| 摘要 |
There is provided a surface light-emitting device capable of preventing an increase in power consumption even if the length of the light-emitting surface of the surface light-emitting device is greater than the width, and capable of emitting light uniformly without decreasing the brightness of the light-emitting surface nor increasing the height of the light guiding space. In the present surface light-emitting device, the incident plane ( 201 ) is one of two sides of the light guiding space ( 20 ) in opposition in the longitudinal direction. The light-transmitting plate ( 4 ) includes a diffusion filter ( 6 ) which covers a specific area of the surface of the light-transmitting plate ( 4 ) near the light source ( 3 ). The remaining area of the surface of the light-transmitting plate at a distance from the light source ( 3 ) is not covered with the diffusion filter ( 6 ). The diffusion filter ( 6 ) is formed of a laminate in which a plurality of diffuse transmission films are layered. The number of diffuse transmission film ( 6 ) layers is highest in the area closest to the light source ( 3 ) so that the light transmittance is increased as the distance from the light source ( 3 ) increases due to a decrease in the diffusion of light, and the number is gradually decreased as the distance from the light source ( 3 ) increases.
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