Photography – With exposure objective focusing means – focusing aid – or... – Manually selected preset focus position or range
Reexamination Certificate
1999-05-28
2001-01-23
Perkey, W. B. (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Manually selected preset focus position or range
Reexamination Certificate
active
06178295
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lens movement control device, which is provided in an automatic focusing device of a camera, to control a range within which focusing lens groups are moved.
2. Description of the Related Art
Generally, in an ultra-telephoto lens, which is detachably mountable on a camera body, a moving amount of the lens is greater than a normal interchangeable lens. Therefore, if the focusing lens groups are always moveable over the whole range, it might take a long time using an automatic focusing adjustment to obtain an in-focus condition, since a range over which the focusing lens groups are moved is too large. Accordingly, an interchangeable lens, which is provided with a focus limiter by which a moving range of the focusing lens groups is restricted, is proposed.
A conventional focus limiter is constructed in such a manner that a limiter member is extended, by rotating a focus limiter switch, to a position at which the limiter member interferes with support members of the focusing lens groups, so that the moving ranges of the focusing lens groups are restricted (Japanese Unexamined Utility Model Publication No. 63-70519, for example).
However, as the conventional focus limiter has a mechanical member, a number of members is great, thus increasing the manufacturing cost.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a lens movement control device, in which a moving range of focusing lens groups is restricted without using a mechanical focus limiter, so that a cost of the lens movement control device is reduced.
According to the present invention, there is provided a lens movement control device a lens moving mechanism, an electrical switch and a lens position sensing system.
The lens moving mechanism moves focusing lens groups, provided in a photographing lens, along an optical axis thereof. The electrical switch electrically determines a focusing range within which the focusing lens groups can be moved. The lens position sensing system electrically senses lens position information regarding positions of the focusing lens groups on the optical axis. The lens moving mechanism moves the focusing lens groups within the focusing range, based on the lens position information and the focusing range.
Further, according to the present invention, there is provided a lens movement control device comprising a lens moving mechanism, a distance information output system and a lens movement limit system.
The lens moving mechanism moves focusing lens groups, provided in a photographing lens, along an optical axis thereof. The distance information output system outputs an electric signal corresponding to a position of at least one of the focusing lens groups. The lens movement limit system controls the lens moving mechanism to stop a movement of at least one of the focusing lens groups, based on the electric signal.
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patent: 5479234 (1995-12-01), Kitaoka
patent: 5899586 (1999-05-01), Kawanami
patent: 63-70519 (1988-05-01), None
Iikawa Makoto
Nakata Masahiro
Sato Osamu
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Perkey W. B.
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