Photography – Camera detail – Shutter
Reexamination Certificate
2000-03-30
2002-05-28
Gray, David M. (Department: 2851)
Photography
Camera detail
Shutter
C396S470000, C396S493000
Reexamination Certificate
active
06394668
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shutter for a camera.
2. Description of the Related Art
Although a shutter for a camera is available in various styles and types, as one type there is a shutter for a camera which operates such that an aperture of a lens is closed by closing a plurality of sheets of sectors and a hole for exposure is opened at a central portion thereof by pivoting the sectors. According to opening and closing operation of the sectors, a base portion of each of the sectors is pivotably supported, a drive pin of a sector drive lever is engaged with a drive hole portion provided at a position apart from the support point by a predetermined distance and the sector can be opened by pivoting the lever and can return to an original position by spring force.
FIG. 11
shows the principle of a shutter drive apparatus for operating two sheets of sectors to open and close according to a conventional technology and an outline of a constitution of the shutter drive apparatus is as follows.
Two sheets of sectors
83
are attached between a shutter base plate
81
and a rear plate
82
to thereby enable to open and close lens apertures
81
a
and
82
a
. The shutter base plate
81
and the rear plate
82
can be fixed to be apart from each other at an interval capable of installing the sectors pivotably by screws
84
.
Respective elements of the shutter drive apparatus are provided on a front face (upper face of
FIG. 11
) of the shutter base plate
81
. First, a sector drive lever
85
formed with projected portions on both sides of a plate-like member formed substantially in a heart-like shape, is provided at a vicinity of a central portion of the upper face of the shutter base plate
81
. According to the sector drive lever
85
, a bearing portion
85
a
provided to project at a pivotal center portion thereof is fitted to a support shaft portion
81
b
provided to project from the upper face of the shutter base plate
81
. A sector drive pin
85
b
is provided straight down from a vicinity of a top portion of a lower face of the sector drive lever
85
and the pin passes through an arc groove portion
81
c
formed in the shutter base plate and is engaged with an oval groove portion
83
a
of the sector. Further, respective sectors constituting the shutter
83
are pivotably supported by pivotal center holes
83
b
and support pins
81
d
provided to project from a rear face of the shutter base plate. The respective support pins
81
d
stably support respectively the sector
83
by being engaged with through holes
82
b
provided at the rear plate
82
.
The sector drive lever
85
is biased in the counterclockwise direction by a spring
86
, and thereby, the shutter
83
is biased in a direction of closing the shutter
83
. A drive coil
87
constituted by winding a coil in a spiral shape and solidifying the coil in a doughnut-like shape, is fixedly attached to a rear face of an ear portion
85
c
formed on a side of the sector drive lever
85
opposed to a position attached with the spring
86
. One lead wire
87
a
of the coil
87
is connected to an outer peripheral portion of the coil and the other lead wire
87
b
is connected to an inner peripheral portion thereof. When electricity is conducted from a drive circuit
88
to the coil
87
, there is produced magnetic flux an upper side of which constitutes an S pole and a lower side of which constitutes an N pole, for example. Conduction of electricity to the coil
87
can be controlled by the drive circuit
88
to thereby enable to arbitrarily open and close the shutter.
The drive coil
87
is also pivoted centering on the support shaft portion
81
b
by pivoting the sector drive lever
85
and a pair of permanent magnets
89
and
90
in a shape of a thin plate are provided on a pivotal locus of the center of the coil. These permanent magnets are fixedly attached onto the upper face of the shutter base plate
81
and the one magnet
89
is disposed on a forward side of the pivotal locus of the coil
87
in the clockwise direction at an initial position and is pasted such that an upper face thereof constitutes an N pole. In contrast thereto, the other permanent magnet
90
is disposed on a rearward side of the pivotal locus and is pasted such that an upper face thereof constitutes an S pole.
Since the constitution is constructed in this way, when magnetic force with the S pole on a downward side is produced in the coil by conducting controlled electricity from the drive circuit
88
to the coil
87
, by the operation of the magnetic force, a suction force is operated between the drive coil
87
and the magnet
89
on the front side and a repulsion force is operated between the drive coil
87
and the magnet
90
on the rear side to thereby move the drive coil
87
in the clockwise direction and pivot the sector drive lever
85
in the same direction. Thereby, the sector
83
is opened and an exposable state is brought about. Next, when electricity is made to stop conducting to the drive coil
87
, the magnetic force is extinguished, and therefore, the sector drive lever
85
returns to the original position by a spring
86
and the shutter is closed.
According to the shutter drive apparatus of the conventional example, the sector drive lever
85
and the drive coil
87
are disposed on different planes and accordingly, there poses a problem in which areas on the planes become large. Further, in addition thereto, the sector drive lever
85
, the drive coil
87
and the permanent magnets
89
and
90
are provided at respectively different heights and accordingly, there poses a problem in which a thickness of the shutter becomes large by that amount. Furthermore, the sector drive lever
85
is pivoted by pivoting the drive coil
87
per se and accordingly, there poses a problem in which large kinetic energy is needed and accordingly, power consumption is increased.
SUMMARY OF THE INVENTION
In order to resolve the above-described problems, according to a shutter for a camera of the invention, a fixed printed board in correspondence with the shutter base plate in the conventional technology and a movable printed board in correspondence with the sector drive lever in the conventional technology, are provided respectively with an optical axis as a reference, a plurality of coil patterns in a spiral shape are arranged at each of the printed boards and a plurality of sectors are made openable and closable by using electromagnetic force produced by conducting electricity to the plurality of coil patterns to thereby realize small-sized formation and high function formation of the shutter.
According to the shutter of the invention, the respective printed boards and a sector ring are constructed so as to be laminated centering on the optical axis and accordingly, areas of the shutter are reduced while the drive coil occupying a large space in the conventional technology is replaced by the coil patterns and accordingly, the shutter can be thinned also in view of a thickness thereof to thereby promote downsizing of the shutter.
When current controlled by a drive circuit is flowed to the coil patterns arranged on the fixed printed board, depending on a way of winding the coil patterns in the spiral shape, electromagnetic force of an N pole or an S pole is produced respectively on a fixed printed board face and a movable printed board face opposed to each other.
When polarities of both are constituted by a same polarity in directions opposed to each other and initial positions of the coil patterns of the movable printed board are set at positions apart from positions of the fixed printed board and shifted in an advancing direction by a predetermined angle, electromagnetic forces by the two coil pattern produced by conducting electricity from the drive circuit repel each other to pivot the movable printed board in a direction of opening the sectors. When electricity is made to stop conducting to the coil patterns by the drive circuit, the electromagnetic forces of the two printed b
Adams & Wilks
Gray David M.
Seiko Precision Inc.
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