JP2007286458A - Display device and control method for display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device and a control method for the display device such that smooth image display can be provided by suppressing a burning phenomenon due to a difference in luminance deterioration in devices (e.g. organic EL elements) depending upon temperatures. <P>SOLUTION: A relative luminance deterioration detector 308 detects a value of relative luminance deterioration with respect to each of high-luminance display pixels and low-luminance display pixels, and a temperature difference detector 311 detects temperature differences between the individual pixels and adjacent pixels. A data standardization processing unit 312 standardizes (converts) the temperature differences between the individual pixels and adjacent pixels into values ΔLa of relative luminance deterioration in the high-luminance display pixels and values ΔLb of relative luminance deterioration in the low-luminance display pixels on which the values of relative luminance deterioration in the high-luminance display pixels and low-luminance display pixels are reflected to perform performing temperature correction. Based upon division results ΔLa/ΔLb of the values ΔLa of relative luminance deterioration and values ΔLb of relative luminance deterioration obtained through the temperature correction, luminance correction is controlled so that deterioration in relative luminance due to temperature may become constant. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a display device and a display device control method, and more particularly to a display device using a self-light emitting element such as an organic electroluminescence element (organic EL (Electro Luminescence) element) as a display element and a control method thereof.

  In recent years, panel-type display devices (displays) using self-luminous elements such as light-emitting diodes (LEDs), laser diodes (LD), and organic EL elements as display elements have been developed. In this type of display device, generally, a screen portion (display panel) is configured by arranging a large number of self-light-emitting elements in a matrix, and each element is selectively made to emit light according to a video signal, thereby displaying an image. Is done.

  As a display medium, a display plays a big role in our daily life, as represented by a television receiver, a computer monitor, a portable information terminal, and the like. With the development of the Internet, the importance of displays as human interfaces is increasing. Under such circumstances, there is a demand for a high-resolution, high-speed display that is easy on the eyes, easy to see on a high-definition screen, and can be clearly displayed without delay in moving images.

  A display device using a self-light emitting element is thinner than a display device using a non-self light emitting element, for example, a liquid crystal display device using liquid crystal (LCD; (Liquid Crystal Display), because a backlight is unnecessary. The organic EL display device using an organic EL element has a wide viewing angle, high visibility, and a response speed of the element. Has been attracting attention in recent years.

  On the other hand, for self-luminous elements, such as organic EL elements, each organic layer deteriorates due to heat generated by light emission, the luminance of light emission decreases, and light emission itself becomes unstable. There is. Such a problem occurs not only in the organic EL display device but also in a display device using other self-luminous elements, such as a plasma display.

  As a countermeasure, conventionally, a luminance relationship due to a rise in temperature is suppressed by suppressing the amount of current flowing through the device by using a proportional relationship between the amount of current and light emission luminance (for example, Patent Document 1). reference).

  In addition, a temperature sensor is arranged near the pixel at the intersection of the scanning line and the data line, and the voltage level of the driving voltage for driving the scanning line is controlled in accordance with the change in the ambient temperature detected by the temperature sensor. Even when the temperature changes, uniform and bright display is performed (for example, see Patent Document 2).

JP 2003-323152 A JP 2003-157050 A

  However, in the conventional technique described in Patent Document 1, since the amount of current flowing through the device is suppressed, there is a problem in that light emission luminance decreases due to control of the amount of current and a good image display cannot be provided. .

  On the other hand, the temperature dependence of light emission luminance-applied voltage characteristics varies depending on the device. Therefore, in the conventional technology described in Patent Document 2 in which the emission luminance is controlled using only the detection output of the temperature sensor, it is possible to cope with the difference in the emission luminance-applied voltage characteristics due to the temperature of each device (organic EL element). There are problems such as being unable to do so.

  In addition, organic EL elements exhibit light-emitting diode characteristics, and the current flowing through the device increases proportionally with increasing temperature. As a result, the organic EL element has a proportional relationship with the emission luminance, and thus tends to promote device degradation. . That is, the organic EL element has a temperature characteristic in which the light emission luminance changes depending on the temperature.

  When light is emitted with a certain luminance, the higher the temperature of the organic EL element, the more easily the relative luminance is degraded. Specifically, as shown in FIG. 7, when the horizontal axis is the driving time, the vertical axis is the relative luminance, and the relative luminance when the driving time is 0 is 1, the relative luminance increases as the driving time increases. In addition to deterioration, the luminance deterioration curve varies depending on the temperature.

  If there is a difference in relative luminance at different temperatures throughout the display area, this difference in relative luminance appears as a so-called burn-in phenomenon to the human eye. That is, a burn-in phenomenon occurs due to a difference in luminance deterioration due to the temperature of the device. It is difficult to correct for the difference in degradation of relative luminance due to temperature by simply suppressing the amount of current flowing through the device or performing control using only the detection output of the temperature sensor. Even if the conventional techniques described in Patent Documents 1 and 2 are used, it is not possible to suppress the image sticking phenomenon that occurs due to the difference in the deterioration of relative luminance due to the temperature of the device.

  Therefore, an object of the present invention is to provide a display device and a display device control method capable of suppressing a burn-in phenomenon caused by a difference in luminance deterioration due to a temperature of a device and realizing a smooth image display.

  In order to achieve the above object, according to the present invention, in a display device in which a plurality of pixels including a light-emitting element formed between a pair of substrates is arranged, one of the pair of substrates is attached to one of the substrates. A light receiving element is arranged corresponding to each, and the light receiving element detects the light leakage of the light emitting element by detecting the light leakage of the light emitting element, and also receives the input signal to the light emitting element and each light reception of the light receiving element group. Based on the detection signal of the element, the deterioration of the relative luminance of the light emitting element is detected. Then, the relative luminance due to the temperature of the light emitting element is reflected by reflecting the deterioration of the relative luminance with respect to the temperature difference between adjacent pixels of each pixel or the temperature difference between the pixel temperature of each pixel and the ambient temperature of the display unit. The light emission luminance of the light emitting element is controlled so that the luminance degradation is constant.

  In the display device having the above-described configuration, the amount of deterioration of the relative luminance of the light emitting element is detected, and the amount of deterioration of the relative luminance is detected as a temperature difference from each pixel adjacent pixel, or the pixel temperature of each pixel and the ambient temperature of the display unit. By controlling the light emission luminance so that the relative luminance deterioration due to the temperature of the light emitting element is made constant by reflecting the difference in temperature of the light emitting element, the image sticking phenomenon caused by the difference in the relative luminance deterioration due to the temperature is suppressed. be able to.

  According to the present invention, it is possible to suppress a burn-in phenomenon that occurs due to a difference in luminance degradation due to the temperature of the light emitting element, and thus it is possible to realize a smooth image display.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
(Top-emitting panel module)
FIG. 1 is a cross-sectional view of an essential part showing an outline of a configuration of a top emission panel module used in a display device according to a first embodiment of the present invention, for example, an organic EL display device.

  As shown in FIG. 1, the panel module 10 </ b> A used in the organic EL display device according to the present embodiment includes a support substrate 11 and a counter substrate 12, and is a light emitting element that is sandwiched between the substrates 11 and 12. 13 is provided. The support substrate 11 is appropriately selected from a transparent substrate such as quartz or glass, a silicon substrate, or the like.

  Here, it is assumed that an active matrix method is adopted as a driving method of the panel module 10A. However, the driving method of the panel module 10A is not limited to the active matrix method, and the present invention can be applied even when the passive matrix method is adopted.

  On the support substrate 11, a transistor for driving the light emitting element 13, for example, a TFT (Thin Film Transistor) is formed for each pixel including the light emitting element 13. Further, when driving the display unit in which the driving circuit, not shown here, specifically, the pixels including the light emitting elements 13 are two-dimensionally arranged in a matrix, the support substrate 11 is driven to display each pixel of the display unit. Is selected via a scanning line wired for each pixel row in a row unit, and is displayed on each pixel in a row selected by the row selection circuit via a data line wired for each pixel column. A data line driving circuit for supplying data is provided.

  The light-emitting elements 13 are organic EL elements that are self-light-emitting elements, and are two-dimensionally arranged in a matrix (matrix shape) in the display area at the center of the main surface of the support substrate 11. Each of these light emitting elements 13 emits light of, for example, each color of R (red), G (green), and B (blue), and is arranged in a display area according to a predetermined arrangement format. An element isolation insulating layer 14 that separates the light emitting elements 13 is formed between the light emitting elements 13. The scanning line is wired for each pixel row in the element isolation insulating layer 14.

  The light emitting element 13 includes a lower electrode (anode) 15 arranged on the support substrate 11 for each light emitting element 13, an organic layer 16 formed on the lower electrode 15 and including a light emitting layer that emits light of each color, A solid film is formed so as to cover the organic layer 16 and the element isolation insulating layer 14, and an upper electrode (cathode) 17 serving as a common electrode of each light emitting element 13 is sequentially laminated.

  Although the lower electrode 15 is an anode and the upper electrode 17 is a cathode here, the lower electrode 15 may be a cathode and the upper electrode 17 may be an anode. Further, a transparent material film 18 made of, for example, silicon nitride is provided between the upper electrode 17 and the counter substrate 12.

  On the surface side of the counter substrate 12, there are a number of light receiving elements 19 corresponding to the light emitting elements 13 at positions between the light emitting elements 13, that is, positions facing the element isolation insulating layer 14 where scanning lines are wired. Just arranged. Specifically, the light receiving element 19 is provided in a state of embedding a recess 12 a formed on the surface side of the counter substrate 12. The recess 12a is formed by etching or the like before the support substrate 11 and the counter substrate 12 are arranged to face each other.

