Displays having improved contrast

• US 5,075,789 A
• Filed: 04/05/1990
• Issued: 12/24/1991
• Est. Priority Date: 04/05/1990
• Status: Expired due to Fees

• Current Assignee: Raychem Corporation (TE Connectivity Limited)
• Original Assignee: Raychem Corporation (TE Connectivity Limited)
• Inventors: Macknick, A. Brian, White, Larry J., Jones, Philip J.
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US07/505,206
• Time in Patent Office: 628 Days
• Field of Search: 350/331 R, 350/335, 350/339 R, 350/351, 350/345, 350/338, 353/119, 353/122, 353/121
• US Class Current: 349/7
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: G09G 3/36 using liquid crystals
• CPC Class Codes: H04N 5/65 Holding-devices for protective discs or for picture masks
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/31 Projection devices for colour picture display , e.g. using electronic spatial light modulators [ESLM]

Abstract

A display presenting an image having enhanced contrast has a screen which switches between a bright, image-presenting state and a dark, image-less state, to minimize glare from ambient light reflections. Alternatively, a shutter which switches between a substantially transparent state and a dark, light absorbing state is placed over a conventional screen.

Claims

1. A projection display presenting an image with improved contrast, comprising

(a) a screen which is switchable between a strongly light scattering state and a substantially transparent state;

(b) projection means for intermittently projecting an image onto the screen;

(c) a housing containing the projection means and onto which the screen is mounted;

the housing having a strongly light absorbing interior; and

(d) switching means for switching the screen synchronously with the projection of the image thereonto by the projection means, such that the screen is in its strongly light scattering state when the image is being projected thereonto and is in its substantially state when the image is not being projected thereonto.

2. A projection display according to claim 1, wherein the screen comprises encapsulated liquid crystal material.

3. A projection display presenting an image with improved contrast, comprising

(a) a screen comprising a plurality of segments, each segment being switchable between a strongly light scattering state and a substantially transparent state;

(b) projection means for sequentially projecting a portion of an overall image onto each segment;

(c) a housing containing the projection means and onto which the screen is mounted;

the housing having a strongly light absorbing interior; and

(d) switching means for switching each segment synchronously with the projection thereonto of the portion of the overall image by the projection means, such that each segment is in its strongly light scattering state when the portion of the overall image is being projected thereonto and is in its substantially transparent state when the portion of the overall image is not being projected thereonto.

4. A projection display according to claim 3, wherein the screen comprises encapsulated liquid crystal material.