Patent ID: 7056004

Claim:
A spread illuminating apparatus comprising: at least one spot-like light source; and a light conductive plate formed of a substantially transparent material, and adapted to allow light emitted from the at least one spot-like light source and introduced thereinto to exit out from one major surface thereof, the light conductive plate being shaped into a polygon which has two sides thereof substantially parallel to each other, and includes, as a part thereof, at least one triangle having its base defined by an imaginary line connecting respective straightly opposing ends of the two parallel sides, and which has a spot-like light source disposed at a side thereof constituting one of two hypotenuses of the triangle, wherein an angle formed between a line normal to the side of the polygon having the spot-like light source and one side of the two parallel sides of the polygon adjacent to the side having the spot-like light source is calculated by a formula: 55−( Y/X )×15 degrees where Y is a length of the one side of the two parallel sides, and X is a distance between the two parallel sides.