JP3165479B2 - 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, each pixel of the three primary colors arranged on the display panel is divided into a plurality of blocks, and the thinning patterns of each block and each frame are set to be different from each other in the pixels of each block. .

[0005]

According to the above-mentioned means, the screen is divided into a plurality of blocks, and the bright lines connecting the illuminated pixels in each block and each frame are different from each other. Since the pattern is not recognized, the moving phenomenon can be substantially prevented.

[0006]

FIG. 4 is a schematic block diagram of a main 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 converted into 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. Therefore, the driving voltages V0 to V input to the driving switch MOSFET
2 is output through the selector SEL. Selector S
In the EL, 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 a block diagram showing an embodiment of a color display screen for explaining a driving system according to the present invention, and an enlarged view of a part thereof. In this embodiment, an active matrix type color liquid crystal display panel using thin film transistors (TFTs) is used.
Is divided into twelve. Then, in the block J exemplarily shown as a representative, the line constituted by the R (red) pixels is a diagonally slanted line to the lower right, and the thinning-out of the halftone data is performed so that the moving direction is directed to the left. The line composed of G (green) pixels is different from the above-mentioned JR (red in the J block) and is a diagonal line that rises to the right and thins out the halftone data so that the moving direction is directed to the left. The line composed of B (blue) pixels is different from the above-mentioned JR and JG (red and green of the J block), and is a diagonally downward slanted line, and the moving direction is intermediate so that the moving direction is rightward. The gradation data is thinned out.

[0012] E, F, G,
I, each block of K is, lines and Mu bins <br/> grayed direction in each color is thinned halftone data as different from each other is performed. The remaining A, B, C, D, Rainto and Mu bicycloalkyl ring direction is set to be different from each other even in relation to the block adjacent to it in each block of the H and L.
That is, in a relatively large area extending over a plurality of blocks of the TFT screen, the line and the moving direction are different from each other, so that a specific bright line is not generated.

FIG. 2 is an enlarged view of one embodiment of a color display screen for explaining the driving method according to the present invention in detail. FIG. 3 shows an example of lighting (white circle) / non-lighting (black circle) of the first frame in the J block. In this embodiment, a set of 3 × 3 pixels is used. For example, if only 3 pixels out of 9 pixels are turned on, when one pixel is smaller than the resolution of the human eye, 3/9 = 1 is given to the human eye.
Appears as / 3 gradation display. 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, when the R (red) pixel is viewed,
The pixels in the columns are lit, the pixels in the first row and second column are non-lit, the first row and third column are non-lit, the pixels in the second row and first column are non-lit, the pixels in the second row and second column are lit, and the second row and third column are non-lit. Non-lighting, pixels in 3 rows and 1 column are non-lighting,
Since the pixels in the third row and the second column are not lit, and the third row and the third column are lit, the lit pixels are arranged in order from the upper left to the lower right. That is, when the pixels in the entire J block are turned on / off as described above, FIG.
A line descending to the right like this appears.

In two frames, the first of the 3 × 3 pixels
Each pixel in the row is right, the second row is left, and the third row is in the center. In three frames, among 3 × 3 pixels, the first row is in the center, the second row is in the right, The pixels on the left of the third row are turned on. In other words, a moving phenomenon occurs in which oblique lines moving downward to the right move leftward when viewed from a plurality of sets of pixels.

In one frame, as in the lighting / non-lighting example of the display panel shown on the upper side, as for the G (green) pixel, the pixels in one row and one column are not lit and the pixels in one row and two columns are Not lit, first row and third column are lit, second row and first column are non lit, second row and second column are lit, second row and third column are non lit, third row and first column are lit, three rows The pixels in the second column are not lit, and the third row and the third column are not lit. Therefore, when this is put together, the lit pixels are arranged from the upper right to the lower left. When the pixels of the entire J block are turned on / off as described above, FIG.
As shown in the figure, a line descending to the left is generated.

In two frames, the first of the 3 × 3 pixels
The pixels in the center of the row, the left in the second row, and the right in the third row are lit. In the three frames, among the 3 × 3 pixels, the first row is the left, the second row is the right, In the third row, each pixel at the center is lit. In other words, a moving phenomenon occurs in which oblique lines moving leftward move leftward when viewed from a plurality of sets of pixels.

