| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a projection optical system that magnifies and project an image from a DMD onto a screen, is bright, has a small lens aperture, is low in cost and optimum for a projection display device of small type. <P>SOLUTION: The projection optical system comprises: in order from a magnifying side; a first optical system with one mirror face; and a second optical system comprising, in order from the magnifying side, a first lens group having negative or positive refractive power as a whole and a second lens group having positive refractive power as a whole. The first lens group comprises, in order from the magnifying side, a 1a-th lens group having negative refractive power as a whole and a 1b-th lens group having positive refractive power as a whole. The second lens group comprises: a 2a-th lens group having negative or positive refractive power as a whole and a 2b-th lens group having positive refractive power as a whole. The 1a-th lens group comprises negative, negative, positive, and negative lenses, and the 1b-th lens group comprises one or two positive lenses. The 2a-th lens group comprises a negative lens, one or two positive lenses, and a negative lens, and the 2b-th lens group comprises one positive lens or comprises a positive or negative lens and a positive lens arranged after the positive or negative lens. <P>COPYRIGHT: (C)2013,JPO&INPIT |
