KR100895304B1 - Liquid crystal device and driving device thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a drive device thereof.

In the liquid crystal display according to the present invention, red, blue, green, and white pixels form one dot which is a basic unit for displaying an image. The RGB image signal applied from the outside is converted into an RGBW image signal, and the converted RGBW image signal is optimized and provided to the data driver. In this case, when providing the RGBW image signal to the data driver, data may be provided in units of 3 pixels.

According to the present invention, by displaying an image using four pixels of RGBW, the light efficiency can be further improved. Accordingly, power consumption can be further reduced. In addition, since optimized RGBW data can be calculated from the RGB data, the power consumption of the liquid crystal display device can be reduced efficiently, and the image quality can be improved by alleviating the characteristic change during gray level inversion.

Pixel array, LCD, Brightness increase, RGBW

Description

Liquid crystal display and driving device thereof

1 is a diagram illustrating a pixel array structure of a liquid crystal display according to a first exemplary embodiment of the present invention.

2 is a diagram illustrating a pixel array structure of a liquid crystal display according to a second exemplary embodiment of the present invention.

3A and 3B illustrate a pixel array structure of a liquid crystal display according to a third exemplary embodiment of the present invention.

4A and 4B are diagrams illustrating a pixel array structure of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

5 is a diagram illustrating a structure of a thin film transistor substrate of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

FIG. 6 is a cross-sectional view of the TFT substrate for a liquid crystal display device taken along the line VI-VI ′ in FIG. 5.

7 is a block diagram of a driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

8 is a structural diagram of a timing controller according to an exemplary embodiment of the present invention shown in FIG. 7.                 

9 is a data output timing diagram of a timing controller according to an embodiment of the present invention.

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a pixel array structure for displaying a high resolution image and a driving device thereof.

In general, a liquid crystal display device injects a liquid crystal material between two substrates having an electrode generating an electric field, and applies an electric potential different from each other to form an electric field to change the arrangement of liquid crystal molecules, thereby transmitting light. It is a device that expresses the image by adjusting.

Such a liquid crystal display has a pixel electrode and a plurality of pixels in which color filters of red (R: red), green (G: green), and blue (B: blue) are formed, and each of the liquid crystal displays has a signal applied through a wiring. The pixels are driven to perform a display operation. The wiring includes a gate line (or scan signal line) for transmitting a scan signal and a data line (or image signal line) for transferring an image signal, and each pixel is formed with a thin film transistor connected to one gate line and one data line. The image signal transmitted to the pixel electrode formed in the pixel is controlled.

In this case, various colors may be displayed by arranging various color filters of red (R), green (G), and blue (B) in each pixel, and in the arrangement method, color filters of the same color are arranged in pixel columns. Stripe type to arrange, mosaic type to sequentially arrange color filters of red (R), green (G) and blue (B) in the column and row directions, and zigzag to stagger the unit pixels in the column direction And a delta type in which color filters of red (R), green (G), and blue (B) are arranged in sequence and arranged in sequence. In the case of the delta type, when displaying an image of three unit pixels including red (R), green (G), and blue (B) color as one dot, the screen displays a circle or a diagonal line. It has the ability to express well.

However, in the conventional liquid crystal display device which displays one dot based on three color pixels of red (R), green (G), and blue (B), there is a disadvantage in that the light efficiency is lowered. Specifically, each of the red (R), green (G), and blue (B) pixels have a color filter. Since the color filter transmits only about one third of the applied light, the overall light efficiency decreases.

Therefore, the technical problem of the present invention is to provide a liquid crystal display device having a high light efficiency.

In addition, another technical problem of the present invention is to improve luminance and power efficiency while maintaining color reproducibility of the liquid crystal display.

In the liquid crystal display according to an aspect of the present invention for achieving the above technical problem, the pixels of the red, blue, green, and white are arranged in the row direction, only pixels of the same color in the column direction A pixel array arranged in which the area of the white pixel is smaller than the area of the remaining pixels; A gate line disposed in the horizontal direction with respect to the pixel row and transferring a scan signal or a gate signal to the pixel; Data lines arranged to insulate and intersect the gate lines in a vertical direction, and to transfer an image or data signal and to be arranged with respect to the pixel columns; Pixel electrodes formed on the pixels in row and column directions, respectively, to which the data signals are transmitted; And a switching element formed in each of the pixels in a row and column direction, the gate electrode connected to the gate line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode. do.

In addition, in the liquid crystal display according to another aspect of the present invention, green, red, blue, and white pixels are arranged adjacent to each other over two pixel rows, and the four pixels display one dot for displaying an image. A pixel array in which the area of the white pixel is smaller than the area of the remaining pixels; A gate line disposed in the horizontal direction with respect to the pixel row and transferring a scan signal or a gate signal to the pixel; Data lines arranged to insulate and intersect the gate lines in a vertical direction, and to transfer an image or data signal and to be arranged with respect to the pixel columns; Pixel electrodes formed on the pixels in row and column directions, respectively, to which the data signals are transmitted; And a switching electrode formed in each of the pixels in a row and column direction and including a gate electrode connected to the gate line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode. Include.

