KR20080000992A - Display device - Google Patents

Abstract

A display device is provided to design two pixel electrodes, which correspond to two color pixels among three color pixels constituting each dot, and to have different polarities in every frame, thereby suppressing vertical line defects. A display device comprises a display panel and a driving part for driving the display panel. The display panel includes dots each consisting of at least three color pixels, and a plurality of pixel electrodes corresponding to the color pixels. Each of the pixel electrodes is divided into at least two sub-pixel electrodes. At least two pixel electrodes corresponding to at least two color pixels among the three color pixels have different polarities in every frame.

Description

 Display Device

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1 is a view for explaining the principle of the vertical line phenomenon in the display device of the 120hz S-PVA system.

FIG. 2 is a diagram showing an arrangement of color pixels employed in a 120 hz S-PVA display device. FIG.

3 is a diagram illustrating voltage states of a specific dot shifted for each frame and pixel electrodes for each frame corresponding to the specific dot.

4 is a block diagram of a display device to which a 120hz S-PVA method is applied according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of one pixel of the display panel illustrated in FIG. 1.

FIG. 6 is an equivalent circuit diagram of one pixel area of the display panel illustrated in FIG. 3.

7 is a diagram illustrating a display panel having a color pixel arrangement structure applied to the display device according to the present invention.

8 is a diagram illustrating a voltage state of a specific dot shifted for each frame and a pixel electrode for each frame corresponding to the specific dot in the display device according to the exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: display panel 130: pixel area

200: timing controller 400: data driver

500: gate driver

R: Red Color G: Green Color

B: blue color pixel PX: pixel electrode

PXa: first subpixel electrode PXb: second subpixel electrode

Gdot: Dot Group

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a liquid crystal display device (LCD) driven at 120 hz.

In addition to a display device using a cathode ray tube, one of the important fields of an image display device is a display device. The display device is a display device in which liquid crystal is injected between two substrates (glass substrates) bonded to each other with a predetermined space. The display device can control the amount of light transmitted to the substrate by applying an electric field to the liquid crystal and adjusting the intensity of the electric field. In this control manner, a desired image signal is displayed.

In recent years, display devices have tended to be enlarged in order to express more image information. In a display device employing a large-area display panel, vertical streaks occur when displaying a still image (eg, a photographic image), especially when the still image is moved.

Accordingly, an object of the present invention is to provide a display device capable of improving the vertical line phenomenon.

According to an aspect of the present invention, there is provided a display device including a display panel including dots consisting of at least three color pixels and a plurality of pixel electrodes corresponding to each of the color pixels. It includes a drive unit. Here, the dots have different color pixel arrangements in a row direction and are formed of a plurality of dot groups having the same color pixel arrangements in a column direction.

Each of the plurality of dot groups is adjacent to one side of the first dot array arranged in the order of red, green, and blue, and the second dot array arranged in the order of green, blue, and red, and adjacent to one side. And a third dot string adjacent to the other side of the first dot string and arranged in the order of blue, red, and green. The pixel electrode includes a first subpixel electrode and a second subpixel electrode.

In this case, a first data voltage is applied to the first subpixel electrode, and a second data voltage having a polarity opposite to the first data voltage is applied to the second subpixel electrode. The voltage levels of the first data voltage and the second data voltage are different from each other.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings. In understanding the drawings, it should be noted that like parts are intended to be represented by the same reference numerals as much as possible. In addition, in the following description, numerous specific details, such as specific processing flows, are described to provide a more general understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without these specific details. Incidentally, detailed descriptions of well-known functions and configurations that are determined to unnecessarily obscure the subject matter of the present invention will be omitted.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the present invention, the display device uses a vertical alignment mode of the liquid crystal to improve side visibility. In the vertical alignment mode, liquid crystal molecules are vertically distributed in a state where no electric field is applied, and when a voltage is applied to the liquid crystal, a liquid crystal is arranged perpendicularly to the electric field direction.

Among these vertical alignment modes, 120 hz Super-Patterned Vertical Alignment (S-PVA) divides one pixel into two sub-pixels to control the filling rate of the liquid crystal for each sub-pixel differently. The difference in charge rate of the two subpixels induces a difference in transmittance, thereby improving side visibility of the display device.

