JP2001268955A - Vibration motor, positioning device and method of controlling vibration motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of increasing the stop time when utilizing the control of a DC servo motor for the stop control of a positioning device utilizing an ultrasonic motor. SOLUTION: There are provided an ultrasonic motor 33 comprising a vibrator 31, a mover 32 and a drive control device 61 which prohibits input of a drive signal to the vibrator 31 after the motor 32 reaches the allowable range of positioning set to the range of the predetermined distance from the target position and a positioning device 30 provided with a movable stage 34 to be driven with the ultrasonic motor 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration motor, a positioning device, and a method for controlling a vibration motor. More specifically, the present invention relates to a vibration motor including a vibrator that generates vibration when a drive signal is input, and an ultrasonic motor suitable for application to a switching device for an information transmission path such as an optical fiber. The present invention relates to a positioning device using a vibration motor and the like, and a method for controlling the vibration motor.

[0002]

2. Description of the Related Art Generally, in order to position a positioning target at a target position using a servomotor such as a DC servomotor as a drive source of a positioning device, a servo loop is formed based on a positional deviation from the target position. By configuring
The drive control of the motor is performed so that the position deviation becomes zero. Then, when the position deviation becomes 0, the driving of the motor is stopped while the servo control is being performed. At this time, if the stop position of the servomotor fluctuates due to disturbance, the motor operates to immediately reduce the generated position deviation to zero. For this reason, in the positioning device using the servomotor, power is always consumed even though the positioning target is very close to the target position.

On the other hand, in a vibration motor, a two-phase driving signal (AC voltage) composed of a continuous wave having a different phase (π / 2) and a predetermined frequency is generally applied to two kinds of piezoelectric elements. By inputting each of them, two standing waves having different phases are excited in the elastic body on which these piezoelectric elements are mounted, and these standing waves are combined to generate an elliptic motion generated in the driving force extracting portion of the elastic body. Is used to frictionally drive the relative motion member that comes into pressure contact with the driving force take-out portion. As this type of vibration motor, an ultrasonic motor using an ultrasonic vibration region is known, and the following description will use this ultrasonic motor as an example.

After stopping at a target position, the ultrasonic motor simply stops the electric input to the piezoelectric element, does not drift, and continues to stop at that position without being disturbed by external force. Has retention properties. For this reason,
It is promising to use this ultrasonic motor as a drive source of a positioning device.

In order to position an object to be positioned at a target position by using an ultrasonic motor as a driving source of a positioning device, the conventional control of a servomotor is directly used.

[0006]

However, if the conventional servomotor control is applied to an ultrasonic motor as it is, feedback control is performed so that the position deviation converges to zero. It increases and decreases in terms of vibration, and the time required to enter a positioning allowable range set within a predetermined distance from the target position is lengthened.

FIG. 11 shows a commanded position, a detection speed of a positioning object and a position deviation (deviation between the commanded position and the current position), a time and a time when the conventional servomotor control is applied to the ultrasonic motor as it is. 6 is a graph showing an example of the relationship.

[0008] As shown in the graph of FIG.
Time t₀Is activated at the position while following the command position.
The object to be determined moves toward the target position and the time t₁At position
Despite being within the allowable range P, the servo control
For control, the ultrasonic motor_Two, T_ThreeAnd t_FourTo
At the time t when the vibration has attenuated _Five
At this time, it finally stops within the positioning allowable range P. This
Therefore, from the time the positioning tolerance is reached (t_Five−
t₁) The stop time until the time elapses has become longer
I will. Prolonging the stop time requires a positioning device such as an optical
This is an important technical problem of the fiber switching terminal driving device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration motor such as an ultrasonic motor capable of stopping at a target position in a short time, a method of controlling the vibration motor, and a method of moving a positioning object to a target position using the vibration motor in a short time. And a positioning device that can be stopped at the same time.

[0010]

According to the present invention, the servo control is continued even after the vibrator or the relative moving member of the vibration motor reaches a positioning allowable range set within a predetermined distance from the target position. Instead, it is based on a new and important finding that the above-mentioned problem can be solved by prohibiting the input of the drive signal to the vibrator.

According to a first aspect of the present invention, there is provided a vibrator for generating a vibration by receiving a drive signal, a relative motion member for generating a relative motion by pressing the vibrator, and a vibrator or a relative motion member. A drive control device for prohibiting the input of a drive signal to the vibrator after reaching a positioning allowable range set within a range of a predetermined distance from the target stop position. I do.

According to a second aspect of the present invention, in the vibration motor according to the first aspect, the drive control device controls the drive to the vibrator after the speed of the vibrator or the relative motion member is reduced to a predetermined speed. It is characterized in that input of a signal is prohibited.

[0013] The invention of claim 3 is claim 1 or claim 2.
In the vibration motor described in the above, there is a vibrator or a relative motion member displaced by the mechanical vibration generated when the input of the drive signal to the vibrator is stopped at the predetermined speed is within the positioning allowable range. Speed.

According to a fourth aspect of the present invention, there is provided a positioning apparatus comprising: the vibration motor according to any one of the first to third aspects; and a movable stage driven by the vibration motor. It is.

Further, according to the fifth aspect of the present invention, the vibrator which receives the drive signal and generates vibration or the relative movement member which generates relative movement by pressurizing and contacting the vibrator is provided at a predetermined position from the target stop position. A method of controlling a vibration motor, comprising: prohibiting input of a drive signal to a vibrator after reaching a positioning allowable range set in a distance range.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, an embodiment of a positioning device using a vibration motor according to the present invention will be described in detail with reference to the accompanying drawings. In the following description of the embodiments, an example in which an ultrasonic motor using an ultrasonic vibration region is used as a vibration motor, and the positioning device according to the present invention is applied to an optical fiber switching device will be described. .

