# US 12,181,788 B2 · Projection lens with a first optical system to form an intermediate image of an optical image and projection device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,788 B2 - Document ID: US12181788B2 - Status: Granted - Kind: B2 - Application number: 17/521,402 - Filed: 2021-11-08 - Published: 2022-02-24 - Granted: 2024-12-31 - Earliest claimed: 2019-05-17 - Assignees: FUJIFILM Corporation - Applicants: FUJIFILM Corporation - Inventors: Masaru Amano; Hironobu Kayano - Web page: https://patentgrep.com/patent/US12181788B2 ## CPC - G02B 13/0065: {having a beam-folding prism or mirror} - G03B 21/28: Reflectors in projection beam {(in illumination beam G03B21/2066)} - G02B 7/182: for mirrors - G02B 13/16: for use in conjunction with image converters or intensifiers {, or for use with projectors, e.g. objectives for projection TV} - G02B 17/08: Catadioptric systems {(used in non-imaging applications G02B19/00)} - G03B 21/142: {Adjusting of projection optics} - G03B 21/145: {Housing details, e.g. position adjustments thereof} - G03B 21/147: {Optical correction of image distortions, e.g. keystone} - G03B 21/30: adapted to collapse or fold, e.g. for portability - H04N 5/74: Projection arrangements for image reproduction, e.g. using eidophor - 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) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A projection lens, which is mounted on a housing of a projection device including an electro-optical element, includes a first holding part that holds a first optical system disposed along a first optical axis along which light emitted from the housing passes, a first reflective part that bends light parallel to the first optical axis to form light parallel to a second optical axis, a second reflective part that bends the light parallel to the second optical axis to form light parallel to a third optical axis, and a second holding part holds the first reflective part and the second reflective part. A distance along the first optical axis between a first lens, which is disposed to be closest to a reduction side in the first optical system, and the first reflective part is longer than a distance along the second optical axis between the first reflective part and the second reflective part. The first optical system includes a second lens that is disposed to be closest to an enlargement side to form an intermediate image of an optical image of the electro-optical element. ## Claims ### Claim 1 A projection lens that is mounted on a housing of a projection device including an electro-optical element, the projection lens comprising: a first holding part that holds a first optical system disposed along a first optical axis along which light emitted from the housing passes; a first reflective part that bends light parallel to the first optical axis to form light parallel to a second optical axis; a second reflective part that bends the light parallel to the second optical axis to form light parallel to a third optical axis; and a second holding part that holds the first reflective part and the second reflective part, wherein a distance along the first optical axis between a first lens, which is disposed to be closest to a reduction side in the first optical system, and the first reflective part is longer than a distance along the second optical axis between the first reflective part and the second reflective part, the first optical system includes a second lens that is disposed to be closest to an enlargement side of the first optical system at an immediate upstream of the first reflective part at a reduction side thereof to form an intermediate image of an optical image of the electro-optical element between the second lens and the first reflective part, the first lens is a lens made of glass, and the first optical system includes an aspherical third lens that is made of a resin material and is disposed to be closer to the reduction side than the second lens. ### Claim 2 (depends on 1) The projection lens according to claim 1, wherein |1/f3| is smaller than |1/f2| in a case where a focal length of the second lens is denoted by f2 and a focal length of the third lens is denoted by f3. ### Claim 3 (depends on 1) The projection lens according to claim 1, wherein |1/f3| is 0.03 or less in a case where a focal length of the third lens is denoted by f3. ### Claim 4 (depends on 1) The projection lens according to claim 1, wherein the first optical system includes a stop portion that is disposed between the first lens and the third lens, and a distance between the stop portion and the third lens is longer than a distance between the stop portion and the first lens. ### Claim 5 (depends on 1) The projection lens according to claim 1, wherein a diameter of an optical surface of the third lens is larger than a diameter of an optical surface of the first lens and is smaller than a diameter of an optical surface of the second lens. ### Claim 6 (depends on 1) The projection lens according to claim 1, wherein the second holding part includes one holding frame that integrally holds the first reflective part and the second reflective part. ### Claim 7 (depends on 1) The projection lens according to claim 1, wherein the second holding part includes a second optical system through which the light parallel to the second optical axis passes, and diameters of optical surfaces of all lenses composing the second optical system are smaller than a diameter of an optical surface of the second lens. ### Claim 8 (depends on 1) The projection lens according to claim 1, wherein the intermediate image is formed to be closer to the reduction side than the first reflective part. ### Claim 9 (depends on 1) The projection lens according to claim 1, further comprising: a second holding part-fixing mechanism that fixes the second holding part to the first holding part, wherein the second holding part is capable of being shifted relative to the first holding part in a case where a fixing force of the second holding part-fixing mechanism is reduced. ### Claim 10 (depends on 1) A projection device comprising: the projection lens according to claim 1; the electro-optical element; and the housing. ### Claim 11 (depends on 1) The projection lens according to claim 1, wherein the second holding part includes one holding frame that integrally holds the first reflective part and the second reflective part. ### Claim 12 (depends on 2) The projection lens according to claim 2, wherein |1/f3| is 0.03 or less in a case where a focal length of the third lens is denoted by f3. ### Claim 13 (depends on 2) The projection lens according to claim 2, wherein the first optical system includes a stop portion that is disposed between the first lens and the third lens, and a distance between the stop portion and the third lens is longer than a distance between the stop portion and the first lens. ### Claim 14 (depends on 2) The projection lens according to claim 2, wherein a diameter of an optical surface of the third lens is larger than a diameter of an optical surface of the first lens and is smaller than a diameter of an optical surface of the second lens. ### Claim 15 (depends on 2) The projection lens according to claim 2, wherein the second holding part includes one holding frame that integrally holds the first reflective part and the second reflective part. ### Claim 16 (depends on 3) The projection lens according to claim 3, wherein the first optical system includes a stop portion that is disposed between the first lens and the third lens, and a distance between the stop portion and the third lens is longer than a distance between the stop portion and the first lens. ### Claim 17 (depends on 3) The projection lens according to claim 3, wherein a diameter of an optical surface of the third lens is larger than a diameter of an optical surface of the first lens and is smaller than a diameter of an optical surface of the second lens. ### Claim 18 (depends on 4) The projection lens according to claim 4, wherein a diameter of an optical surface of the third lens is larger than a diameter of an optical surface of the first lens and is smaller than a diameter of an optical surface of the second lens. ### Claim 19 (depends on 9) The projection lens according to claim 9, wherein the second holding part-fixing mechanism includes a male screw, a female screw that engages with the male screw, and a screw insertion hole into which the male screw is inserted, and the female screw is formed in any one of the first holding part or the second holding part, and the screw insertion hole is formed in the other thereof.