Optical: systems and elements – Lens – With support
Reexamination Certificate
2003-07-01
2004-08-24
Sugarman, Scott J. (Department: 2873)
Optical: systems and elements
Lens
With support
C359S821000, C359S822000, C359S823000, C359S824000
Reexamination Certificate
active
06781772
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.
2. Related Background Art
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 of those digital cameras will be discussed in the following.
The main power source is initially turned 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 by the image monitor.
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.
FIG. 15
illustrates a small-sized stop apparatus or shutter apparatus. In the apparatus, a motor for driving the stop blade or the shutter blade is formed in a ring shape, and its inner portion is used as the optical path. Outer diameters of the stop apparatus and shutter apparatus can be hence reduced.
In
FIG. 15
, reference numeral
101
designates a cylindrical rotor whose outer surface portions are alternately magnetized into N and S magnetic poles. Reference numerals
102
a
and
102
b
designate coils which are respectively disposed along the axial direction of the rotor sandwiching the rotor. Reference numerals
103
a
and
103
b
designate stators formed of magnetic material. The stator
103
a
is magnetically excited by the coil
102
a
, and the stator
103
b
is magnetically excited by the coil
102
b
. Each of the stators
103
a
and
103
b
is comprised of an outer cylinder and an inner cylinder. The outer cylinder has an outer magnetic pole portion which extends in the axial direction in a planer form, and the outer magnetic pole portion is disposed in a position facing the outer surface of the rotor
101
. The inner cylinder also has an inner magnetic pole portion which extends in the axial direction in a planer form, and the inner magnetic pole portion is disposed in a position facing the inner surface of the rotor
101
. Reference numerals
104
a
and
104
b
designate auxiliary stators which are fixed to the inner cylinders of the stators
103
a
and
103
b
, respectively. Reference numeral
105
designates a coupling ring which is formed of non-magnetic material, and serves to couple the stators
103
a
and
103
b
to each other with a predetermined phase shift. Upon supplying electric power to the coils
102
a
and
102
b
, the outer magnetic pole portions of the stators
103
a
and
103
b
and the auxiliary stators
104
a
and
104
b
are excited, and the rotor
101
is rotated up to a predetermined position. Reference numeral
106
designates an output ring which is fixed to the inner surface of the rotor
101
and rotates together with the rotor
101
. Reference numeral
107
designates a plate on which grooves for engaging with pins on the output ring
106
are formed. Those grooves regulate the rotational range of the output ring
106
. Reference numerals
108
a
and
108
b
designate shutter blades which engage with the pins of the output ring
106
, respectively, and whose opened condition is changed according to the rotational position of the rotor
101
.
FIG. 16
illustrates another conventional structure in which the outer diameter of a motor is greatly decreased without making its inner portion hollow.
In
FIG. 16
, reference numeral
201
designates a cylindrical rotor
201
whose portions
201
a
and
201
b
are magnetized to the 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 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 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 thus opened or closed.
When no current is supplied to the coil
202
, the elastic force of the torsion spring
206
brings the shutter blades
207
and
208
into the condition under which they close the aperture portion
205
a
. When current is supplied to the coil
202
, the rotor
202
is rotated against the elastic force of the torsion spring
206
. The aperture portion formed by the shutter blades
207
and
208
is enlarged as the magnitude of the current increases.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a driving apparatus which includes a rotatable ring-shaped rotor having magnet portions divided along a circumferential direction and differently magnetized; a first magnetic pole portion formed extending in a direction perpendicular to a rotational axis of the rotor, and facing a face of the magnet portion perpendicular to the rotational axis; and a second magnetic pole portion sandwiching the magnet portion between the second magnetic pole portion and the first magnetic pole portion, and facing another face of the magnet portion perpendicular to the rotational axis. In this driving apparatus, the condition of −0.333X+0.7>Y is satisfied where Y is a ratio of a central angle of each first magnetic pole portio
Canon Kabushiki Kaisha
Robin Blecker & Daley
Sugarman Scott J.
Thompson Tim
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