PURPOSE: To make a distance of a depth direction of a projection system small, and to make a projector thin, by constituting so that a linear Fresnal lens face is positioned in a projection side of a screen body having a circular Fresnel lens face.
CONSTITUTION: A lens body 2 having a linear Fresnel lens face 21 is positioned in a projection side of a screen body 1 having a circular Fresnel lens 11. Also, an inclination of the linear Fresnel lens face 21 is designed to a prescribed angle, and also light which is made incident to the screen body 1 is not made parallel to an optical axis, but is shifted by a specified angle and is made incident. In this way, light emitted from an emitting point C advances like D→D'→B, E→E'→B and F→F'→B, and is condensed to a point B. By displacing a position of the emitting point C in this way, it is possible to make a distance of a depth direction of a projection system as small as possible, and to make a projector thin.
TAKAHASHI HIDEO
INOUE MASAO
SUZUKI SHINGO
