KR20060047359A - Liquid crystal display device and method for driving thereof - Google Patents

Abstract

Provided are a liquid crystal display device and a method of driving the same, which effectively improve visibility by minimizing the difference in gamma characteristics at the front and side surfaces. The liquid crystal display includes a plurality of gate lines and a plurality of data lines which are formed in a row and a column direction to cross each other, a plurality of switching elements connected to the plurality of gate lines and a plurality of data lines, and a plurality of switching elements. And a liquid crystal panel including a plurality of pixels including a first pixel group and a second pixel group, a gate driver providing a gate signal to a gate line, and receiving an external image signal and corresponding to different gamma constants, respectively. A timing controller for providing a first data signal and a second data signal, and a gray voltage corresponding to the first data and the second data signal applied from the timing controller are provided to the first pixel group and the second pixel group, respectively, through the data line. And a data driver.

Liquid Crystal Display, Gamma Constant, Vertical Alignment (VA)

Description

Liquid crystal display device and method for driving thereof

1 is a graph of a gamma characteristic curve of a conventional vertical alignment mode liquid crystal display.

2A is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

2B is a block diagram of a liquid crystal display according to another exemplary embodiment of the present invention.

3A is a gamma curve at the front of a liquid crystal display according to an exemplary embodiment of the present invention.

3B is a gamma curve at the side of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 4 is a graph showing a relationship between an identification PPI (Pixel Per Inch) and a distance (viewing distance) from a liquid crystal display to a viewer.

5 and 6 illustrate a liquid crystal panel to which a data signal having a constant gamma constant is applied to each pixel group regardless of a frame.

7A to 8B illustrate liquid crystal panels to which data signals having different gamma constants are applied at predetermined periods.

9A to 10B are diagrams illustrating an inversion driving signal of a data signal applied in a liquid crystal display according to an exemplary embodiment of the present invention.

11A and 11B are graphs measuring the amount of change (or color difference) on a color coordinate according to a change in a viewing angle of a liquid crystal display.

12 is a block diagram of a liquid crystal display according to another exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: liquid crystal panel

200: gate driver

300: data driver

400: timing controller

The present invention relates to a liquid crystal display and a driving method thereof, and more particularly, to a liquid crystal display (LCD) and a driving method thereof, which effectively improve visibility by minimizing a difference in gamma characteristics at the front and side. It is about.

Recently, according to the trend of large-sized televisions, instead of cathode ray tube (CRT), liquid crystal display (LCD), plasma display panel (PDP), organic EL display (Organinc ElectroLuminiscent Display; OELD) A flat panel display device such as) is being developed. Among such flat panel display devices, a liquid crystal display device capable of being lighter and thinner is particularly attracting attention.

In the liquid crystal display, a liquid crystal material having anisotropic dielectric constant is injected between an upper substrate on which a common electrode, a color filter, and the like are formed, and a lower substrate on which a thin film transistor and a pixel electrode are formed. The display device expresses a desired image by adjusting the intensity of an electric field formed in the liquid crystal material by applying a potential, thereby changing the molecular arrangement of the liquid crystal material, and controlling the amount of light transmitted through the substrate. In the liquid crystal display, a thin film transistor liquid crystal display (TFT LCD) using a thin film transistor (TFT) as a switching element is mainly used.

Among them, the vertical alignment (VA) mode liquid crystal display in which the long axes of the molecules of the liquid crystal material are arranged perpendicular to the upper substrate and the lower substrate without an electric field applied, has a large contrast ratio and facilitates wide viewing angle. Be in the spotlight. However, in the vertical alignment mode liquid crystal display, as shown in FIG. 1, the front gamma characteristics (On Axis) and the side gamma characteristics (Off-Axis: Upward, Off-Axis: Right, Off-Axis: Diagonal) Because of the different side visibility became worse. In order to solve this problem, in a vertical alignment mode liquid crystal display, a plurality of subpixels are formed for each pixel, and a coupling capacitor is formed between the plurality of subpixels, so that a gray level voltage applied to one subpixel is applied. Therefore, the visibility of the side surface was improved by applying a gray scale voltage to other sub-pixels (half-tone gray system).

However, when the visibility of the side is improved by the above method, a liquid crystal panel in which a plurality of pixels are formed must be separately designed, and the aperture ratio is reduced due to the sub-pixels formed in each pixel, so that the overall luminance of the liquid crystal panel is also reduced. Is reduced. In particular, in the case of forming the liquid crystal panel using the organic insulating film, it is difficult to form a large capacitance of the coupling capacitor, and thus it is very difficult to improve the visibility of the liquid crystal display.

Accordingly, a technical problem of the present invention is to provide a liquid crystal display (LCD) which can effectively improve visibility by minimizing the difference in gamma characteristics at the front and side without forming a plurality of sub pixels for each pixel. To provide.

Another object of the present invention is to provide a method of driving such a liquid crystal display.

The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, a plurality of gate lines and a plurality of data lines are formed in a row and a column direction to cross each other, and the plurality of gate lines and the plurality of liquid crystal display devices according to an embodiment of the present invention. A liquid crystal panel comprising a plurality of switching elements connected to data lines of the plurality of switching elements, a plurality of pixels connected to the plurality of switching elements, the plurality of pixels including a first pixel group and a second pixel group, and providing a gate signal to the gate line A gate controller configured to receive an external image signal, provide a first data signal and a second data signal corresponding to different gamma constants, and the first data and the second data applied from the timing controller. The gray voltage corresponding to the signal is applied to the first pixel group and the second pixel group through the data line, respectively. The blank includes a data driver.

