JP2006018130A - Burn-in correction device, display device, and image processing device and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a burn-in phenomenon at a fixed display part by solving the inevitable problem that burn-in happens or brightness differences increase as the time elapses. <P>SOLUTION: The burn-in correction device is composed of (a) an area divider to divide the image into several areas, (b) an accumulator to accumulate the light emitted from all the pixels constituting an area for a certain period to obtain an accumulated amount of emitted light, (c) a correction value deciding section to compare the accumulated amount of emitted light of the area and to decide the larger correction value, the larger the area deviates from the reference, (d) a correction value adjuster to correct the correction value corresponding to the position in the area so that the correction value continuously changes between the adjoining areas, and (e) a correction processor to correct the image data in the area according to the correction adjustment value given from the correction value adjuster during the correction period to eliminate the variations of the summed amount of emitted light between the areas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

One aspect of the present invention relates to a burn-in correction device for a self-luminous display device.
The present invention is also realized as a display device and an image processing device equipped with a burn-in correction device. The present invention is also realized as a program for providing a burn-in correction function.

A light-emitting body constituting a self-luminous display device has a characteristic that it deteriorates in proportion to the amount of light emission and time. For this reason, the improvement of the performance of a light-emitting body is expected.
On the other hand, the content of the image displayed on the display device is not uniform. For this reason, the deterioration of the light emitter easily proceeds partially. For example, the light emitting body in the time display area progresses more rapidly than the light emitting bodies in the other display areas.
The luminance of the light-emitting body that has deteriorated is relatively lowered as compared with the luminance of other display areas. In general, this phenomenon is called “burn-in”. Hereinafter, partial deterioration of the light emitter is referred to as “burn-in”.

Currently, various methods are being studied as measures for improving “burn-in”. Some of them are listed below.
For example, Patent Document 1 discloses a method of detecting a change amount of a drive voltage of a light emitting element and controlling a constant current drive signal according to the change amount.
For example, Patent Document 2 discloses a method of applying a reverse bias so that an EL element does not deteriorate while an electroluminescent element (hereinafter referred to as “EL element”) does not emit light.
Further, for example, Patent Document 3 discloses a method of actively discharging a storage capacitor of a pixel (pixel) and suppressing unnecessary light emission time.
Further, for example, Patent Document 4 discloses a method of calculating the deterioration amount from the usage time of the display device, reducing the luminance of all display elements, and slowing the deterioration rate of the display elements.
Further, for example, Patent Document 5 discloses a technique for reducing the luminance of all display elements when an image that does not change is input to the screen for a certain period of time.
JP-A-7-36410 Japanese Patent Laid-Open No. 2003-150110 Japanese Patent Laid-Open No. 2002-169509 JP 2000-356981 A Japanese Patent Laid-Open No. 5-61426

Such a technique is effective in delaying the appearance of “burn-in” or preventing an increase in the appearing luminance difference.
However, there is still a problem that “burn-in” appears or the luminance difference cannot be avoided if time passes.

The inventors pay attention to the above technical problems and propose the following techniques.
That is, as a burn-in correction device for a self-luminous display device,
(A) an area dividing unit that divides an image into a plurality of partial areas;
(B) an accumulation processing unit that accumulates the light emission amounts of all the pixels constituting the partial region for a certain period and sets the cumulative light emission amount for each partial region;
(C) a correction value determining unit that compares the accumulated light emission amount of each partial region with a reference value, and determines a larger value as a correction value for a partial region having a larger degree of deviation from the reference value;
(D) a correction value correcting unit that corrects the corresponding correction value according to the position in the partial area so that the correction value continuously changes between adjacent partial areas;
(E) Proposing a correction processing unit that corrects image data in a corresponding partial area with a correction value given from a correction value correction unit during a correction period, and eliminates variation in the accumulated light emission amount between the partial areas. To do.

It should be noted that the correction process using the correction value is preferably performed only for a still image area where a burn-in phenomenon is likely to occur.
In this case, the burn-in correction apparatus includes a motion determination unit that determines whether each partial region corresponds to a still image region or a moving image region in units of frames, and converts the light emission amount of the partial region determined to be a moving image region to zero. On the other hand, it is preferable to mount a data conversion unit that maintains the light emission amount of the partial area determined as the still image area.
In the burn-in correction apparatus, it is desirable to set a correction range near the boundary of the partial region and correct a correction value to be applied to image data for each pixel only for each pixel located in the correction range.

By adopting such a correction technique, it is possible to positively eliminate the variation in the accumulated light emission amount between the partial areas. That is, the degree of deterioration of the light emitter can be made uniform over the entire display screen. As a result, the burn-in phenomenon itself can be eliminated from the display screen.
In addition, the correction effect of the boundary portion can be blurred by correcting the corresponding correction value according to the position in the partial region so that the correction value continuously changes between the adjacent partial regions. That is, it is possible to make it difficult to perceive the boundary of the partial area that is a correction unit.

Hereinafter, exemplary embodiments of a correction device that corrects burn-in of a self-luminous display device and an electronic apparatus equipped with the correction device 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.
The embodiment described below is one embodiment of the present invention and is not limited thereto.

(A) Terminology In the following description, it is assumed that the sub-pixels of the minimum display unit constituting the display panel are arranged in a matrix.
Each sub-pixel corresponds to each color of R (red), G (green), and B (blue).
One picture element (pixel) is composed of three sub-pixels corresponding to these colors. The display color of each pixel (pixel) is expressed by a combination of these colors.
In this specification, data giving the luminance of a subpixel is referred to as subpixel data.
The sub pixel data corresponding to R (red) is R sub pixel data, the sub pixel data corresponding to G (green) is G sub pixel data, and the sub pixel data corresponding to B (blue) is B sub. This is called pixel data.
Also, data that gives luminance in units corresponding to each pixel (pixel) is called pixel data.
The calculation of the cumulative light emission amount is performed by cumulative addition of these subpixel data. For example, this is performed by cumulative addition of luminance values (gradation data) in units of pixels (pixels) obtained by adding three subpixel data.

