LENS SHEET AND BACK LIGHT

摘要

PURPOSE: To make it possible to suppress the generation of bright and dark patterns by superposition of lens sheets by forming the lens units of the lens sheets to specific shapes. CONSTITUTION: The lens sheet is a lens sheet having the lens faces formed with the many lens units in parallel on its one surface and is formed with the ridge lines of the lens units to the rugged shapes having a center line average roughness of 0.2 to 3.2μmRmax. Namely, the many lens units 7 are formed in parallel on one surface of a translucent sheet and the ridge lines 8 corresponding to the peak part of the respective lens units 7 are formed to such rugged shapes. In such a case, the generation of the bright and dark patterns by contact of the lens sheets with each other in the case the plural lens sheets are used in superposition is significant if the center line average roughness of the ridge lines 8 of the lens units 7 is below 0.2μmRmax. The front surface luminance of the back light degrades if the center line average roughness exceeds 3.2μmRmax.