JP2000187259A - Shake prevention controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a controller small in size and light in weight, and also to enhance offset signal removing accuracy. SOLUTION: This controller is provided with offset attenuating means 116a, 116b, 116f and 116g for attenuating offset signals superposed on a 1st signal from a shake detecting means 19 for detecting the shake, a remaining offset amount fixing means 116j for fixing the offset amount remaining in the 2nd signal to a prescribed remaining offset amount, and a remaining offset removing means 11 for removing the remaining offset amount, based on the 1st signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an anti-vibration control device for performing processing such as removal of an offset signal superimposed on a signal from a vibration detecting means.

[0002]

2. Description of the Related Art In a current camera, all operations important for photographing, such as exposure determination and focusing, are automated. Therefore, even a person unskilled in camera operation is very unlikely to fail in photographing.

[0003] Recently, a system for preventing camera shake added to a camera has been studied, and a factor which causes a photographer to make a photographing error has almost disappeared.

Here, a system for preventing camera shake will be briefly described.

The camera shake at the time of photographing is generally a vibration of 1 Hz to 10 Hz as a frequency. At the time of the release of the shutter, even if such camera shake occurs, it is possible to take a picture without image shake. As an idea, it is necessary to detect the camera shake caused by the camera shake and to displace the correction lens according to the detected value.
Therefore, in order to take a photograph in which image shake does not occur even when camera shake occurs, first, it is necessary to accurately detect the camera vibration and, secondly, to correct the optical axis change due to camera shake. Become.

In principle, this vibration (camera shake) is detected by a shake detection sensor that detects acceleration, angular acceleration, angular velocity, angular displacement, and the like, and an output of the shake detection sensor is appropriately processed for camera shake correction. This can be performed by mounting a vibration detection device having a calculation unit on a camera. Then, based on this detection information, the image blur suppression is performed by driving the correcting means for decentering the photographing optical axis.

FIG. 9 is a perspective view showing the appearance of a compact camera having an anti-vibration system.
The camera has a function of performing shake correction for camera vertical shake and horizontal shake indicated by p and 42y.

In the camera body 43, 43a is a release button, 43b is a mode dial (including a main switch), 43c is a retractable strobe, and 43d is a finder window.

FIG. 10 is a perspective view showing the internal configuration of the camera shown in FIG. 9, in which 44 is a camera body, 51 is a correction means, 52 is a correction lens, and 53 is a correction lens 52 in FIG.
Driving freely in the directions of 8p and 58y, the arrow 42p in FIG.
This is a support frame for performing shake correction in the 42y direction, and details thereof will be described later. 45p and 45y are arrows 46p and 46, respectively.
It is a vibration detecting device such as an angular velocity meter or an angular accelerometer that detects a vibration around y.

The outputs of the vibration detecting devices 45p and 45y are converted into drive target values of the correcting means 51 via arithmetic units 47p and 47y, which will be described later, and input to the coils of the correcting means 51 to perform shake correction. Incidentally, 54 is a ground plane, 56p and 56y are permanent magnets, and 510p and 510y are coils.

FIG. 11 is a block diagram showing details of the arithmetic units 47p and 47y. Since these units have the same configuration, only the arithmetic unit 47p will be described in FIG.

The arithmetic unit 47p includes a DC cut filter 48p and a low-pass filter 49 surrounded by a dashed line.
p, an analog / digital conversion circuit (hereinafter, referred to as an A / D conversion circuit) 410p, a driving device 419p, and a camera microcomputer 411 indicated by a broken line. The camera microcomputer 411 includes a storage circuit 412p, a differential circuit 4
13p, DC cut filter 414p, integration circuit 415
p, a storage circuit 416p, a differential circuit 417p, and a PWM duty change circuit 418p.

Here, a vibration gyro for detecting a shake angular velocity of the camera is used as the vibration detection device 45p. The vibration gyro is driven in synchronization with turning on of a main switch of the camera, and detects a shake angular velocity applied to the camera. To start.

In the output signal of the vibration detecting device 45p, a DC bias component superimposed on the output signal is cut by a DC cut filter 48p composed of an analog circuit. The DC cut filter 48p has a frequency characteristic of cutting a signal having a frequency of 0.1 Hz or less, and does not affect a camera shake frequency band of 1 to 10 Hz applied to the camera. However, like this
If the characteristic is set so as to cut the frequency below 0.1 Hz, there is a problem that it takes about 10 seconds from the input of the shake signal from the vibration detection device 45p until the DC is completely cut. Therefore, the time constant of the DC cut filter 48p is set to be small (for example, a characteristic of cutting a signal having a frequency of 10 Hz or less) until, for example, 0.1 second after the main switch of the camera is turned on. Cut DC in a short time, then increase the time constant (
DC with the characteristic to cut only the frequency below 0.1Hz) DC
The cut filter 48p prevents the shake angular velocity signal from deteriorating.

The output signal of the DC cut filter 48p is
The signal is appropriately amplified by the low-pass filter 49p formed of an analog circuit in accordance with the resolution of the A / D conversion circuit 410p, and high-frequency noise superimposed on the shake angular velocity signal is cut. This is to prevent the reading of the sampling of the A / D conversion circuit 410p when the shake angular velocity signal is input to the camera microcomputer 411 from occurring due to the noise of the shake angular velocity signal. The output signal of the low-pass filter 49p is sampled by the A / D conversion circuit 410p and taken into the camera microcomputer 411.

Although the DC bias component is cut by the DC cut filter 48p, the DC bias component is again superimposed on the shake angular velocity signal by the amplification of the low-pass filter 49p. It is necessary to perform DC cut again.

Therefore, for example, the shake angular velocity signal sampled 0.2 seconds after the main switch of the camera is turned on is stored in the storage circuit 412p, and the difference between the stored value and the shake angular velocity signal is obtained by the differential circuit 413p to cut the DC. Do. In this operation, only a rough DC cut can be performed. (Since the shake angular velocity signal stored 0.2 seconds after the main switch of the camera is turned on includes not only a DC component but also an actual camera shake, ), DC cut filter 414 constituted by a digital filter in the subsequent stage
A sufficient DC cut is performed at p. The time constant of the DC cut filter 414p can be changed similarly to the analog DC cut filter 48p, and the time constant is gradually increased by spending another 0.2 second 0.2 seconds after the main switch of the camera is turned on. . More specifically, the DC cut filter 414p has a filter characteristic of cutting a frequency of 10 Hz or less when 0.2 seconds have elapsed since the main switch was turned on. Thereafter, the frequency cut by the filter every 50 msec is changed to 5 Hz, 1 Hz, or 5 Hz. 0.5H
z, 0.2Hz.

