WO2018167835A1 - Organic electroluminescence display device - Google Patents

Organic electroluminescence display device Download PDF

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Publication number
WO2018167835A1
WO2018167835A1 PCT/JP2017/010116 JP2017010116W WO2018167835A1 WO 2018167835 A1 WO2018167835 A1 WO 2018167835A1 JP 2017010116 W JP2017010116 W JP 2017010116W WO 2018167835 A1 WO2018167835 A1 WO 2018167835A1
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Prior art keywords
power supply
organic electroluminescence
organic el
voltage
display device
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PCT/JP2017/010116
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French (fr)
Japanese (ja)
Inventor
将紀 小原
野口 登
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シャープ株式会社
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Priority to PCT/JP2017/010116 priority Critical patent/WO2018167835A1/en
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    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09FDISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • G09F9/30Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
    • H05B33/00Electroluminescent light sources
    • H05B33/02Details

Abstract

A pixel circuit 21 is configured to apply a fixed voltage ELVDD to the anode terminals of organic EL elements Lr, Lg, Lb and connect the cathode terminals to the drain terminals of transistors T2r, T2g, T2b, respectively. The pixel circuit applies three types of voltages to the source terminals of the transistors T2r, T2g, T2b, respectively, and connects the gate terminals to one conductor of a transistor T1. The pixel circuit sets a voltage ELVSS_R to low level and voltages ELVSS_G and ELVSS_B to high level, thereby allowing the organic EL elements Lr alone to emit light in a first subframe. The pixel circuit displays a black screen at the beginning of a subframe and performs a correction process for compensating for differences in the luminance due to the differences in the light-emission period of an organic EL element to correct an input video signal.

Description

Organic electroluminescence display device

The present invention relates to a display device, and more particularly to an organic electroluminescence display device.

In recent years, an organic EL display device including a pixel circuit including an organic electroluminescence (Electro-Luminescence: hereinafter referred to as EL) element has been put into practical use. Also, one frame period is divided into a plurality of subframe periods, and in each subframe period, a red subframe based on a red video signal, a green subframe based on a green video signal, a blue subframe based on a blue video signal, etc. 2. Description of the Related Art Field sequential display devices that display in order are known. By combining these technologies, a field sequential organic EL display device can be configured. For the organic EL element, for example, an organic light emitting diode (OLED) is used.

Various pixel circuits have been known for field sequential organic EL display devices. FIG. 17 is a circuit diagram of a pixel circuit of an organic EL display device described in Patent Document 1. When the voltage of the scanning line Si becomes low level in the first subframe period, the transistor T1 is turned on, and the voltage of the data line Dj (voltage corresponding to the red video signal) is written between the gate terminal and the source terminal of the transistor T2. It is. After the transistor T1 is turned off, the voltage of the light emission control line ERi becomes low level for about one subframe period. At this time, the transistor T3r is turned on, and the organic EL element Lr emits red light with a luminance corresponding to the gate-source voltage of the transistor T2. As a result, the red subframe is displayed in the first subframe period. In the same manner, a green subframe is displayed in the second subframe period, and a blue subframe is displayed in the third subframe period.

FIG. 18 is a circuit diagram of a pixel circuit of an organic EL display device described in Patent Document 2. When the voltage of the scanning line Si becomes low level in the first subframe period, the transistor T1 is turned on, and the voltage of the data line Dj (voltage corresponding to the red video signal) is the gate terminal and the source terminal of the transistors T2r, T2g, T2b Written between. After the transistor T1 is turned off, the power supply voltage ELVDD_Ri becomes a high level for about one subframe period, and the organic EL element Lr emits red light with a luminance corresponding to the gate-source voltage of the transistor T2r. At this time, the power supply voltages ELVDD_Gi and ELVDD_Bi are at a low level. As a result, the red subframe is displayed in the first subframe period. In the same manner, a green subframe is displayed in the second subframe period, and a blue subframe is displayed in the third subframe period.

Japanese Unexamined Patent Publication No. 2005-148749 Japanese Laid-Open Patent Publication No. 2005-148751

In the organic EL display device including the pixel circuit shown in FIG. 17, in order to control the transistors T3r, T3g, and T3b in the pixel circuits in each row to the ON state at different timings, light emission control provided for each row of the pixel circuits. A light emission control circuit that controls the voltages of the lines ERi, EGi, and EBi is required. For this reason, in the organic EL display device having the pixel circuit shown in FIG. 17, the circuit scale of the drive circuit becomes large. In addition, although the pixel circuit illustrated in FIG. 17 includes five transistors, it is preferable that the number of transistors in the pixel circuit is smaller.

In the organic EL display device having the pixel circuit shown in FIG. 18, it is necessary to control the power supply voltages ELVDD_Ri, ELVDD_Gi, and ELVDD_Bi supplied to the pixel circuits in each row to a high level at different timings. For this reason, in the organic EL display device including the pixel circuit shown in FIG. 18, the circuit scale of the power supply circuit becomes large.

Therefore, an object of the present invention is to provide a field sequential type organic EL display device having a small circuit scale.

A first aspect of the present invention is a field sequential organic electroluminescence display device,
A plurality of scan lines;
Multiple data lines,
A plurality of pixel circuits arranged corresponding to the intersections of the scanning lines and the data lines;
A scanning line driving circuit for driving the scanning lines;
A data line driving circuit for driving the data line;
A power supply circuit for controlling a plurality of power supply voltages corresponding to a plurality of colors,
The pixel circuit includes:
A plurality of organic electroluminescence elements corresponding to the plurality of colors;
A plurality of drive transistors each connected in series to a corresponding organic electroluminescent element;
A write control transistor having a gate terminal connected to the scan line, a first conduction terminal connected to the data line, and a second conduction terminal connected to gate terminals of the plurality of drive transistors;
The organic electroluminescence element has an anode terminal to which a fixed high-level power supply voltage is applied, and a cathode terminal connected to a drain terminal of a corresponding driving transistor,
A power supply voltage corresponding to the color of the corresponding organic electroluminescence element among the plurality of power supply voltages is applied to the source terminal of the drive transistor,
In each subframe period, the power supply circuit controls a power supply voltage corresponding to a color of the subframe period to a first level at which the organic electroluminescence element can emit light, and the organic electroluminescence element emits another power supply voltage. The second level is not controlled.

According to a second aspect of the present invention, in the first aspect of the present invention,
A display off period is provided for each subframe period,
The scanning line driving circuit applies an on-voltage for turning on the write control transistor to all the scanning lines in a display off period,
The data line driving circuit applies a display off voltage for stopping light emission of the organic electroluminescence element to all the data lines in a display off period.

According to a third aspect of the present invention, in the second aspect of the present invention,
A correction process is performed on the input video signal to compensate for a difference in luminance due to a difference in the length of the light emission period of the organic electroluminescence element, and the corrected video signal is sent to the data line driving circuit. A correction unit for outputting is further provided.

According to a fourth aspect of the present invention, in the third aspect of the present invention,
A characteristic data storage unit for storing the characteristic data of the organic electroluminescence element for each color;
The correction unit performs the correction process using characteristic data stored in the characteristic data storage unit.

According to a fifth aspect of the present invention, in the first aspect of the present invention,
The difference between the high level power supply voltage and the first level voltage is greater than the light emission threshold voltage of the organic electroluminescence element,
A difference between the high level power supply voltage and the second level voltage is smaller than a light emission threshold voltage of the organic electroluminescence element.

A sixth aspect of the present invention is the fifth aspect of the present invention,
The second level voltage is the high level power supply voltage.

According to a seventh aspect of the present invention, in the second aspect of the present invention,
The scanning line driving circuit applies the ON voltage to all the scanning lines according to a first control signal, and sets the OFF voltage at which the write control transistor is turned off to all the scanning lines according to a second control signal. It is characterized by applying.

According to an eighth aspect of the present invention, in the sixth aspect of the present invention,
The scanning line driving circuit has a configuration in which unit circuits are connected in multiple stages,
The unit circuit is
An output terminal connected to the scanning line;
A first transistor that applies the on-voltage to the output terminal according to the first control signal;
And a second transistor for applying the off voltage to the output terminal in accordance with the second control signal.

According to a ninth aspect of the present invention, in the first aspect of the present invention,
A blanket electrode for applying the high-level power supply voltage to the anode terminal of the organic electroluminescence element is further provided.

According to a tenth aspect of the present invention, in the first aspect of the present invention,
The power supply circuit controls first to third power supply voltages;
The pixel circuit includes:
First to third organic electroluminescence elements each having an anode terminal to which the high-level power supply voltage is applied and emitting light in red, green, and blue, respectively;
Connected to the drain terminal connected to the cathode terminal of each of the first to third organic electroluminescence elements, the source terminal to which the first to third power supply voltages are applied, and the other conduction terminal of the write control transistor And first to third driving transistors each having a gate terminal formed thereon.

According to an eleventh aspect of the present invention, in the first aspect of the present invention,
The scanning line driving circuit is formed on the same panel as the pixel circuit.

A twelfth aspect of the present invention is the eleventh aspect of the present invention,
The driving transistor is configured using an oxide semiconductor,
The write control transistor and the transistor included in the scan line driver circuit are formed using low-temperature polysilicon.

According to a thirteenth aspect of the present invention, in the first aspect of the present invention,
A plurality of white data lines;
The pixel circuit includes:
A white organic electroluminescence device corresponding to white,
A white driving transistor connected in series to the white organic electroluminescence element;
A white write control transistor having a gate terminal connected to the scanning line, a first conduction terminal connected to the white data line, and a second conduction terminal connected to the gate terminal of the white drive transistor. Including
The white organic electroluminescence element has an anode terminal to which the high-level power supply voltage is applied, and a cathode terminal connected to a drain terminal of the white driving transistor,
A white power supply voltage is applied to a source terminal of the white driving transistor.

