Photography – Camera shake sensing
Reexamination Certificate
1996-09-12
2003-06-03
Mahoney, Christopher (Department: 2851)
Photography
Camera shake sensing
C396S303000, C396S055000
Reexamination Certificate
active
06574436
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims priority from Japanese Patent Application No. 07-237433 filed Sep. 14, 1995, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to image blur compensation devices, which are used in still cameras, video cameras, and other optical devices and instruments. In particular, it relates to image blur compensation devices reducing the effects of noise which becomes a problem during position detection using a Position Sensitive Device (PSD).
2. Description of the Related Art
Image blur compensation devices, which compensate for image blur arising due to camera vibration, caused by hand motions and the like during photography, normally compensate for image blur by moving at least one lens (hereinafter termed “image blur compensation optical system”) in a direction at right angles to the optical axis of the photographic lens. A general description of a prior art image blur compensation device is provided below.
FIG. 31
is a lateral cross sectional diagram showing an image blur compensation device. In
FIG. 31
, an image blur compensation optical system
1
is located in a lens barrel
2
. Namely, the lens and the lens barrel are integral.
The lens barrel
2
, as shown in
FIG. 32
, may be driven in the XY plane if the direction of the optical axis is the Z axis. Thus, the lens barrel
2
is driven at right angles to the Z axis in the direction of the XY plane by an electromagnetic actuator consisting of a coil
6
, a magnet
7
, a yoke
9
, and a yoke
10
.
The electromagnetic actuator constituted by the coil
6
, the magnet
7
, the yoke
9
and the yoke
10
, consists of two sets of these elements located in mutually orthogonal directions. This structure generates respective forces in the X axis direction and the Y axis direction.
Namely, the image blur compensation optical system
1
is a structure which can move integrally with the lens barrel
2
in the X axis direction and the Y axis direction.
A slit plate
4
is located in the base edge side (yoke
9
) in the sidewall of the lens barrel
2
. An infrared light emitting element (IRED)
8
is located in the front end side of the lens barrel
2
. The light beam of the IRED
8
is disposed to pass through a slotted hole (slit) in the slit plate
4
.
Then, a position sensitive device (PSD)
5
is disposed in the yoke
9
, which is fixed in position. The PSD
5
, by detecting the light of the IRED
8
passing through the slit of the slit plate
4
, detects the movement position of the image blur compensation optical system
1
.
FIGS.
32
(
a
)-(
b
) are cross sectional diagrams of the support structure of the image blur compensation optical system (lens barrel). FIG.
32
(
a
) shows the state with the image blur compensation optical system in the optical axis position, and FIG.
32
(
b
) shows the state with the image blur compensation optical system moved from the optical axis position.
As shown in FIGS.
32
(
a
) and
32
(
b
), the lens barrel
2
is cantilever supported by four elastic support members
3
(because FIGS.
32
(
a
) and
32
(
b
) are cross sections, only two are shown,
3
a
and
3
b
). The base end of support members
3
a
,
3
b
, are engaged with the yoke
9
and can move in a direction at right angles with respect to the optical axis.
FIG. 33
is a constitutional block diagram of a prior art image blur compensation device. In
FIG. 33
, the image blur compensation device is equipped with an angular velocity detection circuit (X axis)
13
, an angular velocity detection circuit (Y axis)
14
, a rangefinding circuit
18
, a photometric circuit
19
, a microcomputer unit (“CPU”)
20
, a main switch
26
, a half depression switch
27
, a release switch
28
, a power supply battery
29
, an optical system
51
, position detection elements
56
X,
56
Y, a lens position detection circuit (X axis)
57
X, a lens position detection circuit (Y axis)
57
Y, a lens position detection circuit (AF)
58
, an actuator drive circuit (X axis)
59
X, an actuator drive circuit (Y axis)
59
Y, a shutter drive circuit (AF)
60
, actuators
61
X,
61
Y, a stepping motor
62
, a DC/DC converter
64
.
In the above constitution, the image blur compensation operation is performed as summarized next. In
FIG. 33
, when half depression of the release button is performed, the half depression switch
27
is set ON, the DC/DC converter
64
starts, and the CPU
20
begins to provide a stabilized power supply.
When the rangefinding circuit
18
and the photometric circuit
19
begin the standard photographic operations of the camera, at the same time the angular velocity circuit (X axis)
13
and the angular velocity circuit (Y axis)
14
begin to detect the blurring motions of the camera. The angular velocity detection sensors use piezoelectric type angular velocity sensors which detect the normal Coriolis force.
The CPU
20
integrates the outputs obtained from the angular velocity sensors (blurring motion sensors) and converts them into blurring motion angles of the camera. Furthermore, it converts the output from the angular velocity sensors into target drive position data of the image blur compensation optical system
54
.
Next, when full depression of the release button is performed, the release switch
28
is set ON, and the focusing lens
55
is driven with the stepping motor
62
being controlled by the shutter drive circuit
60
. Simultaneously with this operation, control is also commenced of control of the image blur compensation mechanism by the image blur compensation optical system
54
.
The control of the image blur compensation mechanism is accomplished by the actuator drive circuit (X axis)
59
X and the actuator drive circuit (Y axis)
59
Y in order to move the image blur compensation optical system according to the same target drive position data as at the time of half depression. The actuator drive circuits
59
X and
59
Y perform in phase by the difference of the target drive position data and the actual image blur compensation optical system position data, and send signals to the actuators
61
X and
61
Y.
Detection of the actual position of the image blur compensation optical system is wholly performed by the lens position detection circuit (X axis)
57
X, the lens position detection circuit (Y axis)
57
Y, and the CPU
20
. The usual PSD is used in the position detection elements
56
X,
56
Y. The CPU
20
calculates the position of the image blur compensation optical system by the output current of the PSD.
The actuator drive circuit (X axis)
59
X and the actuator drive circuit (Y axis)
59
Y next supply drive currents to the actuators
61
X,
61
Y, based on the signals of the servo units.
The actuators
61
X,
61
Y, based on these drive currents, move the image blur compensation optical system in a plane at right angles to the optical axis, and effect compensation of the image blur, such as due to hand motions.
However, in the prior art, in the case of detection using a PSD of the position of the image blur compensation optical system, because the photoelectric current obtained from the PSD is a very small current, there were cases in which the position data could not be accurately detected, because of the effects of noise arising inside the camera and outside the camera.
As noise sources inside the camera, there are switching noise of the DC/DC converter which is in the power supply circuit, stepping motor drive noise when driving the shutter, motor noise when driving the focusing lens(es), and the like. However, it is difficult to bring about a reduction of these noises because they stem from the characteristics and character of their devices.
Accordingly, how to reduce these noises in a image blur compensation device using a PSD in position detection of the image blur compensation optical system has become an important problem.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to solve the above problems of the prior
Matsushima Jun
Otani Tadashi
Mahoney Christopher
Nikon Corporation
LandOfFree
Image blur compensation device with reduced noise effect... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image blur compensation device with reduced noise effect..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image blur compensation device with reduced noise effect... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3112147