However, when the photographer presses the release button 43a halfway (turns on sw1) and performs photometry and distance measurement during the above-described operation, there is a possibility that photography is immediately performed, and time is consumed by the time constant. It may not be desirable to make changes. Therefore, in such a case, the change of the time constant is stopped halfway according to the photographing conditions. For example, it has been found from the photometry result that the shooting shutter speed is 1/60, and the shooting focal length is 15/60.
At 0 mm, the vibration isolation accuracy is not so required.
The C cut filter 414p is completed when the time constant is changed to the characteristic of cutting the frequency of 0.5 Hz or less (the time constant change amount is controlled by the product of the shutter speed and the photographing focal length). As a result, the time for changing the time constant can be reduced, and the photo opportunity can be prioritized. Of course, when the shutter speed is higher or the focal length is shorter, the characteristic of the DC cut filter 414p is completed when the time constant is changed to the characteristic that cuts the frequency of 1 Hz or less. At the time, shooting is prohibited until the time constant is completely changed.

The integration circuit 415p starts integrating the output signal of the DC cut filter 414p in response to the half-press of the release button 43a of the camera (sw1 is turned on), and converts the angular velocity signal into an angle signal. However, as described above, when the time constant change of the DC cut filter 414p is not completed, the integration operation is not performed until the time constant change is completed. still,
Although omitted in FIG. 11, the integrated angle signal is appropriately amplified based on the focal length and subject distance information at that time, and converted so as to drive an appropriate amount correction unit 51 according to the shake angle (zoom focus). Changes the photographing optical system, and the amount of eccentricity of the optical axis changes with respect to the driving amount of the correcting means 51, so that this correction needs to be performed.

Push release of the release button 43a (sw2
(ON), the correction means 51 starts to be driven in accordance with the shake angle signal. At this time, however, it is necessary to take care that the shake correction operation of the correction means 51 does not suddenly start. The storage circuit 416p and the differential circuit 417p are provided for this measure. The storage circuit 416p stores the release button 4
Integrator circuit 4 in synchronization with pushing off of 3a (on of sw2)
The 15p shake angle signal is stored. Differential circuit 417p
Calculates the difference between the signal of the integration circuit 415p and the signal of the storage circuit 416p. Therefore, when the switch sw2 is on, the two signal inputs of the differential circuit 417p are equal,
Although the drive target value signal to the 17p correction means 51 is zero, the output is continuously performed from zero thereafter (the storage circuit 416p plays the role of using the integrated signal at the time of turning on the switch sw2 as the origin). As a result, the correcting means 51 is not driven suddenly.

The target value signal from the differential circuit 417p is P
It is input to the WM duty change circuit 418p. When a voltage or current corresponding to the deflection angle is applied to the coil 510p (see FIG. 10) of the correction unit 51, the correction lens 52
Is driven in accordance with the deflection angle. However, PWM driving is desirable in order to reduce the driving power consumption of the correction unit 51 and the power consumption of the coil driving transistor.

Therefore, the PWM duty changing circuit 418
p changes the coil drive duty according to the target value. For example, in a PWM having a frequency of 20 KHz,
When the target value of the differential circuit 417p is "2048", the duty is set to "0", when the target value is "4096", the duty is set to "100", and the interval is equally divided to determine the duty according to the target value. The duty is determined not only by the target value but also by the camera's photographing conditions (temperature, camera attitude, power supply state) at that time, so that accurate shake correction is performed.

The output of the PWM duty change circuit 418p is input to a known driving device 419p such as a PWM driver, and the output of the driving device 419p is applied to a coil 510p (see FIG. 10) of the correction means 51 to perform shake correction. Do.
The driving device 419p is turned on in synchronization with the turning on of the switch sw2, and turned off when exposure to the film is completed.
Also, even after the exposure is completed, the integration circuit 415p continues integration as long as the release button 43a is half-pressed (sw1 is turned on), and the storage circuit 416p again outputs a new integrated output when the next switch sw2 is turned on. Is stored.

When the release button 43a is half-pressed, the integration circuit 415p stops integrating the output of the DC cut filter 414p, and resets the integration circuit 415p. Resetting is to empty all information that has been integrated up to now.

When the main switch is turned off, the vibration detecting device 45
p is turned off, and the image stabilization sequence ends.

When the output signal of the integration circuit 415p becomes larger than a predetermined value, it is determined that the camera has been panned, and the time constant of the DC cut filter 414p is changed. For example, the characteristic that cuts the frequency of 0.2 Hz or less is changed to the characteristic that cuts the frequency of 1 Hz or less,
The time constant is restored again in a predetermined time. The time constant change amount is also controlled by the magnitude of the output of the integration circuit 415p. That is, when the output signal exceeds the first threshold, D
The characteristic of the C-cut filter 414p is set to a characteristic that cuts 0.5 Hz or less. When the characteristic exceeds the second threshold, the characteristic is cut to 1 Hz or less. When the characteristic exceeds the third threshold, 5H is set.
A characteristic that cuts z or less is set.

When the output of the integrating circuit 415p becomes very large, the integrating circuit 415p is reset once to prevent the saturation (overflow) in the operation.

In FIG. 11, the DC cut filter 41
4p is configured to start the operation 0.2 seconds after the main switch is turned on. However, the present invention is not limited to this, and the operation may be started by half-pressing the release button 43a. In this case, the integration circuit 415p is activated from the time when the change of the time constant of the DC cut filter is completed.

The integration circuit 415p is also operated by the release button 4
Although the operation is started by half-pressing the switch 3a (sw1), the operation may be started by pressing the release button 43a off (sw2). In this case, the storage circuit 41
6p and the differential circuit 417p become unnecessary.

In FIG. 11, the DC cut filter 48p and the low-pass filter 49p are provided in the arithmetic unit 47p. However, it is needless to say that these may be provided in the vibration detecting unit 45p.

