JPH0241683A - Drive circuit for ultrasonic motor - Google Patents

Abstract

PURPOSE:To reduce the number of components by regulating a driving signal from driving signal generating means by level regulating means controlled by control means and by switch means, and supplying it to a piezoelectric element. CONSTITUTION:In a driving circuit of an ultrasonic motor, a mode selection switch 46 is connected to a system controller (sys-con) 45, and a corresponding signal is supplied thereto. The sys-con 45 supplies a control signal to variable resistors 52-53, switches 54-56 on the basis of a signal corresponding to a selected mode. A driving signal formed of a driving signal generator 47 is supplied to a variable resistor 52 and a phase shifter 58, phase-shifted by pi/2, and supplied to the resistor 53. A driving signal level-regulated by the resistor 52 is supplied to an A-phase piezoelectric element 60 through an amplifier 59 and the switch 54. Similarly, it is also supplied to a B-phase piezoelectric element 63, and a circuit configuration of a winding side is similarly composed, and supplied to piezoelectric elements 69-70.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ultrasonic motor drive circuit, particularly an ultrasonic motor drive circuit suitable for an electronic device having tape winding and rewinding functions such as a VTR. Regarding circuit Q.

[Summary of the invention]

This invention bends and vibrates the stator using a piezoelectric element,
In a drive circuit for an ultrasonic motor that rotationally drives a rotor by a traveling wave generated from this bending vibration, a drive signal generating means for generating a drive signal to be supplied to a piezoelectric element;
Ultrasonic This allows complex and diverse control operations to be performed on the motor.

(Prior Art) Electronic devices having tape winding and rewinding functions, such as VTRs and tape recorders, are provided with reel stands on the supply side and the winding side. Conventionally, each of these reels The drive of each reel stand was performed by a reel motor, and an electromagnetic motor was used as the reel motor.The drive of each reel stand was either direct drive without a gear/clutch mechanism, or one electromagnetic motor. It was either an indirect drive in which the output of the motor was reduced by multiple gears.

By the way, the above-mentioned reel motor is controlled by a drive circuit. By this drive circuit, the rotational speed of the reel motor is controlled to one of various speed modes such as FWD (record/play), fast forward, rewind, cue review play, reverse play, and stop. The reel motor is controlled by the above-mentioned drive circuit so that it can perform various operations such as take-up, feed (low speed/high speed), release, soft brake, lock brake, etc. in accordance with the operation mode of the VTR. .

[Problem to be solved by the invention]

With the reel motor mentioned above, the required torque cannot be obtained by direct drive, so in reality, the required torque can be obtained by connecting a complicated gear/clutch mechanism to the reel motor and gearing down the rotation of the reel motor. There are often As a result, there was a problem in that the number of parts became enormous. Furthermore, since the number of parts is enormous, there is a problem in that the cost increases and the productivity further decreases. In addition, the space inside the VTR is occupied by complicated gear/clutch mechanisms, etc.
There was a problem that the area became even narrower, and improvements were desired.

Incidentally, in recent years, ultrasonic motors have attracted attention and are being used in various fields. According to this ultrasonic motor, the required torque can be obtained without requiring a gear/clutch mechanism, so the configuration of the drive system of the reel stand can be simplified and the above-mentioned problems can be expected to be solved. be.

Therefore, an object of the present invention is to be able to perform complex and diverse control operations like a conventional electromagnetic motor (reel motor) drive circuit, and to solve the above-mentioned problems when an ultrasonic motor is applied to a VTR reel motor. It is an object of the present invention to provide a driving circuit for an ultrasonic motor that can solve the problems.

[Means to solve the problem]

In this invention, in a drive circuit for an ultrasonic motor that bends and vibrates a stator using a piezoelectric element and rotates a rotor by a traveling wave generated from the bending vibration, a drive signal generating means generates a drive signal to be supplied to the piezoelectric element. , a level adjustment means for adjusting the level of the drive signal, a switch means for opening and closing the supply path of the drive signal, and a control means for controlling the level adjustment means and the switch means based on an instruction from the outside. .

