JPH11231830A - Gradation display system of plasma display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gradation display system where a pseudo-animation outline can be dissolved. SOLUTION: A gradation is carried out so that the combination of sub-fields may be altered every frame to display one gradation, and the top and its lower bits (MSB, MSB-1) except the lowest bit (LSB) are severally divided into (2<n-1> -1)=3 and 1, (2<n-1> -1)=1 and 1 to form each sub-field in five sheets in all. A black circle in a table shows a picture element emission timing, for instance, in the case of the gradation 3, in an odd number frame, an emission is caused in time sub-fields of gradation LSB and MSB-1, and in an even number frame, the emission is caused in three sub-fields of the divided gradation MSB. The combination of sub-fields is varied every frame to cause the emission, and the emission timing of one picture element can be adjusted at random, and nonemission term during carrying therefore becomes various and a pseudo- animation outline can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for driving a plasma display device.

[0002]

2. Description of the Related Art In a plasma display device, for gradation display, one or more subfields in which the luminance weighting (number of pixel emission times) is changed by a binary code are used.
Make up the frame. FIG. 1 shows this briefly.

The example shown in FIG. 1 is a 4-bit gradation (= 16 gradations in total).
In the example, one frame is composed of four subfields in which the weighting of the light emission period (sustain discharge) after addressing is four types of 1, 2, 4, and 8. FIG. 2 illustrates a light emission sequence of one pixel in such a subfield type gradation display method.

In the example shown in the figure, the gradation in the previous frame is 7,
The figure shows a case where the gradation rises to the highest digit of 8 in the succeeding current frame. In this case, gradation 7 is displayed by emitting light with weights 1, 2, and 4 in the previous frame,
In the current frame, the gray scale 8 is displayed by emitting light with the weight 8. At that time, after the light is emitted with the weight of 4 in the previous frame, the light is not emitted with the weight of 8, and in the current frame, the light is not emitted with the weight of 1 to 4 and then emitted with the weight of 8. In other words, during the subfields of weight 8 of the previous frame and the subfields of weights 1 to 4 of the current frame, the pixel remains unlit.

[0005]

As described above, in the sequence in which the subfields are simply arranged in ascending order of the weights, a long non-light emitting period (in the case of descending order, the light emitting period is reversed) when the gradation goes up. , And a non-light emitting period equivalent to one frame may occur particularly when the carry to the highest digit is performed. A false contour of a moving image in which a non-light emission pattern affects perceived luminance has been raised as a problem to be solved.

[0006]

In order to prevent a false contour of a moving image, it is conceivable to employ a system in which the non-light emitting period is made non-uniform and a non-light emitting pattern is erased. For this purpose, a method of changing the arrangement of subfields for each frame, that is, a method of changing the arrangement of weighted ascending order for odd frames and weighted descending order for even frames is possible. However, a satisfactory effect cannot be obtained even with this, so in the present invention, furthermore, in the present invention, weighting is coded so as to obtain a plurality of combinations of subfields having a predetermined weight, and one gradation is expressed. The combination of subfields can be changed in a plurality of frames.

That is, according to the present invention, in a gray scale display method of a plasma display apparatus which forms one frame from a plurality of subfields having different luminance weightings and performs multi-gray scale display, a subfield for one gray scale display is provided. , Weights are coded so that two or more combinations of the subfields can be made, and the combination of subfields can be changed for each frame. As a specific first coding method, each weight of the n-bit gradation is expressed by (2) except for the least significant bit (representing weight 1).
It is possible to adopt a method of forming one frame from 2n-1 subfields by dividing into ^n-1 -1) and 1. As a second coding method, a method can be used in which one frame is composed of (n + 1) subfields obtained by adding subfields having the same weight as the least significant bit of the n-bit gradation. As a third coding method, the most significant bit of the n-bit gradation is replaced with the least significant bit, and the weight of the most significant bit is divided into (2 ^n-1 -1) and one. Thus, a method of forming one frame from (n + 1) subfields can be adopted.

According to such a method, weighting is coded so that a combination of two or more types of subfields can be considered for one gradation display, and the combination of subfields is changed between an odd frame and an even frame. The emission timing of one pixel, which was conventionally uniform for each gradation, can be freely and non-uniformly adjusted, and the non-emission period can be varied to prevent false contours of a moving image.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a gradation display method according to the first method, where n = 3 bit gradation (8 gradations in total).
Are shown in the table. In this example, 2n-1 = 5 subfields are used, and the combination of the subfields is changed between an odd frame and an even frame displaying one gradation.

