JP3279020B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for generating a driving force by generating an elliptical motion in a rod-shaped elastic body.
The present invention relates to an ultrasonic motor that drives two phases of a longitudinal vibration mode and a bending vibration mode.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of a linear ultrasonic motor. In the conventional linear type ultrasonic motor, a transformer 102 for vibration is disposed on one end of a rod-shaped elastic body 101, and a transformer 103 for vibration suppression is disposed on the other end.
Transformers 102 and 103 include vibrators 102a and 103, respectively.
a is joined. An AC voltage is applied from the oscillator 102b to the vibrator 102a to vibrate the rod-shaped elastic body 101, and the vibration propagates through the rod-shaped elastic body 101 to become a traveling wave. This traveling wave causes the rod-shaped elastic body 10
The moving body 104 that is in pressure contact with 1 is driven.

[0003] On the other hand, the vibration of the rod-shaped elastic body 101 is transmitted to a vibrator 103a through a damping transformer 103, and the vibrator 103a converts vibration energy into electric energy. Vibration is absorbed by consuming electric energy by the load 103b connected to the vibrator 103a. The vibration-reducing transformer 103 suppresses the reflection of the end face of the rod-shaped elastic body 101 and
01 is prevented from being generated.

The linear ultrasonic motor shown in FIG.
The length of the rod-shaped elastic body 101 is necessary only for the moving range of 04, and the entire rod-shaped elastic body 101 must be vibrated. In order to prevent this, there is a problem that a transformer 103 for damping is required.

To solve such a problem, various self-propelled ultrasonic motors have been proposed.
A “deformed degenerate longitudinal L1-bending B4 mode flat motor” described in “222 Piezoelectric Linear Motor for Moving Optical Pickup” in “Symposium on Dynamics of Rotating Electromagnetics” is known.

FIG. 5 is a schematic diagram showing a conventional example of a deformed reduced length L1-bent B4 mode flat motor.
5A is a front view, FIG. 5B is a side view, and FIG. 5C is a plan view. The elastic body 1 includes a rectangular flat base 1a,
Projections 1b, 1 formed on one surface of the base 1a
c. The piezoelectric elements 2 and 3 are
Is an element that is attached to the other surface of the base portion 1a and generates a longitudinal vibration L1 mode and a bending vibration B4 mode. The protrusions 1b and 1c of the elastic body 1 are provided at positions of antinodes of the bending vibration B4 mode generated on the base 1a, and are pressed against a guide rail (not shown).

[0007]

However, as shown in FIG.
In the motor described above, two modes of vibration, the longitudinal vibration mode and the bending vibration mode, are generated in the elastic body 1, and if the elastic body 1 is not properly supported, the generated vibration is attenuated. there were.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an ultrasonic motor which has a reduced supporting loss without attenuating the vibration as much as possible in any of the longitudinal vibration mode and the bending vibration mode. To provide.

[0009]

According to a first aspect of the present invention , there is provided an electromechanical transducer comprising an elastic body and an electromechanical transducer coupled to the elastic body. In the ultrasonic motor, a longitudinal vibration mode and a bending vibration mode are generated in the elastic body by the electromechanical conversion element, and a driving force is obtained from a predetermined position of the elastic body by an elliptical motion generated by a synthetic vibration of the elastic body. At a position where the node of the longitudinal vibration mode and the node of the bending vibration mode coincide with each other or at a position around the same , relative to the elastic body in the driving direction and the pressing direction.
An ultrasonic motor comprising a support means (14, 15, 16, 17, 18) for applying pressure while maintaining the positional relationship and supporting the elastic body. Claim 2
The invention relates to the ultrasonic motor according to claim 1, wherein
The support means is movable with the elastic body.
It is an ultrasonic motor characterized by the following.

[0010] The invention of claim 3 provides the ultrasonic motor according to claim 1, wherein the support means, characterized by pressure supporting nearly central portion in the longitudinal direction of vibration of the elastic body super
It is a sound wave motor .

[0011] A fourth aspect of the present invention, in the ultrasonic motor according to claim 1, wherein the support means is an ultrasonic motor for causing fixed portion to pressure contact as pressed to the elastic body There is . The invention of claim 5 is based on claim 1.
3. The ultrasonic motor according to claim 1, wherein
Perpendicular to the surface on which the electromechanical conversion element of the
Engages with a convex portion provided on the surface, and has a degree of freedom in the driving direction.
In the pressure direction according to the displacement of the elastic body.
It is an ultrasonic motor characterized by applying pressure.

[0012] The invention of claim 6 provides the ultrasonic motor according to claim 1, wherein the support means, an ultrasonic motor, characterized in that to to pressure contact to draw the elastic body fixing part is there.

