JPH09160523A - Driving method for display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a grid pattern inconspicuous on display screen when the screen moves at a regular speed (e.g. moves by an even number of dots per frame). SOLUTION: At least two of plural sub-frames constituting one frame are set to be weighted equally, and a dot pattern 1 (indicated by the marks ○) in which one of the two sub-frames is turned on while the other is not and a dot pattern 2 (indicated by the marks ) in which the former is not turned on while the latter is turned on are set. When a screen 20 is displayed on which a plurality of dots displayed by the equally weighted 'on' and 'off' sub-frames are present, six kinds of unit screen patterns 1 to 6 produced by the combination of the dot patterns 1, 2, with M lines × N dots (M×N>=3) as a unit screen UG, are displayed as they are switched from one to another for every frame. When a screen that moves at a regular speed is displayed, the regularity at which the dot patterns 1, 2 appear is dispersed to make a grid pattern unlikely to appear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention configures one frame (or one field) with a plurality of subframes (or subfields), weights the brightness of each subframe, and outputs a halftone image (for example, 256 gradations). The present invention relates to a driving method of a display device that displays an image).

[0002]

2. Description of the Related Art Recently, as a thin and lightweight display device, P
Attention has been paid to DP (plasma display panel). The driving method of this PDP is completely different from the conventional CRT driving method, and is a direct driving method using digitized video input signals. Therefore, the luminance gradation emitted from the panel surface is determined by the number of bits of the signal to be handled.

[0003] PDPs are AC type and D type having different basic characteristics.
It is divided into two types of C type. In the AC type PDP, sufficient characteristics have been obtained with respect to luminance and life, but there has been only a report of a gradation level of up to 64 gradation display at the prototype level. However, the address / display separation type driving method (A
DS subframe method) has been proposed. The driving sequence and driving waveform of the PDP used in this method are shown in FIG.
It is shown in (a) and (b).

In FIG. 3A, for example, in the case of 256 gradations, one frame has a relative luminance ratio of 1, 2, 4,
8, 16, 32, 64 and 128 subframes S
The display is composed of F1 to SF8, and the display of 256 gradations is performed by the combination of the luminances of 8 screens. In FIG. 3B, each sub-frame includes an address period in which data for one refreshed screen is written and a sustain period for determining a luminance level of the sub-frame. In the address period, first, wall charges are initially formed on each pixel at the same time for the entire screen, and then a sustain pulse is applied to the entire screen to perform display. The brightness of the sub-frame is proportional to the number of sustain pulses and is set to a predetermined brightness. In this way, 256 gradation display is realized.

[0005]

However, in the conventional address / display separation type driving method (ADS subframe method), since the subframe is configured as shown in FIG. There is a problem that a non-display period (a period during which no display is performed) may become longer during display, and this may be displayed on the screen as a false contour.

In order to solve the above-mentioned problem, the present applicant sets the weights of at least two subframes among a plurality of subframes forming one frame to be equal, and one of the subframes having the same weight is turned on. Then, a driving method has been proposed in which a dot screen in which the other is not illuminated is displayed by switching the illuminated subframes and the unilluminated subframes of the same weight for each dot, each line, or each dot and each line.

For example, as shown in FIG. 4, one frame is composed of six sub-frames SF1 to SF6, the brightness levels of SF1 and SF6 are both set to 4 and the brightness levels of SF2 and SF5 are both set. When the screen 10 in which the brightness levels of the dots are 4 is set to be equal to 8 and the screen 10 is displayed, as shown in FIG. 5, display of a dot pattern 1 in which SF1 is a lighting subframe and SF6 is a non-lighting subframe (Displayed with a circle) and display of dot pattern 2 in which SF1 is a non-lighted subframe and SF6 is a lighted subframe (displayed with a ● in the figure) are switched and displayed for each dot, line and frame. It was

However, when the screen 10 is regularly moved in the direction shown by the arrow in FIG. 5 (leftward in the horizontal direction), a grid pattern may appear on the screen. For example, as shown in FIGS. 6A, 6B, and 6C, when the screen 10 moves in the direction of the arrow at a rate of 1 dot per frame, no lattice pattern appears on the screen (other than 1 dot). The same applies to the case of moving an odd number of dots), but as shown in FIGS. 7A, 7B, and 7C, when the screen 10 is moving in the direction of the arrow at a rate of 2 dots per frame, There was a problem that a grid pattern appeared on top (the same was true when moving even dots other than 2 dots). For example, in the frame control and dither method, since the levels displayed for each dot and each line are switched to perform halftone display,
There is a problem that a houndstooth check pattern may be conspicuous in an image that moves at a regular speed.