  Here, an arrangement structure is adopted in which the light receiving element 19 is embedded in a recess 12a formed on the surface side of the counter substrate 12, but a recess is formed on the light emitting element 13 side of the counter substrate 12, and light is received in the recess. It is also possible to adopt an arrangement structure in which the element 19 is embedded, or an arrangement structure in which a recess is formed on the counter substrate 12 side of the transparent material film 18 and the light receiving element 19 is embedded in the recess.

  The light receiving element 19 is a high-sensitivity light receiving sensor (visible light sensor) formed of, for example, an amorphous silicon semiconductor, detects leakage light of the light emitting element 13 in a corresponding relationship, performs photoelectric conversion, and an electrical signal corresponding to the amount of light received Is generated. The correspondence relationship between the light emitting element 13 and the light receiving element 19 will be described later.

  The light receiving element 19 is not limited to a high sensitivity light receiving sensor formed of an amorphous silicon semiconductor, and a known light receiving sensor capable of generating an electric signal according to the amount of received light can be used. However, by using a highly sensitive light receiving sensor as the light receiving element 19, there is an advantage that leakage light having a light amount of about 20% with respect to the light emission intensity of the light emitting element 13 can be detected as will be described later.

  In addition, since the organic EL element can have a function as a light receiving element because of its structure, the organic EL element can also be used as the light receiving element 19. By using the organic EL element as the light receiving element 19, in the organic EL display device, since the light emitting element 13 and the light receiving element 19 can be formed by the same process, there is an advantage that the manufacturing process is advantageous. is there.

  The light receiving element 19 emits leakage light having a light amount of about 20% with respect to the light emission intensity of the light emitting element 13 due to the arrangement relationship with respect to the light emitting element 13 determined by the pixel arrangement pitch and the film thickness of the upper electrode 17 and the transparent material film 18. Can be detected. As described above, if the light receiving element 19 can receive about 20% of the light emission intensity of the light emitting element 13, the control described later based on the light receiving output of the light receiving element 19 can be sufficiently realized.

  As shown in the plan view of FIG. 2, the light receiving elements 19 are arranged between the light emitting elements 13 adjacent in plan view in the scanning direction. When a light emitting element 13 in a certain pixel row is selected during scanning of the pixel row by the above-described row selection circuit, one light receiving element 19 adjacent to the light emitting element 13 in the selected row is the light emitting element 13. It is a correspondence relationship to monitor the leakage light. This correspondence is the correspondence between the light emitting element 13 and the light receiving element 19 described above.

  That is, the light emitting element 13 in a certain pixel row and the one light receiving element 19 adjacent to the light emitting element 13 in the scanning direction are paired, and the light receiving element 19 corresponding to the light emitting element 13 in the same cycle as the scanning cycle of the light emitting element 13. Light leakage from the light emitting element 13 is monitored. Due to this timing relationship, even if there are two light emitting elements 13 adjacent to both sides in the scanning direction with respect to one light receiving element 19, the light receiving element 19 receives only the amount of light leakage from one light emitting element 13. In addition, the amount of light leakage from the other light emitting element 13 can be prevented from being received. Here, the cross-sectional view taken along the line AA ′ of FIG. 2 is the cross-sectional configuration diagram of FIG.

  As described above, the so-called top emission type panel module 10 </ b> A that extracts light emitted from the organic layer 16 of the light emitting element 13 from the counter substrate 12 side is configured. And in this upper surface light emission type panel module 10A, the temperature sensor 20 is located on the opposite side of the light extraction direction, that is, on the support substrate 11 side, at a portion facing the light emitting element 13 on one main surface (outer surface) of the support substrate 11. Is provided.

  Since the temperature sensor 20 is in close contact with one main surface of the support substrate 11, it is possible to reliably detect the temperature associated with the heat generation of the light emitting elements 13 that face each other with the support substrate 11 interposed therebetween. As this temperature sensor 20, for example, a known temperature sensor formed of an amorphous silicon semiconductor or the like can be used.

  Here, the top-emitting panel module 10A is taken as an example, but the present invention is not limited to the application to the top-emitting panel module 10A. Light emitted from the organic layer 16 of the light-emitting element 13 is used as the support substrate 11. The present invention can also be applied to a so-called bottom (bottom) light emitting panel module that is taken out from the side. The structure of the bottom emission panel module will be described below.

(Bottom-emitting panel module)
FIG. 3 is a cross-sectional view of an essential part showing an outline of the configuration of the bottom emission panel module used in the organic EL display device according to the first embodiment of the present invention. In FIG. Is shown.

  As shown in FIG. 3, in the case of the bottom emission type panel module 10B used in the organic EL display device according to the present embodiment, the emitted light from the organic layer 16 is extracted from the support substrate 11 side. The lower electrode 15 is made of a transparent material. Here, the lower electrode 15 is disposed in a state corresponding to each light emitting element 13 on a planarization insulating film (not shown) provided in a state of covering the TFT disposed on the support substrate 11.

  The light receiving element 19 is disposed on the planarization insulating film between the lower electrodes 15 so as to be separated from the adjacent lower electrodes 15. In addition, since the light receiving element 19 detects leakage light of the light emitting element 13, the element isolation insulating layer 14 disposed in a state of covering the light receiving element 19 is made of a transparent material. On the other hand, the temperature sensor 20 is provided on the opposite side of the light extraction direction, that is, on the counter substrate 12 side, at a portion facing the light emitting element 13 on one main surface (outer surface) of the counter substrate 12.

  The above point is that the bottom emission panel module 10B is structurally different from the top emission panel module 10A, and the other structures are basically the same as the top emission panel module 10A.

  The organic EL display device according to the present embodiment includes a control unit according to the present embodiment described below in addition to the top emission panel module 10A or the bottom emission panel module 10B described above. Thus, the display control (drive control) of the panel modules 10A / 10B is performed.

(Control part)
FIG. 4 is a block diagram showing an example of the configuration of the control unit 30A according to the second embodiment that controls the panel modules 10A / 10B having the above-described configuration.

  As shown in FIG. 4, the control unit 30A according to the present embodiment includes a level control unit 301, a relative level adjustment unit 302, a memory unit 303, a division unit 304, an A / D (analog / digital) conversion unit 305, and a memory unit. 306, multiplication unit 307, relative luminance deterioration detection unit 308, A / D conversion unit 309, memory unit 310, temperature difference detection unit 311, data normalization processing unit 312, voltage division calculation unit 313, voltage division result comparison calculation unit 314 The voltage division ratio control unit 315 and the calculation selection control unit 316 are included.

  The control unit 30A performs display control of each pixel of the display unit in the panel module 10A according to the input digital video signal, while the light receiving elements 19 of the light receiving element group provided in the panel module 10A / 10B. The relative luminance deterioration amount is detected based on the detection signal, and the temperature difference between adjacent pixels of each pixel is detected based on the detection signal of each temperature sensor 20 of the temperature sensor group provided in the panel module 10A. Based on the relative luminance deterioration amount and the temperature difference, the light emitting element 13 is controlled so that the deterioration of the relative luminance due to the temperature characteristics of the light emitting element 13 becomes constant (uniform).

  In the control unit 30A, the digital video signal is supplied to the memory unit 303 via the level control unit 301 and the relative level adjustment unit 302, and after the gradation value of each display pixel is stored in the memory unit 303, the panel module 10A. / 10B. Each function of the level control unit 301 and the relative level adjustment unit 302 will be described later.

  In the panel module 10A / 10B, as described above, each pixel of the display unit in which pixels are two-dimensionally arranged in a matrix is selected in units of rows, and each pixel in the selected row is selected according to a digital video signal. By writing the display data, the light emitting element 13 of each pixel is driven to emit light at a gradation corresponding to the digital video signal.

  When the light emitting element 13 of each pixel emits light sequentially in units of rows by the display drive by this row scanning, each light receiving element 19 receives the leakage light of each light emitting element 13 having a corresponding relationship, and performs photoelectric conversion according to the amount of light received. Output as a voltage value. The voltage value output from the light receiving element 19 is supplied to the division unit 304.

  The division unit 304 performs arithmetic processing for dividing the voltage value output from the light receiving element 19 by the gradation value given from the memory unit 303 via the multiplication unit 307. Here, if the light emission intensity (light emission luminance) of the display pixel is high (if it is bright), the gradation is high, and conversely if the light emission intensity is low (if it is dark), the gray scale is low. From the division result, the state of luminance of the display pixel (whether it is high luminance or low luminance) can be recognized. The division result is converted into digital data by the A / D conversion unit 305 and stored in the memory unit 306.

  The multiplication unit 307 performs a 20% multiplication process on the gradation value of each display pixel stored in the memory unit 303. Here, the multiplication process of 20% with respect to the gradation value of the display pixel is performed when the light reception amount of the leak light received by the light receiving element 19 is about 20% of the light emission amount of the light emitting element 13 as described above. For this reason, the voltage value from the light receiving element 19 to be subjected to the division operation and the gradation value from the memory unit 303 are associated with each other (aligned).

  Here, the multiplication unit 307 performs a multiplication process of 20% on the gradation value from the memory unit 303, but by performing a multiplication process of 5 times on the voltage value from the light receiving element 19. In addition, the voltage value from the light receiving element 19 to be subjected to the division operation in the division unit 304 can be associated with the gradation value from the memory unit 303.

