Patent ID: 8016445

Claim:
A planar light emitting element comprising: a light source; a light guide body for transmitting light emitted by the light source; first and second refractive index layers provided on the side of a light output surface of the light guide body; and a reflective plate for reflecting light output from the light guide body through an opening section; wherein the opening section is provided in the second refractive index layer, the second refractive index layer being arranged between the light guide body and the first refractive index layer, the opening section extending through the second refractive index layer; and the following expressions are established: n 1 >n 2 >n 3 ; and n 1 −n 2 >n 2 −n 3 , where n 1 is a refractive index of the light guide body, n 2 is a refractive index of the first refractive index layer, and n 3 is a refractive index of the second refractive index layer.