SURFACE LIGHT SOURCE DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a surface light source device whose manufacture cost can be reduced with simple constitution, which can improve the polarization degree of outgoing light and has high light use efficiency against all light beams by providing a high refractive index layer having a specified refractive index on the outgoing-side surface of a light transmission body. SOLUTION: The surface light transmission body 2 where a surface-side is set to be a light outgoing surface 2a-side, a light source 3 arranged so that light is made incident from the side end surface 2b of the light transmission body 2 and a reflection board 4 provided on the surface side opposite to the light outgoing surface 2a of the light transmission body 2 are provided. The surface light source device 1 is provided with the high refractive index layer 7 with the refractive index of more than 1.7 on the outgoing-side surface 2a. It is desirable that the refractive index of the high refractive index layer 7 is high as much s possible and transparency is desirable to be high as much as possible. Optical thickness can be suppressed to about 1/4 of a center wavelength. It is desirable to use titanium oxide as the high refractive index layer 7 when the refractive index, operability and cost are considered, for example.