# US 2018/0024429 A1 · High contrast discrete input prism for image projectors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024429 A1 - Document ID: US20180024429A1 - Status: Published application - Kind: A1 - Application number: 15/540,946 - Filed: 2015-12-21 - Published: 2018-01-25 - Earliest claimed: 2014-12-31 - Assignees: Dolby Laboratories Licensing Corporation - Applicants: Dolby Laboratories Licensing Corporation - Inventors: Duane Scott DEWALD; Nathan WAINWRIGHT; Douglas J. GORNY; Martin J. RICHARDS - Web page: https://patentgrep.com/patent/US20180024429A1 ## CPC - G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)} - G02B 1/11: Anti-reflection coatings - G02B 5/04: Prisms - G02B 27/1033: {having a single light modulator for all colour channels} - G03B 21/008: {using micromirror devices} - G03B 21/2013: {Plural light sources} - G03B 21/2066: {Reflectors in illumination beam (in projection beam G03B21/28)} - G03B 33/12: using beam-splitting or beam-combining systems, e.g. dichroic mirrors - H04N 9/3126: {for spatial light modulators in series} - G02B 27/0994: {Fibers, light pipes (optical fibers per se G02B6/02)} - 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) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Prism assemblies for projector display systems disclosed receive inputs from discrete color channels (e.g., red, green and blue channels. In one embodiment, “off state” light from the red, green, and blue DLP modulation may be reflected away from on-state light paths within the prism, tending to avoid uncontrolled scatter. In other embodiments, by keeping the colors separate for much of the prism path length, power levels may be significantly reduced at typical failure points. Light efficiency may be increased significantly when using discrete light sources like LEDs and lasers by removal of the additional red, green, and blue separation and re-combination losses. ## Claims ### Claim 1 A prism assembly for an image projector display system, the display system configured to supply a plurality of discrete color light inputs to the prism assembly, comprising: for each discrete color light input, a separate color channel prism path, wherein each separate color prism path receives a thermal load from the display system less than a prism assembly configured to receive full spectrum illumination from the display system. ### Claim 2 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path comprises: an input wedge element; a second wedge element; and a dump wedge element. ### Claim 3 (depends on 2) The prism assembly of claim 2 comprising a separate color channel modulator for each separate color channel prism path, the modulator capable of receiving the discrete color light input and affecting operational modes. ### Claim 4 (depends on 3) The prism assembly of claim 3 wherein further the modulator comprises a DMD reflector. ### Claim 5 (depends on 4) The prism assembly of claim 4 wherein further the modulator affects an ON state, and an OFF state ### Claim 6 (depends on 1) The prism assembly of claim 1 wherein further the prism assembly receives separate color light input from a plurality of separate color light inputs. ### Claim 7 (depends on 6) The prism assembly of claim 6 wherein the plurality of separate color light inputs comprises one of a group, said group comprising: lasers, LEDS and partially coherent light sources. ### Claim 8 (depends on 6) The prism assembly of claim 6 wherein the plurality of separate color light inputs comprises a white light input and an initial prism assembly to separate the white light to the plurality of separate color light inputs. ### Claim 9 (depends on 1) The prism assembly of claim 1 wherein said separate color channel prism paths comprises a separate Anti-Reflective (AR) coating applied to each separate color channel prism path. ### Claim 10 (depends on 6) The prism assembly of claim 6 wherein the AR coating is optimized for each separate color light for each separate color channel prism path. ### Claim 11 (depends on 10) The prism assembly of claim 10 wherein the AR coating is optimized for a range of angles that the separate color light makes with each separate color channel prism path. ### Claim 12 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path receives separate color light at a nominal angle. ### Claim 13 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path comprises an f/# of substantially f/4.5. ### Claim 14 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path comprises substantially a range of 2 to 3 thermal absorption margin on each element in the separate color channel prism path when compared to a prism assembly configured to receive full spectrum illumination from the display system. ### Claim 15 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path has a reduced back scatter when compared to a prism assembly configured to receive full spectrum illumination from the display system. ### Claim 16 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path has a reduced forward scatter when compared to a prism assembly configured to receive full spectrum illumination from the display system. ### Claim 17 (depends on 1) The prism assembly of claim 1 wherein each separate color channel prism path comprises a separate color light dump for each separate color light. ### Claim 18 A method for modulating separate color light sources in an image projector display system comprising: receiving a plurality of separate color light inputs into a prism assembly, the prism assembly comprising a plurality of separate color channel prism paths, one prism path for each separate color light inputs; modulating each color light input with a separate color light modulator in each separate color channel prism path. ### Claim 19 (depends on 18) The method of claim 18 further comprising dumping unused color light input into a separate color channel prism path light dump. ### Claim 20 (depends on 18) The method of claim 18 further comprising receiving a plurality of separate color light inputs at a nominal angle. ### Claim 21 (depends on 18) The method of claim 18 further comprising reducing the reflection of light in each separate color channel prism path by application of an optimized AR coating for each separate color light input.