JPH0870585A - Ultrasonic actuator drive - Google Patents

Abstract

(57) [Abstract] [Purpose] Even when the relative motion member is exposed to the outside, it is prevented that the driving force and the driving efficiency are lowered due to the adhesion of dust or the like. [Structure] Piezoelectric elements 12, 13 excited by a drive signal
, The piezoelectric elements 12 and 13 are joined to each other, and the elastic body 11 that causes an elliptical motion in the drive portion due to the excitation of the piezoelectric element, the relative movement member 20 that is in pressure contact with the drive portion of the elastic body 11, and the relative movement member 20. Cleaning member 1 for removing the deposits attached to the
8 and.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device using an ultrasonic actuator, and more particularly, to two-phase driving in a longitudinal vibration mode and a bending vibration mode to generate an elliptic motion on a driving surface of a plate-like elastic body. The present invention relates to an ultrasonic actuator drive device that obtains a driving force.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a conventional example of a linear ultrasonic motor. In a conventional linear ultrasonic motor, a vibrating transformer 102 is arranged on one end side of a rod-shaped elastic body 101 and a vibrating transformer 103 is arranged on the other end side.
Each of the transformers 102, 103 includes a vibrator 102a, 103
a is joined. An alternating voltage is applied from the oscillator 102b to the vibrator 102a for vibration to vibrate the rod-shaped elastic body 101, and this vibration propagates through the rod-shaped elastic body 101 to become a traveling wave. Due to this traveling wave, the rod-shaped elastic body 10
The moving body 104 that is brought into pressure contact with 1 is driven.

On the other hand, the vibration of the rod-shaped elastic body 101 is transmitted to the vibrator 103a through the vibration damping transformer 103, and the vibrator 103a converts the vibration energy into electric energy. The load 103b connected to the vibrator 103a consumes the electric energy to absorb the vibration. This vibration damping transformer 103 suppresses the reflection of the end surface of the rod-shaped elastic body 101, and the rod-shaped elastic body 1
The generation of standing waves of 01 eigenmodes is prevented.

The linear type ultrasonic motor shown in FIG.
The length of the rod-shaped elastic body 101 is required only for the moving range of 04, and the whole of the rod-shaped elastic body 101 has to be vibrated, so that the device becomes large and the standing wave of the eigenmode is generated. In order to prevent this, there has been a problem that the vibration damping transformer 103 and the like are required.

In order to solve such problems, various self-propelled ultrasonic motors have been proposed.
The "degenerate vertical L1-bending B4 mode flat plate motor" described in "222 Piezoelectric linear motor for moving optical pickup" in "Proceedings of Dynamics Symposium on Electromagnetic Force" is known.

FIG. 8 is a schematic view showing a conventional example of a modified degenerate vertical L1-bending B4 mode flat plate motor.
8A is a front view, FIG. 8B is a side view, and FIG. 8C is a plan view. The elastic body 1 includes a rectangular flat plate-shaped base portion 1a,
Drive portions 1b, 1 formed on one surface of the base portion 1a
and c. The piezoelectric elements 2 and 3 are elastic bodies 1.
Is an element that is attached to the other surface of the base portion 1a to generate a longitudinal vibration L1 mode and a bending vibration B4 mode. The drive parts 1b and 1c of the elastic body 1 are provided at antinode positions of the bending vibration B4 mode generated in the base part 1a, and are pressed against a relative motion member (not shown).

[0007]

In the ultrasonic actuator of FIG. 7 described above, when the relative motion member is exposed to the outside of the drive unit, external dust or other foreign matter may adhere to the relative motion member. However, there is a possibility that the adhered matter may enter the ultrasonic actuator driving device while being attached. In this case, there is a problem that the attached matter is caught between the driving surface of the elastic body and the relative movement member, the driving force of the elastic body is not well transmitted to the relative movement member, and the driving force and the driving efficiency are reduced. Occurs.