In accordance with another aspect of the present invention, a liquid crystal display device includes a plurality of gate lines and a plurality of data lines that are formed in a row and a column direction to cross each other, and the plurality of gate lines and the plurality of gate lines. A liquid crystal panel comprising a plurality of switching elements connected to data lines of the plurality of switching elements, a plurality of pixels connected to the plurality of switching elements, the plurality of pixels including a first pixel group and a second pixel group, and providing a gate signal to the gate line. A timing controller configured to receive a gate driver, an external image signal, and selectively provide a first data signal and a second data signal having different gamma constants or one gamma constant, and the first controller applied from the timing controller The gray level voltage corresponding to the data and the second data signal are respectively transmitted through the data line. And a data driver provided to the pixel group and the second pixel group.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display device, including a plurality of gate lines and a plurality of data lines formed in a row and a column direction to cross each other, and the plurality of gates. A gate on the gate line for a liquid crystal panel including a plurality of switching elements connected to a line and the plurality of data lines, and a plurality of pixels connected to the plurality of switching elements and including a first pixel group and a second pixel group Providing a signal; receiving an external image signal; generating a first data signal and a second data signal corresponding to different gamma constants; and a gray level corresponding to the first data signal and the second data signal. And providing a voltage to the first pixel group and the second pixel group through the data line, respectively.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display device, including a plurality of gate lines and a plurality of data lines formed in a row and a column direction to cross each other, and the plurality of gates. A gate on the gate line for a liquid crystal panel including a plurality of switching elements connected to a line and the plurality of data lines, and a plurality of pixels connected to the plurality of switching elements and including a first pixel group and a second pixel group Providing a signal, receiving an external image signal and selectively generating a first data signal and a second data signal corresponding to different gamma constants or corresponding to one gamma constant, the first data signal and The gray level voltage corresponding to the second data signal is converted into the first pixel group and the second pixel through the data line, respectively. Providing to the subgroup.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

A liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to FIG. 2A. 2A is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

The liquid crystal display according to the exemplary embodiment of the present invention includes a liquid crystal panel 100, a gate driver 200, a data driver 300, and a timing controller 400 as illustrated in FIG. 2A.

The liquid crystal panel 100 is formed in a row and column direction, respectively, and includes a plurality of gate lines G1 to Gn and a plurality of data lines D1 to Dm, a plurality of gate lines G1 to Gn, and a plurality of gate lines. It includes a switching element (M) connected to the data lines (D1 to Dm), and a plurality of pixels connected to the plurality of switching elements (M). The plurality of pixels includes a first pixel group and a second pixel group. The first pixel group and the second pixel group may be alternately arranged to form a grid pattern, and their arrangement may be variously changed. As will be described in detail later, three pixels corresponding to one pixel or RGB may be used as the first pixel group and the second pixel group. For example, when the first pixel group and the second pixel group each use one pixel as a basic unit of the lattice pattern, the plurality of pixels is a set of pixels in which the sum of the rows and columns of the pixel matrix is even. The second pixel group is a set of pixels in which the sum of the pixel group and the rows and columns of the pixel matrix is an odd number. The first pixel group may be a set of pixels in which the sum of the rows and columns of the pixel matrix is odd, and the second pixel group may be a set of pixels in which the sum of the rows and columns of the pixel matrix is even.

Each pixel includes a switching element M connected to a plurality of gate lines G1 to Gn and a plurality of data lines D1 to Dm, a liquid crystal capacitor Clc, and a storage capacitor Cst connected thereto.

The plurality of gate lines G1 to Gn formed in the row direction transmit a gate signal to the switching element M, and the plurality of data lines D1 to Dm formed in the column direction transmit data to the switching element M. The gray voltage corresponding to the signal is transmitted. The switching element M is a three-terminal element, the control terminal is connected to the gate lines G1 to Gn, the input terminal is connected to the data lines D1 to Dm, and the output terminal is the liquid crystal capacitor Clc. And one terminal of the storage capacitor Cst. As the switching element M, a MOS transistor is used, and the MOS transistor is implemented as a thin film transistor having amorphous silicon or polycrystalline silicon as a channel layer. The liquid crystal capacitor Clc is connected between the output terminal of the switching element M and the common electrode (not shown), and the storage capacitor Cst is connected between the output terminal of the switching element M and the common electrode (independent wiring). Method) or a connection (shear gate method) between the output terminal of the switching element M and the gate lines G1 to Gn directly above.

The gate driver 200 is connected to a plurality of gate lines G1 to Gn, and receives a gate signal formed by a combination of a gate on voltage Von and a gate off voltage Voff provided from the driving voltage generator 500. The first data signal Data1 and the first data signal provided from the plurality of gate lines G1 to Gn, the data driver 300 is connected to the plurality of data lines D1 to Dm, and are provided from the timing controller 400. The gray voltage is generated according to the two data signals Data2 and provided to the plurality of data lines D1 to Dm.

The timing controller 400 receives the external image signals R, G, and B from an external graphic source (not shown), and outputs a first data signal Data1 and a second data signal corresponding to different gamma constants. Data2) is provided to the data driver 300. Here, the first data signal Data1 is transmitted to the pixels belonging to the first pixel group, and the second data signal Data2 is transmitted to the pixels belonging to the second pixel group. In addition, the timing controller 400 may include a gate select signal Gate CLK or CPV, a vertical synchronization start signal STV, an output enable signal OE, and the like that control the output of the gate on / off signal Von / Voff. Produce it and provide it to the gate driver 200.

Hereinafter, a process of providing the first data signal Data1 and the second data signal Data2 corresponding to different gamma constants in the timing controller 400 will be described in detail.

The timing controller 400 receives the external image signal for the first pixel group from the graphic source and converts the first data signal Data1 in which the gamma characteristic is converted to match the gamma curve of the first gamma constant γ1. 300). The timing controller 400 receives an external image signal for the second pixel group from the graphic source and converts the second data signal Data2 obtained by converting the gamma characteristic to the gamma curve of the second gamma constant γ2. Output to the data driver 300. Here, the first gamma constant gamma 1 and the second gamma constant gamma 2 have different values, and the first gamma constant gamma 1 corresponding to the first data signal Data1 and the second data signal Data2, respectively. And the second gamma constant γ 2 may always be constant regardless of a predetermined period. In addition, the first data signal Data1 is transmitted to the pixels belonging to the first pixel group, and the second data signal Data2 is transmitted to the pixels belonging to the second pixel group.

Further, when the timing controller 400 outputs the first data signal and the second data signal corresponding to these different gamma constants, the timing controller 400 swaps the gamma constants at predetermined intervals so that the timing controller 400 changes the gamma constants. It can be applied to the second data signal. For example, in the first period, the timing controller 400 receives an external image signal for the first pixel group and converts the gamma characteristic to a gamma curve of the first gamma constant γ 1. Data1 and the second image signal Data2 obtained by receiving an external image signal with respect to the second pixel group and converting the gamma characteristics thereof to the gamma curve of the second gamma constant γ2. Thereafter, in the second period, the timing controller 400 receives the external image signal for the first pixel group and converts the gamma characteristic to the gamma curve of the second gamma constant γ2. ) And a second data signal Data2 obtained by converting the gamma characteristic of the second pixel group according to the gamma curve of the first gamma constant γ1. Here, the same period may be used for the first period and the second period. For example, the first period and the second period may each be one frame.

The timing controller 400 alternately has a first data having a first gamma constant γ 1 and a second gamma constant γ 2 in one frame unit by using a look-up table (LUT) or a mathematical operation. The signal Data1 and the second data signal Data2 may be provided. The lookup table may be stored in a memory area of the timing controller 400, for example, a read only memory (ROM) device, which is a nonvolatile memory device. In this case, the lookup table may be easily changed without changing the structure of the liquid crystal panel 100. You can adjust the gamma constant.

FIG. 2B is a block diagram of a liquid crystal display according to another exemplary embodiment of the present invention. As shown in FIG. 2B, a separate memory device 450 is connected to the timing controller 400 so that the memory device ( The lookup table stored at 450 may be used. In this case, since the memory device 450 may be easily changed or replaced, various lookup tables may be used according to a user's needs, and even if the liquid crystal panel is changed, only the optimal lookup table may be changed to the changed liquid crystal panel to cope with panel changes. . Here, various memory storage devices may be used as the memory device 450. For example, a memory storage element such as a ROM or an electric erasable and programmable read-only memory (EEPROM) may be used as the memory element 450.

Hereinafter, the gamma characteristics of the front and side surfaces of the liquid crystal display according to the exemplary embodiment of the present invention will be described in detail with reference to FIGS. 3A and 3B. 3A is a gamma curve at the front of a liquid crystal display according to an exemplary embodiment of the present invention. 3B is a gamma curve at the side of the liquid crystal display according to the exemplary embodiment of the present invention. Although the gamma characteristic graph shown in FIGS. 3A and 3B has been described using 256 gray scales as an example, the present invention is not limited thereto and may be applied to a liquid crystal display device using 64 gray scales, 1024 gray scales, or the like.

In general, the luminance and the gradation level of the liquid crystal display have a relationship as shown in Equation 1 below.

Here, γ refers to a gamma constant, and the normalized brightness is proportional to the γ power of the gradation level. Thus, the gamma curves shown in FIGS. 3A and 3B are graphs showing the relationship between the exponential function of luminance and gray level.

In the gamma curve for the front face shown in FIG. 3A, the gamma curve F4 generally uses a gamma constant (for example, 2.2, 2.4, or 2.6, or the following standard gamma constant (γnormal)) used in a liquid crystal display device. To show the relationship between the gradation level and the luminance. In the gamma curve for the side shown in FIG. 3B, the gamma curve S4 is a graph showing the relationship between the gradation level and the luminance using the standard gamma constant γnormal. When the gamma curve F4 and the gamma curve S4 shown in FIGS. 3A and 3B are compared, when the general standard gamma constant (γnormal) is used, the LCD is viewed from the side rather than the front side at the halftone level. It can be seen that the luminance greatly increases. That is, the conventional liquid crystal display device has good visibility on the front side, but has a problem in that the visibility is bad due to a large increase in luminance on the side surface.