1 is a view for explaining the principle of occurrence of the vertical line phenomenon in the display device of the 120hz S-PVA system. In FIG. 1, the same pixel electrode inverted with different polarities is shown, and this pixel electrode is assumed to be an electrode representing one red (R) color pixel.

As shown in FIG. 1, in the display device to which the 120 hz S-PVA method is applied, two data voltages (+, −) having opposite polarities are applied to one pixel electrode. The two data voltages applied to one pixel electrode are positive data voltages for the common voltages for each frame, and negative data voltages for the common voltages. Is reversed. In this case, the two data voltages (+,-) and the inverted two data voltages (-, +) have the same potential difference based on the common voltage to have the same luminance.

However, due to the wiring resistance of the common voltage line guiding the common voltage, the variation of the common voltage and the kick back deviation according to the resistance, the common voltage in the entire area of the display panel is not centered on the two data voltage levels. impossible.

In this case, when the level of the common voltage changes, the luminance corresponding to the pixel electrode shown on the left side of FIG. 1 and the pixel electrode shown on the right side of FIG. 1 is expressed differently. For the same pixel electrode (same color pixel), the voltage application state on the left shown in FIG. 1 and the voltage application state on the right shown in FIG. 1 express different luminance.

In the 120 hz S-PVA display device, the above two voltage applied states are repeatedly displayed 120 times per second for each pixel electrode. Assuming that the voltage application state on the left side shown in FIG. 1 represents the bright luminance, and the voltage application state on the right side shown in FIG. 1 represents the dark luminance, as the bright luminance and the dark luminance are repeated 120 times per second. Visually, moderate luminance is perceived.

When a general image is displayed, a large problem does not occur, but when a still image that is maintained at the same brightness is moved on the display screen, an unexpected vertical line phenomenon is caused.

This vertical line phenomenon can be found in the arrangement of the color pixels on the upper substrate.

FIG. 2 is a diagram showing an arrangement of color pixels employed in a 120 hz S-PVA display device. FIG.

As illustrated in FIG. 2, a plurality of dots are arranged in a matrix form on the display panel, and each dot is defined as a red (R) pixel, a green (G) pixel, and a blue (B) color pixel.

Each of the dots is arranged in the order of red (R) green (G) blue (B) in the row direction. Therefore, the dots arranged in a matrix form have the same color pixel arrangement structure in the column direction.

When a still image is moved from one side of the display screen to the other side in the display device having the color pixel arrangement structure, a vertical line phenomenon occurs.

3 is a diagram illustrating a movement of a specific dot representing a still image for four consecutive frames. For convenience of explanation, only one color pixel line is shown for each frame.

When the still image moves from left to right on the display screen, as shown in FIG. 3, the specific dot DOT1 representing the still image is shifted from left to right on the display screen by one dot for every frame. (shift). At this time, when the voltage applied state of the shifted dots DOT1 is carefully examined, as illustrated in FIG. 3, each color pixel of the dot is displayed on the display screen every frame at the same voltage state. That is, the still image will move to the left on the right side of the display screen while maintaining a specific luminance. The specific luminance may be represented by light to dark luminance. In this case, when the display device is driven by the line inversion method in the column direction, the specific luminance appears in the form of a line, which causes a vertical line phenomenon.

Accordingly, the display device to which the 120-Hz S-PVA method is applied according to the present invention proposes the following improvements to improve the vertical line phenomenon.

4 is a block diagram of a display device to which a 120 hz S-PVA method is applied according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating a configuration of one pixel of the display panel illustrated in FIG. 1.

Referring to FIG. 4, the display device 10 includes a display panel 100, a timing controller 200, a gray voltage generator 300, a data driver 400, and a gate driver 500.

The display panel 100 includes a plurality of data line pairs D1a to Dma and D1b to Dmb and a plurality of gate lines G1 to Gn that are insulated from and cross the plurality of data line pairs D1a to Dma and D1b to Dmb. It includes. The data line pairs D1a and D1b and the gate line G1 may be defined as one unit pixel area, and the display panel has a plurality of unit pixel areas arranged in a matrix form.

