# US 10,310,366 B2 · Projection optical assembly and projector device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,310,366 B2 - Document ID: US10310366B2 - Status: Granted - Kind: B2 - Application number: 14/972,836 - Filed: 2015-12-17 - Published: 2016-04-21 - Granted: 2019-06-04 - Earliest claimed: 2011-07-05 - Assignees: Nittoh Inc. - Applicants: Nittoh Inc. - Inventors: Takahiko Matsuo - Web page: https://patentgrep.com/patent/US10310366B2 ## CPC - G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)} - G02B 13/16: for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV} - G02B 13/18: with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} - G02B 13/22: Telecentric objectives or lens systems - G02B 15/143107: {arranged +++} - G02B 15/15: compensation by means of only one movement or by means of only linearly related movements, e.g. optical compensation - G02B 15/163: having a first movable lens or lens group and a second movable lens or lens group, both in front of a fixed lens or lens group (G02B15/177 takes precedence) - G02B 17/08: Catadioptric systems {(used in non-imaging applications G02B19/00)} - G03B 21/147: {Optical correction of image distortions, e.g. keystone} - H04N 9/315: {Modulator illumination systems (general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20)} - H04N 9/317: {Convergence or focusing systems (electronic adjustment of convergence H04N9/3185; convergence or focusing arrangements for cathode ray tubes H04N9/28; means for automatic focusing of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/53)} - H04N 9/3197: {using light modulating optical valves} - 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 There is provided a projection optical system (1) that projects from a first image plane on a reducing side to a second image plane on an enlargement side, including a first refractive optical system (11) that includes eight lenses (L1) to (L8) and forms a first intermediate image (31) on the enlargement side using light that is incident from the reducing side, a second refractive optical system (12) that includes six lenses (L9) to (L14) and forms the first intermediate image (31) on the reducing side into a second intermediate image (32) on the enlargement side, and a first reflective optical system (20) that includes a first reflective surface (21a) with positive refractive power that is positioned closer to the enlargement side than the second intermediate image (32). ## Claims ### Claim 1 A projection optical system that projects from a first image plane on a reducing side to a second image plane on an enlargement side, comprising: a zoom optical system that includes a plurality of lenses and forms light incident from the reducing side via a first intermediate image formed inside the zoom optical system into a second intermediate image on the enlargement side, the zoom optical system including multiple lenses arranged on the reducing side of the first intermediate image and being configured to correct aberrations including curvature of filed, astigmatism and comatic aberration and multiple lenses arranged on the enlargement side of the first intermediate image and being configured to correct distortion including keystone distortion; a reflective optical system that includes a first reflective surface with positive reflective power that is positioned closer to the enlargement side than the second intermediate image, wherein the zoom optical system includes, in order from the reducing side, a former group, a middle group, and a latter group, the latter group including a first lens and a second lens and the first intermediate image being formed therebetween, and when zooming from a wide angle end to a telephoto end, the former group moves from the reducing side to the enlargement side, the middle group moves so as to compensate for movement of the former group, and the latter group is fixed, wherein the zoom optical system consists of the former group, the middle group and the latter group, distances between lenses included in the former group are fixed during zooming, and distances between lenses included in the middle group are fixed during zooming. ### Claim 2 (depends on 1) The projection optical system according to claim 1, wherein the former group has positive refractive power, the middle group has positive refractive power, and the latter group has positive refractive power. ### Claim 3 (depends on 1) The projection optical system according to claim 1, wherein a light ray that reaches a center of the second image plane from a center of the first image plane reaches the second image plane having crossed any of an optical axis of the zoom optical system and an optical axis of the reflective optical system three times. ### Claim 4 (depends on 1) The projection optical system according to claim 1, wherein the first image plane and the first reflective surface are disposed in a same side with respect to a first plane that includes an optical axis. ### Claim 5 (depends on 1) The projection optical system according to claim 1, wherein the first intermediate image and the second intermediate image are formed on opposite sides of an optical axis. ### Claim 6 (depends on 1) A projector comprising: the projection optical system according to claim 1; and a light modulator that forms an image on the first image plane. ### Claim 7 (depends on 6) The projector according to claim 6, further comprising an illuminating optical system that illuminates the first image plane and is disposed in a same side as the first reflective surface with respect to a first plane that includes the optical axis. ### Claim 8 (depends on 1) The projection optical system according to claim 1, wherein the first lens is the only lens of the latter group located on the reducing side of the first intermediate image. ### Claim 9 A projection optical system that projects from a first image plane on a reducing side to a second image plane on an enlargement side, comprising: a zoom optical system that includes a plurality of lenses and forms light incident from the reducing side via a first intermediate image formed inside the zoom optical system into a second intermediate image on the enlargement side; a reflective optical system that includes a first reflective surface with positive reflective power that is positioned closer to the enlargement side than the second intermediate image, wherein the zoom optical system includes, in order from the reducing side, a former group, a middle group, and a latter group, the latter group including a first lens and a second lens and the first intermediate image being formed therebetween, and when zooming from a wide angle end to a telephoto end, the former group moves from the reducing side to the enlargement side, the middle group moves so as to compensate for movement of the former group, and the latter group is fixed; wherein the zoom optical system consists of the former group, the middle group and the latter group, distances between lenses included in the former group are fixed during zooming, and distances between lenses included in the middle group are fixed during zooming; wherein the first lens is the only lens of the latter group located on the reducing side of the first intermediate image. ### Claim 10 (depends on 9) A projector comprising: the projection optical system according to claim 9; and a light modulator that forms an image on the first image plane. ### Claim 11 A projection optical system that projects from a first image plane on a reducing side to a second image plane on an enlargement side, comprising: a zoom optical system that includes a plurality of lenses and forms light incident from the reducing side via a first intermediate image formed inside the zoom optical system into a second intermediate image on the enlargement side; a reflective optical system that includes a first reflective surface with positive reflective power that is positioned closer to the enlargement side than the second intermediate image, wherein the zoom optical system includes, in order from the reducing side, a former group, a middle group, and a latter group, the latter group including a first lens and a second lens and the first intermediate image being formed therebetween, and when zooming from a wide angle end to a telephoto end, the former group moves from the reducing side to the enlargement side, the middle group moves so as to compensate for movement of the former group, and the latter group is fixed; wherein distances between lenses included in the former group are fixed during zooming and distances between lenses included in the middle group are fixed during zooming, and only the former group and the latter group of the zoom optical system move during zooming. ### Claim 12 (depends on 11) The projection optical system according to claim 11, wherein the first lens is the only lens of the latter group located on the reducing side of the first intermediate image. ### Claim 13 (depends on 11) A projector comprising: the projection optical system according to claim 11; and a light modulator that forms an image on the first image plane.