JP7520686B2 - Vibration type driving device and driving method for a vibration type driving device - Google Patents

Description

This relates to a drive device for an actuator that uses ultrasonic vibration.

In a vibration actuator that uses a vibrating body that is excited by an electrical-mechanical energy conversion element (piezoelectric element, electrostrictive element, etc.), a method is known for measuring the applied voltage to detect defects such as a disconnection in the vibrating body. For example, Patent Document 1 shows an example of detecting a disconnection by detecting the generation of high-frequency components in an AC voltage applied to the vibrating body via an inductor. Patent Document 2 also shows an example of detecting a disconnection by detecting changes in the Q value or peak frequency of the peak characteristics of the frequency characteristics of the applied voltage that change depending on the characteristics of a step-up transformer.

In the case of a single vibrator as in Patent Document 1, the change in applied voltage due to a disconnection is large, and the occurrence of a disconnection can be detected by the generation of high-frequency components. However, the following problems exist in a series-connected vibrator device in which multiple vibrator units, each having an inductor element and a vibrator connected in parallel, are connected in series, or in which a vibrator is connected in parallel to the secondary side of multiple transformers and the primary side of each transformer is connected in series.

In other words, even if one vibrator breaks, there is little change in the waveform of the voltage applied to both ends of the series connection, and the high-frequency components that appear in a frequency range higher than the drive frequency increase or decrease depending on the frequency. For this reason, the presence or absence of a break cannot be determined simply because high-frequency components have been generated.

Also, as in Patent Document 2, by using the frequency characteristics of the secondary side of the transformer to focus on the peak characteristics of the frequency characteristics of the applied voltage and using a method to detect the peak frequency and Q value, it is possible to detect defects in individual vibrators. However, in the above-mentioned series-connected vibrator device, it is necessary to detect the AC voltage applied to all vibrators, and while it is possible to detect defective parts, there is a drawback in that the circuit size becomes large. In addition, there is a problem that the detection of the peak frequency and Q value using frequency sweep in the high frequency range or pseudo-random numbers is likely to cause speed fluctuations and abnormal noise if it is performed independently by superimposing a separate high frequency voltage while applying a normal driving voltage. In a vibration type unit in which multiple vibrators are connected in series, even if one of the multiple vibrators breaks, the applied voltage is supplied to the other vibrators and they can be driven to a certain extent, so they have the property that they can continue to be driven even if the wire breaks. However, there is a problem that the burden on the other vibrators becomes heavy in the broken state, and performance deterioration may progress at an accelerated rate.

Patent No. 5716624 Patent Publication No. 2018-78769

In view of the above problems, the present invention aims to detect a disconnection of a vibrator while it is being driven in a vibrator unit that has multiple vibrators connected together.

The vibration type driving device for solving the above problem includes: a control unit that outputs a command signal;
A drive unit that outputs a drive signal based on the command signal;
a vibrator unit including two or more vibrators arranged in series and vibrating based on the drive signal;
a drive signal analysis means for analyzing the drive signal and outputting an analysis result; and a determination means for determining whether or not a wire connected to the vibrating body is broken based on the analysis result,
The vibrator unit includes a plurality of transformers whose primary sides are connected in series, and the secondary sides of the transformers are connected in parallel to each other, and the primary sides of the transformers are configured to receive the drive signal,
the driving unit includes a rectangular voltage generating means for generating a pulse signal having a predetermined voltage and frequency, and a waveform shaping means inserted between the rectangular voltage generating means and the vibrator unit,
The frequency of the harmonic of the drive signal is configured to be near the lowest point of the valley of the frequency characteristic of the output voltage or output current of the waveform shaping means when the vibrator is not broken.
Another vibratory drive device is
A control unit that outputs a command signal;
A drive unit that outputs a drive signal based on the command signal;
a vibrator unit including two or more vibrators arranged in series and vibrating based on the drive signal;
a drive signal analysis means for analyzing the drive signal and outputting an analysis result; and a determination means for determining whether or not a wire connected to the vibrating body is broken based on the analysis result,
The vibrator unit includes a plurality of pairs of a pair of an inductor and a vibrator connected in parallel and connected in series,
the driving unit includes a rectangular voltage generating means for generating a pulse signal having a predetermined voltage and frequency, and a waveform shaping means inserted between the rectangular voltage generating means and the vibrator unit,
The frequency of the harmonic of the drive signal is configured to be near the lowest point of the valley of the frequency characteristic of the output voltage or output current of the waveform shaping means when the vibrator is not broken .

According to the present invention, in a vibration type drive device having a vibration type unit in which multiple vibrators are connected, it is possible to detect a disconnection of a vibrator during normal operation. Even if a disconnection occurs during normal operation, it is possible to quickly implement drive control according to the disconnection situation, thereby reducing the impact of the disconnection on peripheral mechanisms and the user.

FIG. 1 is a diagram showing a first example of a drive circuit for a vibration actuator according to a first embodiment; FIG. 1 is a diagram showing a first example of the structure of a vibration type actuator; A diagram showing electrical connections within a vibration actuator. FIG. 11 is a diagram showing a first example of a change in frequency characteristic of a driving voltage amplitude when a wire is broken in the first embodiment; FIG. 13 is a diagram showing a change in the driving voltage waveform when a wire is broken in the first embodiment; FIG. 11 is a diagram showing a first example of an analysis result when driven by a pulse signal with a duty of 50% in the first embodiment; FIG. 11 is a diagram showing a first example of an analysis result when driven by a pulse signal with a duty of 38% in the first embodiment; FIG. 11 is a diagram showing a first example of the relationship between the number of breaks and analysis results when driven by a pulse signal with a duty of 50% in the first embodiment; FIG. 11 is a diagram showing a first example of the relationship between the number of breaks and analysis results when driven by a pulse signal with a duty of 38% in the first embodiment; FIG. 2 is a diagram showing a second example of a drive circuit for the vibration actuator according to the first embodiment; FIG. 11 is a diagram showing a second example of a change in frequency characteristic of a driving voltage amplitude when a wire is broken in the first embodiment; FIG. 11 is a diagram showing a second example of the analysis results when driven by a pulse signal with a duty of 50% in the first embodiment; FIG. 11 is a diagram showing a third example of a drive circuit for the vibration actuator according to the first embodiment; FIG. 11 is a diagram showing a third example of a change in frequency characteristic of a driving voltage amplitude when a wire is broken in the first embodiment; FIG. 11 is a diagram showing a third example of an analysis result when driven by a pulse signal with a duty of 50% in the first embodiment; FIG. 2 is a diagram showing a second example of the analysis results when driven by a pulse signal with a duty of 38% in the first embodiment; FIG. 11 is a diagram showing a first example of a drive circuit for a vibration actuator according to a second embodiment; FIG. 13 is a diagram showing an example of a change in frequency characteristic of a driving voltage amplitude when a wire is broken in the second embodiment; FIG. 13 is a diagram showing an example of a change in a driving voltage waveform when a wire is broken in the second embodiment; FIG. 13 is a diagram showing an example of an analysis result when driven by a pulse signal with a duty of 50% in the second embodiment; FIG. 13 is a diagram showing a second example of a drive circuit for a vibration actuator according to a second embodiment; FIG. 13 is a diagram showing the configuration of a vibrating body of a vibration actuator according to a third embodiment; FIG. 13 is a diagram showing vibration modes of a vibrating body according to a third embodiment; FIG. 13 is a diagram showing a configuration example of a vibration actuator according to a third embodiment; FIG. 13 is a diagram showing a drive circuit of a vibration actuator according to a third embodiment. FIG. 13 is a diagram showing an example of a change in frequency characteristic of a driving voltage amplitude when a wire is broken in the third embodiment; FIG. 13 is a diagram showing a change in the driving voltage waveform when a wire is broken in the third embodiment. FIG. 13 is a diagram showing an example of an analysis result when driven by a pulse signal with a duty of 50% in the third embodiment; 11 is a flowchart showing an example of the operation of the CPU 15 according to the third embodiment. 11 is a flowchart showing an example of the operation of the CPU 15 of the third embodiment, including waveform analysis, disconnection determination, and vibration amplitude control. FIG. 13 is a diagram showing a drive circuit of a vibration actuator according to a fourth embodiment. FIG. 13 is a diagram showing an example of a change in frequency characteristic of a driving current when a wire is broken in the fourth embodiment; FIG. 13 is a diagram showing an example of an analysis result when driven by a pulse signal with a duty of 50% in the fourth embodiment; 13 is a flowchart showing an example of the operation of the CPU 15 of the fourth embodiment, including waveform analysis, disconnection determination, and vibration amplitude control.

