JP3249814B1 - Display device and brightness control method thereof - Google Patents

Abstract

The present invention provides a display device and a brightness control method for the display device, which can more reliably prevent damage to a display unit. SOLUTION: A temperature difference estimator 4 outputs a temperature estimation value Te indicating an outer peripheral temperature of a display screen of a PDP 11 from a video signal VS and a PD output from a panel outer peripheral temperature setting device 5.
An estimated temperature difference value Td is obtained using a reference value To representing the temperature of the panel outer peripheral portion of P11, and an image displayed on the display unit 1 by the controller 3 and the brightness controller 2 according to the estimated temperature difference value Td. Control the brightness of.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a display device for displaying an image with luminance according to a video signal input from the outside, and a luminance control method therefor.

[0002]

2. Description of the Related Art PDP (Plasma Display Panel)
Is advantageous in that it can be made thinner and larger. In this plasma display panel device, an image is displayed by utilizing light emission at the time of discharge of a discharge cell constituting a pixel. With this light emission, heat is generated on the glass surface constituting the PDP, and the calorific value increases as the luminance of the image increases. For this reason, there has been a problem that the temperature of the glass surface increases, and in the worst case, the glass surface is damaged.

In order to solve the above-mentioned problems, as a conventional display device, for example, there is a display device disclosed in Japanese Patent Application Laid-Open No. H11-194745. In this display device,
The entire display screen is divided into a plurality of blocks, temperature predicted values are calculated for all blocks, and a maximum value of the calculated predicted temperatures is compared with a reference temperature to generate a luminance correction coefficient. The brightness of the display screen is controlled by the correction coefficient.

[0004]

Generally, a display section for displaying an image is fixed at an outer peripheral portion of the display section, and damage to the display section due to an increase in temperature due to an increase in luminance occurs near the outer peripheral section of the display section. Is the most. That is, the damage of the display unit depends on the temperature difference rather than the maximum temperature, and usually, the temperature difference between the outer peripheral portion of the display unit that does not generate heat and the outer peripheral portion of the display screen of the display unit that generates heat becomes largest. It is often damaged by thermal stress due to temperature difference.

However, in the above-mentioned conventional display device, the brightness control is performed only when the maximum value of the predicted temperature is higher than the reference temperature, that is, when the temperature of any part on the display screen exceeds a certain upper limit value. It is carried out. For this reason,
When excessive thermal stress is applied to the most susceptible outer part of the display unit, the brightness cannot always be controlled,
The display cannot be reliably prevented from being damaged.

Further, in the above-mentioned conventional display device, the entire display screen is divided into a plurality of blocks, and the predicted temperatures are calculated for all the blocks. Therefore, the arithmetic processing becomes complicated and the arithmetic processing takes a long time. It costs. In particular, in recent years, there has been a demand for higher definition of a display image, and the number of pixels of a display screen, that is, the number of discharge cells tends to increase. In this case,
The above arithmetic processing becomes more and more complicated, and the processing time becomes longer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display device and a brightness control method for the display device, which can more reliably prevent damage to the display unit.

It is another object of the present invention to provide a display device and a brightness control method thereof that can more reliably prevent the display unit from being damaged with a small amount of calculation.

[0009]

Means for Solving the Problems (1) First invention A display device according to a first invention comprises: a display section for displaying an image at a luminance corresponding to a video signal inputted from the outside; Temperature estimating means for estimating a temperature estimated value corresponding to the temperature of the display screen of the unit, and calculating means for obtaining a temperature difference estimated value using a reference value and a temperature estimated value corresponding to the temperature of the outer peripheral part of the display unit, Control means for controlling the brightness of the image displayed on the display unit based on the temperature difference estimated value.

In the display device according to the present invention, an estimated temperature value corresponding to the temperature of the display screen of the display unit is estimated from the video signal, and the estimated temperature value is compared with a reference value corresponding to the temperature of the outer peripheral portion of the display unit. Is used to calculate a temperature difference estimated value, and the brightness of an image displayed on the display unit is controlled based on the temperature difference estimated value. In general, a display section for displaying an image is fixed at an outer peripheral portion thereof. Therefore, damage to the display section due to a rise in temperature due to an increase in luminance almost always occurs near the outer peripheral section of the display section. Therefore, as described above, the display is controlled by controlling the luminance according to the temperature difference estimated value obtained from the temperature estimated value corresponding to the temperature of the display screen and the reference value corresponding to the temperature of the outer peripheral portion of the display unit. The brightness can be controlled based on the temperature difference between the outer peripheral portion of the display unit and the display screen, which has the greatest influence on the damage of the display unit, and the display unit can be more reliably prevented from being damaged.

(2) Second invention In the display device according to the second invention, in the configuration of the display device according to the first invention, the temperature estimating means corresponds to the temperature of the outer peripheral portion of the display screen of the display section. This is for estimating the temperature estimation value.

In this case, an estimated temperature value corresponding to the temperature of the outer periphery of the display screen of the display unit is estimated from the video signal, and the estimated temperature value and a reference value corresponding to the temperature of the outer periphery of the display unit are used. The temperature difference estimation value is obtained, and the brightness of the image displayed on the display unit is controlled based on the temperature difference estimation value. As described above, since the temperature difference estimation value is obtained from the temperature estimation value corresponding to the temperature at the outer peripheral portion of the display screen and the reference value corresponding to the temperature at the outer peripheral portion of the display portion, the temperature difference is most affected by damage to the display portion. The brightness can be controlled based on the temperature difference between the outer peripheral portion of the large display portion and the outer peripheral portion of the display screen closest to the outer peripheral portion, and the display portion can be more reliably prevented from being damaged. Also,
Since the temperature estimation value calculated to obtain the temperature difference estimation value is limited to the temperature estimation value at the outer peripheral portion of the display screen of the display unit, the amount of calculation is smaller than when calculating the temperature estimation value of the entire display screen. And the processing is simplified and the processing time is shortened. As a result, it is possible to more reliably prevent the display unit from being damaged with a small amount of calculation.

(3) Third Invention A display device according to a third invention is the display device according to the first or second invention, wherein the display section has a plurality of light emitting elements formed between the display portions. An outer periphery of the display unit includes a first and a second substrate to which an outer periphery is fixed. Part.

In this case, the reference value corresponds to the temperature of the portion between the outermost light emitting element and the fixed portion of the first and second substrates. The brightness can be controlled in a short time, and the display unit can be more reliably prevented from being damaged.

(4) Fourth Invention A display device according to a fourth invention is the display device according to any one of the first to third inventions, wherein the temperature estimating means is:
A temperature estimation value is estimated by integrating data relating to luminance from a video signal and subtracting a heat radiation amount, and the calculating means obtains a temperature difference estimation value by subtracting a reference value from the temperature estimation value.

In this case, since the data relating to the luminance is integrated from the video signal and the heat radiation is subtracted, a temperature estimation value corresponding to the actual temperature can be obtained. Therefore, since the luminance is controlled based on the temperature difference estimated value obtained by subtracting the reference value from the temperature estimated value, the luminance can be controlled with higher accuracy, and the display unit can be more reliably prevented from being damaged.

(5) Fifth Invention According to a fifth aspect of the present invention, in the display device according to any one of the first to fourth aspects of the invention, the control means may be configured to respond to an increase in the estimated temperature difference value. The brightness of the image displayed on the display unit.

In this case, since the brightness is reduced in accordance with the increase in the estimated temperature difference, the display can be more reliably prevented from being damaged.

(6) Sixth invention In the display device according to the sixth invention, in the configuration of the display device according to any one of the first to fifth inventions, the control means is arranged to respond to an increase in the estimated temperature difference value. The maximum brightness of the image displayed on the display unit.

In this case, since the maximum luminance is reduced in accordance with the increase in the estimated temperature difference, it is possible to more reliably prevent the display unit from being damaged, and to display luminance other than the maximum luminance as it is. Thus, a good image corresponding to the original luminance of the video signal can be displayed.

