| 摘要 |
PURPOSE:To provide a plane light source device at a low cost and allowing it to emit light with uniform brightness by forming a plurality of light diffusion parts to diffuse the light led by a light leading layer, wherein the surface roughness of each light diffusion part shall be greater than that of the light leading layer, and arranging each light diffusion part so that its light diffusing area varies as going farther from a light emitting element. CONSTITUTION:Light emitted by a light emitting element 5 is led to a light leading layer 1 and is diffused particularly intensely by a light diffusion part 7, which is formed on the reflecting layer 4 side surface of this light leading layer 1 and has a great surface roughness. The diffused light at the light diffusion part 7 is partially diffused to light diffusion layer 3 to pass through it and be emitted, while another part is diffused to the reflecting layer 4 to be reflected thereby, projected again onto the light leading layer 1, passed through the light diffusion layer 3, and then emitted. Each light diffusion part 7 is so arranged that its light diffusing area increases monotonously from the incident side 8 edge of the light emitting element toward the opposing edge member. |
