JP4792788B2 - Temperature information detection method, display device, temperature information detection device, and program - Google Patents

Description

  One embodiment of the present invention relates to a method for detecting a temperature distribution in a light emitting region in which self-emitting elements are arranged in a matrix. One embodiment of the present invention relates to a temperature distribution detection device and a display device equipped with the same. Moreover, one form of invention is related with the program which makes a computer perform the temperature distribution detection function.

Flat panel displays are widely used in products such as computer displays, portable terminals, and televisions. Currently, many liquid crystal display panels are mainly used. However, the narrow viewing angle and slow response speed of the liquid crystal display panel continue to be pointed out.
On the other hand, an organic EL display formed of a self-luminous element can overcome the above-described viewing angle and responsiveness problems, and can achieve a thin form, high brightness, and high contrast that do not require a backlight. Therefore, it is expected as a next-generation display device that replaces the liquid crystal display.

By the way, it is known that organic EL elements and other self-light-emitting elements have characteristics that deteriorate in accordance with the light emission amount and the light emission time. At the same time, it is known that the degradation rate of these elements varies depending on the temperature of the elements themselves.
Since the self-luminous element is a self-luminous type, it generates heat during operation. And, as the higher luminance is realized, a larger amount of current is required, and heat is generated at a higher temperature. As a result, the higher the temperature, the faster the deterioration.
Therefore, appropriate temperature control is required to realize a long life of the organic EL display.

An example of the temperature control method currently proposed is shown below.
JP, 2003-295776, A This art discloses the technique which controls a temperature regulator based on the temperature detected from a light emitting element, and the information which assumed transition of a temperature rise. That is, a technique for uniformly adjusting the temperature in the light emitting surface by heating or cooling the regionized portion is disclosed. In this document, based on the detected ambient temperature, the temperature characteristic of the voltage-current characteristic of the light-emitting element is referred to, and the display data value is corrected so as to obtain an appropriate luminance. Is disclosed.

  However, these technologies require that an element structure for detecting the surface temperature and an element structure for detecting the environmental temperature be mounted on the display panel. For this reason, there is a problem that the structure of the display panel becomes complicated.

The inventors propose a method for detecting a temperature distribution in a light emitting region in which self-emitting elements are arranged in a matrix without using these element structures.
That is, a method having the following processing functions is proposed.
(1) Processing to divide display signal into block areas to which corresponding pixels belong (2) Processing to calculate light emission amount for each block area based on display signal after region formation (3) Light emission amount to each block area This technology can be realized not only as hardware but also as software. Of course, part of the processing can be executed as hardware, and the remaining processing can be executed as software.

  If this invention is used, even if it does not mount a temperature detection element, the temperature distribution in a light emission area | region can be detected. For this reason, the structure of the light emitting region and the display device can be simplified. Further, even for a display device that does not include a temperature detection element, it is possible to detect the temperature distribution in the light emitting region.

Hereinafter, an embodiment of a temperature distribution detection technique that employs the technical technique according to the invention will be described. Here, a case where the in-plane temperature distribution of the organic EL panel is calculated 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) Temperature distribution detection device (a) Device configuration FIG. 1 shows a configuration example of a temperature distribution detection device. The temperature distribution detection apparatus 1 includes a gray scale conversion unit 3, a regionizing unit 5, a light emission amount calculation unit 7, and a temperature calculation unit 9 as main components.
The gray scale conversion unit 3 is a processing device that converts a color image signal into a gray scale signal.
In this embodiment, the color image signal is an R (red) signal, a G (green) signal, and a B (blue) signal corresponding to the three primary colors of light. In addition to these, when complementary color signals are used, these color signals are also included. The color image signal is a digital signal.

Gray scale conversion is realized by a weighting calculation using a current ratio (temperature ratio) flowing through each single color pixel constituting one pixel on display during white display as a weighting coefficient.
FIG. 2 shows a configuration example of one pixel on the display. FIG. 2 shows a case where one pixel on the display is composed of three colors of a red pixel (R), a green pixel (G), and a blue pixel (B).
FIG. 3 shows the calculation principle of gray scale conversion. FIG. 3A shows the ratio of current flowing through each single color pixel when luminance information (white component) is expressed by one pixel on the display. As shown in the figure, the current value flowing through the red pixel (R): the current value flowing through the green pixel (G): the current value flowing through the blue pixel (B) is given by 5: 3: 2.

This current ratio also corresponds to the temperature ratio of each pixel. This is because the temperature of the organic EL element is proportional to the amount of current.
FIG. 3B is a formula for calculating a gray scale signal. As shown in FIG. 3B, the gray scale signal is a weighted calculation of the display signal (for example, gradation value) of each single color pixel constituting one pixel on the display at a ratio of 5: 3: 2. Is calculated by
By this arithmetic processing, the color image signal is converted into a gray scale signal reflecting temperature information.

