TWI408656B - Pixel driving method for reducing color shift - Google Patents

Abstract

A pixel driving method for reducing color shift is provided. The method is suitable for driving each pixel with two sub-pixels in a liquid crystal panel. The method divides each frame into two sub-frames and generates four sub-gray levels according to a gray level corresponding to a pixel, wherein the sub-gray levels are respectively displayed in the sub-frames. By the method, the sub-gray levels are generated by increasing the sub-frames and then a color shift phenomenon of the display panel can be improved by a prefer combination of the sub-gray levels.

Description

Pixel driving method for reducing color shift

The present invention relates to a driving method of a liquid crystal panel, and more particularly to a pixel driving method capable of reducing a color shift phenomenon.

Thin film transistor liquid crystal display (TFT-LCD) has gradually become the mainstream of the market due to its high image quality, good space utilization efficiency, low power consumption, and no radiation. At present, the market's performance requirements for liquid crystal displays are toward high contrast (High Contrast Ratio), fast response and wide viewing angle. Among them, a technology capable of achieving a wide viewing angle requirement is generally a multi-domain vertical alignment (MVA) thin film transistor liquid crystal display, and a multi-domain horizontal alignment (MHA) thin film transistor liquid crystal display. Wait.

Since the steering angle of the liquid crystal is directional, when the human eye views the screen through different angles, the gray scale of the pixel will be different, resulting in a color shift phenomenon, that is, color shift. The phenomenon. When the user views the LCD screen through different angles, the color of the screen will be different from that when viewed from the forward angle, and different regions of the overall screen will have different degrees of color shift.

In the prior art, the problem of color shift is usually improved by a pixel structure design or driving method. As shown in FIG. 1 , FIG. 1 is a schematic diagram of a low color pixel structure and a driving method thereof according to the prior art. Each pixel consists of two children The pixels display two sub-gray scales respectively, and the effect of the human eye integral is used to mix the two sub-gray steps to reach the gray scale value corresponding to the pixel. Since the degree of color shift caused by liquid crystals under different gray levels is different, the conventional technique uses two sub-pixels instead of a single pixel, and uses different sub-gray steps (H and L) to improve the color shift phenomenon. Since the color shift phenomenon of the liquid crystal in the middle gray scale portion is serious, the combination of high gray scale (refer to FIG. 1 and denoted by H) and low gray scale (refer to FIG. 1 , denoted by L) can be used to achieve the desired result. The grayscale value causes the pixel brightness seen at different angles to approach the pixel brightness seen by the positive angle.

2 is a graph of gray scale values and pixel luminances according to the pixel of FIG. 1. The curve RX0 is the relationship between the gray scale and the pixel brightness under the positive angle, and the curve RX60 is the relationship between the gray scale and the pixel brightness measured by the lateral 60 degrees. The curve RXL represents the relationship between the gray scale and the brightness of the pixels after the mixing of the two sub-pixels (also measured by the lateral 60 degrees). As can be seen from FIG. 2, under the same gray scale value, the brightness corresponding to the curve RX0 and the curve RX60 (the vertical axis in FIG. 2 is the normalized relative brightness) is different, so the pixel gray level perceived by the user is not The same, its color will be biased. Although the curve RXL is closer to the curve RX0 than the curve RX60, it has the effect of improving the color shift phenomenon, but the effect is still not satisfactory and cannot meet the needs of the user.

The invention provides a pixel driving method, which uses a time-sharing method to drive pixels, so that the liquid crystal panel can maintain a certain resolution and effectively improve. Color shift phenomenon.

In the above, the present invention provides a pixel driving method, which is suitable for driving a liquid crystal panel, the liquid crystal panel includes a plurality of pixels, and each pixel includes a first sub-pixel and a second sub-pixel, and the pixel driving The method comprises the following steps: first, dividing a picture into a first sub-picture and a second sub-picture; then, in the first sub-picture, causing the first sub-pixel to display the first sub-gray, and the second sub-pixel display The second sub-gray. Next, in the second sub-picture, the first sub-pixel is displayed with the third sub-gray, and the second sub-pixel is displayed with the fourth sub-gray. The first to fourth sub-gray levels correspond to one of the gray scale values of the pixels.

In an embodiment of the present invention, the pixel driving method, wherein the first sub-gray scale is greater than or equal to the second sub-gray scale, and the third sub-gray scale is less than or equal to the fourth sub-gray scale.

In an embodiment of the present invention, the pixel driving method, wherein when the picture is a static picture, the first sub-gray level is greater than or equal to the second sub-gray level, and the third sub-gray level is greater than or equal to the fourth sub-gray level .

