JPH11146667A - Ultrasonic motor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic motor, which can stably hold a stator formed in a cylindrical shape with a simple constitution so that noise may be produced hardly without hindering the oscillation of the stator, and can accelerate the improvement of the driving efficiency of a rotor. SOLUTION: An ultrasonic motor device is provided with a stator 15 in which a full-face electrode 15c is formed on either the inner or outer peripheral surface of a piezoelectric element 15a formed in a cylindrical shape, and a plurality of split electrodes 15b1 and 15b2 are arranged on the outer or inner peripheral surface of the element 15a along the circumference of the element 15a. The rotor 14 of the motor device compressively contacted with the stator 15 is rotationally driven by oscillating the stator 15 by supplying high-frequency driving signals between the split electrodes 15b1 and 15b2 and full-face electrode 15c. The stator 15 is held in such a state that the outer peripheral surface of the stator 15 is coated with rubber 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an ultrasonic motor device having a structure in which a rotor is pressed against a cylindrical stator that vibrates ultrasonically.

[0002]

2. Description of the Related Art As is well known, an ultrasonic motor device such as the one described above applies a high-frequency AC voltage to a cylindrical piezoelectric element serving as a stator to generate ultrasonic vibration of about 20 kHz or more. The rotor which is pressed against the stator is rotationally driven. The rotor has a simple structure and is suitable for reduction in size and weight. In addition, a high torque can be obtained even at low speed rotation, and the drive noise is small and quiet. Has advantages.

[0003]

However, the conventional ultrasonic motor device having the above-described structure has a problem that it is difficult to hold the stator. That is, when the stator is formed into a cylindrical shape, all of its outer peripheral surface, inner peripheral surface, and both end surfaces are displaced during driving. For this reason, no matter where the stator is held, the regular vibration is hindered, and the driving efficiency of the rotor deteriorates.

[0004] Conventionally, simple holding is often performed on a cylindrically formed stator by sandwiching the stator from both end surfaces or fitting the outer peripheral surface. There is an inconvenience that noise is easily generated between the holding member and the holding member.

In view of the above circumstances, the present invention has been made in consideration of the above circumstances, and has a simple configuration in which a cylindrically-shaped stator is formed so as not to hinder vibration and generate less noise. It is an object of the present invention to provide an extremely good ultrasonic motor device which can be stably held and which can promote improvement in driving efficiency of a rotor.

[0006]

An ultrasonic motor device according to the present invention comprises a piezoelectric element formed in a cylindrical shape, and an entire surface electrode formed on one of the inner and outer surfaces of the piezoelectric element. A plurality of divided electrodes arranged on the other surface of the piezoelectric element along the circumference of the piezoelectric element; and supplying a high-frequency drive signal between the plurality of divided electrodes and the entire surface electrode to form the piezoelectric element. A drive means for vibrating, a rotor pressed against the piezoelectric element and driven to rotate by receiving the vibration of the piezoelectric element, and a rubber for covering and holding the outer peripheral surface of the piezoelectric element.

According to the above configuration, since the outer peripheral surface of the piezoelectric element is covered and held by the rubber, the radial displacement of the piezoelectric element is absorbed by the rubber with a simple configuration. In addition, the piezoelectric element can be stably held without obstructing its vibration and generating less noise, and the driving efficiency of the rotor can be improved.

Further, an ultrasonic motor device according to the present invention provides a piezoelectric element formed in a cylindrical shape, an entire surface electrode formed on one of the inner and outer surfaces of the piezoelectric element, On the other surface, a plurality of divided electrodes arranged and formed along the circumference of the piezoelectric element except for the vicinity of one end in the central axis direction of the piezoelectric element, and A driving means for supplying a high-frequency drive signal to the piezoelectric element to vibrate the piezoelectric element, a rotor pressed against the piezoelectric element and driven to rotate by receiving the vibration of the piezoelectric element, and a portion of the piezoelectric element where a plurality of divided electrodes are not formed. And holding means for holding.

