JP2002229089A - Vibration isolator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration isolator which prevents defects by image shake correction in changing an angle of view by deciding whether a shake signal detected by the vibration exerted to a camera exceeds a prescribed threshold continuously for a time longer than the prescribed time and exactly deciding whether this vibration is the vibration by the operation of changing the angle of view, such as panning/tilting, and stopping the image shake correction when decision is made that the vibration is the vibration in changing the angle of view. SOLUTION: A CPU 16 determines the displacement rate (shaking signal) of a vibration isolating lens 10 for correcting the image shake according to the signal from an angular speed sensor 14. The CPU decides that the vibration is the vibration in changing the angle of view and turns off the image shake correction, when the shake signal exceeds the prescribed threshold continuously for the time longer than the prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration device, and more particularly to an anti-vibration device for preventing an image blur of a camera due to vibration.

[0002]

2. Description of the Related Art For example, an anti-vibration lens is movably arranged in a plane orthogonal to an optical axis in a photographing optical system of a television camera, and when vibration is applied to a camera (photographing optical system of the camera), the vibration is canceled. 2. Description of the Related Art There is known an image stabilizing apparatus that corrects image shake by moving an image stabilizing lens in an direction by an actuator. Conventionally, in such a vibration isolator, when a vibration applied to a camera is detected by a shake detection sensor (an angular velocity sensor, an acceleration sensor, or the like), the vibration is used to capture an image at a fixed angle of view (a fixed imaging direction). It is automatically determined whether the vibration is caused by intention (camera shake or the like) or the vibration caused by the angle-of-view changing operation when intentionally changing the angle of view such as pan / tilt. That is a challenge. For example, if you intend to shoot a fixed angle of view (hereinafter,
It is appropriate to drive the anti-vibration lens so as to cancel the vibration generated at a fixed angle of view), that is, to perform image blur correction, but to change the angle of view such as pan / tilt. When the image blur correction is performed for the vibration at the time, the responsiveness to the angle-of-view changing operation is deteriorated, and the operability is impaired. Therefore, it is not desirable to execute the image blur correction. Therefore, when changing the angle of view, it is desirable not to perform the image blur correction, and it is complicated and impractical for the photographer to switch whether or not to perform the image blur correction. It is desired to automatically determine whether or not the change has been made and to automatically switch whether or not to execute image blur correction in accordance with the determination. For this reason, Japanese Unexamined Patent Publication No. Hei 5-142624 discloses that a vibration applied to a camera based on a shake signal obtained from a shake detection sensor, that is, a signal indicating the amount of shake of the camera or an image when the angle of view is changed. There has been proposed a method of automatically judging whether or not the data is a product.

According to this, the frequency of vibration at a constant angle of view, that is, the vibration caused by camera shake is about 1 to 12 Hz, whereas the vibration caused by the angle of view changing operation at the time of changing the angle of view is more than that. In consideration of the low frequency, the shake signal obtained from the shake detection sensor continues in one direction, that is, the shake center (zero value) for longer than a predetermined determination time.
If the camera shakes in any one of the positive and negative directions, it is determined that the vibration applied to the camera can be determined to be when the angle of view is changed.

[0004]

However, as a practical problem, in the method described in Japanese Patent Application Laid-Open No. 5-142624, for the following reasons, it is determined whether or not the vibration applied to the camera is caused when the angle of view is changed. It cannot be judged correctly. That is, when the angle of view is changed, it is empirically clear that not only ideal vibration (low-frequency vibration) due to the angle-of-view changing operation but also high-frequency vibration corresponding to camera shake and the like are superimposed. In particular, when the photographing optical system of the camera has a high magnification (when the focal length is long), since a minute vibration applied to the camera causes a large image shake, a shake detection sensor is used to detect the minute vibration. The sensitivity is set very high. For this reason, in the shake signal obtained from the shake detection sensor, not only ideal vibration due to the angle-of-view changing operation, but also high-frequency vibration corresponding to camera shake or the like appears remarkably as a large signal component. Then, the shake signal easily oscillates between positive and negative with respect to the shake center (zero value).

