JPH1165541A - PDP display device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a means for reliably and efficiently taking measures against PDP burning that does not depend on the operation of the user. SOLUTION: A video signal S0 is stored in a field memory 3 as 1
The field signal is delayed and compared with the video signal S0 by the comparison circuit 4 to obtain a difference between the two. The threshold circuit 5 takes out a difference equal to or greater than a predetermined threshold and writes it to the memory 6. The MPU 10 reads the data in the memory 6 every time the vertical synchronizing signal S1 is interrupted by the procedure of the image display time measurement processing unit 12a, measures the display time of the image data of a fixed pattern, and determines the still image display. The negation circuit 7 performs a negation for each bit of the video signal S0, stores it in the VRAM 8, and reads it out with the CRTC 9 to obtain screen saver display data S2 which is a one's complement of the video signal V0. When the MPU 10 continues to display a still image for a predetermined time, the switching circuit 1 switches the display of the video signal V0 from the display of the video signal V0 to the screen saver display data S2 and supplies it to the PDP 2 for display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a PDP (Plasma Display Panel) display device which eliminates a sticking phenomenon that occurs when displaying a still image on a PDP (plasma display panel).

[0002]

2. Description of the Related Art In a PDP display device, when a fixed still image such as an advertisement, a map, or a character display is displayed for a long time, a so-called burning phenomenon occurs, and when another image is displayed, it remains as an afterimage. Conventionally, in order to reduce this burning phenomenon as much as possible, fixed display is avoided as much as possible, and when not in use, it is dealt with by the use and operation of the display device such as activating the screen saver function. Was. However, in such a method, there is a problem that measures against the burning phenomenon become uncertain, and the burning of the PDP cannot be sufficiently reduced.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide means for reliably and efficiently taking measures against burning of a PDP which does not depend on the operation of a user.

[0004]

[Means for Solving the Problems] Means for measuring image data and image display time of a display image, screen saver data calculating means for calculating a one's complement from the image data, and screen saver display switching for instructing switching to screen saver display Means are provided to display the screen saver data after the image is displayed, thereby automatically avoiding burning of the PDP.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a display device for displaying an image using a PDP (Plasma Display Panel), means for measuring image data and image display time of a display image, and screen saver data for calculating one's complement from the image data Calculating means and screen saver display switching means for instructing switching to screen saver display are provided, and the screen saver data is displayed after the image is displayed.

[0006] Still image determination means for determining whether a display image is a still image is provided, and the screen saver display is performed only when a still image is displayed.

[0007] Still image display time measuring means for measuring the display time of the still image is provided, and when the display time of the still image is within a predetermined time, the screen saver display is not performed.

[0008] The screen saver display is performed for a time proportional to the display time of the still image.

An LUT (Look Up Table) storing data of an optimum screen saver display time with respect to the display time of the still image obtained by an experiment is provided, and the screen saver display is performed for a time obtained from the LUT.

The difference between the image display time and the still image display time is defined as a moving image display time, and the screen saver display time is calculated as an effective still image display time obtained by subtracting the moving image display time from the still image display time. To do.

The screen saver data calculating means for calculating the one's complement from the display image data comprises a NOT circuit for each bit of the digitized image data, and a field memory for storing the output of the NOT circuit for each field. .

A plurality of the field memories are provided, and the screen saver data is calculated from an average value of image data for each pixel output from each of the field memories.

In the calculation of the screen saver data, a value obtained by subtracting the image data to be displayed from the maximum value for each image data of each color signal to be displayed is used instead of the one's complement.

The screen saver display switching means comprises a timer for counting a predetermined time, and a controller for switching between the display image data and the screen saver data at regular intervals obtained from the timer.

The screen saver display switching means switches to screen saver data in response to a power-off signal of the PDP display device and displays the data.

The screen saver display switching means is provided with an external input key such as a remote controller, and switches and displays the screen saver data by the input key.

A means for generating all-white image data is provided so that the display can be switched to the all-white image data in accordance with designation from the input key in addition to the screen saver data.

