| 摘要 |
PURPOSE:To form an optical path bending prism which is put near a CRT and a compact and high-performance bending type video projection by forming an optical system of six groups of lenses which meet specific requirements. CONSTITUTION:The 4th group of positive lenses with radii r7 and r8 of curvature is added to the triplet consisting of the 1st group of positive lens with r1 and r2, the 2nd group of negative lenses with r3 and r4, and the 3rd group of positive lenses with r5 and r6 successively from a screen side to constitute a four-group lens system which has a large aperture ratio, high aberration compensating ability, and focal length fF. A bending prism P having optical length L is provided right behind the lens system, the aperture ratios of the 5th group of positive lenses with radii r9 and r10 of curvature and the 6th lens group of negative lenses with r11 and r12 are increased, and an optical system for improving aberration ability is provided at the side of the CRT. Those six lens groups form an optical system having facal length (f), and the optical requirements shown by inequalities I -IV are met to form the compact, high-performance bending type video projector. |
