Ultrasonic motor

Piezoelectric motors which are used to move the focusing elements in some autofocus lenses.

Ultrasonic motors work by applying an electric current to a piezoelectric material - one which changes shape when the current is applied. The very small shape change, repeated thousands of times a second, rotates one part of the motor relative to the rest.

Ultrasonic motors provide faster, quieter focusing than the micro motors and gear systems used in earlier autofocus lenses.

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