In FIGS. 3A and 3B, the gamma curve F1 and the gamma curve S1 are gamma curves using the first gamma constant γ1 for the front and side surfaces, respectively, and the gamma curve F2 and the gamma curve S2 are respectively. Gamma curve using the second gamma constant (γ2) for the front and side surfaces. The first gamma constant γ1 such that the gamma curve F3 representing the average luminance of the gamma curve F1 and the gamma curve F2 at the front is substantially the same as the gamma curve F4 by the standard gamma constant γnormal. And the second gamma constant γ 2 can be defined. At this time, the gamma curve S3 representing the average luminance of the gamma curve S1 and the gamma curve S2 on the side surface may be minimized in comparison with the gamma curve S4. have.

Hereinafter, a method of defining the first gamma constant gamma 1 and the second gamma constant gamma 2 will be described in detail. When the second gamma constant γ2 has a value smaller than the first gamma constant γ1, as shown in FIGS. 3A and 3B, the gamma curves F1 and S1 are lower than the gamma curves F2 and S2. It is located at. Looking at the gamma curves F4 and S4 by the standard gamma constant gamma normal, it can be seen that the difference between the gamma curves of the front and the side is remarkable at a low gray level. In order to prevent the luminance of the side surface from increasing at a low gray level, the first gamma constant gamma 1 may have various values depending on the gray level. That is, at the low gray level, the first gamma constant gamma 1 can be set to a high value so that the luminance becomes substantially zero in this section.

When the maximum gradation level at which the luminance is substantially zero in the gamma curves F1 and S1 is referred to as the threshold gradation level Gray_C, the value may change based on the threshold gradation level Gray_C. The first gamma constant gamma 1 preferably has a larger value than that in the second section that is greater than or equal to the threshold gray level in the first section that is less than or equal to the threshold gray level Gray_C. Here, the first gamma constant γ 1 may be set to γ 1 ≧ 3 at or below the threshold gradation level Gray_C.

In this way, the first gamma constant γ1 and the first are made such that the average of the luminance by the first gamma constant γ1 and the luminance by the second gamma constant γ2 is substantially the same as the luminance by the standard gamma constant γnormal. By setting the two gamma constants? 2, the difference between the gamma characteristics at the front and the gamma characteristics at the side is minimized, and it is not necessary to form a plurality of sub pixels for each pixel.

FIG. 4 is a graph showing a relationship between an identification PPI (Pixel Per Inch) and a distance (viewing distance) from a liquid crystal display to a viewer. Here, the PPI refers to the resolution and specifically represents the number of pixels formed per inch. In general, the more objects are taken towards the viewer's eyes, the more detailed the object appears, because more information is filled in the light sensor in the retina of the eye. When the object is brought closest to the eye at a distance that does not leave the eye's focus, the human eye has the maximum resolution, which is called the near point or point of most distinct vision. In normal naked eyes, the root point is about 30cm and the angle resolution at the root point is about 1/60 ° (≒ 0.0167 °). The human eye has the best eye resolution at the near point, and when it is closer, the resolution is poor because it is out of focus. The distance with an angular resolution of 1/60 ° for an object 1.5 m from the eye is about 436 μm. When the pitch of the pixel is 436 μm, this corresponds to about 58 PPI.

Accordingly, the timing controller 400 receives the first data signal Data1 corresponding to the first gamma constant γ1 and the second data signal Data2 corresponding to the second gamma constant γ2 regardless of a predetermined frame. In the case of providing a data signal having a different gamma constant for each adjacent pixel group through the liquid crystal panel 100, the human eye does not detect this in a high-definition liquid crystal display device of about 58 PPI or more. Therefore, the image quality can be realized with improved side visibility.

Of course, the present invention can also be applied to a non-high-definition liquid crystal display device. In this case, the gamma constant corresponding to each data signal is alternately changed at every predetermined period, thereby improving the visibility of the side surface and making the screen look coarse. It can prevent. For example, the timing controller 400 may include a first data signal Data1 corresponding to the first gamma constant γ1 for odd frames and a second gamma constant γ2 for even frames in one frame unit, The second data signal Data2 corresponding to the second gamma constant γ2 during the odd frame and the first gamma constant γ1 may be provided to the data driver 300 during the even frame. As a result, flicker phenomenon and streaks can be effectively suppressed and the contrast ratio can be improved. As mentioned above, although the present invention has been described using a liquid crystal display device using a data signal in which the gamma constant is changed in units of one frame, the present invention is not limited thereto, and the period in which the gamma constant changes may be variously changed. However, when the first data signal Data1 and the second data signal Data2 have the first gamma constant γ1 and the second gamma constant γ2 in a plurality of frame units, the flicker phenomenon becomes stronger or streaks. Since there is a possibility that such a phenomenon may occur, the change period of the gamma constant may be variously changed to the extent that this phenomenon can be prevented. Hereinafter, for convenience of description, the present invention will be described using data signals alternately having different gamma constants in one frame unit.

