JPH10207423A - Plasma display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict reducing the illuminance of a high illuminance signal to the minimum, to make the influence for animation video to the minimum, and to prevent heat destruction of a panel by judging whether an inputted video signal is an animation or a still picture and controlling the illuminance of the inputted video signal in accordance with the result. SOLUTION: Inputted video signals are synthesized by an adder 1 and made to an illuminance signal, it is inputted to a frame memory 8 and a level conversion table 2, then illuminance signal and an output signal from the frame memory 8 are inputted to an subtracter 9, and a difference between frames of video signals is detected. And it is judged whether the video signal is an animation or a still picture by this difference of frames in a movement discriminating section 10, and a coefficient inputted to a multiplier 3 is switched by switching a characteristic of the level conversion table 2. And a plasma display panel 7 is driven by controlling an anode driver 5 and a cathode driver 6 by a panel driving control section 4 with a video signal outputted from the multiplier 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a panel thermal destruction protection circuit suitable for preventing a panel from being cracked due to local temperature rise of the panel itself due to driving in a plasma display panel.

[0002]

2. Description of the Related Art A large screen is required to enjoy a high-definition image with a sufficient sense of presence and power. Therefore, a “wall-mounted TV” that does not take depth even when the screen becomes large has been desired as a high-vision receiver. Among various flat displays, a plasma display is promising as a device that can achieve the image quality required for high-definition video and is relatively easy to increase in size, and is currently being actively developed.

[0003] A plasma display is a device in which a gas discharge is caused in each space (pixel) partitioned between two glass plates, and a phosphor is emitted by emitted ultraviolet rays.

[0004] One of the problems to be solved in such a plasma display panel is thermal destruction of the panel. Thermal destruction of a panel is a phenomenon in which a temperature difference due to light emission occurs in a portion where a luminance difference of a picture to be displayed is large, and the temperature difference causes a distortion and a crack in a glass plate.

For example, in a white (maximum luminance) and black (non-light emitting) portion, the amount of current for driving the panel is different, and the amount of heat generation is significantly different. Since the heat causes the glass plate constituting the panel to expand or contract, the boundary between white and black becomes the boundary between expansion and contraction. If this state continues for a long time, the glass plate will crack. The time until cracking depends on the material of the glass plate and the temperature difference at the boundary due to the brightness difference.

Hereinafter, prevention of thermal destruction of a conventional plasma display panel will be described. FIG. 5 shows a configuration of a conventional panel thermal destruction prevention circuit, which comprises an adder 1, a level conversion table 2, a multiplier 3, a panel drive control unit 4, an anode driver 5, a cathode driver 6, and a plasma display panel 7. Have been.

In the conventional configuration, the input signal is synthesized by the adder 1 and the generated luminance signal Y is monitored. By changing the coefficient G of the multiplier 3 using the level conversion table having the characteristic of B shown in the figure, the signal level is reduced to a luminance at which the output of the multiplier 3 does not cause thermal destruction.

The level-converted signal is applied to panel drive control unit 4
And drives the plasma display panel 7 by controlling the anode driver 5 and the cathode driver 6 to display pixels. Thus, by suppressing the luminance with respect to the high luminance signal, the temperature rise of the panel is suppressed, and the occurrence of thermal destruction is prevented.

[0009]

However, in the above arrangement, since the panel is driven by lowering the luminance of the high luminance signal, the average luminance of the image is reduced, resulting in an image with insufficient brightness. Had.

[0010]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a determining unit for determining whether an input video signal is a moving image or a still image, and the input unit according to the result of the determining unit. The present invention provides a plasma display including a brightness control unit for controlling the brightness of a video signal.

As a result, it is possible to minimize the reduction of the luminance of the high luminance signal, minimize the influence on the moving image, and prevent the panel from being thermally damaged.

Further, according to the present invention, one pixel or a plurality of pixels are defined as one block, the horizontal coordinate is set to M, the vertical coordinate is set to N, and the panel display section is divided into (M × N) blocks. The average luminance is detected from the luminance of each pixel in the block, and the average luminance of an arbitrary block (m, n) and peripheral blocks (m-1, n-1), (m, n-1), (m +
1, n-1), (m-1, n), (m + 1, n), (m-
An object of the present invention is to provide a plasma display which compares the average luminance of (1, n + 1), (m, n + 1), and (m + 1, n + 1) and switches the luminance of an input video signal according to the result.