FIG. 1 shows a positioning device 30 according to this embodiment.
1 is a perspective view showing a simplified state in which a part is seen through. 2 is a view as viewed in the direction of the arrow A in FIG. 1, and FIG. 3 is a view as viewed in the direction of arrow B in FIG.

As shown in FIGS. 1 to 3, the positioning device 30 of this embodiment has an ultrasonic motor 33 and a movable stage 34. Hereinafter, these components of the positioning device 30 of the present embodiment will be sequentially described.

[Ultrasonic motor 33] Ultrasonic motor 33
Has a vibrator 31, a mover 32, and a vibrator fixing member 42. Hereinafter, these will be sequentially described.

(I) Vibrator 31 FIG. 4 shows the vibrator 31 and the mover 32 in this embodiment.
It is a perspective view which shows each structure. FIG. 5 is an explanatory view of the vibrator 31. FIG. 5A is a top view, and FIG.
FIG. 5B is a side view, and FIG. 5C is an explanatory diagram showing waveform examples of two different vibrations L1 and B4 generated in the vibrator 31.

As shown in FIGS. 1 to 5, the vibrator 31 used in this embodiment includes an elastic body 35 and an elastic body 35.
And a piezoelectric body 36 mounted on one of the flat surfaces. The elastic body 35 is desirably made of a metal material having a large resonance sharpness such as steel, stainless steel, phosphor bronze, or Elinvar material, and is formed in a rectangular flat plate shape. The dimensions of each part of the elastic body 35 are set such that the natural frequencies f _L1 and f _B4 of the generated primary longitudinal vibration L1 and the generated quaternary bending vibration B4 substantially coincide with each other.

A piezoelectric body 36 is provided on one plane of the elastic body 35.
Is mounted, for example, by bonding. In the other plane of the elastic body 35, two grooves are provided in the width direction of the elastic body 35 at a predetermined distance from each other in the relative movement direction (the left and right directions in FIGS. 2, 4 and 5). In each of these grooves, a rod-shaped sliding member having a rectangular cross-sectional shape, which is mainly composed of a polymer material, is fitted and mounted, and is mounted so as to protrude. As the polymer material, PTF
Polymer materials such as E, polyimide resin, polyacetal, PPS, and PEEK are exemplified.

The sliding member is used as a driving force extracting portion 37.
Functions as a and 37b. Therefore, the elastic body 35 comes into pressure contact with the moving element 32 via the driving force extracting portions 37a and 37b formed of these sliding members.

As shown in FIG. 3, each of the driving force extracting portions 37a and 37b is divided into two in the width direction of the vibrator 31, and each of the divided driving force extracting portions 37a and 37b is divided into two.
a, 37 a ′, 37 b, and 37 b ′ are arranged on the end side in the width direction of the vibrator 31. Thus, in the present embodiment,
Each of the driving force extracting portions 37a and 37b is constituted by two sliding members.

These driving force take-out portions 37a, 37b
Figure 5 (B) and FIG. 5 as shown in (C), 4 single loop position l ₁ to l ₄ of the fourth order bending vibration B4 generated in the elastic member 35
Are respectively provided at positions corresponding to the two antinode positions l ₁ and l ₄ located outside. In addition, the driving force extracting unit 3
7a and 37b are two antinode positions l ₁ and l of the bending vibration B4.
_It is not necessary to be provided at a position exactly corresponding to ₄ , and it may be provided near these antinode positions l ₁ and l ₄ .

In the present embodiment, the piezoelectric body 36 is composed of a single thin plate-shaped piezoelectric element made of PZT (lead titanium zirconate). As shown in FIGS. 4 and 5, the input regions 36a and 36c to which the A-phase drive signal _VA is input and the A-phase drive signal have a phase of about (π /
2) input drive signal V _B of the shifted phase B are input area 3
6b and 36d are formed. Each input area 36a-36
As shown in FIGS. 5 (A) to 5 (C), d is continuous with four regions defined by _five nodal positions n _{1 to} n ₅ of bending vibration B4 generated in elastic body 35. Formed. That is, each input region 36a~36d be deformed by input of the driving signal are both, it does not cross the nodal position n ₁ ~n ₅ is fixed point. Therefore, the input area 36a-
Never deformation 36d is suppressed by nodal positions n ₁ ~n _5. Thereby, the electric energy input to each of the input areas 36a to 36d can be converted into the mechanical energy of the elastic body 35 with maximum efficiency.

At the nodes n ₂ and n ₄ of the bending vibration B4, detection areas 36p and 36p 'for outputting electric energy by the longitudinal vibration L1 generated by the vibrator 31 are provided.
Thereby, the vibration state of the longitudinal vibration L1 generated by the vibrator 31 is monitored.

FIGS. 4, 5A and 5B
As shown in the figure, each of the input areas 36a to 36d and each of the detection areas 36p and 36p '
a to 38d, 38p and 38p '. As a result, it is possible to input a drive signal to each of the input regions 36a to 36d independently, and to output a detection signal independently from each of the detection regions 36p and 36p '. In addition, in order to simplify a drawing and to make it easy to understand, in FIGS. 1-3, silver electrode 38a-38d, 38p, and 38p 'are all omitted.

