To provide a surface light source device capable of suppressing luminance unevenness without applying a special processing on a light diffusion plate.
The surface light source device 20 is provided with: a plurality of light sources 31 which are point light sources and are arranged two dimensionally; and a light diffusion plate 40 which diffuses light from the plurality of light sources 31. Each of light-distributions I(θ) of the respective plurality of light sources 31 is set so as to satisfy following formula (1) based on: an emitting angle θ of light from each light sources 31; a forward-direction radiation-intensity function f (θ, 0) of the BTDF (Bidirectional Transmission Distribution Function) of the light diffusion plate 40; and a forward-direction luminance profile p(θ) by each of the plurality of light sources 31 of the surface light source device 20 which is of a triangle shape, a trapezoid shape or a rectangle shape taking into account overlap in order to make the forward-direction luminance of the surface light source device 20 constant. Formula (1): I(θ)=(cosθ)-2{f(θ, 0)}-1p(θ).
| JP2009123709A | 2009-06-04 | |||
| JP2009048995A | 2009-03-05 |
| WO2009122761A1 | 2009-10-08 | |||
| WO2008146544A1 | 2008-12-04 |
Yoshinori Shimizu
Takashi Mikami