Medium transport apparatus, medium feeder, and image formation system

This application claims priority based on 35 USC 119 from prior Japanese patent application no. 2016-169284 filed on Aug. 31, 2016, the entire contents of which are incorporated herein by reference.

The disclosure relates to an image formation system which forms an image on a medium, and a medium transport apparatus and a medium feeder which are installed in the image formation system.

Some of image formation apparatuses, such as copiers, printers and facsimile machines, are designed such that an external medium feeder is attachable to them. An external medium feeder is attached to an attachment section of an image formation apparatus before print operation (see Patent Document 1: U.S. Pat. No. 8,490,964, for example).

An operation of attaching the medium feeder to the image formation apparatus is desired to be done smoothly while avoiding their collision.

To this end, there are demands for: a medium feeder smoothly attachable to an image formation apparatus; an image formation system including such a medium feeder; and a medium transport apparatus suitable for the medium feeder and the image formation system.

A medium transport apparatus in one or more embodiments may include: a frame; a table including a placement surface on which a medium is placed, a first end portion, and a second end portion, the table extending from the first end portion to the second end portion and being rotatable about a first shaft portion parallel to the placement surface; a first rotor arranged adjacent to the first end portion of the table; a second rotor arranged adjacent to the second end portion of the table; a belt that is stretched by the first rotor and the second rotor, and is configured to rotate circularly and to transport the medium in a first direction from the first end portion toward the second end portion; and a biasing part that links the frame and an attachment part provided between the second end portion and the first end portion of the table, and that biases the table.

A medium feeder in one or more embodiments may include: a medium separator including a stacker that holds media as stacked one on another, and a separation part that separates the media one by one, and a medium transport apparatus that transports a medium separated from the media by the medium separator. The medium transport apparatus includes: a frame; a table including a placement surface on which the medium is placed, a first end portion and a second end portion, the table extending from the first end portion to the second portion and being rotatable about a first shaft portion parallel to the placement surface; a first rotor arranged adjacent to the first end portion of the table; a second rotor arranged adjacent to the second end portion of the table; a belt that is stretched by the first rotor and the second rotor, and is configured to rotate circularly and to transport the medium in a first direction from the first end portion toward the second end portion; and a biasing part that links the frame and an attachment part between the second end portion and the first end portion of the table, and that biases the table. In addition, an image formation system in one or more embodiments may include: a medium feeder; and an image formation apparatus. The medium feeder includes: a medium separator includes: a stacker that holds media as stacked one on another, and a separation part that separates a medium from the media on a one-by-one basis, and a medium transport apparatus that transports the medium separated from the media by the medium separator, and the medium transport apparatus includes: a frame, a table including a placement surface on which the medium is placed, a first end portion and a second end portion, the table extending from the first end portion to the second portion and being rotatable about a first shaft portion parallel to the placement surface, a first rotor arranged adjacent to the first end portion of the table, a second rotor arranged adjacent to the second end portion of the table, a belt that is stretched by the first rotor and the second rotor, and is configured to rotate circularly and to transport the medium in a first direction from the first end portion toward the second end portion, and a biasing part that links the frame and an attachment part located between the second end portion and the first end portion in the table and which biases the table.

In the medium transport apparatus, the medium feeder and the image formation system as one or more embodiments may include the biasing part which biases part of the table upward. Accordingly, even in a case where the table is bulky in size and weight, the table can be attached to an attached part of the image formation apparatus relatively easily while avoiding the table's unnecessary collision with surroundings.

The medium transport apparatus and the medium feeder as one or more embodiments can be smoothly attached to the image formation apparatus. In addition, the image formation apparatus as one or more embodiments enables such a medium transport apparatus and such a medium feeder to be smoothly attached to the image formation apparatus.

FIG. 1 is a schematic view illustrating an example of an overall configuration of an image formation system according to one or more embodiments.

FIG. 2 is a front view illustrating an outer appearance of the image formation system illustrated in FIG. 1 .

FIG. 3 is a perspective view illustrating an outer appearance of a medium feeder illustrated in FIG. 1 .

FIG. 4 is a perspective view illustrating an outer appearance of an image formation apparatus illustrated in FIG. 1 .

FIG. 5 is a magnified schematic view illustrating the medium feeder illustrated in FIG. 1 .

FIG. 6 is a magnified perspective view illustrating an attached part of the image formation apparatus illustrated in FIG. 4 .

FIG. 7 is a schematic cross-sectional view illustrating a structure of the attached part of the image formation apparatus illustrated in FIG. 4 .

FIG. 8 is a schematic cross-sectional view illustrating how a medium transport apparatus is attached to the attached part of the image formation apparatus illustrated in FIG. 4 .

FIG. 9 is a first cross-sectional view illustrating how to attach the medium transport apparatus to the image formation apparatus in the image formation system illustrated in FIG. 1 .

FIG. 10 is a second cross-sectional view illustrating how to attach the medium transport apparatus to the image formation apparatus in the image formation system illustrated in FIG. 1 .

FIG. 11 is a third cross-sectional view illustrating how to attach the medium transport apparatus to the image formation apparatus in the image formation system illustrated in FIG. 1 .

Embodiments of the invention are hereinbelow explained in detail with reference to drawings. Incidentally, the following explanations are provided for one specific example of the invention. The invention is not limited to the below-explained aspects. In addition, the invention is not limited by arrangements, dimensions, dimensional ratios and the like of the components illustrated in the drawings. The explanations are provided in the following sequence.

