L faces will be defined as position X 26 .

It can be seen from FIG. 12 that, in a case of scanning the recording unit 120 for the distance ΔX 2 , the discharge orifice row 122 K for black ink in the recording head 124 R cannot face a region on the recording medium 106 to the left side of the position X 23 in the X direction. Accordingly, black ink can only be discharged from the discharge orifice row 121 K in the recording head 124 L to region C 1 on the recording medium 106 from the edge position X 1 to the position X 23 . It can similarly be seen that the discharge orifice row 121 K for black ink in the recording head 124 L cannot face a region on the recording medium 106 to the right side of the position X 24 in the X direction. Accordingly, black ink can only be discharged from the discharge orifice row 122 K in the recording head 124 R to region C 3 on the recording medium 106 from the position X 24 to the edge position X 2 . Region C 2 on the recording medium 106 from positions X 23 to X 24 can be faced by both the discharge orifice row 121 K in the recording head 124 L and the discharge orifice row 122 K in the recording head 124 R while scanning the recording unit 120 over the distance ΔX 2 .

In the second comparative example, black ink is not discharged from the discharge orifice row 122 K as to the region C 1 on the recording medium 106 ; ink is discharged to the region C 1 only from the discharge orifice row 121 K. Also, black ink is not discharged from the discharge orifice row 121 K as to the region C 3 on the recording medium 106 ; ink is discharged to the region C 3 only from the discharge orifice row 122 K. Further, ink is discharged to the region C 2 on the recording medium 106 from both the discharge orifice row 121 K and the discharge orifice row 122 K.

On the other hand, in a case of scanning the recording unit 120 for the distance ΔX 2 , the discharge orifice row 122 Y for yellow ink in the recording head 124 R cannot face a region on the recording medium 106 to the left side of the position X 25 in the X direction. Accordingly, yellow ink can only be discharged from the discharge orifice row 121 Y in the recording head 124 L to the region C 4 on the recording medium 106 from the edge position X 1 to the position X 25 . It can similarly be seen that the discharge orifice row 121 Y for yellow ink in the recording head 124 L cannot face a region on the recording medium 106 to the right side of the position X 26 in the X direction. Accordingly, yellow ink can only be discharged from the discharge orifice row 122 Y in the recording head 124 R to the region C 6 on the recording medium 106 from the position X 26 to the edge position X 2 while scanning the distance ΔX 2 .

The region C 5 on the recording medium 106 from positions X 25 to X 26 can be faced by both the discharge orifice row 121 Y in the recording head 124 L and the discharge orifice row 122 Y in the recording head 124 R while scanning the recording unit 120 over the distance ΔX 2 . Accordingly, in the second comparative embodiment, yellow ink is not discharged from the discharge orifice row 122 Y as to the region C 4 on the recording medium 106 ; ink is discharged to the region C 4 only from the discharge orifice row 121 Y. Also, yellow ink is not discharged from the discharge orifice row 121 Y as to the region C 6 on the recording medium 106 ; ink is discharged to the region C 6 only from the discharge orifice row 122 Y. Further, ink is discharged to the region C 5 on the recording medium 106 from both the discharge orifice row 121 Y and the discharge orifice row 122 Y.

As described above, the recording unit 120 according to the second comparative embodiment performs recording in which the recording unit 120 is scanned by a distance ΔX 2 that is longer than the distance ΔX 1 in the present embodiment and first comparative embodiment, so that the width in the region C 2 where shared recording is performed by the discharge orifice row 121 K and discharge orifice row 122 K is the same length as the width of the region A 2 where the discharge orifice row 111 K and discharge orifice row 112 K perform shared recording. Accordingly, the width in the X direction of the region C 2 and region C 5 in the second comparative embodiment is longer than the width in the X direction of the region B 2 and region B 5 in the first comparative embodiment, and the width in the X direction of the region C 3 and region C 6 is shorter than the width in the X direction of the region B 3 and region B 6 . Change in lightness in the X direction of black ink of which lightness is low can be made to be inconspicuous in the second comparative embodiment, the same as in the present embodiment.

