Patent ID: 9715054
Date: 2017-07-25
CPC Classifications: G02B

Claim:
1. A planar light unit comprising: a light source; and a light guide plate including an incident surface for receiving light emitted from the light source, an emission surface from which the light introduced through the incident surface is emitted, an opposing surface disposed so as to oppose the emission surface, and a side surface disposed along an outer periphery of the emission surface and the opposing surface, wherein the light guide plate has a circular solid disk shape with a cutaway portion, the incident surface is formed in the cutaway portion, the emission surface is disposed in an upper surface of the circular solid disk with the cutaway portion, wherein the emission surface has a non-rectangular outer shape, and at least a part of the side surface is formed as a diffusing surface, wherein the incident surface includes a first incident surface and a second incident surface located beside the first incident surface, the light source includes a first light source opposed to the first incident surface and a second light source opposed to the second incident surface, the first incident surface includes a first prism having a ridgeline oriented in a thickness direction of the light guide plate, the second incident surface includes a second prism having a ridgeline oriented in a thickness direction of the light guide plate, the first prism has an asymmetrical horizontal cross-sectional shape parallel to the emission surface, the cross-section including a first side located on a side of the side surface and a second side located on a side of the second incident surface, the second prism has an asymmetrical horizontal cross-sectional shape parallel to the emission surface, the cross-section including a third side located on a side of the first incident surface and a fourth side located on a side of the side surface, a first average value of angles defined between a first optical axis from the first light source to the first incident surface and the first side is larger than a second average value of angles defined between the first optical axis and the second side, and a fourth average value of angles defined between a second optical axis from the second light source to the second incident surface and the fourth side is larger than a third average value of angles defined between the second optical axis and the third side.