# US 2017/0285374 A1 · Goa circuit based on ltps semiconductor thin film transistor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0285374 A1 - Document ID: US20170285374A1 - Status: Published application - Kind: A1 - Application number: 14/907,817 - Filed: 2015-12-29 - Published: 2017-10-05 - Earliest claimed: 2015-12-07 - Assignees: Wuhan China Star Optoelectronics Technology Co., Ltd. - Applicants: Wuhan China Star Optoelectronics Technology Co., Ltd. - Inventors: Yafeng Li - Web page: https://patentgrep.com/patent/US20170285374A1 ## CPC - G02F 1/1303: {Apparatus specially adapted to the manufacture of LCDs} - G09G 3/36: using liquid crystals - G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)} - G09G 3/3677: {suitable for active matrices only} - G11C 19/28: using semiconductor elements (G11C19/14, G11C19/36 take precedence) - G09G 2300/0408: Integration of the drivers onto the display substrate - G09G 2310/0286: Details of a shift registers arranged for use in a driving circuit - G09G 2310/0289: Details of voltage level shifters arranged for use in a driving circuit - 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 - 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) - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract The present invention provides a GOA circuit based on LTPS semiconductor thin film transistor to control the voltage levels of the first node, the second node and the third node (Q(n), P1(n), P2(n)) with the forward scan direct current control signal (U2D) and the backward scan direct current control signal (D2U). The clock signal (CK(M)) is merely in charge of the output of the GOA unit of corresponding stage, which can effectively reduce the loading of the clock signal. It ensures that the entire loading of the clock signal after the GOA units of multiple stages are coupled to promote the output stability of the GOA circuit, and to realize the forward-backward scan of the GOA circuit. ## Claims ### Claim 1 A GOA circuit based on LTPS semiconductor thin film transistor, comprising GOA units of a plurality of stages which are cascade coupled, and the GOA unit of each stage comprises: a scan control unit, a forward scan pull-down unit, a backward scan pull-down unit and an output unit; n is set to be a positive integer and except the GOA units of the first, the second, the next to last and the last stages, in the nth stage GOA unit: the scan control unit comprises: a first thin film transistor, and a gate of the first thin film transistor is electrically coupled to an output end of a two former stage n−2th GOA unit, and a source is electrically coupled to a forward scan direct current control signal, and a drain is electrically coupled to a source of a fourth thin film transistor; and a third thin film transistor, and a gate of the third thin film transistor is electrically coupled to an output end of a two latter stage n+2th GOA unit, and a drain is electrically coupled to the source of the fourth thin film transistor, and a source is electrically coupled to a backward scan direct current control signal; and the fourth thin film transistor, a gate of the fourth thin film transistor is electrically coupled to a constant high voltage level, and a drain is electrically coupled to a first node; the forward scan pull-down unit comprises: a fifth thin film transistor, and a gate of the fifth thin film transistor is electrically coupled to the forward scan direct current control signal, and a source is electrically coupled to the constant high voltage level, and a drain is electrically coupled to a second node; a sixth thin film transistor, and a gate of the sixth thin film transistor is electrically coupled to the backward scan direct current control signal, and a drain is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level; a thirteenth thin film transistor, and a gate of the thirteenth thin film transistor is electrically coupled to the first node, and a drain is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level; a ninth thin film transistor, and a gate of the ninth thin film transistor is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to the first node; and a tenth thin film transistor, a gate of the tenth thin film transistor is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to and output end; the backward scan pull-down unit comprises: an eighth thin film transistor, and a gate of the eighth thin film transistor is electrically coupled to the forward scan direct current control signal, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to a third node; a seventh thin film transistor, and a gate of the seventh thin film transistor is electrically coupled to the backward scan direct current control signal, and a source is electrically coupled to the constant high voltage level, and a drain is electrically coupled to the third node; a fourteenth thin film transistor, and a gate of the fourteenth thin film transistor is electrically coupled to the first node, and a drain is electrically coupled to the third node, and a source is electrically coupled to the constant low voltage level; an eleventh thin film transistor, a gate of the eleventh thin film transistor is electrically coupled to the third node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to the first node; and a twelfth thin film transistor, and a gate of the twelfth thin film transistor is electrically coupled to the third node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to the output end; the output unit comprises: a second thin film transistor, and a gate of the second thin film transistor is electrically coupled to the first node, and a source is electrically coupled to a Mth clock signal, and a drain is electrically coupled to an output end; and a bootstrap capacitor, and one end of the bootstrap capacitor is electrically coupled to a first node, and the other end is electrically coupled to the output end; voltage levels of the forward scan direct current control signal and the backward scan direct current control signal are opposite. ### Claim 2 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein the voltage level of the first node, the voltage level of the second node and the voltage level of the third node are all controlled by the forward scan direct current control signal and the backward scan direct current control signal. ### Claim 3 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein in the first stage GOA unit and the second stage GOA unit, the gate of the first thin film transistor is electrically coupled to a start signal. ### Claim 4 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein in the next to last