JP2006267619A - Plasma television and plasma display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma television and a plasma display device which are capable of preventing image sticking without depending upon an inputted video signal. <P>SOLUTION: An inversion circuit 20 replaces the most significant bit most contributing to gradation with the least significant bit having the most random nature in gradation data, whereby gradation data processed by the inversion circuit 20 has a random nature. Consequently, random video can be displayed on a PDP panel 13, so that a temperature distribution of each cell is made uniform to be able to resolve image sticking. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma television and a plasma display device including a plasma display panel that inputs a digital video signal and reproduces an image on a display surface.

Conventionally, as this type of plasma display device, when a display image is a still image, an apparatus that displays a reverse image of the still image as a screen saver is known (for example, see Patent Document 1).
According to this configuration, a cell having a high luminance when displaying a still image has a low luminance when the screen saver is displayed. On the other hand, a cell having a low luminance when displaying a still image has a high luminance when the screen saver is displayed. Therefore, when the screen saver is displayed, the former cell can be cooled and the latter cell can be heated. Therefore, the temperature difference between the two cells is eliminated, and it is possible to eliminate the image sticking caused by the temperature difference.
JP-A-11-65541

  The above-described plasma display device prevents burn-in during a still image. However, even in the case of a moving image, a moving image with little movement causes a deviation in luminance distribution and burn-in occurs. Therefore, in the conventional technology targeted for burn-in by still images, there is a problem that burn-in caused by a moving image with little movement cannot be eliminated.

  Also, it is considered that burn-in can be eliminated in the same manner by displaying an inverted moving image as a screen saver even for a moving image with little movement. However, in a moving image with little motion, there are some cells whose luminance has changed. For such a cell, a reverse moving image is displayed as a screen saver, so that burn-in is promoted. For example, a cell that has changed from a high luminance to a low luminance is again set to a high luminance in the inverted moving image, so that the temperature rise is significant. On the other hand, a cell that has changed from a low luminance to a high luminance is set to a low luminance again in the inverted moving image, and therefore remains at a low temperature. That is, since burn-in is promoted locally, a reverse moving image cannot be displayed as a screen saver for a moving image with little movement.

  The present invention has been made in view of the above problems, and an object thereof is to provide a plasma television and a plasma display device capable of preventing burn-in without depending on an input video signal.

In order to achieve the above object, a second aspect of the present invention provides a plasma display device including a plasma display panel that inputs a digital video signal and reproduces an image on a display surface.
An A / D conversion means for converting an analog video signal into a digital video signal, and interposed between the A / D conversion means and the plasma display panel, represent the gradation of the digital video signal according to a predetermined condition. Inversion means for replacing the most significant bit of data with the least significant bit is provided.

  According to the second aspect configured as described above, an image based on the digital image signal is reproduced on the display surface of the plasma display panel. An analog video signal is input to the A / D conversion means, and converted into a digital video signal by the A / D conversion means. Further, the digital video signal is input to the plasma display panel through the inverting means, and an image based on the digital video signal is reproduced on the display surface of the plasma display panel.

  The inversion means replaces the most significant bit of the data representing the gradation of the digital video signal with the least significant bit according to a predetermined condition. That is, when the inversion means operates, the digital video signal is processed so that the value of the least significant bit becomes the value of the most significant bit. The value of the least significant bit that easily reflects a random error can be used as the value of the most significant bit that contributes most to the gradation level of the digital video signal. Accordingly, the digital video signal capable of reproducing a random image can be output to the plasma display panel. Therefore, when the inverting means operates, the digital video signal imbalance can be eliminated and burn-in can be eliminated. Of course, the randomness of the least significant bit does not depend on the analog video signal, and therefore any burn-in prevention effect can be exhibited when any analog video signal is input.

The invention according to claim 3 further comprises A / D conversion means for converting an analog video signal into a digital video signal, and the inversion means is provided between the A / D conversion means and the plasma display panel. As an intervening configuration.
In the invention of claim 3 configured as described above, since the digital video signal is generated by the A / D conversion means, the gradation of the digital video signal is adjusted by a sampling error at the time of A / D conversion. The least significant bit of the data to be represented can be given randomness. Thus, the digital video signal capable of reproducing a highly random image can be output to the plasma display panel.

