JP5972026B2 - Vibration detection device and control device for vibration actuator - Google Patents

Description

  The present invention relates to a vibration detection device and a control device for a vibration type actuator.

The vibration type actuator pressurizes the vibrating body and the moving body, transmits the vibration force of several microns generated on the vibrating body to the moving body through the frictional force, and relatively moves between the vibrating body and the moving body. The actuator to be moved.
Since it generally has a low-speed and high-torque performance, it is used for direct drive of a drive target. Since it is directly driven in this way, a reduction gear is not required, which contributes to noise reduction.
On the other hand, since the frictional force is used, it is not easy to increase the maximum efficiency to 50% or more. Therefore, materials and processing techniques that increase the vibration efficiency have been developed.
However, when the vibration efficiency is increased, the power consumption can be reduced and the temperature rise can be suppressed. On the other hand, there is a problem that high-frequency vibration generated by the contact between the vibrating body and the moving body is likely to occur. Since this high-frequency vibration sometimes becomes audible sound, it is a major issue for noise reduction, which is an important selling point of the vibration type actuator.
So far, development has been made in a form that balances the demand for increasing efficiency and the damping performance for suppressing vibration.
However, in order to achieve noise reduction, it is necessary to set the damping performance with a sufficient margin, and a drastic improvement in efficiency cannot be taken.

Under such circumstances, some proposals have been made to suppress unnecessary vibrations by actively controlling vibrations rather than relying on mechanical damping performance.
For example, in Patent Document 1, a vibration detection phase for detecting a vibration state and a drive phase for suppressing unnecessary vibration are provided in a vibrating body, and a detection signal obtained from the vibration detection phase and the detection signal are phase-shifted. There has been proposed a method of detecting unnecessary vibration components by synthesizing these signals.
In addition, there has been proposed a drive device that attenuates unnecessary vibrations by phase-adjusting a signal indicating an unnecessary vibration component obtained by this method and inputting the signal to the drive phase.
Patent Document 2 proposes a driving device that detects an unnecessary vibration component by separating a driving frequency and an unnecessary vibration component using a band-pass filter.

JP-A-3-093480 JP-A-2-026284

However, as described in Patent Document 1, the combination of the vibration detection signal and the signal whose phase is shifted has the following problems.
That is, although it is possible to cancel the frequency component for driving, the phase delay amount of the unnecessary vibration component changes greatly according to the difference between the frequency of the unnecessary vibration component and the driving frequency.
Further, when the frequency of the unnecessary vibration component is close to the driving frequency, the phase delay increases and the amplitude also decreases.
For this reason, unnecessary vibrations cannot be suppressed in a wide frequency range, and in order to realize this, it is necessary to correct the frequency characteristics for each frequency region.
Moreover, the thing of patent document 2 also has the same subject.

In view of the above problems, an object of the present invention is to provide a vibration detection device for a vibration type actuator that can detect an unnecessary vibration component by reducing changes in amplitude and phase characteristics over a wide frequency range.
It is another object of the present invention to provide a control device for a vibration type actuator that can suppress unnecessary vibration in a wide frequency range and suppress noise.

The vibration detection device of the vibration type actuator of the present invention comprises:
A vibration detection device for a vibration type actuator, comprising: a vibrating body having a vibrating means; and a moving body that moves relative to the vibrating body by vibration of the vibrating body due to application of an alternating voltage to the vibrating means. And
Vibration detecting means for detecting vibration of the vibrating body;
Drive frequency removing means for removing, from the vibration detection signal, the signal of the frequency component of the AC voltage contained in the vibration detection signal output from the vibration detection means;
With
The drive frequency removing means includes first frequency conversion means for converting a frequency component of the vibration detection signal into a different frequency;
Filter means for removing a frequency component caused only by the frequency of the AC voltage from the output signal of the first frequency conversion means;
Second frequency conversion means for converting the output signal of the filter means to the original frequency;
It is characterized by having.

  According to the vibration detection device of the vibration type actuator of the present invention, it is possible to detect unnecessary vibration components by reducing changes in amplitude and phase characteristics over a wide frequency range. Further, according to the control device for the vibration type actuator of the present invention, it is possible to suppress unnecessary vibration in a wide frequency range and to suppress noise.

