U.S. patent application number 09/320892 was filed with the patent office on 2001-09-20 for image shake correction device for optical apparatus and optical apparatus having image shake correction device.
Invention is credited to HARA, YOSHIHIRO, KOSAKA, AKIRA, MINATO, SHOICHI, TANAKA, YOSHIHARU, TANII, JUNICHI.
Application Number | 20010022688 09/320892 |
Document ID | / |
Family ID | 15761957 |
Filed Date | 2001-09-20 |
United States Patent
Application |
20010022688 |
Kind Code |
A1 |
KOSAKA, AKIRA ; et
al. |
September 20, 2001 |
IMAGE SHAKE CORRECTION DEVICE FOR OPTICAL APPARATUS AND OPTICAL
APPARATUS HAVING IMAGE SHAKE CORRECTION DEVICE
Abstract
An image shake correction device for correcting image shake on
the focal plane of an optical apparatus due to vibration of the
optical apparatus such as a camera. A correction optical element is
provided in the optical path of the principal optical system, the
correction optical element is driven correspondingly to the
detected image shake magnitude, and the image shake on the focal
plane of an optical apparatus is corrected. A driving mechanism
which utilizes shape memory alloy is used for driving a correction
lens for correcting image shake.
Inventors: |
KOSAKA, AKIRA; (YAO-SHI,
JP) ; TANII, JUNICHI; (IZUMI-SHI, JP) ; HARA,
YOSHIHIRO; (KISHIWADA-SHI, JP) ; TANAKA,
YOSHIHARU; (KAWACHINAGANO-SHI, JP) ; MINATO,
SHOICHI; (SAKAI-SHI, JP) |
Correspondence
Address: |
BARRY E BRETSCHNEIDER
MORRISON & FOERSTER LLP
2000 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
200061888
|
Family ID: |
15761957 |
Appl. No.: |
09/320892 |
Filed: |
May 27, 1999 |
Current U.S.
Class: |
359/557 |
Current CPC
Class: |
G03B 2205/003 20130101;
G03B 2205/0023 20130101; G03B 5/00 20130101; G03B 2205/0076
20130101; G02B 27/646 20130101; G03B 2205/0015 20130101 |
Class at
Publication: |
359/557 |
International
Class: |
G02B 027/64 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 1998 |
JP |
10-162825 |
Claims
What is claimed is:
1. An image shake correction device of an optical apparatus
comprising: an optical element provided in the optical path of the
principal optical system, including a pair of flat plates being
made of transparent material corresponding to the incident surface
and outgoing surface and transparent fluid filler filled between
said pair of flat plates; and a driving mechanism, having an
actuator which utilizes shape memory alloy functioning to change
the angle of at least one of said pair of flat plates with respect
to an optical axis of a principal optical system of the optical
apparatus.
2. An image shake correction device of an optical apparatus as
claimed in claim 1, wherein said pair of flat plates is disposed
perpendicularly to the optical axis of the principal optical system
when not activated and inclined by a prescribed angle with respect
to the optical axis of the principal optical system when
activated.
3. An image shake correction device of an optical apparatus as
claimed in claim 1, wherein a plurality of said actuators are
provided on the peripheries of said flat plates so as to connect
said pair of flat plates at the peripheries.
4. An image shake correction device of an optical apparatus as
claimed in claim 1, wherein said actuator functions to incline said
pair of flat plates by a prescribed angle with respect to the
optical axis of the principal optical system.
5. An image shake correction device of an optical apparatus as
claimed in claim 1, wherein said driving mechanism is provided with
an elastic member which exerts a pressing force in the direction to
resist against the restoring force due to restoration of said
actuator including shape memory alloy to a memorized shape.
6. An image shake correction device of an optical apparatus as
claimed in claim 1, wherein said driving mechanism controls heating
of said actuator including shape memory alloy to control the
deformation length of said actuator.
7. An image shake correction device of an optical apparatus
comprising: a correction optical system provided in the optical
path of the principal optical system; a holder being provided
movably in the plane approximately perpendicular to the optical
axis of the principal optical system for holding said correction
optical system; and a first driving mechanism having an actuator
which utilizes shape memory alloy to move said holder and functions
to move said holder in the plane approximately perpendicular to the
optical axis of the principal optical system in the first
direction.
8. An image shake correction device of an optical apparatus as
claimed in claim 7, wherein said first driving mechanism is
provided with an elastic member which exerts a pressing force in
the direction to resist against the restoring force due to
restoration of said actuator consisting of shape memory alloy to a
memorized shape.
9. An image shake correction device of an optical apparatus as
claimed in claim 7, wherein said first driving mechanism controls
heating of said actuator consisting of shape memory alloy to
control the deformation length of said actuator.
10. An image shake correction device of an optical apparatus as
claimed in claim 7, wherein said image shake correction device of
the optical apparatus is further provided with the second driving
mechanism, which moves said holder in a plane approximately
perpendicular to the optical axis of the principal optical system
in the second direction different from said first direction to
correct the image shake.
11. An image shake correction device of an optical apparatus as
claimed in claim 10, wherein said second driving mechanism is
provided with an actuator which utilizes shape memory alloy to move
said holder.