When a coupling capacitor between a pixel and a sub pixel is used to improve side visibility of a conventional liquid crystal display device, since the dielectric constant of the organic insulating layer used as the dielectric is low, it occupies a large area and thus the aperture ratio is lowered. A problem arises. However, since the liquid crystal display according to the exemplary embodiment of the present invention does not use a coupling capacitor, the aperture ratio can be increased. In addition, the liquid crystal display according to the exemplary embodiment of the present invention does not need to form a separate sub-pixel in one pixel, so that the aperture ratio is improved, and thus the luminance of the entire liquid crystal panel 100 may be increased. This can easily compensate for the change in the gamma characteristic of the liquid crystal panel 100.

One pixel in one frame that may be represented on the liquid crystal panel 100 may be represented by a second plane of X and Y. X is the number of horizontal lines and Y is the number of vertical lines. Here, if the variable of the time axis indicating the number of frames is set to Z, the coordinate value for the pixel position at any one point may be expressed in three dimensions of X, Y, and Z. In this case, X, Y may be fixed to a constant value, and a value obtained by dividing the number of times the pixel is turned on by the predetermined frame number while the predetermined frame is repeated at the position may be defined as a duty rate. For example, assuming that the duty ratio of the gradation voltage level of a data signal at position (1,1) is 1/2, it indicates that the pixel is turned on for one frame out of two frames at position (1,1). . Therefore, in order to express various gray voltage levels in a liquid crystal display, a frame rate control (FRC) method may be used in which a duty ratio is set for each gray voltage level and pixels are turned on or off according to the set duty ratio. have. In addition, the side visibility is dithered by dithering the position of the pixel to which the data signal having the first gamma constant γ1 is applied and the position of the pixel to which the data signal having the second gamma constant γ2 is applied. Improved picture quality can be achieved.

Hereinafter, a data signal applied to each pixel group of the liquid crystal panel of the liquid crystal display according to the exemplary embodiment of the present invention will be described with reference to FIGS. 5 to 8B.

5 and 6 illustrate a liquid crystal panel to which a data signal corresponding to a constant gamma constant is applied to each pixel group regardless of the frame period.

Specifically, FIG. 5 illustrates a first pixel group and a second pixel group constituting a grid pattern by alternately arranging three pixels corresponding to RGB as basic units of the pixel group. As shown in FIG. 5, a first data signal Data1 having a first gamma constant γ1 is applied to a pixel belonging to a first pixel group, and a second gamma constant γ2 is applied to a pixel belonging to a second pixel group. The second data signal Data2 having (k) may be applied. Here, the positions of the first pixel group and the second pixel group may be interchanged.

6 illustrates a first pixel group and a second pixel group constituting a grid pattern by alternately arranging one pixel as a basic unit of the grid pattern. As shown in FIG. 6, the first pixel group is a set of pixels in which the sum of the rows and columns of the pixel matrix is even, and the second pixel group is a collection of pixels in which the sum of the rows and columns of the pixel matrix is odd. That is, in the pixels belonging to the first pixel group, that is, pixels in odd-numbered columns C1, C3, C5, C7, and C9 in odd-numbered rows R1 and R3 and even-numbered rows in even-numbered rows R2 and R4. The first data signal Data1 having the first gamma constant γ1 may be applied to the pixels C2, C4, C6, and C8. In the pixels belonging to the second pixel group, that is, the pixels in the even columns C2, C4, C6, and C8 of the odd rows R1 and R3 and the odd columns C1 in the even rows R2 and R4. The second data signal Data2 having the second gamma constant γ2 may be applied to the pixels C3, C5, C7, and C9. Here, the positions of the first pixel group and the second pixel group may be interchanged.

7A to 8B illustrate liquid crystal panels to which data signals having different gamma constants are applied at predetermined periods.

Specifically, FIGS. 7A and 7B illustrate a liquid crystal panel to which a data signal is applied every one frame. FIG. 7A is a diagram illustrating a data signal applied to an odd frame, and FIG. 7B is a diagram illustrating a data signal applied to an even frame. Here, the first pixel group and the second pixel group alternately arrange three pixels corresponding to RGB as basic units of the pixel group to form a grid pattern.

In an odd-numbered frame, as shown in FIG. 7A, a first data signal Data1 corresponding to a first gamma constant γ1 is applied to a pixel belonging to a first pixel group, and a first data signal Data1 corresponding to a pixel belonging to a second pixel group is applied. The second data signal Data2 corresponding to the two gamma constant γ2 may be applied.

In the even-numbered frame, as shown in FIG. 7B, the second data signal Data2 corresponding to the second gamma constant γ2 is applied to the pixels belonging to the first pixel group, and the pixels belonging to the second pixel group. The first data signal Data1 corresponding to the first gamma constant γ1 may be applied to the first gamma constant γ1.

Here, the data signal applied to the odd frame and the data signal applied to the even frame may be interchanged.

8A and 8B illustrate a liquid crystal panel to which a data signal is applied every one frame. 8A is a diagram illustrating a data signal applied to an odd-numbered frame, and FIG. 8B is a diagram illustrating a data signal applied to an even-numbered frame. Here, the first pixel group and the second pixel group are alternately arranged with one pixel as a basic unit of the pixel group to form a grid pattern.

