JPH08251515A - Method for preventing burning of display device - Google Patents

Abstract

PURPOSE: To prevent the burning of the display device by changing over a gamma correction coefficient in response to a mean luminance level so as to control the contrast. CONSTITUTION: A/D converter sections 2R, 2G, 2B convert red, green, blue video signals from terminals 1R, 1G, 1B into digital signals, they are given to a matrix circuit 3, in which matrix processing is conducted, an APL calculation section 4 calculates a mean luminance level and a discrimination section 6 compares the level with a reference luminance level from a storage section 5 to output the difference. Gamma correction sections 7R, 7G, 7B read a gamma correction coefficient corresponding to a signal from the discrimination section through a control section 10 from gamma ROMs 8R, 8G, 8B to apply gamma correction to a video signal of each color from the A/D converter sections and the result is given to a display section 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display burn-in prevention method, and more particularly to a display burn-in prevention method for controlling the amplitude of a video signal by switching gamma correction coefficients.

[0002]

2. Description of the Related Art Plasma display panels (PDPs)
In such display devices, image sticking occurs on the screen due to the display like a cathode ray tube. This burn-in is lit with high brightness,
In addition, it appears remarkably when the same screen is displayed for a long time, and in order to prevent this image sticking, for example, when the same image is displayed for a long time, the image is inverted, the screen brightness is lowered, or There is a screen for switching to another prepared screen, and a screen for automatically turning off the power when there is no signal for a required time. However, if you reverse the image, the screen will look different, and if you reduce the screen brightness, the original screen may be bright,
There is a problem that the image sinks and becomes difficult to see when changing to a dark screen, and the one that switches to another screen is
If a person does not see the screen except at a specific time, such as an unmanned reception device, there will be no problem if the person is detected and the original screen is restored. It is not allowed to switch to another screen. In such a case, a method of lowering the contrast by limiting the contrast according to the average luminance level of the video signal is used, but simply limiting the amplitude of the video signal and lowering the contrast results in a screen that lacks power. Therefore, there is a problem that the image quality is deteriorated.

[0003]

SUMMARY OF THE INVENTION In view of the above, the present invention selects a gamma correction coefficient corresponding to the average luminance level of a video signal and gamma-corrects the video signal so that the video quality does not deteriorate. The purpose is to limit the brightness of the display and prevent burn-in.

[0004]

In order to solve the above problems, the present invention is an AP for calculating an average luminance level of a video signal.
An L calculation unit, a storage unit that stores a reference brightness level for preventing image sticking of the display, a determination unit that compares the data from the APL calculation unit with the data read from the storage unit, and determines a difference; A γ-ROM that stores the gamma correction coefficient of
The gamma correction coefficient corresponding to the signal from the discriminator is γ-
The present invention provides a method for preventing image sticking of a display, which comprises a gamma correction section which reads out from a ROM and gamma-corrects a video signal and outputs the gamma-corrected video signal.

[0005]

With the above-described structure, in the image sticking prevention method according to the present invention, the average luminance level of the video signal is compared with the reference value of the luminance level, and the gamma correction coefficient corresponding to the luminance difference is set to γ. Read from ROM and gamma correct the video signal, which limits the brightness of the display and prevents burn-in.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a display image sticking prevention method according to the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an essential part of an embodiment of a method for preventing seizure of a display according to the present invention. In the figure, 1R, 1G and 1B are video signal input terminals respectively for inputting red, green and blue video signals. 2R, 2G and 2B are A / D converters which convert the video signals from the video signal input terminals 1R, 1G or 1B into digital signals. 3 is a matrix circuit, A
The video signals of the respective colors from the / D converters 2R, 2G and 2B are matrixed. An APL calculator 4 integrates the signal from the matrix circuit 3 for one field, for example, to calculate an average brightness level (APL). A storage unit 5 stores a reference luminance level of a video signal, which serves as a determination reference for preventing image sticking of the display. A discriminator 6 compares the data from the APL calculator 4 with the data read from the memory 5 and outputs a difference signal. 7R, 7G and 7B are gamma correction units,
The gamma correction coefficient corresponding to the signal from the discriminator 6 is γ-R.
The OM8R, 8G or 8B is read out, and the respective video signals from the A / D converters 2R, 2G and 2B are gamma-corrected and output. Reference numeral 9 denotes a display unit, which uses a PDP as a display and displays based on signals from the gamma correction units 7R, 7G and 7B. A control unit 10 controls each unit.