1. One embodiment (Medium Transport Apparatus, as well as Medium Feeder and Image Formation System in which Medium Transport Apparatus is Installed) 1.1 Overall Configuration of Image Formation System 1.2 Detailed Configuration of Medium Feeder 1.3 Detailed Configuration of Image Formation Apparatus 1.4 Working/Effects of Image Formation System 2. Modifications

1. One Embodiment

[1.1 Overall Configuration of Image Formation System]

FIG. 1 is a schematic view illustrating an example of an overall configuration of an image formation system according to one or more embodiments. FIG. 2 is a front view illustrating an outer appearance of the image formation system. The image formation system corresponds to a specific example of the “image formation system” in one or more embodiments, and includes medium feeder S 1 and image formation apparatus S 2 . FIG. 3 is a perspective view illustrating an example of an overall configuration of medium feeder S 1 illustrated in FIGS. 1 and 2 . FIG. 4 is a perspective view illustrating an example of an overall configuration of image formation apparatus S 2 . Medium feeder S 1 corresponds to a specific example of the “medium feeder” in one or more embodiments, and includes medium separator S 11 , medium transport apparatus S 12 , controller SS 1 , and drive motor S 1 M. Medium separator S 11 and medium transport apparatus S 12 share common frame 2015 . In medium feeder S 1 , frame 2015 is vertically movably provided to pedestal 2018 with casters 2017 via stand section 2016 . Since medium feeder S 1 is provided with casters 2017 , medium feeder S 1 is horizontally movable on the floor. Medium separator S 11 includes: stacker 2020 which holds media PM 1 as stacked one on another; and separation part 10 ( FIG. 10 ) which separates media PM 1 on a one-by-one basis. Medium transport apparatus S 12 is located downstream of medium separator S 11 , and transports media PM 1 , after separated by medium separator S 11 , to image formation apparatus S 2 which is located downstream of medium transport apparatus S 12 . Incidentally, in this specification, an arbitrary position is used as a reference; a direction from the arbitrary position toward stacker 2020 and a position closer to stacker 2020 than the arbitrary position is are referred to as upstream or rearward; and a direction of becoming farther from stacker 2020 than from the arbitrary position and a position farther from stacker 2020 than from the arbitrary position are referred to as downstream or frontward. In the image formation system, stacker 2020 is located in the most upstream position. Image formation apparatus S 2 includes housing K. A side surface of housing K is provided with opening 650 of attached part 600 . Medium transport apparatus S 12 is attached to attached part 600 with a distal end portion of medium transport apparatus S 12 inserted into opening 650 . In addition, controller SS 1 controls the entirety of medium feeder S 1 in cooperation with controller SS 2 (described later) of image formation apparatus S 2 . Based on an instruction from controller SS 1 , drive motor S 1 M functions as a drive source for later-described feed transport section 2010 and medium transport apparatus S 12 .

[1.2 Detailed Configuration of Medium Feeder S 1 ]

FIG. 5 is a magnified front view illustrating a main part of medium feeder S 1 . Incidentally, in this specification, a transport direction of transport of media PM 1 is referred to as an X-axis direction. Furthermore, a width direction of media PM 1 which is orthogonal to the X-axis direction is referred to as a Z-axis direction, and a direction orthogonal to the main surfaces of media PM 1 is referred to as a Y-axis direction.

Medium separator S 11 includes bridge 2005 in addition to stacker 2020 and separation part 10 , which are discussed above. Stacker 2020 and separation part 10 are adjacently arranged with bridge 2005 interposed in between. Stacker 2020 and separation part 10 are attached to bridge 2005 .

(Configuration of Stacker 2020 )

Stacker 2020 , for example, includes: bottom plate 2020 S which supports stacked media PM 1 from below; stack guide 2021 which guides the rear ends of stacked media PM 1 ; and set guides 2022 which guides the side ends of media PM 1 .

(Configuration of Separation Part 10 )

Separation part 10 includes separation section 2001 and feed transport section 2010 .

(Separation Section 2001 )

Separation section 2001 includes separation frame 2002 , separator 2003 , knob 2004 , separator frame 2006 and support 2025 . Separation frame 2002 is fixed to bridge 2005 with the assistance of connector 2024 , and holds support 2025 movable in the Y-axis direction. As illustrated in FIG. 5 , knob 2004 is held by separation frame 2002 so as to be rotatable about axis J 4 in +R 4 and −R 4 directions, and functions as an operation part which operates the movement of support 2025 in the Y-axis direction. Support 2025 is a member extending in the Y-axis direction. Support 2025 , for example, moves in the +Y direction in response to the turn of knob 2004 in the +R direction, and moves in the −Y direction in response to the turn of knob 2004 in the −R direction. When support 2025 moves in the +Y direction, part or all of support 2025 enters into separation frame 2002 . Meanwhile, when support 2025 moves in the −Y direction, part or all of support 2025 , which has been inside separation frame 2002 , comes out of separation frame 2002 (in a direction opposite to knob 2004 ). Separator frame 2006 is connected to a distal end of support 2025 , that is, an opposite end portion of support 2025 from separation frame 2002 . Separator 2003 is provided to an opposite side of separator frame 2006 from support 2025 . Separator 2003 is provided facing feed transport section 2010 , and includes a contact surface which comes into contact with media PM 1 when medium separator S 11 performs a medium separation operation. This configuration makes support 2025 , separator frame 2006 and separator 2003 integrally movable in the +Y or −Y direction in response to the turn of knob 2004 . Incidentally, in the embodiment, the +Y direction is referred to as an upward direction, and the −Y direction is referred to as a downward direction, in some cases. Separator 2003 does not come into direct or indirect contact with a surface of feed belt 2011 , and is displaceable such that a height position (Y-axis direction position) of the contact surface of separator 2003 is located lower than a height position of the surface of feed belt 2011 .