Each embodiment to be described later can be similarly applied to the case where the cumulative light emission amount is aligned in units of pixels and the case where the cumulative light emission amount is aligned in units of subpixels.
In addition, when aligning the accumulated light emission amount in pixel units, the corresponding light emission amount is considered in pixel units.
On the other hand, when the accumulated light emission amounts are made uniform in subpixel units, the corresponding light emission amounts are considered in subpixel units corresponding to the respective colors.
Below, in order to avoid duplication description, the case where the accumulation light-emission amount is arrange | equalized in a pixel unit (pixel unit) is demonstrated.
However, as described above, each embodiment can be similarly applied to the case where the accumulated light emission amounts are arranged in units of subpixels (color units).

(B) Conceptual Configuration of Burn-in Correction Device Here, two configuration examples employed as the burn-in correction device will be described. The burn-in correction device is mounted on a part of the semiconductor integrated circuit and a part of the image processing board. However, the function of the burn-in correction device is also realized by program processing.
(A) Configuration example 1
FIG. 1 shows a configuration example of the burn-in correction apparatus 1. The burn-in correction apparatus 1 is a correction apparatus that includes a partial region forming unit 3, a cumulative addition unit 5, a correction value determination unit 7, a correction value correction unit 9, and a correction processing unit 11 as constituent elements.
The partial area unit 3 is a processing device that divides image data into a plurality of partial areas. The partial area unit 3 divides one frame image into a plurality of partial areas, and executes a process for obtaining the light emission amount for each partial area. Here, the light emission amount of each partial area is given as an added value of all the pixel data located in the partial area.
Note that the size of the partial area (number of pixels) depends on the resolution of the input image.
The cumulative addition unit 5 is a processing device that cumulatively adds the light emission amount for each partial area obtained for each frame for a certain period and obtains a cumulative addition value for each partial area. The cumulative addition value is stored for each partial area.

The correction value determination unit 7 is a processing device that compares the accumulated light emission amount of each partial region with a reference value, and determines a larger value as a correction value for a partial region having a larger degree of deviation from the reference value. The method of determining the reference value is selected according to the method for eliminating the difference of the cumulative addition value between the partial areas.
For example, if the deterioration rate of the entire area is made uniform by reducing the deterioration speed of the partial area where deterioration has progressed, the reference value is the cumulative emission amount of the partial area most delayed in deterioration (the minimum cumulative addition value). ).
In addition, for example, if the deterioration rate of the entire screen is made uniform by increasing the deterioration speed of the partial area where the deterioration is delayed, the reference value is the cumulative light emission amount (the maximum value of the cumulative addition value) of the partial area where the deterioration is most advanced. Set to.
Further, for example, when the progress of deterioration is converged to a target deterioration degree, the reference value is set to an intermediate value between the maximum value and the minimum value of the accumulated light emission amount.
The correction value correction unit 9 is a processing device that corrects the corresponding correction value according to the position in the partial area so that the correction value continuously changes between the adjacent partial areas. This processing device is arranged for the purpose of making it difficult to perceive the luminance difference at the boundary portion when the difference between the correction values is large between adjacent partial regions. A specific processing method will be described later.
The correction processing unit 11 is a processing device that corrects pixel data of each partial region with a corresponding correction value. By the correction process, the difference in the accumulated light emission amount between the partial areas is reduced. That is, the light emission performance is uniform over the entire screen. Here, the correction value is obtained by adding correction by the correction value correction unit 9.

(B) Configuration example 2
FIG. 2 shows a configuration example of the burn-in correction device 21. The burn-in correction device 21 is a correction device having a configuration in which the still image region determination unit 23 is added to the configuration example 1. The still image area determination unit 23 is disposed between the partial area conversion unit 3 and the cumulative addition unit 5.
The still image area determination unit 23 is a processing device that determines the still image area of each frame. The still image area determination unit 23 determines whether the area is a still image area or a moving image area by comparing the current frame with the previous frame. Incidentally, a partial region having the same light emission amount in the current frame and the previous frame is determined as a still image region. On the other hand, a partial area in which the amount of light emission differs between the current frame and the previous frame is determined as a moving image area.
The still image area determination unit 23 converts the light emission amount of the partial area determined as the moving image area to zero. The still image area determination unit 23 outputs the light emission amount of the partial area determined as the still image area as it is.
The still image area determination unit 23 is used for the purpose of reflecting only the information of the still image area in determining the correction value. This is because the deterioration of the light emitter proceeds in the still image region.
Note that the same processing devices as those in the configuration example 1 are used as the processing devices having the same reference numerals as those in FIG.