(7) Seventh invention A display device according to a seventh invention is the display device according to any one of the first to sixth inventions, wherein the display unit is configured to display an image from a plurality of gradations. The image is displayed at a gradation corresponding to the signal, and the control means reduces the luminance of the image displayed on the display unit at the same ratio for each gradation.

In this case, since the luminance is reduced at the same ratio for each gradation, the luminance of the display unit can be reduced without giving the viewer a sense of strangeness.

(8) Eighth Invention The display device according to the eighth invention is the display device according to any one of the first to seventh inventions, wherein the display unit has the same total number of gradations and An image is displayed at a gradation corresponding to a video signal in a plurality of light emission formats in which the number of light emission pulses in each gradation is different, and the control means selects a light emission format selected from the plurality of light emission formats according to the temperature difference estimated value. To control the brightness of the image displayed on the display unit.

In this case, the luminance can be controlled by switching the light emission format in order from the plurality of light emission formats with the same gradation and the largest number of light emission pulses from the plurality of light emission formats in accordance with the increase in the estimated temperature difference. The luminance can be reduced without greatly changing the total number of gradations.

(9) Ninth Invention A display device according to a ninth invention is the display device according to any one of the first to eighth inventions, wherein the control means controls the display screen of the display unit to include a plurality of display screens. An outer peripheral block adjacent to the outer periphery of the display screen is extracted from the plurality of blocks by dividing into blocks, and the luminance of the outer peripheral block is reduced.

In this case, since the brightness of the outer peripheral block adjacent to the outer periphery of the display screen is reduced, the image of the block inside the display screen can be displayed at the original luminance of the video signal, and the viewer can visually recognize the image. It is possible to provide a display screen without a sense of strangeness, and it is possible to more reliably prevent the outer peripheral portion of the display unit from being damaged.

(10) Tenth invention In a display device according to a tenth invention, in the configuration of the display device according to any one of the first to ninth inventions, the control means controls the display screen of the display unit to include a plurality of display screens. An outer peripheral block adjacent to the outer periphery of the display screen is extracted from the plurality of blocks by dividing into blocks, and the luminance of the outer peripheral block is made lower than that of the inner block of the display screen of the display unit.

In this case, since the luminance of the outer peripheral block is made lower than that of the block inside the display screen, the change of the luminance of the display screen becomes smooth, and a display screen free from visual discomfort by the viewer is provided. In addition to this, it is possible to more reliably prevent the outer peripheral portion of the display unit from being damaged.

(11) Eleventh invention A display device according to an eleventh invention is the display device according to any one of the first to tenth inventions, wherein the display screen of the display unit is divided into a plurality of blocks. And a block extracting unit for extracting an outer peripheral block adjacent to the outer periphery of the display screen from the plurality of blocks, wherein the temperature estimating unit estimates a temperature estimated value for each outer peripheral block, An outer peripheral block temperature difference estimated value is obtained from the estimated temperature estimated value, and the control means controls the luminance for each outer peripheral block based on the outer peripheral block temperature difference estimated value.

In this case, the display screen is divided into a plurality of blocks, and the brightness is controlled for each of the outer peripheral blocks adjacent to the outer periphery of the display screen. It is possible to provide a display screen without a sense of strangeness, and it is possible to more reliably prevent damage on the outer peripheral portion of the display unit.

(12) Twelfth Invention In the display device according to the twelfth invention, in the configuration of the display device according to the eleventh invention, the control means may be configured to control the distance between adjacent outer blocks based on the estimated outer block temperature difference. The luminance is controlled for each outer peripheral block so that the luminance control amount of the peripheral block changes smoothly.

In this case, since the brightness control amount between the adjacent outer peripheral blocks changes smoothly, it is possible to provide a display screen that is not visually uncomfortable to the viewer, and to generate a display screen at the outer peripheral portion of the display section. Since the thermal stress changes smoothly, it is possible to more reliably prevent the display unit from being damaged.

(13) Thirteenth Invention A display device according to a thirteenth invention is the display device according to any one of the first to twelfth inventions, wherein the display screen of the display unit is divided into a plurality of blocks. And a block extracting unit for extracting an outer peripheral block adjacent to the outer periphery of the display screen from the plurality of blocks, wherein the temperature estimating unit estimates a temperature estimated value for each outer peripheral block, An outer peripheral block temperature difference estimated value for each outer peripheral block is obtained from the estimated temperature estimated value, and a maximum outer peripheral block temperature difference estimated value is extracted from the outer peripheral block temperature difference estimated value. The brightness of the image displayed on the display unit is controlled based on the value.

In this case, since the luminance is controlled by using the estimated value of the maximum outer peripheral block temperature difference having the largest temperature difference in the outer peripheral block, it is possible to more reliably prevent the display unit from being damaged. Further, since the luminance is controlled by one maximum outer peripheral block temperature difference estimated value, the luminance control process is simplified.

(14) Fourteenth Invention In the display device according to the fourteenth invention, in the configuration of the display device according to any one of the first to thirteenth inventions, the reference value is determined by the position of the outer peripheral portion of the display unit. It includes a plurality of different reference values.

In this case, the brightness of the image displayed on the display unit can be controlled using a plurality of reference values that are different depending on the position of the outer peripheral portion of the display unit. Is set, and a low reference value is set in a portion where the temperature is unlikely to rise, whereby the luminance can be controlled based on each reference value. As a result, the display unit can be more reliably prevented from being damaged, and the luminance is not unnecessarily reduced.

(15) Fifteenth Invention In the display device according to the fifteenth invention, in the configuration of the display device according to any one of the first to fourteenth inventions, the temperature of the outer peripheral portion of the display section is measured and measured. It further comprises a measuring means for outputting a reference value corresponding to the temperature to the calculating means.

In this case, the temperature of the outer peripheral portion of the display section can be directly measured, and the luminance can be controlled based on the reference value corresponding to the temperature. The display unit can be reliably prevented from being damaged.

(16) Sixteenth Invention A brightness control method for a display device according to a sixteenth invention is a brightness control method for a display device including a display unit for displaying an image at a brightness corresponding to a video signal input from the outside. A temperature estimation value corresponding to the temperature of the display screen of the display unit is estimated from the video signal, and a temperature difference estimation value is obtained using the reference value and the temperature estimation value corresponding to the temperature of the outer peripheral portion of the display unit. , For controlling the brightness of the image displayed on the display unit based on the estimated temperature difference.

In the brightness control method for a display device according to the present invention, an estimated temperature value corresponding to the temperature of the display screen of the display unit is estimated from the video signal, and the estimated temperature value is associated with the temperature of the outer peripheral portion of the display unit. A temperature difference estimated value is obtained using the reference value to be calculated, and the brightness of the image displayed on the display unit is controlled based on the temperature difference estimated value. In general, a display unit for displaying an image is fixed at an outer peripheral portion thereof, and in most cases, damage to the display unit due to an increase in luminance occurs near the outer peripheral portion of the display unit. Therefore, as described above, the display is controlled by controlling the luminance according to the temperature difference estimated value obtained from the temperature estimated value corresponding to the temperature of the display screen and the reference value corresponding to the temperature of the outer peripheral portion of the display unit. The brightness can be controlled based on the temperature difference between the outer peripheral portion of the display unit and the display screen, which has the greatest influence on the damage of the display unit, and the display unit can be more reliably prevented from being damaged.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an AC plasma display device will be described as an example of a display device according to the present invention. Note that the display device to which the present invention is applied is not particularly limited to an AC type plasma display device, and can be similarly applied to other display devices as long as the temperature of the display screen changes due to a change in luminance. is there.

First, a plasma display device according to a first embodiment of the present invention will be described. FIG. 1 is a block diagram showing the configuration of the plasma display device according to the first embodiment of the present invention.

The plasma display apparatus shown in FIG. 1 includes a display unit 1, a brightness controller 2, a controller 3, a temperature difference estimator 4, and a panel outer peripheral temperature setting unit 5.

