JPH0591771A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To obtain such an ultrasonic motor that a prescribed voltage can be surely applied to a piezoelectric body and, at the same time, a sufficiently high adhesive strength can be secured for sticking the piezoelectric body to an vibrating elastic body. CONSTITUTION:When a piezoelectric body is stuck to a vibrating elastic body, a conductive bonding agent 50 is applied to part of an electrode 20 provided on the surface of the piezoelectric body and a nonconductive bonding agent 52 having a strong adhesive strength is applied to the other part of the electrode 20. When the electrode 20 is divided into a plurality of electrodes 40, 42, 44-1, and 44-2, the boding agents 50 and 52 are used for each of the divided electrodes 40, 42, 44-1, and 44-2. The application of a voltage to the piezoelectric body is performed by means of the partially used conductive bonding agent 50 and adhesion of the piezoelectric body to the vibrating elastic body is mainly obtained by means of the nonconductive bonding agent 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, and more particularly to improvement of a bonding structure between a piezoelectric body and a vibrating elastic body of a stator portion thereof.

[0002]

2. Description of the Related Art An ultrasonic motor converts an oscillating motion generated when a frequency voltage such as an alternating current is applied to a piezoelectric body into a rotary motion or a one-dimensional motion. Compared with conventional electromagnetic motors, it does not require windings, so it has the advantages of simple structure and small size, high torque even at low speed rotation, and a small moment of inertia.

Generally, an ultrasonic motor is composed of a rotor which is a moving body, a stator which is a vibrating body, and a support member for supporting them.

Among them, the stator is formed by bonding a piezoelectric body such as PZT (lead zirconate titanate) to a vibration elastic body made of copper alloy or the like. The voltage is applied to the piezoelectric body by connecting one electrode lead to the vibration elastic body and connecting the other electrode lead to the surface of the piezoelectric body opposite to the vibration elastic body. Therefore, the vibration elastic body and the piezoelectric body are bonded to each other by using a conductive adhesive material such as a conductive epoxy resin, or when a non-conductive adhesive material is used, the adhesive layer is thinned as much as possible. It was necessary to establish electrical continuity.

[0005]

However, when the conductive adhesive is used, the electric connection between the piezoelectric body and the vibrating elastic body can be surely achieved, but it is sticking out from the end surface of the piezoelectric body or the vibrating elastic body at the time of adhering. There is a problem that the voltage may not be reliably applied because the adhesive may cause insulation failure and cause current leakage. Further, since the conductive adhesive generally has lower adhesive strength than the non-conductive adhesive, there is a possibility of fatigue due to repetitive stress or peeling due to aging, and there was concern during long-term use.

When a non-conductive adhesive is used,
Since the thickness of the adhesive layer is likely to be non-uniform, there is a problem that electrical continuity may not be ensured.

The present invention has been made in view of the above point, and it is possible to reliably apply a predetermined voltage to the piezoelectric body and to secure sufficient bonding strength in bonding the piezoelectric body. The purpose is to provide a possible ultrasonic motor.

[0008]

In order to solve the above problems, an ultrasonic motor according to the present invention comprises a piezoelectric body provided with front and back electrodes, and a vibration elastic member bonded to the back side of the piezoelectric body. A stator having a body and generating ultrasonic vibration for driving on the surface of the vibrating elastic body by applying a voltage between the surface electrode and the vibrating elastic body; and a vibration generated on the surface of the vibrating elastic body. In a ultrasonic motor including a moving body that moves in a predetermined direction, the piezoelectric body and the vibration elastic body are bonded to each other by using a conductive adhesive as a part of the bonding between the back electrode and the vibration elastic body. It is characterized in that the electrical continuity is ensured and the non-conductive adhesive is used to bond the other parts.

[0009]

The piezoelectric body is bonded to the vibrating elastic body by bonding a part of the facing surface with a conductive adhesive and bonding the other part of the facing surface with a non-conductive adhesive.

As a result, electrical conduction can be achieved through the conductive adhesive material, and a predetermined voltage can be reliably applied to the piezoelectric body.

Further, since the portions other than the portions necessary for conduction are adhered by the non-conductive adhesive material, it is possible to secure sufficient adhesive strength.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the structure of an annular ultrasonic motor according to an embodiment of the present invention.

The ultrasonic motor of the embodiment has a stator 100.
And a rotor 200 that is rotationally driven by ultrasonic vibration generated on the surface of the stator 100.

The stator 100 has a piezoelectric body 12 formed in a ring shape and a vibrating elastic body 10 adhered to one side of the piezoelectric body 12. The piezoelectric body 12 generates mechanical ultrasonic vibration by applying a voltage. The vibrating elastic body 10 is for efficiently transmitting and vibrating the ultrasonic vibration generated in the piezoelectric body 12, and a plurality of notches are radially provided on the surface to increase the amplitude. .. Therefore, the ultrasonic elliptical vibration in the predetermined direction is efficiently generated on the surface of the vibrating elastic body 10.

