JP2007286374A - 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 individual devices (e.g. organic EL elements) can individually be brought under optimum luminance control without being affected by differences in variation in light emission luminance-applied voltage characteristics among the devices. <P>SOLUTION: A light emission luminance variation detector 308 detects a value of variation in light emission luminance based upon a detection output of a photodetector 19 with respect to each of high-luminance display pixels and low-luminance display element, and a temperature detector 311 detects a value of temperature variation of each pixel based upon a detection output of a temperature sensor 20. A data standardization processing unit 312 standardizes(converts) values of temperature variation of the individual pixels into luminance values La of the high-luminance display pixels and luminance values Lb of the low-luminance display pixels corresponding to the values of luminance variation of the high-luminance display pixels and low-luminance display pixels, thereby performing temperature correction. Then the luminance values La and Lb obtained through the temperature correction are used to control luminance correction. <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. 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. . 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.

  Therefore, the present invention provides a display device and a display device capable of performing optimal brightness control for each device without being affected by a difference in change due to temperature of light emission brightness-applied voltage characteristics of each device. It is an object to provide a control method.

  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 luminance of each light emitting element is detected by detecting leakage light of the light emitting element by the light receiving element, and a temperature sensor is arranged corresponding to each of the light emitting elements, The temperature of each light emitting element is detected by the temperature sensor, and the light emission luminance of the light emitting element is controlled based on the input signal to the light emitting element, the detection signal of the light receiving element, and the detection signal of the temperature sensor.

  In the display device having the above-described configuration, by controlling the light emission luminance of each light emitting element using not only the temperature information of each light emitting element but also the luminance information of each light emitting element, the change in the light emission luminance accompanying the change in temperature is controlled. Even if the method differs depending on the device, it is possible to reflect the change state of the brightness of each light emitting element in the control of the light emission brightness according to the temperature change of each light emitting element.

  According to the present invention, since the luminance change state of each light emitting element can be reflected in the control of the light emission luminance according to the temperature change of each light emitting element, it is caused by the temperature of the light emitting luminance-applied voltage characteristic of each device. Optimal brightness control can be performed for each device without being affected by the difference in change.

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

  FIG. 1 is a cross-sectional view of a principal part showing an outline of a configuration of a panel module of a display device according to an embodiment of the present invention, for example, a top emission organic EL display device.

(Top-emitting organic EL display device)
As shown in FIG. 1, the organic EL display device 10 includes a support substrate 11 and a counter substrate 12, and has a configuration in which a light emitting element 13 is provided between the substrates 11 and 12. . The support substrate 11 is appropriately selected from a transparent substrate such as quartz or glass, a silicon substrate, or the like.

  Here, an active matrix system is adopted as a driving system of the organic EL display device 10. However, the driving method of the organic EL display device 10 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. 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 panel module of the so-called top emission type organic EL display device 10 that takes out the light emitted from the organic layer 16 of the light emitting element 13 from the counter substrate 12 side is configured. In the panel module of the top emission organic EL display device 10, a portion facing the light emitting element 13 on one main surface (outer surface) of the support substrate 11 on the side opposite to the light extraction direction, that is, on the support substrate 11 side. Is provided with a temperature sensor 20.

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

(Bottom-emitting organic EL display device)
FIG. 3 is a cross-sectional view of an essential part showing an outline of the configuration of the panel module of the bottom emission type organic EL display device according to one embodiment of the present invention. In FIG. 3, the same parts as those in FIG. It shows.

  As shown in FIG. 3, in the case of the bottom emission type organic EL display device 10 ′, the emitted light from the organic layer 16 is taken out from the support substrate 11 side. The 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 panel module of the bottom emission organic EL display device 10 ′ is structurally different from the panel module of the top emission organic EL display device 10, and the top emission organic EL display for other structures. This is basically the same as the panel module of the apparatus 10.

  The top emission organic EL display device 10 or the bottom emission organic EL display device 10 ′ according to the present embodiment described above includes a control unit described below in addition to the panel module. The panel module is configured to perform display control (drive control).

(Control part)
FIG. 4 is a block diagram illustrating an example of a configuration of a control unit that controls the panel module 10A having the above-described configuration.

  As shown in FIG. 4, the control unit 30 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, a memory unit 306, and a multiplication unit 307. , Emission luminance change detection unit 308, A / D conversion unit 309, memory unit 310, temperature change detection unit 311, data normalization processing unit 312, voltage division unit 313, voltage division result comparison calculation unit 314, voltage division ratio control unit 315 and a calculation selection control unit 316.