An on-screen display circuit is provided, and when the display is switched to the screen saver data or the all-white image data, a display indicating that a screen saver display is to be performed is displayed on the display screen of the PDP.

The still image determining means stores a display image data for each field or frame, and outputs the data with a delay of one field or one frame, and the same as the output of the field memory or the frame memory. A comparison circuit for comparing image data is provided, and the determination is made based on the fact that both image data for each pixel match.

The still image is determined by integrating the comparison value for each pixel for a certain period of time.

The still image determination is performed only when the comparison value for each pixel is equal to or more than a predetermined threshold value.

The still image judging means judges a still image even when the image data changes only in a part of the display image.

The still image judging means judges a still image even when the image data changes within the switching time of the still image screen by the personal computer.

[0024] The still image judging means is provided with means for detecting a synchronizing signal of the image data, so that a still image is judged even when the image data changes within a period of disconnection of the synchronizing signal.

[0025]

FIG. 1 is a block diagram showing a main part of an embodiment of a PDP display device according to the present invention. The digital video signal S0 composed of image data is supplied to the PDP 2 via the switching circuit 1 and displayed. The digital video signal S0 is stored in the field memory 3, read out with a delay of one field, and compared with the digital video signal S0 by the comparison circuit 4 to obtain a difference between the two. By taking out the obtained difference by a threshold value circuit 5 or more by a threshold value, the influence of noise of the video signal S0 can be removed. The difference from which the noise component has been removed is written to the memory 6. The MPU 10 reads the data of the memory 6 every time the vertical synchronization signal S1 is interrupted, and measures the display time of the image data of a fixed pattern in which the output of the memory 6 becomes 0, in the procedure of the image display time measurement processing unit 12a. As a result, when the display time is equal to or longer than a predetermined time, it can be determined that a still image is displayed. On the other hand, a NOT circuit 7 performs a negation for each bit of the digital video signal S0 and stores the result in a VRAM (Video RAM) 8.
By reading the data of the VRAM 8 with a CRTC (CRT Controller) 9, the one's complement of the digital video signal can be obtained.
That is, screen saver display data S2 which is a difference from the maximum value of the video signal is obtained. According to the procedure of the screen saver display switching processing section 12b, the MPU 10 switches the switching circuit 1 when the display of the still image continues for a predetermined time, supplies the screen saver display data S2 to the PDP 2 for a predetermined time by referring to the clock 11, and displays the data. I do.

The screen saver display data S2 is displayed by the MPU 10 in the procedure of the screen display switching processing section 12b by a time proportional to the display time of the still image measured as described above. Or
An LUT 13 (Look Up Table) made up of a ROM storing data of an optimum screen saver display time with respect to a display time of a still image obtained by an experiment is provided.
Then, the screen saver display time corresponding to the display time of the still image may be read out, and the screen saver display may be performed for that time. When the display time of the above-mentioned still image is a short time within a predetermined time, a moving image is displayed, and it is not necessary to perform a screen saver display particularly for preventing burn-in. Therefore, the screen saver display is not performed. . Furthermore, the difference between the total image display time and the still image display time measured as described above is defined as the moving image display time. The screen saver display time may be calculated by setting the time obtained by subtracting the time as the effective still image display time.
In the above description, the number of field memories for measuring the time for displaying the fixed image data is one. However, the number of the field memories is plural, and the screen saver data is calculated from the average value of the image data for each pixel output from each field memory. May be calculated.

