JP2013222057A - Manufacturing method for display device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a display device, in which a correction error in a characteristic dispersion of a drive transistor is reduced over an entire gradation so as to suppress luminance unevenness.SOLUTION: A manufacturing method for a display device, includes: obtaining a first reference voltage on a representative voltage to luminance characteristic common to a display panel, which attains a measured luminance by applying a first signal voltage in a medium gradation area to a target pixel; obtaining a first correction parameter which causes a first signal voltage to be a first reference voltage; obtaining a second correction parameter which causes a luminance measured by applying a second signal voltage of a low gradation area to a target pixel to be a luminance corresponding to a first correction voltage on a representative voltage-luminance characteristic in which a first correction parameter is applied to a second signal voltage; and obtaining a third correction parameter which causes a light emission luminance measured by applying a third signal voltage of a high gradation area to a target pixel to be a luminance corresponding to a second correction voltage on a representative voltage-luminance characteristic in which a first correction parameter is applied to a third signal voltage.

Description

  The present invention relates to a display device manufacturing method and an organic EL display device, and more particularly, to an active matrix organic EL display device manufacturing method and an organic EL display device.

  As an image display device using a current-driven light-emitting element whose emission intensity is controlled according to the amount of current, an image display device (organic EL display device) using an organic EL element (OLED: Organic Light Emitting Diode) is known. It has been. This organic EL display device has attracted attention as a high-quality and high-performance display device characterized by thin and light weight, high-speed response, wide viewing angle, and low power consumption.

  In an organic EL display device, organic EL elements constituting pixels are usually arranged in a matrix. An organic EL element is provided at the intersection of a plurality of scanning lines and a plurality of signal lines, and the organic EL element is driven by applying a signal voltage corresponding to the video signal between the selected scanning lines and the plurality of signal lines. This is called a passive matrix organic EL display device.

  On the other hand, a thin film transistor for selection (TFT) is provided at the intersection of a plurality of scanning lines and a plurality of signal lines, a gate of a driving transistor is connected to the TFT, and the TFT is turned on through the selected scanning line. A signal voltage is input to the driving transistor from the signal line. A device in which an organic EL element is driven by this driving transistor is called an active matrix type organic EL display device.

  Unlike the passive matrix organic EL display in which the organic EL element connected to the active matrix organic EL display device emits light only during a period when each scanning line is selected, the organic matrix display is organic until the next scanning (selection). Since the EL element can emit light, the luminance of the display is not reduced even when the duty ratio is increased. Therefore, the active matrix organic EL display device can be driven at a low voltage and can reduce power consumption. However, in an active matrix organic EL display device, due to variations in characteristics of drive transistors, even if the same signal voltage is applied to each pixel, the luminance of the organic EL element differs in each pixel. There is a disadvantage that unevenness occurs. This is because the luminance of the current-driven organic EL element is determined by the drain (source) current of the drive transistor, and the drive transistor has variations in mobility and threshold voltage between pixels.

  Therefore, conventionally, a gain / offset method is known as a method for correcting the characteristic variation of the drive transistor. For example, in Patent Document 1, the signal voltage-luminance characteristics of each linearly converted pixel are corrected by two parameters, gain and offset, in order to eliminate non-uniformity of the light emission characteristics of a display composed of organic light emitting diodes. Techniques to do this are disclosed.

  Further, in Patent Document 2, in order to eliminate the luminance unevenness of the EL display panel due to the characteristic variation of the current control TFT, a correction that is a difference between the luminance average value acquired by lighting all the pixels and the luminance value of each pixel is corrected. A technique is disclosed in which a value is added to display data and input to an EL display panel.

  In Patent Document 3, in a light-emitting device in which a plurality of pixel portions each having a light-emitting element and a driving transistor are arranged, pixel current measurement is performed in order to eliminate variation in luminance of the light-emitting element due to characteristic variation of the driving transistor. A technique for correcting a video signal input to a pixel unit using two parameters of gain and offset based on a light emission current measured by a circuit for use is disclosed.

  By the correction technique described above, luminance unevenness can be reduced and uniform display can be achieved.

Special table 2008-535028 gazette Japanese Patent Laid-Open No. 11-282420 JP 2010-160497 A

  In the above-described display device including pixels having current-driven light-emitting elements, the signal voltage-luminance characteristics of the drive transistor and the light-emitting elements included in each pixel are non-linear characteristics, and the curve shape representing the non-linear characteristics is a pixel shape. It is necessary to assume different cases.

  However, the correction technique disclosed in Patent Document 2 only adds or subtracts an offset correction value, which is the difference between the luminance average value at a predetermined gradation and the luminance value of each pixel, to the display data, and provides a single offset. The correction value alone cannot sufficiently correct the non-linear characteristic variation of each pixel over all gradations.

  Further, in the correction technique disclosed in Patent Document 1, since the nonlinear characteristics of each pixel are corrected by approximating the linear characteristics, correction errors cannot be ignored with only two parameters such as gain and offset. High precision uniformity cannot be obtained.

  Further, in the correction technique disclosed in Patent Document 3, as described above, the correction error cannot be ignored only with the two parameters of gain and offset, and high-precision uniformity cannot be obtained in the display image.

  Further, the low drive voltage range below the threshold voltage of the drive transistor is a weak inversion region of the drive transistor. Here, the weak inversion region in the driving transistor corresponds to a low gradation region in which the theoretical formula of the nonlinear characteristics of the strong inversion region in the middle gradation region and the high gradation region is not satisfied. Therefore, in the low gradation range, the signal voltage-luminance characteristics exhibit nonlinear characteristics different from those in the middle gradation range and the high gradation range. Thereby, for example, when the correction gain and the correction offset are determined based on the theoretical formulas in the middle gradation region and the high gradation region, the characteristic variation between the pixels in the low gradation region becomes large. That is, the above-described gain / offset method including two or less parameters has a problem that a correction error at a low gradation or a high gradation becomes large.

  The present invention has been made in view of the above-described problems, and provides a display device manufacturing method and a display device that reduce luminance correction correction errors over all gradations and suppress luminance unevenness. Objective.

  In order to solve the above problems, a method for manufacturing a display device according to one embodiment of the present invention includes a plurality of pixels including a light-emitting element and a driving element that controls supply of a current reflecting the luminance of the light-emitting element with an input voltage. A first step of obtaining a function representing a representative voltage-luminance characteristic common to a display panel including the first signal voltage corresponding to one gradation belonging to an intermediate gradation region of the representative voltage-luminance characteristic; And a luminance obtained from the representative voltage-luminance characteristics is a pixel to be corrected, in a second step of measuring the luminance emitted from the plurality of pixels by a measuring device and applying the luminance to the driving elements included in each of the pixels. A first reference voltage is obtained when the target pixel emits light with the first signal voltage, and a first correction parameter for setting the first signal voltage to the first reference voltage is determined as the target pixel. Last A third step of obtaining and driving the second pixel voltage corresponding to one gradation belonging to a low gradation area whose gradation is lower than the middle gradation area of the representative voltage-luminance characteristics included in the target pixel; A fourth step of measuring the luminance emitted from the target pixel by the measuring device by applying to the element, and the luminance when the target pixel is caused to emit light at the second signal voltage is the second signal voltage A fifth step of obtaining, for the target pixel, a second correction parameter that is a coefficient that provides a first reference luminance obtained when the first correction voltage to which the first correction parameter is added is input to the function; Applying a third signal voltage corresponding to one gradation belonging to a high gradation area having a gradation higher than the intermediate gradation area of the representative voltage-luminance characteristics to a driving element included in the target pixel; Luminance emitted from the pixel The sixth step of measuring by the measuring device, and the luminance when the target pixel is caused to emit light at the third signal voltage are the second correction voltage obtained by adding the first correction parameter to the third signal voltage. And a seventh step of obtaining a third correction parameter for the target pixel, which is a coefficient that provides a second reference luminance obtained when input to the function.

  According to the manufacturing method of the display device according to the present invention, the characteristic variation of the driving transistor is corrected with high accuracy by at least three correction parameters including the offset, the low gradation area gain, and the high gradation area gain. Accordingly, it is possible to manufacture a display device in which luminance unevenness is reduced.

It is a block diagram which shows the structure of the organic electroluminescence display which concerns on Embodiment 1 of this invention, and an organic electroluminescence display manufacturing apparatus. 3 is a diagram illustrating a circuit configuration of a pixel included in a display unit of the display panel according to Embodiment 1 and a connection with peripheral circuits thereof. FIG. FIG. 3 is a block diagram illustrating a functional configuration of a control circuit and a correction parameter determination device according to the first embodiment. 6 is a diagram illustrating an example of a correction parameter table according to Embodiment 1. FIG. 4 is a graph showing voltage-luminance characteristics for explaining a correction principle of the organic EL display device according to the first embodiment. It is a graph showing the voltage-luminance characteristic according to human visibility. It is a figure showing the voltage-luminance characteristic explaining the system which correct | amends an offset in a middle gradation area, and a gain in a low gradation area and a high gradation area. It is a figure showing the voltage-luminance characteristic explaining the system which correct | amends an offset in a low gradation area, and a gain in a middle gradation area and a high gradation area. It is a figure showing the voltage-luminance characteristic explaining the system which correct | amends an offset in a high gradation area | region, and a gain in a low gradation area | region and a middle gradation area | region. 5 is a flowchart illustrating an example of an operation in which a correction parameter determination device according to Embodiment 1 determines a correction parameter. 4 is a flowchart illustrating an example of processing in which a correction parameter calculation unit according to Embodiment 1 calculates a first correction parameter. FIG. 10 is a diagram for describing processing in which a correction parameter calculation unit according to Embodiment 1 calculates a second correction parameter. 10 is a flowchart illustrating an example of processing in which a correction parameter calculation unit according to Embodiment 1 calculates a third correction parameter. It is a block diagram showing the correction | amendment process of the organic electroluminescence display which concerns on Embodiment 1 of this invention. 6 is a graph showing voltage-luminance characteristics for explaining the correction principle of the organic EL display device according to the second embodiment. It is a block diagram showing the correction | amendment process of the organic electroluminescence display which concerns on Embodiment 2 of this invention. It is a graph for defining the threshold voltage of the drive transistor which the organic electroluminescence display of this invention has. 1 is an external view of a thin flat TV incorporating an organic EL display device manufactured by a method for manufacturing an organic EL display device according to the present invention.