The block diagram which shows the 1st structural example of the vibration detection apparatus which detects the unnecessary vibration in Example 1 of this invention. The figure which shows the frequency characteristic explaining the operation | movement of the drive frequency removal means in Example 1 of this invention. The figure which shows the frequency characteristic of the filter in Example 1 of this invention. The block diagram which shows the example of the internal structure of the band stop filter in Example 1 of this invention. The block diagram which shows the 2nd structural example of the vibration detection apparatus which detects the unnecessary vibration in Example 1 of this invention. The figure which shows the electrode structure of the piezoelectric element in Example 1 of this invention. The figure which shows the structure of the vibration type actuator in Example 1 of this invention. The figure which shows the example of the frequency distribution of the unnecessary vibration in Example 1 of this invention. The block diagram which shows the structural example of the vibration detection apparatus which detects the unnecessary vibration in Example 2 of this invention. The figure which shows an example of the operation | movement waveform in Example 2 of this invention. The figure which shows the other example of the operation | movement waveform in Example 2 of this invention. The block diagram which shows the structural example of the vibration detection apparatus which detects the unnecessary vibration in Example 3 of this invention. The figure which shows the electrode and connection state of a piezoelectric element in the 1st structural example of Example 3 of this invention. The figure which shows the structure of the vibration type actuator of Example 3 of this invention. The block diagram which shows the structure of the speed control part of Example 3 of this invention. The block diagram which shows the unnecessary vibration control apparatus in the 2nd structural example of Example 3 of this invention. The figure which shows the electrode and connection state of a piezoelectric element in the 2nd structural example of Example 3 of this invention. The block diagram which shows the unnecessary vibration control apparatus in the 3rd structural example of Example 3 of this invention.

  The mode for carrying out the present invention will be described with reference to the following examples.

[Example 1]
As a first embodiment, a configuration example of a vibration detection apparatus that detects unnecessary vibration to which the present invention is applied will be described.
A vibration actuator is an actuator that vibrates an elastic body made of metal or ceramic using the resonance phenomenon of its natural vibration mode and relatively moves a moving body that contacts the elastic body. Actuators have been proposed.
A piezoelectric element is mainly used as a generation source of the excitation force for excitation, but in principle, any excitation means can be used.
For example, it can be excited using various actuators such as a magnetostrictive element, an electrostrictive element, a voice coil, and an electrostatic actuator.
These actuators can generate an excitation force by inputting an AC voltage or an AC current having the same frequency as the excitation frequency.
In the case of a piezoelectric element, an alternating voltage to be applied, and in the case of a voice coil, an alternating current corresponds to an excitation force. In the following embodiments, a case using a piezoelectric element will be described as an example.

The vibration detection apparatus of this embodiment includes the following drive frequency removing means. That is, the first frequency conversion means for converting the frequency of the AC voltage for driving the vibration type actuator included in the frequency component of the output signal of the vibration detection means into a different frequency is provided.
Further, a filter means for cutting off the frequency component caused only by the frequency of the AC voltage from the output signal of the first frequency conversion means, and a second frequency for returning the remaining frequency component output from the filter means to the original frequency component. It has conversion means.
As a result, the frequency component signal of the AC voltage included in the vibration detection signal output from the vibration detection means is removed from the vibration detection signal, and an unnecessary vibration waveform with small amplitude and phase change is detected in a wide frequency range. .
As a specific example, first, a first configuration example will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes a piezoelectric element provided on a vibrating body (not shown), and 2 denotes an AC voltage generating means for generating an AC voltage having a frequency corresponding to a frequency command designated by a command means (not shown) on the piezoelectric element 1. is there.
Reference numerals 3 and 5 denote current detection means for measuring currents flowing into the piezoelectric element 1 and a capacitor 4 described later, respectively.
Reference numeral 4 denotes a capacitor having an electrostatic capacity substantially equal to the braking capacity of the piezoelectric element 1.
Reference numeral 6 denotes vibration detection means for obtaining and outputting a difference between output signals of the current detection means 3 and the current detection means 5.
This cancels the current flowing into the braking capacity of the piezoelectric element 1 from the current flowing into the piezoelectric element 1, and vibrates a component that flows outside the braking capacity of the piezoelectric element 1, that is, a signal proportional to the vibration speed of a vibrating body (not shown) It is output as a detection signal.
7 is a sine wave generating means for generating a sine wave signal having a frequency corresponding to the frequency command, and 8 is a cosine wave generating means for generating a cosine wave signal having a frequency corresponding to the frequency command.
9 is a first multiplication means, and 10 is a second multiplication means. Thus, by multiplying the vibration detection signal and the sine wave signal and the vibration detection signal and the cosine wave signal, a first frequency conversion means for converting the frequency component of the vibration detection signal into a different frequency component. It is composed.

