JPH04304174A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To prevent a piezoelectric element against exfoliation from an oscillator and to protect the piezoelectric element against breakdown by forming coating layers on the adhesion interfaces between an electrostriction element, an electrode and a resilient member. CONSTITUTION:A piezoelectric member 11 is adhered to the rear of a resilient member 10 and an electrode 12 is adhered to the rear of the piezoelectric member. The electrode 12 is formed slightly larger than the radial width of the resilient member 10 and the electrode 12 is adhered to the piezoelectric member 11 so that the electrode 12 projects from the resilient member 10 at the opposite ends thereof. In a stator 3 having such constitution, a coating layer 14 is formed between the adhering faces of the piezoelectric member 11 and the electrode 12. The coating layers 14 are formed on both inner and outer peripheral faces of the stator 3. Since exfoliation of the piezoelectric member from the resilient member and breakdown of the piezoelectric member can be avoided by such technical means, an ultrasonic motor having stabilized output characteristics can be obtained.

Description

[Detailed description of the invention]

0001

[Purpose of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traveling wave type ultrasonic motor, and more particularly to a moisture-resistant structure of a vibrating body of an ultrasonic motor.

0003

[Prior Art] Part 5 regarding the prior art related to the present invention
This will be explained using FIG.

In FIG. 5, a stator 50 is constructed by bonding a piezoelectric material 52 made of an electrostrictive element such as PZT (lead zirconate titanate) to a vibrating body 51 made of an elastic material and having two parallel annular surfaces. ing. Further, the rotor 54 had a structure 55 made of an elastic material and a slider 56 made of a highly wear-resistant material such as engineering plastic bonded thereto. The stator 50 is fixed to the case 58 with screws 59, and includes a spring 60 and a spacer 61.
A constant pressing force is applied between the rotor 54 and the rotor 54 by the snap spring 62.

Still referring to FIG. 6, the stator 50
discloses that a piezoelectric body 52, which is an electrostrictive element, is bonded to a vibrating body 51.

[0006]

However, in a conventional ultrasonic motor, it has been shown that a piezoelectric resistor made of an electrostrictive element is directly bonded to the stator using an adhesive. However, since the adhesive strength of the adhesive is significantly reduced depending on the ambient temperature or humidity, there is a risk that the piezoelectric body may peel off from the vibrating body. Furthermore, there was a possibility that the strength of the piezoelectric body would decrease due to changes in humidity, resulting in malfunction of the ultrasonic motor.

The present invention has been made to solve the problems of the prior art described above, and provides an ultrasonic motor and an ultrasonic motor that can eliminate separation of the piezoelectric element from the vibrating body and damage to the piezoelectric body. The challenge is to do so.

[0008]

[Structure of the invention]

[0009]

[Means for Solving the Problems] The technical means taken to solve these technical problems are: an electrostrictive element; an electrode that allows power to be supplied to the electrostrictive element; a rotor; In an ultrasonic motor in which an annular elastic body is bonded to an electrostrictive element and the electrode, and the rotor is frictionally driven in contact with the surface of the elastic body by a traveling wave generated on a predetermined surface area of the elastic body. The ultrasonic motor is characterized in that a coating layer is formed on an adhesive interface between the electrostrictive element, the electrode, and the elastic body.

0010

[Operation] By using the above technical means, it is possible to avoid separation of the piezoelectric material from the elastic material and damage to the piezoelectric material, making it possible to create an ultrasonic motor with stable output characteristics. .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partially sectional perspective view of an ultrasonic motor 1 to which the present invention is applicable. Stator 3 is on base 2
At the same time, a shaft 5 is disposed via a bearing 4 so as to be rotatable with respect to the base 2. Note that the detailed configuration of the stator 3 will be described later. A rotor 6 is disposed on the periphery of the stator 3 so as to be rotatable around the stator 3. A disc spring 7 is interposed between the rotor 6 (rotor) and the shaft 5, so that the shaft 5 rotates following the rotation of the rotor 6. Furthermore, electrodes (based on a flexible printed circuit) for supplying power to the stator 5 are connected to the lower surface of the stator 5 . Since the configuration of the ultrasonic motor 1 shown above is a well-known technique, further detailed explanation will be omitted.