The weight is determined by the least significant bit (LSB).
The most significant bits and the bits below (MSB, MSB-
1) is divided into (2 ^n-1 -1) and 1. That is, the weight is LSB because it is a 3-bit gradation.
= 1, MSB-1 = 2, MSB = 4, of which MSB-1 is (2 ^n-1 -1) = 1 and 1, and MSB is (2 ^{n -1).}
-1) = 3 and 1 Each of these forms a subfield, so that the total number of subfields is five.

At the timing when the black circle in the table causes the pixel to emit light, for example, if the gradation is 1, in the odd-numbered frame, the light is emitted in the subfield of the weighted LSB.
In the even-numbered frame, light is emitted in one of the divided subfields of the weight MSB-1. If the tone is 3,
In the odd-numbered frames, light is emitted in all the subfields of the weighted LSB and MSB-1, and in the even-numbered frames, light is emitted in the three subfields divided by the weighted MSB. As described above, the light emission timing of one pixel is randomly adjusted by changing the combination of subfields for each frame to emit light, so that the non-emission period at the time of carry is varied, thereby preventing a false contour of a moving image.

FIG. 4 shows an example of the same three-bit gradation in the gradation display method according to the second method. In this example, n + 1 = 4 subfields are used.

The weighting is performed using the conventional LSB, MS
B-1, in addition to MSB, LS with the same weight as LSB
B-1. Therefore, the total number of subfields is four. In this case, as in the first method, if the gradation is 1, the weight L is applied to the odd frame.
Light is emitted in the SB subfield, and in even frames, light is emitted in the weighted LSB-1 subfield. In the case of gradation 3, light is emitted in the weighted LSB and MSB-1 subfields in the odd frame, and light is emitted in the weighted LSB-1 and MSB-1 subfields in the even frame.

FIG. 5 shows an example of the same three-bit gradation in the gradation display method according to the third method. Also in this example, n + 1 = 4 subfields are used.

The weighting is such that the MSB and MSB-1 are swapped, and (2 ^n-1-
1) = 3 and 1 Therefore, the total number of subfields is four. In this example, the subfield combination of the odd-numbered frame and the even-numbered frame is changed at the time of carry to the most significant digit, which is the most problematic. That is, the weighting LS
Light is emitted in the B and MSB-1 subfields, and in even frames, light is emitted in the three divided subfields of the weighted MSB. In the odd-numbered frame of gradation 4, light is emitted in both subfields 3 and 1 of the weighted MSB.
Light is emitted in one of the divided SB and MSB, and in the subfield of MSB-1.

[0016]

According to the present invention, the weighting is coded so that a plurality of combinations of subfields can be made in one gradation, so that the light emission timing of the pixels is randomly adjusted for each frame to reduce the non-light emission period. This makes it possible to make the image non-uniform, thereby eliminating the false contour of the moving image and improving the image quality of the plasma display device.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a subfield showing a conventional gradation display method.

FIG. 2 is an explanatory diagram showing a light emission sequence of one pixel according to a conventional gradation display method.

FIG. 3 is an explanatory diagram of a weighting coding table and subfields showing a first example of a gradation display method according to the present invention.

FIG. 4 is an explanatory diagram of a weighting coding table and subfields showing a second example of the gradation display method according to the present invention.

FIG. 5 is an explanatory diagram of a weighting coding table and subfields showing a third example of the gradation display method according to the present invention.

Claims (4)

[Claims] 1. A gray scale display method for a plasma display apparatus which forms one frame from a plurality of subfields having different luminance weightings and performs multi-gray scale display, wherein the combination of subfields for display of one gray scale is 2
A gradation display method characterized in that weights are coded so that more than one type can be performed, and the combination of subfields can be changed for each frame. 2. By dividing each weight of an n-bit gradation into (2 ⁿ -1 -1) and 1 except for the least significant bit,
2. The gradation display method according to claim 1, wherein one frame is composed of n-1 subfields. 3. The gradation display method according to claim 1, wherein one frame is composed of (n + 1) subfields to which a subfield having the same weight as the least significant bit of the n-bit gradation is added. 4. An n + 1 by replacing the most significant bit of the n-bit gradation weighting with the lower-order bit and dividing the weight of the most significant bit into (2 ^n-1 -1) and 1 2. The gradation display method according to claim 1, wherein one frame is composed of one subfield.