Optical: systems and elements – Lens – With variable magnification
Reexamination Certificate
2002-07-16
2003-10-28
Mack, Ricky (Department: 2873)
Optical: systems and elements
Lens
With variable magnification
C359S700000
Reexamination Certificate
active
06639731
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a zoom lens of a camera, and more particularly to a zoom lens barrel assembly of a camera.
BACKGROUND OF THE INVENTION
A telescoping type of zoom lens having a plurality of concentrically arranged moving barrels is Well known. This type of zoom lens is widely utilized in a camera for reducing the thickness of the camera when it is not in use. The conventional zoom lens is formed of a fixed barrel, an outer barrel fitted into the fixed barrel and a plurality of moving barrels. The outer barrel is provided on the inner peripheral surface thereof with a plurality of cam grooves for receiving therein a plurality of cam follower pins. Various moving barrels are fitted into the outer barrel for housing a first group of lenses and a second group of lenses. When the outer barrel is driven to move and rotate relative to the fixed barrel, the outer barrel can carry the moving barrels to move along the direction of the optical axis. Thereby, the optical system of the camera is formed.
The driving system for controlling the movements of the barrels is different from that for controlling the motions of the shutter. For example, the shutter, which is mounted in one of the moving barrels, is driven by a step motor. When the first group and the second group of lenses are moved to respective positions corresponding to a set focal length by the moving barrels, the shutter is driven by the step motor for taking a photograph, which is well known to one skilled in the art.
Please refer to
FIG. 1
, which is a longitudinal section view of the conventional zoom lens barrel. As shown in
FIG. 1
, a middle barrel
104
is fitted into the outer barrel
103
to relatively move. A guide ring
105
is mounted on the front end of the middle barrel
104
for guiding the linear moving barrel
102
to move along the direction of the optical axis. Three cam follower pins
107
are respectively mounted in the penetrated holes
1051
of the guide ring
105
to be served as supporters in the conventional method for keeping the moving range of the optical system. Recently, the camera has a design tendency of long focal length and wide moving range of the zoom lens barrels. However, when the rotating angle of the outer barrel is too small, the guide grooves formed on the inner periphery of the outer barrel
103
must be designed to have cliffy oblique angle. In this situation, the torque for rotating the outer barrel
103
will go beyond the requirement. Therefore, the conventional zoom lens barrel structure is unstable.
Certainly, in order to increase the moving range of the optical system and allow the cam follower pins
107
to rotate at a total rotating angle larger than
120
, the gradient of the guide grooves of the outer barrel
103
is released. However, keeping the moving range of the cam follower pins
107
along the direction of optical axis would lead to the assembly of the guiding ring
105
and the middle barrel
104
hard. Recently, in order to solve the above-mentioned problems and allow the middle barrel
104
to rotate at a rotating angle larger than
120
, the guide ring
105
is provided with a hook structure
1052
as shown in FIG.
2
. However, in order to avoid the disengagement of the guide ring
105
and the middle barrel
104
, the guide ring
105
must employ at least three hooks to hook the front end of the middle barrel
104
. However, the hooks will deform and the guide ring
105
will disengage from the linear moving barrel
104
when a powerful external force is exerted upon the guide ring
105
.
In addition, when the hooks are respectively forced to engage with the middle barrel
104
, those parts will result in deformation due to the powerful external force. Therefore, it is required to reserve a buffer space. However, such design will result in the existence of the.clearance between those parts and derivate native influences on the optical system of a camera.
Therefore, it is desired for the applicant to develop a suitable zoom lens barrel assembly, which allows the middle barrel
104
thereof to move linearly and rotate in a rotating angle larger than
120
, allows the guide ring
105
thereof to move with the middle barrel
104
along the direction of optical axis, and employs a plurality of cam follower pins
101
to guide the middle barrel
104
to move along the direction of optical axis. And, the cam follower pins can be respectively assembled with the guide ring
105
and middle barrel
104
simply and correctly without exerting a powerful external force upon the cam follower pins
101
.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a zoom lens barrel assembly which allows the middle barrel thereof to move linearly and rotate in a rotating angle larger than
120
, allows the guide ring thereof to move with the middle barrel along the direction of optical axis, and employs a plurality of cam follower pins to guide the middle barrel to move along the direction of optical axis.
To achieve the object of the present invention, a zoom lens barrel is provided. The zoom lens barrel includes a moving barrel provided on the outer peripheral surface of the front portion thereof with a flange and a circumferential groove adjacent to the flange, a guide ring having at least one penetrated hole on the outer peripheral surface thereof and a slider way therein, and at least one cam follower pin having one end piercing through the penetrated hole of the guide ring and disposed in the circumferential groove of the moving barrel. The flange of the moving barrel is received in the slider way of the guide ring and limited by the end of the cam follower pin, thereby the guide ring is rotatably mounted on the front portion of the moving barrel.
Preferably, the cam follower pin has a semicircle-shaped projection and a flat surface on the end. More preferably, the other end of the cam follower pin has a taper portion.
There is further an object of the present invention to provide a zoom lens barrel assembly. The zoom lens barrel assembly includes: an outer barrel provided on the inner peripheral surface thereof with at least one key guide groove and at least one cam groove; a middle barrel fitted into the outer barrel and provided on the outer peripheral surface of the front portion thereof with at least one guide key, a flange and a circumferential groove adjacent to the flange, wherein the guide key is positioned in the key guide groove of the outer barrel; a middle guide ring rotatably mounted on the front end of the middle barrel, and having at least one penetrated hole on the outer periphery thereof and a slider way therein; at least one cam follower pin, one end of which is piercing through the penetrated hole of the guide ring and disposed in the circumferential groove of the middle barrel and the other end of which is movable disposed in the cam groove of the outer barrel; and an inner barrel fitted into the middle barrel.
In accordance with one aspect of the present invention, the zoom lens barrel assembly further includes a fixed barrel provided on the inner peripheral surface thereof with female helicoids which are engaged by male helicoids formed on the outer peripheral surface of the outer barrel.
Preferably, the key guide groove is extending parallel to the direction of optical axis and the cam groove is formed oblique to the optical axis.
Preferably, the guide key of the middle barrel is projecting outwardly from the middle barrel in a radial direction.
In accordance with another aspect of the present invention, the flange of the middle barrel is provided on the outer peripheral surface of the front end of the middle barrel.
In accordance with another aspect of the present invention, the zoom lens barrel assembly further includes a first guide plate secured to the middle guide ring by screws.
In accordance with another aspect of the present invention, the first guide plate has a plurality of L-shaped guide projections respectively inserted into the rectangle guide channels formed on the
Mack Ricky
Madson & Metcalf
Primax Electronics Ltd.
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