Display device and method of driving the same

This application is based on and claims priority to and benefit from Korean Patent Application No. 10-2008-0006343, filed on Jan. 21, 2008 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

1. Technical Field

Embodiments of the present invention relate to a display device and a method of driving the same.

2. Description of the Prior Art

A liquid crystal display (LCD), which is a type of flat panel display, is provided with a liquid crystal display (LCD) panel including a first substrate having a pixel electrode, a second substrate having a common electrode, and a liquid crystal layer having dielectric anisotropy and injected between the first substrate and the second substrate. An electric field is formed between the pixel electrode and the common electrode, and through adjustment of the intensity of the electric field, the quantity of light transmitting through the LCD panel is controlled to display a desired image on the LCD panel. Since the LCD is not a self-illumination display device, it includes a plurality of lighting blocks-.

Recently, in order to improve the display quality, techniques have been developed that divide an LCD panel into a plurality of display blocks, arrange a plurality of lighting blocks corresponding to the respective display blocks, and control luminance of the respective lighting blocks in accordance with an image being displayed on the respective display blocks.

If the number of display blocks provided in the LCD is large, then the number of lighting blocks provided corresponding to the display blocks also becomes large. Accordingly, the number of light sources and the number of drivers for driving the light sources are increased, and thus the manufacturing cost of the LCD is increased.

Accordingly, one or more embodiments of the present invention provide a display device that may reduce the manufacturing cost thereof. Embodiments of the present invention also provide a method of driving a display device that may reduce the manufacturing cost of the device thereof.

Additional advantages, objects, and features of the invention according to one or more embodiments will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

There is provided a display device, according to embodiments of the present invention, which includes a display panel including a plurality of display blocks arranged in the form of a matrix; a plurality of lighting blocks emitting light to the display panel, each of the lighting blocks arranged so as to correspond to at least one row of the matrix and having adjustable light luminance; and a signal control unit adapted to receive an image signal, determine display block luminance of the respective display blocks when an image is displayed on the respective display blocks in accordance with the image signal, determine the light luminance of the respective lighting blocks by using the display block luminance of some display blocks corresponding to the respective lighting blocks, correct the image signal by using the light luminance and the display block luminance, and provide the corrected image signal to the display panel.

In another aspect according to an embodiment of the present invention, there is provided a display device, which includes a display panel including a plurality of display blocks arranged in the form of a matrix; a plurality of lighting blocks including light sources provided on at least one of one side and the other side of a lower part of the display panel, each of the lighting blocks being arranged so as to correspond to at least one row of the matrix and having adjustable light luminance; and a signal control unit adapted to receive an image signal, determine display block luminance of the respective display blocks when an image is displayed on the respective display blocks in accordance with the image signal, determine the light luminance of the respective lighting blocks by using the display block luminance of some display blocks corresponding to the respective lighting blocks, correct the image signal by using the light luminance and the display block luminance, and provide the corrected image signal to the display panel.

In still another aspect according to another embodiment of the present invention, there is provided a method of driving a display device including a display panel having a plurality of display blocks arranged in the form of a matrix, and a plurality of lighting blocks each being arranged so as to correspond to at least one row of the matrix and emitting light to the display panel, which includes receiving an image signal and determining display block luminance of the respective display blocks; determining light luminance of the respective lighting blocks by using the display block luminance of some display blocks corresponding to the respective lighting blocks; correcting the image signal in accordance with the light luminance and the display block luminance; emitting light in accordance with the corrected image signal; and displaying an image in accordance with the corrected image signal.

The above and other objects, features and advantages of the present invention according to one or more embodiments will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating the configuration of a liquid crystal display, explaining a liquid crystal display and a method of driving the same according to an embodiment of the present invention;

FIG. 2 is an equivalent circuit diagram of one pixel according to an embodiment of the present invention;

FIG. 3 is a schematic view explaining an arrangement form of display blocks and lighting blocks LB 1 to LBn of FIG. 1 according to an embodiment of the present invention;

FIG. 4 is a block diagram explaining a signal control unit of FIG. 1 according to an embodiment of the present invention;

FIGS. 5 to 7 are conceptual views explaining the operation of the signal control unit of FIG. 4 according to one or more embodiments of the present invention;

FIG. 8 is a table explaining the operation of the signal control unit of FIG. 4 according to an embodiment of the present invention;

FIG. 9 is a graph explaining the operation of the signal control unit according to an embodiment of the present invention;

FIG. 10 is a conceptual view explaining the operation of lighting blocks according to an embodiment of the present invention;

FIG. 11 is a circuit diagram explaining the operation of a backlight driver and a corresponding lighting block according to an embodiment of the present invention;

FIG. 12 is a perspective view of lighting blocks, explaining a modified example of the lighting blocks according to an embodiment of the present invention;

FIG. 13A is a perspective view explaining a light guide plate of FIG. 12 according to an embodiment of the present invention;

FIG. 13B is a sectional view taken along line AA′ of FIG. 13A ;

FIG. 13C is a sectional view taken along line BB′ of FIG. 13A ;

FIG. 13D is a beam profile of one lighting block according to an embodiment of the present invention;

FIG. 14 is a block diagram illustrating the configuration of a signal control unit, explaining a liquid crystal display and a method of driving the same according to another embodiment of the present invention;

FIG. 15A is a conceptual view explaining the operation of an inherent light luminance calculation unit of FIG. 14 according to an embodiment of the present invention;

FIG. 15B is a view showing equations, explaining the operation of an inherent light luminance calculation unit of FIG. 14 according to an embodiment of the present invention;

FIG. 16 is a view showing equations, explaining the operation of an inherent light luminance calculation unit of FIG. 14 according to an embodiment of the present invention;

FIG. 17 is a plan view of lighting blocks, explaining a liquid crystal display according to another embodiment of the present invention;

FIG. 18 is a conceptual view explaining a liquid crystal display and a method of driving the same according to another embodiment of the present invention;

FIG. 19 is a block diagram illustrating the configuration of a signal control unit, explaining a liquid crystal display and a method of driving the same according to another embodiment of the present invention; and

FIG. 20 is a table explaining the operation of the signal control unit of FIG. 19 according to an embodiment of the present invention.