12. An image shake correction device of an optical apparatus as
claimed in claim 10, wherein said second direction is approximately
perpendicular to said first direction.
13. An image shake correction device of an optical apparatus as
claimed in claim 10, wherein said correction optical system and
holder comprises a first correction optical system and holder which
move in said first direction and a second correction optical system
and holder which move in said second direction.
14. An image shake correction device of an optical apparatus as
claimed in claim 10, wherein said second driving mechanism is
provided with an elastic member which exerts a pressing force in
the direction to resist against the restoring force due to
restoration of said actuator consisting of shape memory alloy to a
memorized shape.
15. An image shake correction device of an optical apparatus as
claimed in claim 10, wherein said second driving mechanism controls
heating of said actuator consisting of shape memory alloy to
control the deformation length of said actuator.
16. An image shake correction device of an optical apparatus
comprising: a correction optical system provided in the optical
path of the principal optical system; a holder for supporting said
correction optical system; a first driving mechanism having an
actuator which utilizes shape memory alloy to move said holder and
incline said holder around the first axis in a plane approximately
perpendicular to the optical axis of the principal optical system;
and a second driving mechanism having an actuator to move said
holder and incline said holder around the second axis, which is
different from the first axis, in a plane approximately
perpendicular to the optical axis of the principal optical
system.
17. An image shake correction device of an optical appatatus as
claimed in claim 16, wherein said second driving mechanism is
provided with an actuator which utilizes shape memory alloy to move
said holder.
18. An image shake correction device of an optical apparatus as
claimed in claim 16, wherein said second axis is disposed in the
direction approximately perpendicular to said first axis.
19. An image shake correction device of an optical apparatus as
claimed in claim 16, wherein said first driving mechanism is
provided with an elastic member which exerts a pressing force in
the direction to resist against the restoring force due to
restoration of said actuator consisting of shape memory alloy to a
memorized shape.
20. An image shake correction device of an optical apparatus as
claimed in claim 16, wherein said first driving mechanism controls
heating of said actuator consisting of shape memory alloy to
control the deformation length of said actuator.
21. An optical apparatus provided with an image shake correction
device comprising: a first optical system for taking in an optical
image from an object; a second optical system for correcting the
shake, due to the shake of said optical apparatus, of the optical
image taken from said first optical system; and a driving mechanism
having an actuator which utilizes shape memory alloy for driving
said second optical system based on the shape change of shape
memory alloy.
22. An optical apparatus provided with an image shake correction
device as claimed in claim 21, wherein said driving mechanism is
provided with an elastic member which exerts a pressing force in
the direction to resist against the restoring force due to
restoration of said actuator consisting of shape memory alloy to a
memorized shape.
23. An optical apparatus provided with an image shake correction
device as claimed in claim 21, wherein said driving mechanism
comprises the first driving mechanism for driving said second
optical system in the first direction and the second driving
mechanism for driving said second optical system in the second
direction which is different from the said first direction.
24. An optical apparatus provided with an image shake correction
device as claimed in claim 21, wherein said first and second
driving mechanisms control heating of said actuator consisting of
shape memory alloy to control the deformation length of said
actuator.
25. A method for correcting the image shake in an optical apparatus
provided with an image shake correction system comprising the steps
of: (1) detecting the shake magnitude caused in the optical
apparatus; (2) calculating the magnitude of displacement of the
correction optical system based on the detected shake magnitude of
the optical apparatus; and (3) heating the actuator including shape
memory alloy which is a component of the driving mechanism for
driving the correction optical system to a temperature determined
based on said calculation result.
Description
[0001] This application is based on application No. 10-162825 filed
in Japan, the contents of which is hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an image shake correction device
for correcting the image shake on the image focal plane of an
optical apparatus due to vibration of an optical apparatus such as
a camera, and an optical apparatus provided with the image shake
correction device.
[0004] 2. Description of the Prior Art
[0005] Heretofore, in the camera industry field, a correction
optical system which drives a correction lens, which is located
behind the photographic lens, eccentrically in a plane
perpendicular to the optical axis has been known as a means for
correcting the image shake on the image forming plane due to camera
shake caused in photographing. In the lens device provided with a
correction optical system, an actuator used exclusively for driving
the correction lens in a predetermined direction is incorporated,
the movement of a camera is detected by means of a camera shake
sensor such as an angular acceleration sensor, and the correction
lens is driven based on the detected signal.
[0006] The applicant of the present invention proposed a
piezoelectric actuator which utilizes a phenomenon that a driven
member coupled frictionally with a driving shaft moves in a
predetermined direction with repeated reciprocal vibration when the
driving shaft is vibrated reciprocally in different speed by a
piezoelectric transducer which is served as the actuator for
driving such a correction optical system. This structure can drive
eccentrically the correction lens having a holder frame coupled
with the driven member of the piezoelectric actuator in a plane
perpendicular to the optical axis (refer to Japanese Laid Open
Patent No. Hei 8-43872 as an example).
[0007] Otherwise, moving coil type of actuator which has two
electromagnetic coils in a plane perpendicular to the optical axis
provided on a holder frame of a correction lens and has a yoke and
a permanent magnet located correspondingly to the two
electromagnetic coils provided on a fixed frame of a lens barrel
has been known.
