GB1421138A - Radiation redistributive device - Google Patents

Abstract

1421138 Projection screens EASTMAN KODAK CO 13 Dec 1972 [13.Dec 1971 (2)] 57517/72 Headings G2J and G2X A reflective front or transparent rear projection screen has a surface with a plurality of parallel contiguous grooves 16, the depth of each groove undulating along its length to define a row of concave and convex optical microelements 11, Fig.6, each microelement being contoured to produce substantially uniform radiance throughout predefined vertical and horizontal, or other perpendicular, field angles; the plane which bisects one of the field angles and which extends perpendicular to the groove length intersects with similarly defined planes of all other microelements substantially along a first line which extends parallel to the surface and is in a plane perpendicular to the groove length. As shown in Figs. 4, 5 and 6 the optical elements 11 tilt as their displacement from the screen centre C increases, the tilting being towards and away from the centre depending on whether the screen is reflective or refractive respectively. The juncture of adjacent grooves 16 form cusp lines 17 and the screen may be cylindrically or spherically curved. The screen can be used in conjunction with a Fresnal lens.