Next, the operation of the image sticking prevention method according to the present invention will be described. The video signals of red, green and blue from the video signal input terminals 1R, 1G and 1B are A / D respectively.
The signals are input to the conversion units 2R, 2G or 2B, converted into digital signals, input to the matrix circuit 3 and matrixed. The signal from the matrix circuit 3 is input to the APL calculation unit 4,
For example, one field worth is integrated to calculate the average luminance level of the video signal. This data is input to the discriminating unit 6 via the control unit 10 and compared with the reference luminance level of the video signal read out from the storage unit 5 via the control unit 10 to prevent image sticking of the display device to discriminate the difference. Based on the signal from the discrimination unit 6, the control unit 10 controls the gamma correction units 7R, 7G and 7B, and the γ-ROM 8R, 8G or 8B outputs the gamma correction coefficient corresponding to the brightness level difference from the discrimination unit 6. The video signals read out and inputted from the A / D converters 2R, 2G or 2B are gamma-corrected and inputted to the display unit 9. By this gamma correction, the output signal is lowered to an appropriate level as in the example shown in FIG. 2, the brightness of the display is suppressed, and the burn-in of the PDP is prevented.

In the above, the video signals of each color of red, green and blue are matrixed by the matrix circuit 3, and the APL calculation unit 4
The average brightness level was calculated with, but A for each color
A PL calculation unit is provided, and the discrimination unit 6 compares the average luminance level for each color with the data from the storage unit 5, and according to the difference, γ-RO
Corresponding gamma correction coefficients may be read out from M8R, 8G or 8B, and the video signals may be gamma-corrected by the gamma correction units 7R, 7G and 7B.

As described above, by controlling the contrast of the video signal by switching the gamma correction coefficient, the brightness of the display is limited without lowering the image quality as compared with the case of controlling the contrast without relying on the gamma correction. It is possible to prevent seizure.

[0010]

As described above, according to the display burn-in prevention method of the present invention, the gamma correction coefficient is switched according to the average luminance level of the video signal, and the video signal is corrected to correct the luminance of the display. Therefore, it is possible to prevent the image sticking of the display device without deteriorating the image quality.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of an embodiment of a method for preventing seizure of a display according to the present invention.

FIG. 2 is a diagram for explaining the operation of the image sticking prevention method for a display according to the present invention.

[Explanation of symbols]

 2R, 2G, 2B A / D conversion unit 3 matrix circuit 4 APL calculation unit 5 storage unit 6 determination unit 7R, 7G, 7B gamma correction unit 8R, 8G, 8B γ-ROM 9 display unit 10 control unit

Claims (5)

[Claims] 1. A for calculating an average luminance level of a video signal
A PL calculation unit, a storage unit that stores a brightness level that serves as a criterion for preventing the image sticking of the display unit, and a determination unit that compares the data from the APL calculation unit with the data read from the storage unit to determine a difference; Γ-RO storing a plurality of gamma correction coefficients
A method for preventing burn-in of a display device, comprising: M, and a gamma correction unit for reading out a gamma correction coefficient corresponding to the signal from the discriminating unit from the γ-ROM and performing gamma correction on the video signal and outputting the gamma-corrected image signal. 2. The method according to claim 1, wherein the γ-ROM stores gamma correction coefficients respectively corresponding to a plurality of average luminance levels of a video signal. 3. A for converting a video signal into a digital signal
An A / D conversion unit is provided, and the APL calculation unit calculates an average luminance level based on a signal from the A / D conversion unit.
3. The image sticking prevention method for a display device according to claim 1, wherein the gamma correction section gamma-corrects the video signal from the A / D conversion section. 4. The A / D conversion unit, gamma correction unit, γ-
A ROM and an APL calculation unit are provided for each of the red, green and blue video signals, and each of the red, green and blue video signals is processed, and the discrimination unit stores the data from the APL calculation unit for each color. The difference is discriminated by comparing with the data read from the storage unit, and the gamma correction coefficient corresponding to the signal from the discriminating unit is applied to the γ-ROM for each color.
4. The image signals of the respective colors are read out, and the gamma correction section for the respective colors performs the gamma correction on the respective video signals.
Method for preventing seizure of the indicated display. 5. The A / D conversion unit, the gamma correction unit, and the γ-ROM are provided for each of the red, green, and blue video signals, and each of the red, green, and blue video signals is processed. 4. The display device according to claim 3, wherein a matrix circuit for matrixing the video signals from the A / D conversion units for each color is provided, and the average brightness level is calculated by the APL calculation unit based on the signals from the matrix circuit. Seizure prevention method.