JPH0795778A - Oscillatory wave driving device - Google Patents

Abstract

PURPOSE:To provide an oscillatory wave driving device which can be started quickly regardless of its load and can be surely started. CONSTITUTION:This invention relates to an oscillatory wave driving device which generates oscillatory waves from 7n oscillatory elastic body by applying an AC voltage to piezoelectric elements 7 and 8 and relatively moves the oscillatory elastic body and a member press-contact with the elastic body by friction, and then, selectively transmits a driving force generated by the relative movement to multiple driven bodies having different loads. The device is provided with a load discriminating means 11 which discriminates the loads of the selected driven bodies and control means which changes the sweep starting frequency of the frequency sweep of the AC voltage at the time of start by applying loads discriminated by the means 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave driving device such as a vibration wave motor or a paper feeding device which utilizes ultrasonic vibration.

[0002]

2. Description of the Related Art A vibration wave driving device utilizing ultrasonic vibration,
For example, frequency control is performed as drive control in a vibration wave motor (hereinafter referred to as an ultrasonic motor), which is drive control in a region having a frequency higher than the resonance frequency of a vibrating elastic body in which drive vibration is excited. In addition, the drive control at startup is higher than the frequency actually used for driving, while the frequency is swept from a frequency higher than the lowest frequency that can be driven to a lower frequency, and resonance occurs while detecting the vibration state of the vibrating elastic body. The ultrasonic motor is driven with a frequency near the frequency as the drive frequency.

FIG. 7 shows the relationship between the frequency and the rotational speed when the load torque of the ultrasonic motor is large or small. When the load torque is large, the resonance frequency is high and the drive frequency is high, and the rotational speed is low. . When the load torque is small, the resonance frequency is low, so the drive frequency is low and the rotation speed is high.

FIG. 8 shows the relationship between the load torque T and the minimum frequency f _{0 that} can be started with the torque T. The minimum start frequency f ₀ is high when the load torque is large and low when the load torque is small. I understand.

Further, as shown in FIG. 9, when the load torque is large, the frequency sweep range when the ultrasonic motor is started is from the lowest frequency f _{0A that} can be started to the drive frequency f _A , and the load torque is small. If the lowest frequency f that can be started
A is more up to starting frequency f _{B 0B,} the lowest frequency f _0A and f _0B bootable is f _0A> f _0B, the drive frequency f _A and f _B is f _A> f _B.

[0006]

Conventionally, the frequency sweep range when the ultrasonic motor is started has been constant regardless of the size of the load. Therefore, for example, the frequency sweep range is set in accordance with a large load. Then, when the load is light, the frequency sweep is started from a frequency much higher than the lowest frequency that can be started, the frequency is swept over a wider range than necessary, it takes time to reach the drive frequency, and the motor starts up quickly. Could not be realized.

Further, if the frequency sweep range is set according to the case where the load is small, the sweep may be started from a frequency lower than the lowest frequency that can be started when the load is large, so that the start may not be possible.

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem and provide a vibration wave driving device which can be quickly started regardless of the size of the load and which is not disabled.

[0009]

The constitution of an oscillatory wave driving device which realizes the object of the present invention is as described in each of the claims, for example, an electric-mechanical energy conversion element. A drive wave is formed in the vibrating elastic body by applying an AC voltage, and the vibrating elastic body and a member that makes pressure contact with the vibrating elastic body are relatively moved by frictional force, and the driving force generated by the relative movement is selected. In a vibration wave drive device that is transmitted to a plurality of driven bodies having different loads, a load discriminating unit that discriminates the load of the selected driven body, and the electric The present invention is characterized by having a control means for changing the sweep start frequency of the frequency sweep of the AC voltage applied to the mechanical energy conversion element at the time of start, and has a large load for the sweep start frequency of the frequency sweep at start. By higher than when the load is small in case, to realize a quick rise, also prevents falling into fatal.

[0010]

1 is a block diagram showing a first embodiment of the present invention.