That is, when moving in the arrow direction at a rate of 1 dot per frame as shown in FIGS. 6A, 6B, and 6C, the subframes SF1 to SF6 of continuous frames are turned on ( The display with hatching) and the non-lighting (display without hatching) are as shown in FIG. 8, and the non-lighting period (non-lighting period) Toff is approximately 1.
The grid pattern does not appear because it appears evenly for each frame. However, when moving in the arrow direction at a rate of 2 dots per frame as shown in FIGS. 7A, 7B, and 7C, the subframes SF1 to SF1
The lighting and non-lighting of SF6 are as shown in FIG. 9, and the non-lighting period Toff is 1 frame or more (approximately 2 frames) and the brightness is higher than the brightness level of the video signal, so that a grid pattern appears. I will end up.

The present invention has been made in view of the above-mentioned problems, and displays in a case where the display screen is moved at a regular speed such as an odd dot or even dot movement per frame. An object of the present invention is to provide a driving method of a display device in which a grid pattern (for example, a houndstooth check pattern) is inconspicuous on a screen.

[0011]

According to a first aspect of the present invention, there is provided a driving method of a display device, wherein one frame is composed of a plurality of sub-frames, the luminance of each sub-frame is weighted, and a halftone image is displayed. Setting at least two subframes of the plurality of subframes to have equal weights,
Set a dot pattern in which one of the subframes with the same weight is lit and the other is not lit, and a dot pattern in which one is unlit and the other is lit and are set. When displaying a screen with multiple dots displayed in the frame,
Switching a plurality of types of unit screen patterns created by a combination of a plurality of types of set dot patterns for each frame in units of M lines × N dots (M and N are positive integers that satisfy M × N ≧ 3) It is characterized by being displayed.

When displaying a screen in which a plurality of dots are displayed in the lit sub-frame and the non-lit sub-frame having the same weighting, a plurality of types of set dot patterns in which the lit sub-frame and the non-lit sub-frame having the same weight are exchanged Since a plurality of types of unit screen patterns created by the above are switched and displayed for each frame in units of M lines × N dots, it is possible to move at a regular speed such as moving an odd dot or an even dot per frame. When a halftone image of the displayed image is displayed, the regularity is dispersed and the grid pattern is less likely to appear, compared to the previously proposed in which the illuminated subframes and the unilluminated subframes having the same weighting in one dot are replaced.

In order to simplify the driving method, the invention of claim 2 sets M = 2 and N = 2 in the invention of claim 1, and sets a plurality of types of set dot patterns in two subframes of equal weighting. 6 types of unit screen patterns created by arraying 2 types of set dot patterns in a 2 line x 2 dot unit screen with 2 types of set dot patterns in which lighting and non-lighting are switched And

According to a third aspect of the present invention, in a method of driving a display device in which one frame is composed of a plurality of sub-frames, the luminance of each sub-frame is weighted to display a halftone image, and among the plurality of sub-frames, Of at least two sub-frames are set equal, and a dot screen in which one of the sub-frames having the same weight is lit and the other is not lit Also, it is characterized in that the frames are randomly switched and displayed.

When displaying a halftone image of a screen moving at a regular speed, a dot screen in which one of the subframes of equal weight is lit and the other is unlit is dot-by-dot and frame-by-frame. In addition, since the lit sub-frames and the non-lit sub-frames having the same weight are randomly switched and displayed, the switching is not regular and the grid pattern is less likely to appear.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the illuminated sub-frames and the non-illuminated sub-frames having the same weight are randomly replaced for each dot and each frame, but are randomly replaced for each line and each frame. It is characterized by being displayed as. In this case, the dot screen in which one of the equally weighted subframes is lit and the other is unlit is displayed by randomly switching the equally weighted lit and unlit subframes for each line and frame. Since it has been replaced, it will be replaced without regularity and the grid pattern will not appear easily.