FIG. 2 is a block diagram of a main part of another embodiment of the PDP display device according to the present invention. The maximum value of each color signal of the digital video signal S0 composed of image data is adjusted by the control circuit 28 to obtain a white balance, and is supplied as the video signal S20 to the PDP 22 via the switching circuit 21 for display. In the same manner as described above, the video signal S20 is stored in the field memory 23, read out with a delay of one field, and compared with the video signal S20 by the comparison circuit 24 to obtain a difference between the two. The obtained difference is taken out by a threshold circuit 25 at a certain threshold or more, the influence of noise of the video signal S20 is removed, and the difference is stored in the memory 26. The MPU 31 reads the data in the memory 26 every time the vertical synchronizing signal S1 is interrupted, measures the display time of the image data of a fixed pattern, and determines the display of a still image in the procedure of the image display time measurement processing unit 32a. When switching to the screen saver display because the still image display has continued for a predetermined time or more,
According to the procedure of the screen saver display data calculation processing unit 32b, the MPU 31 reads out the display image data from the field memory 23, and subtracts this image data from the maximum value of each color signal set in the white balance control circuit to obtain the screen saver display data. Is written to the VRAM 30. By reading the VRAM 30 with the CRTC 29,
Screen saver display data S32 different from the above is obtained. The MPU 31 switches the switching circuit 21 to the screen saver display data S32 at predetermined time intervals by referring to the vertical synchronizing signal S1 or the clock 33 according to the procedure of the screen saver display switching processing section 32c, and performs the screen saver display on the PDP 22. This screen saver display switching can be performed by switching to screen saver display data for a predetermined time after the power is turned off at the end of the display of the PDP display device. Alternatively, the screen saver display switching may be performed by switching to screen saver display data by depressing an input key of the remote controller 34 input from the outside by a user or the like who has determined that it is necessary to further perform screen saver display for preventing burning. . As the screen saver display data, the all white image data S33 generated by the all white image data generation circuit 35 in accordance with designation from the input key of the remote controller 34 can be switched and displayed with the screen saver display data S32.

The PDP display device is provided with an on-screen display circuit 36, and when the display is switched to the screen saver display data S32 or the all-white image data S33, a display indicating that the screen saver display is to be made on the display screen of the PDP 22. To do.

When the MPU 31 measures the display time of the fixed image data, the MPU 31 integrates the comparison value for each pixel in the memory 26 for a fixed time to determine a still image, thereby obtaining a small still image which causes burning. It becomes possible to cope with a case where the image data changes. Even when the image data of only a part of the display image changes, such as the time display portion of the display screen of the PDP 22, the entire image is determined to be a still image, and the screen other than the portion where the image data changes is determined. Can be prevented from burning. Further, even when the image data changes within the switching time of the still screen by the personal computer, the still image is determined as the still image, and the still image is displayed. Further, the MPU 31 is provided with means for detecting a synchronizing signal such as the vertical synchronizing signal S1 of the image data, so that the image data is determined to be a still image even when the image data changes within the synchronization signal disconnection period. Even when image data changes due to switching of general image data, burning as a still image can be prevented by treating it as a still image as a whole.

[0030]

As described above, the image data of the display image and the means for measuring the image display time, and
Screen saver data calculating means for calculating the complement of
By providing screen saver display switching means for instructing switching to screen saver display, and displaying the screen saver data after displaying the same image,
It becomes possible to automatically avoid burning of the DP.

[Brief description of the drawings]

FIG. 1 is a principal block diagram of an embodiment of a PDP display device according to the present invention.

FIG. 2 is a block diagram of a main part of another embodiment of the PDP display device according to the present invention.

[Explanation of symbols]

 S0 Digital video signal S1 Vertical synchronization signal 1 Switching circuit 2 PDP (plasma display panel) 3 Field memory 4 Comparison circuit 5 Threshold circuit 6 Memory 7 Negation circuit 8 VRAM 9 CRTC 10 MPU 11 Clock 12a Image display time measurement processing unit 12b Screen saver display Switching processing unit 13 LUT 21 Switching circuit 22 PDP (plasma display panel) 23 Field memory 24 Comparison circuit 25 Threshold circuit 26 Memory 27 White balance circuit 28 Control circuit 29 CRTC 30 VRAM 31 MPU 32a Image display time measurement processing unit 32b Screen saver display data Calculation processing unit 32c Screen saver display switching processing unit 33 Clock 34 Remote control 35 All white image data generation circuit 36 On-screen display circuit

