Planar lighting device

TL;DR: The planar lighting device as mentioned in this paper includes a light guide plate having the light exit plane, two pairs of light entrance planes formed at the four sides of the light exiting plane, and rear planes formed opposite to the light departure plane and inclined such that the light guidance plate grows thicker toward the center thereof.

Abstract: The planar lighting device includes a light guide plate having the light exit plane, two pairs of light entrance planes formed at the four sides of the light exit plane, and rear planes formed opposite to the light exit plane and inclined such that the light guide plate grows thicker toward the center thereof, a pair of main light sources and a pair of auxiliary light sources disposed opposite their respective light entrance planes to emit light to the respective light entrance planes, and illuminance distribution control unit to adjust the amount of light emitted by the main and auxiliary light sources to form a designated local illuminance distribution for any position desired in the light exit plane. The planar lighting device performs area control and line control to adjust illuminance at a light exit plane for any area desired and along any line desired, respectively.