1 is a microcomputer for controlling the ultrasonic motor,
The control signal is output according to the input information. 2 is an 8-bit digital-analog converter (D / A), for example.
As shown in, the voltage V corresponding to the input from the microcomputer 1 is output. A voltage controlled oscillator (VCO) 3 outputs an AC voltage having a frequency f according to the input voltage V from the D / A converter 2 as shown in FIG. Reference numeral 4 is a phase shifter which shifts the phase of the input signal by +90 depending on the rotation direction of the ultrasonic motor (not shown)
To 90 degrees or -90 degrees.

Amplifiers 5 and 6 amplify the input signal to a size suitable for driving an ultrasonic motor (not shown). Reference numerals 7 and 8 are piezoelectric elements for driving an ultrasonic motor (not shown).

The drive signal from the VCO 3 is branched into the amplifier 5 and the phase shifter 4, the drive signal from the amplifier 5 is applied to one piezoelectric element 7, and the signal from the phase shifter 4 is passed through the amplifier 6. When an alternating voltage is applied to the other piezoelectric element 8 and has a phase difference of 90 degrees, for example, an alternating voltage is applied to the piezoelectric elements 7 and 8 to excite a vibrating elastic body (not shown). Due to, for example, the combination of the bending vibrations, the surface particles on the driving surface of the vibrating elastic body undergo an elliptic motion, and the member that comes into pressure contact with the driving surface and the vibrating elastic body move relatively by frictional force.

Reference numeral 9 is a vibration detecting piezoelectric element, and 10 is a phase comparator, which is a driving signal output to the driving piezoelectric element 7,
The phase difference θ from the detection signal detected by the piezoelectric element 9 for detecting the vibration state is output to the microcomputer 1. Here, if the ultrasonic motor is, for example, a rod-shaped ultrasonic motor, the piezoelectric element 7,
8 and 9 are formed in a disk shape and have different polarization directions with a diameter portion as a boundary, and the driving piezoelectric elements 7 and 8 are 90
The piezoelectric element for detecting the vibration state is stacked in the same phase as the piezoelectric element 7, and is sandwiched by the vibrating elastic body. Therefore, the microcomputer 1 has this phase difference θ.
Is controlled to be constant (ideally θ = 0).

Reference numeral 10 denotes an output switching device shown in FIG. 4, which switches the output between a driven object having a large load and a driven object having a small load driven by an ultrasonic motor. Reference numeral 11 denotes a load discriminating device, which outputs a signal to the microcomputer 1 according to the output switching of the ultrasonic motor by the output switching device 10.

FIG. 4 shows an output switching device provided with a load discriminating device, and 31 is an output gear of an ultrasonic motor (not shown), 3
Reference numeral 2 is a connecting gear, 33 is a switching gear, and the switching gear 33 is axially supported by the shaft portion of the connecting gear 32 so as not to rotate and movable in the thrust direction. Reference numeral 34 is a first transmission gear connected to a large load (not shown), 35 is a second transmission gear connected to a small load (not shown), 36 is an actuator, 37 is a switching lever, and the switching lever 37 is a switching gear 33 depending on the movement of the actuator 36. Is slid to the left and right in the figure to switch the engagement with the first transmission gear 34 or the second transmission gear 35 to switch the output.

Reference numeral 38 is a load discriminating device comprising a leaf switch. As shown in FIG. 4, the switching gear 33 is a first transmission gear 34.
In the driving state with a large load in mesh with, the signal is turned on and the signal K = 1 is output to the microcomputer 1. In the driving state with a small load in mesh with the second transmission gear 34 as shown in FIG.
The signal K = 0 is output to the microcomputer 1. That is, the signal K
= 1 means a large load and K = 0 means a small load.

In this output switching device, when the load is large, the rotation of the motor is transmitted in the order of gears 31 → 32 → 33 → 34. At this time, the lower end of the switching lever 37 contacts the leaf switch 38 and the leaf switch 38. Turns on. When the load is small, the rotation of the motor is changed from the gear 31 to 32.
→ 33 → 35 is transmitted. At this time, since the lower end of the switching lever 37 is separated from the leaf switch 38, the leaf switch 38 is turned off.

The operation of the above-described first embodiment will be described below with reference to the flow chart shown in FIG.

When the start-up flowchart starts (step 1), it is first determined whether or not the value of the load discriminating device 11 is K = 1 (step 2). If the load on the ultrasonic motor is large (K = 1), the process proceeds to step 3, and if the load on the ultrasonic motor is small (K ≠ 1), the process proceeds to step 4.