(Feed Transport Section 2010 )

Feed transport section 2010 is located lower than stacker 2020 and separation section 2001 , and includes, for example, feed belt 2011 , medium sensor 2012 , drive roller 2013 and stretch roller 2014 . Feed belt 2011 is an endless belt member stretched by drive roller 2013 and stretch roller 2014 which both extend in the Z-axis direction. Drive force is transmitted to drive roller 2013 from drive motor S 1 M which drives under the control of controller SS 1 , and thus, drive roller 2013 rotationally drives in an arrow R 13 direction ( FIG. 5 ). The rotation of drive roller 2013 makes feed belt 2011 circularly rotate in a direction indicated with arrow R 11 . Frictional force between stretch roller 2014 and feed belt 2011 makes stretch roller 2014 rotate in response to feed belt 2011 . Medium sensor 2012 ( FIG. 1 ) detects whether media PM 1 are stacked on stacker 2020 .

(Configuration of Bridge 2005 )

Moreover, bridge 2005 includes: load guide 2027 which comes into contact with front end surfaces of media PM 1 (see FIG. 1 ) stacked on stacker 2020 ; and preliminary movement guide 2026 located lower than load guide 2027 . Load guide 2027 includes, for example, a flat surface extending in the Y-axis direction, while preliminary movement guide 2026 includes a curve surface which becomes gradually closer to separation section 2001 . Preliminary movement guide 2026 functions to make media PM 1 advance slightly further in the +X direction (downstream direction) as media PM 1 advances further downward (becomes closer to feed belt 2011 ).

(Configuration of Medium Transport Apparatus S 12 )

As illustrated in FIGS. 3 and 5 , medium transport apparatus S 12 includes, for example, transport belt 2031 , drive roller 2032 , transport table 2033 , transport rollers 2034 , medium sensors 2035 , 2036 ( FIG. 1 ), stretch roller 2037 and transport roller frame 2039 , in addition to frame 2015 .

Transport table 2033 is a member on which media PM 1 are placed after separated by medium separator S 11 , and which guides thus-placed media PM 1 to image formation apparatus S 2 . Transport table 2033 is a flat plate-shaped member which, for example, includes: placement surface 33 S extending on the X-Z plane; end portion 33 T 1 located upstream: and end portion 33 T 2 located downstream. Transport table 2033 is provided turnable about shaft portion J 1 ( FIG. 5 ) which is parallel to placement surface 33 S, for example, in an arrow R 1 direction ( FIG. 5 ). Shaft portion J 1 is a specific example corresponding to a “first shaft portion” in one or more embodiments. For example, the two ends of shaft portion J 1 is fixed to frame 2015 .

Drive roller 2032 is a rotor arranged adjacent to, near, or close to end portion 33 T 1 of transport table 2033 , and is a specific example corresponding to a “first rotor” in one or more embodiments. Drive force is transmitted to drive roller 2032 from drive motor S 1 M which drives under the control of controller SS 1 , and thus, drive roller 2032 rotationally drives about shaft portion J 1 , which extends in the Z-axis direction, in an arrow R 32 direction ( FIG. 5 ).

Stretch roller 2037 is a rotor arranged adjacent to, near, or close to end portion 33 T 2 of transport table 2033 , and is a specific example corresponding to a “second rotor” in one or more embodiments. Stretch roller 2037 is located in a distal end portion of medium transport apparatus S 12 . When medium transport apparatus S 12 is attached to attached part 600 , stretch roller 2037 is inserted into opening 650 of attached part 600 .

Transport belt 2031 is an endless belt member stretched by drive roller 2032 and stretch roller 2037 so as to surround part of transport table 2033 or pass above placement surface 33 S. Rotation of drive roller 2032 circularly rotates transport belt 2031 in a direction indicated with arrow R 31 ( FIG. 5 ). Thus, transport belt 2031 transports media PM 1 in the +X direction from the upstream to the downstream. Incidentally, frictional force between stretch roller 2037 and transport belt 2031 makes stretch roller 2037 rotate in response to transport belt 2031 .

Furthermore, transport rollers 2034 are rotors which rotate, for example, about their axes each extending in the Z-axis direction, and are provided along the transport direction of media PM 1 (X-axis direction) while facing transport belt 2031 and transport table 2033 . Transport rollers 2034 rotate in response to the circular rotation of transport belt 2031 with medium PM 1 held between transport rollers 2034 and transport belt 2031 . Thereby, transport rollers 2034 transport medium PM 1 to image formation apparatus S 2 . Transport roller frame 2039 holds respective transport rollers 2034 rotatable. Frame 2015 holds transport roller frame 2039 movable. Endmost transport roller 2034 , which is the closest to end portion 33 T 2 , is movable to be away from transport belt 2031 (or placement surface 33 S). More specifically, for example, frame 2015 holds transport roller frame 2039 so that transport roller frame 2039 can turn in an arrow R 39 direction about rotational shaft J 39 provided to a rear end portion of transport roller frame 2039 ( FIG. 5 ). Rotational shaft J 39 extends in the Z-axis direction, and its two ends are fixed to frame 2015 . Each of transport rollers 2034 is a specific example corresponding to an “auxiliary roller” in one or more embodiments, and transport roller frame 2039 is a specific example corresponding to a “support” in one or more embodiments.

Medium sensor 2035 is provided adjacent to, near, or close to a distal end of feed transport section 2010 (adjacent to, near, or close to stretch roller 2037 ). Medium sensor 2036 is provided in a middle position (between drive roller 2032 and stretch roller 2037 ) in the X-axis direction.

Medium transport apparatus S 12 further includes a pair of first guide rollers 2040 and a pair of second guide rollers 2042 which are provided at positions on transport table 2033 different from one another in both the X-axis direction and the Z-axis direction. For example, first guide rollers 2040 are provided respectively to two ends of transport table 2033 in the Z-axis direction. Second guide rollers 2042 are provided between first guide rollers 2040 and are located next to each other in the Z-axis direction. First guide rollers 2040 are provided to a pair of frames 2041 which are fixed to transport table 2033 . Second guide rollers 2042 are provided to frame 2043 which links the pair of frames 2041 together.

