| 摘要 |
<p>A projection lens (20) for projecting an enlargement of an image in a light valve (30) onto a screen (12) in a light valve projection system has, in succession from the light valve side, first, second and third lens groups (G1, G2, G3) whose relative powers lie within prescribed ranges which are such that a space is determined between the second and third groups (G2, G3) in which a mirror (40) is disposed that folds the optical path through the lens. In a rear projection system, a compact cabinet (10) can then be achieved. For a full colour projection system using the projection lens together with three light valves, each illuminated with light of a different colour, optical combining means (24) for combining the three light valve outputs is accommodated between the light valves and the second lens group. In a single light valve system, a further mirror may precede the second lens group.</p> |