Referring to FIG. 5, each unit pixel region 130 of the display panel 100 includes lower and upper substrates 110 and 120 facing each other, and a liquid crystal interposed between the lower and upper substrates 110 and 120. Layer (not shown).

Each unit pixel area 130 includes one pixel electrode PE formed on the lower substrate 110 and one color pixel CE formed on the upper substrate 120. The pixel electrode PE includes two subpixel electrodes PEa and PEb each including a first subpixel electrode PEa and a second subpixel electrode PEb.

Each of the first and second subpixel electrodes PEa and PEb has liquid crystal capacitors CLCa and CLCb, and each of the liquid crystal capacitors CLCa and CLCb includes the subpixel electrodes PEa and PEb of the lower substrate 110. The common electrode (not shown) of the upper substrate 120 has two terminals, and the liquid crystal layer between the two terminals functions as a dielectric. The first and second subpixel electrodes PEa and PEb are separated from each other and form one pixel electrode PE. The common electrode CE is formed on one surface of the upper substrate 120 and receives a common voltage VCOM.

The one color pixel CE is a color filter corresponding to any one of red (R), green (G), and blue (B) color pixels corresponding to three primary colors of light, and is formed on the lower substrate 110. It is formed on the upper substrate 120 to correspond to one pixel electrode PE 1: 1. In this structure, by adjusting the light transmittance of the liquid crystal layer of each pixel area, various kinds of colors can be expressed by a combination of red (R), green (G), and blue (B) color pixels having different brightnesses.

Referring back to FIG. 4, the timing controller 200 adjusts and outputs the image data signals R, G, and B to match the timings required by the data drivers 400a and 400b and the gate driver 500. In addition, the timing controller 200 outputs first and second control signals CNTL1 and CNTL2 for controlling the data driver 400 and the gate driver 500. The first control signal CNTL1 includes a horizontal synchronization start signal STH, a data output signal TP, and the like. The second control signal CNTL2 includes a scan start signal STV, a gate clock signal CPV, an output enable signal OE, and the like.

The gray voltage generator 300 generates a plurality of gray voltages related to the transmittance of the pixel area 130 and provides them to the data driver 400 described below.

The data driver 400 may respond to data lines of the display panel 100 in response to the first control signal CNTL1 applied from the timing controller 200 and the gray voltage applied from the gray voltage generator 300. D1a to Dma and D1b to D1m).

The data driver 400 receives the first control signal CNTL1 and the image signal DAT for one pixel row from the timing controller 200, and outputs each image signal among the gray voltages generated by the gray voltage generator 300. Select the gradation voltage corresponding to (DAT). Thereafter, the data driver 400 converts the selected gray voltage into a corresponding data voltage and applies the same to the corresponding data lines D1a, D1b, D2a, D2b, ..., Dma, and Dmb.

The gate driver 500 responds to the second control signal CNTL2 input from the timing controller 200 and the gate-on voltage VON and the gate-off voltage VOFF output from the driving voltage generator (not shown). The gate lines G1 to Gn of the display panel 100 are driven. The gate driver 500 applies a gate voltage to each pixel region 130 through the gate lines G1 to Gn to 'turn on' or 'turn off' the thin film transistors constituting each pixel region 130. Let's do it.

FIG. 6 is an equivalent circuit diagram of one pixel area of the display panel illustrated in FIG. 3.

Referring to FIG. 6, one pixel PX includes three data lines D1a and D1b, a common gate line G1, and first and second subpixel electrodes PXa and PXb.

The first subpixel electrode PXa includes the first thin film transistor Ta and the first liquid crystal capacitor CLCa. A gate of the first thin film transistor Ta is connected to the common gate line G1, a source is connected to the first data line D1a, and a drain is connected to one end of the first liquid crystal capacitor CLCa.

The second subpixel electrode PXb includes the second thin film transistor Tb and the second liquid crystal capacitor CLCb. A gate of the second thin film transistor Tb is connected to the common gate line G1, a source is connected to the second data line D1b, and a drain is connected to one end of the second liquid crystal capacitor CLCb.