A fourteenth aspect of the present invention is the thirteenth aspect of the present invention,
The power supply circuit controls the white power supply voltage to a level at which the white organic electroluminescence element can emit light in each subframe period.

According to a fifteenth aspect of the present invention, in the thirteenth aspect of the present invention,
The white power supply voltage is a fixed low-level power supply voltage.

According to a sixteenth aspect of the present invention, in the thirteenth aspect of the present invention,
The white organic electroluminescence element emits light in a period in which any of the plurality of organic electroluminescence elements emits light in each subframe period.

A seventeenth aspect of the present invention is the sixteenth aspect of the present invention,
The white organic electroluminescence element emits light with the same luminance in each subframe period.

An eighteenth aspect of the present invention is the sixteenth aspect of the present invention,
The white organic electroluminescent element emits light at the same luminance ratio as the plurality of organic electroluminescent elements in each subframe period.

A nineteenth aspect of the present invention is a field sequential organic electroluminescence display device,
A plurality of scan lines;
Multiple data lines,
A plurality of pixel circuits arranged corresponding to the intersections of the scanning lines and the data lines;
A scanning line driving circuit for driving the scanning lines;
A data line driving circuit for driving the data line;
A power supply circuit for controlling a plurality of power supply voltages corresponding to a plurality of colors,
The pixel circuit includes:
A plurality of organic electroluminescence elements corresponding to the plurality of colors;
A plurality of drive transistors each connected in series to a corresponding organic electroluminescent element;
A write control transistor having a gate terminal connected to the scan line, a first conduction terminal connected to the data line, and a second conduction terminal connected to gate terminals of the plurality of drive transistors;
The organic electroluminescence element has an anode terminal to which a fixed high-level power supply voltage is applied, and a cathode terminal connected to a drain terminal of a corresponding driving transistor,
A power supply voltage corresponding to the color of the corresponding organic electroluminescence element among the plurality of power supply voltages is applied to the source terminal of the drive transistor,
The power supply circuit controls the power supply voltage corresponding to the color of the subframe period to the first level and the other power supply voltage to the second level in each subframe period,
The difference between the high level power supply voltage and the first level voltage is greater than the light emission threshold voltage of the organic electroluminescence element,
A difference between the high level power supply voltage and the second level voltage is smaller than a light emission threshold voltage of the organic electroluminescence element.

According to the first aspect, since the light emission of the organic EL element can be controlled by controlling a plurality of power supply voltages corresponding to a plurality of colors using the power supply circuit, the light emission control transistor in the pixel circuit and the drive circuit The light emission control circuit is not required. Further, the configuration of the power supply circuit is simplified as compared with the case where the power supply voltage supplied to the pixel circuits in each row is controlled. Therefore, it is possible to provide a field sequential type organic EL display device having a small circuit scale.

According to the second aspect, by stopping the light emission of the organic EL element and performing black insertion during the display off period, color breakup can be reduced and display quality can be improved.

According to the third aspect, by performing a correction process that compensates for the difference in luminance due to the difference in the length of the light emission period of the organic EL element, an image can be obtained without using the light emission control transistor and the light emission control circuit. Display with correct brightness.

According to the fourth aspect, it is possible to perform a suitable correction process on the input video signal in consideration of the fact that the characteristics of the organic EL element differ for each color.

According to the fifth aspect, by determining the first and second levels as described above, the light emission of the organic EL element can be controlled without using the light emission control transistor and the light emission control circuit.

According to the sixth aspect, by using the high level power supply voltage as the second level voltage, the type of power supply voltage can be reduced and the configuration of the power supply circuit can be simplified.

According to the seventh aspect, the on-voltage and the off-voltage can be selectively applied to all the scanning lines using the first and second control signals.

According to the eighth aspect, the scan line driving circuit that selectively applies the on-voltage and the off-voltage to all the scan lines by connecting the unit circuits including the first and second transistors in multiple stages is configured. can do.

According to the ninth aspect, a high-level power supply voltage can be easily applied to the anode terminal of the organic EL element included in the pixel circuit using the blanket electrode.

According to the tenth aspect, it is possible to provide a field sequential organic EL display device with a small circuit scale that displays a red subframe, a green subframe, and a blue subframe.

According to the eleventh aspect, the organic EL display device can be miniaturized by forming the pixel circuit and the scanning line driving circuit on the same panel.

According to the twelfth aspect, when the driving transistor, the write control transistor, and the transistor in the scanning line driving circuit are all configured by using an oxide semiconductor, or when these transistors are all configured by low-temperature polysilicon. Compared with, the layout area of the transistor can be reduced.

According to the thirteenth aspect, by providing the white organic EL element, the luminance of the organic EL element in each subframe period can be adjusted. Since the brightness of the organic EL element can be lowered by the amount of light emitted from the white organic EL element, the life of the organic EL element can be extended. Further, by causing the organic EL element and the white organic EL element to emit light in the same period, it is possible to suppress color breakup that occurs on the display screen. Since no white subframe period is provided, these effects can be obtained while maintaining the length of the subframe period.

According to the fourteenth aspect, the effect of the thirteenth aspect can be obtained while performing the same light emission control as that of the organic EL element on the white organic EL element.

According to the fifteenth aspect, the configuration of the power supply circuit can be simplified by fixing the white power supply voltage to the low level power supply voltage.

According to the sixteenth aspect, the effect of the thirteenth aspect can be obtained while causing the white organic EL element to emit light for the same period as the other organic EL elements in each subframe period.

According to the seventeenth aspect, the luminance of the white organic electroluminescence element in each subframe period can be easily obtained.

According to the eighteenth aspect, since the white organic electroluminescent element emits light at the same luminance ratio as the plurality of organic electroluminescent elements in each subframe period, color breakup can be further reduced.

According to the nineteenth aspect, since the light emission of the organic EL element can be controlled by controlling a plurality of power supply voltages corresponding to a plurality of colors using the power supply circuit, the light emission control transistor in the pixel circuit and the drive circuit The light emission control circuit is not required. Further, the configuration of the power supply circuit is simplified as compared with the case where the power supply voltage supplied to the pixel circuits in each row is controlled. Further, by determining the first and second levels as described above, it is possible to control the light emission of the organic EL element without using the light emission control transistor and the light emission control circuit. Therefore, it is possible to provide a field sequential type organic EL display device having a small circuit scale.

1 is a block diagram illustrating a configuration of an organic EL display device according to a first embodiment of the present invention. FIG. 2 is a circuit diagram of a pixel circuit of the organic EL display device shown in FIG. 1. It is a timing chart of the organic electroluminescence display shown in FIG. It is a block diagram which shows the structure of the scanning line drive circuit of the organic electroluminescence display shown in FIG. FIG. 5 is a circuit diagram of a unit circuit of the scanning line driving circuit shown in FIG. 4. 5 is a timing chart of the scanning line driving circuit shown in FIG. FIG. 3 is a diagram showing voltage-luminance characteristics of the organic EL element of the pixel circuit shown in FIG. FIG. 3 is a diagram showing voltage distribution in the pixel circuit shown in FIG. 2. It is a figure for demonstrating the effect of the organic electroluminescent display apparatus shown in FIG. FIG. 3 is a diagram schematically showing the layout of the pixel circuit shown in FIG. 2. It is a figure which shows typically the layout of the pixel circuit which concerns on a comparative example. It is a figure which shows a mode that metal wiring is formed with a metal vapor deposition method. It is a block diagram which shows the structure of the organic electroluminescence display which concerns on the 3rd Embodiment of this invention. FIG. 14 is a circuit diagram of a pixel circuit of the organic EL display device shown in FIG. 13. 14 is a timing chart of the organic EL display device shown in FIG. It is a figure which shows the brightness | luminance of the white organic EL element in the organic EL display apparatus shown in FIG. It is a circuit diagram of a pixel circuit of a conventional organic EL display device. It is a circuit diagram of a pixel circuit of a conventional organic EL display device.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of an organic EL display device according to the first embodiment of the present invention. An organic EL display device 10 shown in FIG. 1 includes an organic EL panel 11, a display control circuit 12, a scanning line driving circuit 13, a data line driving circuit 14, a power supply circuit 15, a correction unit 16, and a characteristic data storage unit 17. This is a field sequential type organic EL display device. In the organic EL display device 10, one frame period is divided into first to third subframe periods. The organic EL display device 10 displays a red subframe based on the red video signal in the first subframe period, displays a green subframe based on the green video signal in the second subframe period, and blue in the third subframe period. A blue subframe is displayed based on the video signal. Thereby, the organic EL display device 10 performs color display. Hereinafter, m and n are integers of 2 or more, i is an integer of 1 to n, and j is an integer of 1 to m.

The organic EL panel 11 includes n scanning lines S1 to Sn, m data lines D1 to Dm, (m × n) pixel circuits 21, and a blanket electrode 22. The scanning lines S1 to Sn are arranged in parallel to each other. The data lines D1 to Dm are arranged in parallel to each other so as to be orthogonal to the scanning lines S1 to Sn. The scanning lines S1 to Sn and the data lines D1 to Dm intersect at (m × n) locations. The (m × n) pixel circuits 21 are arranged corresponding to the intersections of the scanning lines S1 to Sn and the data lines D1 to Dm. The pixel circuit 21 includes an organic EL element that emits red light, an organic EL element that emits green light, and an organic EL element that emits blue light, and functions as a pixel that displays red, green, and blue in a time-sharing manner. . The blanket electrode 22 is provided corresponding to the entire arrangement region of the pixel circuit 21.

The display control circuit 12 outputs control signals C1 to C3 to the scanning line driving circuit 13, the data line driving circuit 14, and the power supply circuit 15, respectively. Further, the display control circuit 12 outputs the video signal X1 supplied from the outside of the organic EL display device 10 to the correction unit 16. The characteristic data storage unit 17 stores characteristic data required for the correction process in the correction unit 16. The correction unit 16 performs correction processing (details will be described later) on the video signal X1 output from the display control circuit 12 using the characteristic data stored in the characteristic data storage unit 17, and the corrected video signal X2 Is output to the data line driving circuit 14.

