U.S. patent application number 10/265110 was filed with the patent office on 2003-02-13 for image pickup device having means for correcting the motion of an image.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Kudo, Toshimichi.
Application Number | 20030030728 10/265110 |
Document ID | / |
Family ID | 15109620 |
Filed Date | 2003-02-13 |
United States Patent
Application |
20030030728 |
Kind Code |
A1 |
Kudo, Toshimichi |
February 13, 2003 |
Image pickup device having means for correcting the motion of an
image
Abstract
There is disclosed an image pickup device comprising a motion
detecting circuit for detecting the motion of the image, from an
image signal obtained from an image pickup element, a motion sensor
for physically detecting the motion of the device, a memory for
storing the image signal, a motion correcting circuit for
correcting the motion by shifting the image readout position from
the memory according to the motion detected by the motion detecting
circuit, and a control circuit for controlling the function of the
motion correcting circuit according to the output of the motion
sensor.
Inventors: |
Kudo, Toshimichi; (Fujisawa,
JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
15109620 |
Appl. No.: |
10/265110 |
Filed: |
October 7, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10265110 |
Oct 7, 2002 |
|
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08864082 |
May 28, 1997 |
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6501503 |
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Current U.S.
Class: |
348/208.6 ;
348/208.2; 348/208.5; 348/E5.046 |
Current CPC
Class: |
H04N 5/23283 20130101;
H04N 5/23267 20130101; G02B 27/646 20130101; H04N 5/23248 20130101;
H04N 5/23254 20130101; H04N 5/23258 20130101 |
Class at
Publication: |
348/208.6 ;
348/208.2; 348/208.5 |
International
Class: |
H04N 005/225 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 1996 |
JP |
8-133643 |
Claims
What is claimed is:
1. An image pickup device comprising: image pickup means for taking
the image of an object and generating an image signal; memory means
for storing the image signal obtained by said image pickup means;
motion detecting means for detecting the motion of the image, from
the image signal obtained from said image pickup means; readout
control means for reading the image signal from said memory means
by controlling the readout address according to the result of
detection by said motion detecting means; and blur detecting means
for detecting the vibration of said image pickup means and
controlling the function of said readout control means according to
the result of said detection.
2. An image pickup device according to claim 1, wherein said
readout control means is adapted to execute said control of the
readout address, in case said blur detecting means detects said
vibration.
3. An image pickup device according to claim 1, further comprising
optical blur correcting means for optically correcting the image
blur based on the result of detection by said blur detecting
means.
4. An image pickup device comprising: image pickup means for taking
the image of an object and generating an image signal; blur
detecting means for detecting the vibration of said image pickup
means; filter means with variable filter characteristics, for
passing a detection signal of said blur detecting means; output
control means for controlling the output of said filter means;
control means for controlling said filter means and said output
control means according to said detection signal; and optical blur
correcting means for optically correcting the blur of the image
taken by said image pickup means, based on the output of said
output control means.
5. An image pickup device according to claim 4, wherein said
control means is adapted to so execute control as to elevate the
low-region cut-off frequency of said filter means in case the
vibration state indicated by said detection signal is stable.
6. An image pickup device according to-claim 4, wherein said
control means is adapted to so execute control as not to release
the output of said filter means, in case the vibration state
indicated by said detection signal is stable.
7. An image pickup device according to claim 6, wherein said
control means is adapted to release a signal for maintaining said
optical blur correcting means at the optical center, in case the
vibration state indicated by said detection signal is stable.
8. An image pickup device according to claim 4, wherein said
optical blur correcting means includes a variable angle prism for
transmitting said image of the object to said image pickup means,
drive means for driving said variable angle prism, angle detecting
means for detecting the vertex angle of said variable angle prism,
and target value generating means for generating a target value of
the vertex angle of said variable angle prism, from the results of
detection by said blur detecting means and said angle detecting
means, and said drive means is adapted to drive said variable angle
prism in such a manner that the target value generated by said
target value generating means is reached.
9. An image pickup device according to claim 1, wherein said blur
detecting means is adapted to detect the vibration in mutually
orthogonal two directions.
10. An image pickup device according to claim 4, wherein said blur
detecting means is adapted to detect the vibration in mutually
orthogonal two directions.
11. An image pickup device according to claim 1, wherein said blur
detecting means is adapted to detect the vibration by an angular
velocity sensor.
12. An image pickup device according to claim 4, wherein said blur
detecting means is adapted to detect the vibration by an angular
velocity sensor.
13. An image pickup device according to claim 1, wherein said image
pickup device includes a solid-state image pickup element.
14. An image pickup device according to claim 4, wherein said image
pickup device includes a solid-state image pickup element.
