JP2001175212A - Display sticking preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make sticking at a masked part and its boundary inconspicuous when the display having a masked part is performed with a video signal having the masked part and a video signal having a different aspect ratio. SOLUTION: This device is provided with a luminance control part for controlling signal levels of a video part, a masked part and the boundary of the masked part, a deciding part deciding the difference between the display time and the accumulated time of the masked part and a predetermined time, a setting part for setting the signal level of the masked part and the mask position of the masked part. Moreover, in this device, prescribed ranges of the front side and the rear side of the boundary are divided into prescribed steps and the display for every step is made to be smoothing display in which luminance is stepwise decreased from the center to the outside of the boundary by the luminance control part and, also, the setting part is made to set the signal level and the mask position of the masked part to a signal level which hardly generates the sticking and a mask position where hardly generates the sticking by the decision of the deciding part.

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 device, and more particularly to a display burn-in prevention device for controlling a luminance level and a display position of a mask portion of a screen, and particularly preventing a burn-in at a boundary of the mask portion. Related to the device.

[0002]

2. Description of the Related Art In recent years, the screens of displays such as televisions and PCs have become wider, and a large number of wide displays have been sold in the market. At the same time as displaying a 16: 9 video source on a wide display, the number of cases of viewing a 4: 3 screen by adding a black level mask portion to the left and right or converting the screen to a wide screen is increasing. In a display such as a plasma display panel (PDP), a phosphor is used to emit light in the same manner as in a CRT or the like. It was noticeable. The image sticking due to the difference in brightness appears more in proportion to the use time as the brightness increases and when the same screen is displayed for a long time. In general, in the case of moving images, the screen is used on average, so there is little danger of burning.However, if screens with different aspect ratios are displayed and the left and right mask parts are used for a long time, another screen is switched. When displayed, there is a problem that this mask portion becomes noticeable as a step.

FIG. 4 shows an input image having an aspect ratio of 4: 3 as one image.
It is explanatory drawing which shows the conventional example at the time of displaying on the display screen of 6: 9. In the input video signal having an aspect ratio of 4: 3 in (1), a mask portion is provided before and after the video signal as in (2), and the signal level L0 of the mask portion is set to a gray level.
The screen display as shown in (3) is performed while the video signal level LY remains input. By setting the mask portion to the gray level in this way, burn-in is reduced, but the brightness difference at the boundary between the mask portion and the video portion may be sharp, and when the same image is displayed for a long time. Results in a step. The human eye is not concerned about the gradual change in brightness, but it recognizes even the smallest difference in brightness between adjacent pixels and makes it noticeably surprising. Also had the problem of becoming A method of periodically moving the screen has also been proposed, but simply moving the screen was sometimes insufficient.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is intended to detect a video signal having a mask portion or a video signal having a different aspect ratio and perform display having the mask portion. It is another object of the present invention to provide a display sticking prevention device which makes sticking at the boundary inconspicuous.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention divides a display screen into a video portion and a mask portion where a video is not displayed, and displays an effective video signal on the video portion. A display mode for displaying a predetermined burn-in reduction signal for reducing burn-in on the mask portion in the same screen mode, in order to control the signal levels of the image portion, the mask portion and its boundary. A brightness control unit, a clock unit that measures the mask unit display time and the accumulated time of the mask part, a storage unit that stores the mask unit display time and the accumulated time, and the mask unit display time and the accumulated time. A determination unit for determining a difference from a predetermined time; and a setting unit for setting a signal level of the burn-in reduction signal and the mask position, before and after the boundary. The predetermined range is divided into predetermined steps, the display of each said step, with a smoothing display stepwise decreasing brightness from the center to the outside of the boundary by the brightness control unit, the determination of the determination unit,
The setting unit sets the signal level of the burn-in reduction signal and the mask position to a signal level and a position at which burn-in is difficult.

The image processing apparatus further comprises an APL detecting section for detecting an average luminance of the image portion, and sets a signal level of the burn-in reduction signal based on an average luminance of all image portions detected by the APL detecting section.

