1985-12-04
1987-11-03
Corbin, John K.
350412, 350469, G02B 958, G02B 1318, G02B 2718
Patent
active
047040092
ABSTRACT:
A projection lens having a large aperture ratio has 3 units for projecting an enlargemen of an image appearing on a CRT onto a screen. The first unit from the screen has a negative power so that the entrance pupil is moved toward the screen to thereby improve off-axis vignetting factor. The second unit consists of two positive power lens elements so that the positive power of the entire system is shared by the second unit and the temperature characteristic is improved by using a positive power glass lens element as one of the two positive power lens elements. The third unit has a negative power to correct curvature of field.
REFERENCES:
patent: 4300817 (1981-11-01), Betensky
patent: 4348081 (1982-09-01), Betensky
patent: 4620773 (1986-11-01), Fukuda
Miyatake Yoshito
Nagaoka Yoshitomi
Nakajima Yasuo
Ono Syusuke
Yamamoto Yoshiharu
Corbin John K.
Gass Rebecca D.
Matsushita Electric - Industrial Co., Ltd.
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