One example of an embodiment of the present invention is a vibration type driving device that includes a control unit that outputs a command signal, a driving unit that outputs a drive signal based on the command signal, and a vibrating body unit in which two or more vibrating bodies that vibrate based on the drive signal are connected. It further includes a drive signal analysis means that analyzes the drive signal and outputs the analysis result, and a determination means that determines whether or not there is a break in the wiring connected to the vibrating body based on the analysis result.

Another example of a form for implementing the present invention is a control method as follows. That is, a control unit outputs a command signal to a drive unit, and a vibrator unit having two or more vibrators connected together vibrates due to a drive signal output by the drive unit based on the command signal. At the same time, the control method for a vibration type drive device analyzes the drive signal, outputs the analysis result, and determines whether or not there is a break in the wiring connected to the vibrator based on the analysis result.

This configuration makes it possible to detect a disconnection in a vibrating body during normal operation in a vibration actuator that has multiple vibrating bodies connected together. This will be described in detail below with reference to the drawings.

Figure 1 shows the drive circuit of the vibration actuator of the first embodiment. 1, 2, and 3 are vibrators, 5, 6, and 7 are transformers with primary inductors connected in series, and the areas surrounded by dotted lines where vibrators 1, 2, and 3 are connected in parallel to the secondary sides of transformers 5, 6, and 7 respectively, show the internal circuit of vibration actuator 10 as a vibration body unit. The inductance value of the secondary coil of the transformer connected in parallel to each vibrator is matched at a predetermined frequency close to the resonant frequency of vibration actuator 10.

That is, when the matching frequency is F ₀ , the damping capacitance value is C ₀ , and the inductance value of the secondary coil of the transformer is L ₀ , the relationship between them is expressed by Equation 1.

１２は周波数指令に応じたパルス信号を出力する矩形電圧生成手段であり、インダクタとコンデンサの直列回路で構成される波形整形手段１１を介して駆動電圧を振動型アクチュエータ１０に出力している。１３は振動型アクチュエータ１０に流れる電流を計測する為の抵抗で、振動体１、２、３の振動速度に比例した電圧を出力する。したがって振動型アクチュエータ１０の全体を代表した電圧の値を抵抗１３の出力から検出できる。

Reference numeral 12 denotes a rectangular voltage generating means that outputs a pulse signal according to a frequency command, and outputs a drive voltage to the vibration actuator 10 via a waveform shaping means 11 that is composed of a series circuit of an inductor and a capacitor. Reference numeral 13 denotes a resistor for measuring the current flowing through the vibration actuator 10, and outputs a voltage proportional to the vibration speed of the vibrating bodies 1, 2, and 3. Therefore, a voltage value representing the entire vibration actuator 10 can be detected from the output of the resistor 13.

To be precise, the amplitude of the vibrating body is proportional to the value obtained by integrating this vibration velocity with respect to time, but since the amplitude of the vibration velocity is roughly proportional to the vibration amplitude, in the following examples, the vibration amplitude is controlled by controlling the amplitude of the vibration velocity signal.

14 is an amplitude detection means for detecting the amplitude of the vibration velocity signal detected by resistor 13, and 15 is a known CPU that outputs a vibration amplitude command for vibration actuator 10 in response to a command from a command means (not shown). 16 is an amplitude comparison means for comparing the vibration amplitude command with the output of amplitude detection means 14, and 17 is an amplitude control means for outputting a frequency command to rectangular voltage generation means 12 in response to the output of amplitude comparison means 16. 18 is a drive signal analysis means for analyzing the waveform of the drive voltage for vibration actuator 10, and CPU 15, which is a control unit, outputs a command signal such as an ON-OFF command in response to the waveform analysis result of drive signal analysis means 18. Based on this command signal, the drive unit outputs a drive signal to a vibration body unit in which two or more vibration bodies are connected.

The CPU 15, which is the control unit, outputs command signals such as ON-OFF commands to the rectangular voltage generating means 12, which is the drive unit, and controls the operation of the vibration actuator 10, such as driving and stopping.

The vibrator unit illustrated in FIG. 1 has a configuration in which vibrators are connected in parallel to the secondary sides of multiple transformers whose primaries are connected in series, and the primary sides of the multiple transformers are configured to be applied with the drive signal. In addition, it is equipped with a waveform shaping means inserted between the rectangular voltage generating means and the vibrator unit.

In this way, two or more vibrating bodies are connected together to form a vibration actuator 10 as a vibrating body unit, and each vibrating body is configured to be driven by a common command signal issued by the CPU 15 as a control unit.

Here, a first example of a vibration type actuator of this embodiment is shown. Figure 2 shows the structure of a vibration type actuator in which three vibrators are brought into contact with the outer circumference of a cylindrical shaft to rotate the cylindrical shaft. 1, 2, and 3 are vibrators that vibrate in the vertical direction (direction of the arrow), and 4 is a cylindrical shaft. In this embodiment, vibrators 1, 2, and 3 are arranged approximately evenly every 120° on the circumference of cylindrical shaft 4. By exciting vibrations in the vertical direction by vibrating vibrators 1, 2, and 3, cylindrical shaft 4 rotates clockwise. The cylindrical shaft corresponds to a common contact body that contacts a vibrator unit in which two or more vibrators are connected, and moves relative to the vibrators in the direction of the resultant force generated by driving vibrators 1, 2, and 3.

Figure 3 is a diagram showing the electrical connections within the vibration actuator 10. 5, 6, and 7 are transformers, and the secondary coils of the transformers 5, 6, and 7 are connected in parallel to the piezoelectric bodies joined to the vibrating bodies 1, 2, and 3. 8 is a connector for inputting AC voltage to the vibration actuator 10, which connects the primary coils of the transformers 5, 6, and 7 in series, with both ends connected. 9 is a donut-shaped hollow case that contains the vibrating bodies, and these are integrated to form the vibration actuator 10, which is made up of multiple vibrating bodies connected together.

The vibrators 1, 2, and 3 have protrusions that are in pressure contact with the cylindrical shaft 4 every 120° in the hollow cylindrical section through which the cylindrical shaft 4 of the case 9 passes, and are pressed against the cylindrical shaft 4 with a constant pressure force by a support member including a spring structure (not shown). Next, the operation of the CPU 15 will be described. The CPU 15 outputs a command signal related to the vibration amplitude based on a table of vibration amplitudes corresponding to the speed command in response to a speed command from a command means (not shown). During driving, the analysis results of the drive signal analysis means 18 are periodically monitored, and if the analysis results are outside a predetermined range, it is determined that one of the vibrators 1, 2, and 3 has broken, and the vibration amplitude command is set to 0 to stop the vibration type actuator. Furthermore, the CPU 15 may operate to notify a command means (not shown) of the breakage when stopping.