15. An image pickup device according to claim 3, wherein said
optical blur correcting means includes a variable angle prism for
transmitting said image of the object to said image pickup means,
drive means for driving said variable angle prism, angle detecting
means for detecting the vertex angle of said variable angle prism,
and target value generating means for generating a target value of
the vertex angle of said variable angle prism, from the results of
detection by said blur detecting means and said angle detecting
means, and said drive means is adapted to drive said variable angle
prism in such a manner that the target value generated by said
target value generating means is reached.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an image pickup device with
image blur correcting function, adapted for use in a video camera
or the like.
[0003] 2. Related Background Art
[0004] The image taking equipment such as video camera or
electronic camera in recent years has shown remarkable progress in
compactization and in the multitude of functions.
[0005] On the other hand, the hand vibration has been a drawback
inherent to such equipment. Particularly in a compact video camera,
the vibration of the supporting hand or of other may cause a blur
in the object image, resulting in an unpleasant image or a
deterioration in the resolving power. Such phenomenon is
particularly conspicuous in the video camera provided with a lens
of a high magnification, and the blur becomes larger and more
noticeable at the telephoto side.
[0006] For this reason there have been proposed and commercialized
various video cameras with a function for correcting the image blur
resulting from the vibration of hand or of other causes (such
function being hereinafter called blur correcting function). An
example of such video cameras is a video camera 400 shown in FIG.
1, with electronic blur correcting function.
[0007] In such video camera 400, an image signal obtained from a
solid-state image pickup element 410 under the control of a
solid-state image pickup element drive control circuit 415 is
supplied to an analog signal processing circuit 411, and, after
predetermined signal processing therein, is digitized by an
analog/digital (A/D) converting circuit 412 to obtain digital image
data, which are stored in a field memory circuit 413 and are
supplied to an image motion detecting circuit 416.
[0008] In case the video camera 400 is set, by an unrepresented
switch, at a mode in which the blur correcting function is
activated (hereinafter called blur correcting mode), the image
motion detecting circuit 416 executes an image motion detecting
process on the image data from the A/D converting circuit 412, and
sends the result of detection to a field memory control circuit
417.
[0009] In response to the result of detection from the image motion
detecting circuit 416, the field memory control circuit 417
controls the reading operation for the image data stored in the
field memory circuit 413.
[0010] More specifically, the field memory control circuit 417
controls the read-out addresses of the field memory circuit 413 in
such a manner that the image data of an area, smaller by a
predetermined number of pixels, are read from the field memory
circuit 413 to a digital signal processing circuit 414.
[0011] The read-out address of the field memory circuit 413 can be
moved within an area of the difference between the image data
stored in the field memory circuit 413 and those read
therefrom.
[0012] Thus the field memory control circuit 417 can execute the
correction of the image blur by moving the read-out address
according to the result of detection from the image motion
detection circuit 416, within such movable range of the read-out
address.
[0013] The image data, read from the field memory circuit 413 under
the control of the field memory control circuit 417, are supplied
to the digital signal processing circuit 414, and are subjected
therein to interpolation to the standard number of pixels matching
the predetermined television system. Thus interpolated image data
are supplied to and displayed on an unrepresented monitor.
[0014] On the other hand, there is known a video camera capable of
correcting the image blur, utilizing an angular velocity sensor for
detecting the vibration of the hand or of other causes and a
variable angle prism (VAP) for correcting the image blur. In such
video camera, the object image is focused on the light-receiving
face of a solid-state image pickup device through the VAP, and, in
the blur correcting mode, a signal representing the vibration,
obtained by a external sensor such as an angular velocity sensor,
is subjected to a filtering process consisting of amplification
after the elimination of the DC component thereof and cutting-off
of the low-frequency components. Such filtering process provides
the target value of the vertex angle of the VAP, according to which
the angle of the VAP is varied to achieve optical correction of the
image blur. However, if such video camera is stably placed for
example on a tripod in the blur correcting mode, the blur of the
object image resulting for example from the noises released from
the angular velocity sensor may become unnegligible. Therefore, in
the video camera of the above-mentioned kind, it has been proposed,
in case the video camera is identified to be in a stable state, to
eliminate such noises in the output signal of the angular velocity
sensor by limiting the frequency band of such output signal with a
high-pass filter (HPF) of which cut-off frequency is shifted to a
higher frequency. Such method allows to prevent the blur in the
object image, resulting from the noises released from the angular
velocity sensor.
[0015] In the image pickup device such as the video camera 400,
however, in case the device is in the blur correcting mode and is
free from the vibration caused for example by hand, if the object
itself to be captured by the solid-state image pickup element 410
vibrates, such vibration is detected by the image motion detecting
circuit 416 and the blur correction is conducted by the result of
such detection. In such case, there is encountered a defective
situation where the background or the entire image area, which
should appear standstill, is displayed in the vibrating state.