In an embodiment of the present invention, the pixel driving method, wherein when the picture is a dynamic picture, the third sub-gray is greater than or equal to the first sub-gray, and the fourth sub-gray is greater than or equal to the second sub-gray .

The present invention further provides a pixel driving method, which is suitable for driving a liquid crystal panel. The liquid crystal panel includes a plurality of pixels, and each pixel includes a first sub-pixel, a second sub-pixel, a third sub-pixel, and a first pixel. Four sub-pixels, wherein the first sub-pixel and the fourth sub-pixel are diagonally arranged, and the second sub-pixel and the third sub-pixel are diagonally arranged, and the pixel driving method comprises the following steps: First, The grayscale value corresponding to the pixel is divided into a first sub-gray scale, a second sub-gray scale, a third sub-gray scale and a fourth sub-gray scale; then the first sub-pixel displays a first sub-gray scale, the second sub-pixel displays a second sub-gray scale, and the third sub-pixel displays a third sub-gray scale, And the fourth sub-pixel displays the fourth sub-gray.

In an embodiment of the invention, the pixel driving method, wherein the first sub-gray scale is greater than or equal to the second sub-gray scale, and the third sub-gray scale is less than or equal to the fourth sub-gray scale.

In an embodiment of the present invention, the pixel driving method, wherein the first sub-gray scale is greater than or equal to the second sub-gray scale, and the third sub-gray scale is greater than or equal to the fourth sub-gray scale.

In an embodiment of the invention, the pixel driving method further includes reading the first to fourth sub-gray levels according to gray scale values corresponding to the pixels via a lookup table.

The invention drives the pixels by using time-division partitioning, so more sub-gray combination can be used to replace the gray level value of the single pixel, so that the lateral angle and the positive angle of the pixel brightness change are closer. , effectively improve the color shift phenomenon.

The above described features and advantages of the present invention will be more apparent from the following description.

First embodiment

FIG. 3A is a schematic diagram of a pixel driving method according to a first embodiment of the present invention. In this embodiment, a pixel is divided into two sub-pixels 310 and 320, and the picture is divided into two sub-pictures, which are respectively the first sub-picture. With the second sub-picture. In the first In a sub-picture, the sub-pixels 310 and 320 respectively display the sub-gray H1 and the sub-gray L1. In the second sub-picture, the sub-pixels 310 and 320 respectively display the sub-gray L2 and the sub-gray H2.

In this embodiment, the grayscale value (for example, 128) of a single pixel may be composed of four sub-grayscales H1, H2, L1, L2 (eg, 233, 0, 0, 0), where the sub-grayscales H1, H2 The grayscale value is greater than or equal to the child grayscales L1, L2. In the first sub-picture, the sub-gray H1 displayed by the sub-pixel 310 is greater than or equal to the sub-gray L1 displayed by the sub-pixel 320; in the second sub-picture, the sub-gray L2 displayed by the sub-pixel 310 It is less than or equal to the sub-gray H2 displayed by the sub-pixel 320. By the conversion of high and low gray scales, the sub-pixels 310 and 320 can be more uniform when displayed on the screen, and are not easily perceived by the human eye.

In addition, it is worth noting that the configuration of the sub-gray scales H1, H2, L1, L2 may vary depending on the dynamic picture or the still picture, as shown in FIGS. 3B and 3C. FIG. 3B is a schematic diagram of a child grayscale configuration in a static picture according to the first embodiment of the present invention; FIG. 3C is a schematic diagram of a child grayscale configuration in a dynamic picture according to the first embodiment of the present invention. Referring to FIG. 3B, when the picture displayed on the liquid crystal panel is a static picture, the sub-gray levels H1 and L1 are respectively displayed in the sub-pixels 310 and 320 in the first sub-picture, and the sub-gray levels H2 and L2 are respectively displayed in the The sub-pixels 310, 320 in the two sub-pictures. Referring to FIG. 3C, when the screen displayed on the liquid crystal panel is a dynamic screen, the sub-gray scales L2 and L1 are respectively displayed in the sub-pixels 310 and 320 in the first sub-screen, and the sub-gray scales H2 and H1 are respectively displayed in the The sub-pixels 310, 320 in the two sub-pictures.

In FIG. 3B, since the gray scale change of the subpixels 310, 320 is small, the driving method of the pixel is a hold type (Hold type); in FIG. 3C, Since the sub-pixels 310 and 320 are converted from a low gray scale to a high gray scale, the pixel driving method is similar to the pulse mode of a cathode ray tube (CRT) display, and is more suitable for display. Dynamic picture.

