OPTICAL SHEET, SURFACE LIGHT SOURCE DEVICE, SCREEN, AND DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an optical sheet having a positioning part capable of keeping a position without causing distortion or crack by absorbing deformed amount even when it is expanded or contracted due to the change of environment such as temperature or humidity, and a surface light source device equipped with the optical sheet, a screen and a display device.

SOLUTION: The recessed positioning part 142 recessed toward the inside of the sheet from the outer shape side of the optical sheet 14 is formed on at least two opposed outer shape sides of the optical sheet 14. The positioning part 142 is formed so that two opposed sides are parallel with each other, and a part that is the bottom of recessed shape becomes a part of a circle.

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