[0008] The above-mentioned piezoelectric actuator and moving coil
type actuator are suitable for the correction lens driving
mechanism for correcting image shake because of excellent
controllability, however on the other hand, these driving
mechanisms are large and heavy to result in a large-sized and
expensive optical apparatus as a whole, therefore a compact and
light-weight correction lens driving mechanism has been desired to
be realized.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a novel
image shake correction device for correcting image shake on the
focal plane of an optical apparatus caused from vibration of the
optical apparatus and to provide an optical system having the image
shake correction device.
[0010] It is another object of the present invention to provide a
compact and light-weight image correction device having a driving
mechanism which utilizes shape memory alloy as the driving
mechanism for driving an image shake correction optical element
located in the optical path of the principal optical system of the
optical apparatus and to provide an optical system having the image
shake correction device.
[0011] It is yet another object of the present invention to provide
a method for correcting image shake by heating shape memory alloy
of the driving mechanism, which is employed as the driving
mechanism for driving an image shake correction optical element
located in the optical path of the principal optical system of an
optical apparatus.
[0012] It is still another object of the present invention to
provide an optical apparatus having an image shake correction
device applying said method for correcting image shake.
[0013] Other objects of the present invention will be clear from
the detailed description of the present invention with reference to
the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view for illustrating an appearance
of an image shake correction optical unit in accordance with the
first embodiment.
[0015] FIG. 2 is a cross sectional view along the axis Y-Y of the
image shake correction optical unit shown in FIG. 1.
[0016] FIG. 3 is a cross sectional view of the correction optical
unit which is in standby condition.
[0017] FIG. 4 is a cross sectional view of the correction optical
unit which is correcting image shake.
[0018] FIG. 5 is a block diagram for illustrating the structure of
a control circuit for controlling the image shake correction
optical unit in accordance with the first embodiment.
[0019] FIG. 6 is a flowchart for describing the control operation
of the image shake correction optical unit in accordance with the
first embodiment.
[0020] FIG. 7 is a plan view for illustrating the structure of an
image shake correction optical unit in accordance with the second
embodiment.
[0021] FIG. 8 is a plan view for illustrating the structure of an
image shake correction optical unit in accordance with the third
embodiment.
[0022] FIG. 9 is a plan view for illustrating the structure of an
image shake correction optical unit in accordance with the fourth
embodiment.
[0023] FIG. 10 is a block diagram for illustrating the structure of
a control circuit for controlling the image shake correction
optical unit in accordance with the fourth embodiment.
[0024] FIG. 11 is a cross sectional view for illustrating the
structure of an image shake correction optical unit in accordance
with the fifth embodiment.
[0025] FIG. 12 is a partially enlarged view of the image shake
correction optical unit shown in FIG. 11.
[0026] FIG. 13 is a cross sectional view along the line A-A of the
image shake correction optical unit shown in FIG. 11.
[0027] FIG. 14 is a cross sectional view for describing the
inclined image shake correction optical unit shown in FIG.
[0028] FIG. 15 is a cross sectional view for illustrating the
structure of a camera provided with an image shake correction
device disclosed in the embodiments.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] The preferred embodiments of the present invention will be
described hereinafter.
[0030] [First Embodiment]
[0031] The first embodiment involves an exemplary image shake
correction device applied to a camera, FIG. 1 is a perspective view
for illustrating the appearance of an image shake correction
optical unit 10, and FIG. 2 is a cross sectional view along Y-Y
axis in FIG. 1. 18 denotes a photographic lens which represents the
principal optical system, and the correction optical unit 10 is
located in the optical path of the principal optical system 18.
[0032] In FIG. 1 and FIG. 2, the correction optical unit 10
comprises flat plates 11a and 11b consisting of transparent
material which is suitable for the optical element, holder frames
12a and 12b for supporting the flat plates 11a and 11b, a
cylindrical diaphragm 13 which defines a closed space, and a liquid
transparent synthetic resin filler 14 filled in the internal of the
closed space which is suitable for the optical element.
[0033] A plurality of elastic members 15 such as coil springs
(referred to as 15a to 15d hereinafter) for pressing the holder
frames 12a and 12b so as to widen the distance between the holder
frames 12a and 12b are provided on the periphery of the supporting
frames 12a and 12b at a plurality of positions where the periphery
is angularly divided into some equal predetermined angular
intervals (for example, 90 degrees or 120 degrees), and the holder
frames 12a and 12b are combined each other with shape memory alloy
wires 16 (referred to as 16a to 16d hereinafter) located near the
respective plurality of elastic members.
[0034] Herein only for the purpose of description, it is assumed in
the following description that the periphery of the holder frames
12a and 12b are divided into 90 degree intervals and an orthogonal
coordinate system having Z-axis coincident with the optical axis is
introduced, the elastic members 15a and 15b and the shape memory
alloy wires 16a and 16b are located on the plane including X-axis,
and the elastic members 15c and 15d and the shape memory alloy
wires 16c and 16d are located on the plane including Y-axis.
