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Projection television lens system

  • US 5,808,804 A
  • Filed: 09/17/1996
  • Issued: 09/15/1998
  • Est. Priority Date: 09/21/1995
  • Status: Expired due to Fees
First Claim
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1. A projection lens system for use with a cathode ray tube comprising in order from the image side:

  • (a) a first lens element which has a positive power, at least one aspheric surface, and an overall meniscus shape which is concave to the cathode ray tube;

    (b) a second lens element which has a negative power and at least one aspheric surface;

    (c) a third lens element which has a positive power and provides a substantial portion of the power of the lens system;

    (d) a fourth lens element which has a weak power, at least one aspheric surface, and an overall meniscus shape which is concave to the cathode ray tube;

    (e) a fifth lens element which has a positive power, at least one aspheric surface, and a cathode-ray-tube-facing surface the majority of which being convex to the cathode ray tube; and

    (f) a lens unit which has a strong negative power, the lens unit being associated with the cathode ray tube during use of the lens system, and providing most of the correction for the field curvature of the lens system.

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