Lead wires 39a-39d for transmitting and receiving electric energy are connected to the silver electrodes 38a-38d by soldering, and lead wires (not shown) are connected to the silver electrodes 38p and 38p '. .) Are connected by soldering.

In this embodiment, as shown in FIG. 5A, the vibrator 31 is formed so as to be point-symmetric about the center of the plane. As a result, the elliptical motions generated in the respective driving force extracting portions 37a, 37a ', 37b, 37b' can be made to have substantially the same shape, and the driving difference due to the reversal of the relative motion direction is almost eliminated.

As will be described later with reference to FIG. 7, the drive control device 61 of the positioning device 30 applies the longitudinal vibration L1 and the bending vibration B to the input areas 36a and 36c of the piezoelectric body 36.
4 A having a frequency substantially coincident with each natural frequency
The phase drive signal _VA is input. Also, the input area 36
b, and the 36d, the drive signal of the A-phase driving signal V _B of the B phase having a phase difference of (π / 2) is input. Then
As shown in FIG. 5C, the elastic body 35 has a primary longitudinal vibration L1, which is the first vibration vibrating in the relative movement direction (the horizontal direction in FIG. 5), and is orthogonal to the relative movement direction. Fourth-order bending vibration B4, which is the second vibration that vibrates in the vertical direction, that is, in the direction parallel to the pressing direction of the vibrator 31 and the moving element 32, is simultaneously generated.

The generated longitudinal vibration L1 and bending vibration B4 are combined, and the driving force extracting portions 37a and 37a 'and the driving force extracting portions 37b and 37b' are combined as shown in FIG. 5B. Elliptic motions whose phases are shifted by π are generated. As a result, the vibrator 31 comes into contact with the moving element 32 under pressure.
, A linear motion relative to the vibration direction of the longitudinal vibration L1 is generated. To reverse the relative movement direction,
The B-phase drive signal is (−π /
What is necessary is just to set so that it may have the phase difference of 2).

As described above, the vibrator 31 of the present embodiment is
Longitudinal vibration L1, which is the first vibration oscillating in the direction of relative motion
And a bending vibration B4, which is a second vibration vibrating in a direction orthogonal to the vibration direction of the first vibration, to generate a linear relative motion with the moving element 32.
This is a so-called deformed mode degenerate type vibrator.

(Ii) Moving Element 32 As shown in FIGS. 1 to 5, in the present embodiment, as a relative movement member that performs relative movement with the vibrator 31,
The moving element 32 is used. FIG. 6 is a perspective view extracting and showing the movable element 32 and the movable stage 34.

The moving element 32 is made of stainless steel, a copper alloy, an aluminum alloy, or the like.
Is fixed by three flat small screws 40 to the slider mounting surface 34a.

In the present embodiment, as shown in FIG. 6, any one of the driving force extracting portions 37a and 37a 'and the driving force extracting portions 37b and 37b' on the contact surface of the moving element 32 with the vibrator 31. The cross-shaped non-contact portion 41c which does not contact the driving force extracting portions 37a, 37a 'and the driving force extracting portions 37b, 3b.
7b 'contacting any one of the contact portions 41a, 41a',
It is formed thinner than 41b and 41b '. Thereby, the contact surface of the moving element 32 with the vibrator 31 is shown in FIGS.
As shown in FIGS. 4 and 6, it is formed in a cross-shaped groove shape. That is, the protrusions 41 a to 41 b ′ are formed at the four corners of the contact surface of the movable element 32 with the vibrator 31. In the present embodiment, as described later, the moving element 3
Although a cross-shaped groove is formed on the contact surface with the second vibrator 31, the groove is hardly vibrated at the nodes.
Because the movable element 32 is mounted on the movable element mounting surface 34a of the movable stage 34 having an L-shaped cross-sectional shape having a large second moment of area, the movable element 32 is not subjected to bending vibration due to bending deformation. do not do.

As will be described later with reference to FIGS. 1 to 3, the movable element 32 includes driving force extracting portions 37a and 37a 'of the vibrator 31 supported by pressure by the oscillator fixing member 42 and a driving force extracting portion. 37b and 37b ', the projections 41a to 41
It is arranged in pressure contact with an appropriate pressing force via b ′.

As a result, when the vibrator 31 is activated, the moving element 32 causes the driving force extracting portions 37a and 37a 'and the driving force extracting portions 37b and 37b' to move in an elliptical manner by shifting their phases by π. The projections 41a to 41
Driven through b ′. For this reason, the moving element 32 includes a linear guide 55 fixed on a base substrate 60 described later.
The movable stage 34 is linearly driven together with the movable stage 34 guided linearly. As described above, in the present embodiment, the movable element 32 is linearly driven by the vibrator 31 that is fixedly arranged.

In this embodiment, the oscillator 31 of the movable element 32
By forming a cross-shaped groove on the contact surface of the positioning device 30, the weight of the moving element 32 forming a part of the moving system of the positioning device 30 is reduced. Thereby, the settling time of the movable stage 34 that moves together with the movable element 32 is reduced.

In a case where the contact surface of the moving element 32 with the vibrator 31 is mirror-finished by lapping in order to improve the contact state with the vibrator 31, in the present embodiment, the projections 41a to 41b You only need to apply this wrap to the bottom of '. For this reason, the area of the lapping processing is reduced, and the processing time of the mirror finish by the lapping processing can be shortened.