Further, in the invention according to claim 4, the inversion means is a data representing gradation of the digital video signal in a state where the plasma display panel inputs the digital video signal output from the A / D conversion means. The most significant bit is replaced with the least significant bit.
In the invention of claim 4 configured as described above, the most significant bit of the data is replaced with the least significant bit in a state where randomness is given to the least significant bit of the data representing the gradation of the digital video signal. It is said. Thereby, the said inversion means can be operated in the state where the burn-in prevention effect is exhibited.

According to a fifth aspect of the present invention, the inversion means terminates the replacement when a predetermined time has elapsed after starting to replace the most significant bit of the data representing the gradation of the digital video signal with the least significant bit. As a configuration.
In the invention of claim 5 configured as described above, the most significant bit of the data representing the gradation of the digital video signal is continuously replaced with the least significant bit until a predetermined time elapses. That is, when the image sticking is eliminated to some extent, normal display can be performed.

Furthermore, the invention according to claim 6 is configured such that the inversion means replaces the most significant bit of the data representing the gradation of the digital video signal with the least significant bit when a predetermined operation by the user is accepted.
In the invention of claim 6 configured as described above, the reversing means can be operated in accordance with a user operation. That is, burn-in prevention can be performed according to the user's request.

Further, in the invention according to claim 7, the A / D conversion means extracts the analog video signal inputted from the channel selection means for extracting a desired signal from the broadcast radio wave and generating an analog video signal, to the digital video signal. It is configured to convert.
In the invention of claim 7 configured as described above, there is provided channel selection means for extracting a desired signal from a broadcast radio wave and generating an analog video signal, and the analog video signal input from the channel selection means is converted into the A / D conversion means converts to the digital video signal. That is, at the time of television reception, an image with high randomness can be reproduced on the plasma display panel, and burn-in can be prevented.

Furthermore, the invention according to claim 8 is configured such that the inversion means rearranges data representing the gradation of the digital video signal in ascending order of bit order.
In the invention of claim 8 configured as described above, a bit value having a high possibility of having randomness is used as a bit value having a higher contribution of the gradation of the digital video signal. Therefore, an image with high randomness can be reproduced on the plasma display panel, and burn-in can be prevented.

Based on the above configuration, the invention of claim 1 is a plasma television including a plasma display panel that inputs a digital video signal and reproduces an image on a display surface.
Channel selection means for extracting a desired signal from broadcast radio waves and generating an analog video signal, A / D conversion means for converting the analog video signal into a digital video signal, the A / D conversion means, and the plasma display panel In a state in which the plasma display panel inputs the digital video signal output from the A / D conversion means, until a predetermined time elapses after a predetermined operation by the user is received, Inverting means characterized in that the data representing the gradation of the digital video signal is rearranged in ascending order of bit order.

Needless to say, in such a more specific configuration, the same effects as the above-described inventions of claims 2 to 8 can be obtained.
The technical idea according to the present invention can also be grasped as an invention of a program that causes a computer to execute the same processing as the processing executed by each of the above means.

As described above, according to the first and second aspects of the invention, it is possible to provide a plasma television and a plasma display device capable of preventing burn-in without depending on an input video signal.
According to the invention of claim 3, an image with high randomness can be displayed and burn-in can be prevented.
According to the invention of claim 4, it is possible to display a burn-in prevention image in a state where the burn-in prevention effect is high.

According to the invention of claim 5, the normal display can be restored.
According to the sixth aspect of the present invention, burn-in can be prevented according to the user's request.
According to the invention of claim 7, burn-in can be prevented at the time of television reception.
According to the eighth aspect of the present invention, it is possible to prevent burn-in by displaying a highly random image.