Hereinafter, one or more embodiments of the present invention will be described in detail with reference to the accompanying drawings. The aspects and features of the present invention and methods for achieving the aspects and features will be apparent by referring to the embodiments to be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed hereinafter, but can be implemented in diverse forms. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is only defined within the scope of the appended claims. In general, the same drawing reference numerals are used for the same elements across various figures.

The term “connected to” or “coupled to” that is used to designate a connection or coupling of one element to another element includes both a case that an element is “directly connected or coupled to” another element and a case that an element is connected or coupled to another element via still another element. In this case, the term “directly connected to” or “directly coupled to” means that an element is connected or coupled to another element without intervention of any other element. Also, the term “and/or” includes the respective described items and combinations thereof.

Although the terms “first, second, and so forth” are used to describe diverse elements, components and/or sections, such elements, components and/or sections are not limited by the terms. The terms are used only to discriminate an element, component, or section from other elements, components, or sections. Accordingly, in the following description, a first element, first component, or first section may be a second element, second component, or second section.

In the following description of embodiments of the present invention, the terms used are for explaining embodiments of the present invention, but do not limit the scope of the present invention. In the description, a singular expression may include a plural expression unless specially described. The term “comprises” and/or “comprising” used in the description means that one or more other components, steps, operation and/or existence or addition of elements are not excluded in addition to the described components, steps, operation and/or elements.

Unless specially defined, all terms (including technical and scientific terms) used in the description could be used as meanings commonly understood by those ordinary skilled in the art to which the present invention belongs. In addition, terms that are generally used but are not defined in the dictionary are not interpreted ideally or excessively unless they have been clearly and specially defined.

Hereinafter, embodiments of the present invention will be explained with reference to a liquid crystal display as an example of a display device, but is not limited thereto. Also, in the following description, the terms “row” and “column” of a matrix may be “column” and “row”, respectively, in accordance with the view point of an observer. Accordingly, in the description of the embodiments of the present invention, the term “row” may be replaced by “column” and the term “column” may be replaced by “row”.

Referring to FIGS. 1 to 3 , a liquid crystal display and a method of driving the same according to an embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating the configuration of a liquid crystal display, explaining a liquid crystal display and a method of driving the same according to an embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of one pixel according to an embodiment of the present invention, and FIG. 3 is a schematic view explaining an arrangement form of display blocks and lighting blocks LB 1 to LBn of FIG. 1 according to an embodiment of the present invention.

Referring to FIG. 1 , the liquid crystal display (LCD) device 10 includes a liquid crystal display (LCD) panel 300 , a gate driver 400 , a data driver 500 , a signal control unit 700 , first to n-th backlight drivers 800 _ 1 to 800 — n . Here, the signal control unit 700 is functionally divided into an image signal control unit 600 _ 1 and an optical data signal control unit 600 _ 2 . The image signal control unit 600 _ 1 controls an image displayed on the LCD panel 300 , and the optical data signal control unit 600 _ 2 controls the first to n-th backlight drivers 800 _ 1 to 800 — n . The image signal control unit 600 _ 1 and the optical data signal control unit 600 _ 2 may be physically separated from each other.

The LCD panel 300 is divided into a plurality of display blocks DB 1 to DB(n×m). For example, the plurality of display blocks DB 1 to DB(n×m) is arranged in the form of a (n×m) matrix. The respective display blocks DB 1 to DB(n×m) include a plurality of pixels. The LCD panel 300 includes a plurality of gate lines G 1 to Gk and a plurality of data lines D 1 to Dj.

An equivalent circuit of one pixel is illustrated in FIG. 2 . A pixel PX, for example, a pixel PX connected to the f-th (where, f=1˜k) gate line Gf and the g-th (where, g=1˜j) data line Dg, includes a switching element Qp connected to the gate line Gf and the data line Dg, a liquid crystal capacitor Clc and a storage capacitor Cst connected to the switching element. The liquid crystal capacitor Clc includes a pixel electrode PE of the first substrate 100 and a common electrode CE of the second substrate 200 . On a part of a common electrode CE, a color filter CF is formed.

The gate driver 400 (shown in FIG. 1 ) receives a gate control signal CONT 2 from the signal control unit 700 , and applies a gate signal to the gate lines G 1 to Gk. Here, the gate signal is composed of a combination of a gate-on voltage Von and a gate-off voltage Voff provided from a gate on/off voltage generation unit (not illustrated). The gate control signal CONT 2 is a signal for controlling the operation of the gate driver 400 , and includes a vertical start signal for starting the operation of the gate driver 400 , a gate clock signal for determining an output time of the gate-on voltage, and an output enable signal for determining a pulse width of the gate-on voltage.

The data driver 500 receives a data control signal CONT 1 from the signal control unit 700 , and applies a voltage corresponding to an image data signal IDAT to the data lines D 1 to Dj. The data control signal CONT 1 includes a signal for controlling the operation of the data driver 500 . The signal for controlling the operation of the data driver 500 includes a horizontal start signal for starting the operation of the data driver 500 , and an output command signal for commanding the output of the image data voltage.