(C) Correction Processing of Correction Value Correction Unit Here, correction value correction processing employed by the correction value correction unit 9 will be described. This correction process has an effect of blurring the correction effect of the boundary portion of the partial region.
FIG. 3 shows the correction concept. FIG. 3 shows the four partial regions 31, 33, 35, and 37. FIG.
Among these, FIG. 3A shows the correspondence between each partial region and the correction value. 3A, “A” corresponds to the partial area 31 in the upper left corner, “B” corresponds to the partial area 33 in the upper right corner, and “D” corresponds to the partial area 35 in the lower left corner. Correspondingly, “E” corresponds to the partial area 37 in the lower right corner.
FIG. 3B shows the concept of the correction process. FIG. 3B shows a correction concept when the correction value A corresponding to the partial area 31 is larger than the correction value B corresponding to the partial area 33. Here, the horizontal width of the correction value corresponds to the horizontal width of the partial area.
FIG. 3B shows an example of correction processing for the correction range 39 set in the peripheral part of the partial area. That is, the case where the correction value is changed linearly starting from the outer edge of the correction range 39 is shown. As a result of the correction process, the correction value in the peripheral part of the partial region 31 is corrected to a smaller value A ′, and the correction value in the peripheral part of the partial region 33 is corrected to a larger value B ′. In FIG. 3B, this correction direction is indicated by an arrow.
By the way, the correction process occurs not only between one adjacent partial area but also between a plurality of adjacent partial areas. FIG. 3A shows such an adjacency relationship with arrows.
For example, in the case of the partial region 31, the following three adjacency relationships are recognized depending on the position within the correction range. That is, the adjacent relationship with the partial region 33, the adjacent relationship with the partial region 35, and the adjacent relationship with the other three partial regions 33, 35, and 37 are recognized.

FIG. 4 shows the allocation relationship of correction values corrected according to these adjacency relationships.
Here, the correction areas A0, B0, D0, and E0 indicate the area portions where the correction values corresponding to the partial areas are used as they are (area portions where the correction value is zero).
Further, the correction area Ab indicates an area portion that ensures continuity with the correction value B among the area portions corresponding to the correction value A.
The correction area Ad indicates an area portion that ensures continuity with the correction value D among the partial areas corresponding to the correction value A.
The correction area Abde (indicated by a circle in the figure) indicates an area portion that ensures continuity with the correction values B, D, and E among the partial areas corresponding to the correction value A.
Similarly, the correction area Ba indicates an area portion that ensures continuity with the correction value A among the area portions corresponding to the correction value B.
In addition, the correction area Be indicates an area portion that ensures continuity with the correction value E among the partial areas corresponding to the correction value B.
Further, the correction area Bade (indicated by Δ in the drawing) indicates an area portion that ensures continuity with the correction values A, D, and E among the partial areas corresponding to the correction value B.
Similarly, the correction area Da indicates an area portion that ensures continuity with the correction value A among the area portions corresponding to the correction value D.
The correction area De indicates an area portion that ensures continuity with the correction value E among the partial areas corresponding to the correction value D.
Further, the correction area Dab (indicated by □ in the figure) indicates an area portion that ensures continuity with the correction values A, B, and E among the partial areas corresponding to the correction value D.
Similarly, the correction area Eb indicates an area portion that ensures continuity with the correction value B among the area portions corresponding to the correction value E.
Further, the correction area Ed indicates an area portion that ensures continuity with the correction value D among the partial areas corresponding to the correction value E.
A correction area Eabd (indicated by a cross in the figure) indicates an area portion that ensures continuity with the correction values A, B, and D among the partial areas corresponding to the correction value E.
Thus, in the correction process for the four partial areas, correction of correction values corresponding to these 16 correction areas (including areas where the correction value is zero) is realized.

FIG. 5 shows the relationship between the corrected correction value and the calculation formula that gives each correction value. FIG. 5 shows a case where one partial region is given by 5 pixels × 5 pixels. In addition, the correction range corresponding to each partial area is one pixel near the boundary.
In the case of FIG. 5, the correction correction value corresponding to the correction area Ab is α, the correction correction value corresponding to the correction area Ad is β, and the correction correction value corresponding to the correction area Abde is χ.
Further, the correction correction value corresponding to the correction area Ba is δ, the correction correction value corresponding to the correction area Be is σ, and the correction correction value corresponding to the correction area Bad is φ.
Further, the correction correction value corresponding to the correction area Da is ε, the correction correction value corresponding to the correction area De is η, and the correction correction value corresponding to the correction area Dabe is ρ.
The correction correction value corresponding to the correction area Eb is μ, the correction correction value corresponding to the correction area Ed is ζ, and the correction correction value corresponding to the correction area Eabd is θ.
Here, the correction correction value between two adjacent partial areas is defined according to the internal ratio in the horizontal direction or the vertical direction. For example, the correction correction values α, β, δ, σ, ε, η, μ, and ζ are defined as follows according to the internal division ratios for the two correction values X and Y. Note that X> Y.
X side correction correction value = (2X + Y) / 3
Correction correction value on the Y side = (X + 2Y) / 3
On the other hand, the correction correction value between three adjacent partial regions is defined as, for example, an average value of surrounding correction correction values. For example, the correction correction values χ, φ, ρ, θ are defined as the average value of two correction correction values in the same partial region as follows:
For example, χ = (α + β) / 2, φ = (δ + σ) / 2, ρ = (ε + η) / 2, and θ = (μ + ζ) / 2 are defined.

A specific example is shown in FIG. FIG. 6A shows an example of correction values calculated for each partial area, and FIG. 6B shows the corrected correction values.
For example, when correction values “24” and “0” are given to the partial area at the upper left corner and the right adjacent partial area, the correction correction value having the larger correction value is “16” (= (2.24 + 0) / 3) is calculated. Further, “8” (= (24 + 2 · 0) / 3) is calculated as the correction correction value with the smaller correction value.
Further, for example, when correction values “24” and “21” are given to the partial area in the upper left corner and the adjacent lower partial area, “23” (= (2.24 + 21) is the correction correction value with the larger correction value. ) / 3) is calculated. Further, “22” (= (24 + 2 · 21) / 3) is calculated as the correction correction value with the smaller correction value.
Also, “19” (= (16 + 23) / 2) is calculated as a correction correction value for the corner adjacent to the other three partial areas in the upper left corner partial area. Other correction correction values are similarly calculated.
The above is the concept of the correction process. In the above description, the correction correction value is set for one pixel located on the outer periphery of each partial area, but the correction range may be a plurality of pixels.
The wider the correction range, the smoother the change in the correction value between the partial areas. For this reason, it is possible to avoid a situation in which the luminance difference at the boundary between the partial areas is emphasized and perceived.
FIG. 7 shows a maximum example of the correction range. FIG. 7 shows an example in which the correction range other than the center point of the partial area is set.