[Operation] The control means adjusts the level of the drive signal and opens and closes the drive signal supply path with respect to the drive signal supplied from the drive signal generation means.

As a result, each piezoelectric element of the ultrasonic motor is supplied with a drive signal of a required level and a required phase difference, or is cut off, so that the operation of the ultrasonic motor can be controlled to a desired state. .

Therefore, in the ultrasonic motor drive circuit according to the present invention,
Complex and diverse control operations can be performed on the ultrasonic motor, and the number of parts and space can be significantly reduced compared to conventional techniques.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, as shown in FIGS. 1 to 5, the VT
This invention is applied to the R reel motor. Note that this explanation will be made in the following order.

(A) About the configuration of the ultrasonic motor (B) About the configuration and operation of the drive circuit of the ultrasonic motor (C) About controlling the drive of the ultrasonic motor (A) About the configuration of the ultrasonic motor Figures 3 and 4 5 shows the overall structure of the ultrasonic motor, and FIG. 5 shows the structure of the piezoelectric body.

In the configuration shown in FIG. 3, the ultrasonic morph 1 has a stator 2
, a piezoelectric body 3.4, a rotor 6, and a shaft 7.

The stator 2 exhibits bending vibrations and generates traveling waves by applying alternating current voltages having different phases to the piezoelectric bodies 34 that are brought into close contact with each other. A large number of protrusions 8 are formed in an annular shape on the front surface 2A side of the stator 2, a circular hole 9 for inserting the shaft 7 is formed approximately in the center of the stator 2, and a circular hole 9 is formed on the back surface 2B side of the stator 2. The above-mentioned piezoelectric body 3.4 is attached. The above-mentioned protrusions 8 contact the outer circumference 10 of the rotor 6 to rotate the rotor 6, and the protrusions 8 are provided at regular intervals.

The piezoelectric body 3.4 generates a traveling wave in the stator 2 when two alternating current voltages having different phases are applied thereto. As shown in FIG. 5, each piezoelectric body 3.4 is formed by disk-shaped piezoelectric elements 11.12, and a circular hole 14 for inserting a receiving washer 28 is provided in the center of the piezoelectric body 3.4. It is formed.

A grounding electrode (not shown) is formed over the entire surface of the back surface 11B of the piezoelectric body 3, and the piezoelectric body 3, 4
are superimposed in the order shown in FIG.

The piezoelectric body 3 includes a piezoelectric element (for example, piezoelectric ceramics) 11
For example, as shown in FIG. 5A, on the surface 11A of
It is configured by providing eight electrodes 16 divided into regions every 5°. This electrode 16 is formed on the surface 11A using a highly conductive metal material by an appropriate method such as printing, vapor deposition, or plating. Then, the piezoelectric body 3 has the above-mentioned back surface I
Polarization is performed on the entire surface grounding electrode (not shown) provided on the IB so that the polarity is alternately different in the thickness direction. As a result, four sets of forced excitation vibrators with eight poles each consisting of regions 17 having alternately positive or negative polarity are constructed.

After polarization, the electrodes 16 are bonded to the back surface 2B (metal surface) of the stator 2 so that a voltage can be applied collectively, and the back surface 2B of the stator 2 serves as an application electrode.

The piezoelectric body 4 has substantially the same structure as the piezoelectric body 3, and comprises four sets of forced excitation vibrators with eight poles each consisting of regions 5 that are alternately made positive or negative.

On the surface 12A of the piezoelectric element 12 constituting the piezoelectric body 4, as shown in FIG. 5B, eight electrodes 18 are provided, which are divided into regions of 45 degrees, for example.

FIG. 10C is a perspective view of the piezoelectric body 4 seen from the back surface 12B side of the piezoelectric element 12. A full-surface silver electrode 23 is provided on the back surface 12B side. The entire surface silver electrode 23 is for supplying voltage to the piezoelectric body 4, and is formed by applying and baking a conductive adhesive containing a silver filler. A lead wire 21 is fixed to this entire surface silver electrode 23 with the above-mentioned conductive adhesive. Note that 22 indicates a connection portion between the full-surface silver electrode 23 and the lead wire 21.