FIG. 13 is a diagram for describing change in lightness in a case where difference in discharge characteristics has occurred at one of the recording head 124 L and recording head 124 R, and that the amount of discharge from discharge orifice rows in the recording head 124 L has become greater than the amount of discharge from discharge orifice rows in the recording head 124 R. A case is illustrated here where the degree of difference in discharge characteristics occurring among the discharge orifice rows is around the same for each color. The horizontal axis represents the position on the recording medium and the vertical axis represents the relative lightness of images recorded by each of black ink and yellow ink. In the second comparative embodiment, the aforementioned relative lightness of an image is obtained by recording the entire region in the X direction by ink of a single color, calculating the difference in lightness between the image of ink of one color and the recording medium in each region, and obtaining the ratio in difference in lightness at each position as to an average of the difference in lightness.

FIG. 13 illustrates the relative lightness of images recorded by black ink using solid lines, and the relative lightness of images recorded by yellow ink using dashed lines. FIG. 13 also assumes a case where the generated recording data is such that the amount of discharge for both black ink and yellow ink would be the same regardless the position on the recording medium in the X direction, had there been no difference in discharge characteristics. Although the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink actually are different, FIG. 13 illustrates the relative lightness shifted in the lightness direction so that the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink agree, for the sake of simplifying description.

As described above, the width of the region C 2 in the X direction according to the second comparative embodiment has the same width as the region A 2 in the X direction according to the present embodiment. Accordingly, comparing the change in lightness of black ink in the second comparative embodiment illustrated in FIG. 13 with the change in lightness of black ink in the present embodiment illustrated in FIG. 8 shows that although the region where change in light ness occurs is shifted to the right in the X direction in the second comparative embodiment as compared to the present embodiment, the degree of change in lightness (the degree of steepness) is no different from that of the present embodiment. Accordingly, the change in lightness in the X direction of black ink of which lightness is low in the second comparative embodiment is gradual, and thus is inconspicuous.

However, the scanning distance of the recording unit 120 in the second comparative embodiment is ΔX 2 , which is longer than the ΔX 1 in the present embodiment, as described above. Accordingly, the amount of time till one scan ends can be made shorter with the present embodiment as compared to the second comparative embodiment, so the amount of time needed to complete recording can be reduced. Further, the width by which the right side of the recording unit 120 runs past the position facing the recording medium 106 at the scan end position is longer in the second comparative embodiment than in the present embodiment, which can be seen by comparing FIGS. 7 and 12 . Accordingly, the movable region of the recording unit 120 in the X direction within the recording device can be made smaller in the present embodiment as compared to the second comparative embodiment, so the size of the recording device can be reduced. Thus, according to the present embodiment, change in lightness of ink with low lightness can be made inconspicuous, while suppressing increase in the recording time and size of the recording device, as described above.

Second Embodiment

An arrangement has been described in the first embodiment above, where the distance between discharge orifice rows for color ink, i.e., discharge orifice rows for cyan ink, magenta ink, and yellow ink, is the same. An arrangement will be described in a second embodiment where the distance between discharge orifice rows is changed regarding the discharge orifice rows discharging color ink as well, in accordance with the difference in lightness as to the surface of the recording medium. Description of portions that are the same as in the above-described first embodiment will be omitted.

There is difference in lightness in color ink besides black ink as well, as illustrated in FIG. 5 . Specifically, of the color inks used in the present embodiment, cyan ink has the greatest lightness difference as to the recording medium, and yellow ink has the smallest lightness difference as to the recording medium. Accordingly, when considering the degree of conspicuousness in the X direction including black ink, it can be seen that this is most conspicuous in the black ink, and less conspicuous in the order of cyan ink, magenta ink, and yellow ink. In light of the above, the discharge orifice rows are arrayed within the recording heads such that the lower the lightness of the ink is, the shorter the distance between the discharge orifice rows discharging that ink is.