A plurality of lighting blocks LB 1 to LBn are provided on a lower part of the LCD panel 300 , and provide light to the LCD panel 300 . The plurality of lighting blocks LB 1 to LBn, for example, may be arranged as illustrated in FIG. 3 . That is, the plurality of lighting blocks LB 1 to LBn may be separately arranged so as to correspond to at least one of rows ROW 1 to ROWn of the display blocks DB 1 To DB(n×m) arranged in the form of a matrix. In FIG. 3 , it is exemplified that the lighting blocks LB 1 to LBn may be arranged so as to correspond to the rows ROW 1 to ROWn in a one-to-one manner. That is, the plurality of display blocks DB 1 to DB(n×m) are composed of n rows and m columns, and the lighting blocks LB 1 to LBn are composed of n rows ROW 1 to ROWn. The lighting blocks LB 1 to LBn are of an edge type, and include light sources provided on one side and on the other side of a lower part of the LCD panel 300 . Here, the light source may be an LED.

The respective backlight drivers 800 _ 1 to 800 — n , for example, are connected to lighting blocks LB 1 to LBn, respectively, and adjust the luminance of the respective lighting blocks LB 1 to LBn. For example, since the number of lighting blocks LB 1 to LBn is “n,” the number of backlight drivers 800 _ 1 to 800 — n is also “n.” That is, the lighting blocks LB 1 to LBn may be arranged to correspond to the rows of the matrix, and thus the light luminance for the lighting blocks LB 1 to LBn may be adjusted.

The plurality of lighting blocks LB 1 to LBn adjust the light luminance in response to optical data signals LDAT, and the respective display blocks DB 1 to DB(n×m) display an image in response to an image data signal IDAT. Here, the optical data signal LDAT is a signal generated by the signal control unit 700 based on RGB image signals R, G, and B, and the image data signal IDAT is a corrected signal outputted by the signal control unit 700 that corresponds to RGB image signals R, G, and B in the unit of display blocks DB 1 to DB(n×m) in accordance with the light luminance. According to the LCD 10 as described above, even though the respective lighting blocks LB 1 to LBn adjust the light luminance corresponding to the rows ROW 1 to ROWn of the matrix, the signal control unit 700 corrects the RGB image signals R, G, and B in the unit of display blocks DB 1 to DB(n×m) in accordance with the light luminance, and thus, substantially the same effect may be obtained as that obtained by the light luminance adjustment through the lighting blocks LB 1 to LBn arranged in the form of a matrix corresponding to the respective display blocks DB 1 to DB(n×m).

The operation of the signal control unit will be described in more detail with reference to FIGS. 4 to 9 . FIG. 4 is a block diagram explaining the signal control unit of FIG. 1 , and FIGS. 5 to 7 are conceptual views explaining the operation of the signal control unit of FIG. 4 according to embodiments of the present invention. FIG. 8 is a table explaining the operation of the signal control unit of FIG. 4 , and FIG. 9 is a graph explaining the operation of the signal control unit according to an embodiment of the present invention.

The signal control unit 700 includes an image signal control unit 600 _ 1 and an optical data signal control unit 600 _ 2 . The image signal control unit 600 _ 1 includes a control signal generation unit 610 and a correction unit 620 . The optical data signal control unit 600 _ 2 includes a representative value determination unit 630 , a display luminance determination unit 640 , a light luminance determination unit 650 , and a luminance ratio calculation unit 660 . The optical data signal control unit 600 _ 2 adjusts the light luminance values B_LB 1 to B_LBn of the respective lighting blocks LB 1 to LBn by outputting the optical data signal LDAT based on the RGB image signals R, G, and B. The image signal control unit 600 _ 1 corrects the RGB image signals R, G, and B by using the light luminance values LB 1 to LBn and the display block luminance values B_DB 1 to B_DB(n×m). However, according to one or more embodiments, at least one of the inner blocks of the optical data signal control unit 600 _ 2 may be included inside the image signal control unit 600 _ 1 .

First, a process in which the optical data signal control unit 600 _ 2 adjusts the light luminance of the lighting blocks LB 1 to LBn, which are arranged to correspond to rows ROW 1 to ROWn, will be described in detail according to an embodiment.

The representative value determination unit 630 receives the RGB image signals R, G, and B, and determines representative values R_DB 1 to R_DB(n×m) of the respective display blocks DB 1 to DB(n×m). For example, when the RGB image signals R, G, and B are provided to the respective display blocks DB 1 to DB(n×m) and an image is displayed as shown in FIG. 5 , the representative value determination unit 630 determines the representative values R_DB 1 to R_DB(n×m) of the RGB image signals R, G, and B provided to the respective display blocks DB 1 to DB(n×m). For example, the representative values R_DB 1 to R_DB(n×m) of the respective display blocks may be average values of the RGB image signals R, G, and B provided to the respective display blocks DB 1 to DB(n×m).

The display luminance determination unit 640 determines the display block luminance values B_DB 1 to B_DB(n×m) of the respective display blocks DB 1 to DB(n×m) by using the representative values R_DB 1 to R_DB(n×m) of the respective display blocks DB 1 to DB(n×m). For example, when the RGB image signals R, G, and B are provided to the respective display blocks DB 1 to DB(n×m) and an image is displayed as shown in FIG. 5 , the display luminance determination unit 640 determines the display block luminance values B_DB 1 to B_DB(n×m) of the respective display blocks DB 1 to DB(n×m) as shown in FIG. 6 . For example, the display block luminance values B_DB 1 to B_DB(n×m) of the respective display blocks DB 1 to DB(n×m) may be any one of values in the range of 10 nit to 300 nit corresponding to the image as shown in FIG. 5 . Here, the display luminance determination unit 640 determines the display block luminance values B_DB 1 to B_DB(n×m) of the respective display blocks DB 1 to DB(n×m) corresponding to the representative values R_DB 1 to R_DB(n×m) of the respective display blocks DB 1 to DB(n×m) by using a lookup table (not illustrated).