Further, since each of the projections 41a to 41b 'has a considerably smaller mass than the vibrator 31,
The natural frequency of each of the protrusions 41a to 41b 'is higher than the frequency of the ultrasonic wave of the vibrator 31 (for example, about 50 kHz). For this reason, even if the vibration generated by the vibrator 31 is transmitted to the projections 41a to 41b 'via the driving force extraction units 37a and 37a' and the driving force extraction units 37b and 37b ', the projections 41a to 41b' In any case, vibrations (low-frequency vibrations) that hinder driving hardly occur. Therefore, the vibration of the movable stage 34 due to the vibration generated by the vibrator 31 is also suppressed. For this reason,
The vibration of the movable stage 34 is suppressed,
Can be positioned with high accuracy.

(Iii) Vibrator fixing member 42 As shown in FIGS. 1 to 3, the vibration motor 30 of the present embodiment
Has a transducer fixing member 42. Vibrator fixing member 42
Is a block having an L-shaped horizontal cross-sectional shape, and is made of a metal material such as an aluminum alloy or stainless steel.
The vibrator fixing member 42 includes a vibrator support member 43 and a vibrator pressing member 44.

As shown in FIGS. 1 to 3, the vibrator support member 43 is a thin plate made of a metal material such as an aluminum alloy or stainless steel, and has a small bent portion 43a.
And a supporting portion 43b having a large plate thickness. Bend 43
Two through-holes are provided at one end of “a”, and the vibrator support member 43 is fixed to the end face of the vibrator fixing member 42 by fixing screws 43c that respectively penetrate these through-holes.

On the plane of the support portion 43b on the vibrator 11 side, two support pins 45a, 45b made of stainless steel are provided.
Are fixed by appropriate means such as adhesion or welding.
The support pins 45a and 45b are fitted into two notches 31a and 31b (see FIG. 5A) on a semicircle formed at substantially the center in the longitudinal direction of both sides of the vibrator 11. Then, it is fixed by appropriate means such as adhesion or welding.

Note that an insulating member 46 made of, for example, plastic or the like is interposed between the piezoelectric body 36 mounted on one plane of the vibrator 31 and the support portion 43b. Short circuit of 36b and 36c is prevented.

The vibrator 31 is constrained by the vibrator support member 43 in the direction of the relative motion (the left-right direction in FIG. 2), and the bending portion 43a is bent and displaced in an arc shape so that the pressing direction (FIG. (Up-down direction in FIG. 3) so as to be able to be displaced minutely and substantially linearly.

On the other hand, as shown in FIGS. 1 to 3, the vibrator pressing member 44 is a plate material having pressing protrusions 47a to 47d at four corners. The pressing projections 47a to 47d are arranged at the four corners of the vibrator pressing member 44 because the electrodes 38a to 38d
This is to prevent interference between the raised portions of the soldering between the lead wires 39a to 39d and the lead wires 39a to 39d.
Pressurizing protrusions 47a and 47c are in a position to match the position of the nodal position n ₂ of the bending vibration B4 generated in the oscillator 31, also pressurizing protrusions 47b and 47d are of the bending vibration B4 generated in the oscillator 31 a position coinciding with the position of the node position n _4, provided respectively in contact with the vibrator 31. In other words, the pressurizing protrusion 47a~47d are both are formed at positions across the section position n _2, n ₄ of the bending vibration B4.

The bent portion 43a of the vibrator support member 43
Is provided with a through-hole 43d.
Each of the pressurizing projections 47b and 47d of the piezoelectric body 3 attached to the vibrator 31 passes through the through hole 43d.
Contact 6 Thereby, the contact between the vibrator support member 43 and the vibrator pressing member 44 is prevented.

As shown in FIG. 2, a pressure generating member 48 is mounted in a receiving hole 42a provided substantially at the center of the plane of the transducer fixing member 42 on the transducer pressing member 44 side. In the present embodiment, a coil spring is used as the pressing force generating member 48. The pressing force generating member 4 of the vibrator fixing member 42
A screw member 49 is screwed to a contact portion with the screw member 8, and by adjusting the screwing depth of the screw member 49, the pressing force generated by the pressing force generating member 48 can be appropriately adjusted. ing.

The vibrator pressing member 44 is urged toward the vibrator 31 by the pressing force generated by the pressing force generating member 48. As a result, the vibrator 31 is brought into press contact with the protrusions 41a to 41b 'of the moving element 32 by the pressurizing force by the pressurizing protrusions 47a to 47d via the driving force extracting portions 37a to 37b'.

The vibrator fixing member 42 is fixed to the base substrate 60 by two mounting screws 42b. Thus, the vibrator 31 and the mover 32 are supported at a certain distance from the surface of the base substrate 60.

As described above, in this embodiment, the vibrator 31 is supported by the vibrator fixing member 42 including the vibrator support member 43 and the vibrator pressing member 44. That is, the ultrasonic motor 33 of the present embodiment linearly moves between the vibrator 31 having the driving force take-out portion and the vibrator 31 by pressing the vibrator 31 through the driving force take-out portion. And a vibrator fixing member 42 for bringing the vibrator 31 into pressure contact with the vibrator 32.

In the present embodiment, the vibrator fixing member 4
2, a relay board 50 is fixed. The relay board 50
The lead wire 39 and the drive control device 61 of the positioning device 30
And the drive control device 6
The drive signal from 1 is input to the piezoelectric body 36. When the relay board 50 is made of an insulating material having a low thermal conductivity such as glass, alumina, ceramic or silicone, for example, a temperature sensor (not shown) is provided on the relay board 50 for driving. By detecting the environmental temperature near the vibrator 31 and using the detected value as a feedback control factor of the drive signal from the drive control device 61, more accurate control can be performed.

