Importance

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Abstract

A front illumination device for illuminating a reflective liquid crystal display cell (42) having a light source (12), a light guide (20), and a light coupling element (22). The light guide (20) has a thin plate element configured to receive light along an edge surface (28) thereof at an angle such that a majority of the light is totally internally reflected from the front surface (24) of the light guide (20). The light coupling element (22) has a thin plate element having a front surface (30) that is in contact with the back surface (26) of planar light guide (20). The front surface (30) of the light coupling element (22) has a plurality of cavities (40) disposed therein. Light impinging the interfaces (27) between cavities (40) and the back surface (26) is totally internally reflected within light guide (20). Light impinging the interfaces (33) between the cavities is transmitted into light coupling element (22) and is allowed to impinge a pixel (48A-48K) of liquid crystal display cell (42) which selectively rotates the polarization according to the selected state of the pixel and reflects the light back through the front surface (24) of light guide (20) for viewing by the user. A method of manufacturing the light coupling element (22) includes depositing a mask on the <100> surface of a silicon substrate (612), preferentially etching the substrate (614) and applying metallization to the etched substrate (616) to form a mold master having an extremely fine intercavity pitch.

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First Claim