Photography – Camera detail – Shutter
Reexamination Certificate
2003-05-21
2004-04-13
Gray, David M. (Department: 2851)
Photography
Camera detail
Shutter
C310S046000, C310S156380
Reexamination Certificate
active
06719463
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement of a drive apparatus and a light quantity adjusting apparatus that are suited for a shutter apparatus or the like used in an image pickup apparatus such as a digital camera. The present invention also relates to an improvement of a lens drive apparatus suited to driving a lens of an image pickup apparatus.
2. Related Background Art
A conventional shutter apparatus for use in a lens shutter camera is shown in FIG.
16
. In this drawing, reference numeral
101
denotes a magnet that is a permanent magnet, numeral
102
a drive lever, and numeral
102
a
a drive pin provided for the drive lever
102
. This drive lever
102
is fixed to the magnet
101
and rotates integrally with the magnet
101
. Reference numeral
103
represents a coil and reference numerals
104
and
105
each indicate a stator that is made of a soft magnetic material and is to be excited by the coil
103
. The stator
104
and the stator
105
are connected to each other through portions
104
a
and
105
a
and are integrated with each other in terms of a magnetic circuit. When the coil
103
is energized, the stator
104
and the stator
105
are excited and the magnet
101
is driven to rotate within a predetermined angle. Reference numerals
106
and
107
each denote a shutter blade and reference numeral
108
indicates a ground board. The shutter blades
106
and
107
are rotatively attached to pins
108
b
and
108
c
of the ground board
108
through hole portions
106
a
and
107
a
, with the drive pin
102
a
being slidably fitted into long holes
106
b
and
107
b
of the shutter blades
106
and
107
. With this construction, the drive lever
102
rotates along with the magnet
101
, the shutter blades
106
and
107
are driven to rotate about the hole portions
106
a
and
107
a
, and an opening portion
108
a
of the ground board is opened/closed. In order to prevent an increase in cost, the magnet is formed using a plastic magnet and the drive pin is formed in an integrated manner.
Reference numeral
109
denotes a front ground board that holds the shutter blades
106
and
107
so as to be movable in a gap between this front ground board
109
and the ground board
108
, while reference numeral
110
indicates a rear ground board that holds the stators
104
and
105
and rotatively holds the magnet
101
.
By the way, digital cameras are now in widespread use which each photoelectrically convert the image of an objective field using a CCD or the like as an image pickup element and records the image in a storage medium as information of a still image. An example of an exposure operation performed by a digital camera of this type will be briefly described below.
First, the main power supply is turned on prior to photographing and, when an image pickup element is placed in an operable state, shutter blades are maintained at an open position at which exposure of the image pickup element is enabled. Under this condition, the image pickup element repeatedly accumulates, discharges, and transfers electric charges, which makes it possible to observe the objective field using an image monitor.
Following this, when a release button is depressed, a diaphragm value and an exposure time are determined in accordance with an output of the image pickup element at this point in time. When it is judged from the determined diaphragm value and exposure time that the diameter of an exposure aperture needs to be reduced, a diaphragm blade is first driven to a position at which a predetermined diaphragm value is obtained. Next, the image pickup element, from which accumulated electric charges have been discharged, is caused to start accumulation of electric charges. At the same time, an exposure time control circuit is activated in response to the accumulation start signal serving as a trigger signal. Then, when a predetermined exposure time has passed, the shutter blades are driven to a close position at which the exposure light to the image pickup element is blocked. After the exposure light is blocked, the accumulated electric charges are transferred and image information is recorded in a recording medium through an image writing apparatus. The exposure of the image pickup element is inhibited during the transfer of the electric charges because it is required to prevent a situation where the electric charges are changed by extra light during this electric charge transfer.
Aside from the shutter apparatus described above, there are also available a shutter apparatus having a mechanism of moving an ND filter and a shutter apparatus having a mechanism of moving a diaphragm regulating member having a small diaphragm diameter.
With these shutter apparatuses, it becomes possible to realize thickness reduction, although a large area of a ground board is occupied by a coil and a stator. In view of this problem, there is proposed a light quantity adjusting apparatus shown in FIG.
17
.
In this drawing, reference numeral
201
denotes a tubular rotor, with its portion
201
a
being magnetized to have the N pole and its portion
201
b
being magnetized to have the S pole. Reference numeral
201
c
represents an arm formed integrally with the rotor
201
, and reference numeral
201
d
indicates a drive pin extending from this arm
201
c
in a rotation axis direction of the rotor
201
. Reference numeral
202
indicates a coil that is disposed in the axis direction of the rotor
201
. Reference numeral
203
denotes a stator that is made of a soft magnetic material and is to be excited by the coil
202
. This stator
203
includes an outer magnetic pole portion
203
a
opposing the outer peripheral surface of the rotor
201
and an inner cylinder inserted into the rotor
201
. Reference numeral
204
indicates an auxiliary stator that is fixed to the inner cylinder of the stator
203
and opposes the inner peripheral surface of the rotor
201
. When the coil
202
is energized, the outer magnetic pole portion
203
a
and the auxiliary stator
204
are excited and the rotor
201
rotates to a predetermined position. Reference numerals
207
and
208
each represent a shutter blade, while reference numeral
205
indicates a ground board. The shutter blades
207
and
208
are rotatively attached to pins
205
b
and
205
c
of the ground board
205
through hole portions
207
a
and
208
a
, with the drive pin
201
d
being slidably fitted into long holes
207
b
and
208
b
. Reference numeral
206
denotes a torsion spring that gives an elastic force to the rotor
201
so that the drive pin
201
d
is pressed against end portions of the long holes
207
b
and
208
b
. When the coil
202
is energized, the drive pin
201
d
rotates along with the rotor
201
in defiance of the elastic force given by the torsion spring
206
, so that the shutter blades
207
and
208
are driven to rotate about the hole portions
207
a
and
208
a
and an opening portion
5
a
of the ground board is opened/closed.
With such a construction, it becomes possible to construct a compact light quantity adjusting apparatus.
The light quantity adjusting apparatus shown in
FIG. 17
has a shape suited for miniaturization, in comparison with the apparatus shown in FIG.
16
. However, the energization needs to be continued when it is desired to move the shutter blades to a close position in defiance of the elastic force given by the torsion spring and to maintain the shutter blades at the close position. Also, in order to maintain the shutter blades at the open position and the close position without using the torsion spring, there may be utilized the direction of energization of the coil. Even in this case, however, in order to maintain the drive target member at a position at which this member is abutted against an end portion of the long hole of the ground board, it is required to continue the energization of the coil. Accordingly, there still remains room for improvement by which power saving is achieved.
SUMMARY OF THE INVENTION
According to one as
Canon Kabushiki Kaisha
Gray David M.
Robin Blecker & Daley
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