JP2008070683A - Image persistence suppression device, spontaneous light display device, image processing apparatus, electronic equipment, image persistence suppression method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problems, in a spontaneous light display device, that in the case of the conventional method, there is a need for continuously monitoring the deterioration state of each pixel, and when a screen size is upsized, the amount of operations and scale are upsized. <P>SOLUTION: The image persistence suppression device comprises (a) an average gray scale value calculation section which calculates the average gray scale value of the video signal inputted in a unit frame or between a plurality of the frames, (b) the gay scale difference calculation section which calculates the two average gray scale values calculated relating to the two calculation periods set so as to avoid superposition of the calculation periods, and (c) a contrast controller which reduces the contrast difference on a display screen when the differential value is smaller than a determined threshold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The invention described in this specification relates to a technique for suppressing the progress of the burn-in phenomenon of a self-luminous display device. The invention proposed by the inventors has aspects as a burn-in suppression device, a self-luminous display device, an image processing device, an electronic device, a burn-in suppression method, and a computer program.

  The self-luminous display element has a characteristic that the light emission luminance decreases in proportion to the light emission amount and time. This decrease in light emission luminance is caused by deterioration in light emission characteristics. As the deterioration of the light emission characteristics proceeds, the luminance gradually decreases even under the same driving conditions, and the initial luminance cannot be maintained.

  By the way, the decrease in emission luminance generally does not proceed uniformly, and the emission characteristics deteriorate within the screen. This is because display contents are not uniform. The state in which the variation in luminance deterioration is visually recognized is called “burn-in phenomenon”.

Conventionally, in order to suppress the image sticking phenomenon, it has been considered most preferable to extend the light emitting lifetime of the light emitting element material.
However, even if the light emitting element material has a long light emission life, the occurrence of the image sticking phenomenon cannot be eliminated in principle, and only video signals that are likely to cause image sticking may be input continuously.

Therefore, a mechanism for delaying the occurrence of burn-in or making the generated burn-in inconspicuous has been studied.
JP 2003-228329 A

  Patent Document 1 discloses a method of controlling the light emission of each pixel so that the deterioration characteristics of each pixel are aligned during a period when the display screen is not in use. However, there is no description of measures that can be implemented during use. In addition, it is necessary to continuously monitor the deterioration state of each pixel. When the screen size is increased, there is a problem that the calculation amount and the system scale are increased.

Therefore, the inventor proposes a burn-in suppression device having an average gradation value calculation unit, a gradation difference calculation unit, and a contrast control unit.
Here, the average gradation value calculation unit functions as a processing device that calculates an average gradation value of a video signal input between unit frames or a plurality of frames.

The gradation difference calculation unit functions as a processing device that calculates a difference value between two average gradation values calculated for two calculation periods set so that calculation periods do not overlap.
The contrast control unit functions as a processing device that reduces the contrast difference of the display screen when the difference value is smaller than the determination threshold.

  That the difference value is smaller than the determination threshold means that the screen change is small. On a screen with little change, it is difficult for the user to visually recognize the change in contrast difference. In view of this, on a screen with a small change, the contrast difference is positively reduced to suppress the variation in the deterioration progress rate in the screen.

  The burn-in phenomenon is perceived when a deterioration amount difference of a certain amount or more is generated between neighboring pixels. Therefore, the occurrence of the burn-in phenomenon can be suppressed by reducing the variation in the progress rate of the deterioration amount.

  Furthermore, the burn-in suppression technology proposed by the inventor does not require monitoring of the deterioration state in units of pixels and control of the light emission amount in units of pixels, and the processing load and system scale can be reduced. Therefore, even when the screen size is increased, it is more advantageous than the prior art.

Hereinafter, specific examples of the image sticking suppression technique according to the invention will be described.
In addition, the well-known or well-known technique of the said technical field is applied to the part which is not illustrated or described in particular in this specification.
Moreover, the form example demonstrated below is one form example of invention, Comprising: It is not limited to these.

(A) Form example 1
(A-1) Functional configuration of burn-in suppression device FIG. The burn-in suppression device 1 includes an average gradation value calculation unit 3, a gradation difference calculation unit 5, and a contrast control unit 7.

  The burn-in suppression device 1 determines whether or not the video signal supplied to the display device 11 is a still image video signal, and if it is determined to be a still image video signal, the contrast difference of the entire screen is reduced. It functions as a processing device that variably controls the driving conditions of the display device 11.

The average gradation value calculation unit 3 in this embodiment functions as a processing device that sequentially calculates the average gradation value C _j of the video signal input during the n frame period. Note that the average gradation value calculation unit 3 does not overlap the calculation periods so that the average gradation value C _j
Is calculated.

For example, when the video signal is an existing terrestrial broadcast or digital broadcast, it is desirable that the calculated frame number n is around 6. When n = 6, if the calculation period of C _j is from the nth frame to the (n + 6) th frame, C _{j + 1}
Is calculated from the (n + 7) th frame to the (n + 12) th frame. The reason why the calculation periods are not overlapped is that a change in the screen is easily detected as a change in the average gradation value.