In step 3, the digital value S = FF for setting the input to the digital-analog converter 2 to the starting lowest frequency according to the preset large load,
Further, in step 4, the digital value S = 99 for setting the input to the digital-analog converter 2 to the starting minimum frequency according to the preset small load, and the process proceeds to step 5, respectively.

In step 5, the frequency in the VCO voltage controlled oscillator 3 is initialized, and the voltage set in step 3 or 4 is converted into the frequency f (S). In addition,
f (FF)> f (99), the minimum starting frequency is increased when the load is large, the minimum starting frequency is decreased when the load is small, and the process proceeds to step 6 to drive the amplifiers 5 and 6 by turning them on. AC voltage is applied to the piezoelectric elements 7 and 8 for use to start the ultrasonic motor.

When the ultrasonic motor is started, in step 7, the phase difference between the driving frequency of the driving piezoelectric element 7 and the AC signal detected by the vibration state detecting element 9 is θ _AS =
θ is compared with a predetermined value θ ₀ preset in the microcomputer 1. If θ ≦ θ ₀ , it is determined that the drive frequency has become appropriate, the process proceeds to step 9, the present flow ends, and θ> θ
_{If 0} , the process proceeds to step 8, the frequency is lowered by Δf, and this routine is repeated until θ ≦ θ ₀ .

As described above, according to the present embodiment, when the load is large, the frequency sweep at the time of start of operation starts from a high frequency, and the ultrasonic motor is driven at an appropriate drive frequency by the well-known phase comparator to ensure the operation. It can be started. That is,
When the load is small, the frequency sweep at startup starts from a lower frequency than when the load is large, and the ultrasonic motor is driven at a proper drive frequency by a known phase comparator, and a quick rotation start can be realized. .

10 to 12 show a second embodiment of the present invention.

In this embodiment, while the rotating load makes one rotation, the driven body is driven under a large load (0 to 180 degrees) and then stopped (180 degrees), and the next load is applied to the load. Small (1
The driven body is driven in the state of 80 degrees to 360 degrees and stopped (0 degrees, 360 degrees), and when the driving is further started, the apparatus that performs the operation of starting the driving again in the above-mentioned heavy load is ultrasonic wave. An example of driving by a motor is shown.

Reference numeral 67 is an output gear of the ultrasonic motor, which meshes with one of the cam gears 61 and 63 having the same number of teeth to mesh with each other, and rotates in the direction of the arrow to form the cam gear 61.
And 63 rotate in different directions at the same speed. The cam gears 61 and 63 are provided with a cam portion having the same shape with a phase difference of 180 degrees. This cam portion is the cam lift portion 61.
a and 63a, and a flat portion (a portion having a constant diameter) 61b,
Drive lever 62 driven by the cam portion of cam gear 61 drives a driven portion (not shown) having a large load, and drive lever 64 driven by the cam portion of cam gear 63 has a small load. The driven part shown is driven.

The drive levers 62 and 64 are provided on the support shaft 62.
a and 64a are rotatable, and the cam follower portions 62b and 64b on one end side are respectively provided on the cam lift portion 61.
a, 63a, contact points 62c, 64c on the other end side
Is designed to drive a driven part (not shown), but the cam lift parts 61a and 63 of the cam parts of the cam gears 61 and 63 are provided.
Since the phase is 180 degrees out of phase with a, when the rotation is started from the position shown in FIG.
When 2 is driven and rotated 180 degrees, the return spring (not shown) makes contact with the flat portion 61b to stop the rotation, and
The drive of the ultrasonic motor is once stopped. Then, the driving of the ultrasonic motor is started again, and this time the driving lever 64 with a small load is driven between 180 degrees and 360 degrees.

On the other hand, a phase substrate 66 having a pattern shown in FIG. 12 corresponding to the cam gear 61 is fixed to a fixing portion (not shown) corresponding to the cam gear 61, and a contact piece 65 provided on the back side of the cam gear 61. Are arranged to slide on the ground pattern G, the load discrimination pattern A, and the stop pattern B provided on the phase board 66.

