KEIWA Incorporated

An optical sheet laminate 100 is built in a liquid crystal display device including a display screen, on a back surface side of which a plurality of point light sources 42 are provided in a dispersed manner. The optical sheet laminate 100 includes a first optical sheet 43 having a first surface 21 b on which a first print pattern 101 A at least partially reducing transmission of light from the plurality of point light sources 42 is formed. A second print pattern 101 B at least partially reducing transmission of light from the plurality of point light sources 42 is formed on a second optical sheet 43 different from the first optical sheet 43 or on a second surface 21 a of the first optical sheet 43. The first print pattern 101 A and the second print pattern 101 B reduce luminance unevenness attributed to the plurality of point light sources 42, thereby making the luminance uniform.

When at least one scope of 0.5 mm square or more of a surface of an optical sheet having the unevenness is measured, height data of each of a plurality of pixels of an image obtained is determined, an approximated surface is calculated, from the height data of each pixel, for a minute region of 100 μm2 or less, and a calculation is repeatedly performed to obtain an inclination angle between: (i) a flat surface appearing after the unevenness is imaginarily removed and: (ii) the approximated surface, while two-dimensionally shifting the minute region at equal intervals along the flat surface by using at least one of the pixels as a unit to obtain a plurality of minute regions, a total area of some of the minute regions each having the inclination angle of 30° or more, accounts for 30% or more of a total area of all the minute regions.