Further, an ultrasonic motor device according to the present invention provides a piezoelectric element having a cylindrical shape, an entire surface electrode formed on one of the inner and outer surfaces of the piezoelectric element, On the other surface, a plurality of divided electrodes arranged and formed along the circumference of the piezoelectric element on both sides except the vicinity of the central portion in the central axis direction of the piezoelectric element, and a plurality of divided electrodes and a full-surface electrode. A driving means for supplying a high-frequency driving signal between them to vibrate the piezoelectric element, a rotor pressed against the piezoelectric element and driven to rotate by receiving the vibration of the piezoelectric element, and a portion of the piezoelectric element in which a plurality of divided electrodes are not formed And holding means for holding the data.

According to the above structure, the divided electrodes are formed except for the vicinity of one end or the center in the direction of the central axis of the piezoelectric element. Therefore, the portion of the piezoelectric element where the divided electrodes are not formed is formed. Since this part is hardly deformed, if this part is held, it becomes possible to stably hold the piezoelectric element without obstructing its vibration and at the same time, hardly generating noise.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 11 denotes a housing formed in a bottomed cylindrical shape.
A support 12 formed in a cylindrical shape is accommodated concentrically inside the housing 11. This support 12
It is fixed inside the housing 11 with one end surface thereof in contact with the bottom surface 11 a of the housing 11.

The other end of the support 12 has a flange 12a.
Are formed. A ring-shaped washer 13, a ring-shaped rotor 14, and a cylindrically-shaped stator 15 are sequentially inserted into the support 12 from its side closer to the flange 12a. Have been.

The support 12 has a housing 11
A screw groove 12b is formed on the outer peripheral surface on the end side attached to the bottom surface 11a. And this screw groove 12b
The rotor 14 and the stator 15 are brought into contact with each other at a predetermined pressure by screwing a pressing member 16 formed in a ring shape and having a thread groove 16a formed on an inner peripheral surface thereof. I have.

This stator 15 is, as shown in FIG.
The divided electrode 1 divided into four at equal intervals along the circumferential direction on the outer peripheral surface of the piezoelectric element 15a formed in a cylindrical shape.
5b1 and 15b2 (the other two divided electrodes are not visible in the figure), and the entire surface of the inner surface of the piezoelectric element 15a is covered with the electrode 15c.

The four split electrodes 15b of the stator 15
1 and 15b2 have solders 15d1 and 15d2, respectively.
(The other two solders are not visible in the drawing.) The phases are mutually shifted by 90 ° between the adjacent divided electrodes 15b1 and 15b2 via the lead wires 15e1, 15e2, 15e3, and 15e4 connected by about 20 kHz or more. Is supplied.

Further, the entire surface electrode 15c of the stator 15 is provided.
Is grounded via a lead wire 15g connected by solder 15f. For this reason, the piezoelectric element 15a constituting the stator 15 has four divided electrodes 15b1, 1
The four regions corresponding to 5b2 are sequentially compressed and expanded in the radial direction and the central axis direction.

That is, the length of the stator 15 is regularly changed in one direction along the circumference. As a result, the rotor 14 pressed against one end face of the stator 15 is driven to rotate by friction with the stator 15, and the ultrasonic motor device is driven to rotate here.

As shown in FIG. 1 again, a cylindrical portion 14 a is formed on the outer peripheral edge of the rotor 14 so as to protrude outward from the open end of the housing 11. A thread groove 14b is formed on the outer peripheral surface of the tip of the cylindrical portion 14a in the protruding direction. In the ultrasonic motor device, a screw groove 14b of the rotor 14 is connected to a driven body (not shown) to transmit a rotational force.

Here, a rubber 17 formed into a cylindrical shape is fitted on the outer peripheral surface of the stator 15. The rubber 17 includes a washer 13, a rotor 14, a starter 1
When the support 12 to which the pressure member 5 and the pressing member 16 are attached is housed and fixed in the housing 11, the support 12 is press-fitted between the outer peripheral surface of the stator 15 and the inner peripheral surface of the housing 11. That is, the stator 15 is held by the housing 11 via the rubber 17.

According to the first embodiment, the rubber 17 is provided between the outer peripheral surface of the stator 15 and the inner peripheral surface of the housing 11.
In this configuration, the radial displacement of the stator 15 is absorbed by the rubber 17, so that the stator 15 does not hinder its vibration, and is stable so that noise is hardly generated. , And the driving efficiency of the rotor 14 can be improved.

FIG. 3 shows a modification of the first embodiment. That is, in FIG. 3, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description will be made. I have to. On the outer peripheral surface of the anisotropic conductive rubber 18, power supply electrodes 18 a 1 and 18 a 2 electrically connected to the four divided electrodes 15 b 1 and 15 b 2 of the stator 15 (the other two power supply electrodes are not visible in the figure). Are formed.

Then, each of the lead wires 15e1, 15e2,
The drive signals supplied via 15e3 and 15e4 are supplied from the power supply electrodes 18a1 and 18a2 via the anisotropic conductive rubber 18 to the corresponding divided electrodes 15b1 and 15b, respectively.
2 and is subjected to vibration of the stator 15. According to such a modification, the vibration in the radial direction of the stator 15 is absorbed by the anisotropic conductive rubber 18 in the same manner as described above, so that the stator 15 is not disturbed by the vibration and noise is generated. It can be held stably so as to be difficult.

The anisotropic conductive rubber 18 is divided into the divided electrodes 15.
b1 and 15b2 and lead wires 15e1 and 15e
Power supply electrode 18a connected to 2, 15e3, 15e4
1 and 18a2, the entire outer peripheral surface of the stator 15 can be covered with the anisotropic conductive rubber 18 irrespective of the soldered portions 15d1 and 15d2 shown in FIG. It is possible to stably hold.

FIG. 4 shows a second embodiment of the present invention. This is explained in FIG. 4 by attaching the same reference numerals to the same parts as in FIG. 2. In the outer peripheral surface of the piezoelectric element 15 a constituting the stator 15, the vicinity of the end portion on the side contacting the pressing member 16 is described. And four divided electrodes 15b1, 15
An area 15h where no b2 is formed is provided.

According to such a configuration, when a driving signal is applied to each of the four divided electrodes 15b1 and 15b2 to vibrate the stator 15, the piezoelectric element 15a
As shown in FIGS. 5A and 5B, only the portions where the four divided electrodes 15b1 and 15b2 are formed are:
It is compressed and expanded in the radial direction and the central axis direction.

The region 15h of the piezoelectric element 15a where the four divided electrodes 15b1 and 15b2 are not formed,
That is, the portions indicated by the arrows in FIGS. 5A and 5B are hardly deformed. Therefore, this region 15
If the portion h is held, the stator 15 can be stably held without hindering its vibration and without generating noise.

FIG. 6 shows a stator 15 having the structure shown in FIG.
Are shown. In FIG. 6, the same parts as those in FIG. 1 are denoted by the same reference numerals. Explaining the rubber 17, the pressing member 16 is shaped so that the outer peripheral surface is in contact with the inner peripheral surface of the housing 11. .

Then, the washer 13, the rotor 14 and the stator 15 are loosely inserted into the support 12, and the pressing member 16 and the stator 15 are bonded together with the pressing member 16 screwed. When fixing the support 12 in the housing 11, the outer peripheral surface of the pressing member 16 and the inner peripheral surface of the housing 11 are bonded.
Thereby, the stator 15 is in contact with the pressing member 16, that is, the four divided electrodes 15 b 1 and 15 b 2
The end on the side of the region 15h where no is formed is the pressing member 1
6 is held by the housing 11.

FIG. 7 shows a third embodiment of the present invention. This is explained by giving the same reference numerals to the same parts as in FIG. 2 in FIG. 7. Four divided electrodes 15 b 1 and 15 b 2 are provided along the outer peripheral surface at the center of the piezoelectric element 15 a in the central axis direction. The region 15i that is not formed is provided.

That is, the four divided electrodes 15b1, 15
b2 is 2 in the central axis direction of the piezoelectric element 15a.
Will be split. In this case, four divided electrodes 15b1 divided into two and arranged on the same circumference on the right side of FIG.
R and 15b2R have solders 15d1R and 15d, respectively.
Lead wires 15e1R, 15e2 connected by 2R
Drive signals whose phases are shifted from each other by 90 ° between adjacent divided electrodes 15b1R and 15b2R are supplied via R, 15e3R and 15e4R.

Further, four divided electrodes 15b1L and 15b2L divided into two and arranged on the same circumference on the left side of FIG.
Have lead wires 15e1L, 15e2L, 15e3 connected by solders 15d1L, 15d2L, respectively.
L, 15e4L, adjacent divided electrodes 15b1
L and 15b2L are supplied with drive signals whose phases are shifted by 90 ° from each other.

The drive signals supplied to the four divided electrodes 15b1R and 15b2R arranged on the same circumference on the right side of FIG. 7 and the four drive electrodes arranged on the same circumference on the left side of FIG.
The drive signal supplied to the two divided electrodes 15b11 and 15b2l refers to the divided electrodes 15b1R and 15b1L and 15b2R and 15b2 that are adjacent to each other in the central axis direction of the piezoelectric element 15a.
The phases between L are set so as to be shifted from each other by 180 °.

According to such a configuration, when a drive signal is applied to each of the eight divided electrodes 15b1R, 15b2R, 15b1L, and 15b2L to cause the stator 15 to vibrate, the piezoelectric element 15a is configured as shown in FIG. , (B)
As shown in the figure, the divided electrodes 15b1R, 15b2R, 15
Only the portions where b1L and 15b2L are formed are compressed and expanded in the radial direction and the central axis direction.

The divided electrodes 15b1R, 15b2R, 15b1 are located at the center of the piezoelectric element 15a in the central axis direction.
Regions 15i where L and 15b2L are not formed, that is, portions indicated by arrows in FIGS. 8A and 8B are hardly deformed. For this reason, if the portion of the region 15i is held, the stator 15 can be stably held without hindering its vibration and without generating noise.

FIG. 9 shows a stator 15 having the structure shown in FIG.
Are shown. In FIG. 9, the same parts as those in FIG. 1 are denoted by the same reference numerals. The rubber 17 is omitted, and the divided electrodes 15 b 1 R, 15 b 2 R, 15 b 1 L, and 15 b 2 of the stator 15 are provided on the inner peripheral surface of the housing 11.
Projection 1 in contact with region 15i where L is not formed
1b.

The support 1 with the washer 13, the rotor 14 and the stator 15 loosely inserted therein and the pressing member 16 screwed thereto.
2 is fixed in the housing 11, the region 1 of the stator 15
5i and the protrusion 11b of the housing 11 are bonded. Thereby, the stator 15 has a central portion in the central axis direction, that is, the divided electrodes 15b1R, 15b2R, 15b1L, 1
The region 15i where 5b2L is not formed is the protrusion 11
It will be held in the housing 11 via b.

FIG. 10 shows a fourth embodiment of the present invention. This is explained in FIG. 10 by assigning the same reference numerals to the same parts as those in FIG. 4, that is, four divided electrodes 15b provided near one end of the outer peripheral surface of the piezoelectric element 15a.
In a part of the region 15h in which 1, 15b2 is not formed,
This is one in which a vibration detection electrode 15j is formed.

FIG. 11 shows a drive circuit for generating drive signals to be applied to the four split electrodes 15b1 and 15b2 of the stator 15. In FIG. 11, reference numeral 19 denotes an oscillation circuit that can output an oscillation signal having a frequency of about 20 kHz or more. The oscillation signal output from the oscillation circuit 19 is supplied to the split electrode 15b1 as a drive signal after passing through the buffer 20. The oscillation signal output from the oscillation circuit 19 is supplied to the inverter buffer 2
After the polarity is inverted through 1, the driving signal is supplied to the split electrode 15b3 (which is located at a position symmetrical with the center axis of the split electrode 15b1 and the piezoelectric element 15a).

On the other hand, the oscillating signal output from the oscillating circuit 19 is supplied to a 90.degree. Phase delay circuit 22 so that the phase is delayed by 90.degree. Is supplied to the divisional electrode 15b2 as a drive signal through.

The oscillation signal supplied to the 90 ° phase delay circuit 22 and delayed in phase by 90 ° passes through the rotation direction switch 23 in the illustrated switching state, and is inverted in polarity by the inverter buffer 25. As the drive signal, the divided electrode 15b4 (the divided electrode 15b2 and the piezoelectric element 15
a at a position symmetrical with respect to the central axis of a).

That is, each split electrode 15 of the stator 15
b1 to 15b4 have adjacent divided electrodes 15b1 to 15b
The drive signals whose phases are mutually shifted by 90 ° between b4 are supplied. Therefore, the piezoelectric element 15a constituting the stator 15 has two adjacent divided electrodes (15b
1, 15b2), (15b2, 15b3), (15b
Each of the regions corresponding to (3, 15b4) and (15b4, 15b1) is compressed and expanded in the thickness direction in order of 90 °.

For this reason, the thickness of the stator 15 repeats a regular change in one direction along the circumference. Thus, the rotor 14 pressed against the stator 15 is driven to rotate by friction with the stator 15, and the ultrasonic motor is driven to rotate in one direction.

When the rotation direction changeover switch 23 is controlled to the opposite switching state, the oscillation signal output from the 90 ° phase delay circuit 22
6, the polarity is inverted and supplied to the buffer 24 and the inverter buffer 25.

For this reason, the thickness of the stator 15 repeats a regular change along the circumference in a direction opposite to the above. As a result, the rotor 14 pressed against the stator 15 is driven to rotate in the opposite direction by friction with the stator 15, and the ultrasonic motor is driven to rotate in the other direction.

When the piezoelectric element 15a is vibrated as described above, a detection signal corresponding to the vibration is generated from the vibration detection electrode 15j and supplied to the phase comparison circuit 27. The phase comparison circuit 27 compares the phase of the input detection signal with the phase of the oscillation signal output from the oscillation circuit 19, and controls the oscillation circuit 19 so as to obtain an oscillation signal of an optimum frequency.

FIG. 12 shows a fifth embodiment of the present invention. This is explained by assigning the same reference numerals to the same parts in FIG. 12 as those in FIG. 7. In other words, the divided electrodes 15b1R, 1
The vibration detection electrode 15k is formed in a part of the region 15i where 5b2R, 15b1L, and 15b2L are not formed.

According to such a configuration, the eight divided electrodes 15b1R, 15b, 15b1R, 15b1
The frequency of an oscillation circuit (not shown) for generating a drive signal to be applied to b2R, 15b1L, and 15b2L can be controlled to an optimal value. It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the scope of the present invention.

[0048]

As described in detail above, according to the present invention,
The stator formed in a cylindrical shape can be stably held with a simple configuration without disturbing its vibration and generating less noise, and can greatly improve the driving efficiency of the rotor. A good ultrasonic motor device can be provided.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a first embodiment of an ultrasonic motor device according to the present invention.

FIG. 2 is a perspective view showing a detailed structure of a stator according to the first embodiment.

FIG. 3 is a perspective view showing a modification of the stator according to the first embodiment.

FIG. 4 is a perspective view showing a second embodiment of the ultrasonic motor device according to the present invention.

FIG. 5 is a side sectional view showing displacement of a stator according to the second embodiment.

FIG. 6 is a side sectional view showing a stator holding means according to the second embodiment.

FIG. 7 is a perspective view showing a third embodiment of the ultrasonic motor device according to the present invention.

FIG. 8 is a side sectional view showing displacement of a stator in the third embodiment.

FIG. 9 is a side sectional view showing a stator holding means in the third embodiment.

FIG. 10 is a perspective view showing a fourth embodiment of the ultrasonic motor device according to the present invention.

FIG. 11 is a block diagram showing a driving circuit according to the fourth embodiment.

FIG. 12 is a perspective view showing a fifth embodiment of the ultrasonic motor device according to the present invention.

[Explanation of symbols]

 14 ... rotor, 15 ... stator, 17 ... rubber.

Claims (7)

[Claims] 1. A piezoelectric element formed in a cylindrical shape, an entire surface electrode formed on one of inner and outer surfaces of the piezoelectric element, and a circle of the piezoelectric element formed on the other surface of the piezoelectric element. A plurality of divided electrodes arranged along the circumference; a driving unit for supplying a high-frequency drive signal between the plurality of divided electrodes and the entire surface electrode to vibrate the piezoelectric element; An ultrasonic motor device comprising: a rotor that is driven to rotate by receiving vibration of the piezoelectric element; and a rubber that covers and holds an outer peripheral surface of the piezoelectric element. 2. The method according to claim 1, wherein the rubber includes an outer peripheral surface of the piezoelectric element,
The ultrasonic motor device according to claim 1, wherein the ultrasonic motor device is press-fitted between the piezoelectric element and an inner peripheral surface of a cylindrical housing that accommodates the piezoelectric element therein. 3. The power supply electrode, which is electrically conductive with an electrode formed on the outer peripheral surface of the piezoelectric element, is formed on the outer peripheral surface of the rubber, which is an anisotropic conductive rubber. 3. The ultrasonic motor device according to 1 or 2. 4. A piezoelectric element formed in a cylindrical shape, a full-surface electrode formed on one of inner and outer surfaces of the piezoelectric element, and a piezoelectric element formed on the other surface of the piezoelectric element. Excluding the vicinity of one end in the direction of the central axis, a plurality of divided electrodes arranged along the circumference of the piezoelectric element, and a high-frequency drive signal is supplied between the plurality of divided electrodes and the entire surface electrode. Driving means for causing the piezoelectric element to vibrate, a rotor being pressed against the piezoelectric element and rotated by receiving the vibration of the piezoelectric element, and holding means for holding a portion of the piezoelectric element where the plurality of divided electrodes are not formed An ultrasonic motor device comprising: 5. A piezoelectric element formed in a cylindrical shape, an entire surface electrode formed on one of inner and outer surfaces of the piezoelectric element, and a piezoelectric element of the piezoelectric element formed on the other surface of the piezoelectric element. A plurality of divided electrodes arranged along the circumference of the piezoelectric element and a high-frequency drive signal is supplied between the plurality of divided electrodes and the entire surface electrode on both sides except for the vicinity of the central portion in the central axis direction. A driving unit for vibrating the piezoelectric element, a rotor pressed against the piezoelectric element and driven to rotate by receiving the vibration of the piezoelectric element, and a holding unit for holding a portion of the piezoelectric element where the plurality of divided electrodes are not formed. And an ultrasonic motor device. 6. A vibration detecting electrode for detecting vibration of the piezoelectric element is formed in a portion of the piezoelectric element where the plurality of divided electrodes are not formed, and the driving means is provided based on an output of the vibration detecting electrode. 6. The ultrasonic motor device according to claim 4, wherein the frequency of the drive signal generated in the step (c) is controlled. 7. The driving means includes two divided electrodes that are adjacent to each other in the central axis direction of the piezoelectric element and have a phase of 180 degrees.
6. A driving signal which is shifted by a degree is supplied.
The ultrasonic motor device according to any one of the preceding claims.