In the liquid crystal display of the present invention having the above characteristics, the area of the gate line connected to the white pixel may be larger than the area of the gate line connected to the remaining pixels. The area of the gate line and the data line connected to the white pixel may be larger than the area of the gate line and the data line connected to the remaining pixels. Here, the green pixel is preferably not disposed adjacent to the white pixel.

A driving device of a liquid crystal display according to another aspect of the present invention may include a plurality of gate lines, a plurality of data lines insulated from and intersecting the plurality of gate lines, and an area in which the plurality of data lines and the gate lines intersect. And a plurality of pixels arranged in a matrix form having switching elements connected to the gate line and the data line, respectively, each pixel being one of red, green, blue, and white pixels. A drive device for a liquid crystal display device, wherein the white pixels form one dot, comprising: a gate driver supplying a gate voltage to the gate line; A data driver supplying a data voltage corresponding to the RGBW image signal applied to the day line; And a timing controller converting an RGB image signal applied from the outside into an RGBW image signal and optimizing the converted RGBW image signal to provide the data driver.

The timing controller may include a data converter configured to convert an RGB image signal applied from the outside into an RGBW image signal; A data optimizer which optimizes the RGBW image signal output from the data converter; A data output unit configured to output the optimized RGBW image signal to the data driver according to a clock signal applied thereto; And a clock generator for generating the clock signal and providing the clock signal to the data output unit.

In particular, the data optimizer separates the achromatic component W ₀ and the color components R ₀ , G ₀ , B ₀ from the RGBW image signal output from the data converter, and maximizes the achromatic component W ₀ . [W '= Min (W ₀ , 255), R' = R ₀ + Max (0, W ₀ -255), G '= G ₀ + Max (0, W ₀ -255), B' = B ₀ + Max (0, W ₀ -255)] The RGBW image signal can be optimized.

In addition, the data optimizer separates the achromatic component W ₀ and the color components R ₀ , G ₀ , B ₀ from the RGBW image signal output from the data converter, and minimizes the achromatic component W ₀ . [W '= W _0- {max-Max (R ₀ , G ₀ , B ₀ )}, R' = R ₀ + max-Max (R ₀ , G ₀ , B ₀ )}, G '= G ₀ + maximum value-Max (R ₀ , G ₀ , B ₀ )}, B '= B ₀ + maximum value-Max (R ₀ , G ₀ , B ₀ )}] The RGBW image signal can be optimized. .

The data optimizer separates the achromatic component W ₀ and the color components R ₀ , G ₀ , and B ₀ from the RGBW output from the data converter, and separates the achromatic component W ₀ and the color component. By equalizing (R ₀ , G ₀ , B ₀ ), [W '= (W ₀ + Average (R ₀ , G ₀ , B ₀ ))} / 2, R' = R ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2, G '= G ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2, B' = B ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2] The RGBW image signal can be optimized.

The data output unit may store the RGBW image signal according to the clock signal and output the corresponding data to the data driver in units of three pixels.

According to still another aspect of the present invention, there is provided a method of driving a liquid crystal display device, the method comprising: forming a plurality of gate lines, a plurality of data lines insulated from and intersecting the plurality of gate lines, and an area in which the plurality of data lines and the gate lines intersect. And a plurality of pixels arranged in a matrix form having switching elements connected to the gate line and the data line, respectively, each pixel being one of red, green, blue, and white pixels. A driving method of a liquid crystal display device in which white pixels form one dot, the method comprising: a) converting an RGB image signal applied from the outside into an RGBW image signal and optimizing the converted RGBW image signal; b) supplying a gate voltage to the gate line; c) supplying a data voltage corresponding to the optimized RGBW image signal to the data line.

DETAILED DESCRIPTION Embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like parts are designated by like reference numerals throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only the other part being "right over" but also another part in the middle. On the contrary, when a part is "just above" another part, there is no other part in the middle.

1 illustrates a pixel array structure of a liquid crystal display according to a first exemplary embodiment of the present invention.

As shown in FIG. 1, in the liquid crystal display according to the first embodiment of the present invention, red, blue, and green color filter pixels and white pixels arranged in a matrix form are provided. W ... are formed, and pixels of the same color are arranged in pixel column units. For example, red, blue, green, and white pixels (... R, B, G, W ...) are sequentially arranged in the row direction, and only pixels of the same color are arranged in the column direction. That is, the red, green, blue, and white pixels have a stripe structure in which pixel units are arranged. Here, the order in which the red, green, blue, and white pixels are arranged is not limited to the above-described one, and since the transmittance of the green pixels is higher than that of the other color pixels, it is preferable not to arrange the green pixels and the white pixels adjacently.

