Tandem lighting panel

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≧2) which are disposed tandem to provide a large continuous emission area;
• and
• primary 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.