A piezoelectric drive device includes a piezoelectric drive portion which includes a contact portion capable of coming into contact with a driven body and a piezoelectric material, and a drive circuit which drives the piezoelectric drive portion. The drive circuit sets an allowable maximum output torque Tlim or less to an allowable output torque range, sets output torque Td of the piezoelectric drive portion so as to be within the allowable output torque range, and operates the piezoelectric drive portion. The allowable maximum output torque Tlim is expressed by the following Expression (1).
Tlim=r1×μk×Ns×fs  (1)
In the expression, r1 is a distance between a rotation center of the driven body and a contact position of the contact portion, μk is a dynamic friction coefficient between the driven body and the contact portion, Ns is a pressing force by which the contact portion presses the driven body when an operation of the piezoelectric drive portion stops, and fs is a coefficient of 1 or less.

A piezoelectric drive device includes a piezoelectric drive portion which includes a contact portion capable of coming into contact with a driven body and a piezoelectric material, and a drive circuit which drives the piezoelectric drive portion. The drive circuit sets an allowable maximum output torque Tlim or less to an allowable output torque range, sets output torque Td of the piezoelectric drive portion so as to be within the allowable output torque range, and operates the piezoelectric drive portion. The allowable maximum output torque Tlim is expressed by the following Expression (1).
Tlim=r1×μk×Ns×fs  (1)
In the expression, r1 is a distance between a rotation center of the driven body and a contact position of the contact portion, μk is a dynamic friction coefficient between the driven body and the contact portion, Ns is a pressing force by which the contact portion presses the driven body when an operation of the piezoelectric drive portion stops, and fs is a coefficient of 1 or less.

An optical scanning device includes an optical deflector, a driving unit, and a detection unit. The optical deflector has a mirror part and an H actuator. The driving unit supplies both of a first driving voltage and a second driving voltage to a first set of piezoelectric divided sections and a second set of piezoelectric divided sections of the H actuator during a first driving period, and supplies the driving voltage only to one set out of the first set and the second set of piezoelectric divided sections during a second driving period. The detection unit detects a deflection angle γ based on the output voltage of the other set of piezoelectric divided sections during the second driving period.

An optical scanning device includes an optical deflector, a driving unit, and a detection unit. The optical deflector has a mirror part and an H actuator. The driving unit supplies both of a first driving voltage and a second driving voltage to a first set of piezoelectric divided sections and a second set of piezoelectric divided sections of the H actuator during a first driving period, and supplies the driving voltage only to one set out of the first set and the second set of piezoelectric divided sections during a second driving period. The detection unit detects a deflection angle γ based on the output voltage of the other set of piezoelectric divided sections during the second driving period.

A piezoelectric drive device includes a rotor which has an output section for outputting a rotational force and a transmission section disposed on an outer periphery of the output section, and rotates around a rotational axis, and a vibrating part which has a piezoelectric element, and rotates the rotor due to a deformation of the piezoelectric element. The transmission section has a first portion and a second portion different from each other in position in a radial direction from the output section toward the transmission section, the first portion is coupled to the output section, the second portion is higher in Young's modulus than the first portion, the second portion is higher in mass per unit volume than the first portion, and the vibrating part makes contact with the transmission section at a position overlapping the second portion in a plan view from an axial direction of the rotational axis.

A piezoelectric drive device includes a rotor which has an output section for outputting a rotational force and a transmission section disposed on an outer periphery of the output section, and rotates around a rotational axis, and a vibrating part which has a piezoelectric element, and rotates the rotor due to a deformation of the piezoelectric element. The transmission section has a first portion and a second portion different from each other in position in a radial direction from the output section toward the transmission section, the first portion is coupled to the output section, the second portion is higher in Young's modulus than the first portion, the second portion is higher in mass per unit volume than the first portion, and the vibrating part makes contact with the transmission section at a position overlapping the second portion in a plan view from an axial direction of the rotational axis.

Provided is a method for controlling an ultrasonic motor provided at a rotary shaft of a surveying instrument to meet requirements for a rotation speed and a plurality of operation modes, and a surveying instrument for the same. In the present invention, the ultrasonic motor is controlled by a first signal having a square wave in a range of rotation speed of the rotary shaft from zero to a first speed, controlled by a second signal in which rises or falls of the square wave are sloped in a range from the first speed to a second speed, controlled by a third signal in which rises and falls of the square wave are sloped in a range from the second speed to a third speed, and controlled by a fourth signal in which the drive signal is continuously applied in a range higher than the third speed.

Information regarding a rotational speed is detected by utilizing a variation in the amplitude at a frequency corresponding to the number of a plurality of protrusions of a vibrating member generated in an S-phase signal detected from a vibration detection electrode of a vibration-type actuator.

Information regarding a rotational speed is detected by utilizing a variation in the amplitude at a frequency corresponding to the number of a plurality of protrusions of a vibrating member generated in an S-phase signal detected from a vibration detection electrode of a vibration-type actuator.

A drive device for a vibration actuator, which makes it possible to perform low-speed and stable driving and expand a dynamic range of driving speed. A first switching circuit and a second switching circuit apply a first drive signal and a second drive signal for exciting vibration, to an electromechanical energy conversion element of a vibrating body. A position detection sensor acquires information on a relative position between the vibrating body and a driven body in pressure contact with each other. An MPU switches the first and second drive signal to a third drive signal and a fourth drive signal, respectively, based on the acquired information, to thereby change a position at which a largest one of peaks of amplitude of vibration excited in the vibrating body is formed.