JP2007240812A - Driving method of light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display images of high quality free from color deviation by detecting a temperature of a display area in a light emitting device like an organic EL device. <P>SOLUTION: A driving method of the light emitting device, which drives the light emitting device provided with a plurality of pixel parts 70 including organic EL elements 72 respectively in an image display area 110, includes steps of; detecting a temperature of organic EL elements 72 by detecting a current value of an organic EL element 79 for temperature sensor selected from organic EL elements 72 as a temperature sensor; calculating an application current to be applied to organic EL elements 72 in accordance with the detected temperature in order to cause organic EL elements 72 to emit light with prescribed luminance; and applying the calculated application current to organic EL elements 72. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technical field of a driving method of a light emitting device such as an organic EL panel.

  An organic EL material used for a light-emitting element of an organic EL (Electro-luminescence) panel, which is an example of this type of light-emitting device, has a problem that light emission luminance varies depending on the temperature characteristic of the material depending on the ambient temperature used. It is known that there is. In the RGB independent light-emitting panel, color shift occurs due to the difference in temperature characteristic peculiar to this material, and the display quality is remarkably deteriorated. The term “color shift” as used herein refers to (1) an IL characteristic (that is, a current-light output characteristic) caused by a temperature difference that can occur in the substrate plane (particularly, a pixel near the center and a pixel near the outer periphery). Change (shift), (2) Change (shift) in IL characteristics due to different temperature characteristics for each RGB, (3) IL characteristics due to heat generated from TFTs and peripheral circuits (wiring), etc. A change (displacement). Regarding such problems, for example, in Patent Document 1, a measurement EL element as a temperature sensor is provided for measuring the temperature of an organic EL panel, and driving is applied to the organic EL element based on the measured temperature. A technique for correcting a waveform is disclosed.

JP 2001-35655 A

  However, in the technique disclosed in Patent Document 1, since the temperature sensor is formed in a region different from the display region in the light emitting substrate on which the light emitting element is formed, it is difficult to accurately measure the temperature of the light emitting element. There is a technical problem. If a temperature sensor is to be formed in the display region on the light emitting substrate side, the light emitting substrate may have a complicated structure such as a multilayer structure, or the aperture ratio of the display region may be reduced. In particular, forming a temperature sensor near the center of the board makes it difficult to route the circuit, and heat generation / heat dissipation due to routing wiring must also be considered. Installation of an external sensor, which is a conventional technology, on a light-emitting panel cannot take advantage of the small size, thinness, lightness, and the like of an organic EL panel, for example.

  The present invention has been made in view of the above-described problems, for example, and provides a driving method of a light-emitting device capable of detecting the temperature in the display region of the light-emitting device and capable of displaying a high-quality image without color shift. Let it be an issue.

  In order to solve the above problems, a driving method of a light emitting device of the present invention is a driving method of a light emitting device for driving a light emitting device provided with a plurality of pixel portions each including a light emitting element in a display region, Detecting a current value of the light emitting element included in at least one of the plurality of pixel parts, and detecting a temperature of the light emitting element, and according to the temperature detected by the temperature detecting process And an applied current calculating step for calculating an applied current to be applied to the light emitting element so that the light emitting element emits light with a predetermined luminance, and a current applying step for applying the applied current to the light emitting element.

  According to the driving method of the light-emitting device of the present invention, during the operation, an applied current is applied to the light-emitting element in each pixel unit, so that a light-emitting layer such as an organic EL (Electro-Luminescence) layer is formed in the light-emitting element. Emits light. In this case, the luminance of the pixel portion is controlled by the applied current. In such an operation, for example, the temperature of the pixel portion is caused by heat generated when the light emitting element emits light, heat generated by a semiconductor element such as a TFT (Thin Film Transistor) provided in the pixel portion, wiring resistance, or the like. May change. The light-emitting element has a temperature characteristic that light emission luminance with respect to an applied current differs when the temperature used is different, and there is a possibility that the luminance in the pixel portion also changes as the temperature of the pixel portion changes.