The rotor 200 includes a ring 16
And a friction material 14 adhered and fixed to the stator contact surface of the ring 16, the friction material 14 being the vibrating elastic body 10.
Is formed so as to come into contact with the surface of the sheet with a predetermined pressure.

Therefore, the driving force by the traveling wave of the ultrasonic vibration generated on the surface of the vibrating elastic body 10 is efficiently transmitted to the rotor 200 by the friction material 14, and the rotor 200 is rotationally driven in the predetermined direction. ..

FIG. 2 is a side view showing a state in which the piezoelectric body 12 is connected to the vibrating elastic body 10. The figure shows an outline of the case where a voltage is applied to the piezoelectric body 12.

In the embodiment, the first electrode 18 and the second electrode 20 for applying a voltage are formed on both sides of the plate-shaped piezoelectric body 12. These electrodes 18 and 20 are formed by baking silver electrodes or the like. And the piezoelectric body 1
2 is adhesively fixed to the vibration elastic body 10 via the adhesive layer 22.

FIG. 3 shows electrode patterns of the first electrode 18 and the second electrode 20 provided on both surfaces of the piezoelectric body 12.

As shown in FIG. 3B, the first electrode 1
Reference numeral 8 is composed of feedback electrodes 30 and 32 and a plurality of input electrodes 34-1, 34-2 ... 34-12 arranged in a ring shape. Accordingly, the regions of the piezoelectric body 12 in which the input electrodes 34-1, 34-2, ... 34-12 are formed function as their own vibration regions.

Further, as shown in FIG. 3 (A), the second electrode 20 is formed with the feedback electrodes 40 and 42 facing the feedback electrodes 30 and 32, respectively.
34-6, and an input electrode 44-1 formed to face the input electrode groups 34-1, 34-2 ... 34-6, and the input electrode group 34-7, 34-8 ... 34-12. And an input electrode 44-2 formed as described above.

The piezoelectric body 12 and the vibrating elastic body 10 are adhered to each other via the adhesive layer 22 as follows. That is, the four electrodes 4 that form the second electrode 20.
The conductive adhesive 50 is partially applied to the vicinity of the center of each of 0, 42, 44-1 and 44-2, and the non-conductive adhesive 52 is applied to the other portions as indicated by the diagonal lines. Has been done. Therefore, the four electrodes 40, 42, 44
-1, 44-2 are surely electrically connected to the vibrating elastic body 12 via the conductive adhesive material 50 applied to each. Although the conductive adhesive 50 is applied to a partial circular area in the figure, it may be applied to an elongated area in the circumferential direction as shown by a dotted line, or may be applied to a plurality of partial areas separately. You may. Then, the outer periphery of the conductive adhesive material 50 thus partially applied is covered with the non-conductive adhesive material 52. By thus distributing the adhesive material, the conductive adhesive material 50 does not stick out to the side surface of the piezoelectric body 12, and the leakage of current can be surely prevented.

Further, in the embodiment, since the non-conductive adhesive 52 having a strong adhesive force is used for most of the adhesion between the piezoelectric body 12 and the vibrating elastic body 10, they can be surely adhered. ..

With the above configuration, in the ultrasonic motor of the embodiment, the second electrode 20 electrically connected to the vibrating elastic body 10, that is, the electrodes 40, 42, 44-1,
All of 44-2 will function as a common ground electrode. Therefore, the piezoelectric body 12 functions similarly to the case where a plurality of piezoelectric bodies having the same shape as the electrodes 30, 32, 34-1, 34-2 ... 34-12 shown in FIG. 3B are arranged in a ring shape. As shown in FIG. 2, each electrode 34-
A traveling wave of ultrasonic vibration can be generated on the surface of the vibrating elastic body 10 by applying a predetermined AC voltage from the power source 10 to the power generators 1, 34-2 ... 34-12.

For example, the power supply 100 includes an oscillator 110 that generates ultrasonic vibrations, an amplifier 112 that outputs the oscillator output as a sine wave, and a phase shifter 116 that changes the phase of the oscillator output by 90 degrees to generate a cosine wave. And a grounding terminal of the oscillator 110 is connected to the vibrating elastic body 10, and the sine wave and the cosine wave output from the amplifiers 112 and 114 are included in the first electrode 18. By applying a predetermined combination to 1, 34-2 ... 34-12, mechanical vibration of ultrasonic waves can be generated in the piezoelectric body 12, and thereby a traveling wave can be generated on the surface of the vibrating elastic body 10. it can.

It is sufficient that the electrode 20 on the adhesive layer 22 side is formed as a single common ground electrode, but a plurality of divided electrodes 40, 42, 44-1 and 44 are used as in this embodiment.
In the case of being formed as -2, the piezoelectric body 12 is turned over and used, and the first electrode 18 is interposed between the elastic vibrating body 1 and the adhesive layer 22.
It is also possible to adhere and fix it to 0.