The scanning line driving circuit 13 drives the scanning lines S1 to Sn based on the control signal C1. The data line driving circuit 14 drives the data lines D1 to Dm based on the control signal C2 and the corrected video signal X2. The power supply circuit 15 outputs a fixed high-level power supply voltage ELVDD to the blanket electrode 22, and controls three types of power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B supplied to the pixel circuit 21 based on the control signal C3 ( Details will be described later). The level when the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B are at the high level is equal to the level of the high level power supply voltage ELVDD. The scanning line driving circuit 13 is formed on the same organic EL panel 11 as the pixel circuit 21 (gate driver monolithic configuration).

FIG. 2 is a circuit diagram of the pixel circuit 21 in the i-th row and j-th column. The pixel circuit 21 includes transistors T1, T2r, T2g, T2b, capacitors Cr, Cg, Cb, and organic EL elements Lr, Lg, Lb. The organic EL elements Lr, Lg, and Lb are realized by organic light emitting layers that emit red, green, and blue, respectively. The transistors T1, T2r, T2g, and T2b are N-channel thin film transistors (Thin-Film-Transistors: TFTs). The transistors T1, T2r, T2g, and T2b are configured using, for example, an oxide semiconductor such as indium gallium zinc oxide (IGZO), amorphous silicon, microcrystalline silicon, low-temperature polysilicon, single crystal silicon, or the like. Is done.

The anode terminals of the organic EL elements Lr, Lg, and Lb are connected to the blanket electrode 22. A fixed high-level power supply voltage ELVDD is applied to the anode terminals of the organic EL elements Lr, Lg, and Lb. The cathode terminals of the organic EL elements Lr, Lg, and Lb are connected to the drain terminals of the transistors T2r, T2g, and T2b, respectively. Variable power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B output from the power supply circuit 15 are applied to the source terminals of the transistors T2r, T2g, and T2b, respectively. Capacitors Cr, Cg, and Cb are provided between the gate terminals and the source terminals of the transistors T2r, T2g, and T2b, respectively. The gate terminal of the transistor T1 is connected to the scanning line Si. One conduction terminal (the left terminal in FIG. 2) of the transistor T1 is connected to the data line Dj. The other conduction terminal of the transistor T1 is connected to the gate terminals of the transistors T2r, T2g, and T2b. Hereinafter, a node to which a gate terminal such as the transistor T2r is connected is referred to as Na.

While the voltage of the scanning line Si is at a high level, the transistor T1 is turned on, and the voltage of the data line Dj is applied to the node Na. When the voltage of the scanning line Si becomes low level, the transistor T1 is turned off. After the transistor T1 is turned off, the node Na enters a floating state, and the gate-source voltages of the transistors T2r, T2g, and T2b are held in the capacitors Cr, Cg, and Cb, respectively. The drive current flowing through the transistor T2r and the organic EL element Lr changes according to the gate-source voltage of the transistor T2r. The organic EL element Lr emits light with a luminance corresponding to the drive current. The same applies to the organic EL elements Lg and Lb. The transistor T1 functions as a write control transistor, and the transistors T2r, T2g, and T2b function as drive transistors.

FIG. 3 is a timing chart of the organic EL display device 10. In FIG. 3, EMR1 to EMRn indicate the light emission periods of the organic EL elements Lr in the pixel circuits 21 in the 1st to nth rows, respectively. EMG1 to EMGn indicate light emission periods of the organic EL elements Lg in the pixel circuits 21 in the 1st to nth rows, respectively. EMB1 to EMBn indicate light emission periods of the organic EL elements Lb in the pixel circuits 21 in the 1st to nth rows, respectively.

A black display period is provided at the beginning of each subframe period. The black display period corresponds to the display off period. In the black display period, the voltages of the scanning lines S1 to Sn and the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B are controlled to a high level, and the voltage VZ for black display is applied to the data lines D1 to Dm. Therefore, in all the pixel circuits 21, the transistor T1 is turned on, and the voltage VZ is applied to the node Na via the transistor T1. At this time, since the drive current does not flow through the transistors T2r, T2g, and T2b, the organic EL elements Lr, Lg, and Lb do not emit light. Therefore, a black screen is displayed during the black display period. The organic EL elements Lr, Lg, and Lb in the i-th pixel circuit 21 do not emit light until the i-th line period of the first to third subframe periods, respectively.

In the first subframe period, the power supply circuit 15 controls the power supply voltage ELVSS_R to a low level and controls the power supply voltages ELVSS_G and ELVSS_B to a high level. In the first subframe period, the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B are controlled so as to satisfy the following expressions (1) to (3).
ELVDD−ELVSS_R >> Vth_R (1)
ELVDD−ELVSS_G << Vth_G (2)
ELVDD−ELVSS_B << Vth_B (3)
However, Vth_R, Vth_G, and Vth_B are emission threshold voltages of the organic EL elements Lr, Lg, and Lb, respectively, where the symbol >> indicates that it is sufficiently large and the symbol << indicates that it is sufficiently small.

In the i-th line period of the first subframe period, the pixel circuit 21 in the i-th row is selected, and writing to the pixel circuit 21 in the i-th row is performed. More specifically, when the voltage of the scanning line Si changes to a high level at the start of the i-th line period, the transistor T1 is turned on, and the voltage of the data line Dj (according to the red video signal is applied to the node Na via the transistor T1). Voltage) is applied. When the voltage of the scanning line Si changes to low level at the end of the i-th line period, the transistor T1 is turned off. Thereafter, the gate-source voltages of the transistors T2r, T2g, and T2b are held in the capacitors Cr, Cg, and Cb, respectively. Since Expressions (1) to (3) are established in the first subframe period, a drive current corresponding to the gate-source voltage of the transistor T2r and the threshold voltage flows through the transistor T2r and the organic EL element Lr. The organic EL element Lr emits red light at a luminance corresponding to the drive current until the power supply voltage ELVSS_R changes to high level at the end of the first subframe period after writing is performed (EMR1 to EMRn in FIG. 3). See). The organic EL elements Lg and Lb do not emit light in the first subframe period.

In the second subframe period, the power supply circuit 15 controls the power supply voltage ELVSS_G to a low level and controls the power supply voltages ELVSS_R and ELVSS_B to a high level. In the second subframe period, the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B are controlled so as to satisfy the following expressions (4) to (6).
ELVDD−ELVSS_R << Vth_R (4)
ELVDD−ELVSS_G >> Vth_G (5)
ELVDD−ELVSS_B << Vth_B (6)

In the i-th line period of the second subframe period, the pixel circuit 21 in the i-th row is selected, and writing to the pixel circuit 21 in the i-th row is performed. However, the voltage of the data line Dj is a voltage corresponding to the green video signal. Since Expressions (4) to (6) are established in the second subframe period, a drive current corresponding to the gate-source voltage of the transistor T2g and the threshold voltage flows through the transistor T2g and the organic EL element Lg. The organic EL element Lg emits green light at a luminance corresponding to the drive current until the power supply voltage ELVSS_G changes to high level at the end of the second subframe period after writing is performed (EMG1 to EMGn in FIG. 3). See). The organic EL elements Lr and Lb do not emit light in the second subframe period.

In the third subframe period, the power supply circuit 15 controls the power supply voltage ELVSS_B to a low level and controls the power supply voltages ELVSS_R and ELVSS_G to a high level. In the third subframe period, the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B are controlled so as to satisfy the following expressions (7) to (9).
ELVDD−ELVSS_R << Vth_R (7)
ELVDD−ELVSS_G << Vth_G (8)
ELVDD−ELVSS_B >> Vth_B (9)

In the i-th line period of the third subframe period, the pixel circuit 21 in the i-th row is selected, and writing to the pixel circuit 21 in the i-th row is performed. However, the voltage of the data line Dj is a voltage corresponding to the blue video signal. Since Expressions (7) to (9) are established in the third subframe period, a driving current corresponding to the gate-source voltage of the transistor T2b and the threshold voltage flows through the transistor T2b and the organic EL element Lb. The organic EL element Lb emits blue light with a luminance corresponding to the drive current until the power supply voltage ELVSS_B changes to high level at the end of the third subframe period after writing is performed (EMB1 to EMBn in FIG. 3). See). The organic EL elements Lr and Lg do not emit light in the third subframe period.

FIG. 4 is a block diagram showing the configuration of the scanning line driving circuit 13. The scanning line driving circuit 13 has a configuration in which n unit circuits 31 are connected in multiple stages. Hereinafter, the i-th unit circuit 31 is referred to as SRi. The unit circuit 31 has a clock terminal CK, an all-on control terminal AON, a clear terminal CLR, a set terminal S, a reset terminal R, and an output terminal Q. The control signal C1 output from the display control circuit 12 to the scanning line driving circuit 13 includes two-phase clock signals CK1 and CK2, an all-on control signal ALL_ON, a clear signal CLEAR, a gate start pulse GSP, and a gate end pulse GEP. Is included. The scanning line driving circuit 13 outputs n output signals Q1 to Qn based on these signals. The output signals Q1 to Qn of the scanning line driving circuit 13 are applied to the scanning lines S1 to Sn, respectively.

The all-on control signal ALL_ON and the clear signal CLEAR are respectively supplied to the all-on control terminal AON and the clear terminal CLR of the unit circuit 31 in each stage. The clock signal CK1 is supplied to the clock terminal CK of the odd-numbered unit circuit 31. The clock signal CK2 is supplied to the clock terminal CK of the even-numbered unit circuit 31. The gate start pulse GSP is supplied to the set terminal S of the first stage unit circuit SR1. The output signal of the previous unit circuit 31 is supplied to the set terminals S of the second to nth unit circuits 31. The gate end pulse GEP is supplied to the reset terminal R of the n-th unit circuit SRn. The output signal of the next stage unit circuit 31 is supplied to the reset terminal R of the 1st to (n−1) th stage unit circuit 31.

FIG. 5 is a circuit diagram of the unit circuit 31. The unit circuit 31 includes transistors T11 to T16. The transistors T11 to T16 are N-channel TFTs. Similar to the transistors in the pixel circuit 21, the transistors T11 to T16 are configured using, for example, an oxide semiconductor such as IGZO, amorphous silicon, microcrystalline silicon, low-temperature polysilicon, single crystal silicon, or the like.

The drain terminal and the gate terminal of the transistor T11 are connected to the set terminal S. The source terminal of the transistor T11 and the drain terminal of the transistor T15 are connected to the gate terminal of the transistor T12 (hereinafter, the node to which the gate terminal of the transistor T12 is connected is referred to as Nb). The drain terminal of the transistor T12 is connected to the clock terminal CK. A high level power supply voltage DC is applied to the drain terminal of the transistor T13. The source terminals of the transistors T12 and T13 and the drain terminals of the transistors T14 and T16 are connected to the output terminal Q. A low level power supply voltage VSS is applied to the source terminals of the transistors T14 to T16. The gate terminal of the transistor T13 is connected to the all-on control terminal AON. The gate terminals of the transistors T14 and T15 are connected to the reset terminal R. The gate terminal of the transistor T16 is connected to the clear terminal CLR. A parasitic capacitance Cgd exists between the gate terminal and the drain terminal of the transistor T12, and a parasitic capacitance Cgs exists between the gate terminal and the source terminal of the transistor T12. Note that the high level power supply voltage DC and the low level power supply voltage VSS supplied to the scanning line driving circuit 13 are the high level power supply voltage ELVDD supplied to the organic EL panel 11 and the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B. Is generally different.

FIG. 6 is a timing chart of the scanning line driving circuit 13. The clock signal CK1 is a signal that becomes high level and low level for a predetermined time. The clock signal CK2 is an inverted signal of the clock signal CK1. The all-on control signal ALL_ON becomes high level during the black display period. The gate start pulse GSP and the clear signal CLEAR are at a high level for a half cycle of the clock signal CK1 after the black display period. The gate end pulse GEP becomes high level for a half cycle of the clock signal CK1 before the black display period.

全 At the start of the black display period, the all-on control signal ALL_ON changes to high level. As a result, the transistor T13 is turned on in all the unit circuits 31, and the output signals Q1 to Qn become high level. At the end of the black display period, the all-on control signal ALL_ON changes to a low level, and the clear signal CLEAR changes to a high level. Accordingly, in all the unit circuits 31, the transistor T13 is turned off, the transistor T16 is turned on, and the output signals Q1 to Qn become low level.

Also, at the end of the black display period, the gate start pulse GSP changes to high level. Accordingly, in the unit circuit SR1 at the first stage, the transistor T11 is turned on, the voltage of the node Nb is changed to a high level, and the transistor T12 is turned on. At this time, since the clock signal CK1 is at a low level, the output signal Q1 is at a low level.

The gate start pulse GSP changes to a low level at the start of the first line period. Accordingly, in the unit circuit SR1 at the first stage, the transistor T11 is turned off and the node Nb is in a floating state. At the start of the first line period, the clock signal CK1 changes to a high level. As a result, the output signal Q1 of the first stage unit circuit SR1 becomes high level. At this time, the voltage of the node Nb becomes higher than the normal high level by the action of the parasitic capacitances Cgd and Cgs (see SR1_Nb in FIG. 6). Accordingly, the high level of the output signal Q1 is the same level as the high level of the clock signal CK1 without being lowered by the threshold voltage of the transistor T12.

The clock signal CK1 changes to low level at the end of the first line period. Accordingly, the output signal Q1 of the unit circuit SR1 at the first stage becomes low level. In the second line period, the output signal Q2 of the second stage unit circuit SR2 is at a high level. The output signal Q2 of the second stage unit circuit 31 is input to the reset terminal R of the first stage unit circuit 31. Therefore, when the output signal Q2 of the second stage unit circuit 31 becomes high level, the transistors T14 and T15 are turned on in the first stage unit circuit 31. When the transistor T15 is turned on, the voltage of the node Nb changes to a low level. When the transistor T14 is turned on, the output signal Q1 quickly changes to a low level. Thus, in the first line period, the output signal Q1 of the unit circuit SR1 at the first stage becomes high level. Similarly, in the 2nd to nth line periods, the output signals Q2 to Qn of the 2nd to nth stage unit circuits 31 are at a high level, respectively.

At the end of the nth line period, the gate end pulse GEP changes to high level. Accordingly, in the unit circuit SRn at the n-th stage, the transistors T14 and T15 are turned on, the voltage at the node Nb changes to the low level, and the output signal Qn quickly changes to the low level. The gate end pulse GEP changes to a low level at the start of the black display period. Accordingly, the transistors T14 and T15 are turned off in the n-th unit circuit SRn.

In this manner, the scanning line driving circuit 13 is supplied with the clock signals CK1 and CK2, the all-on control signal ALL_ON, the clear signal CLEAR, the gate start pulse GSP, and the gate end pulse GEP shown in FIG. The lines S1 to Sn can be driven at the timing shown in FIG.

Hereinafter, the correction unit 16 will be described. As shown in FIG. 3, in the organic EL display device 10, the length of the light emission period of the organic EL elements Lr, Lg, and Lb is different for each row of the pixel circuits 21. The luminance of the organic EL elements Lr, Lg, and Lb is proportional to the length of the light emission period. For this reason, when the data lines D1 to Dm are driven using the video signal X1 supplied from the outside, the brightness of the display screen is bright at the portion corresponding to the previously selected scanning line (upper part of the display screen in the drawing). Therefore, the portion corresponding to the scanning line selected later becomes dark. Accordingly, the correction unit 16 performs a correction process on the video signal X1 to compensate for the difference in luminance due to the difference in the length of the light emission periods of the organic EL elements Lr, Lg, and Lb. The video signal X2 is obtained.

Before performing the correction process, in the inspection process of the organic EL display device 10, the voltage-luminance characteristics of the organic EL elements Lr, Lg, and Lb are obtained by the following method. First, after controlling the organic EL elements Lg and Lb to a non-light emitting state, the voltage applied to the organic EL element Lr is switched stepwise from the minimum value to the maximum value, and the organic EL panel 11 when each voltage is applied. Measure the brightness. Based on the measurement result of the luminance, the voltage-luminance characteristic when the organic EL element Lr emits light continuously in one subframe period in one frame period is obtained. Thereby, for example, the voltage-luminance characteristics shown in FIG. 7 are obtained for the organic EL element Lr. In the same manner, the voltage-luminance characteristics when the organic EL elements Lg and Lb emit light continuously in one subframe period in one frame period are obtained. The characteristic data storage unit 17 stores the obtained three types of voltage-luminance characteristics.

Assume that the red component of the gradation data of the pixel in the i-th row and j-th column included in the video signal X1 is Xr, the green component is Xg, and the blue component is Xb. The correcting unit 16 obtains a corrected red component Xr ′ based on the red component Xr by the following method. First, the correction unit 16 obtains a voltage Vr corresponding to the red component Xr. Next, the correction unit 16 obtains the luminance Yr corresponding to the voltage Vr using the voltage-luminance characteristics of the organic EL element Lr stored in the characteristic data storage unit 17. Next, the correction unit 16 obtains a corrected luminance (Ki × Yr) by multiplying the luminance Yr by a coefficient Ki shown in the following equation (10).
Ki = Len_F / Len_EMRi (10)
However, in Expression (10), Len_F represents the length of one subframe period, and Len_EMRi represents the length of the light emission period of the organic EL element Lr in the pixel circuit 21 in the i-th row.

Next, the correction unit 16 obtains a corrected voltage Vr ′ corresponding to the corrected luminance (Ki × Yr) using the voltage-luminance characteristics of the organic EL element Lr stored in the characteristic data storage unit 17. (See FIG. 7). Next, the correcting unit 16 obtains a corrected red component Xr ′ corresponding to the corrected voltage Vr ′.

The correction unit 16 obtains the corrected green component Xg ′ based on the green component Xg and the corrected blue component Xb ′ based on the blue component Xb by the same method. When obtaining the corrected green component Xg ′, the voltage-luminance characteristic of the organic EL element Lg stored in the characteristic data storage unit 17 is used. When obtaining the corrected blue component Xb ′, the characteristic data storage unit 17 stores the corrected green component Xg ′. The stored voltage-luminance characteristics of the organic EL element Lb are used. The correction unit 16 corrects the corrected video signal including the corrected red component Xr ′, the corrected green component Xg ′, and the corrected blue component Xb ′ as the gradation data of the pixel in the i-th row and j-th column. X2 is output.

In this way, the correction unit 16 performs a correction process that compensates for the difference in luminance caused by the difference in the length of the light emission periods of the organic EL elements Lr, Lg, and Lb, so that the light emission control transistor and the light emission control circuit are not used. The image can be displayed with the correct brightness.

Hereinafter, the setting method of the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B will be described in detail with reference to FIG. In the following description, the organic EL element Lc is any one of the organic EL elements Lr, Lg, and Lb, and the transistor T2c is a transistor connected to the anode terminal of the organic EL element Lc (any one of the transistors T2r, T2g, and T2b). The power supply voltage ELVSS_C is a power supply voltage (any one of the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B) applied to the source terminal of the transistor T2c.