The video signal VS is input to the brightness controller 2 and the temperature difference estimator 4. The panel outer peripheral temperature setting device 5 sets a reference value To indicating the temperature of the outer peripheral portion of the panel of the display unit 1 and outputs the reference value To to the temperature difference estimator 4. The temperature difference estimator 4 calculates a temperature difference estimated value Td representing a difference between the temperature of the outer peripheral portion of the display unit 1 and the temperature of the display screen using the video signal VS and the reference value To, and calculates the temperature difference estimated value. Td is output to the controller 3.

The controller 3 outputs a brightness control signal LC for controlling the brightness of the display screen of the display unit 1 to the brightness controller 2 according to the estimated temperature difference Td.
The brightness controller 2 outputs a data driver drive control signal DS, a scan driver drive control signal CS, and a sustain driver drive control signal US for displaying an image with luminance according to the brightness control signal LC to the display unit 1. .

FIG. 2 is a block diagram showing a configuration of the temperature difference estimator 4 shown in FIG. As shown in FIG. 2, the temperature difference estimator 4 includes an outer periphery adjacent part separator 41, an integration circuit 42, a heat radiation amount subtraction circuit 43 and a subtractor 44.

The outer periphery adjacent separator 41 receives the video signal VS, separates the outer periphery adjacent portion adjacent to the outer periphery of the display screen of the display unit 1 from the video signal VS, and separates the integration circuit 4.
Output to 2. The video signal VS includes not only the original video signal but also a vertical synchronizing signal, a horizontal synchronizing signal, and the like, and an outer peripheral portion is separated using the horizontal synchronizing signal, the vertical synchronizing signal, and the like.

The integrating circuit 42 integrates data relating to luminance, for example, a luminance signal of the outer peripheral portion, from the video signal of the outer peripheral portion separated by the outer peripheral separator 41 and outputs the integrated signal to the heat radiation subtraction circuit 43.

The heat radiation amount subtracting circuit 43 calculates a temperature estimation value Te representing the temperature of the outer periphery adjacent portion by subtracting the heat radiation amount from the integrated luminance signal of the outer periphery adjacent portion, and subtracts the estimated temperature value Te by a subtractor. Output to 44.

The subtractor 44 calculates the temperature estimation value T
By subtracting the reference value To of the outer peripheral portion of the panel from e, an estimated temperature difference Td of the outer peripheral portion of the display screen is obtained, and the estimated temperature difference Td is output to the controller 3.

The controller 3 selects a corresponding light emission format from a plurality of light emission formats in accordance with the temperature difference estimated value Td obtained by the above processing, and performs a light emission pulse control for designating the selected light emission format. A brightness control signal LC including the signal EC and a multiplication coefficient k in the selected light emission format is generated and output to the brightness controller 2.

FIG. 3 is a block diagram showing the configuration of the brightness controller 2 shown in FIG. As shown in FIG. 3, the brightness controller 2 includes a multiplying circuit 21, a video signal-subfield associator 22, and a subfield pulse generator 23.

The multiplication circuit 21 multiplies the video signal VS by a multiplication coefficient k included in the brightness control signal LC, and
Is output to the video signal-subfield correlator 22.

Video signal-subfield correlator 22
Since one field is divided into a plurality of sub-fields and displayed, one of a plurality of light emission formats is designated from a video signal of one field according to a light emission pulse control signal EC included in the brightness control signal LC. Creates image data for each subfield of the light emission format, and outputs a data driver drive control signal DS corresponding to the image data for each subfield.
Is output to the display unit 1.

The sub-field pulse generator 23 drives a scan driver corresponding to each sub-field of a designated light emission format from a plurality of light emission formats in accordance with a light emission pulse control signal EC included in the brightness control signal LC. A control signal CS and a sustain driver drive control signal US are output to the display unit 1.

FIG. 4 is a block diagram showing a configuration of the display unit 1 shown in FIG. The display unit shown in FIG. 1 includes a PDP (plasma display panel) 11, a data driver 12, a scan driver 13, and a sustain driver 14.

The data driver 12 is connected to a plurality of address electrodes (data electrodes) AD of the PDP 11.
The scan driver 13 includes therein a drive circuit provided for each scan electrode (scan electrode) SC of the PDP 11, and each drive circuit is connected to the corresponding scan electrode SC. The sustain driver 14 is commonly connected to a plurality of sustain electrodes (sustain electrodes) SU of the PDP 11.

In accordance with the data driver drive control signal DS, the data driver 12 controls the PDP during the writing period.
A write pulse is applied to the corresponding address electrode AD of No. 11. On the other hand, according to the scan driver drive control signal CS, the scan driver 13
The PDP 11 shifts the shift pulse in the vertical scanning direction.
Are sequentially applied to the plurality of scan electrodes SC. As a result, the address discharge is performed in the corresponding discharge cell, and the discharge cell corresponding to the video signal VS is selected.

The scan driver 13 responds to the scan driver drive control signal CS during the sustain period.
A periodic sustain pulse is applied to the plurality of scan electrodes SC of the PDP 11. On the other hand, the sustain driver 14 simultaneously applies a sustain pulse 180 degrees out of phase with respect to the sustain pulse of the scan electrode SC to the plurality of sustain electrodes SU of the PDP 11 in the sustain period in accordance with the sustain driver drive control signal US. As a result, sustain discharge is performed in the discharge cell selected in the address period, and an image is displayed on the display screen with luminance according to the video signal VS.

FIG. 5 is a schematic diagram showing the configuration of PDP 11 shown in FIG. As shown in FIG. 5, the PDP 11 includes a plurality of address electrodes AD, a plurality of scan electrodes SC, a plurality of sustain electrodes SU, a front glass substrate FP, a back glass substrate BP, and a partition WA.

A plurality of address electrodes AD are arranged in the vertical direction of the screen, and a plurality of scan electrodes SC and a plurality of sustain electrodes SU are arranged in the horizontal direction of the screen. The sustain electrodes SU are commonly connected. A discharge cell CE is formed at each intersection of the address electrode AD, the scan electrode SC, and the sustain electrode SU, and each discharge cell CE forms a pixel on the screen.

The scan electrodes SC and the sustain electrodes SU are formed on the front glass substrate FP in the horizontal direction of the screen so as to form a pair, and are covered with a transparent dielectric layer and a protective layer. On the other hand, the address electrode AD is formed on the back glass substrate BP facing the front glass substrate FP in the vertical direction of the screen, a transparent dielectric layer is formed thereon, and a phosphor is applied thereon. . A partition WA is provided between the address electrodes AD to separate adjacent discharge cells CE. When displaying in color,
The address electrodes AD are provided for each of R, G, and B, and a partition WA is provided between the address electrodes AD.

Front glass substrate FP and back glass substrate BP
Means that the outer periphery is joined and fixed by the sealing glass SG. For this reason, when the temperatures of the front glass substrate FP and the back glass substrate BP rise due to the light emission of the discharge cells CE, cracks are generated near the sealing glass SG of the front glass substrate FP and the back glass substrate BP, and the PDP 11 is damaged. There are many. In the embodiment, in order to control the brightness of the PDP 11 based on the temperature difference of the most fragile portion, the temperature difference estimated value Td is obtained as follows.

Display Screen of PDP 11, That is, Discharge Cell C
Out of the portions where E is formed, at least a portion including the discharge cell CE located at the outermost periphery (for example, a rectangular frame portion indicated by hatching) is defined as an outer periphery adjacent portion NE, and the outer periphery adjacent separator of the temperature difference estimator 4 is used. The video signal in this area is separated by 41, and the separated video signal is integrated by the integration circuit 42 and the heat radiation subtraction circuit 43, thereby obtaining a temperature estimation value Te representing the temperature of the outer peripheral adjacent part NE.