Here, this frequency conversion will be described.
2A and 2B are diagrams for explaining the frequency conversion operation of the multiplication means 9 and 10. FIG. The horizontal axis indicates frequency and the vertical axis indicates amplitude.
Hereinafter, the frequency conversion operation will be described with reference to FIGS. 1 and 2.
If the frequency command is F0, the frequency of the AC voltage output from the AC voltage generating means (hereinafter referred to as the drive frequency) is F0.
Therefore, an excitation force having a frequency F0 is applied to the piezoelectric element 1, and a vibrating body (not shown) provided with the piezoelectric element 1 vibrates.
Then, the main frequency component of the vibration detection signal corresponding to the vibration speed of the vibrating body is F0. The solid line component shown above F0 in FIG. 2A indicates the magnitude of vibration at this time.
Here, it is assumed that another vibration is generated in a vibrating body (not shown) by some external force. This is indicated by a broken line in FIG.
In FIG. 2A, all signals indicated by solid lines and broken lines are input to the multiplication means 9 and 10 as vibration detection signals.
When this vibration detection signal is multiplied by a sine wave and a cosine wave having the frequency F0, the respective frequencies are added and subtracted in the frequency domain, as is apparent from the multiplication theorem of the trigonometric function.
The result of the conversion is shown in FIG.
The signal of the frequency command F0 is converted into a frequency component indicated by two solid lines of F0 frequency and 0 (DC) due to the difference by adding two F0s.
In other words, the signal of the driving frequency component is converted into the double F0 and the direct current component that are the frequency caused by the driving frequency F0 by the frequency conversion.
Similarly, the unnecessary vibration component is also converted into a frequency in a region indicated by two broken lines by addition and subtraction with F0.

Next, post-processing of frequency conversion will be described.
The purpose of this apparatus is to detect only the broken line area in FIG. 2A, and it is necessary to block the solid line waveform.
This process is performed on the signal after the above frequency conversion, and the characteristic of this apparatus is that the signal indicated by the solid line in the state of FIG. 2B is cut off to the state of FIG. To perform the operation. A block for executing this operation will be described with reference to FIG.
Reference numerals 11 and 12 denote band stop filters which cut off a signal having a frequency component twice the frequency indicated by a frequency command from a command means (not shown).
A filter with a narrow band as much as possible is desirable, and is constituted by a notch filter having a high Q value.
Reference numerals 13 and 14 denote high-pass filters that block DC components included in the signal.
As shown in FIG. 2C, when the double F0 component is cut by the band stop filters 11 and 12, the unnecessary vibration component in the vicinity of the double F0 frequency also has a smaller amplitude as the frequency difference from the double F0 is smaller. Will be attenuated.
However, even if the DC component is cut by the high-pass filters 13 and 14, if the cutoff frequency is set appropriately, the influence on the unnecessary vibration component can be minimized.
This is due to the large difference between the 49 kHz characteristic when 50 kHz is cut by the band stop filter and the 1 kHz characteristic when 10 Hz is cut by the high-pass filter.
In other words, the DC side can make the cut-off frequency infinitely low, while the band stop filter cannot do this.
FIG. 3A is a diagram illustrating an example of the frequency characteristics of the band stop filter, and FIG. 3B is a diagram illustrating an example of the frequency characteristics of the high-pass filter.