  The relative luminance deterioration detection unit 308 determines, based on the data stored in the memory unit 306, a pixel that emits light at the highest luminance or its vicinity on one display screen as a high luminance display pixel, and a pixel that emits light at the lowest luminance or its vicinity. Recognized as a luminance display pixel, and for each of the high luminance display pixel and the low luminance display pixel, the amount of relative luminance deterioration in a predetermined driving period is detected based on the gradation value given from the memory unit 303 via the multiplication unit 307 To do.

  As described above, the organic EL element exhibits a light emitting diode characteristic, and has a temperature characteristic in which the light emission luminance varies depending on the temperature. When the light is emitted at a certain luminance, the light emission luminance (brightness) deteriorates as the temperature increases. Specifically, as the driving time becomes longer, the relative luminance deteriorates and the luminance deterioration curve varies depending on the temperature. Also, the characteristics of luminance degradation due to temperature are different between the high-luminance display pixel and the low-luminance display pixel, and as is clear from FIG. 5, the characteristic (A) of the high-luminance display pixel is the characteristic of the low-luminance display pixel. Deterioration is more remarkable than in (B).

  Each temperature sensor 20 of the temperature sensor group in the panel module 10A detects the temperature of each pixel during the non-display period of the display pixel and outputs it as a voltage value. The voltage value output from the temperature sensor 20 is converted into digital data by the A / D conversion unit 309 and stored in the memory unit 310. The temperature difference detection unit 311 is based on the storage data about the detected temperature stored in the memory unit 310, and the temperature difference (voltage value difference) between adjacent pixels for each pixel, for example, the previous pixel in the scanning order. ) For each pixel.

  The data normalization processing unit 312 has a numerical correlation data table indicating a correspondence relationship between luminance and temperature, and a relative luminance deterioration detection unit is added to the temperature difference between each adjacent pixel detected by the temperature difference detection unit 311. By reflecting the relative luminance degradation amount of each of the high luminance display pixel and the low luminance display pixel detected in 308, it corresponds to the temperature difference with the adjacent pixel in which the relative luminance degradation amount of the high luminance display pixel is reflected. A second voltage corresponding to the temperature difference between the first voltage value (hereinafter referred to as “the relative luminance deterioration amount of the high luminance display pixel”) ΔLa and the adjacent pixel in which the relative luminance deterioration amount of the low luminance display pixel is reflected. Is normalized (converted) to ΔLb (hereinafter referred to as “relative luminance degradation of low luminance display pixel”).

  The voltage division calculation unit 313 divides the relative luminance degradation amount ΔLa of the high luminance display pixel normalized by the data normalization processing unit 313 by the relative luminance degradation amount ΔLb of the low luminance display pixel for each pixel. This division result ΔLa / ΔLb is the ratio of the temperature difference between the adjacent pixels reflecting the relative luminance degradation of the high luminance display pixel and the temperature difference between the adjacent pixels reflecting the relative luminance degradation of the low luminance display pixel. Therefore, it represents the degree of image sticking phenomenon that occurs due to the difference in luminance degradation due to temperature. Hereinafter, the division result ΔLa / ΔLb is referred to as a temperature characteristic image sticking correlation coefficient.

  The voltage division result comparison calculation unit 314 is caused by the temperature due to the temperature difference between adjacent pixels detected based on the temperature characteristic burn-in correlation coefficient ΔLa / ΔLb, which is the division result of the voltage division calculation unit 313, for each pixel. The degree of image sticking phenomenon that occurs due to the difference in luminance deterioration is determined.

  Here, a correspondence relationship between a temperature difference between adjacent pixels and a critical point at which a seizure phenomenon occurs (hereinafter referred to as a “seizure critical point”) will be described. Note that the seizure critical point (numerical value) corresponds to a predetermined reference value in the claims. As an example, as shown in FIG. 6, when the temperature difference between adjacent pixels is 5 ° C., the critical point for occurrence of seizure is 1.53. This indicates that the critical point at which the seizure phenomenon occurs at a temperature difference of 5 ° C. is 1.53, and at the temperature difference of 5 ° C., the temperature characteristic seizure correlation coefficient ΔLa / ΔLb is less than the critical point ( If ΔLa / ΔLb <1.53), it means that no seizure phenomenon occurs.

  Similarly, when the temperature difference between adjacent pixels is 10 ° C., the critical point for image sticking is 1.45, and when the temperature difference between adjacent pixels is 15 ° C., the critical point for image sticking is 1.40, between adjacent pixels. When the temperature difference is 20 ° C., the critical point for image sticking is 1.36, when the temperature difference between adjacent pixels is 25 ° C., the critical point for image sticking is 1.31, and the temperature difference between adjacent pixels is 30 ° C. When the temperature difference is 1.24, the critical point for image sticking is 1.24, when the temperature difference between adjacent pixels is 35 ° C., the critical point for image sticking is 1.19, and when the temperature difference between adjacent pixels is 40 ° C., the image sticking occurs. The critical point is 1.12.

  That is, ΔLa / ΔLb <1.45 at a temperature difference of 10 ° C., ΔLa / ΔLb <1.40 at a temperature difference of 15 ° C., ΔLa / ΔLb <1.36 at a temperature difference of 29 ° C., and ΔLa / ΔLb <at a temperature difference of 25 ° C. 1.31, ΔLa / ΔLb <1.24 at a temperature difference of 30 ° C., ΔLa / ΔLb <1.19 at a temperature difference of 35 ° C., and seizure phenomenon at ΔLa / ΔLb <1.12 at a temperature difference of 40 ° C. Will not.

  Therefore, the voltage division result comparison calculation unit 314 performs the following comparison calculation process. That is, in a certain pixel, for example, when the temperature difference with the detected adjacent pixel is 15 ° C., for example, the temperature characteristic seizure from the correspondence between the temperature difference between the adjacent pixels and the critical point for occurrence of seizure. If the correlation coefficient ΔLa / ΔLb is 1.40 or more, that is, whether or not the seizure phenomenon occurs, and if it is 1.40 or more, the extent of occurrence of the seizure phenomenon, that is, the seizure critical point ( Processing for calculating the difference with respect to 1.40) is performed.

  The voltage division ratio control unit 315 calculates, for each pixel, a control value for preventing the image sticking phenomenon from occurring based on the determination result of the degree of the image sticking phenomenon occurring by the voltage division result comparison operation unit 314. Specifically, when it is determined that the seizure phenomenon occurs in the voltage division result comparison operation unit 314 and a difference is calculated with respect to the critical point for occurrence of seizure, a control value corresponding to the difference is calculated. This control value is a luminance correction value for correcting the signal level of the input digital signal so that the deterioration of the relative luminance due to the temperature characteristics of the light emitting element 13 is constant (uniform).

  Here, it is assumed that the voltage division calculation unit 313, the voltage division result comparison calculation unit 314, and the voltage division ratio control unit 315 incorporate a correspondence table indicating the correspondence relationship between the calculated voltage value and the luminance. Thus, when performing luminance correction, it is possible to inquire for each circuit unit how much luminance value the calculated voltage value corresponds to, so that smooth correction is possible.

  Based on the brightness correction value (control value) of each pixel calculated by the voltage division ratio control unit 315, the calculation selection control unit 316 performs high brightness when the correction target pixel is a high brightness display pixel. Selection control is performed to determine whether or not to correct the signal level (luminance level) for the display pixel. Then, based on the selection result by the calculation selection control unit 316, the level control unit 301 performs correction control according to the luminance correction value calculated by the voltage division ratio control unit 315 with respect to the signal level of the high luminance display pixel. Do.

  The relative level adjustment unit 302 includes a still image determination unit 3021, a changeover switch 3022, and a level adjustment unit 3023.

For example, as shown in FIG. 7, the still image determination unit 3021 includes a frame memory 30211, an arithmetic circuit 30212, and a determination circuit 30213. The still image determination unit 3021 includes the video signal level V 1 N of the Nth frame, Using the video signal level V1 (N-1) of the (N-1) th frame, the arithmetic circuit 30212 uses [{V1N-V1 (N-1)} / V1 (N-1)] * 100.
The calculation circuit 30213 determines whether or not the calculation result is, for example, 70% or less of the video signal level V1 (N-1) of the (N-1) th frame. It is determined that the image is a still image. Naturally, when it exceeds 70%, it becomes a moving image.

  The change-over switch 3022 normally supplies the input digital video signal directly to the memory unit 303, and when the determination result of the still image determination unit 3021 is a still image, the input digital video signal is converted to the level adjustment unit 3023. To the memory unit 303. The level adjustment unit 3023 multiplies the signal level of the video signal when it is determined as a still image by, for example, 100 times.

  Here, the reason why the signal level of the video signal is multiplied by 100 when it is determined as a still image is as follows. That is, as described above, the relative luminance deterioration detection unit 308 detects the change in the emission luminance (luminance level) in a predetermined period (for example, one frame period). The brightness level varies between frames due to a change or the like. The change in the luminance level of the still image in one frame period is as extremely small as about 1/100 compared to the change in the luminance level of the moving image in one frame period.

  Therefore, when it is determined that the image is a still image, the relative luminance deterioration detection unit 308 performs a weak signal level transition between the previous and next frames by performing a multiplication process of about 100 times on the signal level of the video signal. (Brightness change) can be easily detected. However, the numerical value of 100 is merely an example, and is not limited to this, and it is sufficient that the magnification is at least enough to detect a weak signal level transition between the preceding and succeeding frames.