Therefore, as described in Japanese Patent Application Laid-Open No. 5-142624, when a shake signal obtained from a shake detection sensor indicates a shake in one direction for a longer time than a predetermined determination time, the camera is instructed. When it is determined that the added vibration is vibration at the time of changing the angle of view, when determining the determination time, at least the vibration at the time of changing the angle of view includes a hand shake other than the ideal low frequency vibration due to the angle of view changing operation. It must be taken into account that high frequencies corresponding to the above are also superimposed. On the other hand, for example, when the determination time is set as the vibration at the time of changing the angle of view is only the vibration of an ideal low frequency, even at the time of changing the angle of view, the determination time is longer than such a determination time. A situation occurs in which a shake signal indicating a shake in one direction is not detected.

However, considering the vibration at the time of changing the angle of view (including vibration at a high frequency), the length of the vibration signal in consideration of the variation in the time during which the shake signal continues to shake in one direction at the time of changing the angle of view is considered. Since the range and the length range in consideration of the variation in the time during which the shake signal continues to shake in one direction at a constant angle of view partially overlap, no matter what determination time is set At the time of changing the angle of view, a situation in which a one-way shake longer than the determination time is not detected, and conversely, at a constant angle of view, a one-way shake longer than the determination time is detected. May occur frequently. Therefore, it is difficult to set an appropriate determination time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and the vibration applied to a photographing optical system such as a camera, particularly the vibration applied to a high-magnification photographing optical system, is not affected by the vibration when the angle of view is changed. It is another object of the present invention to provide a vibration isolator capable of accurately discriminating a vibration in a case other than the above, and automatically switching to a proper process when judging the vibration at the time of changing the angle of view.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a vibration detecting means for detecting a vibration applied to a photographing optical system, and a vibration detected by the vibration detecting means. Correction amount output means for outputting a correction amount for correcting an image shake based on the correction amount, and image shake correction means for performing an image shake correction based on the correction amount output by the correction amount output means. In the image stabilizing apparatus, when the correction amount output from the correction amount output means continuously exceeds a predetermined threshold value different from zero value for a longer time than a predetermined time, the image blur correction by the image blur correction means is performed. Control means is provided for stopping the correction or performing image blur correction in the image blur correction means, the correction capability of which is smaller than the normal image blur correction based on the correction amount.

The invention described in claim 2 is the first invention.
In the invention described in the above, the control means reduces the correction ability after stopping the image blur correction by the image blur correction means or in the image blur correction means as compared with the normal image blur correction based on the correction amount. If the correction amount output from the correction amount output means continuously falls within a predetermined threshold for a longer time than a predetermined time after the image blur correction is performed, the image blur correction means Is characterized in that normal image blur correction based on the correction amount is started.

According to the present invention, when the correction amount for correcting the image blur continuously exceeds a predetermined threshold value different from zero value for a longer time than the predetermined time, it is determined that the angle of view is to be changed. The system automatically switches to processing such as stopping image blur correction, so that it is possible to accurately determine when the angle of view is changed and when the angle of view is constant, and to automatically change the angle of view without any trouble. The process is switched to a more appropriate one.
After the image blur correction is stopped, for example, when the angle of view is changed, if the correction amount falls within a predetermined threshold value for a longer time than a predetermined time, the normal image blur correction is performed. Is automatically started, so that the normal image blur correction can be appropriately started without any trouble after the view angle changing operation is stopped.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vibration isolator according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a configuration diagram showing an embodiment of a vibration isolator according to the present invention. Examples of the anti-vibration device include a lens device (photographing lens) for a television camera, a movie camera,
Alternatively, the anti-vibration lens 10 mounted on a still camera or the like and shown in FIG. 1 is mounted vertically (in a vertical direction) in a plane perpendicular to the optical axis in a lens device on which the anti-vibration device is mounted or a photographing optical system of the camera. ), Left and right (horizontally). Further, the anti-vibration lens 10 is moved up and down by a motor 12,
Alternatively, when the camera (photographing optical system) is vibrated, the motor 12 moves to a position where image blur is prevented (a position where the vibration is canceled out). I have. The anti-vibration lens 10 is driven in the up-down direction and the left-right direction. Since the anti-shake lens 10 is driven in the same manner based on the vibration generated in each direction, the present embodiment employs the anti-shake method in the up-down direction. A configuration for performing the vibration will be described.