Next, the operation of the drive signal analysis means 18 will be described. Figure 4 shows the change in frequency characteristics of the drive voltage amplitude when the connection of the vibrating body of the vibration actuator 10 is broken. Assuming that the rectangular voltage generation means 12 outputs a drive signal that is a sinusoidal voltage signal, the frequency is swept and the amplitude of the drive voltage is measured. The drive frequency range of the vibration actuator 10 in this embodiment is approximately between 93 kHz and 98 kHz.

In Fig. 4, the solid line indicates no breakage, the dashed line indicates a breakage in the wiring connected to one of the vibrators, the dashed line indicates a breakage in the wiring connected to each of the two vibrators, and the dotted line indicates a breakage in the wiring connected to each of all the vibrators. In Fig. 4, _F1 indicates the fundamental frequency of a certain driving voltage waveform within the frequency range used in normal driving, _F2 indicates the frequency of its second harmonic, and _F3 indicates the frequency of its third harmonic. Comparing the voltage amplitudes of each order in Fig. 4, it can be seen that the ratio of the amplitudes between the orders differs depending on the number of breakages, and the waveform changes. In addition, since the frequency _F3 of the third harmonic of the driving voltage is near the frequency (around 310 kHz) at the lowest point of the valley of the frequency characteristic when there is no breakage, the amplitude of the third harmonic changes significantly when a breakage occurs, which makes the waveform change large when a breakage occurs.

Figure 5 shows the change in the waveform of the drive voltage. Figure 5(a) shows the case where the rectangular voltage generating means 12 outputs a pulse signal with a duty of 50%, and Figure 5(b) shows the case where the rectangular voltage generating means 12 outputs a pulse signal with a duty of 38%. The solid line shows the case where there is no break, the dashed line shows the case where one vibrator is broken, the dashed line shows the case where two vibrators are broken, and the dotted line shows the case where all are broken.

In both Figures 5(a) and 5(b), when a break occurs, part of the smooth waveform changes to abrupt and a square wave is superimposed. It can also be seen that as the number of breaks increases, the steepness of the waveform increases while the amplitude decreases, and the proportion of superimposed square wave components increases.

Figure 6 shows an example of the waveform analysis results of the drive signal analysis means 18 when the duty of the pulse signal output by the rectangular voltage generation means 12 is 50%. Figures 6(a) and (b) are graphs calculated based on the "average absolute value" and effective value of the drive voltage when the frequency of the drive voltage is changed. Figure 6(a) shows the result of the form factor ("average absolute value"/effective value), and Figure 6(b) shows the result of effective value - "average absolute value".

The closer the effective value of an AC signal is to a square wave, the closer it approaches the "average absolute value" of the AC signal. Therefore, as the number of breaks increases and the superimposed square wave components increase, the form factor approaches 1, and the effective value - the "average absolute value" decreases.

The waveform analyzed in this manner may be a waveform of the average absolute value of the drive voltage relative to the frequency of the drive voltage, or a waveform of the effective value of the drive voltage relative to the frequency of the drive voltage.

6(c) and (d) are graphs calculated from the amplitude of the harmonics of the drive voltage. FIG. 6(c) is a graph showing the total harmonic distortion (the value obtained by dividing the amplitude of high-frequency components (harmonic components) other than the fundamental wave by the amplitude of the fundamental wave) for evaluating the degree of high-frequency components, and FIG. 6(d) is a graph showing the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave. Methods for measuring the amplitude of the fundamental wave and the harmonics include the well-known method of using FFT (fast Fourier transform) as well as the following methods. That is, there are a method of using a low-pass filter to separate the fundamental wave and the high-frequency components (harmonic components) and measure their respective amplitudes, and a method of extracting a specific order of harmonics using a band-pass filter and measuring the amplitude. In addition, in this embodiment, the waveform was analyzed using the drive signal analysis means 18, but the time-series waveform of the drive voltage may be read into the CPU 15 using an A/D converter (not shown) and the waveform may be analyzed using calculations such as FFT. In this case, the sampling frequency of the A/D converter can be lowered by attenuating the fifth and higher harmonics with a low-pass filter before inputting the signal to the A/D converter. Since the third and lower harmonics have a large effect on the change in waveform, it is desirable to perform sampling at a sampling frequency sufficient to detect the third harmonic (for example, a frequency 12 times or higher than the fundamental wave). In this way, analysis can be performed from the waveforms of the amplitude of the third harmonic and the amplitude of the fundamental wave relative to the frequency of the drive voltage.

According to the frequency characteristics of the drive voltage amplitude in FIG. 4, the second and higher harmonic components of the square wave increase almost entirely due to breakages, so the harmonic distortion factor and the value obtained by dividing the amplitude of the third harmonic (frequency near _F3 ) by the amplitude of the fundamental wave (frequency near _F1 ) increase as the number of breakages increases.

The threshold value for determining whether or not there is a break is shown by the long-dash line in each of the graphs in Figures 6(a), (b), (c), and (d). By using this threshold value, it is possible to determine whether or not there is a break from the results of each waveform analysis calculation, regardless of the frequency at which the device is being driven, from 94 kHz to 97 kHz.

Figure 7 shows an example of the waveform analysis results of the drive signal analysis means 18 when the duty of the pulse signal output by the rectangular voltage generation means 12 is 38%. Figures 7(a) and (b) are graphs calculated based on the "average absolute value" and effective value of the drive voltage when the frequency of the drive voltage is changed. Figure 7(a) shows the form factor ("average absolute value"/effective value), and Figure 7(b) shows the result of effective value - "average absolute value". Figures 7(c) and (d) are graphs calculated from the amplitude of the harmonics of the drive voltage. Figure 7(c) shows the total harmonic distortion (the value obtained by dividing the amplitude of high-frequency components (harmonic components) other than the fundamental wave by the amplitude of the fundamental wave), and Figure 7(d) shows the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave.

The analysis results in Figures 7(a) and (b) show a uniform increase or decrease due to the break, but the results for break 0 and break 1 are close to each other, and even if a threshold is set between them, the reliability of the break determination is low. The analysis results in Figures 7(c) and (d) show a sufficient gap between break 0 and break 1, making it relatively easy to determine whether or not there is a break.

Figure 8 is a graph based on Figure 6 showing the change in analysis results with respect to the number of breaks when the frequency when the duty of the pulse signal output by the rectangular voltage generating means 12 is 50% is fixed to a specified frequency. Figure 8(a) is the form factor, Figure 8(b) is the effective value - "average of absolute values", Figure 8(c) is the total harmonic distortion, and Figure 8(d) is the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave. In the frequency range from 94 kHz to 97 kHz, each value changes roughly uniformly depending on the number of breaks as shown in Figure 8, so it is also possible to determine the number of breaks.

Figure 9 is a graph based on Figure 7 showing the change in the analysis results for the number of breaks when the frequency of the pulse signal output by the rectangular voltage generating means 12 with a duty of 38% is fixed to a specified frequency. Figure 9(a) is a graph showing the form factor, Figure 9(b) is a graph showing the effective value - "average of absolute values", Figure 9(c) is a graph showing the total harmonic distortion, and Figure 9(d) is a graph showing the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave.

