| 摘要 |
<p>Projection lens systems (13) for use in CRT projection televisions (10) are provided. From the screen side, the systems have three lens units (U1, U2, U3), the first two units (U1, U2) forming a retrofocus lens and the third unit (U3) being associated with the CRT during use and serving to correct field curvature. At its screen end, the first lens unit (U1) has a negative element (E1) which has a screen surface (S1) which is concave to the screen. The second lens unit (U2) has two positive subunits (US1, US2), the first subunit (US1) being a color correcting doublet composed of glass and the second subunit having a positive lens element (E2) at its screen end. The projection lens systems are fully color corrected, have f/♯'s of 1.0 for an infinite conjugate, have half fields of view of at least 25°, and are economical to manufacture.</p> |