[0013]

According to the present invention, since the position where the node of the longitudinal vibration mode coincides with the node of the bending vibration mode and the periphery thereof are used to support, the vibration of either the longitudinal vibration mode or the bending vibration mode is used. The support can be performed with little support loss with little attenuation.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments will be described in more detail with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of the ultrasonic motor according to the present invention. Elastic body 11
Has a base portion 11a and two protrusions 11b and 11c. The base portion 11a has piezoelectric elements 12, 1 for generating a longitudinal vibration L1 mode and a bending vibration B4 mode.
3 are arranged. The function of each element is the same as that shown in FIG. In this embodiment, the piezoelectric element 1
2 and 13 are polarized as shown in FIG. 1B, and two-phase input voltages A and B as shown in FIG. 2A described later are applied.

The elastic body 11 is provided at the center of the base 11a.
A pair of pins 14 are arranged. This position is a position that becomes a node of both vibrations in the longitudinal vibration L1 mode and the bending vibration B4 mode, as is apparent from FIG. 2 described later. This pin 1
The position 4 is the center position of the elastic body 11 in the thickness direction and the length direction. Therefore, it is most suitable to support this position and its surroundings in terms of supporting efficiency.

The support 15 is a pressing means (for example, a spring)
The pin 14 is separated from the fixing portion 20 via the bearing 16 and bearing members (for example, rollers) 17 and 18, and pressure is applied in a direction to press the fixing portion 19. The pressed elastic body 11
The tips of the two projections 11 b and 11 c come into pressure contact with the fixing portion 19, and relative movement occurs between the two projections 11 b and 11 c and the fixing portion 19.

As shown in FIG. 1, this ultrasonic motor
By applying the high-frequency voltages A and B to the two piezoelectric elements 12 and 13, a combined vibration of bending vibration and longitudinal vibration is caused, thereby generating an elliptical motion at the tips of the protrusions 11b and 11c, and driving force Is generated.
Here, G is the ground. Also, two piezoelectric elements 1
2 and 13 are polarized so that the polarities are in the same direction, and the high-frequency voltages A and B have a temporal phase difference of π / 2. The polarization of the two piezoelectric elements 12 and 13 may be opposite to each other.

FIG. 2A shows the temporal 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. 2A indicates the effective value of the high-frequency voltage. FIG. 2B shows a state of deformation of a cross section of the ultrasonic motor, and shows a temporal change (t1 to t9) of bending vibration generated in the ultrasonic motor. FIG. 2C shows a state of deformation of a cross section of the ultrasonic motor, and shows a temporal change (t1 to t9) of longitudinal vibration generated in the ultrasonic motor. FIG. 2D shows the projections 11b, 11b of the ultrasonic motor.
c shows the temporal change (t1 to t9) of the elliptical motion occurring.

Next, the operation of the ultrasonic motor of this embodiment will be described for each time change (t1 to t9). Time t
In FIG. 1, as shown in FIG. 2A, 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. 2B, the bending motions due to the high-frequency voltages A and B cancel each other, and the mass point Y1
And Z1 have an amplitude of zero. As shown in FIG. 2C, the longitudinal vibrations caused by the high-frequency voltages A and B are generated in the direction in which the longitudinal vibrations extend. Mass points Y2 and Z2 show the greatest extension about node X, as indicated by the arrows. As a result, FIG.
As shown in (D), the two vibrations are combined and the mass point Y1
The combination of the motions of the mass points Y1 and Z2 is the motion of the mass point Y, and the combination of the motions of the mass points Z1 and Z2 is the motion of the mass point Z.

At time t2, as shown in FIG. 2A, the high-frequency voltage B becomes zero, and the high-frequency voltage A generates a positive voltage. As shown in FIG. 2B, a bending motion occurs due to the high-frequency voltage A, and the mass point Y1 oscillates in the positive direction and the mass point Z1 oscillates in the negative direction. In addition, as shown in FIG. 2C, longitudinal vibration occurs due to the high-frequency voltage A, and the mass points Y2 and Z2 contract more than at time t1. As a result, as shown in FIG.
And Z move clockwise more than at time t1.

At time t3, as shown in FIG. 2A, 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. 2B, the bending motions due to the high-frequency voltages A and B are combined and amplified, and the mass point Y1 is amplified more positively than at the time t2, and exhibits the largest positive amplitude value. Mass point Z1 is time t2
Is amplified in the negative direction more than in the case of, and shows the maximum negative amplitude value. As shown in FIG. 2C, the longitudinal vibrations caused by the high-frequency voltages A and B cancel each other, and the mass points Y2 and Z2
Returns to its original position. As a result, as shown in FIG. 2D, the two vibrations are combined, and the mass points Y and Z move clockwise more than at time t2.

At time t4, as shown in FIG. 2A, the high frequency voltage A becomes zero and the high frequency voltage B generates a negative voltage. As shown in FIG. 2B, a bending motion occurs due to the high-frequency voltage B, and the amplitude of the mass point Y1 is lower than that at time t3, and the amplitude is lower than that at mass point Z1 at time t3. Further, as shown in FIG. 2C, a 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. 2 (D), the two vibrations are combined, and the mass points Y and Z move clockwise more than at time t3.

At time t5, as shown in FIG. 2A, the high-frequency voltage A generates a negative voltage, and the high-frequency voltage B similarly generates the same negative voltage. As shown in FIG. 2B, the bending motions due to the high-frequency voltages A and B cancel each other, and the mass points Y1 and Z1 have an amplitude of zero. FIG.
As shown in (C), the longitudinal vibration caused by the high-frequency voltages A and B occurs in a contracting direction. The mass points Y2 and Z2 show the maximum contraction around the node X as indicated by the arrows. As a result, as shown in FIG. 2D, the two vibrations are combined, and the mass points Y and Z move clockwise more than at time t4.

As time t6 to t9 changes,
A bending vibration and a longitudinal vibration are generated in the same manner as described above, and as a result, as shown in FIG. 2D, the mass points Y and Z move clockwise and perform an elliptical motion. According to the above principle, this ultrasonic motor is configured to generate a driving force by generating an elliptical motion at the tip with the projections 11a and 11b. Therefore, the tips of the protrusions 11b and 11c are
When the pressure is applied to the elastic member 11, the elastic body 11 self-runs with respect to the fixed portion 19.

FIG. 3 shows a second embodiment of the ultrasonic motor according to the present invention.
It is the schematic diagram which showed the Example of FIG. Note that portions that perform the same functions as in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. The support 21 presses the pin 14 </ b> A in a direction of pulling the pin 14 </ b> A into the fixing portion 25 via a pressing unit (spring) 22 and bearing members (rollers) 23 and 24. The support 21, the pressing means 22, the bearing member 2
The pins 3 and 24 are similarly provided on a pin 14B opposite to the pin 14A. In the pressed elastic body 11, the distal ends of the two protrusions 11 b and 11 c come into pressure contact with the fixing portion 25, and relative movement between the two protrusions 11 b and 11 c and the fixing portion 25 occurs. Occur.

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. For example, the elastic body 11 may be pressed against the fixing portion 19 by its own weight.

[0027]

As described above in detail, according to the present invention, the position where the node of the longitudinal vibration mode coincides with the node of the bending vibration mode and the periphery thereof are used to support, so that the longitudinal vibration is achieved. There is an effect that the support can be performed with little support loss without hardly damping any of the vibrations in the mode and the bending vibration mode.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a driving operation of the ultrasonic motor according to the first embodiment.

FIG. 3 is a schematic view showing a second embodiment of the ultrasonic motor according to the present invention.

FIG. 4 is a view showing a conventional example of a linear ultrasonic motor.

FIG. 5 is a schematic diagram showing an example of a deformed reduced length L1-bent B4 mode flat motor.

[Explanation of symbols]

 11 Elastic body 12, 13 Piezoelectric element 14 pin

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02N 2/00-2/18

Claims (6)

(57) [Claims] 1. An elastic body and an electromechanical transducer coupled to the elastic body, wherein the electromechanical transducer causes the elastic body to generate a longitudinal vibration mode and a bending vibration mode, and a combination thereof. the elliptical motion generated by the vibration, the ultrasonic motor to obtain a driving force from a predetermined position of the elastic body, the elastic in the position of or around the section of the longitudinal oscillation mode and the node of the flexural oscillation mode matches Body and driving direction
And pressurizing while maintaining the relative positional relationship in the pressing direction.
An ultrasonic motor , further comprising: support means for supporting the elastic body. 2. The ultrasonic motor according to claim 1, wherein
An ultrasonic motor , wherein the support means is movable with the elastic body . 3. The ultrasonic motor according to claim 1, wherein said support means presses and supports a substantially central portion of said elastic body in a longitudinal vibration direction. 4. The ultrasonic motor according to claim 1, wherein said support means presses said elastic body against a fixed portion to make pressure contact. 5. An ultrasonic motor according to claim 1, wherein :
The support means is provided for the electromechanical transducer of the elastic body.
Engage with a protrusion provided on a surface orthogonal to the provided surface,
The driving direction has no degree of freedom and the pressing direction
An ultrasonic motor characterized in that pressure is applied according to displacement of an elastic body . 6. The ultrasonic motor according to claim 1, wherein said support means presses and contacts said elastic body so as to be drawn into a fixed portion.