Method of correcting a resonance frequency of a small rotary actuator
AssigneeSeiko Instruments Inc.
InventorsMizuaki Suzuki, Kazuo Tani
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Abstract
In a small rotary actuator having a rotor and a plurality of oscillators, each having a piezoelectric element that is excited by application of energy thereto so that the piezoelectric element oscillates at a resonance frequency thereof, the resonance frequency of the respective oscillators varies to some degree. This variation reduces the efficiency of rotation of the rotor. In order to reduce this variation, one or more of the piezoelectric elements of the oscillators is etched so that its resonance frequency is increased to match the resonance frequency of the other oscillators.
Claims22
A method of correcting the resonance frequency of a small rotary actuator having a rotor and a plurality of oscillators each having a piezoelectric element and being excited by applying energy to the piezoelectric element to cause oscillation of the respective oscillators at a resonance frequency thereof, in which a torque is supplied to the rotor by virtue of the oscillators impacting the rotor due to vibration of the oscillators, comprising the step of:
- cutting the piezoelectric element for driving one or more of the oscillators in order to reduce a variation in resonance frequency of the respective oscillators to improve the efficiency of rotation of the rotary actuator.
A method of reducing a variation in resonance frequency in a rotary actuator having a rotor and three or more piezoelectric oscillators, comprises the steps of:
- providing the three or more oscillators in rotary symmetry with respect to the rotor, each of the oscillators having a piezoelectric element oscillated by the application of energy at a resonance frequency thereof so as to apply a torque to the rotor by impacting the rotor, and each oscillator having a resonance frequency which varies in accordance with its size;
- selecting a reference frequency as the resonance frequency of one of the respective oscillators;
- changing the size of at least one of the other oscillators to reduce a variation in resonance frequency of the respective oscillators so that each of the oscillators has the desired resonance frequency to improve the efficiency of movement of the actuator.
Dependencies are inferred from the claim text.