An angular velocity sensor 14 shown in FIG. 1 is used as a shake detection sensor for detecting camera vibration. Note that a speed sensor, an acceleration sensor, or the like can be used instead of the angular speed sensor. This angular velocity sensor 14
Is installed, for example, on the upper surface of the lens barrel, detects the angular velocity of the vertical vibration of the lens barrel, and outputs an electric signal of a voltage corresponding to the detected angular velocity.

A CPU 16 shown in FIG. 1 obtains an electric signal output from the angular velocity sensor 14 via an A / D converter 18 to obtain an angular velocity of a vibration applied to the camera. Then, the angular velocity of the vibration is subjected to a process such as first-order integration to correct (prevent) image blur, and the position of the vibration isolating lens 10 (hereinafter, image blur correcting position), that is, the vibration of the vibration isolating lens 10 A shake signal indicating a displacement amount with respect to the center (a correction amount for correcting image shake) is obtained. Since the camera or image shake amount and the displacement amount of the image stabilizing lens 10 with respect to the shake center are associated in advance so as to prevent image shake, the shake signal obtained by the CPU 16 is the camera or image shake amount. Can be interpreted as a signal indicating

As will be described later in detail, the CPU 16 determines whether the vibration detected by the angular velocity sensor 14 is based on the shake signal based on the view angle changing operation at the time of changing the view angle such as pan / tilt, or the like. Then, it is determined whether or not the photographing is caused when the photographing of a fixed angle of view is intended. That is, it is determined whether or not the current camera operation is changing the angle of view (at the time of changing the angle of view). As a result, when it is determined that the angle of view is not changed, that is, when it is determined that the angle of view is constant, the process of turning on the image blur correction is executed. That is, the above-mentioned shake signal is output to the motor drive circuit 22 via the D / A converter 20 as a position command signal for commanding movement to the image blur correction position. On the other hand, if it is determined that the angle of view is to be changed, a process of turning off image blur correction is executed.
That is, a position command signal for moving the image stabilizing lens 10 to the shake center is output to the motor drive circuit 22 via the D / A converter 20.

The motor drive circuit 22 detects the position of the anti-vibration lens 10 by using the potentiometer
Motor 1 based on the position command signal given from U16.
2 to move the anti-vibration lens 10 to a position designated by the position command signal.

Next, the CPU 16 determines whether or not the angle of view is changed.
Will be described. CP as described above
U16 indicates whether the camera is at the time of changing the angle of view such as pan / tilt based on the shake signal detected from the angular velocity sensor 14,
It is determined whether the angle of view is constant. Therefore, first, as shown in FIG. 2, predetermined threshold values x _S1 , −x _S1 (x _S1 is positive) different from the zero value are set for (the value of) the shake signal x. At the start of the angle change operation, the shake signal x indicates a very large value in a positive or negative direction, the threshold x _S1 (or -x when at least this as in the drawing waveform S _1
S1 ). Thus, for example, the curves S ₂ , S _{3 in} FIG.
If the vibration signal x as does not exceed the threshold x _S1 or -x _S1, i.e., in the case of x _S1 ≧ x ≧ -x _S1 may be determined not to be at the angle of view changes. The threshold values x _S1 and −x _S1 are not at least zero values or values near zero values. For example, assuming that the anti-vibration lens 10 has an ability to prevent image blur of about 1/5 of the photographing screen when the focal length of the photographing optical system is about 1000 mm, suitable threshold values x _S1 , −x _S1 is set to a value near the maximum displacement amount of the anti-vibration lens 10 at that time.

