JP3265461B2 - Ultrasonic drive motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an ultrasonic drive motor.

[0002]

2. Description of the Related Art An ultrasonic drive motor moves a moving body by using a reciprocating motion of an ultrasonic vibrator provided in the ultrasonic drive motor. One of the methods is to extend and retract an ultrasonic vibrator in a longitudinal direction. Some use vibration. Such an ultrasonic drive motor is disclosed, for example, in JP-B-59-37672.
As described with reference to FIG. 7, for example, as described with reference to FIG. 7, an ultrasonic vibrator 100 is configured by providing piezoelectric members 104 on both surfaces of a vibrator member 102, and the ultrasonic vibrator 1
A vibrating piece 106 at one end in the direction of expansion and contraction indicated by the arrow 106 of FIG. The moving direction indicated by reference numeral 112 can be converted.

Also, an ultrasonic drive motor using one or more sets of ultrasonic drive motors of such a type so that a moving body can linearly move in the forward and reverse directions has been proposed in Japanese Patent Application Laid-Open No. 59-194678. I have. This ultrasonic drive motor will be described with reference to FIG. 8. First, as shown in FIG. 8A, the ultrasonic drive motor is provided with ultrasonic vibrators 114 and 116 having the same configuration as described above,
One ultrasonic transducer 114 that expands and contracts in eight directions is indicated by an arrow 12.
0 direction, the vibrating piece 121 is brought into contact with the moving body 122 and then vibrated to move the moving body 122 in the forward direction 12.
4 at this time, and the switching lever
The other ultrasonic vibrator 116 that vibrates in the direction
The vibrating piece 130 is moved away from the moving body 122 by moving the vibrating piece 130. Conversely, as shown in FIG. 8B, one of the ultrasonic vibrators 114 is moved in the direction of the arrow 131 by the switching lever to separate the vibrating piece 121 from the moving body 122, and the other ultrasonic vibrator 116 is moved by the arrow. The moving member 122 is moved in the direction of an arrow 134 by switching the direction of the moving member 132 to the direction 132 and bringing the vibrating piece 130 into contact with the moving member 122 and oscillating the ultrasonic vibrator 116.

[0004]

However, in the ultrasonic drive motor shown in FIG. 7, the moving body cannot be moved in the forward and reverse directions. In addition, in the ultrasonic drive motor shown in FIG. 8, although the moving body can be moved in the forward and reverse directions, an actuator is separately required for switching the switching lever, and the lever is switched at high speed. It is also difficult to switch with the switching lever because it is difficult. Furthermore, since a switching lever and an actuator are required, the overall shape becomes complicated and costly, and there is a problem that it is not easy to make the device thinner and smaller.

[0005]

According to the present invention, there is provided an ultrasonic drive motor comprising a first vibrator member and piezoelectric members provided on both sides of the first vibrator member. A first ultrasonic vibrator having a vibrating reed on the end side of the first vibrator member in the direction of expansion and contraction due to the vibration, a second vibrator member, and both surfaces thereof are provided. A piezoelectric member, which vibrates at a second resonance frequency by application of an electric signal, and
A second ultrasonic vibrator provided with a vibrating reed at the end of the second vibrator member in the direction of expansion and contraction caused by the vibration; and the two ultrasonic vibrators are arranged at a predetermined angle with respect to each other. And, by being characterized in that the respective vibrating reeds are connected to each other, even if an electric signal is applied to the two ultrasonic vibrators, since the respective resonance frequencies are different, the two ultrasonic vibrators are At the same time, the resonance vibrations are combined and the vibration trajectory of the end of the vibrating piece in contact with the moving body does not change.Therefore, the moving body can be moved in the normal and reverse directions only by applying an electric signal without a switching lever. In addition to being switched and moved, each of the ultrasonic vibrators is constituted by a vibrator member and piezoelectric members provided on both sides of the vibrator member, and the vibrating piece is provided at a longitudinal end of the vibrator member. Since is provided, the overall shape is very simple.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic drive motor according to an embodiment of the present invention will be described below. FIG. 1 is a perspective view of an ultrasonic drive motor of the present embodiment. Referring to FIG. 1, the ultrasonic drive motor of the present embodiment vibrates at a first resonance frequency f1 by application of an electric signal. 1 includes an ultrasonic vibrator 2 and a second ultrasonic vibrator 4 that vibrates at a second resonance frequency f2 different from the first resonance frequency f1. Each of the ultrasonic vibrators 2 and 4 has a rectangular shape in a plan view, and includes vibrating pieces 6 and 8 extending in the longitudinal direction, that is, in the center of the end in the direction of extension and contraction thereof, in the direction of extension and contraction by the vibration. On the other hand, they are arranged at a predetermined angle, in this embodiment, at a right angle. And each vibrating piece 6,
8 are connected to each other by joining or integrating them.

