Large screen display apparatus utilizing a transparent plate to display an image over an entire surface of a diffusing surface

• US 5,264,941 A
• Filed: 01/06/1993
• Issued: 11/23/1993
• Est. Priority Date: 08/03/1990
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Iwata, Shuji, Shiramatsu, Naoki, Nakajima, Hajime, Nakano, Masaaki
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): HSIA, SHERRIE Y
• Application Number:
  US08/001,230
• Time in Patent Office: 321 Days
• Field of Search: 358/56, 358/60, 358/64, 358/231, 358/237, 358/238, 358/239, 358/240, 358/241, 358/230, 358/242, 359/451, 359/455, 359/453, 359/456, 359/457, 359/460, 359/599, 359/68, 359/69, 359/707
• US Class Current: 348/383
• CPC Class Codes: H04N 5/72 Modifying the appearance of television pictures by optical filters or diffusing screens
• CPC Class Codes: H04N 9/12 Picture reproducers H04N9/11 takes precedence
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3147 Multi-projection systems displays in general H04N9/12; video walls G06F3/1446, G09G2300/026

Abstract

A large-size screen display apparatus, having a plurality of projection display devices arrayed in a matrix arrangement to form one large screen, is 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. Further, 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.

Claims

1. A large screen display apparatus having a plurality of projection display devices arranged in a matrix array, each of the plurality of projection display devices comprising:

an optical image forming section for creating an optical image in response to a video signal;

a projection lens for magnifying and projecting an enlarged optical image of the optical image formed by the optical image forming section;

a housing for accommodating and supporting the optical image forming section and the projection lens; and

a screen for displaying the enlarged optical image by reflecting incident projected light rays with a transparent plate, the screen including the transparent plate provided on a light entrance side of the screen, receiving the optical image from the projection lens, and a diffusing surface provided on a viewing side of the screen, receiving the optical image from the transparent plate, wherein a periphery of the screen is mounted to the housing and the transparent plate reflects incident light rays from said projection lens so as to increase an angle of magnification of the optical image so that the enlarge optical image is displayed on an entire surface of the diffusing surface, thereby preventing non-display areas on the diffusing surface.

2. The projection display device of claim 1, wherein the transparent plate is fabricated in the form of a lens which is concave at its light entrance side.

3. The projection display device of claim 1, wherein the transparent plate is fabricated in the form of a Fresnel lens.

4. The projection display device of claim 1, wherein the transparent plate is a distributed-reflection plate, a feature of which is that a refractive index increases progressively in proportion to a distance from a center of the transparent plate to corners of the transparent plate.