(D) Example Hereinafter, an example of the configuration example 2 among the two types of configuration examples described above will be described. Specifically, two types of embodiments will be described according to the difference in the method of eliminating the difference in the accumulated light emission amount between the partial areas.
(A) Example 1
(1) Processing concept of correction to be used In this embodiment, a method of aligning the degree of deterioration of the entire screen is applied by reducing the deterioration speed of a partial area where deterioration has progressed.
In other words, the smallest accumulated light emission amount among all the partial areas is set as the reference value, and the larger correction value is subtracted from the corresponding original pixel data as the partial area has a larger degree of deviation of the accumulated light emission amount from the reference value. The case where it does is demonstrated.
FIG. 8 shows an image of the correction process. FIG. 8 shows a transition example of the accumulated light emission amount for each partial region when the self-luminous display device is lit for a certain period.
The horizontal axis in FIG. 8 represents the lighting time. In this example, the lighting time is 200 frames.
The vertical axis in FIG. 8 corresponds to the accumulated light emission amount for each partial region.
In the case of FIG. 8, the cumulative light emission amount is given as a cumulative addition value of pixel data corresponding to each partial region. Incidentally, the cumulative addition value (count value) of the partial area 2 after lighting 200 frames is 2500, and the cumulative addition value (count value) of the partial area 1 is 50.

Here, the partial region 1 provides a reference value for the accumulated light emission amount. That is, the partial area 1 is a partial area that gives the minimum cumulative addition value. In other words, the partial area 1 corresponds to the partial area with the least deterioration.
On the other hand, the partial area 2 corresponds to a partial area other than the reference value. That is, the partial area 2 corresponds to a partial area where the cumulative addition value is larger than that of the partial area 1 and deterioration is more advanced.
In the case of FIG. 8, the difference between the cumulative addition values is 2450. If this difference is eliminated in the 200 frame period, the correction value per frame is 12.25 (= 2450 ÷ 200).
Therefore, in this correction process, the correction value is subtracted from the pixel data of the partial region 2 respectively. Incidentally, the correction value of the pixel data for the partial region 1 is zero.
FIG. 9 shows the input / output characteristics after the start of correction. Here, the input / output characteristics corresponding to the partial region 1 are indicated by thin lines. Further, the input / output characteristics before correction corresponding to the partial region 2 are indicated by broken lines. Also, the input / output characteristics after the start of correction corresponding to the partial area 2 are indicated by bold lines.
As shown in FIG. 9, the input / output characteristics for the partial region 1 do not change before and after the start of correction. However, the input / output characteristics for the partial region 2 shift downward before and after the start of correction.
This is because the value of each pixel data is converted to a value smaller by the correction value. For example, when the average gradation value of pixel data before the start of correction is 255, the average gradation value after the start of correction is 242.75 (= 255−12.25).

In the first place, even if the pixel data having the same value as the partial area 1 is given, the partial area 2 cannot generate the same luminance as the partial area 1 due to the deterioration of the light emitting element. That is, a difference in light emission ability indicated by a broken line and a thin line is recognized. In addition, after the start of correction, the output luminance of the partial area 2 further decreases. This means that the contrast difference becomes large.
However, as a result of such correction processing, the progress speed of deterioration in the partial region 2 is surely slower than that in the partial region 1. For this reason, the continuation of the correction process makes it possible to bring the degree of deterioration (residual life) of the partial area 2 to the same or nearly the same as the degree of deterioration (residual life) of the partial area 1.
FIG. 10 shows the situation. At the correction start time t1, a life difference between the partial area 1 and the partial area 2 is recognized.
However, at the correction end time t2, the life difference between the partial area 1 and the partial area 2 is ideally eliminated. That is, during the correction period, the degree of deterioration of all the partial areas coincides with the degree of deterioration of the partial area 1 that has not progressed the most.
This means that the input / output characteristics of the partial area 1 and the input / output characteristics of the partial area 2 substantially coincide as shown in FIG.
Therefore, when the same gradation value is given as pixel data, the same output luminance can be obtained. If the output luminance is the same, the burn-in phenomenon is not perceived. This is the principle of correction.

Incidentally, if the burn-in phenomenon is eliminated in one correction period, pixel data (for example, blue back) of the same gradation value is applied to all partial areas in order to eliminate the occurrence of a new life difference during the correction period. It is desirable to give.
On the other hand, when the correction is performed using the normal screen, it is unavoidable that a new life difference occurs during the correction period, and thus it is necessary to repeatedly execute the correction process. It should be noted that the lifetime difference can be converged to substantially the same range by repeatedly executing the correction process. The burn-in phenomenon is not perceived when the difference in life is almost the same (the input / output characteristics are the same).
As described above, since this correction process determines the correction value for each partial region based on the pixel data information actually used for displaying the image, it is possible to accurately measure the difference in the accumulated light emission amount.
In the case of this correction process, if the correction period is shortened, the correction process can be executed in real time. By correcting the burn-in in real time, it is possible to prevent a difference in life (a difference in input / output characteristics) from occurring for a long time.
The correction period can be set freely. That is, optimization can be performed according to the screen size and system configuration of the display device to be applied.