Here, when the cam position in FIG. 10 is θ = 0 degrees and the ultrasonic motor rotates in the direction of the arrow, the contact pattern 65 provided on the cam gear 61 causes the discriminative pattern A and the ground pattern of the phase substrate 66. G and θ = 0 degree to 1
The contact is made within a range of 80 degrees, the switch A composed of the discrimination pattern A and the ground pattern G is turned on, and K = 1 indicating that the load is large as the load discrimination device is output. Next, at θ = 180 degrees, the switch B is turned on and the driving of the ultrasonic motor is stopped. Then, when the ultrasonic motor is activated, the switch A is turned off in the range of θ = 180 degrees to 360 degrees, and the switch A outputs K = 0 as a load determination device. Then, the switch B is turned on at θ360 degrees, and the ultrasonic motor is stopped in response to this signal.

Therefore, based on the signal from this load discriminating apparatus, the ultrasonic motor can be smoothly driven by switching the starting minimum frequency in the same manner as in the above-mentioned first embodiment, and the driving of the lever and The relationship of the switches is shown in FIG.

The operation of the second embodiment will be described with reference to the flow chart shown in FIG.

Since steps 1 to 8 are the same as the flowchart showing the operation of the first embodiment shown in FIG. 6, the description thereof will be omitted and it is determined in step 7 that proper driving is being performed. Then, in step 9, it is determined whether or not the switch B is turned on. When the switch B is turned on, driving of the ultrasonic motor is stopped (step 10), and when restart is instructed (step 11), the process returns to step 2. , The output of the load discriminating device composed of the switch A is checked, and the starting lowest frequency is switched to the higher or lower depending on the load.

15 and 16 show a third embodiment of the present invention.

In this embodiment, a planetary gear mechanism is used to switch the drive load depending on the forward and reverse rotation directions of the planetary lever. For example, film winding and rewinding in a film feeding mechanism of a camera. It is used as a transmission mechanism.

Reference numeral 21 is an ultrasonic motor (not shown), for example, an output gear of a rod-shaped ultrasonic motor, 22 is a reduction gear that meshes with the output gear 21, 23 is a sun gear that rotates coaxially with the reduction gear 22, and 24 is Planetary arm, 25 is planetary gear,
26 is a first transmission gear connected to a large load (not shown),
A second transmission gear 27 is connected to a small load (not shown), and these gears and the like constitute a known planetary clutch.

In FIG. 15, when the ultrasonic motor rotates clockwise (CW), the planet gear 25 rotates around the sun gear 23 that rotates integrally with the reduction gear 22, and the planet arm 24 rotates counterclockwise as indicated by arrow A. The planetary gear 25 rotating in the clockwise direction and rotating in the clockwise direction meshes with the first transmission gear 26,
The ultrasonic motor is driven under a heavy load. At this time, when clockwise rotation is input to the load discriminating apparatus 11 shown in FIG. 1 by the means for determining the driving direction of the ultrasonic motor, the load discriminating apparatus 11 outputs the signal K = 1.

As shown in FIG. 16, when the ultrasonic motor rotates counterclockwise (CCW), the planetary arm 24
Rotates clockwise in the direction of arrow B, the planetary gear 25 rotating counterclockwise meshes with the second transmission gear 27, and the ultrasonic motor is driven under a small load. When the counterclockwise rotation is input from the means for determining, the load determination device outputs K = 0.

FIG. 17 is a flow chart showing the operation of this embodiment, but steps 5 to 12 are the same as steps 2 to 9 of the flow chart shown in FIG. In the operation of the present embodiment, the rotation direction of the ultrasonic motor is determined in step 2, and if it is clockwise rotation, the process proceeds to step 3 where the load determination device is K = 1.
Is output, and in the counterclockwise direction, the load determination device outputs K = 0 in step 4.

As described above, according to the present embodiment, it is possible to determine whether the load is large or small based on the rotating direction of the ultrasonic motor, so that it is not necessary to provide a special switch mechanism.