The condition for the organic EL element Lc to emit light is given by the following formula (11).
ELVDD−ELVSS_C ≧ Vth_C + VDS (11)
In Equation (11), Vth_C represents the light emission threshold voltage of the organic EL element Lc, and VDS represents the drain-source voltage when the transistor T2c operates in the saturation region. From the equation (11), the following equation (12) is derived. Expression (12) represents a condition that the power supply voltage ELVSS_C should satisfy when the organic EL element Lc emits light.
ELVSS_C ≦ ELVDD− (Vth_C + VDS) (12)

The high level power supply voltage ELVDD is a fixed voltage. If the voltage VDS is a parameter determined by the device characteristics of the transistor T2c, the power supply voltage ELVSS_C when the organic EL element Lc does not emit light can be adjusted using (VDS + ΔV) on the right side of the equation (12). The light emission threshold voltage Vth_C and the voltage VDS can be obtained based on the current-voltage characteristics of the organic EL element Lc and the transistor T2c.

When the power supply voltage ELVSS_C when the organic EL element Lr does not emit light is ELVSS_off and the power supply voltage ELVSS_C when the organic EL element Lr emits light is ELVSS_on, the following expression (13) is established.
ELVSS_off ≧ ELVSS_on + VDS + ΔV (13)
In order to selectively bring the organic EL element Lc into a non-light emitting state within one subframe period, the voltage ELVSS_off is set higher than the voltage ELVSS_on by (VDS + ΔV) or more. However, the upper limit of the voltage ΔV is the threshold voltage Vth_C. The power supply circuit 15 applies the voltage ELVSS_on to the source terminal of the transistor T2c during the subframe period in which the organic EL element Lc emits light, and applies the voltage ELVSS_off to the source terminal of the transistor T2c in the subframe period during which the organic EL element Lc does not emit light. . Thereby, the organic EL elements Lr, Lg, and Lb can emit light at a desired timing.

Hereinafter, effects of the organic EL display device 10 according to the present embodiment will be described. In the following description, the organic EL display device having the pixel circuit shown in FIG. 17 is the first conventional organic EL display device, and the organic EL display device having the pixel circuit shown in FIG. 18 is the second conventional organic EL. It is called a display device.

The organic EL display device 10 has an effect that the circuit scale can be reduced as compared with the conventional organic EL display device. As described above, the first conventional organic EL display device requires a light emission control circuit that controls the voltages of the light emission control lines ERi, EGi, and EBi. For example, when each stage of the light emission control circuit that controls one light emission control line is configured by six transistors, the total number of transistors in the light emission control circuit is 18n. The organic EL display device 10 does not require a light emission control circuit. Therefore, according to the organic EL display device 10, the frame of the organic EL panel 11 (periphery of the arrangement area of the pixel circuit 21) can be narrowed by the light emission control circuit.

Further, the pixel circuit shown in FIG. 17 includes five transistors, whereas the pixel circuit 21 of the organic EL display device 10 includes only four transistors. Therefore, according to the organic EL display device 10, the area of the transistor in the pixel circuit can be reduced by 20% as compared with the first conventional organic EL display device. In addition, since the number of transistors is small, wirings and contacts connected to the transistors are also reduced. Therefore, according to the organic EL display device 10, the area of the wiring and the contact can be reduced as compared with the first conventional organic EL display device.

In the second conventional organic EL display device, in order to control the power supply voltages ELVDD_Ri, ELVDD_Gi, and ELVDD_Bi supplied to the pixel circuits in each row, a power supply circuit having a complicated configuration is required. In the organic EL display device 10, the light emission of the organic EL elements Lr, Lg, and Lb can be controlled by controlling the three types of power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B by using the power supply circuit 15. Therefore, the configuration of the power supply circuit is simple. Become. Therefore, according to the organic EL display device 10, the circuit scale of the power supply circuit can be reduced as compared with the second conventional organic EL display device.

In the pixel circuit 21 of the organic EL display device 10, the low-level power supply voltage ELVSS is applied to the source terminal of the drive transistor. For this reason, the organic EL display device 10 also has an effect of high display quality. When the N-channel driving transistor T2c is used, a pixel circuit having the configuration shown in FIG. In the circuit configuration shown in FIG. 9A, the high-level power supply voltage ELVDD is applied to the drain terminal of the drive transistor T2c, the source terminal of the drive transistor T2c is connected to the anode terminal of the organic EL element Lc, and A low level power supply voltage ELVSS is applied to the cathode terminal.

The drive current Ids flowing through the transistor T2c and the organic EL element Lc changes according to the gate-source voltage Vgs of the transistor T2c (generally proportional to the square of the voltage Vgs). In the circuit configuration shown in FIG. 9A, the source terminal of the transistor T2c is connected to the anode terminal of the organic EL element Lc. For this reason, when the characteristics of the organic EL element Lc vary, the source voltage of the transistor T2c also varies. As a result, variations occur in the gate-source voltage Vgs of the transistor T2c and also in the drive current Ids flowing through the organic EL element Lc. For this reason, in the organic EL display device adopting the configuration shown in FIG. 9A, the display screen may vary in luminance.

The pixel circuit 21 of the organic EL display device 10 has a configuration shown in FIG. In the circuit configuration shown in FIG. 9B, the high-level power supply voltage ELVDD is applied to the anode terminal of the organic EL element Lc, the cathode terminal of the organic EL element Lc is connected to the drain terminal of the drive transistor T2c, A low level power supply voltage ELVSS is applied to the source terminal. For this reason, even if the characteristics of the organic EL element Lc vary, the source voltage of the transistor T2c does not vary. There is no variation in the gate-source voltage Vgs of the transistor T2c and the drive current Ids flowing through the organic EL element Lc. Therefore, according to the organic EL display device 10 adopting the configuration shown in FIG. 9B, it is possible to suppress variations in luminance in the display screen and to improve display quality.

The organic EL display device 10 also has an effect that power supply lines for supplying power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B can be easily formed. FIG. 10 is a diagram schematically showing the layout of the pixel circuit 21 of the organic EL display device 10. FIG. 11 is a diagram schematically illustrating a layout of a pixel circuit according to a comparative example. In the pixel circuit according to the comparative example, the transistors T1 and T2 in the pixel circuit illustrated in FIG. 17 are N-channel type, the transistors T3r, T3g, and T3b are deleted, and the cathode terminals of the organic EL elements Lr, Lg, and Lb are respectively connected. The power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B are applied.

In a general manufacturing process of an organic EL panel, an organic layer forming process is provided after the TFT forming process, and then a metal layer forming process is provided. The power supply wiring for supplying the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B is formed in the metal layer forming process. Although a metal vapor deposition method is performed in the metal layer forming step, fine processing cannot be performed by the metal vapor deposition method.

FIG. 12 is a diagram showing a state in which metal wiring is formed using a metal vapor deposition method. In the metal vapor deposition method, the metal of the wiring material is heated and vaporized. The vaporized metal is ejected from the nozzle 41 and passes through the opening 43 formed in the metal mask 42 and collides with the panel substrate 44. As a result, metal wiring 45 is formed on the panel substrate 44. The minimum width of the pattern of the opening 43 that can be formed in the metal mask 42 is, for example, about 10 μm. Since a space having the same width is required between the openings 43, the minimum interval between the wirings 45 that can be formed is 20 μm.

In the manufacturing process of the organic EL panel 11 of the organic EL display device 10, the power supply wiring for supplying the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B is formed in the TFT forming process. In the TFT formation step, wiring can be formed at intervals of about 2 to 10 μm using photolithography and etching. Therefore, even when the high-definition organic EL panel 11 is manufactured, the power supply wiring for supplying the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B can be easily formed. Further, the sheet resistance of the metal wiring formed in the TFT forming process is smaller than the sheet resistance of the metal wiring formed in the metal layer forming process. Therefore, according to the organic EL display device 10, it is possible to reduce the resistance of the power supply wiring that supplies the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B.

As described above, the organic EL display device 10 according to this embodiment includes the plurality of scanning lines S1 to Sn, the plurality of data lines D1 to Dm, the plurality of pixel circuits 21, the scanning line driving circuit 13, A data line driving circuit 14 and a power supply circuit 15 that controls a plurality of power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B corresponding to a plurality of colors (red, green, and blue) are provided. The pixel circuit 21 includes a plurality of organic EL elements Lr, Lg, Lb corresponding to a plurality of colors, a plurality of driving transistors T2r, T2g, T2b connected in series to the corresponding organic EL elements, and a scanning line Si. , A first conduction terminal (left conduction terminal in FIG. 2) connected to the data line Dj, and a second conduction terminal connected to the gate terminals of the plurality of drive transistors T2r, T2g, and T2b. And a write control transistor T1. The organic EL element has an anode terminal to which a fixed high-level power supply voltage ELVDD is applied, and a cathode terminal connected to the drain terminal of the corresponding drive transistor, and the source terminal of the drive transistor has a plurality of power supply voltages. Among these, the power supply voltage corresponding to the color of the corresponding organic EL element is applied. In each subframe period, the power supply circuit 15 sets the power supply voltage corresponding to the color of the subframe period to a first level at which the organic EL element can emit light (a level satisfying the formula (1), (5), or (9)). The other power supply voltage is controlled to a second level at which the organic EL element does not emit light (a level satisfying equations (2) to (4) or (6) to (8)).

In the organic EL display device 10, the light emission of the organic EL elements Lr, Lg, and Lb can be controlled by controlling a plurality of power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B corresponding to a plurality of colors using the power supply circuit 15. The light emission control transistor 21 and the light emission control circuit in the drive circuit are not necessary. Further, the configuration of the power supply circuit 15 is simplified as compared with the case of controlling the power supply voltage supplied to the pixel circuits in each row. Therefore, according to the organic EL display device 10 according to the present embodiment, it is possible to provide a field sequential type organic EL display device with a small circuit scale.