stage GOA unit and the last stage GOA unit, the gate of the third thin film transistor is electrically coupled to a start signal. ### Claim 5 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein as the forward scan direct current control signal is high voltage level and the backward scan direct current control signal is low voltage level, a forward scan is performed. ### Claim 6 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein as the forward scan direct current control signal is low voltage level and the backward scan direct current control signal is high voltage level, a backward scan is performed. ### Claim 7 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein the clock signal comprises four clock signals: a first clock signal, a second clock signal, a third clock signal and a fourth clock signal. ### Claim 8 (depends on 1) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 1, wherein the thin film transistors are all N type LTPS thin film transistors. ### Claim 9 A GOA circuit based on LTPS semiconductor thin film transistor, comprising GOA units of a plurality of stages which are cascade coupled, and the GOA unit of each stage comprises: a scan control unit, a forward scan pull-down unit, a backward scan pull-down unit and an output unit; n is set to be a positive integer and except the GOA units of the first, the second, the next to last and the last stages, in the nth stage GOA unit: the scan control unit comprises: a first thin film transistor, and a gate of the first thin film transistor is electrically coupled to an output end of a two former stage n−2th GOA unit, and a source is electrically coupled to a forward scan direct current control signal, and a drain is electrically coupled to a source of a fourth thin film transistor; and a third thin film transistor, and a gate of the third thin film transistor is electrically coupled to an output end of a two latter stage n+2th GOA unit, and a drain is electrically coupled to the source of the fourth thin film transistor, and a source is electrically coupled to a backward scan direct current control signal; and the fourth thin film transistor, a gate of the fourth thin film transistor is electrically coupled to a constant high voltage level, and a drain is electrically coupled to a first node; the forward scan pull-down unit comprises: a fifth thin film transistor, and a gate of the fifth thin film transistor is electrically coupled to the forward scan direct current control signal, and a source is electrically coupled to the constant high voltage level, and a drain is electrically coupled to a second node; a sixth thin film transistor, and a gate of the sixth thin film transistor is electrically coupled to the backward scan direct current control signal, and a drain is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level; a thirteenth thin film transistor, and a gate of the thirteenth thin film transistor is electrically coupled to the first node, and a drain is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level; a ninth thin film transistor, and a gate of the ninth thin film transistor is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to the first node; and a tenth thin film transistor, a gate of the tenth thin film transistor is electrically coupled to the second node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to and output end; the backward scan pull-down unit comprises: an eighth thin film transistor, and a gate of the eighth thin film transistor is electrically coupled to the forward scan direct current control signal, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to a third node; a seventh thin film transistor, and a gate of the seventh thin film transistor is electrically coupled to the backward scan direct current control signal, and a source is electrically coupled to the constant high voltage level, and a drain is electrically coupled to the third node; a fourteenth thin film transistor, and a gate of the fourteenth thin film transistor is electrically coupled to the first node, and a drain is electrically coupled to the third node, and a source is electrically coupled to the constant low voltage level; an eleventh thin film transistor, a gate of the eleventh thin film transistor is electrically coupled to the third node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to the first node; and a twelfth thin film transistor, and a gate of the twelfth thin film transistor is electrically coupled to the third node, and a source is electrically coupled to the constant low voltage level, and a drain is electrically coupled to the output end; the output unit comprises: a second thin film transistor, and a gate of the second thin film transistor is electrically coupled to the first node, and a source is electrically coupled to a Mth clock signal, and a drain is electrically coupled to an output end; and a bootstrap capacitor, and one end of the bootstrap capacitor is electrically coupled to a first node, and the other end is electrically coupled to the output end; voltage levels of the forward scan direct current control signal and the backward scan direct current control signal are opposite; wherein the voltage level of the first node, the voltage level of the second node and the voltage level of the third node are all controlled by the forward scan direct current control signal and the backward scan direct current control signal. In the first stage GOA unit and the second stage GOA unit, the gate of the first thin film transistor is electrically coupled to a start signal. In the next to last stage GOA unit and the last stage GOA unit, the gate of the third thin film transistor is electrically coupled to a start signal. ### Claim 10 (depends on 9) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 9, wherein as the forward scan direct current control signal is high voltage level and the backward scan direct current control signal is low voltage level, a forward scan is performed. ### Claim 11 (depends on 9) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 9, wherein as the forward scan direct current control signal is low voltage level and the backward scan direct current control signal is high voltage level, a backward scan is performed. ### Claim 12 (depends on 9) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 9, wherein the clock signal comprises four clock signals: a first clock signal, a second clock signal, a third clock signal and a fourth clock signal. ### Claim 13 (depends on 9) The GOA circuit based on LTPS semiconductor thin film transistor according to claim 9, wherein the thin film transistors are all N type LTPS thin film transistors.