OPTICAL DIFFUSION SHEET, AND BACKLIGHT DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an optical diffusion sheet that extends the viewing angle and provides high front plane luminance.

SOLUTION: The optical diffusion sheet 16 is used for an edge light type backlight device. The optical diffusion sheet 16 includes a first refraction layer 17 having a front surface 171 having a plurality of linear prisms LP formed thereon. The optical diffusion sheet includes a second refraction layer 18 that is formed on the front surface 171 and has a refractive index different from that of the linear prisms LP. Light entering in the normal direction of the light diffusion sheet 16 from the rear surface 172 of the first refraction layer 17 is refracted on the front surface 171 as a boundary surface between the first and second refraction layers. At this time, the light is hardly totally-reflected, and retroreflection hardly occurs. The light having transmitted through the front surface 171 is further refracted on the front surface 181 of the second refraction layer 18, and goes to the outside.

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