Embodiments of the present invention will be described in the following order.
(1) Configuration of plasma television:
(2) Configuration of inverting circuit:
(3) Signal switching process:
(4) Modification:
(5) Summary:

(1) First embodiment:
FIG. 1 is a block diagram showing the configuration of an embodiment of a plasma (PDP) television according to the present invention.
In FIG. 1, a PDP television 10 generally includes a tuner 11, a video signal processing circuit 12, a PDP panel 13, a microcomputer 14, a selector circuit 15, and an inverting circuit 20. The video signal processing circuit 12 includes a digital signal processing circuit 12a and an adjustment circuit 12b inside, and a control circuit 12c and a microcomputer I / F 12d are connected via a bus 12e such as an IIC bus. A microcomputer 14 is connected to the microcomputer I / F, and the microcomputer 14 can control each circuit of the video signal processing circuit 12 via the microcomputer I / F 12d.

  Here, the microcomputer 14 is connected with an operation panel 14a, a remote control I / F 14b, a ROM 14c, a RAM 14d, a flash memory slot 14e, and a timer 14f, and the microcomputer 14 reads various control programs stored in advance in the ROM 14c. The RAM 14d is used as a work area, and the control of each circuit described above is executed. In addition, a portable memory such as a compact flash memory can be mounted in the flash memory slot 14e, and the microcomputer 14 can acquire digital image data stored in the portable memory. It has become. Digital image data acquired by the microcomputer 14 is written in a frame memory 12b2 described later and displayed on a plasma display (PDP) panel 13.

  Here, the PDP panel 13 is a display element in which a large number of discharge cells are arranged in a dot matrix on the display surface, and plasma sealed in each discharge cell emits light. The light emitted from the plasma collides with a predetermined phosphor and is converted into RGB visible light. The balance of RGB visible light can be adjusted by controlling the light emission amount (luminance) in each discharge cell. As a result, it is possible to emit light with a desired color and brightness in one pixel composed of RGB cells.

  The tuner 11 is a tuner for analog television, and receives television broadcast radio waves with a connected antenna 11a. The tuner 11 outputs a television broadcast signal (composite video signal) as an analog video signal based on the received television broadcast radio wave. The PDP television 10 also receives an external input terminal 15a for inputting an analog video signal (composite video signal) from the VTR as an external input terminal, and an analog video signal (composite video signal) from the LD player. And an external input terminal 15c for inputting an analog video signal (composite video signal) from the DVD player.

  The tuner 11 and the external input terminals 15a to 15c are connected to the selector circuit 15. The composite video signal (television broadcast signal) output from the tuner 11 and the composite video signal input from the external input terminal 15a and the external input. One composite video signal can be selected from the composite video signal input from the terminal 15b and the composite video signal input from the external input terminal 15c. This selection is performed by an operation by a remote controller that is input via an operation panel 14a connected to the microcomputer 14 and a remote controller I / F 14b. The composite video signal selected by the selector circuit 15 is sent to the video signal processing circuit 12. The sent composite video signal is input to the digital signal processing circuit 12 a inside the video signal processing circuit 12.

  The digital signal processing circuit 12a includes an A / D conversion circuit 12a1, a Y / C separation circuit 12a2, a chroma decoder circuit 12a3, an image quality adjustment circuit 12a4, and a matrix circuit 12a5. In this configuration, when the composite video signal is input, the A / D conversion circuit 12a1 has a predetermined signal level range between the white level and the black level in the composite video signal, and a digital signal having a gradation corresponding to each signal level. Convert to Subsequent predetermined signal processing is executed based on this digital signal. The Y / C separation circuit 12a2 performs separation processing into a Y signal and a C signal based on this digital signal. The separated Y signal and C signal are input to the chroma decoder circuit 12a3 and subjected to predetermined signal processing. Later, it is output as a YUV signal.

  The image quality adjustment circuit 12a4 of the digital signal processing circuit 12a adjusts sharpness, color, and TINT for the YUV signal. The matrix circuit 12a5 performs RGB matrix conversion processing on the YUV signal whose image quality has been adjusted by the image quality adjustment circuit 12a4 to generate RGB data. The generated RGB data is sent to the adjustment circuit 12b. The adjustment circuit 12b includes a pixel number conversion circuit 12b1, an image quality adjustment circuit 12b2, an output processing circuit 12b3, and a frame memory 12b4. The pixel number conversion circuit 12b1 receives the RGB data generated by the digital signal processing circuit 12a, and performs RGB data for one screen displayed on the PDP panel 13 while performing scaling processing on the RGB data. Generate. The RGB data for one screen is stored in the frame memory 12b4. In the present embodiment, it is assumed that RGB gradation data corresponding to each cell of the PDP panel 13 is expressed by 256 gradations (8 bits). Then, the plasma of each cell is emitted with a luminance substantially proportional to the gradation data.