In the pixel arrangement structure according to the first embodiment of the present invention, red, green, blue and white pixels sequentially arranged in the row direction are used as "dots" which are basic units for displaying an image. Here, the areas of the pixels constituting the dots are the same.

When the image is displayed using red, green, blue and white pixels as one dot as in the present invention, the overall light efficiency is increased. For example, assume that the amount of light passing through the TFT substrate-side polarizer in the liquid crystal display device is "1". In the case of displaying dots with three pixels of red, green, and blue, one-third of the area of each pixel, and the transmittance is 1/3 by color filter, the total transmittance of one dot is [1/3 × 1 / 3 (R)] + [1/3 x 1/3 (G)] + [1/3 x 1/3 (B)] = 1/3 = 33.3%.

However, in the embodiment of the present invention, since the pixel is 1/4 of the area of each pixel and the transmittance of the white pixel is 1 (the white pixel has no color filter), the total transmittance of one dot is [1/4 x 1 / 3 (R)] + [1/4 × 1/3 (G)] + [1/4 × 1/3 (B)] + [1/4 × 1 (W)] = 1/2 = 50% do. As described above, according to the exemplary embodiment of the present invention, the luminance is about 1.5 times higher than that of the conventional liquid crystal display.

Meanwhile, the liquid crystal display according to the exemplary embodiment of the present invention may have a pixel array structure having a checkerboard structure, in addition to the stripe structure as in the first embodiment.

2 is a diagram illustrating a pixel array structure of a liquid crystal display according to a second exemplary embodiment of the present invention.

As shown in FIG. 2, in the liquid crystal display according to the second exemplary embodiment, red, green, blue, and white pixels forming one dot are arranged adjacent to each other over two pixel rows. For example, green and red pixels or blue and white pixels are sequentially arranged in the row direction, and green and blue pixels or red and white pixels are sequentially arranged in the column direction. Here, it is preferable that the green pixels and the white pixels are not disposed adjacent to each other.

In the pixel array structure according to the second embodiment of the present invention, red, green, blue, and white pixels formed over two pixel rows are used as "dots" which are basic units for displaying an image. Therefore, similarly to the first embodiment, the total transmittance of one dot is about 1.5 times higher than that of the conventional liquid crystal display by the transmittance of the white pixel.

As in the first and second embodiments described above, when white pixels are used in one dot display, the luminance may be increased while the color concentration at high luminance may be reduced.

Therefore, in the third embodiment of the present invention, the area of the white pixel is adjusted in order to increase the luminance and to prevent the color concentration from decreasing.

3A and 3B illustrate a pixel array structure of a liquid crystal display according to a third exemplary embodiment of the present invention.

3A and 3B, in the liquid crystal display according to the third embodiment of the present invention, red, green, blue, and white pixels are arranged in pixel columns as in the first embodiment. It has a stripe structure, and unlike the first embodiment, the area of the white pixel is reduced to, for example, 1/4 of the other pixels.

More specifically, as shown in FIG. 3A, in order to adjust the size of the white pixel in one dot having a stripe structure as in the first embodiment, the data line separating each pixel is shifted to red, The white pixels are reduced by increasing the area of the green and blue pixels.

In contrast, as shown in FIG. 3B, without adjusting the area of each pixel according to the movement of the day line, the size of the wiring (for example, data wiring, gate wiring, etc.) provided around each pixel is adjusted. Adjust the area of the pixel. That is, by increasing the size of the wiring formed around the white pixel to reduce the area, the area in which light of the white pixel is relatively transmitted is reduced. At this time, the area where the data line and the gate line of each pixel cross each other acts as a capacitive load, so it is preferable not to increase the area.

In this third embodiment, as the area of the white pixel is reduced, the area of the other pixel is increased, so that the luminance increase effect of the white pixel can be obtained while maintaining the color density.

4A and 4B illustrate a pixel array structure of a liquid crystal display according to a fourth exemplary embodiment of the present invention.

As shown in FIGS. 4A and 4B, in the liquid crystal display according to the fourth embodiment of the present invention, red, green, blue, and white pixels are adjacent to each other over two pixel rows as in the second embodiment. It consists of a checkerboard structure arranged. Here, the pixels are arranged in a checkerboard structure in which green and red pixels arranged adjacent to one pixel row and blue and white pixels arranged adjacent to each other adjacent pixel row are used as one dot. Unlike the second embodiment, the area of the white pixel is smaller than that of the other pixels.

