Photography – Having variable focal length of camera objective – Having focus operation
Reexamination Certificate
1999-09-07
2001-05-29
Perkey, W. B. (Department: 2851)
Photography
Having variable focal length of camera objective
Having focus operation
Reexamination Certificate
active
06240254
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a zoom camera and, more particularly, to a zoom lens barrel driving system for a lens shutter type camera which can effectively perform the zooming and focusing operations only with one driving source.
2. Description of the Related Art
Generally, compact zoom cameras have a zoom lens barrel driving system with a zooming function of varying magnification, i.e., of varying the focal length of photographing lens, and a focusing function of controlling the focal point in view of the distance between the lens and the object.
Such a zoom lens barrel driving system is disclosed in U.S. Pat. Nos. 4,936,664, 5,602,608 and 5,687,029, respectively.
U.S. Pat. No. 4,936,664 discloses a zoom lens barrel driving system where the zooming and focusing operations are preformed by a zoom motor for varying magnifications and a focus motor for controlling the focus, respectively.
FIG. 17
is a graph illustrating the relation of the focal lengths controlled by one driving source to the focal points controlled by another driving source. In the drawing, the horizontal axis line indicates barrel rotation angles, the vertical axis upper-side line indicates focal lengths, and the vertical axis lower-side line indicates focal points. When one motor is driven to vary the focal length, barrel components rotate so that continuous zooming ratio variation occurs from a wide-angle position (Wide) to a telephoto position (Tele) or from the Tele position to the Wide position. In contrast, when another motor is driven to vary the focal point, a focus lever mounted within a shutter block rotates at a predetermined angle within the focusing area to thereby perform the focus controlling operation. In this structure, the zooming and focusing operations are separately performed.
U.S. Pat. No. 5,602,608 discloses a zoom lens barrel system where the zooming, focusing, film winding, and film rewinding operations are performed with one driving source by using separate selection gear mechanisms.
U.S. Pat. No. 5,687,029 also discloses a zoom lens barrel system where the zooming and focusing operations are performed with one driving source. Particularly, in the system, a plurality of grooves are repeatedly formed within the barrel to realize the zooming and focusing areas.
FIG. 18
illustrates the relation of the zooming area to the focusing area. In the drawing, the horizontal axis line indicates barrel rotation angles, the vertical axis upper-side line indicates focal lengths, and the vertical axis lower-line indicates focal points. The focusing lengths can be selected step by step at the setting position and the optical field can be realized in accordance with the selected focal lengths. In the optical field realizing area shown in the drawing with a solid line, a front or rear lens group moves along the grooves formed at the barrel so that the focusing position is determined in the area between the near focal point and the infinite focal point.
The zoom lens barrel system disclosed in U.S. Pat. No. 4,936,684 has good efficiency in control because it uses a DC motor having high driving power as the driving source for the zooming operation, and a stepping motor capable of easily providing position-control as the driving source for the focusing operation, but causes an increase in the production cost. The zoom lens barrel system disclosed in U.S. Pat. No. 5,602,608 has a disadvantage in that the complicated structure of the separate selection gear mechanisms is inappropriate for the compact camera use. Furthermore, the zoom lens barrel system disclosed in U.S. Pat. No. 5,687,029 has a disadvantage in that the grooves formed in the barrel affect the operation of the barrel so that inappropriate areas for the photographing optical field are present, making it difficult to perform a continuous zooming operation or to realize a multi-stepped magnification area.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a camera with a zoom lens barrel driving system which realizes the zooming and focusing operations only with one driving source, resulting in elevated system stability and reduced production cost.
It is another object to provide a camera with a zoom lens barrel driving system which has simple but sophisticated zooming and focusing structures.
It is still another object to provide a camera with a zoom lens barrel driving system which has a minimized size with the smallest number of components.
These and other objects may be achieved by a zoom lens barrel driving system for a camera including a driving source, a magnification controlling unit, and a focus controlling unit. The magnification controlling unit is formed with a plurality of barrels and a plurality of lens groups. The barrels and the lens groups move in an optical axis direction upon receipt of a driving power from the driving source such that the magnification continuously varies. The focus controlling unit is formed with the lens groups. The lens groups repeatedly move between a near focal position and an infinite focal position in the optical axis direction in synchronization with variations in the magnification to perform a focus controlling operation.
For instance, the components of the zoom lens barrel driving system may be specified as follows. A motor is mounted within a camera body as the driving source. A plurality of power transmitting gears is connected to the motor. A lens base is fixed to the camera body. The lens base has an internal periphery with a plurality of female helicoid threads and a plurality of linear guide grooves in an optical axis direction. A barrel idle gear is fixed to the lens base. The barrel idle gear engages the neighboring power transmitting gear to receive driving power from the motor via the power transmitting gears. A helicoid ring has an external periphery with a plurality of male helicoid threads and a plurality of spur gear threads, and an internal periphery with a plurality of female helicoid threads. The male helicoid threads of the helicoid ring engage the female helicoid threads of the lens base such that the helicoid ring rotates and linearly moves in the optical axis direction. The spur gear threads engage threads of the barrel idle gear such that the helicoid ring rotates and linearly moves in the optical axis direction upon receipt of driving power through the barrel idle gear. A guide plate is combined with the helicoid ring. The guide plate rotates relative to the helicoid ring and linearly moves along the linear guide groove of the lens base in the optical axis direction. The guide plate has a front end with a plurality of linear movement guide members extended in the optical axis direction, each with a predetermined length. Each of the linear movement guide members has a side with a plurality of cam surfaces. A zoom ring has an external periphery with a plurality of male helicoid threads. The male helicoid threads of the zoom ring engage the female helicoid threads of the helicoid ring such that the zoom ring linearly moves in the optical axis direction with the guidance of the linear movement guide member. A rear cam is combined with the zoom ring. The rear cam rotates and linearly moves in the optical axis direction in accordance with the movement of the helicoid ring. A rear lens group is mounted within the zoom ring. The rear lens group moves in the optical axis direction in synchronization with the rear cam. A shutter block is fixed to the zoom ring to control the quantity of light. A front lens group is mounted within the shutter block. The front lens group rotates and linearly moves in the optical axis direction. The front lens group is dynamically connected to the shutter block via a coil spring such that the rotation of the front lens group is defined. A cam lever is provided at an eccentric position of the shutter block. The cam lever repeatedly rotates in a predetermined area in synchronization with the focus cam surface of the guide plate. The cam lever has a first rotating arm con
Choi Yong-hag
Jo Nae-Jin
Kim Jin-hwan
Lee Seon-Ho
Mun Byung-Jun
Alston & Bird LLP
Perkey W. B.
Samsung Aerospace Industries Ltd.
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