Photography – Having variable focal length of camera objective
Reexamination Certificate
1998-12-17
2001-11-13
Mahoney, Christopher E. (Department: 2851)
Photography
Having variable focal length of camera objective
C396S133000
Reexamination Certificate
active
06317562
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a driving apparatus utilizing a motor as a driving source, for particular use in an optical apparatus, for example.
2. Related Background Art
Hitherto, an apparatus shown in
FIG. 9
was known as a lens driving apparatus for a still camera, a video camera, and the like. Referring to
FIG. 9
, a lead screw
102
is connected to the output shaft (not shown) of a step motor
101
. A frame
103
rotatably holds the ends of the lead screw
102
and fixes or secures the step motor
101
as well. The frame
103
is fixed to a bottom board (not shown).
A lens frame
105
has an arm portion, including an internal thread engaged with the lead screw
102
. The lens frame
105
fixes or holds a lens
104
. Also, the lens frame
105
can move in the direction of the optical axis of the lens, while rotation about the lens optical axis is restricted by a bottom board (not shown).
In a lens driving apparatus constructed as discussed above, when the lead screw
102
is rotated by the step motor
101
, the lens frame
105
, which is engaged with the lead screw
102
at the internal screw portion, is moved. Consequently, the lens
104
is moved in the back and forth directions of the optical axis, corresponding to the revolution of the step motor
101
. By this back and force motion, focusing, zooming, etc., can be achieved.
A conventional step motor is shown in
FIG. 10. A
stator coil
115
is concentrically wound around a bobbin
111
. The bobbin
111
is clamped between two stator yokes
116
in the axial direction. In the stator yokes
116
, stator teeth
116
a
and
116
b
are alternately disposed in the circumferential direction of the internal radius of the bobbin
111
.
The stator yoke
116
is integrally fixed, in a case
113
a
or
113
b
, with the stator teeth
116
a
or the stator teeth
116
b
. Thus, the stator
112
includes the bobbin
111
, the stator coil
115
, and stator yoke
116
.
A flange
125
and a bearing
118
a
are fixed to the case
113
a
, while a second bearing
118
b
is fixed to another case
113
b
. A rotor
119
has a rotor shaft (output shaft)
120
and rotor magnets
121
, fixed to the rotor shaft
120
. Gaps are radially formed between the rotor magnets
121
and the stator tooth
116
a
of the stator
112
. The driving shaft
120
is rotatably supported by the two bearings
118
a
and
118
b
.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, an optical apparatus comprises a movable lens unit, a rotatable lead screw moving the movable lens unit, and a motor driving the rotatable lead screw. The optical apparatus is configured such that the center of the motor and the center of the lead screw are disposed so as to be approximately aligned on the same circumference of a circle centered on an optical axis of a lens in the movable lens unit.
According to another aspect of the present invention, an optical apparatus comprises a step motor including: (i) a magnet formed in a cylindrical shape, wherein at least the external magnet periphery is circumferentially divided into multiple portions, and wherein each of the multiple portions are alternately magnetized into north and south magnetic poles; (ii) first and second coils provided in the axial direction of the magnet, wherein the first coil is disposed on a first side of the magnet, and the second coil is disposed on a second side of the magnet; (iii) a first external magnet pole, magnetized by the first coil and opposed to the external periphery of a first end of the magnet; (iv) a first internal magnetic pole, magnetized by the first coil and opposed to the internal periphery of the first end of the magnet; (v) a second external magnet pole, magnetized by the second coil and opposed to the external periphery of a second end of the magnet; and (vi) a second internal magnet pole, magnetized by the second coil and opposed to the internal periphery of the second end of the magnet.
According to still another aspect of the present invention, an optical apparatus comprises a movable lens unit, a rotatable lead screw moving the movable lens unit, and a step motor driving the rotatable lead screw. In the optical apparatus, the step motor comprises two coils disposed in the axial direction of the lead screw.
According to a further aspect of the present invention, an optical apparatus comprises a movable lens unit, a rotatable lead screw moving the movable lens unit, and a step motor driving the rotatable lead screw. The step motor comprises: (i) a magnet formed in a cylindrical shape, wherein at least the external magnet periphery is circumferentially divided into multiple portions, and wherein each of the multiple portions are alternately magnetized into different magnetic poles; (ii) first and second coils provided in the axial direction of the magnet, wherein the first coil is disposed on a first side of the magnet, and the second coil is disposed on a second side of the magnet: (iii) a first external magnet pole, magnetized by the first coil and opposed to the external periphery of a first end of the magnet; (iv) a first internal magnetic pole, magnetized by the first coil and opposed to the internal periphery of the first end of the magnet; (v) a second external magnet pole, magnetized by the second coil and opposed to the external periphery of a second end of the magnet; and (vi) a second internal magnet pole, magnetized by the second coil and opposed to the internal periphery of the second end of the magnet, wherein the step motor is disposed in a direction parallel to the lead screw.
According to another aspect of the present invention, a driving apparatus comprises a movable display member unit, a rotatable lead screw moving the movable display unit, a motor driving the rotatable lead screw, and a holding member which holds both the rotatable lead screw and the motor so that the rotatable lead screw and the motor are disposed in a side-by-side, parallel arrangement.
According to still another aspect of the present invention, a driving apparatus comprises a step motor including: (i) a magnet formed in a cylindrical shape, wherein at least the external magnet periphery is circumferentially divided into multiple portions, and wherein each of the multiple portions are alternately magnetized into north and south magnetic poles; (ii) first and second coils provided in the axial direction of the magnet, wherein the first coil is disposed on a first side of the magnet, and the second coil is disposed on a second side of the magnet; (iii) a first external magnetic pole, magnetized by the first coil and opposed to the external periphery of a first end of the magnet; (iv) a first internal magnetic pole, magnetized by the first coil and opposed to the internal periphery of the first end of the magnet; (v) a second external magnetic pole, magnetized by the second coil and opposed to the external periphery of a second end of the magnet; and (vi) a second internal magnetic pole, magnetized by the second coil and opposed to the internal periphery of the second end of the magnet.
REFERENCES:
patent: 3508091 (1970-04-01), Kavanaugh
patent: 4767958 (1988-08-01), Sasaki
patent: 5241422 (1993-08-01), Shimada et al.
patent: 5489958 (1996-02-01), Katagiri et al.
patent: 5594518 (1997-01-01), Ohshita
patent: 5831356 (1998-11-01), Aoshima
patent: 5860030 (1999-01-01), Tada et al.
patent: 5937215 (1999-08-01), Mogamiya
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Mahoney Christopher E.
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