According to a fifth aspect of the invention, in the third aspect of the invention, instead of randomly switching the illuminated subframes and the unilluminated subframes having the same weight for each dot and each frame, each dot, each line and each frame are replaced. It is characterized in that the images are displayed by randomly replacing them. In this case, the screen of dots in which one of the subframes having the same weight is lit and the other is not lit is displayed on a dot-by-dot, line-by-line, and frame-by-frame basis by randomly illuminating subframes and non-illuminating subframes having the same weight. Since they are swapped, they have no regularity and the grid pattern is unlikely to appear.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the invention according to claims 1 and 2. For convenience of description, one frame includes six subframes SF1 to SF1 as shown in FIG.
The screen of FIG. 7 (a), which is composed of F6, has the same brightness level of SF1 and SF6 set to 4, the same brightness level of SF2 and SF5 set to 8, and a brightness level of 4 for each dot. Similar to the cases of (b) and (c), the case of moving in the horizontal direction (left direction) at a rate of 2 dots per frame will be described.

(1) When the unit screen UG is M = 2 and N = 2, that is, 2 lines × 2 dots, six types of unit screen patterns as shown in FIG. Set 1 to 6. In this figure, the dots marked with circles indicate that SF1 in FIG.
Represents a dot pattern 1 in which is a non-lighting sub-frame.
The dot pattern 2 in which F6 is the lighting sub-frame is shown, and the □ mark shows the dots not of interest.

(2) The display screen 20 of n + 0 frame is
As shown in FIG. 1B, if the unit screen UG is represented by a unit screen pattern 2, the display screen 20 of the n + 1 frame has the unit screen UG as shown in FIG. Is displayed by the unit screen pattern 3, and the display screen 20 of the n + 2 frame is the unit screen UG represented by the unit screen pattern 4 as shown in FIG. Hereinafter, n + 3, n + 4, n + 5, n
Similarly, the display screen 20 of the +6, ... Frame is the unit screen UG represented by the unit screen patterns 5, 6, 1, 2 ,.

For this reason, a screen in which the unit screen UG is represented by the same unit screen pattern is displayed once every six frames. Therefore, as shown in FIG. 6 or FIG. 7, a lattice pattern appears as compared with the already proposed example in which the unit screen UG is represented by the same unit screen pattern once in one frame or once in two frames. It gets harder.

In the above embodiment, the case where the display screen 20 moves in the horizontal direction (left direction) at a rate of 2 dots per frame has been described, but the present invention is not limited to this, and 1 dot per frame. It can also be used when moving at a rate of, or when moving at a rate of a plurality of dots other than 2 dots in one frame, and the moving direction is horizontal direction (right direction), vertical direction (upward or downward direction). It can also be used in the case of an oblique direction.

In the embodiment described above, M and N of the unit screen UG of M lines × N dots are M = 2, N = 2 (that is, the unit screen UG is 2 lines × 2 dots), and the lighting subframes have the same weighting. The case has been described where there are two types of set dot patterns and six types of unit screen patterns in which the non-lighted subframes are replaced, but the present invention is not limited to this, and M and N of the unit screen UG are M × N ≧ It can be used when a positive integer that satisfies 3 is set, a plurality of types of dot patterns are set, and three or more types of unit screen patterns are set. At this time, as the number of types of unit screen patterns is set, the rate of appearance of the same unit screen pattern can be reduced, and the lattice pattern is less likely to appear.

Consider, for example, the case where the screen of the brightness level 12 of each dot is moving in a predetermined direction at a regular speed. SF1 and SF2 in FIG. Dot pattern 1 as a frame, sub-frames for lighting SF1 and SF5, S
Dot pattern 2 in which F2 and SF6 are unlit subframes, dot pattern 3 in which SF2 and SF6 are unlit subframes, and SF1 and SF5 are unlit subframes
, SF5 and SF6 are lighting subframes, SF1 and SF
4 with dot pattern 4 where 2 is a non-lighting subframe
It is possible to set 24 types of unit screen patterns even if M = 2 and N = 2 by setting types of dot patterns.

FIG. 2 shows an embodiment of an apparatus for carrying out the invention according to claims 3, 4 and 5, in which reference numeral 30 is a halftone image of a video signal inputted to an input terminal 32. Is a halftone processing circuit that outputs a signal for
The halftone processing circuit 30 configures one frame screen of an input video signal by a plurality of sub-frame screens, weights the brightness of each sub-frame screen, and at least 2
It is configured to output signals with equal weighting of the two sub-frame screens. A random pulse generation circuit 34 randomly (arbitrarily) outputs a pulse of level 1 (or H) and a pulse of level 0 (or L).

Reference numeral 36 denotes a sub-frame replacement circuit. This sub-frame replacement circuit 36 displays one of the sub-frames having the same weight in the signal output from the halftone processing circuit 30 while the other is not lit. When there is a signal corresponding to a dot screen, a pulse output from the random pulse generation circuit 34 is used as a switching signal, and a lighting subframe and a non-lighting subframe are dot by dot, frame by frame, line by line and frame by frame. Alternatively, it is configured such that each dot, each line, and each frame are switched and output to the output terminal 38.