More specifically, as shown in Fig. 4A, as in the third embodiment, the white pixels are reduced by shifting the data lines separating each pixel to increase the area of the red, green, and blue pixels. At this time, as the area of the white pixel is reduced while the area of one dot is fixed, the area of the other pixel is relatively increased. Therefore, in this case, the ratio of increasing the area of the red, green, and blue pixels, and the ratio of decreasing the area of the color pixels are determined in consideration of the amount of light of the backlight and the color temperature as the final target. For example, since blue pixels do not affect visibility relative to other color pixels, as shown in FIG. 4A, in the pixel arrangement structure described in the second embodiment such that the area of the blue pixels is increased, the green pixels and the blue pixels are increased. The area of the white pixel is reduced by changing the position of the pixel and adjusting the position of the data line.

Alternatively, as shown in FIG. 4B, as in the third embodiment, the area of the white pixel can be adjusted by adjusting the size of the wiring (eg, data wiring, gate wiring, etc.) provided around each pixel. have. Even in this case, the area of the region where the data wiring and the gate wiring of each pixel cross each other is not changed.

Next, the structure of the thin film transistor substrate of the liquid crystal display according to the fourth exemplary embodiment having the pixel array structure described above will be described in more detail.

5 is a detailed pixel structure diagram of a thin film transistor substrate of a liquid crystal display device according to a fourth exemplary embodiment of the present invention having the pixel arrangement above. FIG. 6 is a cross-sectional view of the TFT substrate for a liquid crystal display device taken along the line IV-IV ′ in FIG. 5.

As shown in FIG. 5, in the thin film transistor substrate according to the fourth embodiment of the present invention, green and red pixels are arranged adjacent to one pixel row, and adjacent to each other pixel row, similarly to FIG. 4B. The blue and white pixels are arranged. In this case, the green and blue pixels are located in the same column, and the red and white pixels are located in the same column. The area of the white pixel is reduced so that the aperture ratio of the white pixel is smaller than that of the other pixels. Here, as shown in FIG. 4B, the area of the data line and the gate line is increased to reduce the aperture ratio of the white pixel.

Specifically, as shown in FIG. 5, in the horizontal direction, one gate line (or a scan signal line 121) for transmitting a scan signal or a gate signal is formed in the pixel row direction, one for each pixel row, and the vertical direction. The data line 171, which transmits a data signal and crosses the gate line 121 and defines a unit pixel, is insulated from the gate line 121 and is formed in a column of pixels (B, R, G, ...). . Here, the gate electrode 123 connected to the gate line 121, the source electrode 173 connected to the data line 171, and the gate electrode at a portion where the gate line 121 and the data line 171 cross each other. A thin film transistor including a drain electrode 175 and a semiconductor layer 150 formed opposite to the source electrode 173 with respect to 123 is formed. Each pixel includes a gate line 121 through a thin film transistor. ) And a pixel electrode 190 electrically connected to the data line 171.                     

In addition, a conductive capacitor pattern 177 is formed on the same layer as the gate line 121 to overlap the pixel electrode 190 to form a storage capacitor, and the conductive capacitor pattern 177 is a gate line. It is formed on the 121, and is connected to the pixel electrode 190 through the contact hole 187. The width of the portion where the conductive capacitor conductor pattern 177 is formed in the gate line 121 is wider than the width of the portion where the conductive capacitor conductor pattern 177 is not formed in order to ensure sufficient holding capacity. It is.

The data line is also connected to the drain electrode 175. In addition, a contact hole 187 of the passivation layer 180 (see FIGS. 5 and 6) for connecting the pixel electrode 190 and the data line is formed on the conductive pattern 177 for the storage capacitor. At the ends of the data line 171, data pads 179 for receiving an image signal from the outside and transmitting the image signal to the data line 171 are connected. In this structure, each pixel column receives an image signal through a data pad connected to the data line 171.

In more detail, the gate wiring is formed on the insulating substrate 100. The gate line is connected to the gate line 121 and the gate line 121 which are formed one by one for each pixel row in the pixel row direction, so that the gate pad receives a gate signal from the outside and transfers the gate signal to the gate line ( 125 and a gate electrode 123 of the thin film transistor connected to the gate line 121. Here, the gate wiring has a taper angle, for example, the taper angle may be 30 ° to 90 °.                     

On the substrate 100, a gate insulating layer 140 made of silicon nitride (SiN _x ) covers the gate wiring.

A semiconductor layer 150 made of a semiconductor such as amorphous silicon is formed in an island shape on the gate insulating layer 140 of the gate electrode 125, and silicide or n-type impurities are doped with high concentration on the semiconductor layer 150. Resistive contact layers 160 made of a material such as n + hydrogenated amorphous silicon are formed, respectively. Alternatively, the semiconductor layer 150 may be formed along the shape of the data line 171.

The data line is formed on the ohmic contact layer 160 and the gate insulating layer 140. The data wires are formed in the vertical direction and intersect the gate lines 121 to define pixels, and the source lines 173 branching from the data lines 171 and the data lines 171 and extending to the upper portion of the ohmic contact layer 160. ), Which is connected to one end of the data line 171 and is separated from the data pad 179 and the source electrode 173 for receiving an image signal from the outside, and is opposite to the source electrode 173 with respect to the gate electrode 123. The drain electrode 175 is formed on the ohmic contact layer 160.