In order to solve the above problems, a method for manufacturing a display device according to one embodiment of the present invention includes a plurality of pixels including a light-emitting element and a driving element that controls supply of a current reflecting the luminance of the light-emitting element with an input voltage. A first step of obtaining a function representing a representative voltage-luminance characteristic common to the display panel including the first signal voltage (V1) corresponding to one gradation belonging to the middle gradation region of the representative voltage-luminance characteristic; A second step of measuring the luminance emitted from the plurality of pixels by a measuring device, applied to the driving elements included in each of the plurality of pixels, and the luminance obtained from the representative voltage-luminance characteristics A first reference voltage (Vr1) is obtained when the target pixel, which is a pixel, emits light with the first signal voltage (V1) and has a luminance (LM1), and the first signal voltage (V1) is determined as the first signal voltage (V1). Reference voltage (Vr1 A third step for obtaining a first correction parameter (OFS) for the target pixel, and a first floor belonging to a low gradation region having a gradation lower than the middle gradation region of the representative voltage-luminance characteristics A fourth step of applying a second signal voltage (V2) corresponding to a tone to a driving element included in the target pixel and measuring a luminance (LL1) emitted from the target pixel by the measuring device; and the target When the luminance (LL1) when the pixel is caused to emit light at the second signal voltage is input to the function, the first correction voltage (Vc1) obtained by adding the first correction parameter to the second signal voltage is input to the function. A fifth step of obtaining a second correction parameter (G _L ), which is a coefficient so as to obtain the first reference luminance (LLB), for the target pixel, and the representative voltage-luminance characteristics from the middle gradation range Also has high gradation A third signal voltage (V3) corresponding to one gradation belonging to a high gradation region is applied to the drive element included in the target pixel, and the luminance (LH1) emitted from the target pixel is measured by the measurement device. And a second correction voltage (Vc2) obtained by adding the first correction parameter to the third signal voltage when the target pixel emits light with the third signal voltage (LH1). Including a seventh correction parameter ( _GH ), which is a coefficient that becomes a second reference luminance (LHB) obtained when the function is input to the function, for the target pixel. And

  According to this aspect, the pixel signal voltage in all gradations is corrected by offset based on the voltage-luminance characteristics in the middle gradation range, and the pixel signal voltage (VinH) in the high gradation range is gained for the high gradation range (Gain 2). Thus, the pixel signal voltage (VinL) in the low gradation region can be corrected with the gain (Gain1) for the low gradation region. Therefore, it is possible to reduce the correction error in the low gradation region, which is particularly difficult to correct, and as a result, it is possible to correct the pixel signal voltage with high accuracy over all gradations. Therefore, the display device manufactured by the method for manufacturing the display device can display an image with reduced luminance unevenness with high accuracy over all gradations.

The first correction parameter (OFS) is an offset voltage indicating a difference between the first signal voltage (V1) and the first reference voltage (Vr1). In the fifth step, the target pixel The second reference voltage (VinL) obtained when the luminance (LL1) when light is emitted with the second signal voltage (V2) is input to the function is obtained by calculation, and the second correction parameter (G _L ) represents the ratio between the voltage difference (Vc1−Vr1) between the first correction voltage and the first reference voltage and the voltage difference (VinL−Vr1) between the second reference voltage and the first reference voltage. Gain, and in the seventh step, a third reference voltage (VinH) obtained when luminance (LH1) when the target pixel is caused to emit light at the third signal voltage (V3) is input to the function. Obtained by calculation, Correction parameters _{(G H),} the voltage difference between the second correction voltage and said first reference voltage and (Vc2-Vr1), the voltage difference between the third reference voltage and the first reference voltage and (VinH-Vr1) It may be a gain indicating the ratio of.

  According to this aspect, the first to third correction parameters are calculated by the voltage difference (V1-Vr1) and the voltage ratio (VD1 / VDL, VD2 / VDH) based on the measured luminance value of the target pixel and the representative voltage-luminance. It becomes possible to do. Therefore, in calculating each correction parameter, it is only necessary to measure the luminance of the target pixel only once, and the calculation can be performed thereafter, so that the manufacturing process of the apparatus can be shortened.

  The first signal voltage (V1) is preferably a gate-source voltage of the driving element at a boundary between a weak inversion region and a strong inversion region where the driving element operates.

  According to this aspect, it is possible to perform correction corresponding to a change in the curve shape of the voltage-luminance characteristic that is different between the strong inversion region and the weak inversion region of the driving transistor.

  Further, the threshold voltage (Vth) of the driving element is preferably a gate-source voltage of the driving element corresponding to a gray level belonging to the middle gray level region.

  In the drive transistor, there is a boundary between the strong inversion region and the weak inversion region when the gate-source voltage is in the vicinity of the threshold voltage. According to this aspect, the offset voltage (OFS) that is the first correction parameter is calculated in the vicinity of the threshold voltage (Vth), so that the curve shape of the voltage-luminance characteristic that is different between the strong inversion region and the weak inversion region. The correction corresponding to the change of can be made.

  The second signal voltage (V2) is preferably a voltage corresponding to a gray scale of 0% to 10% of the maximum gray scale that can be displayed in each pixel.

  According to this aspect, as the second signal voltage (V2) corresponding to one gradation belonging to the low gradation area, the voltage corresponding to one gradation belonging to the gradation area of 0% to 10% of the maximum gradation is obtained. Apply. As a result, the second correction parameter can be calculated in a low gradation range suitable for human visibility.

  The third signal voltage (V3) is preferably a voltage corresponding to a gradation of 20% to 100% of the maximum gradation that can be displayed in each pixel.

  According to this aspect, as the third signal voltage (V3) corresponding to one gradation belonging to the high gradation range, a voltage corresponding to one gradation belonging to the gradation range of 20% to 100% of the maximum gradation is applied. To do. As a result, the third correction parameter can be calculated in a high gradation range suitable for human visibility.

  The representative voltage-luminance characteristic may be a voltage-luminance characteristic for any one of a plurality of pixels included in the display panel.

  According to this aspect, the representative voltage-luminance characteristics may be the voltage-luminance characteristics for any one of a plurality of pixels included in the display panel. Thereby, it is possible to easily obtain a function representing the representative voltage-luminance characteristics.

  The representative voltage-luminance characteristic is a characteristic that is commonly set for the entire display panel including the plurality of pixels, and is an averaged voltage-luminance characteristic of each pixel included in the display panel. There may be.

  According to this aspect, the representative voltage-luminance characteristics are set in common for the entire display panel including a plurality of pixels, and are obtained by averaging the voltage-luminance characteristics of each pixel included in the display panel. Accordingly, the first to third correction parameters are obtained so that the luminance of each pixel included in the display panel has a representative voltage-luminance characteristic common to the entire display panel. Therefore, the video signal is obtained using these correction parameters. Is corrected, it is possible to reduce unevenness in luminance of light emitted from each pixel.

  The light emitting element included in the pixel emits one of red, green, and blue, and in the third step, the first correction parameter is obtained for each of the red, green, and blue colors, Preferably, in the fifth step, the second correction parameter is obtained for each of the red, green, and blue colors, and in the seventh step, the third correction parameter is obtained for each of the red, green, and blue colors.

  According to this aspect, the first to third correction parameters are obtained for each color of red, green, and blue. Thereby, brightness unevenness can be reduced for each of red, green, and blue colors.

  Further, the first correction parameter obtained in the third step, the second correction parameter obtained in the fifth step, and the third correction parameter obtained in the seventh step, It is preferable to include an eighth step of writing in a predetermined memory used for the display panel.

  According to this aspect, the obtained first to third correction parameters are written in a predetermined memory used for the display panel. By correcting the video signal input to each pixel using the first to third correction parameters stored in the predetermined memory, the correction accuracy of all gradations including the low gradation region can be improved. it can. As a result, luminance unevenness of the display panel recognized by human eyes can be reduced.

  The measuring device may be an image sensor.

  According to this aspect, when measuring the luminance by applying a predetermined voltage to the target pixel, the luminance when the predetermined voltage is applied to all the target pixels can be measured with high accuracy by one imaging. Therefore, it is possible to shorten the manufacturing process of this apparatus for obtaining the first to third correction parameters for all the pixels in order to eliminate the luminance unevenness of the display panel.

  The present invention can be realized not only as a method for manufacturing such a display device but also as a display device manufactured using the method for manufacturing the display device. Further, the present invention can also be realized as a display device manufacturing apparatus that realizes the display device manufacturing method, a program that executes processing performed by a processing unit included in the display device manufacturing apparatus, and a storage medium that stores the program. Furthermore, a correction parameter determination method included in the display device manufacturing method, a correction parameter determination device that realizes the correction parameter determination method, and a program that executes processing performed by a processing unit included in the correction parameter determination device It can also be realized as a storage medium for storing the program.

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

(Embodiment 1)
<Device configuration>
FIG. 1 is a block diagram showing a configuration of an organic EL display device and an organic EL display device manufacturing apparatus according to Embodiment 1 of the present invention. As shown in FIG. 1, the organic EL display device 1 is a display device that displays an image on a display unit 21, and includes a control circuit 10 and a display panel 20.

  The control circuit 10 controls a video signal to be displayed on the display panel 20 and displays a video on the display panel 20. Details of the control circuit 10 will be described later.

  The display panel 20 includes a display unit 21, a scanning line driving circuit 22, and a data line driving circuit 23, and is based on signals from the control circuit 10 input to the scanning line driving circuit 22 and the data line driving circuit 23. The video is displayed on the display unit 21. Here, the display unit 21 includes a plurality of pixels 100 arranged in a matrix. The detailed description of the display panel 20 will be described later.

  The organic EL display device manufacturing apparatus 2 is an apparatus that manufactures an organic EL display device in which luminance unevenness of the display panel 20 is reduced. The organic EL display device manufacturing apparatus 2 includes a correction parameter determination device 30 and a measurement device 40.

  The measuring device 40 is a measuring device that measures the luminance of light emitted from the plurality of pixels 100 included in the display unit 21. Specifically, the measurement device 40 is an image sensor such as a CCD (Charge Coupled Device) image sensor, and the brightness when a predetermined voltage is applied to all the pixels 100 included in the display unit 21 with high accuracy is obtained by one imaging. It is possible to measure with. Therefore, in order to eliminate the luminance unevenness of the display panel 20, it is possible to shorten the manufacturing process of this apparatus for acquiring correction parameters for all pixels. The measuring device 40 is not limited to an image sensor, and any measuring device may be used as long as it can measure the luminance of the pixel 100.