As explained in Figure 7, the analysis results in Figures 9(a) and (b) show a uniform increase or decrease due to the number of breaks, but the results for the number of breaks are close to each other, so there is a possibility that the error in determining the number of breaks will be large. The analysis results in Figures 9(c) and (d) show that there is a sufficient gap between breaks 0 and 1, so it is possible to determine the number of breaks in the same way as with a duty of 50%.

The reason why there is such a large difference between the analysis results for a duty of 50% and a duty of 38% is because the amplitude ratio of the second and third harmonics of the pulse signal is different. The frequency characteristics of the drive voltage amplitude in Figure 4 show large changes in characteristics due to disconnections around the frequencies of the second and third harmonics, so the difference in the amplitude ratio of the second and third harmonics of the pulse signal affects the difference in the analysis results. As the analysis results change depending on the drive conditions (duty and drive frequency), in applications where the drive conditions change, it is effective to switch the waveform analysis method depending on the drive conditions.

Figure 10 shows a configuration in which the waveform shaping means 11 of the drive circuit of the vibration actuator in Figure 1 is replaced with a waveform shaping means 19 consisting of an inductor only. The operation of the CPU 15 is the same as in the above example, but the change in the frequency characteristics of the amplitude of the drive voltage when the vibrating body of the vibration actuator 10 is broken is different, so the analysis results of the drive signal analysis means 18 are different.

Figure 11 shows the change in the frequency characteristics of the amplitude of the drive voltage when the connection of the vibrating body of the vibration actuator 10 in the drive circuit of the vibration actuator of Figure 10 is broken.

Because the waveform shaping means does not have a capacitor for cutting DC, the frequency characteristics of the drive voltage amplitude in the low frequency range are increased compared to the characteristics in Figure 4.

FIG. 12 shows an example of the waveform analysis result of the drive voltage by the drive signal analysis means 18 when the duty of the pulse signal output by the rectangular voltage generation means 12 is 50%. FIG. 12(a) is a graph showing the form factor, FIG. 12(b) is the effective value - "average of absolute values", FIG. 12(c) is a graph showing the total harmonic distortion (the value obtained by dividing the amplitude of the harmonic components other than the fundamental wave by the amplitude of the fundamental wave), and FIG. 12(d) is a graph showing the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave. In the graph of FIG. 11, the characteristics other than the break 3, which is all broken, have little amplitude change in the high frequency range (frequencies of _F2 or more). On the other hand, the amplitude increases as the frequency approaches 90 kHz to 100 kHz, so the closer the frequency of the fundamental wave (near _F1 ) is to 100 kHz, the less the change in the waveform due to breakage. Therefore, the analysis results of FIG. 12(a), (c), and (d) show that the higher the frequency, the less the change in break 0, break 1, and break 2.

The analysis results in Figure 12 show that changes due to breaks are small around 97 kHz, but each value changes uniformly depending on the number of breaks. Therefore, by measuring the characteristics of the amplitude of the drive voltage generated by breaks in advance and preparing each analysis result as a comparison table for each frequency, it is possible to determine whether breaks exist and how many breaks there are.

Figure 13 shows a third example of a drive circuit for a vibration actuator in a different configuration. In the above example, transformers 5, 6, and 7 were connected in parallel to vibrators 1, 2, and 3 to form vibration actuator 10. In this example, inductors 20, 21, and 22 are connected in parallel to vibrators 1, 2, and 3, and vibrators 1, 2, and 3 are connected in series to form vibration actuator 23 as a vibrator unit. In other words, a pair of inductors and vibrators connected in parallel constitutes the vibrator unit, with multiple pairs connected in series.

The operation of each part is the same as in the above example, so only the operation of the drive signal analysis means 18 will be explained.

Figure 14 shows the change in frequency characteristics of the amplitude of the drive voltage when the connection of the vibrating body of the vibration actuator 23 is broken. As explained above, the frequency was swept and the amplitude of the drive voltage was measured, assuming that the rectangular voltage generating means 12 outputs a sine wave.

The solid line indicates no breaks, the dashed line indicates one vibrator breaks, the dashed line indicates two vibrators breaks, and the dotted line indicates all breaks. _F1 indicates the fundamental frequency of a certain drive voltage waveform used in normal driving, _F2 indicates the frequency of the second harmonic, and _F3 indicates the frequency of the third harmonic.

Figure 15 shows an example of the waveform analysis results of the drive signal analysis means 18 when the duty of the pulse signal output by the rectangular voltage generation means 12 is 50%. Figure 15(a) is a graph showing the form factor, Figure 15(b) is the effective value - "average of absolute values", Figure 15(c) is a graph showing the total harmonic distortion (the amplitude of harmonic components other than the fundamental wave divided by the amplitude of the fundamental wave), and Figure 15(d) is a graph showing the amplitude of the third harmonic divided by the amplitude of the fundamental wave. Since the gap between break 0 and break 1 is large in each analysis result, it is easy to determine whether or not there is a break. The long-dash line in each graph is the threshold value for determining whether there is a break.

Figure 16 shows an example of the waveform analysis result of the drive voltage by the drive signal analysis means 18 when the duty of the pulse signal output by the rectangular voltage generation means 12 is 38%. Figure 16(a) is a graph showing the form factor, Figure 16(b) is the effective value - "average of absolute values", Figure 16(c) is the total harmonic distortion (the value obtained by dividing the amplitude of the harmonic components other than the fundamental wave by the amplitude of the fundamental wave), and Figure 16(d) is a graph showing the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave. The characteristics other than the total harmonic distortion in Figure 16(c) are the same as those in the case of a duty of 50% in Figure 15, except that the gap between the number of breaks is narrower, making it easy to determine whether or not there is a break. However, the order of break 0 and break 1 is reversed in the total harmonic distortion in Figure 16(c) compared to Figure 15(c). A decrease in the total harmonic distortion indicates that the high frequency components are reduced relative to the fundamental wave components, and the characteristics in Figure 16(c) show that the high frequency components of the drive voltage are reduced by break 1. Therefore, to determine the presence or absence of a break using the total harmonic distortion in Figure 16(c), two thresholds, large and small, are required, as shown by the two long-dash lines in the figure. Also, since there is no intersection between the graphs of the number of breaks in the range of 94 kHz to 97 kHz with any of the analysis methods in Figure 16, it is possible to determine the presence of a break by creating a comparison table in advance of the analysis results of the drive voltage waveform due to breaks and making a judgment based on that.

The above explanation shows that the effect of a break on the drive voltage waveform differs depending on the circuit, duty cycle, and drive frequency. The explanation in Figure 16 shows that even when a break occurs, the high-frequency components may decrease, and that depending on the drive conditions, a break cannot be determined simply by the presence or absence of high-frequency components. It also shows that if a comparison table is created in advance of the analysis results of the drive voltage waveform due to a break, a break can be determined by using the frequency command, the analysis results, and the comparison table to make a judgment based on that.

In addition, in the above explanation, a method for determining whether a wire is broken was explained using four examples of waveform analysis methods, but any calculation method or measurement method in which the output changes depending on the waveform can be used. For example, a wire break causes a steep waveform to appear, and the magnitude changes depending on the number of breaks, so the maximum value of the change in drive voltage per unit time can be used. It is also possible to determine whether a wire is broken based on the harmonic amplitude of a specific order.

In the above explanation, a pulse signal output from the rectangular voltage generating means 12 is used as the drive voltage, but other waveforms may also be used. Even triangular waves, sawtooth waves, and PWM modulated waves output from known class D amplifiers can be used to detect breaks, as long as they contain many relatively low-order harmonics of the fifth order or less, because the change in waveform due to a break is relatively large.