The signal level of the burn-in reduction signal is
It is set based on the average luminance of a line or a pixel in contact with the boundary detected by the APL detection unit.

The signal level of the burn-in reduction signal is
A predetermined black level or a predetermined gray level is set.

The signal level of the burning reduction signal is
It can be selected or set from the input unit.

The predetermined step is divided into a line unit or a pixel unit.

Further, each luminance difference between the predetermined steps is a value obtained by equally dividing the difference in signal level between the video section and the mask section by the number of steps.

Further, a plurality of the mask positions are provided on the left and right or up and down from the standard position, and the mask positions are sequentially moved each time a predetermined continuous time of the mask section display time elapses.

Further, the mask position is sequentially moved every time the video signal or the screen mode is switched.

Further, the mask position is sequentially moved at a predetermined time.

Further, the movement of the mask position can be selected from movement or movement inhibition by a command from an input unit.

Further, the storage unit stores the accumulated time of the mask display time for each of the mask positions, and moves the mask position to the same mask position having the smallest accumulated time when the mask position is moved.

Further, the storage unit accumulatively stores a display time level product which is a product of the mask display time and the signal level of the burn-in reduction signal for each of the mask positions, and stores the mask position in the same mask position. At the time of movement, it moves to the same mask position having the same display time level product.

Further, the timer unit measures the energizing time, and stores the energizing time in the storage unit. When the ratio between the energizing time and the mask display time exceeds a predetermined value,
The determination unit increases the signal level of the burn-in reduction signal by a predetermined level.

Further, the screen mode has a maintenance mode. During the maintenance mode, it is possible to select an inverted display in which the video portion is at a black level and the mask portion is at a white level.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a main part of a display sticking prevention device for explaining one embodiment of the present invention. A description will be given based on FIG. Input composite video signal, Y / C video signal that separates luminance signal and chrominance signal, component video signal such as Y, Pb, Pr, and input video signal such as R, G, B video signal of personal computer etc. and input synchronization The signal is subjected to signal processing such as input switching, color demodulation, and color separation / processing by the input signal processing unit 1 and then branched. One of the signals is separated and synchronized by the synchronization signal processing unit 2 to generate a timing and a clock from the separated synchronization signal. The generated timing and clock are supplied to each unit. The other signal output from the input signal processing unit 1 is A / D (Analog D
The digital signal is converted by a digital converter 3, and digital signal processing such as gamma processing and scanning line conversion is performed by a signal processing unit 4.

The output branched from the A / D 3 is input to an aspect ratio detection unit 5, which determines the type of the input video signal from the horizontal synchronization frequency, the vertical synchronization frequency, and the clock of the input video signal, and validates the screen area of the video signal. The signal component and the invalid component are monitored, and the aspect ratio is detected. When the input signal processing unit 1 selects an S terminal to which a Y / C signal obtained by separating a luminance signal and a color signal is input, the aspect ratio information included in the color signal of the selected Y / C signal, For example, when an interface signal with a digital tuner is selected, the aspect determination unit 6 determines the aspect ratio information and the like included in the control signal paired with the selected video signal. The output of the signal processing unit 4 is input to the aspect ratio conversion processing unit 7, and when the aspect ratio conversion is required according to the detection result of the aspect ratio detection unit 5 and the result determined by the aspect determination unit 6, and the screen mode. Then, an aspect ratio conversion process is performed to match the aspect ratio of the display screen.
The aspect ratio conversion processing unit 7 has a frame memory and a line memory (not shown), and performs parallel storage and processing of the screen. The display position of the video signal subjected to the aspect ratio conversion processing is controlled by the display position control unit 8 so that the effective screen becomes the center of the display screen, and the output control unit 9 adds an on-screen signal, sets a signal level, Signals are interfaced in accordance with the display unit and displayed on the display unit 10. The display unit 10 is 16: 9 in this embodiment.
Is a wide plasma display having a screen.

