Patent ID: 6031664
Filing Date: 2000-02-29
Classification: G03B

Abstract:
A transmission type projection screen comprising:a plurality of parallel optical sheets arranged perpendicularly to an optical axis, said optical sheets including a front sheet having a front surface exposed directly to an observation side and a rearmost sheet having a surface facing a light source which emits light that passes substantially along said optical axis through said rearmost sheet and then through said front sheet to said observation side, said front sheet having a rear surface opposite to said front surface; anda plurality of prism lenses formed on said rear surface of said front sheet and including unit triangular prisms extending in a first direction along said rear surface and disposed in a succeeding arrangement, wherein each of the unit triangular prisms has a first inclined surface and a second inclined surface, and wherein the angle between said second inclined surface and said rear surface is less than the angle between said first inclined surface and said rear surface, said first inclined surface being so inclined as to internally reflect an outside light coming from the observation side into each unit triangular prism, to a direction inclined to said optical axis to remove said outside light out of viewer's sight.