In the odd-numbered frame, as shown in FIG. 8A, the pixels belonging to the first pixel group, that is, the pixels in the odd-numbered columns C1, C3, C5, C7, and C9 in the odd-numbered rows R1 and R3 and the even-numbered rows The first data signal Data1 corresponding to the first gamma constant γ1 is applied to the even-numbered columns C2, C4, C6, and C8 of (R2, R4), that is, to the pixels belonging to the second pixel group, that is, Pixels in the even columns C2, C4, C6, and C8 of the odd rows R1 and R3 and odd columns C1, C3, C5, C7, and C9 in the even rows R2 and R4 are arranged in the second column. The second data signal Data2 corresponding to the gamma constant γ2 is applied.

In the even-numbered frame, as shown in FIG. 8B, the pixels belonging to the first pixel group, that is, the pixels in the odd-numbered columns C1, C3, C5, C7, and C9 of the odd-numbered rows R1 and R3 are even-numbered. The first data signal Data1 corresponding to the second gamma constant γ2 is applied to the even-numbered columns C2, C4, C6, and C8 of the rows R2 and R4, and to the pixels belonging to the second pixel group, That is, the pixels of the even columns C2, C4, C6, and C8 of the odd rows R1 and R3 and the odd columns C1, C3, C5, C7, and C9 of the even rows R2 and R4 are formed. The second data signal Data2 corresponding to one gamma constant gamma 1 is applied.

The data signal corresponding to the gamma constant shown in FIG. 8A is not necessarily applied to the odd frame, and the data signal corresponding to the gamma constant shown in FIG. 8B is not necessarily applied to the odd frame. It is also possible to apply a data signal corresponding to the shown gamma constant and to apply the data signal corresponding to the gamma constant shown in FIG. 8A to an even-numbered frame.

As described above, the data signal in which the gamma constant is changed every one frame has been described. However, the present invention is not limited thereto, and as described above, the period may be variously changed within the limit to prevent the flicker phenomenon or the streaks. can do.

Hereinafter, the inversion driving of the data signal applied in the liquid crystal display according to the exemplary embodiment of the present invention will be described with reference to FIGS. 9A to 10B. For convenience of explanation, the inversion driving of the data signal will be described using the liquid crystal panel described with reference to FIGS. 8A and 8B, but the present invention is not limited thereto, and the aforementioned first and second pixel groups of various types are described. The application is possible with respect to this arrange | positioned liquid crystal panel.

9A and 9B show dot inversion driving signals. 10A and 10B show a (1 + 2) dot inversion driving signal. Here, the positive and negative signs in the pixels of FIGS. 9A to 10B indicate the polarities of the respective pixels.

The data signal applied to each pixel of the liquid crystal display according to the exemplary embodiment of the present invention is not limited to a dot inversion driving signal or a (1 + 2) dot inversion driving signal, and various types of inversion driving may be applied. . Preferably, when the data signal is a dot inversion driving signal, flicker or streaks can be more effectively suppressed, and the contrast ratio can be improved.

11A and 11B are graphs measuring the amount of change in color coordinates (hereinafter, referred to as color difference) according to the change in the viewing angle of the liquid crystal display. Here, FIG. 11A illustrates a color difference according to a viewing angle of a conventional vertical alignment mode liquid crystal display, and FIG. 11B illustrates a color difference according to a viewing angle of a liquid crystal display according to an exemplary embodiment of the present invention. Here, the curve A is the color difference of the color whose RGB gray level is (192, 128, 64) according to the change of the viewing angle, and the curve B is the color of the color whose RGB gray level is (64, 192, 128). The color difference, and the curve C is a graph showing the color difference of the color whose RGB gray level is (217, 172, 144).

As shown in FIGS. 11A and 11B, the liquid crystal display according to the exemplary embodiment of the present invention corresponds to gamma constants different for the first pixel group and the second pixel group that are alternately arranged to form a lattice pattern. It can be seen that the color difference in the side surface is significantly reduced by applying the first data signal and the second data signal.

In the above, the liquid crystal display device driven by the first data signal Data1 and the second data signal Data2 corresponding to different gamma constants has been described. FIG. 12 is a block diagram of a liquid crystal display according to another embodiment of the present invention. In the liquid crystal display of the present embodiment, gamma of the first data signal Data1 and the second data signal Data2 is selected according to a user's selection. The same or different integers may adjust the image quality of the liquid crystal display.

That is, when only the front visibility is considered in the liquid crystal display (hereinafter, the normal mode), the selection signal SS for allowing the first data signal Data1 and the second data signal Data 2 to correspond to the same gamma constant is a timing. It may be applied to the controller 400. In addition, when the side visibility is also considered in the liquid crystal display (hereinafter, referred to as side enhancement mode), the selection signal SS may be configured such that the first data signal Data1 and the second data signal Data 2 correspond to different gamma constants. The timing controller 400 may be applied to the timing controller 400.

As such, when the selection signal SS is applied according to a user's request, the timing controller 400 may additionally provide the first data signal Data1 and the second data signal Data2 corresponding to the same gamma constant. . For example, when the user provides the selection signal SS to the timing controller 400 using a remote controller or the like, the timing controller 400 may include the first data signal Data1 and the first data suitable for the normal mode or the side enhancement mode. The image quality of the liquid crystal display may be adjusted by providing a data signal Data 2.

