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Projection variable focusing lens and projection display device

  • US 8,199,419 B2
  • Filed: 06/15/2009
  • Issued: 06/12/2012
  • Est. Priority Date: 07/24/2008
  • Status: Active Grant
First Claim
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1. A projection variable focusing lens comprising:

  • a first lens group having a negative refractive power;

    a second lens group having a positive refractive power;

    a third lens group, wherein the third lens group includes a first negative lens, a second positive lens having a convex surface facing the reduction side, and a third positive lens having a convex surface facing the reduction side arranged in this order from the magnification side; and

    a fourth lens group having a positive refractive power,wherein the first to fourth lens groups are arranged in this order from a magnification side, andwhen a focal length varies, the second lens group is moved in an optical axis direction,during focusing, the third lens group is moved in the optical axis direction, anda reduction side is substantially telecentric.

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