FIG. 14 is a diagram illustrating a recording unit 130 used in the present embodiment in detail, schematically illustrating the recording unit 130 from below in the vertical direction. The recording head 134 L and the recording head 134 R in the recording unit 130 according to the present embodiment are separated by a distance W 5 in the X direction. The recording head 134 L has four discharge orifice rows 131 C, 131 M, 131 Y, and 131 K, in the order of discharge orifice row 131 K that discharges black ink, discharge orifice row 131 C that discharges cyan ink, discharge orifice row 131 M that discharges magenta ink, and discharge orifice row 131 Y that discharges yellow ink, from the right side in the X direction. On the other hand, the recording head 134 R has four discharge orifice rows 132 C, 132 M, 132 Y, and 132 K, in the order of discharge orifice row 132 C that discharges cyan ink, discharge orifice row 132 M that discharges magenta ink, discharge orifice row 132 Y that discharges yellow ink, and discharge orifice row 132 K that discharges black ink, from the right side in the X direction. The four discharge orifice rows 131 C, 131 M, 131 Y, and 131 K in the recording head 134 L are laid out separated from each other by a same distance d. In the same way, the four discharge orifice rows 132 C, 132 M, 132 Y, and 132 K in the recording head 134 R are laid out separated from each other by the same distance d.

Now, the distance in the X direction between the two discharge orifice rows that discharge ink of each color according to the present embodiment will be described in the same way as with the first embodiment. First, with regard to the cyan ink, the discharge orifice row 131 C is situated the second from the right side in the X direction within the recording head 134 L, and the discharge orifice row 132 C is situated the second from the left side in the X direction within the recording head 124 R. Accordingly, distance W_C 3 in the X direction between the discharge orifice row 131 C and discharge orifice row 132 C is a distance that can be calculated by Expression (3-1).

W _ C 3= W 5+1× d+ 1× d=W 5+2 d   Expression (3-1)

Next, with regard to the magenta ink, the discharge orifice row 131 M is situated the third from the right side in the X direction within the recording head 134 L, and the discharge orifice row 132 M is situated the third from the left side in the X direction within the recording head 134 R. Accordingly, distance W_M 3 in the X direction between the discharge orifice row 131 M and discharge orifice row 132 M is a distance that can be calculated by Expression (3-2).

W _ M 3= W 5+2× d+ 2× d=W 5+4 d   Expression (3-2)

Also, with regard to the yellow ink, the discharge orifice row 131 Y is situated the fourth from the right side in the X direction within the recording head 134 L, and the discharge orifice row 132 Y is situated the fourth from the left side in the X direction within the recording head 134 R. Accordingly, distance W_Y 3 in the X direction between the discharge orifice row 131 Y and discharge orifice row 132 Y is a distance that can be calculated by Expression (3-3).

W _ Y 3= W 5+3× d+ 3× d=W 5+6 d   Expression (3-3)

Further, with regard to the black ink, the discharge orifice row 131 K is situated the first from the right side in the X direction within the recording head 134 L, and the discharge orifice row 132 K is situated the first from the left side in the X direction within the recording head 134 R. Accordingly, distance W_K 3 in the X direction between the discharge orifice row 131 K and discharge orifice row 132 K is a distance that can be calculated by Expression (3-4).

W _ K 3= W 5+0× d+ 0× d=W 5  Expression (3-4)

It can thus be seen from Expressions (3-1), (3-2), (3-3), and (3-4), that the discharge orifice rows corresponding to ink of each color are arranged such that the distances between the discharge orifice rows corresponding to the respective colors are shorter in the order of distance W_Y 3 between the discharge orifice rows 131 Y and 132 Y discharging yellow ink (W 5 +6d), distance W_M 3 between the discharge orifice rows 131 M and 132 M discharging magenta ink (W 5 +4d), distance W_C 3 between the discharge orifice rows 131 C and 132 C discharging cyan ink (W 5 +2d), and distance W_K 3 between the discharge orifice rows 131 K and 132 K discharging black ink (W 5 ). That is to say, the discharge orifice rows corresponding to the respective colors are arrayed such that the lower the lightness of the ink is, the shorter the distance between the discharge orifice rows discharging that ink is.