In addition, the comparison relationship between the sub-gray scales H1, H2, L1, L2 and the pixel gray scale values can be obtained through a lookup table, and the lookup table can be obtained through prior simulation and measurement. Since the general gray scale value is usually 0~255, the degree of color shift corresponding to each gray scale value can be directly measured by measurement, and the selection of the sub gray scales H1, H2, L1, L2 can also be simulated. Learn about the best combination. After determining the correspondence between each grayscale value and the child grayscales H1, H2, L1, and L2, a lookup table can be established. When the display is displayed on the screen, the appropriate sub-gray scales H1, H2, L1, and L2 can be directly selected through the lookup table. In addition, the conversion of the grayscale value and the sub-gradation value can be directly performed by the circuit or directly by the software. It is calculated by calculation, and it is not described here.

4 is a diagram showing relationship between pixel gray scale values and pixel luminance according to the first embodiment of the present invention. The curve RX0 is the relationship between the gray scale and the pixel brightness under the positive angle, and the curve RX60 is the relationship between the gray scale and the pixel brightness measured by the lateral 60 degrees. The curve RXL represents the relationship between the gray scale and the pixel brightness change (also measured by the lateral 60 degrees) of the two sub-pixels and the two sub-pictures (for example, FIG. 3A, FIG. 3B, and FIG. 3C). Comparing FIG. 4 with the conventional FIG. 2, the curve RXL in this embodiment is closer to the curve RX0, that is, the pixel brightness seen at the lateral angle is closer to the positive angle, which can improve the color shift phenomenon. .

In summary, the present embodiment can be summarized as a pixel driving method, as shown in FIG. 5, which is a pixel driving method according to a first embodiment of the present invention. flow chart. The driving method is suitable for driving a liquid crystal panel, the liquid crystal panel includes a plurality of pixels, each pixel is composed of a first sub-pixel and a second sub-pixel. The pixel driving method comprises the following steps: First, in the step In S310, the screen is divided into a first sub-screen and a second sub-screen; then, in step S320, in the first sub-screen, the first sub-pixel is displayed to display the first sub-gray, and the second sub-pixel is displayed. The second sub-gray scale; next, in step S330, in the second sub-picture, the third sub-pixel is displayed with the third sub-gray, and the fourth sub-pixel is displayed with the fourth sub-gray.

The second sub-picture is after the first sub-picture, and the first to fourth sub-gray positions are referred to the sub-gray levels H1, H2, L1, and L2 shown in FIG. 3A to FIG. 3C above. Repeated.

This embodiment replaces the grayscale values of the single pixels by using the spatial and temporal mixed sub-gray scales H1, H2, L1, and L2. Compared with the two sub-pixels in the prior art, the combination changes more, so the gray-scale combination with lower color-shifting phenomenon can be obtained, thereby improving the color-shift phenomenon of the pixel, and the resolution of the liquid crystal panel is not Decreased by the implementation of this technical means.

Second embodiment

The sub-gray scales H1, H2, L1, and L2 may be directly arranged on the same screen, that is, one pixel is divided into four sub-pixels, and the sub-gray scales H1, H2, L1, and L2 are respectively displayed. As shown in FIG. 6, FIG. 6 is a schematic diagram of a child grayscale configuration according to a second embodiment of the present invention. Sub-pixels 610, 620, 630, and 640 represent a pixel unit that displays sub-gray levels H1, L1, L2, and H2, respectively. The correspondence between the sub-gray scales H1, L1, L2, H2 and the pixel gray scale values is as described in the first embodiment above.

In the display, in order to make the gray scale mixing of the sub-pixels more uniform, the configuration of the child gray scales H1, L1, L2, H2 is as shown in FIG. 6, and the sub-pixels 610 and 640 are set in the diagonal for displaying gray. The sub-gray scales H1 and H2 having higher order values are set to the other diagonals, and the sub-gray scales L1 and L2 having lower gray-scale values are displayed. The gray-scale mixing of the sub-pixels 610-640 can be more uniform by the interlaced arrangement of high and low gray levels.

In addition, it should be noted that the configuration of the sub-gray scales H1, L1, L2, and H2 in this embodiment may also directly refer to the configuration manners of FIG. 3A to FIG. 3C, as long as the sub-gray scale corresponding to the second sub-screen is displayed. It can be used in sub-pixels 630 and 640. In other words, in this embodiment, only the four-seed gray scale is mixed with the spatial arrangement to replace the gray scale value of the single pixel, and the color shift phenomenon of the liquid crystal display is reduced by selecting a better combination of the four-seed gray scale. Those skilled in the art should be able to easily infer the configuration of their sub-gray scales after the disclosure of the present invention, and will not be described here.

