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Device for changing directions of light rays

  • US 4,813,765 A
  • Filed: 05/18/1987
  • Issued: 03/21/1989
  • Est. Priority Date: 09/20/1985
  • Status: Expired due to Fees
First Claim
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1. A method of converting rays having various directions into light rays within a limited range of directions comprising the steps of:

  • providing a transparent optical body in the form of a wedge-shaped plate having opposite non-parallel major surfaces constituting reflecting surfaces, and a light incidence surface interconnecting one end of said reflecting surfaces, said reflecting surfaces converging gradually in a direction away from said light incidence surface;

    causing light rays having various directions to enter said optical body through said light incidence surface;

    causing the light rays, which have entered said optical body, to be internally and successively reflected by said reflecting surfaces until said successively internally reflected light rays are caused to have angles incident on the reflecting surfaces, which angles are equal to or smaller than a critical angle with respect to said reflecting surfaces; and

    causing the light rays, whose angles incident on the reflecting surfaces have become an angle equal to or smaller than said critical angle, to emerge from within the optical body to the outside through a light emerging surface portion of the optical body remote from said light incidence surface, in such a manner that the light rays emerging will be within a limited range of directions; and

    causing the light rays emerging from said light emerging surface portion to pass through transparent auxiliary elements of substantially triangular cross section, disposed outside of and adjacent to said light emerging surface portion, so as to make smaller the range of directions of the light rays which have passed through the auxiliary elements.

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