  In addition, when a still image is determined, the signal level of the video signal is multiplied by about 100 times so that the change in the luminance level in one frame period is the same voltage for the still image and the moving image. Can be a value. In this way, by making the change in the luminance level the same voltage value at the time of still image and moving image, the data normalization processing unit 312 → voltage division unit 313 → voltage division result comparison calculation unit 314 → voltage division ratio The correction control system of the control unit 315 → the calculation selection control unit 316 → the level control unit 301 can be made common for still images and moving images (separation is not necessary). In this case, a value of 100 times works effectively.

  Regarding the adjustment of the signal level at the time of still image, a correspondence table between the signal level at the time of still image and the corresponding luminance value is incorporated in the level adjustment unit 3023 in advance, and this correspondence table is used to adjust the signal level at the time of still image. It is also possible to adopt a configuration in which the signal level is set to a luminance value corresponding to the signal level.

  In the organic EL display device including the control unit 30A according to the present embodiment having the above-described configuration, as described above, the organic EL element used as the light-emitting element 13 is deteriorated in relative luminance as the driving time becomes longer. The luminance degradation curve has different characteristics depending on the temperature, and the luminance degradation characteristics due to temperature are different between the high luminance display pixel and the low luminance display pixel. A burn-in phenomenon occurs due to a difference in luminance deterioration due to the temperature of the device.

  As described above, in the display device using the organic EL element as the light emitting element 13, since the organic EL element is a self-luminous element, the temperature rises as much as the same display state continues for a long time. And in the present situation that the burn-in phenomenon occurs due to the difference in luminance degradation due to the temperature of the device, the organic EL display device including the control unit 30A according to the present embodiment is characterized by adopting the following configuration. .

  That is, a light receiving element 19 is arranged corresponding to each light emitting element 13, and the light receiving element 19 detects leakage light of the light emitting element 13 to detect the luminance of each light emitting element 13, and the temperature sensor 20 emits light. The temperature of each of the pixels including the element 13 is detected, and under the control of the control unit 30A, the deterioration of the relative luminance in a predetermined driving period is detected using the input digital signal and the detection signal of the light receiving element 19. Then, the temperature difference between the adjacent pixels is detected for each pixel using the temperature information of each pixel by the temperature sensor 20, and the relative luminance deterioration due to the temperature of the light emitting element 13 is reflected in this temperature difference. A configuration is adopted in which the light emission luminance of the light emitting element 13 is controlled so that the deterioration becomes constant.

  As described above, the luminance information of each light emitting element 13 is detected using the luminance information of each light emitting element 13, and the light emitting luminance of each light emitting element 13 is reflected by reflecting the deterioration of the relative luminance in the temperature difference with each adjacent pixel. Specifically, by controlling the light emission luminance of each light emitting element 13 so that the deterioration of the relative luminance due to the temperature of the light emitting element 13 becomes constant, the deterioration of the relative luminance due to the temperature of the device is controlled. Since the image sticking phenomenon caused by the difference can be suppressed, smooth image display can be realized.

  In the luminance control by the control unit 30A according to the present embodiment, as specific control, the relative luminance degradation detection unit 308 detects the relative luminance degradation for each of the high luminance display pixel and the low luminance display pixel, and the pixel A temperature change detection unit 311 detects a temperature difference from each adjacent pixel, and the temperature difference from each pixel adjacent pixel is reflected by a relative luminance deterioration amount for each of the high luminance display pixel and the low luminance display pixel. The data normalization processing unit 312 normalizes (converts) the relative luminance degradation amount ΔLa of the high luminance display pixel and the relative luminance degradation amount ΔLb of the low luminance display pixel, and obtains the temperature correction. The luminance correction is controlled based on the temperature characteristic burn-in correlation coefficient ΔLa / ΔLb, which is the result of dividing the relative luminance degradation ΔLa and the relative luminance degradation ΔLb.

  In addition, in the organic EL display device including the control unit 30A according to the present embodiment, the temperature sensor 20 that detects the temperature of each pixel is a pair of the top emission panel module 10A and the bottom emission panel module 10B. By adopting a configuration in which the substrate 11, 12 is arranged on the support substrate 11 opposite to the light extraction direction, an extra space for arranging the temperature sensor 20 in plan view on the panel module 10 </ b> A / 10 </ b> B. Therefore, the display area is not suppressed, and the reduction of the panel size is not hindered.

  Moreover, as apparent from FIGS. 1 and 3, the aperture ratio of the pixel including the light emitting element 13 is obtained by orienting each of the temperature sensors 20 with the support substrate 11 interposed between the light emitting elements 13. Therefore, the temperature sensor 20 is brought into close contact with the support substrate 11, so that the light emitting elements 13 are individually connected by the temperature sensor 20. The temperature of the can be reliably detected.

  The control unit 30A having the above-described configuration may be configured to be mounted on the panel module 10A / 10B together with a display unit in which pixels are arranged in a matrix and its peripheral drive circuit, or a panel. You may take the structure provided outside module 10A / 10B.

  Here, each component of the control unit 30A according to the present embodiment, that is, the level control unit 301, the relative level adjustment unit 302, the memory unit 303, the division unit 304, the A / D conversion unit 305, the memory unit 306, and the multiplication unit 307. , Relative luminance deterioration detection unit 308, A / D conversion unit 309, memory unit 310, temperature difference detection unit 311, data normalization processing unit 312, voltage division calculation unit 313, voltage division result comparison calculation unit 314, voltage division ratio control The unit 315 and the calculation selection control unit 316 are realized by a software configuration using a computer device that executes functions such as information storage processing, signal processing, and arithmetic processing by executing a predetermined program like a personal computer. It is possible to do. However, the present invention is not limited to the implementation by software configuration, and can also be implemented by a hardware configuration or a combined configuration of hardware and software.

(Control method)
Next, a processing procedure of the organic EL display device control method according to the present embodiment having the above-described configuration (display device control method according to the present invention) will be described in detail with reference to the flowchart of FIG. The processing by this control method corresponds to the processing of the control unit 30A in FIG. Note that this series of processing is executed in units of pixels in synchronization with the scan cycle.

  Here, as an example, as shown in FIG. 9, when the initial temperature of the light emitting element 13 is 30 ° C., the relative luminance of the high luminance display pixel (A) is La (= 1.0), and the low luminance display is performed. The relative luminance of the pixel (B) is set to Lb (= 1.0), and the temperature of the high luminance display pixel in the display state after the elapse of a predetermined driving period t rises to 60 ° C., and the high luminance display at this time The relative luminance of the pixel deteriorates 6% from the initial value La (ΔLa = La × 6%), the temperature of the low-luminance display pixel rises to 45 ° C., and the relative luminance of the low-luminance display pixel at this time is the initial value Lb. As an example, the luminance correction control in the case of 4% deterioration (ΔLa = La × 4%) will be described.

  Note that the control method is the same for both still images and moving images, and therefore, here, a description will be given of common control for still images / moving images.

  First, a digital video signal for image display is fetched (step S11), the gradation value indicated by the signal level of the video signal is stored (step S12), and then the digital video signal is sent to the panel modules 10A / 10B. (Step S13). Thereby, in the panel module 10A / 10B, display driving of the pixel is performed based on the digital input signal, and the light emitting element 13 of each pixel emits light.

  When the light emitting element 13 emits light, the corresponding light receiving element 19 receives the leakage light of the light emitting element 13 and outputs an electric signal corresponding to the amount of received light, that is, a voltage value corresponding to the light emission luminance. A temperature sensor 20 disposed opposite to the light emitting element 13 with the support substrate 11 interposed therebetween detects the temperature of the light emitting element 13 and outputs a voltage value corresponding to the temperature.

  Thus, when the panel module 10A is in the display driving state, a voltage value (luminance voltage value) corresponding to the light emission luminance output from the light receiving element 19 is captured (step S14), and this luminance voltage value is obtained in step S12. Divide by the stored gradation value (step S15), convert to digital data, and store (step S16).

  Next, for each of the high-luminance display pixel and the low-luminance display pixel, the deterioration of the light emission luminance during a predetermined driving period is detected based on the gradation value stored in step S12 (step S17).

  Note that the gradation value used for the division process in step S15 and the detection of the luminance degradation in step S17 is actually the amount of light received by the light receiving element 19 is equal to the amount of light emitted by the light emitting element 13. It is about 20%, and in order to correspond to the voltage value from the light receiving element 19, 20% division processing is performed.

  Next, a voltage value (temperature voltage value) corresponding to the temperature of the pixel including the light emitting element 13 output from the temperature sensor 20 is taken in (step S18), and the temperature difference (voltage value of the voltage value) between adjacent pixels for each pixel. (Difference) is detected (step S19).

  In addition, each process of steps S14 to S17 for detecting the luminance change amount for each of the high luminance display pixel and the low luminance display pixel, and step S18 for detecting a temperature difference between adjacent pixels for each pixel. About each process of S19, the order of the process may be reverse, and you may make it perform both detection processes in parallel.

  Next, based on the numerical correlation data table indicating the correspondence between the brightness and the temperature, the temperature difference between each adjacent pixel is detected for each of the high brightness display pixel and the low brightness display pixel detected in step S17. The voltage value corresponding to the luminance deterioration amount (relative luminance deterioration amount of the high luminance display pixel) ΔLa and the voltage value corresponding to the temperature change amount of the low luminance display pixel (relative luminance deterioration amount of the low luminance display pixel) ΔLb Normalization (conversion) is performed (step S20).