[Movable stage 34] FIGS. 1 to 3 and 6
As shown in (1), the positioning device 30 of the present embodiment has a movable stage 34.

The movable stage 34 is made of a light metal material such as an aluminum alloy and is lightweight. In the present embodiment, the movable stage 34 includes a movable member mounting surface 34a which is a first plane to which the movable member 32 is fixed, and a mounting surface 3 which is a second plane substantially orthogonal to the movable member mounting surface 34a.
4b, and is formed to be bent in an L-shape as shown in FIG. For this reason, as shown in FIG. 3, when the plane perpendicular to the direction of the relative motion is viewed as a cross section, the second moment of area is large, and the sliding surface has high rigidity against bending. Therefore, the moving element mounting surface 34a is
Even if it receives a pressing force due to the bending vibration B4, which is the second vibration generated by 1, vertically, it is difficult to deform.

As shown in FIG. 6, the moving element mounting surface 34a is provided with nothing except a screw hole for screwing the three flat small screws 40 for mounting the moving element 32. It is said that.

On the other hand, the mounting surface 34b extends in the direction in which the vibrator 31 and the moving element 32 are pressed, that is, in the direction parallel to the vibration direction of the bending vibration B4. This mounting surface 34
A guide 53 is fixed to the substantially central portion of the lower surface of b by four screws 52. The guide 53 is fitted on a rail 54 laid on the base substrate 60 in a direction parallel to the direction of the relative movement, and forms a linear guide 55 together with the rail 54. Therefore, the movable stage 34 is supported by the linear guide 55 so as to be movable in a direction parallel to the direction of the relative movement.

The switching terminal 56 of the optical fiber 56a is mounted on the mounting surface 34b. The switching terminal 56 is formed in a rectangular parallelepiped shape by, for example, a resin material, and is fixed and mounted in a state where the end of the optical fiber 56a on the input side is penetrated.

In this embodiment, as the optical fiber 56a, a core provided at the center and having a refractive index of n ₁ and a clad provided at the outer periphery of the core and having a refractive index of n ₂ (n ₂ <n ₁ ). A step-type optical fiber having a cladding and a jacket provided on the outer periphery of the cladding and made of a material having much more light absorption than the cladding is used.

The four switching terminals 58 of each of the four optical fibers 58a are mounted on the support 57 fixed to the base substrate 60 such that the four switching terminals 58 have the same installation height as the switching terminals 56 of the optical fiber 56a. Is done. Each switching terminal 58
Are formed in a rectangular parallelepiped shape by, for example, a resin material, and are fixed and mounted in a state where the ends of the four optical fibers 58a are respectively penetrated. On one end face of each switching terminal 58, an end face of each optical fiber 58a is arranged so as to be on the same plane. This optical fiber 58a
Like the optical fiber 56a, it is a step-type optical fiber.

Although FIGS. 1 to 3 show a case where four switching terminals 58 are arranged in parallel to simplify the drawings and facilitate understanding, the present invention is not limited to this. The same applies to a case where two, three, five or more switching terminals are arranged in parallel.

On the base substrate 60, a light emitting portion 59a and a light receiving portion 59b constituting a detecting portion of the transmission type encoder 59 are opposed to each other with a scale portion 59c fixed to a vertical flange 34c of the movable stage 34 interposed therebetween. Placed. The current position of the movable stage 34 is detected by the encoder 59. The detected value is output to the drive control device 61 of the positioning device 30, and the drive of the ultrasonic motor 33 is controlled.

In the present embodiment, the rigidity of the movable stage 34 is increased by bending the movable stage 34 into an L-shape by the moving element mounting surface 34a and the mounting surface 34b. Further, the mounting surface 34b has a structure in which the mounting surface 34b projects perpendicularly to the moving member mounting surface 34a. For this reason, even if a notch or a hollow portion is provided on the mounting surface 34b for weight reduction, the bending rigidity of the moving member mounting surface 34a can be sufficiently maintained, and the impact due to the clutch function of the vibration motor 33 can be obtained. However, the vibration caused by the deformation of the moving element mounting surface 34a
b is a structure that is unlikely to occur (especially bending). Therefore, in this embodiment, of the mounting surface 34b, a portion other than the mounting portion of the switching terminal 56 and the mounting portion of the guide 53, that is, a portion located above the light receiving portion 59b, the light emitting portion 59a and the support base 57 A hollow portion 34d and a cutout portion 34e are respectively provided between the two. For this reason, according to the present embodiment, the vibration caused by the clutch function of the vibration motor 33 does not occur on the movable stage 34 and the movable stage 3
4 can be reduced in weight.

In this embodiment, as shown in FIGS. 1 to 3 and 6, the hollow portion 34d and the notch 34e are
In each case, the center of gravity of the movable stage 34 is brought close to the position directly above the rail 54 of the linear guide 55 because the center of gravity of the movable stage 34 is provided on the plane of the movable stage 34 opposite to the vibrator mounting surface 34 a with respect to the mounting portion of the linear guide 55. be able to. Thereby, the movable stage 3 immediately before the stop
4 can be reduced. For this reason, according to the present embodiment, the movable stage 34 can be stopped without generating a displacement that rotates around the center of gravity, and the positioning accuracy of the movable stage 34 can be improved.