  FIG. 2 shows an internal configuration example of the average gradation value calculation unit 3. The average gradation value calculation unit 3 shown in FIG. 2 includes a unit frame average gradation value calculation unit 21, an average gradation value storage unit 23, and an n frame average gradation value calculation unit 25.

  The unit frame average gradation value calculation unit 21 is a processing device that calculates an average gradation value (APL: average picture level) per frame based on a video signal. The calculation period is from one vertical synchronization signal to the next vertical synchronization signal.

  The average gradation value accumulation unit 23 is a storage area or a storage device that accumulates the average gradation value APL calculated for each frame for m frame periods. For example, it is realized as a semiconductor storage device, a hard disk device, other storage device, or a part of its storage area. In the case of this embodiment, a storage area of 6 frames or more is secured.

The n-frame average gradation value calculation unit 25 calculates the average gradation value C _j of the average gradation value APL for m frames stored in the average gradation value storage unit 23. In the case of this embodiment, the average gradation value APL for 6 frames is added so that the calculation periods do not overlap, and the added gradation value is divided by “6” to obtain the average gradation value C _j within the same period.
Is calculated. FIG. 3 shows an example of calculating the average gradation value C _j .

The gradation difference calculation unit 5 includes the latest average gradation value C _{j + 1} and the previous average gradation value C _j among the average gradation values calculated every m frames (6 frames in this embodiment). It is a processing device that calculates the difference between. The calculated difference value corresponds to a screen change amount.

  The contrast control unit 7 compares the calculated difference value with the determination threshold B to determine whether to execute the contrast difference reduction process, and controls the driving condition of the display device 11 based on the determination result. Process. In the case of this embodiment, the determination threshold B is set to “35 (when the video signal is 8 bits long)”.

  Further, the contrast control unit 7 controls a reference voltage value used in the display device 11. Specifically, a reference voltage value that defines an upper limit value and a lower limit value of an output voltage in a digital / analog converter constituting the data line driver is set as a control target.

That is, the reference voltage value D _b that defines the black level (minimum value), the two reference voltage value D _w which defines the white level (maximum value) and the control target. The contrast difference on the display screen can be reduced by controlling these two reference voltage values D _b and D _w so that the difference between them becomes small.

  When the calculated difference value is larger than the determination threshold B, the contrast control unit 7 determines that the current input image is an image having a large change, and determines that the contrast difference reduction control is unnecessary. At this time, the reduction rate α is set to 0 (zero).

  Here, the reduction ratio α is a value representing the reduction amount of the contrast difference with the contrast difference when the contrast difference is not reduced as 100%. Therefore, the greater the reduction ratio α, the smaller the contrast difference.

Here, since the reduction ratio α is 0 (zero), are both set to the standard value and the reference voltage value D _w which defines the reference voltage value D _b and white level which defines the black level (setpoint).
FIG. 4 shows the input / output relationship when the contrast difference is not reduced.

On the other hand, when the calculated difference value is smaller than the determination threshold B, the contrast control unit 7 determines that the current input image is an image with little change, and executes reduction control of the contrast difference. In the reduction control of contrast differences, the process of determining the reduction ratio α (≠ 0), the reference voltage value D _b corresponding to the determined reduction ratio alpha, and the determination process D _w is performed.

In this case the embodiment, the reference voltage value D _b that defines the black level is determined to a voltage higher by a value corresponding to one half of the reduction ratio α than the standard value.
On the other hand, the reference voltage value D _w which defines the white level is determined to a voltage lower by a value corresponding to half the reduction ratio α than the standard value.

  FIG. 5 shows an input / output relationship when the contrast difference is reduced. Note that the 0% luminance level and the 100% luminance level shown in FIG. 5 respectively correspond to the lower limit value and the upper limit value of the voltage value used when the contrast difference is not reduced.

  Incidentally, when the contrast difference reduction control continues, the contrast control unit 7 used in this embodiment executes a process of gradually increasing the contrast difference reduction rate α until the upper limit value E is reached. FIG. 6 conceptually shows how the contrast difference is gradually reduced as the reduction rate α increases.

(A-2) Configuration of Display Device In the case of this embodiment, the display device is assumed to be an organic EL display that is one of self-luminous display devices.
FIG. 7 shows a functional configuration example of the display device 11. The display device 11 includes a timing generator 31, a data line driver 33, a scan driver 35, a scan driver 37, a power supply voltage source 39, and an organic EL display panel 41.

  The timing generator 31 is a processing device that generates various timing signals necessary for screen display based on a timing signal included in the video signal. For example, a write pulse is generated.

The data line driver 33 is a circuit device that drives the data lines of the organic EL display panel 41. The data line driver 33 is composed of a digital / analog converter that converts a gradation value designating the light emission luminance of each pixel into an analog voltage value and supplies the data line. Note that the reference voltage V _b that defines the black level of the digital / analog converter and the reference voltage V _w that defines the white level are _supplied from the power supply voltage source 39.