The passivation layer 180 is formed on the data line and the semiconductor layer 150 that does not cover the data line. In the passivation layer 180, contact holes 185 and 189 respectively exposing the drain electrode 175 and the data pad 179 are formed, and the contact holes 182 exposing the gate pad 125 together with the gate insulating layer 140. Is formed. The passivation layer 180 may be formed of a SiNX single layer or an organic layer, and may also be formed of an organic layer / SiNX.

On the passivation layer 180, a pixel electrode 190 electrically connected to the drain electrode 175 through the contact hole 185 and positioned in the pixel is formed. In addition, an auxiliary gate pad 95 and an auxiliary data pad 97 connected to the gate pad 125 and the data pad 179 are formed on the passivation layer 180 through the contact holes 182 and 189, respectively.

5 and 6, the pixel electrode 190 overlaps with the gate line 121 to form a storage capacitor. When the storage capacitor is insufficient, the pixel electrode 190 is disposed on the same layer as the gate lines 121, 125, and 123. It is also possible to add a storage capacitor wiring.

On the other hand, the structure of the thin film transistor technology of the liquid crystal display device according to the first to the third embodiments described above, those skilled in the art and the pixel arrangement described above, and the structure described in the fourth embodiment (Figs. 5 and 6) Since it can be easily devised, detailed description is omitted.

Next, a driving device of the liquid crystal display device according to the first to fourth embodiments described above will be described.

7 is a block diagram of a driving device of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 7, the driving device of the liquid crystal display according to the exemplary embodiment of the present invention includes a gate driver 200 and a data driver 300 for supplying a gate signal and a data signal to the liquid crystal panel 100. And a driving voltage generator 400, a gray voltage generator 500, and a timing controller 600.                     

The liquid crystal panel 100 may include a plurality of signal lines G ₁ -G _n , D ₁ -D _m and a plurality of pixels connected thereto in an equivalent circuit, and each pixel includes the signal lines G ₁ -G _n. And a switching element Q connected to D ₁ -D _m , a liquid crystal capacitor C _lc , and a storage capacitor C _st connected thereto. The signal lines G ₁ -G _n , D ₁ -D _m transmit a gate signal (or called a scan signal), and a plurality of gate lines (or called scan signal lines) extending in a row direction (G ₁ -G) _n ) and a data line D ₁ -D _m which transmits a data signal (or called a picture signal) and extends in the column direction. The switching element Q is a three-terminal element, the control terminal of which is connected to the gate line G ₁ -G _n , the input terminal of which is connected to the data line D ₁ -D _m , and the output terminal of the liquid crystal capacitor ( C _lc ) and one terminal of the holding capacitor C _st . Meanwhile, in order to implement color display, a red, green, or blue color filter is provided in an area corresponding to the pixel electrode of each pixel, and the color filter is not provided in the pixel corresponding to white. Each pixel having such a structure can be arranged in the same manner as in the first to fourth embodiments described above, and four pixels of red, green, blue and white form one dot.

The timing controller 600 controls the R, G, and B data signals, a vertical sync signal Vsync as a frame discrimination signal, a horizontal sync signal Hsync as a row discrimination signal, and a clock signal from an image source (not shown) external to the LCD module. The digital signal outputs a digital signal for driving the gate driver 200 and the data driver 300.

The timing signal output from the timing controller 600 to the gate driver 200 includes a vertical start signal STV for instructing the gate on voltage to be applied to the gate line, and the gate on voltage. A gate clock signal (CPV signal) for sequentially applying to each gate line, a gate on enable signal OE for enabling the output of the gate driver 200, and the like.

The timing signal output from the timing controller 600 to the data driver 300 includes digital data signals R (0: N) and G (0: N) from an external data source (for example, a graphics controller). ), A horizontal start signal (Hstart) for instructing B (0: N)] to be input to the data driver 300, and a signal for instructing the panel to apply a data signal converted to analog in the data driver 300 ( Hereinafter referred to as " LOAD signal " and the horizontal clock signal HCLK for data shift in the data driver 300. In particular, in the embodiment of the present invention, the timing controller 600 converts an image signal to be applied, that is, a digital data signal [R, G, B] into [R, G, B, W] and outputs it.

8 shows a detailed structure of the timing controller 600 according to the embodiment of the present invention.

As illustrated in FIG. 8, the timing controller 600 includes a data converter 601 for converting RGB applied from the outside into RGBW, a data optimizer 602 for optimizing RGBW output from the data converter, and optimized output. The data generator 603 outputs the RGBW to the data driver 300 according to the applied clock signal OPC, and the clock generator 604 generates the clock signal OPC and provides the generated clock signal to the data output unit 603. ).