As a result, it is possible to minimize the reduction of the luminance of the high luminance signal, minimize the influence on the displayed image, and prevent the panel from being thermally damaged.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a determining unit for determining whether an input video signal is a moving image or a still image, and a brightness control for controlling the brightness of the input video signal according to the result of the determining unit. The present invention relates to a plasma display having a unit, a specific configuration example of which is an adder that synthesizes an input video signal to generate a luminance signal, a frame memory that stores one frame of video data, A subtracter for detecting a frame difference of an output signal from a frame memory; a motion determining unit for determining whether the image is a moving image or a still image based on the frame difference; and a coefficient input to a multiplier based on a determination result of the motion determining unit. A level conversion table, a multiplier for converting the luminance of the video signal input by the coefficient, and an anode driver and a cathode driver for receiving the signal from the multiplier. Characterized in that it comprises a panel drive control section for controlling.

Further, according to the present invention, the panel display section is divided into a plurality of blocks by using one or more pixels on the panel display section as one block, and an average luminance is detected from the luminance of each pixel in each block. The present invention relates to a plasma display having a brightness control unit that compares the brightness of the blocks of the video signal and controls the brightness of the input video signal according to the result.A specific configuration example is to synthesize the input video signal. An adder for generating a luminance signal, a panel display unit divided into blocks each composed of one or more pixels, a luminance distribution detection unit for detecting an average luminance in each block, and an average block luminance of an arbitrary block of the panel display unit And a luminance distribution determining unit that compares the average luminance of the peripheral blocks with the luminance distribution determining unit. A table, those comprising a multiplier for converting the luminance of the input video signal by said coefficient, and a panel drive control unit which controls the anode driver and cathode driver receives a signal from the multiplier.

According to the structure of the present invention, the panel is prevented from being cracked due to a local temperature rise of the panel itself due to the driving, and the brightness of the high brightness signal is reduced to a minimum. Impact on the
In addition, thermal destruction of the panel can be prevented.

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG.
, 8 is a frame memory for storing a video signal for one frame, 9 is a subtractor for obtaining a difference between video signals between frames, and 10 is a motion for judging whether the video signal is a moving image or a still image from the result of the subtractor 9. It is a determination unit. In FIG. 1, the same reference numerals as those in FIG. 5 denote the same names.

The input video signals of R, G, and B are combined by an adder 1 and input to a frame memory 8 and a level conversion table 2 as a luminance signal Y. Luminance signal Y
And the output signal Y2 from the frame memory is input to the subtractor 9, the frame difference of the video signal is detected, the motion determining unit 10 determines whether the image is a moving image or a still image, and the characteristics of the level conversion table 2 are switched. The coefficient G input to the multiplier 3 is switched. The panel driver 4 controls the anode driver 5 and the cathode driver 6 with the video signal output from the multiplier 3 to drive the plasma display panel 7.

When the input signal is a moving image, even if there is a portion having a large luminance difference in the picture to be displayed, since the image is a moving image, the portion having a large luminance difference is not fixedly displayed on the same portion of the panel, and the temperature is not changed. Since the rise occurs almost uniformly throughout the panel, thermal breakdown is unlikely to occur. Therefore, the coefficient G of the multiplier 3 is determined based on the characteristic of FIG. 2A, and the input signal and the output signal level of the multiplier 3 are converted at a conversion ratio matching the light emission characteristics of the panel. This makes it possible to display a high-luminance video without lowering the luminance during moving images.

When the input signal is a still image, a portion having a large luminance difference in the picture to be displayed is fixedly displayed on the same portion of the panel, and a temperature rise occurs locally in the panel for a long time. Distortion occurs and thermal destruction occurs. Therefore, as in the conventional case, level conversion is performed using the characteristic of B, and when a signal of luminance y or more that may cause thermal destruction is input, the coefficient is changed in a region where the signal level is large, and the multiplier 3 Lower the output signal level. This allows
By suppressing the luminance only for the high luminance signal of the still image, the temperature rise of the panel is suppressed and the occurrence of thermal destruction is prevented.

