JPH03164793A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce flicker or the unevenness of display by rewriting a dot pattern adapted for a liquid crystal display unit in a gradation pattern memory for the liquid crystal display unit having different characteristic. CONSTITUTION:The data on the dot pattern in which gradation display is performed by a pattern thinning system is stored. The gradation data of a dot for display, frame information showing what number of frame it is in one display cycle, and horizontal and vertical position information showing the position of the dot in the dot pattern are inputted at the address of the gradation pattern memory 6 which can be rewritten by an external operation. The display of the liquid crystal display unit 4(dot matrix) is controlled according to the display on/off information of the dot obtained from the gradation pattern memory 6 in a frame memory readout and liquid crystal display circuit 3. Thus, the flicker or the unevenness of the liquid crystal display is reduced by properly changing to the pattern for thinning adapted for the characteristic, etc., of the liquid crystal display unit 4 which is an object.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a liquid crystal display device that displays a screen based on a video signal and a luminance signal from, for example, a personal computer in gradations using a pattern thinning method on a dot matrix type liquid crystal display unit. It is related to.

<Prior Art> Conventionally, a thinning method has generally been adopted as a gradation display in a focus matrix display type liquid crystal display device.

This thinning method uses, for example, a display cycle of 16 frames as one display position, and the dots, for example rAJ
If the gradation data of the dot indicated by is "16",
The rAJ dot is displayed in each of the 16 frame scans in the display cycle, and if the gradation data is rOJ, the rAJ dot is kept in a non-display state in any of the 16 frame scans. .

In this way, by displaying each dot the number of times corresponding to its gradation data in 16 frame scans, 17 gradation levels are displayed.

However, the gradation display using the above-mentioned thinning method has the drawback that flickering occurs when displaying halftones. This flickering becomes more noticeable as the area of the display screen becomes larger, even for the same gradation.

Therefore, in order to reduce flicker, a pattern-based thinning method has been adopted in recent years. This pattern thinning method will now be explained for a range of 4 horizontal dots x 2 vertical dots shown in FIG.

Here, the number of dots that are lit at the same time is an even number of 2.4 and 6.8, and five gradation levels including non-display can be displayed. When the floor 8 lap data is rlJ, the arrangement of the two display doors (/) is sequentially changed to the four patterns shown in FIG. 2 (al to (d)), and these four patterns are
By repeating the display cycle, intermediate gradations are displayed. Note that the shaded areas in the figure are display dots.

Therefore, each of the eight dots rAJ to fHJ shown in FIG. 3 is always displayed once in one display cycle using the four patterns shown in FIG. 2 (al to (d)), and the dots displayed simultaneously are dispersed. Because of this, large flickering does not occur even when the same gradation is displayed on a large-area screen.

<Problem to be solved by the invention> By displaying gradations using the pattern thinning method as described above, it is possible to considerably reduce flickering on a large screen, but since the pattern is manipulated again, even the smallest flickering can be completely removed. I can't.

The occurrence of liquid crystal display unevenness called fine flickering or ghosting varies greatly depending on the characteristics of the liquid crystal material, the characteristics of the driver for the liquid crystal display unit, and the like. On the other hand, since the dot pattern thinned out for each pattern in one display cycle is constant, even if the above-mentioned fine flickering or liquid crystal display unevenness becomes extremely worse due to liquid crystal display units with different characteristics, this problem cannot be solved at all. There is.

The present invention has been made in view of these conventional problems, and aims to reduce flickering and unevenness in liquid crystal display as much as possible by appropriately changing the thinning pattern to adapt to the characteristics of the target liquid crystal display unit. It is a technical issue to provide a liquid crystal display device that can reduce the amount of noise.

<Means for Solving the Problems> In the present invention, as a technical means for achieving the above-mentioned problems, a liquid crystal display device is configured as follows. That is, in a liquid crystal display device in which a video signal or the like is signal-processed by a liquid crystal display driving means into gradation display data that matches the format for the liquid crystal display, and the gradation is displayed on a dot matrix type liquid crystal display unit, the gradation display is performed using a pattern thinning method. A gradation pattern memory in which dot pattern data to be displayed is stored and can be rewritten by external operations, gradation data of display dots, frame information indicating which frame in one display cycle, and dot position in the dot pattern is stored. and a liquid crystal display circuit that manually inputs horizontal and vertical position information to the address of the gradation pattern memory and controls the display of the liquid crystal display unit based on dot display on/off information obtained from the gradation pattern memory. It is structured with the following characteristics.

For example, gradation data corresponding to one screen of the video signal is created based on the color video signal and luminance signal of the video signal from a personal computer, and this gradation data is calculated based on the number of frames in one display cycle. For example, RA
It is stored at an address in a rewritable gradation pattern memory consisting of M.

