JPH10337050A - Driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control the operation of vibration detectors, by providing a processing part for processing the output of a vibration detector and a selection part for selecting either one or at least two of the vibration detectors, and allowing a processing part to process the output information of the vibration detectors being selected by the selection part. SOLUTION: A selection circuit 47 receives information that a relative motion member is driven in right direction from a controller 46. As a result, the selection circuit 47 selects a piezoelectric body 13p' located at a side where the relative motion member advances and inputs the detection signal to a controller 46. The controller 46 obtains the effective value of the detection signal being inputted from the selection circuit 47. The obtained effective value is compared with a value being set to, for example, the memory of the controller 46 in advance. When they do not agree, the controller 47 gives a proper oscillation command to an oscillator 42, changes the frequency of a drive signal being generated by the oscillator 42, and controls the operation of an ultrasonic motor so that the speed of the relative motion member reaches a specific value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a vibration actuator which makes a relative motion with a relative motion member by bringing a vibrator into contact with the relative motion member.

[0002]

2. Description of the Related Art Conventionally, a drive signal is applied to an elastic body on which a piezoelectric body is mounted to generate a longitudinal vibration and a bending vibration harmoniously, and to generate an elliptical motion on the surface of the elastic body. There is known a vibration actuator which makes a relative motion with a relative motion member which comes into pressure contact with a member. Such a vibration actuator is described in “Piezoelectric Linear Motor for Moving Optical Pickup” (Mr. Yoshiro Tomikawa et al .: Proceedings of the 5th Dynamic Symposium on Electromagnetic Force, pp. 393-398). The analysis results regarding the configuration and the load characteristics are described in detail. Further, a self-propelled device using this vibration actuator is disclosed in a new version of ultrasonic motor (by Sadayuki Ueba and Yoshiro Tomikawa, published by Trikeps, pages 145 to 146).

FIG. 4 is a perspective view showing a vibrator of a conventional vibration actuator. The vibrator 110 is a flat elastic body 1 designed such that the natural frequencies of the first-order longitudinal vibration mode and the fourth-order bending vibration mode have very close values.
12, two piezoelectric members 114 are joined. An AC voltage having a predetermined frequency is applied to each piezoelectric body 114 with a predetermined phase difference. Here, the predetermined frequency is a frequency close to the natural frequency of the above two vibration modes of the elastic body 112. The application of the AC voltage causes the piezoelectric body to vibrate, and causes the elastic body 112 to harmoniously generate the above two modes of vibration. A driving force extracting portion 116 is provided at a portion of the antinode of vibration of the bending fourth mode generated in the elastic body, and when the elastic body 112 vibrates, the driving force extracting portion 11 is provided.
Elliptic motion occurs at the tip of No. 6. The distal end of the driving force extracting portion 116 is in pressure contact with a relative motion member (not shown) at a predetermined pressure, and when the distal end performs the elliptical motion, a thrust is obtained, and the vibrator 110 and the relative motion member Perform a linear relative motion.

Conventionally, in such a vibration actuator, a pickup for detecting the vibration amplitude of the vibrator is attached to the vibrator 110 in order to detect the speed of the relative movement between the vibration actuator and the relative motion member. And
The driving device of the vibration actuator controls the operation (relative movement) of the vibration actuator with reference to the output of the pickup.

[0005]

In the above-mentioned vibration actuator, the vibrator 110 is designed and manufactured so as to be symmetrical with respect to the direction of relative movement. However, it is impossible to obtain a completely symmetrical shape, and therefore, the vibrator 110 oscillates asymmetrically in the front-rear direction. Therefore, the vibration detected by the pickup differs, for example, between the case where the pickup is mounted at the position Y1 of the vibrator shown in FIG. 4 and the case where the pickup is mounted at the position Y2 symmetrical thereto. On the other hand, the elliptical motion performed by the driving force extracting unit 116 is represented by an arrow M in the figure.
As shown by, the major axis S is not perpendicular to the elastic body 112 but is slightly inclined so as to open toward the front and rear ends of the elastic body. For this reason, the contribution ratios of the forces of the two driving force output units to the relative motion performed by the vibrator 110 are not equal. For example, when the vibrator 110 moves in the direction of the arrow N, the contribution ratio of the driving force extraction unit 116a is Is larger than the contribution ratio of the driving force extracting portion 116b. From the above two circumstances, if the pickup is mounted at the position Y1 of the vibrator 110, the vibrator 110 performs relative motion in the direction of arrow N, and the relative motion in the opposite direction. Thus, there is a problem that even if the detection signals output from the pickups are the same, the speeds of the relative motions are different and accurate speed detection cannot be performed.