Medium transport apparatus S 12 further includes biasing part 2044 . Biasing part 2044 links or connects frame 2015 and attachment part 2015 T provided between end portion 33 T 2 and shaft portion J 1 in transport table 2033 , and thereby urges transport table 2033 upward. In other words, transport table 2033 includes attachment part 2015 T provided between second end portion 33 T 2 and end portion 33 T 1 in X-axis direction. Biasing part 2044 connecting frame 2015 and attachment part 2015 T biases transport table 2033 in a longitudinal direction of biasing part 2044 . Biasing part 2044 is, for example, an elastic member such as a coil spring or a leaf spring. Hung by biasing part 2044 , transport table 2033 is elastically turnable about shaft portion J 1 .

[1.3 Detailed Configuration of Image Formation Apparatus S 2 ]

Next, referring to FIG. 1 , descriptions are provided for a configuration of image formation apparatus S 2 . Image formation apparatus S 2 corresponds to a specific example of an “image formation apparatus” in one or more embodiments, and is, for example, a printer which forms an image (for example, a color image) on medium PM 1 , PM 2 such as a paper sheet and a film, which serve as materials to be printed on, by use of an electrophotographic method. Inside housing K, image formation apparatus S 2 includes medium feed device 100 , transport device 300 , image formation device 400 , attached part 600 , intermediate transfer device 700 , fixation device 500 , delivery device 800 , reverse device 900 , controller SS 2 , and drive motor S 2 M. Controller SS 2 controls the entirety of image formation apparatus S 2 in cooperation with controller SS 1 in medium feeder S 1 . Based on an instruction from controller SS 2 , drive motor S 2 M serves as a drive source for the entirety. Image formation apparatus S 2 is configured such that medium transport apparatus S 12 is attachable to and detachable from attached part 600 .

(Medium Feed Device 100 )

Medium feed device 100 includes feed tray 101 , placement board 102 , lift-up lever 103 , motor 104 , elevation detector 201 , pickup roller 202 , feed roller 203 and retard roller 204 .

Feed tray 101 , for example, is detachably attached to a lower part of image formation apparatus S 2 , contains media PM 2 as stacked, and is provided with placement board 102 so that placement board 102 is turnable about shaft J 102 . Some of media PM 2 are stacked on placement board 102 . Lift-up lever 103 , which is supported turnable by shaft J 103 , is provided to a feed-out side of feed tray 101 from which media PM 2 are fed out. Drive force from motor 104 rotates shaft J 103 . For example, based on a signal from controller SS 2 , motor 104 operates and stops. In medium feed device 100 like this, lift-up lever 103 turns about shaft J 103 ; thereby, a distal end portion of lift-up lever 103 pushes placement board 102 upward; and media PM 2 placed on placement board 102 also rise. This configuration makes sure that the upper surface of the uppermost one of media PM 2 is in contact with pickup roller 202 . Elevation detector 201 detects that placement board 102 is elevated sufficiently up to a predetermined height and the upper surface of the uppermost one of media PM 2 comes into contact with pickup roller 202 . Based on a signal from elevation detector 201 , controller SS 2 stops the drive of motor 104 . Pickup roller 202 , feed roller 203 and retard roller 204 jointly function as a print medium feed-out section which feeds media PM 2 , contained in feed tray 101 , to transport device 300 on a one-by-one basis. Pickup roller 202 and feed roller 203 are rotationally driven in their respective arrow directions illustrated in FIG. 1 .

(Attached Part 600 )

Attached part 600 receives medium PM 1 transported from medium transport apparatus S 12 in medium feeder S 1 , and includes opening 650 provided in the side surface of housing K. FIG. 6 illustrates an external appearance of attached part 600 in a magnified way. FIG. 7 illustrates medium transport apparatus S 12 detached away from attached part 600 . FIG. 8 illustrates medium transport apparatus S 12 attached to attached part 600 . Attached part 600 as a whole has a recess portion such that a distal end of medium transport apparatus S 12 , inserted through opening 650 , is attachable to and detachable from attached part 600 . Attached part 600 includes: guide surface 605 serving as the ceiling surface of the recess portion; medium load plate 601 serving as the bottom surface of the recess portion; and a pair of guide plates 608 serving as the side surfaces of the recess portion. Feed roller 603 and retard roller 604 are provided in the most downstream portion of attached part 600 . Pickup roller 602 , which is supported rotatable by frame 607 , is provided before feed roller 603 . Pickup roller 602 , feed roller 603 and retard roller 604 jointly function as a print medium feed-out section which feeds media PM 1 , transported from medium transport apparatus S 12 , to transport device 300 on a one-by-one basis.

Guide surface 605 guides first guide rollers 2040 and second guide rollers 2042 to the deep of attached part 600 while biasing first guide rollers 2040 and second guide rollers 2042 downward. Guide surface 605 includes slope portion 605 A, slope portion 605 B, flat surface portion 605 C and slope portion 605 D in this order from opening 650 to the downstream. Slope portion 605 B and flat surface portion 605 C jointly form protrusion T 605 . Protrusion T 605 is provided only in a middle portion between the pair of second guide rollers 2042 in the width direction of medium PM 1 (in the Z-axis direction). Thus, when medium transport apparatus S 12 is attached to attached part 600 , the pair of first guide rollers 2040 do not come into contact with protrusion T 605 , and only the pair of second guide rollers 2042 come into contact with protrusion T 605 .

It should be noted that pickup rollers 202 , 602 and feed rollers 203 , 603 each may include, for example, a built-in one-way clutch mechanism such that the rollers are idly rotatable in the directions indicated with the arrows, respectively. Furthermore, using rotational torque generators, retard rollers 204 , 604 generate rotational torque in their respective arrow directions illustrated in FIG. 1 , respectively.

