# US 8,772,761 B2 · Light emitting device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,772,761 B2 - Document ID: US8772761B2 - Status: Granted - Kind: B2 - Application number: 13/203,072 - Filed: 2010-02-22 - Published: 2012-03-01 - Granted: 2014-07-08 - Earliest claimed: 2009-02-24 - Assignees: Panasonic Corporation - Applicants: Kazuyuki Yamae; Kenichiro Tanaka - Inventors: Kazuyuki Yamae; Kenichiro Tanaka - Web page: https://patentgrep.com/patent/US8772761B2 ## CPC - H10K 50/125: specially adapted for multicolour light emission, e.g. for emitting white light - H10K 50/854: comprising scattering means - H10K 50/858: comprising refractive means, e.g. lenses - H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES ## Abstract The light emitting device includes an organic electroluminescent element (20) and a diffractive optical element (30). The organic electroluminescent element (20) includes an anode layer (21), a cathode layer (22), and plural light emitting layers (231 and 232) interposed between the anode layer (21) and the cathode layer (22) and configured to emit light rays with different wavelengths. The diffractive optical element (30) is positioned in paths of light rays emitted from the organic electroluminescent element (20). The diffractive optical element (30) is designed to have different grating patterns (311 and 312) diffracting the light rays respectively emitted from the light emitting layers (231 and 232) for reducing chromatic aberration. ## Claims ### Claim 1 A light emitting device comprising: an organic electroluminescence element including an organic light emitting layer including plural light emitting layers having different dominant emission wavelengths, which are stacked, said organic light emitting layer being configured to emit light rays of said different dominant emission wavelengths through a light emission surface of said organic light emitting layer; and a diffractive optical element placed over said light emission surface of said organic light emitting layer, wherein: said diffractive optical element is designed to have different grating patterns such that the light rays are diffracted by said grating patterns in such a manner to travel in a predetermined direction; and said different grating patterns comprise diffraction angles different from each other in relation to an incident light ray of a same wavelength. ### Claim 2 (depends on 1) The light emitting device as set forth in claim 1, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate having a first surface and a second surface, said substrate being placed over said light emission surface of said organic light emitting layer, and said substrate having transparency for the light rays, said plural light emitting layers interposed between said anode layer and said cathode layer, said anode layer, said cathode layer, said plural light emitting layers being stacked on said first surface, and at least one of said grating patterns being defined by said second surface having grooves periodically arranged thereon. ### Claim 3 (depends on 1) The light emitting device as set forth in claim 1, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate placed over said light emission surface of said organic light emitting layer, said substrate having transparency for the light rays said plural light emitting layers interposed between said anode layer and said cathode layer, and at least one of said grating patterns defined by regions which are formed inside of said substrate at predetermined intervals and have a different refractive index from that of said substrate. ### Claim 4 (depends on 3) The light emitting device as set forth in claim 3, wherein each of said regions is a cavity. ### Claim 5 (depends on 1) The light emitting device as set forth in claim 1, wherein one of said different grating patterns is a serrated grating pattern having a serration shape in cross-section, each serration of said serrated grating pattern having a plurality of levels, said serrated grating pattern being formed according to: a depth L being represented by a formula L = 15 ⁢ ⁢ λ 16 ⁢ ( n 1 - 1 ) wherein a dominant wavelength of said light ray is λ, and a refractive index of a material of said at least one serrated grating pattern is n1; and a pitch per pixel being represented by a formula Λ=N×λ×sin θ1 wherein θ1 is said diffraction angle, N is a number of levels, N sin θ1 is much greater than 1. ### Claim 6 (depends on 5) The light emitting device as set forth in claim 5, wherein said serrated grating pattern is optimized based on parameters selected from the group consisting of light intensity distributions of said organic electroluminescence element, dimensions of said different grating patterns, the number of levels N, a size of an irradiation area, location of the irradiation area, and output intensity distribution. ### Claim 7 A light emitting device comprising: an organic electroluminescence element including an organic light emitting layer including plural light emitting layers having different dominant emission wavelengths, which are stacked, said organic light emitting layer being configured to emit light rays of said different dominant emission wavelengths through a light emission surface of said organic light emitting layer; and a diffractive optical element placed over said light emission surface of said organic light emitting layer, wherein said diffractive optical element is designed to have different grating patterns diffracting the light rays for reducing color unevenness; and said different grating patterns comprise diffraction angles different from each other in relation to an incident light ray of a same wavelength. ### Claim 8 (depends on 7) The light emitting device as set forth in claim 7, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate having a first surface and a second surface, said substrate being placed over said light emission surface of said organic light emitting layer and said substrate having transparency for the light rays, said plural light emitting layers interposed between said anode layer and said cathode layer, said anode layer, said cathode layer, said plural light emitting layers being stacked on said first surface, and at least one of said grating patterns being defined by said second surface having grooves periodically arranged thereon. ### Claim 9 (depends on 7) The light emitting device as set forth in claim 7, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate placed over said light emission surface of said organic light emitting layer, said substrate having transparency for the light rays, said plural light emitting layers interposed between said anode layer and said cathode layer, and at least one of said grating patterns defined by regions which are formed inside of said substrate at predetermined intervals and have a different refractive index from that of said substrate. ### Claim 10 (depends on 9) The light emitting device as set forth in claim 9, wherein each of said regions is a cavity. ### Claim 11 (depends on 7) The light emitting device as set forth in claim 7, wherein one of said different grating patterns is a serrated grating pattern having a serration shape in cross-section, each serration of said serrated grating pattern having a plurality of levels, said serrated grating pattern being formed according to: a depth L being represented by a formula L = 15 ⁢ ⁢ λ 16 ⁢ ( n 1 - 1 ) wherein a dominant wavelength of said light ray is λ, and a refractive index of a material of said at least one serrated grating pattern is n1; and a pitch per pixel being represented by a formula Λ=N×λ×sin θ1 wherein θ1 is said diffraction angle, N is a number of levels, N sin θ1 is much greater than 1. ### Claim 12 (depends on 11) The light emitting device as set forth in claim 11, wherein said serrated grating pattern is optimized based on parameters selected from the group consisting of light intensity distributions of said organic electroluminescence element, dimensions of said different grating patterns, the number of levels N, a size of an irradiation area, location of the irradiation area, and output intensity distribution. ### Claim 13 A light emitting device comprising: an organic electroluminescence element including an organic light emitting layer including plural light emitting layers having different dominant emission wavelengths, which are stacked, said organic light emitting layer being configured to emit light rays of said different dominant emission wavelengths through a light emission surface of said organic light emitting layer; and a diffractive optical element placed over said light emission surface of said organic light emitting layer, wherein said diffractive optical element is designed to have different grating patterns diffracting the light rays for reducing wavelength dependency of the light rays; and said different grating patterns comprise diffraction angles different from each other in relation to an incident light ray of a same wavelength. ### Claim 14 (depends on 13) The light emitting device as set forth in claim 13, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate having a first surface and a second surface, said substrate being placed over said light emission surface of said organic light emitting layer, and said substrate having transparency for the light rays, said plural light emitting layers interposed between said anode layer and said cathode layer, said anode layer, said cathode layer, said plural light emitting layers being stacked on said first surface, and at least one of said grating patterns being defined by said second surface having grooves periodically arranged thereon. ### Claim 15 (depends on 13) The light emitting device as set forth in claim 13, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate placed over said light emission surface of said organic light emitting layer said substrate having transparency for the light rays, and said plural light emitting layers interposed between said anode layer and said cathode layer, and at least one of said grating patterns defined by regions which are formed inside of said substrate at predetermined intervals and have a different refractive index from that of said substrate. ### Claim 16 (depends on 15) The light emitting device as set forth in claim 15, wherein each of said regions is a cavity. ### Claim 17 (depends on 13) The light emitting device as set forth in claim 13, wherein one of said different grating patterns is a serrated grating pattern having a serration shape in cross-section, each serration of said serrated grating pattern having a plurality of levels, said serrated grating pattern being formed according to: a depth L being represented by a formula L = 15 ⁢ ⁢ λ 16 ⁢ ( n 1 - 1 ) wherein a dominant wavelength of said light ray is λ, and a refractive index of a material of said at least one serrated grating pattern is n1; and a pitch per pixel being represented by a formula Λ=N×λ×sin θ1 wherein θ1 is said diffraction angle, N is a number of levels, N sin θ1 is much greater than 1. ### Claim 18 (depends on 17) The light emitting device as set forth in claim 17, wherein said serrated grating pattern is optimized based on parameters selected from the group consisting of light intensity distributions of said organic electroluminescence element, dimensions of said different grating patterns, the number of levels N, a size of an irradiation area, location of the irradiation area, and output intensity distribution. ### Claim 19 A light emitting device comprising: an organic electroluminescence element including an organic light emitting layer including plural light emitting layers having different dominant emission wavelengths, which are stacked, said organic light emitting layer being configured to emit light rays of said different dominant emission wavelengths through a light emission surface of said organic light emitting layer; and a diffractive optical element placed over said light emission surface of said organic light emitting layer, wherein said diffractive optical element is designed to have different grating patterns diffracting the light rays for making spatial phase distribution of each of the light rays uniform; and said different grating patterns comprise diffraction angles different from each other in relation to an incident light ray of a same wavelength. ### Claim 20 (depends on 19) The light emitting device as set forth in claim 19, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate having a first surface and a second surface, said substrate being placed over said light emission surface of said organic light emitting layer, and said substrate having transparency for the light rays, said plural light emitting layers interposed between said anode layer and said cathode layer, said anode layer, said cathode layer, said plural light emitting layers being stacked on said first surface, and at least one of said grating patterns being defined by said second surface having grooves periodically arranged thereon. ### Claim 21 (depends on 19) The light emitting device as set forth in claim 19, wherein said organic electroluminescence element comprises: an anode layer; a cathode layer; and, a substrate placed over said light emission surface of said organic light emitting layer, said substrate having transparency for the light rays, said plural light emitting layers interposed between said anode layer and said cathode layer, and at least one of said grating patterns defined by regions which are formed inside of said substrate at predetermined intervals and have a different refractive index from that of said substrate. ### Claim 22 (depends on 21) The light emitting device as set forth in claim 21, wherein each of said regions is a cavity. ### Claim 23 (depends on 19) The light emitting device as set forth in claim 19, wherein one of said different grating patterns is a serrated grating pattern having a serration shape in cross-section, each serration of said serrated grating pattern having a plurality of levels, said serrated grating pattern being formed according to: a depth L being represented by a formula L = 15 ⁢ ⁢ λ 16 ⁢ ( n 1 - 1 ) wherein a dominant wavelength of said light ray is λ, and a refractive index of a material of said at least one serrated grating pattern is n1; and a pitch per pixel being represented by a formula Λ=N×λ×sin θ1 wherein θ1 is said diffraction angle, N is a number of levels, N sin θ1 is much greater than 1. ### Claim 24 (depends on 23) The light emitting device as set forth in claim 23, wherein said serrated grating pattern is optimized based on parameters selected from the group consisting of light intensity distributions of said organic electroluminescence element, dimensions of said different grating patterns, the number of levels N, a size of an irradiation area, location of the irradiation area, and output intensity distribution.