  The image quality adjustment circuit 12b2 of the adjustment circuit 12b is subjected to scaling processing by the pixel number conversion circuit 12b1, and adjusts brightness, contrast, black balance, and white balance for the RGB data stored in the frame memory 12b4. . The output processing circuit 12b3 performs gamma correction, dither processing, and the like on the RGB gradation data that has undergone image quality adjustment by the image quality adjustment circuit 12b2, and adds a background signal, an OSD signal, a blanking signal, and the like. The same gradation data is output to the inverting circuit 20.

  The inversion circuit 20 described in detail later performs predetermined processing on the gradation data and outputs the gradation data to the subsequent PDP panel 13. As described above, the composite video signal input from the selection destination selected by the selector circuit 15 is input to the A / D conversion circuit 12a1 of the digital signal processing circuit 12a and converted into a digital signal. The PDP panel 13 reproduces an image on the display surface by discharging each cell in accordance with RGB gradation data processed based on the digital signal. However, the digital image data acquired by the microcomputer 14 from the flash memory slot 14e is written in the frame memory 12b2 without being passed through the A / D conversion circuit 12a1, and displayed on the plasma display (PDP) panel 13. The

(2) Configuration of inverting circuit:
FIG. 2 shows a circuit configuration of the inverting circuit 20. In the figure, the inverting circuit 20 includes a cross circuit 21 and a switch unit 22. The cross circuit 22 has input terminals B0 to B7, and 8-bit parallel data representing luminance gradation is input to the input terminals B0 to B7. The most significant (highest digit) bit signal of the parallel data is input to the input terminal B0, the second bit signal is input to the input terminal B1, and the third bit signal is input to the input terminal B2. The fourth bit signal is input to the input terminal B3, the fifth bit signal is input to the input terminal B4, the sixth bit signal is input to the input terminal B5, and the sixth terminal signal is input to the input terminal B6. A 7-bit signal is input, and the least significant bit signal is input to the input terminal B7.

  The switch unit 22 includes switch elements S0 to S7 using diodes, bipolars, transistors, MOSFETs, or the like. Each switch element S0 to S7 receives a selection signal output from the microcomputer 14. The switch element S0 can be connected to either of the terminals S0a and S0b according to the selection signal. Similarly, each of the switch elements S1 to S7 is connected to any one of the terminals S1a, S1b, S2a, S2b, S3a, S3b, S4a, S4b, S5a, S5b, S6a, S6b, S7a, S7b according to the selection signal. It is possible to do. When the selection signal is low, the switch elements S0 to S7 are connected to the terminals S0a, S1a, S2a, S3a, S4a, S5a, S6a, and S7a on the upper side of the drawing. On the other hand, when the selection signal is high, each of the switch elements S0 to S7 is connected to terminals S0b, S1b, S2b, S3b, S4b, S5b, S6b, and S7b on the lower side of the drawing.

  The most significant bit of the gradation data input to the input terminal B0 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S0a of the switch element S0 and the terminal S7b of the switch element S7. The second bit input to the input terminal B1 of the cross circuit 21 branches in the cross circuit 21 and reaches the terminal S1a of the switch element S1 and the terminal S6b of the switch element S6. The third bit of the gradation data input to the input terminal B2 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S2a of the switch element S2 and the terminal S5b of the switch element S5. The fourth bit of the gradation data input to the input terminal B3 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S3a of the switch element S3 and the terminal S4b of the switch element S4.