The timing controller 400 may select the normal mode or the side enhancement mode by the selection signal SS from the outside, but the present invention is not limited thereto, and the external image signals R, G, and the like may be input from an external graphic source. Depending on the type of B), normal mode or side enhanced mode can be selected automatically. In general, the still image is not considered much of the side visibility, and in the case of video, the side visibility is often considered. Therefore, when the external image signals R, G, and B input to the timing controller 400 from an external graphic source are still images, the timing controller 400 automatically corresponds to the same gamma constant corresponding to the normal mode. The first data signal Data1 and the second data signal Data 2 may be provided. In addition, when the external image signals R, G, and B input to the timing controller 400 are moving images, the timing controller 400 automatically generates first data signals corresponding to different gamma constants corresponding to the side enhancement mode. Data1 and the second data signal Data 2 may be provided.

Such a liquid crystal display of the present invention can be applied not only to the vertical alignment mode but also to the twisted nematic (TN) mode that requires enhanced side visibility.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

As described above, the liquid crystal display according to the present invention applies a data signal having a different gamma constant to a pixel adjacent to one pixel unit and a data signal having a different gamma constant to one pixel in a predetermined frame unit. The application can effectively improve visibility.

In addition, the liquid crystal display according to the exemplary embodiment of the present invention does not need to form a separate sub-pixel in one pixel, so that the aperture ratio may be improved, thereby increasing the overall luminance of the liquid crystal panel, and Changes in gamma characteristics can be easily compensated for. In particular, when the liquid crystal panel is formed using the organic insulating film, the luminance of the entire liquid crystal panel can be increased more effectively.

Claims (47)