In the case of an input signal having an aspect ratio different from that of the display screen, an insertion position of the mask portion is set by the mask position setting section 11 according to the screen. When the display screen is 16: 9 and the input signal is 4: 3, the invalid screen is a mask part on the left and right. When the display screen is 4: 3 and the input signal is 16: 9, the invalid screen is a mask part on the upper and lower sides. Insert A black level, a gray level,
The signal level such as the average luminance of the effective screen is given, and the output control section 9 superimposes the signal on the video signal and outputs it. The signal branched from the A / D 3 is an average value of the luminance of the effective screen of the video signal, the average value of the luminance of the upper and lower lines, and the average value of the luminance of the left and right vertical lines in the APL detector 13 using a frame memory or a line memory. Are detected, and the detected value is input to the control unit 14. The control unit 14 is, specifically, a CPU
The synchronization information and timing information from the synchronization signal processing unit 2, the detection result by the aspect ratio detection unit 5, the detection result by the aspect ratio discrimination unit 6, and the like are also input. The respective units perform predetermined settings and operations from information such as commands, signal levels, setting values such as mask positions, etc., and the determination result of the determination unit 16 for determining whether the mask display time has exceeded a predetermined time. To send control commands to control. Therefore, the control unit 14
Is also connected to a clock unit 17 having a function of clocking the time, the mask display time and the accumulated time, and a storage unit 18 for storing set values and a clock result of the clock unit 17. If the display time exceeds a predetermined time, the setting unit 19 makes the signal level of the burn-in reduction signal difficult to burn, or selects and sets the mask position to an optimum position, and performs control for preventing burn-in. I do.

Next, the operation of the embodiment of the display sticking prevention device according to the present invention will be described with reference to FIG. Figure 2 is 16: 9
2 shows an example of a signal waveform and a screen display state when a 4: 3 video signal is displayed on a plasma display having a display screen of FIG. In FIG. 2, (1) shows the signal waveform of the NTSC video signal in the horizontal synchronization period when the input signal is 4: 3. This signal is determined to be a 4: 3 image by the aspect ratio detection unit 5 from the fact that it is a full image and the relationship between the horizontal synchronization frequency and the vertical synchronization frequency. This video signal is Y
In the case of / C input, the aspect ratio information is superimposed on the color signal as a DC component. In this case, the aspect ratio determination unit 6 determines the aspect ratio. A screen mode set by the aspect ratio information and a command from the input unit 15, that is, a wide mode in which a 4: 3 image is evenly extended left and right on a 16: 9 display screen, and a center portion is 4: 4 The determination unit 16 determines whether the mode is a wide mode in which both sides are extended, a normal mode in which a mask portion is provided on both sides and a 4: 3 screen is displayed in the center, or a zoom mode in which a cinema screen or the like is enlarged and displayed. The respective aspect ratio conversion processes are performed by the aspect ratio conversion processing unit 7 and the display unit 1
The control unit 14 controls each unit so that 0 is displayed.

When a 4: 3 image is displayed on a 16: 9 display screen, for example, a gray signal is superimposed on a mask portion on both sides as shown in (2), and a 4: 3 image is formed in a central portion. One boundary between the mask portion and the center portion has a signal waveform whose luminance is limited so that the luminance increases stepwise and the other decreases stepwise. The display screen performs smoothing display at the boundary as shown in (3). The boundary portion is divided into five in pixel units, and the signal level of each of the five pixels is obtained by dividing the difference between the maximum level of the image and the level of the mask portion into five levels from Step 0 to Step 5.
Increase or decrease step by step. For example, if the maximum luminance of the video part is 8
When expressing in bit gradation, the maximum is 255 gradations, and L
Assuming that the signal level of 0 is 15 gradations, if the difference 240 gradations is divided into 5 equal parts, one step becomes 48 gradations. Therefore, gradations 15, 63, 111, and 15 are sequentially provided from L0.
The control of the luminance limiting unit 12 is performed so that the levels 9, 207 and 255 become the maximum levels that can be obtained in the respective steps.