The regionizing unit 5 is a processing device that divides a grayscale signal into block areas to which corresponding pixels belong. Note that the corresponding pixel is one pixel on display. This block area is a unit for calculating temperature information.
FIG. 4A shows an example of region formation. In this example, the light emitting area is divided into block areas of 5 pixels × 5 pixels.
In FIG. 4A, one pixel on the display is surrounded by a broken line, and a block area is indicated by a solid line (thick line). Here, the case where the gradation value is given by 8 bits is shown. That is, the case where the gradation value is given as a value from 0 to 255 is shown. Therefore, the numerical value of the pixel is the grayscale signal gradation value.

In FIG. 4A, the block area is divided with the upper left corner in the figure as a base point. For this reason, a block area of 3 pixels × 5 pixels and a block area of 5 pixels × 2 pixels are generated at the right end portion and the lower end portion in the drawing.
The light emission amount calculation unit 7 is a processing device that calculates the light emission amount for each block area based on the grayscale signal after the region. The light emission amount calculation unit 7 includes a set of computing units that calculate the light emission amount of each block area.
In the case of this embodiment, the computing unit calculates the light emission amount of each block area as an average gradation value APLi of each pixel constituting the block area. The variable i is a frame identification number.
FIG. 4B shows the calculation result of the average gradation value. Each block area in FIG. 4B corresponds to each block area in FIG.
In the case of FIG. 4B, the average gradation value of the block area located at the left end of the uppermost stage is “92”, and the average gradation value of the block area located right next to it is “104”.

FIG. 5 shows a basic configuration example of the light emission amount calculation unit 7.
FIG. 5 shows an example in which arithmetic units are arranged in the number of block areas. In the case of FIG. 5, a total of 5 × n arithmetic units are mounted, five in the vertical direction and n in the horizontal direction.
In the case of this configuration, it is possible to calculate an average gradation value for all block areas constituting one frame at a time.
However, the configuration shown in FIG. 5 increases the system scale depending on the number of block areas. In such a case, an improved light emission amount calculation unit 7 as shown in FIG. 6 is used.
The light emission amount calculation unit 7 shown in FIG. 6 corresponds to a method in which calculators are arranged as many as the number of block areas for one line in the horizontal direction, and the average gradation value in the block area is calculated in units of one line.
In the case of this example, since the number of block areas in the vertical direction is 5, the number of computing units can be reduced to n, which is 1/5.
When this configuration is adopted, the average gradation value calculated for each line is sequentially stored in a memory (not shown) until the calculation for all lines is completed.

The temperature calculation unit 9 is a processing device that converts the calculated light emission amount into temperature information of each block area.
In the temperature calculation unit 9, three processes are executed. One is a process of accumulating the calculated light emission amount for a certain period in block area units to calculate the accumulated light emission amount Sj. Another one is processing for obtaining a temperature rise degree from the accumulated light emission amount Sj. The remaining one is a process of calculating the temperature for each block area using the obtained temperature rise degree.
Here, the cumulative light emission amount Sj is obtained as a cumulative value ΣAPLi (i = 1,..., N) of average gradation values calculated for each frame.
The variable j is a serial number assigned to the storage period of the average gradation value APL. The variable n is the number of accumulated frames. The number of frames is selected in units of several frames, seconds, minutes, etc.

For this reason, the temperature calculation unit 9 is equipped with a storage device having a storage capacity of at least n frames.
FIG. 7 shows a calculation image of the accumulated light emission amount Sj. For example, in the first APL storage period, the cumulative light emission amount S1 for the n average gradation values APL1 to APLn from the first to the nth frame is calculated. Further, for example, in the second APL storage period, the cumulative light emission amount S2 for the n average gradation values APL2 to APLn + 1 from the second to the (n + 1) th frame is calculated. The same applies hereinafter.

Further, the temperature calculation unit 9 refers to the conversion table storing the relationship between the accumulated light emission amount Sj and the temperature rise degree, and converts the accumulated light emission amount Sj obtained for each block area into the temperature rise degree. The temperature rise degree here is a value indicating how much the temperature rises when the current light emission state continues for a certain time.
FIG. 8 shows an example of the conversion table. This conversion table indicates that the temperature rises once when the state where the accumulated light emission amount Sj is “0 to 1000” continues for a certain period. Further, when the state where the accumulated light emission amount Sj is “1001 to 2000” continues for a certain period, the temperature rises by 1.5 degrees.
The temperature calculation unit 9 calculates the temperature of each block area based on the converted temperature rise degree. For example, the temperature rise degree converted per frame is integrated, and the temperature corresponding to the light emission period is calculated. Note that the temperature of the entire light emitting region is obtained by calculating the cumulative light emission amount Sj in units of frames.