  However, in the present invention, in particular, the temperature of the light emitting element is detected by detecting the current value of the light emitting element included in at least one of the plurality of pixel portions in the temperature detecting step. That is, the temperature of the light emitting element is detected using the temperature characteristics of the light emitting element included in the pixel portion selected as the temperature sensor for detecting the temperature of the light emitting element among the plurality of pixel portions. Here, the temperature characteristic of the light-emitting element means a property that a voltage required to apply a predetermined current to the light-emitting element changes with a temperature change. For example, it is necessary to apply a predetermined current to the light-emitting element. It can be expressed as the amount of change per unit temperature of the correct voltage.

  Since the temperature of the light emitting element is detected using the temperature characteristics of the light emitting element included in the pixel portion provided in the display area in this manner, for example, a temperature sensor provided in an area different from the display area is used. Compared to the case of detecting the temperature, the temperature of the light emitting element can be detected near the light emitting element (in particular, the light emitting element itself). Therefore, the temperature of the light emitting element can be detected with higher accuracy.

  Further, in the present invention, in particular, the applied current calculation step calculates the applied current to be applied to the light emitting element so that the light emitting element emits light with a predetermined luminance according to the temperature detected by the temperature detection step. Subsequently, the applied current calculated in this way is applied to the light emitting element by the current application step. In other words, an applied current corrected to emit light with a predetermined luminance at the detected temperature is applied to the light emitting element. Therefore, it is possible to control the luminance of the pixel portion to be a predetermined luminance according to the detected temperature. That is, it is possible to reduce or prevent a change in light emission luminance due to a temperature change of the light emitting element or a deviation from a predetermined luminance. Therefore, high quality image display is possible.

  In addition, in the present invention, in particular, the temperature detection step detects the temperature of the light emitting element by using the temperature characteristic of the light emitting element formed in the pixel portion and contributing to display. Compared to the case of forming a temperature sensor for detecting, little or no complication of the manufacturing process is required.

  As described above, according to the driving method of the light emitting device of the present invention, the temperature of the light emitting element included in at least one of the plurality of pixel portions is detected and corrected according to the detected temperature. Since current is applied to the light emitting element, high-quality image display is possible. In particular, the temperature detection process detects the temperature of the light emitting element by utilizing the temperature characteristics of the light emitting element that contributes to the display, so that it is possible to detect the temperature in the display region and almost complicate the manufacturing process. Or not at all.

  In one aspect of the driving method of the light emitting device of the present invention, the light emitting element includes three types of light emitting elements each including a light emitting layer that emits one of R (red), G (green), and B (blue) colors. The temperature detecting step detects the temperature of each of the three types of light emitting elements, and the applied current calculating step calculates the applied current for each of the three types of light emitting elements.

According to this aspect, it is possible to reduce or prevent color misregistration that may occur in RGB independent light-emitting panels and that is caused by the difference between the light emitting pixel temperatures at the center and the end of the panel. That is, by accurately detecting the temperature for each RGB pixel and feeding back to the calculation of the applied current for each RBG pixel,
Color shift due to temperature difference can be further reduced or eliminated.

  In another aspect of the method for driving a light emitting device of the present invention, the light emitting element includes a light emitting material having a temperature characteristic of 5 mV / ° C. or higher.

  According to this aspect, since the current fluctuation in the light emitting element with respect to the temperature change is large, the temperature of the light emitting element can be easily detected by the temperature detecting step. That is, the light emitting element can easily function as a temperature sensor. Here, “temperature characteristic of 5 mV / ° C.” means that the amount of change per unit temperature of the voltage required to apply a predetermined current is 5 mV.

  In another aspect of the driving method of the light emitting device of the present invention, the temperature detecting step detects a current value by applying a predetermined voltage to the light emitting element included in the at least one pixel portion.