The light luminance determination unit 650 determines the light luminance values B_LB 1 to B_LBn of the respective lighting blocks LB 1 to LBn by using the display block luminance values B_DB 1 to B_DB(n×m) of the respective display blocks DB 1 to DB(n×m). As described above, since the respective lighting blocks LB 1 to LBn correspond to rows ROW 1 to ROWn of the respective display blocks DB 1 to DB(n×m), the light luminance determination unit 650 determines the maximum values among the display block luminance values B_DB 1 to B_DB(n×m) of some of the display blocks DB 1 to DB(n×m) corresponding to the respective lighting blocks LB 1 to LBn to be the light luminance values B_LB 1 to B_LBn of the respective lighting blocks LB 1 to LBn.

More specifically, as shown in the embodiment of FIG. 6 , when the display blocks DB 1 to DB(n×m) are arranged in the form of an 8×10 matrix, 10 display blocks of the first row ROW 1 have the display block luminance of 280 nit, respectively. Accordingly, the light luminance determination unit 650 determines the light luminance of the lighting blocks corresponding to the first row ROW 1 as 280 nit. The 10 display blocks of the fifth row ROW 5 may have the display block luminance of any one of the display block luminance amounts including 120 nit and 300 nit. Accordingly, the light luminance determination unit 650 determines the light luminance of the lighting blocks corresponding to the fifth row ROW 5 as 300 nit.

As a result, the light luminance determination unit 650 , as shown in the embodiment of FIG. 7 , determines the maximum values among the display block luminance values B_DB 1 to B_DB(n×m) of some of the display blocks DB 1 to DB(n×m) corresponding to the respective lighting blocks LB 1 to LBn to be the light luminance values B_LB 1 to B_LBn.

In addition, the light luminance determination unit 650 outputs the optical data signals LDAT corresponding to the light luminance values B_LB 1 to B_LBn to the backlight drivers 800 _ 1 to 800 — n . The respective lighting blocks LB 1 to LBn receive the optical data signals LDAT and emit light with the light luminance values B_LB 1 to B_LBn, respectively, as shown in FIG. 7 . Here, the optical data signal LDAT may be a PWM (Pulse Width Modulation) signal. Also, the light luminance determination unit 650 outputs the light luminance signals B_LB 1 to B_LBn of the respective lighting blocks LB 1 to LBn to the luminance ratio calculation unit 660 .

Next, a process of correcting the RGB image signals R, G, and B in the unit of display blocks DB 1 to DB(n×m) by using the light luminance values B_LB 1 to B_LBn of the respective lighting blocks LB 1 to LBn and the display block luminance values B_DB 1 to B_DB(n×m) of the respective display blocks DB 1 to DB(n×m) will be described in detail according to one or more embodiments.

The luminance ratio calculation unit 660 calculates the block luminance ratios RB_DB 1 to RB_DB(n×m), which are the ratios of the display block luminance values B_DB 1 to B_DB(n×m) to the light luminance values B_LB 1 to B_LBn, respectively. Referring to FIGS. 5 and 8 , since the light luminance of the lighting block corresponding to the first row ROW 1 is 280 nit and the display block luminance of the respective display blocks of the first row ROW 1 is 280 nit, the block luminance ratios RB_DB 1 to RB_DB(n×m) of the respective display blocks of the first row ROW 1 become 1.00. Also, since the light luminance of the lighting block corresponding to the fifth row ROW 5 is 300 nit and the display block luminance of the respective display blocks of the fifth row ROW 5 may be, for example, either 120 nit or 300 nit, the block luminance ratios of the respective display blocks of the fifth row ROW 5 are either 0.40 or 1.00. As described above, the luminance ratio calculation unit 660 calculates the block luminance ratios RB_DB 1 to RB_D(n×m) of the respective display block luminance values B_DB 1 to B_DB(n×m) to the respective light luminance values B_LB 1 to B_LBn, and outputs the calculated block luminance ratios RB_DB 1 to RB_D(n×m) to the correction unit 620 .

The correction unit 620 receives the RGB image signal R, G, and B and the block luminance ratios RB_DB 1 to RB_D(n×m), corrects the RGB image signals R, G, and B in the unit of display blocks DB 1 to DB(n×m), and outputs an image data signal IDAT.

For example, as shown in the embodiment of FIG. 8 , since the block luminance ratios of 10 display blocks of the first row ROW 1 are 1, the correction unit 620 receives the RGB image signals R, G, and B corresponding to 10 display blocks of the first row ROW 1 , and outputs the image data signal IDAT as it is without correcting its gray level. On the other hand, since the block luminance ratio of the fifth display block of the fifth row ROW 5 is 0.40, the correction unit 620 corrects the gray level of the RGB image signals R, G, and B in accordance with the block luminance ratio of 0.40. This feature will be described in more detail with reference to FIG. 9 .

A curve illustrated in FIG. 9 indicates the display block luminance B_DB 1 to B_DB(n×m) according to the gray level of the RGB image signals R, G, and B when the block luminance ratio is 1. For example, it is assumed that the display block luminance B_DB 1 to B_DB(n×m) has the maximum value of 300 nit when the block luminance ratio is 1, therefore, RGB image signals R, G, and B having a maximum gray level of 255 are provided to the display blocks to display an image. It is also assumed that the display block luminance B_DB 1 to B_DB(n×m) is 120 nit when the RGB image signals R, G, and B having a gray level of 130 are provided to the display blocks to display an image.

