Photography – Having variable focal length of camera objective – Power zoom
Reexamination Certificate
1999-03-08
2002-01-15
Gray, David M. (Department: 2851)
Photography
Having variable focal length of camera objective
Power zoom
C396S349000
Reexamination Certificate
active
06339682
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a camera having a type of zoom lens in which a lens barrel can be collapsed in a camera body.
2. Description of the Related Art
Non-lens-interchangable type compact cameras having a zoom lens mechanism have recently been placed on the market. For example, a camera of this type, such as that shown in
FIG. 11
, is known.
In the camera shown in
FIG. 11
, the positions of fore and rear groups of a photographing optical system are controlled with one cam ring
201
and a straight-drive cam
202
to position the two lens groups at focal distances which change continuously. A gear
201
a
is formed on a rear outer-circumferential portion of the cam ring
201
. The gear
201
a
is driven with a gear
203
to which a driving force is transmitted from a power source to perform zooming.
In the arrangement shown in
FIG. 11
, the whole lens barrel including the cam ring
201
and the straight-drive cam
202
can be collapsed in the body by an operation using a retraction cam ring
205
and a retraction straight-drive cam
204
slidably engaging with a pin
204
′ embedded in the straight-drive cam
202
.
The conventional zooming mechanism shown in
FIG. 11
entails the following problems.
(a) To prevent the outer circumferential gear portion
201
a
provided on the cam ring
201
from interfering with an inner circumferential portion of the straight-drive cam
204
when the lens barrel is collapsed, it is necessary to increase the diameters of the cam
204
and the cam ring
205
. However, the overall size of the camera is increased if the cam
204
and the cam ring
205
are increased.
(b) To maintain the engagement between the gear
203
and the gear
201
a
while the lens barrel is retracted, it is necessary to extend the gear portion
201
a
of the cam ring
201
as indicated at
201
b
. However, if such an extended gear portion
201
b
is provided, it must be covered with an outer casing portion of the camera so that it is not exposed outside the camera even when put out from the collapsed position, resulting in an increase in the outside diameter of the lens barrel cover.
(c) If the cam ring
201
is exposed outside when the lens barrel is put out from the collapsed position, the cam ring
201
having the rotating cam groove can be seen from the outside so that the appearance of the camera is marred and, moreover, there is a risk of a light leak through the cam groove. To prevent this risk, it is necessary to form an outer casing
206
so as to cover the cam ring
201
and the straight-drive cam
202
. This design has a contrary effect; the thickness of the camera is increased in comparison with conventional cameras, although the lens barrel unit can be collapsed in the camera body.
The applicant of the present invention has proposed a camera disclosed in Japanese Patent Application No. 1-320130 (now, Japanese Laid-Open Patent No. 3-180826) to solve this problem.
The zoom lens barrel of this camera is generally constituted of three lens groups. The positions of the first and second lens groups are controlled by the rotation of a cam ring, and the third lens group is driven by another driving mechanism. These three lens groups are operated for zooming, and the third lens group is used as a focusing lens. An input gear formed of a gear train meshing with an internal teeth formed on an inner circumferential surface of a rear end portion of the cam ring and an output gear of the zoom driving mechanism provided on the camera body are connected at a lens barrel put-out position to transmit a zoom driving force to the cam ring.
However, the input gear and the output gear constituting the zoom driving mechanism are disconnected when the lens barrel is retracted into the camera body, and there is a possibility of these gears rotating relative to each other to be out of phase when the camera is carried so that the gears cannot be connected smoothly when the lens is put out for photographing.
There is also a problem that a diverging torque from the output gear cannot be used to drive a zoom finder. This is because if the input and output gears become out of phase, the phase of a cam for making a torque diverge from the output gear to drive a lens of the finder by a well-known means is shifted.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a camera with a zoom lens free from the above-described problems.
To achieve this object, according to one aspect of the present invention, there is provided a camera comprising a lens barrel collapsing drive mechanism for putting out a lens barrel including a zoom operation member for operating a plurality of lenses for zooming by controlling the positions of the lenses from a collapsed position to a photographing waiting position in front of the camera body, a bayonet member for positioning and retaining the lens barrel on the camera body, the bayonet member being mounted on the camera body so as to be rotatable on an optical axis, a zoom driving force transmission mechanism for transmitting a zoom driving force to the zoom operation member by connecting an input gear for transmitting a driving force to the zoom operation member provided on the lens barrel and an output gear provided on the camera body, an input gear rotation inhibition member capable of engaging with the input gear while the input gear is moved to a position immediately before the position at which is connected to the output gear, the input gear rotation inhibition member being provided on the camera body, and a lock member for positioning and retaining the lens barrel in the photographing waiting position and for releasing the lens barrel from the positioned and retained state, the lock member being engaged/disengaged with the output gear by an operation of rotating the bayonet member to inhibit/allow the rotation of the output gear.
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Photographing Industry, Camera Test, published Jun., 1988.
Suzuki Ryoichi
Yamamoto Harushige
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