12 to 14 are views showing the details of the correction means 51. More specifically, FIG. 12 is a front view of the correction means 51, and FIG. 13 (a) is a side view seen from the direction of arrow B in FIG. FIG. 13B is a cross-sectional view taken along the line AA of FIG. 12, and FIG.

In FIG. 12, the correction lens 52 (FIG. 13)
As shown in (b), this correction lens 52 is
Lens 52a, 52b fixed to the
, Which constitutes a group of photographing optical systems), is fixed to a support frame 53.

A yoke 55 made of a ferromagnetic material is attached to the support frame 53, and permanent magnets 56p and 56y of neodymium or the like are attracted and fixed (shown by hidden lines) to the back surface of the yoke 55 in FIG. Also, three pins 53a extending radially from the support frame 53 are fitted into long holes 54a provided in the side walls 54b of the base plate 54.

As shown in FIG. 13A and FIG.
3a and the long hole 54a are fitted in the direction of the optical axis 57 of the correction lens 52 so that there is no play, but since the long hole 54a extends in the direction orthogonal to the optical axis 57, the support frame 53 is 5
4 is restricted in the direction of the optical axis 57, but can move freely in a plane perpendicular to the optical axis (arrows 58p, 58p).
y, 58r). However, as shown in FIG. 12, the tension springs 59 are hung between the hooks 53b on the support frame 53 and the hooks 54c on the main plate, so that each direction (58p, 58
y, 58r).

The coils 510p and 510y are attached to the base plate 54 so as to face the permanent magnets 56p and 56y (partly hidden lines). The arrangement of the yoke 55, the permanent magnet 56p, and the coil 510p is as shown in FIG. 13B (the permanent magnet 56y and the coil 510y have the same arrangement).
When a current is passed through 10p, the support frame 53 is driven in the direction of the arrow 58p.
3 is driven in the direction of arrow 58y.

The driving amount is determined by the spring constant of the tension spring 59 in each direction and the coils 510p and 510.
y and the thrust generated in relation to the permanent magnets 56p and 56y. That is, the amount of eccentricity of the correction lens 52 can be controlled based on the amount of current flowing through the coils 510p and 510y.

[0037]

As described with reference to FIG. 11, the DC bias component superimposed on the signal of the vibration detecting device 45p (45y) is cut by the DC cut filter 48p composed of an analog circuit. You. This D
The configuration of the C-cut filter 48p is as shown in FIG.
Operational amplifier 420p, capacitor 421p, resistor 422
p, 423p and a switch 424p (the same applies to the DC cut filter of the vibration detection device 45y). Then, the characteristics of this DC cut filter 48p are
In order to set a characteristic of cutting a frequency of 0.1 Hz or less, for example, a capacitor 421p is set to 10 μF and a resistor 422
Let p be 160 kΩ.

The resistance value of the resistor 423p is set to, for example, 1.6 k.
When the switch 424p is closed, the DC cut filter 48p cuts the frequency of 10 Hz or less, and when the switch 424p is opened, the cutoff frequency is 0.1 Hz or less. By closing the switch 424p until, for example, 0.1 second elapses after the main switch is turned on, it is possible to cut the DC component early.

By the way, in the circuit configuration of FIG. 15, since a large-capacity capacitor of 10 μF is used for the capacitor 421p, the circuit becomes considerably large.
In addition, there was a problem that the cost was high. Further in this way DC
When the cut filter 48p is formed, there is a problem that the accuracy of the image stabilization is reduced. This will be described with reference to FIGS.

FIG. 16 shows the DC cut filter 48 of FIG.
5 conceptually shows a frequency characteristic of p, and a line segment 425 is
The ratio (gain) of the output signal to the signal input to the DC cut filter 48p is shown, and the line segment 426 similarly shows the phase of the signal output to the input signal.

Looking at the line segment 425, it can be seen that the gain decreases at frequencies lower than 0.1 Hz, but the output of signals below this frequency is attenuated, and DC cut characteristics can be obtained. .

In order to perform image stabilization with high accuracy, it is necessary to input the signal of the vibration detecting device to the correcting means with as little phase shift as possible.
At 10 Hz to 10 Hz, the phase is advanced particularly on the low frequency side, and accurate vibration isolation cannot be performed.

In order to improve the anti-vibration accuracy, for example, the current DC cut filter that cuts a frequency of 0.1 Hz or less may be changed to a characteristic that cuts 0.01 Hz. However, in this case, the capacitance of the capacitor 421p is increased to, for example, 100 μF (or the resistance 422p is
1.6 MΩ), which is not preferable in terms of circuit scale and noise.

As described above, the current DC cut filter has a large capacitor and is not suitable for miniaturization and cost reduction.
Further, there is a problem that the vibration control accuracy is reduced.

(Purpose of the Invention) A first object of the present invention is to provide an image stabilization control device which can be reduced in size and weight and can further enhance the accuracy of offset signal removal.

A second object of the present invention is to provide an anti-vibration control device which can be reduced in size and weight, and can increase the speed of offset signal removal while maintaining the accuracy of offset signal removal. is there.

A third object of the present invention is to provide an anti-vibration control device which is miniaturized by adopting a circuit configuration in which the output signal of the vibration detecting means is not saturated so that the means for removing the offset is unnecessary. Is what you do.

[0048]

According to the first aspect of the present invention, an offset signal superimposed on a first signal from a vibration detecting means for detecting a vibration is attenuated. Offset attenuating means for outputting a second signal, remaining offset amount fixing means for fixing an offset amount remaining in the second signal to a residual offset amount of a predetermined value, and the remaining offset amount based on the first signal. This is an anti-vibration control device having a residual offset removing means for removing an offset amount.

In the above arrangement, attention is paid to the fact that the remaining offset amount can be predicted, the remaining offset amount is obtained, and the remaining offset amount is removed based on the first signal from the vibration detecting means. .

In order to achieve the second object,
According to a second aspect of the present invention, there is provided a vibration detecting means for detecting a vibration, an offset removing means for removing an offset signal superimposed on a first signal from the vibration detecting means, and an offset removing means for the offset removing means. An anti-vibration control device having an offset removal amount changing means for changing the amount.

In the above configuration, paying attention to the fact that the offset signal removal speed can be made variable, the offset removal amount changing means changes the offset removal amount based on the elapsed time from the start of the image stabilization control device, or sets the offset removal amount. Until the predetermined time elapses for the first time after the start of the vibration control device, the offset removal amount is increased, the offset removal amount is changed based on the first signal, or when the first signal is larger than a predetermined value. And the amount of offset removal is increased.