In one frame, as in the lighting / non-lighting example of the display panel shown on the upper side, regarding the B (blue) pixel, the pixels in one row and one column are lit, and the pixels in one row and two columns are non-lighted. Lit, 1st row, 3rd column is not lit, 2nd row, 1st column is not lit, 2
The pixels in row 2 and column 2 are lit, the rows 2 and 3 are not lit, the pixels in row 3 and column 1 are not lit, the pixels in row 3 and column 2 are not lit, and the rows 3 and 3 are lit. In summary, the lighting pixels are arranged from the upper left to the lower right. When the pixels in the entire J block are turned on / off as described above, a line which is lower right is generated as shown in FIG.

In two frames, the first of the 3 × 3 pixels
The pixels in the middle of the row, the right in the second row, and the left in the third row are lit. In the three frames, among the 3 × 3 pixels, the first row is the right, the second row is the left, In the third row, each pixel at the center is lit. In other words, a moving phenomenon occurs in which oblique lines moving to the lower right move rightward when viewed from a plurality of sets of pixels.

As described above, the moving phenomenon occurs only in the limited small blocks so that the moving phenomena differs from one color to another. As a result, when viewed from a relatively large area on the color display panel, each color is displayed in a dispersed manner, and conspicuous bright lines (lines) such as one oblique straight line do not occur.
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 substantial problem since no noticeable line such as a bright line is generated.

In this embodiment, the lighting pattern of the three primary color pixels in the same frame is made different in one block, and this is performed for each frame so as to be different from each other in a plurality of blocks of the entire screen. This is intended to reduce the concentration of lit parts and non-lit parts. Thereby, for example, when the entire screen or a large display area is displayed in gray with 1/3 gradation using the three primary colors, the moving image becomes inconspicuous, and characters and the like displayed with the moving image as a background can be easily seen.

FIG. 3 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, the color information is R, and the block information is J, the thinning circuit is 100 at the first scanning timing for one frame, and the second scanning. 010 is formed at the timing, and 001 is formed at the third scanning timing. 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, 010 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. If the block information is J
, The binary pattern is made different according to each. Therefore, the thinning circuit can be constituted by a decoder circuit (logic gate circuit) that receives halftone data such as 01 and 10, frame information, color information and block information. Or,
It can be constituted by a pattern generating circuit using a ROM (Read Only Memory) having each of the above information as an address.

The functions and effects obtained from the above embodiment are as follows. (1) In multi-tone display by FRC, each pixel of the three primary colors arranged on the display panel is divided into a plurality of blocks, and the thinning patterns of each block and each frame are different from each other in the pixels of each block. By setting as described above, since the bright lines connecting the lighting pixels are different from each other for each color and for each block and each frame divided on the screen, a specific bright line is not recognized on the display screen. This has the effect of preventing it. (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 embodiments, the invention of the present application is not limited to the above embodiments, 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.

[0029]

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 the FRC, each pixel of the three primary colors arranged on the display panel is divided into a plurality of blocks, and the thinning patterns of each block and each frame are set to be different from each other in the pixels of each block. Therefore, since the bright lines connecting the lighting pixels are different from each other for each color and for each block and each frame divided on the screen, a specific bright line is not recognized on the display screen, so that the moving phenomenon is substantially prevented. Can be.

[Brief description of the drawings]

FIG. 1 is a configuration of a color display screen and a partially enlarged view for explaining an embodiment of a driving method according to the present invention.

FIG. 2 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. 3 is a schematic block diagram of an entire display device to which a driving method of a color display device according to the present invention is applied.

FIG. 4 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.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-11393 (JP, A) JP-A-2-291521 (JP, A) JP-A-2-993 (JP, A) JP-A-63- 97921 (JP, A) JP-A-3-20780 (JP, A) (58) Fields investigated (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, the combination of the lighting pixels is changed in three ways.
And the display screen has multiple screens in each of the vertical and horizontal directions.
To form a plurality of display blocks, and in each of the display blocks, the above-described pixel set performs １ ／ gradation display.
When performing, the lighting pixels corresponding to any one color
Line and its moving direction are in the first direction
One time, it is composed of lighting pixels corresponding to other colors
The line and its moving direction are different from the first direction
Combination of the above 1/3 gradation pixels in the second direction
Set colors and support each color even between adjacent display blocks
Line composed of lit pixels and its moving
A method for driving a color display device, wherein directions are different from each other . 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
The driving method of a color display device, characterized in that it is intended to be formed based on the 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.