Next, frequency conversion means (second frequency) when the frequency component of the unnecessary vibration divided into the two frequency regions in FIG. 2C is frequency-converted again and returned to the original frequency component in FIG. The operation of the conversion means) will be described.
Reference numeral 15 shown in FIG. 1 denotes third multiplication means, and 16 denotes fourth multiplication means.
When the sine wave signal and the cosine wave signal are multiplied by the multiplying means 15 and the multiplying means 16 with respect to the frequency component divided into the two broken line areas in FIG. 2C, three frequency components are obtained as shown in FIG. The frequency is converted to the frequency domain. As a result of multiplication with the sine wave signal and cosine wave signal of the frequency command F0, the result of frequency conversion of the broken line portion of FIG. 2C by subtraction of the frequency with F0 is the broken line region of FIG. The result converted by the addition of the frequency is the dotted line region in FIG.
Next, an operation for extracting only unnecessary vibration components from the state divided into three frequency regions will be described.
Reference numeral 17 in FIG. 1 denotes an adding means (first adding means), which adds the outputs of the multiplying means 15 and 16 and outputs an unnecessary vibration signal.
The phase characteristics of the output signals of the multiplication unit 15 and the multiplication unit 16 have a region in phase with a region that is relatively shifted by 180 °.
A frequency region indicated by a dotted line in FIG. 2D is a region where the phase characteristics are shifted by 180 °.
By using this characteristic, the outputs of the multiplication means 15 and 16 are added by the addition means 17 to cancel the frequency region indicated by the dotted line in FIG.

FIG. 2E shows the distribution of the frequency components of the unnecessary vibration signal finally obtained.
Although the amplitude and phase characteristics of the obtained unwanted vibration signal slightly change with respect to the original characteristics, it is possible to reduce the change by dividing the frequency domain into two, filtering and synthesizing again. .
That is, since the filtering process for the frequency component divided to the DC side does not deteriorate the characteristic of the unnecessary vibration component, the change in the amplitude and phase characteristics can be reduced as compared with the conventional method of directly filtering the vibration detection signal. .
In addition, although the frequency is converted to a double frequency here, it may be converted at other magnifications.
If one frequency is a DC component, the same effect can be obtained. For example, as a method of quadrupling, a direct current component is blocked by a high-pass filter with respect to a state once converted to a double frequency.
Then, there are only twice as many frequency components and unnecessary vibration components. Considering this double frequency as a new drive frequency, if this is multiplied by a sine wave and cosine wave of double frequency, the frequency can be converted into a frequency component that is four times the drive frequency and a new DC component. .

FIG. 4 is a diagram illustrating an example of the internal configuration of the band stop filters 11 and 12. When there are a plurality of frequency commands (not shown), it is necessary to change the frequency characteristics of the band stop filters 11 and 12 with respect to the frequency.
The example of FIG. 4 shows an example when the frequency command is limited to three. Reference numerals 18, 19 and 20 denote band stop filters whose frequency characteristics are set in advance so as to cut off different frequencies. Reference numeral 21 denotes switching means for switching which of the band stop filters 18, 19, 20 is used according to a frequency command from a command means (not shown).
Each band stop filter is adjusted to cut twice the frequency with respect to its frequency command.
In this embodiment, three frequency characteristics are used. However, a switch and a capacitor filter that can continuously switch the frequency characteristics, an adaptive filter that automatically follows the largest frequency component, or the like may be used.
Further, the frequency to be cut off by the band stop filter is set to be twice as high as the frequency command.
Actually, the drive frequency and the frequency of the vibration detection signal may not completely match when the drive frequency changes. What is necessary is just to determine the precision of a frequency characteristic according to the magnitude | size and precision of the unnecessary vibration which should be measured.

Next, a second configuration example of the present embodiment will be described with reference to FIG.
The configuration example of FIG. 5 is substantially the same as that of FIG. 1, and a description of the overlapping configuration is omitted. Reference numerals 22-a, 22-b, and 22-c denote piezoelectric sections corresponding to respective electrodes of a ring-shaped piezoelectric element to be described later, and are hereinafter referred to as electrodes 22-a, electrodes 22-b, and electrodes 22-c. FIG. 6 shows the electrode configuration of the piezoelectric element 22.
The code | symbol shown in FIG. 6 has shown the polarization direction of each electrode area | region, and electrode 22-a and electrode 22-b consist of several polarization divisions.
The polarization sections in the electrode 22-a and the electrode 22-b are electrically connected, and when an alternating voltage of a predetermined frequency is applied, the vibration of compression / expansion is repeated according to the polarity, and 8 along the circumferential direction of the ring. Two bending vibrations are formed.
Further, AC voltages φA and φB having a phase difference of 90 ° are applied to the electrodes 22-a and 22-b by the sine wave generating means 7 and the cosine wave generating means 8, and the antinodes of the bending vibration are positioned in the circumferential direction of the ring. A progressive vibration wave that continuously moves is formed.