In order to achieve the first object,
According to a seventh aspect of the present invention, there is provided a comparator having a predetermined dead band for comparing a first signal from the vibration detecting means or a value obtained by amplifying the first signal with a reference value, and the signal of the comparator is A clock gate to be input, a D / A converter, an up / down counter for increasing and decreasing an output signal of the D / A converter based on a signal from the clock gate, a signal from the D / A converter, And a differential device for subtracting the first signal.

In order to achieve the second object,
The present invention according to claim 8, wherein a comparator for comparing the first signal from the vibration detecting means or a value obtained by amplifying the first signal with a reference value, and a clock gate to which the signal of the comparator is input An output signal of the D / A converter based on a signal from the D / A converter and the clock gate;
Up / down counter for downing, D / A control means for changing the rate of change of the D / A converter by the up / down counter, and differential device for subtracting the signal from the D / A converter and the first signal And an anti-vibration control device having:

In order to achieve the third object,
According to a ninth aspect of the present invention, there is provided a signal amplifying means for amplifying a first signal from a vibration detecting means for detecting a vibration at a plurality of amplification factors, based on the first signal or a signal from the signal amplifying means. And a gain changing means for changing the gain of the signal amplifying means.

[0055]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing a circuit configuration of a camera which is a premise of the first embodiment of the present invention. Only a portion relating to the present embodiment is shown, and other elements of the camera will be described. Omitted for simplicity.

In FIG. 1, the camera microcomputer 11 (FIG. 1)
When the ON signal of the main switch 114 is input, the microcomputer 411 extends the photographing lens barrel from the retracted state to the state of the photographable optical system, and simultaneously opens the lens barrier. At this time, the vibration detecting mechanism 19a
Detecting device 19 comprising a vibration detecting circuit portion 19b
Also start.

The photographing mode selected by the photographer is input to the camera microcomputer 11 from the photographing mode input member 112. The shooting modes include, for example, a sports mode suitable for shooting a moving subject, a portrait mode suitable for shooting a person up, a macro mode suitable for shooting a subject close-up, and a night view. It has a night view mode suitable for

The flash mode is input to the camera microcomputer 11 from the flash mode input member 111. There are two strobe modes: a strobe off mode that does not use a strobe, a strobe on mode in which the strobe is forcibly fired, and a strobe auto mode that controls whether or not the strobe is fired depending on the brightness of the subject and the direction of the light beam.
Further, it is possible to determine whether to activate the red-eye reduction function at the time of flash emission.

Information on whether or not to perform shake correction at the time of photographing determined by the photographer is input from the image stabilizing switch 18 to the camera microcomputer 11. A zoom signal in response to a photographer's operation is transmitted from the zoom operation member 15 to the camera microcomputer 1.
1, the camera microcomputer 11 controls the zoom driving device 16 to change the photographing focal length.

When the photographing focal length is determined, the release member 11 which is a release button by the photographer is used.
3 is half-pressed (sw1 is turned on). At the timing of this half-press, the distance measuring device 13 measures the distance to the subject and outputs the information (distance measurement information) to the camera microcomputer 11, and outputs the information to the camera microcomputer 11. The microcomputer 11 controls the AF driving device 115 based on the distance measurement information to drive a part or all of the photographing lens barrel to adjust the focus of the photographing optical system.

At this time, the shake information from the vibration detecting device 19 is also input to the camera microcomputer 11 via the A / D converter 117, and the camera microcomputer 11 determines whether the camera is in a hand-held state or on a tripod or the ground based on the shake state. Determine if it is fixed.

The subject brightness is input from the photometric device 12 to the camera microcomputer 11. The camera microcomputer 11 has the information and film sensitivity and type, the use state of the anti-vibration system, the shooting focal length and the brightness of the lens at that time, the shooting mode, the selection of shake correction, the distance information to the subject, the shake information, etc. The exposure time is calculated based on the photographing information determined in (1), and at the same time, it is determined whether or not the flash device 17 is used.

When the release member 113 is pushed off (sw2 is turned on), the camera microcomputer 11 controls the correcting means 110 based on a signal from the vibration detecting device 19 to start shake correction. After that, the film exposure is performed by controlling the shutter driving device 14, and the flash device 17
To emit light.

Reference numeral 116 denotes an analog signal processing circuit comprising the DC cut filter 48p and the low-pass filter 49 described with reference to FIG. Output to converter 117. The A / D converter 117 samples the signal of the analog signal processing circuit 116 and sends it to the camera microcomputer 11.

Here, the method of cutting the offset signal of the vibration detecting device 19 in the analog signal processing circuit 116 does not use the filter having the frequency characteristic as described with reference to FIG. ing.

The signal detected by the vibration detecting device 19 is input to an analog signal processing circuit 116, and the signal
At 6a, the signal is subtracted from an offset extraction component to be described later, and then the noise superimposed on the signal component is cut by an amplifier / low-pass filter 116b, similarly to the low-pass filter 49p of FIG. 11, and the signal is amplified. The output signal from the amplifier / low-pass filter 116b is supplied to the A / D converter 1
17 and simultaneously to the comparator 116c. The comparator 116c includes the amplifier / low-pass filter 11
6b and the reference signal 116d are compared. The reference signal 116d is substantially half of the power supply voltage input to the vibration detection circuit section 19b, and is the center value of the signal output range of the vibration detection device 19. The reference signal is also used as a reference when DC removal and integration are performed by a digital filter in the camera microcomputer 11 thereafter.

When the signal of the amplifier / low-pass filter 116b is larger than the reference signal (when there is a positive offset voltage), the comparator 116c outputs the "H" signal.
When the signal is smaller than the reference signal 11 d (when there is a negative offset voltage), the signal of “L” is output to the clock gate 11.
6e. The clock gate 116e outputs the signal from the comparator 116c to the up / down counter 116 when the clock signal is input from the reset terminal 116h.
Send to f.

The up / down counter 116f increases the count by one bit every clock when the signal from the clock gate 116e is "H", and lowers the count by one bit when the signal is "L". D / A converter 1
16g outputs an analog signal corresponding to the output of the up / down counter 116f, and outputs, for example, plus 2 mV to the differential unit 116a when the 1-bit count increases.

