Patent ID: 6554440
Filing Date: 2003-04-29
Classification: G02B

Abstract:
A light pipe comprising:an upper surface; a lower surface; side surfaces between said upper and lower surfaces, at lease two of said side surfaces constituting incidence side surfaces each extending in left-right and front-rear directions of said light pipe; and light output means formed in one of said upper and lower surfaces so that incident light to said one of said upper and lower surfaces from each of said incidence side surfaces is made to go out from the other one of said upper and lower surfaces by said light output means, said light output means comprising a repetitive structure of prismatic structures having ridgelines extending along each of said incidence side surfaces respectively, wherein said light output means is constituted by the repetitive structure of the prismatic structures which are disposed at intervals of a predetermined pitch in a range of from 80 &mgr;m to 1 mm and each of which has a transmission light reflection surface and a counter surface facing said transmission light reflection surface, each of said transmission light reflection surfaces is constituted by a slope facing said incidence side surfaces at an inclination angle in a range of from 30 to 45 degrees with respect to a reference plane of a light exit surface which is located in the other one of said upper and lower surfaces where no light output means is located, a projected width of said transmission light reflection surface on said reference plane is not larger than 40 &mgr;m, and each of said counter surfaces is constituted by a slope inclined at an inclination angle of not smaller than 40 degrees with respect to said reference plane.