[0016] Also in the image pickup device such as the video camera
with optical image blur correcting function utilizing the angular
velocity sensor and the variable angle prism, in case such device
is placed in a stable state and is free from the vibration caused
for example by hand, the blur in the object image, resulting for
example from the noises in the output signal of the angular
velocity sensor, is prevented by limiting the frequency band of the
output signal of the angular velocity sensor through a shift of the
cut-off frequency of the high-pass filter to a higher frequency,
but, if the video camera is equipped with the lens of an ultra high
magnification, the complete prevention of the image blur cannot be
achieved unless the cut-off frequency of the high-pass filter is
shifted to a considerably high frequency.
[0017] It is therefore conceivable, in such video camera, to shift
the cut-off frequency of the high-pass filter to a considerably
high frequency if the device is in a stable state.
[0018] However, if a vibration is suddenly given after such
frequency shift, it becomes necessary to execute the blur
correction by returning the cut-off frequency of the high-pass
filter to the ordinary state, but the returning of the cut-off
frequency of the high-pass filter from such considerably high
shifted frequency to the ordinary cut-off frequency requires a
certain time. For this reason, there is required an additional time
before the effect of blur correction can be reached.
SUMMARY OF THE INVENTION
[0019] The present invention is proposed to resolve the drawbacks
mentioned above, and a first object thereof is to provide an image
pickup device capable of providing a satisfactory image, by
executing exact blur correction of the image without erroneous
operation according to the vibration state of the device.
[0020] A second object of the present invention is to provide an
image pickup device capable of reducing the time required to obtain
the effect of blur correction from the stable state.
[0021] The above-mentioned objects can be attained, according to a
preferred embodiment of the present invention, by an image pickup
device comprising image pickup means for taking the image of an
object thereby generating an image signal, memory means for storing
the image signal obtained by the image pickup means, motion
detecting means for detecting the motion of the image based on the
image signal obtained by the image pickup means, readout control
means for reading the image signal from the memory means by
controlling the readout address according to the result of
detection by the motion detecting means, and vibration detecting
means for detecting the vibration of the image pickup means and
controlling the function of the readout control means according to
the result of such detection.
[0022] Also according to another preferred embodiment of the
present invention, there is provided an image pickup device
comprising image pickup means for taking the image of an object
thereby generating an image signal, vibration detecting means for
detecting the vibration of the image pickup means, filter means
with variable filter characteristics for passing the detection
signal generated by the vibration detecting means, output control
means for controlling the output of the filter means, control means
for controlling the filter means and the output control means
according to the detection signal, and optical vibration blur
correcting means for optically correcting the blur in the image
taken by the image pickup means, based on the output of the output
control means.
[0023] Still other objects of the present invention, and the
features thereof, will become fully apparent from the following
description which is to be taken in conjunction with the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a block diagram showing the configuration of a
video camera provided with a blur correcting device;
[0025] FIG. 2 is a block diagram showing the configuration of a
first embodiment in which the present invention is applied to a
video camera;
[0026] FIG. 3 is comprised of FIGS. 3A and 3B are block diagrams
showing the configuration of a second embodiment of the present
invention;
[0027] FIG. 4 is a view showing the configuration of a variable
angle prism adapted for use in an optical blur correcting unit in
an embodiment of the present invention;
[0028] FIG. 5 is a block diagram showing a third embodiment of the
present invention; and
[0029] FIG. 6 is a flow chart showing the functions of a signal
processing circuit in a video camera embodying the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] In the following there will be explained a first embodiment
of the present invention, with reference to the attached
drawings.
[0031] The image pickup device of the present invention is
applicable for example to a video camera 100 shown in FIG. 2.
[0032] The video camera 100 with electronic blur correcting
function is provided, as shown in FIG. 2, with a solid-state image
pickup element 101 composed for example of a CCD (charge coupled
device), a solid-state image pickup device drive control circuit
106 for controlling the charge accumulation and readout of the
solid-state image pickup element 101, an analog/digital (A/D)
converting circuit 103 receiving the output of the solid-state
image pickup element 101, a field memory circuit 104 receiving the
output of the A/D converting circuit 104 and storing the image of
an image frame, an image motion detecting circuit 107 receiving the
output of the A/D converting circuit 104 and detecting the motion
of the image based on the image signal, a field memory control
circuit 108 receiving the output of the image motion detecting
circuit 107 and controlling the readout position of the image
information from the field memory circuit 104, and a digital signal
processing circuit 105 receiving the output of the field memory
circuit 104.