  According to this aspect, for example, a current value is detected by applying a predetermined voltage to the light emitting element during a non-display period that does not contribute to display, so that the current value can be detected with high accuracy. Therefore, the temperature of the light emitting element can be detected with high accuracy.

  In another aspect of the driving method of the light emitting device of the present invention, the temperature detecting step detects temperatures of the light emitting elements included in a plurality of pixel portions in the display region.

  According to this aspect, for example, the temperature of the light emitting element in at least one pixel portion in each of the central portion and the peripheral portion of the display region is detected. Therefore, it is possible to detect temperature variations of the plurality of pixel portions in the display area, that is, temperature distribution. Therefore, luminance variations in the display area can be reduced or prevented. This is particularly effective when the display area is large, that is, when the size of the light-emitting panel is large.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the method for driving a light emitting device of the present invention is applied to an organic EL device.
<First Embodiment>
A method of driving the organic EL device according to the first embodiment of the present invention will be described with reference to FIGS.

  First, the overall configuration of the organic EL device according to the present embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing the overall configuration of the organic EL device according to this embodiment.

  In FIG. 1, an organic EL device 10 which is an example of a “light emitting device” according to the present invention is a display device driven by an active matrix driving method with a built-in driving circuit, and each pixel unit 70 included in the organic EL device 10. Is configured to include sub-pixel portions 71R, 71G, and 71B.

  The image display area 110 of the organic EL device 10 is provided with data lines 114 and scanning lines 112 wired vertically and horizontally, and the sub-pixel portions 71R, 71G and 71B corresponding to the intersections thereof are arranged in a matrix. One pixel unit 70 is configured by combining these three sub-pixel units. The image display area 110 is an example of the “display area” according to the present invention. As will be described later, each of the sub-pixel portions 71R, 71G, and 71B emits light having wavelengths of red (R), green (G), and blue (B). Accordingly, the organic EL device 10 can display an image in full color under the control of the pixel unit 70 by the scanning line driving circuit 130 and the data line driving circuit 150.

  Further, the image display area 110 is provided with power supply lines 117 corresponding to the sub-pixel portions 71R, 71G and 71B arranged for the respective data lines 114.

  A scanning line driving circuit 130, a data line driving circuit 150, a driving waveform control circuit 170, and a current detection circuit 190 are provided in the peripheral area located around the image display area 110. The scanning line driving circuit 130 sequentially supplies scanning signals to the plurality of scanning lines 112. As will be described later, the current detection circuit 190 is configured to be able to detect the current value of the temperature sensor organic EL element 79 provided in the pixel unit 70, and outputs the detected current value to the drive waveform control circuit 170. . As will be described later, the drive waveform control circuit 170 calculates the temperature of the temperature sensor organic EL element 79 based on the current value detected by the current detection circuit 190, and based on the calculated temperature, correction data described later. Is output to the data line driving circuit 150. The data line drive circuit 150 generates a drive waveform for driving the pixel unit 70 from the correction data and the display data from the drive waveform control circuit 170, and the generated drive waveform is data wired to the image display area 110. Supply to line 114. Note that the operation of the scanning line driving circuit 130 and the operation of the data line driving circuit 150 are synchronized with each other via the synchronization signal line 160.

  The power supply line 117 is supplied with pixel driving power from an external circuit. Focusing on one pixel portion 70 in FIG. 1, the pixel portion 70 is provided with organic EL elements 72R, 72G, and 72B, and a switching transistor 76 and a driving transistor 74 configured using, for example, TFTs. In addition, a storage capacitor 78 is provided for each sub-pixel portion. The scanning line 112 is electrically connected to the gate electrode of the switching transistor 76, the data line 114 is electrically connected to the source electrode of the switching transistor 76, and the drive is connected to the drain electrode of the switching transistor 76. The gate electrode of the transistor 74 is electrically connected. The power supply line 117 is electrically connected to the drain electrode of the driving transistor 74, and the anode of the organic EL element 72 is electrically connected to the source electrode of the driving transistor 74.