FIG. 15 is a diagram for describing the way in which recording is performed on the recording medium 106 using the recording unit 130 according to the present embodiment. Of the two recording units 130 illustrated in FIG. 15 , the recording unit 130 situated at the left side in the X direction and drawn using dashed lines schematically illustrates the scan start position of the recording unit 130 when scanning the recording unit 130 from the left side toward the right side, while the recording unit 130 situated at the right side in the X direction and drawn using solid lines schematically illustrates the scan end position of the recording unit 130 .

The recording unit 130 according to the present embodiment is scanned over a range from where the discharge orifice row situated at the right edge portion of the recording head 134 L in the X direction is at a position facing an edge position X 1 , to where the discharge orifice row situated at the left edge portion of the recording head 134 R in the X direction is at a position facing an edge position X 2 , in the same way as in the first embodiment. The recording unit 130 according to the present embodiment is scanned by a distance ΔX 1 , in the same way as in the first embodiment.

Hereinafter, positions on the recording medium in the X direction that the discharge orifice row 132 K, the discharge orifice row 132 C, the discharge orifice row 132 M, and the discharge orifice row 132 Y, within the recording head 134 R face at the scan start position of the recording unit 130 will be defined as position X 33 , position X 35 , position X 37 , and position X 39 , respectively. Also, positions on the recording medium in the X direction that the discharge orifice row 131 K, the discharge orifice row 131 C, the discharge orifice row 131 M, and the discharge orifice row 131 Y, within the recording head 134 L face at the scan end position of the recording unit 130 will be defined as position X 34 , position X 36 , position X 38 , and position X 40 , respectively.

In the same way as with the first embodiment, black ink is not discharged from the discharge orifice row 132 K as to the region D 1 on the recording medium 106 from the edge position X 1 to position X 33 ; ink is discharged to the region D 1 only from the discharge orifice row 131 K. Also, black ink is not discharged from the discharge orifice row 131 K as to the region D 3 on the recording medium 106 from the position X 34 to the edge position X 2 ; ink is discharged to the region D 3 only from the discharge orifice row 132 K. Further, black ink is discharged from both the discharge orifice row 131 K and discharge orifice row 132 K to the region D 2 on the recording medium from position X 33 to X 34 .

Next, regarding yellow ink, yellow ink is not discharged from the discharge orifice row 132 Y as to the region D 4 on the recording medium 106 from the edge position X 1 to position X 39 ; ink is discharged to the region D 4 only from the discharge orifice row 131 Y. Also, yellow ink is not discharged from the discharge orifice row 131 Y as to the region D 6 on the recording medium 106 from the position X 40 to the edge position X 2 ; ink is discharged to the region D 6 only from the discharge orifice row 132 Y. Further, yellow ink is discharged from both the discharge orifice row 131 Y and discharge orifice row 132 Y to the region D 5 on the recording medium from position X 39 to X 40 .

Next, regarding magenta ink, magenta ink is not discharged from the discharge orifice row 132 M as to the region D 7 on the recording medium 106 from the edge position X 1 to position X 37 ; ink is discharged to the region D 7 only from the discharge orifice row 131 M. Also, magenta ink is not discharged from the discharge orifice row 131 M as to the region D 9 on the recording medium 106 from the position X 38 to the edge position X 2 ; ink is discharged to the region D 9 only from the discharge orifice row 132 M. Further, magenta ink is discharged from both the discharge orifice row 131 M and discharge orifice row 132 M to the region D 8 on the recording medium from position X 37 to X 38 .

Next, regarding cyan ink, cyan ink is not discharged from the discharge orifice row 132 C as to the region D 10 on the recording medium 106 from the edge position X 1 to position X 35 ; ink is discharged to the region D 10 only from the discharge orifice row 131 C. Also, cyan ink is not discharged from the discharge orifice row 131 C as to the region D 12 on the recording medium 106 from the position X 36 to the edge position X 2 ; ink is discharged to the region D 12 only from the discharge orifice row 132 C. Further, cyan ink is discharged from both the discharge orifice row 131 C and discharge orifice row 132 C to the region D 11 on the recording medium from position X 35 to X 36 .