The first ultrasonic vibrator 2 includes a first vibrator member 10
And first and second piezoelectric members 12 having electrode films on both surfaces thereof,
The second ultrasonic vibrator 4 comprises a second vibrator member 16 and third and fourth piezoelectric members 16 and 18 having electrode films on both surfaces thereof.

Each of the ultrasonic transducers 2 and 4 having the above-described configuration has T-shaped first to fourth fixing members 22 to 22 in plan view on both sides on a line parallel to the short direction at the center in the longitudinal direction.
28, respectively. Each fixing member 22 to 28
Are the respective vibrator members 10, 1 of the respective ultrasonic vibrators 2, 4.
6 are electrically and mechanically connected to each other, and each has a hole 30 for screw insertion for fixing to an appropriate motor wall. Here, the second fixing member 24 and the third fixing member 26 are integrally connected by a connecting member 32, respectively. The first and second piezoelectric members 12 and 14 on both surfaces of the vibrator member 10 of the first ultrasonic vibrator 2 and the third and fourth piezoelectric members 18 on both surfaces of the vibrator member 16 of the second ultrasonic vibrator 4. 2
On the line parallel to the short direction at each central portion in the long direction, a node of the vibration mode is set, and one intermediate point between the long direction and the short direction is an energization point 34, 36. However, for the second piezoelectric member 14 and the fourth piezoelectric member 20, the current-carrying points do not appear in the drawing. A conduction point 38 is also formed at the center of the connection member 32.

The drive circuit 40 of the ultrasonic drive motor has electric signal output units 42 to 46, and the first electric signal output unit 4
2 is connected to the respective energization points of the first and second piezoelectric members 12 and 14 via the two energization lines 48 and 50, respectively, and the second electric signal output unit 46 connects the two energization lines 52 and 54 respectively. The third and fourth piezoelectric members 18 and 20 are connected to the current-carrying points of the third and fourth piezoelectric members 18 and 20, respectively. The electric signal output section 44 is connected to the conduction point 38 of the connection member 32 via a conduction line 56.

Here, the vibrator members 10 and 16, the fixing members 22 to 28, and the connecting member 32 of each of the ultrasonic vibrators 2 and 4 each have a single plate shape as shown in FIG. And an elastic member 58 made of a metal such as stainless steel.

Next, the operation will be described. The first ultrasonic vibrator 2 includes the first vibrator member 10 and the first and second piezoelectric members 12 and 1.
4, the electric signal output unit 42 of the drive circuit 40,
An AC electric signal is supplied from the power supply line 44 via each of the energizing lines 48, 50, and 56. When the frequency of the AC electric signal is continuously changed to become the first resonance frequency f1, the first and second piezoelectric members 12 are provided. , 14 exhibit a peak at which the impedance sharply decreases, thereby causing the first and second piezoelectric members 1
The current flowing through each of the first and second ultrasonic transducers 2 and 14 increases, and the first ultrasonic vibrator 2 enters a resonance state. Similarly, the second ultrasonic transducer 4
Are the second vibrator member 16 and the third and fourth piezoelectric members 18 and 20
The electric signal output units 44 and 4 of the drive circuit 40 are provided between them.
6, and the third and fourth piezoelectric members 18 and 20 when an AC electric signal is applied via the energizing lines 52 to 56 and the frequency of the AC electric signal is continuously changed to reach the second resonance frequency f2. Presents a peak at which the impedance of the second ultrasonic transducer 4 suddenly decreases, whereby the current flowing through the third and fourth piezoelectric members 18 and 20 increases, and the second ultrasonic transducer 4 enters a resonance state.

[0012] Of the resonance modes of the first and second ultrasonic vibrators 2 and 4, the first ultrasonic vibrator 2 and the second ultrasonic vibrator 4 are respectively associated with a certain resonance mode. Vibrates so as to expand and contract in the longitudinal direction. In this case, the amplitude of the vibration changes according to the magnitude of the applied voltage, but usually, the connecting end portions of the vibrating pieces 6, 8 of the respective ultrasonic vibrators 2, 4 vibrate with an amplitude of about several μm. I do. At this time, the frequency f1 of the resonance mode in which the first ultrasonic transducer 2 expands and contracts in the longitudinal direction is different from the frequency f2 of the resonance mode in which the second ultrasonic transducer 4 expands and contracts in the longitudinal direction. When the vibrator 2 is vibrating so as to expand and contract in the longitudinal direction, the second ultrasonic vibrator 4 does not vibrate, and conversely, vibrates so that the second ultrasonic vibrator 4 expands and contracts in the longitudinal direction. During this operation, the first ultrasonic transducer 2 does not vibrate. The moving trajectory of the vibrating piece 6 of the first ultrasonic vibrator 2 is shown in FIGS. 3A to 3C, and the moving trajectory of the vibrating piece 8 of the second ultrasonic vibrator 4 is shown in FIGS. This movement trajectory is shown in FIG. 3 for the first ultrasonic transducer 2.
a → FIG. 3b → FIG. 3c → FIG. 3b → FIG. 3a. For the second ultrasonic transducer 4, FIG. 4a → FIG. 4b → FIG.
4b → FIG. 4a are repeated.

