LIGHTING LENS, LIGHT-EMITTING DEVICE, SURFACE LIGHT SOURCE, AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

A lighting lens (1) is provided with an incident surface (11), an exit surface (12), and a bottom surface (13). The incident surface (11) comprises a first incident surface (111) which is a curved surface orthogonal to an optical axis (A) and convex toward the exit surface (12) side and a second incident surface (112) which connects obliquely to the inner edge of the bottom surface (13) while expanding from the edge of the first incident surface (111). Assuming, in a cross section in the direction of light diffusion, an angle of refraction formed when the virtual light which directly reaches the incident surface (11) from the base point (Q) on the optical axis (A) corresponding to the position of a light source (20) passes through the incident surface (11) to be ?1, the sign of the ?1 on the optical axis (A) side of the normal (N) to the incident surface (11) to be negative, and the sign on the opposite side to be positive, the sign of the ?1 becomes negative in the first incident surface (111) and positive in the second incident surface (112).