(2) Device Configuration FIG. 12 shows a configuration example of a burn-in correction device corresponding to this correction processing.
This burn-in correction device 41 includes a partial area unit 43, a still image area determination circuit 45, a cumulative addition circuit 47, a difference value calculation circuit 49, a correction value calculation circuit 51, a correction value correction circuit 53, a correction And a processing circuit 55.
First, the partial region forming unit 43 calculates the light emission amount of each frame for each partial region.
FIG. 13 shows a configuration example of the partial area unit 43. The partial area converting unit 43 includes an area dividing circuit 43A and a partial area adding circuit 43B.

The area dividing circuit 43A realizes a function of dividing and outputting the pixel data taken into the frame memory by dividing into partial areas as shown in FIG. In addition, the partial area adding circuit 43B realizes a function of adding the pixel data output for each partial area to generate a light emission amount for each partial area.
FIG. 14 is a partially enlarged view of the display element. Each area surrounded by a grid corresponds to each pixel. In this embodiment, nine pixels given by 3 rows × 3 columns are treated as one partial region.
Accordingly, as shown in FIG. 14B, the partial area unit 43 treats the added value of the nine pieces of pixel data in the partial area as a light emission amount corresponding to the partial area.
FIG. 15 shows a specific example. For example, in the case of FIG. 15A, nine pixel data corresponding to the partial region in the upper left corner are “1”, “226”, “36”, “28”, “68”, “191”, “87”. “,” “49” and “28” are gradation values.
In this case, as shown in FIG. 15B, the partial area unit 43 outputs an addition value 714 (= 1 + 226 + 36 + 28 + 68 + 191 + 87 + 49 + 28) of nine gradation values as a light emission amount corresponding to the partial area.

The still image region determination circuit 45 is a processing circuit that recognizes a still image portion in units of partial regions and supplies this to the cumulative addition circuit 47.
FIG. 16 shows an example of the still image area determination circuit 45. The still image area determination circuit 45 shown in FIG. 16 includes frame memories 45A and 45B, a motion determination circuit 45C, and a data conversion circuit 45D. The frame memory 45A is a storage device that stores the light emission amount of the current frame. The frame memory 45B is a storage device that stores the light emission amount of the previous frame.
The motion determination circuit 45C is a processing circuit that compares the previous frame stored in the frame memory 45B with the current frame stored in the frame memory 45A and classifies the still image region and the moving image region. Specifically, as shown in FIG. 17A, the motion determination circuit 45C compares the previous frame and the current frame, and determines whether or not the input subpixel data of the corresponding subpixel is the same.
The motion determination circuit 45C determines whether or not the light emission amounts of the corresponding partial areas are the same in the preceding and following frames. When the two light emission amounts are the same, the motion determination circuit 45C determines that the area is a still image area. On the other hand, when the two light emission amounts are different, the motion determination circuit 45C determines that the region is a moving image region. The determination result is given to the data conversion circuit 45D.
The data conversion circuit 45D rewrites the light emission amount of the moving image area to zero and outputs the light emission amount of the still image area as it is.

The cumulative addition circuit 47 receives the light emission amount of each frame from the data conversion circuit 45D. Each time the light emission amount of the current frame is input, the cumulative addition circuit 47 adds the light emission amount of the current frame to the cumulative addition value up to the previous frame, and updates the cumulative addition value. Such an operation can be realized using an internal memory and an adder.
In the difference value calculation circuit 49, a simple difference value calculation process is executed. FIG. 18 shows an example of the difference value calculation process.
The difference value calculation circuit 49 compares the accumulated light emission amounts between adjacent partial areas, and calculates the maximum value of the difference values. For example, in the case of FIG. 18A, the difference values between the partial area in the upper left corner and the three surrounding partial areas are “3120”, “420”, and “2122”.
Accordingly, the difference value calculation circuit 49 associates the maximum value “3120” with the partial region in the upper left corner, as shown in FIG. 18B. Note that zero is set as the difference value in the partial area where the accumulated light emission amount is the smallest among the surroundings.
However, in order to obtain a more accurate value, the minimum value of the accumulated light emission amount may be obtained for all partial areas, and the difference from the accumulated light emission amount of each partial area may be calculated.

The correction value calculation circuit 51 is a processing circuit that calculates a correction value to be given within the correction period. The correction value calculation circuit 51 divides the difference value corresponding to each partial area by the number of frames in the correction period, and sets the value as a correction value for each partial area.
FIG. 19 shows correction values per frame when the number of frames in the correction period is 131. FIG. 19A is a list of difference values calculated by the difference value calculation circuit 49, and FIG. 19B is a list of correction values calculated by the correction value calculation circuit 51. In FIG. 19B, the result of the division operation is rounded off and expressed as an integer value.
The correction value correction circuit 53 is a processing device that corrects the correction value calculated for each partial region by the method described above. When the correction value calculated for each partial area is given, the correction value correction circuit 53 checks the magnitude relationship of the correction values between the partial areas. The correction value correction circuit 53 calculates a correction correction value associated with the pixels in each correction area according to the internal ratio according to the confirmed magnitude relationship.
The correction processing circuit 55 is a processing circuit that subtracts the correction value of the corresponding partial area from the pixel data of the current frame. This subtraction process is executed for the correction period (131 frames in the case of FIG. 19).
Note that after the end of the correction period, the pixel data is output as it is until a new correction period is started.
As described above, the calculation itself required for the burn-in correction device is very simple. Therefore, it does not require complicated calculation and memory unlike the conventional apparatus. Further, unlike a conventional apparatus, a high-performance CPU (central processing unit) and a large-scale logic circuit are not required.
Incidentally, as a result of simple circuit configuration, even when this burn-in correction device is mounted on an existing substrate, it can be mounted on a part of a semiconductor integrated circuit such as a timing generator. That is, it can be mounted without requiring a special peripheral circuit.