On the other hand, when the shake signal x is equal to the threshold value x _S1 or -x
If it exceeds _S1, i.e., x> x _S1, or in the case of x <-x _S1, not necessarily the time necessarily angle change is believed may be due to vibration during constant angle. Therefore, next, the time (over time) during which the shake signal x continuously exceeds the threshold value x _S1 or −x _S1 is measured, and it is determined whether or not the over time exceeds a predetermined determination time t _S1. judge. If the over time exceeds the determination time t _S1 as shown in FIG. 2, it is determined that the angle of view is to be changed. On the other hand, when the over time does not exceed the determination time t _S1 as in the waveform S ₄ of FIG.
It is determined that the angle of view is constant. That is, the time during which the shake signal x exceeds the threshold value x _S1 (or −x _S1 ) at the time of changing the angle of view is longer than at least at the time of the constant angle of view, and thus the over time exceeds the determination time t _S1 . In this case, it can be determined that the angle of view has been changed.

As described above, the threshold value x _S1 (and −
x _S1 ) and the determination time t _S1 , it is possible to determine whether or not the angle of view is changed, and the threshold value x _S1 and the determination time t _S1 are determined.
Is determined by the type of the photographing optical system of the camera or the like so that it can be determined whether or not the angle of view is changed based on the threshold value x _S1 and the determination time t _S1 as described above. A suitable value is set accordingly. In the case where the vibration isolator having the same configuration according to the present invention can be used for various photographing optical systems (various lenses having different focal lengths and the like), a CPU is required.
16 automatically determines the type of the imaging optical system, and determines a suitable threshold value x predetermined in accordance with the type of the imaging optical system.
_S1 (and -x _S1) and the determination time t _S1 may be set. The threshold value x _S1 (and -x _S1 ) and the determination time t _S1 may be set by the user in the CPU 16 by a predetermined adjusting means.

In a photographing optical system in which the focal length can be changed and the shift amount of the image on the photographing screen with respect to the displacement amount of the anti-vibration lens 10 becomes constant regardless of the focal length, an angular velocity The shake signal x obtained from the output signal of the sensor 14 is changed according to the focal length. That is, even if the vibration applied to the photographing optical system is the same, the amount of shake of the image on the screen differs depending on the focal length. Therefore, the amount of displacement (the shake signal) of the image stabilizing lens 10 for correcting the amount of image shake x) is also changed by the focal length. For example, in the process of calculating the shake signal x from the output signal of the angular velocity sensor 14, the gain is changed based on the focal length (the longer the focal length (closer to the telephoto end), the greater the gain, and the larger the shake signal x Becomes larger), and if the output signal of the angular velocity sensor 14 is s and the focal length is f, the shake signal x is represented by the following equation.

X = G (f) · F (s) where F (s) indicates a value calculated from the output signal s of the angular velocity sensor 14 without considering the focal length f.
(F) shows a gain determined by the focal length f. For example, G (f) is a value obtained by multiplying f by a constant (positive real number).

In such a case, it is appropriate that the threshold value x _S1 (and -x _S1 ) is also changed according to the focal length. For example, an appropriate threshold value x _{S1 at} a certain focal length f ₀ Is x _S10 , the threshold value x at the focal length f
_S1 is changed by the following equation using the gain G (f).

X _S1 = (G (f) / G (f ₀ )) · x _S10 Also, in the case of the above-described photographing optical system, the anti-vibration lens 10
It is appropriate to change the maximum displacement of the lens according to the focal length. For example, the maximum displacement at the longest focal length f _T (tele end) in the range of the changeable focal length is u ₀ (and −
u ₀ ), the maximum displacement u at the focal length f is changed by the following equation.

