Patent ID: 7675679
Filing Date: 2010-03-09
Classification: G02B,G02F,G03B

Abstract:
1. A Fresnel lens sheet used for an image display device, comprising: a light entrance plane and a light exit plane; a first prism group provided in an area on the light entrance plane where an incident angle of light is equal to or more than a predetermined incident angle of light; a second prism group provided in an area on the light entrance plane where an incident angle of light is less than the predetermined value; a third prism group provided in an area on the light exit plane opposite to the first prism group and proximate the second prism group; and a fourth prism group provided in an area on the light exit plane opposite to the second prism group, wherein the first prism group includes a first refraction plane that refracts the light made incident thereon at an angle equal to or more than the predetermined incident angle and a first total reflection plane that reflects the light being refracted by the first refraction plane and leads it to an exit side, wherein the second prism group includes a second refraction plane that refracts the light made incident thereon at an angle less than the predetermined incident angle and leads it to the exit side and a second total reflection plane that reflects the light bring refracted by the second refraction plane and leads it to the exit side, wherein an area of the light exit plane distal from the second prism group is planar, wherein the fourth prism group includes a third refraction plane that further refracts light being refracted by the second refraction plane of the second prism group and a fourth refraction plane that refracts light being reflected by the second total reflection plane of the second prism group, wherein light incident to the second prism group exits through the third prism group or the fourth prism group.