(B) Example 2
(1) Processing concept of correction to be used In this embodiment, a method of aligning the degree of deterioration of the entire screen is applied by increasing the deterioration speed of the partial area whose deterioration has been delayed.
In other words, the largest cumulative emission amount among all the partial areas is set as the reference value, and a larger correction value is added to the corresponding original pixel data as the partial area has a larger degree of deviation of the cumulative emission amount from the reference value. The case where it does is demonstrated.
FIG. 20 shows an image of the correction process. FIG. 20 shows a transition example of the accumulated light emission amount for each partial region when the self-luminous display device is lit for a certain period.
The horizontal axis of FIG. 20 represents lighting time. In this example, the lighting time is 200 frames.
The vertical axis in FIG. 20 corresponds to the accumulated light emission amount for each partial region.
In the case of FIG. 20, the cumulative light emission amount is given as a cumulative addition value of pixel data corresponding to each partial region. Incidentally, the cumulative addition value (count value) of the partial area 2 after lighting 200 frames is 2500, and the cumulative addition value (count value) of the partial area 1 is 50.

Here, the partial area 2 gives a reference value of the accumulated light emission amount. That is, the partial area 2 is a partial area that gives the maximum cumulative addition value. In other words, the partial area 2 corresponds to the partial area where the deterioration is most advanced.
On the other hand, the partial area 1 corresponds to a partial area other than the reference value. That is, the partial area 1 corresponds to a partial area that has a smaller cumulative addition value than the partial area 2 and is delayed in deterioration.
In the case of FIG. 20, the difference between the cumulative addition values is 2450. If this difference is eliminated in the 200 frame period, the correction value per frame is 12.25 (= 2450 ÷ 200).
Therefore, in this correction process, the correction value is added to the pixel data of the partial region 1 respectively. Incidentally, the correction value of the pixel data for the partial region 2 is zero.
FIG. 21 shows the input / output characteristics after the start of correction. Here, the input / output characteristics corresponding to the partial region 2 are indicated by thin lines. Further, the input / output characteristics before correction corresponding to the partial region 1 are indicated by broken lines. Also, the input / output characteristics after the start of correction corresponding to the partial region 1 are indicated by bold lines.
As shown in FIG. 21, the input / output characteristics for the partial region 2 do not change before and after the start of correction. However, the input / output characteristics for the partial region 1 shift upward before and after the start of correction.
This is because the value of each pixel data is converted to a value that is larger by the correction value. For example, when the average gradation value of the pixel data before the start of correction is 255, the average gradation value after the start of correction is 267.25 (= 255 + 12.25).

In the first place, even if the pixel data having the same value as the partial area 2 is given, the partial area 1 emits light with higher brightness than the partial area 2 because the light emitting element is less deteriorated.
That is, a difference in light emission ability indicated by a broken line and a thin line is recognized. In addition, after the start of correction, the output luminance of the partial area 1 is further increased. This means that the contrast difference becomes large.
However, as a result of such correction processing, the progress speed of deterioration in the partial area 1 is surely faster than that in the partial area 2.
For this reason, the continuation of the correction process makes it possible to bring the degree of deterioration (residual life) of the partial area 1 to the same or almost the same as the degree of deterioration (residual life) of the partial area 2.
FIG. 22 shows the situation. At the correction start time t1, a life difference between the partial area 1 and the partial area 2 is recognized.
However, at the correction end time t2, the life difference between the partial area 1 and the partial area 2 is ideally eliminated. That is, during the correction period, the degree of deterioration of all the partial areas coincides with the degree of deterioration of the partial area 2 that has been most deteriorated.
This means that the input / output characteristics of the partial area 1 and the input / output characteristics of the partial area 2 substantially coincide as shown in FIG.
Therefore, when the same gradation value is given as pixel data, the same output luminance can be obtained. If the output luminance is the same, the burn-in phenomenon is not perceived. This is the principle of correction.

Incidentally, if the burn-in phenomenon is eliminated in one correction period, pixel data (for example, blue back) of the same gradation value is applied to all partial areas in order to eliminate the occurrence of a new life difference during the correction period. It is desirable to give.
On the other hand, when the correction is performed using the normal screen, it is unavoidable that a new life difference occurs during the correction period, and thus it is necessary to repeatedly execute the correction process. It should be noted that the lifetime difference can be converged to substantially the same range by repeatedly executing the correction process. The burn-in phenomenon is not perceived when the difference in life is almost the same (the input / output characteristics are the same).
As described above, since this correction process determines the correction value for each partial region based on the pixel data information actually used for displaying the image, it is possible to accurately measure the difference in the accumulated light emission amount.
In the case of this correction process, if the correction period is shortened, the correction process can be executed in real time. By correcting the burn-in in real time, it is possible to prevent a difference in life (a difference in input / output characteristics) from occurring for a long time.
The correction period can be set freely. That is, optimization can be performed according to the screen size and system configuration of the display device to be applied.
(2) Device Configuration FIG. 24 shows a configuration example of a burn-in correction device corresponding to this correction processing.
The basic configuration of the burn-in correction device 61 is the same as that of the first embodiment (FIG. 12). The only difference is that the difference value calculation circuit 49 uses the reference value as the maximum cumulative addition value, and the correction processing circuit 63 uses a processing circuit that adds correction values of partial areas corresponding to pixel data of the current frame. It is. Others are the same as those of the first embodiment, and thus description thereof is omitted.