  The scan driver 35 is a circuit device that sequentially selects gate lines provided for selecting a horizontal line for writing gradation values. This selection signal is supplied to the organic EL display panel 41 as a write pulse. The scan driver 35 in this embodiment outputs a write pulse for each horizontal line.

  The scan driver 37 is a circuit device that drives a gate line provided for supplying a duty pulse signal. The duty pulse signal here refers to a signal that gives the lighting time length within one frame period.

  FIG. 8 shows an example of the duty pulse signal. FIG. 8A shows a vertical synchronization pulse that gives the maximum duration of the maximum lighting time length. FIG. 8B shows an example of a duty pulse signal. In the case of FIG. 8B, the L level period is the lighting time length within one frame period. In the case of this embodiment, the lighting time is fixed.

The power supply voltage source 39 is a circuit device that generates reference voltages V _b and V _w to be supplied to the data line driver 33 based on the reference voltage values D _b and D _w given from the contrast control unit 7.

  The organic EL display panel 41 is a display device in which organic EL elements are arranged in a matrix. The organic EL display panel 41 is for color display. Accordingly, one pixel (pixel) on the display is composed of pixels (subpixels) corresponding to the three colors of RGB.

FIG. 9 shows a connection relationship between the pixel circuit 43 formed at the intersection of the data line and the selection line and the peripheral circuit.
The pixel circuit 43 includes a switch element T1, a capacitor C1, a current supply element T2, and a lighting period control element T3.

  Here, the switch element T1 is a transistor that controls the capturing (writing) of the voltage value applied through the data line. The voltage value capture timing is given in units of horizontal lines.

  The capacitor C1 is a storage element that holds the acquired voltage value for one frame. By using the capacitor C1, even in the case where the data is written by line sequential scanning, a light emission mode similar to that of the surface sequential scanning is realized.

The current supply element T2 is a transistor that supplies a drive current corresponding to the voltage value of the capacitor C1 to the organic EL element D1.
The lighting period control element T3 is a transistor that controls the lighting time length of the organic EL element D1 within one frame.

  The lighting period control element T3 is arranged in series with respect to the drive current supply path. While the lighting period control element T3 is on, the organic EL element D1 is lit. On the other hand, the organic EL element D1 is turned off while the lighting period control element T3 is turned off. However, in the case of this embodiment, the light emission time length is fixed.

(A-3) Image sticking suppression process Hereinafter, the image sticking suppression operation will be described.
FIG. 10 shows the determination processing operation executed every 6 frames.

First, the burn-in suppression device 1 calculates an average gradation value C _j per six frames in the average gradation value calculation unit 3 (S1).
Next, the burn-in suppression device 1 determines whether the difference between the previous average gradation value C _j and the latest average gradation value C _{j + 1} is equal to or greater than the determination threshold B (S2).

  If a positive result is obtained in this determination process, the burn-in suppression device 1 controls the contrast difference reduction process parameter to be off (S3). On the other hand, if a negative result is obtained in this determination process, the burn-in suppression apparatus 1 controls the contrast difference suppression process parameter to be on (S4).

Thereafter, the burn-in suppression device 1 executes a contrast difference reduction process based on the reduction process parameter (S5).
FIG. 11 shows a detailed example of the contrast difference reduction processing operation. First, the image sticking suppression apparatus 1 confirms a reduction process parameter for contrast difference (S11).

Next, the image sticking suppression apparatus 1 determines whether or not the reduction processing parameter is ON (S12).
If the determination result is a negative result, the burn-in suppression device 1 sets the reduction rate α to 0 (zero) (S13).

On the other hand, when the determination result is an affirmative result, the burn-in suppression device 1 determines whether or not the reduction process parameter was in the on state last time (S14).
When a negative result is obtained (that is, in the case of the off state at the previous determination), the burn-in suppression device 1 sets the reduction rate α to 0 (zero) (S15). This is to maintain the contrast difference and stabilize the image quality when the screen is switched.

  On the other hand, when a positive result is obtained (that is, when the ON state continues), the burn-in suppression device 1 sets the reduction rate α to a value obtained by adding the fixed value d to the previous reduction rate α ( S16). That is, the reduction rate α is increased. Since the initial value of the reduction rate α is 0 (zero), the updated reduction rate α is given as a multiple of the fixed value d.

Thereafter, the burn-in suppression device 1 determines whether or not the reduction rate α is equal to or less than the upper limit value E (S17).
Here, when a negative result is obtained, the burn-in suppression device 1 resets the reduction rate α to the upper limit value E (S18).

When the reduction rate α is determined, the burn-in suppression device 1 calculates a reference voltage value D _b that defines the black level and a reference voltage value D _w that defines the white level according to the reduction rate α (S19).
Thereafter, the burn-in suppression device 1 outputs the calculated reference voltage values _Db and _Dw to the display device 11 (S20).