The gradation pattern memory outputs the display on/off information stored at the input address to the liquid crystal display circuit. Based on the information on whether each dot in the data is displayed on or off, serial liquid crystal display data for driving the liquid crystal display unit that conforms to the liquid crystal display format is created, and this liquid crystal display data is The signals are output to a liquid crystal display unit, and the liquid crystal display unit inputs these signals and displays an image corresponding to the screen of the video signal in gradation.

In this liquid crystal display device, a readable/writable RAM or the like is used as the gradation pattern memory, so by rewriting the dot pattern adapted to the gradation pattern memory for liquid crystal display units with different characteristics,
Flickering and display unevenness can be reduced as much as possible without changing the controller unit as a liquid crystal display driving means.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention in which a screen based on a video signal from a personal computer is displayed in gradation on a liquid crystal display unit.

In the figure, a horizontal/vertical timing and clock generation circuit 1 is connected to a clock input from a personal computer or the like.
R7 Horizontal synchronizing signal H1m'l'lc% for driving the display device
Vertical synchronization signal V SVI'le, color video signal R,
Based on the G, B and luminance signals I, a horizontal timing signal Hblank, a vertical timing signal Vblank, and a clock signal CLock for controlling the operation of the frame memory writing circuit 2 are created, and color video signals R, G of the video signals are generated. .

Then, the frame memory writing circuit 2 writes the gradation data corresponding to one screen of the video signal input to the frame memory writing circuit 2 into the address of the frame memory of the frame memory circuit 5 corresponding to that screen at a predetermined timing. It is written sequentially in synchronization with the signal and is temporarily stored.

When writing of the gradation data to the frame memory is completed, the read/write switching signal of the frame memory write circuit 2 switches to a data read mode in which the data of the frame memory can be read. The gradation data stored in the frame memory is sequentially read out in synchronization with a data read signal that matches the display timing.

This read gradation data includes: (1) frame information indicating what frame in the display cycle it is, and horizontal and vertical information indicating where the dot is located in the horizontal and vertical directions in the dot pattern. Together with the vertical position information, it is stored at an address in a readable/writable gradation pattern memory 6 consisting of RAM, E''FROM, and EFROM.

The gradation pattern memory 6 reads the display on/off information stored at the input address from the frame memory and outputs it to the liquid crystal display circuit 3. In the frame memory readout and liquid crystal display circuit 3, the format for the liquid crystal display is adapted based on information about whether each dot in the frame, horizontal/vertical position, and gradation data obtained from the input data is displayed on or off. Serial liquid crystal display data for driving the liquid crystal display unit is created, and this liquid crystal display data is output to the dot matrix type liquid crystal display unit 4 as serial data for liquid crystal display together with a liquid crystal display synchronization signal and a data shift clock signal. The liquid crystal display unit 4 inputs these signals and displays an image corresponding to the screen in gradation.

Note that write and read access to the frame memory is performed in a time-division manner, and read access is performed between write accesses, the read gradation data is latched, and the data is processed to match the format of the liquid crystal display. and display it on the LCD.

In addition, when a liquid crystal display unit 4 with different characteristics is used, a gradation pattern rewriting signal is sent from the external operation unit 7 to the gradation pattern memory 6 which can be read and written, and the dots in the gradation pattern memory 6 are By rewriting the pattern to adapt to the characteristics of the liquid crystal display unit 4, it is possible to correspond to each liquid crystal display unit 4 having different characteristics without changing the controller section, and flickering and unevenness in liquid crystal display can be reduced as much as possible.

Furthermore, by rewriting the door pattern for gradation display, you can change the lower gradation display, such as changing 16 gradations to 8 gradations, or change the gradation data to a fixed pattern. You can easily do what you said.

<Effects of the Invention> As described above, according to the liquid crystal display device of the present invention, since a rewritable RAM or the like is used as a gradation pattern memory, it is possible to create dot patterns that are suitable for liquid crystal display units with different characteristics. By rewriting to the gradation pattern memory, flickering and display unevenness can be reduced as much as possible without changing the controller section as the liquid crystal display driving means.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a pattern thinning method which is a gradation display means according to the present invention, and FIG. 3 is a dot arrangement diagram thereof. 3... Frame memory readout and liquid crystal display circuit 4
−・Liquid crystal display unit・−gradation pattern memory Patent applicant Sharp Corporation representative

Claims (1)

[Claims] (1) Signal processing the video signal etc. into gradation display data that matches the format for the liquid crystal display by the liquid crystal display driving means,
In a liquid crystal display device that displays gradation on a dot matrix type liquid crystal display unit, there is a gradation pattern memory in which dot pattern data for gradation display is stored using a pattern thinning method and can be rewritten by external operation, gradation data of display dots, Frame information indicating which frame in one display cycle and horizontal/vertical position information indicating the position of the dot in the dot pattern are input to the address of the gradation pattern memory, and the dots obtained from the gradation pattern memory are input. and a liquid crystal display circuit that controls the display of the liquid crystal display unit based on display on/off information.