Illuminating lens, lighting device, surface light source, and liquid-crystal display apparatus

摘要

An illuminating lens has a light entrance surface and a light exit surface. The light exit surface has a first light exit surface recessed toward a point on an optical axis A and a second light exit surface extending outwardly from the periphery of the first light exit surface. The first light exit surface includes a transmissive region located in the center of the first light exit surface and a total reflection region located around the transmissive region. The transmissive region transmits light that has been emitted from a starting point Q, which is the position of a light source on the optical axis A, at a relatively small angle with respect to the optical axis A. The total reflection region totally reflects light that has been emitted from the starting point Q at a relatively large angle with respect to the optical axis A.