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Abstract

A system for uniformly illuminating a liquid crystal display board from the rear side includes a main body as an essential component. The main body includes a transparent substrate made of transparent resin, a first coated layer on the front surface of the transparent substrate made of transparent resin having a refractive index different from that of the transparent substrate, a second coated layer on the rear surface of the transparent substrate made of transparent resin having a refractive index different from that of the transparent substrate and a rugged layer on the second coated layer made of transparent resin suitably employable for forming an underlying layer. A plurality of light sources each in the form of a fluorescent lamp are arranged in the transparent substrate in a spaced relationship. The rugged layer has a number of light reflecting means in the form of concavities and convexities formed on the front surface of the rugged layer for the purpose of irregularly reflecting light from each fluorescent lamp. The light reflecting means are distributed with a density per unit area which is determined to increase in inverse proportion to a square of the distance as measured from each fluorescent lamp to keep brightness substantially uniform over the whole surface of the transparent substrate.

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First Claim