  The correction parameter determination device 30 is a device that determines a correction parameter for making the luminance of the plurality of pixels 100 included in the display unit 21 uniform based on the luminance of each pixel 100 measured by the measurement device 40. Further, the correction parameter determination device 30 outputs the determined correction parameter to the control circuit 10 of the organic EL display device 1. A detailed description of the correction parameter determination device 30 will be described later.

  Next, a detailed configuration of the display panel 20 will be described.

  FIG. 2 is a diagram illustrating a circuit configuration of a pixel included in the display unit of the display panel according to the first embodiment and a connection with peripheral circuits thereof.

  The pixel 100 is one pixel included in the display unit 21 and has a function of emitting light by a signal voltage supplied via a data line. As shown in the figure, the pixel 100 includes a light emitting element 110, a driving transistor 120, a selection transistor 130, a storage capacitor 140, a scanning line 24, a data line 25, and a power supply line 151.

  The peripheral circuit of the pixel 100 includes a power supply 150 and a power supply 160 in addition to the scanning line driving circuit 22 and the data line driving circuit 23.

  First, the internal circuit configuration of the pixel 100 will be described with reference to FIG.

  The light emitting element 110 is an organic EL (electroluminescence) element that emits one of red, green, and blue colors. Specifically, the light emitting element 110 has an anode connected to one of a source and a drain of the driving transistor 120 and a cathode connected to the power source 160. The light emitting element 110 has a function of emitting light when a current driven by the driving transistor 120 flows. That is, current is supplied to the light emitting element 110 through the power supply line 151, and the light emitting element 110 emits light.

  The drive transistor 120 is a voltage-driven drive element that controls supply of current to the light emitting element 110. Specifically, the driving transistor 120 has a gate connected to the data line 25 via the selection transistor 130, one of the source and the drain connected to the light emitting element 110, and the other of the source and the drain connected to the power source 150. Yes. The drive transistor 120 has a function of converting the signal voltage supplied from the data line 25 into a signal current corresponding to the magnitude thereof.

  In FIG. 2, an n-type transistor is illustrated as the drive transistor 120, but the drive transistor 120 is not limited to an n-type transistor, and may be a p-type transistor.

  The selection transistor 130 has a gate connected to the scanning line 24, one of the source and the drain connected to the data line 25, and the other of the source and the drain connected to the gate of the driving transistor 120. The selection transistor 130 switches between conduction and non-conduction between the data line 25 and the gate of the driving transistor 120. That is, the selection transistor 130 has a function of supplying the signal voltage from the data line 25 to the pixel 100 during a period in which the scanning line 24 is at a high level.

  The storage capacitor 140 is a capacitor that accumulates charges. The storage capacitor 140 is connected between one of the source and drain of the drive transistor 120 and the gate of the drive transistor 120. That is, a signal current corresponding to the charge accumulated in the storage capacitor 140 is caused to flow from the power supply line 151 to the light emitting element 110 by the driving transistor 120.

  The power supply 150 is a constant voltage source for the drive transistor 120 and is set to 10 V, for example. The power supply 160 is a constant voltage source of the light emitting element 110, and is grounded, for example. In the present embodiment, the potential of the power source 150 is set higher than the potential of the power source 160.

  The scanning line driving circuit 22 supplies a scanning signal to each scanning line 24 arranged for each pixel row. That is, the scanning line driving circuit 22 is connected to a plurality of scanning lines 24 for supplying a scanning signal to each of the plurality of pixels 100 and has a function of controlling conduction of the selection transistor 130 of the pixel 100.

  The data line driving circuit 23 supplies a signal voltage to each data line 25 arranged for each pixel column. That is, the data line driving circuit 23 is connected to a plurality of data lines 25 for supplying a signal voltage to each of the plurality of pixels 100 and has a function of determining a signal current flowing through the driving transistor 120.

  Next, detailed configurations of the control circuit 10 and the correction parameter determination device 30 will be described.

  FIG. 3 is a block diagram illustrating a functional configuration of the control circuit and the correction parameter determination device according to the first embodiment.

  As shown in the figure, the correction parameter determination device 30 is a device that determines a parameter for correcting the luminance, and includes a measurement control unit 31 and a correction parameter calculation unit 32.

  The measurement control unit 31 is a processing unit that measures the luminance of light emitted from the plurality of pixels 100 included in the display panel 20 using the measurement device 40.

  Specifically, the measurement control unit 31 first obtains a function representing a representative voltage-luminance characteristic common to the display panel 20. Here, the representative voltage-luminance characteristic is a voltage-luminance characteristic that is a reference for making the luminance uniform. The function representing the voltage-luminance characteristic is a function representing the relationship between the signal voltage supplied from the data line to the gate of the driving transistor 120 and the light emission luminance from the predetermined pixel 100. A function representing the representative voltage-luminance characteristic is determined in advance by measurement or the like.

  In addition, the measurement control unit 31 causes the control circuit 10 to emit light from the plurality of pixels 100 included in the display panel 20 and causes the measurement device 40 to measure the light emission luminance from the plurality of pixels 100, whereby the light emission luminance. To get.

  Specifically, the measurement control unit 31 applies a first signal voltage corresponding to one gradation belonging to the middle gradation range of the representative voltage-luminance characteristic to the driving transistor 120 included in each of the plurality of pixels 100. By measuring the light emission luminance from the plurality of pixels 100 using the measuring device 40, the light emission luminance for each pixel is acquired.

  Further, the measurement control unit 31 applies the second signal voltage calculated by the correction parameter calculation unit 32 to the drive transistor 120 included in the target pixel that is the target pixel for calculating the correction parameter, and emits light from the target pixel. By measuring the luminance using the measuring device 40, the emission luminance for each pixel is acquired.

  In addition, the measurement control unit 31 applies the third signal voltage calculated by the correction parameter calculation unit 32 to the drive transistor 120 included in the target pixel, and measures the emission luminance from the target pixel using the measurement device 40. As a result, the emission luminance of each pixel is acquired.

  The correction parameter calculation unit 32 uses the light emission luminance for each target pixel acquired by the measurement control unit 31 and a function representing the representative voltage-luminance characteristics, and uses the first correction parameter, the second correction parameter, and the second correction parameter for the target pixel. 3 correction parameters are calculated, and the calculated first to third correction parameters are output to the control circuit 10. The correction parameter calculation unit 32 stores the first to third correction parameters in the storage unit 13 of the organic EL display device 1.

  Specifically, the correction parameter calculation unit 32 uses the first reference voltage when the luminance obtained from the representative voltage-luminance characteristics is the luminance when the target pixel emits light with the first signal voltage (V1 in FIG. 5). (Vr1 in FIG. 5) is obtained, and a first correction parameter (OFS in FIG. 5) for changing the first signal voltage (V1) to the first reference voltage (Vr1) is obtained for the target pixel.

  The first correction parameter (OFS) is an offset voltage indicating the difference between the first signal voltage (V1) and the first reference voltage (Vr1).

  In addition, the correction parameter calculation unit 32 uses the luminance (LL1) when the target pixel emits light with the second signal voltage (V2) corresponding to one gradation belonging to the low gradation region of the representative voltage-luminance characteristics as the representative voltage. The second reference voltage (VinL in FIG. 5) obtained when input to the function representing the luminance characteristic is obtained by calculation, and the voltage difference between the first correction voltage (Vc1) and the first reference voltage (Vr1) and the second A gain indicating a ratio of the voltage difference between the reference voltage (VinL) and the first reference voltage (Vr1) is defined as a second correction parameter (Gain1).

  Further, the correction parameter calculation unit 32 represents the luminance (LH1) when the target pixel is caused to emit light with the third signal voltage (V3) corresponding to one gradation belonging to the high gradation region of the representative voltage-luminance characteristic. The third reference voltage (VinH in FIG. 5) obtained when input to the function representing the luminance characteristic is obtained by calculation, and the voltage difference between the second correction voltage (Vc2) and the first reference voltage (Vr1) and the third reference A gain indicating a ratio between the voltage (VinH) and the voltage difference between the first reference voltage (Vr1) is defined as a third correction parameter (Gain2).

  Further, the correction parameter calculation unit 32 obtains a first correction parameter, a second correction parameter, and a third correction parameter for each of red, green, and blue colors emitted from the light emitting element 110.

  The control circuit 10 is a processing unit for displaying an image on the display panel 20, and includes a control unit 11, a correction unit 12, and a storage unit 13.

  The control unit 11 outputs a signal to the display panel 20 to display an image on the display panel 20. Specifically, the control unit 11 causes the plurality of pixels 100 included in the display panel 20 to emit light according to an instruction from the measurement control unit 31. In addition, the control unit 11 writes the first correction parameter, the second correction parameter, and the third correction parameter for each pixel 100 calculated by the correction parameter calculation unit 32 in the storage unit 13.

  The storage unit 13 stores the first to third correction parameters input from the control unit 11 for each of the plurality of pixels 100. Specifically, the storage unit 13 stores a correction parameter table 13a including a first correction parameter, a second correction parameter, and a third correction parameter for each pixel 100.

  FIG. 4 is a diagram illustrating an example of a correction parameter table according to the first embodiment.

  As shown in the figure, the correction parameter table 13a is a data table including correction parameters including first to third correction parameters for each pixel.

In the figure, the first correction parameter is indicated by offset OS11 to offset OSmn, the second correction parameter is indicated by gain G _L 11 to gain G _L mn, and the third correction parameter is gain G _H 11 to gain. It is shown as _GH mn. That is, the correction parameter table 13a stores correction parameters configured by (gain G _L , gain G _H , offset OS) for each pixel 100 corresponding to the matrix of the display unit 21 (m rows × n columns). ing.

  The correction unit 12 reads a predetermined correction parameter corresponding to each of the plurality of pixels 100 from the storage unit 13 with respect to the video signal input from the outside, and corrects the video signal corresponding to each of the plurality of pixels 100. . Then, the correction unit 12 outputs the corrected video signal to the control unit 11, and the control unit 11 outputs the corrected video signal to the display panel 20, thereby displaying the video on the display panel 20.

<Correction principle and correction parameter calculation method>
Next, in describing the correction principle of the organic EL display device according to the first embodiment of the present invention, first, problems to be solved by the organic EL display device and the manufacturing method thereof of the present invention will be described.

  FIG. 5 is a graph showing voltage-luminance characteristics for explaining the correction principle of the organic EL display device according to the first embodiment. As shown in the figure, the representative voltage-luminance characteristic (representative VL characteristic in FIG. 5) is, for example, that the luminance of light emitted from the pixel 100 is the square of the voltage supplied to the drive transistor 120. The signal voltage-drain current characteristic corresponding to the representative voltage-luminance characteristic is expressed by the following equation (1).

