JPH0361924A - Control method for multi-gradation display - Google Patents

Abstract

PURPOSE:To suppress the generation of flowing stripes as less as possible and to express an easily observable image by changing the size of an effective dot matrix in accordance with gradation. CONSTITUTION:As shown in the sizes of effective dot matrixes in gradations 1 to 6, dot expressed by circles are made effective in a certain gradation and other dots are made effective in the succeeding frame to attain the gradation expression of characters or graphics. Since the size of effective dot matrix is changed in accordance with the gradation, the possibility of mutual interference between the effective dot in a certain frame and that of the succeeding frame is reduced. Consequently, the generation of flowing stripes due to the mutual interference of the effective dots can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a multi-gradation display that displays images such as characters and figures in multiple gradations.

[Conventional technology]

A liquid crystal display (LCD) is known as an example of a device that can display images in multiple gradations. LCD like this
In order to express gradation, we usually first consider n dots in the horizontal direction, and express the gradation difference by how many of these dots are enabled (and light up if there is data), and these effective dots are calculated in frame units. By changing the position of the effective dot, the position of the effective dot is prevented from being fixed. Conventionally, the repetition cycle in the vertical direction at this time was the same for all gradations, for example, the same number of n dots as in the horizontal direction.

That is, by considering an effective dot matrix of n dots by n dots and moving the effective dots within this matrix vertically up and down or horizontally left and right in units of frames, multi-gradation expression is possible. this,
This will be explained with reference to FIG.

First, for a display body in which a large number of dots are arranged in a matrix, an effective dot matrix of 8×8 dots is set as shown in the figure. In the example shown in FIG. 5A, all dots in the first row in the horizontal direction in the first frame are set as effective dots as indicated by circles in the figure. In the next second frame, all of the eighth row in the horizontal direction is set as a valid dot like a triangle mark, and in the next third frame,
All the seventh rows in the horizontal direction are made into valid dots like a cross mark. In this way, each of the 8.times.8-64 dots becomes effective once in each of the eight frames from the first to the eighth frame, making it possible to display 1/8 gradation. In the example shown in FIG. 3B, the effective dots in each frame are arranged in one diagonal row. This method also makes it possible to display an image at 1/8 gradation similar to that shown in FIG.

[Problem to be solved by the invention]

However, with the above-mentioned conventional technology, if the range occupied by each gradation image is larger than n dots x n dots, some flow stripes will appear, but if it is smaller than that, especially
When tiling is performed using different gradations, there is a problem in that effective dots interfere with each other, resulting in more noticeable streaks. On the other hand, JP-A-63-287828
No. 3, discloses a method for driving an LCD in which flicker (display flickering) is prevented by dispersing dots that blink in the same phase on the screen. However, even with this method, it is difficult to solve the problem that effective dots interfere with each other and cause flow stripes.

The present invention aims to solve the above problems.

[Means to solve the problem]

The method for controlling a multi-gradation display according to the present invention is to provide a control method for a multi-gradation display body in which a large number of dots are distributed in a matrix on a two-dimensional plane.
When controlling a display such as a CD, by selectively turning on and off the many dots described above, the dots can be used as effective dots for displaying an image, and the image can be displayed in multiple levels on the display. When determining the distribution of effective dots on a frame-by-frame basis, the size of the effective dot matrix, which is the basis of the distribution of effective dots, is determined based on the display gradation level of the image in at least one of its row and column directions. It is characterized by being different depending on.

Here, the arrangement of effective dots in the effective dot matrix may be distributed in the row and column directions in units of frames.