  FIG. 12 shows screen luminance characteristics when the reduction ratio α is 0 (zero). In FIG. 12, the maximum luminance level is set to 1, and the screen luminance characteristics of other gradation values are normalized. FIG. 12 shows the screen luminance characteristics of the three colors of red (R), green (G), and blue (B) normalized to the one with the largest maximum luminance level among the three colors.

FIG. 13 shows screen luminance characteristics when the reduction process is executed (α ≠ 0). The display format is the same as in FIG.
As shown in FIG. 13, the contrast difference between the black level and the white level is reduced. Further, when the input video signal is a still image type video signal, this contrast difference is reduced to a contrast difference defined by the upper limit value E of the reduction ratio α.

(A-4) Effect As described above, when a still image image is displayed, the contrast difference is controlled to be reduced, so that the deterioration amount difference accumulated by the display during the control period is reduced as compared with the original display. can do.

Therefore, by continuing the reduction control of the contrast difference, the period until the burn-in phenomenon is perceived can be delayed. That is, the occurrence of the image sticking phenomenon can be suppressed.
The burn-in suppression device 1 can be realized with a small-scale circuit. For this reason, the burn-in suppression device 1 can be stored in a part of an IC (integrated circuit) mounted on the display device 11.

  For example, in the case of the display device 11 having the device structure shown in FIG. 7, the burn-in suppression device 1 can be mounted on a part of the timing generator 31. In this way, if it is mounted on a part of an existing processing circuit, it is not necessary to change the layout or the mounting space. Therefore, it is advantageous in terms of manufacturing cost. In particular, even when the screen size increases, the amount of calculation and the system scale are small, which is advantageous in terms of manufacturing cost.

(B) Embodiment 2
Here, a case will be described in which the burn-in suppression apparatus 1 has a basic configuration, and a function for optimizing the contrast difference reduction control according to the genre information of the video signal is mounted in the burn-in suppression apparatus. The genre information is described in text format as one of metadata, and is also described as a code value defined by a transmission format or the like.

(B-1) Functional configuration of burn-in suppression device FIG. 14 shows a functional configuration example of this type of burn-in suppression device 51. In FIG. 14, the same reference numerals are given to the portions corresponding to those in FIG. 1.
The burn-in suppression device 51 includes an average gradation value calculation unit 53, a gradation difference calculation unit 5, and a contrast control unit 55.

The basic processing operation of the average gradation value calculation unit 53 is the same as that of the average gradation value calculation unit 3 described in the first embodiment. However, this embodiment differs from Embodiment 1 in that a function for changing the number of frames n that gives the calculation period of the average gradation value C _j based on the genre information attached to the video signal is installed.
FIG. 15 shows an internal configuration example of the normal tone value calculation unit 53. FIG. 15 shows parts corresponding to those in FIG. 2 with the same reference numerals.

  Here, the average gradation value calculation unit 53 includes a unit frame average gradation value calculation unit 21, an average gradation value accumulation unit 23, an n frame average gradation value calculation unit 25, and a calculation period setting unit 57. That is, the configuration other than the calculation period setting unit 57 is the same as that of the first embodiment.

The calculation period setting unit 57 is a processing device that sets the calculation frame number n of the average gradation value C _j based on the genre information. For example, when the genre information represents a video program or scene, the calculated frame number n is set to a small value (for example, n = 2), and when the genre information represents a still image program or scene, the calculated frame number n is set to A large value (for example, n = 8) is set.

  Also, for example, when the genre information represents detailed program information such as drama, music, movie, sports, news, entertainment, etc., it is set to the calculated frame number n associated with each program information. Basically, the calculated frame number n is set to a smaller value for a program with more movement.

  When the processing of the calculation period setting unit 57 is expressed in a flowchart format, the processing procedure shown in FIG. 16 is obtained. First, the genre information acquisition process is executed (S31), and then the calculation frame number changing process is executed (S32). This process is executed every time new genre information is acquired.

Next, the processing operation of the contrast control unit 55 will be described. The basic processing operation of the contrast control unit 55 is the same as that in the first embodiment.
However, the contrast control unit 55 is equipped with a function for setting the determination threshold B based on the genre information.

  For example, when the genre information represents a video program or scene, the determination threshold B is set to a small value (for example, B = 20), and when the genre information represents a still image program or scene, the determination threshold B is set to a large value. (For example, B = 50). Of course, when the genre information represents detailed program information such as drama, music, movie, sport, news, entertainment, etc., the determination threshold B is set to a value associated with each program information. Basically, the determination threshold B is set to a smaller value for programs with more movement.

  When the processing of the contrast control unit 55 is expressed in a flowchart format, the processing procedure shown in FIG. 17 is obtained. First, the genre information acquisition process is executed (S41), and then the determination threshold value B changing process is executed (S42). This process is also executed every time new genre information is acquired.

(B-2) Effects As in this embodiment, the contrast difference reduction processing period and reduction degree are optimized by changing the calculated frame number n and the determination threshold value B in accordance with the genre information that is ancillary information of the video signal. Can be As a result, it becomes possible to minimize degradation of visibility and image quality.