(E) System Example Next, an implementation example of the above-described burn-in correction apparatus and burn-in correction program will be described.
Here, a case where a self-luminous display device and an image processing device that generates an image signal are separate housings will be described.
Needless to say, it can also be mounted on an electronic device in which a self-luminous display device and an image processing device are mounted in one housing.
(A) Display Device Mounted Type FIG. 25 shows a system example in which the burn-in correction device 71 is mounted on the display device 73. The self-luminous display device 73 and the image processing device 75 are connected via a wired communication path or a wireless communication path. The connection form may be direct connection or LAN connection.
FIG. 26 shows a functional block configuration of the self-luminous display device 73. Examples of this type of display device 73 include CRT (cathode lay tube), PDP (plasma display panel), EL (electroluminescence display), FED (field
emission display).
The display device 73 includes a display device 73A corresponding to these various display methods, a drive circuit 73B, and a burn-in correction device 71.
As the drive circuit 73B, one corresponding to the display device 73A to be driven is used. The image processing device 75 may have a known circuit configuration.
In the case of this system example, the image processing device 75 outputs an image signal corresponding to the connection destination display device. The image signal may be analog or digital.
When the image signal is input from the image processing device 75, the display device 73 performs the above-described burn-in correction processing on the input subpixel data corresponding to each subpixel.
The pixel data after this correction processing is given to the drive circuit 73B, and the display device 73A is driven. Thus, an image is displayed.

(B) Image Processing Device Mounted Type FIG. 27 shows a system example in which the burn-in correction device 81 is mounted on the image processing device 83. Also in this case, the connection between the image processing device 81 and the self-luminous display device 85 may be a wired connection or a wireless connection. Of course, the connection form may be direct connection or LAN connection.
FIG. 28 shows a functional block configuration of the image processing device 83 connected to the self-luminous display device 85. In general, the image processing device 83 can be connected to a non-self-luminous display device (for example, a liquid crystal display device).
Therefore, the functional block configuration of FIG. 28 is a configuration in the case where a self-luminous display device 85 is connected as an image signal output device.
The image processing device 83 includes an image processing circuit 83A and a burn-in correction device 81. In FIG. 28, a well-known circuit configuration is omitted. The image processing circuit 83A executes image processing according to the form of the electronic device (image processing device 83) to be mounted. For example, image capturing, reproduction, editing, and other processes are executed.
In the case of this system example, the burn-in correction process is executed in the housing of the image processing apparatus 83. That is, the image signal output from the image processing circuit 83A is input to the burn-in correction circuit 81 arranged between the output interface.
The burn-in correction circuit 81 performs the burn-in correction process described above for each pixel data of the image signal. In the case of this system example, the display device 85 displays the input image signal on a display device through known signal processing.
Examples of this type of image processing apparatus 83 include a video camera, a digital camera, and other imaging apparatuses (including not only a camera unit but also an apparatus configured integrally with a recording apparatus), a computer (including a server). Various information processing terminals (portable computers, mobile phones, portable game machines, electronic notebooks, etc.), various image playback devices (including home servers), image editing devices, and game machines can be applied. is there.

(F) Effects of Embodiments As in the above embodiments, by calculating the accumulated light emission amount of each partial region for a still image signal, it is possible to positively correct a still image signal that causes partial luminance degradation. . That is, it is possible to correct luminance degradation fairly accurately.
Further, by correcting the pixel data in units of partial areas, the frame memory can be greatly reduced.
In addition, a correction range is set at the boundary between multiple partial areas, and correction values assigned to each partial area are partially corrected so that the correction values continuously change within the range. Block noise and block noise after correction can be reduced.
In addition, by correcting the burn-in in real time by shortening the correction period, correction without deviation can be performed even if the correction is performed for a long time.
In addition, the scale of the system can always be optimized by freely changing the correction period. As a result, even if the correction period is changed, the burn-in correction can be prevented from being hindered.
Further, unlike the prior art, no burn-in correction is performed to increase the brightness of the deteriorated pixel (to promote the deterioration of the lifetime), so that the lifetime of the light emitter is not shortened.
In addition, the luminance deterioration of the fixed display portion can be made inconspicuous regardless of the usage.
In addition, it is practical because it is possible to suppress variations in luminance deterioration for each partial region by preparing only two frame memories.

(G) Other Embodiments (a) In the above-described embodiments, the partial area pixel data is corrected based on the most advanced degradation level or the most delayed degradation level as a partial area correction method. Explained the case.
However, the method for correcting the accumulated light emission amounts of all the partial areas to be equal is not limited to these. For example, an intermediate value between the maximum and minimum accumulated light emission amounts is set as the reference value, and for partial areas that have deteriorated more than the reference value, correction is made so that the deterioration speed decreases, and the deterioration is lower than the reference value. It may be corrected so as to increase the deterioration speed for the partial area delayed.
Even in this way, the burn-in phenomenon can be solved in principle.
(B) In the above-described embodiment, the case where the burn-in correction apparatus is realized in hardware has been described. In this case, each function of the burn-in correction device may be realized by a program.
(C) Although the case where the correction correction value is sequentially calculated has been described in the above-described embodiment, a method of using a storage table for the correction value according to the correction value difference and the correction range may be employed. In this case, the correction correction value within the correction range can be obtained by adding and subtracting the correction value of the corresponding partial area and the correction value read from the storage table.
(D) Various modifications can be considered in the above-described embodiment within the scope of the gist of the invention. Various modifications and application examples created based on the description of the present specification are also conceivable.