[Effect]

According to the configuration of the present invention, since the size of the effective dot matrix differs depending on the gradation, the possibility that effective dots in one frame and effective dots in the next frame will interfere with each other is reduced.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram explaining the basic system of the present invention, and FIG.
-(f) respectively indicate the size of the effective dot matrix from gradation 1 (1/8 gradation expression) to gradation 6 (7/8 gradation expression). In other words, the horizontal direction is 8 dots, and the vertical direction is gradation 1 (
- gradation 6) - 8 dots, gradation 2 (- gradation 5) - 5 dots, and gradation 3 (- gradation 4) - 3 dots. In each effective dot matrix, the dots indicated by circles in the figure are made effective in one frame, and another dot is made effective in the next frame, making it possible to express gradation of characters and figures. There is.

Specifically, for example, in the first frame, the first dot in the horizontal direction indicated by a circle in FIG. In the third frame, the seventh dot above it is set as the effective dot. Then, in the ninth frame, the first dot is made valid as in the first frame, and this process is repeated thereafter. Then, in the example shown in Figure 1(a), each of the 8x8-64 dots becomes valid once in 8 frames, so 1
/8 gradation expression is possible.

FIG. 2 shows a modification of the basic scheme of the invention.

In this example, unlike the one in FIG. 1, the effective dots in each frame are distributed and arranged in the effective dot matrix. That is, the effective dots are distributed almost evenly in the horizontal and vertical directions of the effective dot matrix, and the positions of the effective dots are shifted in the vertical direction for each frame. Therefore, at gradation 1, it occurs once every 8 frames, and at gradation 2, it occurs once every 8 frames.
Control is performed so that each dot becomes effective once every frame, and once every three frames at gradation level 3. In addition, at gradation 4, gradation 5
In this case, each dot is controlled to become effective four times in every five frames, and in the case of gradation 6, each dot becomes effective seven times in every eight frames.

The method of the present invention is characterized in that the size of the effective dot matrix in at least one of the horizontal and vertical directions is made different depending on the gradation. That is, when the effective dot matrix is n dots and 10 m dots (m and n are natural numbers), at least one of m and n is set to a different value depending on the gradation. Here, the arrangement pattern of effective dots in a certain frame is set as an initial pattern,
The next occurrence of this same pattern will take a frame (
Assuming that (K is a natural number) operations are required, each dot of the effective dot matrix becomes effective the same number of times in this latest frame. Specifically, in the case of Figure 2(a), each dot is activated once in eight frames, and in the case of Figure 2(e), each dot is activated four times in five frames. validate. This enables uniform gradation expression.

Therefore, in the present invention, it is possible to perform control such that, for example, a dot immediately below a dot that is enabled in a certain frame becomes effective in the next frame, and a dot below it becomes effective in the next frame. Not required. In the present invention, if the size of the effective dot matrix is set to be different between different gradations, and each dot is made effective the same number of times between a predetermined number of frames, the dispersion of the effective dots can be reduced. Various modifications can be made to the shift mode and the like. Furthermore, the display is not limited to LCDs, but can also be EL (electroluminescence) panels or PD (plasma display) panels, as long as they display images in multiple gradations by selectively lighting up and turning off a large number of dots. It's also good.

Next, a specific example of the method for controlling a multi-gradation display according to the present invention will be described with reference to the method applied to an LCD.

3A and 3B are diagrams showing a specific structure of the LCD, in which FIG. 3A is a planar configuration diagram and FIG. 3B is a diagram schematically showing a dot matrix of the display panel. The display portion 1 of the liquid crystal panel is formed at the intersection of 200 horizontal scanning electrodes 2-2 and 640 signal electrodes 3-3, and therefore includes 2008640 dots.

A horizontal scanning signal X - It will be done. Signal type 640゛ The pole drive circuit 5 is composed of 80 element circuits 5□~5, the first element circuit 5□ receives the DE80 overnight signal Y-Y, and the next element circuit 52 receives the 80 data signal Y9~ Each receiver has an output of data signal Y of 8 dots, such as 1B.

