| 摘要 |
A beam-split system of an LCD projecting apparatus for improving the contrast effect receives light from the light source of the LCD projecting apparatus and signal of an image to be projected, and outputs images to be projected. The beam-split system includes a plurality of polarizing filters, a plurality of polarization beam splitters (PBS), and three sets of LCD panels. The polarizing filters are for transferring a polarization state of a specific color beam. The PBSs are disposed in the light-path where the polarizing filter located, and each of PBSs includes a pair of prisms for splitting the color polarizing light beam that is incident through the PBS. The LCD panels are to reflect respectively the above-mentioned polarizing light beams having three different colors, and in the meantime, change their polarization state. The characteristics of the beam-split system is as follows: at least a peripheral wall, among those peripheral walls of each of the prisms of the PBS not being passed by the light path, is a polished surface. This is to make most of the stray light beam, that is incident upon the polished surface in the beam-split system, transmit through the polished surface. Therefore, it can greatly reduce the stray light beam in the beam-split system, and diminish the signal noise of the output light, and enhance the contrast effect of the output images.
|