The camera microcomputer 11 starts the operation of the analog signal processing circuit 116 (the analog signal processing circuit 1).
0.1 after 0.1 second
The second clock signal is output to the clock gate 116c.

In the above configuration, when the main switch 114 of the camera is first turned on, the vibration detecting device 19 and the analog signal processing circuit 116 start operating.

Now, assuming that there is little vibration such as camera shake for the sake of explanation, at this time, the output of the vibration detecting device 19 changes from the start of the operation to the waveform 118 in FIG. to the offset V _1. Signal greatly fluctuates between immediately after the start of operation until T ₀ hours here. This is a signal fluctuation until the vibration is stabilized when, for example, a known vibration gyro is used as the vibration detection device 19, and is a signal fluctuation until the circuit is stabilized when an angular acceleration clock is used. .

The camera microcomputer 11 operates at T ₁ from the start of operation.
(E.g., 0.1 seconds) to output a clock signal until lapse T ₂ hours time clock gate 116c. Where T ₁
The clock signal is supplied to the clock gate 116
The reason why the signal is not output to c is that the offset component superimposed on the signal of the vibration detecting device 19 has fluctuated as described above.

[0074] The comparator 1 to the output of the differentiator 116a will initially that generates a signal offset V ₁ at time T ₁
16c outputs an "H" signal, and the clock gate 116c
Each time one clock is input, the signal of the D / A converter 116g input to the differential unit 116a increases. Therefore, the offset component of the signal of the differential unit 116a decreases as the clock increases (waveform 119), and finally the D / A
Within the range of the minimum resolution (for example, 2 mV) of the converter 116g, the signal of the differential unit 116a alternately fluctuates in accordance with the clock (arrow 120).

At time T ₂ , the camera microcomputer 11 stops the output of the clock signal.
The signal output from 6g to the differential 116a is fixed to the signal at the time when the clock signal stops outputting. Thus, no longer change of the signal at the arrow 120 shown in FIG. 2 (a), the offset component is reduced to V _2.

Here, in the conventional DC cut filter 48p described with reference to FIG. 11, the offset component can be finally reduced to zero, while the offset is slightly (V ₂ ) remaining in the present system. There is a disadvantage.

Here, the reason why the analog signal processing circuit 116 must also remove the offset in order to remove the offset in the camera microcomputer 11 in the subsequent processing will be described below.

Now, consider a case where the analog signal processing circuit 116 does not remove offset. Vibration detector 19
Is amplified by a considerable high gain before it is A / D converted and taken into the camera microcomputer 11. This is because the output of the camera shake component detected by the vibration detection device 19 is extremely small. Therefore, the signal of the amplifier may be saturated by an offset component superimposed on the signal. Therefore, in order to prevent this saturation, it is necessary to reduce the signal offset of the vibration detecting device 19 to some extent before amplification.

In the configuration of FIG. 1, the offset component V ₁ is reduced to V ₂ as shown in FIG. 2A, thereby preventing the signal of the amplifier / low-pass filter 116b from being saturated. Can be done.

In the removal of the offset component by the method described above, the circuit can be considerably reduced in size because a large-capacity capacitor is not required unlike a conventional DC cut filter, and the circuit is composed of a capacitor and a resistor. Since there is no time setting circuit, there is an advantage that there is no fear of deterioration in image stabilization accuracy due to a phase shift in a camera shake frequency band. However, as described above, unlike the conventional offset removal, a slight offset V ₂ (2 mV) cannot be removed. Since this offset amount is known to be 2 mV, it seems to be removed in the subsequent processing, but in practice, as described above, T
_{In the} vicinity of ₂ hours, the waveform 119 alternately oscillates between 2 mV and −2 mV, and the offset amount at the time T ₂ changes to 2 mV or −2 mV due to a slight change in the original offset amount of the vibration detecting device 19. Therefore, it is difficult to predict the offset amount.

Therefore, in the present embodiment, the remaining offset amount can be predicted by further changing the configuration as shown in FIG.

FIG. 3 is different from FIG.
A differential 116h and a window comparator 116i are provided in place of 6c, and both constitute a comparator 116j having a dead zone. The dead zone of the window comparator 116j is set to, for example, 2 to 4 mV. When the output of the differential 116h is out of the range of the dead zone, the window comparator 116j is set to “H” according to the polarity of the differential 116h. The "L" signal is supplied to the clock gate 11
6e, when the offset of the signal of the differential unit 116a is gradually removed and the difference from the reference signal 116d is reduced (for example, when the difference becomes 3 mV or less), the window comparator 116j stops outputting the signal. The removal operation ends.

As described above, since the dead zone is provided in the comparator, the offset beyond the dead zone is not removed.
The alternating change of the offset as shown by the arrow 120 in (a) does not occur.

The D / A converter 116g changes the D / A conversion rate according to a signal from the camera microcomputer 11. For example, when a signal is not input from the camera microcomputer 11, if the count of the up / down counter is increased by one bit, a plus 2 mV is output, and if the count of the up / down counter is decreased by one bit, a minus 2 mV is output. At times, when the count of the up / down counter is increased by one bit, the output is increased by 10 mV, and when the count is decreased by one bit, the output is decreased by 10 mV. Then, the camera microcomputer 11 a predetermined time from time T ₁ (e.g., 50 msec) D / A converter 1
16g to output a signal to the up / down counter 116f
The output of the A / D converter 116g per bit is increased.

FIG. 2B shows the waveform of the offset removing operation in the circuit block of FIG. 3. The offset removing waveform 121 becomes like the signal 118 having the same offset as in FIG. 2A.

When comparing the waveforms 121 and 119, T ₁
It can be seen that the offset removal speed from time has changed. This is the D / A converter 116f per bit.
Are different from each other. In the circuit block of FIG. 3 which outputs 10 mV per bit, the offset can be removed early. However, since this remains in becomes rough removal accuracy of the offset, the camera microcomputer 11 after the lapse of the predetermined time T ₁ times the D / A converter 116
The signal output to f is stopped to reduce the output per bit. Thus, accurate offset removal can be performed after a large offset is removed early.