The present invention has been made in view of the above problems, and accurately detects the speed of relative movement regardless of the direction of relative movement between a vibration actuator and a relative movement member, thereby properly operating the vibration actuator. To provide a control device for controlling the driving force.

[0007]

According to a first aspect of the present invention, there is provided a vibration actuator for performing a relative motion with a relative motion member by bringing a vibrator into contact with the relative motion member. A driving unit for a vibration actuator including at least two vibration detectors in the vibrator, a processing unit that processes an output of the vibration detector, and one or more of the vibration detectors are selected. A drive unit, wherein the processing unit processes output information of the vibration detector selected by the selection unit.

According to a second aspect of the present invention, in the driving device according to the first aspect, the processing unit controls a speed of the vibration actuator based on an output of the vibration detector selected by the selection unit. It is a drive device characterized by the above-mentioned. The invention according to claim 3 is claim 1 or claim 2.
5. The driving device according to claim 1, wherein the selection unit changes the selected vibration detector according to a driving state of the vibration actuator.

According to a fourth aspect of the present invention, in the driving device according to the first or second aspect, the selection section changes the selected vibration detector according to the direction of the relative movement. It is a driving device characterized by the following. According to a fifth aspect of the present invention, in the driving device according to any one of the first to fourth aspects, the vibrator is excited by longitudinal vibration and bending vibration, and is provided with a driving force provided at a predetermined position. Having a flat or columnar elastic body that generates elliptical motion in the take-out part,
The relative movement member is brought into contact with the driving force extraction unit to perform the relative movement, the selection unit,
A driving device, wherein one or two or more of the vibration detectors provided on a rear side of the vibrator are selected with respect to a direction of the relative motion.

According to a sixth aspect of the present invention, in the driving device according to the fifth aspect, the selecting section is provided in the vicinity of the driving force extracting section located on the rear side of the vibrator with respect to the direction of the relative movement. A driving apparatus, wherein one or two or more of the vibration detectors provided are selected. Claim 7
In the driving device according to claim 5, in the driving device according to claim 5 or 6, the vibrator has a shape that is symmetrical in a longitudinal direction with respect to a direction of the relative motion, and the at least two vibration detectors include the vibrator. The driving device is provided at a position symmetrical in the front-rear direction with respect to the direction of the relative movement.

According to an eighth aspect of the present invention, there is provided an elastic body for performing a predetermined vibration, two or more output extracting portions provided at different positions of the elastic body, and detecting different vibration characteristics of the output extracting portions. A vibration actuator that includes two or more vibration detectors and performs relative movement with the relative movement member by bringing the output extraction section into contact with the relative movement member, wherein the output extraction section acts on the relative movement member. In a driving device that drives a vibration actuator, the rate of the force to be applied that contributes to the relative movement is different depending on the direction of the relative movement, a control unit that controls the operation of the vibration actuator, and the force that contributes to the relative movement is a maximum. A selection unit that selects the vibration detector that detects a vibration characteristic of the output extraction unit, wherein the control unit is configured to control the vibration detector selected by the selection unit. A driving device and controls the operation of the vibration actuator based on the force.

According to a ninth aspect of the present invention, in the driving device according to the eighth aspect, the selection section selects the vibration detector based on information on the direction of the relative motion obtained from the control section. A driving device characterized by the following. According to a tenth aspect of the present invention, in the driving device according to the eighth aspect, the control unit controls the vibration actuator to generate a first drive signal and a second drive signal having a phase difference from the first drive signal. And the direction of the relative movement is controlled by the sign of the phase difference, and the selecting unit selects the vibration detector based on information on the sign of the phase difference. It is.

[0013]

Embodiments of the present invention will be described below in more detail with reference to the drawings. In the following description, an ultrasonic motor using an ultrasonic vibration region will be described as an example of a vibration actuator.

FIG. 1 is a side view showing an embodiment of an ultrasonic motor driven by a driving device according to the present invention.
FIG. 2 is a perspective view of a vibrator used in the ultrasonic motor shown in FIG. First, the configuration of the vibrator 11 will be described with reference to FIG. The vibrator 11 includes an elastic body 12 and four piezoelectric bodies 13a, 13b, 13p, and 13p 'joined to the upper surface of the elastic body 12.

