There is provided a medical device whose occupied space is reduced. According to an aspect of the present invention, a medical device (1) adjusts a position of a medical instrument including a rod-like insertion unit (201) for being inserted into a body. The medical device includes an ultrasonic actuator that holds the insertion unit of the medical instrument, and that displaces or rotates the insertion unit with respect to the ultrasonic actuator, and an actuator fixing unit (101 and 102) that fixes a position of the ultrasonic actuator to a surgical site.

A vibration wave motor comprises: an electromechanical conversion element; an elastic body which has a drive surface on which a vibration wave is generated due to vibration of the electromechanical conversion element; and a relative motion member which makes contact with the drive surface of the elastic body and is configured to rotationally drive by the vibration wave, the electromechanical conversion element having a density of from 4.2 to 6.010.sup.3 kg/m.sup.3, a plurality of grooves being provided on the drive surface side of the elastic body, and a value of T/(B+C) being within a range of from 1.3 to 2.8 when: depth of at least one groove of the plurality of grooves is defined as T; thickness from a base unit of the groove to a first surface is defined as B; and thickness of the electromechanical conversion element is defined as C.

A hollow-cylindrical ultrasonic actuator is disclosed a central axis, an inner peripheral surface facing the central axis and an outer peripheral surface facing away from the central axis and spaced apart from the inner peripheral surface, a closed inner contour curve, a closed outer contour curve, at least one electrode, and an electromechanical material provided between opposed electrodes. In a non-actuated state of the ultrasonic actuator, a curvature of the inner contour curve or of an outer contour curve includes at least three mutually spaced-apart local maximum points.

An ultrasonic motor includes an actuator with a piezo-electric plate, at least one friction element, an element to be driven in active contact with the friction element, a tensioning device for pressing the friction element against the element to be driven, and a thermo-compensation platform having abutting sections by which displacement of the actuator is only possible along abutting side surfaces of the piezo-electric plate. The tensioning device includes two rotation angle levers of which two tension lever arms are connected to one another via a tensioned tension spring, to exert torque on the rotation angle lever such that pressure lever arms will act on the actuator to be linearly guided by the abutting sections in the direction of the element to be driven.

Provided is a vibration wave motor including: a vibrator; a friction member that comes into frictional contact with the vibrator; a press member that pressurizes the vibrator and the friction member into frictional contact with each other; a first guide member and a second guide member that guide the vibrator and the friction member so as to allow relative movement of the vibrator and the friction member; a hold member that holds the friction member and the first guide member; and a fixing member. The friction member and the first guide member are fixed to the hold member with the fixing member.

Provided is a vibration wave motor, including: a vibrator; a friction member, which is in friction contact with the vibrator; a pressurizing unit, which is configured to pressurize the vibrator against the friction member; and a guiding unit, which is configured to guide relative movement between the vibrator and the friction member, wherein the relative movement between the vibrator and the friction member is caused by vibration generated by the vibrator, and wherein the guiding unit holds the friction member and has fixing portions, and the fixing portions are formed in the guiding unit in vicinities of both ends of the guiding unit sandwiching the friction member.

A vibration wave motor includes a vibrator, a pressing member configured to press the vibrator against a friction member, a holding member configured to hold the vibrator, and a buffering member provided between the vibrator and the holding member. The vibrator and the friction member are moved relatively to each other in a relative movement direction by vibration of the vibrator, and the holding member holds the vibrator in such a manner that an extending part extending in a pressing direction of the pressing member sandwiches the vibrator and the buffering member.

A vibration wave motor including: a vibrator; a friction member; and a pressurizing member configured to press the vibrator and the friction member into contact with each other. The vibrator and the friction member are relatively moved in a direction orthogonal to the pressurizing direction of the pressurizing member by vibrations generated on the vibrator, the vibrator and the friction member are configured so as to move in parallel with the pressurizing direction with respect to a fixed member, and the vibration wave motor further includes at least one first restricting portion that restricts a movable amount of the friction member in the pressurizing direction and at least one second restricting portion that restricts a movable amount of the vibrator in the pressurizing direction, such that the movable amount of the friction member is smaller than the movable amount of the vibrator in the pressurizing direction.

A vibration motor includes a vibrator, a friction member, and a pressurizing unit. The vibrator includes projecting portions and is vibrated by application of a driving voltage. The projecting portions are arranged in vicinities of nodes of the vibration, respectively. The friction member has a sliding surface formed of a curved surface with which the projecting portions come into contact. The pressurizing unit pressurizes the vibrator against the friction member with a pressurizing force. When the vibrator is vibrated, a driving force is generated in a tangential direction of the sliding surface by the vibration to drive the friction member relative to the vibrator, and each of the projecting portions generates an elliptic motion by the vibration. The elliptic motion is generated with an inclination at a predetermined angle with respect to the curved surface of the sliding surface.

A thin vibration wave motor is provided by thinning a friction member of the vibration wave motor. In a vibration wave motor including: a vibrator including a piezoelectric element and a vibration plate; and a friction member including a frictional contact surface to be brought into contact with the vibrator, the vibrator and the friction member being moved relative to each other using vibration generated in the vibrator, the vibration plate includes a flat plate portion to which the piezoelectric element is fixed and projection portions to be brought into contact with the friction member, and the friction member includes at least one reinforcing portion that increases a strength of the friction member along a direction of the relative movement, in a region between the flat plate portion and the friction member.