| 摘要 |
PROBLEM TO BE SOLVED: To enable a projection type liquid crystal display device using cross- dichroic prism as a color synthesis optical system to prevent a projection image from deteriorating in picture quality and display an excellent projection image. SOLUTION: Two dichroic surfaces 13, 14 in the cross-dichroic prism 8 are formed so that the incident angle of red light mainly reflected by the red- reflection dichroic surface 13 forms 60 degrees to a red reflecting dichroic surface 13 and that of blue light mainly reflected by the blue-refection dichroic surface 14 forms 60 degrees to the blue-reflection dichroic surface 14. A part of color light flux which is reflected by the dichroic surface 13, 14 but passes through them without being reflected is not made incident on the back of liquid crystal display element of the other color light. Further, divergent component of the light flux is reflected on a side surface of the cross-dichroic prism 8 and is not made incident on the projection lens 9, and thus, ghost image is not generated on a screen. |
