Abstract: A wafer with a reversed domain is prepared for two piezoelectric single crystal plates 11 and 12 having about the same thickness as each other by using direct bonding without any adhesive. Then, driving electrodes 13 are formed on two principal planes of the wafer with a reversed domain to provide a piezoelectric resonator. A piezoelectric resonator having the structure with a reverses polarization and using odd-order vibration modes vibrating with a fundamental wave has a wavelength of a thickness thereof suppresses scattering of the thickness of the domains with a reversed polarization. In the direct bonding, the axes of the spontaneous polarization of the two piezoelectric single crystal plates are reverse to each other and crystalline axes other than the axes of polarization are shifted intentionally by an angle other than zero. Thus, spurious modes are suppressed in a simple way.

Abstract: The present invention relates to a method for driving an ultrasonic motor of the type which includes a vibrator for causing a flexural vibration wave in response to a pair of AC driving voltage signals, and a rotor in contact with the vibrator and moved by the flexural vibration wave. The rotational speed of the ultrasonic motor is controlled by using a feedback signal and a data table, the feedback signal indicating the current rotational speed of the ultrasonic motor, and the data table storing values of the feedback signal as a standard function of the rotational 21 speed. The method includes the step of sampling the feedback signal and detecting the rotational speed in a plurality of rotation states of the ultrasonic motor. The method obtains an approximate function representing the relationship between the sampled feedback signal and the detected rotational speed of the ultrasonic motor, and calculates correction coefficients for adjusting the approximate function to the standard function.

Abstract: A position where the projection member is disposed is optimized by the product of a vibration displacement distribution of a vibration member composed of an elastic member for exciting the primary elastic progressive waves or more in the radial direction and the tertiary elastic progressive waves or more in the peripheral direction, and a generation force distribution of a vibration member to be caused in accordance with the pressure force so that the motor output is made larger. The construction is optional in accordance with the necessary characteristics, and the characteristics are superior by the shape of the supporting means of the vibrating member and the vibration member, thus providing an ultrasonic motor of higher stability.

Abstract: An ultrasonic motor which achieves uniform contact between the vibrating body and the moving body and features high output transfer efficiency and high reliability, and by which the manufacturing process for the moving body thereof can be simplified and the moving body made lighter.By comprising the moving body of a carbon fiber reinforced resin composite material reinforced by at least carbon fiber, and constructing the moving body with a both-side supported or single-side supported beam construction, elasticity according to the pressure of the ultrasonic motor can be imparted in the direction of pressure of the moving body. Thus, the undulations in the contact surface of the vibrating body and the moving body can be absorbed and stable, uniform contact can be assured, and long-term maintenance of a stable friction condition can be achieved.

Abstract: An ultrasonic motor comprising vibrating body, piezoelectric body for exciting an elastic travelling wave in the vibrating body and moving body driven by the elastic travelling wave provides plural vibration amplitude detection electrodes for detecting an amplitude of vibration of the vibrating body these output signals from which are utilized to identify the magnitude of vibration amplitude of the vibrating body and the ultrasonic motor is controlled using the magnitude of vibration amplitude as a control index.

Abstract: A bimorph element is formed by bonding first and second piezoelectric bodies together with an elastic shim interposed between. The bimorph element is firmly held by a base frame which has a recess and a groove at the bottom of the recess. The elastic shim 103 has an extending portion which is firmly inserted in the groove and its end portion is inserted in the recess of the base frame. A space between the recess and the end portion of the bimorph element is filled by an elastic support member.

Abstract: In an ultrasonic motor having a rotor (6,12) and a vibrating stator (43,49) wherein travelling wave is excited to drive the rotor, the vibrating stator comprises a piezoelectric member (25,26,29,60) and alternately-disposed first segment electrodes and second segment electrodes, the first segment electrodes being connected with each other to form a first intermittent ring or linear electrode train and the second segment electrodes being connected with each other to form a second intermittent ring or linear electrode train, each of the segment electrodes having a length of a quarter of wavelength of the travelling wave in the direction of the travelling wave and being to be polarized in an opposite direction to adjacent electrodes within the same segment electrode.

Abstract: An ultrasonic motor achieves uniform contact between a vibrating body and a moving body and features high output transfer efficiency and high reliability. The manufacturing process for the moving body can be simplified and the moving body made lighter by making the moving body of a carbon fiber reinforced resin composite material reinforced by at least carbon fiber, and constructing the moving body with a both-side supported or single-side supported beam construction. Elasticity according to the pressure of the ultrasonic motor can be imparted in the direction of pressure of the moving body. Thus, the undulations in the contact surface of the vibrating body and the moving body can be absorbed, stable, uniform contact can be assured, and long-term maintenance of a stable friction condition can be achieved.

Abstract: In a linear-type actuator where an elastic wave is excited upon the vibrator composed of a rod shaped elastic member and a piezo member so as to drive the moving member bought into pressure contact upon the vibrator, the present invention provides a linear-type actuator where the improvement of the driving efficiency and the simplification of the driving circuit can be achieved by the new driving principle.

Abstract: An ultrasonic motor has a circular vibrator and a mover which is pressed into contact with the circular vibrator. A circular elastic member which constitutes the circular vibrator has a uniform thickness along a circumferential direction thereof, and has a plurality of recesses on a face of the circular elastic member opposing the mover. According to the above structure, uniform elastic travelling waves are generated in the circular elastic member of the vibrator, and a uniform contact is attained between the vibrator and the mover, and yet the development of cracks at bottoms of the recesses is prevented. A ring-like recess is provided on another elastic member which constitutes the mover.

Abstract: A method of driving an ultrasonic motor having a rotation body (6) which is rotated by travelling waves generated in a vibrator body (3), whereby the drive frequency of the motor is controlled in accordance with the value of an operating parameter such as phase difference between drive current and voltage, such as to maintain the drive frequency at a value which is lower than the antiresonance frequency of the vibrator body (3) and higher than a highest resonance frequency of the vibrator body (3) in a hysteresis loop exhibited by a resonance frequency characteristic of the vibrator body (3). Continuous stable operation is attained, irrespective of the effects of temperature and load changes upon the motor operating characteristics.

Abstract: In an ultrasonic motor wherein an elastic travelling wave is excited in a vibrating stator comprising a piezoelectric element and an elastic element thereby to drive and a rotor which is disposed to touch the vibrating stator with pressure by friction forces, an ultrasonic motor having high efficiency is obtained. In the present invention, the above-mentioned vibrating stator is substantially disk-type, electrodes being provided to the piezoelectric element are disposed in a form of two sets of concentric circles having different phases with respect to each other in a circumferential direction in which the vibration is travelling, and have a constitution which excites the vibrating stator by flexural vibration modes of second order or higher in a radial direction and of third order or higher in the circumferential direction, and also, are designed so that at least mechanical impedances seen from each electrode become equal.