On the other hand, the panel outer peripheral temperature setting device 5 determines the portion of the sealing glass SG of the front glass substrate FP and the rear glass substrate BP and the portion between the outermost discharge cell CE and the sealing glass SG. The outer peripheral portion of the panel is set, and the temperature of this portion is set as a reference value To. Accordingly, the temperature difference estimated value Td of the outer peripheral portion of the display screen is calculated by subtracting the reference value To of the outer peripheral portion of the panel from the estimated value Te of the outer peripheral portion NE. Therefore, by controlling the luminance as described later using the temperature difference estimated value Td representing the temperature difference of the most susceptible part, P can be more reliably determined.
DP11 is prevented from being damaged.

In this embodiment, the PDP 11 corresponds to the display unit, the temperature difference estimator 4 corresponds to the temperature estimating means and the calculating means, and the brightness controller 2, the controller 3, the data driver 12, and the scan driver 13 And the sustain driver 14 corresponds to control means. Further, the outer periphery adjacent separator 41, the integration circuit 42, and the heat radiation subtraction circuit 43 correspond to a temperature estimating unit, and the subtractor 44 corresponds to a calculating unit.

Next, as an example of the gradation display method of the display device configured as described above, the total number of gradations is 256 and 1
A gradation display method using five types of light emission formats in which a field is divided into eight subfields and displayed will be described. The gradation display method to which the present invention is applied is not particularly limited to the following example, and another gradation display method may be used.

FIG. 6 is a diagram showing sub-fields where sustain discharge is to be performed when a display screen is displayed at each gradation level when the total number of gradations is 256. In FIG. 6, each of the subfields SF1 to SF8 is, for example, 1, 2,.
The brightness is weighted in the order of 4, 8, 16, 32, 64 and 128, and each weight is a value proportional to the luminance of the display screen, for example, proportional to the number of times of light emission in each discharge cell.

In FIG. 6, subfields SF1 to SF8 used to cause discharge cells to emit light at each gradation level are shown.
Is indicated by ○. For example, the subfield SF1 (weight 1) may be used to emit the discharge cell at the gray level 1, and the subfield SF1 and the subfield SF2 (weighted 1) may be used to emit the discharge cell at the gray level 3. 2) may be used, and a circle is added to the corresponding column of each subfield. As described above, if the discharge cells are caused to emit light by the number of times of light emission according to the weighting by combining the respective sub-fields, it is possible to perform gradation display at each gradation level from 0 to 255. Note that the number of subfield divisions, weighting, and the like are not particularly limited to the above example, and various changes are possible.

Next, as one example of the light emission format using the subfields SF1 to SF8 weighted as described above, five light emission formats in which the total number of gradations is 256 will be described.

FIG. 7 is a diagram showing the number of light emission pulses in each of the subfields SF1 to SF8 of the five light emission formats A to E. Each of the light emission formats A to E is determined by the controller 2 according to the magnitude of the temperature difference estimated value Td, and is specified by the light emission pulse control signal EC, as described later.

In the light emission format A, the total number of light emission pulses is 1275.
5 in the subfield SF1, and 10 in the subfield SF2. Similarly, 20, 40, 80, and 16 in each of the subfields SF3 to SF8.
Zero, 320, and 640 light emission pulse numbers are assigned.

The light emission type B has a total light emission pulse number of 1020.
The light emitting format C has a total number of pulses of 765, the light emitting format D has a total number of pulses of 510, and the light emitting format E has a total number of pulses of 255. The number of emission pulses as shown in the figure is assigned to SF8.

Therefore, each of subfields SF1 to SF
When 256 gradations are displayed by combining F8, even at the same gradation level, the number of light emission pulses is different depending on each of the light emission formats A to E, and the luminance is different. That is, assuming that the luminance of the light emission format E is a reference (1 time), the luminance of the light emission format D is twice the luminance of the light emission format E, and the luminance of the light emission format C is 3 times that of the light emission format E.
The luminance of the light emitting format B is four times that of the light emitting format E, and the luminance of the light emitting format A is five times that of the light emitting format E. Therefore, by sequentially switching the light emission format from the light emission format A to the light emission format E, the luminance of the display screen can be reduced without changing the total number of gradations much.

Next, the temperature difference estimated value Td and the multiplication coefficient k in the case of performing the sustain discharge by combining the above light emission types A to E are described.
Will be described. FIG. 8 is a diagram illustrating a relationship between the estimated temperature difference value Td and the multiplication coefficient k when the sustain discharge is performed by combining the light emission types A to E. The relationship between the estimated temperature difference Td and the multiplication coefficient k shown in FIG. 8 is stored in the controller 3 in advance, and the light emission format and the multiplication coefficient k corresponding to the estimated temperature difference Td estimated by the temperature difference estimator 4.
Are specified by the controller 3.

As shown in FIG. 8, in the light emission format A, the multiplication coefficient k linearly decreases from 1.0 to 0.8 as the estimated temperature difference Td increases. Next, in the light emission format B, as the temperature difference estimated value Td increases, the multiplication coefficient k decreases from 1.0 to 0.75. Next, in the light emission format C, as the temperature difference estimated value Td increases, the multiplication coefficient k
Decreases from 1.0 to 0.67. Next, as the temperature difference estimated value Td increases in the light emission format D, the multiplication coefficient k
Decreases from 1.0 to 0.5. Finally, as the temperature difference estimated value Td increases in the light emission format E, the multiplication coefficient k
Decreases from 1.0.

Here, the reason why the multiplication coefficient is reduced from 1.0 and returned to 1.0 when the light emission format is switched is as follows. That is, the total number of light emission pulses of the light emission type A is 1275, and the total number of light emission pulses of the light emission type B is 10
There are 20 pulses, and the ratio of these pulse numbers is 0.8.
For this reason, when switching from the light emission format A to the light emission format B, the multiplication coefficient k is switched from 0.8 to 1.0, so that the number of light emission pulses is maintained at a fixed rate before and after the switch in accordance with the temperature difference estimated value Td. Can be reduced by
The brightness of the display screen can be controlled linearly. The same applies to the subsequent switching of each light emission format.

As described above, by switching the multiplication coefficient k according to the total number of light emission pulses when the light emission format is switched,
Even when an image is displayed using a different light emission format, it is possible to linearly control the luminance of the display screen according to the temperature difference estimated value Td, and to reduce the luminance without drastically reducing the total number of gradations. Can be reduced.

When the video signal VS is multiplied by the above multiplication coefficient k and an image is displayed using the video signal VS, as shown in FIG. 9, the temperature difference estimated value Td increases and the luminance after control becomes It decreases linearly, and the brightness of the display screen can be reduced according to the estimated temperature difference Td. Note that FIG.
In the example, when the luminance is not reduced, that is, when the temperature difference estimated value Td is 0, the luminance is displayed as 5 (relative value).

The light emission format is not particularly limited to the above example, and the sustain discharge may be performed using only the light emission type A among the above light emission types A to E. FIG. 10 is a diagram illustrating a relationship between the estimated temperature difference Td and the multiplication coefficient k when the light emission format A is used. As shown in FIG. 10, the temperature difference estimated value Td
Is zero, that is, when the temperature has not risen, the multiplication coefficient k is output at 1.0, and the multiplication coefficient k decreases linearly as the temperature difference estimated value Td increases. Therefore, by multiplying the video signal VS by the multiplication coefficient k by the multiplication circuit 21, the brightness of the display screen can be reduced according to the temperature difference estimated value Td, as in the case shown in FIG.

Next, a first luminance control method for the plasma display device configured as described above will be described.

First, in the temperature difference estimator 4, the video signal of the peripheral portion is separated from the video signal VS by the peripheral portion separator 41, and the luminance signal of the video signal of the peripheral portion is integrated by the integration circuit 42. The heat radiation amount subtracting circuit 43 subtracts the heat radiation amount, and the temperature estimation value Te of the outer peripheral adjacent portion is calculated. Next, the temperature estimation value T of the outer periphery adjacent portion is
The reference value To of the outer peripheral portion of the panel set by the panel outer peripheral temperature setting device 5 is subtracted from e, and the estimated temperature difference Td of the outer peripheral portion of the display screen is calculated.