  Here, Id is a signal current flowing through the driving transistor 120 and the light emitting element 110, k is a constant, μ is the mobility of the driving transistor 120, Vgs is a gate-source voltage of the driving transistor 120, and Vth is the driving transistor 120. It is a threshold voltage. The above equation 1 is a theoretical equation applied in the strong inversion region where Vgs> Vth. Since Equation 1 and the luminance L of the light emitting element 110 are proportional to the signal current Id, it can be seen that the luminance L is proportional to the square of (Vgs−Vth).

  Also, in the target pixel, when it is assumed that the current-voltage characteristic corresponding to the voltage-luminance characteristic is expressed by Equation 1, it can be seen that the luminance L of the target pixel depends on the threshold voltage Vth and the mobility μ. . Since the threshold voltage Vth and the mobility μ vary between TFTs constituting the driving transistor, the voltage-luminance characteristics of the target pixel vary from pixel to pixel. Therefore, when the same signal voltage is applied to each pixel without correction, luminance unevenness occurs because the emission luminance varies between the pixels. In order to eliminate this luminance unevenness, it is necessary to correct the signal voltage with a correction parameter that matches the voltage-luminance characteristic of the target pixel with the representative voltage-luminance characteristic.

  In the conventional correction method, in order to make the voltage-luminance characteristic of the target pixel coincide with the representative voltage-luminance characteristic, two correction parameters such as offset (voltage addition) and gain (voltage multiplication) are extracted to correct the signal voltage. Yes.

  FIG. 6 is a graph showing voltage-drain current characteristics according to human visibility. In this figure, since the human eye has a sensitivity close to the LOG function, the drain current is indicated by a curve of the LOG function, and the voltage-drain current characteristic corresponding to the human visual sensitivity is represented. Yes. From the graph shown in FIG. 6, it can be seen that the human eye does not easily recognize luminance unevenness in the high gradation range, and easily recognizes luminance unevenness in the middle gradation range and the low gradation range. For this reason, in order to increase the correction accuracy in accordance with human visibility, it is particularly preferable to set correction errors in the middle gradation region and the low gradation region to be small.

  However, for example, in the low gradation region below the threshold voltage Vth, there is a weak inversion region in which the theoretical formula of Equation 1 above does not hold. The signal voltage-drain current characteristic of the weak inversion region where Vgs <Vth is expressed by the following Expression 2.

  Here, W and L are the gate width and gate length of the drive transistor 120, B is the Boltzmann constant, and T is the temperature. Since Equation 1 and Equation 2 do not match, it can be seen that the voltage-luminance characteristics in the middle gradation region and the high gradation region are different from the voltage-luminance properties in the low gradation region. Therefore, for example, as seen in the pixel VL characteristic (thin solid line) which is the voltage-luminance characteristic of the target pixel described in FIG. 5, the characteristic curve at the high gradation and the characteristic curve at the low gradation are medium. It is assumed that the gradation ranges are different. From this, for example, a case where the curve of the representative VL characteristic (thick solid line) defined by Equation 1 and the curve of the pixel VL characteristic (solid line) do not match is assumed. In this case, for example, as a correction method for matching the pixel VL characteristic with the representative VL characteristic, the pixel VL characteristic graph illustrated in FIG. 5 is translated to the right (positive voltage direction) ( Even if the voltage offset (thin broken line) is used, the two characteristics do not match in the low gradation area and the high gradation area, and further, both the characteristics match in the high gradation area by tilting (gaining) the graph of the pixel VL characteristics. Even if it is made, both characteristics cannot be matched in the low gradation range. That is, with the conventional correction method using two parameters of offset and gain, it is difficult to perform high-precision correction over all gradations.

  Therefore, a correction method using three or more parameters can be cited as a method for performing high-accuracy correction over all gradations. Hereinafter, the correction methods based on the three parameters will be compared using FIGS. 7A to 7C.

  FIG. 7A is a diagram illustrating a voltage-luminance characteristic for explaining a method of correcting the offset in the middle gradation region and the gain in the low gradation region and the high gradation region, and FIG. 7B illustrates the offset and medium in the low gradation region. FIG. 7C is a diagram illustrating a voltage-luminance characteristic for explaining a method of correcting a gain in a gradation region and a high gradation region, and FIG. 7C corrects an offset in a high gradation region and a gain in a low gradation region and a middle gradation region. It is a figure showing the voltage-luminance characteristic explaining a system.

  When calculating the correction parameter in each gradation region, there is always an operation error due to the bit number limitation in the calculation operation of the correction parameter. In the correction method shown in FIG. 7B, since offset correction is performed in the low gradation range, (offset calculation error in the low gradation range + gain calculation error in the middle gradation range) occurs in the middle gradation range. . Further, in the high gradation range, (offset calculation error in the low gradation range + gain calculation error in the middle gradation range + gain calculation error in the high gradation range) occurs, and the correction calculation error in the high gradation range becomes large. Further, in the correction method shown in FIG. 7C, offset correction is performed in the high gradation range, so that (offset calculation error in the high gradation range + gain calculation error in the middle gradation range) occurs in the middle gradation range. . Further, in the low gradation range, (offset calculation error in the high gradation range + gain calculation error in the middle gradation range + gain calculation error in the low gradation range) occurs, and the correction calculation error in the low gradation range increases. .

  On the other hand, in the correction method shown in FIG. 7A, (offset calculation error in the middle gradation range + gain calculation error in the high gradation range) occurs in the high gradation range, and (middle floor) in the low gradation range. An offset calculation error in the adjustment range + a gain calculation error in the low gradation range) occurs. In the high gradation region and the low gradation region in the correction method shown in FIG. 7A, the gain operation error in the other gradation regions is not superimposed, so that the operation error is smaller than the method shown in FIGS. 7B and 7C. Can be small.

  Further, since luminance unevenness in the middle gradation range is easily visually recognized, it is preferable that correction is performed only with an offset in the middle gradation range so that a calculation error in the middle gradation range is reduced.

  That is, for the offset correction and the gain correction, calculation errors occur and luminance unevenness in the middle gradation range is easily visually recognized. Therefore, first, the offset correction is performed in the middle gradation range near the threshold voltage Vth. Therefore, it is desirable to execute gain correction in the high gradation region and the low gradation region in a state where the offset correction is performed.

  The manufacturing method of the organic EL display device according to the first embodiment of the present invention includes a correction method defined by the above viewpoint. That is, in contrast to the above-described problem in the conventional correction method, the method for manufacturing the organic EL display device according to the first embodiment of the present invention includes at least an offset in the middle gradation region near the threshold voltage Vth, a gain in the high gradation region, And a step of determining three correction parameters, that is, a gain in a low gradation region. That is, by adjusting the voltage near the threshold voltage Vth with an offset and using two types of gains, a gain for a high gradation region and a gain for a low gradation region, the correction in the low gradation region, which has been particularly difficult to correct, is performed. The error can be reduced, and as a result, highly accurate correction can be performed over all gradations. As a result, it is possible to perform correction corresponding to changes in the curve shape of the voltage-luminance characteristics that are different between the strong inversion region and the weak inversion region of the driving transistor.

  Hereinafter, the correction principle of the organic EL display device 1 will be described in detail while explaining the process in which the correction parameter determination device 30 determines the correction parameter.

  FIG. 8 is a flowchart illustrating an example of an operation in which the correction parameter determination device according to Embodiment 1 determines a correction parameter.

  As shown in the figure, first, the measurement control unit 31 obtains a function representing a representative voltage-luminance characteristic (S10: first step). In the graph of FIG. 5, the representative VL characteristic (thick solid line) corresponds to the representative voltage-luminance characteristic acquired in this step. Details of the processing for acquiring the function representing the representative voltage-luminance characteristic will be described later.

  Next, the correction parameter calculation unit 32 calculates the first correction parameter (offset voltage) in the middle gradation range for the target pixel (S20). In the graph of FIG. 5, the voltage difference (OFS: white triangle and black) in the middle gradation region between the pixel VL characteristic (thin solid line) which is the voltage-luminance characteristic of the target pixel and the representative VL characteristic (thick solid line). The voltage difference from the triangle) corresponds to the first correction parameter calculated in this step. Details of the processing for calculating the first correction parameter will be described later with reference to FIG. 9A.

  Next, the correction parameter calculation unit 32 calculates the second correction parameter (low gradation gain) in the low gradation region for the target pixel (S30). In the graph of FIG. 5, the gain difference (Gain1) in the low gradation region between the voltage-luminance characteristic (thin broken line) obtained by offsetting the voltage-luminance characteristic of the target pixel and the representative VL characteristic (thick solid line) This corresponds to the second correction parameter calculated in the step. Details of the process of calculating the second correction parameter will be described later with reference to FIG. 9B.

  Next, the correction parameter calculation unit 32 calculates a third correction parameter (high gradation gain) in the high gradation region for the target pixel (S40). In the graph of FIG. 5, the gain difference (Gain 2) in the high gradation region between the voltage-luminance characteristic (thin broken line) obtained by offsetting the voltage-luminance characteristic of the target pixel and the representative VL characteristic (thick solid line) is shown in this step. This corresponds to the third correction parameter calculated in (1). Details of the process of calculating the third correction parameter will be described later with reference to FIG. 9C.

  Thus, the process of determining the correction parameter by the correction parameter determining apparatus 30 is completed.

  Next, details of the process (S10 in FIG. 8) in which the measurement control unit 31 acquires a function representing the representative voltage-luminance characteristic will be described.

  Specifically, the following two acquisition methods are mentioned as the processing in step S10. First, the first acquisition method will be described.

  The measurement control unit 31 causes the control unit 11 to apply a data voltage to the measurement pixel for obtaining a function representing the representative voltage-luminance characteristic, and to cause a current to flow through the measurement pixel, so that the measurement pixel The light emitting element 110 is caused to emit light, and the measurement device 40 is caused to measure the luminance of the display panel 20. The data voltage application and the luminance measurement are performed a plurality of times at different data voltages. Further, the data voltage application and the luminance measurement may be performed simultaneously on a plurality of measurement pixels, or may be repeatedly performed for each measurement pixel. Next, the measurement control unit 31 obtains a voltage-luminance characteristic for each measurement pixel from the data voltage obtained in the data voltage application and luminance measurement and the corresponding luminance. Finally, the measurement control unit 31 obtains the representative voltage-luminance characteristics by averaging the voltage-luminance characteristics obtained for each of the plurality of measurement pixels.