As described above, the movable stage 34 is fixed to the moving element 32 and extends in a direction substantially parallel to the direction in which the vibrator 31 and the moving element 32 are pressed. The movable element 31 is supported so as to be linearly movable in a direction substantially parallel to the direction of the relative movement between the movable element 31 and the movable element 32.

FIG. 7 is a block diagram showing an example of the drive control device 61 of the positioning device 30 of the present embodiment. FIG. 8 is a flowchart of the CPU 62 of the drive control device 61.

In step (hereinafter abbreviated as "S") 1 in FIG. 8, the CPU 62 of the drive control unit 61 inputs commands for the target position and operating conditions (acceleration / deceleration, maximum speed, etc.) from the upper command device 63. Is done. Also, the CPU 62
Outputs a digital signal based on the deviation between the target position and the count value of the encoder 59 from the counter 68. Then, the process proceeds to S2.

In S2, the CPU 62 calculates a movement amount, which is the difference between the target position and the current position, based on the value detected by the encoder 59. Then, the process proceeds to S3. S3
In, the CPU 62 sets an operating speed profile when the moving amount calculated in S2 is moved under the operating conditions (acceleration / deceleration, maximum speed, etc.) input in S1.

FIG. 9 is a graph showing an example of the set operation speed profile and command position. As shown by the graph in FIG. 9, in S3, the command position with respect to time is determined. Then, the process proceeds to S4.

In S4, the CPU 62 sets the drive frequency to the initial value f ₀ (on the higher frequency side than the resonance frequency),
A digital signal is output to the D / A converter 64 in FIG. The D / A converter 64 converts a digital signal into an analog voltage signal and outputs the signal to the VCO 65. VCO6
5 generates two frequency signals corresponding to the voltage value of the analog voltage signal input from the D / A converter 64 and outputs the two frequency signals to the amplifier 66A and the phase shifter 67. The phase shifter 67 shifts the phase of the input frequency signal by (± π / 2). And. The drive signal of the A phase from the amplifier 66A
a, 36c applied to the silver electrodes 38a, 38c;
The driving signal of the B phase is supplied from the amplifier 66B to the input areas 36b, 3b.
The voltage is applied to the 6d silver electrodes 38b and 38d. As a result, the vibrator 31 is excited, and the driving force extracting portions 37a to 37
a moving member 32 which comes into pressure contact with the moving member b '
The movable stage 34 fixed to 2 is linearly driven together.

In S5, the CPU 62 sets the counter 6
8 until the driving of the movable stage 34 is confirmed to be started by the encoder 59 via Δ8.
Sweep by one. Then, after the start of driving is confirmed, S6
Move to

In S6, the CPU 62 calculates a deviation e, which is a deviation between the command position and the detected position at each time, based on the detected value of the encoder 59. And S7
Move to

In S7, the CPU 62 arbitrarily sets the control gain α, and sets the drive frequency f based on the deviation e calculated in S6. And the driving frequency f
While changing the speed so that the deviation e becomes zero. Then, control goes to a step S8. The method of determining the drive frequency f is not limited to this, and an arbitrary expression can be set based on the deviation e.

In S8, the CPU 62 confirms that the detected position has reached a preset allowable positioning range. Then, if it has not arrived, the process proceeds to S6, and if it has reached, the process proceeds to S9. That is, in S8, it is confirmed that the movable stage 34 has reached a positioning allowable range set within a range of a predetermined distance from the target position.

In S9, the CPU 62 confirms that the detected speed has reached a preset stop speed. Here, the movable stage 3 driven by the ultrasonic motor 33
When the motion at the time of stop of No. 4 is replaced by the vibration of the one-degree-of-freedom system of the spring-mass system on which the viscous damping force acts, the mass is m
Where k is the spring constant and c is the viscous damping coefficient.
The equation of motion is: (c / m) = 2μ, p = √ (k / m)
The following equation (1) is obtained.

X ″ + 2μx ′ + p ² x = 0 (1) When this equation (1) is solved, if μ <0, the solution is given as the following equation (2) .

[0077]

(Equation 1) Therefore, the stop speed in S9 is a speed at which the vibrator displaced by the mechanical vibration generated when the input of the drive signal to the vibrator 31 is stopped exists in the above-described predetermined positioning allowable range. Specifically, for example,
The speed v at which the deviation falls within the positioning allowable range and the speed a becomes half the positioning allowable range in the equation (2).
_When the speed has decreased to ₀ , the process proceeds to S10, and when the speed has not decreased to v0, the process proceeds to S6. That is, in S8, it is confirmed that the movable stage 34 has decreased to such a predetermined stop speed.

Then, in S10, the CPU 62
A drive signal is input to the vibrator 31, that is, a signal for prohibiting the application of the drive voltage is output. In the present embodiment, the input of the drive signal to the vibrator 31 is stopped by cutting off the drive power supply. As a result, the movable stage 34 stops while performing damped oscillation with the initial amplitude a. However, the movable stage 34 does not deviate from the allowable positioning range.

According to the positioning device 30 of this embodiment, the following effects can be obtained. (1) Since the movable stage 34 is fixed to the movable element 32 in a state of extending in a direction substantially parallel to the pressing direction of the oscillator 31 and the movable element 32, the oscillator fixed member 42 and the oscillator 31 , The movable element 32 and the movable stage 34 can be arranged side by side in this direction. Therefore, the size of the positioning device 30 in the direction orthogonal to the base substrate 60 can be suppressed as much as possible. Therefore, it is possible to provide the positioning device 30 which is small in size and can be installed in a small installation space.