Since the display block luminance of the fifth display block of the fifth row ROW 5 is 120 nit (See FIG. 6 ), but the light luminance B_LB 1 to B_LBn of the lighting blocks LB 1 to LBn corresponding to the fifth row ROW 5 is 300, the correction unit 620 lowers the gray level of the RGB image signals R, G, and B provided to the fifth display block of the fifth row ROW 5 . For example, if the gray level of the RGB image signals R, G, and B provided to the fifth display block of the fifth row ROW 5 is 130, the correction unit corrects the RGB image signals to output the image data signal IDAT having the gray level of 117 corresponding to 48 nit (=120×0.40). Since the display block luminance of the fifth display block of the fifth row ROW 5 is 120 nit, but the light luminance of the lighting blocks corresponding to the fifth row ROW 5 is 300 nit, the correction unit 620 corrects the gray level of the RGB image signals in accordance with the block luminance ratio of 0.40. In this case, an effect may be obtained that is substantially the same as or similar to that of a case in which the light of 120 nit is provided from a lower part of the fifth display block of the fifth row ROW 5 .

In other words, the respective lighting blocks LB 1 to LBn may be arranged to correspond to rows ROW 1 to ROW 8 of the matrix, and the light luminance B_LB 1 to B_LBn may be adjusted for each of the lighting blocks LB 1 to LBn. However, by correcting the gray level of the RGB image signals R, G, and B in the unit of display blocks DB 1 to DB(n×m) corresponding to the light luminance B_LB 1 to B_LBn, the lighting blocks LB 1 to LBn are arranged to correspond to the respective display blocks DB 1 to DB(n×m) in the form of a matrix as illustrated in FIG. 6 , and thus, an effect may be obtained that is substantially the same as or similar to that of a case in which the light luminance B_LB 1 to B_LBn is adjusted. Here, the respective lighting blocks LB 1 to LBn may be of an edge type as described above. That is, even if using a small number of LEDs and backlight drivers 800 _ 1 to 800 — n , the display quality can be improved with the manufacturing cost of the LCD 10 being reduced.

However, the method of correcting the RGB image signals R, G, and B is not limited thereto. For example, the correction unit 620 may correct the RGB image signals R, G, and B having the gray level of 130 to output the image data signal IDAT having a gray level of 52 (=130×0.40).

The control signal generation unit 610 of FIG. 4 receives external control signals Vsync, Hsync, Mclk, and DE, and outputs the data control signal CONT 1 and the gate control signal CONT 2 . For example, the control signal generation unit 610 may output a vertical start signal STV for starting the operation of the gate driver 400 of FIG. 1 , a gate clock signal CPV for determining an output time of a gate-on voltage, an output enable signal OE for determining a pulse width of a gate-on voltage, a horizontal start signal STH for starting the operation of the data driver 400 of FIG. 1 , and an output command signal for commanding an output of an image data voltage.

At least one of the lighting blocks LB 1 to LBn as described above may be successively turned on/off. FIG. 10 is a conceptual view explaining the operation of lighting blocks according an embodiment of the present invention. Referring to FIG. 10 , three rows among eight rows ROW 1 to ROW 8 for one frame are grouped and successively turned on/off. That is, during a first period P 1 of one frame, the lighting blocks of the first to third rows ROW 1 to ROW 3 are turned off and the lighting blocks of the fourth to eighth rows ROW 4 to ROW 8 are turned on to emit light having the above-described light luminance. During a second period P 2 , the lighting blocks of the second to fourth rows ROW 2 to ROW 4 are turned off, and the lighting blocks of the first row ROW 1 and the fifth to eighth rows ROW 5 to ROW 8 are turned on to emit light having the above-described light luminance. As the operation of the lighting blocks as described above is successively performed, the lighting blocks of the sixth to eighth rows ROW 6 to ROW 8 are turned off, and the lighting blocks of the first to fifth rows ROW 1 to ROW 5 are turned on. As described above, at least one lighting block may be successively turned on/off.

The optical data signal control unit 600 _ 2 may control the operation of the lighting blocks LB 1 to LBn by using the optical data signals LDAT. Alternatively, the backlight drivers 800 _ 1 to 800 — n may control the operation of the lighting blocks LB 1 to LBn by periodically turning on/off the LEDs. In the present invention, the method of controlling the operation of the lighting blocks LB 1 to LBn is not limited to any one of the above-described methods according to one or more embodiments.

When an image is displayed on the LCD panel 300 in a state that the lighting blocks LB 1 to LBn operate as shown in the embodiment of FIG. 10 , an effect that a black image is inserted into at least one row ROW 1 to ROW 8 is produced for one frame. This means that the LCD panel operates in a manner similar to a CRT, and thus the display quality thereof is improved.

Hereinafter, with reference to FIG. 11 , the operation of backlight drivers 800 _ 1 to 800 — n of FIG. 1 and corresponding lighting blocks LB 1 to LBn will be described according to one or more embodiments. FIG. 11 is a circuit diagram explaining the operation of the first backlight driver 800 _ 1 and the first lighting block LB 1 connected thereto for convenience in explanation.

Referring to FIG. 11 , the backlight driver 800 _ 1 includes a switching element, and controls the luminance of the first lighting block LB 1 in response to the optical data signal LDAT. Here, the optical data signal may be a PWM signal.

In operation, if the switching element of the backlight driver 800 _ 1 is turned on in response to a high-level optical data signal LDAT inputted thereto, a power supply voltage Vin is provided to an LED, and current flows through the LED and an inductor L. At this time, energy caused by the current is stored in the inductor L. If the optical data signal LDAT goes to a low level, the switching element is turned off, and the LED, the inductor L, and a diode D form a closed circuit to cause current to flow in the closed circuit. At this time, as energy stored in the inductor L is discharged, the current is reduced. Since the turn-on time of the switching element is adjusted in accordance with a duty ratio of the optical data signal LDAT, the light luminance B_LB 1 of the first lighting block LB 1 is controlled in accordance with the duty ratio of the optical data signal LDAT. Also, in accordance with the optical data signal LDAT, at least one lighting block may be successively turned on/off.