  In addition to the configuration of the pixel circuit illustrated in FIG. 1, various types of pixel circuits such as a current programming type pixel circuit, a voltage programming type pixel circuit, a voltage comparison type pixel circuit, a subframe type pixel circuit, and the like. Can be adopted.

  Next, a specific configuration of the organic EL device according to this embodiment will be described with reference to FIGS. FIG. 2 is a plan view showing a schematic configuration of the organic EL device, and FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG.

  2 and 3, the organic EL device 10 includes a plurality of pixel units 70 formed in an image display region 110 on the substrate 1.

  The pixel units 70 are arranged in a matrix in the image display area 110 on the substrate 1. The pixel unit 70 is configured as a set of three sub-pixel units 71R, 71G, and 71B arranged along the horizontal direction in the drawing, and extends along the vertical and horizontal directions of the image display region 110 in the drawing. Are arranged. An organic EL element 72 is formed in a concave portion 62 surrounded by the partition wall portion 47 in each sub-pixel portion 71.

  In FIG. 3, the organic EL device 10 includes a substrate 1, an organic EL element 72 (that is, organic EL elements 72 </ b> R, 72 </ b> G, and 72 </ b> B), a driving transistor 74, a bank unit 47, and a sealing plate 20.

  The substrate 1 is composed of, for example, a glass substrate. The substrate 1 includes not only the organic EL element 72 formed on the substrate 1 but also various circuits such as the scanning line driving circuit 130, the data line driving circuit 150, and the driving waveform control circuit 170 shown in FIG. . Such a circuit is provided in the peripheral area of the image display area 110 on the substrate 1.

  The organic EL element 72 includes an organic EL layer 50, a cathode 49, and an anode 34.

  The organic EL layer 50 is formed by applying an organic material to the recess 62 surrounded by the bank portion 47 functioning as an element isolation portion for separating the plurality of organic EL layers 50 from each other using an inkjet method. . More specifically, the organic EL layer 50 is applied to the recess 62 defined for each sub-pixel unit 71 by applying an organic EL material that emits red light, an organic EL material that emits green light, and an organic EL material that emits blue light. It is formed by dividing. That is, the organic EL element 72R includes an organic EL layer 50 made of an organic EL material that emits red light, and the organic EL element 72G includes an organic EL layer 50 made of an organic EL material that emits green light. Includes an organic EL layer 50 made of an organic EL material that emits blue light.

  The bank unit 47 includes a first bank unit 47a and a second bank unit 47b, and defines a recess 62 in which the organic EL layer 50 is formed. The first bank portion 47a is an inorganic material layer composed of an inorganic material such as SiO, SiO2, or TiO2. For example, a CVD (Chemical Vapor Deposition) method, a coating method, a sputtering method, or the like is formed on the protective layer 45. The film forming method is used. The 2nd bank part 47b is an organic material layer comprised by organic materials, such as an acrylic resin or a polyimide resin, and has a taper shape which tapers toward the upper side in the figure. The second bank part 47b is formed by forming an organic material layer on the first bank part 47a and then patterning the organic material layer using a photolithography technique or the like. The second bank portion 47b is formed so that the bottom thereof is smaller than the first bank portion 47a along the horizontal direction in the figure.

  The anode 34 is formed so as to be embedded in the first bank portion 47a among the gate insulating layer 2, the interlayer insulating film 41, the protective layer 45, and the first bank portion 47a sequentially formed on the substrate 1. The anode 34 is, for example, a transparent electrode made of a transparent material such as ITO (Indium Tin Oxide) so as to transmit light emitted downward from the organic EL layer 50 downward in the drawing. Therefore, the organic EL device 10 is a so-called bottom emission type organic EL device. The driving method of the light emitting device of the present invention can also be applied to a so-called top emission type organic EL device that emits light toward the sealing plate 20 side.

