Optical: systems and elements – Lens – With field curvature shaping
Patent
1993-03-30
1994-05-03
Groody, James J.
Optical: systems and elements
Lens
With field curvature shaping
359648, 348781, G02B 300, H04N 931, H04N 916
Patent
active
053092830
ABSTRACT:
A projection lens system for projecting an image from a cathode ray tube (CRT) onto a screen is provided which includes in order from the image end: a first lens unit (U1), a second positive lens unit (U2) which may include a color correcting doublet, a corrector lens unit (CR), and a third negative lens unit (U3) which is associated with the CRT during use. The first lens unit preferably has a hybrid construction and includes: a first lens element (L1) composed of glass and having spherical surfaces, a second lens element (L2) composed of plastic and having at least one aspherical surface, and a third lens element (L3) also composed of plastic and having at least one aspherical surface. L1 has substantially more optical power than either L2 or L3, e.g., .vertline.f.sub.L2 .vertline./f.sub.L1 and .vertline.f.sub.L3 .vertline./f.sub.L1 are each above 1.3. In this way, the lens system is easily fabricated and is relatively insensitive to changes in temperature of the lens elements. The lens system is applicable to both rear and front projection televisions.
REFERENCES:
patent: 4989961 (1991-02-01), Yoshioka
patent: 5015076 (1991-05-01), Ueda
patent: 5066113 (1991-11-01), Nakajima et al.
Burgess Glenton B.
Groody James J.
Klee Maurice M.
U.S. Precision Lens Incorporated
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