FIG. 7 is a diagram illustrating a configuration example of a vibration type actuator using a ring-shaped piezoelectric element.
In FIG. 7, reference numeral 45 denotes a vibrating body to which the piezoelectric element 22 is bonded, and 44 denotes a rotor that is in pressure contact with an upper portion of the vibrating body 45 by a pressing means (not shown).
The rotor 44 rotates in the circumferential direction by minute elliptical vibration formed at the contact portion with the vibrating body 45.
The electrode 22-c is an electrode for detecting vibration displacement. Reference numeral 23 denotes vibration detection means for cutting the DC component of the output signal of the electrode 22-c and outputting a vibration detection signal. The vibration detection signal output from the vibration detection means 23 is a signal proportional to the vibration displacement of the section provided with the electrode 22-c.
As shown in FIG. 7, a plurality of protruding structures are provided at the contact portion of the vibrating body 45, and contact with the rotor 44 at high frequency is repeated. For this reason, high-order vibrations caused by contact may be generated by self-excitation.

FIG. 8 is a diagram illustrating an example of a frequency distribution of a vibration detection signal when unnecessary vibration occurs.
In FIG. 8, the component with the largest amplitude indicated by F8 indicates the vibration of the drive frequency component that drives the vibration type actuator. Eight bending vibrations (eighth-order vibrations) are caused on the ring-shaped vibrating body 45 along the circumference of the ring. (Bending vibration).
The frequencies indicated by F4, F6, F7, and F9 indicate the amplitudes of the fourth, sixth, seventh, and ninth bending vibrations, respectively.
As described above, the actual unnecessary vibration is generated in the vicinity of the natural frequency of the vibration shape (wave number) obtained by the mode analysis, and thus shows a discrete frequency characteristic. Unnecessary vibration often occurs in the vicinity of the main drive order (8th order in the present embodiment) or a half order.
In the case of detecting such unnecessary vibration, since the frequency component close to F8 such as F7 and F9 has a small frequency difference in the conventional method of removing the drive frequency component by the direct filter, the amplitude and phase characteristics are not sacrificed. It was difficult to separate. If this method is used, changes in amplitude and phase characteristics can be reduced as compared with the prior art.

Moreover, although the example of the apparatus which detects an unnecessary vibration signal was demonstrated in the said description, various proposals regarding the method of suppressing an unnecessary vibration using a detection result are made.
For example, there is a method of avoiding unnecessary vibration by reducing the vibration amplitude of the vibration body 45 when unnecessary vibration occurs.
When unnecessary vibration occurs, it is a vibration type actuator that is driven at a frequency outside the audible range, but audible sound may be generated due to the beating phenomenon between the unnecessary vibration and the drive frequency. ing.
If the amplitude of the unwanted vibration signal detected in the present embodiment is greater than a predetermined value, for example, the amplitude of the drive voltage is lowered, or the frequency of the AC voltage applied to the piezoelectric element 22 is shifted to a higher frequency, etc. You may comprise so that the vibration amplitude of 45 may be lowered | hung.