  The control unit 30 performs display control of each pixel of the display unit in the panel module 10A according to the input digital video signal, while detecting signals of the light receiving elements 19 of the light receiving element group provided in the panel module 10A. Is used to monitor the light emission luminance change of each pixel, and the temperature change of each pixel is monitored based on the detection signal of each temperature sensor 20 of the temperature sensor group provided in the panel module 10A. The drive control of the light emitting element 13 is performed so that the ratio (contrast) of the light emission intensity of the luminance display portion is constant.

  In the control unit 30, 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 10 </ b> A. To be supplied. Each function of the level control unit 301 and the relative level adjustment unit 302 will be described later.

  In the panel module 10A, 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 display data corresponding to the digital video signal is selected for each pixel in this selected row. Is written, 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 light emission luminance change detection unit 308 determines, from the data stored in the memory unit 306, a pixel that emits light at the highest luminance on one display screen or a luminance near the high luminance display pixel, and a pixel that emits light at the lowest luminance or a luminance near the low luminance. Light is recognized as a luminance display pixel, and light emission in a predetermined period (for example, one frame period) is performed for each of the high luminance display pixel and the low luminance display pixel based on the gradation value provided from the memory unit 303 via the multiplication unit 307. A change in luminance (emission intensity) (difference in voltage value) is detected.

  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 change detection unit 311 detects, for each pixel, a temperature change (voltage value difference) in a predetermined period (for example, one frame period) based on the stored data about the detected temperature stored in the memory unit 310. .

  The data normalization processing unit 312 has a numerical correlation data table indicating the correspondence between luminance and temperature, and the emission luminance change detection unit 308 detects the temperature change of each pixel detected by the temperature change detection unit 311. The first voltage value (hereinafter referred to as “high voltage”) corresponding to the temperature change reflecting the luminance change of the high luminance display pixel is reflected by reflecting the luminance change of each of the high luminance display pixel and the low luminance display pixel. "Luminance value of the luminance display pixel" La) and a second voltage value corresponding to the temperature change amount reflecting the luminance change amount of the low luminance display pixel (hereinafter, "the luminance value of the low luminance display pixel") Standardize (convert) to Lb.

  The voltage division calculation unit 313 divides the luminance value La of the high luminance display pixel normalized by the data normalization processing unit 312 by the luminance value Lb of the low luminance display pixel for each pixel. This division ratio La / Lb is a ratio between the brightness of the high-luminance display pixel and the brightness of the low-luminance display pixel, and therefore represents the contrast.

  The voltage division result comparison operation unit 314 compares the division result La / Lb in the voltage division operation unit 313 with a constant ratio (reference value) R set corresponding to a desired contrast for each pixel, The difference of the division result La / Lb with respect to the ratio R is calculated. The difference of the division ratio L1 / L2 with respect to the reference value R becomes a variation due to a temperature change of each pixel with respect to a desired contrast. The fixed ratio R can be arbitrarily set.

  The voltage division ratio control unit 315 is a control value corresponding to the difference of the division ratio La / Lb with respect to the constant ratio R calculated by the voltage division result comparison calculation unit 314, specifically, such that the difference becomes almost zero. That is, a control value is calculated for each pixel so that the division ratio La / Lb becomes a constant ratio R. This control value is a luminance correction value that corrects a change in luminance caused by the temperature of each pixel.

  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.

  The arithmetic selection control unit 316 increases the luminance of the signal level (luminance level) of each pixel of the digital video signal based on the luminance correction value (control value) of each pixel calculated by the voltage division ratio control unit 315. Or to control the brightness to decrease. Then, based on the selection result by the calculation selection control unit 316, the level control unit 301 controls the signal level (luminance level) of the pixel unit of the digital video signal.

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

As shown in FIG. 5, for example, 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 V1N of the Nth frame and the previous frame stored in the frame memory 30211. 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 light emission luminance change detection unit 308 detects the amount of change in the light 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 as a still image, the light emission luminance change 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 the still image, a correspondence table between the signal level at the time of the 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 the 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 10 (10 ′) according to the present embodiment having the above-described configuration, the organic EL element used as the light-emitting element 13 is deteriorated in the organic layer 16 (see FIG. 1) due to heat generated due to light emission. However, there is a problem of deterioration over time such that light emission itself becomes unstable. In addition, the organic EL element exhibits a light emitting diode characteristic, and the current flowing through the device increases proportionally as the temperature rises, resulting in a proportional relationship with the light emission luminance.