[0033] The video camera 100 is further provided with a blur
detecting unit 110 which physically detects the vibration applied
to the video camera and is composed, though not illustrated, of two
independent blur detecting units, namely a blur detecting unit for
the vertical (pitching) direction and that for the horizontal
(yawing) direction.
[0034] These two blur detecting units have similar configurations,
and each is provided with an angular velocity sensor 111, a DC
component cut-off filter 112 for receiving the output of the
angular velocity sensor 111, an amplifier 113, and a blur state
discrimination circuit 114.
[0035] As the above-mentioned blur detecting unit for the vertical
direction and that for the horizontal direction are of similar
configurations and are so designed as to effect similar functions,
the blur detecting unit 110 in the following description will be
assumed as the above-mentioned one for the vertical direction, for
the purpose of simplicity.
[0036] In the following there will be explained the function of the
video camera 100 when it is set at the blur correcting mode.
[0037] The charge accumulation and readout of the solid-state image
pickup element 101 are controlled by the solid-state image pickup
element drive control circuit 106, whereby the solid-state image
pickup element 101 converts the object image, focused on the light
receiving face thereof through an unrepresented optical system,
into an electrical signal and sends such electrical signal
(hereinafter called image signal) to the analog signal processing
circuit 102.
[0038] The analog signal processing circuit 102 applies
predetermined signal processing to the image signal obtained from
the solid-state image pickup element 101, and sends the processed
image signal to the A/D converting circuit 103.
[0039] The A/D converting circuit 103 digitizes the image signal
from the analog signal processing circuit 102, and sends thus
digitized image signal (hereinafter called image data) to the field
memory circuit 104 and the image motion detecting circuit 107.
[0040] The field memory circuit 104 stores the image data of an
image frame, supplied from the A/D converting circuit 103.
[0041] On the other hand, the image motion detecting circuit 107
detects the motion in the image by applying a motion detecting
process to the image data from the A/D converting circuit 103, and
supplies the field memory control circuit 108 with the result of
detection. The image motion detecting circuit 107 detects the
motion in the entire image area by extracting feature points of the
image in plural positions within the image area and calculating
motion vectors from the changes in the feature points between
plural images of different times.
[0042] On the other hand, in the blur detecting unit 110, the
angular velocity sensor 111 detects the vibration of the video
camera 100 in the vertical direction.
[0043] The detection signal released from the angular velocity
sensor 111 is supplied to the amplifier 113, after elimination of
the DC component by the DC cut-off filter 112.
[0044] The amplifier 113 amplifies the detection signal, supplied
through the DC cut-off filter 112, for supply to the blur state
discrimination circuit 114.
[0045] The blur state discrimination circuit 114 discriminates,
based on the detection signal from the amplifier 113, whether the
vibration of the vertical direction is applied to the video camera
100, and sends the result of discrimination to the field memory
control circuit 108.
[0046] Also the above-mentioned blur detecting unit for the
horizontal direction discriminates whether the vibration of the
horizontal direction is applied to the video camera 100, in a
similar manner as in the blur detecting unit 110 for the vertical
direction.
[0047] Consequently the field memory control circuit 108 receives
the results of discrimination of the vibration in the vertical and
horizontal directions.
[0048] The field memory control circuit 108 controls the readout
operation of the image data from the field memory circuit 104,
according to the result of detection of the image motion
electronically determined by the image motion detecting circuit 107
and the results of discrimination of the vertical and horizontal
directions supplied from the blur detecting units 110.
[0049] More specifically, the field memory control circuit 108 so
controls the field memory circuit 104 as to read the image data of
an area which is smaller by a predetermined number of pixels.
Stated differently, the readout area of the memory is smaller than
the write-in area thereof.
[0050] The readout address of the field memory circuit 104 can be
moved within an area of the difference between the image data
stored in the field memory circuit 104 and those read therefrom
under the control of the field memory control circuit 108.
[0051] Thus, the field memory control circuit 108 executes
correction of the image blur by moving the readout address of the
field memory circuit 104, within the movable range of the readout
address, according to the result of detection supplied from the
image motion detecting circuit 107.
[0052] In such blur correction, the field memory control circuit
108 does not execute the blur correction in the vertical direction
or in the horizontal direction respectively in case the video
camera 100 is not given the vibration in the vertical or horizontal
direction, according to the result of discrimination received from
the blur detecting unit 110.
[0053] Stated differently, the field memory control circuit 108
executes the correction of the image blur by moving the readout
address of the field memory circuit 104, only in case the vibration
is applied to the video camera 100 in the vertical or horizontal
direction, in the direction of such vibration.
[0054] Under the above-explained control of the field memory
circuit 104 by the field memory control circuit 108, the image data
stored in the field memory circuit 104 are supplied to the digital
signal processing circuit 105.