In FIG. 2B, the arrow 12 in FIG.
The alternating vibration of the offset seen at 0 is not seen and the offset is constant. This is due to the dead zone of the window comparator 116i as described above.
When the waveform originally has a positive offset from the reference value as in the waveform 118 of (b), this offset becomes a constant value of, for example, plus 3 mV, and the original signal shows a negative offset with respect to the reference value. In this case, this offset is finally fixed at -3 mV. Therefore, by looking at the original signal, it is possible to know the remaining offset component even after the offset removal, and the remaining offset component is used in the subsequent processing (for example, when performing quantization and arithmetic processing in the camera microcomputer 11). By subtracting, accurate offset removal becomes possible.

FIG. 4 is a flowchart for explaining the operation of the camera microcomputer 11. This flow is started when the main switch of the camera is turned on (the vibration detecting device 19 and the analog signal processing circuit are also used when the anti-vibration switch 18 is off). This flow operates because 116 is driven in standby.)

First, in step # 1001, the shake
Power supply for the motion detection device 19 and the analog signal processing circuit 116
To start the operation. And the next step #
In step 1002, a timer t is started, and
In top # 1003, T ₁ Wait for 0.1 second
And proceed to step # 1004. This is shown in FIG.
As described in the above, in the initial driving of the vibration detecting device 19,
Due to the large fluctuation of the offset component, the offset component
This is to avoid an extraction error.

In the next step # 1004, A /
A signal (first signal) V ₁ input from the D converter 117 to the camera microcomputer 11 is fetched. At this time D /
Since the A converter 116g has no output, the signal input to the camera microcomputer 11 has an offset,
The signal V ₁ was sometimes saturated when the offset is greater.

In step # 1005, the signal V ₁
And the reference signal Vref. At this time, even if the signal V ₁ is saturated, since the polarity of the signal V ₁ is only checked with respect to the reference signal Vref, it is sufficient to know whether the signal V ₁ is saturated to the plus side or to the minus side. No. Then, the process proceeds to step # 1006 or step # 1007 by the polarity of the signal V ₁ with respect to the reference signal Vref.

[0092] If the process proceeds to step # 1006, because here is when the signal V ₁ is larger than the reference signal Vref,
Since the offset of +3 mV remains after the offset is removed (remaining offset), +3 mV is stored in the camera microcomputer 11 to subtract the offset. Also, if the process proceeds to step # 1007, the signal V ₁ is the reference signal Vref
Since the offset is smaller than the offset, the offset of -3 mV remains even after the offset is removed (remaining offset). Therefore, -3 mV is stored in the camera microcomputer 11 to add the offset. Thereafter, the process proceeds to any step # 1008.

In step # 1008, the D / A (conversion) conversion rate of D / A converter 116g is changed. This means that the output of the D / A converter 116g per bit of the up / down counter 116f is changed from the reference 2 mV to 10 mV. And the next step #
At 1009, the camera microcomputer 11 outputs a clock signal, and the output signal (first signal) of the vibration detecting device 19
Starts removing the offset component superimposed on. At this time, D /
The D / A conversion rate of A converter 116g is rough (10mV)
Therefore, each time the camera microcomputer 11 outputs one clock, the offset is largely removed, so that the offset removing speed is high.

In the next step # 1010, T ₂
After waiting for the time, the process proceeds to step # 1011. This step # 1010 has set the time to change the D / A rate of the D / A converter 116 g, it is set to 30msec, for example, from time T _1. Next step # 1
At 011, the D / A conversion rate is initialized and the up / down counter 116 f sets the D / A conversion rate to 2 mV per bit.

[0095] In step # 1012, the flow advances to wait until after T ₂ hours to step # 1013. Wherein T ₂ hours is set to 0.1 seconds after the time T _1, to control the offset removing operation terminates. And the next step # 1
In step 013, the operation of removing the clock signal from the camera microcomputer 11 and removing the offset from the first signal is stopped, and the flow ends.

In this flow, the initialization of the D / A conversion rate is controlled by time. However, when the amount of offset superimposed on the first signal is reduced to a predetermined value or less, the D / A conversion rate is initialized. May be initialized.

FIG. 5 is a flowchart when such control is performed. What differs from FIG. 4 is step # 101.
The only difference is that 0 is changed to step # 1014.

[0098] In step # 1014, the output V ₁ of the first signal so that the process proceeds to step # 1011 after waiting until within a predetermined range V _2. As a result, the timing for initializing the D / A conversion ratio can be assured, so that the offset removal speed can be increased.

According to the first embodiment described above, the offset signal superimposed on the first signal from the vibration detecting device 19 for detecting vibration is attenuated, and the offset attenuating means (difference signal) for outputting the second signal is used. (Motor 116a, amplifier / low-pass filter 116b, clock gate 116e, up / down counter 116f, and D / A converter 116g)
A remaining offset amount fixing means (comparator 116j) for fixing an offset amount remaining in the second signal to a predetermined remaining offset value; and a residual offset removing means for removing the remaining offset amount based on the first signal. (Camera microcomputer 1
1) constitutes a device for anti-vibration control.

Further, a comparator 116j having a predetermined dead zone for comparing the first signal from the vibration detecting device 19 or a value obtained by amplifying the first signal with a reference value, and the comparator 116j
And a D / A
A converter 116g and an up / down counter 116 for increasing / decreasing an output signal of the D / A converter 116g based on a signal from the clock gate 116e.
f, a differential unit 116a for subtracting the first signal from the signal from the D / A converter 116g,
camera microcomputer 11 for subtracting a predetermined value from the signal from a
Constitutes an apparatus for anti-vibration control.

By paying attention to the fact that the remaining offset amount can be predicted, by adopting the above-described configuration, the offset removal accuracy can be further improved. Further, the circuit configuration for removing the offset signal can be made more compact than before.

Further, an offset removing means for removing an offset signal superimposed on the first signal from the vibration detecting device 19 for detecting a vibration, and an offset removing amount changing means for changing the offset removing amount are used for anti-vibration control. The offset removal amount changing means increases the offset removal amount until a predetermined time elapses after the start of the shake detection, or the offset removal amount changing means determines that the first signal has a predetermined value. When the value is larger than the value, the offset removal amount is increased.