(C) Embodiment 3
Here, a description will be given of a burn-in suppression device that performs a contrast difference reduction process through gradation conversion of a video signal.

(C-1) Functional configuration of burn-in suppression device FIG. 18 shows a functional configuration example of this type of burn-in suppression device 61. In FIG. 18, parts corresponding to those in FIG.
The burn-in suppression device 61 includes an average gradation value calculation unit 3, a gradation difference calculation unit 5, and a contrast control unit 63.

  Here, the contrast control unit 63 compares the difference value calculated by the gradation difference calculation unit 5 with the determination threshold B to determine whether or not to execute the contrast difference reduction process, and the determination result Based on this, a process for gradation conversion of the video signal is executed.

As described above, this embodiment is different from Embodiment 1 in that the contrast difference reduction process is executed through the gradation conversion of the video signal.
In the case of this embodiment, the driving condition of the display device 11 (the reference voltage value defining the black level and the white level of the digital / analog converter) remains a fixed value.

(C-2) Burn-in suppression process Hereinafter, the burn-in suppression operation will be described.
FIG. 19 shows the determination processing operation executed every 6 frames.

First, the burn-in suppression device 61 calculates an average gradation value C _j per six frames in the average gradation value calculation unit 3 (S51).
Next, the burn-in suppression device 61 determines whether the difference between the previous average gradation value C _j and the latest average gradation value C _{j + 1} is equal to or greater than the determination threshold B (S52).

  If an affirmative result is obtained in this determination process, the burn-in suppression device 61 controls the contrast difference reduction process parameter to be off (S53). On the other hand, if a negative result is obtained in this determination processing, the burn-in suppression device 61 controls the contrast difference suppression processing parameter to be on (S54).

Thereafter, the burn-in suppression device 61 executes a contrast difference reduction process based on the reduction process parameter (S55).
FIG. 20 shows a detailed example of the contrast difference reduction processing operation. First, the burn-in suppression device 61 confirms a reduction process parameter for contrast difference (S61).

Next, the burn-in suppression device 61 determines whether the reduction process parameter is on (S62).
If the determination result is a negative result, the burn-in suppression device 61 sets the reduction rate α to 0 (zero) (S63).

On the other hand, if the determination result is a positive result, the burn-in suppression device 61 determines whether or not the reduction process parameter was in the on state in the previous time (S64).
When a negative result is obtained (that is, in the case of the off state at the previous determination), the burn-in suppression device 61 sets the reduction rate α to 0 (zero) (S65).

  On the other hand, when a positive result is obtained (that is, when the ON state continues), the burn-in suppression device 61 sets the reduction rate α to a value obtained by adding the fixed value d to the previous reduction rate α ( S66). That is, the reduction rate α is increased. Since the initial value of the reduction rate α is 0 (zero), the updated reduction rate α is given as a multiple of the fixed value d.

Thereafter, the burn-in suppression device 61 determines whether or not the reduction rate α is equal to or less than the upper limit value E (S67).
If a negative result is obtained, the burn-in suppression device 61 resets the reduction rate α to the upper limit value E (S68).

  When the reduction rate α is determined, the burn-in suppression device 61 performs gradation conversion of the video signal according to the reduction rate α (S69). Specifically, as shown in FIG. 21, when the reduction process is not executed (α = 0), the gradation value at the time of input is output as it is, and when the reduction process is executed (α ≠ 0). First, gradation conversion processing is executed based on conversion characteristics determined according to the reduction ratio α.

The gradation processing here may be performed by arithmetic processing, or may be executed using a conversion table for each reduction ratio prepared in advance. In the case of this example, a conversion table is adopted.
Thereafter, the burn-in suppression device 61 outputs the video signal after gradation conversion to the display device 11 (S70).

(C-3) Effect As described above, the same effect as in the first embodiment can be realized also when the tone conversion of the video signal is performed. In other words, when displaying still images, the contrast difference is controlled to be reduced, so that the deterioration amount accumulated by the display during the control period is reduced compared to the original display, thereby suppressing the progress of the burn-in phenomenon. Can do.

(D) Mounting example Here, the mounting example to the electronic device of the image sticking suppression apparatus mentioned above is demonstrated.

(A) Mounting on a self-luminous display device The burn-in suppression device described above can be mounted in a self-luminous display device 71 as shown in FIG. A self-luminous display device 71 shown in FIG. 22 includes a display device 73 and a burn-in suppression device 75.

(B) Image Processing Device The burn-in suppression device described above can also be mounted on an image processing device 91 as an external device that supplies a video signal to the self-luminous display device 81 as shown in FIG.
An image processing device 91 illustrated in FIG. 23 includes an image processing unit 93 and a burn-in suppression device 95. The processing content of the image processing unit 93 depends on the installed application.