  The cathode 49 is formed in common to the sub-pixel portions 71R, 71G, and 71B so as to face the anode through the organic EL layer 50. More specifically, the cathode 49 is formed so as to cover the surface of the second bank unit 47b that separates the sub-pixel units 70 from each other and the surface of each organic EL layer 50, and different sub-pixel units 71R, 71G, and 71B. Are common electrodes common to the organic EL elements 72R, 72G and 72B. The cathode 49 is made of a metal thin film such as Al so as to reflect light emitted upward from the organic EL layer 50 in the drawing.

  The source electrode 74s of the driving transistor 74 is electrically connected to the power supply line 117 shown in FIG. 1, and the drain electrode 74d is electrically connected to the anode 34. The driving transistor 74 is turned on / off in response to a data signal supplied to the gate electrode 3a via the data line 114 shown in FIG. The circuit including such an element is provided so as to avoid the lower side of the organic EL layer 50 so as not to block light emitted from the organic EL layer 50 to the substrate 1 side. Similarly to the driving transistor 74, the switching transistor 76 shown in FIG. 1 is also formed on the substrate 1.

  The semiconductor layer 3 is a polycrystalline silicon layer or an amorphous silicon layer formed by using, for example, a low-temperature polysilicon technique. On the semiconductor layer 3, the gate insulating layer 2 of the switching transistor 76 and the driving transistor 74 is formed by embedding the semiconductor layer 3. The gate electrode 3 a of the driving transistor 74 and the scanning line 112 shown in FIG. 1 are formed on the gate insulating layer 2. A part of the scanning line 112 is formed as a gate electrode of the switching transistor 76. The gate electrode 3a and the scanning line 112 may include at least one of Al (aluminum), W (tungsten), Ta (tantalum), Mo (molybdenum), Ti (titanium), copper (Cu), chromium (Cr), and the like. It is formed using the metal material which contains.

  An interlayer insulating layer 41 is formed on the gate insulating layer 2 so as to embed the scanning line 112 and the gate electrode 3 a of the driving transistor 74. The interlayer insulating layer 41 and the gate insulating layer 2 are made of, for example, a silicon oxide film. On the interlayer insulating layer 41, for example, a data line 114 and a power supply line 117, and a source electrode 74 s of the driving transistor 74, each formed of a conductive material including aluminum (Al) or ITO, are formed. Contact holes 501 and 502 are formed in the interlayer insulating layer 41 from the surface of the interlayer insulating layer 41 through the interlayer insulating layer 41 and the gate insulating layer 2 to reach the semiconductor layer 3 of the driving transistor 74. The conductive film constituting the power supply line 117 and the drain electrode 74d is continuously formed so as to reach the surface of the semiconductor layer 3 along the inner walls of the contact holes 501 and 502, respectively. On the interlayer insulating layer 41, for example, a silicon nitride film (SiNx) or a silicon oxide film (SiOx) is formed as the protective layer 45 by embedding the power supply line 117 and the drain electrode 74d. On the protective layer 45, a first bank portion 47a made of, for example, a silicon oxide film is formed, and a second bank portion 47b is formed on the first bank portion 47a. The formation area of the organic EL layer 50 in the pixel portion is defined by the first bank portion 47a and the second bank portion 47b.

  The sealing plate 20 is made of glass, plastic or the like, and prevents moisture from entering the organic EL layer 50 from the outside of the organic EL device 10. More specifically, the sealing plate 20 is bonded to the substrate 1 with an adhesive, and seals the organic EL element 72 so as not to be exposed to the atmosphere. The sealing plate 20 is bonded and sealed to the substrate 1 via an adhesive applied to the peripheral portion of the sealing plate 20 using an application means such as a dispenser, for example. Thereby, for example, the deterioration of the organic EL element 72 due to moisture contained in the atmosphere can be reduced, and the life of the organic EL device 10 can be extended.