[Example 2]
As a second embodiment, a configuration example of a vibration detection device that detects unnecessary vibration in a form different from that of the first embodiment will be described with reference to FIG.
The difference between the present embodiment shown in FIG. 9 and the first embodiment is that processing is performed by digital calculation.
Blocks having the same functions as those in the first embodiment are denoted by the same numbers as those in the first embodiment, and description thereof is omitted.
A pulse generator 24 outputs a clock signal having a frequency 16 times the frequency command from a command means (not shown). Reference numeral 25 denotes a 4-bit counter that counts clock signals and repeatedly outputs 4-bit address signals from 0 to 15. Reference numerals 26 and 27 denote ROMs in which waveforms of sine waves and cosine waves corresponding to 4-bit address signals are stored.
Reference numeral 28 denotes A / D conversion means for A / D converting the vibration detection signal at the timing of the clock signal.
Here, the vibration detection signal may be a signal after filtering in order to avoid the influence of aliasing generated by A / D conversion.
Reference numerals 29 and 30 denote delay means. The input signal is output after being delayed by 4 clock signals. Reference numerals 31 and 32 denote addition means (second addition means).
The combination of the delay unit 29 and the addition unit 31 and the combination of the delay unit 30 and the addition unit 32 constitute a band stop filter.
The input signal is delayed by a half cycle by a delay of 4 clock signals and added by the adding means 31 and 32 to cancel the input signal.
Here, the waveforms of the sine wave and cosine wave output from the ROMs 26 and 27 are stored so as to be one cycle for 16 clock signals.
Therefore, the frequency canceled with a delay of 4 clocks (a time delay corresponding to a quarter period of the stored waveform) is twice the frequency of the sine wave.
Reference numerals 33 and 34 denote D / A conversion means for converting sine waves and cosine waves output from the ROMs 26 and 27 into analog signals and outputting them. The output signals φA and φB are applied directly or amplified to a piezoelectric element (not shown).
The operation speed of each part in FIG. 9 is higher than the timing of the clock signal in order to reduce the delay in the operations other than the delay means 29 and 30.

Below, operation | movement of the vibration detection apparatus in a present Example is demonstrated using each waveform.
10 and 11 show examples of waveforms corresponding to the signal names shown in the drawings. FIG. 10A shows a waveform of Vin and an output signal of the A / D conversion means 28.
The waveform is stepped and is output after A / D conversion at the timing of the clock signal.
FIG. 10B shows the output waveform of the ROM 27 which is a Vcos waveform and is output at the timing of the clock signal.
FIG. 10C shows the waveform of Vc1. A DC component and a double frequency component are generated by multiplying signals of the same frequency with different phases.
FIG. 10D shows the waveform of Vc2, and the waveform of Vc1 is delayed by 4 clock signals and output.
FIG. 10E shows the output of the adding means 32 with a waveform of Vc3. Since the phases of Vc1 and Vc2 are inverted, a frequency component almost twice the frequency of Vin is canceled from the result of addition by the adding means 32, and a component caused by a DC component and unnecessary vibration is output. .
FIG. 10F shows a waveform of Vc4, in which a DC component is cut by the high pass filter 14 and a waveform resulting from unnecessary vibration is output.
For Vs1, Vs2, Vs3, Vs4, and Vsin shown in FIG. 9, substantially the same waveforms as in FIG. 10 are obtained.

Next, another example of the waveform will be described with reference to FIG.
FIG. 11A shows the waveform of Vc4 in a wider time range than FIG. 10F.
FIG. 11B shows the waveform of Vs4. FIG. 11C and FIG. 11D show the waveforms of Vc5 and Vs5, respectively. This is the result of multiplying the waveforms of Vc4 and Vs4 by the multiplication means 15 and 16 with the waveforms of Vcos and Vsin, respectively.
FIG. 11E shows a waveform of Vout, and an unnecessary vibration component signal is obtained.
As described above, since each unit operates in synchronization with the clock signal, even if the frequency command from the command unit (not shown) changes, the cutoff characteristic of the band stop filter composed of the delay unit and the addition unit is interlocked with the change of the drive frequency. And change. Therefore, even when the driving frequency is continuously changed, the signal of the driving frequency component can be sufficiently attenuated from the vibration detection signal.

[Example 3]
As a third embodiment, a configuration example of an unnecessary vibration control device to which the present invention is applied will be described.
FIG. 12 is a block diagram illustrating a first configuration example of the unnecessary vibration control apparatus according to the present embodiment.
In this embodiment, the unnecessary vibration signal detected by the vibration detection apparatus of the first embodiment is used to control the unnecessary vibration of the vibration type actuator.
Reference numeral 35 denotes AC voltage generating means for generating AC voltages having a phase difference of 90 ° at a frequency corresponding to a frequency command from a speed control unit described later.
The two-phase voltage consists of φA and φB signals. Reference numeral 36 denotes a piezoelectric element. Reference numerals 36-a, 36-b, and 36-c denote piezoelectric sections corresponding to the respective electrodes provided on the piezoelectric element 36 to be described later. Hereinafter, the electrodes 36-a and 36-b are shown. , Referred to as electrode 36-c.