In the device shown in FIG. 3(a), the signal electrode drive circuit 5 receives the data signal Y in units of each element circuit 5 to 58o.
-Y, but the scanning electrode part B40 motion circuit 4 sequentially outputs the horizontal scanning signal X1 to horizontal scanning signal X, and when it outputs the horizontal scanning signal
After that, horizontal scanning signals X, X3°12, . . . are sequentially output. Here, the scanning signal X2o1
For ~X, there are no corresponding scanning electrodes 2281-092, so the effective portion of the panel in the vertical direction is 200 dots. Therefore, if the display portion 1 realized by the apparatus shown in FIG. 3(a) is represented by a dot matrix, it can be expressed as shown in FIG. 3(b). In designing a practical LCD for image display, it is desirable to use two 200 dots x 640 dots panels to form a 400 dots x 640 dots display.

FIG. 4 shows a detailed configuration of the element circuit 5□ shown in FIG. 3(a).

As shown in the figure, the element circuit includes a gradation data decoder 6, an effective dot matrix generation circuit 7, and an output gate circuit GT. The gradation data decoder 6 has R, G (
The 3-bit color signal of (most significant bit) and B (least significant bit) is decoded, and one of the gradation signal output terminals from 0 to 7 is made valid, ie, "1". The output terminal for gradation 0 is an oven, so! When NNO3 is present, the data signal Y - Y8 is always zero, and the output terminal for gradation 7 is directly input to the OR gate of the output gate circuit GT, so when the gradation is 7, the data signal Y - Y8 is always zero.
-Y8 is always "1", ie, valid. Therefore, it is necessary to control the blinking of each dot at gradations 1 to 6, and the effective dot matrix generating circuit 7 performs this.

The effective dot matrix generation circuit 7 has generation circuit units 7 to 76 for each gray level to generate effective dot matrices of floors A1 to A6, and outputs from terminals indicated by A to H and A to H in the figure. The signal is given to the output gate circuit GT. The output gate circuit GT has eight gate units GT-GT8 corresponding to the data signal Y-Y8, and each gate unit GT-GT8 receives the gradation output of the gradation data decoder 6 and the effective dot matrix generation circuit 7. The A-H terminal and the output signal from the A-H terminal (when "1" is a valid dot signal) are given.

Here, since the data is always zero at gradation 0, the output of gradation 0 from the gradation data decoder 6 is sent to the output gate circuit GT.
There is no human power required. Conversely, at gradation 7, the data is always '1'.
” Therefore, as explained above, the output of the gradation 7 of the gradation data decoder 6 is output from the output gate circuit GT without being ANDed with the output of the effective dot matrix generation circuit 7. .

On the other hand, the gradation 1 output from the gradation data decoder 6 is transmitted to each gate unit GT configuring the output gate circuit GT.
The output of gradation 2 is ANDed to the AND gate gtl of GT8.
The output of gradation 3 is output to gate g t 2 and gate g t
3, the output of gradation 6 is similarly inputted to the ANDage-gtB of each gate unit GT to GTa. Furthermore, the outputs A-H of the generation circuit unit 7 which generates the effective dot matrix of gradation 1 are assigned to the first . 4, 6, 3.5, 8.2° The output A-E of the generating circuit unit 72 which is input to each AND gate gt1 in the seventh order and generates an effective dot matrix of gradation 2 is A-GT, B-GT
, GT S C-GT % D-1375 GT, GT, E-GT, and GT6 in combination 2 8 4 are input to the respective AND gates gt2, and in the same manner, the effective dot matrix generation circuit 76 of gradation 6 is input.
The outputs A-H are input to the AND gates gtB of each gate unit GT-GT8 in the order of 1st, 4th, 6th, 3rd, 5th, 8th, 2.7th from the top. This allows the horizontal and vertical distribution of effective dots to be
It is determined as shown in FIG.

FIG. 5 shows the effective dot matrix generation circuit 7 shown in FIG.
The detailed configuration is shown.

As shown, this circuit includes a D-type flip-flop 71,
It has three OR gates 72 to 723 that input these 100 outputs, three shift registers 73 to 733 having input terminals IN and output terminals A to H, and inverters 74 to 743.