[0055] The digital signal processing circuit 105 executes
interpolation of the image data supplied from the field memory
circuit 104 to match a predetermined television system. Thus
interpolated image data are supplied to and displayed on an
unrepresented monitor or the like.
[0056] As explained in the foregoing, the video camera 100
physically detects whether a vibration is applied thereto in the
vertical or horizontal direction, and executes correction of the
image blur in the direction of such vibration only if such
vibration is applied in the vertical or horizontal direction.
Consequently, if the vibration is not applied to the video camera
100 but the object taken by the solid-state image pickup element
101 is vibrating, the correction of the image blur is not conducted
even if the video camera 100 is set at the blur correcting mode. It
is therefore rendered possible to prevent a situation where the
background which should appear still, or the entire image area, is
displayed in the vibrating state.
[0057] Consequently the video camera 100, being capable of exact
correction of the image blur according to the state of vibration
applied to the video camera 100, can provide a satisfactory
image.
[0058] In the following there will be explained a second embodiment
of the present invention with reference to the attached
drawings.
[0059] The image pickup device of the present embodiment is
applicable, for example, to a video camera 200 as shown in FIGS. 3A
and 3B.
[0060] The video camera 200 is provided, as shown in FIGS. 3A and
3B, with an optical blur correcting unit 210 for optically
correcting the image blur, in addition to the components of the
above-explained video camera 100 shown in FIG. 2.
[0061] The optical blur correcting unit 210 is composed, though not
illustrated, of two independent optical blur correcting units
respectively for the vertical (pitching) direction and for the
horizontal (yawing) direction, wherein the output of the blur
correcting unit for the vertical direction in the blur correcting
unit 110 is supplied to the above-mentioned optical blur correcting
unit of the vertical direction while that of the blur correcting
unit for the horizontal direction is supplied to the optical blur
correction unit of the horizontal direction.
[0062] In the video camera 200 shown in FIGS. 3A and 3B, components
equivalent in function to those in the video camera 100 shown in
FIG. 2 are represented by corresponding numbers and will not be
explained further.
[0063] Also, since the above-mentioned optical blur correcting unit
for the vertical direction and that for the horizontal direction
have similar configurations and are so designed as to effect
similar functions, the blur correcting unit 110 in the following
description is assumed as that for the vertical direction and the
optical blur correcting unit 210 is assumed as that for the
vertical direction, for the purpose of simplicity.
[0064] The output of the amplifier 113 is supplied not only to the
blur state discrimination circuit 114 but also to optical blur
correcting means 210, which is provided with a signal processing
circuit 211 for receiving the output of the amplifier 113, an adder
212 for receiving the output of the signal processing circuit 211,
a drive circuit 213 for receiving the output of the adder 212, an
actuator 214 for receiving the output of the drive circuit 213, a
variable angle prism (VAP) 215 for receiving the output of the
actuator 214, an angle sensor 216 for receiving the output of the
VAP 215, and an amplifier 217 for receiving the output of the angle
sensor 216. The adder 212 also receives the output of the amplifier
217.
[0065] The VAP 215 is so provided that the image of the object is
focused on the unrepresented light-receiving face of the
solid-state image pickup device 101 through the VAP 215.
[0066] The VAP 215 is composed, as shown in FIG. 4, of mutually
opposed two glass plates 215a, 215b, bellows 215c, 215d so provided
as to connect the two glass plates 215a, 215b, and liquid 215e of a
high refractive index filling the space enclosed by the glass
plates 215a, 215b and the bellows 215c, 215d, and the glass plates
215a, 215b are respectively provided with rotary shafts 215f,
215g.
[0067] In such VAP 215, when a glass plate 215a is rotated by an
angle .delta. about the rotary shaft 215f, the incident light beam
215h is deflected by an angle .alpha. by the principle of a
wedge-shaped prism, and the incident light beam 215h is similarly
deflected also when the other glass plate 215b is rotated about the
rotary shaft 215g.
[0068] The actuator 214 is so provided as to rotate the two glass
plates 215a, 215b thereby varying the vertex angle (hereinafter
called VAP angle) formed by the two glass plates 215a, 215b. The
correction of the image blur is achieved by the variation of the
VAP angle.
[0069] The signal processing circuit 211 is composed for example of
a microcomputer, and effects signal processing for generating the
optimum angle (hereinafter called target angle) of the VAP.
[0070] In the following there will be explained the function of the
optical blur correcting unit 210.
[0071] In case the video camera 200 is set at the blur correcting
mode, the blur detecting unit 110 detects the vibration of the
video camera 200 in the vertical direction by means of the angular
velocity sensor 111, and the detection signal obtained in the
angular velocity sensor 111 is supplied to the amplifier 113 after
the elimination of the DC component by the DC cut-off filter 112.