[0024] u = (G (f) / G (f 0)) · u 0 if the maximum displacement amount u ₀ is in the range of mechanical limitations end in the telephoto end, the maximum displacement amount u obtained by the above equation (If the shake signal x exceeds the maximum displacement amount u, the vibration-proof lens 10 is not displaced beyond the maximum displacement amount u). When the maximum displacement of the image stabilizing lens 10 is also changed in accordance with the focal length, the threshold value x _S1 is set to a value of the maximum displacement of the image stabilizing lens 10 or a value near the focal distance at a certain focal length. In such a case, the value is set to a value near the maximum displacement amount of the image stabilizing lens 10 regardless of the focal length. Experience has shown that the preferred maximum displacement value and the preferred threshold value x _S1 are approximately the same (although this is not necessarily the case).
mm, the anti-vibration lens 1
A preferable maximum displacement amount of 0 is such that the image is shifted by one-fifth on the photographing screen, and the preferable threshold value _xS1 is a value of this maximum displacement amount or a value in the vicinity thereof. At this time, the maximum displacement amount or the threshold value x _S1 of the anti-vibration lens 10 is a reference value for determining whether or not the angle of view is changed, and the maximum value of the anti-vibration lens 10 for securing a preferable anti-vibration operation. It can also be used as a value that limits the range in which displacement is possible, and it is possible to set only one of the values and use it for both purposes.

FIG. 5 is a flowchart showing a procedure for judging whether or not the angle of view has been changed and for turning on / off the angle of view correction based on the judgment result. First, the CPU 16 detects a shake signal x indicating a displacement amount of the image stabilizing lens 10 from the shake center based on a signal from the angular velocity sensor 14 (Step S10). Then, it is determined whether the vibration signal x exceeds a predetermined threshold value x _S1 (or -x _S1) (Step S12). That is, it is determined whether x> x _S1 or x <−x _S1 . At this time, if NO is determined, it is determined that it is not at the time of changing the angle of view, and the process of turning on the image blur correction is executed as usual (step S14). That is, in order to execute image shake correction, the shake signal detected in step S10 is output to the D / A converter 20 as a position command signal, and the image stabilizing lens 10 is moved to a position where image shake is prevented. Then, the process from step S10 is repeated.

On the other hand, if YES is determined in step S12, then the shake signal x is set to the threshold value x
_S1 (or -x _S1) to continue beyond that time (over time) performs the measurement process (step S16). Then, it is determined whether or not the measured over time has exceeded a predetermined determination time t _S1 (step S18). here,
If the determination is NO, the processing from step S10 is repeated. On the other hand, when the determination is YES, it is determined that the angle of view is to be changed, and the process of turning off the image blur correction is executed (step S20). That is, regardless of the shake signal detected in step S10, the shake center (zero value) of the anti-vibration lens 10
Is output to the D / A converter 20 to move the image stabilizing lens 10 to the center of the shake and stop at the center of the shake. Once the processing of step S20 is performed,
Thereafter, a process for starting image blur correction shown in FIG. 7 is executed.

Next, it is determined that the angle of view has been changed as described above.
Automatically start image stabilization after turning off image stabilization
Will be described. The CPU 16
After the image blur correction is turned off in step S20, the image
Whether or not to start the shake correction is determined by the shake signal x as described above.
Is determined based on Therefore, first, as shown in FIG.
The shake signal when changing the angle of view definitely exceeds that value
Such a threshold x_S2, -X_S2(X_S2Is set to positive).
Then, the shake signal x continues to have the threshold value x _S2, -X
_S2Within, ie, x_S2≧ x ≧ −x_S2Total time
Measure. As a result, the waveform S in FIG._FiveAt the time of measurement like
Judgment sufficient to judge that the angle of view change operation has stopped
Time t_S2Is exceeded, image stabilization is turned on and image stabilization is
Start positive.

FIG. 7 shows a CPU 1 for starting image blur correction.
6 is a flowchart illustrating a processing procedure in the sixth embodiment. Ma
CPU 16 based on the signal from angular velocity sensor 14
Indicating the amount of displacement of the image stabilizing lens 10 from the center of shake.
The signal x is detected (Step S30). And that swing
Signal x has a predetermined threshold value x_S2(Or -x_S2)
Is determined (step S32). That is, x_S2≧ x ≧ −
x_S2It is determined whether or not. At this time, if it is determined to be NO
Repeatedly executes the processing from step S30.
You. On the other hand, if the determination is YES, the shake signal x is
Then the threshold x _S2(Or -x_S2)
The interim measurement process is performed (step S34). And that
Measurement time is a predetermined judgment time t_S2Judge whether or not
(Step S36). Here, when it is determined as NO
, The process from step S30 is repeated. one
On the other hand, if the determination is YES, the angle-of-view changing operation is stopped.
The image blur correction ON process (step
S38).

