JP2005024608A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a smooth gray scale characteristic by obtaining the balance of the light emission luminance of each gray scale of a display device such as a plasma display panel (PDP). <P>SOLUTION: The display device which has the PDP having a plurality of display cells, constitutes one field by a plurality of sub-field, performs weighting of luminance by the number of light emission of each sub-field and performs gray-scale display by combinations of the presence or absence of the light emission in each sub-field, is provided. The device is provided with a plurality of driving modes varying in the total number of weighting of the one field and is so constituted that the driving modes can be switched. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device such as a plasma display that divides one field into a plurality of subfields and performs gradation display by a combination of the presence or absence of light emission in the subfields.
[0002]
[Prior art]
In recent years, various display devices have been put to practical use, but plasma displays are attracting attention as display panels with excellent visibility (thin display devices), and higher definition, larger screens, and higher gradations have been promoted. ing.
[0003]
This plasma display uses a subfield driving method for gradation expression. For example, when it is configured with 8 subfields, weights are set to 1, 2, 4, 8, 16, 32, 64, and 128. It is configured, and a gradation of 0 to 255 is expressed by the combination. In general, the number of subfields is increased in order to reduce moving image pseudo contours. For example, in a configuration with 9 subfields, 1, 2, 3, 6, 11, 20, 38, 64 are used. , 110 are weighted, and gradations are expressed by combinations thereof. Furthermore, in order to increase the emission luminance, each subfield is multiplied by a uniform multiple, for example, four times the number of pulses 4, 8, 12, 24, 44, 80, 152, 256, 440, and this subfield is emitted. The gradation is expressed by controlling the number of times of light emission of each pixel in combination (see Patent Document 1).
[0004]
However, in such a plasma display, since it is necessary to perform sub-field driving and express gradation in one field time, the driving time is limited. For example, in order to increase the luminance, it is necessary to increase the number of times of light emission, so that the sustain light emission time becomes longer, and in order to improve the video performance, it is advantageous to increase the number of subfields and the number of subfields has increased. Minutes, address time increases. In order to improve the gradation performance, it is necessary to increase the total number of weights. However, if the total number of weights is increased with the same number of subfields, the difference in the weights of adjacent subfields increases.
[0005]
Regarding the relationship between the weighting of each subfield and the generation of the moving image pseudo contour, as shown in Patent Document 2, it is advantageous for reducing the moving image pseudo contour that the difference between adjacent sub fields is smaller. In other words, in order to increase the gradation, it has been necessary to take measures such as sacrificing the moving image performance or lowering the luminance.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 08-146914 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-40981
[Problems to be solved by the invention]
An object of the present invention is to solve such problems, to balance the light emission luminance of each gradation, and to realize smooth gradation.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention includes a display panel having a plurality of display cells, one field is composed of a plurality of subfields, and luminance is weighted according to the number of times of light emission of each subfield. A display device that performs gradation display by combining the presence or absence of light emission in a field, and is provided with a plurality of drive modes having different total weights for one field, and the drive modes can be switched.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
That is, the invention according to claim 1 of the present invention includes a display panel having a plurality of display cells, one field is constituted by a plurality of subfields, and luminance is weighted by the number of times of light emission of each subfield, A display device that performs gradation display by a combination of the presence or absence of light emission in each subfield, and is provided with a plurality of drive modes having different total weights for one field, and the drive modes can be switched.
[0010]
According to a second aspect of the present invention, in the first aspect, the drive mode includes patterns having different numbers of subfields.
[0011]
According to a third aspect of the present invention, in the first aspect, the plurality of drive modes are switched in conjunction with selection of the video display mode.
[0012]
Furthermore, the invention described in claim 4 is characterized in that in claim 1, an illuminance sensor for detecting the illuminance of the surrounding environment of the display device is provided, and a plurality of drive modes are switched according to detection values of the illuminance sensor. And
[0013]
Hereinafter, a display device according to an embodiment of the present invention will be described with reference to FIGS.
[0014]
FIG. 1 shows a block diagram of a plasma display according to an embodiment of the present invention. In FIG. 1, 1 is an input terminal for an input video signal, 2 is a subfield conversion circuit, 3 is a control circuit by a microcomputer (microcomputer), 4 is a drive pulse control circuit as a control means, 5 is a light emission number table, and these drive pulse control circuit 4 and light emission number table 5 are controlled by the control circuit 3. A driving circuit 6 supplies a predetermined voltage to each electrode of a plasma display panel (PDP) 7 which is a display device having a plurality of display cells to drive display.
[0015]
