Ultrasonic transducer

An ultrasound treatment system comprising:

• an energy controller configured to output electric energy, and control output of the electric energy;
• an ultrasound transducer that is connected to the energy controller, and configured to propagate ultrasonic vibration, the ultrasound transducer including:
• a piezoelectric device configured to generate ultrasonic vibration from supplied electric energy along a longitudinal axis;
• a proximal end block arranged on a proximal end side of the piezoelectric device along the longitudinal axis;
• and
• a distal end block arranged on a distal end side of the piezoelectric device opposite to the proximal end side, the distal end block including, sequentially in a direction from a proximal end of the distal end block to a distal end of distal end block along the longitudinal axis:
• a first portion adjacent to the piezoelectric device, the first portion including a supported portion;
• a second portion adjacent to the first portion;
• and
• a third portion adjacent to the second portion, the third portion having a cross-sectional area perpendicular to the longitudinal axis that differs from a cross-sectional area of the second portion perpendicular to the longitudinal axis;
• and
• an ultrasound treatment tool that is connected to the ultrasound transducer, and configured to treat a subject with the ultrasonic vibration propagated from the ultrasound transducer,
• wherein:
• the distal end block is configured such that a position of a boundary between the second portion and the third portion corresponds to or substantially corresponds to an antinode of the ultrasonic vibration in a state in which the piezoelectric device generates the ultrasonic vibration, and the ultrasonic vibration is propagated to the proximal end block, the first portion, the second portion, and the third portion, and
• a resonance frequency of the ultrasonic vibration depends on a position of the boundary between the second portion and the third portion under a condition that a distance from the supported portion to a distal end of the third portion along the longitudinal axis is a predetermined distance.

A method for manufacturing an ultrasound treatment tool, comprising:

• assembling a distal end block that is configured to propagate ultrasonic vibration generated by an ultrasonic vibrator, the distal end block including sequentially in a direction from a proximal end to a distal end of the distal end block along a longitudinal axis:
• a first portion adjacent to the ultrasonic vibrator, the first portion including a supported portion;
• a second portion adjacent to the first portion;
• and
• a third portion adjacent to the second portion, the third portion having a cross- sectional area perpendicular to the longitudinal axis different from a cross-sectional area perpendicular to the longitudinal axis of the second portion;
• and
• determining a position at which a boundary between the second portion and the third portion corresponds to or substantially corresponds to an antinode of the ultrasonic vibration in a state in which the ultrasonic vibration is propagated at a predetermined resonance frequency as a reference position;
• wherein a resonance frequency of the ultrasonic vibration differs according to the position of the boundary between the second portion and the third portion along the longitudinal axis relative to the reference position under a condition that a distance from the supported portion to a distal end of the third portion along the longitudinal axis is constant.