In the organic EL display device 10, a display off period (black display period) is provided for each subframe period. The scanning line driving circuit 13 applies an on-voltage (high level power supply voltage DC) that turns on the write control transistor T1 to all the scanning lines S1 to Sn in the display off period, and the data line driving circuit 14 displays the display. In the off period, a display off voltage (voltage VZ for black display) for stopping the light emission of the organic EL elements Lr, Lg, and Lb is applied to all the data lines D1 to Dm. Thus, by stopping the light emission of the organic EL elements Lr, Lg, and Lb during the display off period and performing black insertion, color breakup can be reduced and display quality can be improved.

Further, the organic EL display device 10 corrects the input video signal (video signal X1) to compensate for the difference in luminance caused by the difference in the length of the light emission periods of the organic EL elements Lr, Lg, and Lb. And a correction unit 16 that outputs the corrected video signal X2 to the data line driving circuit 14 is provided. By performing such correction processing, an image can be displayed with correct luminance without providing the light emission control transistor in the pixel circuit 21. The organic EL display device 10 includes a characteristic data storage unit 17 that stores the characteristic data of the organic EL elements Lr, Lg, and Lb for each color. The correction unit 16 stores the characteristic data stored in the characteristic data storage unit 17. Is used to perform correction processing. Therefore, it is possible to perform a suitable correction process on the input video signal in consideration of the fact that the characteristics of the organic EL elements Lr, Lg, and Lb differ for each color.

The difference between the high level power supply voltage ELVDD and the first level voltage is larger than the light emission threshold voltage of the organic EL element, and the difference between the high level power supply voltage ELVDD and the second level voltage is the light emission threshold voltage of the organic EL element. (Equations (1) to (9)). By determining the first and second levels in this way, the light emission of the organic EL elements Lr, Lg, and Lb can be controlled without using the light emission control transistor and the light emission control circuit. The second level voltage is a high level power supply voltage (a high level such as ELVSS_R is equal to ELVDD). Thereby, the kind of power supply voltage can be reduced and the structure of the power supply circuit 15 can be simplified.

Further, the scanning line driving circuit 13 applies an ON voltage to all the scanning lines S1 to Sn according to the first control signal (all-on control signal AON), and performs all scanning according to the second control signal (clear signal CLR). An off voltage (low level power supply voltage VSS) that turns off the write control transistor T1 is applied to the lines S1 to Sn. Therefore, the on-voltage and the off-voltage can be selectively applied to all the scanning lines S1 to Sn using the first and second control signals. The scanning line driving circuit 13 has a configuration in which unit circuits 31 are connected in multiple stages. The unit circuit 31 applies an ON voltage to the output terminal Q connected to the scanning line Si and the output terminal Q according to the first control signal. A first transistor T13 to be applied and a second transistor T16 to apply an off voltage to the output terminal Q in accordance with the second control signal are included. By connecting the unit circuits 31 including the first and second transistors T13 and T16 in multiple stages, the scanning line driving circuit 13 for selectively applying the on voltage and the off voltage to all the scanning lines S1 to Sn is configured. be able to. The organic EL display device 10 further includes a blanket electrode 22 that applies a high-level power supply voltage ELVDD to the first terminals of the organic EL elements Lr, Lg, and Lb. Therefore, the high level power supply voltage ELVDD can be easily applied to the anode terminals of the organic EL elements Lr, Lg, Lb included in the pixel circuit 21 using the blanket electrode 22.

The power supply circuit 15 controls the first to third power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B, and the pixel circuit 21 has an anode terminal to which the high-level power supply voltage ELVDD is applied, and includes red, green, and blue First to third organic EL elements Lr, Lg, and Lb that respectively emit light, drain terminals connected to cathode terminals of the first to third organic EL elements Lr, Lg, and Lb, and first to third power supplies, respectively. It includes first to third driving transistors T2r, T2g, and T2b each having a source terminal to which voltages ELVSS_R, ELVSS_G, and ELVSS_B are applied and a gate terminal connected to the other conduction terminal of the write control transistor T1. Accordingly, it is possible to provide a field sequential type organic EL display device that displays a red subframe, a green subframe, and a blue subframe and has a small circuit scale. The scanning line driving circuit 13 is formed on the same panel (organic EL panel 11) as the pixel circuit 21. Therefore, the organic EL display device 10 can be reduced in size.

(Second Embodiment)
In the organic EL display device according to the second embodiment of the present invention, in the organic EL display device 10 according to the first embodiment, the drive transistor in the pixel circuit 21 is configured using an oxide semiconductor. The write control transistor in the scanning line and the transistor in the scanning line driving circuit 13 are formed using low-temperature polysilicon.

The transistors T2r, T2g, and T2b (drive transistors) in the pixel circuit 21 are oxide semiconductor transistors. As the oxide semiconductor transistor, for example, an N-channel IGZO transistor in which a semiconductor layer is formed using IGZO is used. The mobility of IGZO is 5 to 20 (au), and the N-channel IGZO transistor has a medium driving capability.

The transistor T1 (input transistor) in the pixel circuit 21 and the transistors T11 to T16 in the scanning line driving circuit 13 are low-temperature polysilicon transistors. Low temperature polysilicon has high mobility, and low temperature polysilicon transistors have high driving capability. The low temperature polysilicon transistor may be a P channel type or an N channel type. The mobility of P-channel type low-temperature polysilicon is about 50 (au), and the mobility of N-channel type low-temperature polysilicon is about 100 (au).

Hereinafter, effects of the organic EL display device according to the present embodiment will be described. In order to control the drive current of the organic EL elements Lr, Lg, Lb according to the gradation of the video signal, the gate voltage of the drive transistors T2r, T2g, T2b in the pixel circuit 21 is in a preferable range (for example, 2 to 5V). Range). However, when a driving transistor is formed using a material having high mobility such as low-temperature polysilicon, a preferable gate voltage range is low and narrow (for example, a range of 0 to 1 V). Since the resolution of the output voltage of the data line driver circuit is limited, if a low and narrow range of gate voltage is used, the display image may be crushed (a phenomenon in which the luminance corresponding to different gradations becomes the same).

As a method of preventing gradation collapse, a method of increasing the gate length of the drive transistor and reducing the drive capability of the drive transistor is conceivable. However, when this method is employed, the layout area of the drive transistor increases. For example, when the mobility of low-temperature polysilicon is 10 times the mobility of IGZO, the channel width and the preferable gate voltage range are the same between the drive transistor using low-temperature polysilicon and the drive transistor using IGZO. In order to achieve this, the gate length of the former drive transistor needs to be 10 times the gate length of the latter drive transistor.

On the other hand, the write control transistor and the transistor in the scanning line driving circuit 13 must always operate at high speed. For this reason, it is preferable to configure these transistors using low-temperature polysilicon. When these transistors are formed using IGZO, the layout area of the transistors increases. For example, when the mobility of low-temperature polysilicon is 10 times the mobility of IGZO, in order to make the gate length and the driving capability the same between a transistor using low-temperature polysilicon and a transistor using IGZO, The channel width of the latter transistor needs to be 10 times the channel width of the former transistor.

When the transistors in the scanning line driving circuit 13 and the pixel circuit 21 are all made of low-temperature polysilicon, the layout area of the driving transistors increases. On the other hand, when these transistors are all made of low-temperature polysilicon, the layout area of the write control transistor and the transistors in the scanning line driving circuit 13 increases. In the organic EL display device according to the present embodiment, the scanning line driving circuit 13 and the pixel circuit 21 are configured by two types of transistors in consideration of the driving capability of the transistors.

In the organic EL display device according to the present embodiment, the driving transistor is configured using an oxide semiconductor, and the writing control transistor and the transistor included in the scanning line driving circuit 13 are configured using low-temperature polysilicon. Therefore, the overall layout area of the transistors can be reduced as compared with the case where all of these transistors are formed using an oxide semiconductor and the case where all of these transistors are formed using low-temperature polysilicon.

(Third embodiment)
FIG. 13 is a block diagram showing a configuration of an organic EL display device according to the third embodiment of the present invention. The organic EL display device 50 shown in FIG. 13 is the same as the organic EL display device 10 according to the first embodiment, except that the organic EL panel 11, the data line driving circuit 14, the power supply circuit 15, the correction unit 16, and the characteristic data storage unit. 17 is replaced with an organic EL panel 51, a data line driving circuit 54, a power supply circuit 55, a correction unit 56, and a characteristic data storage unit 57, respectively. Similar to the organic EL display device 10, the organic EL display device 50 displays a red subframe, a green subframe, and a blue subframe in the first to third subframe periods, respectively. Hereinafter, the same reference numerals are given to the same components of the present embodiment as those of the first embodiment, and the description thereof will be omitted.

The organic EL panel 51 includes n scanning lines S1 to Sn, m data lines D1 to Dm, m white data lines DW1 to DWm, (m × n) pixel circuits 61, and blanket electrodes. 22 is included. The white data lines DW1 to DWm are arranged in parallel with the data lines D1 to Dm. The (m × n) pixel circuits 61 are arranged corresponding to the intersections of the scanning lines S1 to Sn and the data lines D1 to Dm. The pixel circuit 61 includes an organic EL element Lw that emits white light in addition to the organic EL elements Lr, Lg, and Lb.

The characteristic data storage unit 57 stores characteristic data required for the correction process in the correction unit 56. The characteristic data storage unit 57 stores the voltage-luminance characteristics of the organic EL element Lw in addition to the voltage-luminance characteristics of the organic EL elements Lr, Lg, Lb. The correction unit 56 performs correction processing on the video signal X1 output from the display control circuit 12 using the characteristic data stored in the characteristic data storage unit 57, and outputs the corrected video signal X3 to the data line driving circuit. 54 is output. The corrected video signal X3 includes data used for driving the white data lines DW1 to DWn.

The data line driving circuit 54 drives the data lines D1 to Dm and the white data lines DW1 to DWm based on the control signal C2 and the corrected video signal X3. The power supply circuit 55 outputs a fixed high-level power supply voltage ELVDD to the blanket electrode 22 and controls four power supply voltages ELVSS_R, ELVSS_G, ELVSS_B, and ELVSS_W supplied to the pixel circuit 61 based on the control signal C3. To do.

FIG. 14 is a circuit diagram of the pixel circuit 61 in the i-th row and j-th column. The pixel circuit 61 is obtained by adding transistors T2w and T3, a capacitor Cw, and an organic EL element Lw to the pixel circuit 21. The organic EL element Lw is realized by an organic light emitting layer that emits white light. The transistors T2w and T3 are N-channel TFTs.

The anode terminal of the organic EL element Lw is connected to the blanket electrode 22 together with the anode terminals of the organic EL elements Lr, Lg, and Lb. A fixed high level power supply voltage ELVDD is applied to the anode terminal of the organic EL element Lw. The cathode terminal of the organic EL element Lw is connected to the drain terminal of the transistor T2w. A variable power supply voltage ELVSS_W output from the power supply circuit 55 is applied to the source terminal of the transistor T2w. The capacitor Cw is provided between the gate terminal and the source terminal of the transistor T2w. The gate terminal of the transistor T3 is connected to the scanning line Si together with the gate terminal of the transistor T1. One conduction terminal (left terminal in FIG. 14) of the transistor T3 is connected to the white data line DWj. The other conduction terminal of the transistor T3 is connected to the gate terminal of the transistor T2w. Hereinafter, the node to which the gate terminal of the transistor T2w is connected is referred to as Nc.

Transistors T1, T2r, T2g, T2b, capacitors Cr, Cg, Cb, and organic EL elements Lr, Lg, Lb operate in the same manner as in the first embodiment in accordance with the change in voltage of the scanning line Si. While the voltage of the scanning line Si is at the high level, the transistor T3 is turned on, and the voltage of the white data line DWj is applied to the node Nc. When the voltage of the scanning line Si becomes low level, the transistor T3 is turned off. After the transistor T3 is turned off, the node Nc enters a floating state, and the gate-source voltage of the transistor T2w is held in the capacitor Cw. The drive current flowing through the transistor T2w and the organic EL element Lw changes according to the gate-source voltage of the transistor T2w. The organic EL element Lw emits light with luminance according to the drive current. The organic EL element Lw functions as a white organic EL element, and the transistor T3 functions as a white write control transistor.

FIG. 15 is a timing chart of the organic EL display device 50. In FIG. 15, EMW1 to EMWn indicate light emission periods of the organic EL elements Lw in the pixel circuits 61 in the 1st to nth rows, respectively. A black display period is provided at the head of each subframe period. The transistors T1, T2r, T2g, T2b and the organic EL elements Lr, Lg, Lb are driven in the same manner as in the first embodiment. Hereinafter, operations of the transistors T2w and T3 and the organic EL element Lw will be described.

The power supply voltage ELVSS_W is controlled to a low level when any of the power supply voltages ELVSS_R, ELVSS_G, and ELVSS_B is at a low level, and is controlled to a high level at other times. For this reason, the organic EL element Lw emits light during a period in which any one of the organic EL elements Lr, Lg, and Lb emits light during the first to third subframe periods. In the black display period, the voltage VZ for black display is also applied to the white data lines DW1 to DWm. Therefore, in all the pixel circuits 61, the transistor T3 is turned on, and the voltage VZ is applied to the node Nc via the transistor T3. At this time, since the driving current does not flow through the transistor T2w, the organic EL element Lw does not emit light. Therefore, a black screen is displayed during the black display period.

The voltages VW1i, VW2i, and VW3i are applied to the white data lines DW1 to DWm in the i-th line period within the first to third subframe periods, respectively. In the i-th line period, in the pixel circuit 61 in the i-th row, the transistor T3 is turned on, and the voltage VW1i, VW2i, or VW3i is applied to the node Nc via the transistor T3. Along with this, the gate-source voltage of the transistor T2w changes. A drive current according to the gate-source voltage (voltage after change) of the transistor T2w and the threshold voltage flows through the transistor T2w and the organic EL element Lw. Therefore, after the start of the i-th line period, the i-th organic EL element Lw emits white light with a luminance according to the voltages VW1i, VW2i, or VW3i written in the i-th line period.

FIG. 16 is a diagram showing the luminance of the organic EL element Lw in the pixel circuit 61 in the i-th row and j-th column. In FIG. 16, Pi represents the time from the start of the i-th line period until the power supply voltage ELVSS_W changes to the high level. In the first sub-frame period, the organic EL element Lw emits light for the time Pi with the brightness BR1i corresponding to the voltage VW1i. In the second subframe period, the organic EL element Lw emits light for a time Pi at a brightness BR2i corresponding to the voltage VW2i. In the third subframe period, the organic EL element Lw emits light for a time Pi at a brightness BR3i corresponding to the voltage VW3i.

Hereinafter, the correction unit 56 will be described. It is assumed that the red component of the gradation data of the pixel in the i-th row and j-th column included in the video signal X1 is Xr, the green component is Xg, and the blue component is Xb. The correction unit 56 first converts the three color components Xr, Xg, and Xb into four color components Er, Eg, Eb, and Ew including the white component Ew according to the following equations (14) to (17). .
Ew = k × min (Xr, Xg, Xb) (14)
Er = Xr−Ew (15)
Eg = Xg−Ew (16)
Eb = Xb−Ew (17)
However, in Formula (14), k is a constant of 0 or more and 1 or less. When the correction unit 56 converts the three color components Xr, Xg, and Xb into the four color components Er, Eg, Eb, and Ew, for example, Japanese Patent Laid-Open No. 2001-147666 and International Publication No. 2012/137553. The method described in the issue may be used.

Next, the correcting unit 56 is a method similar to the first embodiment, and the corrected red component Xr based on the converted red component Er, the converted green component Eg, and the converted blue component Eb. ', The corrected green component Xg' and the corrected blue component Xb 'are obtained respectively. Next, the correcting unit 56 obtains white components Ew1 to Ew3 that satisfy the following expression (18).
Ew = Ew1 + Ew2 + Ew3 (18)

The correction unit 56 obtains the white components Ew1 to Ew3 using, for example, the following method. The correcting unit 56 may obtain the white components Ew1 to Ew3 according to the equation (19) (first method).
Ew1 = Ew2 = Ew3 = Ew / 3 (19)
Alternatively, the correction unit 56 may obtain the white components Ew1 to Ew3 according to the equations (20) to (22) (second method).
Ew1 = Ew × Er / (Er + Eg + Eb) (20)
Ew2 = Ew × Eg / (Er + Eg + Eb) (21)
Ew3 = Ew × Eb / (Er + Eg + Eb) (22)
In the first method, the luminance of the organic EL element Lw in the first to third subframe periods is equal. According to the first method, the white components Ew1 to Ew3 can be easily obtained. In the second method, the organic EL element Lw emits light at the same luminance ratio as the organic EL elements Lr, Lg, and Lb in the first to third subframe periods. According to the second method, color breakup can be further reduced.

Next, the correction unit 56 obtains corrected white components Xw1 'to Xw3' based on the white components Ew1 to Ew3 in the same manner as in the first embodiment. When obtaining the corrected white components Xw1 'to Xw3', the voltage-luminance characteristics of the organic EL element Lw stored in the characteristic data storage unit 57 are used. The correction unit 56 uses the corrected red component Xr ′, the corrected green component Xg ′, the corrected blue component Xb ′, and the corrected white component Xw1 as the gradation data of the pixel in the i-th row and j-th column. The corrected video signal X3 including “˜Xw3” is output.

In the first subframe period, the data line driving circuit 54 applies a voltage corresponding to the corrected red component Xr ′ to the data line Dj, and corrects the white component Xw1 ′ to the white data line DWj. Apply a voltage according to. In the second subframe period, the data line driving circuit 54 applies a voltage corresponding to the corrected green component Xg ′ to the data line Dj, and corrects the white component Xw2 ′ to the white data line DWj. Apply a voltage according to. In the third subframe period, the data line driving circuit 54 applies a voltage corresponding to the corrected blue component Xb ′ to the data line Dj, and corrects the white component Xw3 ′ after correction to the white data line DWj. Apply a voltage according to.

As described above, the correction unit 56 performs the correction process for compensating for the difference in luminance caused by the difference in the length of the light emission periods of the organic EL elements Lr, Lg, Lb, and Lw, thereby using the light emission control transistor and the light emission control circuit. The image can be displayed with the correct brightness.

As described above, the organic EL display device 50 according to the present embodiment includes m white data lines DW1 to DWm. The pixel circuit 61 includes a white organic EL element Lw corresponding to white, a white driving transistor (transistor T2w) connected in series to the white organic EL element Lw, a gate terminal connected to the scanning line Gi, and white A white write control transistor (transistor T3) having a first conduction terminal (left terminal in FIG. 14) connected to the data line and a second conduction terminal connected to the gate terminal of the second drive transistor; It is out. The white organic EL element has an anode terminal to which a high-level power supply voltage ELVDD is applied and a cathode terminal connected to the drain terminal of the white drive transistor, and the white power supply voltage ELVSS_W is connected to the source terminal of the drive transistor. Is applied.

According to the organic EL display device 50, the luminance of the organic EL element in each subframe period can be adjusted by providing the white organic EL element Lw. Since the luminance of the organic EL elements Lr, Lg, and Lb can be lowered by the amount of light emitted from the white organic EL element Lw, the lifetime of the organic EL elements Lr, Lg, and Lb can be extended. Further, by causing the organic EL elements Lr, Lg, and Lb and the white organic EL element Lw to emit light in the same period, it is possible to suppress color breakup that occurs on the display screen. Since no white subframe period is provided, these effects can be obtained while maintaining the length of the subframe period.

The power supply circuit 55 controls the white power supply voltage ELVSS_W to a level at which the white organic EL element Lw can emit light in each subframe period. Therefore, the above effect can be obtained while performing the same light emission control as that of the organic EL elements Lr, Lg, and Lb on the white organic EL element Lw.

Further, the organic EL element Lw emits light during a period in which any one of the plurality of organic EL elements Lr, Lg, and Lb emits light in each subframe period. Therefore, the above-described effects can be obtained while the organic EL element Lw emits light for the same period as the other organic EL elements Lr, Lg, and Lb in each subframe period.

The organic EL element Lw may emit light with the same luminance in each subframe period (first method). According to the first method, the luminance of the organic EL element Lw in each subframe period can be easily obtained. Alternatively, the organic EL element Lw may emit light at the same luminance ratio as the plurality of organic EL elements Lr, Lg, and Lb in each subframe period (second method). According to the second method, color breakup can be further reduced.

In the organic EL display device 50, the white power supply voltage ELVSS_W is controlled as shown in FIG. 15, but the white power supply voltage ELVSS_W may be a fixed low level power supply voltage. Thus, by fixing the white power supply voltage to the low level power supply voltage, the configuration of the power supply circuit 55 can be simplified.

The following modifications can be configured for the organic EL display device according to the embodiment of the present invention. For example, the organic EL display device according to the modification may display three subframes in an order other than the above in the first to third subframe periods. For example, the organic EL display device according to the modification may display three subframes in the order of a red subframe, a blue subframe, and a green subframe in the first to third subframe periods.

Further, the organic EL display device according to the modification may divide one frame period into four or more subframe periods and display four or more subframes in one frame period. In this case, the organic EL display device according to the modified example includes the pixel circuit 21, and two or three of the organic EL elements Lr, Lg, and Lb in the sub-frame period of colors other than red, green, and blue. The organic EL element may emit light. Alternatively, the organic EL display device according to the modification includes a pixel circuit including four or more organic EL elements, the same number of drive transistors, and a write control transistor, and one organic EL in each subframe period. The element may emit light.

Since the organic electroluminescence display device of the present invention has a feature that the circuit scale is small, it can be used as a single display device or a display unit of various electronic devices.

DESCRIPTION OF SYMBOLS 10, 50 ... Organic EL display device 11, 51 ... Organic EL panel 12 ... Display control circuit 13 ... Scanning line drive circuit 14, 54 ... Data line drive circuit 15, 55 ... Power supply circuit 16, 56 ... Correction part 17, 57 ... Characteristic data storage unit 21, 61 ... Pixel circuit 22 ... Blanket electrode 31 ... Unit circuit

Claims (19)

  1. A field sequential type organic electroluminescence display device,
    A plurality of scan lines;
    Multiple data lines,
    A plurality of pixel circuits arranged corresponding to the intersections of the scanning lines and the data lines;
    A scanning line driving circuit for driving the scanning lines;
    A data line driving circuit for driving the data line;
    A power supply circuit for controlling a plurality of power supply voltages corresponding to a plurality of colors,
    The pixel circuit includes:
    A plurality of organic electroluminescence elements corresponding to the plurality of colors;
    A plurality of drive transistors each connected in series to a corresponding organic electroluminescent element;
    A write control transistor having a gate terminal connected to the scan line, a first conduction terminal connected to the data line, and a second conduction terminal connected to gate terminals of the plurality of drive transistors;
    The organic electroluminescence element has an anode terminal to which a fixed high-level power supply voltage is applied, and a cathode terminal connected to a drain terminal of a corresponding driving transistor,
    A power supply voltage corresponding to the color of the corresponding organic electroluminescence element among the plurality of power supply voltages is applied to the source terminal of the drive transistor,
    In each subframe period, the power supply circuit controls a power supply voltage corresponding to a color of the subframe period to a first level at which the organic electroluminescence element can emit light, and the organic electroluminescence element emits another power supply voltage. The organic electroluminescence display device is controlled to a second level.
  2. A display off period is provided for each subframe period,
    The scanning line driving circuit applies an on-voltage for turning on the write control transistor to all the scanning lines in a display off period,
    2. The organic electro luminescence device according to claim 1, wherein the data line driving circuit applies a display off voltage for stopping light emission of the organic electroluminescence element to all the data lines during a display off period. Luminescence display device.
  3. A correction process is performed on the input video signal to compensate for a difference in luminance due to a difference in the length of the light emission period of the organic electroluminescence element, and the corrected video signal is sent to the data line driving circuit. The organic electroluminescence display device according to claim 2, further comprising a correction unit for outputting.
  4. A characteristic data storage unit for storing the characteristic data of the organic electroluminescence element for each color;
    The organic electroluminescence display device according to claim 3, wherein the correction unit performs the correction process using characteristic data stored in the characteristic data storage unit.
  5. The difference between the high level power supply voltage and the first level voltage is greater than the light emission threshold voltage of the organic electroluminescence element,
    2. The organic electroluminescence display device according to claim 1, wherein a difference between the high level power supply voltage and the second level voltage is smaller than a light emission threshold voltage of the organic electroluminescence element.
  6. The organic electroluminescence display device according to claim 5, wherein the second level voltage is the high level power supply voltage.
  7. The scanning line driving circuit applies the ON voltage to all the scanning lines according to a first control signal, and sets the OFF voltage at which the write control transistor is turned off to all the scanning lines according to a second control signal. The organic electroluminescence display device according to claim 2, wherein the organic electroluminescence display device is applied.
  8. The scanning line driving circuit has a configuration in which unit circuits are connected in multiple stages,
    The unit circuit is
    An output terminal connected to the scanning line;
    A first transistor that applies the on-voltage to the output terminal according to the first control signal;
    The organic electroluminescence display device according to claim 6, further comprising: a second transistor that applies the off voltage to the output terminal according to the second control signal.
  9. The organic electroluminescence display device according to claim 1, further comprising a blanket electrode that applies the high-level power supply voltage to an anode terminal of the organic electroluminescence element.
  10. The power supply circuit controls first to third power supply voltages;
    The pixel circuit includes:
    First to third organic electroluminescence elements each having an anode terminal to which the high-level power supply voltage is applied and emitting light in red, green, and blue, respectively;
    Connected to the drain terminal connected to the cathode terminal of each of the first to third organic electroluminescence elements, the source terminal to which the first to third power supply voltages are applied, and the other conduction terminal of the write control transistor 2. The organic electroluminescence display device according to claim 1, further comprising first to third driving transistors each having a gate terminal.
  11. The organic electroluminescence display device according to claim 1, wherein the scanning line driving circuit is formed on the same panel as the pixel circuit.
  12. The driving transistor is configured using an oxide semiconductor,
    The organic electroluminescence display device according to claim 11, wherein the write control transistor and the transistor included in the scanning line driving circuit are configured using low-temperature polysilicon.
  13. A plurality of white data lines;
    The pixel circuit includes:
    A white organic electroluminescence device corresponding to white,
    A white driving transistor connected in series to the white organic electroluminescence element;
    A white write control transistor having a gate terminal connected to the scanning line, a first conduction terminal connected to the white data line, and a second conduction terminal connected to the gate terminal of the white drive transistor. Including
    The white organic electroluminescence element has an anode terminal to which the high-level power supply voltage is applied, and a cathode terminal connected to a drain terminal of the white driving transistor,
    2. The organic electroluminescence display device according to claim 1, wherein a white power supply voltage is applied to a source terminal of the white driving transistor.
  14. 14. The organic electroluminescence display device according to claim 13, wherein the power supply circuit controls the power supply voltage for white to a level at which the white organic electroluminescence element can emit light in each subframe period.
  15. The organic electroluminescence display device according to claim 13, wherein the white power supply voltage is a fixed low-level power supply voltage.
  16. The organic electroluminescence display device according to claim 13, wherein the white organic electroluminescence element emits light in a period in which any of the plurality of organic electroluminescence elements emits light in each subframe period.
  17. The organic electroluminescence display device according to claim 16, wherein the white organic electroluminescence element emits light with the same luminance in each subframe period.
  18. The organic electroluminescence display device according to claim 16, wherein the white organic electroluminescence element emits light at the same luminance ratio as the plurality of organic electroluminescence elements in each sub-frame period.
  19. A field sequential type organic electroluminescence display device,
    A plurality of scan lines;
    Multiple data lines,
    A plurality of pixel circuits arranged corresponding to the intersections of the scanning lines and the data lines;
    A scanning line driving circuit for driving the scanning lines;
    A data line driving circuit for driving the data line;
    A power supply circuit for controlling a plurality of power supply voltages corresponding to a plurality of colors,
    The pixel circuit includes:
    A plurality of organic electroluminescence elements corresponding to the plurality of colors;
    A plurality of drive transistors each connected in series to a corresponding organic electroluminescent element;
    A write control transistor having a gate terminal connected to the scan line, a first conduction terminal connected to the data line, and a second conduction terminal connected to gate terminals of the plurality of drive transistors;
    The organic electroluminescence element has an anode terminal to which a fixed high-level power supply voltage is applied, and a cathode terminal connected to a drain terminal of a corresponding driving transistor,
    A power supply voltage corresponding to the color of the corresponding organic electroluminescence element among the plurality of power supply voltages is applied to the source terminal of the drive transistor,
    The power supply circuit controls the power supply voltage corresponding to the color of the subframe period to the first level and the other power supply voltage to the second level in each subframe period,
    The difference between the high level power supply voltage and the first level voltage is greater than the light emission threshold voltage of the organic electroluminescence element,
    2. The organic electroluminescence display device according to claim 1, wherein a difference between the high level power supply voltage and the second level voltage is smaller than a light emission threshold voltage of the organic electroluminescence element.
PCT/JP2017/010116 2017-03-14 2017-03-14 Organic electroluminescence display device WO2018167835A1 (en)

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