Photography – Folding or collapsible camera – Having axially moving lens
Reexamination Certificate
2002-03-04
2003-10-28
Mahoney, Christopher (Department: 2851)
Photography
Folding or collapsible camera
Having axially moving lens
Reexamination Certificate
active
06637951
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lens device, and in particular relates to a lens device used for a collapsible camera having a zoom function.
2. Description of the Related Art
A cam mechanism is known as a device which moves a lens holding member for holding a moving lens in a zoom lens device along an optical axis. The cam mechanism is composed of a cam follower projecting and provided on an outer peripheral surface of the lens holding member, a cam groove formed on an inner peripheral surface of a cam barrel to be engaged with the cam follower, and a straight guide for stopping the rotation of the lens holding member and guiding the lens holding member in moving straight. The lens moves straight along the optical axis by a displacement in the cam groove along the optical axis by rotation of the cam barrel.
There are various mechanisms for the straight guide for guiding the lens holding member in straight motion, including a mechanism with a construction for guiding a lens holding member by engaging a cam follower with a guide groove formed on the inner peripheral surface of a fixed barrel, and a mechanism with a construction for guiding a lens holding member by engaging a slider formed on the lens holding member with a guide bar disposed along the optical axis.
The present inventor has proposed a construction in Japanese Patent Application Publication No. 2001-100083 published on Apr. 13, 2001, in which an arm is provided on a tip of a rear lens group holding member, and a projection formed on the tip of the arm is engaged with a straight guide groove formed on the inner peripheral surface of a front lens group holding member to be guided.
However, with the above-described construction, because the straight guide groove is provided on the front lens group holding member, if a pressing impact is applied to the front lens group holding member when, for example, the camera drops, a twisting force is applied to the arm and straight guide groove by the cam, thus causing a possibility that the projection disengages from the straight guide groove. In particular, in recent years, there are requests for more compact lens devices, and therefore, the lens holding member with less wall thickness is used for constituting the lens device. This limits the depth of the groove, and there has been a possibility of disengagement of the projection from the groove even on a small impact.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances, and its object is to provide a lens device with a simple configuration that is able to prevent a guide member from being disengaged from a guide groove for guiding a lens holding member in moving straight.
In order to achieve the above-described object, the present invention is directed to a lens device, comprising: a lens holding member that holds a lens, a guide groove parallel to an optical axis being formed on a peripheral surface of the lens holding member; and a guide member engaged with the guide groove of the lens holding member, the guide member movably guiding the lens holding member along the optical axis, wherein a projecting thread portion is formed on a sidewall of the guide groove along the direction of the optical axis, and a recessed thread portion to be engaged with the projecting thread portion of the guide groove is formed on the guide member.
The present invention is also directed to a lens device, comprising: a lens holding member that holds a lens, a guide groove parallel to an optical axis being formed on a peripheral surface of the lens holding member; and a guide member engaged with the guide groove of the lens holding member, the guide member movably guiding the lens holding member along the optical axis, wherein a recessed thread portion is formed on a sidewall of the guide groove along the direction of the optical axis, and a projecting thread portion to be engaged with the recessed thread portion of the guide groove is formed on the guide member.
According to the present invention, the projecting thread portion or the recessed thread portion provided on the guide groove is engaged with the recessed thread portion or the projecting thread portion provided on the guide member; therefore, even if a twisting force is applied to the guide member and the guide groove, the guide member is not disengaged from the guide groove.
Preferably, a tip side portion and a base side portion of the guide member which are oppositely placed with respect to the recessed thread portion of the guide member are formed to have the same widths. Hence, strength of the guide member is not reduced even if the recessed thread portion is formed on the guide member.
REFERENCES:
patent: 6049432 (2000-04-01), Machida et al.
patent: 6208809 (2001-03-01), Kanai et al.
patent: 6256458 (2001-07-01), Iwasa
patent: 6437924 (2002-08-01), Azegami
patent: 6469840 (2002-10-01), Nomura et al.
patent: 6483994 (2002-11-01), Kabe et al.
patent: 2003/0007796 (2003-01-01), Nomura et al.
patent: 2001-100083 (2001-04-01), None
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Optical Co., Ltd.
Mahoney Christopher
LandOfFree
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