  FIG. 6 shows an example of the temperature dependence of the light emission luminance-applied voltage characteristics of the organic EL element. Specifically, an applied voltage of a certain voltage value is applied to the device (organic EL element), and when the temperature of the device is 30 ° C., the emission luminance is L1, and the temperature is 45 ° C. When the temperature further rises to 60 ° C., the emission luminance changes to L2 (L1 <L2) and further to L3 (L2 <L3) as the temperature rises.

  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 condition that the light emission luminance changes as the temperature of the device rises and the method of the change varies from device to device, the organic EL display device 10 (10 ') according to the present embodiment has the following configuration. It is characterized by adopting.

  That is, in the organic EL display device 10 (10 ′) according to the present embodiment, each of the light emitting elements 13 is disposed on one of the pair of substrates 11 and 12, specifically, on the counter substrate 12 side on the light extraction side. Each of the pixels including the light emitting element 13 is detected by the temperature sensor 20 while detecting the luminance of each light emitting element 13 by detecting the leakage light of the light emitting element 13 by the light receiving element 19. Under the control of the control unit 30, the input digital signal, the detection signal of the light receiving element 19, and the detection signal of the temperature sensor 20 are used to detect a change in light emission luminance during a predetermined period, A configuration is adopted in which the light emission luminance of the light emitting element 13 is controlled based on the change in the light emission luminance.

  As described above, not only the temperature information of each light emitting element 13 but also the luminance information of each light emitting element 13 is used to detect a change in light emission luminance, and each light emitting element 13 emits light based on the change in the light emission luminance. By controlling the brightness, specifically, by controlling the brightness of each light emitting element 13 so that the contrast is constant, even if the method of changing the brightness due to the temperature change varies from device to device. Since the change in luminance of each light emitting element 13 can be reflected in the control of light emission luminance according to the temperature change of each pixel, the difference in change due to the temperature of the light emission luminance-applied voltage characteristics of each device can be reflected. Optimal brightness control can be performed for each device without being affected.

  In the luminance control by the control unit 30, as specific control, the light emission luminance change for each of the high luminance display pixel and the low luminance display pixel is detected by the light emission luminance change detection unit 308, and the temperature change amount of each pixel is detected. The temperature change detection unit 311 detects the temperature change of each pixel, and the brightness value La of the high brightness display pixel corresponding to the brightness change amount for each of the high brightness display pixel and the low brightness display pixel and the low brightness display. Temperature correction is performed by normalizing (converting) the pixel brightness value Lb to the pixel brightness value Lb, and brightness correction control is performed using the brightness values La and Lb obtained by the temperature correction. ing.

  By such brightness correction control, it is possible to perform the correction control so that the brightness ratio (brightness ratio) between the high brightness display pixel and the low brightness display pixel, that is, the contrast is always constant. Optimum brightness control can be performed for each device without being affected by the specific emission brightness-applied voltage characteristics, and even if the method of changing the characteristics varies from device to device. Therefore, it is possible to always display an image with a uniform contrast.

  Further, in the organic EL display device 10 (10 ′) according to the present embodiment, the temperature sensor 20 for detecting the temperature of each pixel is the same as the pair of substrates 11 and 12 regardless of the top emission type or the bottom emission type. By adopting the configuration arranged on the support substrate 11 opposite to the light extraction direction, it is not necessary to secure an extra space for arranging the temperature sensor 20 in plan view on the panel module 10A. It does not suppress the display area or prevent the panel size from being reduced.

  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 30 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 30 in the organic EL display device 10 (10 ′) according to the present embodiment, that is, a level control unit 301, a relative level adjustment unit 302, a memory unit 303, a division unit 304, A / D conversion. Unit 305, memory unit 306, multiplication unit 307, light emission luminance change detection unit 308, A / D conversion unit 309, memory unit 310, temperature change detection unit 311, data normalization processing unit 312, voltage division unit 313, voltage division result About the comparison calculation part 314, the voltage division ratio control part 315, and the calculation selection control part 316, the computer which performs each function, such as an information storage process, a signal process, and a calculation process, by executing a predetermined program like a personal computer It can be realized by using a device and a software configuration. 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 control method of the organic EL display device 10 (10 ′) according to the present embodiment having the above-described configuration (the 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 30 in FIG. Note that this series of processing is executed in units of pixels in synchronization with the scan cycle.