[0035] Shrink shape of a predetermined size is memorized in the
shape memory alloy wires 16a to 16d. When an current is supplied to
the shape memory alloy wires to heat to a predetermined
temperature, the wires are restored to the memorized original
shape. Because the size of the wires after restoration depends on
the temperature, the size of the shape memory alloy wires after
restoration is controlled by the current value of an electric
current namely the heating temperature.
[0036] In the structure described herein above, the shape memory
alloy wires 16a to 16d, when no current is supplied to wires 16a to
16d, receives the tensile force due to pressing force in the
direction to widen the distance between the holder frame 12a and
12b of the elastic members 15a to 15d, and the initial condition
that the elastic force of the elastic members 15a to 15d balances
the tension of the wires 16a to 16d is maintained. FIG. 2 shows a
cross sectional view of the correction optical unit 10 in the
initial condition.
[0037] Next, when first currents of the same current value are
supplied to the plurality of shape memory alloy wires 16a to 16d
for heating from a control circuit, which will be described
hereinafter, in order to set the standby position, the shape memory
alloy wires 15a to 15d are shrunk to the shape of memorized standby
position against the elastic force of the elastic members 15a to
15d. FIG. 3 shows a cross sectional view of the correction optical
unit 10 in the standby condition.
[0038] At this time, the flat plates 11a and 11b consisting of
transparent material remain perpendicular to the optical axis and
parallel each other because the displacement of the plurality of
shape memory alloy wires 16a to 16d is equal each other, therefore
the incident light into the correction optical unit 10 is allowed
to pass without refraction.
[0039] Next, electric currents different in current value are
supplied from the control circuit, which will be described
hereinafter, to heat the plurality of shape memory alloy wires 16a
to 16d based on image shake correction signal. In detail, for
example, an electric current of a second current value which is
larger than the first current value is supplied to the shape memory
alloy wire 16c disposed on the upper side in Y-axis direction, an
electric current of the first current value is supplied to the
shape memory alloy wire 16d disposed on the under side in Y-axis
direction, and an electric current of a third current value which
is intermediate between the first current value and the second
current value is supplied to the shape memory alloy wires 16a and
16b disposed on the right and left side in X-axis direction, and at
this time, the shape memory alloy wires 16a to 16d are restored
respectively to the memorized shape of sizes corresponding to the
respective current values, as the result, the flat plates 11a and
11b consisting of the transparent material of the correction
optical unit 10 are changed to a deformed shape having the shorter
length at the upper side. FIG. 4 shows a cross sectional view of
the correction optical unit 10 in an image shake correction
condition in which the flat plates 11a and 11b consisting of the
transparent material of the correction optical unit 10 are
positioned close each other at the upper side in Y-axis
direction.
[0040] An incident light into the correction optical unit 10 is
refracted in the plane including Y-axis when passing as shown in
FIG. 4, and the image shake is corrected.
[0041] FIG. 5 is a block diagram for illustrating the structure of
the control circuit 20 for controlling the correction optical unit.
The control circuit 20 has a CPU 21 as a main component, a camera
shake sensor 24, a memory unit 25, and an exposure controller 26
are connected to the input/output port of the CPU 21 and heater
driving units 23a to 23d for heating the respective shape memory
alloy wires 16a to 16d are connected to the output port of the CPU
21. A CPU for controlling the optical apparatus not shown in the
drawing may also be served as the CPU 21 or a CPU exclusively used
for the correction optical unit may be provided as the CPU 21.
[0042] Current value data for heating corresponding to the image
shake magnitude is stored in the memory unit 25. The relation
between the current value to be supplied to the shape memory alloy
wire and the deformation length of the memorized shape is
previously measured and further the deformation length of the shape
memory alloy wire corresponding to the inclination angle
(refraction angle) of the flat plates 11a and 11b, namely the image
shake correction magnitude, is determined previously, and a current
value corresponding to an image shake correction magnitude detected
by the camera shake sensor 24 is thereby determined.
[0043] Next, the control operation of the correction optical unit
driving mechanism performed in the CPU 21 is described with
reference to a flowchart shown in FIG. 6. First, a signal, which is
generated from the exposure controller 26 of the camera, which
indicates ON of a switch S1 for indicating the starting of
preparation for photograph taking activated by first step pushing
down (half pushing down) of a shutter button has been waited (step
P1), and when ON signal of the switch S1 is entered, whether the
camera shake correction switch for selecting the correction of the
camera shake is determined ON or not (step P2).
[0044] If the camera shake correction switch is ON, then an image
shake correction operation is started. That is, when the magnitude
of the shake in X-axis direction and Y-axis direction of the
camera, namely a lens system, is detected, the CPU 21 calculates
the correction magnitude required to correct the image shake,
namely the magnitude of the inclination angle (the inclination
angle of the flat plates is the determinant of the refraction angle
of the light which passes the correction optical unit 10) of the
flat plates 11a and 11b, reads out a current value data for heating
corresponding to the image shake correction magnitude stored in the
memory unit 25, heats the shape memory alloy wires 16a and 16d
through the heater driving units 23a to 23d, and starts the image
shake correction operation (step P3).
