HOLLOW PLANAR ILLUMINATING DEVICE

摘要

Provided is a hollow planar illuminating device having uniform luminance distribution over the entire light emitting surface. A reflecting surface member (2) is arranged on the bottom side of a hollow unit case (1), a light emitting surface member (3) is arranged on the side facing the reflecting surface member of the unit case, and a space sandwiched between the reflecting surface member and the light emitting surface member of the unit case is permitted to be a hollow light guide region (10). An LED light source unit (5) wherein many LEDs are mounted in a row on a wiring board is arranged adjacent to the both sides or one side of the hollow light guide region so that light is emitted to the hollow light guide region. Between the LED light source unit and an end surface of the hollow light guide region, a light collecting lens (9) is arranged. The light collecting lens reduces the directivity angle of light emitted from the LED light source unit in the device thickness direction. Thus, a hollow planar illuminating device (30) is formed. The surface roughness (Ra) of the surface of the reflecting surface member (2) facing the hollow light guide region (10) is set to satisfy the inequalities of 1µm