  Here, when the relative luminance deterioration of the high luminance display pixel due to the temperature change from 30 ° C. to 60 ° C. after the elapse of the predetermined driving period t is 6%, the relative luminance deterioration ΔLa of the high luminance display pixel is For example, when the relative luminance deterioration of the low-luminance display pixel is 4%, which is normalized to a voltage value of 4.8 V and the temperature change from 30 ° C. to 45 ° C. after a predetermined driving period has elapsed, It is assumed that the relative luminance degradation ΔLb is standardized as a voltage value of 3.2 V, for example.

  Next, the relative luminance degradation ΔLa of the high luminance display pixel is divided by the relative luminance degradation ΔLa of the low luminance display pixel (step S21), and then the temperature difference ΔT between the high luminance display pixel and the low luminance display pixel is ΔT. Based on the temperature characteristic seizure correlation coefficient ΔLa / ΔLb as a result of division when ≧ 15 ° C. (= 60 ° C.−45 ° C.), the correspondence between the temperature difference and seizure critical point shown in FIG. Then, the degree of occurrence of the image sticking phenomenon due to the difference in deterioration of the relative luminance due to temperature is determined (step S22).

  In this example, the temperature characteristic image sticking correlation coefficient ΔLa / ΔLb is ΔLa / ΔLb = 4.8 V / 3.2 V = 1.50. From the correspondence in FIG. Since the temperature difference ΔT with respect to the display pixel is equal to or higher than the critical point (1.40) at which image sticking occurs when the temperature difference is 15 ° C., it is determined that the image sticking phenomenon occurs due to the difference in relative luminance degradation due to temperature. Then, a process for calculating the degree of occurrence of seizure phenomenon, that is, the difference between the temperature characteristic seizure correlation coefficient ΔLa / ΔLb and the seizure critical point is performed.

  Here, in order to reduce the temperature characteristic image sticking correlation coefficient ΔLa / ΔLb to less than 1.40, that is, to decrease it by a value exceeding 0.10, the relative luminance degradation amount ΔLb of the low-luminance display pixel is reduced to about It may be set to 3.43 V or higher, or the relative luminance degradation ΔLa of the high luminance display pixel may be set to about 4.48 V or lower. For this purpose, the signal level of the low luminance display pixel is amplified by about 0.23 V (= 3.43 V-3.2 V) or more, or the signal level of the high luminance display pixel is about 0.32 V (= 4.48 V-4). .8V) or more is selected.

  Such processing is executed in each processing step of steps S23 to S25. That is, the luminance correction value for keeping the temperature characteristic image sticking correlation coefficient ΔLa / ΔLb in the range of 1.0 to 1.4 (in the above example, 0.23 V / high luminance display pixel with respect to the low luminance display pixel). 0.32V) is calculated for each pixel (step S23), and then correction by signal level amplification is performed on the low luminance display pixel or correction by attenuation of the signal level on the high luminance display pixel (Step S24), and then, based on the selection result, the luminance correction is performed by performing amplification control or attenuation control on the signal level (luminance level) of each pixel of the digital video signal (step S25). ).

  Through the above-described series of processing, the deterioration of relative luminance is detected for each of the high luminance display pixel and the low luminance display pixel, and the temperature difference between the adjacent pixels of each pixel is detected by the high luminance display pixel and the low luminance display pixel. The temperature correction was performed by converting the relative luminance deterioration amount ΔLa of the high luminance display pixel corresponding to the deterioration amount of the relative luminance and the relative luminance deterioration amount ΔLb of the low luminance display pixel. Since the luminance correction is performed such that the temperature characteristic image sticking correlation coefficient ΔLa / ΔLb, which is the result of the division of the relative luminance deterioration ΔLa, ΔLb, is less than the critical point for image sticking, the relative luminance due to the temperature of the light emitting element 13 is obtained. Control is performed so that the deterioration of the ink becomes constant. Thereby, since the image sticking phenomenon that occurs due to the difference in deterioration of the relative luminance due to the temperature of the light emitting element 13 can be suppressed, a smooth image display can be realized.

  In the present embodiment described above, the temperature sensor 20 is arranged corresponding to each pixel, and the temperature sensor detects the temperature of each pixel to detect the temperature difference between adjacent pixels. However, the organic EL element emits light. A diode characteristic is shown, and the current flowing through each light emitting element 13 is estimated from the luminance information of the light emitting element 13 detected by the light receiving element 19 using the characteristic that there is a proportional relationship between the light emitting luminance and the amount of current. The power consumption can be calculated from the estimated current value, and the temperature of each pixel can be estimated from the calculated power consumption to detect the temperature difference between adjacent pixels.

[Second Embodiment]
(Top-emitting panel module)
FIG. 11 is a cross-sectional view of an essential part showing an outline of the configuration of a top emission panel module used in a display device according to a second embodiment of the present invention, for example, an organic EL display device. In FIG. Are denoted by the same reference numerals.

  As is clear from the comparison between FIG. 11 and FIG. 1, the panel module 10C used in the organic EL display device according to the present embodiment does not have a temperature sensor for detecting the temperature of each pixel for each pixel. The panel module 10A is different from the panel module 10A shown in FIG. 1, and other structures are the same as those of the panel module 10A.

(Bottom-emitting panel module)
FIG. 12 is a cross-sectional view of an essential part showing an outline of the configuration of a top emission panel module used in the organic EL display device according to the second embodiment of the present invention. In FIG. Is shown.

  As is clear from the comparison between FIG. 12 and FIG. 3, the panel module 10D used in the organic EL display device according to this embodiment does not have a temperature sensor for detecting the temperature of each pixel for each pixel. The panel module 10B is different from the panel module 10B shown in FIG. 1, and the other structure is the same as that of the panel module 10B.

  The top-emitting panel module 10C or the bottom-emitting panel module 10D described above does not have a temperature sensor for detecting the temperature of each pixel for each pixel, but is arranged around a display unit in which pixels are arranged in a matrix. At least one is arranged and has a temperature sensor 21 (see FIG. 12) that detects the ambient temperature of the display unit (which can also be said to be the environmental temperature where the panel module 10C / 10D is placed).

  The organic EL display device according to the present embodiment includes a display of the panel module 10C / 10D in addition to the top emission panel module 10C or the bottom emission panel module 10D having the temperature sensor 21 at the panel periphery (periphery of the display unit). A control unit that performs control (drive control) is provided.

(Control part)
FIG. 12 is a block diagram illustrating an example of a configuration of a control unit 30B according to the second embodiment that performs control of the panel module 10C / 10D. As described above, the panel module 10C / 10D includes the temperature sensor 21 that detects the ambient temperature of the display unit (the temperature of the non-display unit) on the panel periphery (the periphery of the display unit).

  As shown in FIG. 12, the control unit 30B according to this embodiment includes a level control unit 321, a relative level adjustment unit 322, a memory unit 323, a division unit 324, an A / D conversion unit 325, a memory unit 326, and a multiplication unit 327. , Relative luminance deterioration detection unit 328, A / D conversion unit 329, pixel temperature detection unit 330, temperature difference detection unit 331, data normalization processing unit 332, voltage difference calculation unit 333, voltage difference result comparison calculation unit 334, voltage difference A ratio control unit 335 and a calculation selection control unit 336 are provided.

  The control unit 30B performs display control of each pixel of the display unit in the panel module 10C / 10D according to the input digital video signal, while each light receiving element of the light receiving element group provided in the panel module 10C / 10D. The relative brightness deterioration amount is detected based on the 19 detection signals, and the temperature of each pixel is detected by estimating the temperature of each pixel from the brightness information of the light emitting element 13 detected by the light receiving element 19, and this detection is performed. A temperature difference between the pixel temperature and the ambient temperature of the display unit by the temperature sensor 21 is detected for each pixel, and the relative luminance deterioration due to the temperature characteristics of the light emitting element 13 is detected based on the detected relative luminance deterioration amount and temperature difference. The drive control of the light emitting element 13 is performed so as to be constant (uniform).

  The control unit 30B estimates the temperature of each pixel from the luminance information of the light emitting element 13 detected by the light receiving element 19, and the estimated pixel temperature and the ambient temperature of the display unit by the temperature sensor 21 (temperature of the non-display unit). The control according to the first embodiment detects a temperature difference between adjacent pixels for each pixel from each pixel temperature detected by each temperature sensor 20 of the temperature sensor group in that the temperature difference between each pixel is detected. It is different from the unit 30A, and the other configuration is basically the same as the configuration of the control unit 30A.

  Therefore, in the following, the temperature of each pixel is estimated from the difference from the control unit 30A, that is, the luminance information of the light emitting element 13, and the temperature difference between the estimated pixel temperature and the ambient temperature of the display unit by the temperature sensor 21 is calculated as a pixel. A specific configuration for detecting each will be mainly described.

  The pixel temperature detection unit 330 uses the characteristic that the organic EL element exhibits a light emitting diode characteristic and there is a proportional relationship between the light emission luminance and the current amount, and detects the light emitting element detected by each light receiving element 19 of the light receiving element group. 13, that is, the current value flowing through each of the light emitting elements 13 is estimated from the brightness information stored in the memory unit 306, the power consumption is calculated from the estimated current value, and the temperature of each pixel is estimated from the calculated power consumption. Thus, the temperature of each pixel is detected.

  Specifically, in the pixel temperature detection unit 330, first, a current value flowing through each of the light emitting elements 13 is estimated from data stored in the memory unit 306, and power consumption is calculated from the estimated current value. Here, in the light emitting element 13, when the current flowing increases and the power consumption increases, the temperature rises in proportion thereto. Therefore, the temperature of the light emitting element 13 is estimated from the power consumption of the light emitting element 13 based on the linear relationship of power consumption-temperature rise. The temperature information for each pixel detected by the pixel temperature detection unit 330 is supplied to the temperature difference detection unit 331 as one input.

  On the other hand, the temperature sensor 21 provided around the display unit of the panel module 10C / 10D detects the ambient temperature of the display unit, that is, the temperature of the environment where the panel module 10C / 10D is installed. The temperature information of the temperature sensor 21 is converted into digital data by the A / D conversion unit 329 and supplied to the temperature difference detection unit 331 as the other input. The temperature difference detection unit 331 detects, for each pixel, a temperature difference (voltage value difference) between individual pixel temperature information detected by the pixel temperature detection unit 330 and the ambient temperature of the display unit detected by the temperature sensor 21. To do.

  The data normalization processing unit 332 has a numerical correlation data table indicating the correspondence between luminance and temperature, and a relative luminance deterioration detection unit is added to the temperature difference between the pixel temperature detected by the temperature difference detection unit 331 and the ambient temperature. By reflecting the relative luminance degradation for each of the high luminance display pixel and the low luminance display pixel detected in 328, the temperature difference between the pixel temperature reflecting the relative luminance degradation of the high luminance display pixel and the ambient temperature The relative luminance degradation amount ΔLa of the low luminance display pixel according to the temperature difference between the pixel temperature reflecting the relative luminance degradation amount of the high luminance display pixel according to the ambient temperature and the relative luminance degradation amount of the low luminance display pixel. And standardize (convert).

  The voltage division calculation unit 333 divides, for each pixel, the relative luminance deterioration amount ΔLa of the high luminance display pixel normalized by the data normalization processing unit 333 by the relative luminance deterioration amount ΔLb of the low luminance display pixel. The temperature characteristic image sticking correlation coefficient ΔLa / ΔLb, which is the result of this division, is obtained by calculating the temperature difference between the pixel temperature and the ambient temperature reflecting the relative luminance degradation of the high luminance display pixel and the relative luminance degradation of the low luminance display pixel. Since it is the ratio between the reflected pixel temperature and the temperature difference between the ambient temperature, it represents the degree of the image sticking phenomenon that occurs due to the difference in luminance degradation due to temperature.

  The voltage division result comparison calculation unit 334 calculates, for each pixel, a temperature difference between the detected pixel temperature and the ambient temperature based on the temperature characteristic burn-in correlation coefficient ΔLa / ΔLb that is a division result of the voltage division calculation unit 333. The degree of image sticking phenomenon that occurs due to the difference in luminance degradation due to temperature is determined.

  Regarding the correspondence between the temperature difference between the pixel temperature and the ambient temperature and the critical point for seizure, consider the same as the correspondence between the temperature difference between adjacent pixels and the critical point for seizure in the first embodiment. Can do.

  Specifically, in FIG. 6, when the temperature difference between adjacent pixels is read as the temperature difference between the pixel temperature and the ambient temperature, when the temperature difference between the pixel temperature and the ambient temperature is 5 ° C., the critical point for occurrence of seizure is 1.53, when the temperature difference between the pixel temperature and the ambient temperature is 10 ° C, the critical point for occurrence of seizure is 1.45, and when the temperature difference between the pixel temperature and the ambient temperature is 15 ° C, the critical point for seizure occurrence is 1.40 When the temperature difference between the pixel temperature and the ambient temperature is 20 ° C., the critical point for image sticking is 1.36, and when the temperature difference between the pixel temperature and the ambient temperature is 25 ° C., the critical point for image sticking is 1.31, when the temperature difference between the pixel temperature and the ambient temperature is 30 ° C., the critical point for occurrence of seizure is 1.24, and when the temperature difference between the pixel temperature and the ambient temperature is 35 ° C., the critical point for seizure occurrence is 1.19 When the temperature difference between the pixel temperature and the ambient temperature is 40 ° C., the critical point for occurrence of seizure is 1.12. .

  That is, ΔLa / ΔLb <1.53 at a temperature difference of 5 ° C., ΔLa / ΔLb <1.45 at a temperature difference of 10 ° C., ΔLa / ΔLb <1.40 at a temperature difference of 15 ° C., and ΔLa / ΔLb <at a temperature difference of 29 ° C. 1.36, ΔLa / ΔLb <1.31 at a temperature difference of 25 ° C., ΔLa / ΔLb <1.24 at a temperature difference of 30 ° C., ΔLa / ΔLb <1.19 at a temperature difference of 35 ° C., ΔLa / at a temperature difference of 40 ° C. If ΔLb <1.12, the seizure phenomenon will not occur.

  Therefore, the voltage division result comparison calculation unit 334 performs the following comparison calculation process. That is, in a certain pixel, for example, when the temperature difference between the detected pixel temperature and the ambient temperature is 15 ° C., for example, the correspondence between the above-described temperature difference between the pixel temperature and the ambient temperature and the critical point for occurrence of seizure. From the above, whether the temperature characteristic seizure correlation coefficient ΔLa / ΔLb is 1.40 or more, that is, whether or not seizure phenomenon occurs, and if it is 1.40 or more, the extent of occurrence of seizure phenomenon, that is, Processing for calculating the difference with respect to the seizure critical point (1.40) is performed.

  The voltage division ratio control unit 335 calculates a control value for each pixel based on the determination result of the degree of occurrence of the image sticking phenomenon by the voltage division result comparison calculation unit 334 for each pixel. Specifically, when it is determined that the seizure phenomenon occurs in the voltage division result comparison operation unit 334 and a difference is calculated with respect to the critical point for occurrence of seizure, a control value corresponding to the difference is calculated. This control value is a luminance correction value for correcting the signal level of the input digital signal so that the relative luminance deterioration due to the temperature characteristics of the light emitting element 13 becomes constant.

  Here, it is assumed that the voltage division calculation unit 333, the voltage division result comparison calculation unit 334, and the voltage division ratio control unit 335 incorporate a correspondence table indicating the correspondence relationship between the calculated voltage value and the luminance. Thus, when performing luminance correction, it is possible to inquire for each circuit unit how much luminance value the calculated voltage value corresponds to, so that smooth correction is possible.

  Based on the brightness correction value (control value) of each pixel calculated by the voltage division ratio control unit 335, the calculation selection control unit 336 performs the high brightness when the correction target pixel is a high brightness display pixel. Selection control is performed to determine whether or not to correct the signal level (luminance level) for the display pixel. Then, based on the selection result by the calculation selection control unit 336, the level control unit 321 performs correction control according to the luminance correction value calculated by the voltage division ratio control unit 335 with respect to the signal level of the high luminance display pixel. Do.

  Here, it is assumed that the voltage difference calculation unit 333, the voltage difference result comparison calculation unit 334, and the voltage difference ratio control unit 335 incorporate a correspondence table indicating the correspondence relationship between the calculated voltage value and the luminance. Thus, when performing luminance correction, it is possible to inquire for each circuit unit how much luminance value the calculated voltage value corresponds to, so that smooth correction is possible.

  Based on the brightness correction value (control value) of each pixel calculated by the voltage division ratio control unit 335, the calculation selection control unit 336 performs the high brightness when the correction target pixel is a high brightness display pixel. Selection control is performed to determine whether or not to correct the signal level (luminance level) for the display pixel. Then, based on the selection result by the calculation selection control unit 336, the level control unit 321 performs correction control according to the luminance correction value calculated by the voltage division ratio control unit 335 with respect to the signal level of the high luminance display pixel. Do.

  In the organic EL display device including the control unit 30B according to the present embodiment having the above-described configuration, as a specific control, the relative luminance deterioration detection unit is used to calculate the relative luminance deterioration amount for each of the high luminance display pixel and the low luminance display pixel. 328, and the temperature difference between the individual pixel temperature and the ambient temperature of the display unit (the temperature of the non-display unit) is detected by the temperature difference detection unit 331. The data normalization processing unit 332 converts the relative luminance deterioration amount ΔLa of the high luminance display pixel and the relative luminance deterioration amount ΔLb of the low luminance display pixel into which the relative luminance deterioration amount of each of the luminance display pixel and the low luminance display pixel is reflected. The temperature correction is performed by normalization (conversion), and the division result of the relative luminance deterioration ΔLa and the relative luminance deterioration ΔLb obtained by the temperature correction, that is, the temperature characteristic burn-in correlation coefficient ΔLa. The brightness correction is controlled based on / ΔLb.

  In this manner, the luminance information of each light emitting element 13 is detected using the luminance information of each light emitting element 13, and the light emitting luminance of each light emitting element 13 is reflected by reflecting the amount of the relative luminance deterioration on the temperature difference from the ambient temperature of each pixel. Specifically, by controlling the light emission luminance of each light emitting element 13 so that the deterioration of the relative luminance due to the temperature of the light emitting element 13 becomes constant, the deterioration of the relative luminance due to the temperature of the device is controlled. Since the image sticking phenomenon caused by the difference can be suppressed, a smooth image display can be realized. Other functions and effects are the same as those of the control unit 30A according to the first embodiment.

  The control unit 30B having the above configuration may be configured to be mounted on the panel module 10A together with a display unit in which pixels are arranged in a matrix and its peripheral drive circuit, or the panel module 10A. You may take the structure provided outside.

  Here, each component of the control unit 30B according to the present embodiment, that is, a level control unit 321, a relative level adjustment unit 322, a memory unit 323, a division unit 324, an A / D conversion unit 325, a memory unit 326, and a multiplication unit 327. , Relative luminance deterioration detection unit 328, A / D conversion unit 329, pixel temperature detection unit 330, temperature difference detection unit 331, data normalization processing unit 332, voltage difference calculation unit 333, voltage difference result comparison calculation unit 334, voltage difference The ratio control unit 335 and the calculation selection control unit 336 have a software configuration using a computer device that performs functions such as information storage processing, signal processing, and arithmetic processing by executing a predetermined program, such as a personal computer. It can be realized by. However, the present invention is not limited to the implementation by software configuration, and can also be implemented by a hardware configuration or a combined configuration of hardware and software.

