To provide a condensable diffusion plate which is simple in structure, makes printing dot patterns invisible and has sufficiently front surface luminance by providing on surface of this plate with a light diffusive structure consisting of a layer which has a condensable structure arranged with columnar materials consisting of a triangular shape in section in the form of straight ridges and is embedded with air in the surface on the opposite side thereof.
This condensable structure is formed by arranging the columnar materials consisting of the triangular shape in the section in the form of the straight ridges on one surface of a sheet. The vertex angle of the triangular shape is preferably 80 to 120° and the triangular shape slightly rounded at the vertex angle is equally well. The base size is 30 to 100μm and the thickness is adequately about 150 to 200μm. The sheet is preferably made of acrylic, polycarbonate and polyester synthetic resins, etc., and the resins denatured to have a high refractive index are more adequate. On the other hand, the opposite side of the condensable structure surface includes the light diffusive structure consisting of the layer embedded with the air.
YAMAZAKI YOSHINOBU
TERAKADO FUMIYA
KAWAGUCHI OSAMU
KOSUGI TAKUMI
OHARA SHUZO
HIROSE JUNGO
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