The elastic body 12 is a rectangular flat plate made of an elastic material such as a metal material or a plastic material. The elastic body generates a driving force for driving the relative motion member by simultaneously performing the fourth-order bending vibration and the first-order longitudinal vibration. On the lower surface of the elastic body 12, two rectangular parallelepiped driving force extracting portions 12 a and 12 b are formed in a protruding shape at positions where antinodes of fourth-order bending vibration occur. Further, the elastic body 12 is provided with cutout portions 12c and 12d having a semicircular cross section at a node position of primary stretching vibration (longitudinal vibration), that is, at a central portion in the longitudinal direction. The four piezoelectric bodies (13a, 13b, 13p, 13p ') are electromechanical transducers composed of PZT in the present embodiment. These piezoelectric bodies are connected to a driving force extracting portion (1) of the elastic body 12.
2a, 12b) are adhered to the surface opposite to the surface on which they are formed.

The piezoelectric bodies 13a and 13b are vibration-generating piezoelectric bodies. By applying a frequency voltage to these and vibrating them,
Flexural vibration and longitudinal vibration are excited in the elastic body 13. on the other hand,
The piezoelectric bodies 13p and 13p 'are piezoelectric bodies for detecting vibration generated in the elastic body 12 by a piezoelectric effect. The position where the piezoelectric body 13p is attached is
This is near the position where a is provided. Therefore, the vibration detected by the piezoelectric body 13p strongly reflects the characteristics of the vibration generated in the driving force output unit 12a. In contrast,
The position where the piezoelectric body 13p 'is attached is near the position where the driving force extraction unit 12b is provided, and the vibration detected by the position strongly reflects the characteristics of the vibration generated in the driving force extraction unit 12b. doing.

As shown in FIG. 1, the vibrator 11 is disposed on the upper surface of the relative motion member 21 and is supported by two support pins 29 fixed to the housing 40. The support pin 29 has its tip portion formed by the notch 12 of the elastic body 12.
By arranging the transducers at positions c and 12d, the transducer 11 is positioned in the left-right direction of the drawing and the direction perpendicular to the drawing. Note that the housing 40 is a part of the housing of the ultrasonic motor 1. A coil spring 28 is arranged on the outer periphery of the support pin 29. The coil spring 28 is in a compressed state, and forces the vibrator 11 downward in the drawing so that the driving force output portions 12a and 12b of the vibrator come into pressure contact with the upper surface of the relative motion member 21 with a predetermined pressure ( Pressure). The relative movement member 21 is a plate-shaped member, and its lower surface is supported by the rollers 30 so as to be movable in the left-right direction in the drawing.

Next, a driving device of the ultrasonic motor 1 will be described. FIG. 3 is a block diagram illustrating a driving device of the ultrasonic motor 1. First, referring to FIG.
Will be described. The controller 46 is a circuit that controls the overall operation of the drive device. The output of the controller 46 is connected to the oscillator 42. Oscillator 4
Reference numeral 2 denotes a circuit that outputs a drive signal (frequency voltage) having a frequency designated by an oscillation command from the controller 42. The output of the oscillator 42 is connected to the amplifier 44 and the phase shifter 43.

The amplifier 44 is a circuit for boosting the drive signal from the oscillator 42 to a predetermined voltage and applying the boosted signal to the piezoelectric body 13a. On the other hand, the phase shifter 43 is a circuit that outputs a signal having a predetermined phase difference from the drive signal input from the oscillator 42. The phase shifter 43 is also connected to the controller 46, and the magnitude of the phase difference
6 as determined by the instruction given. Phase shifter 43
Are connected to an amplifier 45. Amplifier 45
Is a circuit that performs the same function as the amplifier 44. That is, the amplifier 45 boosts the drive signal from the phase shifter 43 to a predetermined voltage, and applies this to the piezoelectric body 13b.

The selection circuit 47 is a circuit which selects one of the piezoelectric bodies 12p and 12p 'in accordance with a command from the controller 46 and inputs a detection signal (output) to the controller 46. Although not shown, the elastic body 12 is connected to the ground of the driving device 41.

Next, the operation of the driving device 41 when the ultrasonic motor 1 is driven to drive the relative movement member 21 rightward in FIG. 1 will be described. First, the controller 46 gives an oscillation command to the oscillator 42, and the oscillator 42 outputs a drive signal having a frequency specified by the oscillation command. Further, the controller 46 gives an instruction to the phase shifter 43 to output a signal whose phase is delayed by 90 ° with respect to the input signal.