Particularly, when the relative motion member is a linear member, the contact with the elastic body is one-dimensional (point contact). Therefore, compared with the case where the relative motion member and the elastic pair are in surface contact, the driving force is Also, there is a problem that the amount of decrease in driving efficiency is large.

An object of the present invention is to provide an ultrasonic actuator driving device which prevents the adherence of dust or the like from adhering to the driving member and the driving efficiency from being reduced even when the relative motion member is exposed to the outside. It is to be.

[0010]

In order to solve the above-mentioned problems, the invention of claim 1 joins the electro-mechanical conversion element (12, 13) excited by a drive signal and the electro-mechanical conversion element. When the electro-mechanical conversion element is excited, an elastic body (1
1), a relative movement member (20) that comes into pressure contact with the drive unit of the elastic body, and a cleaning member (18) that removes deposits attached to the relative movement member.

According to a second aspect of the present invention, there is provided an electro-mechanical conversion element which is excited by a drive signal, and the electro-mechanical conversion element (12, 13).
An elastic body (11) to which a mechanical conversion element is joined and which causes an elliptic motion in a drive part by excitation of the electro-mechanical conversion element,
A drive roller (14) that is pressed by the drive unit of the elastic body and is rotated by an elliptic motion of the drive unit; and a relative motion member (20) to which the rotation of the drive roller is transmitted.
An auxiliary roller (15) for contacting the relative motion member on the surface opposite to the drive roller and reducing a frictional reaction force generated due to the movement of the relative motion member; A first pressure member (16) that applies pressure to the first pressure member, and a second pressure member (17) that applies pressure while sandwiching the relative movement member between the auxiliary roller and the drive roller,
A cleaning member (18) for removing deposits attached to the relative motion member.

The invention according to claim 3 is claim 1 or claim 2.
In the ultrasonic actuator driving device described above, the cleaning member vibrates ultrasonically.

According to a fourth aspect of the present invention, in the ultrasonic actuator driving device according to the third aspect, the cleaning member (1
8) is a cleaning electro-mechanical conversion element (18-1) excited by a drive signal, a cleaning elastic body (18-2) excited together with the cleaning electro-mechanical conversion element, and the cleaning elasticity. A removing member (18-3) provided on the body for removing deposits adhering to the relative motion member.

The invention of claim 5 is from claim 1 to claim 4.
The ultrasonic actuator drive device according to any one of claims 1 to 4, wherein the electro-mechanical conversion element and the cleaning electricity-
The mechanical conversion element is characterized by being driven by the same drive circuit.

The invention of claim 6 is from claim 1 to claim 5.
In the ultrasonic actuator drive device according to any one of items 1 to 5, the relative movement member is a planar member (21), and the cleaning member (18A) cleans the elastic body side of the relative movement member. Characterize.

[0016]

According to the present invention, the relative movement member is cleaned by the cleaning member to remove foreign matters such as dusts, which are externally attached, immediately before contacting the elastic body. Therefore, it is possible to prevent the adhering matter from entering between the relative motion member and the elastic body, and prevent the driving force and the driving efficiency from decreasing.

[0017]

【Example】

(First Embodiment) Hereinafter, the embodiments will be described in more detail with reference to the drawings. 1 and 2 are external views showing a first embodiment of an ultrasonic actuator driving device according to the present invention, and FIG. 1 is a side view.
FIG. 2A is a view seen from the driving direction of the relative motion member, and FIG. 2B is a cross-sectional view taken along the alternate long and short dash line in FIG.

The drive device of this embodiment includes an elastic body 11,
The piezoelectric elements 12 and 13, the driving roller 14, the auxiliary roller 15, the first pressure member 16, the second pressure member 17, the cleaning member 18, and the support member 19 are included. The elastic body 11 includes a base portion 11a and two drive portions 11b, 1
1c, and a piezoelectric element 12,
13 are arranged. A sliding member 11d is joined to the tips of the drive units 11b and 11c.

