Patent ID: 7503684

Claim:
A plane source of light comprising: a source of light; a light guide plate which confines light from the source of light, spreads light like a plane, and permits light to go out from the light-leaving surface and from at least a portion of the surface on the side opposite to the light-leaving surface; and a prism sheet arranged facing the side opposite to the light-leaving surface, wherein deflecting patterns are formed on the surface of the light guide plate on the side opposite to the light-leaving surface for reflecting light that propagates through the light guide plate; light reflected by the deflecting patterns goes out from the light-leaving surface in a manner that the direction of a peak intensity thereof is nearly perpendicular to the light-leaving surface; light goes out from the surface on the side opposite to the light-leaving surface in a manner that the direction of a peak intensity thereof is aslant relative to a direction perpendicular to the surface of the opposite side; light going out from the surface on the opposite side is deflected by the prism sheet in a manner that the direction of a peak intensity thereof is nearly perpendicular to the surface on the opposite side; and the source of light is a point source of light, and arcuate patterns are formed on the prism sheet with a position corresponding to the point source of light as nearly a center.