(2) Driving force take-out part 3 of mover 32
Since the thickness of the non-contact portion 41c with the contact portions 7a to 37b 'is smaller than the thickness of the contact portions 41a to 41b' with the drive force output portions 37a to 37b ', the weight of the movable element 32 can be reduced.
Further, since the hollow portion 34d and the cutout portion 34e are formed in the movable stage 34, the weight of the movable stage 34 can be reduced. Therefore, due to these synergistic effects, the moving element 3
The weight of both the movable stage 34 and the movable stage 34 can be reduced, and the settling time of the movable stage 34 can be reduced.

(3) Driving force take-out part 3 of movable element 32
Since the thickness of the non-contact portion 41c with the contact portions 7a to 37b 'is smaller than the thickness of the contact portions 41a to 41b' with the drive force take-out portions 37a to 37b ', the lapping of the protrusion portions 41a to 41b' is performed. Time can be reduced.

(4) Driving force take-out part 3 of mover 32
Since the thickness of the non-contact portion 41c with the driving force take-out portions 37a to 37b 'is smaller than the thickness of the non-contact portion 41c with the driving force take-out portions 37a to 37b', the movable portion is movable due to the vibration generated by the vibrator 31. The vibration of the stage 34 can be suppressed. Further, since the movable stage 34 is provided with the vibrator mounting surface 34a fixed to the mover 32 and the mounting surface 34b, even if the hollow portion 34d and the notch 34e are formed on the mounting surface 34b, the vibrator 31 is Vibration of the movable stage 34 due to the generated vibration can be suppressed. Further, by providing the hollow portion 34d and the cutout portion 34e on the plane of the movable stage 34 located on the opposite side of the vibrator mounting surface 34a with respect to the mounting portion of the linear guide 55, the movable stage 34 is positioned around its center of gravity. It can be stopped without any rotational displacement. Therefore, the positioning accuracy of the movable stage 34 can be improved by these synergistic effects.

(5) FIG. 10 shows a case where the input of the drive signal to the vibrator 31 of the ultrasonic motor 33 is stopped when the movable stage 34 reaches the vicinity of the target position according to the present embodiment. 7 is a graph showing an example of a relationship between a detected speed and a position deviation (deviation between a command position and a current position) and time.

As shown by the graph in FIG. 10, the ultrasonic motor 33 is started at time t ₀ , moves toward the target position while following the command position, and moves from the drive control device 61 to the positioning allowable range P. At time t ₁ when the speed reaches the predetermined stop speed and reaches a predetermined stop speed, a signal for prohibiting the input of a drive signal to the vibrator 31 of the ultrasonic motor 33 is output. In this case, vibration generated in the movable stage 34 are the vibration of amplitude a without departing from the positioning tolerance, the movable stage 34 via a time t _2, the at time t _3, and stops at the target position.

As described above, in the present embodiment, the servo control is not continued even after the movable stage 34 reaches the positioning allowable range set within a predetermined distance from the target position. In order to prohibit input of a drive signal to the vibrator 31, the movable stage 34, which is a positioning target,
Further, the switching terminal 56 can be stopped at the target position in a short time.

For this reason, according to the present embodiment, for example, an ultrasonic motor 33 capable of stopping at a desired target position in a short time, a control method thereof, and a positioning object using the ultrasonic motor 33 Both the movable device 34 and the positioning device 30 capable of stopping the switching terminal 56 at the target position in a short time can be provided.

Further, since the moving speed of the movable stage 34 is sufficiently reduced by the time when the input of the drive signal is stopped, the vibration amplitude of the movable stage 34 during the stop is sufficiently small. The movement of the movable stage 34 after the stop of the signal due to the vibration does not deviate from the allowable positioning range. Further, since the movable stage 34 does not move due to the self-holding force of the ultrasonic motor 33 even after the vibration of the movable stage 34 is completely stopped, it is not necessary to input a drive signal.

(Modification) In the description of the embodiment, the case where the vibration motor is an ultrasonic motor is taken as an example. But,
The present invention is not limited to the ultrasonic motor, and is equally applicable to a vibration motor using a vibration region other than the ultrasonic wave.

In the description of the embodiment, the case where the positioning device according to the present invention is applied to an optical fiber switching device is taken as an example. However, the present invention is not limited to the optical fiber switching device, but is equally applicable to various positioning devices.

Further, in the description of the embodiment, the primary longitudinal vibration which is the first vibration vibrating in a direction substantially parallel to the direction of the relative movement generated between the vibrator and the moving element, An example in which a deformed mode degenerate type vibrator that excites a fourth-order bending vibration, which is a second vibration vibrating in a direction substantially parallel to the direction in which the moving element is pressed, is used. However, the vibrator used in the present invention is not limited to the order of each of the longitudinal vibration and the bending vibration. For example, a vibrator that excites primary longitudinal vibration and secondary bending vibration, a vibrator that excites primary longitudinal vibration and sixth-order bending vibration, and a tertiary longitudinal vibration and eighth-order bending vibration A vibrator that excites bending vibration can be used in the same manner.

The vibrator used in the present invention is not limited to the combination of the longitudinal vibration and the bending vibration. And can be similarly applied.

In the description of the embodiment, the case where the vibrator has a piezoelectric body is taken as an example. However, the present invention is not limited to a piezoelectric body, and can be equally applied to any interconversion element of electric energy and mechanical energy such as an electrostrictive element.

