Surface light source device and liquid crystal display device, portable telephone and information terminal using surface light source device

摘要

In a surface light source device using a so-called point light source, the luminance distribution is made uniform, and the luminance thereof is increased. The direction of each of a plurality of diffuse pattern elements 24a constituting a diffuse pattern 24 formed on the lower surface of an optical waveguide plate 22 (a direction along the length) is at an angle of approximately 90° to a direction along the line connecting the diffuse pattern element 24a and a point light source 30. The density Á of the diffuse pattern elements is approximately zero in the vicinity of the point light source 30, while linearly increasing as the distance from the point light source 30 increases.