FIG. 18 shows an embodiment in which the above-mentioned third embodiment is used in a film feeding mechanism of a camera. 50 is a camera, 51 is a film feeding control circuit, 52 is an ultrasonic motor, and 53 is a third. Of the planetary gear mechanism, 54 is a film winding spool, 55 is a transmission belt, 56 is a rewinding fork, and the output switching device 53 is a forward rotation of the ultrasonic motor 52. The rotation is transmitted to the winding spool 54, and the film is wound under a large load. At that time, the film feeding control circuit 51
In response to rotation of the ultrasonic motor 52 in the forward direction, frequency sweep is started from a high frequency which is the lowest frequency at startup.

When the ultrasonic motor 52 is rotated in the reverse direction, the output switching device 53 transmits the rotation of the ultrasonic motor 52 to the transmission belt 55.
To the rewinding fork 56 to rewind the film with a small load. At that time, the film feeding control circuit 51 receives the rotation in the reverse direction of the ultrasonic motor and sweeps the lowest frequency at the time of starting from a low frequency.

Therefore, the optimum frequency sweep can be performed for the respective loads of film winding and rewinding, so that a quick start-up of rotation can be obtained and the time of film winding and rewinding can be shortened.

In each of the above embodiments, two loads having different loads are driven, but three or more loads may be driven.

[0045]

As described above, according to the present invention, a quick start-up can be realized even when the load at the time of starting is large or small, and the inability to start cannot be prevented. can do.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a characteristic diagram of the digital-analog converter of FIG.

FIG. 3 is a characteristic diagram of the voltage controlled oscillator of FIG.

FIG. 4 is a schematic diagram of the output switching device of FIG. 1, showing a state in which the output is switched to a large load.

5 is a schematic view of the output switching device of FIG. 1, showing a state in which the output is switched to a small load.

6 is a flowchart showing the operation of the embodiment of FIG.

FIG. 7 is a characteristic diagram of an ultrasonic motor showing the relationship between frequency and rotation speed when the load torque is large or small.

FIG. 8 is a characteristic diagram of an ultrasonic motor showing a relationship between load torque and minimum starting frequency.

FIG. 9 is a characteristic diagram of an ultrasonic motor showing a frequency sweep range when the load torque is large or small.

FIG. 10 is a schematic diagram of an output switching device showing a second embodiment.

11 is a side view of FIG.

12 is a diagram showing a pattern of the phase substrate of FIG.

13 is a timing chart of the output switching device of FIG.

FIG. 14 is a flowchart illustrating the operation of the second embodiment.

FIG. 15 is a schematic diagram of an output switching device showing a third embodiment, showing a state in which a heavy load is switched.

FIG. 16 is a schematic view of an output switching device showing a third embodiment, showing a state in which the load is switched to a small load.

FIG. 17 is a flowchart illustrating the operation of the third embodiment.

FIG. 18 is a diagram showing an example in which the output device shown in the third embodiment is used in a film feeding device of a camera.

[Explanation of symbols]

 1 Microcomputer 2 Digital / Analog Converter (D / A) 3 Voltage Controlled Oscillator (VCO) 4 Phase Shifter 5, 6 Amplifier 7, 8, 9 Piezoelectric Element 10 Output Switching Device 11 Load Discrimination Device 31, 32, 33, 34, 35 Gear 36 Actuator 37 Switching lever 38 Leaf switch

Claims (4)

[Claims] 1. A drive wave is formed in an oscillating elastic body by applying an AC voltage to an electro-mechanical energy conversion element, and the oscillating elastic body and a member that is brought into pressure contact with the oscillating elastic body are relatively moved by a frictional force. In addition, in the vibration wave drive device that selectively transmits the driving force generated by the relative movement to the plurality of driven bodies having different loads, load determining means for determining the load of the selected driven body,
An oscillatory wave drive device comprising: a control unit that changes a sweep start frequency of a frequency sweep of an AC voltage applied to the electro-mechanical energy conversion element at the time of startup according to the load determined by the load determination unit. . 2. The output switching means determines the selective switching of a plurality of driven bodies according to the relative movement direction or phase of the vibrating elastic body and the member pressingly contacting the vibrating elastic body. The load discriminating means outputs load information to the control means based on the switching information from the switching means. 3. The control means according to claim 1 or 2,
An oscillatory wave drive device characterized in that a sweep start frequency of a frequency sweep at startup is made higher when a load is large than when a load is small. 4. An apparatus using the vibration wave drive device according to claim 1, 2 or 3 as a drive source.