JP3165478B2 - Driving method of color display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving system for a color display device, and more particularly to a technique effective for driving a color liquid crystal display device for displaying color gradation.

[0002]

2. Description of the Related Art As one of the gradation display technologies using liquid crystal,
There is FRC (Frame Rate Control). According to this technique, gray scale display is performed by controlling display data between frames and changing the effective value of the liquid crystal drive voltage. Regarding this FRC, for example, 199
One year, "Flat Panel Display '91", pages 173 to 180, published by Nikkei Electronics and Nikkei Microdevices.

[0003]

In the case of the FRC, as pointed out in the document, when viewed on a large screen,
The line (bright line) connecting the lighting pixels moves for each frame. This movement of the bright line is called moving. The speed of this moving phenomenon is proportional to the frame frequency, and at a practical frame frequency of 60 Hz to 70 Hz, this moving phenomenon is conspicuous, which hinders practical use of multi-tone display by FRC. The purpose of this invention is
An object of the present invention is to provide a driving method of a color liquid crystal display device in which a moving phenomenon is substantially suppressed. The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0004]

The following is a brief description of an outline of a typical invention among the inventions disclosed in the present application. That is, in the multi-tone display by the FRC, the thinning-out pattern for each frame is set to be different for each pixel of the three primary colors arranged on the display panel.

[0005]

According to the above-mentioned means, since the bright lines connecting the lighting pixels are different from each other for each color and each frame, a specific pattern by the bright lines is not recognized, so that the moving phenomenon can be substantially prevented.

[0006]

FIG. 3 is a schematic block diagram showing an essential part of an embodiment of a color liquid crystal display device to which the present invention is applied. The signal line driving circuit has a function of driving m signal lines D1 to Dm including 1 to m. Although not particularly limited, when the number m of signal lines of the liquid crystal display panel LCD is large, m signal lines are divided and driven by a plurality of signal line driving circuits. Pixel data is fetched serially from the input terminal Din and output in parallel. That is, the latch circuits FF1 to FFm are:
It constitutes a shift register and latch having a serial / parallel conversion function. Data Din input to the shift register & latch is binary data. Therefore, as will be described later, the intermediate gradation data is processed by a thinning circuit such as lighting / non-lighting for each frame and input.

The pixel data held in the latch circuits FF1 to FFm is transmitted in parallel to the level shifters LS1 to LSm. Level shifters LS1 to LSm
Forms a control signal of a switch MOSFET for selectively outputting the driving voltages V0 to V2 formed by a driving voltage generating circuit (not shown) in accordance with the input pixel data.

The latch circuits FF1 to FFm constituting the shift register and latch are not particularly limited,
Since it operates by receiving a power supply voltage of about 5 V, a signal consisting of a high level of about 5 V and a low level of 0 V is output. On the other hand, the driving voltages V0 to V2 supplied to the liquid crystal display panel are set to a relatively high level. Therefore, the level (5
V, 0 V), the switch MOSFET may not be able to be turned on or off, so that the level is shifted by the level shifters LS1 to LSm to an appropriate level.

The switch MOSFETs Q1 to Q3 exemplarily shown as representatives constitute a drive circuit of a unit corresponding to one signal line D1, and one of the drive voltages V0 to V2 formed as described above. One is transmitted to the signal line D1. It is necessary to invert the polarity of the liquid crystal common electrode for AC driving of the liquid crystal. The above voltage V0
V2 is a polarity control signal for the AC drive signal M for AC drive. That is, V0 is a voltage of 0 V with respect to the common electrode, and turns on the pixel. In other words, light is transmitted with the transmittance of the liquid crystal being 100%. V1 is a positive drive voltage, which sets the transmittance of the liquid crystal to 0 and turns off the liquid crystal. V2 is a negative drive voltage, and the liquid crystal is turned off by setting the transmittance of the liquid crystal to 0 as described above. That is, the drive voltages V0 to V2 input to the drive switch MOSFET
Is output through the selector SEL. Selector SE
In L, the drive voltage V1 or V2 is switched by the AC signal M.

In FIG. 1, one scanning line drive circuit GDV is arranged on the left side of the liquid crystal display panel LCD.
The scanning line driving circuit GDV sequentially selects scanning lines extending in the horizontal direction of the liquid crystal display panel LCD. In a liquid crystal display panel having an active matrix configuration, selection of a TFT transistor is performed by the scanning line. As a result, the respective drive voltages transmitted in parallel from the signal lines D1 to Dm are written to the liquid crystal pixels corresponding to the selected scanning line. The liquid crystal pixel acts equivalently as a capacitor and holds the written drive voltage until the next drive voltage is written.

FIG. 1 is an enlarged view of one embodiment of a color display screen for explaining a driving method according to the present invention. The drawing shows an example of lighting (white circle) / non-lighting (black circle) of the first frame. In this embodiment, 3 × 3
When one pixel is smaller than the resolution of the human eye, for example, if one pixel is smaller than the resolution of the human eye, 3/9 = 1/3 gradation display is made to the human eye. Then, the positions of the lighting pixels are moved every three frames to eliminate the flicker phenomenon.

The above 1/3 gradation is for one color. On an actual color display panel, as shown in FIG. 1, a color filter formed by repeating RGB, RGB... It is formed in a stripe shape. Therefore, a set of three primary color pixels is composed of 3 × 3 × 3 = 27 pixels arranged in three rows and three columns as shown by a dotted line in FIG.

On the lower side of the figure, there is shown a lighting / non-lighting display pattern when the colors are combined for each color. In one frame, as in the lighting / non-lighting example of the display panel shown on the upper side, as for the R (red) pixel, the pixels in one row and one column are lit, the pixels in two rows and two columns are non-lit, The row 3 column is not lit, the 2 row and 1 column pixel is not lit, the 2 row and 2 column pixel is lit,
The second row and the third column are not lit, the pixels of the third row and the first column are not lit, and the third row and the second column are not lit.
The pixels in the column are not lit, and the third row and the third column are lit. Therefore, when this is put together, the lit pixels are arranged from the upper left to the lower right. Regarding the G (green) pixel, the pixels in the first row and the first column are not lit, the pixels in the first row and the second column are lit, the first row and the third column are not lit, the pixels in the first row and the second column are lit, and the second row and the second column Pixels are not lit,
The second row and the third column are not lit, the pixels of the third row and the first column are not lit, and the third row and the second column are not lit.
The pixels in the column are not lit, and the third row and the third column are lit. Therefore, when this is put together, the lit pixels are arranged from the upper right to the lower left. Regarding the B (blue) pixel, the pixels in the first row and the first column are lit, the pixels in the first row and the second column are not lit, the first row and the third column are lit, the second row and the first column are not lit, and the second row and the second column Pixel lights up,
The second row and the third column are not lit, the pixels of the third row and the first column are not lit, and the third row and the second column are not lit.
The pixels in the column are not lit, and the third row and third column are lit. Therefore, when this is put together, the lit pixels are arranged from the upper left to the lower right. However, on the color display screen, the illuminated pixels are dispersed so that a conspicuous bright line such as one oblique straight line does not occur.

In the two frames, among the 3 × 3 pixels of R, each pixel in the first row is on the right, the second row is on the left, and the center of the third row is on. Of the 3 × 3 pixels, the first row is centered, the second row is left, and the third row is right, and in B, of the 3 × 3 pixels, First
The pixels in the center of the row, the right in the second row, and the left in the third row are lit. This is similarly dispersed and displayed on the above-mentioned color display panel, so that a conspicuous bright line such as an oblique straight line can be prevented.

In three frames, R is 3
Among the × 3 pixels, the first row is centered, the second row is right, the third row is left, and each pixel is lit. For G, the first row of 3 × 3 pixels is Is on the left, the second row is on the right, and the third row is on the center of each pixel. For B, of the 3 × 3 pixels,
The pixels on the first row are on the right, the second row is on the left, and the third row is on the center. This is similarly dispersed and displayed on the above-mentioned color display panel, so that a conspicuous bright line such as an oblique straight line can be prevented. In the case of 2/3 gradation, among the 3 × 3 pixels, the number of illuminated pixels is as large as six. Therefore, there is no problem because a noticeable line such as a bright line does not occur.

In this embodiment, the lighting pattern of the three primary color pixels in the same frame is made different and is performed for each frame, so that the concentration of the lit portion and the non-lit portion in the entire screen is reduced. It is to be. Accordingly, when the entire screen or a large display area is displayed in gray (gray) with the three primary colors, for example, moving is unlikely to occur, and the displayed characters and the like can be easily viewed.

FIG. 2 is a block diagram showing one embodiment of the entire display device. The display system is a source of pixel data, and includes, for example, a display controller such as a CRTC or a VGA, and a frame memory in which color image data is written. When the data read from the frame memory is composed of four levels of full lighting, 2/3 gray scale, 1/3 gray scale and all non-lighting as described above,
Data per pixel is composed of 2 bits. For example, 11 is full lighting, 2/3 gradation is 10, and 1/3 gradation is 0.
1. All non-lighting is assigned like 00.

The pixel data from such a frame memory is repeatedly read out in synchronization with the display operation of the display device. The thinning-out circuit 1 for all lighting and all non-lighting data unconditionally means 1 and 0 means non-lighting.
And output. Data 1 indicating intermediate gradation
For 0 or 01, the following thinning is performed. That is, it is converted into data of 1 meaning lighting and 0 meaning non-lighting for each frame and output.

If the frame information is 1 and the gradation data is 01 and the color information is R and the color information is R, the thinning-out circuit is 100 at the first scanning timing in one frame, 010 at the second scanning timing, and At the scanning timing, 001 is formed. For the color information G, 001 is formed at the first scanning timing in one frame, 010 is formed at the second scanning timing, and 100 is formed at the third scanning timing. 100 is formed at the scanning timing, 101 is formed at the second scanning timing, and 001 is formed at the third scanning timing.