(C) Other mounting examples The burn-in suppression device can be mounted on various electronic devices other than the above-described devices. Note that the electronic device here may be portable or stationary. In addition, the display device does not necessarily have to be mounted on an electronic device.

(C1) Broadcast wave receiving device The burn-in suppression device can be mounted on the broadcast wave receiving device.
FIG. 24 shows a functional configuration example of the broadcast wave receiving apparatus. The broadcast wave receiving apparatus 101 includes a display device 103, a system control unit 105, an operation unit 107, a storage medium 109, a power source 111, and a tuner 113 as main constituent devices.

  Note that the system control unit 105 is configured by, for example, a microprocessor. The system control unit 105 controls the operation of the entire system. The operation unit 107 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 109 is used as a storage area for firmware and application programs in addition to data corresponding to images and videos displayed on the display device 103. The power supply 111 uses a battery power supply when the broadcast wave receiving apparatus 101 is portable. Of course, when the broadcast wave receiving apparatus 101 is a stationary type, a commercial power source is used.

The tuner 113 is a device that selectively receives broadcast waves of a specific channel selected by the user from incoming broadcast waves.
This configuration of the broadcast wave receiving apparatus can be used when applied to, for example, a television program receiver, a radio program receiver, and a portable electronic device equipped with a broadcast wave receiving function.

(C2) Audio Device FIG. 25 is a functional configuration example when applied to an audio device as a playback device.
The audio apparatus 121 as a playback device includes a display device 123, a system control unit 125, an operation unit 127, a storage medium 129, a power supply 131, an audio processing unit 133, and a speaker 135 as main constituent devices.

  Also in this case, the system control unit 125 is configured by, for example, a microprocessor. The system control unit 125 controls the operation of the entire system. The operation unit 127 includes a graphic user interface in addition to a mechanical operator. The display device 123 displays operation information, music information, and the like.

  The storage medium 129 is a storage area for firmware and application programs in addition to audio data. It is also used for storing music data. As the storage medium 129, a hard disk device or the like is used in addition to a semiconductor storage medium.

The power source 131 uses a battery power source when the audio device 121 is portable. Of course, when the audio device 121 is a stationary type, a commercial power source is used.
The audio processing unit 133 is a processing device that processes audio data. The decompression process of the compression-encoded audio data is also executed. The speaker 135 is a device that outputs the reproduced sound.

When the audio device 121 is used as a recorder, a microphone is connected instead of the speaker 135. In this case, the audio processing unit 133 realizes a function of compressing and encoding audio data.
The configuration of the audio device can be used when applied to, for example, a portable music device, a mobile phone, or the like.

(C3) Communication Device FIG. 26 is a functional configuration example when applied to a communication device. The communication device 141 includes a display device 143, a system control unit 145, an operation unit 147, a storage medium 149, a power supply 151, and a communication unit 153 as main constituent devices.

  The system control unit 145 is constituted by a microprocessor, for example. The system control unit 145 controls the operation of the entire system. The operation unit 147 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 149 is used as a storage area for firmware and application programs in addition to data files corresponding to images and videos displayed on the display device 143. The power supply 151 uses a battery power supply when the communication device 141 is portable. Of course, when the communication device 141 is a stationary type, a commercial power source is used.

  The communication unit 153 includes a wireless or wired communication module that transmits / receives data to / from another device. This configuration of the communication device can be used, for example, when applied to a stationary telephone, a cellular phone, and a portable electronic device equipped with a communication function.

(C4) Imaging Device FIG. 27 is a functional configuration example when applied to an imaging device. The imaging apparatus 161 includes a display device 163, a system control unit 165, an operation unit 167, a storage medium 169, a power source 171 and an imaging unit 173 as main constituent devices.

  Note that the system control unit 165 is configured by, for example, a microprocessor. The system control unit 165 controls the operation of the entire system. The operation unit 167 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 169 is used as a storage area for firmware and application programs in addition to data files corresponding to images and videos displayed on the display device 163. The power source 171 uses a battery power source when the imaging device 161 is portable. Of course, when the imaging device 161 is a stationary type, a commercial power source is used.

  The imaging unit 173 includes, for example, a CMOS sensor and a signal processing unit that processes an output signal thereof. The configuration of the imaging apparatus can be used when applied to, for example, a digital camera, a video camera, a portable electronic device equipped with an imaging function, and the like.

(C5) Information Processing Device FIG. 28 is a functional configuration example when applied to a portable information processing device. The information processing apparatus 181 includes a display device 183, a system control unit 185, an operation unit 187, a storage medium 189, and a power source 191 as main constituent devices.

  Note that the system control unit 185 is configured by, for example, a microprocessor. The system control unit 185 controls the operation of the entire system. The operation unit 187 includes a graphic user interface in addition to a mechanical operator.

  The storage medium 189 is used as a storage area for firmware and application programs in addition to data files corresponding to images and videos displayed on the display device 183. The power source 191 uses a battery power source when the information processing apparatus 181 is portable. Of course, when the information processing apparatus 181 is a stationary type, a commercial power source is used.