Further, a comparator 116j for comparing the first signal from the vibration detection image value 19 or a value obtained by amplifying the signal with a reference value, a clock gate 116e to which the signal is input, a D / A converter 116g, an up / down counter 116f for increasing / decreasing an output signal of the D / A converter 116g based on a signal from the clock gate 115e, and the up / down counter 11
A camera microcomputer 11 for changing the rate of change of the D / A converter 116e by 6 g;
A differential 116 for subtracting the first signal from the signal from 16g
a constitutes a device for anti-vibration control.

By paying attention to the fact that the offset removal speed can be made variable, by adopting the above configuration, it was possible to increase the speed while maintaining the accuracy of the offset removal.

(Second Embodiment) As described above, the output of the vibration detecting device 19 is subjected to the offset removing operation again in the camera microcomputer 11. And the camera microcomputer 1
The reason why the offset removing operation is performed even before the signal is input to 1 is to prevent the signal from being saturated by the offset before the A / D conversion in the process of amplifying the signal. Therefore,
If the signal amplification rate is low, even if there is an offset, signal saturation does not occur even if there is an offset, and the offset removal function before A / D conversion can be omitted.

However, if the signal is not amplified to some extent before the A / D conversion (unless the camera shake detection sensitivity is increased), the quantization error due to the A / D conversion becomes large, and the image stabilization accuracy is reduced. It will deteriorate.

The offset component superimposed on the vibration detecting device 19 can be made sufficiently small at the time of manufacturing, but the offset change due to temperature has individual differences and cannot be compensated for by simple temperature compensation. Therefore, it is considered that the offset at room temperature is sufficiently reduced at the time of manufacturing, and the amplification factor is adjusted so that the signal does not saturate when the temperature change is severe.

In this case, when the temperature change is large, the quantization error of the A / D conversion increases and the image stabilization accuracy decreases.
The reduction in the image stabilization accuracy can be compensated for to some extent by the emission of the strobe light and the shutter speed, and that amount can be used for miniaturization by eliminating the offset removal function.

FIG. 6 is a block diagram showing a circuit configuration of a main part of a camera according to a second embodiment of the present invention. Portions denoted by the same reference numerals as those in FIG. 11 have the same functions.

FIG. 6 differs from FIG. 11 in that the DC cut filter 48p and the low-pass filter 49p are eliminated, a variable amplifying circuit 21p is provided instead, and a saturation detection circuit 22p, an amplification factor A change circuit 23p and a correction amplifier circuit 24p are provided.
The saturation detection circuit 22p and the amplification factor changing circuit 23
Although p and the correction amplification circuit 24p are shown by blocks for the sake of explanation, they are actually numerical calculation units in the camera microcomputer 11.

The variable amplifying means 21p amplifies the signal from the vibration detecting device 45p and performs a noise cut operation before A / D conversion, similarly to the low-pass filter 49p of FIG. When the signal from the A / D converter 410p is equal to or more than a predetermined value, the saturation detecting means 22p detects the saturation of the signal and sends the signal to the amplification factor changing circuit 23p. When the signal is input, the gain changing means 23p lowers the gain of the variable amplifier circuit 21p. By repeating this operation, the signal of the vibration detection device 45p is taken into the camera microcomputer 11 without saturation.

The amplification factor changing circuit 23p includes a correction amplification circuit 24.
Output the corrected amplified signal to p. This is the variable amplification circuit 2
This is to keep the image stabilization sensitivity constant by increasing the amplification factor of the correction amplifier circuit 24p by an amount corresponding to the reduction of the amplification factor of 1p.

FIG. 7 is a flowchart for explaining the above operation. This flow starts when the main switch of the camera is turned on. The same steps as those in FIG. 5 are denoted by the same step numbers.

In step # 1001, the power is applied to the vibration detecting device 19 to start the operation, and in the next step # 1002, the timer t is started. Then, at the next step # 1003, T ₁ hour (e.g., 0.1 seconds), the process proceeds to wait to step # 1004. This is to avoid an offset component extraction error due to a large fluctuation of the offset component in the initial stage of driving the vibration detecting device 19, as described with reference to FIG.

In the next step # 1004, the vibration
The first signal V from the detection device 45p ₁ Take in. Soshi
Then, in the next step # 2001, the signal V₁ Is saturated
It is determined whether or not the voltage is close to the voltage Vsa.
Proceed to step # 2002, otherwise step
Proceed to # 2003. In step # 2002,
The width factor changing circuit 23p lowers the amplification factor of the variable amplifier circuit 21p.
Make

Step # 1004 → # 2001 → #
By repeating 2002 → # 1004..., The saturation of the first signal from the vibration detecting device 45p is eliminated, so that it is possible to proceed from step # 2001 to step # 2003.

In the next step # 2003, the sensitivity of the variable amplifier circuit 21p is further reduced by half. This is because the first signal of the vibration detecting device 15p also includes an actual camera shake or a panning signal, which causes the signal to be saturated again, and the steps # 1004 and # 200.
This is to cope with the case where the saturation is eliminated for a moment due to the vibration of the hand shake during the repetition of steps # 1 and # 2002 and the process proceeds to step # 2003. And step #
In 2004, the amplification factor changing circuit 23p outputs the correction amplification signal to the correction amplification circuit 24p to make the image stabilization sensitivity constant, and ends this flow.

According to the above-described second embodiment, signal amplifying means (variable amplifying circuit 21p) for amplifying the first signal from vibration detecting device 45p for detecting vibration at a plurality of amplification factors.
And the first signal or the signal of the signal amplifying means,
A gain changing means (amplifying rate changing circuit 23p) for changing the gain of the signal amplifying means constitutes an apparatus for image stabilization control.

As a result, the offset removing means can be eliminated, and the size of the apparatus can be reduced.

(Third Embodiment) In FIG. 6, the variable amplification circuit 21p has a slightly complicated circuit because the amplification factor is variably set. FIG. 8 is a block diagram according to the third embodiment of the present invention.
Amplifying circuit 21p in which 1p is fixed to three different amplification factors
a, 21pb and 21pc. The respective signals are input to the switch circuit 31p.

The switching circuit 31p is provided with an amplification factor changing circuit 2
Three amplifier circuits 21pa-21p based on the signal from 3p
c, select an amplifier circuit with an appropriate amplification factor, and
/ D converter 410p. More specifically, the switch circuit 31p initially selects the amplifier circuit 21pa, and when the signal from the A / D converter 410p exceeds a predetermined range, the saturation detection circuit 22p sends the signal to the amplification factor changing circuit 23p. Then, the amplification factor change circuit 23p causes the switch circuit 31p to select the amplification circuit 21pb.
When the signal of the A / D converter 410p is within the predetermined range, the control of image stabilization is started using the amplifier circuit 21pa as it is.