It is a figure which shows one structural example of the burn-in correction apparatus. It is a figure which shows one structural example of the burn-in correction apparatus. It is a figure which shows the concept of a correction process. It is a figure which shows the positional relationship of a correction area | region. It is a figure which shows the correspondence of a correction correction value and a correction area | region. It is a figure which shows the specific example of a correction process. It is a figure which shows the modification of a correction process. It is a figure which shows the transition of the accumulated light emission amount in a partial area | region. It is a figure which shows the change of the input-output characteristic before and behind correction | amendment. It is a figure which shows the transition relationship of the lifetime of the light-emitting body by correction | amendment. It is a figure which shows the input / output characteristic after completion | finish of correction | amendment. It is a figure which shows the Example of a burn-in correction apparatus. It is a figure which shows the structural example of a partial area | region formation part. It is a figure which shows the production | generation principle of the emitted light amount according to partial area. It is a figure which shows the example of calculation of the emitted light amount according to partial area. It is a figure which shows the structural example of a still area | region determination circuit. It is a figure which shows the process example of a still region determination circuit. It is a figure which shows the process example of a difference value calculation circuit. It is a figure which shows the process example of a correction value calculation circuit. It is a figure which shows the transition of the accumulated light emission amount in a partial area | region. It is a figure which shows the change of the input-output characteristic before and behind correction | amendment. It is a figure which shows the transition relationship of the lifetime of the light-emitting body by correction | amendment. It is a figure which shows the input / output characteristic after completion | finish of correction | amendment. It is a figure which shows the Example of a burn-in correction apparatus. It is a figure which shows the example of a system with a display apparatus mounting type. It is a figure which shows the functional block structure of a self-luminous type display apparatus. It is a figure which shows the example of a system of an image processing apparatus mounting type. . It is a figure which shows the functional block structure of an image processing apparatus.

Explanation of symbols

3 Partial region forming unit 5 Cumulative adding unit 7 Correction value determining unit 9 Correction value correcting unit 11 Correction processing unit 23 Still image region determining unit

Claims (7)

An area dividing unit for dividing an image into a plurality of partial areas;
A cumulative processing unit that accumulates the light emission amount of all the pixels constituting the partial region for a certain period, and sets the cumulative light emission amount for each partial region;
A correction value determination unit that compares the accumulated light emission amount of each partial region with a reference value, and determines a larger value as a correction value for a partial region with a larger degree of deviation from the reference value;
A correction value correction unit that corrects the corresponding correction value according to the position in the partial region so that the correction value continuously changes between adjacent partial regions;
A correction processing unit that corrects the image data in the corresponding partial area with the correction value given from the correction value correcting unit during the correction period, and eliminates the variation in the accumulated light emission amount between the partial areas. Self-luminous display burn-in correction device. The burn-in correction device according to claim 1,
A motion determination unit that determines in frame units whether each partial area corresponds to a still image area or a moving image area;
A burn-in correction apparatus, further comprising: a data conversion unit that converts a light emission amount of a partial region determined to be a moving image region to zero while leaving a light emission amount of the partial region determined to be a still image region. The burn-in correction device according to claim 1,
A burn-in correction apparatus that determines a correction value of each partial area for each color and corrects image data. The burn-in correction apparatus according to claim 1,
The burn-in correction apparatus, wherein the correction value correction unit sets a correction range near a boundary of a partial region, and corrects a correction value corresponding to each pixel only for each pixel located in the correction range. An area dividing unit for dividing an image into a plurality of partial areas;
A cumulative processing unit that accumulates the light emission amount of all the pixels constituting the partial region for a certain period, and sets the cumulative light emission amount for each partial region;
A correction value determination unit that compares the accumulated light emission amount of each partial region with a reference value, and determines a larger value as a correction value for a partial region with a larger degree of deviation from the reference value;
A correction value correction unit that corrects the corresponding correction value according to the position in the partial region so that the correction value continuously changes between adjacent partial regions;
A correction processing unit that corrects the image data in the corresponding partial area with the correction value given from the correction value correction unit during the correction period, and eliminates the variation in the accumulated light emission amount between the partial areas;
A self-luminous display device comprising: a display device that inputs image data corrected by the correction processing unit and displays a corresponding image on a screen. An area dividing unit for dividing an image into a plurality of partial areas;
A cumulative processing unit that accumulates the light emission amount of all the pixels constituting the partial region for a certain period, and sets the cumulative light emission amount for each partial region;
A correction value determination unit that compares the accumulated light emission amount of each partial region with a reference value, and determines a larger value as a correction value for a partial region with a larger degree of deviation from the reference value;
A correction value correction unit that corrects the corresponding correction value according to the position in the partial region so that the correction value continuously changes between adjacent partial regions;
A correction processing unit that corrects the image data in the corresponding partial area with the correction value given from the correction value correction unit during the correction period, and eliminates the variation in the accumulated light emission amount between the partial areas;
An image processing apparatus comprising: an output unit that outputs the image data corrected by the correction processing unit to a self-luminous display device. In a computer that processes image data that drives a self-luminous display device,
A process of dividing the image into a plurality of partial areas;
A process of accumulating the light emission amount of all the pixels constituting the partial area for a certain period, and setting the accumulated light emission amount for each partial area;
A process of comparing the accumulated light emission amount of each partial area with a reference value, and determining a larger value as a correction value for a partial area having a larger degree of deviation from the reference value;
A process of correcting the corresponding correction value according to the position in the partial area so that the correction value continuously changes between adjacent partial areas;
A program for correcting image data in a corresponding partial area with a correction value given from the correction value correcting unit during a correction period, and executing a process for eliminating variation in the accumulated light emission amount between the partial areas. .

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