However, according to an embodiment, the optical data signal control unit 600 _ 2 , unlike the optical data signal control unit as illustrated in the embodiment of FIG. 1 , may output the optical data signal LDAT to the respective backlight drivers 800 _ 1 to 800 — n through a serial interface.

In the liquid crystal display and the method of driving the same according to an embodiment of the present invention, the LCD panel 300 may be divided into a plurality of display blocks DB 1 to DB(n×m) in the form of a matrix, and the lighting blocks may be arranged to correspond to the rows of the matrix. The light luminance of the respective lighting blocks LB 1 to LBn is adjusted corresponding to the rows ROW 1 to ROW 8 of the matrix, but the RGB image signals R, G, and B are corrected for the respective display blocks DB 1 to DB(n×m). Accordingly, an effect may be obtained that is the same as or similar to that of a case in which the lighting blocks LB 1 to LBn emit light having different light luminance B_LB 1 to B_LBn corresponding to the display blocks DB 1 to DB(n×m) in the form of a matrix. At this time, since a small number of light sources (e.g., LEDs) and backlight drivers 800 _ 1 to 800 — n may be used, the manufacturing cost of the liquid crystal display 10 may be reduced. However, the present invention is not limited thereto, and the lighting blocks LB 1 to LBn may be arranged to correspond to the rows of the matrix according to one or more embodiments.

Hereinafter, with reference to FIGS. 12 to 13D , a modified example of the lighting blocks will be described according to one or more embodiments. FIG. 12 is a perspective view of lighting blocks explaining a modified example of the lighting blocks. FIG. 13A is a perspective view explaining a light guide plate of FIG. 12 , FIG. 13B is a sectional view taken along line AA′ of FIG. 13A , FIG. 13C is a sectional view taken along line BB′ of FIG. 13A , and FIG. 13D is a beam profile of one lighting block.

Unlike the lighting blocks as illustrated in the embodiment of FIG. 3 , light sources may be provided only on one side of a lower part of the LCD panel 300 . Hereinafter, it is exemplified that the light source is an LED, but the light source is not limited thereto.

The respective lighting blocks LB 1 to LBn are of an edge type, and include LEDs arranged on one side surface of the lower part of the LCD panel to correspond to the respective rows ROW 1 to ROWn. A light guide plate 220 ( FIG. 13A ) is provided on the lower part of the LCD panel 300 to guide the light emitted from the LEDs provided on one side surface toward an upper surface of the LCD panel 300 .

Hereinafter, the structure of the light guide plate 200 according to an embodiment will be described in detail. However, the light guide plate is not limited to the structure as described below, but may be formed in various shapes.

In the light guide plate 220 , a specified pattern may be formed on a light output surface 227 or an opposite surface 228 facing the light output surface 227 so that incident light may be uniformly transferred over the whole surface of the LCD panel 300 .

Specifically, the light guide plate 220 includes a light input surface 224 and first protrusions 221 formed on the light output surface 227 adjacent to the light input surface 224 . The first protrusions 221 may be formed to extend in a vertical direction. The first protrusions 221 may have elliptical cut portions parallel to the light input surface 224 , and a spacer 222 having a flat surface may be formed between the first protrusions 221 . Alternatively, the spacer 222 may have a concave or convex surface. One or more first protrusions 221 may be formed on the light output surface 227 of the light guide plate 220 , and one or more second protrusions 223 may be formed on the opposite surface 228 facing the light output surface 227 . The second protrusions 223 may extend in a direction parallel to the first protrusions 221 . In addition, between the second protrusions 223 , a reflective pattern 225 having a reflective surface 226 facing the light input surface 224 may be further formed. The reflective pattern 225 , for example, may be in the form of a triangular prism having a negative angle, or it may be in diverse forms such as a semicircle, a pyramid, and the like. However, according to an embodiment, the second protrusions 223 may be omitted, and only the reflective pattern 225 may be formed on the opposite surface 228 .

In order to heighten the reflection efficiency, the base angle θ 1 ( FIG. 13C ) of the reflective surfaces 226 _ 1 and 226 _ 2 of the reflective pattern 225 located on the side of the light input surface 224 and the base angle θ 2 of the opposite surfaces 229 _ 1 and 229 _ 2 may be formed to satisfy the conditions of θ 1 ≦θ 2 . Also, since the luminance is lowered as the reflective pattern becomes more distant from the light input surface 224 , the height H 2 of the reflective pattern 225 _ 2 formed apart from the light input surface 224 may be formed to be greater than the height H 1 of the reflective pattern 225 _ 1 formed near the light input surface 224 in order to heighten the luminance of a place more distant from the light input surface 224 .

Via the light guide plate 220 , the respective lighting blocks BL 1 to BLn may be arranged to correspond to rows ROW 1 to ROWn of the matrix. In FIG. 13D , a beam profile of one lighting block is illustrated according to an embodiment. The light emitted from one lighting block exerts almost no influence upon the adjacent lighting blocks. That is, the respective lighting blocks may be divided by using the light guide plate 220 , without the necessity of physical division, and the light luminance for the respective lighting blocks LB 1 to LBn may be adjusted.

For example, the lighting blocks LB 1 to LBn as illustrated in FIG. 3 may be constructed by symmetrically arranging the light sources LEDs and the light guide plate 220 as illustrated in FIG. 12 .

With reference to FIGS. 14 to 15B , a liquid crystal display and a method of driving the same according to another embodiment of the present invention will be described. FIG. 14 is a block diagram illustrating the configuration of a signal control unit, explaining a liquid crystal display and a method of driving the same according to another embodiment of the present invention. FIG. 15A is a conceptual view explaining the operation of an inherent light luminance calculation unit of FIG. 14 , and FIG. 15B is a view showing equations explaining the operation of an inherent light luminance calculation unit of FIG. 14 .