The timing controller 600 does not include only the above-described elements, and further includes a plurality of elements for processing and generating various control signals for driving a general liquid crystal display, and for processing input image data. can do. Since these functions and the components that perform them are already known techniques, detailed descriptions are omitted here.

Based on this structure, the operation of the driving apparatus of the liquid crystal display according to the embodiment of the present invention will be described.

A plurality of control input signals for controlling the RGB data signals R, G, B and their display from an external graphic controller (not shown), for example, a vertical sync signal, a horizontal sync signal, and a clock signal ( When the IPC) or the like is input, the timing controller 600 generates a plurality of gate control signals and data control signals based on the control input signal, and processes the RGB data signals to display one dot as in the embodiment of the present invention. Generate RGBW data to do this.

In detail, the data converter 601 of the timing controller 600 converts input RGB data into RGBW data through calculation. In this data conversion method, a white component is extracted from binarized R, G, B, and data, and a half-tone process is used to generate RGBW, and the minimum value of RGB data increments is increased. A method of subtracting from the value and using it as an input value of the white component and using an RGB increment other than the white subtraction amount as an RGB output signal may be used. Here, the method of converting the RGB data into the RGBW data is already known, and thus detailed description thereof will be omitted.

At this time, one RGBW data is not generated from the RGB data by the data converter 601, and a plurality of RGBW data are generated. Accordingly, the data optimizer 602 optimizes the RGBW data according to the characteristics of the current liquid crystal display among the plurality of RGBW data. For example, a method of expressing white pixels with 127 gray levels includes (W = 0, RGB = 255), (W = 1, RGB = 254),... , (W = 255, RGB = 0), and so on. In the present invention, the redundancy of the gray scale representation method is used to improve the performance of the liquid crystal display, and the data is selectively optimized according to what performance is to be improved. In the embodiment of the present invention, the RGBW optimization is selectively performed according to the case where the resolution is to be improved, when the power consumption is to be reduced, when the values of RGB and W are to be averaged.

First, the data optimizer 602 receives RGBW data output from the data converter 601 and divides the RGBW data into an achromatic component W ₀ and a color component R ₀ , G ₀ , B ₀ as follows. Each achromatic component and color component can be represented as follows.

W ₀

R ₀ = R-Min (R, G, B)

G ₀ = G-Min (R, G, B)

B ₀ = B-Min (R, G, B)

Next, when the resolution of the liquid crystal display is to be improved, the difference between the gray level of the W pixel and the gray level of the RGB pixel is maximized.

For example, in the case of a twisted nematic (TN) liquid crystal display, the change in gray level inversion may be alleviated as the difference between gray levels represented by the white pixel and the RGB pixel is maximized. In other words, when the W pixel is to be expressed with 127 gradations, it is better to set (W = 0, RGB = 255) or (W = 255, RGB = 0) rather than (W = 127, RGB = 127). It is much more advantageous from the standpoint of such. Accordingly, when the current liquid crystal display is in the TN mode, the RGBW data output from the data converter 601 is processed to maximize the gray level difference between the W pixel and the RGB pixel. In this case, as a method of maximizing the gradation difference, the difference with the RGB pixel may be maximized by maximizing the gradation value of the W pixel or by maximizing the gradation value of the W pixel.

In this case, the gradation value of the W pixel is made maximum or the gradation value of the W pixel is made minimum, depending on the efficiency of power consumption. Specifically, when the liquid crystal display device is used in a mobile phone or the like, it is important to reduce power consumption as much as possible. In order to reduce power consumption as much as possible, it is desirable to apply a high voltage to the W pixel and a low voltage to the RGB pixel. For example, when expressing 127 grayscales in a normally black mode, (W = 255, RGB = 0) is advantageous in terms of power consumption reduction, and vice versa in a normally white mode. It is more advantageous to set (W = 255, RGB = 0).

Accordingly, in order to reduce power consumption as much as possible, the achromatic component (W ₀ ) and the color components (R ₀ , G ₀ , B ₀ ) calculated from the RGB data are calculated as follows. Branches yield RGBW data.

W '= Min (W ₀ -255)

R '= R ₀ + Max (0, W ₀ -255)

G '= G ₀ + Max (0, W ₀ -255)

B '= B ₀ + Max (0, W ₀ -255)

On the contrary, in the case of calculating RGBW data having the minimum value of the W pixel, the achromatic component W ₀ calculated from the RGB data and the color components R ₀ , G ₀ , B ₀ are calculated as follows. Yields RGBW data having the minimum value.