[0045] ON of the photographing starting switch S2 is waited (step
P4) because an image shake correction operation has started. If a
signal which indicates ON of the switch S2 is entered, then the
exposure control operation is performed (step P5), an OFF signal of
the switches S1 and S2 is waited (step P6), and if an OFF signal is
detected, the photographing is determined to be finished and the
currents supplied to the shape memory alloy wires 16a to 16d are
shut off to stop the image shake correction operation (step P7),
and the control sequence is brought to an end.
[0046] If the camera shake correction switch is not ON in the
determination in step P2, then a normal photographing sequence is
performed (step P10) and the control sequence is brought to an
end.
[0047] In the above-mentioned description, a case that the
periphery of the holder frames 12a and 12b is divided into 90
degree angular intervals to introduce the orthogonal coordinate
system having the optical axis coincident with Z-axis, the elastic
members 15a and 15b and the shape memory alloy wires 16a and 16b
are disposed on the plane including X-axis, and the elastic members
15c and 15d and the shape memory alloy wires 16c and 16d are
disposed on the plane including Y-axis is described herein above,
however, another case that the periphery of the holder frames 12a
and 12b is divided into three portions, the holder frames 12a and
12b are held by three elastic members and three shape memory alloy
wires, and desired inclination direction and inclination angle
(refraction angle) is set by selecting suitably three shape memory
alloy wires may be employed.
[0048] The structure of the correction optical unit 10 is described
herein above, the correction optical unit 10 is to be incorporated
in the lens barrel which contains the principal optical system such
as photographic lens as described herein above, many alternative
structures are designed desirably by applying the known means.
[0049] [Second Embodiment]
[0050] Next, the second embodiment is described. FIG. 7 is a plan
view for illustrating the structure of a correction optical unit 30
in accordance with the second embodiment. In FIG. 7, the structure
for driving the correction lens in X-axis direction is shown, the
same structure is provided in Y-axis direction, and thus the first
correction lens which moves in X-axis direction and the second
correction lens which moves in Y-axis direction are used
combinedly, and a correction optical unit for correcting the image
shake on XY-plane perpendicular to the optical axis is
provided.
[0051] In FIG. 7, 31 denotes a fixed frame having an aperture 31a
at the center, which is incorporated in a lens barrel of a lens
system not shown in the drawing. A holder frame 32 which holds a
correction lens 33 is located at the aperture 31a. An arm 34 is
formed on one end of the holder frame 32, and the holder frame 32
is guided by a shaft 35 which is provided on the fixed frame 31 in
X-axis direction and supported slidably in X-axis direction.
[0052] Further, an elastic member 36 such as a coil spring is
provided between a pin 31b provided on the fixed frame 31 and a
hook provided to the arm 34 of the holder frame 32, and a shape
memory alloy wire 37 is provided between a pin 31c provided on the
fixed frame 31 and a pin 34b provided to the arm 34 of the holder
frame 32.
[0053] A shrunk shape with a predetermined size has been memorized
in the shape memory alloy wire 37 previously, when a current is
supplied to the shape memory alloy wire to heat up to a
predetermined temperature, the shape memory alloy wire is restored
to the memorized shape. Because the size of shape memory alloy wire
after restoration depends on the temperature, the temperature is
controlled by controlling the current value to be supplied, and the
magnitude of restoration of the shape memory alloy wire is
controlled.
[0054] In the above-mentioned structure, the holder frame 32 is
pulled downward in FIG. 7 by the elastic force of the elastic
member 36, but a desired current is supplied to the shape memory
alloy wire 37 for heating to cause a prescribed shrinking
deformation, the shrinking deformation causes a force which lifts
the holder frame 32 upward in FIG. 7. When the image shake
correction is not activated, the downward pull force of the elastic
member 36 balances the upward pull force of the shape memory alloy
wire 37, and the holder frame 32 is positioned at the standby
position of no image shake correction.
[0055] When an image shake correction starts, an electric current
corresponding to the correction magnitude is supplied to the shape
memory alloy wire 37. If the current value corresponding to the
correction magnitude is larger than the predetermined current value
which have been set when the above-mentioned holder frame 32 is set
at the standby position, the shrinking deformation length of the
wire 37 is larger, and the holder frame 32 moves from the standby
position in X-axis positive direction (wire 37 side). On the other
hand, if the current value corresponding to the correction
magnitude is smaller than the predetermined current value which has
been set when the above-mentioned holder frame 32 is set at the
standby position, the shrinking deformation length of the wire 37
is smaller, and the holder frame 32 moves from the standby position
in X-axis negative direction (elastic member 36 side).
[0056] The driving mechanism for moving the correction lens in
Y-axis direction is operated in the same manner as that in X-axis,
and by combining two driving mechanisms, the image shake correction
optical unit for correcting image shake on XY-plane perpendicular
to the optical axis is structured.
[0057] The control circuit suitable for the structure in accordance
the second embodiment is a control circuit similar to the control
circuit used in the first embodiment shown in FIG. 5, and the
control circuit for the second embodiment has the structure that,
the heater driving unit shown in FIG. 5 is replaced with a heater
driving unit for heating the shape memory alloy wire of X-axis
direction driving mechanism and a heater driving unit for heating
the shape memory alloy wire of Y-axis direction driving mechanism,
and the control circuit is operated in the same manner as that of
the above-mentioned first embodiment and the description is
omitted.