The signal level L0 of the mask portion is a signal level of any one of the black level, the gray level, the average luminance of all the image portions detected by the APL detecting section 13, or the average luminance of the pixels of the vertical line at the boundary. Selection from the input unit 15 is enabled. Generally, the black level mask portion is most difficult to burn, but since the initial luminance is maintained, the luminance difference is most conspicuous, and the gray level mask portion becomes conspicuous, but the luminance difference is reduced. When the mask portion is the average luminance of all video portions, the APL of a normal moving image is 50
%, The mask portion becomes considerably conspicuous, but the luminance difference is the smallest. The same effect can be obtained when the average luminance of each of the vertical lines of the boundary part where the mask part is on the left and right, or the average luminance of the horizontal line of the boundary part on the screen where the mask part exists above and below is the level of the mask part. Connection can be improved. When any of the average luminances is used as the level of the mask portion, the luminance of the mask portion changes. Therefore, the detection time constant is increased, and the level is set to, for example, 1/3 of the average luminance. The change in luminance may be suppressed by a method. Decreasing the brightness of the mask part is disadvantageous for printing, but in any case, by using the smoothing display of the border together, the step at the border is eliminated and the burning is less noticeable, so the user can select the desired mask part. The level can be set, and it is possible to avoid a sense of incongruity. The signal of the mask portion gives priority to the user's selection, but when the determination unit 16 determines that the mask display time exceeds a predetermined limit, the setting unit 19 increases the level. For this reason, when the mask portion is set to the black level, if the usage time is short, it is left as it is, and if it is long, the signal level is increased stepwise according to the usage time, so that burn-in or a luminance difference can be prevented. There are two methods of smoothing the boundary: one is to limit the luminance of the video part in a stepwise manner, and the other is to increase the level of the mask part in a stepwise manner. The same effect can be obtained by either or a combination of both. Can be.

In this embodiment, in addition to the smoothing display of the boundary, the burn-in is further prevented by adaptively moving the mask position or the effective screen position.
FIG. 3A shows an example in which a 4: 3 screen is displayed on a 16: 9 display screen. As shown in the figure, the boundary of a normal mask portion is located at P0. In addition, five pixels P-2, P-1, P0, P + 1, and P + 2 are provided to allow two pixels to move left and right. FIG. 3B shows an example in which a 16: 9 screen is displayed on a 4: 3 display screen. Similarly, the boundary of a normal mask portion is located at P0. In addition, P-2, P-
Five positions of 1, P0, P + 1 and P + 2 are prepared.
The timer 17 measures the mask display time for each position in units of one minute, and stores the accumulated display time in the storage 18. If the mask display time exceeds a predetermined time set by the input unit 15, for example, 30 minutes, the position is shifted by one position. The position is moved by shifting the prepared positions in order. In addition, the position may be moved at the time of input signal switching, at the time of screen mode switching, or at a specific time. The movement method can be selected by setting of the input unit 15, and the movement can be prohibited. In any case, the determination unit 16 monitors the setting from the input unit 15 and the accumulated display time for each position. If a difference of more than a predetermined difference occurs in the accumulated display time, the judgment unit 16 determines the accumulated display time. The lowest position selection is prioritized.