Next, as shown in FIG.
Determines the light emission format and the multiplication coefficient k corresponding to the magnitude of the temperature difference estimated value Td, and the light emission pulse control signal EC corresponding to the determined light emission format and the brightness control signal LC including the determined multiplication coefficient k are determined. Generated.

Next, in the brightness controller 2, the multiplying coefficient k included in the brightness control signal LC is multiplied by the multiplying circuit 21 by the video signal VS, and the video signal whose luminance is controlled in accordance with the multiplying coefficient k is obtained. Created. Next, 1 in which the luminance is controlled by the video signal-subfield correlator 22.
From the video signal of the field, image data is generated for each subfield of a light emission format corresponding to the light emission pulse control signal EC included in the brightness control signal LC, and a data driver drive control signal DS corresponding to this image data is output. You. In addition, the subfield pulse generation unit 23
Scan driver drive control signal CS corresponding to each subfield of the light emission format corresponding to light emission pulse control signal EC
And a sustain driver drive control signal US is created.

Finally, in the display unit 1, the data driver 12 and the scan driver 13 perform address discharge of the corresponding discharge cells in accordance with the data driver drive control signal DS and the scan driver drive control signal CS. 13 and the sustain driver 14, sustain discharge is performed in the discharge cells in which the address discharge has been performed according to the scan driver drive control signal CS and the sustain driver drive control signal US, and the display screen has a brightness controlled according to the multiplication coefficient k. The image is displayed above, and the larger the temperature difference estimated value Td is,
The brightness of the display screen decreases.

As described above, in the present brightness control method, the temperature estimation value Te corresponding to the temperature of the outer peripheral portion of the display screen of the PDP 11 is estimated from the video signal VS, and this temperature estimation value T
e and a reference value To corresponding to the temperature of the outer peripheral portion of the panel, a temperature difference estimated value Td is obtained, and a light emission format and a multiplication coefficient k corresponding to the magnitude of the temperature difference estimated value Td are determined.
The PDP 11 is determined according to the determined light emission format and the multiplication coefficient k.
Is controlling the brightness of the display screen. Therefore, PDP
The brightness can be controlled based on the temperature difference between the outer peripheral portion of the panel which is most influential on the damage of the panel 11 and the outer peripheral adjacent portion closest to the outer peripheral portion of the panel, and the PDP 11 can be more reliably prevented from being damaged. Since only the temperature estimation value Td of the outer periphery adjacent portion is calculated, the calculation amount is reduced,
The processing can be simplified and the processing time can be shortened.

Next, a description will be given of a second brightness control method for the above plasma display device. The second luminance control method is a method of dividing the display screen into a plurality of blocks and controlling the luminance of an outer peripheral block adjacent to the outer periphery of the display screen among the divided blocks. This control method
When the video signal VS corresponding to the outer peripheral block is input to the multiplying circuit 21 by the controller 3, a multiplication coefficient k corresponding to the temperature difference estimated value Td is output, and the video signal corresponding to the inner block other than the outer peripheral block is output. When VS is input to the multiplication circuit 21, 1 is output as the multiplication coefficient k, and the multiplication circuit 21 multiplies the video signal VS by these multiplication coefficients k. in this case,
A vertical synchronizing signal, a horizontal synchronizing signal, and the like are input to the controller 3 via the temperature difference estimator 4, and the display screen is divided using the horizontal synchronizing signal, the vertical synchronizing signal, and the like, and an outer peripheral block is specified.

FIG. 11 is a diagram showing an example of the multiplication coefficient k of each block when the luminance of the outer peripheral block is controlled.
In the following description, a case will be described in which the display screen is divided into five blocks in each of the vertical and horizontal directions and divided into a total of 25 blocks. However, the number of divisions of the display screen is not particularly limited to this example. The value can be appropriately determined according to the number of pixels on the screen and the processing capability of the temperature difference estimator 4 and the controller 3 and the like. Also, in FIG. 11, the outermost peripheral discharge cells are located at the outermost peripheral portion of each outer peripheral block,
The outer frame indicates the outer periphery of the PDP 11.

In the example shown in FIG. 11, the multiplication coefficient k of the outer peripheral block (the hatched block) is set to 0.5, and the multiplication coefficient k of the other inner blocks is set to 1. In this case, the multiplication coefficient k is reduced only in the part of the outer peripheral block that is most likely to be damaged, and the luminance of this part is reduced. Therefore, it is possible to more reliably prevent the PDP 11 from being damaged without lowering the luminance inside the display screen.

Next, a third brightness control method for the above-described plasma display device will be described. The third brightness control method is a method of controlling the brightness of each block so that the brightness of the outer peripheral block is lower than that of the inner block.
According to this control method, when the video signal VS corresponding to the outer peripheral block is input to the multiplying circuit 21 by the controller 3, a multiplication coefficient k corresponding to the temperature difference estimated value Td is output, and the inner blocks other than the outer peripheral block are output. Is multiplied according to the position of each block so that the multiplication coefficient k becomes 1 in the central block when the video signal VS corresponding to is input to the multiplication circuit 21. This is performed by multiplying the video signal VS.

FIG. 12 is a diagram showing an example of the multiplication coefficient k of each block when the luminance of each block is controlled so that the luminance of the outer peripheral block is lower than that of the inner block. In the example shown in FIG. 12, the multiplication coefficient k of the outer peripheral block is set to 0.5, the multiplication coefficient k of the inner block is set to 0.75, and the multiplication coefficient k of the center block is set to 1
Is set to In this case, the luminance of the outermost block, which is most likely to be damaged, is reduced most, and the PDP 11 can be more reliably prevented from being damaged. Also, the multiplication coefficient k
Is gradually reduced toward the outer periphery of the PDP 11, so that a change in luminance due to a change in the multiplication coefficient k is difficult to visually recognize, and deterioration in image quality can be prevented. The change amount of the multiplication coefficient k depending on the block position is
The present invention is not particularly limited to the above example, and various changes such as increasing the size toward the outer peripheral side are possible.

Next, a description will be given of a plasma display device according to a second embodiment of the present invention. FIG.
FIG. 6 is a block diagram illustrating a configuration of a plasma display device according to a second embodiment of the present invention.

In the plasma display device shown in FIG. 13, the display screen of the display unit 1 is divided into a plurality of blocks, and the outer peripheral block temperature difference estimated value is determined for each of the outer blocks adjacent to the outer periphery of the display screen among the divided blocks. T
bd is obtained, and the brightness is controlled using the outer peripheral block temperature difference estimated value Tbd. Therefore, FIG.
1 is different from the plasma display device shown in FIG. 1 in that the temperature difference estimator 4 is changed to a temperature difference estimator 4A for estimating an outer peripheral block temperature difference estimated value Tbd for each outer peripheral block. Since the other points are the same as those of the plasma display apparatus shown in FIG. 1, the same parts are denoted by the same reference numerals, and the description thereof will be omitted below. Only the changed temperature difference estimator 4A will be described in detail. .

FIG. 14 shows the temperature difference estimator 4A shown in FIG.
FIG. 3 is a block diagram showing the configuration of FIG. The difference between the temperature difference estimator 4A shown in FIG. 14 and the temperature difference estimator 4 shown in FIG.
The difference is that a block separator 45 is added between the outer periphery adjacent separator 41 and the integrating circuit 42, and the other points are the same as those of the temperature difference estimator 4 shown in FIG. The reference numerals are used, and the description is omitted below.

As shown in FIG. 14, the block separator 45
Is connected to the outer peripheral adjacent part separator 41, receives the video signal of the outer peripheral adjacent part output from the outer peripheral adjacent part separator 41, separates this video signal into each outer peripheral block adjacent to the outer periphery of the display screen, and Output to the circuit 42. In this case, a vertical synchronizing signal and a horizontal synchronizing signal included in the video signal VS are input to the block separator 45, and an outer peripheral block is extracted using the horizontal synchronizing signal and the vertical synchronizing signal. After the integration circuit 42, each process is executed for each outer peripheral block in the same manner as in the first embodiment, and finally the outer peripheral block temperature difference estimated value Tbd is output from the subtractor 44 for each outer peripheral block.