In this way, the drive signal analysis means analyzes the waveform of the output voltage or output current of the waveform shaping means, and detects a value corresponding to any one of the following: form factor, harmonic distortion, difference between the effective value and the average of the absolute value, and harmonic amplitude. Although it is preferable to have a waveform shaping means, it is not essential and direct signal processing may be used.

Figure 17 is a diagram showing the drive circuit of the vibration actuator of the second embodiment. In the vibration actuator of the above embodiment, vibrators 1, 2, and 3 are connected in parallel with transformers 5, 6, and 7, but in this embodiment, matching adjustment capacitors 24, 25, and 26 are additionally connected in parallel. The operation of each part is the same as in the first embodiment, so the explanation is omitted, and the analysis of the drive voltage waveform and the determination of disconnection will be explained.

The capacitors connected in parallel to each vibrating body are capacitors for adjusting the matching frequency, and the capacitance value _C1 of the capacitor is expressed by the following equation 2, where the matching frequency is _F0 , the damping capacitance value is _C0 , and the inductance value of the secondary coil of the transformer is _L0 .

トランスの２次側コイルのインダクタンス値Ｌ_０や制動容量値Ｃ_０の値はバラツキが大きいので、マッチング調整用コンデンサ（静電容量値Ｃ_１）を並列に接続することでマッチング周波数Ｆ_０を揃えるようにしている。

Since there is a large variation in the inductance value _L0 and the damping capacitance value _C0 of the secondary coil of the transformer, a matching adjustment capacitor (capacitance value _C1 ) is connected in parallel to make the matching frequency _F0 uniform.

Next, we will explain the difference from the above embodiment in the drive voltage waveform when the vibrator is disconnected. In terms of circuit configuration, in the above embodiment, when the connection of the vibrator is disconnected, the electrostatic capacitance component connected in parallel to the transformer or inductor connected in parallel to the vibrator disappears, whereas in this embodiment, the connection of the matching adjustment capacitor remains. Therefore, a parallel resonance system between the transformer and the matching adjustment capacitor appears due to the disconnection, and the effect of this appears in the drive voltage waveform.

Figure 18 shows the change in frequency characteristics of the amplitude of the drive voltage when the connection of the vibrator of the vibration actuator 27 in Figure 17 is broken. Assuming that the rectangular voltage generating means 12 outputs a sine wave, the frequency is swept and the amplitude of the drive voltage is measured.

The solid line indicates no breakage, the dashed line indicates one vibrator breakage, the dashed line indicates two vibrators breakage, and the dotted line indicates all breakages. _F1 indicates the fundamental frequency of a certain drive voltage waveform used in normal driving, _F2 indicates the frequency of the second harmonic, _F3 indicates the frequency of the third harmonic, and _F4 indicates the frequency of the fourth harmonic. The peak characteristics between the third harmonic frequency _F3 and the fourth harmonic frequency _F4 are the influence of the parallel resonance of the matching adjustment capacitor and the transformer caused by the breakage of the vibrator. In addition, since the frequency _F3 of the third harmonic of the drive voltage is near the lowest frequency (around 310 kHz) of the valley of the frequency characteristic when there is no breakage, the amplitude of the third harmonic changes significantly when the breakage occurs, which makes the waveform change large when the breakage occurs.

Figure 19 shows the drive voltage waveform when the rectangular voltage generating means 12 outputs a pulse signal with a duty of 50%. The solid line indicates no breaks, the dashed line indicates one vibrator break, the dashed line indicates two vibrators break, and the dotted line indicates all breaks. It can be seen that when breaks occur, the sine wave approaches a rectangular wave as the number of breaks increases.

FIG. 20 shows an example of the waveform analysis result of the drive voltage by the drive signal analysis means 18 when the duty of the pulse signal output by the rectangular voltage generation means 12 is 50%. FIG. 20(a) is a graph showing the form factor, FIG. 20(b) is the effective value - "average of absolute values", FIG. 20(c) is the total harmonic distortion factor (the value obtained by dividing the amplitude of the harmonic components other than the fundamental wave by the amplitude of the fundamental wave), and FIG. 20(d) is a graph showing the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave. In all the waveform analysis results in FIG. 20, the gap between break 0 and break 1 is wide, making it easy to determine whether or not there is a break. The long chain line in FIG. 20 indicates the threshold value for determining whether or not there is a break while the vibration actuator 27 is being driven. The reason why the gap is wide is that the frequency characteristic of the drive voltage amplitude in FIG. 18 changes greatly depending on the presence or absence of a break near the third harmonic (F ₃ ) due to the influence of the parallel resonance of the matching adjustment capacitor and the transformer. In this way, by setting the frequency of the parallel resonance formed by the matching adjustment capacitor and the transformer near the low-order harmonic of the pulse signal, it is possible to easily determine whether or not there is a break in the wire.

As in the above embodiment, by measuring the characteristics of the amplitude of the drive voltage generated by a break in advance and creating a comparison table of the analysis results, it is possible to determine the presence or absence of a break in the drive voltage and the number of breaks by using the analysis results and the comparison table while the vibration actuator 27 is being driven.

Figure 21 is a diagram showing a second example of the drive circuit of the vibration type actuator of the second embodiment. In the example shown in Figure 17, the transformers 5, 6, 7 and the matching adjustment capacitors 24, 25, 26 are connected in parallel to the vibrating bodies 1, 2, 3, while the inductors 20, 21, 22 and the matching adjustment capacitors 24, 25, 26 are connected in parallel to the vibrating bodies 1, 2, 3. The matching adjustment capacitors 24, 25, 26 are mounted adjacent to the inductors 20, 21, 22 on a circuit board (not shown), and the vibrating bodies 1, 2, 3 are connected to this circuit board by a flexible board via a connector. In applications where the flexible board is repeatedly bent or folded, the risk of breakage of the flexible board increases.

The capacitance value _C1 of the matching adjustment capacitor is expressed by the following equation 2, where _F0 is the matching frequency, _C0 is the damping capacitance, and _L0 is the inductance of the inductor. The parallel-series circuit of the vibrators 1, 2, 3, the inductors 20, 21, 22, and the matching adjustment capacitors 24, 25, 26 constitutes a vibration actuator 28, to which a pulse signal from a rectangular voltage generating means 12 is applied via a waveform shaping means 11. The current flowing through the vibration actuator 28 is converted into a voltage signal by a resistor 13, and input to an amplitude detecting means 14. The operation of each part is the same as in the first embodiment, so a description thereof will be omitted.

Furthermore, as the number of vibrating bodies connected in series increases, so does the risk of improper insertion of connectors during manufacturing. Improper insertion is also a type of disconnection, and the analysis result changes from disconnection 0 to disconnection 1 during the period from poor contact to the connector completely falling off (disconnection). During this change, the analysis result crosses the threshold, making it possible to detect improper insertion of connectors, etc.

In addition, in the above explanation, four waveform analysis methods were used, but any method in which the output changes depending on the waveform can be used.

In the above explanation, a pulse signal output from the rectangular voltage generating means 12 is used as the drive voltage, but other waveforms may also be used. Even triangular waves, sawtooth waves, and PWM modulated waves output from known class D amplifiers can be used to detect breaks, as long as they contain many relatively low-order harmonics of the fifth order or less, because the change in waveform due to a break is relatively large.