Next, the drive signal output from the oscillator 42 is
An amplifier 44 is connected to the piezoelectric body 13a, and a phase shifter 43
And applied to the piezoelectric body 13 via the amplifier 45. Due to the application of the drive signal, the piezoelectric bodies 13a and 13b perform an oscillating motion at the same frequency. However, the vibration performed by the piezoelectric body 13b has a phase delay of 90 ° with respect to the vibration performed by the piezoelectric body 13a. As a result, the first-order longitudinal vibration and the fourth-order bending vibration are excited harmoniously in the elastic body 12, and the elliptic motion, which is a combination of these vibrations, is generated by the driving force extraction units 12 a and 12 b.
Occurs on the end face of As described above, since the driving force output portions 12a and 12b are in pressure contact with the relative motion member 21, the relative motion member 21 is driven in the right direction in the drawing by the elliptical motion.

On the other hand, the selection circuit 47 includes a controller 46
Receives information that the relative motion member 21 is driven in the right direction in the drawing. As a result, the selection circuit 47 selects the piezoelectric body 13p 'on the side of the direction in which the relative motion member 21 moves, and inputs a detection signal thereof to the controller 46. The controller 46 obtains the effective value of the voltage of the detection signal input from the selection circuit 47. This effective value is a value representing the speed of the relative motion member 21. The obtained effective value is compared with a value set in a memory or the like of the controller 46 in advance. If the values do not match, the controller 47 gives an appropriate oscillation command to the oscillator 42 and changes the frequency of the drive signal generated by the oscillator 42 so that the two values match, ie, the relative motion The operation of the ultrasonic motor 1 is controlled so that the speed of the member 21 becomes a predetermined value.

Next, the operation of the driving device 41 when the relative movement member 21 is driven in the left direction on the paper of FIG. 1 will be described. In this case, the controller 46 gives a command to the phase shifter 43 to output a signal whose phase is advanced by 90 ° with respect to the input signal, and the piezoelectric body 13b
Vibration advanced by 90 ° with respect to the vibration is performed. As a result, the rotation direction of the elliptical motion generated on the end faces of the driving force extracting portions 12a and 12b is opposite to that described above, and the relative motion member 21 is driven in the left direction on the paper. On the other hand, the controller 46 has the selection circuit 47
Gives the information that it is driven in the left direction on the paper. As a result, the selection circuit 47 selects the piezoelectric body 13p on the side of the relative movement member 21 in the traveling direction, and inputs the detection signal to the controller 46. Therefore, in this case, the controller 46 controls the operation of the ultrasonic motor 1 based on the detection signal output from the piezoelectric body 13p.

As described above, in the driving device 41 of the present embodiment, the selection circuit 47 has two vibration detecting piezoelectric members (12) according to the direction in which the relative movement member is driven.
p, 12p '). The controller 47 controls the operation of the ultrasonic motor 1 based on the selected detection signal of the piezoelectric body, and adjusts the speed at which the relative motion member is driven. Here, the piezoelectric body selected by the selection circuit 47 is a piezoelectric body attached to the vibrator 11 on the side of the direction in which the relative motion member moves.
More specifically, the piezoelectric body selected by the selection circuit 47 is a piezoelectric body attached near the driving force extracting portion provided on the vibrator 11 on the side of the direction in which the relative motion member moves. In other words, the selection circuit 47 determines the vibration characteristics of the driving force take-out unit that most contributes to driving the relative motion member,
The piezoelectric material that reflects the best is selected, and the detection signal is input to the controller 46. As a result, the controller 46
Can accurately detect the speed of the relative motion performed by the relative motion member irrespective of the direction, and can appropriately control the operation of the ultrasonic motor 1 so that the speed coincides with a predetermined value.

(Other Embodiments) The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

1) In the above embodiment, the case where the selection circuit determines the piezoelectric body to be selected in accordance with a command from the controller has been described. However, this is because the selection circuit is a changeover switch, and is manually operated by an external operation. The selected piezoelectric body may be switched. Further, the selection circuit determines a piezoelectric body to be selected based on an output of an encoder or other sensor for detecting a moving direction of the relative moving member, and a piezoelectric body to be selected according to a phase difference command given to the phase shifter 43 by the controller. The body may be defined, or a piezoelectric body to be selected according to a command received from an external computer or the like through communication may be defined. Further, the selection circuit may inspect the piezoelectric body for detecting vibration before driving the ultrasonic motor, and select one or more piezoelectric bodies having good performance.