  Here, as an example, when the initial temperature of the light emitting element 13 is 30 ° C., the luminance value of the high luminance display pixel is La and the luminance value of the low luminance display pixel is Lb. The temperature of the high-luminance display pixel is increased to 60 ° C., and the luminance value of the high-luminance display pixel at this time is changed by 110% (La × 110%) from the initial value La. The brightness correction control in the case where the brightness value of the low brightness display pixel at this time has changed by 105% (Lb × 105%) from the initial value Lb will be described as an example.

  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 S11), the gradation value indicated by the signal level of the video signal is stored (step S12), and then the digital video signal is input to the panel module 10A. (Step S13). Thereby, in the panel module 10A, 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, a change in light emission luminance (voltage value difference) in a predetermined 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 change in step S17 is actually 20% of the light emission amount of the light emitting element 13 when the light receiving amount of the leakage light received by the light receiving element 19 is 20%. 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 a temperature change (voltage value difference) is detected for each pixel. (Step S19).

  In addition, about each process of step S14-S17 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 S18, S19 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 brightness and temperature, the temperature change of each pixel is detected for each of the high brightness display pixel and the low brightness display pixel detected by the light emission intensity change detection unit 308. Normalized (converted) into a voltage value (brightness value of the high-brightness display pixel) La corresponding to the luminance change amount and a voltage value (brightness value of the low-brightness display pixel) Lb corresponding to the temperature change amount of the low-brightness display pixel. (Step S20).

  Here, when the change in the luminance value of the high luminance display pixel due to the temperature change from 30 ° C. to 60 ° C. after the predetermined period has elapsed is 110%, the luminance value La of the high luminance display pixel is, for example, a voltage value of 4.0V. When the change in the luminance value of the low luminance display pixel accompanying the temperature change from 30 ° C. to 45 ° C. after the lapse of the predetermined period is 105%, the luminance value Lb of the low luminance display pixel is, for example, 1.5V. It shall be normalized as a voltage value.

  Next, the luminance value La of the high luminance display pixel is divided by the luminance value Lb of the low luminance display pixel (step S21), and then the division result La / Lb is set to a certain ratio (corresponding to a desired contrast). Compared with the reference value (R), the difference of the division result La / Lb with respect to the constant ratio R is calculated as a variation due to the temperature change of each pixel with respect to the desired contrast (step S22).

  Here, the constant ratio R is set to R = 2.0. However, this numerical value is an example and can be set arbitrarily. In this example, since the division result La / Lb is 4.0 V / 1.5 V with respect to R = 2.0, a variation due to a temperature change occurs. In this case, if the luminance value La of the high-luminance display pixel can be set to 3.0V, the division result La / Lb becomes La / Lb = 3.0V / 1.5V, which matches the constant ratio R (= 2.0). Therefore, no change in luminance occurs. That is, the high luminance display pixel may be controlled to subtract 1.0 V from the video signal level.

  Such processing is executed in each processing step of steps S23 to S25. That is, a control value is calculated for each pixel so that the difference between the division ratio La / Lb and the constant ratio R becomes substantially zero, that is, the division ratio La / Lb becomes the constant ratio R (step S23). This control value is a luminance correction value that corrects a change in luminance caused by the temperature of each pixel. In this example, the luminance correction value for the high luminance display pixel is −1.0V.

  Next, based on the brightness correction value (control value) of each pixel, it is determined whether the signal level (brightness level) of the pixel unit of the digital video signal is controlled to increase the brightness or to decrease the brightness. Then, the luminance is corrected by controlling the signal level (luminance level) of each pixel of the digital video signal based on the selection result (step S25). In this example, control for subtracting 1.0 V from the video signal level is performed on the high luminance display pixel.

  Through the series of processes described above, the change in emission luminance is detected for each of the high luminance display pixel and the low luminance display pixel, and the temperature change of each pixel is detected as the luminance change for each of the high luminance display pixel and the low luminance display pixel. The temperature correction is performed by converting the luminance value La of the high luminance display pixel corresponding to the minute and the luminance value Lb of the low luminance display pixel, and the luminance correction is performed using the luminance values La and Lb obtained by the temperature correction. Therefore, correction control can be performed so that the contrast is always constant, and the method of changing the characteristics of each device is not affected by the light emission luminance-applied voltage characteristics unique to the self-light-emitting element. Even if they are different, optimum brightness control can be performed for each device without being affected by the difference. As a result, image display can always be performed with uniform contrast.