(Transport Device 300 )

Transport device 300 is a mechanism which transports media PM 2 from medium feed device 100 , or media PM 1 from medium transport apparatus S 12 , to a transfer device on a one-by-one basis. Transport device 300 includes, for example, medium sensor 301 , transport roller pair 302 , medium sensor 303 , transport roller pair 304 , medium thickness sensor 320 , medium sensor 330 , and transport roller pair 305 which are arranged in this order from the upstream to the downstream. Transport roller pairs 302 , 304 , 305 transport medium PM 1 , PM 2 to the downstream while restricting the skew of medium PM 1 , PM 2 or preventing medium PM 1 , PM 2 from taking an oblique course. Medium PM 1 from attached part 600 flow into the transport passage at an area between transport roller pair 302 and transport roller pair 304 . Medium sensors 301 , 303 , 330 detect the positions of medium PM 1 , PM 2 in order to adjust timings of driving transport roller pairs 302 , 304 , 305 .

(Image Formation Device 400 )

Image formation device 400 includes, for example, image formation units 400 Y, 400 M, 400 C, 400 K. Using their corresponding color toners, that is, a yellow toner, a magenta toner, a cyan toner and a black toner, image formation units 400 Y, 400 M, 400 C, 400 K form their respective color toner images, which are specific examples of a developer image.

Image formation units 400 Y, 400 M, 400 C, 400 K each include, for example, photosensitive drum 401 , charge roller 402 , light emitting diode (LED) head 850 , development roller 404 , cleaning part 405 , toner containers 406 Y, 406 M, 406 C, 406 K, and supply roller 407 . Charge roller 402 , development roller 404 and supply roller 407 jointly form a development unit, and work under the control of controller SS 2 .

Photosensitive drum 401 is a column-shaped member which carries an electrostatic latent image on its surface (surface part), and which extends in the Z-axis direction. Photosensitive drum 401 includes a photoreceptor (for example, an organic photoreceptor). More specifically, photosensitive drum 401 includes a conductive support, and a photoconductive layer covering the circumference (surface) of the conductive support. The conductive support is formed, for example, from a metal pipe which is made of aluminum. The photoconductive layer has, for example, a structure in which a charge generation layer and a charge transport layer are stacked sequentially. Photosensitive drum 401 like this rotates at a predetermined circumferential speed (in this example, rotates counterclockwise as indicated with the corresponding arrow in FIG. 1 ) based on an instruction from controller SS 2 .

Charge roller 402 is a member (charge member) which electrically charges the surface (surface part) of photosensitive drum 401 , and which is arranged in contact with the surface (circumferential surface) of photosensitive drum 401 . Charge roller 402 includes, for example, a metal shaft, and a semi-conductive rubber layer (for example, a semi-conductive epichlorohydrin rubber layer) covering the circumference (surface) of the metal shaft. In this example, charge roller 402 rotates clockwise (rotates in a direction opposite to the direction in which photosensitive drum 401 rotates).

Development roller 404 is a member that carries the toner, which is used to develop the electrostatic latent image, on its surface. Development roller 404 is arranged in contact with the surface (circumferential surface) of photosensitive drum 401 . Development roller 404 includes, for example, a metal shaft, and a semi-conductive urethane rubber layer covering the circumference (surface) of the metal shaft. Development roller 404 like this rotates at a predetermined circumferential speed (in this example, rotates clockwise, that is, in the direction opposite to the direction in which photosensitive drum 401 rotates).

Toner containers 406 Y, 406 M, 406 C, 406 K respectively contain the yellow toner, the magenta toner, the cyan toner and the black toner, as well as supply the respective color toners to corresponding supply rollers 407 depending on the necessity.

Each of supply rollers 407 is a member (supply member) which supplies the color toner to development roller 404 , and are arranged in contact with the surface (circumferential surfaces) of development roller 404 . Supply roller 407 includes, for example, a metal shaft, and a foamed silicone rubber layer covering the circumference (surface) of the metal shaft. In this example, supply roller 407 rotates clockwise (rotates in the same direction as development roller 404 rotates).

Each LED head 850 is a light exposure device which forms electrostatic latent images on the surface (surface part) of photosensitive drum 401 by exposing the surface of photosensitive drum 401 to light. Each LED head 850 includes light emitting portions which are in charge of corresponding photosensitive drum 401 , and which are arranged in the Z-axis direction. Each LED head 850 includes, for example, a light source such as a light emitting diode which emits irradiation light, and a lens array which forms an image of the irradiation light on the surface of photosensitive drum 401 .

Cleaning part 405 removes toner which remains on the surface of photosensitive drum 401 after a toner image is transferred onto medium PM 1 , PM 2 .

(Intermediate Transfer Device 700 )

Intermediate transfer device 700 is also termed an intermediate transfer belt unit, and includes intermediate transfer belt 701 , drive roller 702 , driven roller 703 , backup roller 704 , primary transfer rollers 705 Y, 705 M, 705 C, 705 K, cleaner 706 , secondary transfer roller 707 , and biasing part 708 . Drive roller 702 , driven roller 703 , backup roller 704 , primary transfer rollers 705 Y, 705 M, 705 C, 705 K, and secondary transfer roller 707 are substantially column-shaped members, which are rotatable about their respective rotational shaft portions extending in the Z-axis direction vertical to paper sheet surfaces. Intermediate transfer device 700 is a mechanism which transports medium PM 1 , PM 2 , transported from transport roller pair 305 , in the transport direction, and which transfers the toner images, formed by image formation units 400 Y, 400 M, 400 C, 400 K, onto intermediate transfer belt 701 sequentially in the transport direction.

Intermediate transfer belt 701 is, for example, an endless elastic belt made of a resin material such as polyimide resin. Intermediate transfer belt 701 is provided stretched (suspended stretched) by drive roller 702 , driven roller 703 and backup roller 704 .

