Large screen display apparatus

Assignee: Mitsubishi Electric Corp

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Filing: 1991-08-01

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Granted: —

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Expires: 2011-08-01

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Abstract

Abstract A large-size screen display apparatus, having a plurality of projection display devices arrayed in a matrix arrangement to form one large screen, for displaying characters and the like. A screen of each projection display device consists of a transparent plate disposed on the light entrance side and a diffusing surface disposed on the viewing side, and the periphery, of the transparent plate is mounted to a housing of the display apparatus. Light rays emanated from a projection lens are reflected by the transparent plate, whereby an optical image is formed on the entire diffusing screen. Since the optical image is displayed on the entire surface of the diffusing screen, no non-display areas will appear on the screen even when the plurality of projection display device are arranged in the matrix array.

Inventors

👤 Masaaki c/o Mitsubishi Denki K.K. Nakano
👤 Naoki c/o Mitsubishi Denki K.K. Shiramatsu
👤 Shuji C/O Mitsubishi Denki K.K. Iwata
👤 Hajime c/o Mitsubishi Denki K.K. Nakajima

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-07 15:19

CPC Classifications

H; H04; H04N; H04N9/00; H04N9/12; H04N9/31; H04N9/3141; H04N9/3147; H04N5/00; H04N5/72

Claims Analysis

Total Claims: 7

Claim 1

Independent Claim 157 words

A projection display device for use in large screen display apparatus having a plurality of such devices arranged in a matrix array, the device (700) comprising: (a) an optical image forming section (200-216) for creating an optical image from a video signal; (b) a projection lens (502) for projecting an enlarged image of the optical image formed by the optical image forming section (200-216); (c) a housing (505) for accommodating and supporting the optical image forming section (200-216) and the projection lens (502); and (d) a screen (600) for displaying the optical image by transmission of projected light rays incident thereon to its outer viewing side, characterized in that the screen (600) is composed of a transparent plate (602-605) provided on the inner, light entrance side to transmit the light towards the periphery of the screen (600), and a diffusing surface (601) provided on the outer, viewing side, with the periphery thereof mounted to the housing (505).

Claim 2

Dependent Claim 25 words

A projection display device according to claim 1 wherein the transparent plate (602-605) is adapted to refract light to the periphery of the screen (600).

Claim 3

Dependent Claim 19 words

A projection display device according to claim 1 or 2, wherein the transparent plate is a concave lens (602).

Claim 4

Dependent Claim 19 words

A projection display device according to claim 1 or 2, wherein the transparent plate is a Fresnel lens (602).

Claim 5

Dependent Claim 52 words

A projection display device according to claim 1 or 2, wherein the thickness of the transparent plate (604) is expressed by t = d (np2/Sin2ϑ - 1) 1/2 where d denotes the thickness of the housing, np denotes the refraction factor of a refracting portion, and ϑ denotes the light incident angle.

Claim 6

Dependent Claim 37 words

A projection display device according to claim 1 or 2, wherein the transparent plate is a distributed-refraction plate (605) in which the refractive index increases progressively in proportion to a distance from the centre to the corners.

Claim 7

Dependent Claim 19 words

A large screen display apparatus comprising a plurality of display devices according to any one of the preceding claims.

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