| 摘要 |
PROBLEM TO BE SOLVED: To erase a ghost image occurring in the case a light ray reflected on an emitting surface of a total reflection type Fresnel lens used as a screen reenters into the screen through a turn back mirror in an optical projection path of a rear projection television, or to lower the ghost image to a level that can not be identified by the naked eye, and to improve the quality of a projection image. SOLUTION: A treatment for improving the transmission rate or a satin treatment is carried out for the emitting surface of the total reflection type Fresnel lens used as the screen, and the amount of the reflected light ray on the emitting surface of the total reflection type Fresnel lens, which causes the ghost image to occur, is reduced. Furthermore, the angle of a reflecting plane in a prism section of the total reflection type Fresnel lens is set so that the light ray reflected on the emitting surface of the total reflection type Fresnel lens cannot reenter into the screen even in the case the light ray is reflected again by the turn back mirror.
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