Optics: image projectors – Plural projection paths with single light source
Patent
1988-04-29
1991-05-21
Miller, Stanley D.
Optics: image projectors
Plural projection paths with single light source
350331R, 353122, G02F 113, G03B 2100
Patent
active
050169840
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
Reference is made to applicant's commonly assigned, U.S. Pat. Nos. 4,435,047, issued Mar. 6, 1984, for "Encapsulated Liquid Crystal and Method"; U.S. Pat. No. 4,606,611, issued Aug. 19, 1986, for "Enhanced Scattering in Voltage Sensitive Encapsulated Liquid Crystal"; U.S. Pat. No. 4,616,903, issued Oct. 14, 1986, for "Encapsulated Liquid Crystal and Method"; U.S. Pat. No. 4,662,720, issued May 5, 1987, for "Colored Encapsulated Liquid Crystal Devices Using Imbibition of Colored Dyes and Scanned Multicolor Displays"; U.S. Pat. No. 4,596,445, issued June 24, 1986, for "Colored Encapsulated Liquid Crystal Apparatus Using Enhanced Scattering"; and Ser. No. 585,883 for "Encapsulated Liquid Crystal Material, Apparatus And Method", filed Mar. 2, 1984; the entire disclosures of such patents and applications hereby are incorporated by reference.
TECHNICAL FIELD
The present invention relates generally to projectors and, more particularly, to a liquid crystal moving picture projector and method. In one embodiment of the invention light incident on a liquid crystal display-type device or imager selectively is scattered or transmitted by respective portions of the liquid crystal display, and a projection mechanism projects an image formed by either such scattered light or such transmitted light. (As used herein in connection with the invention the terms liquid crystal display and liquid crystal imager are intended to be synonymous and equivalent).
BACKGROUND
A conventional optical moving or motion picture projector may include a light source, an input image device holder, such as a film guide, sprockets, shutter, etc., or by which a film, and particularly the frames thereof, may be placed for illumination by light from the light source, and a lens system for projecting an image of the illuminated frame. Typically the film would have optically transparent portions and optically absorbent portions, e.g., black and/or colored portions. When projected onto a screen, such black portions appear black due to absorption of light by the light absorbing, e.g., black emulsion, material, and the optically transmissive portions would appear relatively bright on the screen. Common exemplary projectors are of 8, 16, and 32 millimeter sizes, depending on the size of the film used.
One problem with conventional projectors is the large amount of heat that is absorbed by the light absorbing portions of the film, which could cause destruction or damage to the film; to minimize such heat build-up it often is necessary to use one or more infrared or heat absorbing filters optically upstream of the film. The heat dissipated in the heat filters and at the optical source or cabinet containing the same requires elimination, for example by a blower or other means. The blower may produce undesirable noise and/or vibration and uses energy that would not have to be consumed if the heat did not require such elimination. A further disadvantage of conventional projectors is the diffraction of light at the interface between light absorbing material, such as a black emulsion, and transparent material of the film; such diffraction can reduce the contrast and quality of the projected image seen on a screen. Furthermore, in conventional film projectors, contrast would be reduced since images are formed in part, at least, by the blockage of light, and such blockage is a function of absorption, which can vary, depending on the quality of opaqueness of the blocking material. Other disadvantages of conventional motion picture projectors is the size and number of reels of film needed to project an entire motion picture, story, etc., due to the relatively fixed nature of the respective images and scenes in the film.
Liquid crystal material currently is used in a wide variety of devices, including, for example, optical devices such as visual displays. A property of liquid crystal material enabling use in visual displays is the ability to scatter and/or to absorb light when the liquid crystal structure is in a random
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Gross Anita Pellman
Manchester R & D Partnership
Miller Stanley D.
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