The amplifier 113 amplifies the detection signal supplied through
the DC cut-off filter 112, and sends the detection signal to the
blur state discrimination circuit 114 and the signal processing
circuit 211 of the optical blur correcting means 210.
[0072] The signal processing circuit 211 applies predetermined
signal processing, for generating the target value of the VAP
angle, to the signal from the amplifier 113.
[0073] More specifically, the signal processing circuit 211
amplifies the signal from the amplifier 113 after cutting off the
DC component, and sends the amplified signal to the adder 212 after
cutting off the low-frequency components.
[0074] On the other hand, the angle sensor 216 detects the vertex
angle of the VAP 215 and sends the corresponding detection signal
to the amplifier 217.
[0075] The amplifier 217 amplifies the detection signal from the
angle sensor 216, for supply to the adder 212.
[0076] The adder 212 calculates the difference between the signal
subjected to the predetermined signal processing in the signal
processing circuit 211 and the detection signal from the amplifier
217, and sends such difference as a control amount to the drive
circuit 213.
[0077] The drive circuit 213 drives the actuator 214 according to
the control amount obtained in the adder 212.
[0078] Consequently the angle of the VAP 215 is varied according to
the target value mentioned above and is matched with the target
value, under the control of the actuator 214 by the drive circuit
213. In this manner the correction of the image blur is achieved
for the vibration in the vertical direction.
[0079] Also the optical blur correcting unit for the horizontal
direction effects the correction of the image blur for the
vibration in the horizontal direction, in a similar manner as in
the above-explained optical blur correcting unit 210 for the
vertical direction.
[0080] As explained in the foregoing, the video camera 200, being
further provided with the optical blur correcting means 210 in the
video camera 100 shown in FIG. 2, can achieve correction of the
image blur in more exact manner, according to the state of the
vibration applied to the video camera 200.
[0081] In the above-explained embodiment, the motion detecting
means detects the motion in the image based on the image signal
obtained from the image pickup means. The motion detecting means
detects the vibration of the image pickup means and controls the
function of the readout control means according to the result of
the detection. The readout control means reads the image signal
from the memory means by controlling the readout address under the
control of the blur detecting means, according to the result of
detection thereof. Consequently the image blur is corrected
according to whether the vibration of the image pickup means is
detected or not.
[0082] The readout control means executes the above-mentioned
control of the readout address only when the blur detecting means
detects vibration. Consequently the correction of the image blur is
executed only when the vibration is applied to the image pickup
means.
[0083] Also the optical blur correcting means optically corrects
the image blur based on the result of detection by the blur
detecting means.
[0084] In the following there will be explained a third embodiment
of the present invention, with reference to the attached
drawings.
[0085] The image pickup device of the present embodiment is
applicable for example to a video camera in which the internal
configuration of the optical blur correcting unit 210 shown in FIG.
3A is modified as shown in FIG. 5.
[0086] In this video camera, the optical blur correcting unit 210
is provided with an A/D converting circuit 211a receiving the
output of the amplifier 113 of the blur correcting unit 110, a
high-pass filter (HPF) 211b receiving the output of the A/D
converting circuit 211a, a high-frequency phase correction filter
211c receiving the output of the HPF 211b, an integrator 211d
receiving the output of the high-frequency phase correction filter
211c, a switch 211e receiving the output of the integrator 211d, a
digital/analog (D/A) converting circuit 211f receiving the output
of the switch 211e, an adder 212 receiving the output of the D/A
converting circuit 211f, a drive circuit 213 receiving the output
of the adder 212, an actuator 214 receiving the output of the drive
circuit 213, a VAP 215 receiving the output of the actuator 214, a
vertex angle sensor 216 receiving the output of the VAP 215, and an
amplifier 217 receiving the output of the angle sensor 216. The
adder 212 also receives the output of the amplifier 217.
[0087] The optical blur correcting unit 210 is provided with a blur
state discriminating unit 211h receiving the output of the A/D
converting circuit 211a, and a characteristics setting unit 211g
receiving the output of the blur state discriminating unit 211h,
and the output of the characteristics setting unit 211g is supplied
to the HPF 211b and the switch 211e.
[0088] The optical blur correcting unit 210 is further provided
with a table 211i, which stores in advance plural constants used by
the characteristics setting unit 211g for determining the cut-off
frequency of the HPF 211b.
[0089] When the video camera is set at the blur correcting mode,
the switch 211e is turned on in the optical blur correcting unit
210 to supply the output of the integrator 211d to the D/A
converting circuit 211f, but, when the video camera is not set at
the blur correcting mode, the switch 211e is turned off whereby the
output of the integrator 211d is not supplied to the D/A converting
circuit 211f.
