JPH1097218A - Display panel drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a moving picture pseudo contour by dividing fluctuation in a light emission time interval in to two groups for addressing and light emitting. SOLUTION: A display panel is constituted of a display panel 101, an address electrode drive electrode drive circuit 102, an address electrode 103, a display electrode drive circuit Y 104, display electrodes 105, 107 and a display electrode drive circuit X 106. A display is performed by writing on a display cell and hold the written data, and one frame period is time shared to plural sub-frames having weighting in a display time, and by deciding brightness and darkness in respective sub-frames based on the written data of respective display cells, gradation of a video is expressed. At this time, by driving so that one period consists of the sub-frame period performing the display by the writing and holding of the written data of display lines of a half of the display panel and the sub-frame period performing the display by writing and holding of the written data of the display lines of a remaining half, the display is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for driving a display panel having a memory function, and more particularly to a method of driving a display panel for performing high-quality multi-gradation display on a plasma display panel, so-called PDP or the like. It is about.

[0002]

2. Description of the Related Art A basic operation of a conventional AC type PDP for performing multi-gradation display will be described with reference to a sub-frame structure shown in FIG. A PDP is a display display that basically displays only binary values of dark and light. For multi-gradation display, one frame period is divided into sub-frames corresponding to the number of gradation bits, and gradation weights are assigned to each sub-frame. By making the light emission time proportional,
The gray scale is displayed by time integration.

FIG. 4 shows an example in which 8-bit, 0-255 gradations are constituted by 8 sub-frames. The address period is a period in which the binarized video data of dark and light is written into each cell line-sequentially, and is the same for each sub-frame period. Once written, the data retains its state due to the memory effect of the cell, and emits light during the next write sustain period, usually a period called a sustain period. By changing the sustain period in proportion to the gradation data, gradation display is performed.

[0004]

However, in such a gradation display method using sub-frames, even if a moving image is displayed or a still image is displayed, a dark line or a bright line appears at the boundary of the gradation when the line of sight moves. However, there was a problem of false contours of moving images. This generation mechanism will be described with reference to FIG. In FIG. 5, the horizontal axis is the time axis, and the vertical axis shows the light emission intensity of a certain display cell. Assuming that the luminance is 127 tones among 256 gradations, seven sub-frames are emitted from the LSB. In the next frame, when the gradation becomes 128 gradations, which is one gradation higher, the first LS
The seven subframes from B do not emit light, but emit only the last MSB, eight subframes. Then 127 → 128
In this case, since the light does not emit for a period close to one frame period, the eyes feel slightly dark, and this is recognized as a dark line. Conversely, with a change from 128 to 127, the light emission interval is narrowed and felt as a bright line. In any case, it looks like linear noise in a smooth portion, and significantly impairs image quality. This phenomenon is most severe under the above-mentioned conditions associated with turning on and off the MSB, but occurs to a lesser extent even when half of the bits change from 63 to 64 or 191 to 192.

[0005]

According to the present invention, a display is performed on a selected display line by writing to a display cell using a memory function and maintaining the write data, and one frame period is assigned to a display time. A display panel that expresses a gray level of an image by time-sharing into a plurality of sub-frames each having a weight and determining light and dark in each sub-frame based on the write data of each of the display cells; The display is driven by driving the display line to be composed of a sub-frame period in which the display is performed by writing the display line and maintaining the write data and a sub-frame period in which the display of the remaining half of the display line is maintained by maintaining the write data. By doing so, an attempt is made to solve the pseudo contour of the moving image.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIG. FIG. 1 shows a subframe structure within one frame period. The present invention combines address and sustain into two groups, eg, A group and B group.
The feature is that it is performed in groups. In the example of FIG. 1, light is emitted in order from the LSB of the A group to the MSB. Then, group B sets MS as the last MSB
Light is emitted from B to LSB. Next, an actual light emission state is shown with FIG.

FIG. 2 shows the state of light emission when the false contour of the moving image changes from 127 to 128, which is the most noticeable in the 0-255 gradation. Here, assuming that the ratio between the address period and the sustain period is a general address of 0.8 and the sustain is 0.2, a non-light emitting period is calculated. First, in the group A, the gradation 127 is the first half of the frame, and the gradation 128
Indicates light emission at the center of the frame. At intervals of the non-light emitting period, about 0.6 → about 1.1 → about 0.9 for each frame period.
Changes. In the B group, the light emission in the latter half of the frame changes to the light emission in the central portion, and the variation in the non-light emission period is as small as about 0.65 → about 0.5 → about 0.9. Conventionally, since the change is about 0.3 → about 1.1 → about 0.9, the moving image pseudo contour is greatly reduced compared to the related art.

[0008] Although not shown, even in the case of a change from 128 to 127, about 0.8 → about 0.4 →
About 0.6, about 0.8 for group B → about 1.0 → about 0.6
, Which is significantly reduced as compared with the related art of about 0.7 → about 0.1 → about 1.