(B) Calculation Operation FIG. 9 shows a series of processing procedures executed by the temperature distribution detection device 1.
First, the temperature distribution detection apparatus 1 converts the color image signal of each frame into a gray scale signal (P1). The gray scale signal is obtained as an average value obtained by weighting each color component based on the ratio of current flowing through each single color pixel during white display.
Next, the temperature distribution detection device 1 divides the grayscale signal into block areas, and calculates the gradation average value APLi for each block area (P2, P3).
Subsequently, the temperature distribution detection device 1 calculates the cumulative light emission amount Sj of the gradation average value APLi, and obtains the temperature rise degree of each block area (P4, P5).
Thereafter, the temperature distribution detection device 1 integrates the temperature rise per frame obtained for each frame, and calculates the temperature of each block area (P6).
This process is repeated for each frame.

(C) Effects of Embodiments Using this temperature distribution detection device 1, the temperature distribution in the light emitting region can be detected without using any temperature detection element. That is, a general-purpose product can be used for the organic EL panel. The manufacturing cost can be reduced accordingly.
Further, the temperature distribution detection device 1 can realize a further reduction in circuit scale by devising the arrangement of computing units that calculate the light emission amount of each block area.
In addition, if the detected temperature distribution is used for temperature control for each block area or temperature control for the entire light emitting region, the life of the organic EL panel can be extended.

(B) Example of Mounting on Panel Module FIG. 10 shows an example of mounting the temperature distribution detecting device on the panel module 11. The panel module 11 includes a light emitting region 13 (a region where organic EL elements are arranged in a matrix) and image drive circuits 15, 17, and 19 that control image display.
The image driving circuit includes a timing generator 15, a data driver 17, and a gate driver 19. Note that the image driving circuit is formed in the periphery of the light emitting region. An existing circuit configuration is applied to these image driving circuits.
FIG. 10 shows a case where the temperature distribution detection device 1 is mounted as a part of the timing generator 15. In this case, the temperature information of each block area is output to the external device through the output terminal 21.
Note that the image driving circuit may be mounted on the panel substrate as a semiconductor integrated circuit, or may be directly formed on the panel substrate using a semiconductor process.

(C) Usage Example of Temperature Distribution Detection Device The temperature distribution detection device can be used externally to the display device in addition to the method of mounting and using the display device as described above.
For example, as shown in FIG. 11, a technique may be employed in which an input display signal that gives a display image via the output terminal 31 </ b> A of the display device 31 is taken into the temperature distribution detection device 33. In this case, the temperature distribution can be detected even for a display device not equipped with the temperature distribution detection device 1.
Further, for example, as shown in FIG. 12, a method may be adopted in which an input display signal input to the display device 31 is branched and input to the temperature distribution detection device 33. Also in this case, temperature distribution can be detected for a display device that does not include the temperature distribution detection device 1.
Although not shown, it is also possible to use only the temperature distribution detection device alone and use it as a simulator for predicting changes in temperature distribution according to the input display signal.

(D) Other Embodiments (a) In the embodiment described above, the case where the gray scale conversion unit 3 is mounted on the temperature distribution detection device 1 has been described.
However, when a signal that has already been subjected to grayscale conversion is input, a configuration in which the grayscale conversion unit 3 is not mounted may be used.
(B) In the above-described embodiment, the case has been described in which the temperature distribution detection device executes up to the process of calculating the temperature (temperature information) of each block area.
However, the temperature distribution detection apparatus may execute a method up to the calculation of the temperature rise degree (temperature information) and calculate the temperature of the corresponding block area by another circuit unit.

(C) In the above-described embodiment, the case where the gradation value is given by 8 bits has been described.
However, the number of bits giving the gradation value may be other than 8 bits. For example, the present invention can be applied to other cases such as 10 bits, 12 bits, and the like.
(D) In the above embodiment, the case where the temperature distribution calculation unit is mounted as a part of the timing generator 15 has been described.
However, the mounting position of the temperature distribution calculation unit is not limited to this.
(E) In the above-described embodiment, the case where the self-luminous element is an organic EL element has been described. However, any self-luminous element in which the in-plane temperature of the display panel is proportional to the amount of current flowing through the pixel can be widely applied to display panels composed of other than organic EL elements.

