Optical: systems and elements – Lens – With variable magnification
Patent
1992-03-20
1995-02-21
Ben, Loha
Optical: systems and elements
Lens
With variable magnification
359694, 359696, 359823, 354400, G02B 1514
Patent
active
053921593
ABSTRACT:
In a zoom lens device of a two-lens group structure, positive and negative lens groups are sequentially arranged from a photographing field side. The zoom lens device has a controller for controlling a rear focusing operation for moving the negative lens group on a high magnification side. The controller also controls one of an entire drawing-out focusing operation for moving the positive and negative lens groups, and a front focusing operation for moving the positive lens group on a low magnification side. The high and low magnification sides are respectively set to telescopic and wide angle sides. A focal length of the zoom lens device is increased on the high magnification side and is decreased on the low magnification side. Thus, a zoom ratio is increased and a lens drawing-out amount is reduced on the telescopic side so that the zoom lens device can be made compact. A driving device of a varifocal lens having a two-lens group structure has a base frame and a rear group holding frame for respectively holding front and rear lens groups and moved in accordance with zooming and focusing control states of the varifocal lens.
REFERENCES:
patent: 4950061 (1990-08-01), Tsurukawa et al.
patent: 5005956 (1991-04-01), Kaneda et al.
Hongo Takashi
Sasaki Saburo
Terui Hiroshi
Tsurukawa Ikuya
Ben Loha
Phan James
Ricoh & Company, Ltd.
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