The features of this effective dot matrix generation circuit 7 are as follows:
The output terminal H of the shift register 73 is the OR gate 72,
The output terminal E of the shift register 73° is connected to the OR
The output terminal C of the shift register 733 is connected to the OR gate 723. Further, inverters 74 to 743 are provided on the output side of the shift registers 73 to 733, and a circuit for gray scale 1.6 and a circuit for gray scale 2 are provided.
, 5 and the circuit for gradation 3.4 are common. As a result, the shift register 73
Eight effective signals for gradation 1 are obtained from terminals A-H of 1, and 8 effective signals for gradation 1 are obtained from terminals A-H of gradation 1.
Eight useful signals are obtained for . Similarly, five valid signals for gray scale 2 are obtained from terminals A-E of shift register 732, three valid signals for gray scale 3 are obtained from terminals A-C of shift register 733, and inverter 74
, 743, an effective signal for gradation 5°4 is obtained.

As mentioned above, in the embodiment, a 640 dot x 200 dot liquid crystal panel is used, and the effective dot matrix is repeated 80 times in the horizontal direction. On the other hand, in the vertical direction, if the vertical size of the effective dot matrix is a multiple of 8.5.3, the effective dots will be fixed, so it must be repeated with a number other than the above multiples and larger than 200. It won't happen. That is, in the vertical direction, the horizontal scanning signal is 202.203, 206°209.2
It is necessary to output the vertical scanning signal when the signal is output a number of times such as 11.213. At this time, horizontal scanning of 201 or more is wasted, so it is better to make it as small as possible.

In the embodiment, when the horizontal scanning signal is output 209 times, that is, when the horizontal scanning signal X is output, the vertical scanning signal is outputted. At this time, to return to the initial pattern again, the lowest common multiple is 8X5X3.
It should take a frame, so it will take 120 frames. As a result, since conventionally the effective dot matrix was 8 dots x 8 dots at any gradation,
The number of frames that interfered was 1 in 120 frames.
As a result, the effect of gradation display has been greatly improved.

Next, the operation of the embodiment shown in FIGS.
This will be explained with reference to the drawings and FIG.

Figure 6 is a timing chart showing the operation.
-H, A-H are the output terminals of the generation circuit units 71 to 76 for generating an effective dot matrix in FIG.
They correspond to the output terminals of shift registers 73□-733 and the output terminals of inverters 741-743 in the figure. When the output of these terminals A to H and A to H is "1", it becomes a valid signal. Also, X-Xl in FIG. indicates a horizontal scanning signal. From this timing chart, it can be seen that after the shift registers 73 to 733 are reset, each time a horizontal scanning signal is applied to the terminal IN, the output of the valid signal shifts in the order of terminals A, B, C, and so on. .

FIG. 7 shows effective dots when the circuits shown in FIGS. 3 to 5 are operated with the signals shown in FIG. 6. FIG. At gradation 2, the same figure (c)
corresponds to gradation 3.

Further, circles in the figure indicate effective dots in the first frame, triangular marks indicate effective dots in the next frame, and cross marks indicate effective dots in the next frame.

First, as shown in FIG. 6, when the horizontal scanning signals X1 to X8 are sequentially output, the outputs A to H of the gradation 1 generation unit 7□ become "1" (valid signal) in that order. Here, the output A-H
are connected to the 1.4, 6.3, 5°, 8.2.7 of gate unit GT-GT8 as shown in Fig. 5, so as shown by the circles in Fig. 7 (a). , the effective dots are Y-1, 4, 6, 3, 5, 8, 2°7 in X-1 to X-8. Thereafter, similar operations are repeated, but as shown in FIG. 3(a), the output of the scanning electrode drive circuit 4 is up to 209 horizontal scanning signals x − Scanning electrodes 2, ~2
We only have the following. Therefore, the effective dot matrix of 8 dots x 8 dots at gradation 1 is repeated 26 times in one frame from the calculation formula 209-8 As shown, in the next frame, it becomes effective with a shift of one dot, as shown by the cross mark.