The first and second data lines D1a and D1b shown in FIG. 6 are connected to the data driver 400 shown in FIG. 4, so that a first data voltage is applied to the first subpixel electrode, and a second subpixel is provided. The second data voltage is applied to the electrode.

In this case, the first data voltage has a polarity opposite to that of the second data voltage. Here, as described above, the first data voltage and the second data with respect to the common voltage due to the wiring resistance of the VOCM line for guiding the common voltage, the variation of the common voltage, the kick back deviation, etc. according to the resistance. The voltage levels of the voltages are different.

The gate line G1 is connected to the gate driver 500 illustrated in FIG. 4, and gate voltages applied through the gate line G1 are first and second of the first and second subpixels PXa and PXb. The thin film transistors Ta and Tb are 'turned on' at the same time.

A display device according to an exemplary embodiment of the present invention including the above components is designed to have a color pixel arrangement structure as follows.

7 is a diagram illustrating a display panel having a color pixel arrangement structure applied to the display device according to the present invention.

Referring to FIG. 7, a plurality of dots DOT1 arranged in a matrix form are formed on the display panel 100. Each of the plurality of dots DOT1 has at least three color pixels. Preferably, the color pixels are composed of red (R) color green (G) color and blue (B) color pixels.

The dots have different color pixel arrangements in the row direction and are composed of a plurality of dot groups Gdots having the same color arrangements in the column direction. Specifically, each of the plurality of dot groups Gdot includes a first dot string, a second dot string, and a third dot string.

The first dot strings have the same color pixel arrangement in the column direction, and are arranged in the order of red (R), green (G), and blue (B) pixels in the row direction. The second dot row is adjacent to one side ('right' in this embodiment) around the first dot row, and the green (G) color, the blue (B) color, and the red (R) color pixel are in this order. Adjacent to the other side (in this embodiment, 'left') around the second dot array and the first dot array arranged in a blue (B) color, red (R) color, and green (G) color. And a third dot string arranged in the order of the pixels. In the display panel 100 according to an exemplary embodiment, a plurality of dot groups Gdots having the color pixel arrangement structure as described above are formed in a row direction.

On the other hand, by employing the color pixel arrangement structure as described above, the display device according to the present invention can improve the vertical line phenomenon that occurs when the still image is moved on the display screen. A detailed description thereof will be described below with reference to FIG. 8.

8 is a diagram illustrating a voltage state of a specific dot shifted for each frame and a pixel electrode for each frame corresponding to the specific dot in the display device according to the exemplary embodiment of the present invention.

In FIG. 8, four consecutive frames (i frame, j frame, k frame, and l frame) are shown, and only one color pixel row is shown for each frame for convenience of description. It is assumed that any still image can be represented by one dot DOTi, and the still image is moved from left to right on the display screen.

In the i frame represented by being arranged in the order of the blue color (B), the red color (R), and the green color (G), the dot (DOTi) is the next frame, i.e., j frame. In the dot j frame adjacent to the right side having a different color pixel arrangement), the image is shifted to the dot DOTj adjacent to the right side having a color pixel array different from the above-described order (BRG order). That is, it is expressed by moving to the dot DOTj arranged in the order of the red color pixel R, the green color pixel G, and the blue color pixel B. FIG. At this time, the voltage state of the pixel electrode corresponding to each of the color pixels constituting the dot DOTi and the voltage state of the pixel electrode corresponding to each of the color pixels constituting the dot DOTj are noted.

Each of the color pixels of the dot DOTi has a voltage state of a pixel electrode having B (− +) R (+ −) G (− +), and each of the color pixels of the dot DOTj is R ( -+) G (+-) B (-+) has the voltage state of the pixel electrode. The remaining two color pixels R and G, except for the blue color pixel, are inverted in the voltage state of the corresponding pixel electrode and are represented in the dot DOTj of the j frame.

Thereafter, the dot DOTj is shifted and expressed as a dot DOTk adjacent to the right side of the dot DOTj in a k frame. That is, it is represented by moving to the dot DOTk arranged in the order of the green color G, the blue color B, and the red color R. FIG.

