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Optical system for projection television

  • US 4,394,681 A
  • Filed: 04/27/1981
  • Issued: 07/19/1983
  • Est. Priority Date: 04/27/1981
  • Status: Expired due to Fees
First Claim
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1. For use in an ultra-compact, rear-projection television receiver, a projection optical system protractible and retractible within a narrow spatial column for emerging from and nesting within a cabinet of said receiver, said optical system comprising in combination:

  • a stationary optical assembly permanently enclosed in a lower portion of said cabinet, said assembly having;

    image projection means including at least one cathode ray tube means for forming a television image, and having associated projection lens means on a common axis therewith for projecting an aerial image of said television image a predetermined image projection distance along an optical path folded by optical path folding means, said common axis being oriented at a predetermined, steeply upward projection angle; and

    first mirror means mounted closely adjacent to said image projection means for receiving said aerial image, said first mirror being oriented at a fixed predetermined first mirror reflection angle effective to reflect said aerial image steeply upwardly along said folded optical path;

    a protractible optical assembly elevatable as a unit from said cabinet including;

    second mirror means located over said image projection means for receiving said aerial image reflected from said first mirror means when said protractible optical assembly is protracted, said second mirror means being oriented at a fixed predetermined second mirror reflection angle effective to reflect said aerial image forwardly, and when said protractible optical assembly is retracted, said predetermined second mirror reflection angle provides for angular conformance with said projection angle of said image projection means effectively permitting nesting of said second mirror with said image projection means;

    rear projection screen means located appreciably forwardly of said second mirror means and vertically arranged for receiving, when said protractible optical assembly is protracted, said aerial image reflected from said second mirror means, and when said protractible optical assembly is retracted, said screen means is vertically arranged for nesting between a front panel of said cabinet and said first mirror means;

    said projection angle of said image projection means, and said predetermined first and second mirror reflection angles being such that said protractible optical assembly, when retracted and nested, is overall depth-wise-shallow, and said receiver is as compact as a conventional, large-screen console television receiver, and when said protractible optical assembly is protracted within said narrow spatial column, said receiver remains depth-wise-shallow, yet is capable of displaying an image with an area greater than three times the image area of said conventional television receiver.

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