[0058] [Third Embodiment]
[0059] Next, the third embodiment is described. FIG. 8 is a plan
view for illustrating the structure of a correction optical unit 40
in accordance with the third embodiment, a correction lens is
rotated round the axis which is positioned apart from the optical
axis and parallel to the optical axis. Because the structure allows
the first correction lens to be driven approximately in X-axis
direction, the same structure is provided also in Y-axis direction,
and by combining the first correction lens which moves
approximately in X-axis direction and the second correction lens
which moves approximately in Y-axis direction, a correction optical
unit for correcting image shake on XY-plane perpendicular to the
optical axis is structured.
[0060] In FIG. 8, 41 denotes a fixed frame having an aperture 41a
at the center to be incorporated in a lens barrel of a lens system
not shown in the drawing. A holder frame 42 which holds a
correction lens 43 is located at the aperture 41a. An arm 44 is
formed on one end of the holder frame 42, and supported rotatably
by the shaft 45 which is provided on the fixed frame 41 and located
in parallel to and apart from the optical axis.
[0061] Further, an elastic member 46 such as a coil spring is
provided extendedly between a pin 41b provided on the fixed frame
41 and a pin 44a provided on the arm 44 of the holder frame 42, and
a shape memory alloy wire 47 is provided extendedly between a pin
41c provided on the fixed frame 41 and a pin 44b provided on the
arm 44 of the holder frame 42 by way of a pulley 48.
[0062] A shrink shape of a predetermined size has been memorized in
the shape memory alloy wire 47 previously, when a current is
supplied to the shape memory alloy wire to heat up to a
predetermined temperature, the shape memory alloy wire is restored
to the memorized shape. Because the size of shape memory alloy wire
after restoration depends on the temperature, the temperature is
controlled by controlling the current value to be supplied, and the
magnitude of restoration of the shape memory alloy wire is
controlled.
[0063] In the structure, the holder frame 42 is pulled rotatably in
counterclockwise direction round the shaft 45 by the elastic force
of the elastic member 46, on the other hand, a predetermined
current is supplied to the shape memory alloy wire 47 for heating
to cause a memorized predetermined shrink deformation, the holder
frame 42 is pulled rotatably in clockwise direction round the shaft
45 by the shrinking force of the shape memory alloy wire 47, thus
when image is not corrected, the pull force in counterclockwise
direction exerted by the elastic member 46 balances the pull force
in clockwise direction exerted by the shape memory alloy wire 47,
and the holder frame 42 is positioned at the standby position of no
image shake correction.
[0064] When an image shake correction starts, an electric current
corresponding to the correction magnitude is supplied to the shape
memory alloy wire 47. If the current value corresponding to the
correction magnitude is larger than the predetermined current value
which have been set when the above-mentioned holder frame 42 is set
at the standby position, the shrinking deformation length of the
wire 47 is larger, and the holder frame 42 rotates from the standby
position in clockwise direction and moves approximately in X-axis
positive direction (wire 47 side). On the other hand, if the
current value corresponding to the correction magnitude is smaller
than the predetermined current value which has been set when the
above-mentioned holder frame 42 is set at the standby position, the
shrinking deformation length of the wire 47 is smaller, and the
holder frame 42 rotates from the standby position in
counterclockwise direction and moves approximately in X-axis
negative direction (elastic member 46 side).
[0065] The driving mechanism for moving the correction lens in
Y-axis direction is operated in the same manner as that in X-axis,
and by combining two driving mechanisms, the image shake correction
optical unit for correcting image shake on XY-plane perpendicular
to the optical axis is structured.
[0066] The control circuit suitable for the structure in accordance
with the third embodiment is a control circuit similar to the
control circuit used in the first embodiment shown in FIG. 5, and
the control circuit for the second embodiment has the structure
that the heater driving unit shown in FIG. 5 is replaced with a
heater driving unit for heating the shape memory alloy wire of
X-axis direction driving mechanism and a heater driving unit for
heating the shape memory alloy wire of Y-axis direction driving
mechanism, and the control circuit is operated in the same manner
as that of the above-mentioned first embodiment and the description
is omitted.
[0067] [Fourth Embodiment]
[0068] The fourth embodiment is described. FIG. 9 is a plan view
for illustrating the structure of an image shake correction optical
unit 50 in accordance with the fourth embodiment, one unit can
moves a correction lens simultaneously in X-axis direction and
Y-axis direction.
[0069] In FIG. 9, 51 denotes a fixed frame having an aperture 51a
at the center, and which is incorporated in a lens barrel of a lens
system not shown in the drawing. A holder frame 52 which holds the
correction lens 53 is located at the aperture 51a.
[0070] Pins 54a, 54b, 54c, and 54d are provided on the fixed frame
51 apart same distance from X-axis, and pins 54e, 54f, 54g, and 54h
are provided on the fixed frame 51 apart same distance from
Y-axis.