[0090] FIG. 6 is a flow chart showing the process executed in the
optical blur correcting unit 210.
[0091] In the following there will be explained the function of the
optical blur correcting unit 210 with reference to FIGS. 5 and
6.
[0092] The optical blur correcting unit 210 shown in FIG. 5 will
not be explained in detail as it is similar, except for the
internal configuration thereof, to that in the video camera 200
shown in FIGS. 3A and 3B.
[0093] In the following description, for the purpose of simplicity,
the optical blur correcting unit 210 is assumed to be that for
correcting the image blur or the vibration in the vertical
direction.
[0094] In case the video camera is set at the blur correcting mode,
the angular velocity sensor 111 in the blur detecting unit 110
detects the vibration of the video camera in the vertical
direction, and the detection signal obtained in the angular
velocity sensor 111 is supplied to the amplifier 113 after the
elimination of the DC component by the DC cut-off filter 112. The
amplifier 113 amplifies the detection signal, supplied through the
DC cut-off filter 112, for supply to the A/D converting circuit
211a.
[0095] Then the A/D converting circuit 211a digitizes the detection
signal from the amplifier 113.
[0096] The detection data, obtained by digitization in the A/D
converting circuit 211a, are supplied through the HPF 211b, the
high frequency phase correction filter 211c and the integrator 211d
in succession, to the switch 211e and the blur state discriminating
unit 211h.
[0097] The switch 211e is turned on in this state, since the video
camera is set at the blur correcting mode.
[0098] The HPF 211b is rendered capable of arbitrarily varying the
cut-off frequency for the detection data from the A/D converting
circuit 211a.
[0099] At first the blur state discriminating unit 211h
discriminates whether the video camera is in a stable state, for
example on a tripod, continuously for a predetermined period, and
sends the result of discrimination to the characteristics setting
unit 211g.
[0100] As shown in the flow chart in FIG. 6, the characteristics
setting unit 211g discriminates, based on the result of
discrimination by the blur state discriminating unit 211h, whether
the video camera 200 is in a stable continuously for a
predetermined period (step S11), and, if the video camera is
identified to be in the stable state continuously for the
predetermined period, there is selected, among the plural constants
set in advance in the table 211i, a constant that shifts the
cut-off frequency of the HPF 211b to a higher frequency and the
selected constant is set in the HPF 211b (step S12). In this manner
the cut-off frequency of the HPF 211b is shifted to a higher
frequency.
[0101] After the step S12, the characteristics setting unit 211g
turns off the switch 211e, whereby the output of the integrator
211d is not supplied to the D/A converting circuit 211f (step
S13).
[0102] After the step S13, the characteristics setting unit 211g
selects, from the table 211i, a constant that shifts the cut-off
frequency of the HPF 211b to the stationary state and sets thus
selected constant in the HPF 211b (step S14). In this manner the
cut-off frequency of HPF 211b is returned to the stationary
state.
[0103] Thus, in case the video camera is in the stable state
continuously for a predetermined period, the characteristics
setting unit 211g shifts the cut-off frequency of the HPF 211b to a
higher frequency, then the switch 211e is turned off and the
cut-off frequency of the HPF 211b is subsequently returned to the
stationary state, as explained above. In such case, the D/A
converting circuit 211f supplies the adder 212 with such a signal
that brings the VAP 215 to the optical center.
[0104] In case the step S11 discriminates that the video camera is
not in the stable state continuously for the predetermined period,
the characteristics setting unit 211g does not execute the steps
S12 to S14 but turns on the switch 211e thereby supplying the D/A
converting circuit 211f with the output of the integrator 211d
(step S15).
[0105] Consequently, in this case, the D/A converting circuit 211f
receives, through the switch 211e, the detection data of the
vibration supplied through the HPF 211b, the high-frequency phase
correction filter 211c and the integrator 211d. The D/A converting
circuit 211f converts the detection data from the switch 211e into
an analog signal and sends thus obtained analog signal to the adder
212.
[0106] On the other hand, the angle sensor 216 detects the vertex
angle of the VAP 215 and sends the detection signal to the
amplifier 216.
[0107] The amplifier 216 amplifies the detection signal from the
angle sensor 216, for supply to the adder 212.
[0108] The adder 212 calculates the difference between the output
signal of the D/A converting circuit 211f, adapted to bring the VAP
215 to the optical center, or the signal obtained from the
detection data of the vibration in the vertical direction, and the
detection signal obtained from the amplifier 216, and sends such
difference as a control amount to the drive circuit 213.
[0109] Based on the control amount obtained in the adder 212, the
drive circuit 213 drives the actuator 214.
