PLANAR LIGHT EMITTING DEVICE, OPTICAL ELEMENT AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

Using a distance L between the centers of light sources 12, 12; a refractive index n of an optical element 15; a thickness d of the optical element; a distance W from the center of the light source to the optical element; a refractive index no of air; an angle of incidence ¸ 1 of light emitted from the light sources and coming into the optical element, relative to the direction of optical axes; an angle of refraction ¸ 2 of light, incident on the optical element, in the optical element; a diameter of each light source as D; and a maximum tangential angle a formed between a tangential line in contact with an outer surface of a luminance distribution generating layer 18 and a plane orthogonal to the optical axes, there is included a maximum tangential angle a satisfying x>L/2-D/2 when calculating a travel range x of a split image of the light sources in a direction normal to the optical axes using (1) n 0 sin(a)=nsin(a-¸ 2 ), (2) n 0 sin¸ 1 =nsin¸ 2 and (3) x=Wtan¸ 1 +dtan¸ 2 . This facilitates uniformalizing of front luminance distribution.