Patent ID: 6241358
Filing Date: 2001-06-05
Classification: G02B

Abstract:
A tandem surface light source device provided with a guiding-emission mechanism, said guiding-emission mechanism comprising:a first-step plate-like guide block B L 1, a second-step plate-like guide block B L 2 . . . a N-1 th-step plate-like guide block B L N-1 and a N th-step plate-like guide block B L N (N.gtoreq.2) which are disposed tandem to provide a large continuous emission area; andprimary light sources L 1, L 2 . . . L N-1 and L N to supply respectively said guide blocks B L 1, B L 2 . . . B L N-1 and B L N with primary light,each of said guide blocks B L 1 through B L N being provided with an incidence face to receive primary light, a distal portion oppositely located with respect to the incidence face and an emission face to output illumination light,at least each of said guide blocks B L 1 to B L N-1 having thickness which tends to decrease as distance from the corresponding incidence face increases,each of distal portions of the k th-step (k=1 . . . N-1) guide blocks having a back face provided with a recess to be used for disposing the primary light source L k+1 for supplying the incidence end face of the k+1 th-step guide block B L k+1 with primary light,a shield is disposed between the primary light source L k+1 and the guide block B L k so that the primary light source L k+1 avoids supplying the guide block B L k with direct light.