The above explanation relates to gradation 1 where the effective dot matrix is 8 dots x 8 dots, but in the case of gradation 2, the size of the effective dot matrix is 8 dots x 5 dots. Therefore, the effective dot matrix at this time is calculated from the calculation formula %, which is repeated 41 times in one frame, and in the next frame, as shown by the triangle mark in Fig. 7 (b), and the next frame is shown by the cross mark. It can be seen that the effect becomes effective with a shift of 4 dots. Furthermore, in the case of gradation 3, according to the calculation formula % formula %, it is repeated 69 times in one frame, and in the next frame, as shown by the triangle mark in Figure 7 (C), the side is shown by a cross mark. As can be seen, it becomes effective with a two-dot shift.

In this embodiment, as is clear from FIG. 7, the effective dots are distributed horizontally and vertically, some dot is always effective on each horizontal and vertical line, and no effective dot is visible in the same frame. are not adjacent to each other, and the effective dots in the next frame are also not adjacent to the previous frame. As a result, not only the stringing phenomenon became less noticeable, but also the interference was reduced, and the effect of gradation display was greatly improved.

FIG. 8 is another example showing the same effect as FIG. 7(a),
The outputs A to H of the shift registers 72□ to 723 in FIG. 5 are allocated in the order of horizontal dots 1.4, 7, 2.5°, 8.3.6.

In this case as well, the effective dots are not adjacent to each other in the same frame, nor are they adjacent to effective dots in the next frame.

In the above embodiment, the drive circuit is configured with positive logic, but the same effect can be obtained with negative logic.

〔Effect of the invention〕

As explained above in detail, in the present invention, the size of the effective dot matrix differs depending on the gradation, so there is a low possibility that effective dots in one frame and effective dots in the next frame will interfere with each other. Become.

Therefore, flow stripes are less likely to occur, making it possible to express an image that is easy to see.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an effective dot matrix according to the basic method of the present invention, FIG. 2 is an explanatory diagram of an effective dot matrix according to another example of the basic method of the present invention, and FIG. 3 is a configuration diagram of an LCD. Figure 4 is a block diagram of an element circuit constituting a signal electrode drive circuit, Figure 5 is a diagram of an effective dot matrix generation circuit, Figure 6 is a timing chart showing the operation, and Figure 7 is a diagram of effective dots in an effective dot matrix. FIG. 8 is a diagram illustrating another example of shifting of effective dots in an effective dot matrix, and FIG. 9 is a diagram illustrating an effective dot matrix according to a conventional method. 1...Display body part, 2-2...Horizontal scanning electrode,
I200 3-3...Signal electrode, 4...Scanning electrode drive circuit, l6405...Signal electrode drive circuit, 5, ~58o...Element circuit, 6...Gradation data decoder, 7... Effective dot matrix generation circuit, 7-76... Generation circuit unit, 71... D-type flip-flop, 721-7
23...OR gate, 73□~733...shift register, 741~743...inverter, GT1~G
T8...Gate unit.

Claims (1)

[Claims] 1. In controlling a display body made up of a large number of dots distributed in a matrix on a two-dimensional plane, by selectively lighting and non-lighting the large number of dots,
Let the dot be a valid dot that is effective for displaying the image,
In a method for controlling a multi-gradation display that displays the image in multiple gradations, when determining the distribution of effective dots on a frame-by-frame basis, the size of an effective dot matrix, which is the basis of the distribution of effective dots, is 1. A method for controlling a multi-gradation display, characterized in that at least one of the row direction and the column direction of a dot matrix is made different depending on the display gradation of the image. 2. The method of controlling a multi-gradation display according to claim 1, wherein the arrangement of the effective dots in the effective dot matrix is distributed in the row direction and the column direction in units of frames.