A plurality of gate lines and a plurality of data lines each formed in a row and column direction to cross each other, a plurality of switching elements connected to the plurality of gate lines and the plurality of data lines, and connected to the plurality of switching elements. A liquid crystal panel including a plurality of pixels including one pixel group and a second pixel group; A gate driver configured to provide a gate signal to the gate line; A timing controller receiving an external image signal and providing a first data signal and a second data signal respectively corresponding to different gamma constants; And And a data driver configured to provide a gray voltage corresponding to the first data and the second data signal applied from the timing controller to the first pixel group and the second pixel group, respectively, through the data line. . According to claim 1, And the first pixel group and the second pixel group are alternately arranged to form a lattice pattern. The method of claim 2, The first pixel group and the second pixel group are each one pixel. The method of claim 2, The first pixel group and the second pixel group are three pixels respectively corresponding to RGB. According to claim 1, And the first data signal corresponds to a first gamma constant (γ1) and the second data signal corresponds to a second gamma constant (γ2). The method of claim 5, The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A liquid crystal display device substantially equal to the luminance corresponding to the level. The method of claim 5, The first gamma constant (γ1) is a liquid crystal display device whose value is changed based on a threshold gray level, which is a maximum gray level substantially equal to zero luminance. The method of claim 7, wherein The first gamma constant γ1 has a larger value below the threshold gradation level than above the threshold gradation level, The first gamma constant (γ1) is γ1 ≥ 3 below the threshold gray level. The method of claim 5, The liquid crystal display device has a resolution of about 58 pixels per inch (PPI) or more. According to claim 1, The first data signal corresponds to a first gamma constant γ 1 in a first period and corresponds to a second gamma constant γ 2 that is smaller than the first gamma constant γ 1 in a second period. And the second data signal corresponds to the second gamma constant (γ2) in the first period and corresponds to the first gamma constant (γ1) in the second period. The method of claim 10, The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A liquid crystal display device substantially equal to the luminance corresponding to the level. The method of claim 10, The first period and the second period are the same period. The method of claim 12, The first period and the second period are both one frame. The method of claim 10, The first gamma constant (γ1) changes in value based on a threshold gray level, which is a maximum gray level of which luminance is substantially zero in a gamma curve as the gray level changes. The method of claim 14, The first gamma constant γ1 has a larger value below the threshold gradation level than above the threshold gradation level, The first gamma constant (γ1) is γ1 ≥ 3 below the threshold gray level. According to claim 1, The timing controller may include a first lookup table for converting the external image signal into the first data signal corresponding to a first gamma constant γ1, and the second image corresponding to the second gamma constant γ2. And a second lookup table for converting the data signal. According to claim 1, A first lookup table for converting the external image signal to the first data signal corresponding to a first gamma constant γ1 and the external image signal to the second data signal corresponding to a second gamma constant γ2 And a memory device configured to store a second lookup table, and to provide the first lookup table and the second lookup table to the timing controller. A plurality of gate lines and a plurality of data lines each formed in a row and column direction to cross each other, a plurality of switching elements connected to the plurality of gate lines and the plurality of data lines, and connected to the plurality of switching elements. A liquid crystal panel including a plurality of pixels including one pixel group and a second pixel group; A gate driver configured to provide a gate signal to the gate line; A timing controller configured to receive an external image signal and selectively provide a first data signal and a second data signal having different gamma constants or one gamma constant; And And a data driver configured to provide a gray voltage corresponding to the first data and the second data signal applied from the timing controller to the first pixel group and the second pixel group, respectively, through the data line. . The method of claim 18, And the first pixel group and the second pixel group are alternately arranged to form a lattice pattern. The method of claim 19, The first pixel group and the second pixel group are each one pixel. The method of claim 19, The first pixel group and the second pixel group are three pixels respectively corresponding to RGB. The method of claim 18, And the timing controller determines whether a gamma constant of the first data signal and the second data signal is equal to each other according to a selection signal input from an external device. The method of claim 18, The first data signal corresponds to a first gamma constant γ 1 and the second data signal corresponds to a second gamma constant γ 2, The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A liquid crystal display device substantially equal to the luminance corresponding to the level. The method of claim 18, The first data signal corresponds to a first gamma constant γ 1 in a first period and corresponds to a second gamma constant γ 2 that is smaller than the first gamma constant γ 1 in a second period. And the second data signal corresponds to the second gamma constant (γ2) in the first period and corresponds to the first gamma constant (γ1) in the second period. The method of claim 24, The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A liquid crystal display device substantially equal to the luminance corresponding to the level. The method of claim 24, The first period and the second period are both one frame. The method of claim 18, The timing controller may include a first lookup table for converting the external image signal into the first data signal corresponding to a first gamma constant γ1, and the second image corresponding to the second gamma constant γ2. And a second lookup table for converting the data signal. The method of claim 18, A first lookup table for converting the external image signal to the first data signal corresponding to a first gamma constant γ1 and the external image signal to the second data signal corresponding to a second gamma constant γ2 And a memory device configured to store a second lookup table, and to provide the first lookup table and the second lookup table to the timing controller. A plurality of gate lines and a plurality of data lines each formed in a row and column direction to cross each other, a plurality of switching elements connected to the plurality of gate lines and the plurality of data lines, and connected to the plurality of switching elements. Providing a gate signal to the gate line of a liquid crystal panel including a plurality of pixels including a first pixel group and a second pixel group; Receiving an external image signal and generating a first data signal and a second data signal corresponding to different gamma constants; And And providing the gray voltages corresponding to the first data signal and the second data signal to the first pixel group and the second pixel group through the data line, respectively. The method of claim 29, And the first pixel group and the second pixel group are alternately arranged to form a lattice pattern. The method of claim 30, And the first pixel group and the second pixel group are each one pixel. The method of claim 30, And the first pixel group and the second pixel group are three pixels respectively corresponding to RGB. The method of claim 29, The generating of the first and second data signals may include converting the external image signal to the first data signal corresponding to a first gamma constant γ 1 and the second data signal corresponding to a second gamma constant γ 2. To convert to The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A method of driving a liquid crystal display device which is substantially the same as the luminance corresponding to the level. The method of claim 29, wherein generating the first and second data signals comprises: The external image signal is converted into the first data signal corresponding to a first gamma constant γ 1 in a first period and corresponding to a second gamma constant γ 2 that is smaller than the first gamma constant γ 1 in a second period. and, Converting the external image signal into the second data signal corresponding to a second gamma constant γ2 in the first period and corresponding to the first gamma constant γ1 in the second period. Driving method. The method of claim 34, wherein The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A method of driving a liquid crystal display device which is substantially the same as the luminance corresponding to the level. The method of claim 34, wherein The first period and the second period are the same period driving method of the liquid crystal display device. The method of claim 36, wherein And the first period and the second period are all one frame. A plurality of gate lines and a plurality of data lines each formed in a row and column direction to cross each other, a plurality of switching elements connected to the plurality of gate lines and the plurality of data lines, and connected to the plurality of switching elements. Providing a gate signal to the gate line of a liquid crystal panel including a plurality of pixels including a first pixel group and a second pixel group; Receiving an external image signal and selectively generating a first data signal and a second data signal corresponding to different gamma constants or corresponding to one gamma constant; And And providing the gray voltages corresponding to the first data signal and the second data signal to the first pixel group and the second pixel group through the data line, respectively. The method of claim 38, wherein And the first pixel group and the second pixel group are alternately arranged to form a lattice pattern. The method of claim 39, And the first pixel group and the second pixel group are each one pixel. The method of claim 39, And the first pixel group and the second pixel group are three pixels respectively corresponding to RGB. The method of claim 38, wherein The generating of the first and second data signals may include determining whether the gamma constants corresponding to the first and second data signals are equal to each other by a selection signal input from an external source. . The method of claim 38, wherein When the gamma constants of the first and second data signals are different, the generating of the first and second data signals may include converting the external image signal into a first gamma constant γ 1 and a first data signal corresponding to a first gamma constant γ 1. Converting to the second data signal corresponding to a two gamma constant γ 2; The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A method of driving a liquid crystal display device which is substantially the same as the luminance corresponding to the level. The method of claim 38, wherein when the gamma constants of the first and second data signals are different, The generating of the first and second data signals may include: generating a second gamma corresponding to the external image signal in a first period, the first gamma constant γ 1 and smaller than the first gamma constant γ 1 in a second period. Converts the external image signal to the first gamma constant γ1 in the first period and converts the external image signal to the second gamma constant γ2 in the first period. And converting the second data signal into a corresponding second data signal. The method of claim 44, The average of the luminance corresponding to the predetermined gradation level at the first gamma constant γ1 and the luminance corresponding to the predetermined gradation level at the second gamma constant γ2 is the predetermined gradation at the standard gamma constant γnormal. A method of driving a liquid crystal display device which is substantially the same as the luminance corresponding to the level. The method of claim 44, The first period and the second period are the same period driving method of the liquid crystal display device. 47. The method of claim 46 wherein And the first period and the second period are all one frame.

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