| 摘要 |
PROBLEM TO BE SOLVED: To provide a picture projection device being suitable for a liquid crystal projector having high utilizing efficiency of light. SOLUTION: This picture projection device is provided with a color separation system 5 separating a light beam emitted from a lamp unit 101 to the plural color light beam, plural liquid crystal panels 9 modulating the respective color light beams R, G and B separated by the separation system 5 based on an image signal, a color synthesis system DP synthesizing the color light beams emitted from the respective panels 9 to one light beam and a projection lens 12 projecting the light beam synthesized by the synthesis system DP on a screen 13. Then, the synthesis system DP is composed of a cross dichroic prism obtained by forming a dichroic film at the sticking surfaces of four prisms and the respective beams R, G and B made incident on the cross dichroic prism are the straight-line polarized light beams. When an angle formed by the polarizing direction of a color light component transmitted through all the dichroic films and that of the color light component reflected on the dichroic films once is defined as θ, the expression of 0 deg.<θ<90 deg. is satisfied. |
