Patent ID: 8449166

Claim:
An image source unit comprising: an image source outputting an image; and an optical sheet disposed closer to an observer than the image source and having a plurality of layers to control light from the image source and transmit the light to the observer side, wherein the optical sheet comprises an optical functional layer comprising: a light-transmitting portion having a trapezoidal cross section, having a refractive index of N p and being arranged along a sheet face to transmit the light; and a low refractive-index portion having a wedge shape cross section, having a refractive index of N b , and being arranged between the light-transmitting portions, and an oblique side of the wedge shape cross section of the low refractive-index portion forms an angle of θ b with respect to a normal line of the sheet face, and when a half-value angle of a divergence angle of image light from the image source is set to θ 0 and a refractive index of air is set to N 0 , N p >N b and the following equation are satisfied. sin - 1 ⁢ N b N p ≦ 90 ⁢ ° - { sin - 1 ⁡ ( N 0 N p · sin ⁢ ⁢ θ 0 ) + θ b }