For example, the sub-frame switching circuit 36 is configured to switch the lighting sub-frames and the non-lighting sub-frames for each dot, each line and each frame and output the same, and a screen in which the brightness level of each dot is 4 is displayed on the PDP. Considering the case of displaying, the screen displayed by the signal output from the halftone processing circuit 30 and switched by the subframe switching circuit 36 for the illuminated subframe and the unilluminated subframe for each dot, each line and each frame is As shown in FIG. 5, there is no regularity such that the dot pattern 1 of the mark ◯ and the dot pattern 2 of the mark  are switched for each dot and each line, and the dot pattern 1 of the mark ◯ and the dot pattern 2 of the mark  And are randomly (arbitrarily) switched per dot, per line, and per frame. Therefore, when a screen with a brightness level of 4 moves in a predetermined direction at a regular speed, the dot pattern 1 marked with a circle and the dot pattern 2 marked with a circle have no regularity on the screen, and the grid pattern disappears. The pattern becomes inconspicuous.

In the above embodiment, one frame is composed of six subframes SF1 to SF6, and one of the subframes SF1 to SF6 is used.
1 and SF6, and the weights of SF2 and SF5 are set to be equal. However, the present invention is not limited to this. One frame is divided into a plurality of subframes SF1 to SFn.
(For example, n is 8), and can be used for at least two subframes (for example, SF1 and SF8) in which the luminance weighting is set equal.

In the above-described embodiment, the case where the display panel is a PDP has been described, but the present invention is not limited to this, and can be used when the display panel is an LCDP (liquid crystal display panel).

[0030]

According to the invention of claim 1, at least two weights of a plurality of sub-frames constituting one frame are set to be equal, and the dots displayed in the lit sub-frames and the non-lit sub-frames having the same weighting are set. When displaying a plurality of existing screens, a plurality of types of unit screen patterns created by a plurality of types of set dot patterns in which the lit sub-frames and the non-lit sub-frames having the same weight are exchanged are set in units of M lines × N dots. Since it is switched and displayed for each frame, when displaying a halftone image of an image moving at a regular speed, 1
The regularity is dispersed and the grid pattern becomes less conspicuous compared to the existing proposal in which the lighting subframes and the non-lighting subframes having the same weighting are replaced in units of dots. For example,
The houndstooth check pattern becomes inconspicuous when displaying an image that moves at a regular speed using frame control or dithering.

According to a second aspect of the present invention, in the first aspect of the present invention, M = 2 and N = 2, the plural kinds of setting dot patterns are two kinds of setting dot patterns, and the plural kinds of unit screen patterns are six kinds. Since the unit screen pattern of
The driving method can be simplified.

According to the invention of claim 3, 4 or 5, at least two sub-frames among the plurality of sub-frames are set to have equal weights, and one of the sub-frames having the same weight is lit and the other is lit. The screen of dots is displayed by switching the illuminated sub-frames and the non-illuminated sub-frames having the same weight for each dot and each frame, for each line and each frame, or for each dot, each line and each frame at random. .

Therefore, when a halftone image of an image moving at a regular speed is displayed, a dot screen in which one of the subframes having the same weight is lit and the other is unlit is displayed for each dot. Also, the lighting sub-frames and the non-lighting sub-frames having the same weighting are randomly replaced for each frame, for each line and each frame, or for each dot, each line, and each frame, resulting in a non-regular replacement so that a grid pattern appears. Hateful. For example, when an image moving at a regular speed is displayed by a frame control or a dither method, irregular levels are replaced for the images, and the houndstooth check pattern becomes inconspicuous.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a method of driving a display device according to the present invention, in which (a) is an explanatory diagram of six types of unit screen patterns when M = 2 and N = 2; ~
(D) is an explanatory view when the display screen (display image) is moving in the horizontal direction (left direction) at a rate of 2 dots per frame, and (b) is a unit screen UG and a unit screen pattern 2
N + 0 frame screen displayed in, (c) is unit screen U
FIG. 9 is an explanatory diagram of an n + 1 frame screen displaying G in a unit screen pattern 3, and (d) is an n + 2 frame screen displaying a unit screen UG in a unit screen pattern 4.

FIG. 2 is a block diagram of an apparatus for implementing another example embodiment of the invention.

FIG. 3 is a driving sequence (a) in 256 gradation display.
3A and 3B are drive waveform diagrams.