By changing the moving trajectory of each of the vibrating pieces 6 and 8 of each of the ultrasonic vibrators 2 and 4 in this manner, the moving body 60 that is in contact with the joint end portions of the two vibrating pieces 6 and 8 is shown in FIG. It is moved in the directions of the arrows a and b.

If the resonance frequencies f1 and f2 of the ultrasonic vibrators 2 and 4 are the same, the trajectories of the vibrating pieces 6 and 8 are as shown in FIGS. Do not move.

In the above embodiment, the first
The two sides of the first vibrator member 10 of the first ultrasonic vibrator 2 are T-shaped at the positions of the nodes of the vibration mode of the ultrasonic vibrator 2, that is, at the center in the longitudinal direction and on a line parallel to the transverse direction. , Second
Similarly, the second ultrasonic vibrator 4 is fixed at the position of the node of the vibration mode of the second ultrasonic vibrator 4, that is, at the center in the longitudinal direction on a line parallel to the short direction. 4 are fixed by T-shaped third and fourth fixing members 26 and 28, so that the ultrasonic drive motor of the present embodiment is provided with a piezoelectric member for each of the ultrasonic vibrators 2 and 4. Since the configuration is such that only the connection is made with the conducting wire, the configuration of the ultrasonic drive motor is simple and the thickness can be reduced.

In the above-described embodiment, the first,
The second ultrasonic vibrators 2 and 4 may have different shapes and different resonance frequencies f1 and f2. For example, the second ultrasonic vibrators 2 and 4 may have different lengths in the longitudinal direction, that is, different lengths in the direction of expansion and contraction. By doing so, the respective resonance frequencies f1 and f2 may be different.

In the above-described embodiment, the first and second ultrasonic vibrators 2 and 4 have different elastic constants of the piezoelectric members and have different resonance frequencies f1 and f1.
f2 may be different.

In the above-described embodiment, the first and second
The ultrasonic vibrators 2 and 4 each include first to fourth fixing members 22
Since both sides are fixed at 28 to 28, the rigidity of the ultrasonic drive motor can be increased, so that the thrust of the ultrasonic drive motor can be improved and generation of abnormal noise can be prevented. As shown, of the fixing members 22 to 28,
The first and fourth fixing members 22 and 28 are omitted, and the first and second ultrasonic vibrators 2 and 2 are formed by the second and third fixing members 24 and 26.
In the case where one of the four sides is fixed, the projection area of the ultrasonic drive motor can be reduced, so that the overall size can be reduced.

[0019]

As described above, according to the present invention, the following effects can be obtained.

According to the first aspect of the present invention, the first vibrator is constituted by the first vibrator member and the piezoelectric members provided on both surfaces of the first vibrator member, and vibrates at the first resonance frequency by application of an electric signal. A first ultrasonic vibrator having a vibrating reed on the end side of the first vibrator member in the direction of expansion and contraction due to the vibration;
A vibrator member and piezoelectric members provided on both sides of the vibrator member, vibrating at a second resonance frequency by application of an electric signal, and an end of the second vibrator member in the direction of expansion and contraction due to the vibration. A second ultrasonic vibrator provided with a vibrating reed on the side, the two ultrasonic vibrators are arranged at a predetermined angle with respect to each other, and the respective vibrating reeds are connected to each other Therefore, even if an electric signal is applied to the two ultrasonic transducers, the respective resonance frequencies are different, so that the two ultrasonic transducers simultaneously vibrate, and the respective resonance vibrations are combined to come into contact with the end of the vibrating piece in contact with the moving body. Therefore, in addition to the fact that the vibration trajectory does not change, the moving body can be switched and moved in the forward / reverse direction only by application of the electric signal without the switching lever. Since the vibrating piece is composed of a member and piezoelectric members provided on both sides of the member and the vibrating piece is provided at a longitudinal end of the vibrator member, the overall shape is simplified and the cost can be reduced. In addition, the thickness and the size can be easily reduced.

