Photography – Camera shake sensing
Reexamination Certificate
1998-01-27
2004-02-17
Adams, Russell (Department: 2851)
Photography
Camera shake sensing
C396S055000, C396S071000
Reexamination Certificate
active
06694096
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for use in a camera system which includes an optical assembly having an image stabilizing unit for correcting image blur caused by shake in a camera or other optical apparatus.
2. Description of the Related Art
In cameras today, important settings including exposure and focus settings are all automated and even a person not familiar with camera operation is unlikely to fail to take a photograph.
Systems for preventing camera shake have been studied, and there are almost no factors that could cause a photographer to abort photographing.
Now a system for preventing camera shake is briefly discussed.
Camera shake during photographing is due to vibrations whose frequency falls within a range of 1 to 12 Hz. In order to photograph in image-blur free fashion even with camera shake at the moment of a shutter release, camera shake is detected and then a correction lens is displaced in response to the detected shake. To take a picture image-blur free, the camera shake needs to be accurately detected and variations in the optical axis of the camera need to be corrected accordingly.
Theoretically speaking, the vibration of a camera (camera-shake) is detected using vibration sensor means for detecting angular acceleration, angular velocity, angular displacement, the like, and camera shake sensor means that outputs angular displacement by electrically or mechanically integrating an output signal of the vibration sensor means. Image blur is thus, prevented by driving a correction optical system that decenters the optical axis of a photograph based on the information from these sensor mean.
The stabilization system using such vibration sensor means is now discussed referring to FIG.
8
.
FIG. 8
shows the system for controlling image blur resulting from the vertical component
81
p
and horizontal component
81
y
of camera shake represented by arrows
81
.
Shown in
FIG. 8
are a lens barrel
82
, and vibration sensor means
83
p
and
83
y
for detecting respectively the vertical component and horizontal component of the camera vibration;
84
p
and
84
y
denote respectively the directions of vibration. A correction optical assembly
85
(including coils
87
p
,
87
y
for imparting thrust to the correction optical assembly
85
and position sensors
86
p
,
86
y
for sensing the position of the correction optical assembly
85
) is provided with a position control loop to be described later, and is driven with its target set to the output of the vibration sensor means
83
p
,
83
y
, thereby stabilizing an image on an image plane
88
.
FIG. 9
is an exploded perspective view of an image stabilizing system (constructed of the vibration sensor means, the correction optical assembly, the coils, the position sensors and a variety of ICs) preferably used for the above purpose, and referring to
FIGS. 9 through 18
, the construction of the assembly is now discussed.
Rear projections
71
a
(one of three projections
71
not shown) of a base plate
71
(see its enlarged view in
FIG. 12
) are engaged with the lens barrel, and known barrel rollers are screwed into holes
71
b
to be secured to the lens barrel.
A glossily plated second yoke
72
of a magnetic material is secured to the base plate
71
by screws that pass through holes
72
a
of the yoke
72
and are screwed into screw holes
71
c
of the base plate
71
. Permanent magnets (for shifting)
73
of neodymium or the like are magnetically attached to the second yoke
72
. The direction of magnetization of each permanent magnet
73
is represented by an arrow
73
a
as shown in FIG.
8
.
A correction lens
74
is attached with a C ring to a support frame
75
(shown in an enlarged view in FIG.
13
). Coils
76
p
,
76
y
(shift coils) are forced to snap into place with the support frame
75
(the coils are not yet snapped in FIG.
13
). Light emission devices (IRED)
77
p
,
77
y
are glued onto the rear surface of the support frame
75
. Light rays emitted therefrom pass through slits
75
ap
,
75
ay
and reach position sensor devices (PSD)
78
p
,
78
y.
Each of holes
75
b
(at three positions) of the support frame
75
receives pins
79
a
,
79
b
, each having a spherical end and made of POM (polyacetal resin), and a bias spring
710
(as shown in FIGS.
10
and
12
). The pin
79
a
is thermally caulked to the support frame
75
(the pin
79
b
is slidable in the direction of the hole
75
b
against the urging of the bias spring
710
).
FIG. 10
is a cross-sectional view showing the image stabilizing system after it is assembled. The pin
79
b
, the bias spring
710
, and the pin
79
a
in that order are inserted into the hole
75
b
of the support frame
75
in the direction of an arrow
79
c
(pins
79
a
,
79
b
are identical in shape), and the circular end portion
75
c
of the hole
75
b
is thermally caulked to prevent the pin
79
a
from coming off.
FIG. 11A
is a cross-sectional view of the hole
75
b
viewed perpendicular to the page of
FIG. 10
, and
FIG. 11B
is a front view of the hole
75
b
viewed from the direction shown by the arrow
79
c
in FIG.
11
A. Reference characters A through D in
FIG. 11B
correspond to depths A through D in FIG.
11
A.
The back end of a blade portion
79
aa
of the pin
79
a
is engaged with and restrained by a surface A, and the circular end
75
a
is caulked, and the pin
79
a
is secured to the support frame
75
.
Since a blade portion
79
ba
of the pin
79
b
is engaged with an abutment surface B, the pin
79
b
is prevented from coming out of the hole
75
b
under the urging of the bias spring
710
.
When image stabilizing system is fully assembled, the pin
79
b
is engaged with the second yoke
72
, and is thus prevented from coming out of the support frame
75
. For convenience of assembling, the abutment surface B for locking purpose is provided.
As
FIGS. 10 and 11
show the shapes of the support frame
75
and the holes
75
b
, the support frame
75
is manufactured using a simple split type molding technique in which a mold is simply pulled out in the direction of the arrow
79
c,
rather than a complex inner diameter slide molding technique, and accommodates high dimensional accuracy requirements.
The use of the pins
79
a
,
79
b
, identical to each other, reduces component cost, promotes error free assembling, and is advantageous from the component management point of view.
A shaft socket
75
d
of the support frame
75
is coated with fluorine-based grease, and receives one end of an L-shaped shaft
711
(non-magnetic stainless steel) (see FIG.
9
). The other end of the L-shaped shaft
711
is received in a shaft socket
71
d
(similarly coated with the grease) formed in the base plate
71
. With the three pins
79
b
resting on the second yoke
72
, the support frame
75
is seated in the base plate
71
.
As shown in
FIG. 9
, pins
71
f
(at three points) of the base plate
71
shown in
FIG. 12
are received in alignment holes (at three points)
712
a
of a first yoke
712
shown in
FIG. 9
while the first yoke
712
is engaged with abutment surfaces
71
e
(at five points) shown in
FIG. 12
to be magnetically coupled to the base plate
71
(by means of magnetic force of the permanent magnets
73
).
In this way the rear surface of the first yoke
712
is put into contact with the pins
79
a
, and the support frame
75
is interposed between the first yoke
712
and the second yoke
72
as shown in
FIG. 10
so that the support frame
75
is registered in the direction of the optical axis of the camera.
The abutment surfaces of the first yoke
712
and the second yoke
72
and of the pins
79
a
,
79
b
mutually in contact are coated with fluorine-based grease, and the support frame
75
is slidably moved relative to the base plate
71
in a plane perpendicular to the optical axis.
The L-shaped shaft
711
permits the support frame
75
to be slidably supported relative to the base plate
71
in the directions shown by the arrows
713
p
,
713
y
only, thereby restrainin
Adams Russell
Smith Arthur A
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