(Control method)
Next, the processing procedure of the organic EL display device control method according to the present embodiment having the above-described configuration (display device control method according to the present invention) will be specifically described with reference to the flowchart of FIG. The processing by this control method corresponds to the processing of the control unit 30B in FIG. Note that this series of processing is executed in units of pixels in synchronization with the scan cycle.

  Here, as an example, in the display state after the temperature sensor 21 detects 30 ° C. as the ambient temperature of the display unit (temperature of the non-display unit) in the initial state (non-display state) and a predetermined drive period t has elapsed. The temperature of the high-luminance display pixel increases to 60 ° C., and the relative luminance of the high-luminance display pixel at this time is deteriorated by 6% from the initial value La (ΔLa = La × 6%). The brightness correction control in the case where the temperature rises to 45 ° C. and the relative brightness of the low brightness display pixel at this time is deteriorated by 4% from the initial value Lb (ΔLb = Lb × 4%) will be described as an example (FIG. 9). Here, the ambient temperature of 30 ° C. in the initial state means that the initial temperature (temperature of the non-display state) of the light emitting element 13 is 30 ° C.

  Note that the control method is the same for both still images and moving images, and therefore, here, a description will be given of common control for still images / moving images.

  First, a digital video signal for image display is captured (step S31), the gradation value indicated by the signal level of the video signal is stored (step S32), and then the digital video signal is sent to the panel module 10C / 10D. (Step S33). Accordingly, in the panel module 10C / 10D, display driving of the pixels is performed based on the digital input signal, and the light emitting elements 13 of the respective pixels emit light.

  When the light emitting element 13 emits light, the corresponding light receiving element 19 receives the leaked light from the light emitting element 13 and outputs an electric signal corresponding to the amount of received light, that is, a voltage value corresponding to the light emission luminance.

  Thus, when the panel module 10A is in the display driving state, a voltage value (luminance voltage value) corresponding to the light emission luminance output from the light receiving element 19 is captured (step S34), and this luminance voltage value is obtained in step S12. Divide by the stored gradation value (step S35), convert to digital data, and store (step S36).

  Next, for each of the high-luminance display pixel and the low-luminance display pixel, the deterioration of the light emission luminance during a predetermined driving period is detected based on the gradation value stored in step S32 (step S37).

  Note that the gradation value used for the division processing in step S35 and the detection of the luminance deterioration in step S37 is actually the amount of light received by the light receiving element 19 is equal to the amount of light emitted by the light emitting element 13. It is about 20%, and in order to correspond to the voltage value from the light receiving element 19, 20% division processing is performed.

  Next, the current value flowing through each of the light emitting elements 13 is estimated based on the voltage value (luminance voltage value) corresponding to the light emission luminance captured in step S34, and the power consumption is obtained from the estimated current value (step S38). Next, each pixel is detected by estimating the temperature of the light emitting element 13 from the obtained power consumption (step S39), and then the temperature difference between the detected pixel temperature and the ambient temperature detected by the temperature sensor 21. Is detected (step S40).

  In addition, about each process of step S34-S37 for detecting a luminance change part about each of a high-intensity display pixel and a low-intensity display pixel, and each process of step S38-S40 for detecting a temperature change part about each pixel. The processing order may be reversed, or both detection processes may be performed in parallel.

  Next, based on the numerical correlation data table indicating the correspondence between the brightness and the temperature, the brightness deterioration for each of the high brightness display pixel and the low brightness display pixel in which the temperature difference of the ambient sensitivity of each pixel is detected in step S37. Normalized to a voltage value corresponding to the minute (relative luminance degradation of the high luminance display pixel) ΔLa and a voltage value (relative luminance degradation of the low luminance display pixel) ΔLb corresponding to the temperature change of the low luminance display pixel ( (Converted) (step S41).

  Here, when the relative luminance deterioration of the high luminance display pixel due to the temperature change from 30 ° C. to 60 ° C. after the elapse of the predetermined driving period t is 6%, the relative luminance deterioration ΔLa of the high luminance display pixel is For example, when the relative luminance deterioration of the low-luminance display pixel is 4%, which is normalized to a voltage value of 1.2 V and the temperature change from 30 ° C. to 45 ° C. after a predetermined driving period has elapsed, Assume that the relative luminance degradation ΔLb is normalized as a voltage value of 0.8 V, for example.

  Next, the relative luminance degradation amount ΔLa of the low luminance display pixel is divided from the relative luminance degradation amount ΔLa of the high luminance display pixel (step S42), and then the temperature difference ΔT between the high luminance display pixel and the low luminance display pixel is ΔT ≧ It is determined how much of the seizure phenomenon occurs the temperature characteristic seizure correlation coefficient which is the result of division when the temperature is 15 ° C. (= 60 ° C.−45 ° C.) (step S43).

  In this example, the temperature characteristic burn-in correlation coefficient ΔLa / ΔLb is ΔLa / ΔLb = 1.2 V / 0.8 V = 1.50. From the correspondence relationship in FIG. Since the temperature difference ΔT with respect to the display pixel is equal to or higher than the critical point (1.40) at which image sticking occurs when the temperature difference is 15 ° C., it is determined that the image sticking phenomenon occurs due to the difference in relative luminance degradation due to temperature. Then, a process for calculating the degree of occurrence of seizure phenomenon, that is, the difference between the temperature characteristic seizure correlation coefficient ΔLa / ΔLb and the seizure critical point is performed.

  Here, in order to reduce the temperature characteristic image sticking correlation coefficient ΔLa / ΔLb to less than 1.40, that is, to decrease it by a value exceeding 0.10, the relative luminance degradation amount ΔLb of the low-luminance display pixel is reduced to about It may be set to 0.858 V or more, or the relative luminance deterioration ΔLa of the high luminance display pixel may be set to about 1.119 V or less. For this purpose, the signal level of the low-luminance display pixel is amplified by about 0.058 V (= 0.858 V-0.8 V) or more, or the signal level of the high-luminance display pixel is about 0.081 V (= 1.2 V−1). .119V) or more is selected.

  Such processing is executed in each processing step of steps S44 to S46. That is, a luminance correction value for keeping the temperature characteristic burn-in correlation coefficient ΔLa / ΔLb in the range of 1.0 to 1.4 (in the above example, 0.058 V / high luminance display pixel with respect to the low luminance display pixel) 0.081V for each pixel (step S44), and then whether to correct the low luminance display pixel by amplification of the signal level or to correct the high luminance display pixel by attenuation of the signal level (Step S45). Then, based on the selection result, luminance correction is performed by performing amplification control or attenuation control on the signal level (luminance level) of the digital video signal in units of pixels (step S46). ).

  Through the series of processes described above, the deterioration of the relative luminance is detected for each of the high luminance display pixel and the low luminance display pixel, and the temperature difference from the ambient temperature of each pixel (the temperature of the non-display part) is detected. A temperature correction is performed by converting the relative luminance degradation amount ΔLa of the high luminance display pixel corresponding to the degradation amount of the relative luminance for each of the low luminance display pixels and the relative luminance degradation amount ΔLb of the low luminance display pixel. Since the luminance correction is performed so that the temperature characteristic image sticking correlation coefficient ΔLa / ΔLb, which is a result of the division of the relative luminance deterioration ΔLa and ΔLb obtained by the correction, becomes less than the critical point for image sticking, Control is performed so that the degradation of relative luminance due to temperature is constant. Thereby, since the image sticking phenomenon that occurs due to the difference in deterioration of the relative luminance due to the temperature of the light emitting element 13 can be suppressed, a smooth image display can be realized.

  In the present embodiment described above, the luminance information of the light emitting element 13 detected by the light receiving element 19 using the characteristic that the organic EL element exhibits a light emitting diode characteristic and there is a proportional relationship between the light emission luminance and the current amount. The current value flowing through each of the light emitting elements 13 is estimated from this, the power consumption is calculated from this estimated current value, and the temperature of each pixel is detected by estimating the temperature of each pixel from this calculated power consumption. Although the temperature difference between the detected pixel temperature and the ambient temperature is detected, the temperature sensor 20 is arranged corresponding to each pixel as in the panel module 10A / 10B used in the organic EL display device according to the first embodiment. It is also possible to adopt a configuration in which the temperature of each pixel is detected by the temperature sensor and a temperature difference from the detected ambient temperature of the pixel temperature is detected.

  In each of the above embodiments, the organic EL display device including the light emitting elements 13 that emit RGB colors has been described as an example. However, the present invention is not limited to this, and the light emitting that emits white light. The present invention can also be applied to an organic EL display device including an element.

  In each of the above embodiments, the light leakage amount of each of the light emitting elements 13 has been described on the assumption that the light receiving elements 19 are uniformly monitored. However, red light, green light, blue light, or Since the light emission intensity (light emission brightness) differs for each light emitting element that emits white light, level control is performed for each emission color so that the relative levels are aligned, or the amount of light leakage is monitored. It is also possible to limit the types of luminescent colors to be limited by the initial setting.

  In each of the above embodiments, the case where the present invention is applied to an organic EL display device has been described as an example. However, the present invention is not limited to application to an organic EL display device, and a device similar to an organic EL element. The present invention can be applied to all display devices including a self-luminous element such as a PDP (Plasma Display Panel) having a characteristic that the light emission luminance changes according to the temperature change.