  Similarly, the fifth bit of the gradation data input to the input terminal B4 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S4a of the switch element S4 and the terminal S3b of the switch element S3. The sixth bit of the gradation data input to the input terminal B5 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S5a of the switch element S5 and the terminal S2b of the switch element S2. The seventh bit of the gradation data input to the input terminal B6 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S6a of the switch element S6 and the terminal S1b of the switch element S1. The last bit of the gradation data input to the input terminal B6 of the cross circuit 21 branches at the cross circuit 21 and reaches the terminal S7a of the switch element S7 and the terminal S0b of the switch element S0.

  The switch elements S0 to S7 are connected to the output terminals O0 to O7 of the inverting circuit 20. The output terminals O0 to O7 are connected to the PDP panel 13. The PDP panel 13 inputs the parallel data output to the output terminals O0 to O7, and discharges in corresponding cells based on the parallel data. For example, as shown in FIG. 3, it is assumed that gradation data in which each bit is represented by “1, 0, 1, 0, 1, 0, 1, 0” is input to the inverting circuit 20 from the highest order. When this gradation data is expressed in decimal, it becomes “170”. Then, a signal level of “1, 0, 1, 0, 1, 0, 1, 0” is input to each of the input terminals B0 to B7.

  Here, when the selection signal input to the switch unit 22 is low, the switch elements S0 to S7 are connected to the terminals S0a, S1a, S2a, S3a, S4a, S5a, S6a, and S7a on the upper side of the drawing. The signal levels of “1, 0, 1, 0, 1, 0, 1, 0” are output to the output terminals O0 to O7. Accordingly, the parallel data output from the output terminals O0 to O7 to the PDP panel 13 is data in which each bit is “1, 0, 1, 0, 1, 0, 1, 0” from the top. That is, when the selection signal input to the switch unit 22 is low, the inverting circuit 20 outputs the same gradation data to the subsequent PDP panel 13 without processing the input gradation data. .

  On the other hand, when the selection signal input to the switch unit 22 is high, as shown in FIG. 4, each switch element S0 to S7 has terminals S0b, S1b, S2b, S3b, S4b, In order to connect to S5b, S6b, and S7b, levels of “0, 1, 0, 1, 0, 1, 0, 1” are input to the output terminals O0 to O7 of the P / S converter 24. Become. Accordingly, the parallel data output from the output terminals O0 to O7 to the PDP panel 13 is data in which each bit is “0, 1, 0, 1, 0, 1, 0, 1” from the most significant. That is, when the selection signal input to the switch unit 22 is high, the inverting circuit 20 rearranges the input grayscale data in ascending order of the bit order and rearranges the same on the subsequent PDP panel 13. Outputs gradation data. At this time, the gradation data input to the PDP panel 13 is expressed as “85” in decimal.

(3) Signal switching process:
FIG. 5 shows the flow of signal switching processing. In the figure, the selection signal is set to low in step S100. That is, in normal display, since it is necessary to reproduce an image faithfully to the input video signal, in principle, the microcomputer 14 outputs a low selection signal and the inversion circuit 20 does not process the gradation data. Set to In step S110, an instruction input for executing the burn-in prevention mode is accepted, and the microcomputer 14 continues to output the low selection signal unless the instruction is accepted. Note that the microcomputer 14 receives an instruction input from the user via the remote control I / F 14b or the operation panel 14a.

  On the other hand, when an instruction input for executing the burn-in prevention mode is accepted in step S110, step S120 is executed. In step S120, it is confirmed whether or not the current video source via the A / D conversion circuit 12a1 is displayed on the PDP panel 13. Since the microcomputer 14 manages the operation of the selector circuit 15 and the flash memory slot 14e, it is possible to confirm what image source is displayed on the PDP panel 13.

  Here, the television mode in which the display of the PDP panel 13 is performed based on the video signal input from the tuner 11 and the display of the PDP panel 13 is performed based on the video signal input from the external input terminals 15a to 15c. In the video input mode, the video source that has passed through the A / D conversion circuit 12a1 is displayed on the PDP panel 13, so step S130 is executed. On the other hand, in the digital camera mode in which the display of the PDP panel 13 is performed based on the digital image data read from the flash memory slot 14e, a video source that does not pass through the A / D conversion circuit 12a1 is displayed on the PDP panel 13. Therefore, step S100 is executed. That is, the user's instruction is ignored and the normal display is continued.