Motive power which is transmitted to drive roller 702 from drive motor S 2 M controlled by controller SS 2 rotates drive roller 702 clockwise in the arrow direction illustrated in FIG. 1 . Thereby, drive roller 702 makes intermediate transfer belt 701 circularly rotate in a direction which is the same as rotation direction R 701 . Drive roller 702 is arranged upstream of image formation units 400 Y, 400 M, 400 C, 400 K in rotation direction R 701 of intermediate transfer belt 701 . Depending on biasing force produced by biasing part 708 , driven roller 703 adjusts tension to be applied to intermediate transfer belt 701 . Driven roller 703 rotates in a direction which is the same as rotation direction R 701 , and is arranged downstream of image formation units 400 Y, 400 M, 400 C, 400 K in rotation direction R 701 . Drive roller 702 , driven roller 703 and biasing part 708 jointly form a drive mechanism which drives intermediate transfer belt 701 . Cleaner 706 is a member which cleans intermediate transfer belt 701 by scraping toners which adhere to the transferred surface of intermediate transfer belt 701 .

Secondary transfer roller 707 and backup roller 704 jointly form secondary transfer section 750 . Secondary transfer roller 707 and backup roller 704 are arranged facing each other with intermediate transfer belt 701 interposed in between. Secondary transfer roller 707 includes, for example, a metal core, and an elastic layer, such as a foamed rubber layer, formed by being wound around the circumferential surface of the metal core. A biasing part, such as a coil spring, whose one end is fixed to housing K or the like of image formation apparatus S 2 biases secondary transfer roller 707 toward backup roller 704 . Thereby, secondary transfer roller 707 is pressed against backup roller 704 with intermediate transfer belt 701 interposed in between.

When backup roller 704 and secondary transfer roller 707 transfer (secondarily transfer) toner images on intermediate transfer belt 701 onto medium PM 1 , PM 2 supplied from transport roller pair 305 , a DC voltage is applied to secondary transfer roller 707 to generate a potential difference between secondary transfer roller 707 and backup roller 704 .

(Configuration of Fixation Device 500 )

Fixation device 500 is a member to apply heat and pressure to the toner images transferred on medium PM 1 , PM 2 having passed secondary transfer section 750 which includes secondary transfer roller 707 and backup roller 704 , as well as to thereby fix the toner images to medium PM 1 , PM 2 . Fixation device 500 includes upper roller 501 and lower roller 502 , as illustrated in FIG. 1 .

Upper roller 501 and lower roller 502 include heat sources 503 A, 503 B, which are heaters such as halogen lamps, therein, respectively. Upper roller 501 and lower roller 502 function as heat rollers which apply heat to the toner images on medium PM 1 , PM 2 . For example, upper roller 501 is rotationally driven by drive motor S 2 M controlled by controller SS 2 . Heat sources 503 A, 503 B are supplied with bias voltages controlled by controller SS 2 , and thus control the surface temperatures of upper roller 501 and lower roller 502 , respectively.

Lower roller 502 is arranged facing upper roller 501 so as to form a press-contact portion between lower roller 502 and upper roller 501 . Lower roller 502 functions as a pressure roller which applies pressure to the toner images on medium PM 1 , PM 2 . Lower roller 502 may include a surface layer made of an elastic material.

(Delivery Device 800 )

Delivery device 800 includes, for example, transport roller pairs 801 to 804 , and stacker 805 . Thus, when delivery separator 901 (described later) is oriented as illustrated in FIG. 1 , medium PM 1 , PM 2 having been sent out from fixation device 500 is transported sequentially by transport roller pairs 801 to 804 to the outside, and is stacked on stacker 805 . Incidentally, delivery port 510 may be additionally provided downstream of transport roller pair 801 so that transport roller pair 504 delivers medium PM 1 , PM 2 through delivery port 510 . In this case, delivery separator 507 is provided in order to select from the transport passage bound for transport roller pair 802 and the transport passage bound for transport roller pair 504 .

(Reverse Device 900 )

Reverse Device 900 is a mechanism which, after the images are formed on the surface of medium PM 1 , PM 2 , forms a transport passage for guiding medium PM 1 , PM 2 from transport roller pair 305 to secondary transfer section 750 and fixation device 500 once again in order to form images on the back surface of medium PM 1 , PM 2 . Reverse device 900 includes delivery separator 901 , reverse roller pair 902 , reverse separator 903 , guide part 904 , transport roller pairs 905 to 907 and evacuation part 914 .

When delivery separator 901 is switched, for example, into a switch-back orientation indicated with dashed lines in FIG. 1 , medium PM 1 , PM 2 having been delivered from fixation device 500 moves in an arrow B direction due to the rotations of reverse roller pair 902 , and is guided to evacuation part 914 . Thereafter, reverse separator 903 turns, and reverse roller pair 902 rotate reversely. Thereby, medium PM 1 , PM 2 having been accommodated in evacuation part 914 moves in an arrow C direction. Transport roller pairs 905 to 907 make medium PM 1 , PM 2 further move through guide part 904 . Thereafter, medium PM 1 , PM 2 is guided to the transport passage before transport roller pair 305 , and is sent out by transport roller pair 305 into secondary transfer section 750 once again. The mechanism like this makes it possible to print the both sides of medium PM 1 , PM 2 .

[1.4 Working/Effects of Image Formation System]

(A. Basic Operation)

The image formation system transfers toner images onto medium PM 1 , PM 2 in the following way.

Once print image data is inputted into activated image formation apparatus S 2 from an external apparatus, controller SS 2 starts an operation of printing the print image data.

More specifically, controller SS 2 drives intermediate transfer belt 701 and each photosensitive drum 401 , as well as makes each charge roller 402 start a charge operation. In addition, controller SS 2 sends a light-exposure control signal to each LED head 850 . At a timing specified by the light-exposure control signal, LED head 850 irradiates photosensitive drum 401 with light corresponding to a color component of a print image, and thereby forms an electrostatic latent image on the surface of photosensitive drum 401 . Development roller 404 forms a toner image as a developer image in the corresponding one of yellow (Y), magenta (M), cyan (C) and black (B) by sticking a corresponding developer to the electrostatic latent image on photosensitive drum 401 . A power supply circuit in controller SS 2 applies transfer biases to primary transfer rollers 705 Y, 705 M, 705 C, 705 K. Thus, primary transfer rollers 705 Y, 705 M, 705 C, 705 K sequentially transfer the toner images on photosensitive drums 401 onto the transferred surface of intermediate transfer belt 701 , and thereby superimpose the toner images.