  This configuration of the information processing apparatus can be used when applied to, for example, a game machine, an electronic book, an electronic dictionary, a computer, a measuring apparatus, and the like. When used in a measuring apparatus, a detection signal of a sensor (detection device) is input to the system control unit 185.

(E) Other Embodiments (a) In the case of Embodiments 1 and 2, the case where the reference voltage values D _b and D _w set according to the reduction rate α are output to the display device 11 has been described.
However, the contrast control unit 7 may output only the reduction ratio α to the display device 11 and generate the reference voltages V _b and V _w corresponding to the reduction ratio α on the display device 11 side.

(B) In the embodiment described above, the case where the number n of calculated frames used in the average gradation value calculating unit 3 is set to “6” has been described.
However, the calculated frame number n may be from 1 frame to 60 frames. Of course, it is desirable to set the specific calculated frame number n according to the combination with the video signal and the determination threshold value B.

(C) In the embodiment described above, the case where the determination threshold value B used in the contrast control units 7 and 55 is set to “35” has been described.
However, other values may be used as the determination threshold B. For example, it may be 10 or more and 100 (when the video signal is 8 bits) or less. Of course, it is desirable to set the specific determination threshold B according to the combination with the video signal and the calculated frame number n.

(D) In the above-described second embodiment, the case where both the calculated frame number n and the determination threshold value B are changed based on the genre information has been described.
However, only one of the calculated frame number n and the determination threshold B may be changed according to the genre information.

(E) In the first and second embodiments, the case where the reference voltage values defining the black level and the white level of the digital / analog converter are variably controlled will be described. In the third embodiment, the gamma conversion characteristics are described. The case has been described in which the gradation width of the output gradation value that is variable and associated with the input gradation value is compressed.

However, in either case, only the black level or only the white level may be variably controlled.
FIG. 29 shows a control example in the case where only the black level is variably controlled. FIG. 30 shows screen luminance characteristics corresponding to this case.
FIG. 31 shows a control example in the case where only the white level is variably controlled. Similarly, FIG. 32 shows screen luminance characteristics corresponding to this case.

  By the way, when only the white level is variably controlled, the same effect as the above-described embodiment can be realized by controlling the L level length of the duty pulse signal that defines the light emission period in the frame of the display device 11. it can.

  FIG. 33 shows an example of variable control of the duty pulse signal. FIG. 33A shows a vertical synchronization pulse that gives the maximum duration of the maximum lighting time length. FIG. 33B shows an example of a duty pulse signal. As shown in FIG. 33B, the L level length is varied in accordance with the reduction rate α. As the reduction ratio α is larger, the L level length is controlled to be shorter. When the reduction rate α is 0 (zero), the L level length is controlled to a set value.

(F) In the embodiment described above, a case has been described in which half of the reduction ratio α is allocated to the black level variable control and the white level variable control.
However, the variable control amount allocation may be asymmetric. For example, the black level side may be varied a lot, and on the contrary, the white level side may be varied and controlled.

(G) In the case of the above-described embodiment, the case where the reduction rate α is gradually increased as the control state continues is described.
However, the reduction rate α may be a fixed value regardless of the continuation of the control state.

(H) In the embodiment described above, the case where the duty pulse signal is output once per frame (FIG. 8) has been described.
However, as shown in FIG. 34, the present invention can also be applied to a case where the duty pulse signal is output once in one horizontal period.

(I) In the embodiment described above, the case where the display device is an organic EL display has been described.
However, the display device may be another self-luminous display device.
For example, an inorganic EL display device, an FED display device, or a PDP display device may be used.

(J) The burn-in suppression device described in the above-described embodiment can realize not only all processing functions by hardware or software, but also by hardware and software function sharing.

(K) Various modifications can be considered for the above-described embodiments within the scope of the gist of the invention. Various modifications and applications created or combined based on the description of the present specification are also conceivable.

