# US 9,040,996 B2 · Light emitting device and electronic appliance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,040,996 B2 - Document ID: US9040996B2 - Status: Granted - Kind: B2 - Application number: 14/330,074 - Filed: 2014-07-14 - Published: 2015-02-05 - Granted: 2015-05-26 - Earliest claimed: 2001-02-21 - Assignees: Semiconductor Energy Laboratory Co., Ltd. - Applicants: Semiconductor Energy Laboratory Co., Ltd. - Inventors: Jun Koyama - Web page: https://patentgrep.com/patent/US9040996B2 ## CPC - C09K 11/06: containing organic luminescent materials - G09G 3/2022: {using sub-frames} - G09G 3/3208: organic, e.g. using organic light-emitting diodes [OLED] - G09G 3/3241: the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror - G09G 3/3266: Details of drivers for scan electrodes - G09G 3/3283: in which the data driver supplies a variable data current for setting the current through, or the voltage across, the light-emitting elements - H05B 33/14: characterised by the chemical or physical composition or the arrangement of the electroluminescent material {, or by the simultaneous addition of the electroluminescent material in or onto the light source} - H10K 59/1213: {the pixel elements being TFTs} - H10K 59/122: Pixel-defining structures or layers, e.g. banks - H10K 59/123: Connection of the pixel electrodes to the thin film transistors [TFT] - H10K 59/124: Insulating layers formed between TFT elements and OLED elements - H10K 59/126: Shielding, e.g. light-blocking means over the TFTs - H10K 59/1315: {comprising structures specially adapted for lowering the resistance} - H10K 77/10: Substrates, e.g. flexible substrates - C09K 2211/1088: containing oxygen as the only heteroatom - C09K 2211/185: of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd - G09G 2300/0417: Special arrangements specific to the use of low carrier mobility technology - G09G 2300/0426: Layout of electrodes and connections - G09G 2300/0809: Several active elements per pixel in active matrix panels - G09G 2300/0842: forming a memory circuit, e.g. a dynamic memory with one capacitor - 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 2310/027: Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters - G09G 2310/0272: Details of drivers for data electrodes, the drivers communicating data to the pixels by means of a current - G09G 2320/0247: Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes - G09G 2320/0266: Reduction of sub-frame artefacts - G09G 2320/041: Temperature compensation - H10D 86/0229: {characterised by control of the annealing or irradiation parameters} - H10D 86/421: {having a particular composition, shape or crystalline structure of the active layer} - H10D 86/60: wherein the TFTs are in active matrices - H10K 59/874: {including getter material or desiccant} - H10K 2102/00: Constructional details relating to the organic devices covered by this subclass - Y02E 10/549: Organic PV cells - Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - 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) - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES - H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The present invention is to provide a light emitting device capable of obtaining a certain luminance without influence by the temperature change, and a driving method thereof. A current mirror circuit formed by using a transistor is provided for each pixel. The first transistor and the second transistor of the current mirror circuit are connected such that the drain currents thereof are maintained at proportional values regardless of the load resistance value. Thereby, a light emitting device capable of controlling the OLED driving current and the luminance of the OLED by controlling the drain current of the first transistor at a value corresponding to a video signal in a driving circuit, and supplying the drain current of the second transistor to the OLED, is provided. ## Claims ### Claim 1 A light emitting device comprising: a transistor; an insulating film over the transistor; a first conductive film over the insulating film; and a pixel electrode comprising a second conductive film of a light emitting element over the insulating film, wherein a source or drain region of the transistor is electrically connected to a source or drain electrode of the transistor via a contact hole, and wherein the first conductive film and a connection portion of the source or drain region with the source or drain electrode overlaps. ### Claim 2 (depends on 1) The light-emitting device according to claim 1, wherein the first conductive film and the second conductive film are not in a same layer. ### Claim 3 (depends on 1) The light-emitting device according to claim 1, further comprising a bank over the source or drain electrode: wherein the first conductive film is over the bank. ### Claim 4 A light-emitting device comprising: a transistor; an insulating film over the transistor; a first conductive film over the insulating film; and an anode comprising a second conductive film of a light emitting element over the insulating film, wherein a source or drain region of the transistor is electrically connected to a source or drain electrode of the transistor via a contact hole, and wherein the first conductive film and a connection portion of the source or drain region with the source or drain electrode overlaps. ### Claim 5 (depends on 4) The light-emitting device according to claim 4, wherein the first conductive film and the second conductive film are not in a same layer. ### Claim 6 (depends on 4) The light-emitting device according to claim 4, further comprising a bank over the source or drain electrode: wherein the first conductive film is over the bank. ### Claim 7 A portable phone comprising: a transistor; an insulating film over the transistor; a first conductive film over the insulating film; and an anode comprising a second conductive film of a light emitting element over the insulating film, wherein a source or drain region of the transistor is electrically connected to a source or drain electrode of the transistor via a contact hole, and wherein the first conductive film and a connection portion of the source or drain region with the source or drain electrode overlaps. ### Claim 8 (depends on 7) The portable phone according to claim 7, wherein the first conductive film and the second conductive film are not in a same layer. ### Claim 9 (depends on 7) The portable phone according to claim 7, further comprising a bank over the source or drain electrode: wherein the first conductive film is over the bank.