Subsequently, controller SS 2 rotates pickup rollers 202 , 602 and feed rollers 203 , 603 , as well as makes medium feeder S 1 start to supply medium PM 1 , PM 2 by sending a control signal to controller SS 1 in medium feeder S 1 . Thereby, medium PM 1 , PM 2 is supplied to transport device 300 at a predetermined transport speed. More specifically, the supply of media PM 2 is achieved as follows. As illustrated in FIG. 1 , to begin with, pickup roller 202 picks up uppermost medium PM 2 from media PM 2 contained in feed tray 101 on a one-by-one basis, and sends out medium PM 2 to feed roller 203 . Subsequently, feed roller 203 and retard roller 204 corrects the skewing or obliqueness of medium PM 2 having been sent out from feed tray 101 . After that, medium PM 2 is transported to secondary transfer section 750 via transport device 300 . Descriptions are later provided for how media PM 1 is supplied in details.

For example, once medium sensor 330 detects the position of medium PM 1 , PM 2 , medium sensor 330 sends a detection signal to controller SS 2 . Controller SS 2 adjusts the transport speed of medium PM 1 , PM 2 and the rotation speed of intermediate transfer belt 701 , and thus aligns medium PM 1 , PM 2 with the toner images on intermediate transfer belt 701 . Thereby, at a secondary transfer position, that is, at a position where backup roller 704 and secondary transfer roller 707 face each other, the toner images on intermediate transfer belt 701 are secondarily transferred onto predetermined areas on medium PM 1 , PM 2 . Thereafter, fixation device 500 applies heat and pressure to the toner images having been transferred onto medium PM 1 , PM 2 , and thus fixes the toner images to medium PM 1 , PM 2 . Eventually, transport roller pairs 801 to 804 and the like in delivery device 800 deliver medium PM 1 , PM 2 with the toner images fixed thereto to the outside, and medium PM 1 , PM 2 is accumulated on stacker 805 .

(B. Attachment Operation of Medium Feeder S 1 )

Next, referring to FIGS. 9 to 11 in addition to FIGS. 7 and 8 , descriptions are provided for how to attach medium feeder S 1 to image formation apparatus S 2 . In this case, the distal end portion of medium transport apparatus S 12 is inserted into attached part 600 of image formation apparatus S 2 by moving medium feeder S 1 in the horizontal direction. Before starting the attachment operation, the height position of the distal end portion of medium transport apparatus S 12 is made to roughly agree with the height position of attached part 600 of image formation apparatus S 2 by adjusting the height of stand section 2016 .

As illustrated in FIG. 7 , to begin with, the distal end portion of medium transport apparatus S 12 , that is, the vicinity of stretch roller 2037 , is brought closer to opening 650 of attached part 600 . To this end, the height position of the vicinity of stretch roller 2037 is finely adjusted by manually lifting and pressing down transport table 2033 so that first guide rollers 2040 come closer to guide surface 605 . Since transport table 2033 is hung from frame 12 by biasing part 2044 , workload on the user is lighter. For this reason, the user can perform the fine adjustment relatively easily.

Next, as illustrated in FIG. 9 , the distal end portion of medium transport apparatus S 12 is inserted into attached part 600 via opening 650 so that first guide rollers 2040 come into contact with guide surface 605 . Thereafter, medium feeder S 1 is moved horizontally with first guide rollers 2040 in contact with guide surface 605 . Thereby, first guide rollers 2040 are guided along the shape of guide surface 605 . While first guide rollers 2040 are being guided along the shape of guide surface 605 , first guide rollers 2040 are pressed gradually downward due to their contact with slope portion 605 A. Thus, medium transport apparatus S 12 turns about shaft portion J 1 so that stretch roller 2037 descends. Continued insertion of medium transport apparatus S 12 brings second guide rollers 2042 closer to slope portion 605 B which forms protrusion T 605 , as illustrated in FIG. 10 . Eventually, as illustrated in FIG. 11 , second guide rollers 2042 come into contact with slope portion 605 B whose gradient is larger than that of slope portion 605 A. Thus, medium transport apparatus S 12 further turns about shaft portion J 1 so that stretch roller 2037 descends. Thereafter, as illustrated in FIG. 8 , second guide rollers 2042 moves over protrusion T 605 , and comes into contact with flat surface portion 605 C. Thereby, medium transport apparatus S 12 is locked. Thus, stretch roller 2037 is located right under pickup roller 602 . With this, the attachment operation of medium transport apparatus S 12 comes to an end.

(C. Operation of Medium Feeder S 1 )

Next, referring to FIGS. 1 to 5 , descriptions are provided for how medium feeder S 1 works. For example, media PM 1 such as envelopes are stacked on stacker 2020 . Media PM 1 are stacked thereon with the rear end portions of media PM 1 lifted by stack guide 2021 . Thereby, the weight of media PM 1 is distributed. Furthermore, with their front end portions in contact with set guides 2022 , media PM 1 are set thereon so as to be prevented from moving downstream. While in the state, upon receipt of a control signal from controller SS 2 of image formation apparatus S 2 , controller SS 1 drives drive motor S 1 M if medium sensor 2012 provided under stacker 2020 detects loaded media PM 1 whereas at least either medium sensor 2035 or medium sensor 2036 detects no media PM 1 . Even when medium sensor 2012 detects media PM 1 , controller SS 1 does not drive drive motor S 1 M if both medium sensor 2035 and medium sensor 2036 detect media PM 1 . Furthermore, it is a matter of course that controller SS 1 does not drive drive motor S 1 M when medium sensor 2012 detects no media PM 1 .

