Patent ID: 7489373
Filing Date: 2009-02-10
Classification: G02B,G02F

Abstract:
1. A prism sheet comprising: a first surface through which light from a light source that is disposed below the first surface enters the prism sheet; and a second surface through which the light exits the prism sheet, wherein the second surface includes prisms extending substantially parallel to one another continuously across the second surface, each of the prisms having a cross-section including sides that are arranged symmetrically about an apex with respect to a virtual normal line that is normal to the first surface, wherein the second surface is opposite to the first surface, and wherein a number of the sides of the second surface is at least four, and two of the symmetric sides meet at the apex, wherein the sides of the prisms comprises: a plurality of first sides forming a first angle that ranges from 65° to 75° with respect to the virtual normal line to refract light having an incident angle of less than about 2.8° with respect to the virtual normal line; and a plurality of second sides forming a second angle that ranges from about 40° to about 60° with respect to the virtual normal line, wherein the first sides and the second sides are alternately connected to each other.