FIG. 13 is a diagram showing electrodes and connection states of the piezoelectric element 36, in which an AC voltage φA is connected to the electrode 36-a, and an AC voltage φB is connected to the electrode 36-b.
The symbol in the figure indicates the polarization direction of the piezoelectric element.
The AC voltage φA and the AC voltage φB are alternately connected to the electrodes of the piezoelectric element 36 along the circumference.
Reference numeral 37 in FIG. 12 denotes an amplifier which inverts and amplifies an unnecessary vibration signal obtained from a vibration detection signal corresponding to the vibration speed detected by the electrode 36-c. Reference numeral 38 denotes an adding means for adding the inverted and amplified unnecessary vibration waveform to the AC voltage φA and outputting the AC voltage φA ′. The AC voltage φA ′ is applied to the electrode 36-c.
Thus, when the unnecessary vibration signal is a signal proportional to the vibration speed, the damping characteristic against the unnecessary vibration is strengthened by inverting and amplifying the signal, and self-excitation of the unnecessary vibration is suppressed.

FIG. 14 is a diagram showing a configuration of a vibration type actuator driven by the piezoelectric element 36.
Except for the piezoelectric element, the configuration is the same as that shown in FIG. FIG. 15 is a block diagram showing the configuration of a speed control unit for controlling the rotational speed (relative movement speed) of the rotor 44 of this vibration type actuator.
Reference numeral 39 denotes speed detection means such as a rotary encoder for detecting the rotational speed of the rotor 44, and reference numeral 40 denotes subtraction means for obtaining a difference between a speed command from a command means (not shown) and the output of the speed detection means 39.
Reference numeral 41 denotes a frequency control means for inputting a speed difference output from the subtracting means 40, performing a proportional integration calculation, etc., and outputting a frequency command.
The frequency control means 41 operates so as to decrease the frequency command when the output of the speed detection means 39 is slower than the speed command, and increase the frequency command if the output is reverse.
When the frequency command is lowered, the frequency of the AC voltage output from the AC voltage generating means approaches the resonance frequency of the vibrating body 45, so that the vibration amplitude of the vibrating body 45 increases and the rotation speed of the rotor 44 increases.

Next, a second configuration example of the unnecessary vibration control device of this embodiment will be described with reference to FIG.
This second configuration example is configured to control the unnecessary vibration of the vibration type actuator using the unnecessary vibration signal detected by the vibration detection device that detects the unnecessary vibration in the second configuration example in the first embodiment. It is.
In the example of FIG. 12, the unnecessary vibration signal is a signal proportional to the vibration speed of the vibrating body 45, whereas in this example, the unnecessary vibration signal is a signal proportional to the vibration displacement of the vibrating body 45, The difference is that the detected electrode and the vibrating electrode are different.
Reference numeral 42 denotes a piezoelectric element, and 42-a, 42-b, 42-c, and 42-d denote piezoelectric sections corresponding to electrodes described later provided on the piezoelectric element. They are referred to as electrode 42-b, electrode 42-c, and electrode 42-d.

FIG. 17 is a diagram showing the electrodes of the piezoelectric element 42 and the connection state. The AC voltage φA is connected to the electrode 42-a and the AC voltage φB is connected to the electrode 42-b. Connected to detect vibration displacement from c.
The excitation electrode for suppressing unnecessary vibration is 42-d, and the φA ′ signal is applied.
Reference numeral 43 denotes a phase shift means that adjusts the phase delay of the unnecessary vibration signal so that the effect of suppressing unnecessary vibration is maximized.
The reason why the phase shift means 43 is necessary is that the vibration detection position and the vibration excitation position are different, and the vibration displacement is delayed by 90 ° with respect to the relative vibration speed. Because.