Figure 22 shows the configuration of the vibrator used in Example 3. In Figure 22(a), 48 is a rectangular elastic body made of a conductive material, and has two protrusions on its surface that come into contact with the contact body. 49 is a piezoelectric body that forms part of elastic body 48 and vibrates it. Figure 22(b) shows electrodes provided on piezoelectric body 49, and electrodes 31 and 32 are electrically insulated from each other, and two AC voltages whose phases change independently are applied to them. The entire back surface of piezoelectric body 49 is an electrode, and it is configured so that electricity can be passed from the front surface through vias (not shown) provided in parts of electrodes 31 and 32.

Figure 23 is a diagram showing the vibration modes of elastic body 48. Figure 23(a) shows the vibration form of the vibration mode (thrust vibration mode) excited when an AC voltage of the same phase is applied to electrodes 31 and 32, and Figure 23(b) shows the vibration form of the vibration mode (feed vibration mode) excited when an AC voltage of the opposite phase is applied.

That is, when the phase difference of the applied AC voltage is 0°, the mode in FIG. 23(a) is excited, and when the phase difference is 180°, the mode in FIG. 23(b) is excited. Also, when the phase difference of the AC voltage is between 0° and 180° (in practice, a range of about 0° to 120° is used), both vibration modes are excited simultaneously, and the contact body that is in pressure contact with the protrusion provided on the elastic body 48 moves in the longitudinal direction of the rectangle of the elastic body 48.

Figure 24 shows the configuration of the linear vibration actuator of this embodiment. Specifically, the protrusions of the vibrating bodies 36 and 37 are arranged facing each other on the top and bottom, and five sets of vibrating bodies are arranged in a straight line in the same way up to vibrating body 38 in top and bottom pairs, so that a total of ten vibrating bodies are configured to move in the direction of the arrows from above and below, sandwiching a common contact body 50.

Figure 25 is a diagram showing the drive circuit of the vibration type actuator of the third embodiment. The vibration type actuator of the first and second embodiments has three vibrating bodies and one phase of the drive voltage, but in this embodiment, the number of vibrating bodies is ten and is driven by a two-phase drive voltage. The ten vibrating bodies 36, 37, ..., 38 are connected to a ground potential by conductive elastic bodies (not shown).

The vibrating body 36 is provided with electrodes 30, 31 provided on the piezoelectric body 49, and is connected in parallel to the transformers 32, 33 together with the matching adjustment capacitors 34, 35. The primary side of the nine transformers 52, ..., 53 are connected in series to the primary side of the transformer 32, and one electrode of the nine vibrating bodies 37, ..., 38 is connected in parallel to each of the secondary sides of the transformers 52, ..., 53. Similarly, the primary sides of nine transformers 54, ..., 55 are connected in series to the primary side of the transformer 33, and the other electrodes of the nine vibrating bodies 37, ..., 38 are connected in parallel to each of the secondary sides of the transformers 54, ..., 55. In addition, matching adjustment capacitors are connected in parallel to the ten vibrating bodies 36, 37, ..., 38 together with the transformers, and the ten units consisting of these vibrating bodies, matching adjustment capacitors, and transformers connected in series constitute the vibration type actuator 51.

40 is a rectangular voltage generating means that outputs a two-phase pulse signal, and applies the drive voltage to the vibration actuator 51 via waveform shaping means 11, 39, which are composed of a series circuit of an inductor and a capacitor. 41 and 42 are resistors for measuring the two-phase currents flowing through the vibration actuator 51, and detect voltages proportional to the vibration speeds of the vibrating bodies 36, 37, ..., 38.

43 is an A/D converter for detecting the vibration velocity detected by resistors 41 and 42, and inputs two-phase current signals (CurA, CurB) to the CPU 15 as time-series data. The CPU 15 determines and outputs a position command, a pulse width command, and a frequency command based on a position command from a command means (not shown), the two-phase current signal from the A/D converter 43, and the analysis results of a drive signal analysis means 47 (described later). The pulse width command and frequency command are input to the rectangular voltage generation means 40, which sets the frequency and pulse width of the two-phase pulse signal to be output. A detailed explanation of the operation of the CPU 15 will be given later.

45 is a known linear encoder for detecting the position of the common contact body 50, and 46 is a position comparison means for outputting the difference between the position command from the CPU 15 and the position signal output by the linear encoder 45. 44 is a position control means for outputting a phase difference command to the rectangular voltage generation means 40 according to the output of the position comparison means 46, and controls the moving direction and speed of the contact body 50 by setting the phase difference of the above-mentioned two-phase pulse signals. 47 is a drive signal analysis means for analyzing the waveforms of the two-phase drive voltages of the vibration type actuator 51, performing waveform analysis of each of the two-phase drive voltages, and outputting the analysis results.

FIG. 26 shows the change in frequency characteristic of the amplitude of the driving voltage when the connection of the vibrating body of the vibration actuator 51 in FIG. 25 is broken. The frequency is swept and the amplitude of the driving voltage is measured assuming that the rectangular voltage generating means 40 outputs a sine wave. The solid line shows the characteristic when there is no break, and the dotted line shows the characteristic when the number of breaks is 1 to 10. _F1 shows the fundamental frequency of a certain driving voltage during normal driving, and _F2 , _F3 , _F4 , and _F5 show the frequencies of the harmonics from the second to the fifth order. Comparing the voltage amplitude of the frequencies of the harmonic orders in FIG. 26, it can be seen that the ratio of the amplitude between the orders differs depending on the number of breaks, and the waveform changes. In particular, it shows that the change in the amplitude of the driving voltage depending on the presence or absence of a break is large near the frequency ( _F3 ) of the third harmonic. In addition, since the frequency _F3 of the third harmonic of the drive voltage is close to the frequency (near 290 kHz) of the lowest point of the valley of the frequency characteristic when there is no breakage, the amplitude of the third harmonic changes significantly when there is a breakage, which makes the change in the waveform when there is a breakage large.

Figure 27 shows the change in the waveform of the drive voltage. The solid line indicates no breaks, the dashed line indicates one vibrator break, the dashed line indicates two vibrators break, and the dotted line indicates all breaks. When a break occurs, the peak of the sine wave collapses, and it can be seen that the sine wave approaches a square wave as the number of breaks increases.

Figure 28 shows an example of the waveform analysis results of the drive voltage by the drive signal analysis means 47 when the duty of the pulse signal output by the rectangular voltage generation means 40 is 50%. Figure 28(a) shows the form factor (average of absolute values/effective value), Figure 28(b) shows the effective value - (average of absolute values), Figure 28(c) shows the total harmonic distortion, and Figure 28(d) shows the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave.

In all of the waveform analysis results in Figure 28, the gap between break 0 and break 1 is wide, making it easy to determine whether or not a break has occurred. The long-dash line in Figure 28 indicates the threshold value for determining whether or not a break has occurred while the vibration actuator 51 is in operation. It can be seen that even if only one of the ten vibrators is broken, it is still possible to determine whether or not a break has occurred.

Now, the detailed operation of the CPU 15 will be explained using a flowchart. The CPU 15 controls the vibration amplitude based on the two-phase current signal from the A/D converter 43, and controls operations such as driving and stopping the vibration actuator 51 based on the waveform analysis results of the drive signal analysis means 47. First, the operations such as driving and stopping the vibration actuator 51 based on the waveform analysis results will be explained.

The control method for the vibration type drive device according to this embodiment is as follows. That is, the control unit outputs a command signal to the drive unit, and the drive signal output by the drive unit causes a vibrator unit, which is made up of two or more connected vibrators, to vibrate. At the same time, the drive signal is analyzed and the analysis result is output, and based on the analysis result, it is determined whether or not there is a break in the wiring connected to the vibrators.

