Illumination for transmissive displays

Claim 1

An illumination device for transmissive displays consisting of: A. a light source which emits light from a thin, straight line, B. a lens placed in front of said light line, with its long axis parallel to said light emitting line, so that it collimates the light and causes it to be cast across a flat reflecting panel, and C. a flat reflecting panel which is an integral unit of rectangular shape, situated parallel to and close to the image forming surface of the display and possessing the following layers: (1) a first layer, on the side nearest the lamp, across which light is cast, being a thin transparent layer possessing a large number of thin, parallel ridges on one surface, with comparatively wide flat space between each of said ridges, such ridges shaped so that light from the light source entering the side of the ridge facing the light source is reflected by the opposite ridge side in a direction perpendicular to the panel and into the panel, (2) a transparent glass layer attached to the first transparent layer on the side opposite the ridges, said glass layer having sufficient thickness to provide structural stability and hold itself and the other layers flat, and (3) optionally a thin translucent diffusing layer inserted between and attached to the first transparent layer on the side opposite the ridges and the glass layer, said diffusing layer possessing sufficient diffusing properties to cause the direction of travel of light passing through it to be spread over a wide angle, said diffusing layer and said ridge layer being thin enough so that light exiting each ridge is cast through the diffusing layer only along a thin line directly in front of each ridge, said line having a width comparable to the width of the ridge, with the surface of the diffuser between the lines remaining un-illuminated.