The drive of drive motor S 1 M rotationally drives drive roller 2013 in the arrow R 13 direction ( FIG. 5 ). The rotational drive of drive roller 2013 makes feed belt 2011 circularly rotate in the direction indicated with arrow R 11 ( FIG. 5 ). Thereby, medium PM 1 , which is located the lowest among media PM 1 stacked on stacker 2020 , is sent out in the +X direction. There is a case, however, where because of frictional forces between them, some of media PM 1 are sent out in the +X direction while remaining stacked together. One or more sent-out media PM 1 enter the interstice between preliminary movement guide 2026 and feed belt 2011 . The function of preliminary movement guide 2026 reduces the number of media PM 1 to move downstream at a time to one or two. One or more media PM 1 move in the +X direction, wiggling under separator 2003 while contacting contact surface 2003 S of separator 2003 . If media PM 1 reaches separator 2003 while remaining stacked together, separator 2003 allows only lowermost medium PM 1 to wiggle under separator 2003 , and stops upper media PM 1 . Because of this behavior, separation section 2001 separates only medium PM 1 from media PM 1 , and sends out medium PM 1 to medium transport apparatus S 12 located downstream of separation section 2001 .

The drive of drive motor S 1 M rotationally drives drive roller 2032 in the arrow R 32 direction ( FIG. 5 ). The rotational drive of drive roller 2032 circularly rotates transport belt 2031 in the direction indicated with arrow R 31 ( FIG. 5 ). Thereby, medium PM 1 , reaching medium transport apparatus S 12 after separated by medium separator S 11 , is transported in the +X direction over transport table 2033 due to frictional force produced between medium PM 1 and transport belt 2031 . Once medium sensor 2035 detects the front end portion of medium PM 1 , drive motor S 1 M stops. This stops the operation of transporting medium PM 1 . When the transport operation stops, it is desirable that the front end portion of medium PM 1 be located downstream of a nip section between pickup roller 602 and transport belt 2031 . After that, under the control of controller SS 2 in image formation apparatus S 2 , pickup roller 602 rotates, and medium PM 1 is transported further downstream. Once medium sensor 2036 detects that the rear end portion of medium PM 1 passes over medium sensor 2036 , the drive of drive motor S 1 M resumes, and medium feeder S 1 thus starts to perform a feed operation on new medium PM 1 .

(D. Working/Effects of Image Formation System)

As discussed above, in the embodiment, biasing part 2044 biases the part of transfer table 2033 upward in medium feeder S 1 . For this reason, even if transport table 2033 is bulky in size and weight, medium transport apparatus S 12 , including transport table 2033 , can be attached to attached part 600 of image formation apparatus S 2 relatively easily while avoiding medium transport apparatus S 12 , including transport table 2033 , unnecessarily colliding with guide plates 608 , medium load plate 601 and the like in attached part 600 . In other words, medium transport apparatus S 12 (medium feeder S 1 ) of the embodiment can be attached to image formation apparatus S 2 smoothly.

Particularly in the embodiment, since guide surface 605 in attached part 600 guides first guide rollers 2040 and second guide rollers 2042 while biasing first guide rollers 2040 and second guide rollers 2042 downward, medium transport apparatus S 12 imposes no excessive load on medium load plate 601 or the like in attached part 600 .

In contrast to this, if the structure were, for example, such that first guide rollers 2040 and second guide rollers 2042 are biased and guided upward by medium load plate 601 and the like while contacting medium load plate 601 and the like, medium load plate 601 and the like would likely be deformed (warped) by the weight of medium transport apparatus S 12 in a case where transport table 2033 is very heavy. Accordingly, attached part 600 would likely deteriorate quickly, and the accurate guide would likely be hindered. With these taken into consideration, it is more desirable that, like in the embodiment, first guide rollers 2040 and second guide rollers 2042 be biased and guided downward by guide surface 605 located above first guide rollers 2040 and second guide rollers 2042 while contacting guide surface 605 .

Modifications

Although described using embodiments, the invention is not limited to the foregoing embodiment, and can be modified variously. For example, although the foregoing embodiment has described the image formation apparatus which forms a color image, the invention is not limited to this. The image formation apparatus may be, for example, one which forms a monochrome image by transferring only a black toner image. Furthermore, although the foregoing embodiment has described the image formation apparatus which performs the secondary transfer, the invention is also applicable to an image formation apparatus which performs primary transfer (direct transfer).

Moreover, although in the foregoing embodiment, transport table 2033 is hung from the side wall portion of frame 2015 by biasing part 2044 , the invention is not limited to this mode. Transport table 2033 may be, for example, pushed upward by biasing part 2044 from below.

Besides, although in the foregoing embodiment and the like, both the table (transport table 2033 ) and the first rotor (drive roller 2032 ) rotate about the first shaft portion (shaft portion J 1 ), the invention is not limited to this. The table (transport table 2033 ) and the first rotor (drive roller 2032 ) may rotate about their respective shaft portions which are different from each other. What is more, the positions of drive roller 2032 and stretch roller 2037 may be swapped for each other so that transport table 2033 and stretch roller 2037 rotate about the same rotational shaft portion.

In addition, although in the foregoing embodiment and the like, the LED heads each using the light emitting diode as the light source are used as the light exposure devices, the light exposure devices each may use, for example, a laser device or the like as the light source instead.

Furthermore, although the foregoing embodiment and the like have described the image formation apparatus including the print function which is a specific example of the “image formation apparatus” in one or more embodiments, the “image formation apparatus” is not limited to this. In other words, the invention is applicable to an image formation apparatus to function as a multi-function printer which, for example, has a scan function and a facsimile function in addition to such a print function.