  Next, a method for driving the organic EL device according to the present embodiment will be described with reference to FIGS. FIG. 4 is a block diagram showing a method for driving the organic EL device according to this embodiment. FIG. 5 is a graph showing temperature characteristics of the organic EL material. FIG. 6 is a plan view showing the position in the image display area of the organic EL element for temperature sensor according to this embodiment.

  In FIG. 4, during the operation of the organic EL device 10, the current value detection circuit 190 detects the current value flowing through the temperature sensor organic EL element 79, for example, at predetermined time intervals. The current value detection circuit 190 outputs the detected current value to the drive waveform control circuit 170.

  The temperature sensor organic EL element 79 is selected in advance to function as a temperature sensor among the organic EL elements 72 provided in each of the plurality of pixel units 70. In the present embodiment, as will be described later, the organic EL elements 72 of the plurality of pixel portions 70 in the image display region 110 are selected in advance as the temperature sensor organic EL elements 79. The temperature sensor organic EL element 79 is electrically connected to the current value detection circuit 190.

  The current value detection circuit 190 detects a current value that flows when the temperature sensor organic EL element 79 emits light (that is, when a display voltage is applied). As a modification of the present embodiment, a predetermined voltage that is weak enough not to affect the display is applied to the temperature sensor organic EL element 79 during a non-display period in which the temperature sensor organic EL element 79 does not contribute to display. Then, the current value may be detected. In this case, since a predetermined voltage can be applied to the temperature sensor organic EL element 79 for a certain period of time, a stable current can flow through the temperature sensor organic EL element 79, and the current value can be detected with high accuracy. .

  The drive waveform control circuit 170 calculates the temperature of the temperature sensor organic EL element 79 based on the current value from the current value detection circuit 190, and is driven so as to obtain a desired light emission luminance based on the calculated temperature. Correction data related to the waveform is generated and output to the data line driving circuit 150.

  As shown in FIG. 5, the organic EL material used for the organic EL layer 50 of the organic EL element 72 has a temperature characteristic that the resistance decreases as the temperature rises and the resistance increases as the temperature decreases. That is, the graphs C1, C2, C3, and C4 in FIG. 5 show the voltage applied to the organic EL material at a constant temperature of 80 ° C., 50 ° C., 25 ° C., and −30 ° C. and the current density at that time, respectively. Showing the relationship. For example, when the same voltage is applied, the current density decreases as the temperature decreases, that is, the current density decreases in the order of graphs C1, C2, C3, and C4. Conversely, in order to generate the same current density in the organic EL material, it is necessary to apply a larger voltage as the temperature is lower. That is, a larger voltage is applied in the order of graphs C1, C2, C3, and C4. There is a need. For example, as shown by the difference W1 in FIG. 5, in order to generate a predetermined current density, a voltage of about 3.5 V is required at 80 ° C. (see graph C1), whereas at −30 ° C. (graph C4). Reference) A voltage of about 6V is required. That is, for a temperature difference of about 110 ° C., the required voltage difference is about 2.5V. That is, the amount of change per unit temperature of the voltage necessary for applying the predetermined current is 23 mV / ° C. Since the organic EL material has such a relatively large temperature characteristic (that is, a temperature characteristic of 5 mV / ° C. or more), an organic EL element including an organic EL layer made of such an organic EL material is used as a temperature sensor. Can function as. That is, the temperature of the temperature sensor organic EL element 79 can be calculated from the voltage applied to the temperature sensor organic EL element 79 and the current value of the temperature sensor organic EL element 79 detected by the current value detection circuit 190.

  As described above, the drive waveform control circuit 170 generates correction data related to the drive waveform so as to obtain a desired light emission luminance based on the temperature thus calculated. Here, the “correction data” is, for example, the width and height of the drive waveform so that the difference between the drive waveform determined corresponding to the preset temperature and the drive waveform determined corresponding to the calculated temperature is reduced. , Data for changing parameters such as shape or inrush current shape. That is, for example, an applied current necessary for causing the organic EL layer 50 to emit light with a desired light emission luminance at a preset temperature and a necessity for causing the organic EL layer 50 to emit light with a desired light emission luminance at a detected temperature. This is data for reducing (i.e., correcting) a difference from the applied current.