The display time level product, which is the product of the accumulated display time and each signal level, is cumulatively stored for each position. The decrease in luminance is inversely proportional to the display time and the display luminance, but the display time level product enables more accurate monitoring of the burning state. For example, if the determination unit 16 determines that the display time level product exceeds the difference from a predetermined value, it means that the burn-in state is considerably noticeable. Is changed so that settings are made to improve image sticking. That is, when the mask portion is at the black level, the luminance level of the mask portion is raised by a predetermined step,
In the case of the white level, the luminance level is lowered by a predetermined step. Generally, there is little problem if the display time level product of the video portion and the mask portion is about 10% or less, and the brightness of the mask portion can be freely selected. For example, there is a method of positively reducing the difference, such as performing white display. Further, the timer 17 measures the power-on time, measures the power-on time from power-on to power-off, and stores the cumulative power-on time. By comparing the energizing time and the display time, the usage ratio of the mask display time of the display at that time can be known. By comparing the cumulative energizing time and the cumulative time of the mask part display time, the cumulative use time of the mask part can be calculated. You can see the usage ratio. Therefore, the magnitude of the printing can be predicted based on the magnitude of the usage ratio of the mask portion. If the use ratio of the mask portion is high, the burning is considered to be progressing, so that it is possible to select to display a maintenance recommendation message recommending maintenance for eliminating the burning. For message display, there are methods such as blinking of an LED and displaying a message display on a screen for a certain period of time when the power is turned on.

Next, the maintenance mode will be described. The screen mode of the display sticking prevention device of the present invention has a maintenance mode for performing maintenance, and performs information display and operation necessary for maintenance. First, in order to effectively eliminate the burn-in of the mask portion, there is an inverted display pattern in which the image portion is set to the black level and the mask portion is set to the white level, and it is possible to select the inverted display in the maintenance mode. This rests the video part,
Since only the mask portion emits light with high luminance, the luminance difference can be reduced. In addition, the display screen has a display pattern in which the entire screen is displayed in white, and display in the maintenance mode can be selected. By performing the white display, the luminance of a portion where the display time is short is high, and the luminance of a portion where the display time is long is low. By combining these patterns, it is possible to produce the effect of first reducing a large luminance difference by inverting display of luminance and then performing white display to smooth the whole.

In the maintenance mode, the power supply time, the mask display time, and the time level product which is the product of the mask display time and the luminance level may be displayed. As a result, the actual operation status can be confirmed, and from this content, it is possible to refer to the life of the display, the method of use, and the like, and to confirm the necessity of displaying the burn-in elimination pattern. Further, in the present apparatus, the program operation is enabled according to the time and the passage of time, and the display of the prevention of burning is performed in the program operation. For example, after driving 8 hours a day, 1
A maintenance period of time is provided, and 30 minutes are highlighted, 3
White display may be performed for 0 minutes. This way, especially when used at a time determined by business use,
Effective seizure prevention and elimination can be performed. The maintenance period may be performed regularly every day, once a week, or once a month. As described above, in the embodiment of the present invention, an example in which screens having different aspect ratios are displayed has been described. However, the present invention is not limited to this embodiment. The same preventive measures can be applied to a screen having a mask portion on the left, right, top and bottom. Although the burning of the mask portion expressed in the present embodiment is a meaning of a luminance difference, it is a resolvable phenomenon different from burning in a strict sense. It is treated.

[0030]

As described above, according to the display burn-in prevention device of the present invention, it is possible to prevent the device from having a different aspect ratio.
When displaying a screen divided into a video portion and a mask portion in which no video is displayed, a brightness control unit for controlling a signal level of the video portion, the mask portion and its boundary, and a mask portion display time and an accumulated time are predetermined. And a setting unit for setting the signal level of the mask portion and the mask position, and divides a predetermined range before and after the boundary into predetermined steps. The display for each step is changed to a smoothing display in which the luminance is reduced stepwise from the center of the boundary to the outside by the luminance control unit, and the setting unit determines the signal level and the mask position of the mask part by the determination of the determination unit. Is set to a signal level and a position at which image sticking is difficult, so that it is possible to provide a display image sticking prevention device in which image sticking at a mask portion and its boundary is not noticeable.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram for explaining a relationship between a signal and a screen in the display sticking prevention device of the present invention.

FIG. 3 is an explanatory diagram for explaining screen movement in the display burn-in prevention device of the present invention.