In the previous embodiment of the present invention described above, it is not considered that the respective lighting blocks LB 1 to LBn may be influenced by the adjacent lighting blocks. For example, in the case where the respective lighting blocks LB 1 to LBn are not physically separated from one another, the luminance of one lighting block LB 1 to LBn may be influenced by the light emitted from other lighting blocks. Also, if the characteristic of the light guide plate 220 is not superior, the luminance of one lighting block LB 1 to LBn may be influenced by the light emitted from other lighting blocks LB 1 to LBn. That is, the light luminance B_LB 1 to B_LBn of one lighting block LB 1 to LBn may be formed through the superimposition of the light provided from other lighting blocks LB 1 to LBn on the light provided from one lighting block LB 1 to LBn. In this case, in order for the respective lighting blocks LB 1 to LBn to finally have the light luminance B_LB 1 to B_LBn, the light sources of the respective lighting blocks LB 1 to LBn should emit light having an inherent light luminance that is lower than the light luminance B_LB 1 to B_LBn. That is, it is required for the signal control unit 701 to output the optical data signals LDAT corresponding to the inherent light luminance that is lower than the light luminance B_LB 1 to B_LBn to the backlight drivers 800 _ 1 to 800 — n (shown in FIG. 1 ).

To accomplish this, in the embodiment of the present invention, the signal control unit 701 may further include an inherent light luminance calculation unit 670 . Specifically, the light luminance determination unit 650 determines the light luminance B_LB 1 to B_LBn of the respective lighting blocks LB 1 to LBn. The inherent light luminance calculation unit 670 calculates the inherent light luminance of the respective lighting blocks LB 1 to LBn in consideration of the influence of other lighting blocks, and outputs the optical data signals LDAT corresponding to the inherent light luminance. Accordingly, the backlight drivers 800 _ 1 to 800 — n drive LEDs of the respective lighting blocks LB 1 to LBn in response to the optical data signals LDAT, and the LEDs emit light having the inherent light luminance. Consequently, the respective lighting blocks LB 1 to LBn may have the light luminance B_LB 1 to B_LBn.

Hereinafter, the calculation of the inherent light luminance will be described in more detail with reference to FIGS. 15A and 15B . In this embodiment of the present invention, it is exemplified that 6 lighting blocks LB 1 to LB 6 are provided to correspond to 6 rows, and the luminance of one lighting block is influenced by other lighting blocks contacting the one lighting block.

In FIG. 15A , in the case of considering only group I, the luminance of the first lighting block LB 1 is influenced by the luminance of the second lighting block LB 2 that is in contact with the first lighting block, but it is not influenced by the luminance of the third lighting block LB 3 that is not in contact with the first lighting block. Also, the luminance of the second lighting block LB 2 is influenced by the luminance of the first and third lighting blocks LB 1 and LB 3 . The luminance of the third lighting block LB 3 is influenced by the luminance of the second lighting block LB 2 , but is not influenced by the first lighting block LB 1 .

Accordingly, as illustrated in FIG. 15B , three simultaneous equations of group I may be derived. Here, B 1 , B 2 , and B 3 are light luminance values B_LB 1 to B_LB 3 of the respective lighting blocks LB 1 to LB 3 , “Cij” is a coefficient indicating the degree of influence exerted on the i-th lighting block by the j-th lighting block, and “bi” is an inherent light luminance of the i-th lighting block. That is, the light luminance B_LB 1 of the first lighting block LB 1 is formed through the superimposition of the inherent light luminance of the first lighting block LB 1 on the inherent light luminance of the second lighting block LB 2 . When LEDs of the first lighting block LB 1 are operated so that the inherent light luminance of the first lighting block LB 1 becomes “b 1 ,” the light luminance of the first lighting block LB 1 is influenced by the inherent light luminance of the second lighting block LB 2 , and thus the first lighting block LB 1 has the light luminance B_LB 1 of B 1 . Here, “Cij” is a value that can be derived by experiments. In the same manner, for group II, group III, and group IV, simultaneous equations of the respective groups may be derived.

Accordingly, using the simultaneous equations of the respective groups, the inherent light luminance “b 1 ” to “b 6 ” of the respective lighting blocks LB 1 to LB 6 may be obtained. The inherent light luminance “b 1 ,” “b 2 ,” and “b 3 ” are obtained in group I, “b 2 ,” “b 3 ,” and “b 4 ” are obtained in group II, “b 3 ,” “b 4 ,” and “b 5 ” are obtained in group III, and “b 4 ,” “b 5 ,” and “b 6 ” are obtained in group IV. Duplicate solutions in the respective groups may be averaged. For example, “b 2 ” may be obtained by averaging “b 2 ” in group I and “b 2 ” in group II, and “b 3 ” may be obtained by averaging “b 3 ” in group I, “b 3 ” in group II, and “b 3 ” in group III.

Through the above-described process according to an embodiment, the inherent light luminance calculation unit 670 may obtain the inherent light luminance “b 1 ” to “b 6 ” of the respective lighting blocks LB 1 to LB 6 , and may output the optical data signals LDAT corresponding to the respective inherent light luminance “b 1 ” to “b 6 .”

Hereinafter, with reference to FIGS. 14 , 15 A and 16 , another method of calculating the inherent light luminance will be described according to an embodiment. FIG. 16 is a view showing equations, explaining another method of calculating the inherent light luminance through the signal control unit.

The above-described method is a method of calculating the inherent light luminance “b 1 ” to “b 6 ” of the respective lighting blocks LB 1 to LB 6 in the case where the luminance of one lighting block is influenced by other lighting blocks that are in contact with the one lighting block. In contrast, a method of calculating the inherent light luminance “b 1 ” to “b 6 ” of the respective lighting blocks LB 1 to LBn in the case where the luminance of one lighting block is influenced by other lighting blocks that are not in contact with the one lighting block will now be described according to an embodiment.

