| 摘要 |
A device for illuminating a display surface. Light is introduced through an end surface of a transparent substrate having front and back plane parallel opposed surfaces and thereby directed into the interior of the substrate. The back surface is textured with a multiplicity of shallow depressions such as grooves or dimples which have shallow sloped sides. These sides are configured so that light is selectively directed from the interior of the substrate through a limited angle out of the substrate towards a display surface adjacent and coextensive with the back surface of the substrate and away from a viewer observing the display surface through the substrate. The device provides uniform, high contrast illumination of underlying large area graphic displays such as maps, photographs, charts, and the like.
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