It is a figure which shows the function structural example of a burn-in suppression apparatus. It is a figure which shows the internal structural example of an average gradation value calculation part. It is a figure which shows the calculation principle of average gradation value _Cj . It is a figure which shows the input / output relationship when not reducing a contrast difference. It is a figure which shows the input / output relationship in the case of reducing a contrast difference. It is a figure which shows reduction control of the contrast difference accompanying the increase in the reduction rate (alpha). It is a figure which shows the function structural example of a display device. It is a figure explaining a duty pulse signal. It is a figure explaining the connection relation of a pixel circuit and a peripheral circuit. It is a figure which shows the execution procedure of reduction process operation | movement. It is a figure which shows the execution procedure of reduction process operation | movement. It is a figure which shows the screen luminance characteristic when not performing a reduction process. It is a figure which shows the screen luminance characteristic in the case of performing a reduction process. It is a figure which shows the function structural example of a burn-in suppression apparatus. It is a figure which shows the internal structural example of an average gradation value calculation part. It is a figure which shows the change procedure of the number of calculation frames. It is a figure which shows the change procedure of a determination threshold value. It is a figure which shows the function structural example of a burn-in suppression apparatus. It is a figure which shows the execution procedure of reduction process operation | movement. It is a figure which shows the execution procedure of reduction process operation | movement. It is a figure explaining the change of a gradation conversion characteristic. It is a figure explaining the example of mounting to the self-light-emitting display apparatus of the image sticking suppression apparatus. It is a figure explaining the example of mounting to the image processing apparatus of the image sticking suppression apparatus. It is a figure explaining the example of mounting to the electronic device of the image sticking suppression apparatus. It is a figure explaining the example of mounting to the electronic device of the image sticking suppression apparatus. It is a figure explaining the example of mounting to the electronic device of the image sticking suppression apparatus. It is a figure explaining the example of mounting to the electronic device of the image sticking suppression apparatus. It is a figure explaining the example of mounting to the electronic device of the image sticking suppression apparatus. It is a figure explaining the control in the case of carrying out variable control of only a black level. It is a figure explaining the screen brightness | luminance characteristic in the case of carrying out variable control of only a black level. It is a figure explaining the control in the case of carrying out variable control of only a white level. It is a figure explaining the screen luminance characteristic in the case of carrying out variable control of only a white level. It is a figure which shows the variable control example of a duty pulse signal. It is a figure explaining the other structural example of a duty pulse signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Burn-in suppression apparatus 3 Average gradation value calculation part 5 Gradation difference calculation part 7 Contrast control part 11 Display device 21 Unit frame average gradation value calculation part 23 Average gradation value storage part 25 n frame average gradation value calculation part 51 Burn-in suppression device 53 Average tone value calculation unit 55 Contrast control unit 57 Calculation period setting unit 61 Burn-in suppression device 63 Contrast control unit

Claims (12)

An average gradation value calculating unit for calculating an average gradation value of a video signal input between unit frames or a plurality of frames;
A gradation difference calculation unit that calculates a difference value between two average gradation values calculated for two calculation periods set so that the calculation periods do not overlap;
And a contrast control unit that reduces a contrast difference of the display screen when the difference value is smaller than a determination threshold. The burn-in suppression device according to claim 1,
The burn-in suppression device, wherein the contrast control unit gradually increases the reduction rate of the contrast difference when the difference value is smaller than the determination threshold value. The burn-in suppression device according to claim 1,
The burn-in suppression apparatus, wherein the contrast control unit controls both or one of a reference voltage value defining a white level and a black level of a display device to reduce a contrast difference. The burn-in suppression device according to claim 1,
The burn-in suppression device, wherein the contrast control unit controls a duty pulse signal length that defines a light emission time ratio within one frame period. The burn-in suppression device according to claim 1,
The burn-in suppression apparatus, wherein the contrast control unit performs gradation conversion of the video signal so as to reduce a gradation width according to a reduction ratio of a contrast difference. The burn-in suppression device according to claim 1,
The burn-in suppressing device, wherein the contrast control unit varies the number of frames for providing a calculation period of an average gradation value based on information attached to a video signal. The burn-in suppression device according to claim 1,
The burn-in suppression device, wherein the contrast control unit varies a determination threshold based on attached information of a video signal. An average gradation value calculating unit for calculating an average gradation value of a video signal input between unit frames or a plurality of frames;
A gradation difference calculation unit that calculates a difference value between two average gradation values calculated for two calculation periods set so that the calculation periods do not overlap;
A contrast control unit for reducing a contrast difference of a display screen when the difference value is smaller than a determination threshold;
A self-luminous display device comprising: a matrix-driven self-luminous display device. An average gradation value calculating unit for calculating an average gradation value of a video signal input between unit frames or a plurality of frames;
A gradation difference calculation unit that calculates a difference value between two average gradation values calculated for two calculation periods set so that the calculation periods do not overlap;
A contrast control unit for reducing a contrast difference of a display screen when the difference value is smaller than a determination threshold;
An image processing apparatus comprising: a signal processing unit that processes a video signal. An average gradation value calculating unit for calculating an average gradation value of a video signal input between unit frames or a plurality of frames;
A gradation difference calculation unit that calculates a difference value between two average gradation values calculated for two calculation periods set so that the calculation periods do not overlap;
A contrast control unit for reducing a contrast difference of a display screen when the difference value is smaller than a determination threshold;
An electronic apparatus comprising: a matrix-driven self-luminous display device. A process of calculating an average gradation value of a video signal input between unit frames or a plurality of frames;
A process of calculating a difference value between two average gradation values calculated for two calculation periods set so that the calculation periods do not overlap;
And a process of reducing the contrast difference of the display screen when the difference value is smaller than the determination threshold. A process of calculating an average gradation value of a video signal input between unit frames or a plurality of frames;
A process of calculating a difference value between two average gradation values calculated for two calculation periods set so that the calculation periods do not overlap;
A computer program for causing a computer to execute a process of reducing a contrast difference of a display screen when the difference value is smaller than a determination threshold value.

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