# US 10,319,305 B2 · Display device and drive method therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,319,305 B2 - Document ID: US10319305B2 - Status: Granted - Kind: B2 - Application number: 15/550,117 - Filed: 2016-02-03 - Published: 2018-02-01 - Granted: 2019-06-11 - Earliest claimed: 2015-02-10 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: Noritaka Kishi; Hiroyuki Furukawa; Katsuya Otoi; Kazuyoshi Yoshiyama; Tamotsu Sakai; Naoko Gotoh - Web page: https://patentgrep.com/patent/US10319305B2 ## CPC - G09G 3/3258: with pixel circuitry controlling the voltage across the light-emitting element - G09G 3/20: 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} - G09G 3/30: using electroluminescent panels - G09G 3/3233: with pixel circuitry controlling the current through the light-emitting element - G09G 3/3266: Details of drivers for scan electrodes - G09G 3/3291: in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements - G09G 2300/0842: forming a memory circuit, e.g. a dynamic memory with one capacitor - G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel - G09G 2320/0295: by monitoring each display pixel - G09G 2320/045: Compensation of drifts in the characteristics of light emitting or modulating elements - G09G 2320/0693: Calibration of display systems - G09G 2330/023: using energy recovery or conservation - G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00) ## Abstract A current measurement circuit measures a current flowing through a drive transistor when a plurality of measurement voltages are written to a pixel circuit in a switching manner, and a current flowing through an organic EL element when another plurality of measurement voltages are written to the pixel circuit in a switching manner. A correction unit obtains a threshold voltage and a gain of the drive transistor and the organic EL element with respect to each pixel circuit based on a measured current, determines in which operation region the drive transistor operates between a saturation region and a triode region with respect to each pixel circuit based on the video signal, and corrects the video signal in accordance with the operation region of the drive transistor. Since the drive transistor operates both in the saturation region and the triode region, it is possible to reduce a power supply voltage and reduce power consumption of a display device. ## Claims ### Claim 1 An active-matrix type display device comprising: a display unit including a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits arranged two-dimensionally; a scanning line drive circuit configured to drive the scanning lines; a data line drive circuit configured to drive the data lines; a measurement circuit provided at an outside of the display unit and configured to measure a current or a voltage with respect to the pixel circuit; and a correction unit configured to correct a video signal to be supplied to the data line drive circuit, based on the current or the voltage measured by the measurement circuit, wherein the pixel circuit includes an electro-optical element, and a drive transistor having a control terminal and connected in series with the electro-optical element, the drive transistor is configured to operate in a saturation region when a data voltage applied to the control terminal using the data line drive circuit is in a first range, and operate in a triode region when the data voltage is in a second range, and the correction unit is configured to determine in which operation region the drive transistor operates between the saturation region and the triode region with respect to each pixel circuit based on the video signal, and correct the video signal in accordance with the operation region of the drive transistor. ### Claim 2 (depends on 1) The display device according to claim 1, wherein the correction unit is configured to obtain characteristics of the drive transistor and the electro-optical element with respect to each pixel circuit based on the current or the voltage measured by the measurement circuit, and correct the video signal in accordance with the operation region of the drive transistor using the characteristics of the drive transistor and the electro-optical element. ### Claim 3 (depends on 2) The display device according to claim 2, wherein the correction unit is configured to obtain a first voltage to be applied to the drive transistor and a second voltage to be applied to the electro-optical element based on a code value included in the video signal, correct the second voltage using the characteristics of the electro-optical element, correct the first voltage using the characteristics of the drive transistor in accordance with the operation region of the drive transistor, and obtain a code value corresponding to a sum of a corrected first voltage and a corrected second voltage. ### Claim 4 (depends on 3) The display device according to claim 3, wherein the correction unit is configured to determine the operation region of the drive transistor based on the first voltage and the corrected second voltage, after correcting the second voltage. ### Claim 5 (depends on 1) The display device according to claim 1, wherein the display unit further includes a power supply electrode configured to supply a power voltage to the pixel circuit, and the display device further comprises an operational amplifier having a non-inverting input terminal to which the power supply voltage is applied, an inverting input terminal connected to the power supply electrode, and an output terminal connected to the power supply electrode. ### Claim 6 (depends on 1) The display device according to claim 1, further comprising a power supply control unit configured to control a level of the power supply voltage to be supplied to the pixel circuit. ### Claim 7 (depends on 1) The display device according to claim 1, wherein the measurement circuit is a current measurement circuit configured to measure a current flowing through the pixel circuit. ### Claim 8 (depends on 7) The display device according to claim 7, wherein the current measurement circuit is configured to measure a current flowing through the drive transistor when a plurality of measurement voltages are written to the pixel circuit in a switching manner, and a current flowing through the electro-optical element when another plurality of measurement voltages are written to the pixel circuit in a switching manner, and the correction unit is configured to obtain a threshold voltage and a gain of the drive transistor and a threshold voltage and a gain of the electro-optical element with respect to each pixel circuit based on the current measured by the current measurement circuit. ### Claim 9 (depends on 7) The display device according to claim 7, wherein the pixel circuit further includes: a write control transistor having a first conduction terminal connected to the data line, a second conduction terminal connected to the control terminal of the drive transistor, and a control terminal connected to a first scanning line in the scanning lines; and a read control transistor having a first conduction terminal connected to the data line, a second conduction terminal connected to a connection point of the drive transistor and the electro-optical element, and a control terminal connected to a second scanning line in the scanning lines, and the current measurement circuit is connected to the data line and is configured to measure the current flowing through the pixel circuit and the data line. ### Claim 10 (depends on 7) The display device according to claim 7, wherein the display unit further includes a plurality of monitor lines, the pixel circuit further includes: a write control transistor having a first conduction terminal connected to the data line, a second conduction terminal connected to the control terminal of the drive transistor, and a control terminal connected to the scanning line; and a read control transistor having a first conduction terminal connected to the monitor line, a second conduction terminal connected to a connection point of the drive transistor and the electro-optical element, and a control terminal connected to the scanning line, and the current measurement circuit is connected to the monitor line and is configured to measure the current flowing through the pixel circuit and the monitor line. ### Claim 11 (depends on 7) The display device according to claim 7, wherein the display unit includes a power supply line, the pixel circuit further includes a write control transistor having a first conduction terminal connected to the data line, a second conduction terminal connected to the control terminal of the drive transistor, and a control terminal connected to the scanning line, the first conduction terminal of the drive transistor is connected to the power supply line, and the current measurement circuit is connected to the power supply line and is configured to measure the current flowing through the pixel circuit and the power supply line. ### Claim 12 (depends on 1) The display device according to claim 1, wherein the measurement circuit is a voltage measurement circuit configured to measure a voltage of a node in the pixel circuit. ### Claim 13 (depends on 12) The display device according to claim 12, wherein the voltage measurement circuit is configured to measure a voltage of one conduction terminal of the drive transistor when a plurality of measurement currents flow through the drive transistor in a switching manner, and a voltage of one terminal of the electro-optical element when another plurality of measurement currents flow through the electro-optical element in a switching manner, and the correction unit is configured to obtain a threshold voltage and a gain of the drive transistor and a threshold voltage and a gain of the drive transistor and a threshold voltage and a gain of the electro-optical element with respect to each pixel circuit based on the voltage measured by the voltage measurement circuit. ### Claim 14 (depends on 13) The display device according to claim 13, wherein the pixel circuit further includes: a write control transistor having a first conduction terminal connected to the data line, a second conduction terminal connected to the control terminal of the drive transistor, and a control terminal connected to a first scanning line in the scanning lines; and a read control transistor having a first conduction terminal connected to the data line, a second conduction terminal connected to a connection point of the drive transistor and the electro-optical element, and a control terminal connected to a second scanning line in the scanning lines, and the voltage measurement circuit is connected to the data line and is configured to measure a voltage at the connection point of the drive transistor and the electro-optical element. ### Claim 15 A drive method for an active-matrix type display device including a display unit having a plurality of scanning lines, a plurality of data lines, and a plurality of pixel circuits arranged two-dimensionally, the method comprising: driving the scanning lines; driving the data lines; measuring a current or a voltage with respect to the pixel circuit at an outside of the display unit; and correcting a video signal to be used for driving the data line, based on a measured current or a measured voltage, wherein the pixel circuit includes an electro-optical element, and a drive transistor having a control terminal and connected in series with the electro-optical element, the drive transistor is configured to operate in a saturation region when a data voltage applied to the control terminal in driving the data lines is in a first range, and operate in a triode region when the data voltage is in a second range, and the correcting includes determining in which operation region the drive transistor operates between the saturation region and the triode region with respect to each pixel circuit based on the video signal, and correcting the video signal in accordance with the operation region of the drive transistor.