Photography – Having variable focal length of camera objective – Lens moves in or out of light path
Reexamination Certificate
2003-07-22
2004-09-28
Perkey, W. B. (Department: 2851)
Photography
Having variable focal length of camera objective
Lens moves in or out of light path
C396S133000, C396S463000, C396S508000, C310S015000, C310S265000, C310S268000
Reexamination Certificate
active
06798987
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to improvements of a driving apparatus and a light-amount regulating apparatus which are suitably usable in a shutter device and the like provided in an image pick-up apparatus such as a digital camera. The present invention also relates to an improvement of a lens driving apparatus suitably usable in a lens driving mechanism provided in the image pick-up apparatus.
2. Related Background Art
A conventional shutter device of a lens shutter camera as illustrated in
FIG. 17
has been proposed. In
FIG. 17
, reference numeral
101
designates a magnet member of a permanent magnet. Reference numeral
102
designates a driving lever. Reference numeral
102
a
designates a driving pin formed on the driving lever
102
. The driving lever
102
is fixed to the magnet
101
, and rotated together with the magnet
101
. Reference numeral
103
designates a coil. Reference numerals
104
and
105
designate stators made of soft magnetic material, and magnetically excited by the coil
103
, respectively. The stators
104
and
105
are connected to each other by portions
104
a
and
105
a
, and integrally arranged in a common magnetic circuit. Upon supplying current to the coil
103
, the stators
104
and
105
are magnetically excited, and the magnet
101
is rotationally driven in a range of a predetermined angle.
Reference numerals
106
and
107
designate shutter blades, respectively. Reference numeral
108
designates a plate. Hole portions
106
a
and
107
a
of the shutter blades
106
and
107
are rotatably mounted on pins
108
b
and
108
c
of the plate
108
, respectively. The driving pin
102
a
is slidably fitted into elongate holes
106
b
and
107
b
. Accordingly, when the driving lever
102
rotates with the magnet
101
, the shutter blades
106
and
107
are rotationally driven about the holes
106
a
and
107
a
, respectively. An aperture portion
108
a
of the plate
108
is hence opened or closed. For purposes of preventing an increase in the cost, there has also been proposed a structure in which the magnet is comprised of a plastic magnet, and the driving pin is formed integrally with the magnet.
Reference numeral
109
designates a front plate for movably holding the shutter blades
106
and
107
between this front plate and the plate
108
. Reference numeral
110
designates a rear plate for holding the stators
104
and
105
, and rotatably holding the magnet
101
.
Digital cameras for opto-electrically converting a field image and recording it as information of a still picture image in a recording medium by using a CCD and the like as a pick-up device have been more and more widely used. An example of the operation of exposure in those digital cameras will be discussed in the following.
The main power source is initially switched on prior to photographing to put the pick-up device in its operating condition, and the shutter blade is hence held at its open position capable of exposing the pick-up device. Accordingly, storing, discharging and transferring of electric charges are repeated by the pick-up device, and observation of the object field is made possible through the image monitor.
Thereafter, upon pushing the release button, stop value and exposure time are determined corresponding to the output of the pick-up device at that time. Accordingly, when the diameter of the exposure aperture needs to be narrowed, the stop blade is driven to be set at a predetermined stop value. Instruction of start of storing electric charges is then sent to the pick-up device from which stored electric charges are discharged. At the same time the circuit for controlling the exposure time begins to operate upon reception of that start instruction as a trigger signal.
After the lapse of a predetermined exposure time, the shutter blade is driven to its closed position for intercepting the exposure of the pick-up device. Upon intercepting the exposure of the pick-up device, the stored electric charges begin to be transferred. The picture image information is thus recorded in the recording medium through an image writing apparatus. Exposure of the pick-up device is blocked during the transfer of electric charges to prevent variation of electric charges due to undesired light during this transfer time.
Other than the above-discussed shutter apparatus, there also exist an apparatus with a mechanism for advancing or retracting an ND filter, and an apparatus with a mechanism for advancing or retracting a stop restricting member having a small stop diameter.
In the above shutter apparatus, the thickness can be decreased, but the coil and the stators are liable to occupy a wide area on the plate. In view of such disadvantage, a light-amount regulating apparatus as illustrated in
FIG. 18
has been proposed.
In
FIG. 18
, reference numeral
201
designates a cylindrical rotor
201
whose portions
201
a
and
201
b
are magnetized to N and S magnetic poles, respectively. Reference numeral
201
c
designates an arm formed integrally with the rotor
201
. A driving pin
201
d
extends from the arm
201
c
in the rotational axial direction of the rotor
201
. Reference numeral
202
designates a coil disposed along the axial direction of the rotor
201
. Reference numeral
203
designates a stator which is formed of soft magnetic material, and magnetically excited by the coil
202
. The stator
203
has an outer magnetic pole portion
203
a
which faces the outer surface of the rotor
201
, and an inner cylinder which is inserted into the rotor
201
.
Reference numeral
204
designates an auxiliary stator which is fixed to the inner cylinder of the stator
203
, and faces the inner surface of the rotor
201
. Upon supplying electric power to the coil
202
, the outer magnetic pole portion
203
a
and the auxiliary stator
204
are magnetically excited, and the rotor
201
is rotated up to a predetermined position. Reference numerals
207
and
208
designate shutter blades, and reference numeral
205
designates a plate. The shutter blades
207
and
208
are respectively rotatable about hole portions
207
a
and
208
a
into which pins
205
b
and
205
c
of the plate
205
are inserted, respectively. The driving pin
201
d
slidably engages with elongate holes
207
b
and
208
b
. Reference numeral
206
designates a torsion spring which gives elastic force to the rotor
201
such that the driving pin
201
d
can be pushed against ends of the elongate
207
b
and
208
b
. When electric power is supplied to the coil
202
to rotate the driving pin
201
d
together with the rotor
201
against the elastic force of the torsion spring
206
, the shutter blades
207
and
208
are rotated about the hole portions
207
a
and
208
a
, respectively. The aperture portion
205
a
of the plate
205
is hence opened or closed.
A compact light-amount controlling apparatus can be achieved by such a light-amount regulating apparatus.
The light-amount regulating apparatus of
FIG. 18
is more suitable for a small-sized structure than that of FIG.
17
. In the light-amount regulating apparatus of
FIG. 18
, however, the shutter blades
207
and
208
can be simply held at either of their open positions or closed positions by changing the current supply condition of the coil only between ON state and OFF state. In other words, those light-amount regulating blades can be driven only between two states, i.e., a state in which the aperture portion is covered with them, and a state in which they are retracted from the aperture portion. Therefore, it is desired to provide an apparatus in which an intermediate open state between the above two states, for example, can also be established.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a driving apparatus which includes a rotor rotatable about its rotational axis and having a cyclindrical magnet portion whose outer circumferential surfaces are divided along a circumferential direction into plural differently magnetized portions; at l
Canon Kabushiki Kaisha
Cowan Liebowitz & Latman
Perkey W. B.
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