Claims (20)

[Claims] 1. PDP (Plasma Display Panel)
A display device for displaying an image by using the image data, a means for measuring image data and an image display time of the display image, a screen saver data calculating means for calculating a one's complement from the image data, and a screen saver for instructing switching to the screen saver display. A PDP display device comprising a display switching means for displaying the screen saver data after displaying the image. 2. The PDP display device according to claim 1, further comprising a still image determination unit for determining whether the display image is a still image, and performing the screen saver display only when a still image is displayed. 3. A still image display time measuring means for measuring the display time of the still image, wherein the screen saver display is not performed when the display time of the still image is within a predetermined time. The PDP display device according to claim 2. 4. The PDP display device according to claim 2, wherein the screen saver display is performed for a time proportional to a display time of the still image. 5. An LUT (Look Up Table) storing data of an optimum screen saver display time with respect to a display time of the still image obtained by an experiment is provided, and the screen saver display is performed for a time obtained from the LUT. The PDP display device according to claim 2, wherein: 6. The screen saver display time is defined as a difference between the image display time and the still image display time as a moving image display time, and a time obtained by subtracting the same moving image display time from the still image display time as an effective still image display time. The PDP display device according to claim 4, wherein the calculation is performed. 7. A screen saver data calculating means for calculating a one's complement from the display image data, comprising: a NOT circuit for each bit of the digitized image data; and a field memory for storing an output of the NOT circuit for each field. The PDP display device according to claim 1, wherein the PDP display device is configured. 8. The PDP display according to claim 7, wherein a plurality of said field memories are provided, and said screen saver data is calculated from an average value of image data for each pixel output from each of said field memories. apparatus. 9. The calculation of the screen saver data is as follows:
2. The PDP display device according to claim 1, wherein a value obtained by subtracting the image data to be displayed from a maximum value of each color signal to be displayed for each image data is used instead of the one's complement. 10. The screen saver display switching means comprises a timer for counting a fixed time, and a controller for switching between the display image data and the screen saver data at regular intervals obtained from the clock. The PDP display device according to claim 1, wherein: 11. The PDP display device according to claim 1, wherein the screen saver display switching means switches the display to screen saver data by a power-off signal of the PDP display device and displays the data. 12. The PDP display device according to claim 1, wherein said screen saver display switching means is provided with an external input key such as a remote controller, and switches and displays the screen saver data using the input key. . 13. A system according to claim 12, further comprising means for generating all-white image data, wherein in addition to said screen saver data, said all-white image data can be switched and displayed by designation from said input key. The PDP display device as described in the above. 14. An on-screen display circuit, wherein when the display is switched to the screen saver data or the all-white image data, a display indicating that the screen saver display is to be performed is displayed on the display screen of the PDP. The P according to claim 11, claim 12, or claim 13.
DP display device. 15. A field memory or frame memory for storing display image data for each field or frame and outputting the data with a delay of one field or one frame, an output of the field memory or the frame memory, 3. The PDP display device according to claim 2, wherein a comparison circuit for comparing the display image data is provided, and the determination is made based on a coincidence between the two image data for each pixel. 16. The PDP display device according to claim 15, wherein the still image determination is performed by integrating the comparison value for each pixel for a predetermined time. 17. The PDP display device according to claim 15, wherein the still image determination is performed only when the comparison value for each pixel is equal to or more than a predetermined threshold value. 18. The PDP display device according to claim 15, wherein said still image judging means judges a still image even when said image data changes only in a part of a display image. 19. The PDP display according to claim 15, wherein said still image judging means judges a still image even when said image data changes within a switching time of a still image screen by a personal computer. apparatus. 20. The apparatus according to claim 20, wherein said still image determination means includes means for detecting a synchronization signal of said image data, and determines that the image data is a still image even when said image data changes within a disconnection period of said synchronization signal. The PDP according to claim 15, characterized in that:
Display device.