It is principal part sectional drawing which shows the outline of a structure of the top emission type panel module used for the organic electroluminescence display which concerns on 1st Embodiment of this invention. It is a top view which shows the outline of a structure of a top emission type panel module. It is principal part sectional drawing which shows the outline of a structure of the bottom emission type panel module used for the organic electroluminescence display which concerns on 1st Embodiment of this invention. It is a block diagram which shows an example of a structure of the control part which concerns on 1st Embodiment. It is explanatory drawing about the definition of division coefficient (DELTA) La / (DELTA) Lb. It is a block diagram which shows an example of a structure of a still image determination part. It is a characteristic view of the luminance degradation due to the temperature of the organic EL element. It is a flowchart which shows the process sequence of the control method which concerns on 1st Embodiment. It is a figure which shows the relative luminance degradation amount of a high-intensity display pixel and a low-intensity display pixel. It is principal part sectional drawing which shows the outline of a structure of the top emission type panel module used for the organic electroluminescence display which concerns on 2nd Embodiment of this invention. It is principal part sectional drawing which shows the outline of a structure of the bottom emission type panel module used for the organic electroluminescence display which concerns on 2nd Embodiment of this invention. It is a block diagram which shows an example of a structure of the control part which concerns on 2nd Embodiment. It is a flowchart which shows the process sequence of the control method which concerns on 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10A, 10C ... Upper surface light emission type panel module, 10B, 10D ... Upper surface light emission type panel module, 11 ... Support substrate, 12 ... Opposite substrate, 13 ... Light emitting element (organic EL element), 14 ... Element isolation insulating layer, 15 ... Lower part Electrode, 16 ... organic layer, 17 ... upper electrode, 18 ... transparent material film, 19 ... light receiving element, 20, 21 ... temperature sensor, 30A, 30B ... control unit, 301, 321 ... level control unit, 302, 322 ... relative Level adjustment unit, 303, 306, 310, 323, 326 ... Memory unit, 304, 324 ... Division unit, 305, 309, 325, 329 ... A / D conversion unit, 307, 327 ... Multiplication unit, 308, 328 ... Relative Luminance deterioration detection unit, 311, 331 ... temperature difference detection unit, 312, 332 ... data normalization processing unit, 313, 333 ... voltage division calculation unit, 314, 334 ... voltage Calculation result comparing unit, 315 and 335 ... voltage dividing ratio control unit, 316 and 336 ... operation selection control section

Claims (13)

A display unit in which a plurality of pixels including a light emitting element formed between a pair of substrates are disposed;
A light receiving element group disposed on one of the pair of substrates in correspondence with each of the light emitting elements, and detecting light leakage of the light emitting elements and performing photoelectric conversion;
A relative luminance deterioration detecting means for detecting a deterioration amount of the relative luminance of the light emitting element based on an input signal to the light emitting element and a detection signal of each light receiving element of the light receiving element group;
Temperature difference detection means for detecting a temperature difference between adjacent pixels for each pixel in the display unit;
The relative luminance deterioration due to the temperature of the light emitting element is reflected by reflecting the amount of deterioration of the relative luminance detected by the relative luminance deterioration detecting means with respect to the temperature difference between each pixel detected by the temperature difference detecting means. And a control means for controlling the light emission luminance of the light emitting element so as to be constant. The display device according to claim 1, wherein each temperature sensor of the temperature sensor group is disposed on a substrate on the opposite side to the light extraction direction of the pair of substrates. The display device according to claim 2, wherein each temperature sensor of the temperature sensor group is disposed to face each of the light emitting elements across the opposite substrate. The relative luminance deterioration detecting means identifies a high luminance display pixel and a low luminance display pixel based on a detection signal of each light receiving element of the light receiving element group, and for each of the high luminance display pixel and the low luminance display pixel. Detects the degradation of relative luminance during a predetermined drive period,
The control means is configured to detect relative to each of the high-luminance display pixel and the low-luminance display pixel detected by the relative luminance deterioration detection unit with respect to a temperature difference between adjacent pixels detected by the temperature difference detection means. The display device according to claim 1, further comprising: a normalization processing unit that reflects luminance degradation, and controlling the light emission luminance of the light emitting element based on a processing result of the normalization processing unit. The control means includes
A first voltage value corresponding to the temperature difference reflecting the luminance change amount of the high luminance display pixel in the normalization processing unit is used as a second voltage corresponding to the temperature difference reflecting the luminance change amount of the low luminance display pixel. A division operation unit for dividing by the voltage value of
A comparison operation unit that compares the division result of the division operation unit with a predetermined reference value;
A division ratio control unit that calculates a luminance correction value based on a comparison result of the comparison operation unit;
The display device according to claim 4, further comprising: a level control unit that controls a signal level of the input signal based on a luminance correction value of each pixel calculated by the division ratio control unit. A determination unit that determines whether the image is a still image or a moving image based on the input signal;
The display device according to claim 1, wherein when the determination unit determines that the image is a still image, the signal level of the input signal is multiplied by a predetermined magnification. A display unit in which a plurality of pixels including a light emitting element formed between a pair of substrates are disposed;
A light receiving element group disposed on one of the pair of substrates in correspondence with each of the light emitting elements, and detecting light leakage of the light emitting elements and performing photoelectric conversion;
A relative luminance deterioration detecting means for detecting a deterioration amount of the relative luminance of the light emitting element based on an input signal to the light emitting element and a detection signal of each light receiving element of the light receiving element group;
A temperature sensor for detecting an ambient temperature of the display unit;
A temperature difference detecting means for detecting a temperature difference from the ambient temperature detected by the temperature sensor for each pixel in the display unit;
The relative luminance deterioration due to the temperature of the light emitting element is reflected by reflecting the deterioration of the relative luminance detected by the relative luminance deterioration detecting means with respect to the temperature difference between the individual pixels detected by the temperature difference detecting means. And a control means for controlling the light emission luminance of the light emitting element so as to be constant. The temperature difference detecting means estimates the temperature of each pixel from the luminance information of the light emitting element detected by each light receiving element of the light receiving element group, and the estimated pixel temperature and the ambient temperature detected by the temperature sensor. The display device according to claim 7, wherein the temperature difference is detected for each pixel. The relative luminance deterioration detecting means identifies a high luminance display pixel and a low luminance display pixel based on a detection signal of each light receiving element of the light receiving element group, and for each of the high luminance display pixel and the low luminance display pixel. Detects the degradation of relative luminance during a predetermined drive period,
The control means is configured to detect relative to each of the high-luminance display pixel and the low-luminance display pixel detected by the relative luminance deterioration detection unit with respect to a temperature difference from the ambient temperature of each pixel detected by the temperature difference detection means. The display device according to claim 7, further comprising: a normalization processing unit that reflects luminance degradation, and controlling light emission luminance of the light emitting element based on a processing result of the normalization processing unit. The control means includes
A first voltage value corresponding to the temperature difference reflecting the luminance change amount of the high luminance display pixel in the normalization processing unit is used as a second voltage value corresponding to the temperature difference reflecting the luminance change amount of the low luminance display pixel. A division operation unit for dividing by the voltage value of
A comparison operation unit that compares the division result of the division operation unit with a predetermined reference value;
A division ratio control unit that calculates a luminance correction value based on a comparison result of the comparison operation unit;
The display device according to claim 4, further comprising: a level control unit that controls a signal level of the input signal based on a luminance correction value of each pixel calculated by the division ratio control unit. A determination unit that determines whether the image is a still image or a moving image based on the input signal;
The display device according to claim 1, wherein when the determination unit determines that the image is a still image, the signal level of the input signal is multiplied by a predetermined magnification. A control method for a display device in which a plurality of pixels including light emitting elements formed between a pair of substrates are arranged,
A leakage light detection step of detecting leakage light of the light emitting element by each light emitting element of the light emitting element group arranged corresponding to each of the light emitting elements on one of the pair of substrates;
A relative luminance deterioration detection step for detecting a deterioration amount of the relative luminance of the light emitting element based on an input signal to the light emitting element and a detection signal of each light receiving element of the light receiving element group;
A temperature difference detection step of detecting a temperature difference between adjacent pixels for each pixel in the display unit;
The relative luminance deterioration due to the temperature of the light emitting element is reflected by reflecting the deterioration of the relative luminance detected in the relative luminance deterioration detecting step on the temperature difference between each pixel detected in the temperature difference detecting step. And a control step of controlling the light emission luminance of the light emitting element so as to be constant. A display device control method comprising: a display unit in which a plurality of pixels including light emitting elements formed between a pair of substrates are arranged; and a temperature sensor that detects an ambient temperature of the display unit,
A leakage light detection step of detecting leakage light of the light emitting element by each light emitting element of the light emitting element group arranged corresponding to each of the light emitting elements on one of the pair of substrates;
A relative luminance deterioration detection step for detecting a deterioration amount of the relative luminance of the light emitting element based on an input signal to the light emitting element and a detection signal of each light receiving element of the light receiving element group;
A temperature difference detecting step for detecting a temperature difference from the ambient temperature detected by the temperature sensor for each pixel in the display unit;
The relative luminance deterioration due to the temperature of the light emitting element is reflected by reflecting the deterioration of the relative luminance detected in the relative luminance deterioration detecting step with respect to the temperature difference with the ambient temperature of each pixel detected in the temperature difference detecting step. And a control step of controlling the light emission luminance of the light emitting element so as to be constant.

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