Next, the structure of the stator 3 will be explained. The stator 3 includes an annular elastic body 10, a piezoelectric body 11 made of an electrostrictive element, and electrodes 12. The elastic body 10, piezoelectric body 11, and electrode 12 are bonded to each other with an adhesive. 13 is a bonding layer made of adhesive.

A first embodiment of the stator 3 according to the present invention will be described with reference to FIG. In this embodiment, the elastic body 10
A piezoelectric body 11 was bonded to the bottom surface of the piezoelectric body, and an electrode 12 was further bonded to the bottom surface of the piezoelectric body. The electrode 12 is formed to be slightly larger than the radial width of the elastic body 10, and is bonded to the piezoelectric body 11 so that both ends of the electrode 12 protrude beyond the elastic body 10. In the stator 3 having the above configuration, a coating layer 14 is formed on the bonding surface of the portion where the piezoelectric body 11 and the electrode 12 are bonded. This coating layer 14 is formed on both the outer and inner circumferences of the stator 3.

A second embodiment of the stator 3 according to the present invention will be described with reference to FIG. In this embodiment, the elastic body 10
The configuration of the piezoelectric body 11 and electrode 12 bonded to the lower surface of the first
Same as the example. In the second embodiment, a coating layer 14 is formed entirely on the lower surface of the stator 3.

Furthermore, FIG. 4 shows a stator 3 according to the present invention.
This is the third embodiment. In this embodiment, an electrode 12, a piezoelectric body 11, and an electrode 12 are sequentially laminated on the lower surface of an elastic body 10 and bonded to the elastic body 10. Each electrode 12 is formed to be slightly larger than the width of the elastic body 10 in the radial direction, and is bonded to the piezoelectric body 11 so that both ends of the electrode 12 protrude beyond the elastic body 10. In the stator 3 having the above configuration, a coating layer 14 was formed by coating on the bonding surface of the portion where the piezoelectric body 11 and the electrode 12 are bonded. That is, the coating layer 14 is formed so as to wrap around the electrodes 12 protruding from both the outer and inner circumferences of the stator 3.

[0017]

[Effects of the Invention] As explained above, by using the stator of the ultrasonic motor of the present invention, separation of the piezoelectric body from the vibrating body and reduction in strength of the piezoelectric body due to changes in humidity can be prevented. This makes it possible to avoid malfunctions of the ultrasonic motor.

[Brief explanation of drawings]

FIG. 1 is a partially sectional perspective view showing an embodiment of an ultrasonic motor to which the present invention is applied.

FIG. 2 is a sectional view of the stator portion of the ultrasonic motor.

FIG. 3 is a sectional view of the stator portion of the ultrasonic motor.

FIG. 4 is a sectional view of the stator portion of the ultrasonic motor.

FIG. 5 is a sectional view of an ultrasonic motor according to the prior art.

FIG. 6 is a perspective view of a stator of an ultrasonic motor according to the prior art.

[Explanation of symbols]

11 Electrostrictive element (piezoelectric body) 12 Electrode 9 Rotor (rotor) 10 Elastic body 14 Coating layer

Claims (1)

[Claims] 1. An electrostrictive element; an electrode that allows power to be supplied to the electrostrictive element; a rotor; and a ring-shaped elastic body that is attached to the electrostrictive element and the electrode, and that is attached to a predetermined surface of the elastic body. In the ultrasonic motor that frictionally drives the rotor in contact with the surface of the elastic body by a traveling wave generated in the area, a coating layer is formed on an adhesive interface between the electrostrictive element, the electrode, and the elastic body. An ultrasonic motor featuring: