SURFACE LIGHT SOURCE DEVICE

摘要

An improved surface light source device applicable to back lighting of a liquid display. In the surface light source device, a plate-shaped optical block (15) is disposed along an emitting surface of a plate-shaped optical member (11), to which illumination light is to be supplied from a primary light source (3), and has on at least one of its outer and inner sides a directivity modifying surface for modifying directivity of illumination light emitted from the emitting surface. Directivity modifying surface occupies at least part of the whole area of the optical block except a predetermined range (AR2) from a position aligning to the incidence surface of the plate-shaped optical member (11). The optical block (15) and the plate-shaped optical member (11) may be held in a unitary form by a holding mechanism formed integrally with the optical block (15) and/or the plate-shaped optical member (11). One end of a reflection member about the primary light source (3) may be pinched between the optical block (15) and the plate-shaped optical member (11).