  In the above embodiment, the organic EL display devices 10 and 10 ′ including the light emitting elements 13 that emit RGB colors are described as examples. However, the present invention is not limited to this, and white light is emitted. The present invention can also be applied to an organic EL display device including a light emitting element that emits light.

  In the above embodiment, 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 white light has been described. Since the light emission intensity (light emission luminance) is different for each light emitting element that emits 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 type of emission color by the initial setting.

  Moreover, although the case where it applied to the organic electroluminescent display apparatus was mentioned as an example and demonstrated in the said embodiment, this invention is not restricted to the application to an organic electroluminescent display apparatus, Like an organic electroluminescent element, it is the device of a device. 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 light emission luminance changes according to a temperature change.

It is principal part sectional drawing which shows the outline of a structure of the panel module of the top emission type organic electroluminescence display to which this invention is applied. It is a top view which shows the outline of a structure of the panel module of a top emission type organic electroluminescence display. It is principal part sectional drawing which shows the outline of a structure of the panel module of the bottom emission type organic electroluminescence display to which this invention is applied. It is a block diagram which shows an example of a structure of a control part. It is a block diagram which shows an example of a structure of a still image determination part. It is a characteristic view which shows an example of the temperature dependence of the light emission luminance-applied voltage characteristic of an organic EL element. It is a flowchart which shows the process sequence of the control method of the display apparatus by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,10 '... Organic EL display apparatus, 10A ... Panel module, 11 ... Support substrate, 12 ... Opposite substrate, 13 ... Light emitting element (organic EL element), 14 ... Element isolation insulating layer, 15 ... Lower electrode, 16 ... Organic Layer, 17 ... upper electrode, 18 ... transparent material film, 19 ... light receiving element, 20 ... temperature sensor, 30 ... control unit, 301 ... level control unit, 302 ... relative level adjustment unit, 303, 306, 310 ... memory unit, 304: division unit, 305, 309 ... A / D conversion unit, 307 ... multiplication unit, 308 ... emission luminance change detection unit, 311 ... temperature change detection unit, 312 ... data normalization processing unit, 313 ... voltage division unit, 314 ... voltage division result comparison operation unit, 315 ... voltage division ratio control unit, 316 ... operation selection control unit

Claims (7)

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 temperature sensor group that is arranged corresponding to each of the light emitting elements and detects the temperature of the light emitting elements;
A control unit that controls the light emission luminance of the light emitting element based on an input signal to the light emitting element, a detection signal of each light receiving element of the light receiving element group, and a detection signal of each temperature sensor of the temperature sensor group; A display device characterized by that. 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 controller is
Based on the detection signal of each light receiving element in the light receiving element group, the high luminance display pixel and the low luminance display pixel are identified, and the luminance change in a predetermined period is detected for each of the high luminance display pixel and the low luminance display pixel. A light emission luminance change detecting unit,
A temperature change detection unit that detects a temperature change amount in a predetermined period of each pixel based on an output of each temperature sensor of the temperature sensor group;
Normalization of reflecting the luminance change amount of each of the high luminance display pixel and the low luminance display pixel detected by the light emission luminance change detection unit with respect to the temperature change amount of each pixel detected by the temperature change detection unit. A processing unit,
The display device according to claim 1, wherein the light emission luminance of the light emitting element is controlled so that the contrast becomes constant based on a processing result of the normalization processing unit. The controller is
The normalization processing unit uses the first voltage value corresponding to the temperature change reflecting the luminance change of the high luminance display pixel as the temperature change corresponding to the luminance change of the low luminance display pixel. A division operation unit for dividing by the second voltage value;
A comparison operation unit that compares the division result of the division operation unit with a fixed ratio set corresponding to a predetermined contrast and calculates the difference;
A division ratio control unit that calculates a luminance correction value according to the difference calculated by the comparison calculation 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 for determining 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 temperature detecting step of detecting the temperature of the light emitting element by each temperature sensor of a temperature sensor group arranged corresponding to each of the light emitting elements;
And a control step of controlling light emission luminance of the light emitting element based on an input signal to the light emitting element, a detection signal in the leakage light detection step, and a detection signal in the temperature detection step. Control method of the device.

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