Patent ID: 10802197

Abstract:
A light guide plate is transparent to visible light and is formed into a plate shape. The light guide plate includes a plurality of prisms 21 provided in a first region 22 on one surface 2b of the light guide plate, each of the plurality of prisms 21 including a reflection surface 21a that reflects the visible light, which is emitted from the light source 3 and enters the light guide plate 2 through an incoming surface 2a, toward the other surface 2c of the light guide plate 2. Then, for each of a plurality of first partial regions (22-1 to 22-n) in the first region 22, at least one of a direction of the reflection surface 21a of each prism 21 arranged in the first partial region and a ratio of a total of areas of the reflection surfaces 21a of each prism 21 to the first partial region is set according to an amount of light traveling from the first partial region toward a predetermined viewpoint such that brightness of the first region 22 changes spatially irregularly as seen from the predetermined viewpoint.