| 摘要 |
PROBLEM TO BE SOLVED: To easily exchange the polarizing plate of a liquid crystal display board. SOLUTION: Red, green and blue light beams separated from a white light beam are made incident on the liquid crystal display boards 2B, 2G and 2R through a polarizing film 1. The light beams modulated according to respective color video signals and emitted are fetched through a polarizing film 3, composited by a dichroic prism 4, and projected to a screen by a projection lens 5. The films 1 and 3 are roll type ones and wound round rotary shafts 1a and 3a. While they are guided by rollers 6a, 6b, 6c and 6d, they pass on three liquid crystal display boards and are taken up to take-up shafts 1b and 3b. When the performance of the polarizing film is deteriorated, the take-up shafts 1b and 3b are rotated by the operation of a handle or the driving of a motor so as to take up the already used part of the polarizing film. By setting the parts of the rotary shafts 1a and 3a and the take-up shafts 1b and 3b as a cartridge type, the polarizing film where the unused part does not exist is easily exchanged. |