Thinking in the same was as with the first embodiment, the widths of the regions where shared recording is performed by two discharge orifice rows in cases in the order of region D 5 for yellow ink, region D 8 for magenta ink, region D 11 for cyan ink, and region D 2 for black ink. That is to say, the lower the lightness is, the longer the width is in the X direction of the region where shared recording is performed. Thus, change in lightness, which is more conspicuous the lower the lightness of the ink is, can be suitably suppressed for each ink.

Third Embodiment

An arrangement has been described in the above first and second embodiments where, regardless of the position in the region A 2 in the X direction, quantization data is distributed to the two discharge orifice rows in the left-right head distribution processing, such that the distribution ratio of quantization data to the discharge orifice row within the recording head at the left side and the distribution ratio of quantization data to the discharge orifice row within the recording head at the right side in the recording unit are equal. As opposed to this, an arrangement will be described in a third embodiment where quantization data is distributed to the two discharge orifice rows such that the distribution ratio of quantization data to the discharge orifice row within the recording head at the left side and the distribution ratio of quantization data to the discharge orifice row within the recording head at the right side differ, in accordance with the position in the region A 2 in the X direction. Description of portions that are the same as in the above-described first and second embodiments will be omitted.

In a case of using the distribution patterns illustrated in FIGS. 4A and 4B , the change in lightness is gradual when viewed over the entire region of the recording medium in the X direction as illustrated in FIG. 8 , but the change in lightness may be steep locally, such as at the boundary between region A 1 and region A 2 , between region A 2 and region A 3 , and so forth, which are adjacent to each other.

Although black ink is discharged to region A 1 using the discharge orifice row 111 K alone (distribution ratio to the discharge orifice row 111 K is 100%), but at the instant of switching from region A 1 to region A 2 in the distribution patterns illustrated in FIGS. 4A and 4B , the distribution ratio to the discharge orifice row 111 K is 50%. Further, the distribution ratio to the discharge orifice row 111 K in region A 2 is constantly 50%, and at the instant of switching from region A 2 to region A 3 , no black ink is discharged from the discharge orifice row 111 K (distribution ratio to the discharge orifice row 111 K is 0%).

Conversely, the distribution patterns used for left-right recording head distribution processing in step S 804 in the present embodiment is different from that in the first embodiment. Accordingly, occurrence of locally steep change in lightness due to discharge properties among discharge orifice rows can be suppressed, in addition to the advantages of the first embodiment.

FIGS. 16A and 16B are schematic diagrams illustrating an example of distribution patterns used in the left-right head distribution in step S 804 in the present embodiment. FIG. 16A corresponds to a certain color, and is a diagram schematically illustrating a distribution pattern for distributing quantization data corresponding to an image at the middle region of the recording medium in the X direction, where shared recording is performed by two discharge orifice rows provided to the recording heads 102 L and 102 R, to the discharge orifice row provided to the recording head 102 L. FIG. 16B is a diagram schematically illustrating a distribution pattern for distributing this quantization data to the discharge orifice row provided to the recording head 102 R. Note that these distribution patterns are stored in the ROM 313 beforehand.

In the same way as in the first embodiment, description will be made assuming that the region at the middle in the X direction where shared recording is performed is a region that has a size of 14 pixels in the X direction, for the sake of simplicity. For example, in a case of considering distribution processing at discharge orifice rows 111 K and 112 K discharging black ink, description will be made assuming that the width of the region A 2 in the X direction in FIG. 7 has a width of 14 pixels. Note however, that the width of the region A 2 in the X direction is not restricted to a size of 14 pixels, and any distribution patterns may be used as long as later-described conditions are satisfied. This is the same for discharge orifice row for other color inks, such as the discharge orifice rows 111 Y and 112 Y that discharge yellow ink for example, and advantages of the present embodiment can be yielded as long as the distribution patterns satisfy later-described conditions.

