| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a surface light source device, capable of enhancing display image quality and improving the brightness in the required angular range containing a normal direction, by erasing ramp image and optimizing the luminance distribution, in the thin and large-sized surface light source device of a direct-type. <P>SOLUTION: The surface light source device comprises a light diffusion plate 6, a primary light source 2 disposed on the side of one side surface of the light diffusion plate 6, a light-condensing element 8 disposed on the side of the other surface of the light diffusion plate 6 and an optical reflecting plate 4 disposed behind the primary light source 2. The light-condensing element 8 has a large number of micro-protrusion parts 8b formed on one side surface of a sheet-like substrate 8a having translucency. In each of the micro-protrusion parts 8b, the maximum value and/or the minimum value among the average inclination angles, formed on a plurality of cross-sections which pass through the center of projection shape to the surface of the sheet-like substrate 8a and include the normal direction of the sheet-like substrate 8a, is 25 to 55°. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
