System for uniformly illuminating liquid crystal display board from rear side

A system for uniformly illuminating a circular liquid crystal display board from the rear side, wherein said system includes a circular main body located behind said liquid crystal display board in a spaced relationship, said main body having a configuration substantially identical to that of the liquid crystal display board and including;

• a single circular transparent substrate made of transparent resin,
• a first coated layer deposited on the front surface of said transparent substrate with transparent resin, said first coated layer having a refractive index different from that of the transparent substrate,
• a second coated layer deposited on the rear surface of the transparent substrate with transparent resin, said second coated layer having a refractive index different from that of the transparent substrate,
• a rugged layer deposited on the second coated layer with transparent resin suitably employable for forming an underlying layer, said rugged layer including a number of light reflecting means in the form of concavities and convexities on the front surface of the rugged layer for irregularly reflecting light from alight source, said light reflecting means being distributed with a density per unit area which increases in inverse proportion to a square of the distance as measured from said light source to keep brightness substantially uniform over the whole surface of the transparent substrate, and
• a single light source disposed at the central part of the transparent substrate for generating light to be irradiated in the interior of the transparent substrate.