Photography – Camera shake sensing – Having stabilization system
Reexamination Certificate
2000-05-12
2002-04-16
Perkey, W. B. (Department: 2851)
Photography
Camera shake sensing
Having stabilization system
Reexamination Certificate
active
06374049
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to improvements in an actuator for a vibration prevention apparatus provided with a coil and a magnet.
2. Related Background Art
A system for preventing a hand fluctuation applied to a camera has heretofore been studied and there is one already carried on a product and put into practical use. Here, a system for preventing hand fluctuation will be briefly described.
Hand fluctuation of a camera during photographing usually is a vibration of a frequency of 1 Hz to 12 Hz, and as a basic idea for making a photograph free of image blur photographable even if such a hand fluctuation is caused at the point of release of a shutter release time, the vibration of the camera by the above-described hand fluctuation must be detected and in conformity with the detected value, a correction lens must be displaced. Accordingly, to make a free of image blur photographable even if hand fluctuation occurs, it is necessary to first detect the vibration of the camera accurately, and then to correct the variation in the optical axis due to the vibration of the camera.
Theoretically speaking, the detection of this vibration (camera vibration) can be accomplished by carrying on the camera a vibration detecting sensor for detecting acceleration, velocity or the like, and means for electrically or mechanically integrating the output signal of the vibration detecting sensor and outputting displacement. On the basis of this detected information, correcting optical means (comprising a correction lens and a fixed frame or the like for holding the correction lens) in a vibration prevention apparatus carried to make the photographing optical axis eccentric is controlled (the correction lens is displaced), whereby image blur correction becomes possible.
FIG. 10
of the accompanying drawings is an exploded perspective view of a vibration prevention apparatus used in the vibration prevention system of an interchangeable lens for a single-lens reflex camera.
FIG. 11
of the accompanying drawings is a detailed view of the portion X (stepping motor unit) of FIG.
10
. The epitome of the vibration prevention apparatus will hereinafter be described with reference to these figures.
This is a system in which a holder
101
holding a correction lens (not shown) is moved on a plane perpendicular to a photographing optical axis L by a driving force generated by coils
105
p,
105
y
and magnets
107
p,
107
y
to thereby correct camera vibration.
The reference
103
designates a restraining member in which two slots
103
f
and
103
g
formed about the photographing optical axis L are fitted on projections, not shown, projected from a ground plate
102
, and the output of the stepping motor unit X which will be described later is transmitted to a gear portion
103
a,
whereby the restraining member
103
is rotated, and projected portions
101
a
to
101
d
(only two of which are seen in
FIG. 10
) provided at four locations on the holder
101
abut against the cam portions
103
b
to
103
e,
respectively, of the restraining member
103
so as to lock (restrain) the correction lens at a predetermined position. This is because when the vibration prevention apparatus is not being driven, the correction lens (and the holder
101
) are swayed by the vibration or the like by the disturbance during the carrying of the camera, strike against the ground plate or the like, and make a crashing sound. In order to avoid being swayed, striking against the ground plate, making the crashing sound, and the damage thereby, it is necessary to provide a lock mechanism for holding the direction lens at a predetermined position during the non-operation of the apparatus.
The reference numeral
106
denotes a hard substrate (printed substrate) having mounted on its back photoreflectors
112
p
and
112
y
for the detection of positions corresponding to the movement positions of pitch and yaw on the holder
101
side, and having mounted thereon the terminal of the stepping motor unit X which will be described later, the terminals of coil units
105
p
and
105
y
and further, elements or the like concerned in the control of these. The reference characters
111
p
and
111
y
designate target members for position detection, and the target members
111
p
and
111
y
are printed with black and white patterns so that the outputs of the photoreflectors
112
p
and
112
y
may vary at a constant rate in conformity with the position of the correction lens.
The reference character X denotes a stepping motor unit of the conventional two-phase type, the reference characters
116
a
and
116
b
designate stator yokes obtained by piling up a plurality of metallic plates of a soft magnetic material and securing to one another, and the reference characters
115
a
and
115
b
denote coil for exciting the stator yokes
116
a
and
116
b.
The reference numeral
114
designates a rotor made of a plastic magnet rotatable by the excited state of the stator yokes
116
a
and
116
b,
and the outer periphery thereof is divisionally and alternately magnetized. The reference numeral
113
denotes a motor case lid which effects the positioning of the stator yokes
116
a,
116
b,
the rotor
114
and the coils
115
a,
115
b,
and is fixed to the ground plate
102
and forms the stepping motor unit X. A gear portion
114
a
provided on the rotor
114
meshes with the gear portion
103
a
of the restraining member
103
and the restraining member
103
is rotated to thereby lock the holder (correction lens)
110
as previously described.
In the aforedescribed vibration prevention apparatus according to the prior art, the position of the correction lens is always detected to perform an accurate correction driving and the output thereof is fed back. Also, as previously described, when the vibration prevention apparatus is not being driven, the correction lens or the like is swayed by the vibration or the like by the disturbance during the carrying or the like of the camera, strikes against the ground plate or the like, and makes a crashing sound. In order to avoid being swayed, striking against the ground plate, making a crashing sound, and the damage thereby, it has been necessary to provide a lock mechanism for locking the correction lens at a predetermined position. Therefor, a position detecting sensor for detecting the position of the correction lens and a part for locking the correction lens must be added, and this has led to disadvantages such as an increased cost and the enlargement of the size of the apparatus. Particularly, when an attempt is made to carry the vibration prevention apparatus on a compact camera or the like, the enlargement of the size of the apparatus as previously noted is fatal.
SUMMARY OF THE INVENTION
It is a first object of the present invention to provide a vibration prevention apparatus of which the enlargement of the size and complication of an apparatus can be prevented, the vibration can be suppressed with good accuracy, and the destruction by vibration or the like can be prevented.
It is a second object of the present invention to provide a vibration prevention apparatus in which the control of the gap between a coil and a magnet can be done easily.
The vibration prevention apparatus of the present invention has:
a holding member for holding an optical unit for correcting an image blur;
a support member for movably supporting the holding member;
a coil member provided on the holding member;
a magnet member provided on the support member, and disposed in opposed relationship with the coil member; and
a member disposed between the coil member and the magnet member, and having electrical conductivity;
wherein the coil member is electrically energized, whereby the holding member is driven relative to the support member.
Or conversely, the vibration prevention apparatus of the present invention has:
a holding member for holding an optical unit for correcting image blur;
a support member for movably supporting the holding member;
a magnet member provided on the
Canon Kabushiki Kaisha
Perkey W. B.
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