Figure 7 is a graph showing the relationship between pixel gray scale values and pixel luminance according to a second embodiment of the present invention. The curve RX0 is the relationship between the gray scale and the pixel brightness under the positive angle, and the curve RX60 is the relationship between the gray scale and the pixel brightness measured by the lateral 60 degrees. The curve RXL represents the relationship between the gray scale and the brightness of the pixels after mixing by four sub-pixels (refer to FIG. 6) (also measured by the lateral 60 degrees). Comparing Figure 7 with Figure 4, the curves of the two curves RX60 are quite close, which are closer to the curve RX0 than the conventional one, that is, the gray level value seen from the lateral 60 degrees is close to the gray seen from the positive angle. Order value.

The above second embodiment can be summarized as another pixel driving method, which is suitable for driving a liquid crystal panel, and the liquid crystal panel includes a plurality of pixels, each pixel. The first sub-pixel, the second sub-pixel, the third sub-pixel, and the fourth sub-pixel, the first sub-pixel and the fourth sub-pixel are diagonally arranged, and the second sub-pixel Please refer to FIG. 8 for the above-mentioned pixel driving method, and FIG. 8 is a flow chart of the pixel driving method according to the second embodiment of the present invention.

First, in step S810, the grayscale value corresponding to the pixel is divided into a first child grayscale, a second child grayscale, a third child grayscale, and a fourth child grayscale; then, in step S820, The first sub-pixel displays the first sub-gray scale, the second sub-pixel displays the second sub-gray, the third sub-pixel displays the third sub-gray, and the fourth sub-pixel displays the fourth sub-gray. For the configuration of the first sub-gray to the fourth sub-gray, please refer to the description of the second embodiment above, which will not be described here.

In summary, the present invention divides the grayscale value into four sub-gray scales, so that the elasticity of the combination is higher, and an excellent lower gray scale combination can be configured. In addition, the present invention uses different sub-pictures to respectively display four sub-gray scales, and uses time and space to mix four sub-gray steps, so that the liquid crystal panel can not only reduce the color shift phenomenon, but also maintain a certain resolution. In addition, the present invention further proposes a special sub-gray-level configuration manner according to the dynamic picture, so that the sub-pixel display mode is similar to the pulse mode, which not only achieves the effect of reducing the color shift, but also improves the display quality of the dynamic picture.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

H, L, H1, H2, L1, L2‧‧‧ sub-gray

310, 320, 610, 620, 630, 640‧ ‧ sub-pixels

S510~S530, S810, S820‧‧‧ steps

FIG. 1 is a schematic diagram of a low color tone pixel structure and a driving method thereof according to the prior art.

2 is a graph of gray scale values and pixel luminances according to the pixel of FIG. 1.

3A is a schematic diagram of a pixel driving method according to a first embodiment of the present invention.

FIG. 3B is a schematic diagram of a child grayscale configuration in a still picture according to the first embodiment of the present invention.

FIG. 3C is a schematic diagram of a child grayscale configuration in a dynamic picture according to the first embodiment of the present invention.

4 is a diagram showing relationship between pixel gray scale values and pixel luminance according to the first embodiment of the present invention.

Fig. 5 is a flow chart showing a pixel driving method according to a first embodiment of the present invention.

FIG. 6 is a schematic diagram of a child gray scale configuration according to a second embodiment of the present invention.

Figure 7 is a graph showing the relationship between pixel gray scale values and pixel luminance according to a second embodiment of the present invention.

FIG. 8 is a flow chart of a pixel driving method according to a second embodiment of the present invention.

S510~S530‧‧‧Steps

Claims (4)

A pixel driving method is suitable for driving a liquid crystal panel, the liquid crystal panel includes a plurality of pixels, and one of the pixels includes a first sub-pixel and a second sub-pixel. The driving method includes: dividing a picture into a first sub-picture and a second sub-picture; and in the first sub-picture, causing the first sub-picture to display a first sub-gray, the second sub-picture Displaying a second sub-gray scale; and in the second sub-picture, causing the first sub-pixel to display a third sub-gray scale, the second sub-pixel displaying a fourth sub-gray scale; wherein The first to fourth sub-gray levels correspond to one of the first pixel gray scale values, and when the picture is a dynamic picture, the third sub-gray level is greater than or equal to the first sub-gray level, and the fourth The child gray level is greater than or equal to the second child gray level. The pixel driving method of claim 1, wherein the first sub-gray scale is greater than or equal to the second sub-gray scale, and the third sub-gray scale is less than or equal to the fourth sub-gray scale. The pixel driving method of claim 1, wherein when the picture is a static picture, the first sub-gray level is greater than or equal to the second sub-gray level, and the third sub-gray level is greater than or equal to the The fourth sub-gray. The pixel driving method of claim 1, further comprising reading the first to fourth sub-gradations according to the grayscale value corresponding to the pixel via a lookup table.