# US 2012/0075539 A1 · Projection display device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2012/0075539 A1 - Document ID: US20120075539A1 - Status: Published application - Kind: A1 - Application number: 13/310,835 - Filed: 2011-12-05 - Published: 2012-03-29 - Earliest claimed: 2009-06-12 - Assignees: Asahi Glass Company, Limited - Inventors: Teppei KONISHI; Atsushi Koyanagi; Ayako Tanaka; Hiroshi Kumai; Yoshiharu Ooi - Web page: https://patentgrep.com/patent/US20120075539A1 ## CPC - H04N 9/3161: {using laser light sources (using laser beams scanning the display screen H04N9/3129)} - G02F 1/13476: {in which at least one liquid crystal cell or layer assumes a scattering state} - G03B 21/005: {Projectors using an electronic spatial light modulator but not peculiar thereto} - H04N 9/3129: {scanning a light beam on the display screen (scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161)} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - 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 A projection display device is provided with: a light source portion including at least one light source that emits coherent light; an image light generation portion that generates image light by modulating the light emitted by the light source portion; a projection portion that projects the image light; a liquid crystal scattering element that is disposed on an optical path between the light source portion and the image light generation portion and temporally changes scattering state for passing light; a transparent electrode formed on each of opposing surfaces of a plurality of transparent substrates of the liquid crystal scattering element; and a liquid crystal layer that is sandwiched between the transparent electrodes and has liquid crystal of a smectic phase having spontaneous polarization in voltage applied state, and is characterized in that an AC voltage is applied to the liquid crystal layer through the transparent electrode. ## Claims ### Claim 1 A projection display device comprising: a light source portion including at least one light source that emits coherent light; an image light generation portion that generates image light by modulating the light emitted by the light source portion; a projection portion that projects the image light; a liquid crystal scattering element that is disposed on an optical path between the light source portion and the image light generation portion and temporally changes scattering state for passing light; a transparent electrode formed on each of opposing surfaces of a plurality of transparent substrates of the liquid crystal scattering element; and a liquid crystal layer that is sandwiched between the transparent electrodes and has liquid crystal of a smectic phase having spontaneous polarization in voltage applied state, wherein an AC voltage is applied to the liquid crystal layer through the transparent electrode. ### Claim 2 (depends on 1) The projection display device according to claim 1, wherein a condenser lens that condenses scattered light is disposed on the optical path between the liquid crystal scattering element and the image light generation portion. ### Claim 3 (depends on 1) The projection display device according to claim 1, wherein an alignment processing is not performed on an interface of the liquid crystal layer. ### Claim 4 (depends on 1) The projection display device according to claim 1, wherein the liquid crystal is chiral smectic C phase liquid crystal. ### Claim 5 (depends on 4) The projection display device according to claim 4, wherein the liquid crystal has a phase transition series of Iso-N(*)-SmC*. ### Claim 6 (depends on 1) The projection display device according to claim 1, wherein the liquid crystal scattering element has a structure in which the liquid crystal layer is stacked more than one in number. ### Claim 7 (depends on 6) The projection display device according to claim 6, wherein a phase of an AC voltage applied to a first liquid crystal layer of the more than one liquid crystal layer and a phase of an AC voltage applied to a second liquid crystal layer of the more than one liquid crystal layer are different from each other. ### Claim 8 (depends on 1) The projection display device according to claim 1, wherein the liquid crystal scattering element has a prism array sheet. ### Claim 9 (depends on 1) The projection display device according to claim 1, wherein the liquid crystal scattering element has a reflection layer that reflects incident light. ### Claim 10 (depends on 1) The projection display device according to claim 1, wherein a voltage where the scattering state occurs is 3 to 100 Vrms. ### Claim 11 (depends on 1) The projection display device according to claim 1, wherein a frequency of the voltage where the scattering state occurs is 70 to 1000 Hz. ### Claim 12 (depends on 1) The projection display device according to claim 1, wherein a light scattering element that scatters incident light and emits the light is disposed on the optical path between the light source portion and the liquid crystal scattering element and on the optical path between the liquid crystal scattering element and the image light generation portion. ### Claim 13 (depends on 1) The projection display device according to claim 1, wherein a light scattering element that scatters incident light and emits the light is disposed on the optical path between the light source portion and the liquid crystal scattering element. ### Claim 14 (depends on 1) The projection display device according to claim 1, wherein a light scattering element that scatters incident light and emits the light is disposed on the optical path between the liquid crystal scattering element and the image light generation portion.