In this case, the voltage state of the pixel electrode corresponding to each of the color pixels constituting the dot DOTj and the voltage state of the pixel electrode corresponding to each of the color pixels constituting the dot DOTk are examined. Each of the color pixels of has a voltage state of the pixel electrode having B (-+) R (+-) G (-+), and each of the color pixels of dot DOTk is G (-+) B (+ -) Has a voltage state of the pixel electrode having R (-+). The remaining two color pixels B and R, except for the green G color pixel, are inverted in the voltage state of the corresponding pixel electrode and are represented in the dot DOTj of the k frame.

Thereafter, the dot DOTk is shifted into a dot DOTl adjacent to the right side of the dot DOTk in the l frame and is represented. That is, it is represented by moving to the dot DOTk arranged in the order of the blue color B, the red color G, and the green color G.

Each of the color pixels of the dot DOTk has a voltage state of the pixel electrode having G (− +) B (+ −) R (− +), and each of the color pixels of the dot DOTl is B (− +). ) Has a voltage state of a pixel electrode having R (+-) G (-+). Here, the remaining two color pixels B and R, except for the green G color pixel, are inverted in the voltage state of the corresponding pixel electrode and are represented in the dot DOTj of the k frame.

In summary, the dot DOTi representing a still image is moved from left to right on the display screen every frame, and pixel electrodes corresponding to two color pixels among the color pixels R, G, and B are displayed. The voltage state of is reversed every frame and displayed on the display screen. That is, the voltage state corresponding to two color pixels among the color pixels of the dots DOTi, DOTj, DOTk, and DOTl moving every frame is changed and displayed on the display screen every frame. Accordingly, it is possible to improve the vertical line phenomenon caused by each color pixel of the dot being displayed on the display screen every frame in the same voltage state.

On the other hand, the color pixels applied to the display device according to the present invention are red (R), green (G), and blue (B) pixels instead of yellow and cyano colors. Pixels, magenta color pixels, and the like may also be used. In addition, the display device having the color pixel arrangement according to the present invention can be applied regardless of the liquid crystal mode or the light scattering method.

As described above, in the display device according to the present invention, two pixel electrodes corresponding to two color pixels among the three color pixels constituting each dot are designed to have different polarities every frame.

Accordingly, in the display device according to the present invention, when a stationary image is moved on the display screen, colors corresponding to different voltage states are expressed for each frame, thereby improving a vertical line phenomenon in which specific luminance is continuously displayed.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (7)

Arranged in a matrix form, each of which comprises dots of at least three color pixels and a plurality of pixel electrodes corresponding to each of the color pixels, each of the plurality of pixel electrodes being divided into at least two subpixel electrodes A display panel; And A driving unit for driving the display panel, And at least two pixel electrodes corresponding to at least two color pixels among the at least three color pixels forming the dots have different polarities every frame. The method of claim 1, wherein the at least two subpixel electrodes, A first subpixel electrode; And A second subpixel electrode, The display panel, First and second thin film transistors connected to the first subpixel electrode and the second subpixel electrode, respectively; First and second data lines connected to sources of the first and second thin film transistors, respectively; And And a gate line connected to the gates of the first and second thin film transistors in common. The method of claim 2, And a first data voltage is applied to the first subpixel electrode, and a second data voltage having a polarity opposite to the first data voltage is applied to the second subpixel electrode. The method of claim 3, wherein And the voltage levels of the first data voltage and the second data voltage are different from each other. The method of claim 1, And the at least three color pixels are color pixels implementing red, green, and blue. The method of claim 5, The dots Form a plurality of dot groups having different color pixel arrangements in the row direction and having the same color pixel arrangements in the column direction; Each of the plurality of dot groups A first dot array arranged in the order of red, green, and blue; A second dot array adjacent to one side of the first dot array and arranged in an order of green, blue, and red; And And a third dot string adjacent to the other side with respect to the first dot string and arranged in the order of blue, red, and green. The method of claim 1, And the display panel is driven by a line inversion method in a column direction.

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