US 8,008,840 B2 · Drive unit

Abstract

A drive unit which generates less heat may be provided. The drive unit includes a piezoelectric element (P1) having a piezoelectric layer (1), a drive power supply (14) configured to apply a driving voltage at a predetermined frequency to the piezoelectric element (P1) such that vibration including stretching vibration and bending vibration is generated in the piezoelectric element (P1), and a movable element (9) which is movable relative to the piezoelectric element (P1) according to the vibration of the piezoelectric element (P1). The difference between the resonance frequency of the bending vibration of the piezoelectric element (P1) and the anti-resonance frequency of the stretching vibration of the piezoelectric element (P1) is smaller than the difference between the resonance frequency of the bending vibration of the piezoelectric element (P1) and the resonance frequency of the stretching vibration of the piezoelectric element (P1).

Claims17

Dependent claims

A drive unit, comprising:

a vibrator having a piezoelectric body;
a drive power supply configured to apply a driving voltage at a predetermined frequency to the vibrator such that vibration including stretching vibration and bending vibration is generated in the vibrator;
a relatively movable element which is movable relative to the vibrator according to the vibration of the vibrator;
and
a driver element fixed to one of the outer surfaces of the vibrator which is crossing the direction of the bending vibration,
wherein the vibrator drives the relatively movable element in a direction of the stretching vibration, and
a difference between a resonance frequency of the bending vibration of the vibrator and an anti-resonance frequency of the stretching vibration of the vibrator is smaller than a difference between the resonance frequency of the bending vibration of the vibrator and a resonance frequency of the stretching vibration of the vibrator.

4 more elements

Dependencies are inferred from the claim text.

Drive unit

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Drive unit

Life of this patent

Abstract

Claims17