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EP0287034A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Projection-type color display device

Assignee: Seiko Epson Corp
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Filing: 1988-04-12
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Granted: —
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Expires: 2008-04-12
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Abstract

Abstract Disclosed is a projection-type color display device wherein light from a common light source (1) is separated by a di­chroic mirror group into the three primary colors, the light of each color being guided to a respective one of three liquid crystal light valves (8B, 8G, 8R). Images produced by the three liquid crystal light valves are com­bined by dichroic prisms (9), the combined image being pro­jected by a single projection lens (12). In order to com­pensate for different luminous intensities of the primary colors within the light emitted by the light source, the length of the optical path for each colored light from the light source to the respective liquid crystal valve is the longer the higher the luminous intensity of the correspon­ding light is. The dichroic prisms (9) and the three liquid crystal light valves (8B, 8G, 8R) are arranged in such a manner that only one of the liquid crystal light valves needs to display a laterally inverted image like a mirror which is achieved by a corresponding construction of the driver circuit.

Inventors

  • 👤 Akitaka Seiko Epson Corporation Yajima
  • 👤 Junichi Seiko Epson Corporation Nakamura

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-04 23:15
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3102; H04N9/3105

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 151 words
A projection-type color display device comprising a single light source (1) for projection, a dichroic mirror group for segregating the light from the light source (1) into the primary colors, three liquid crystal light valves (8B, 8G, 8R) of an active matrix type for forming images, dichroic prisms (9) for synthesizing these images and a single lens (12) for projection, characterized in that said dichroic mirror group is so arranged that the length of the optical path between said three liquid crystal light valves (8B, 8G, 8R) and the light source (1) is the longest for the colored light with a highest lu­minous intensity and the shortest for the colored with the lowest luminous intensity, and a driver circuit for said liquid crystal light valves (8B, 8G, 8R) is so arranged that only one liquid crystal light valve among the three liquid crystal light valves displays mirror like laterally inverted images.
Claim 2
Dependent Claim 151 words
A projection-type color display device comprising a single light source (1) for projection, a dichroic mirror group for segregating the light from the light source (1) into the primary colors, three liquid crystal light valves (8B, 8G, 8R) of an active matrix type for forming images, dichroic prisms (9) for synthesizing these images and a single lens (12) for projection, characterized in that said dichroic mirror group is so arranged that the length of the optical path between said three liquid crystal light valves (8B, 8G, 8R) and the light source (1) is the longest for the colored light with a highest lu­minous intensity and the shortest for the colored with the lowest luminous intensity, and a driver circuit for said liquid crystal light valves (8B, 8G, 8R) is so arranged that only one liquid crystal light valve among the three liquid crystal light valves displays mirror like laterally inverted images.
Claim 3
Dependent Claim 19 words
Device as claimed in claim 1, characterized in that a tungsten halogen lamp is used as light source (1).
Claim 4
Dependent Claim 17 words
Device according to claim 1, characterized in that a xenon lamp is used as light source (1).
Claim 5
Dependent Claim 18 words
Device according to claim 1, characterized in that a metal halide lamp is used as light source (1).
Claim 6
Dependent Claim 38 words
Device according to any of the preceding claims, characterized by a light guide (4) for holding the dichroic mirror group and guiding the light from the light source (1) to the liquid crystal light valves (8B, 8G, 8R).

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