In FIG. 15A , the first lighting block LB 1 may be influenced by the inherent light luminance “b 2 ” to “b 6 ” of the second to sixth lighting blocks LB 2 to LB 6 . Also, the second lighting block LB 2 may be influenced by the inherent light luminance “b 1 ,” and “b 3 ” to “b 6 ” of the first and third to sixth lighting blocks LB 1 and LB 3 to LB 6 . The third lighting block LB 3 is influenced by the luminance of the first, second, and fourth to sixth lighting blocks LB 1 , LB 2 , LB 4 to LB 6 . In this manner, 6 simultaneous equations may be derived as shown in FIG. 16 .

Here, B 1 , B 2 , B 3 , B 4 , B 5 , and B 6 are the light luminance B_LB 1 to B_LB 6 of the respective lighting blocks LB 1 to LB 6 , “Cij” is a coefficient indicating the degree of influence exerted on the i-th lighting block by the j-th lighting block, and “bi” is an inherent light luminance of the i-th lighting block. When LEDs of the i-th lighting block are operated so that only the luminance of the i-th lighting block becomes “bi,” the i-th lighting block has the light luminance of B 1 . Here, “Cij” is a value that may be derived by experiments.

That is, the inherent light luminance calculation unit 670 may obtain the inherent light luminance “b 1 ” to “b 6 ” of the respective lighting blocks LB 1 to LB 6 through the equations as shown in FIG. 16 . Also, the inherent light luminance calculation unit 670 outputs the optical data signals LDAT corresponding to the inherent light luminance “b 1 ” to “b 6 .”

With reference to FIG. 17 , a liquid crystal display according to another embodiment of the present invention will be described. FIG. 17 is a plan view of lighting blocks, explaining a liquid crystal display according to another embodiment of the present invention.

Unlike the previous embodiment of the present invention, the lighting blocks LB 1 to LBn according to another embodiment of the present invention are of a direct downward type and include line light sources. Here, the light source may be any one of a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), or an external electrode fluorescent lamp (EEFL). The direct downward type lighting blocks LB 1 to LBn including the line light sources, in the same manner as described above, may be arranged to correspond to the rows ROW 1 to ROWn of the matrix, and may have different light luminance. Also, the respective direct downward type light sources may be successively turned on/off in the same manner as shown in FIG. 10 .

In the liquid crystal display according to an embodiment of the present invention, the respective lighting blocks LB 1 to LBn include line light sources, and the light luminance is adjusted corresponding to the rows ROW 1 to ROWn of the matrix. However, since the RGB image signals R, G, and B are corrected for the respective display blocks D 1 to DB(n×m), an effect may be obtained that is substantially the same as or similar to that of a case in which the lighting blocks LB 1 to LBn emit light of different light luminance B_LB 1 to B_LBn corresponding to the display blocks DB 1 to DB(n×m) in the form of a matrix.

With reference to FIGS. 18 to 20 , a liquid crystal display and a method of driving the same according to still another embodiment of the present invention will be described. FIG. 18 is a conceptual view explaining a liquid crystal display and a method of driving the same according to another embodiment of the present invention. FIG. 19 is a block diagram illustrating the configuration of a signal control unit, explaining a liquid crystal display and a method of driving the same according to another embodiment of the present invention, and FIG. 20 is a table explaining the operation of the signal control unit of FIG. 19 .

In this embodiment, the LCD panel 300 , as shown in FIG. 18 , is divided into a plurality of display columns COL 1 to COLm including some display blocks corresponding to at least one column of the matrix. The signal control unit 702 as shown in FIG. 19 determines display column luminance when the RGB image signals R, G, and B are provided to the respective display columns COL 1 to COLm to display the image, determines column luminance ratios that are ratios of the display column luminance to the lighting blocks LB 1 to LBn, and corrects the RGB image signals R, G, and B provided to the respective display columns COL 1 to COLm in accordance with the column luminance ratios RB_COL 1 to RB_COLm in the unit of the display columns COL 1 to COLm.

Referring to FIGS. 19 and 20 , the luminance ratio calculation unit 662 first calculates the block luminance ratios RB_DB 1 to RB_D(n×m) as described above, and calculates the column luminance ratios RB_COL 1 to RB_COLm by averaging the block luminance ratios RB_DB 1 to RB_D(n×m) of some display blocks DB 1 to DB(n×m) corresponding to the display columns COL 1 to COLm. For example, the luminance ratio calculation unit 662 calculates the column luminance ratio RB_COL 1 of 0.96 of the first display column COL 1 by averaging the respective block luminance ratios RB_DB 1 to RB_D(n×m) of 1.00, 1.00, 1.00, 1.00, 1.00, 0.93, 0.75, and 1.00 of the first column COL 1 . In this manner, the luminance ratio calculation unit 662 calculates the column luminance ratios RB_COL 1 to RB_COLm of the respective display columns, and outputs the respective column luminance ratios RB_COL 1 to RB_COLm to a correction unit 622 .

The correction unit 622 corrects the gray level of the RGB image signals R, G, and B provided to the display columns COL 1 to COLm in the unit of display columns COL 1 to COLm by using the column luminance ratios RB_COL 1 to RB_COLm. That is, the correction unit 622 corrects the gray level of the RGB image signals R, G, and B provided to the second display column COL 2 by using the column luminance ratio RB_COL 2 of 0.97. In the same manner, the correction unit corrects the gray level of the RGB image signals R, G, and B provided to the third to tenth display columns COL 3 to COL 10 by using the column luminance ratios of 0.95, 0.84, 0.77, 0.85, 0.96, 0.82, 0.80, and 0.79.

Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.