(F) In the above-described embodiment, a total of 25 pixel areas each including five pixels in the horizontal direction and the vertical direction are set as block areas. However, the number of pixels in the horizontal direction and the vertical direction constituting the block area is arbitrary.
(G) In the above-described embodiment, the display device incorporating the temperature distribution detection device has been described. This display device may be in the form of a single product or may be mounted as part of another image processing device. For example, video cameras, digital cameras and other imaging devices (including not only camera units but also those integrated with a recording device), information processing terminals (portable computers, mobile phones, portable game machines) , Electronic notebook, etc.) and display devices for game machines.
(H) In the above-described embodiment, the case where the temperature distribution detection device is built in the display device has been described. However, the temperature distribution detection device may be mounted on the image processing device that supplies an input display signal to the display device.

(I) In the above-described embodiment, the case where the arithmetic unit is mounted as hardware has been described.
However, the function of this arithmetic unit may be realized by software processing.
(J) In the above-described embodiment, the functional configuration of the in-plane temperature adjusting device has been described, but it goes without saying that an equivalent function can be realized as hardware or software.
Further, not only all the functions constituting the in-plane temperature adjusting device are realized by hardware or software, but some of them may be realized by using hardware or software. That is, a combination of hardware and software may be used.
(K) Various modifications can be considered for the above-described embodiments 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 the example of a form of a temperature distribution detection apparatus. It is a figure which shows the structural example of 1 pixel on a display. It is a figure which shows the method of gray scale conversion. It is a figure which shows the block area example. It is a figure which shows the structural example of the light emission amount calculation part. It is a figure which shows the structural example of the light emission amount calculation part. It is a figure which shows the calculation image of accumulated light emission amount. It is a figure which shows the relationship between accumulated light emission amount and a temperature rise degree. It is a figure which shows a temperature calculation procedure. It is a figure which shows the structural example of a panel module. It is a figure which shows the usage example of a temperature distribution detection apparatus. It is a figure which shows the usage example of a temperature distribution detection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 33 Temperature distribution detection apparatus 3 Gray scale conversion part 5 Area formation part 7 Light emission amount calculation part 9 Temperature calculation part 11 Panel module 13 Light emission area 15 Timing generator 21 Output terminal 31 Display apparatus

Claims (10)

A method for detecting temperature information of a self-luminous element ,
A process for calculating a grayscale signal value by a weighting calculation using a ratio of currents flowing through the individual light-emitting elements for each color when white is displayed as a weighting factor for one pixel on the display configured by a combination of the self-light-emitting elements for each color ;
Processing for calculating temperature information of one pixel on the display based on the grayscale signal value;
And a temperature information detecting method. Self-luminous elements are arranged in a matrix in the light emitting region of the display device ,
Processing to divide grayscale signal values into block areas to which corresponding pixels belong;
Based on the grayscale signal value after regionization, a process for calculating the light emission amount for each block area,
Processing for converting the outgoing light amount to the temperature information of each block area,
And
Detect the temperature distribution in the light emitting area
The temperature information detection method according to claim 1 . Originating light intensity is obtained as the accumulated emission values obtained by accumulating the average gradation value for each frame
The temperature information detection method according to claim 1 or 2 . Based on the accumulated emission values determined, determine the degree of temperature increase
The temperature information detection method according to claim 3 . Referring to the conversion table that stores the relationship between the cumulative amount of light emission and the temperature rise, the temperature rise is obtained
The temperature information detection method according to claim 4. Integrate the temperature rise per frame obtained for each frame and calculate the temperature
The temperature information detection method according to claim 4 or 5. Find the temperature rise for each block area,
Calculate the temperature for each block area,
Calculate the temperature of the entire light emitting area by calculating the cumulative amount of light emitted in units of frames.
The temperature information detection method according to any one of claims 4 to 6. A light emitting region in which self-emitting elements are arranged in a matrix;
Gray scale conversion for calculating a gray scale signal value by a weighting calculation using a ratio of current flowing through each color self light emitting element during white display as a weighting coefficient for one pixel on the display constituted by a combination of self light emitting elements for each color And
A temperature conversion unit that calculates temperature information of one pixel on the display based on the grayscale signal value;
And a display device. An apparatus for detecting temperature information of the light-emitting element,
Gray scale conversion for calculating a gray scale signal value by a weighting calculation using a ratio of current flowing through each color self light emitting element during white display as a weighting coefficient for one pixel on the display constituted by a combination of self light emitting elements for each color And
A temperature conversion unit that calculates temperature information of one pixel on the display based on the grayscale signal value;
And a temperature information detecting device. A process for calculating a grayscale signal value by a weighting calculation using a ratio of currents flowing through the individual light-emitting elements for each color when white is displayed as a weighting factor for one pixel on the display configured by a combination of the self-light-emitting elements for each color;
Processing for calculating temperature information of one pixel on the display based on the grayscale signal value;
To execute the bets in a computer program for detecting the temperature information of the light-emitting elements arranged in a matrix in the light-emitting region.

Images