FIG. 15 shows the estimated temperature value Tb estimated for each outer peripheral block and the estimated temperature difference Tbd for the outer peripheral block.
It is a figure showing an example of. In the following description, a case where the display screen is divided into five in the vertical direction and the horizontal direction and a block adjacent to the outer periphery of the display screen among the divided blocks is set as an outer peripheral block will be described. The number and the like are not particularly limited to this example, and the values can be appropriately determined according to the number of pixels of the display screen and the processing capability of the temperature difference estimator 4A and the controller 3 and the like. In FIG. 15, the outermost peripheral discharge cell is located at the outermost peripheral portion of the outer peripheral block, and the outer frame indicates the outer periphery of the PDP 11.

As shown in FIG. 15A, first, an estimated temperature value Tb is estimated for each outer peripheral block. For example, in the outer peripheral block in the upper left portion of the display screen, the temperature estimated value Tb is 17, the temperature estimated value Tb of the outer peripheral block to the right is 18 and the temperature estimated value Tb of the outer peripheral block to the right is 20. It is. Thus, the temperature estimation value Tb is estimated for each outer peripheral block.

Next, the reference value To is subtracted from each temperature estimated value Tb shown in FIG. In this example, the upper UR
The reference value To for the outer peripheral block included in the two rows
It is set to 0, and the reference value To for the outer peripheral blocks included in the three rows of the lower DR is set to 5. Accordingly, the outer peripheral block temperature difference estimated value Tbd of each outer peripheral block after the subtraction of each reference value is a value shown in FIG. Using this value, the multiplication coefficient k is determined for each outer peripheral block in the same manner as in FIG. 8, and the luminance of each outer peripheral block is controlled according to the multiplication coefficient k.

In general, as shown in FIG. 5, the PDP 11 is provided with a cooling vent or the like at the lower part because the address electrode AD is wired at the upper part, so that the temperature of the upper part is lower than that of the lower part. Easy to rise. Therefore, as described above, by setting a high reference value for the upper UR of the PDP 11 and setting a lower reference value for the lower DR than that of the upper UR, the thermal stress actually generated on the outer peripheral portion of the panel of the PDP 11 can be improved. It is possible to calculate a temperature difference estimated value closer to the above. As a result, the breakage of the PDP 11 can be more reliably prevented, and the brightness is not unnecessarily reduced. Note that the method of controlling the luminance using a plurality of reference values that are different depending on the position of the outer peripheral portion of the panel of the PDP 11 as described above can be similarly applied to other embodiments.

The controller 3 uses the estimated outer peripheral block temperature difference value Tbd for each outer peripheral block obtained as described above to generate a brightness control signal LC so that the luminance is controlled for each outer peripheral block. Output to the brightness controller 2. The brightness controller 2 outputs an address driver drive control signal AD, a scan driver drive control signal CS, and a sustain driver drive control signal US for controlling the brightness of each outer peripheral block according to the brightness control signal LC to the display unit 1. Output to In the display unit 1,
According to the respective brightness control methods described below, the brightness is controlled for each outer peripheral block in accordance with the input drive control signals.

In this embodiment, the temperature difference estimator 4A corresponds to the temperature estimating means and the calculating means, the block separator 45 corresponds to the block extracting means, and the other parts are the first.
This is the same as the embodiment.

Next, a first brightness control method for the plasma display device configured as described above will be described. The first luminance control method estimates a temperature estimated value Tb for each outer peripheral block and calculates a temperature estimated value Tb for each outer peripheral block.
Is subtracted from the reference value To to estimate the outer peripheral block temperature difference T
In this method, bd is obtained, and luminance is controlled for each outer peripheral block in accordance with the outer peripheral block temperature difference estimated value Tbd. Also in this control method, the controller 3 uses the block separator 4
5, the video signal V corresponding to the outer peripheral block separated by
When S is input to the multiplying circuit 21, a multiplication coefficient k corresponding to the outer peripheral block temperature difference estimated value Tbd of each outer peripheral block is output, and the video signal VS corresponding to the inner block other than the outer peripheral block is multiplied by the multiplying circuit 21. Is output as a multiplication coefficient k, and the multiplication circuit k multiplies the video signal VS by the multiplication coefficient k.

FIG. 16 is a diagram showing an example of the estimated outer peripheral block temperature difference value Tbd and the multiplication coefficient k of each outer peripheral block when the luminance is controlled for each outer peripheral block by the above-described first luminance control method.

First, as shown in FIG. 16 (a), it is assumed that the outer peripheral block temperature difference estimated value Tbd is estimated for each outer peripheral block. In other words, it is assumed that the outer peripheral block temperature difference estimated value Tbd of the outer peripheral block located at the center of the upper, lower, left, and right sides of the display screen is 20, and the outer peripheral block temperature difference estimated values Tbd of the other outer blocks are 0. . In this case, the multiplication coefficient k of each outer peripheral block
Is as shown in FIG. 16 (b). That is, the multiplication coefficient k of the outer peripheral block at the center of the upper side, the lower side, the left side, and the right side is 0.5, the multiplication coefficient k of the other outer blocks is 1, and the luminance of each outer peripheral block is controlled according to the multiplication coefficient k. Is done.

In this case, the outer peripheral block temperature difference estimated value Tb
The multiplication coefficient k is reduced only in the peripheral block where d is large,
Only the brightness of this part is reduced. Therefore, only the brightness of the outermost block that is most likely to be damaged is reduced without lowering the brightness of the other blocks, and the PDP 11 can be more reliably prevented from being damaged.

Next, a description will be given of a second luminance control method for the above plasma display device. In the second luminance control method, an outer peripheral block temperature difference estimated value Tbd ′ obtained by performing a filtering process on the outer peripheral block temperature difference estimated value Tbd between adjacent outer peripheral blocks so that the luminance control amount between adjacent outer peripheral blocks changes smoothly. Is used to control the luminance for each outer peripheral block. In this control method, the controller 3 performs filtering processing such as integration or interpolation on the outer peripheral block temperature difference estimated value Tbd between adjacent outer peripheral blocks, and performs a multiplication coefficient k according to the outer peripheral block temperature difference estimated value Tbd ′ after the filtering processing. Is output, and the multiplication coefficient k is multiplied by the multiplication coefficient by the video signal VS corresponding to the outer peripheral block.

FIG. 17 shows an estimated value Tbd of the outer peripheral block temperature difference of each outer peripheral block when the luminance is controlled for each outer peripheral block so that the luminance control amount changes smoothly by the above-mentioned second luminance control method. It is a figure which shows an example of the subsequent outer peripheral block temperature difference estimation value Tbd 'and the multiplication coefficient k.

First, as shown in FIG. 16A, it is assumed that the outer peripheral block temperature difference estimated value Tbd is estimated for each outer peripheral block as shown in FIG. next,
Estimated outer peripheral block temperature difference T between adjacent outer peripheral blocks
bd is filtered by interpolation, and the outer peripheral block temperature difference estimated value Tbd ′ after the filtering processing is obtained as shown in FIG.
(B). The outer peripheral block temperature difference estimated value Tbd of the outer peripheral block between the outer peripheral block whose outer peripheral block temperature difference estimated value Tbd is 20 and the outer peripheral block whose outer peripheral block temperature difference estimated value Tbd is 0 is interpolated from 0 to 10. In this case, the multiplication coefficient k of each outer peripheral block is as shown in FIG. That is, the multiplication coefficient k of the outer peripheral block at the center of the upper side, the lower side, the left side, and the right side
Is 0.5, the multiplication coefficient k of the outer peripheral block located at each vertex of the display screen is 1, the multiplication coefficient k of the intermediate outer block is 0.75, and the change of the multiplication coefficient k becomes smooth. The luminance of each outer peripheral block is controlled according to the coefficient k.