  Next, the second acquisition method will be described.

  The measurement control unit 31 causes the control unit 11 to simultaneously apply a common data voltage to the plurality of measurement pixels to cause a current to flow through the plurality of measurement pixels at the same time, and the light emitting elements 110 of the plurality of measurement pixels. Are simultaneously emitted, and the measurement apparatus 40 is caused to measure the total luminance of the plurality of measurement pixels. The data voltage application and the luminance measurement are performed a plurality of times at different data voltages. Next, the measurement control unit 31 divides the total luminance value obtained in the data voltage application and luminance measurement by a plurality of measurement pixels. Finally, the division process is executed for each data voltage to obtain the representative voltage-luminance characteristics.

  By obtaining the representative voltage-luminance characteristics by the two methods described above, the current is measured only for a plurality of selected measurement pixels, instead of measuring the current of all the pixels 100 included in the display panel 20. Therefore, it is possible to greatly shorten the time required to set the representative voltage-luminance characteristics common to the entire display panel 20.

  Note that the first and second specific methods for obtaining the representative voltage-luminance characteristics need not be applied to each organic EL display device of the present invention. For example, as the representative voltage-luminance characteristic, the representative voltage-luminance characteristic acquired in the manufacturing method of another organic EL display device manufactured under the same conditions is used as it is as the representative voltage-luminance characteristic of its own organic EL display device. May be. As a result, the representative voltage-luminance characteristics obtained by a manufacturing method of a certain organic EL display device are used in a manufacturing method of another organic EL display device manufactured under the same conditions as the device. It is possible to save the trouble of setting the representative voltage-luminance characteristics every time the correction parameter is measured. As a result, the manufacturing process of the apparatus can be shortened.

  The representative voltage-luminance characteristic may be a voltage-luminance characteristic for any one of a plurality of pixels included in the display panel 20. This also makes it possible to easily obtain a function representing the representative voltage-luminance characteristics, thereby shortening the manufacturing process of the apparatus.

  Next, details of the process (S20 in FIG. 8) in which the correction parameter calculation unit 32 calculates the first correction parameter will be described with reference to FIGS. 5 and 9A.

  FIG. 9A is a flowchart illustrating an example of a process in which the correction parameter calculation unit according to Embodiment 1 calculates a first correction parameter.

  First, the measurement control unit 31 is a drive element that includes, in the target pixel, the first signal voltage (V1) corresponding to one gradation belonging to the middle gradation region of the representative voltage-luminance characteristic. The luminance (LM1) emitted from the pixel is applied to the driving transistor 120 and measured using the measuring device 40 (S210: second step). Here, the first signal voltage (V1) is preferably set to a voltage value in the vicinity of the threshold voltage Vth that is a boundary between the weak inversion region and the strong inversion region of the driving transistor. In the graph of FIG. 5, the voltage V1 on the voltage-luminance characteristics (thin solid line) of the target pixel corresponds to the first signal voltage.

  Next, the correction parameter calculation unit 32 calculates a first reference voltage (Vr1) at which the luminance of the representative voltage-luminance characteristic becomes the luminance (LM1) of the target pixel (S220: third step). In the graph of FIG. 5, the reference voltage Vr1 on the representative voltage-luminance characteristic (thick solid line) corresponds to the first reference voltage.

  Next, the correction parameter calculation unit 32 calculates a first correction parameter (OFS) for changing the first signal voltage (V1) to the first reference voltage (Vr1) for the target pixel (S230: third step). That is, the first correction parameter (OFS) is an offset voltage that combines the voltage-luminance characteristics and the representative voltage-luminance characteristics of the target pixel in the middle gradation range, and is expressed by the following Expression 3.

First correction parameter (OFS) = first signal voltage (V1) −first reference voltage (Vr1)
(Formula 3)

  Thus, the correction parameter calculation unit 32 ends the process of calculating the first correction parameter (S20 in FIG. 8).

  Next, details of the process (S30 in FIG. 8) in which the correction parameter calculation unit 32 calculates the second correction parameter will be described with reference to FIGS. 5 and 9B.

  FIG. 9B is a flowchart illustrating an example of a process in which the correction parameter calculation unit according to Embodiment 1 calculates a second correction parameter.

  First, the measurement control unit 31 gives the control circuit 10 the luminance (LL1) of the target pixel at the second signal voltage (V2) corresponding to one gradation belonging to the low gradation region of the representative voltage-luminance characteristic. Measurement is performed using the measuring device 40 (S310: fourth step). Here, the second signal voltage (V2) is preferably set to a voltage value in a weak inversion region that is smaller than the threshold voltage Vth of the driving transistor.

Next, the correction parameter calculation unit 32 receives the second reference voltage obtained when the luminance (LL1) when the target pixel is caused to emit light with the second signal voltage (V2) is input to the function representing the representative voltage-luminance characteristics. (VinL) is calculated and the voltage difference (Vc1−) between the first correction voltage (Vc1) obtained by adding the first correction parameter (OFS) to the second signal voltage (V2) and the first reference voltage (Vr1). A gain indicating a ratio between Vr1) and a voltage difference (VinL−Vr1) between the second reference voltage (VinL) and the first reference voltage (Vr1) is defined as a second correction parameter (G _L ). (S320: 5th step). That is, the correction parameter (G _L ) is expressed by the following formula 4.

G _L = (Vc1−Vr1) / (VinL−Vr1)
= (Second signal voltage V2-first correction parameter OFS-first reference voltage Vr1)
/ (Second reference voltage VinL−first reference voltage Vr1) (Formula 4)

  In the graph of FIG. 5, (Vc1-Vr1) is VD1, and (VinL-Vr1) is equivalent to VDL.

  Thus, the correction parameter calculation unit 32 ends the process of calculating the second correction parameter (S30 in FIG. 8).

  Next, details of the process (S40 in FIG. 8) in which the correction parameter calculation unit 32 calculates the third correction parameter will be described with reference to FIGS. 5 and 9C.

  FIG. 9C is a flowchart illustrating an example of a process in which the correction parameter calculation unit according to Embodiment 1 calculates a third correction parameter.

  First, the measurement control unit 31 causes the control circuit 10 to measure the luminance (LH1) of the target pixel at the third signal voltage (V3) corresponding to one gradation belonging to the high gradation region of the representative voltage-luminance characteristic. Measurement is performed using the device 40 (S410: sixth step). Here, the third signal voltage (V3) is preferably set to a voltage value in a strong inversion region that is larger than the threshold voltage Vth of the driving transistor.

Next, the correction parameter calculation unit 32 receives the third reference voltage obtained when the luminance (LH1) when the target pixel is caused to emit light at the third signal voltage (V3) is input to the function representing the representative voltage-luminance characteristics. (VinH) is obtained by calculation, and the voltage difference (Vc2−) between the second correction voltage (Vc2) obtained by adding the first correction parameter (OFS) to the third signal voltage (V3) and the first reference voltage (Vr1). A gain indicating a ratio between Vr1) and a voltage difference (VinH−Vr1) between the third reference voltage (VinH) and the first reference voltage (Vr1) is defined as a third correction parameter ( _GH ). (S420: 7th step). That is, the correction parameter ( _GH ) is expressed by the following formula 5.

G _H = (Vc2−Vr1) / (VinH−Vr1)
= (Third signal voltage V3-first correction parameter OFS-first reference voltage Vr1)
/ (Third reference voltage VinH−First reference voltage Vr1) (Formula 5)

  In the graph of FIG. 5, (Vc2-Vr1) is VD2, and (VinH-Vr1) is equivalent to VDH.

  Thus, the correction parameter calculation unit 32 ends the process of calculating the third correction parameter (S40 in FIG. 8).

As described above, the calculation process (step S20 to step S40) of the first correction parameter (OFS), the second correction parameter (G _L ), and the third correction parameter (G _H ) described in FIG. And finally, the calculated first to third correction parameters are written in the storage unit 13 to complete the correction parameter table shown in FIG.

  The organic EL display device manufactured by the organic EL display device manufacturing method of the present invention including the correction parameter calculation process described above corrects a video signal using the correction parameter and supplies a correction signal voltage to each pixel. It becomes possible. As a result, it is possible to display an image with reduced luminance unevenness with high accuracy over all gradations.

<Correction method>
Next, a process in which the organic EL display device manufactured by the above manufacturing method generates a correction signal voltage using the correction parameter calculated in the manufacturing process will be described with reference to FIGS.

  FIG. 10 is a block diagram showing a correction process of the organic EL display device according to the first embodiment of the present invention. The block diagram shown in the figure represents an operation flow of the correction unit 12 included in the control circuit 10.

  The control circuit 10 receives an external video signal and acquires gradation data to be displayed by each pixel 100 from the video signal. The correction unit 12 determines a corrected signal voltage for causing the light emitting element 110 of each pixel 100 to emit light with this gradation data by the following process.

  First, the correction unit 12 determines a signal voltage (input value) before correction for displaying the gradation data, assuming that the target pixel is a pixel having the representative VL characteristic in FIG. . If the gradation data at this time is data for causing the light emitting element 110 to emit light with the luminance LL1 in the low gradation region in the graph shown in FIG. 5, the correction unit 12 sets the input value to VinL.

  Next, the correction unit 12 subtracts the first reference voltage Vr1 from the input value VinL by the subtractor 211 to calculate (VinL−Vr1).

Next, the correction unit 12 is calculated by the multiplier 212 and (VinL-Vr1) _G multiplied by the gain _{G L} is the second correction parameter L (VinL-Vr1), the third corrected by the multiplier 213 calculating the _G H multiplied by the gain _{G H} is a parameter (VinL-Vr1).

Next, when the value of (VinL−Vr1) calculated by the subtractor 211 is negative, the correction unit 12 selects G _L (VinL−Vr1) calculated by the multiplier 212. When the value of (VinL−Vr1) calculated by the subtractor 211 is positive, G _H (VinL−Vr1) calculated by the multiplier 213 is selected. In this example, since the input value VinL <the first reference voltage Vr1, the correction unit 12 selects G _L (VinL−Vr1).

Next, the correction unit 12 uses the adder 215 to add the offset (OFS) and the reference value (Vr1), which are the first correction parameters, to the selected G _L (VinL−Vr1). 5 and Expression 4, the pixel voltage value (correction signal voltage) that is the output of the correction unit 12 is expressed by Expression 6 below.