W '= W _0- {255-Max (R ₀ , G ₀ , B ₀ )}

R '= R ₀ + {255-Max (R ₀ , G ₀ , B ₀ )}

G '= G ₀ + {255-Max (R ₀ , G ₀ , B ₀ )}

B '= B ₀ + {255-Max (R ₀ , G ₀ , B ₀ )}

On the other hand, in the case of a liquid crystal display device which does not need to consider side visibility or power consumption, it is better to set the image to a similar value than to maximize the difference between W and RGB. In the case of a low-resolution liquid crystal display device (e.g., a liquid crystal display device for a TV), since the pixels may be seen separately, a similar distribution of the intensity of W and RGB gives a uniform feeling. The image quality is better. At this time, since there is no color filter in the W pixel, more light is transmitted per unit area. Therefore, it is more advantageous for the image quality improvement that the W gray value is relatively lower than the same gray value of W and RGB.

In the case where the values of W and RGB are to be equal, RGBW data is calculated by calculating achromatic components W ₀ and color components R ₀ , G ₀ , B ₀ calculated from RGB data as follows. .

W '= {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2

R '= R ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2

G '= G ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2

B '= B ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2

On the other hand, in order to obtain a relatively low gray level value of W in order to obtain better image quality, another method is used without calculating RGBW according to Equation 4 above.

In addition to the above-described optimization method of RGBW, another optimization method may be used, and the RGBW value is calculated in consideration of the maximum value (for example, 255) that the RGBW can represent.

When the RGBW is selectively generated and output by the data optimizer 602 as described above, the data output unit 603 converts the RGBW according to the clock signal OPC provided from the clock generator 604. )

In the exemplary embodiment of the present invention, an apparatus for processing data according to four color pixels of RGBW may be used as the data driver 300. However, in consideration of an increase in manufacturing cost, the data driver 300 processes data of conventional RGB three color pixels. It is more preferable to use a data driver. In this case, the data optimizer 602 reorganizes RGBW data and outputs the RGBW data to the data driver 300 as follows.

In the case of processing the RGBW data, the amount of data is about one third more than in the case of the processing of the conventional RGB data, so the pixel clock, that is, the clock signal, must be increased by that much. Accordingly, in the exemplary embodiment of the present invention, the clock generator 604 processes the clock signal IPC applied from the outside to generate a clock signal OPC of 4/3 times.

FIG. 9 shows timing charts for outputting RGBW data when RGBW pixels are arranged in the form of vertical stripes on the liquid crystal panel as in the first and third embodiments.

As shown in FIG. 9, RGBW optimized from the data optimization unit 602 is sequentially input (R ₀ G ₀ B ₀ W ₀ , R ₁ G ₁ B ₁ W ₁ , R ₂ G ₂ B ₂ W ₂ When the clock signal IPC is input from the outside, the data output unit 603 has a period that is 4/3 times the clock signal OPC input from the clock generator 604, that is, the input clock signal. RGB data input according to the clock signal (OPC) is converted into R ₀ G ₀ B ₀ , W ₀ R ₁ G ₁ , B ₁ W ₁ R ₂ , G ₂ B ₂ W ₂ ,. Output in order of.

On the other hand, when the RGBW pixels are arranged in the form of a checkerboard structure on the liquid crystal panel as in the second and fourth embodiments above, the RGBW constituting one dot is displayed over two gate lines. The pixel data for displaying the dot is stored and then output RGBW data as follows.

Specifically, R ₀ G ₀ B ₀ W ₀ , R ₁ G ₁ B ₁ W ₁ , R ₂ G ₂ B ₂ W ₂ ,. When the RGBW data is input in the order of, it is stored, and G ₀ R ₀ G ₁ , R ₁ G ₂ R ₂ ,... , R _N-2 G _N-1 R _N-1 is output first, and then B ₀ W ₀ B ₁ , W ₁ B ₂ W ₂ ,... , W _N-2 B _N-1 W _N-1 In this case, the data output unit 603 may include a line buffer to store the applied RGBW data.

As described above, the RGBW data processed by the timing controller 600 is provided to the data driver 300, and the data driver 300 corresponds to grayscale image data applied in synchronization with the horizontal start signal Hstart, respectively. The voltage is converted into a voltage and then applied to the switching element of the liquid crystal panel 100, that is, the source electrode of the TFT according to the load signal applied thereto. The gate driver 200 applies a gate-on voltage to the gate electrode of the TFT in synchronization with the gate clock signal output from the timing controller 600, and as a result, the data voltage applied to the source electrode is charged in the pixel electrode.

Therefore, the alignment state of the liquid crystal varies according to the potential difference between the data voltage supplied to each pixel electrode and the voltage of the common electrode, and accordingly, the amount of light transmitted varies so that a desired image is displayed.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

As described above, according to the present invention, by displaying an image using four pixels of RGBW, the light efficiency can be further improved. Accordingly, power consumption can be further reduced.

In addition, by appropriately adjusting the area of the W pixel in RGBW, it is possible to maintain color density characteristics with high luminance.