The distribution patterns illustrated in FIGS. 16A and 16B are configured with an 8-pixel size in the Y direction as a repetition unit, and the left-right head distribution processing is completed as to the entirety of the region where shared recording is to be performed, by repeatedly using these distribution patterns in the Y direction. In the distribution patterns illustrated in FIGS. 16A and 16B , the black pixels indicate pixels regarding which discharging of ink is permitted in a case where ink discharge is set by the quantization data. On the other hand, the white pixels indicate pixels regarding which discharging of ink is not permitted, even in a case where ink discharge is set by the quantization data.

It can be seen from FIGS. 16A and 16B that the distribution pattern corresponding to the discharge orifice row provided to the recording head 102 L used in the present embodiment, and the distribution pattern corresponding to the discharge orifice row provided to the recording head 102 R have ink discharge permitted at mutually exclusive and complementary positions. Accordingly, left-right head distribution processing can be performed so that in a case where quantization data instructing discharge of ink to all pixels is acquired as the quantization data corresponding to the region where shared recording is to be performed, for example, ink is discharged just once, from either one or the other of a discharge orifice row in the recording head 102 L and a discharge orifice row in the recording head 102 R, at all pixels within this region, the same as in the first embodiment.

Further, it can be seen from FIGS. 16A and 16B that the discharge pattern corresponding to the discharge orifice row in the recording head 102 L and the discharge pattern corresponding to the discharge orifice row in the recording head 102 R, used in the present embodiment, have a different number of pixels regarding which discharge of ink is permitted, in accordance with the position in the X direction on the recording medium. Specifically, in the distribution pattern corresponding to the discharge orifice row in the recording head 102 L illustrated in FIG. 16A , permission/non-permission is set such that of the number of pixels regarding which discharge of ink is permitted gradationally decreases from the left side in the X direction toward the right side. On the other hand, in the distribution pattern corresponding to the discharge orifice row in the recording head 102 R illustrated in FIG. 16B , permission/non-permission is set such that of the number of pixels regarding which discharge of ink is permitted gradationally increases from the left side in the X direction toward the right side.

By using the distribution patterns illustrated in FIGS. 16A and 16B , the distribution ratio of quantization data to the discharge orifice row in the recording head 102 L gradationally decreases in the region where shared recording is performed, from the left side in the X direction in that region toward the right side, from 100% to 0%. Also, the distribution ratio of quantization data to the discharge orifice row in the recording head 102 R gradationally increases from 0% to 100%. Even in a region where shared recording is performed, the total of the distribution ratio of the recording head 102 L and the distribution ratio of the recording head 102 R is always 100% at any position in the X direction.

FIG. 17 is a diagram for describing change in lightness in a case where difference in discharge characteristics has occurred at one of the recording head 102 L and recording head 102 R, and that the amount of discharge from discharge orifice rows in the recording head 102 L has become greater than the amount of discharge from discharge orifice rows in the recording head 102 R, when using the distribution patterns illustrated in FIGS. 16A and 16B . A case is illustrated here where the degree of difference in discharge characteristics occurring among the discharge orifice rows is around the same for each color. The horizontal axis represents the position on the recording medium and the vertical axis represents the relative lightness of images recorded by each of black ink and yellow ink. Here, the aforementioned relative lightness of an image is obtained by recording the entire region in the X direction by ink of a single color, calculating the difference in lightness between the image of ink of one color and the recording medium in each region, and obtaining the ratio in difference in lightness at each position as to an average of the difference in lightness.

FIG. 17 illustrates the relative lightness of images recorded by black ink using solid lines, and the relative lightness of images recorded by yellow ink using dashed lines. FIG. 17 also assumes a case where the generated recording data is such that the amount of discharge for both black ink and yellow ink would be the same regardless the position on the recording medium in the X direction, had there been no difference in discharge characteristics. Although the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink actually are different, FIG. 17 illustrates the relative lightness shifted in the lightness direction so that the average in difference in lightness for the black ink and the average in difference in lightness for the yellow ink agree, for the sake of simplifying description.