When the amplifier circuit 21pb is selected, the signal of the A / D converter 410p is again supplied to the saturation detection circuit 22pb.
When the signal exceeds the predetermined range, the signal is output to the amplification factor changing circuit 23p, and the amplification factor changing circuit 23p causes the switch circuit 31p to select the amplification circuit 21pc. When the signal of the A / D converter 410p is within a predetermined range, the control of image stabilization is started using the amplifier circuit 21pb as it is. Of course, the amplifier circuits 21pa and 21p
The amplification factor changing circuit 23p changes the amplification factor of the correction amplification means 24p in accordance with the selection of b and 21pc, and controls so that the overall sensitivity becomes constant.

As described above, by providing a plurality of amplifying circuits having a fixed amplification factor and appropriately selecting them using the switch circuit 31p, a circuit configuration simpler than the circuit configuration of FIG. 6 can be obtained.

(Modification) The software configuration and the hardware configuration of the above embodiment can be replaced as appropriate.

Further, the present invention may be applied to a case where all or a part of the configuration of the claim or the embodiment forms one device or is combined with another device. , Which may be a constituent element of the device.

Further, the invention of each claim or the configuration of each embodiment may be such that it forms one device as a whole, or may be such that it is separated or combined with another device. Or it may be something like an element making up the device.

Although the present invention has been described as applied to a lens shutter camera, various forms of cameras such as a single-lens reflex camera and a video camera, as well as optical devices and other devices other than cameras, and The present invention can also be applied to devices applied to these cameras, optical devices, and other devices, or to components constituting these devices.

Further, the present invention may have a configuration in which the above embodiments or their techniques are appropriately combined.

[0129]

As described above, according to the first or seventh aspect of the present invention, it is possible to provide an anti-vibration control device which can be reduced in size and weight and can further increase the accuracy of offset signal removal. is there.

Further, according to the present invention, it is possible to provide an anti-vibration control device capable of increasing the offset signal removal speed while maintaining the accuracy of offset signal removal. is there.

Further, according to the ninth aspect of the present invention, since the output signal of the vibration detecting means is not saturated because the means for removing the offset is not required, the anti-vibration control apparatus which has been reduced in size is achieved. Can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a main part of a camera which is a premise of a first embodiment of the present invention.

FIG. 2 is a timing chart from the start of shake detection to the removal of an offset component in the circuit configurations of FIGS. 1 and 3;

FIG. 3 is a block diagram in which a part of the circuit configuration of FIG. 1 is modified.

FIG. 4 is a flowchart showing an operation of the camera according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing an example in which a part of FIG. 4 is changed.

FIG. 6 is a block diagram showing a configuration of a main part of a camera according to a second embodiment of the present invention.

FIG. 7 is a flowchart showing an operation of a main part of the camera according to the second embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a main part of a camera according to a third embodiment of the present invention.

FIG. 9 is an external view of a conventional compact camera having an anti-vibration system.

FIG. 10 is a perspective view showing an internal mechanism of the camera shown in FIG. 9;

FIG. 11 is a block diagram showing an internal configuration of the arithmetic device of FIG. 10;

12 is a front view of a correction unit provided in the camera of FIG.

13 is a diagram viewed from the direction of arrow B in FIG. 12 and a diagram showing a cross section taken along line AA.

FIG. 14 is a perspective view of the correction means shown in FIG.

15 is a circuit diagram showing a configuration of the DC cut filter shown in FIG.

FIG. 16 is a diagram illustrating frequency characteristics of the DC cut filter having the configuration of FIG. 15;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Camera microcomputer 19 Vibration detection device 21p Variable amplification circuit 21pa-21pc Amplification circuit 22p Saturation detection circuit 23p Amplification change circuit 31p Switch circuit 45p Vibration detection device

Claims (9)

[Claims] A first detecting means for detecting vibrations;
Attenuating an offset signal to be superimposed on the second signal, outputting a second signal, an offset attenuating means, and a remaining offset amount fixing means for fixing the remaining offset amount of the second signal to a predetermined remaining offset amount, An image stabilization control device comprising: a residual offset removing unit configured to remove the residual offset amount based on the first signal. 2. A vibration detecting means for detecting a vibration, an offset removing means for removing an offset signal superimposed on a first signal from the vibration detecting means, and an offset removing means for changing an offset removing amount of the offset removing means. An anti-vibration control device comprising: an amount changing unit. 3. The anti-vibration control device according to claim 2, wherein the offset removal amount changing means changes the offset removal amount according to an elapsed time from the start of the anti-shake control device. 4. The anti-shake control device according to claim 3, wherein the offset removal amount changing means increases the offset removal amount until a predetermined time elapses for the first time after the start of the anti-shake control device. 5. The image stabilization control device according to claim 2, wherein the offset removal amount changing means changes the offset removal amount based on the first signal. 6. The anti-vibration control device according to claim 5, wherein the offset removal amount changing means increases the offset removal amount when the first signal is larger than a predetermined value. 7. A comparator having a predetermined dead band for comparing a first signal from the vibration detecting means or a value obtained by amplifying the first signal with a reference value, and a clock to which a signal of the comparator is input. A gate, a D / A converter, an up / down counter for increasing / decreasing an output signal of the D / A converter based on a signal from the clock gate, a signal from the D / A converter, and the first signal And a differential device for subtracting the difference. 8. A comparator for comparing a first signal from the vibration detecting means or a value obtained by amplifying the first signal with a reference value, a clock gate to which the signal of the comparator is inputted,
A / A converter, an up / down counter for increasing / decreasing an output signal of the D / A converter based on a signal from the clock gate, and a D / A converter for changing a rate of change of the D / A converter by the up / down counter. A
An anti-vibration control device comprising: a control unit; and a differential that subtracts the signal from the D / A converter and the first signal. 9. A method according to claim 1, wherein said first detecting means detects a vibration from said vibration detecting means.
Signal amplification means for amplifying the signal at a plurality of amplification rates, and amplification rate changing means for changing the amplification rate of the signal amplification means based on the first signal or the signal of the signal amplification means. Characteristic anti-vibration control device.