Correction signal voltage = G _L (VinL−Vr1) + OFS + Vr1 = Vc1 + OFS (Formula 6)

  OFS in Equation 6 is the first correction parameter in Equation 3, and the correction signal voltage eventually becomes V2 in FIG. By the correction operation of the correction unit 12, a correction signal voltage V2 for causing the light emitting element 110 of the target pixel to emit light with the luminance LL1 reflecting the gradation data is calculated.

  Note that the correction unit 12 performs the same correction process when correcting the signal voltage for data in the high gradation range. For example, in the case of data for causing the light emitting element 110 to emit light with the luminance LH1 in the high gradation range, the correction unit 12 calculates V3 as the correction signal voltage by the correction process.

  As described above, according to the display device of the present invention and the method for manufacturing the same, the display device of the present invention is capable of providing the offset voltage calculated in the middle gradation region, the low gradation gain and the high gradation region calculated in the low gradation region. It is possible to correct the signal voltage with high accuracy using the high gradation gain calculated in step 1, and to display a high-quality image with reduced luminance unevenness.

Use In the above-described correction parameter calculation method, when determining the low gradation region gain G _L and the high Choiki gain G _H, as in the above formula 4 and formula 5, the first reference voltage Vr1 of medium gradation region However, it is not limited to this. Without using the first reference voltage Vr1 in the middle gradation range, for example, the slope between two points in the low gradation range on the voltage-luminance characteristics of the target pixel and the low gradation range on the representative voltage-luminance characteristics. The low gradation range gain _GL may be calculated by comparing the slope between two points. In this case, the measurement control unit 31 performs luminance measurement at two points in the low gradation range.

(Embodiment 2)
In the first embodiment, three correction parameters corresponding to each gradation area are set in order to reduce the correction error. However, in this embodiment, the gradation area is further subdivided for the purpose of further reducing the correction error. A case will be described in which four or more correction parameters are set.

  The configuration of the control circuit and the correction parameter determination device according to the present embodiment is the same as that of the control circuit 10 and the correction parameter determination device 30 shown in FIG.

  In the method of manufacturing the organic EL display device according to the second embodiment of the present invention, the display gradation area is divided into four gradation areas, that is, a low gradation area, a medium gradation area 1, a medium gradation area 2, and a high gradation area. The correction is performed by five correction parameters, namely, an offset in the middle gradation area 1 and the intermediate gradation area 2, a gain in the high gradation area, a gain in the intermediate gradation area, and a gain in the low gradation area. That is, it is possible to further reduce the correction error in the entire gradation range by subdividing the gradation range in which the correction parameter is to be generated. As a result, it is possible to perform a correction corresponding to the change in the curve shape of the voltage-luminance characteristic which is different between the strong inversion region and the weak inversion region of the driving transistor with high accuracy.

  Hereinafter, the correction principle of the organic EL display device according to the present embodiment will be described in detail while explaining the process in which the correction parameter determination device determines the correction parameter. In addition, description is abbreviate | omitted when operation | movement of the measurement control part 31 and the correction parameter calculation part 32 is the same operation | movement as Embodiment 1. FIG.

  FIG. 11 is a graph showing voltage-luminance characteristics for explaining the correction principle of the organic EL display device according to the second embodiment.

  First, the measurement control unit 31 acquires a function representing the representative voltage-luminance characteristic. In the graph of FIG. 11, the representative VL characteristic (thick solid line) corresponds to the representative voltage-luminance characteristic acquired in this step.

  Next, the correction parameter calculation unit 32 calculates the first correction parameter (OFS1) in the middle gradation range 1 for the target pixel. In the graph of FIG. 11, the voltage difference (OFS1) in the middle gradation range between the pixel VL characteristic (thin solid line) and the representative VL characteristic (thick solid line), which is the voltage-luminance characteristic of the target pixel, is shown in this step. This corresponds to the first correction parameter calculated in (1).

  Next, the correction parameter calculation unit 32 calculates the second correction parameter (low gradation gain) in the low gradation region for the target pixel. In the graph of FIG. 11, the gain difference (Gain1) in the low gradation range between the voltage-luminance characteristic (thin broken line) in which the voltage-luminance characteristic of the target pixel is offset by OFS1 and the representative VL characteristic (thick solid line) is shown. This corresponds to the second correction parameter calculated in this step.

  Next, the correction parameter calculation unit 32 calculates a third correction parameter (medium gradation 2 gain) in the intermediate gradation area 2 for the target pixel. In the graph of FIG. 11, the gain difference (Gain2) in the middle gradation region 2 between the voltage-luminance characteristic (thin broken line) in which the voltage-luminance characteristic of the target pixel is offset and the representative VL characteristic (thick solid line) is This corresponds to the third correction parameter calculated in this step.

  Next, the correction parameter calculation unit 32 calculates the fourth correction parameter (OFS2) in the middle gradation range 2 for the target pixel. In the graph of FIG. 11, the voltage difference (OFS2) in the middle gradation region 2 between the pixel VL characteristic (thin solid line) and the representative VL characteristic (thick solid line), which is the voltage-luminance characteristic of the target pixel, is represented by this graph. This corresponds to the fourth correction parameter calculated in the step.

  Next, the correction parameter calculation unit 32 calculates a fifth correction parameter (high gradation gain) in the high gradation range for the target pixel. In the graph of FIG. 11, the gain difference (Gain3) in the high gradation region between the voltage-luminance characteristic (thin broken line) in which the voltage-luminance characteristic of the target pixel is offset by OFS2 and the representative VL characteristic (thick solid line) is This corresponds to the fifth correction parameter calculated in this step.

  Thus, the process of determining the correction parameter by the correction parameter determination device is completed.

  Next, details of the process in which the correction parameter calculation unit 32 calculates the first correction parameter will be described with reference to FIG.

  First, the measurement control unit 31 causes the control circuit 10 to apply the first signal voltage (V1) corresponding to one gradation belonging to the middle gradation range 1 of the representative voltage-luminance characteristic to the control element 10 using a drive element included in the target pixel. The luminance (LM 1) emitted from the pixel is applied to a certain driving transistor 120 and measured using the measuring device 40. Here, the first signal voltage is preferably set to a voltage value near the threshold voltage Vth of the driving transistor. In the graph of FIG. 10, the voltage V1 on the voltage-luminance characteristics (thin solid line) of the target pixel corresponds to the first signal voltage.

  Next, the correction parameter calculation unit 32 calculates a first reference voltage (Vr1) in which the luminance of the representative voltage-luminance characteristic is the luminance (LM1) of the target pixel. In the graph of FIG. 11, the reference voltage Vr1 on the representative voltage-luminance characteristic (thick solid line) corresponds to the first reference voltage.

  Next, the correction parameter calculation unit 32 calculates a first correction parameter (OFS1) for changing the first signal voltage (V1) to the first reference voltage (Vr1) for the target pixel. That is, the first correction parameter (OFS1) is an offset voltage that combines the voltage-luminance characteristics and the representative voltage-luminance characteristics of the target pixel in the middle gradation range 1, and is expressed by the following Expression 7.

First correction parameter (OFS1) = first signal voltage (V1) −first reference voltage (Vr1)
(Formula 7)

  Thus, the correction parameter calculation unit 32 ends the process of calculating the first correction parameter.

  Next, details of the process in which the correction parameter calculation unit 32 calculates the second correction parameter will be described with reference to FIG.

  First, the measurement control unit 31 gives the control circuit 10 the luminance (LL1) of the target pixel at the second signal voltage (V2) corresponding to one gradation belonging to the low gradation region of the representative voltage-luminance characteristic. Measurement is performed using the measuring device 40. Here, the second signal voltage is preferably set to a voltage value in a weak inversion region that is smaller than the threshold voltage Vth of the driving transistor.

Next, the correction parameter calculation unit 32 receives the second reference voltage obtained when the luminance (LL1) when the target pixel is caused to emit light with the second signal voltage (V2) is input to the function representing the representative voltage-luminance characteristics. (VinL) is obtained by calculation, and the voltage difference (Vc1−) between the first correction voltage (Vc1) obtained by adding the first correction parameter (OFS1) to the second signal voltage (V2) and the first reference voltage (Vr1). A gain indicating a ratio between Vr1) and a voltage difference (VinL−Vr1) between the second reference voltage (VinL) and the first reference voltage (Vr1) is defined as a second correction parameter (G _L ). That is, the correction parameter (G _L ) is expressed by the following formula 8.

G _L = (Vc1−Vr1) / (VinL−Vr1)
= (Second signal voltage V2-first correction parameter OFS1-first reference voltage Vr1)
/ (Second reference voltage VinL−first reference voltage Vr1) (Equation 8)

  In the graph of FIG. 11, (Vc1-Vr1) is VD1, and (VinL-Vr1) is equivalent to VDL.

  Thus, the correction parameter calculation unit 32 ends the process of calculating the second correction parameter.

  Next, details of the process in which the correction parameter calculation unit 32 calculates the third correction parameter will be described with reference to FIG.

  First, the measurement control unit 31 gives the control circuit 10 the luminance (LM2) of the target pixel at the third signal voltage (V3) corresponding to one gradation belonging to the middle gradation region 2 of the representative voltage-luminance characteristic. Measure using the measuring device 40.

Next, the correction parameter calculation unit 32 receives the third reference voltage obtained when the luminance (LM2) when the target pixel is caused to emit light with the third signal voltage (V3) is input to the function representing the representative voltage-luminance characteristics. (VinM) is obtained by calculation, and the voltage difference (Vc2−) between the second correction voltage (Vc2) obtained by adding the first correction parameter (OFS1) to the third signal voltage (V3) and the first reference voltage (Vr1). A gain indicating a ratio between Vr1) and a voltage difference (VinM−Vr1) between the third reference voltage (VinM) and the first reference voltage (Vr1) is defined as a third correction parameter (G _M ). That is, the correction parameter (G _M ) is expressed by the following formula 9.

G _M = (Vc2−Vr1) / (VinM−Vr1)
= (Third signal voltage V3-first correction parameter OFS1-first reference voltage Vr1)
/ (Third reference voltage VinM−First reference voltage Vr1) (Equation 9)

  In the graph of FIG. 11, (Vc2-Vr1) is VD2, and (VinM-Vr1) is equivalent to VDM.

  Thus, the correction parameter calculation unit 32 ends the process of calculating the third correction parameter.

  Next, details of the process in which the correction parameter calculation unit 32 calculates the fourth correction parameter will be described with reference to FIG.