As described above, according to the first embodiment, the input video signal is synthesized by the adder 1 to generate a luminance signal, which is input to the frame memory 8 and the level conversion table 2 and the luminance signal is input. And the output signal from the frame memory is input to the subtractor, the frame difference of the video signal is detected, the motion determining unit 10 determines whether the image is a moving image or a still image based on the frame difference, and switches the characteristics of the level conversion table 2. By switching the coefficient input to the multiplier 3, the panel driver control unit controls the anode driver 5 and the cathode driver 6 with the video signal output from the multiplier 3 to drive the plasma display panel 7. Panel heat that minimizes the drop in luminance of the luminance signal, minimizes the effect on video images, and prevents thermal damage to the panel It is possible to provide a corrupted protection circuit.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described.

In the present embodiment, the panel display section is divided into one or a plurality of pixels, and the luminance signal is determined by averaging the luminance of the pixels in each block. The average luminance is compared with an adjacent block or a peripheral block, and the luminance of an input video signal is controlled according to the result. This embodiment will be described with reference to the drawings.

In FIG. 3, reference numeral 11 denotes a luminance distribution detecting unit for calculating the average luminance of each block, and 12 denotes a luminance distribution determining unit for comparing the average luminance with surrounding blocks.

The input video signals of R, G, and B are combined by an adder 1 and input to a luminance distribution detecting section 11 and a level conversion table 2 as a luminance signal Y. As shown in FIG. 4, the luminance distribution detecting section 11 divides the panel display section 7 into (M × N) blocks of horizontal coordinates M and vertical coordinates N, and detects the average luminance in each block. Each block may be composed of one pixel, or may be composed of a plurality of pixels.

The luminance detecting section 11 detects the average luminance of the block from the luminance of the pixels in each block. The detection result is input to the luminance distribution comparison unit 12, and an arbitrary block (m, n) portion (m is an arbitrary positive number equal to or less than M and n is an arbitrary positive number equal to or less than N) on the panel display unit 7 Average luminance and surrounding blocks, for example (m-1, n-1), (m, n-1),
(M + 1, n-1), (m-1, n), (m + 1, n),
(M-1, n + 1), (m, n + 1), (m + 1, n +
1) Compare the respective average luminances and switch the characteristics of the level conversion table 2. The coefficient G input to the multiplier 3 is switched according to the result.

The panel driver 4 controls the anode driver 5 and the cathode driver 6 with the video signal output from the multiplier 3 to drive the plasma display panel 7. An example of the luminance distribution detection unit can calculate the average luminance by writing the luminance signal Y to the memory and reading the luminance signal Y for each arbitrary block.

For example, the average luminance of a block in an arbitrary (m, n) portion and the peripheral blocks (m-1, n-1), (m,
n-1), (m + 1, n-1), (m-1, n), (m
+ 1, n), (m-1, n + 1), (m, n + 1), (m
+1 and n + 1), the temperature rise may be fixed to the same part of the panel if the average luminance is not significantly different and if any of the time is shorter than the time leading to panel destruction. No heat destruction occurs because it occurs in the entire panel. Therefore, the coefficient G of the multiplier is determined based on the characteristic shown in FIG. 2A, and the input signal and the output signal level of the multiplier are converted at a conversion ratio suitable for the light emission characteristic of the panel. This makes it possible to display the high-luminance signal without lowering the luminance.

On the other hand, the average luminance of an arbitrary (m, n) block and the surrounding blocks (m-1, n-1), (m, n)
n-1), (m + 1, n-1), (m-1, n), (m
+ 1, n), (m-1, n + 1), (m, n + 1), (m
If the average luminance of any of (+1, n + 1) is significantly different and the time is longer than the time required for the panel to undergo thermal destruction, the temperature rise due to the picture to be displayed is fixed to the same part of the panel. Distortion occurs and thermal destruction occurs. Therefore, as in the conventional case, level conversion is performed using the characteristic of B, and when a signal having a luminance of y or more that may cause thermal destruction is input, the coefficient is changed in a region where the signal level is large, and the output of the multiplier is changed. Decrease the signal level. This allows
By suppressing the luminance only for the high luminance signal, the temperature rise of the panel is suppressed, and the occurrence of thermal destruction is prevented.