In this case, the luminance of the outermost block which is most likely to be damaged is reduced most, and the thermal stress in the outermost block also changes smoothly, so that the PDP 11 can be more reliably prevented from being damaged. Further, since the multiplication coefficient k changes smoothly in steps, the multiplication coefficient k
Changes in brightness due to changes in
Image quality can be prevented from deteriorating. Note that the change of the multiplication coefficient k by the filtering process is not particularly limited to the above example, and various changes such as changing exponentially are possible.

Next, a description will be given of a plasma display device according to a third embodiment of the present invention. FIG.
FIG. 9 is a block diagram illustrating a configuration of a plasma display device according to a third embodiment of the present invention.

In the plasma display device shown in FIG. 18, the display screen of the display unit 1 is divided into a plurality of blocks, and the outer peripheral block temperature difference estimated value is determined for each of the outer peripheral blocks adjacent to the outer periphery of the display screen among the divided blocks. T
bd is obtained, a maximum outer peripheral block temperature difference estimated value Tmax is extracted from the outer peripheral block temperature difference estimated value Tbd, and luminance is controlled using the maximum outer peripheral block temperature difference estimated value Tmax. Therefore, the difference between the plasma display device shown in FIG. 18 and the plasma display device shown in FIG. 13 is that the temperature difference estimator 4A estimates the outer peripheral block temperature difference estimated value Tbd for each outer peripheral block and estimates the maximum outer peripheral block temperature difference. This is a point changed to the temperature difference estimator 4B for extracting the value Tmax.
3 is similar to the plasma display device shown in FIG.
The same portions are denoted by the same reference numerals, and the description thereof will be omitted below.
Only the changed temperature difference estimator 4B will be described in detail.

FIG. 19 shows the temperature difference estimator 4B shown in FIG.
FIG. 3 is a block diagram showing the configuration of FIG. The difference between the temperature difference estimator 4B shown in FIG. 18 and the temperature difference estimator 4A shown in FIG. 14 is that a maximum value selector 46 is added after the subtractor 44, and the other points are shown in FIG. Since it is the same as the temperature difference estimator 4A shown, the same portions are denoted by the same reference numerals and description thereof will be omitted below.

As shown in FIG. 19, the maximum value selector 46
Is connected to the subtractor 44 and is the largest estimated outer peripheral block temperature difference Tbd from the estimated outer peripheral block temperature difference Tbd of each outer peripheral block in one field output from the subtracter 44, that is, in one display screen. Is selected as the maximum peripheral block temperature difference estimated value Tmax.

FIG. 20 is a diagram showing an example of the estimated temperature value Tb, estimated temperature value Tbd of the outer peripheral block, and estimated value Tmax of the maximum peripheral block temperature estimated for each outer peripheral block.

As shown in FIG. 20A, it is assumed that the temperature estimation value Tb is estimated for each outer peripheral block in the same manner as in FIG. 15A. Next, as shown in FIG. 20B, the outer peripheral block temperature difference estimated value Tbd of each outer peripheral block is obtained as in FIG. 15B. Finally, FIG.
The outer peripheral block at the lower left corner having the largest estimated outer peripheral block temperature difference Tbd (13 in the example of FIG. 20) is selected from the outer peripheral block temperature difference estimated values Tbd shown in FIG.
The outer peripheral block temperature difference estimated value Tbd of the outer peripheral block 13 is the maximum outer peripheral block temperature difference estimated value Tmax.

As a result, as shown in FIG.
Peripheral block temperature difference estimated value Tb of all peripheral blocks
d is replaced with the maximum outer peripheral block temperature difference estimated value Tmax. This maximum outer peripheral block temperature difference estimated value Tma
The multiplication coefficient k is determined for each outer peripheral block in the same manner as in FIG. 8 using x, and the luminance of each outer peripheral block is controlled according to the multiplication coefficient k.

The controller 3 uses the maximum outer peripheral block temperature difference estimated value Tmax obtained as described above,
A brightness control signal LC is output to the brightness controller 2 so that brightness control is performed for each outer peripheral block. The brightness controller 2 outputs an address driver drive control signal AD, a scan driver drive control signal CS, and a sustain driver drive control signal US for controlling the brightness of each outer peripheral block according to the brightness control signal LC to the display unit 1. Output to In the display unit 1, the brightness is controlled in accordance with the input drive control signals.

In the present embodiment, the temperature difference estimator 4B corresponds to the temperature estimating means and the calculating means, and the other parts are the same as in the second embodiment.

In the plasma display device configured as described above, the brightness control method of each of the above embodiments can be used similarly, and the same effect can be obtained.

Further, in this embodiment, since the luminance is controlled using the maximum outer peripheral block temperature difference estimated value Tmax having the largest temperature difference in the outer peripheral block, the PDP 11 can be more reliably prevented from being damaged. With
Since the luminance is controlled by one maximum outer peripheral block temperature difference estimated value, the luminance control process is simplified.

Next, a plasma display device according to a fourth embodiment of the present invention will be described. FIG.
FIG. 14 is a block diagram illustrating a configuration of a plasma display device according to a fourth embodiment of the present invention.

The difference between the plasma display device shown in FIG. 21 and the plasma display device shown in FIG.
The point to which the temperature measuring unit 6 is added is shown in FIG.
Is the same as that of the plasma display device shown in FIG.

As shown in FIG. 21, the temperature measuring section 6 is connected to the panel outer peripheral temperature setting device 5, directly measures the temperature of the panel outer peripheral portion of the PDP 11, and outputs the measured temperature to the panel outer peripheral temperature setting device 5. Output to The panel outer peripheral temperature setter 5 sets a reference value To corresponding to the measured temperature and outputs the same to the temperature difference estimator 4, and thereafter, the subsequent processing is performed in the same manner as in the first embodiment. The brightness is controlled.

In this embodiment, the panel outer peripheral temperature setting device 5 and the temperature measuring section 6 correspond to measuring means, and the other portions are the same as those in the first embodiment.

In the plasma display device configured as described above, the brightness control method of the first embodiment can be used similarly, and the same effect can be obtained.
Also, when the temperature measurement unit 6 of the present embodiment is used in another embodiment, the brightness control method of the other embodiment can be used similarly, and the same effect can be obtained.

In this embodiment, the temperature of the outer peripheral portion of the panel is directly measured, and the luminance can be controlled based on the reference value To corresponding to the temperature. Even if it changes, it is possible to reliably prevent the PDP 11 from being damaged. The temperature measurement unit 6
The measurement point may be one point or a plurality of points on the outer peripheral portion of the panel.
When a plurality of points are measured, a reference value may be set for each measurement point, or a reference value may be set for an average value obtained by averaging the measurement results of the plurality of points.

In each of the above embodiments, the video signal VS is multiplied by the multiplication coefficient k included in the brightness control signal LC output from the controller 3 by the multiplication circuit 21.
Although the brightness was controlled, the multiplying circuit 21 was changed to a limiting circuit for limiting the maximum brightness of the video signal, and a maximum brightness upper limit value corresponding to the estimated temperature difference was output from the controller 3. The maximum brightness of the image displayed on the PDP may be reduced by limiting only the brightness exceeding the brightness upper limit value.

[0128]

According to the present invention, the luminance is determined according to the temperature difference estimated value obtained from the temperature estimated value corresponding to the temperature of the display screen of the display unit and the reference value corresponding to the temperature of the outer peripheral portion of the display unit. Is controlled, the brightness can be controlled based on the temperature difference between the outer peripheral portion and the display screen, which has the greatest influence on the damage to the display section, and the display section can be more reliably prevented from being damaged.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a plasma display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a temperature difference estimator shown in FIG. 1;

FIG. 3 is a block diagram showing a configuration of a brightness controller shown in FIG. 1;

FIG. 4 is a block diagram showing a configuration of a display unit shown in FIG.

FIG. 5 is a schematic diagram showing the configuration of the PDP shown in FIG.