The relative lightness of the image recorded in the region A 1 by the black ink is a relatively low value D_K 1 , the same as in the first embodiment. The relative lightness of the image recorded in the region A 3 by the black ink is a relatively high value D_K 2 . The relative lightness in the region A 2 gradationally increases from D_K 1 to D_K 2 , from the left side in the X direction to the right side accordingly. The reason is that by using the distribution patterns illustrated in FIGS. 16A and 16B , the distribution ratio to the discharge orifice row 111 K within the recording head 102 L gradationally decreases from the left side in the X direction to the right side accordingly, while the distribution ratio to the discharge orifice row 112 K within the recording head 102 R gradationally increases, as described above.

For example, the distribution ratio to the discharge orifice row 112 K near the region A 1 in the region A 2 in the X direction is small, and the distribution ratio to the discharge orifice row 111 K is great. Accordingly, more ink is discharged from the discharge orifice row 111 K to the image recorded by black ink in this region, so the effects of discharge characteristics of the discharge orifice row 111 K are dominant. Accordingly, the relative lightness near region A 1 in the region A 2 in the X direction is a value close to that of D_K 1 .

It can be seen from FIG. 17 that the width of the region A 2 in the X direction where shared recording is performed by black ink can be made longer than the width of the region A 5 in the X direction where shared recorded is performed by yellow ink in the present embodiment, the same as in the first embodiment. Further, the relative lightness of the black ink in the region A 2 can be gradationally changed from D_K 1 to D_K 2 from the left side in the X direction to the right side in the present embodiment, as described above. This enables sudden local change in lightness to be suppressed, even at the boundary between region A 1 and region A 2 , and region A 2 and region A 3 .

Other Embodiments

Embodiment(s) of the disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)), a flash memory device, a memory card, and the like. Although a case of using cyan ink, magenta ink, yellow ink, and black ink has been described in the above embodiments, this is not restricted to using inks of different colors. Advantages of the embodiments can be yielded in a case of using multiple types of ink that differ from each other in lightness. For example, in a case where the composition of a first black ink and a second black ink differ, and the lightness of the second black ink is higher than the first black ink, the distance between discharge orifice rows that discharge the first black ink can be made shorter than the distance between discharge orifice rows that discharge the second black ink.

Description has been made in the embodiments above regarding a case of using cyan ink, magenta ink, yellow ink, and black ink, including dye as a color material. However, ink containing pigment may be used as well.

Although description has been made in the above embodiments regarding a recording unit where the left recording head and right recording head are disposed separated by a certain distance, it is preferable that this separation distance (W 5 ) is longer than the distance d between discharge orifice rows in the recording heads. Since the longer the distance between recording heads is, the more the recording time can be reduced, so the recording heads are preferably separated in practice by a distance that yields a desired recording time.

Although an arrangement has been described in the above embodiments where one discharge orifice row is configured by a single row of multiple discharge orifices that discharge ink of the same color being arrayed in the Y direction, other arrangements may be made as well. For example, an arrangement may be made where one discharge orifice row is configured by two rows of multiple discharge orifices that discharge ink of the same color being arrayed in the Y direction, with the two rows being positionally staggered in the X direction such that the discharge orifices of one row can discharge ink between discharge orifices of the other row. In this case, the above-described distance between the discharge orifice rows can be based on the center position in the X direction between the two rows making up each discharge orifice row.

Although description has been made in the above embodiments regarding a recording unit made up of two different recording heads and a holding part holding the recording head, other arrangements may be made. That is to say, advantages the same as those of the embodiments can be yielded by an arrangement using a recording unit having a first recording part and a second recording part each having discharge orifice rows discharging two types of ink having different lightness, with the first and second recording parts being disposed with a certain distance therebetween in the X direction. For example, advantages the same as those of the embodiments can be yielded by an arrangement using a recording unit that does not have a holding part and the first recording unit and second recording unit are provided within a single recording head.

According to the recording device of the disclosure, change in lightness can be made inconspicuous even in cases where there is change in the amount of discharge differs among recording parts due to difference in discharge characteristics, without making the scanning range of the recording unit longer.

While the disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2016-120098 filed Jun. 16, 2016, which is hereby incorporated by reference herein in its entirety.