Furthermore, the notch 19 formed on the outer circumference of the piezoelectric body 4 is
This is to facilitate securing a connection portion between a grounding electrode (not shown) on the back surface 11B side of the piezoelectric element 11 and a lead wire (not shown).

The piezoelectric bodies 3.4 are superimposed in the following manner.

The minimum amplitude point of the piezoelectric body 3.4 is located at the adjacent electrode 16.18.
The maximum amplitude point is near the boundary position of each electrode 16.18
This is the position near the center of . Therefore, the arrangement of the piezoelectric body 3.4 is such that the boundary (minimum amplitude point) of the electrode 1B of the piezoelectric body 4 corresponds to the vicinity of the center (maximum amplitude point) of the electrode 16 of the piezoelectric body 3, as shown in FIG. They are superimposed to look like this.

When a traveling wave is generated in the stator 2, the rotor 6 rotates due to the frictional force generated between the rotor 6 and the stator 2, and generates a driving force. The inner peripheral side of the rotor 6 is a recessed portion 24, and is provided with a step slightly lower than the brim-shaped outer peripheral portion 1o. A circular hole 25 for fitting the shaft 7 is formed in the center of the rotor 6, and a back surface 10B of the outer peripheral part 10 of the rotor 6 is formed.
Since the protrusions 8 of the stator 2 come into contact with the protrusions 8, a cavity for generating frictional force is provided.

By fitting the shaft 7 into the circular hole 25 of the rotor 6,
It transmits the rotation of the rotor 6, and is rotatably supported by a bearing 26.

In the figure, 27 indicates a substrate that supports the ultrasonic motor 7 and is fixed to other members (not shown). Also, 29
30 indicates a countersunk wing, 30 indicates a wing holder, and 31 indicates a clip.

The ultrasonic motor is assembled as follows.

The lower part 33 of the receiving washer 28 is fitted into the circular hole 32 of the substrate 27, and the bearing 26 is fitted and fixed inside the receiving washer 28 as shown in FIG. This bearing 26 rotatably supports the shaft 7. In this state, as shown in FIG. 4, the receiving washer 28 is attached to the base plate 27, the bearing 26 is attached to the receiving washer 28, and the shaft 7 is attached to the bearing 26.

The circular hole 9 of the stator 2 to which the piezoelectric bodies 3 and 4 are attached is inserted through the shaft 7 described above, and the stake 2 is attached. The vicinity of the circular hole 9 on the back surface 2B of the stator 2 is the fourth
As shown in the figure, the stator 2 comes into contact with the upper end surface 34 of the receiving washer 28 and the hair ring 26, so that the stator 2 comes into contact with the receiving washer 28.
8 and a bearing 26.

Next, the shaft 7 is slidably inserted into the circular hole 25 of the rotor 6, and the shaft 7 is slidably inserted into the circular hole 25 of the rotor 6, and
is positioned in contact with the protrusion 8 of the stator 2. The rotor 6 and shaft 7 described above rotate together, but slide in the longitudinal direction of the shaft 7, and at this time a constant pressure preload by the spring 29 is applied. Further, a disc spring 29 is placed in the recess 24 of the rotor 6. Further, the circular hole 35 of the spring holder 30 is inserted through the shaft 7, and the countersunk spring 2
9 is pressed from above, and then the clip 31 is engaged with the engaging portion 36 at the tip of the shaft 7 to fix the spring presser 30.

As a result, due to the elasticity of the disc springs 29, the back surface 10B of the outer circumferential portion 10 of the rotor 6
The ultrasonic mortar 1 is configured in a state in which it is in contact with.

(B) Regarding the configuration and operation of the ultrasonic motor drive circuit FIG. 1 shows an embodiment of an ultrasonic motor drive circuit.

A mode selection switch 46 is connected to the system controller 45 (hereinafter abbreviated as system controller) shown in FIG. 1, and a signal corresponding to the selected mode is supplied to the system controller 45.

