# US 5,349,400 A · Back-projection display system and method for making a back-projection mirror > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,349,400 A - Document ID: US5349400A - Status: Granted - Kind: A - Application number: 08/064,164 - Filed: 1993-05-27 - Granted: 1994-09-20 - Earliest claimed: 1990-11-30 - Assignees: Thomson-CSF - Inventors: Daniel Kaplan; Jean-Claude Lehureau - Web page: https://patentgrep.com/patent/US5349400A ## CPC - G03B 21/30: adapted to collapse or fold, e.g. for portability - G03B 21/10: Projectors with built-in or built-on screen - 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 Back-projection display system including a screen which can be moved away from or, conversely, placed up against a support such as a wall, for example. A projector located at some distance away, on the ceiling for example, illuminates a back-projection mirror located at 45.degree. in relation to the illumination beam and in relation to the screen. The back-projection mirror itself is also articulated. In addition, the mirror may be made in the form of a holographic mirror. ## Claims ### Claim 1 A back-projection display system, comprising: a display screen; a projector for displaying images on a rear face of said display screen, wherein said display screen is attached to a planar surface and includes means for folding said display screen against said planar surface and also for moving said display screen away from said planar surface so that a major surface of said display screen is maintained substantially parallel to said planar surface when said display screen is held against said planar surface and when said display screen is moved perpendicularly away from said planar surface; and a mirror for reflecting light from said projector onto said rear face of said display screen, including means for folding said mirror against said planar surface. ### Claim 2 (depends on 1) The back-projection display system according to claim 1, wherein said mirror is a holographic mirror. ### Claim 3 (depends on 2) The back-projection display system according to claim 2, wherein said means for folding said display screen against said planar surface comprises first and second systems of rods for connecting opposite sides of said display screen to said planar surface, respectively. ### Claim 4 (depends on 2) The back-projection display system according to claim 2, wherein said mirror is connected to said display screen and said planar surface. ### Claim 5 (depends on 4) The back-projection display system according to claim 4, wherein each of said plurality of rods includes a first end having an element for sliding engagement in a slideway which is attached to said planar surface. ### Claim 6 (depends on 4) The back-projection display system according to claim 4, wherein each of said plurality of rods includes a first end having an element for sliding engagement in a slideway which is attached to said display screen. ### Claim 7 (depends on 5) The back-projection display system according to claim 5, wherein a second end of each of said plurality of rods includes a second element for sliding engagement with a second slideway attached to said display screen. ### Claim 8 (depends on 3) The back-projection display system according to claim 3, further comprising an elastic system for moving two rods of one of said systems of rods closer together to thereby cause said display screen to move away from said planar surface. ### Claim 9 (depends on 3) The back-projection display system according to claim 3, further comprising: at least one damper member connected between one of said rods and said planar surface for controlling movement of said display screen. ### Claim 10 (depends on 3) The back-projection display system according to claim 3, further comprising: at least one damper member connected between one of said rods and said display screen for controlling movement of said display screen. ### Claim 11 (depends on 1) The back-projection display system according to claim 1, further comprising: a latch means for holding said display screen in a position so that said display screen is folded away against said planar surface. ### Claim 12 (depends on 1) The back-projection display system according to claim 1, further comprising: at least one cable including a first end attached to said display screen and a second end attached to a winding drum which is coupled to said planar surface. ### Claim 13 (depends on 1) The back-projection display system according to claim 1, further comprising: at least one cable including a first end attached to said planar surface and a second end attached to a winding drum which is coupled to said planar surface. ### Claim 14 (depends on 1) The back-projection display system according to claim 1, further comprising: at least one cable including a first end attached to said display screen and a second end attached to a winding drum which is coupled to said display screen. ### Claim 15 (depends on 1) The back-projection display system according to claim 1, further comprising: at least one cable including a first end attached to said planar surface and a second end attached to a winding drum which is coupled to said display screen. ### Claim 16 (depends on 12) The back-projection display system according to claim 12, further comprising a motor for driving said winding drum. ### Claim 17 (depends on 13) The back-projection display system according to claim 13, further comprising a motor for driving said winding drum. ### Claim 18 (depends on 14) The back-projection display system according to claim 14, further comprising a motor for driving said winding drum. ### Claim 19 (depends on 15) The back-projection display system according to claim 15, further comprising a motor for driving said winding drum. ### Claim 20 (depends on 2) The back-projection display system according to claim 2, wherein said holographic mirror serves as both a mirror and a lens. ### Claim 21 (depends on 2) The back-projection display system according to claim 2, wherein said holographic mirror comprises: a hologram for correcting distortions in the beam of light projected onto said display screen. ### Claim 22 (depends on 2) The back-projection display system according to claim 2, wherein said display screen comprises a grid of serrations. ### Claim 23 (depends on 21) The back-projection display system according to claim 21, wherein said hologram is recorded using a beam having the same direction as the beam emitted by said projector with respect to the plane of the holographic mirror and using a beam transmitted by a cylindrical lens inclined in relation to the plane of the holographic mirror. ### Claim 24 (depends on 21) The back-projection display system according to claim 21, wherein said hologram is recorded zone by zone, using a beam having the same direction as the beam emitted by said projector with respect to the plane of the holographic mirror, and illuminating said zone in a direction toward a corresponding zone of said display screen.