In addition, since optimized RGBW data can be calculated from the RGB data, the power consumption of the liquid crystal display device can be reduced efficiently, and the image quality can be improved by alleviating the characteristic change during gray level inversion.                     

In addition, by reorganizing the RGBW data to supply the RGBW data to the liquid crystal panel using an existing driving circuit (eg, data driver, gate driver, etc.), the cost of using the new driving circuit can be reduced.

Claims (12)

A pixel array in which red, blue, green, and white pixels are arranged in a row direction, only pixels of the same color are arranged in a column direction, and an area of the white pixel is smaller than that of the remaining pixels; A gate line disposed in the row direction and transferring a gate signal to the pixel; A data line arranged to insulate and cross the gate line in the column direction, and to transmit a data signal to the pixel; Pixel electrodes formed in the pixels in the row and column directions and to which the data signal is transmitted; And Switching elements formed in the pixels in the row and column directions, respectively, and including a gate electrode connected to the gate line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode. Including; And a portion of at least one of the gate line and the data line adjacent to the white pixel is wider than the other gate line and the data line. Green, red, blue, and white pixels are arranged adjacent to each other over two pixel rows, wherein the four pixels form one dot for displaying an image, and the area of the white pixel is larger than that of the remaining pixels. Small pixel array; A gate line disposed in a row direction and transferring a gate signal to the pixel; A data line arranged to insulate and cross the gate line in a column direction, and to transmit a data signal to the pixel; Pixel electrodes formed in the pixels in the row and column directions and to which the data signal is transmitted; And Switching elements formed in the pixels in the row and column directions, respectively, and including a gate electrode connected to the gate line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode. Including; And a portion of at least one of the gate line and the data line adjacent to the white pixel is wider than the other gate line and the data line. The method according to claim 1 or 2 The wide portion is a portion that does not intersect other portions of the gate line and the data line. delete The method according to claim 1 or 2 And the green pixel is not disposed adjacent to the white pixel. delete A plurality of gate lines, a plurality of data lines insulated from and intersecting the plurality of gate lines, and a switching element formed in a region where the plurality of data lines and the gate lines intersect, and connected to the gate lines and the data lines, respectively. In the driving apparatus of the liquid crystal display device comprising a plurality of pixels arranged in a matrix form, each pixel is one of red, green, blue and white pixels, wherein the red, green, blue and white pixels form a dot , A gate driver supplying a gate voltage to the gate line; A data driver supplying a data voltage corresponding to the RGBW image signal applied to the day line; And A timing controller which converts an RGB image signal applied from the outside into an RGBW image signal and optimizes the converted RGBW image signal to provide the data driver. Including; The timing controller A data converter for converting an RGB image signal applied from the outside into an RGBW image signal; A data optimizer for optimizing the RGBW image signal; A data output unit configured to output the optimized RGBW image signal to the data driver according to a clock signal applied thereto; And A clock generator which generates the clock signal and provides the clock signal to the data output unit; Driving device for a liquid crystal display comprising a. The method of claim 7, wherein The data optimization unit The achromatic component W ₀ and the color component R ₀ , G ₀ , B ₀ are separated from the RGBW image signal output from the data converter, and the achromatic component W ₀ is maximized as follows. A drive device of a liquid crystal display device for optimizing an image signal. W '= Min (W ₀ , 255) R '= R ₀ + Max (0, W ₀ -255) G '= G ₀ + Max (0, W ₀ -255) B '= B ₀ + Max (0, W ₀ -255) W ', R', G ', and B': optimized values The method of claim 7, wherein The data optimization unit The achromatic component W ₀ and the color component R ₀ , G ₀ , B ₀ are separated from the RGBW image signal output from the data converter, and the achromatic component W ₀ is minimized as follows. A drive device of a liquid crystal display device for optimizing an image signal. W '= W _0- {max-Max (R ₀ , G ₀ , B ₀ )} R '= R ₀ + {max-Max (R ₀ , G ₀ , B ₀ )} G '= G ₀ + {max-Max (R ₀ , G ₀ , B ₀ )} B '= B ₀ + {max-Max (R ₀ , G ₀ , B ₀ )} W ', R', G ', and B': optimized values The method of claim 7, wherein The data optimization unit The achromatic component W ₀ and the color components R ₀ , G ₀ , B ₀ are separated from the RGBW image signal output from the data converter, and the achromatic component W ₀ and the color components R ₀ , G are separated. ₀ , B ₀ ) equalization to optimize the RGBW image signal. W '= {W ₀ + Average (R ₀ , G ₀ , B ₀ )} / 2 R '= R ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2 G '= G ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2 B '= B ₀ + {W ₀ -Average (R ₀ , G ₀ , B ₀ )} / 2 W ', R', G ', and B': optimized values The method of claim 7, wherein The data output unit, And driving the RGBW image signal according to the clock signal and outputting the data to the data driver in units of three pixels. delete

Images