  In step S130, the microcomputer 14 outputs a high selection signal. As described above, when the microcomputer 14 outputs a high selection signal, the gradation data rearranged in the order from the lowest bit order is input to the PDP panel 13. As a result, a random image can be displayed on the PDP panel 13 without depending on the video signal originally input via the A / D conversion circuit 12a1. When the digital video signal is generated by the A / D conversion circuit 12a1, a slight random error occurs in the gradation generated by a sampling error or the like. Of course, since this is a slight error with respect to the entire gradation, this random error does not deteriorate the normal display. This random error appears in the lower bits in the gradation data.

  For example, in the decimal number, when there is an error of “1” above and below “171”, the binary gradation data is “1, 0, 1, 0, 1, 0, 1, 0” (= 170) or “1,0,1,0,1,0,1,1” (= 171) or “1,0,1,0,1,0,0,1” (= 169) . In these gradation data, the upper bits are not different, while the lower bits are greatly different. When these gradation data are rearranged in ascending order of the bit order by the inverting circuit 20, the gradation data are “0, 1, 0, 1, 0, 1, 0, 1” (= 85) and “ “1,1,0,1,0,1,0,1” (= 106) and “1,0,0,1,0,1,0,1,” (= 149). In other words, a large gradation change can be caused by replacing the low-order bits that greatly differ due to the random error of the A / D conversion circuit 12a1 with the high-order bits that greatly contribute to the magnitude of the gradation.

  Accordingly, the discharge intensity in each cell of the PDP panel 13 can be greatly varied in accordance with a random error that occurs randomly due to the characteristics of the A / D conversion circuit 12a1. For example, even when a video signal composed of a single color image is input, discharge is performed at a gradation that greatly reflects a different random error for each cell of the PDP panel 13. Therefore, each cell of the PDP panel 13 can be discharged without deviation for each position, and the PDP panel 13 can be prevented from being burned. Even when a still image is input, the A / D conversion circuit 12a1 changes the random error over time, so that each cell discharge intensity can be changed over time. As described above, by randomizing the discharge intensity of each cell of the PDP panel 13 in terms of position and time, the temperature difference between the cells can be eliminated and the burn-in of the PDP panel 13 can be prevented.

  In step S130, the microcomputer 14 starts outputting a high selection signal and starts measuring time with the timer 14f. In step S140, when it is confirmed that 30 seconds have elapsed since the execution of step S130, the process returns to step S100, and the microcomputer 14 outputs a low selection signal. In other words, the normal image display is restored after the burn-in prevention is completed. It should be noted that since the time until burn-in prevention is completed differs depending on the characteristics of the PDP panel 13, it is desirable to set a time suitable for the characteristics of the PDP panel 13.

(4) Modification:
As described above, by rearranging the gradation data in ascending order of the bit order in the inverting circuit 20, random image data can be created and burn-in prevention can be realized. However, when creating random image data, it is not always necessary to rearrange the gradation data in ascending order of bit order. For example, an inverting circuit 120 as shown in FIG. 6 may be applied. In the figure, the inverting circuit 120 has a circuit configuration in which the least significant bit and the most significant bit are switched when the selection signal is high. Even in this case, since the most significant bit that greatly contributes to the magnitude of the gradation can be replaced with the least significant bit having randomness, a large randomness can be imparted to the gradation.

  In FIG. 6, ten input terminals I0 to I9 and ten output terminals O0 to O9 are provided, respectively, and can be handled as 10-bit gradation data. Various bits of gradation data can be considered, and an inversion circuit corresponding to the number of bits may be formed. Further, the inversion circuit 20 may be disposed at a stage subsequent to the A / D conversion circuit 12a1, and need not be disposed immediately before the PDP panel 13. Therefore, for example, the inverting circuit 20 may be interposed between the digital signal processing circuit 12a and the adjustment circuit 12b. Further, although the example in which the inverting circuit 20 is interposed in the section in which the gradation data is transferred in parallel, the inverting circuit 20 may be arranged in the section in which the gradation data is serially transferred. The function similar to that of the inverting circuit 20 may be performed by software.