FIG. 4 is an explanatory diagram for explaining a relationship between a signal and a screen in a conventional example of the display burn-in prevention device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input signal processing part 2 Synchronous signal processing part 3 A / D 4 Signal processing part 5 Aspect ratio detection part 6 Aspect ratio discrimination part 7 Aspect ratio conversion processing part 8 Display position control part 9 Output control part 10 Display part 11 Mask part position Setting unit 12 Brightness control unit 13 APL detection unit 14 Control unit 15 Input unit 16 Judgment unit 17 Clock unit 18 Storage unit 19 Setting unit

Claims (15)

[Claims] A display screen is divided into an image portion and a mask portion in which no image is displayed, and a screen mode for displaying an effective image signal on the image portion is provided. In the screen mode, burn-in on the mask portion is reduced. A display burn-in prevention device for displaying a predetermined burn-in mitigation signal for controlling a signal level of the image portion, the mask portion and a boundary thereof, and a mask portion display time and accumulation of the mask portion. A timer that measures time, a storage unit that stores the mask unit display time and the accumulated time, and a determination unit that determines a difference between the mask unit display time and the accumulated time and a predetermined time. A setting unit for setting a signal level of the burn-in reduction signal and the mask position, dividing a predetermined range before and after the boundary into predetermined steps, The display is a smoothing display in which the luminance decreases stepwise from the center of the boundary to the outside by the luminance control unit, and according to the determination by the determination unit, the setting unit determines the signal level of the burning reduction signal and the mask. A display burn-in prevention device, wherein the position is set to a signal level and a position where it is difficult to burn. 2. An average for detecting an average luminance of the image portion.
2. The display according to claim 1, further comprising an age picture level (hereinafter, referred to as APL) detection unit, wherein a signal level of the burn-in reduction signal is set based on an average luminance of all image portions detected by the APL detection unit. Anti-seizure device. 3. The signal level of the burn-in mitigation signal is set from an average luminance of a line or a pixel in contact with the boundary detected by the APL detection unit.
Display sticking prevention device as described. 4. The display burn-in prevention device according to claim 1, wherein the signal level of the burn-in reduction signal is a predetermined black level or a predetermined gray level. 5. The display burning prevention device according to claim 1, wherein the signal level of the burning reduction signal can be selected or set from an input unit. 6. The display burn-in prevention device according to claim 1, wherein the predetermined step is divided into a line unit or a pixel unit. 7. Each of the luminance differences during the predetermined step is:
7. The display burn-in prevention apparatus according to claim 1, wherein a difference between signal levels of the image portion and the mask portion is a value obtained by equally dividing the difference by the number of steps. 8. The apparatus according to claim 1, wherein a plurality of the mask positions are provided on the left and right or up and down from a standard position, and the mask positions are sequentially moved each time a predetermined continuous time of the mask unit display time elapses. 8. An image sticking prevention device according to any one of claims 7 to 7. 9. The display burn-in prevention apparatus according to claim 1, wherein the mask position is sequentially moved every time the video signal or the screen mode is switched. 10. The display burn-in prevention device according to claim 1, wherein the mask position is sequentially moved at predetermined time intervals. 11. The display sticking prevention device according to claim 1, wherein selection of movement or prohibition of movement of the mask position can be made by a command of an input unit. 12. The storage unit stores the accumulated time of the mask display time for each of the mask positions, and when the mask position is moved, moves the mask position to the same mask position having the least accumulated time. The display sticking prevention device according to any one of claims 1 to 11, wherein: 13. The storage unit accumulates and stores a display time level product, which is a product of the mask display time and the signal level of the burn-in reduction signal, for each of the mask positions. 13. The display burn-in prevention device according to claim 1, wherein the mask position is moved to the same mask position having the least display time level product. 14. The timing section measures the energization time, and stores the energization time in the storage section. If the ratio between the energization time and the mask display time exceeds a predetermined value, the setting section sets 14. The display burning prevention device according to claim 1, wherein the signal level of the burning reduction signal is increased by a predetermined level. 15. The screen mode includes a maintenance mode, and during the maintenance mode, the display screen is a reverse display in which the video portion has a black level and the mask portion has a white level, or a full-screen white display. 15. The display burn-in prevention device according to claim 1, wherein the device can be selected.