When the frame information changes like 2 or 3, the thinning circuit converts the data into 1-bit data for each pixel according to the lighting / non-lighting of the two frames and three frames in FIG. Output. Therefore, the thinning-out circuit
It can be constituted by a decoder circuit (logic gate circuit) that receives intermediate gradation data such as 1, 10 and frame information and color information. Alternatively, an RO using the above information as an address
It can be constituted by a pattern generation circuit using M (read only memory).

The functions and effects obtained from the above embodiment are as follows. (1) In multi-tone display by FRC, by setting the thinning-out pattern for each frame to be different from each other for each of the three primary colors of color arranged on the display panel, the bright lines connecting the illuminated pixels are different from each other. Since a specific bright line is not recognized on the display screen, the moving phenomenon can be substantially prevented. (2) According to the above (1), an effect that a multi-color display can be performed using a color liquid crystal display panel with a simple configuration can be obtained.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention of the present application is not limited to the embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say. For example, the liquid crystal display panel may have a simple matrix configuration. That is, in the FRC of this embodiment, halftone display is performed by thinning out pixel data for each frame. The color display panel is only required to be capable of binary display of light and dark according to the drive voltage. Therefore,
In addition to liquid crystal, any other device that performs color display by the same binary display may be used. LCD drive voltage and lighting /
The non-lighting relationship may be such that the light is turned on by application of a driving voltage such that the directions of polarizing plates provided with the liquid crystal interposed therebetween are orthogonal to each other. One pixel combination is:
3 (R, G, B) × 2 (columns) × 2 (rows) with three frames consisting of full lighting, half gradation and all non-lighting in two frames, and 3 (R, G, B) × 4 (row) × 4
(Non-lighting, 1/4 gradation, 4 frames)
Various embodiments can be adopted, such as 2/4 gray scale, 3/4 gray scale, and 5 gray scales including all lighting. The present invention can be widely used as a driving method for a color display device.

[0023]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows. That is, in the multi-tone display by FRC, by setting the thinning patterns for each frame to be different from each other for the pixels of the three primary colors arranged on the display panel, the bright lines connecting the lighting pixels are changed for each color and each frame. Since no specific bright line is recognized on the display screen, the moving phenomenon can be substantially prevented.

[Brief description of the drawings]

FIG. 1 is a pattern diagram of a lighting example of a display panel and a lighting example of each color for each frame for describing an embodiment of a driving method of a color display device according to the present invention.

FIG. 2 is an overall schematic block diagram of a display device to which a driving method of a color display device according to the present invention is applied.

FIG. 3 is a schematic block diagram showing one embodiment of a color liquid crystal display device used in the present invention.

[Explanation of symbols]

FF1 to FFm: shift register and latch, LS1 to L
Sm: level shifter, SEL: selector, Q1-Q3 ...
Switch MOSFET, LCD: Liquid crystal display panel, GD
V: scanning line driving circuit, G1 to G480: scanning line electrodes, D
1 to Dm: signal line electrodes.

Continuation of front page (56) References JP-A-3-118596 (JP, A) JP-A-3-11393 (JP, A) JP-A-2-291521 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) G09G 3/00-3/38 G02F 1/133 505-580

Claims (3)

(57) [Claims] Multiple lines in the vertical direction of 1. A display screen, a plurality of rows arranged in the lateral direction, and left and right directions along connexion red, green, and three primary colors picture element which are arranged repeatedly in a predetermined color order of blue, Voltages of a plurality of signal lines extending in the vertical direction of the display screen are sequentially applied in accordance with signals of a plurality of scanning lines extending in the horizontal direction of the display screen to perform a lighting operation for one frame of the display screen. a method of driving a color display device in which, mosquito arranged in three rows and three columns of the three primary colors image Motono
Pixel set composed of three primary color pixels
In each of the three primary color pixels,
Three cycles as one cycle, all lighting, 1/3 gradation, 2/3 floor
The tone display consisting of the tone and all non-lighting is performed.
In the 1/3 gradation display, the combination of the lighting pixels changes in three ways.
Allowed to reduction, when performing 1/3 gradation display in the pixel group, Izu
Lighting pixel corresponding to one color goes from upper right to lower left
When the pixels are lined up, the lighting pixels corresponding to other colors
A method for driving a color display device, characterized by being combined so as to line down . 2. The camera according to claim 1, wherein the red, green, and blue colors are repeatedly arranged in a predetermined color order.
The three primary color pixels are scanned in the horizontal direction of the display screen.
A line selected by the line and repeatedly arranged in the predetermined color order of red, green, and blue.
Each of the three primary color pixels extends in the vertical direction of the display screen
To receive the lighting / non-lighting voltage from the signal line
Yes, the lighting / non-lighting and voltage are supplied to the color display device
Half-tone data, color information and
A method for driving a color display device, wherein the method is formed based on frame information . 3. The method for driving a color display device according to claim 1, wherein the display screen is provided with a stripe-shaped color filter corresponding to each of the signal lines.