[0110] Consequently, under the control of the actuator 214 by the
drive circuit 213, the vertex angle of the VAP 215 is varied
according to the above-mentioned control amount and is matched with
the target value. In this manner the correction of the image blur
is achieved for the vibration in the vertical direction.
[0111] Also the optical blur correcting unit for the horizontal
direction executes the correction of the image blur for the
vibration in the horizontal direction, in a similar manner as in
the above-explained optical blur correcting unit 210 for the
vertical direction.
[0112] As explained in the foregoing, in case the video camera is
set in the blur correcting mode and is in the stable state
continuously for the predetermined period, the optical blur
correcting means 210 shifts the cutoff frequency of the HPF 211b to
a higher frequency and the switch 211e is turned off, and the
cut-off frequency of the HPF 211b is returned to the stationary
state, whereby the adder 212 is given a signal that brings the VAP
215 to the optical center.
[0113] Consequently, in this case, while the VAP 215 is maintained
at the optical center, the optical blur correcting means 210
executes a process same as that in case of image blur correction
(hereinafter called stationary state). Therefore the effect of the
image blur correction can be obtained immediately even in case the
video camera is shifted from a state installed in a stable position
to a state where vibration is given suddenly.
[0114] In the foregoing embodiment, the blur detecting means
detects the vibration in the image pickup means, and the detection
signal of the blur detecting means is supplied through the filter
means to the output control means. In this state the control means
varies the filter characteristics of the filter means according to
the detection signal of the blur detecting means, and controls the
output control means. In this manner the output control means
executes output from the filter means, under the control of the
control means. Also the optical blur correcting means optically
corrects the blur in the image taken by the image pickup means,
according to the output of the output control means. Consequently,
the optical correction of the image blur is executed according to
whether the vibration of the image pickup means is detected or
not.
[0115] Also the control means executes control so as to shift the
low-frequency range cut-off frequency of the filter means to a
higher frequency when the vibration state indicated by the
detection signal is stable. Consequently, in case the image pickup
means is in a stable state, the frequency band of the detection
signal of the blur detecting means becomes limited.
[0116] Also in case the vibration state indicated by the detection
signal is stable, the control means so controls the output control
means as to inhibit the output from the filter means. Consequently,
in case the image pickup means is in a stable state, the detection
signal of the blur detecting means is not supplied to the optical
blur correcting means, so that the optical correction of the image
blur is not conducted.
[0117] Also in case the vibration state indicated by the detection
signal is stable, the control means controls the output control
means in such a manner as to maintain the optical blur correcting
means at the optical center. Consequently, when the image pickup
means is in a stable state, the optical blur correcting means is
maintained at the optical center.
[0118] Also in the optical blur correcting means mentioned above,
the target value generating means generates the target value of the
vertex angle of the variable angle prism, from the detection signal
indicating the vibration of the image pickup means, obtained from
the blur detecting means, and from the detection signal indicating
the vertex angle of the variable angle prism, obtained from the
angle detecting means. The drive means drives the variable angle
prism so as to match the target value obtained by the target value
generating means. Consequently the object image is transmitted to
the image pickup means when the vertex angle of the variable angle
prism reaches the target value mentioned above.
[0119] As explained in the foregoing, the embodiment explained
above, so designed as not to execute the correction of the image
blur in case the vibration is not applied to the device but the
object image taken by the image pickup means is vibrating, can
achieve correction of the image blur in exact manner. Consequently
there can be obtained a satisfactory display of the image.
Therefore, in case the image pickup device is free from external
vibration applied for example by a hand but the image taken by the
image pickup means is vibrating, there can be prevented the
situation where the entire image vibrates by the correction of such
external vibration.
[0120] Also the vibration is detected in the components of mutually
orthogonal two directions and the correction of the image blur is
executed in the direction of vibration applied to the image pickup
means, whereby the image blur correction can be achieved in more
precise manner, thereby providing an even better displayed
image.
[0121] Also the image blur correction in optical manner enables the
blur correction in more precise manner.
[0122] Furthermore, there are cut off noises generated by the
angular velocity sensor in order to reduce the time lag in case the
image pickup means is shifted from a state in which it is in a
stable state continuously for a predetermined period to another
state in which it is not in such stable state, whereby the
correction for the image blur is not conducted on the blur of the
object image resulting from such noises, and it is therefore
rendered possible to execute the image blur correction in an exact
manner and to reduce the time required for obtaining the effect of
the image blur correction. Consequently the effect of the image
blur correction can be obtained immediately even in case a
vibration is applied suddenly to the image pickup device while it
is placed in a stable state.
[0123] Many widely different embodiments of the present invention
may be constructed without departing from the spirit and scope of
the present invention. It should be understood that the present
invention is not limited to the specific embodiments described in
the specification, except as defined in the appended claims.
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