  The data line driving circuit 150 generates a driving waveform for driving the pixel unit 70 from the correction data and the display data from the driving waveform control circuit 170, and the generated driving waveform is transmitted to the pixel unit 70 via the data line 114. Supply. Therefore, an applied current having a drive waveform corresponding to the detected temperature is applied to the organic EL element 72 including the temperature sensor organic EL element 79. In other words, the current value of the temperature sensor organic EL element 79 is fed back to the drive waveform control circuit 170, so that the applied current of the drive waveform adjusted in accordance with the temperature of the organic EL element 72 is changed to the organic EL element 72. To be applied. Therefore, for example, even when the temperature of the organic EL element 72 is changed due to heat generated when the organic EL element 72 emits light during operation or due to heat generation from the TFTs 74 and 76, the luminance of the pixel unit 70 is desired. Can be controlled so as to have a brightness of.

  Furthermore, in the present embodiment, the temperature is calculated based on the current value of the temperature sensor organic EL element 79 selected from among the organic EL elements 72 provided in the pixel unit 70, so that the image display area 110 and Compared to the case where the temperature is detected by, for example, a temperature sensor circuit provided in a different region, the temperature of the organic EL element 72 can be detected near the pixel unit 70. Therefore, the temperature can be detected with higher accuracy.

  In this embodiment, the current value detection circuit 190 is provided separately from the drive waveform control circuit 170 in order to detect the current value of the organic EL element 79 for temperature sensor. You may make it detect the electric current value of the organic EL element 79 for temperature sensors. In the present embodiment, the current value detection circuit 190 detects the current value of the temperature sensor organic EL element 79, and the temperature is calculated based on the current value detected by the drive waveform control circuit 170. A temperature detection circuit that detects the current value of the temperature sensor organic EL element 79 and calculates the temperature based on the detected current value may be provided.

  In addition, in this embodiment, in particular, the temperature of the organic EL element 72 is detected by using the temperature characteristics of the organic EL element 72 formed in the pixel unit 70. For example, the organic EL element formed in the pixel unit 70 Compared to forming a temperature sensor circuit for detecting temperature separately from 72, little or no complication of the manufacturing process is required.

  As shown in FIG. 6, in the present embodiment, in particular, the organic EL element 72 included in the pixel portion 70 a disposed in the center of the image display region 110 and the four pixel portions 70 b in the peripheral portion of the image display region 110 are respectively provided. The included organic EL element 72 is selected as the temperature sensor organic EL element 79. That is, the current values of the plurality of temperature sensor organic EL elements 79 in the image display area 110 are detected by the current detection circuit 190, and the drive waveform control circuit 170 calculates the temperatures of the plurality of temperature sensor organic EL elements 79, respectively. Is done. Therefore, the temperature distribution of the plurality of pixel units 70 in the image display area 110 can be calculated. Therefore, the drive waveform applied to the plurality of pixel units 70 is corrected by the drive waveform control circuit 170 described above according to the temperature distribution of the plurality of pixel units 70, thereby causing the temperature distribution of the plurality of pixel units 70. Luminance variations in the image display area 110 can be reduced or prevented. In particular, when the image display area 110 is wide (that is, the size of the substrate 1 and the sealing plate 20 or the light-emitting panel is large), the temperature distribution of the plurality of pixel portions 70 is likely to occur, and luminance variations occur in the image display area 110. Therefore, it is extremely effective to correct the drive waveform in accordance with the temperature distribution of the plurality of pixel units 70 calculated based on the current value of the organic EL element for temperature sensor.