[0071] A shape memory alloy wire 55a is provided extendedly between
the pins 54a and 54b, a shape memory alloy wire 55b is provided
extendedly between the pins 54c and 54d, a shape memory alloy wire
55c is provided extendedly between the pins 54e and 54f, and a
shape memory alloy wire 55d is provided extendedly between the pins
54g and 54h so that all the shape memory alloy wires surround the
holder frame 52 which holds the correction lens 53. The respective
wires are in contact with the holder frame 52 pressingly and
function to set the holder frame 52 so that the center of the
correction lens is located at the position coincident with the
optical axis.
[0072] A shrunk shape with a predetermined size has been memorized
in the shape memory alloy wires 55a to 55d previously, when a
current is supplied to the shape memory alloy wires to heat up to a
predetermined temperature, the shape memory alloy wires are
restored to the memory shape. Because the size of shape memory
alloy wires after restoration depends on the temperature, the
temperature is controlled by controlling the current value to be
supplied, and the magnitude of restoration of the shape memory
alloy wires is controlled.
[0073] In the above-mentioned structure, the condition in which a
current is not supplied to the respective shape memory alloy wires
for heating represents the standby condition, and in the standby
condition, the holder frame 52 is located at the position where the
center of the correction lens 53 is coincident with the optical
axis. FIG. 9 shows this condition.
[0074] When an image shake correction starts, a current
corresponding to the correction magnitude is supplied to the shape
memory alloy wires 55a to 55d. When the correction lens 53 is
wanted to be moved in X-axis positive direction (right direction in
FIG. 9), a current is supplied to the shape memory alloy wire 55c
for heating, the wire 55c is restored to the memory shape and
shrinks against to the elastic force of the wire 55d, and the wire
55c is deformed to a form which is more approximate to a straight
line. As the result, the wire 55c pushes the holder frame 52 in
X-axis positive direction, and the correction lens 53 is moved in
X-axis positive direction.
[0075] The correction lens 53 is wanted to be moved in X-axis
negative direction (direction to the left in FIG. 9), a current is
supplied to the shape memory alloy wire 55d in the same manner as
described herein above, and the correction lens 53 is moved in
X-axis negative direction.
[0076] Further, the correction lens 53 is wanted to be moved in
Y-axis positive direction (upper direction in FIG. 9), a current is
supplied to the shape memory alloy wire 55b for heating to push the
holder frame 53 in Y-axis positive direction, and the correction
lens 53 is moved in Y-axis positive direction. When the correction
lens 53 is wanted to be moved in Y-axis negative direction
(downward direction in FIG. 9), a current is supplied to the shape
memory alloy wire 55a for heating to push the holder frame 53 in
Y-axis negative direction, and the correction lens 53 is moved in
Y-axis negative direction.
[0077] FIG. 10 is a block diagram for illustrating the structure of
the control circuit 60 for controlling the correction optical unit.
The control circuit 60 has a CPU 61 as the main component, a camera
shake sensor 64, a memory unit 65, and an exposure controller 66
are connected to the input/output port of the CPU 61 and heater
driving units 63a to 63d for heating the respective shape memory
alloy wires 55a to 55d are connected to the output port of the CPU
61.
[0078] Current value data for heating corresponding to the image
shake magnitude is stored in the memory unit 65. The relation
between the current value to be supplied to the shape memory alloy
wire and the magnitude of the deformation length of the memorized
shape is previously measured and further the current value is
determined based on the image shake correction magnitude namely the
displacement of the correction lens.
[0079] The control circuit selects shape memory alloy wires 55a to
55d to be heated based on the image shake correction magnitude and
direction detected by the camera shake sensor 64, and a current
value corresponding to the image shake correction magnitude is
determined from the memory data of the memory unit 65, and supplies
an electric current to the selected shape memory alloy wire. Thus
the correction lens is moved to the position for correcting the
detected image shake, and the image shake is corrected.
[0080] [Fifth Embodiment]
[0081] The fifth embodiment is described. The fifth embodiment has
a structure in which the image shake is corrected by inclining a
correction lens with respect to the optical axis.
[0082] FIG. 11 is a cross sectional view for illustrating the
structure of a correction optical unit. FIG. 12 is an enlarged
cross sectional view for illustrating the structure of an inclining
mechanism of the correction optical unit, and FIG. 13 is a cross
sectional view along the line A-A in FIG. 11. FIG. 14 is a cross
sectional view for illustrating the inclined correction optical
unit shown in FIG. 11.
[0083] In FIG. 11 to FIG. 14, a correction optical unit 70 is
provided with a holder frame 72 for supporting correction lenses
71a and 71b and a fixed frame 73 mounted in a lens barrel not shown
in the drawing, the holder frame 72 and the fixed frame 73 are
engaged with a cylindrical engaging unit 77.
[0084] At positions corresponding where the periphery of the
engaging unit is divided into a plurality of angular intervals (for
example, 90 degrees, 120 degrees), a plurality of driving members
74 (74a to 74d in the following description) consisting of shape
memory alloy are inserted between the end face of a flange 72a
formed on the end of the holder frame 72 and the end face of a
flange 73a formed on the end of the fixed frame 73 in the engaging
unit 77, and as the result the flange 72a and the flange 73a are
pressed by a plurality of elastic members 75 (75a to 75d in the
following description) such as U-shaped springs.
