JPH0251379A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To stabilize an ultrasonic motor, and to improve output efficiency by fixing a plurality of the laminated type piezoelectric elements of thickness vibrations onto the plane section of the ring-shaped laminated type piezoelectric element of torsional vibrations and pressing and bringing into contact a moving body. CONSTITUTION:A stator section for a ultrasonic motor has the ring-shaped laminated type piezoelectric element 1 of torsional vibrations and the laminated type piezoelectric elements 2 of thickness vibrations. The piezoelectric elements 2 are fastened to the piezoelectric element 1, and a rotor is pressed and brought into contact directly with the top faces of the laminated type piezoelectric elements 2 of thickness vibrations, thus constituting the ultrasonic motor. When the piezoelectric element 1 and the piezoelectric elements 2 are driven similarly, oblique vibrations are generated in the piezoelectric elements 2, and the rotor is pressed and brought into contact with the piezoelectric elements 2, thus rotating and moving the rotor on the piezoelectric elements 2. When the rotor is driven by the phase difference of 90 deg., elliptical vibrations are generated, and the piezoelectric elements 2 are turned when the rotor is pressed and brought into contact with the piezoelectric elements 1.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an ultrasonic motor using piezoelectric elements.

(Prior Art) Ultrasonic motors using piezoelectric elements are being researched and developed, but their principles and structures vary. For example, an ultrasonic motor that performs rotational motion using elastic traveling waves has a plurality of piezoelectric elements 12 attached to an elastic ring 11, as shown in an exploded perspective view in FIG. When the elastic ring 11 is sequentially driven using different signals, an elastic traveling wave that performs a circular motion is generated in the elastic ring 11, and this elastic traveling wave rotates the rotor 13 that is brought into pressure contact with the elastic ring 11.

In an ultrasonic motor with such a configuration, a ring is required to generate a bony traveling wave in the ring and obtain driving force, which limits the degree of freedom in design. It had to be driven by a signal, which necessitated an increase in the size of the drive circuit. Furthermore, since the amplitude of the elastic traveling wave generated in the elastic ring is minute, there are various problems such as the need to expand the displacement or improve efficiency.

(Problems to be Solved by the Invention) The present invention provides an ultrasonic motor that uses standing waves to provide a high degree of freedom in design, stability, and high output efficiency.

[Structure of the Invention] (Means for Solving the Problems) The ultrasonic motor according to the present invention has a plurality of laminated piezoelectric elements that vibrate in thickness fixed to a plane part of a laminated piezoelectric element that vibrates torsionally in a ring shape. The movable body is brought into pressure contact with this thickness-vibrating laminated piezoelectric element directly or via a driving member.

(Function) The ultrasonic motor according to the present invention uses not an elastic traveling wave (
, an ultrasonic motor is constructed from a laminated piezoelectric element with torsional vibration, a laminated piezoelectric element with thickness vibration, and a moving body placed on top of the piezoelectric element, and the generated standing waves are used, so there is a high degree of freedom in design and non-resonance. It can also be driven in mode, stable and high output can be obtained, and the drive circuit can be made small and simple.

(Example) Fig. 1 shows a perspective view of the stator section of the ultrasonic motor of the present invention, in which 1 is a ring-shaped torsional vibration WI layer type piezoelectric element, and 2 is a thickness vibration laminated type piezoelectric element. , this piezoelectric element 2 is fixed to the piezoelectric element 1. When the rotor is brought into pressure contact directly with the top surface of this thickness-vibrating laminated piezoelectric element 2,
An ultrasonic motor is configured.

In the ultrasonic motor having this configuration, as shown in FIG.
nωt), the piezoelectric element 2 generates an oblique vibration as shown by 3, and by bringing the rotor into pressure contact with this vibration, the rotor rotates on the piezoelectric element 2.

Further, as shown in FIG. 3, the piezoelectric element 1 is
(t) t, piezoelectric element 2 as V o CO3(t)
When driven at 4, an elliptical vibration as shown at 4 occurs, and when the rotor is brought into pressure contact with this, it rotates.

In this example, the piezoelectric element 1 and the piezoelectric element 2 are fixed to form a stator, but they may also be fixed with a connecting body such as a metal or ceramic between them. A drive member having a rotor may be fixed and brought into contact with the rotor.

[Effects of the Invention] The ultrasonic motor according to the present invention uses a standing wave instead of an elastic traveling wave, so the ultrasonic motor has a high degree of freedom in design, is stable,
Since a high-output motor can be realized and can be driven in a non-resonant mode, the drive circuit and control circuit can also be made small and simple.

In addition, since a laminated piezoelectric element is used, low voltage and
It is possible to drive with low power, and is fast and highly efficient.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention, FIG. 1 is a perspective view showing the stator section of the ultrasonic motor, and FIGS. 2 and 3 are the stator parts of the ultrasonic motor shown in FIG. 1. FIG. 4 is an exploded perspective view showing a conventional ultrasonic motor. 1...Laminated piezoelectric cord with torsional vibration 2...
・Patent application for laminated piezoelectric cord with thickness vibration
Hito Marukon Electronics Co., Ltd.A perspective view of the stator section of an ultrasonic motor.Figure 1.Explanatory diagram showing the vibration displacement of the stator section.Figure 2.Explanatory diagram showing the vibration displacement of the stator 9 section.Figure 3.Figure 3.

Claims (2)

[Claims] (1) A plurality of thickness-vibrating laminated piezoelectric elements are fixed on the flat surface of a ring-shaped torsionally vibrating laminated piezoelectric element, and a moving body is applied to the thickness-vibrating laminated piezoelectric elements directly or via a drive member. Ultrasonic motor that uses pressure contact. (2) The ultrasonic motor according to claim (1), wherein a plurality of thickness-vibrating integral piezoelectric elements are fixed to the flat surface of the ring-shaped torsionally vibrating laminated piezoelectric element via a connecting body.