As described above, in the above embodiment, the image blur correction is automatically turned off when the angle of view is changed. Regardless of whether or not the mode is set, the user may always be able to select the mode in which the image blur correction is turned on by a predetermined switch.

In the above embodiment, the image blur correction is turned off when the angle of view is changed. However, the present invention is not limited to this.
When the angle of view is changed, the image blur correction may be performed by reducing the correction ability with respect to the normal image blur correction when the image blur correction is on. As a method of reducing the correction capability, for example,
The shake signal detected as described above from the angular velocity sensor 14 is reduced at a fixed rate, and the vibration-proof lens 10 is displaced by the reduced shake signal.
May be displaced with a smaller displacement amount than the position where image blur is prevented.

In the above-described embodiment, the case where the image blur is prevented by the anti-vibration lens displaced in the plane perpendicular to the optical axis of the photographing optical system has been described. The present invention can be applied to all image stabilization apparatuses that drive the correction optical system based on the instructed correction amount (the displacement amount of the image stabilizing lens 10 in the above embodiment) to prevent image blur. Further, the present invention can be applied to an image stabilizing apparatus using an electronic method that shifts a range from which a video signal is cut out from an image sensor to prevent image blur.

[0032]

As described above, according to the image stabilizing apparatus according to the present invention, the predetermined threshold value for which the correction amount for correcting the image blur is continuously longer than the predetermined time and different from the zero value is set. If the angle of view is exceeded, it is determined that the angle of view is to be changed, and the process is automatically switched to processing such as stopping image blur correction. Therefore, it is possible to accurately determine whether the angle of view has been changed and when the angle of view is constant. At the same time, when the angle of view is changed, the process is automatically switched to an appropriate process without any trouble. After the image blur correction is stopped, for example, when the angle of view is changed, if the correction amount falls within a predetermined threshold value for a longer time than a predetermined time, the normal image blur correction is performed. Is automatically started, so that the normal image blur correction can be appropriately started without any trouble after the view angle changing operation is stopped.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a vibration isolator according to the present invention.

FIG. 2 is an explanatory diagram used for explaining a method of determining whether or not the angle of view is changed;

FIG. 3 is an explanatory diagram used for explaining a method of determining whether or not the angle of view is changed;

FIG. 4 is an explanatory diagram used for explaining a method of determining whether or not the angle of view is changed;

FIG. 5 is a flowchart illustrating a process of determining whether or not the angle of view is changed and a process of turning on / off the angle of view based on the determination result;

FIG. 6 is an explanatory diagram used for explaining a method of determining whether to start angle-of-view correction.

FIG. 7 is a flowchart illustrating a processing procedure in the CPU for starting image blur correction;

[Explanation of symbols]

10 anti-vibration lens, 12 motor, 14 angular velocity sensor, 16 CPU, 22 motor drive circuit

Claims (2)

[Claims] 1. A vibration detecting means for detecting a vibration applied to a photographing optical system, a correction amount output means for outputting a correction amount for correcting an image blur based on the vibration detected by the vibration detecting means, An image blur correction unit that performs image blur correction based on the correction amount output by the correction amount output unit, wherein the correction amount output from the correction amount output unit is longer than a predetermined time. When a predetermined threshold value different from the zero value is continuously exceeded for a long time, the image blur correction by the image blur correction unit is stopped, or the normal image based on the correction amount is determined by the image blur correction unit. What is claimed is: 1. An image stabilizing apparatus, comprising: a control unit configured to execute image blur correction in which the correction capability is reduced as compared with the blur correction. 2. The image processing apparatus according to claim 1, wherein the control unit stops the image blur correction by the image blur correction unit or reduces the correction capability of the image blur correction unit compared to a normal image blur correction based on the correction amount. After performing the image blur correction, if the correction amount output from the correction amount output means is continuously within a predetermined threshold for a longer time than a predetermined time, the image blur correction means 2. A normal image blur correction based on the correction amount is started.
Anti-vibration device.