A projection-type display apparatus including an elliptical condenser mirror having a concave reflecting surface consisting of part of a substantially elliptical surface, a light source arranged near a first focal point of the elliptical surface, a collimator lens having a focal point near a second focal...http://www.google.com.tw/patents/US5982563?utm_source=gb-gplus-share專利 US5982563 - Projection-type display apparatus