Among the mode selection switches 46, 47 is a FWD (recording, playback) mode switch, 48 is an RVS mode switch, 4
9 is FF/REW mode switch, 50 is QUE/RE
VIEW mode switches 51 indicate 5 TOP mode switches, respectively.

In this specification, "FWD" refers to normal speed forward feed, and "RVS" refers to normal speed reverse feed.

Further, FF indicates high-speed forward feeding, and REW indicates high-speed reverse feeding. QUE represents high-speed forward playback, and REVIEW represents high-speed reverse playback.

Furthermore, 5TOP represents stop.

Based on the signal corresponding to the selected mode, the system controller 45 sends a control signal as shown in FIG. 2 to the variable resistor 5.
2.53 and switches 54, 55, and 56, respectively.

The drive signal generated by the drive signal generation circuit 57 is supplied to the variable resistor 52 and the phase shift circuit 58, respectively.

In the phase shift circuit 58 , the drive signal from the drive signal generation circuit 57 is shifted and summed by π/2, and this output signal is supplied to the variable resistor 53 .

In the variable resistors 52 and 53, the level of the drive signal is adjusted based on the control signal from the system controller 45.

The drive signal whose level has been adjusted by the variable resistor 52 is supplied to the A-phase piezoelectric body 60 via the amplifier 59 and the switch 54.

On the other hand, the drive signal whose level is adjusted by the variable resistor 53 is
an inversion circuit 61 in which the phase of the signal is inverted by 180 degrees;
Or via either the switch 55, the amplifier 62
, and is supplied to the B-phase piezoelectric body 63 via the switch 56.

The switches 54, 55, and 56 open and close the drive signal supply path based on the control signal from the system controller 45.

Moreover, the space between each of the piezoelectric bodies 60 and 63 described above is grounded.

In the circuit configuration on the winding side, 64.65 is a variable resistor,
66, 67, and 68 indicate switches, respectively. Further, 69 indicates an A-phase piezoelectric body, and 70 indicates a B-phase piezoelectric body. Although other configurations are not shown in detail,
The configuration is the same as that on the supply side, and redundant explanation will be omitted.

(C) About controlling the drive of the ultrasonic motor (C-1) Drive state and drive signal In the ultrasonic motor 1, for example, the piezoelectric body 60, 63 on the supply side
Various driving states can be obtained by supplying the following driving signals to the . Note that the voltages shown in the following equations can be adjusted to arbitrary levels.

Low speed rotation-----1--------2-phase drive Vsinωt±VCO8ωt High-speed rotation----2-phase drive Vm
axsinωt±Vmaxcos ωt free ---
----------m--Two-phase drive (weak progressive drive) V
sin a> t±Vcosωt or one---
−−−−−−−−−−−−1 phase drive (supplying only standing waves)
V sin ωt Soft brake --- Two-phase drive (weak progressive drive) ■ Sin ω in hand VCO 8 ωt Lock brake -- 111 - Energization stop surface, the above-mentioned low-speed rotation is usually realized by intermittent energization. The energization time can usually be varied within a range of several m5ec. in this case,
For example, startup and shutdown are possible in approximately 2m5ec. Furthermore, the soft brake is set with this in mind, since sudden stopping may damage the magnetic tape. Further, the lock brake completely stops within several m5ec, for example, about 2m5ec after the power supply is stopped.

((,-2) Regarding the drive control of the ultrasonic motor, Fig. 2 shows the variable resistance 5
2.53.64.65 and switch 54.55.56.
66, 67, and 68 control states are shown.

(1) FWD I: Recording/Reproduction] In this mode, the ultrasonic motor 71 on the supply side operates as a soft brake, and the ultrasonic motor 72 on the winding side rotates at a low speed.

(1-1) On the supply side, the drive signal from the drive signal generation circuit 57 is Vo sinω
t, the level is adjusted by the variable resistor 52 to Vl-sinωL, and this drive signal is closed (
It is supplied to the A-phase piezoelectric body 60 through the switch 54 (on).