  First, the measurement control unit 31 causes the control circuit 10 to apply the fourth signal voltage (V3) corresponding to one gradation belonging to the middle gradation range 2 of the representative voltage-luminance characteristic to the control element 10 using a drive element included in the target pixel. The luminance (LM2) emitted from the pixel is applied to a certain driving transistor 120 and measured using the measuring device 40. In the graph of FIG. 10, the voltage V3 on the voltage-luminance characteristic (thin solid line) of the target pixel corresponds to the fourth signal voltage.

  Next, the correction parameter calculation unit 32 calculates a second reference voltage (Vr2) in which the luminance of the representative voltage-luminance characteristic is the luminance (LM2) of the target pixel. In the graph of FIG. 10, the reference voltage Vr2 on the representative voltage-luminance characteristic (thick solid line) corresponds to the second reference voltage.

  Next, the correction parameter calculation unit 32 calculates the fourth correction parameter (OFS2) for setting the fourth signal voltage (V3) to the second reference voltage (Vr2) for the target pixel. That is, the fourth correction parameter (OFS2) is an offset voltage that combines the voltage-luminance characteristics and the representative voltage-luminance characteristics of the target pixel in the middle gradation range 2, and is expressed by the following Expression 10.

Fourth correction parameter (OFS2) = fourth signal voltage (V3) −second reference voltage (Vr2)
(Formula 10)

  Thus, the correction parameter calculation unit 32 ends the process of calculating the fourth correction parameter.

  Next, details of the process in which the correction parameter calculation unit 32 calculates the fifth correction parameter will be described with reference to FIG.

  First, the measurement control unit 31 causes the control circuit 10 to measure the luminance (LH1) of the target pixel at the fifth signal voltage (V4) corresponding to one gradation belonging to the high gradation region of the representative voltage-luminance characteristic. Measurement is performed using the device 40.

Next, the correction parameter calculation unit 32 inputs the fourth reference voltage obtained when the luminance (LH1) when the target pixel emits light with the fifth signal voltage (V4) is input to the function representing the representative voltage-luminance characteristics. (VinH) is obtained by calculation, and the voltage difference (Vc3−) between the third correction voltage (Vc3) obtained by adding the fourth correction parameter (OFS2) to the fifth signal voltage (V4) and the second reference voltage (Vr2). A gain indicating a ratio between Vr2) and a voltage difference (VinH−Vr2) between the fourth reference voltage (VinH) and the second reference voltage (Vr2) is defined as a fifth correction parameter ( _GH ). That is, the correction parameter ( _GH ) is expressed by the following equation 11.

_GH = (Vc3-Vr2) / (VinH-Vr2)
= (5th signal voltage V4-4th correction parameter OFS2-2nd reference voltage Vr2)
/ (Fourth reference voltage VinH−second reference voltage Vr2) (formula 11)

  In the graph of FIG. 11, (Vc3-Vr2) is VD3, and (VinH-Vr2) is equivalent to VDH.

  Thus, the correction parameter calculation unit 32 ends the process of calculating the fifth correction parameter.

As described above, the first correction parameter (OFS1), the second correction parameter (G _L ), the third correction parameter (G _M ), the fourth correction parameter (OFS2), and the fifth correction according to the present embodiment. The correction parameter table is completed by executing the parameter ( _GH ) calculation process for all pixels.

<Correction method>
A process in which the organic EL display device manufactured by the above manufacturing method generates the correction signal voltage using the correction parameter will be described with reference to FIGS.

  FIG. 12 is a block diagram showing a correction process of the organic EL display device according to the second embodiment of the present invention. The block diagram shown in the figure represents an operation flow of the correction unit 12 included in the control circuit 10.

  The control circuit 10 receives an external video signal and acquires gradation data to be displayed by each pixel 100 from the video signal. The correction unit 12 determines a signal voltage for causing the light emitting element 110 of each pixel 100 to emit light based on the gradation data by the following process.

  First, the correction unit 12 determines a signal voltage (input value) before correction for displaying the gradation data, assuming that the target pixel is a pixel having a representative VL characteristic. If the gradation data at this time is data for causing the light emitting element 110 to emit light with the luminance LL1 in the low gradation region in the graph illustrated in FIG. 11, the correction unit 12 sets the input value to VinL.

  Next, the correction unit 12 subtracts the first reference voltage Vr1 and the second reference voltage Vr2 from the input value VinL by the subtracters 221 and 226, respectively, and calculates (VinL−Vr1) and (VinL−Vr2).

Next, the correction unit 12 uses the multiplier 222 to multiply the calculated (VinL−Vr1) by the gain _GL that is the second correction parameter, _GL (VinL−Vr1), and the multiplier 223 to the correction parameter a is the gain _{G M} obtained by multiplying the _G M (VinL-Vr1), by the multiplier 227, the calculated (VinL-Vr2) to the fifth is a correction parameter gain _{G H} multiplied by _G H (VinL -Vr2).

Next, the correction unit 12, the comparison selector 224, when the value of which is calculated by the subtracter 221 (VinL-Vr1) is negative, and selects the calculated _G L (VinL-Vr1) by the multiplier 222 , the value of which is calculated by the subtracter 221 (VinL-Vr1) is the case of positive, selects the calculated _G M (VinL-Vr1) by the multiplier 223. In this example, since the input value VinL <the first reference voltage Vr1, the correction unit 12 selects G _L (VinL−Vr1).

Next, the correction unit 12 uses the adder 225 to add the offset (OFS1) and the reference value (Vr1) that are the first correction parameters to the selected G _L (VinL−Vr1). 11 and Expression 8, the output of the adder 225 is expressed by Expression 12 below.

Output of adder 225 = G _L (VinL−Vr1) + OFS1 + Vr1 = Vc1 + OFS1
(Formula 12)

  OFS1 in Equation 12 is the first correction parameter in Equation 7, and the output of the adder 225 is V2 in FIG.

Further, the correction unit 12 adds the offset (OFS2) and the reference value (Vr2), which are the fourth correction parameters, to _GH (VinL−Vr1) that is the output of the multiplier 227 by the adder 228.

  Next, when the value of (VinL−Vr2) calculated by the subtractor 226 is negative by the comparison selector 229, the correction unit 12 selects V2 calculated by the adder 225 and calculates by the subtractor 226. When the value of (VinL−Vr2) is positive, the output of the adder 228 is selected. In this example, since the input value VinL <the second reference voltage Vr2, the correction unit 12 selects V2.

  By the correction operation of the correction unit 12, a correction signal voltage V2 for causing the light emitting element 110 of the target pixel to emit light with the luminance LL1 reflecting the gradation data is calculated.

  Note that the correction unit 12 performs the same correction process when correcting the signal voltage with respect to the data of the high gradation region and the intermediate gradation region.

  As described above, according to the organic EL display device and the manufacturing method thereof according to Embodiment 2 of the present invention, the display device of the present invention has two offset voltages calculated in the intermediate gradation region 1 and the intermediate gradation region 2. Using the low gradation gain calculated in the low gradation area, the medium gradation gain calculated in the middle gradation area, and the high gradation gain calculated in the high gradation area, the signal voltage can be corrected with higher accuracy. It can be executed and a high quality image with reduced luminance unevenness can be displayed.

In the above-described correction parameter calculation method, the low gradation area gain G _L, Upon obtaining the medium gradation range gain G _M and higher order Choiki gain G _H, as in the above formulas 8,9 and 11, medium gradation Although the first reference voltage Vr1 in the area 1 and the second reference voltage Vr2 in the middle gradation area 2 are used, the present invention is not limited to this. Without using the first reference voltage Vr1 and the second reference voltage Vr2, for example, the slope between two points in the low gradation region on the voltage-luminance characteristics of the target pixel and the low gradation region on the representative voltage-luminance characteristics The low gradation range gain _GL may be calculated by comparing the slope between the two points. In this case, the measurement control unit 31 performs luminance measurement at two points in the low gradation range.

  As described above, the first to third correction parameters are written in the storage unit 13 which is a predetermined memory used in the display panel 20 as in the organic EL display device and the manufacturing method thereof according to the first and second embodiments. Thus, the correction accuracy of all gradations including the low gradation region is obtained by correcting the signal voltage input to each pixel 100 using the first to third correction parameters stored in the predetermined memory. Can be increased. As a result, the luminance unevenness of the display panel 20 recognized by human eyes can be reduced.

  As mentioned above, although the manufacturing method and display apparatus of the display apparatus of this invention were demonstrated based on Embodiment 1 and 2, this invention is not limited to embodiment mentioned above.

  That is, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, in the first and second embodiments, the correction parameter determination device 30 determines the first to third correction parameters for all the pixels 100 included in the display panel 20. However, the correction parameter determination device 30 may determine the first to third correction parameters for only some of the pixels 100 included in the display panel 20.

  In the first and second embodiments, the correction parameter calculation unit 32 stores the calculated first to third correction parameters in the storage unit 13. However, the correction parameter calculation unit 32 may end the process without storing the first to third correction parameters in the storage unit 13.

  In the first and second embodiments, the correction parameter is determined from the relationship between the voltage and the luminance at each pixel by using the voltage-luminance characteristics at each pixel. However, the correction parameter is determined from the relationship between the voltage and current in each pixel by using the voltage-current characteristics of each pixel using the value of the current flowing through the light emitting element 110 instead of the luminance. It may be. Since the luminance and the current are in a proportional relationship, the correction parameter can be determined by a similar method by replacing the luminance in the first and second embodiments with the current.

  In the method for manufacturing a display device of the present invention, it is preferable to set the offset voltage that is the first correction parameter in the middle gradation region in the vicinity of the threshold voltage value of the drive transistor 120. Here, in the display device manufacturing method and the display device of the present invention, the threshold voltage Vth of the drive transistor 120 is defined as follows.

  FIG. 13 is a graph for defining the threshold voltage of the drive transistor included in the display device of the present invention. The figure shows the relationship between the gate-source voltage Vgs of the drive transistor 120 and the drain current Id.

  Here, in the strong inversion region where Vgs> Vth, the above-described theoretical formula of Formula 1 is applied. Therefore, Formula 1 is converted to obtain Formula 13 below.

From the above equation 13, there is a region where the graph of Id ^1/2 -Vgs is a straight line. The X-axis intercept of this straight line is defined as Vth. Here, the straight line is defined as a tangent at a point where the differential value of the graph of Id ^1/2 -Vgs is maximized. According to the above definition, the threshold voltage Vth is a boundary point between the weak inversion region and the strong inversion region.