[0085] For the purpose of description, as shown in FIG. 13, the
exemplary structure in which the engaging unit periphery is divided
into 90 degree intervals and the orthogonal ordinate system having
the optical axis coincident with Z-axis is introduced, the driving
members 74a and 74b consisting of shape memory alloy are located in
Y-axis direction, and the driving members 74c and 74d consisting of
shape memory alloy are located in X-axis direction is
described.
[0086] A shrunk shape with a predetermined size has been memorized
in the driving members 74a to 74d consisting shape memory alloy
previously. Heaters 76a to 76d are provided on the outside of the
respective driving members 74a to 74d, when the heaters 76a to 76d
heat the respective driving members 74a to 74d consisting of shape
memory alloy up to a predetermined temperature, the driving members
74a to 74d are restored to the memory shape. Because the size of
shape memory alloy after restoration depends on the temperature,
the temperature is controlled by controlling the current value to
be supplied, and the magnitude of restoration of the shape memory
alloy wires is controlled.
[0087] In the above-mentioned structure, the condition in which no
current is supplied to heaters 76a to 76d and the respective
driving members 74a to 74d consisting of shape memory alloy are not
heated and represents the standby condition. The holder frame 72 is
not inclined with respect to the fixed frame 73, and the center of
the correction lenses 71a and 71b is located at the position
coincident with the optical axis.
[0088] When an image shake correction starts, an electric current
is supplied to any one or two of the heaters 76a to 76d
correspondingly to the correction magnitude to incline the holder
frame 72 with respect to the fixed frame 73. For example, as shown
in FIG. 14, in order to incline the incident light which has passed
the correction lens downward in Y-plane, a current is supplied to
the heater 76a to heat the driving member 74a consisting of shape
memory alloy. The driving member 74a is restored to the memory
shape and the diameter increases (becomes larger in the optical
axis direction), the upper side of the holder frame 72 is pushed
out to the right side with respect to the fixed frame 73, and the
incident light which has passed the correction lens is inclined
downward in Y-axis plane.
[0089] The control circuit suitable for the structure in accordance
the fifth embodiment has the same structure that, in the control
circuit in accordance with the fourth embodiment shown in FIG. 10,
the wires 55a to 55d consisting of shape memory ally are replaced
with the heaters 76a to 76d, and the control circuit is operated in
the same manner as that of the above-mentioned fourth embodiment
and the description is omitted.
[0090] In the embodiments described hereinbefore, image shake
correction driving mechanisms which utilize shape memory alloy for
correction in either X-axis direction and Y-axis direction,
actuators having other structures may be used combinedly. For
example, an image shake correction driving mechanism which utilizes
shape memory alloy may be used combinedly with a driving mechanism
which utilizes piezoelectric transducer, which is excellent in
controllability. In this case, a driving mechanism which utilizes a
piezoelectric transducer is used for driving in the direction in
which image shake occurs more often and a driving mechanism which
utilizes shape memory alloy is used for driving in the direction in
which image shake occurs more seldom, thereby image shake is
corrected more precisely and the driving mechanism is made compact
and light weight.
[0091] FIG. 15 is a cross sectional view for illustrating the
structure of a camera which is provided with one of the image shake
correction devices explained in the first to fifth embodiments. In
FIG. 15, 101 denotes a camera body, 111 denotes a photographic lens
barrel. The photographic lens barrel 111 accommodates a
photographic lens 112 and an optical element 113 of an image shake
correction device behind the photographic lens 112, and these
components forms an optical system 114.
[0092] On the other hand, the camera body 101 accommodates a quick
return mirror 105 in the optical path, a focusing plate 106,
apentaprism107, and an ocular lens 108, and the incident light
which has passed through the optical system 114 is reflected from
the quick return mirror 105 to form an object image on the focusing
screen 106, and the object image is observed through the pentagonal
prism 107 and eyepiece lens 108. A film F is located on the image
forming plane behind the quick return mirror 105, the quick return
mirror 105 is turned upward to allow the incident light which has
passed the optical system 114 to form an image on the film F for
exposure.
[0093] An angular acceleration sensor not shown in the drawing is
provided for detecting camera shake in the camera body 101, and
when a shutter button is pushed, the optical element 113 for
correcting image shake is driven by a driving mechanism not shown
in the drawing to correct image shake. Simultaneously when the
shutter button is pushed, the quick return mirror 105 is lifted to
allow the incident light which has passed the optical system 114 to
form an image on the film F, therefore the image shake on the focal
plane is corrected even though the camera shake is caused in
photographing, and an object image is photographed without image
shake.
[0094] As described hereinbefore, the image shake correction device
for an optical apparatus of the present invention is provided with
a correction optical element for correction in the optical path of
the principal optical system for driving the correction optical
element correspondingly to the detected image shake magnitude to
correct the image shake on the image forming plane of an optical
system. By employing the driving mechanism which utilizes shape
memory alloy for driving a correction lens for correcting the image
shake, there is provided a compact light-weight image shake
correction device, in comparison with a conventional image shake
correction device having a driving mechanism which utilizes a
piezoelectric transducer or moving coil for driving a correction
lens.
* * * * *