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Image-projection-arrangement

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Image projection arrangement

Details

Inventors: van den Brandt, Andrianus H. J.;
Assignee: U.S. Philips Corporation (New York, NY)
Primary Examiner: Cuchlinski, Jr.; William A.
Assistant Examiner: Dowling; William C.
Attorney, Agent or Firm:

An image projection arrangement is described which comprises a light source (1) for producing a first light beam (b.sub.1), a reflective image display system (10) provided in the path of this light beam and a projection lens system (20), arranged in the path of a second light beam (b.sub.2) originating from the image display system. A beam-separating element (5) whose operating principle is based on total internal reflection of one of the beams (b.sub.1, b.sub.2) is provided in the light path between the light source and the image display system on the one hand and said system and the projection lens system on the other hand. This sresults in an adequate separation of these beams while the dimensions of the arrangement remain limited.

DETAILED DESCRIPTION I claim: 1.
An image projection arrangement comprising a light source for producing a first light beam, a reflective image display system arranged in the path of the first light beam and having at least one image display panel for generating an image to be projected, a projection lens system arranged in the path of a second light beam originating from the image display system for projecting the image produced by the image display system onto a projection screen, characterized in that between the light source and the image display system on the one hand and between this system and the projection lens system on the other hand a transition from a first to a second medium is provided, these media having different refractive indices, the transition being arranged such that one of the first and second light beams is totally reflected by the transition whilst the other light beam is transmitted by the transition.
2.
An image projection arrangement as claimed in claim 1, characterized in that the transition is constituted by an interface between air and a transparent material.
3.
An image projection arrangement as claimed in claim 2, characterized in that the transition is included in a prism system which consists of two transparent prisms having an air layer between two facing surfaces of the prisms.
4.
An image projection arrangement as claimed in claim 1, 2 or 3, in which the image display system modulates the polarization direction of the second light beam in accordance with the image information, characterized in that in the radiation path from the light source to the transition on the one hand and in the radiation path from this transition to the projection lens system on the other hand a polarization-sensitive beam splitter is provided for splitting the beam originating from the light source into two mutually perpendicularly polarized sub-beams which are both incident on the image display system and for recombining the two sub-beams after they have been modulated with the image information

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