Patent ID: 6384881
Filing Date: 2002-05-07
Classification: G01D,G02B,G02F

Abstract:
A surface light source device of the side light type comprising:a guide plate having an emission faces a back face and a side end face; a primary light source which supplies illumination light to said side end face of said guide plate; and a polarization separating element arranged in a light path of emission from said emission face, which element selectively transmits light in a first polarization plane and selectively reflects light in a second polarization plane; said back face being provided with a great number of projection rows which run parallel with each other and in a first direction, said first direction neither being parallel with said first polarization plane nor vertical with respect to said first polarization plane, whereby said projection rows receive light reflected by said polarization separating element to produce a recyclic light that is directed to said emission face and is rich in light polarized in said first polarization plane to allow said recyclic light to transmit through said polarization separating element.