Photography – Camera shake sensing – Having stabilization system
Reexamination Certificate
1998-01-27
2001-03-27
Perkey, W. B. (Department: 2851)
Photography
Camera shake sensing
Having stabilization system
Reexamination Certificate
active
06208810
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image blur preventing device for preventing image blur resulting, for example, from hand vibration in a camera, an optical instrument or the like.
2. Related Background Art
In recent cameras, the possibility of failure in photograph taking is quite low even for an amateur who is not skilled in the manipulation of the camera, because important operations for photograph taking such as determination of the exposure and focusing are all automated.
Also, systems have been developed for preventing interference of hand vibration to the camera, so that few factors inducing the failure in photograph taking are left on the part of the photographer.
In the following there will be briefly explained such system for preventing hand vibration.
Vibration of the camera induced by hand vibration during photograph taking usually has a frequency of 1 to 12 Hz. The basic principle for providing a photograph without image blur even in the presence of such hand vibration when the shutter is released consists of detecting the vibration of the camera induced by such hand vibration and displacing a correction lens in response to the detected amount. Therefore, in order to obtain a photograph without image blur even in the presence of a camera vibration, it is necessary to first precisely detect the vibration of the camera and then to correct the change in the optical axis resulting from such vibration.
The detection of such vibration (camera vibration) can in principle be achieved by providing the camera with vibration detection means (e.g., a sensor) for detecting an angular acceleration, an angular velocity or an angular variation, and camera vibration detection means for outputting the angular variation by electrically or mechanically integrating the output signal of the sensor. The image vibration can be suppressed by driving a correcting optical device, for deviating the photographing optical axis, based on the detected information.
A vibration preventing system employing such a vibration detection means now is described with reference to FIG.
18
.
FIG. 18
shows a system for suppressing the image blur resulting from a pitching vibration
81
p
and a yawing vibration
81
y
of the camera, indicated by arrows
81
.
In
FIG. 18
, there are shown a lens barrel
82
; vibration detection means
83
p
,
83
y
for respectively detecting pitching and yawing vibrations of the camera, with respective vibration detecting directions
84
p
,
84
y
; and an optical correction device
85
(with coils
87
p
,
87
y
for applying driving forces to the optical correction device
85
and position detectors
86
p
,
86
y
for detecting the position of correction device
85
). The optical correction device
85
is provided with a position control loop to be explained later, and is driven with the outputs of the vibration detection means
83
p
,
83
y
as target values thereby achieving stabilization on the image plane
88
.
FIG. 19
is an exploded perspective view of an image blur correction device (composed of the above-mentioned vibration detection means, optical correction device, coils, position detectors and various IC's to be explained later) adapted for use for the above-mentioned object. The structure of this device will be explained with reference to
FIGS. 19
to
28
.
A base plate
71
(shown in
FIG. 22
in magnified manner) is provided with three rear projections
71
a
(one being not visible) which are fitted on an unrepresented lens barrel, and are fixed thereto by screwing of known lens barrel rollers or the like into holes
71
b.
A second yoke
72
, composed of a magnetic material and provided with metal plating is fixed to holes
71
c
of the base plate
71
by screws passing through holes
72
a
. Permanent magnets (shifting magnets)
73
such as neodymium magnets are magnetically adhered to the second yoke
72
. The permanent magnets
73
are respectively magnetized in directions indicated by arrows
73
a
shown in FIG.
19
.
In a support frame
75
(shown in
FIG. 23
in magnified manner), in which a correction lens
74
is fixed with C-rings or the like, coils (shifting coils)
76
p
,
76
y
are fixed by forced fitting (
FIG. 23
showing an unfixed state), and light emitting elements
77
p
,
77
y
such as IRED's are also adhered to the rear face of the support frame
75
, whereby the emitted lights pass through slits
75
ap
,
75
ay
and enter position detecting elements
78
p
,
78
y
such as PSD's to be explained later.
In three holes
75
b
of the support frame
75
, there are inserted support balls
79
a
,
79
b
with spherical ends, composed for example of POM (polyacetal resin), and charging springs
710
(cf. FIGS.
20
and
21
A), and the support balls
79
a
are fixed to the support frame
75
by heat caulking (support balls
79
b
being rendered slidable in the direction of holes
75
b
, against the force of the charging springs
710
).
FIG. 20
is a longitudinal cross-sectional view of the image vibration correction device after assembling thereof. In each hole
75
b
of the support frame
75
, there are inserted in succession, in a direction
79
c
, the support ball
79
b
, the charged spring
710
and the support ball
79
a
(support balls
79
a
and
79
b
being identical in shape), and the peripheral edge
75
c
of the hole
75
b
is finally heat caulked to retain the support ball
79
a.
FIG. 21A
is a cross-sectional view of the hole
75
b
in a direction perpendicular to the plane of
FIG. 20
, and
FIG. 21B
is a plan view of the hole
75
b
seen from a direction
79
c
. In
FIG. 21A
, symbols A to D indicate depths of areas A to D shown in FIG.
21
B.
As the rear end of a fin portion
79
aa
of the support ball
79
a
is received and limited by an area of the depth A, the support ball
79
a
is fixed to the support frame
75
by the heat caulking of the peripheral edge
75
a.
Also as the front end of a fin portion
79
ba
of the support ball
79
b
is received and limited by an area of the depth B, the support ball
79
b
cannot escape, under the force of the charging spring
710
, from the hole
75
b
in a direction
79
c.
After the assembling of the image blur correcting device, the support ball
79
b
is received by the second yoke
72
as shown in FIG.
20
and cannot escape from the support frame
75
, but the escape preventing area B is provided in consideration of convenience of assembling.
As the shape of the hole
75
b
of the support frame
75
, as illustrated in
FIGS. 20
,
21
A and
21
B, does not require, in the molding of the support frame
75
, a complex mold but can be prepared with a simple two-part mold in which a part is extracted in a direction opposite to the arrow
79
c
, so that the dimensional precision can be strictly defined.
Also as the support balls
79
a
,
79
b
are identical in shape, it is rendered possible to reduce the cost of the parts, to avoid errors in assembling and to facilitate management of the parts.
In a bearing portion
75
d
of the support frame
75
, there is coated for example fluorinated grease, and an L-shaped shaft
711
(made of non-magnetic stainless steel) is inserted therein (cf. FIG.
19
). The other end of the L-shaped shaft
711
is inserted into a bearing portion
71
d
(similarly coated with grease) of the base plate
71
, and the support frame
75
is placed in the base plate
71
, with three support balls
79
b
riding on the second yoke
72
.
Then three positioning holes
712
a
of a first yoke
712
shown in
FIG. 19
are fitted on three pins
71
f
, shown in
FIG. 22
, of the base plate
71
, and the first yoke
712
is received by five receiving faces
71
e
, shown in
FIG. 22
, and is magnetically coupled, by the magnetic force of the magnets
73
, to the base plate
71
.
In this manner the rear face of the first yoke
712
comes into contact with the support balls
79
a
, and, as shown in
FIG. 20
, the support frame
75
is sandwiched between the first yoke
712
and the second yoke
72
and is defin
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Perkey W. B.
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