FIG. 2 shows an example of the subfield (SF) configuration of the plasma display. In this example, it has a structure of 9 subfields, and each subfield is roughly divided as shown in FIG. 2 and has an address period for writing whether or not to emit light and a sustain light emitting period for actually emitting light. ing. The weights of the subfields are 1, 2, 3, 6, 11, 20, 38, 64, and 110, and the number of drive pulses that is the number of times of light emission is four times the number of pulses 4, 8, 12 in this example. , 24, 44, 80, 152, 256, 440.
[0016]
FIG. 3 is a diagram showing an example of a subfield configuration and its driving mode of the plasma display according to the present invention.
[0017]
The driving mode of FIG. 3A has a 9-subfield configuration, the weights of each subfield are 1, 2, 3, 6, 11, 20, 38, 64, 110, and the number of gradations that is the total weight is 256. It is a thing. Further, the number of drive pulses is multiplied by a certain ratio for improving the luminance. In this example, the number of drive pulses is 4, 8, 12, 24, 44, 80, 152, 256, 440 as four times.
[0018]
In the driving mode of FIG. 3b, the number of gradations which is the total number of weights is increased to 512 while maintaining the 9 subfield configuration.
[0019]
In the driving mode of FIG. 3c, the number of gradations which is the total number of weights is set to 512, which is the same as b of FIG. 3, and the number of subfields is increased to 10. In this case, as shown in FIG. 3c, the difference between the weights of adjacent subfields is smaller than that in FIG. 3b, and the generation of the moving image pseudo contour can be suppressed.
[0020]
In this drive mode, if the subfield is increased, the address time is increased. Therefore, the drive is performed within a limited time of one field. Therefore, in the example of FIG. The number of times of light emission is controlled to be the same as b in FIG. As an example of driving, if the number of lines is 500 and the period of the sustain light emission pulse is 5 μs in one line writing time 2 μs, in this case, the number of subfields is increased by 1, and the increase in time of the address period is 500 × 2 μs = 1000 μs. This corresponds to the number of sustain light emission pulses (1000 μs / 5 μs = 200), and corresponds to about 20% of the light emission pulses in the example of driving four times that in FIG.
[0021]
FIG. 4 shows an example in which a plurality of drive modes are switched in conjunction with selection of the video display mode in the present invention. In the example shown in FIG. The number 9, the total number of weights (the number of gradations) 256, and the total number of light emission pulses 1020 are set. As the drive mode 2, the number of subfields 10, the total number of weights (the number of gradations) 512, and the total number of light emission pulses 800 are set.
[0022]
That is, by switching the driving mode 1 to the driving mode 2 when the luminance is necessary and switching to the driving mode 2 when the gradation is necessary, an optimum driving method corresponding to the usage can be taken.
[0023]
Further, in conjunction with the video mode, this control is used in accordance with the purpose by selecting drive mode 1 emphasizing luminance in the dynamic mode and driving mode 2 emphasizing gradation in the standard mode. It becomes possible.
[0024]
Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the illuminance sensor 8 for detecting the illuminance of the surrounding environment of the display device is provided, information detected by the illuminance sensor 8 is input to the control circuit 3, and based on the information, as described in FIG. The driving mode 1 and the driving mode 2 having different driving modes are switched.
[0025]
That is, in FIG. 5, the brightness of the surrounding environment is detected by the illuminance sensor 8 and compared with the threshold level set by the detected value, control for switching between the driving mode 1 and the driving mode 2 is performed. The switching point of the drive mode with respect to the surrounding environment is provided with a function that can be set in advance, and is set according to the specification environment of each user. With this control, when the surrounding environment is bright, the driving mode is switched to the luminance-oriented driving mode 1 in which the luminance is more important than the gradation, and when the surrounding environment is dark, the high luminance is not necessary and the gradation of the low luminance portion is more desired. Therefore, it is possible to switch to the gradation-oriented driving mode 2 and to perform optimum display driving automatically.
[0026]
【The invention's effect】
As is clear from the above description, according to the present invention, at least a plurality of drive modes with different total weights are provided, and the drive modes are switched according to the purpose, so that it matches the use conditions, user's specification environment, lifestyle, etc. The optimum display drive can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an example of a plasma display according to an embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating an example of a subfield configuration. FIG. 3 is an explanatory diagram illustrating an example of a drive mode. FIG. 5 is a block diagram showing an example of a plasma display according to another embodiment of the present invention.
2 Subfield conversion circuit 3 Control circuit 4 Drive pulse control circuit 5 Light emission count table 6 Drive circuit 7 PDP
8 Illuminance sensor

Claims (4)

Having a display panel having a plurality of display cells, one field is composed of a plurality of subfields, luminance is weighted according to the number of times of light emission in each subfield, and gradation is determined by the combination of the presence or absence of light emission in each subfield. A display device for performing display, wherein a plurality of drive modes having different total weights in one field are provided, and the drive modes can be switched. The display device according to claim 1, wherein the driving mode includes patterns having different numbers of subfields. The display device according to claim 1, wherein the plurality of drive modes are configured to be switched in conjunction with selection of a video display mode. The display device according to claim 1, further comprising an illuminance sensor that detects illuminance of an ambient environment of the display device, and configured to switch a plurality of drive modes according to a detection value of the illuminance sensor.

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