As described above, according to the second embodiment, the input video signals are synthesized by the adder and input to the luminance detection unit and the level conversion table as a luminance signal. The panel display is divided into M * N blocks,
The average luminance in each block is detected, the detection result is input to a luminance distribution comparison unit, the average luminance of an arbitrary block (m, n) of the panel is compared with the average luminance of peripheral blocks, and a level conversion table is obtained. By switching the characteristics of the above, by switching the coefficient to be input to the multiplier, the video signal output from the multiplier, by controlling the anode driver, the cathode driver by the panel drive control unit, to drive the plasma display panel, Provided is a plasma display capable of protecting a panel from thermal destruction, which minimizes a decrease in luminance of a high-luminance signal, minimizes an influence on a displayed image, and prevents a panel from being thermally destructed. be able to.

[0031]

As described above, in the plasma display of the present invention, the input video signal is synthesized by the adder to form a luminance signal, which is input to the frame memory, and the luminance signal and the output signal from the frame memory are subtracted. , The frame difference of the video signal is detected, the motion determining unit determines whether the image is a moving image or a still image based on the frame difference, and by switching the characteristics of the level conversion table, the coefficient input to the multiplier is switched. By controlling the anode driver and cathode driver by the panel drive control unit with the video signal output from the display, and driving the plasma display panel, it is possible to minimize the reduction of the brightness of the high brightness signal, and The influence can be minimized and the thermal destruction of the panel can be prevented.

In the plasma display of the present invention, the input video signals are synthesized by an adder and input as a luminance signal to a luminance detection section and a level conversion table, and the panel display section is set to M * N by the luminance distribution detection section. Divided into blocks, the average luminance of each block is detected, and the detection result is input to the luminance distribution comparison unit, and the average luminance of an arbitrary block (m, n) of the panel and the average luminance of peripheral blocks are calculated. By switching the characteristics of the level conversion table, the coefficient to be input to the multiplier is switched, and the video signal output from the multiplier is used to control the anode driver and the cathode driver by the panel drive control unit, and the plasma display By driving the panel, the reduction of the brightness of the high-brightness signal is minimized, the effect on the displayed video is minimized, and the It can be possible to prevent thermal destruction.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a plasma display according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a characteristic example of a signal level conversion unit according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a plasma display according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a luminance distribution detection block according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional plasma display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adder 2 Level conversion table 3 Multiplier 4 Panel drive control part 5 Anode driver 6 Cathode driver 7 Plasma display panel 8 Frame memory 9 Subtractor 10 Motion detecting part 11 Luminance distribution detecting part 12 Luminance distribution judging part

Claims (4)

[Claims] 1. A plasma display comprising: a determination unit that determines whether an input video signal is a moving image or a still image; and a brightness control unit that controls brightness of the input video signal according to a result of the determination unit. 2. An adder for synthesizing an input video signal into a luminance signal, a frame memory storing one frame of video data, and detecting a frame difference between the luminance signal and an output signal from the frame memory. A subtractor, a motion determining unit that determines whether the image is a moving image or a still image based on the frame difference, a level conversion table that switches a coefficient to be input to a multiplier based on a determination result of the motion determining unit, and an image input by the coefficient. A plasma display, comprising: a multiplier for converting a luminance of a signal; and a panel drive control unit that receives a signal from the multiplier and controls an anode driver and a cathode driver. 3. The panel display section is divided into a plurality of blocks by using one pixel or a plurality of pixels on the panel display section as one block, an average luminance is detected from the luminance of each pixel in each block, and a peripheral block is detected. A plasma display including a luminance control unit that compares the luminance with an average luminance and controls the luminance of an input video signal according to the result. 4. An adder for synthesizing an input video signal to generate a luminance signal, and a luminance distribution detection for dividing a panel display section into blocks each composed of one or more pixels and detecting an average luminance in each block. Unit, a luminance distribution determining unit that compares the average luminance of an arbitrary block of the panel display unit with the average luminance of the peripheral blocks, and a level conversion that switches a coefficient to be input to a multiplier based on a result of the determination by the luminance distribution determining unit. A plasma display, comprising: a table; a multiplier for converting luminance of a video signal input by the coefficient; and a panel drive control unit for receiving a signal from the multiplier and controlling an anode driver and a cathode driver.