On the other hand, the above-mentioned drive signal is phase-shifted by π/2 in the phase shift circuit 58 to become VocosωL, and level-tuned by the variable resistor 53 to become Vl·cosωt. Since the switch 55 is open (off), this drive signal passes through the inversion circuit 61 and becomes Vl ・COSωt, and is supplied to the B-phase piezoelectric body 63 via the switch 56, which is closed (on). Ru.

Therefore, the drive signal supplied to the piezoelectric body 60.63 becomes Vl -5in6)t, -Vl .cosωt, realizing soft braking.

(1-2) On the winding side, the drive signal Vosinωt is at level 8 at the variable resistor 64.
It was determined as ■1 ・sinωt by Shusei! It is supplied to the A-phase piezoelectric body 69 via the closed (on) switch 66.

On the other hand, the above-mentioned drive signal is converted to Vo by a phase shift circuit (not shown).
cos ωt, and by adjusting the level with the variable resistor 65, it becomes 1.COS ωt. This drive signal is closed (
It is supplied to the B-phase piezoelectric body 7o via the switches 67 and 68 which are turned on).

Therefore, the drive signal supplied to the piezoelectric body 69.7o becomes Vl ·sinωt+■1 ·cosωt, and low-speed rotation is realized.

(2) In the case of RVS In this mode, the ultrasonic motor 71 on the supply side rotates in low-speed reverse rotation, and the ultrasonic motor 72 on the winding side operates as a soft brake.

(2-1) On the supply side, the drive signal Vosinωt is set to ■1 ・sinωt by level adjustment with the variable resistor 52, and then closed (on).
It is supplied to the A-phase piezoelectric body 60 through the switch 54 .

On the other hand, the above drive signal is converted to Voco by the phase shift circuit 58.
sωt, and by adjusting the level with the variable resistor 53,
It is assumed that Vl ・COSωt. Since the switch 55 is open (off), this drive signal passes through the inversion circuit 61 and becomes Vl·COSωt. This drive signal is passed through the closed (on) switch 56 to the B-phase piezoelectric body 63.
is supplied to

Therefore, the drive signal supplied to the piezoelectric bodies 60 and 63 becomes Vl .sin ωt - 1 .CO3 ωt, and low-speed reverse rotation is realized.

(2-2) On the winding side, the drive signal Vosjnωt is leveled by the variable resistor 64 to become ■1 ・sinωt, and then passes through the closed (on) switch 66 to the A-phase piezoelectric material. 69.

On the other hand, the above-mentioned drive signal is converted to Vo by a phase shift circuit (not shown).
cos ωL, and by adjusting the level with the variable resistor 65, it becomes ■1 ・cos o)L. This drive signal passes through the closed (on) switches 67 and 68 and is supplied to the B-phase piezoelectric body 7o.

Therefore, the drive signal supplied to the piezoelectric bodies 69 and 70 becomes Vl · sin ωt + V 1 · cos ωt, and rough 1 to brake is realized.

(3) In the case of FF In this mode, the ultrasonic motor 71 on the supply side is free;
The ultrasonic motor 72 on the winding side rotates at high speed.

(3-1) On the supply side, the drive signal Vosinωt is set to V2 ・sinωt by level adjustment with the variable resistor 52, and then closed (on).
It is supplied to the A-phase piezoelectric body 60 through the switch 54 .

On the other hand, the above drive signal is converted to Voco by the phase shift circuit 58.
sωt, and by adjusting the level at the variable resistor 53, it becomes 2.COSωL. This drive signal is closed (
It is supplied to the B-phase piezoelectric body 63 via the switches 55 and 56 which are turned on).

Therefore, the drive signal supplied to the piezoelectric body 60.63 becomes V2 .sinωt+V2 .cosωt, and free (two-phase drive) is realized.

(3-2) On the winding side, the drive signal Vosinωt is set to ■3 ・sinωt by level adjustment with the variable resistor 64, and then closed (on).
It is supplied to the A-phase piezoelectric body 69 through the switch 66 .