As described above, even when the A group and the B group are used alone, a great effect is obtained. This indicates that, for example, the A group may be set to the upper half and the B group may be set to the lower half. However, there may be a case where the boundary looks slightly linear noise. In order to reduce this phenomenon, as shown in the panel configuration diagram of FIG. Both the A group and the B group emit light in the same manner as in FIG. 2 but are adjacent to each other, and are averaged at a normal viewing distance, so that there is a greater effect of reducing a moving image pseudo contour.

FIG. 3 shows an example of a configuration diagram of the present invention, wherein 101 is a display panel, 102 is an address electrode drive circuit, and 103 is an address electrode. 104 is a display electrode drive circuit Y, 105 (a) is a display electrode of a display cell group of A group, for example, and 105 (b) is a display electrode of a display cell of B group. Normally, the display electrode drive circuit Y104 sequentially scans from top to bottom during the address period to write video data in the display cells. In this case, the first half first scans sequentially in the display electrode 105 (a), and the display is performed during that time. The electrode 105 (b) is supplied with a non-selected potential to which no video data is written. Then, during the address period of the common MSB, the display electrodes 105 (a) and 105 (b) are collectively scanned in order.

In the latter half, the display electrodes 10 of the B group are used.
5 (b), scanning is performed sequentially, and at the same time, the display electrode 105 is scanned.
(A) is a non-display potential. 106 (a) is a display electrode drive circuit X1, and the number of display electrodes (a) connected thereto is 10;
7A, which is a display electrode group of Group A. Similarly, 106 (b) is the display electrode drive circuit X2, and the display electrode (b) connected thereto is 107 (b), which is a group B of display electrodes. Here, since light emission periods are different, examples of different wirings and driving circuits are shown; however, this is not necessarily required depending on the display panel.

The reason is that if the display electrode drive circuit Y determines the light emitting and non-light emitting state irrespective of the potential of the address electrode, the display is performed normally. In terms of the discharge voltage margin, it is desirable to separate the display electrode drive circuits X1 and 106 (a) from the display electrode drive circuits X2 and 106 (b).

Further, the feature of the present invention is that the address period is not increased by the same amount as in the prior art, even though the address is divided into two groups and the addresses are finely equivalent to 15 sub-frames. It is characteristic.

However, the light emission period is 256/382 (1 + 2 + 4 +... +128+) from the conventional 256 gradation unit.
64+. . + 4 + 2 + 1), the luminance decreases at this rate. In the present invention, without weakening the effect of moving image false contour reduction, in order to prevent this brightness reduction even a little,
The MSB emission period is made common.

Although the present invention has been described as being divided into two groups, a larger group, for example, four groups may be used. The four groups have a subframe structure in which the two groups described so far are in the first half and the second half. In this case, the degree of moving image false contour reduction is even greater than in the two groups. However, although the address period is not increased, the luminance is reduced because the substantial light emission period is reduced (halved than two groups). The selection is based on the balance between the pseudo contour of the moving image and the luminance.

It is needless to say that the present invention can be applied to a display having a memory function and performing gradation display by a sub-frame configuration, for example, an EL display and a reflective display integrated with a semiconductor memory.

[0017]

As described above, according to the present invention, pseudo-contours of a moving image can be reduced by dividing the variation of the light emission time interval into two groups and emitting the address and the light. Then, by sharing the MSB of the video data, it is possible to reduce a decrease in luminance. Further, by arranging these two groups adjacent to each other, there is an effect of further reducing the moving image pseudo contour.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a subframe according to an embodiment of the present invention;

FIG. 2 is a diagram showing the operation of the present invention.

FIG. 3 is a configuration diagram of a display panel in one embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional subframe.

FIG. 5 is a diagram showing a pseudo contour of a moving image.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Display panel 102 Address electrode drive circuit 103 Address electrode 104 Display electrode drive circuit Y 105 (a) Display electrode of group A display cell group 105 (b) Display electrode of group B display cell 106 (a) Display electrode drive circuit X1 106 (b) Display electrode drive circuit X2 107 (a) Display electrode 107 (b) connected to display electrode drive circuit X1 Display electrode connected to display electrode drive circuit X2

Claims (4)

[Claims] 1. A plurality of light emitting and displaying devices are provided for a selected display line by writing to a display cell using a memory function and maintaining the write data, and one frame period is weighted for a display time. In a display panel that is time-divided into sub-frames and determines the brightness and darkness in each sub-frame based on the write data of each display cell to express the gradation of an image, the display panel is divided into display lines by n ( (n: integer) A method of driving a display panel, wherein video data over a plurality of subframes is temporally concentrated for each group, and writing and maintenance / light emission of the written data are performed. 2. The method according to claim 1, wherein n is 2. 3. An MSB of video data of a subframe of a group to be written first and a data retention period, and a MSB of video data of a subframe of a next group in a group adjacent to each other in time. The method according to claim 1, wherein the sustain period and the sustain period are common. 4. The display panel driving method according to claim 2, wherein a half display line to be written first and the remaining display lines are adjacent to each other.