According to the second aspect of the present invention, the vibrator member of each of the two ultrasonic vibrators and the fixing member for fixing each of the two ultrasonic vibrators are commonly formed by the conductive elastic member. In addition, since the fixing member is provided at a position corresponding to the node of the expansion and contraction direction vibration mode of each of the ultrasonic transducers, the configuration as the ultrasonic drive motor can be made simpler, thinner, and smaller. Becomes

According to the third aspect of the present invention, the resonance frequencies are different from each other because the lengths of the two ultrasonic transducers in the longitudinal direction are different from each other. Can be further reduced in thickness.

According to the fourth aspect of the present invention, since the piezoelectric members of the two ultrasonic transducers have different elastic constants from each other, it is only necessary to select the material of the piezoelectric members, and the shape of the ultrasonic transducer can be changed. By changing the resonance frequency, it is not necessary to increase the resonance frequency, thereby making it possible to further reduce the overall configuration.

According to the fifth aspect of the present invention, since the fixing members for each of the two ultrasonic vibrators are provided on both sides of the node of the vibration mode in the expansion and contraction direction, the rigidity of the ultrasonic drive motor increases, It is possible to improve the thrust of the ultrasonic drive motor and effectively prevent generation of abnormal noise.

According to the sixth aspect of the present invention, since the fixing member for each of the two vibrators is provided at one side of the node in the expansion / contraction vibration mode, the projection area of the ultrasonic drive motor is reduced. The overall configuration can be further reduced in size.

[0026]

[Brief description of the drawings]

FIG. 1 is a perspective view of an ultrasonic drive motor according to an embodiment of the present invention.

FIG. 2 is a perspective view of an elastic member constituting a vibrator member, a fixed member, and the like in FIG.

FIG. 3 is a diagram showing a movement trajectory of a resonator element of a first ultrasonic transducer.

FIG. 4 is a diagram showing a movement locus of a vibrating piece of a second ultrasonic transducer.

FIG. 5 is a diagram showing a movement trajectory of the two vibrating pieces when the resonance frequencies of the two ultrasonic vibrators match.

FIG. 6 is a plan view showing another modification of the fixing member.

FIG. 7 is a plan view of a conventional ultrasonic drive motor.

FIG. 8 is a plan view of another conventional ultrasonic drive motor.

[Explanation of symbols]

 2 First ultrasonic vibrator 4 Second ultrasonic vibrator 6,8 Vibrating piece 10 First vibrator member 12,14 Piezoelectric member 16 Second vibrator member 18,20 Piezoelectric member 22-28 Fixing member 34,36 Vibration Section of mode 40 Drive circuit 42-46 Electric signal output unit 48-56 Conductive line

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-58883 (JP, A) JP-A-7-7974 (JP, A) JP-A-6-277624 (JP, A) JP-A 8-78 237971 (JP, A) JP-A-9-308271 (JP, A) JP-A-5-67194 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02N 2/00

Claims (6)

(57) [Claims] 1. A first vibrator member and both surfaces thereof
And a piezoelectric member provided.
Vibrates at the first resonance frequency.
A vibrating reed is provided at the end of the first vibrator member in the direction of expansion and contraction.
The first ultrasonic transducer, the second transducer member, and both surfaces thereof
It is composed of piezoelectric members provided for each
Vibrates at the second resonance frequency by the application of
The end of the second vibrator member in the direction of expansion and contraction
And a second ultrasonic vibrator provided with a vibrating reed.
The wave oscillators are arranged at a predetermined angle with respect to each other,
It is noted that the respective vibrating bars are connected to each other.
Ultrasonic drive motor. 2. The ultrasonic vibration device according to claim 1, further comprising: a conductive elastic member.
Each transducer member of the rotor and each of the two ultrasonic transducers
And a fixing member for fixing the
First, the fixing member is expanded and contracted by each of the two ultrasonic vibrators.
Be provided at the position corresponding to the node of the directional vibration mode.
The ultrasonic drive motor according to claim 1, wherein: 3. A longitudinal direction of each of the two ultrasonic transducers.
Are different from each other due to the different length of
3. The super according to claim 1 or 2, wherein
Sound wave drive motor. 4. A piezoelectric member for each of the ultrasonic transducers.
Have different elastic constants from each other
The ultrasonic drive motor according to claim 1 or 2. 5. A method according to claim 1, wherein each of said two ultrasonic transducers is fixed.
Fixed members are provided on both sides of the joint of the vibration mode in the telescopic direction.
3. The method according to claim 1, wherein
Ultrasonic drive motor. 6. A fixed member for each of the two ultrasonic transducers.
The fixed member is provided at one side of the node in the telescopic vibration mode.
3. The method according to claim 1, wherein
Ultrasonic drive motor.