| CPC G02B 6/0053 (2013.01) [G02B 6/0051 (2013.01)] | 10 Claims |
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1. An optical composite sheet, which comprises:
a prism sheet;
a light diffusion layer disposed under the prism sheet; and
a light absorbing layer disposed on the prism sheet, between the prism sheet and the light diffusion layer, or under the light diffusion layer,
wherein the following Relationship (1) is satisfied:
0.5≤(TPeak_0−TPeak_60)/(T450_0−T450_60)≤1.5 (1)
in Relationship (1),
TPeak_0 (front absorption peak) is lowest value among color transmittances measured in a direction perpendicular to a plane direction of the prism sheet,
TPeak_60 (lateral absorption peak) is lowest value among color transmittances measured in a direction at an angle of 60° to the perpendicular direction,
T450_0 (front blue transmittance) is color transmittance at a wavelength of 450 nm measured in the perpendicular direction, and
T450_60 (lateral blue transmittance) is color transmittance at a wavelength of 450 nm measured in the 60° direction;
in order to measure the color transmittance of the front blue transmittance and the color transmittance of the lateral blue transmittance, a light source that emits white light with a continuous emission spectrum is prepared, a spectral intensity (L1) of light from the optical composite sheet is measured when light from the light source passes through the optical composite sheet, a reference sheet is prepared by removing the light absorbing layer from the optical composite sheet, a spectral intensity (L0) of light from the optical composite sheet is measured when light from the light source passes through the reference sheet, and the color transmittance of the front blue transmittance and the color transmittance of the lateral blue transmittance are each a value obtained by dividing L1 by L0.
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