  Furthermore, the present invention is not limited to a television, and can be applied to any display device that inputs a video signal and displays an image on a PDP panel. That is, if the reversing means is provided before the PDP panel, image data having randomness can be output to the PDP panel to prevent the PDP panel from being burned. Even when image data created by an optical device such as a digital camera is displayed on such a display device, a random image can be displayed according to the present invention.

  That is, even when the display device itself having the reversing means does not include the A / D conversion means, the A / D conversion means included in the optical device such as a digital camera is an alternative, so that the image data such as the digital camera is displayed. A random image can be created from the image. Therefore, it is not always necessary to prevent burn-in prevention in the digital camera mode as in the above-described embodiment. However, when displaying still image data of a digital still camera or the like, the random error does not change with time, so the randomness is slightly inferior compared with the case where the A / D conversion means is used.

(5) Summary:
As described above, in the present invention, the inverting circuit 20 replaces the most significant bit that contributes most to the magnitude of the gradation, with the least significant bit having the most randomness in the gradation data. As a result, the gradation data processed by the inverting circuit 20 has randomness. Therefore, it is possible to display a random image on the PDP panel 13, uniform the temperature distribution of each cell, and eliminate burn-in.

1 is a schematic block diagram of a PDP television according to the present invention. It is a circuit diagram of an inverting circuit. It is operation | movement explanatory drawing of an inverting circuit. It is operation | movement explanatory drawing of an inverting circuit. It is a flowchart which shows the flow of a signal switching process. It is a circuit diagram of the inversion circuit concerning a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Plasma display (PDP) television 11 ... Tuner 12 ... Video signal processing circuit 12a1 ... A / D conversion circuit 13 ... Plasma display (PDP) panel 14 ... Microcomputer 14a ... Operation panel 14c ... ROM
14d ... RAM
14e ... Flash memory slot 14f ... Timer 15 ... Selector circuits 15a-15c ... External input terminal 20 ... Inverting circuit 21 ... Crossing circuit 22 ... Switch units B0-B7 ... Input terminals O0-O7 ... Output terminals S0-S7 ... Switch elements

Claims (8)

In a plasma television equipped with a plasma display panel that inputs a digital video signal and reproduces an image on a display surface,
A channel selection means for extracting a desired signal from a broadcast radio wave and generating an analog video signal;
A / D conversion means for converting the analog video signal into a digital video signal;
A predetermined operation by a user is accepted in a state of being interposed between the A / D conversion means and the plasma display panel and the plasma display panel receiving the digital video signal output from the A / D conversion means. And a reversing means for rearranging the data representing the gradation of the digital video signal in ascending order of bit order until a predetermined time elapses. In a plasma display device having a plasma display panel that inputs a digital video signal and reproduces an image on a display surface,
A plasma display device comprising: inversion means for replacing the most significant bit of the data representing the gradation of the digital video signal with the least significant bit according to a predetermined condition. A / D conversion means for converting an analog video signal into a digital video signal,
3. The plasma display device according to claim 2, wherein the inversion means is interposed between the A / D conversion means and the plasma display panel.   The inversion means replaces the most significant bit of the data representing the gradation of the digital video signal with the least significant bit in a state where the plasma display panel receives the digital video signal output from the A / D conversion means. The plasma display device according to claim 3.   3. The reversing device according to claim 2, wherein the inversion means ends the replacement when a predetermined time elapses after the most significant bit of the data representing the gradation of the digital video signal is replaced with the least significant bit. Item 5. The plasma display device according to any one of items 4 to 4.   6. The inversion means replaces the most significant bit of the data representing the gradation of the digital video signal with the least significant bit when a predetermined operation by the user is accepted. A plasma display device according to claim 1.   The A / D conversion means converts the analog video signal input from the channel selection means for extracting a desired signal from a broadcast radio wave and generating an analog video signal into the digital video signal. The plasma display device according to claim 6.   The plasma display device according to any one of claims 2 to 7, wherein the inversion means rearranges data representing gradations of the digital video signal in ascending order of bit order.

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