FIG. 4 shows one frame including six subframes SF1 to SF.
6 of which SF1 and SF6, SF2 and SF
This is a drive sequence in 28 gradation display in which the respective weightings of luminance 5 are set equal.

5 is an explanatory diagram of a state in which a moving screen (moving image) of luminance level 4 is displayed by the configuration of subframes SF1 to SF6 in FIG.

6A and 6B are explanatory views showing a state where the screen of FIG. 5 is moving in a direction of an arrow (leftward in the horizontal direction) at a rate of 1 dot per frame, where (a) is a screen of n + 0 frame and (b) is a screen.
Is an explanatory diagram of an n + 1 frame screen, and (c) is an explanatory diagram of an n + 2 frame screen.

7A and 7B are explanatory diagrams showing a state where the screen of FIG. 5 is moving in a direction of an arrow (horizontal leftward direction) at a rate of 2 dots per frame, where (a) is a screen of n + 0 frame, and (b) is a screen.
Is an explanatory diagram of an n + 1 frame screen, and (c) is an explanatory diagram of an n + 2 frame screen.

8 is a drive sequence for dots at fixed positions on the display panel displaying the moving screen of FIG.

9 is a drive sequence for dots at fixed positions on the display panel displaying the moving screen of FIG. 7. FIG.

[Explanation of symbols]

10, 20 ... Screen, 30 ... Halftone processing circuit, 32 ...
Input terminal, 34 ... Random pulse generation circuit, 36 ... Subframe replacement circuit, 38 ... Output terminal, M ... Number of lines of unit screen, N ... Number of dots of unit screen, SF1 to SF
6 ... Subframes constituting one frame (FIG. 4), To
ff ... Non-lighting period (non-lighting period), UG ... Unit screen.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Onodera 1116 Suenaga, Takatsu-ku, Kawasaki-shi, Kanagawa Within Fujitsu General Co., Ltd. 72) Inventor Seiji Matsunaga, 1116 Suenaga, Takatsu-ku, Kawasaki-shi, Kanagawa, within Fujitsu General Co., Ltd. (72) Toru Aida, 1116 Suenaga, Takatsu-ku, Kawasaki, Kanagawa, within Fujitsu General Co., Ltd.

Claims (5)

[Claims] 1. A method of driving a display device, wherein one frame is composed of a plurality of sub-frames, the luminance of each sub-frame is weighted to display a halftone image, and at least two of the plurality of sub-frames are selected. Subframe weights are set equally, and a dot pattern in which one of the subframes with the same weight is displayed with one lighted and the other not lighted and the dot pattern with one lighted and the other lighted are set and weighted. Units of M lines × N dots (M and N are positive integers satisfying M × N ≧ 3) when displaying a screen in which a plurality of dots are displayed in the same lighting sub-frame and non-lighting sub-frame As a feature, a plurality of types of unit screen patterns created by combining a plurality of types of set dot patterns are switched and displayed for each frame. Method for driving display device. 2. M = 2 and N = 2, and the plural kinds of setting dot patterns are composed of two kinds of setting dot patterns in which lighting and non-lighting of two subframes having the same weight are interchanged, and plural kinds of unit screens are set. 2. The method of driving a display device according to claim 1, wherein the pattern comprises 6 types of unit screen patterns created by the array of the 2 types of set dot patterns in the 2 lines × 2 dots unit screen. 3. A method of driving a display device, wherein one frame is composed of a plurality of sub-frames, the luminance of each sub-frame is weighted to display a halftone image, and at least two of the plurality of sub-frames are selected. Set the weighting of the subframes equally, and display a screen of dots in which one of the subframes with the same weight is lit and the other is not lit. A method for driving a display device, wherein the display device is replaced at random for display. 4. A method of driving a display device, wherein one frame is composed of a plurality of sub-frames, the luminance of each sub-frame is weighted to display a halftone image, and at least two of the plurality of sub-frames are selected. Set the weights of the subframes equally, and display a dot screen in which one of the subframes with the same weight is lit and the other is not lit. A method for driving a display device, wherein the display device is replaced at random for display. 5. A method of driving a display device, wherein one frame is composed of a plurality of sub-frames, and the luminance of each sub-frame is weighted to display a halftone image. At least two of the plurality of sub-frames are provided. Set the weights of the subframes equally, and display a screen of dots in which one of the subframes with the same weight is lit and the other is not lit. A method of driving a display device, wherein the display is performed by randomly switching each frame.