FIG. 29 is a flowchart showing an example of the operation of the CPU 15 which executes different drive sequences of the vibration actuator 51 depending on the result of the disconnection. The sequence of the position control operation of the contact body 50 is shown, and different operation sequences are selected depending on the number of disconnections (N). Each operation sequence will be explained using the flowchart. The position control operation starts when a new position command POS_C is input from a command means (not shown). First, the number of disconnections N of the vibrator that have occurred up to that point is confirmed. If the number of disconnections N is 2 or more, the disconnection state display LED is turned on in red and the position control operation ends. If the number of disconnections N is 1 or less, in order to generate a drive voltage to be applied to the vibration actuator 51, the pulse width command PW_C is set to a predetermined pulse width PW0 and the frequency command Frq is set to an initial frequency _F0 . Then, the amplitude command AMP_C is set to a predetermined amplitude AMP0, and the drive timer T is initialized to 0. Then, a pulse signal is output from the rectangular voltage generating means 40, and the movement of the vibration actuator 51 starts. Next, waveform analysis, disconnection determination, and vibration amplitude control are performed. Details of the vibration amplitude control will be described later. If the number of breaks N determined by the breakage judgment is 0, the breakage state display LED is lit in green, and waveform analysis, breakage judgment, and vibration amplitude control are repeated until the drive timer T reaches T1 or the number of breaks N reaches 1 or more. If the position command POS_C is updated from a command means (not shown) during this time, the drive timer T is initialized to 0, and waveform analysis, breakage judgment, and vibration amplitude control are repeated until the drive timer T reaches T1. When the drive timer T reaches T1, the pulse width command PW_C is set to 0, and the vibration amplitude command AMP_C is also set to 0, ending the position control operation.

If the number of breaks N becomes 1 or more before the drive timer T reaches T1, different operations are executed depending on the number of breaks N. If the number of breaks N is 1, the LED for indicating the break state turns yellow and the same operation as when the number of breaks N is 0 continues. If the number of breaks N is 2, the LED for indicating the break state turns orange, the position command POS_C is not updated, but the same operation as when the number of breaks N is 0 continues until the drive timer T reaches T1. If the number of breaks N is 3 or more, the LED for indicating the break state turns red, the pulse width command PW_C is set to 0, the vibration amplitude command AMP_C is also set to 0, and the position control operation ends.

A vibration actuator with multiple vibrating body units connected in series, such as vibration actuator 51, may be able to continue driving even if some of the vibrating bodies are broken, so depending on the application, driving may continue. Also, even if the number of breaks is small, continuing driving can cause accumulated damage to the surrounding mechanisms, so even if driving is continued, measures such as prohibiting driving when the accumulated driving time exceeds a certain amount may be taken.

Next, we will explain the operations of waveform analysis, disconnection detection, and vibration amplitude control.

Figure 30 is a flowchart of the waveform analysis, breakage judgment, and vibration amplitude control operation. First, the two-phase time series current signals CurA(t) and CurB(t) input from the A/D converter 43 separately by interrupt processing are added to generate the signal Cur(t). This corresponds to the vibration speed (vibration amplitude) of the thrust-up vibration mode of the vibrator. Next, the first-order (fundamental wave) signal is extracted by low-pass filter calculation to obtain the first-order amplitude Amp(1). Next, the number of breakages in each of the two phases is obtained from the analysis results (e.g., form factor) based on the analysis method of Figure 28 input from the drive signal analysis means 47, and the total number of breakages N is obtained. Next, the vibration amplitude command Amp_C is compared with the first-order amplitude Amp(1), and if Amp(1) is smaller than Amp_C, the frequency is set lower by dF from the frequency command Frq. If Amp(1) is larger than Amp_C, the frequency is set higher by dF in the frequency command Frq. The frequency command is also limited to fall within the minimum frequency Frq_min and maximum frequency Frq_max.

In this way, the vibration amplitude of the thrust vibration mode of the vibration actuator 51 is controlled by the vibration amplitude command Amp_C, and the contact state between the contact body 50 and the vibrating body is maintained in a desired state. In this embodiment, the waveform analysis of the two-phase drive voltages is performed separately, but the waveform analysis may also be performed based on a signal to which the drive voltages are added.

In addition, in the above explanation, four waveform analysis methods were used, but any method in which the output changes depending on the waveform can be used.

In the above explanation, a pulse signal output from the rectangular voltage generating means 12 is used as the drive voltage, but other waveforms may also be used. Even triangular waves, sawtooth waves, and PWM modulated waves output from known class D amplifiers can be used to detect breaks, as long as they contain many relatively low-order harmonics of the fifth order or less, because the change in waveform due to a break is relatively large.

In the above embodiment, a break in the vibrating body of the vibration actuator is detected by analyzing the waveform of the drive voltage, but a break can also be detected by analyzing the waveform of the current flowing into the vibration actuator. Figure 31 shows a modification of the drive signal analysis means 47 of the drive circuit of the vibration actuator in Figure 25 to analyze the waveform of the terminal voltage of resistors 41 and 42 (current flowing into the vibration actuator) instead of the drive voltage. The operation of each part is the same as in Example 3, so the explanation will be omitted and the waveform analysis operation will be explained.

FIG. 32 shows the change in frequency characteristic of the amplitude of the terminal voltage (current flowing into the vibration actuator) of the resistor 41 or 42 when the connection of the vibrator of the vibration actuator 51 in FIG. 31 is broken. The solid line shows the characteristic when there is no break, and the dotted line shows the characteristic when the number of breaks is 1 to 10. _F1 shows the fundamental frequency of a certain drive voltage waveform during normal driving, and _F2 , _F3 , _F4 , and _F5 show the frequencies of the harmonics from the second to the fifth order. Comparing the amplitude of the inflow current at the frequency of each harmonic order in FIG. 32, it can be seen that the ratio of the amplitude between the orders differs depending on the number of breaks, and the waveform changes. In particular, the frequency ( _F3 ) of the third harmonic shows a large change in the inflow current amplitude depending on the presence or absence of a break. Compared to the characteristic of the drive voltage amplitude in FIG. 26, it is characteristic that the negative peak characteristic coincides regardless of the number of breaks near 310 kHz. This is caused by parallel resonance between the secondary side of the transformer connected in parallel with the vibrator and the matching adjustment capacitor.

Figure 33 shows an example of the results of waveform analysis of the current flowing into the vibration type actuator 51 by the drive signal analysis means 47 when the duty of the pulse signal output by the rectangular voltage generation means 40 is 50%. Figure 33(a) shows the form factor (average of absolute values/effective value), Figure 33(b) shows the effective value - (average of absolute values), Figure 33(c) shows the total harmonic distortion, and Figure 33(d) shows the value obtained by dividing the amplitude of the third harmonic by the amplitude of the fundamental wave.

It is possible to determine whether or not there is a break between break 0 and break 1 in all of the waveform analysis results in Figure 33, but since the analysis result values change significantly depending on the frequency, it is necessary to change the threshold for break determination depending on the drive frequency. It is necessary to measure the characteristics of the amplitude of the current flowing into the vibration actuator caused by a break in advance and create a comparison table of the analysis results. By doing so, it is possible to determine whether or not there is a break and the number of breaks using the analysis results and the comparison table while the vibration actuator 51 is being driven, as in the above embodiment.

The operation of the CPU 15, which controls the drive and stop in different sequences depending on the result of the disconnection, follows the flowchart in Figure 29 and is the same as described above, so a detailed explanation will be omitted.

