# US 2014/0192038 A1 · Oled pixel driving circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192038 A1 - Document ID: US20140192038A1 - Status: Published application - Kind: A1 - Application number: 14/151,413 - Filed: 2014-01-09 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: EverDisplay Optronics (Shanghai) Limited - Applicants: EverDisplay Optronics (Shanghai) Limited - Inventors: Yongliang Qin; Jr Hong Chen; Chu Wan Huang - Web page: https://patentgrep.com/patent/US20140192038A1 ## CPC - G09G 3/3258: with pixel circuitry controlling the voltage across the light-emitting element - G09G 2300/043: Compensation electrodes or other additional electrodes in matrix displays related to distortions or compensation signals, e.g. for modifying TFT threshold voltage in column driver - G09G 2300/0861: with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes - G09G 2320/045: Compensation of drifts in the characteristics of light emitting or modulating elements - 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 The present invention relates to an OLED pixel driving circuit which has a data input unit for sending out controlling signals, a voltage storage unit for storing voltages from a first power source, a driving unit for receiving the controlling signals from the data input unit to selectively activate the voltage storage unit, a second power source providing a voltage to be stored in the voltage storage unit; and a switch connected to the second power source to offset potential loss of the first power source from the voltage stored in the voltage storage unit. The compensation circuit can not only compensate the non-uniformity of the threshold voltage but also eliminate the non-uniformity of the OLED display caused by the power IR drop, so that the effect of display of the OLED are maximally improved. ## Claims ### Claim 1 In a compensation circuit having a data input unit for sending out controlling signals, a voltage storage unit for storing voltages from a first power source and a driving unit for receiving the controlling signals from the data input unit to selectively activate the voltage storage unit, wherein the improvement comprises: a second power source providing a voltage to be stored in the voltage storage unit; and a switch connected to the second power source to offset potential loss of the first power source from the voltage stored in the voltage storage unit. ### Claim 2 (depends on 1) The compensation circuit according to claim 1, wherein the driving unit comprises a first electrode, a second electrode and a control terminal; current flowing through the first electrode and the second electrode of the driving unit is controlled according to variation of the voltage loaded on the control terminal; one end of the voltage storage unit is connected to the control terminal of the driving element to form a coupling point; the other end of the voltage storage unit is connected to the first electrode to form an input point; the second electrode of the driving unit forms an output point; a coupling element is coupled to the coupling point; the first power input is connected to the input point; a synchronous switch is connected between the output point and the coupling point and controlled by the controlling signals. ### Claim 3 (depends on 2) The compensation circuit according to claim 2, further comprising a light-emitting working unit controllably coupled to the output point. ### Claim 4 (depends on 3) The compensation circuit according to claim 3, wherein the light-emitting working unit further comprises a light-emitting element and a control element; the light-emitting element is connected to the output point through the control element; the control element is a control switch which is controlled by level fluctuation. ### Claim 5 (depends on 2) The compensation circuit according to claim 2, further comprising a voltage input unit controllably connected to the coupling element for sending data voltage to the driving unit. ### Claim 6 (depends on 5) The compensation circuit according to claim 5, wherein the voltage input unit is connected to the coupling element by a data switch. ### Claim 7 (depends on 6) The compensation circuit according to claim 6, wherein the data switch is a switch transistor which is formed by a thin film transistor. ### Claim 8 (depends on 6) The compensation circuit according to claim 6, wherein the data switch is a PMOS switch transistor; the gate of the PMOS switch transistor is connected to the data input unit. ### Claim 9 (depends on 1) The compensation circuit according to claim 1, wherein the driving unit is a driving transistor. ### Claim 10 (depends on 1) The compensation circuit according to claim 1, wherein the voltage storage unit is a non-polar capacitor. ### Claim 11 (depends on 1) The compensation circuit according to claim 1, wherein the switch is a switch transistor which is formed by a thin film transistor. ### Claim 12 (depends on 1) The compensation circuit according to claim 1, wherein the switch is a PMOS switch transistor; the gate of the PMOS switch transistor is connected to the data input unit. ### Claim 13 (depends on 2) The compensation circuit according to claim 2, wherein the coupling element is a non-polar capacitor. ### Claim 14 (depends on 4) The compensation circuit according to claim 4, wherein the synchronous switch is a switch transistor which is formed by a thin film transistor. ### Claim 15 (depends on 2) The compensation circuit according to claim 2, wherein the synchronous switch is a PMOS switch transistor; the gate of the PMOS switch transistor is connected to the data input unit. ### Claim 16 (depends on 4) The compensation circuit according to claim 4, wherein the light-emitting element is an organic light-emitting element. ### Claim 17 (depends on 4) The compensation circuit according to claim 4, wherein the control switch is a switch transistor which is formed by a thin film transistor. ### Claim 18 (depends on 4) The compensation circuit according to claim 4, wherein the control switch is a PMOS switch transistor; the gate of the PMOS switch is connected to a level input for controlling light-emitting working