Next, a configuration example of a third example of the unnecessary vibration control apparatus of this embodiment will be described with reference to FIG.
This third configuration example is configured to control unnecessary vibration of the vibration type actuator using the unnecessary vibration signal detected by the vibration detecting device for detecting unnecessary vibration according to the second embodiment.
Description of the same numbers in the second embodiment is omitted. Reference numerals 46 and 47 denote amplifiers that amplify the output signals of the D / A conversion means 33 and 34.
Reference numeral 48 denotes a vibration speed detecting means for optically measuring the vibration speed near the center of the electrode 36-c in a non-contact manner.
The unnecessary vibration signal output from the adding means 17 is an unnecessary vibration component included in the vibration speed near the center of the electrode 36-c of the piezoelectric element 36.
This signal is inverted and amplified by the amplifier 37, added by the adding means 38 to the AC voltage φA, and applied to the electrode 36-c.
By detecting a signal corresponding to the vibration speed of the unnecessary vibration and applying it to the electrode 36-c which is the excitation electrode at the detected position after being inverted and amplified, the damping against the unnecessary vibration is performed as in the example shown in FIG. The characteristic is strengthened and self-excited generation of unnecessary vibration is suppressed.
According to the configuration of the present embodiment, the frequency of the AC voltage that drives the vibration type actuator included in the frequency component of the output signal of the vibration detection means is converted to a different frequency by the first frequency conversion means. Then, after the frequency component caused only by the frequency of the AC voltage is cut off by the filter means, the remaining frequency component is returned to the original frequency component by the second frequency conversion means.
By inputting this to the control means and vibrating the vibrating body, unnecessary vibration in a wide frequency range of the vibration type actuator can be suppressed, but noise can be suppressed.

1: Piezoelectric element 2: AC voltage generation means 3, 5: Current detection means 4: Capacitor 6: Vibration detection means 7: Sine wave generation means 8: Cosine wave generation means 9, 10, 15, 16: Multiplication means 11, 12 ,: Band stop filters 13 and 14 are high-pass filters 17: addition means

Claims (11)

A vibration detection device for a vibration type actuator, comprising: a vibrating body having a vibrating means; and a moving body that moves relative to the vibrating body by vibration of the vibrating body due to application of an alternating voltage to the vibrating means. And
Vibration detecting means for detecting vibration of the vibrating body;
Drive frequency removing means for removing, from the vibration detection signal, the signal of the frequency component of the AC voltage contained in the vibration detection signal output from the vibration detection means;
With
The drive frequency removing means includes first frequency conversion means for converting a frequency component of the vibration detection signal into a different frequency;
Filter means for removing a frequency component caused only by the frequency of the AC voltage from the output signal of the first frequency conversion means;
Second frequency conversion means for converting the output signal of the filter means to the original frequency;
A vibration detection device for a vibration type actuator comprising: The first frequency conversion means includes
2. The vibration type actuator according to claim 1, further comprising a first multiplying unit and a second multiplying unit that multiply the sine wave and cosine wave of the frequency of the AC voltage by the vibration detection signal. Vibration detection device. The second frequency converting means includes
Third and fourth multiplication means for multiplying the sine wave and cosine wave of the frequency of the alternating voltage by the output signal of the filter means;
First addition means for adding the outputs of the third multiplication means and the fourth multiplication means;
The vibration detection device for a vibration type actuator according to claim 1, wherein   4. The vibration detection apparatus for a vibration type actuator according to claim 1, wherein the filter unit removes a frequency component and a DC component that are twice the frequency of the AC voltage. 5.   5. The vibration detection device for a vibration type actuator according to claim 1, wherein the filter unit includes a notch filter that cuts off a frequency component that is twice the frequency of the AC voltage. 6.   The said filter means has a 2nd addition means which adds an input signal and the signal which delayed this input signal for the period of the quarter of the period of the said alternating voltage. The vibration detection device of the vibration type actuator according to 1. A vibration type actuator control device comprising: the vibration type detection device for a vibration type actuator according to any one of claims 1 to 6; and an AC voltage generation unit that generates the AC voltage .   8. The vibration type actuator control device according to claim 7, wherein an output signal of the drive frequency removing unit is added to an AC voltage output from the AC voltage generating unit and output.   9. The vibration type actuator control device according to claim 7, wherein the vibration detecting means detects a vibration speed of the vibrating body.   The control of the vibration type actuator according to any one of claims 7 to 9, wherein a relative moving speed of the moving body and the vibrating body is controlled by a frequency of the AC voltage output from the AC voltage generating means. apparatus. The vibration type actuator comprising the vibration body having the vibration means and the moving body, the vibration detection device of the vibration type actuator according to any one of claims 1 to 6, and the AC voltage. An AC voltage generating means for generating .

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