FIG. 6 is a diagram showing subfields used for each gradation level when displaying an image with 256 gradations.

FIG. 7 is a diagram showing the number of light emission pulses in each subfield according to different light emission formats.

8 is a diagram showing a relationship between a temperature difference estimated value and a multiplication coefficient when the light emission formats A to E shown in FIG. 7 are used.

9 is a diagram showing a relationship between the temperature difference estimated value and the luminance after control when the temperature difference estimated value and the multiplication coefficient shown in FIG. 8 are used.

10 is a diagram showing a relationship between a temperature difference estimated value and a multiplication coefficient when the light emission format A shown in FIG. 7 is used.

11 is a second view of the plasma display device shown in FIG.
For explaining the brightness control method of FIG.

FIG. 12 shows a third example of the plasma display device shown in FIG.
For explaining the brightness control method of FIG.

FIG. 13 is a block diagram showing a configuration of a plasma display device according to a second embodiment of the present invention.

FIG. 14 is a block diagram illustrating a configuration of a temperature difference estimator illustrated in FIG. 13;

FIG. 15 is a diagram illustrating an example of a temperature estimation value and an estimation value of an outer peripheral block temperature difference estimated for each outer peripheral block;

16 is a diagram showing an example of an outer peripheral block temperature difference estimated value and a multiplication coefficient according to the first luminance control method of the plasma display device shown in FIG.

17 is a diagram showing an example of an outer peripheral block temperature difference estimated value, an outer peripheral block temperature difference estimated value after filtering processing, and a multiplication coefficient according to the second luminance control method of the plasma display device shown in FIG. 13;

FIG. 18 is a block diagram showing a configuration of a plasma display device according to a third embodiment of the present invention.

FIG. 19 is a block diagram illustrating a configuration of a temperature difference estimator illustrated in FIG. 18;

FIG. 20 shows a temperature estimation value estimated for each outer peripheral block,
The figure which shows an example of an outer peripheral block temperature difference estimated value and the maximum outer peripheral block temperature difference estimated value.

FIG. 21 is a block diagram showing a configuration of a plasma display device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Display part 2 Brightness controller 3 Controller 4 Temperature difference estimator 5 Panel outer peripheral temperature setting device 6 Temperature measuring part 11 PDP 12 Data driver 13 Scan driver 14 Sustain driver 21 Multiplier circuit 22 Video signal-subfield matching device 23 Sub-field pulse generator 41 Perimeter outer separator 42 Integrator 43 Heat radiation subtractor 44 Subtractor 45 Block separator 46 Maximum value selector FP Front glass substrate BP Back glass substrate AD Address electrode SC Scan electrode SU Sustain electrode SG Seal Glass-coated SE discharge cell

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-11-288244 (JP, A) JP-A-11-231828 (JP, A) JP-A-11-194745 (JP, A) JP-A-11-288 212517 (JP, A) JP-A-9-288467 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09G 3/00-3/38 PCI (DIALOG) WPI (DIALOG)

Claims (13)

(57) [Claims] A display unit configured to display an image with luminance according to a video signal input from the outside; a display unit including an outer peripheral portion adjacent to the display screen; Temperature estimating means for estimating a corresponding temperature estimated value; calculating means for obtaining a temperature difference estimated value using a reference value corresponding to the temperature of the outer peripheral portion and the temperature estimated value; and displaying the display screen in a plurality of blocks. Control means for dividing the plurality of blocks and extracting an outer peripheral block adjacent to the outer periphery of the display screen, and controlling the luminance of the outer peripheral block to decrease in accordance with an increase in the temperature difference estimation value. Display device. 2. A display screen for displaying an image at a luminance according to a video signal input from the outside, a display unit comprising an outer peripheral portion adjacent to the display screen, and a temperature of the display screen from the video signal. Temperature estimating means for estimating a corresponding temperature estimated value; calculating means for obtaining a temperature difference estimated value using a reference value corresponding to the temperature of the outer peripheral portion and the temperature estimated value; Is divided into a plurality of blocks, and an outer peripheral block adjacent to the outer periphery of the display screen is extracted from the plurality of blocks, and control is performed such that the luminance of the outer peripheral block is lower than that of the inner block of the display screen. A display device comprising: 3. A display unit for displaying an image with luminance according to a video signal input from the outside, a display unit comprising an outer peripheral portion adjacent to the display screen, and dividing the display screen into a plurality of blocks. A block extracting means for extracting an outer peripheral block adjacent to the outer periphery of a display screen from the plurality of blocks; and a temperature estimator for estimating a temperature estimation value corresponding to the temperature of the display screen from the video signal for each outer peripheral block. Means, calculating means for obtaining an outer peripheral block temperature difference estimated value using a reference value corresponding to the temperature of the outer peripheral portion and the temperature estimated value estimated for each outer peripheral block, and the control means, the outer peripheral block Control means for controlling luminance for each of the outer peripheral blocks based on the estimated temperature difference. 4. A display unit comprising: a display screen for displaying an image with luminance according to a video signal input from the outside; a display unit comprising an outer peripheral portion adjacent to the display screen; and dividing the display screen into a plurality of blocks. A block extracting means for extracting an outer peripheral block adjacent to the outer periphery of a display screen from the plurality of blocks; and a temperature estimator for estimating a temperature estimation value corresponding to the temperature of the display screen from the video signal for each outer peripheral block. An outer peripheral block temperature difference for each outer peripheral block from a temperature estimated value estimated for each outer peripheral block using a reference value corresponding to the temperature of the outer peripheral portion and the temperature estimated value estimated for each outer peripheral block. Calculating an estimated value, extracting a maximum outer peripheral block temperature difference estimated value from the outer peripheral block temperature difference estimated value, and calculating an outer peripheral block temperature difference estimated value; Serial display and control means for controlling the brightness of an image displayed on the display unit based on the maximum outer peripheral block temperature difference estimated value. 5. The control means controls the luminance of each of the outer peripheral blocks based on the outer peripheral block temperature difference estimation value such that a luminance control amount between adjacent outer peripheral blocks changes smoothly. The display device according to claim 1. 6. The display device according to claim 1, wherein the reference value includes a plurality of reference values that differ depending on a position of an outer peripheral portion of the display unit. 7. The apparatus according to claim 1, further comprising a measuring unit that measures a temperature of an outer peripheral portion of the display unit and outputs a reference value corresponding to the measured temperature to the arithmetic unit.
The display device according to any one of the above. 8. The temperature estimation unit according to claim 1, wherein the temperature estimating unit estimates a temperature estimation value corresponding to a temperature of an outer peripheral portion in a display screen adjacent to the outer peripheral portion. Display device. 9. The display section includes a first and a second substrate to which outer peripheries are bonded, and a plurality of light-emitting devices that form the display screen formed between the first and the second substrates. An outer peripheral portion of the display unit includes a portion between a light emitting element located at an outermost periphery of the display screen and a joint between the first and second substrates. The display device according to any one of claims 1 to 8. 10. The temperature estimating means estimates the temperature estimated value by integrating data relating to luminance from the video signal and subtracting a heat radiation amount, and the calculating means calculates the reference value from the temperature estimating means. The display device according to any one of claims 1 to 9, wherein the temperature difference estimation value is obtained by subtracting the temperature difference. 11. The apparatus according to claim 1, wherein the control unit decreases the maximum luminance of an image displayed on the display unit according to an increase in the temperature difference estimation value. Display device. 12. The display screen displays an image at a gradation corresponding to the video signal from among a plurality of gradations, and the control unit displays the image at the same ratio for each gradation. The display device according to claim 1, wherein brightness of an image is reduced. 13. The display unit displays an image at a gradation corresponding to the video signal in a plurality of light emission formats having the same total number of gradations and different numbers of light emission pulses in each gradation. The brightness of an image displayed on the display unit is controlled using a light emission format selected from the plurality of light emission formats according to the temperature difference estimation value. The display device according to claim 1.