2) In the above-described embodiment, an example has been described in which the piezoelectric bodies (12p, 12p ') for vibration detection are both used to detect the same information of the speed of relative motion. This may be that the two piezoelectrics are used to detect different information. For example, one piezoelectric body is attached to an elastic body at a position where mainly longitudinal vibrations can be detected, and the other piezoelectric body is attached to an elastic body at a position where bending vibrations can be mainly detected. It may be to detect the pressing force between the and the relative motion member.

[0029]

As described above in detail, according to the present invention, the driving device detects the state of the relative motion most appropriately in accordance with the direction of the relative motion of the vibration actuator with respect to the relative motion member. Since the operation of the vibration actuator is controlled using the output of the selected vibration detector, the vibration actuator can always be appropriately controlled regardless of the direction of the relative motion.

[Brief description of the drawings]

FIG. 1 is a side view showing an ultrasonic motor driven by a driving device according to the present invention.

FIG. 2 is a perspective view of a vibrator used in the ultrasonic motor shown in FIG.

FIG. 3 is a block diagram showing a driving device according to the present invention.

FIG. 4 is a perspective view showing a vibrator of a conventional vibration actuator.

[Explanation of symbols]

 41 Driver 42 Oscillator 43 Phase shifter 44, 45 Amplifier 46 Controller 47 Selection circuit

Claims (10)

[Claims] 1. A vibration actuator that performs relative movement with a relative motion member by bringing the vibrator into contact with the relative motion member, wherein the vibration actuator includes at least two vibration detectors. A processing unit that processes the output of the vibration detector; and a selection unit that selects one or more of the vibration detectors, wherein the processing unit is selected by the selection unit. A driving device for processing output information of a vibration detector. 2. The driving device according to claim 1, wherein the processing unit controls a speed of the vibration actuator based on an output of the vibration detector selected by the selection unit. apparatus. 3. The driving device according to claim 1, wherein the selection unit changes the selected vibration detector in accordance with a driving state of the vibration actuator. . 4. The driving device according to claim 1, wherein the selection unit changes the selected vibration detector in accordance with a direction of the relative movement. 5. The method according to claim 1, wherein:
In the driving device described in the paragraph, the vibrator has a flat or columnar elastic body that excites longitudinal vibration and bending vibration and generates an elliptical motion in a driving force extraction unit provided at a predetermined position, The relative movement member is brought into contact with the driving force take-out unit to perform the relative movement, and the selection unit is one or two provided on the rear side of the vibrator with respect to the direction of the relative movement. A driving device, wherein the above-mentioned vibration detector is selected. 6. The driving device according to claim 5, wherein the selection unit is provided in the vicinity of the driving force extraction unit located on the rear side of the vibrator with respect to the direction of the relative movement. A driving device, wherein two or more vibration detectors are selected. 7. The driving device according to claim 5, wherein the vibrator has a shape that is symmetrical in the front-rear direction with respect to a direction of the relative movement, and the at least two vibration detectors include the vibrator. A driving device provided at a position symmetrical in the front-rear direction with respect to the direction of the relative movement. 8. An elastic body that performs a predetermined vibration, two or more output extraction units provided at different positions of the elastic body, and 2 that detects different vibration characteristics of the output extraction units.
A vibration actuator comprising the above-described vibration detector and performing relative movement with the relative movement member by bringing the output extraction portion into contact with a relative movement member, wherein the output extraction portion acts on the relative movement member. In a driving device for driving a vibration actuator, in which a rate of a force contributing to the relative motion is different depending on a direction of the relative motion, a control unit for controlling an operation of the vibration actuator, wherein a force contributing to the relative motion is maximum. A selection unit that selects the vibration detector that detects a vibration characteristic of the output extraction unit, wherein the control unit controls the operation of the vibration actuator based on an output of the vibration detector selected by the selection unit. A drive device characterized by controlling. 9. The driving device according to claim 8, wherein the selection unit selects the vibration detector based on information on the direction of the relative movement obtained from the control unit. . 10. The driving device according to claim 8, wherein the control unit supplies the vibration actuator with a first driving signal and a second driving signal having a phase difference from the first driving signal. The drive device controls the direction of the relative motion based on the sign of the phase difference, and the selection unit selects the vibration detector based on information on the sign of the phase difference.