In this case, as shown in FIG. 4 (B), the plurality of electrodes 30, 32, 34-constituting the first electrode 18 are formed.
1, 34-2 ... 34-12 near the center of the conductive adhesive 5
0 is partially applied, and the non-conductive adhesive material 52 is applied to the other parts.

Thus, the piezoelectric body 12 can be securely bonded and fixed to the vibrating elastic body 10 while ensuring electrical conduction between the first electrode 18 and the vibrating elastic body 10.

At this time, as shown in FIG.
Since the second electrode 20 as shown in (A) is formed,
The piezoelectric body 12 includes a plurality of electrodes 4 that form the second electrode 20.
This means that a plurality of piezoelectric bodies having the same shape as 0, 42, 44-1 and 44-2 function similarly to the case where they are arranged in a ring shape.

As is clear from the above description, the adhesive layer 2
Although it is not necessary to divide the electrode on the second side into a plurality of electrodes, the first and second electrodes 18 and 20 formed on both surfaces of the piezoelectric body 12 as in the present embodiment, as shown in FIGS. If divided, there is an advantage that the surface to be bonded can be changed and used depending on the application.

In particular, in the case where the piezoelectric body 12 in which the electrode on the adhesive layer side is divided into a plurality of pieces is used as in the embodiment, when the piezoelectric body 12 is bonded to the vibrating elastic body 10, as described above. It is extremely effective to partially use the conductive adhesive 50. That is, by connecting the plurality of divided electrodes to the piezoelectric body 12 via the conductive adhesive material, the two are surely electrically connected to each other, and the piezoelectric body 12 does not have to worry about current leakage. A voltage can be applied to.

Further, by using a non-conductive adhesive material having an excellent adhesive force for the other portions, sufficient adhesive strength can be secured. Further, since the conduction is not achieved by making the adhesive layer 22 thin, the adhesive layer 22 can be made thick. For example, when PZT is used as the piezoelectric body 12, there is a large difference in thermal expansion coefficient between the metal used as the vibrating elastic body 10 and PZT which is ceramics, and the stress caused by this difference in thermal expansion coefficient is increased by the thick adhesive layer 22. It can absorb and improve the reliability of adhesion due to temperature change.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention.

For example, although the ultrasonic motor of the type using one piezoelectric body 12 has been described in the above embodiment, a plurality of piezoelectric bodies 12 are bonded to the vibrating elastic body 10 as shown in FIG. 5, for example. The present invention can be applied to an ultrasonic motor of the type used.

Further, although the annular ultrasonic motor has been described in the above embodiments, the present invention can be applied to the case where a piezoelectric body is adhered to a disk ultrasonic motor or a linear ultrasonic motor. it can.

[0037]

As described above, according to the present invention,
The piezoelectric body is bonded to the vibrating elastic body partially by a conductive adhesive material and the other parts by a non-conductive adhesive material so that the applied voltage can be conducted through the conductive adhesive material. It becomes possible to reliably apply a predetermined voltage to the body. In addition, since the non-conductive adhesive is used to bond the parts other than the part necessary for conduction, it is possible to secure sufficient bonding strength.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of an annular ultrasonic motor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a piezoelectric body is bonded to a vibration elastic body.

FIG. 3 is a diagram showing an electrode pattern formed on a surface of a piezoelectric body and application distributions of a conductive adhesive material and a non-conductive adhesive material of an adhesive layer.

FIG. 4 is a diagram showing an electrode pattern formed on the surface of a piezoelectric body and application distributions of a conductive adhesive and a non-conductive adhesive of an adhesive layer.

FIG. 5 is an explanatory view of another embodiment for adhering a plurality of divided piezoelectric bodies.

[Explanation of symbols]

10 vibration elastic body 12 piezoelectric body 14 friction material 16 ring 18 first electrode 20 second electrode 22 adhesive layer 30, 32, 40, 42 feedback electrode 34-1, 34-2 ... 34-17 input electrode 44- 1, 44-2 Input electrode 50 Conductive adhesive 52 Non-conductive adhesive
AS011101

Claims (1)

[Claims] 1. A piezoelectric body provided with a front surface electrode and a back surface electrode, and a vibrating elastic body adhered to the back surface side of the piezoelectric body, and a voltage is applied between the front surface electrode and the vibrating elastic body. An ultrasonic motor including: a stator that generates ultrasonic vibration for driving on the surface of the vibrating elastic body; and a moving body that moves in a predetermined direction by the vibration generated on the surface of the vibrating elastic body. For the adhesion with the vibration elastic body, a conductive adhesive is used for a part of the adhesion between the back electrode and the vibration elastic body to ensure electrical conduction between the two, and a non-conductive adhesive is used for the adhesion of the other parts. An ultrasonic motor characterized in that the ultrasonic motor is used.