Next, the operations of waveform analysis, disconnection judgment, and vibration amplitude control will be described. Figure 34 is a flowchart of the waveform analysis, disconnection judgment, and vibration amplitude control operations. First, the two-phase time series current signals CurA(t) and CurB(t) input from the A/D converter 43 separately by interrupt processing are added to generate a signal Cur(t). This corresponds to the vibration speed (vibration amplitude) of the thrust-up vibration mode of the vibrator. Next, the first (fundamental wave) and third harmonic signals are extracted by bandpass filter calculation to obtain the first amplitude Amp(1) and the third amplitude Amp(3). Next, Amp(3)/Amp(1) is obtained, and the number of disconnections N is obtained from the relationship between the frequency command Frq and the previously obtained relationship shown in Figure 31(d). Next, the vibration amplitude command Amp_C is compared with the first amplitude Amp(1), and if Amp(1) is smaller than Amp_C, the frequency is set lower by dF from the frequency command Frq. If Amp(1) is greater than Amp_C, the frequency command Frq is set to be dF higher. The frequency command is also limited to be within the minimum frequency Frq_min and maximum frequency Frq_max. In this way, the vibration amplitude of the thrust-up vibration mode of the vibration actuator 51 is controlled by the vibration amplitude command Amp_C.

In this way, this embodiment uses the current signal flowing through the vibration actuator 51 for both vibration amplitude control and disconnection analysis, making it possible to reduce the circuit size.

In this way, the analysis results are the result of analyzing the waveform of the driving voltage or the waveform of the current flowing into the vibrating body unit.

In addition, in the above explanation, four waveform analysis methods were used, but any method in which the output changes depending on the waveform can be used.

In the above explanation, a piezoelectric body is bonded to the vibrating body, but the vibrating body itself may be constructed of a piezoelectric body. The piezoelectric body may also be a laminated piezoelectric body.

The vibration type drive device described above can be applied to a variety of devices.

1, 2, 3, 36, 37, 38, 48 vibrator 4 cylindrical shaft 5, 6, 7, 32, 33, 52, 53, 54, 55 transformer 10, 23, 27, 28, 51 vibration actuator 11, 19 waveform shaping means 12, 40 rectangular voltage generating means 13, 41, 42 resistor 14 amplitude detecting means 15 CPU
16 Amplitude comparison means 17 Amplitude control means 18, 39, 47 Drive signal analysis means 20, 21, 22 Inductors 24, 25, 26, 34, 35 Matching adjustment capacitors 43 A/D converter 44 Position control means 46 Position comparison means 49 Piezoelectric body 50 Common contact body

Claims (18)

A control unit that outputs a command signal;
A drive unit that outputs a drive signal based on the command signal;
a vibrator unit including two or more vibrators arranged in series and vibrating based on the drive signal;
a drive signal analysis means for analyzing the drive signal and outputting an analysis result; and a determination means for determining whether or not a wire connected to the vibrating body is broken based on the analysis result,
The vibrator unit includes a plurality of transformers whose primary sides are connected in series, and the secondary sides of the transformers are connected in parallel to each other, and the primary sides of the transformers are configured to receive the drive signal,
the driving unit includes a rectangular voltage generating means for generating a pulse signal having a predetermined voltage and frequency, and a waveform shaping means inserted between the rectangular voltage generating means and the vibrator unit,
A vibration type driving device configured so that the frequency of the harmonics of the driving signal is near the lowest point of the valley of the frequency characteristic of the output voltage or output current of the waveform shaping means when the vibrator is not broken . A control unit that outputs a command signal;
A drive unit that outputs a drive signal based on the command signal;
a vibrator unit including two or more vibrators arranged in series and vibrating based on the drive signal;
a drive signal analysis means for analyzing the drive signal and outputting an analysis result; and a determination means for determining whether or not a wire connected to the vibrating body is broken based on the analysis result,
The vibrator unit includes a plurality of pairs of a pair of an inductor and a vibrator connected in parallel and connected in series,
the driving unit includes a rectangular voltage generating means for generating a pulse signal having a predetermined voltage and frequency, and a waveform shaping means inserted between the rectangular voltage generating means and the vibrator unit,
A vibration type driving device configured so that the frequency of the harmonics of the driving signal is near the lowest point of the valley of the frequency characteristic of the output voltage or output current of the waveform shaping means when the vibrator is not broken . The vibration type driving device according to claim 1 or 2, characterized in that the driving signal analysis means analyzes the waveform of the output voltage or output current of the waveform shaping means and detects a value corresponding to any one of the following: form factor, harmonic distortion factor, difference between the effective value and the average value of the absolute value, and harmonic amplitude. 4. The vibratory driving device according to claim 1 , wherein the waveform shaping means is a series circuit of an inductor and a capacitor or an inductor. The vibration type driving device according to claim 2, characterized in that a capacitor is further connected in parallel to the inductor. 2. The vibratory driving device according to claim 1 , further comprising a capacitor connected in parallel with a secondary side of said transformer. 7. The vibratory driving device according to claim 1, wherein the determining means determines the presence or absence of a disconnection based on a predetermined threshold value. 7. The vibratory driving device according to claim 1, wherein the determining means determines the number of breaks based on a table of analysis results previously obtained according to the number of breaks. 9. The vibratory driving device according to claim 1, further comprising a common contact body that is in contact with the vibrating body units. 10. The vibratory driving device according to claim 9 , wherein the contact body is a cylindrical shaft, and the vibrating body is provided with three vibrating bodies arranged approximately evenly around the circumference of the cylindrical shaft. The vibratory driving device according to claim 9 or 10 , further comprising a hollow case that houses the contact body and the vibrator. 12. The vibratory driving device according to claim 1, wherein the vibrator comprises a rectangular elastic body having two protrusions and a piezoelectric body. The control unit outputs a command signal to the drive unit, and a vibrator unit having two or more vibrators connected together vibrates in response to a drive signal output by the drive unit based on the command signal, and the drive signal is analyzed to output an analysis result.
the analysis result is a result of analyzing a waveform of a driving voltage or a waveform of a current flowing into the vibration body unit as the driving signal,
the waveform is a waveform of a third harmonic amplitude and a fundamental amplitude with respect to a frequency of the driving voltage,
A control method for a vibration type driving device, the control method determining whether or not there is a break in wiring connected to the vibrating body based on the analysis result. The vibrator unit is configured such that vibrators are connected in parallel to secondary sides of a plurality of transformers whose primary sides are connected in series, and the drive signal is applied to the primary sides of the plurality of transformers,
The control method for a vibratory driving device according to claim 13, wherein the driving unit comprises a rectangular voltage generating means for generating a pulse signal having a predetermined voltage and frequency, and a waveform shaping means inserted between the rectangular voltage generating means and the vibrating body unit. The vibrator unit is configured such that a pair of an inductor and a vibrator connected in parallel are connected in series to each other,
The control method for a vibratory driving device according to claim 13, wherein the driving unit comprises a rectangular voltage generating means for generating a pulse signal having a predetermined voltage and frequency, and a waveform shaping means inserted between the rectangular voltage generating means and the vibrating body unit. The method for controlling a vibratory driving device according to claim 13 , wherein a different driving sequence is executed depending on the number of breaks in wiring connected to the vibrating body in the vibrating body. The method for controlling a vibratory driving device according to claim 16 , further comprising the step of lighting an LED for indicating a disconnection state in accordance with the number of disconnections. An apparatus equipped with a vibration type driving device according to any one of claims 1 to 12.

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