On the other hand, the above-mentioned drive signal is set to Vocosωt by a phase shift circuit (not shown), and is variable J'J, L lJ"l;
By adjusting the level at 65, it is set to ■3 ・cosωt. This drive signal is supplied to the B-phase piezoelectric body 70 via the switches 67 and 68 which are closed (on).

Therefore, the drive signal supplied to the piezoelectric bodies 69 and 70 becomes: (13) .sin ωt+2.3 .CO3 ωt, realizing high-speed rotation.

(4) In the case of REW In this mode, the ultrasonic motor 71 on the supply side rotates in reverse at high speed, and the ultrasonic motor 72 on the winding side becomes free.

(4-1) On the supply side, the drive signal Vosinωt is set to ■3 sinωt by level adjustment with the variable resistor 52, and then closed (on).
It is supplied to the A-phase piezoelectric body 60 through the switch 54 .

On the other hand, the above drive signal is converted to Voco by the phase shift circuit 58.
By adjusting the level with the variable resistor 53, the drive signal is set to 3.cosωt. Since the switch 55 is open (off), this drive signal passes through the inversion circuit 61 and becomes V3·cosωt, and is supplied to the B-phase piezoelectric body 63 via the switch 56, which is closed (on). be done.

Therefore, the drive signal supplied to the piezoelectric body 60.63 becomes V3·s4nωt, -V3·cosωt, realizing high-speed reverse rotation.

(4-2) On the winding side, the drive signal Vosinωt is set to ■2 ・sinωt by level adjustment with the variable resistor 64, and then closed (on).
It is supplied to the A-phase piezoelectric body 69 through the switch 66 .

On the other hand, the above-mentioned drive signal is converted to Vo by a phase shift circuit (not shown).
cos ωt, and by adjusting the lever adjustment by the variable resistor 65 for 8 rounds, it is set to v2·COS ωL.

Since the switch 67 is closed (off), the second drive signal passes through an inverting circuit (not shown), becomes V2・COSωt, and passes through the switch 68, which is closed (on), to the B-phase piezoelectric body 70. is supplied to

Therefore, the drive signal supplied to the piezoelectric bodies 69 and 70 becomes: (2) .sin ωL-V2 .cos ωt, and free (two-phase drive) is realized.

(5) In the case of QUE In this mode, the ultrasonic motor 71 on the supply side is free;
The ultrasonic motor 72 on the winding side rotates at medium speed.

(5-1) Regarding the supply side, the drive signal Vosinωt is set to ■2・sinωL due to the level fluctuation at the variable resistor 52, and is then supplied to the A-phase piezoelectric body 60 via the closed (on) switch 54. be done.

On the other hand, the above drive signal is converted to Voco by the phase shift circuit 58.
However, since the switch 56 is open (off), the drive signal is not supplied to the B-phase piezoelectric body 63.

Therefore, the drive signal is supplied only to the piezoelectric body 60, and
- S i nωL and free (one-phase drive) is realized.

(5-2) On the winding side, the drive signal Vosinωt is level-adjusted by the variable resistor 64 to become ■2 ・sinωt, and then the drive signal Vosinωt is closed (
It is supplied to the A-phase piezoelectric body 69 through the switch 66 (on).

On the other hand, the above-mentioned drive signal is converted to Vo by a phase shift circuit (not shown).
cosωL, and by adjusting the level with the variable resistor 65, it becomes 2.COSωt. This drive signal is closed (
It is supplied to the B-phase piezoelectric body 70 through the switches 67 and 68 which are turned on.

Therefore, the drive signal supplied to the piezoelectric bodies 69 and 70 is V2 .sjnωt+V2 .cosωt, achieving medium speed rotation.

(6) Case of REVIEW In this mode, the ultrasonic motor 71 on the supply side rotates in reverse at a medium speed, and the ultrasonic motor 72 on the winding side becomes free.

(6-1) On the supply side, the drive signal Vosinωt is set to ■2 ・sinωt by level adjustment with the variable resistor 52, and then closed (on).
It is supplied to the A-phase piezoelectric body 60 through the switch 54 .

