# US 2019/0244577 A1 · Display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0244577 A1 - Document ID: US20190244577A1 - Status: Published application - Kind: A1 - Application number: 16/234,347 - Filed: 2018-12-27 - Published: 2019-08-08 - Earliest claimed: 2018-02-06 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: TAKATSUGU KUSUMI; TAKUYA WATANABE; AKIRA TAGAWA; YASUAKI IWASE; YOHEI TAKEUCHI - Web page: https://patentgrep.com/patent/US20190244577A1 ## CPC - G09G 3/3677: {suitable for active matrices only} - G09G 3/3696: {Generation of voltages supplied to electrode drivers} - G02F 1/1368: in which the switching element is a three-electrode device {(G02F1/136277 takes precedence)} - G02F 2202/10: semiconductor - G09G 2310/0251: Precharge or discharge of pixel before applying new pixel voltage - G09G 2310/0286: Details of a shift registers arranged for use in a driving circuit - G09G 2310/063: Waveforms for resetting the whole screen at once - G09G 2310/08: Details of timing specific for flat panels, other than clock recovery - G09G 2320/0204: Compensation of DC component across the pixels in flat panels - G09G 2320/0233: Improving the luminance or brightness uniformity across the screen - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - G09G 2320/0257: Reduction of after-image effects - G09G 2330/027: Arrangements or methods related to powering off a display - H10D 86/423: {comprising semiconductor materials not belonging to the Group IV, e.g. InGaZnO} - H10D 86/60: wherein the TFTs are in active matrices - 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) - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES ## Abstract A configuration in which a voltage (a gate on voltage) of only one system is used as a voltage for turning scanning lines to a selected state is employed (single power supply system configuration). A unit circuit that constitutes a shift register within a gate driver includes a thin film transistor whose source terminal is connected to an output control node. In such a configuration, when the external power supply is stopped, a voltage supplied to a gate terminal of the thin film transistor and a voltage supplied to a drain terminal of the thin film transistor are set to the gate on voltage. ## Claims ### Claim 1 A display device comprising: a display panel including a plurality of scanning lines and a scanning line drive circuit, the plurality of scanning lines being connected respectively to a plurality of pixel formation portions, the scanning line drive circuit selectively driving the plurality of scanning lines; a voltage generation circuit configured to receive external power supply and generate one kind of scanning line selecting voltage and one kind of scanning line unselecting voltage, the scanning line selecting voltage being a voltage for turning the scanning lines to a selected state, the scanning line unselecting voltage being a voltage for turning the scanning lines to an unselected state; and a drive control circuit configured to control an operation of the scanning line drive circuit using the scanning line selecting voltage and the scanning line unselecting voltage which are generated by the voltage generation circuit, wherein the scanning line drive circuit includes a shift register including a plurality of unit circuits provided so as to respectively correspond to the plurality of scanning lines, the shift register being configured to perform a shift operation based on a plurality of clock signals, each of the plurality of unit circuits includes: an output node connected to a corresponding scanning line; an output control transistor having a control terminal, a first conducting terminal to which one of the plurality of clock signals is supplied, and a second conducting terminal connected to the output node; an output control node connected to the control terminal of the output control transistor; and an off control transistor having a control terminal, a first conducting terminal, and a second conducting terminal connected to the output control node, in normal times, the drive control circuit sets a voltage of the plurality of clock signals to the scanning line selecting voltage and the scanning line unselecting voltage alternatingly, and sets a voltage supplied to the control terminal of the off control transistor and a voltage supplied to the first conducting terminal of the off control transistor to the scanning line unselecting voltage, and when the power supply is stopped, the drive control circuit sets the voltage of the plurality of clock signals, the voltage supplied to the control terminal of the off control transistor, and the voltage supplied to the first conducting terminal of the off control transistor to the scanning line selecting voltage. ### Claim 2 (depends on 1) The display device according to claim 1, wherein an off control signal outputted from the drive control circuit is supplied to the control terminal of the off control transistor via a dedicated line, and the drive control circuit sets the off control signal to the scanning line unselecting voltage in normal times, and sets the off control signal to the scanning line selecting voltage when the power supply is stopped. ### Claim 3 (depends on 2) The display device according to claim 2, wherein the off control signal is supplied to the first conducting terminal of the off control transistor. ### Claim 4 (depends on 2) The display device according to claim 2, wherein a reference voltage outputted from the drive control circuit and serving as a reference of the operation of the scanning line drive circuit is supplied to the first conducting terminal of the off control transistor, and the drive control circuit sets the reference voltage to the scanning line unselecting voltage in normal times, and sets the reference voltage to the scanning line selecting voltage when the power supply is stopped. ### Claim 5 (depends on 1) The display device according to claim 1, wherein a capacitor and a resistor are connected to a line for supplying the scanning line selecting voltage from the voltage generation circuit to the drive control circuit. ### Claim 6 (depends on 1) The display device according to claim 1, wherein the display panel includes a plurality of transistors including the output control transistor and the off control transistor, and an off leakage current in at least a part of the plurality of transistors is one tenth or smaller than an that in a thin film transistor whose channel layer is made of low-temperature polysilicon. ### Claim 7 (depends on 6) The display device according to claim 6, wherein at least a part of the plurality of transistors is a thin film transistor whose channel layer is made of indium gallium zinc oxide.