  The second signal voltage (V2) corresponding to one gradation belonging to the low gradation region of the representative voltage-luminance characteristic is preferably 0% or more and 10% or less of the maximum gradation that can be displayed in each pixel 100. A voltage corresponding to the gradation is preferable. As a result, the second correction parameter can be calculated in a low gradation range suitable for human visibility.

  The third signal voltage (V3) corresponding to one gradation belonging to the high gradation region of the representative voltage-luminance characteristic is preferably a level that is 20% or more and 100% or less of the maximum gradation that can be displayed in each pixel 100. It is preferable that the voltage corresponds to the tone. As a result, the third correction parameter can be calculated in a high gradation range suitable for human visibility.

  Further, the processing described in Embodiments 1 and 2 is performed for each of red, green, and blue colors emitted from the light emitting element 110. That is, the correction parameter calculation unit 32 obtains first to third correction parameters for each of the red, green, and blue colors. Then, the correction parameter calculation unit 32 outputs the calculated first to third correction parameters for the red, green, and blue colors to the control unit 11, and the correction parameter is stored in the storage unit 13. Let it be written.

  Thereby, it can correct | amend so that a brightness | luminance may become uniform about each color of red, green, and blue.

  Further, in the organic EL display device 1 in which the correction parameters are written in the storage unit 13, the correction unit 12 performs first to first corresponding to each of the plurality of pixels 100 from the storage unit 13 with respect to the video signal input from the outside. The third correction parameter is read, and the signal voltage corresponding to each of the plurality of pixels 100 is corrected. Then, the correction unit 12 outputs the corrected signal voltage to the control unit 11, and the control unit 11 outputs the corrected signal voltage to the display panel 20, thereby displaying an image on the display panel 20.

  For example, the organic EL display device 1 is built in a thin flat TV as shown in FIG. By the manufacturing method of the organic EL display device 1 according to the present invention, a thin flat TV including the organic EL display device 1 capable of reducing the luminance unevenness of the display panel 20 over all gradations with high accuracy is realized.

  INDUSTRIAL APPLICABILITY The present invention is particularly useful for a method for manufacturing an organic EL flat panel display incorporating an organic EL display device, and a method for manufacturing an organic EL display device capable of reducing luminance unevenness of the display panel with high accuracy over all gradations. And so on.

DESCRIPTION OF SYMBOLS 1 Organic EL display apparatus 2 Organic EL display apparatus manufacturing apparatus 10 Control circuit 11 Control part 12 Correction | amendment part 13 Memory | storage part 13a Correction | amendment parameter table 20 Display panel 21 Display part 22 Scan line drive circuit 23 Data line drive circuit 24 Scan line 25 Data line DESCRIPTION OF SYMBOLS 30 Correction parameter determination apparatus 31 Measurement control part 32 Correction parameter calculation part 40 Measurement apparatus 100 Pixel 110 Light emitting element 120 Drive transistor 130 Selection transistor 140 Holding capacity 150,160 Power supply 151 Power supply line 211,221,226 Subtractor 212,213,222 223, 227 Multiplier 214, 224, 229 Comparison selector 215, 225, 228 Adder

Claims (12)

A first step of obtaining a function representing a representative voltage-luminance characteristic common to a display panel including a plurality of pixels including a light emitting element and a driving element that controls supply of a current reflecting the luminance of the light emitting element by an input voltage;
A first signal voltage corresponding to one gradation belonging to the middle gradation region of the representative voltage-luminance characteristic is applied to the driving element included in each of the plurality of pixels, and luminance emitted from the plurality of pixels is increased. A second step of measuring with a measuring device;
A first reference voltage is obtained when the luminance obtained from the representative voltage-luminance characteristic is the luminance when the target pixel, which is a correction target pixel, emits light with the first signal voltage, and the first signal voltage is determined. A third step of obtaining a first correction parameter for the target pixel to obtain the first reference voltage;
Applying a second signal voltage corresponding to one gradation belonging to a low gradation area whose gradation is lower than the intermediate gradation area of the representative voltage-luminance characteristics to a driving element included in the target pixel; A fourth step of measuring the luminance emitted from the target pixel by the measuring device;
A brightness obtained when the target pixel emits light at the second signal voltage is obtained when a first correction voltage obtained by adding the first correction parameter to the second signal voltage is input to the function. A fifth step of obtaining a second correction parameter for the target pixel, which is a coefficient that provides a reference luminance;
Applying a third signal voltage corresponding to one gradation belonging to a high gradation area having a gradation higher than the intermediate gradation area of the representative voltage-luminance characteristics to a driving element included in the target pixel; A sixth step of measuring the luminance emitted from the pixel by the measuring device;
The luminance obtained when the target pixel is caused to emit light at the third signal voltage is obtained when a second correction voltage obtained by adding the first correction parameter to the third signal voltage is input to the function. A seventh step of obtaining a third correction parameter for the target pixel, which is a coefficient that provides a reference luminance;
A method for manufacturing a display device. The first correction parameter is an offset voltage indicating a difference between the first signal voltage and the first reference voltage;
In the fifth step,
Obtaining a second reference voltage obtained by inputting the luminance when the target pixel is caused to emit light at the second signal voltage into the function;
The second correction parameter is a gain indicating a ratio between a voltage difference between the first correction voltage and the first reference voltage and a voltage difference between the second reference voltage and the first reference voltage.
In the seventh step,
Obtaining a third reference voltage obtained by inputting the luminance when the target pixel is caused to emit light at the third signal voltage into the function by calculation;
The third correction parameter is a gain indicating a ratio between a voltage difference between the second correction voltage and the first reference voltage and a voltage difference between the third reference voltage and the first reference voltage. The manufacturing method of the display apparatus of description. The method for manufacturing a display device according to claim 1, wherein the first signal voltage is a gate-source voltage of the drive element at a boundary between a weak inversion region and a strong inversion region in which the drive element operates. 4. The method of manufacturing a display device according to claim 1, wherein the threshold voltage of the driving element is a gate-source voltage of the driving element corresponding to a gradation belonging to the middle gradation range. 5. 5. The method for manufacturing a display device according to claim 1, wherein the second signal voltage is a voltage corresponding to a gradation of 0% or more and 10% or less of a maximum gradation that can be displayed in each pixel. . The method for manufacturing a display device according to claim 1, wherein the third signal voltage is a voltage corresponding to a gradation of 20% to 100% of a maximum gradation that can be displayed in each pixel. . The method for manufacturing a display device according to claim 1, wherein the representative voltage-luminance characteristic is a voltage-luminance characteristic for any one of a plurality of pixels included in the display panel. . The representative voltage-luminance characteristic is a characteristic that is commonly set for the entire display panel including the plurality of pixels, and is an averaged voltage-luminance characteristic of each pixel included in the display panel. Item 7. A method for manufacturing a display device according to any one of Items 1 to 6. The light emitting element included in the pixel emits one of red, green and blue colors,
In the third step, the first correction parameter is obtained for each of the red, green, and blue colors,
In the fifth step, the second correction parameter is obtained for each of the red, green, and blue colors,
The method for manufacturing a display device according to claim 1, wherein in the seventh step, the third correction parameter is obtained for each of the red, green, and blue colors. further,
The first correction parameter obtained in the third step, the second correction parameter obtained in the fifth step, and the third correction parameter obtained in the seventh step are displayed on the display panel. The method for manufacturing a display device according to claim 1, further comprising an eighth step of writing in a predetermined memory to be used. The method for manufacturing a display device according to claim 1, wherein the measurement device is an image sensor. A plurality of pixels including a light-emitting element and a voltage-driven drive element that controls supply of current to the light-emitting element;
A plurality of data lines for supplying a signal voltage to each of the plurality of pixels;
A plurality of scanning lines for supplying a scanning signal to each of the plurality of pixels;
A data line driving circuit for supplying the signal voltage to the plurality of data lines;
A scanning line driving circuit for supplying the scanning signal to the plurality of scanning lines;
A storage unit for storing predetermined correction parameters for each of the plurality of pixels;
A correction unit that reads out the predetermined correction parameter corresponding to each of the plurality of pixels from the storage unit with respect to a video signal input from the outside, and corrects the video signal corresponding to each of the plurality of pixels; With
The predetermined correction parameter is:
A first step of obtaining a function representing a representative voltage-luminance characteristic common to a display panel including a plurality of pixels including a light-emitting element and a voltage-driven drive element that controls supply of current to the light-emitting element;
A first signal voltage corresponding to one gradation belonging to the middle gradation region of the representative voltage-luminance characteristic is applied to the driving element included in each of the plurality of pixels, and luminance emitted from the plurality of pixels is increased. A second step of measuring with a measuring device;
A first reference voltage is obtained when the luminance obtained from the representative voltage-luminance characteristic is the luminance when the target pixel, which is a correction target pixel, emits light with the first signal voltage, and the first signal voltage is determined. A third step of obtaining a first correction parameter for the target pixel to obtain the first reference voltage;
Applying a second signal voltage corresponding to one gradation belonging to a low gradation area whose gradation is lower than the intermediate gradation area of the representative voltage-luminance characteristics to a driving element included in the target pixel; A fourth step of measuring the luminance emitted from the target pixel by the measuring device;
A brightness obtained when the target pixel emits light at the second signal voltage is obtained when a first correction voltage obtained by adding the first correction parameter to the second signal voltage is input to the function. A fifth step of obtaining a second correction parameter for the target pixel, which is a coefficient that provides a reference luminance;
Applying a third signal voltage corresponding to one gradation belonging to a high gradation area having a gradation higher than the intermediate gradation area of the representative voltage-luminance characteristics to a driving element included in the target pixel; A sixth step of measuring the luminance emitted from the pixel by the measuring device;
The luminance obtained when the target pixel is caused to emit light with the third signal voltage is obtained when a second correction voltage obtained by adding the first correction parameter to the third signal voltage is input to the function. And a seventh step for obtaining a third correction parameter for the target pixel, which is a coefficient that gives 2 reference luminances,
The first correction parameter is an offset voltage indicating a difference between the first signal voltage and the first reference voltage;
The second correction parameter is a function representing a voltage difference between the first correction voltage and the first reference voltage, and a luminance when the target pixel emits light with the second signal voltage, representing the representative voltage-luminance characteristic. Is a gain indicating a ratio between a voltage difference between the second reference voltage and the first reference voltage obtained when input to
The third correction parameter is a function representing a voltage difference between the second correction voltage and the first reference voltage, and luminance when the target pixel is caused to emit light with the third signal voltage, representing the representative voltage-luminance characteristics. A display device, which is a gain indicating a ratio of a voltage difference between the third reference voltage and the first reference voltage obtained when input to the display device.

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