On the other hand, the above drive signal is converted to Voco by the phase shift circuit 58.
sωL, and by adjusting the level with the variable resistor 53,
The drive signal is 2.cosωt. Since the switch 55 is open (off), this drive signal passes through the inversion circuit 61 and becomes v2·cosωt, and is supplied to the B-phase piezoelectric body 63 via the switch 56, which is closed (on). be done.

Therefore, the drive signal supplied to the piezoelectric body 60.63 is V2・5ina+t−V2・cos ωt
.

As a result, medium-speed reverse rotation is achieved.

(6-2) On the winding side, the drive signal Vosinωt is set to V2 · sinωt by level adjustment with the variable resistor 64, and then closed (on).
It is supplied to the A-phase piezoelectric body 69 through the switch 66 .

On the other hand, the above-mentioned drive signal is converted to Vo by a phase shift circuit (not shown).
cos ωt, but since the switch 68 is open (off), the drive signal is not supplied to the B-phase piezoelectric body 70.

Therefore, the drive signal is supplied only to the piezoelectric body 69, and V2
- sin ωt, and free (one-phase drive) is realized.

(7) In the case of STOP, the driving state of the ultrasonic motors 71 and 72 in this mode is a lock brake on both the supply side and the drive side. That is, the drive signal Vosinωt is
6 and 68 are both open (off), so the piezoelectric body 6
It is not supplied at 0.63.69.70 and the power is cut off.

Therefore, the ultrasonic motors 71, 72 become locking brakes.

According to this embodiment, complex and various control operations can be performed on the ultrasonic motor using a drive circuit having an extremely simple configuration.

In addition, since complex and diverse control operations of the ultrasonic motor are possible, conventional electromagnetic motors and their associated gears and
Since various parts such as a clutch mechanism are no longer required, the number of parts can be significantly reduced.

Although this embodiment is explained using a VTR as an example, the present invention is not limited to this and can of course be applied to other electronic devices having tape winding and rewinding functions.

〔Effect of the invention〕

In the ultrasonic motor drive circuit according to the present invention, the drive signal generated from the drive signal generation means is adjusted by the level adjustment means and the switch means controlled by the control means, and is supplied to the piezoelectric element. This has the advantage that complex and diverse control operations can be performed on the ultrasonic motor.

Additionally, since it becomes possible to perform complex and diverse control operations on the ultrasonic motor, various parts such as the conventional electromagnetic motor and its accompanying gear, clutch, and punch mechanisms are no longer required, and the number of parts can be significantly reduced. It has the effect of Since the number of parts is significantly reduced, it has the effect of reducing costs and improving productivity. In addition, since the number of parts can be significantly reduced, the space inside the electronic device is prevented from being occupied, resulting in space saving.

[Brief explanation of the drawing]

Figure 1 is a diagram of the first embodiment of the present invention, Figure 2 is a route diagram showing the control status in each operation mode, Figure 3 is an exploded perspective view of the ultrasonic motor, and Figure 4 is the ultrasonic motor. FIG. 5G is a schematic cross-sectional view of the sonic motor, and FIG. 5G is a perspective view illustrating the structure of the piezoelectric body. Explanation of main symbols in the drawings 1.71.72: Ultrasonic motor, 2: Stator, 6: Rotor, 11.12: Piezoelectric element, 45 Nijistem controller, 52.53.64.65: Variable resistor, 54. 55
．． 56.66.67.68: Switch, 57; Drive signal generation circuit.

Claims (1)

[Scope of Claim] In a drive circuit for an ultrasonic motor that bends and vibrates a stator using a piezoelectric element and rotates a rotor using a traveling wave generated from the bending vibration, a drive that generates a drive signal to be supplied to the piezoelectric element. a signal generation means; a level adjustment means for adjusting the level of the drive signal; a switch means for opening and closing the supply path of the drive signal; and a control means for controlling the level adjustment means and the switch means based on an external instruction. An ultrasonic motor drive circuit characterized by comprising: