# US 7,746,570 B2 · Fresnel optical element and projection display apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,746,570 B2 - Document ID: US7746570B2 - Status: Granted - Kind: B2 - Application number: 11/802,544 - Filed: 2007-05-23 - Published: 2009-03-12 - Granted: 2010-06-29 - Earliest claimed: 2003-12-17 - Assignees: Mitsubishi Denki Kabushiki Kaisha - Inventors: Hiroshi Suzuki; Takao Endo; Shinsuke Shikama; Kohei Teramoto - Web page: https://patentgrep.com/patent/US7746570B2 ## CPC - G02B 5/02: Diffusing elements; Afocal elements - G02B 3/08: with discontinuous faces, e.g. Fresnel lens {(diffractive Fresnel lenses G02B5/1876)} - G02B 5/045: {Prism arrays} - G03B 21/625: Lenticular translucent screens - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) ## Abstract Each of a plurality of Fresnel prisms 12 is formed so that a refractive surface 12 thereof includes a non-light incidence surface 12c upon which any light ray emitted from a projector 1 is not directly incident because it is intercepted by another Fresnel prism 12, the non-light incidence surface having an angle τ′ with a reflective surface 12b which is different from the prism apex angle τ of each of the plurality of Fresnel prisms. As a result, a light ray reflected by the refractive surface 12a of each of the plurality of Fresnel prisms without passing through the refractive surface can be preventing from emerging, as unnecessary light, toward the viewer's line of sight. ## Claims ### Claim 1 A Fresnel optical element having a plurality of Fresnel prisms arranged on a surface of a base faced a light emitting body, each of said plurality of Fresnel prisms having a first surface for receiving a part of an incident light ray emitted from a light emitting body, a second surface faced the first surface each other, and a third surface placed between the first surface and the second surface, wherein the third surface is transparent, and has an optical absorbing function of absorbing an incident light ray. ### Claim 2 A Fresnel optical element having a plurality of Fresnel prisms arranged on a surface of a base faced a light emitting body, each of said plurality of Fresnel prisms having a first surface for receiving a part of an incident light ray emitted from a light emitting body, a second surface faced the first surface each other, and a third surface placed between the first surface and the second surface, wherein the second surface receives at least a part of the incident light ray passing through the first surface, and wherein the third surface is transparent, and has an optical diffusing function of diffusing an incident light ray. ### Claim 3 (depends on 2) The Fresnel optical element according to claim 2, wherein the third surface is substantially flat. ### Claim 4 (depends on 2) The Fresnel optical element according to claim 2, wherein the third surface is substantially parallel to the surface of the base. ### Claim 5 A Fresnel optical element having a plurality of Fresnel prisms arranged on a surface of a base faced a light emitting body, each of said plurality of Fresnel prisms having a first surface for receiving a part of an incident light ray emitted from said light emitting body, a second surface faced the first surface each other, and a third surface placed between the first surface and the second surface, wherein the second surface receives at least a part of the incident light ray passing through the first surface, and wherein the third surface is transparent and has an optical absorbing function of absorbing an incident light ray. ### Claim 6 A Fresnel optical element having a plurality of Fresnel prisms arranged on a surface of a base faced a light emitting body, each of said plurality of Fresnel prisms having a first surface for receiving a part of an incident light ray emitted from a light emitting body, a second surface faced the first surface each other, and a third surface placed between the first surface and the second surface, wherein the second surface reflects at least a part of the incident light ray passing through the first surface to the surface of the base, and wherein the third surface is transparent, and has an optical diffusing function of diffusing an incident light ray. ### Claim 7 (depends on 6) The Fresnel optical element according to claim 6, wherein the third surface is substantially flat. ### Claim 8 (depends on 6) The Fresnel optical element according to claim 6, wherein the third surface is substantially parallel to the surface of the base. ### Claim 9 A Fresnel optical element having a plurality of Fresnel prisms arranged on a surface of a base faced a light emitting body, each of said plurality of Fresnel prisms having a first surface for receiving a part of an incident light ray emitted from a light emitting body, a second surface faced the first surface each other, and a third surface placed between the first surface and the second surface, wherein the second surface reflects at least a part of the incident light ray passing through the first surface to the surface of the base, and wherein the third surface is transparent, and has an optical absorbing function of absorbing an incident light ray. ### Claim 10 A Fresnel optical element having a plurality of Fresnel prisms arranged on a surface of a base faced a light emitting body, each of said plurality of Fresnel prisms having a first surface for receiving a part of an incident light ray emitted from said light emitting body, a second surface faced the first surface each other, and a third surface placed between the first surface and the second surface, wherein the third surface has an optical diffusing function of diffusing an incident light ray. ### Claim 11 (depends on 10) The Fresnel optical element according to claim 10, wherein the third surface is substantially flat. ### Claim 12 (depends on 10) The Fresnel optical element according to claim 10, wherein the third surface is substantially parallel to the surface of the base.