The piezoelectric elements 12 and 13 are electro-mechanical conversion elements for converting electric energy into mechanical energy.
An electrostrictive element or the like may be used instead of the piezoelectric element. The piezoelectric elements 12 and 13 are joined to the joint surface of the elastic body 11, and are driven by the combined vibration of the longitudinal vibration L1 mode and the bending vibration B4 mode generated in the elastic body 11 by the excitation of the piezoelectric elements 12 and 13. Elliptical motion occurs on the surface.
The piezoelectric elements 12a and 13a are mechanical-electrical conversion elements that detect the vibration state of the elastic body 11, and the drive circuit is controlled to a suitable drive state based on the detected value.

The drive roller 14 is a drive unit 1 for the elastic body 11.
The relative motion member 20 is rotated by the elliptical motion generated by the driving units 11b and 11c when being pressurized by 1b and 11c.
It is a roller that transmits the driving force to. The auxiliary roller 15 is
This is a roller for reducing a frictional reaction force generated when the relative motion member 20 is driven. The first pressure member 16 is
It is a member that presses the elastic body 11 against the drive roller 14. The cushioning material 16a is for preventing the vibration of the elastic body 11 from being attenuated by pressurization, and a material such as felt is preferably used. The second pressure member 17 is a member that presses the relative motion member 20 while sandwiching it between the drive roller 14 and the auxiliary roller 15. The cleaning member 18 is a member that removes deposits on the relative motion member 20. The support member 19 is
It is a member that supports the elastic body 11, the driving roller 14, the auxiliary roller 15, the first and second pressure members 16 and 17, and the cleaning member 18.

The relative movement member 20 is a member (for example, a linear member) having a width smaller than the width of the elastic body 11, and is sandwiched between the driving roller 14 and the auxiliary roller 15 to form the driving roller 1
It is driven by transmitting the driving force from 4.

According to the above configuration, the piezoelectric element 1
2 and 13 are excited by the drive signal to generate elliptic motions in the drive portions 11b and 11c of the elastic body 11, and drive force is exerted between the elastic body 11 and the drive roller 14 which is in pressure contact with the elastic body drive surface. Occurs, and the drive roller 14 rotates. As the drive roller 14 rotates, the relative motion member 20 that is in pressure contact with the drive roller 14 is driven.

In this embodiment, the piezoelectric elements 12 and 13 are
As shown in FIG. 1B, it is polarized, and FIG.
Two-phase input voltages A and B as shown in (A) are applied.

As shown in FIG. 1, this ultrasonic motor is
By applying high-frequency voltages A and B to the two piezoelectric elements 12 and 13, a composite vibration of bending vibration and longitudinal vibration is generated, which causes elliptical motion at the tips of the driving units 11b and 11c, thereby driving force. Is configured to generate.
Here, G is the ground. In addition, the two piezoelectric elements 1
2 and 13 are polarized so that their polarities are in the same direction, and the high frequency voltages A and B have a time phase difference of π / 2. The polarizations of the two piezoelectric elements 12 and 13 may be opposite to each other.

FIG. 3A shows time changes of the two-phase high frequency voltages A and B input to the ultrasonic motor at t1 to t9. The horizontal axis of FIG. 3A represents the effective value of the high frequency voltage. FIG. 3B shows how the cross section of the ultrasonic motor is deformed, and shows a temporal change (t1 to t9) of bending vibration generated in the ultrasonic motor. FIG. 3C shows how the cross section of the ultrasonic motor is deformed, and shows the temporal change (t1 to t9) of the longitudinal vibration generated in the ultrasonic motor. FIG. 3D shows the protrusions 11b and 11 of the ultrasonic motor.
3 shows temporal changes (t1 to t9) of the elliptic motion generated in c and c.

Next, the operation of the ultrasonic motor of this embodiment will be described for each time change (t1 to t9). Time t
1, the high frequency voltage A generates a positive voltage, and the high frequency voltage B similarly generates the same positive voltage, as shown in FIG. As shown in FIG. 3B, the bending motions due to the high frequency voltages A and B cancel each other out, and the mass point Y1
And Z1 have zero amplitude. Further, as shown in FIG. 3C, the longitudinal vibrations due to the high frequency voltages A and B are generated in the extending direction. The mass points Y2 and Z2 show the maximum elongation around the node X, as indicated by the arrow. As a result, FIG.
As shown in (D), the above-mentioned both vibrations are combined, and the mass point Y1
The synthesis of the motion of Y and Y2 becomes the motion of the mass point Y, and the synthesis of the motion of the mass points Z1 and Z2 becomes the motion of the mass point Z.

At time t2, as shown in FIG. 3 (A), the high frequency voltage B becomes zero and the high frequency voltage A generates a positive voltage. As shown in FIG. 3 (B), a bending motion is generated by the high frequency voltage A, the mass Y1 oscillates in the positive direction, and the mass Z1 oscillates in the negative direction. Further, as shown in FIG. 3C, longitudinal vibration due to the high frequency voltage A occurs, and the mass points Y2 and Z2 contract more than at time t1. As a result, as shown in FIG. 3 (D), both of the above vibrations are combined and the mass Y
And Z move clockwise relative to the time t1.

At time t3, as shown in FIG. 3 (A), the high frequency voltage A generates a positive voltage and the high frequency voltage B similarly generates the same negative voltage. As shown in FIG. 3 (B), the bending motions due to the high frequency voltages A and B are combined and amplified, and the mass point Y1 is amplified in the positive direction more than at the time t2, showing the maximum positive amplitude value. Mass point Z1 is time t2
It is amplified in the negative direction more than, and shows the maximum negative amplitude value. Further, as shown in FIG. 3C, the longitudinal vibrations due to the high frequency voltages A and B cancel each other out, and the mass points Y2 and Z2
And return to their original positions. As a result, as shown in FIG. 3 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t2.

At time t4, as shown in FIG. 3 (A), the high frequency voltage A becomes zero and the high frequency voltage B generates a negative voltage. As shown in FIG. 3 (B), a bending motion occurs due to the high-frequency voltage B, and the mass of the mass point Y1 is lower than that at the time t3, and the mass Z1 is less than that at the time t3. Further, as shown in FIG. 3 (C), longitudinal vibration is generated by the high frequency voltage B, and the mass points Y2 and Z2 contract.
As a result, as shown in FIG. 3 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t3.

At time t5, as shown in FIG. 3 (A), the high frequency voltage A produces a negative voltage, and similarly the high frequency voltage B produces the same negative voltage. As shown in FIG. 3B, the bending motions due to the high frequency voltages A and B cancel each other out, and the masses Y1 and Z1 have zero amplitude. Also, FIG.
As shown in (C), the longitudinal vibration due to the high frequency voltages A and B is generated in the contracting direction. The mass points Y2 and Z2 show the maximum contraction around the node X, as indicated by the arrow. As a result, as shown in FIG. 3 (D), both of the above vibrations are combined, and the mass points Y and Z move clockwise relative to the time t4.

As the time t6 to t9 changes,
Bending vibration and longitudinal vibration are generated in the same manner as the above-described principle, and as a result, as shown in FIG. 3D, the mass points Y and Z move clockwise and make an elliptic motion. On the basis of the above principle, this ultrasonic actuator driving device is provided with the projections 11a, 1
The driving force is generated by causing elliptical motion at the tip of 1b. Therefore, when the tips of the protrusions 11b and 11c are pressed against the relative motion member 20, the elastic body 11 becomes
The relative motion member 20 is moved.

At this time, the cleaning member 18 removes deposits attached to the relative motion member 20 (linear member) outside the ultrasonic actuator driving device. Therefore, the adhered matter attached to the relative motion member 20 does not enter between the drive roller 14 and the relative motion member 20 or between the drive roller 14 and the elastic body 11, and the driving force and the driving efficiency are reduced. Can be prevented.

FIG. 4 is a view for explaining the cleaning member according to the first embodiment. The cleaning member 18 includes a cleaning unit piezoelectric element 18-1 and a cleaning unit piezoelectric element 18-, which are excited by a drive signal.
The cleaning unit elastic body 18-2 that excites together with the cleaning unit 1 and the brush-shaped removing unit 18-3 that is provided on the cleaning unit elastic body 18-2 and removes the deposits attached to the linear relative motion member 20. It

The cleaning section piezoelectric element 18-1 is excited by a drive signal, and the cleaning section elastic body 18-2 is excited in response to the excitation. Excitation of the cleaning unit elastic body 18-2 causes the removal unit 18-3 to vibrate, and the deposits attached to the relative motion member 20 are removed. In this embodiment, since the removing unit 18-3 is ultrasonically vibrated, the relative motion member 20 is removed by the removing unit 18-.
The frictional resistance that occurs when passing 3 is reduced. Also,
By vibrating the removing unit 18-3, the removing effect is also improved. In this embodiment, the cleaning member 18 is driven to be removed by ultrasonic vibration, but the effect of removing the adhering substance can be obtained without ultrasonic vibration.

FIG. 5 is a block diagram showing a drive circuit of the ultrasonic actuator drive apparatus according to the first embodiment. The oscillator 31 oscillates a signal having a frequency corresponding to the first longitudinal vibration mode and the fourth bending vibration mode of the vibrating body composed of the elastic body 11 and the piezoelectric elements 12 and 13. The output of the oscillator 31 is branched, and one output is amplified by the amplifier 33 and then input to the electrodes of the piezoelectric element 12 and the cleaning section piezoelectric element 18-1 as the A-phase voltage. Further, the other branched output is connected to the phase shifter 32, and the phase shifter 32 causes the phase A voltage to be π /
After the phase is shifted by 2 to form the B-phase voltage, the amplifier 34
Is input to the electrode of the piezoelectric element 13 via.

The drive signal applied to the cleaning unit piezoelectric element 18-1 is applied to the ultrasonic actuator by making the resonance frequencies of the cleaning unit elastic body 18-2 and the elastic body 11 of the ultrasonic actuator substantially the same. The drive signal generation unit and the drive signal generation unit applied to the cleaning member 18 can be made common, which simplifies the drive circuit. The drive signal applied to the cleaning unit piezoelectric element 18-1 may be different from the drive signal applied to the ultrasonic actuator.

(Second Embodiment) FIG. 6 is an external view showing a second embodiment of the ultrasonic actuator driving apparatus according to the present invention. In addition, the same reference numerals are given to the portions having the same functions as those of the above-described first embodiment, and the overlapping description will be appropriately omitted. In the first embodiment, the case of driving the linear relative motion member has been described, but the second embodiment is an example of the case where the relative motion member is not linear, for example, paper-shaped or flat-plate-shaped.

The relative movement member 21 is paper-shaped or flat-plate shaped, is sandwiched between the driving roller 14 and the auxiliary roller 15, and is driven by the transmission of the driving force from the driving roller 14. In the second embodiment, since the deposits on the surface of the relative movement member 21 on the auxiliary roller 15 side have almost no effect on the performance deterioration, the removing unit 18A is provided so as to remove the deposits only on the surface on the drive roller 14 side. I decided to provide it.

The present invention is not limited to the embodiments described above, and various modifications and changes are possible, which are also included in the present invention. In the present embodiment, the brush-shaped removing member is used as a member for removing the adhering matter of the relative motion member, but the adhering matter may be removed by pressing against a member such as a sponge. Also, without providing a member such as a brush or sponge,
Any method may be used as long as it is a method of removing the adhering matter attached to the relative motion member, such as a method of blowing off the adhering matter by blowing air.

Further, as the electromechanical conversion element, the piezoelectric body has been described as an example, but an electrostrictive element may be used. Further, as the vibration mode, the vibration in the L1-B4 mode has been described as an example, but other modes such as L1-B2, L1-B6 and L2-B4 may be used. Furthermore, although the elastic body side is fixed and the relative movement member is moved has been described as an example, the relative movement member may be fixed and a self-propelled type may be used.

[0041]

As described above, according to the present invention, the cleaning member is used to remove foreign matters such as dust attached to the relative motion member outside, so that the contact member that comes into contact with the relative motion member or the elastic body. There is an effect that foreign matter does not enter between the elastic body and the elastic body, and it is possible to prevent the driving force and the driving efficiency from decreasing.

[Brief description of drawings]

FIG. 1 is an external view (side view) showing a first embodiment of an ultrasonic actuator driving device according to the present invention.

FIG. 2 is an external view of an ultrasonic actuator driving device according to a first example (a view seen from a driving direction of a relative motion member and a cross-sectional view taken along the chain line of FIG. 1A). .

FIG. 3 is a diagram illustrating a driving operation of the ultrasonic actuator driving device according to the first embodiment.

FIG. 4 is a diagram illustrating a cleaning member of the ultrasonic actuator driving device according to the first embodiment.

FIG. 5 is a block diagram showing a drive circuit of the ultrasonic actuator drive apparatus according to the first embodiment.

FIG. 6 is a schematic view showing a second embodiment of the ultrasonic actuator driving device according to the present invention.

FIG. 7 is a diagram showing a conventional example of a linear ultrasonic motor.

FIG. 8 is a schematic view showing an example of a modified degenerate vertical L1-bending B4 mode flat plate motor.

[Explanation of symbols]

 11 Elastic Body 12, 13 Piezoelectric Element 14 Drive Roller 15 Auxiliary Roller 16 First Pressure Member 17 Second Pressure Member 18 Cleaning Member 19 Support Member 20 Relative Motion Member 31 Oscillator 32 Phase Shifter 33, 34 Amplifier

Claims (6)

[Claims] 1. An electro-mechanical conversion element that is excited by a drive signal; and an elastic member that is joined to the electro-mechanical conversion element and that produces an elliptical motion or a progressive vibration wave in the drive section by the excitation of the electro-mechanical conversion element. An ultrasonic actuator driving device comprising: a body; a relative movement member that comes into pressure contact with a drive unit of the elastic body; and a cleaning member that removes deposits attached to the relative movement member. 2. An electro-mechanical conversion element that is excited by a drive signal; an elastic body that is joined to the electro-mechanical conversion element, and that causes an elliptical motion in a drive portion due to the excitation of the electro-mechanical conversion element; A drive roller that is pressed by a drive unit of the body and is rotated by an elliptic motion of the drive unit; a relative movement member to which the rotation of the drive roller is transmitted; and a relative movement on a surface opposite to the drive roller. Contact the member,
An auxiliary roller for reducing a frictional reaction force generated by the movement of the relative movement member; a first pressing member for pressing the elastic body against the drive roller; and a relative movement member for the auxiliary roller and the auxiliary roller. An ultrasonic actuator driving device, comprising: a second pressure member that presses while sandwiching it by a drive roller; and a cleaning member that removes deposits attached to the relative motion member. 3. The ultrasonic actuator driving device according to claim 1, wherein the cleaning member vibrates ultrasonically. 4. The ultrasonic actuator drive apparatus according to claim 3, wherein the cleaning member includes a cleaning electro-mechanical conversion element that is excited by a drive signal; and a cleaning electro-mechanical conversion element that is excited together with the cleaning electro-mechanical conversion element. An ultrasonic actuator drive device, comprising: an elastic body; and a removing member that is provided on the cleaning elastic body and removes adhered matter attached to the relative motion member. 5. The ultrasonic actuator drive device according to claim 1, wherein the electro-mechanical conversion element and the cleaning electro-mechanical conversion element are driven by the same drive circuit. An ultrasonic actuator driving device characterized by being driven. 6. The ultrasonic actuator drive device according to claim 1, wherein the relative movement member is a planar member, and the cleaning member is the relative movement member. An ultrasonic actuator drive device characterized in that an elastic body side is cleaned.