  Furthermore, as shown in FIG. 6, in this embodiment, the organic EL elements 72R, 72G, and 72B included in the sub-pixel portions that constitute each of the pixel portions 70a and 70b are temperature sensor organic EL elements 79R, 79G. And 79B. That is, the respective temperatures are detected based on the current values of the temperature sensor organic EL elements 79R, 79G, and 79B of different organic EL materials. Then, the drive waveform circuit 170 generates correction data relating to the drive waveform for each of the organic EL elements 72R, 72G, and 72B, and the data line drive circuit 150 applies the applied current of the drive waveform corrected for each RGB to the organic EL element. Applied to 72R, 72G and 72B, respectively. Therefore, it is possible to reduce or prevent color misregistration that may occur in an RGB independent light emitting panel, which is caused by the difference in the light emitting pixel temperature between the center and the end of the panel. In other words, the color shift due to the temperature difference can be further reduced or eliminated by accurately detecting the temperature for each RGB pixel and feeding back to the calculation of the applied current for each RBG pixel.

  In the present embodiment, the organic EL elements 72R, 72G, and 72B included in each of the sub-pixel parts constituting the pixel part 70 are selected as a set as the organic EL element for the temperature sensor, but for example, the organic EL element 72R For example, one organic EL element 72 may be selected, or two organic EL elements 72 such as organic EL elements 72R and 72B may be selected.

  As described above, according to the driving method of the organic EL device of the present embodiment, the temperature of the organic EL element 79 for temperature sensor among the organic EL elements 72 included in each of the plurality of pixel units 70 is detected and detected. Since the applied current corrected according to the temperature is applied to the organic EL element 72, high-quality image display is possible. In particular, the temperature characteristic of the temperature sensor organic EL element 79 is detected using the temperature characteristic of the temperature sensor organic EL element 79, so that the temperature in the image display region 110 can be detected and the manufacturing process is complicated. Little or no conversion is required.

  The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. The method is also included in the technical scope of the present invention.

1 is a block diagram illustrating an overall configuration of an organic EL device according to a first embodiment. 1 is a plan view illustrating a schematic configuration of an organic EL device according to a first embodiment. FIG. 3 is a cross-sectional view taken along line AA ′ in FIG. 2. It is a block diagram which shows the drive method of the organic electroluminescent apparatus which concerns on 1st Embodiment. It is a graph which shows the temperature characteristic of organic electroluminescent material. It is a top view which shows the position in the image display area | region of the organic EL element for temperature sensors which concerns on 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 10 ... Organic EL apparatus, 20 ... Sealing plate, 47 ... Bank part, 72 ... Organic EL element, 74, 76 ... TFT, 79 ... Organic EL element for temperature sensors, 110 ... Image display area, 130 ... Scanning line drive circuit, 150 ... Data line drive circuit, 170 ... Drive waveform control circuit, 190 ... Current value detection circuit

Claims (5)

A driving method of a light emitting device for driving a light emitting device provided with a plurality of pixel portions each including a light emitting element in a display region,
A temperature detecting step of detecting a temperature of the light emitting element by detecting a current value of the light emitting element included in at least one of the plurality of pixel parts;
An applied current calculating step of calculating an applied current to be applied to the light emitting element in order for the light emitting element to emit light with a predetermined luminance in accordance with the temperature detected by the temperature detecting step;
And a current applying step of applying the applied current to the light emitting element. The light-emitting elements are three types of light-emitting elements each including a light-emitting layer that emits one of the colors R (red), G (green), and B (blue).
The temperature detection step detects the temperature of each of the three types of light emitting elements,
The method of driving a light emitting device according to claim 1, wherein the applied current calculation step calculates the applied current of each of the three types of light emitting elements.   The method for driving a light emitting device according to claim 1, wherein the light emitting element includes a light emitting material having a temperature characteristic of 5 mV / ° C. or more.   4. The temperature detection process according to claim 1, wherein the current value is detected by applying a predetermined voltage to the light emitting element included in the at least one pixel unit. 5. Driving method of light emitting device.   5. The method for driving a light emitting device according to claim 1, wherein the temperature detecting step detects temperatures of the light emitting elements included in a plurality of pixel portions in the display region. .

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