Further, in the description of the embodiment, the case where the vibrator has four driving force output portions is taken as an example. However, the present invention is not limited to this form, and is equally applicable, for example, even when two driving force extracting portions are provided at a predetermined distance in the width direction of the elastic body in the relative movement direction. . In this case, since the contact portion of the mover with the drive force take-out portion has a rectangular planar shape, a cross-shaped groove as in each embodiment is formed on the contact surface of the mover with the vibrator. Instead, a rectangular flat groove is formed substantially at the center in the direction of relative movement.

Further, in the description of the embodiment, a case where both the notch portion and the hollow portion are formed in the moving stage is taken as an example. However, the present invention is not limited to this mode, and one of the cutout portion and the hollow portion may be formed.

Further, in the description of the embodiment, the case where the input of the drive signal to the vibrator is prohibited at the timing when the deviation falls within the positioning allowable range and the speed is reduced to the predetermined speed is taken as an example. However, the present invention is not limited to this timing, and input of a drive signal to the vibrator may be prohibited after this timing.

Further, in the description of the embodiment, the case where the input of the drive signal to the vibrator is prohibited at the timing when the deviation falls within the allowable positioning range and the speed is reduced to the predetermined speed is taken as an example. However, the present invention is not limited to this mode, and if the speed at the time of reaching the positioning allowable range is suppressed sufficiently small, even if the speed does not decrease to the predetermined speed, the vehicle enters the positioning allowable range. At a timing, the input of the drive signal to the vibrator may be prohibited.

In the description of the embodiment, the application of the drive voltage is prohibited by shutting off the drive power supply. However, the present invention is not limited to this embodiment. Any means may be used.

In the description of the embodiment, the case where the vibrator is fixedly arranged and the relative movement member is provided on the movable stage is taken as an example. However, the present invention is not limited to this embodiment. The member may be fixedly arranged, and the vibrator may be provided on the movable stage.

Further, each embodiment is an example in which the present invention is embodied, and various modifications are possible within a range in which the effects of the present invention can be obtained.

[0100]

According to the present invention, a vibration motor, such as an ultrasonic motor, capable of stopping at a desired stop position in a short time, a control method thereof, and an object to be positioned at a target position by using the vibration motor. A positioning device that can be stopped in a short time can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a simplified state of a positioning device of an embodiment with a part thereof being seen through.

FIG. 2 is a view taken in the direction of arrow A in FIG.

FIG. 3 is a view taken in the direction of arrow B in FIG. 1;

FIG. 4 is a perspective view showing a configuration of each of a vibrator and a moving element in the embodiment.

FIG. 5 is an explanatory diagram of a vibrator according to the embodiment;
5A is a top view, FIG. 5B is a side view, and FIG. 5C is an explanatory diagram showing waveform examples of two different vibrations L1 and B4 generated in the vibrator.

FIG. 6 is a perspective view extracting and showing a movable element and a movable stage in the embodiment.

FIG. 7 is a block diagram illustrating an example of a drive control device of the positioning device according to the embodiment.

FIG. 8 shows a CP of the drive control device of the positioning device according to the embodiment.
6 is a flowchart of U.

FIG. 9 is a graph showing an example of an operation speed profile and a command position set in the embodiment.

FIG. 10 is a diagram showing an example in which the input of a drive signal to the vibrator of the ultrasonic motor is stopped when the movable stage reaches the vicinity of the target position. 6 is a graph showing an example of a relationship between a position (deviation from position) and time.

FIG. 11 shows a commanded position, a detection speed of a positioning object, and a positional deviation (deviation between a commanded position and a current position) when the conventional servomotor control is directly applied to an ultrasonic motor.
6 is a graph showing an example of a relationship between time and time.

[Explanation of symbols]

 Reference Signs List 30 positioning device 31 vibrator 32 mover 33 ultrasonic motor 34 movable stage 61 drive control device

Continued on the front page F-term (reference) 5H303 AA05 BB01 BB06 BB11 CC06 DD14 EE03 EE07 FF09 HH01 JJ01 KK02 KK35 MM01 5H680 AA09 BB03 BB13 BC10 CC02 DD01 DD15 DD23 DD53 DD72 DD82 DD92 EE22 EE23 FF30 GG24 FF04 GG24 FF24 GG04 FF02 GG24 FF04

Claims (5)

[Claims] 1. A vibrator that generates vibration by receiving a drive signal, a relative motion member that generates relative motion by pressurizing and contacting the vibrator, and a target stop of the vibrator or the relative motion member. A vibration motor, comprising: a drive control device for prohibiting the input of the drive signal to the vibrator after a positioning tolerance set within a range of a predetermined distance from a position is reached. 2. The drive control device according to claim 1, wherein input of the drive signal to the vibrator is prohibited after the speed of the vibrator or the relative motion member is reduced to a predetermined speed. The vibration motor according to claim 1. 3. The vibrator or the relative motion member, which is displaced by mechanical vibration generated when the input of the drive signal to the vibrator is stopped, is within the positioning allowable range. The vibration motor according to claim 1, wherein the vibration motor is driven at a predetermined speed. 4. One of claims 1 to 3
A positioning device, comprising: the vibration motor described in the above section; and a movable stage driven by the vibration motor. 5. A vibrator that receives a drive signal and generates vibration or a relative motion member that generates relative motion by pressing and contacting the vibrator is set within a predetermined distance from a target stop position. A method for controlling a vibration motor, comprising: prohibiting input of the drive signal to the vibrator after reaching a positioning allowable range.