Drive Circuits and Methods for Ultrasonic Piezoelectric Actuators
First Claim
Patent Images
1. A drive circuit for a piezoelectric actuator, comprising:
- an impedance coupled to the piezoelectric actuator, wherein the impedance and the piezoelectric actuator together form a tank circuit that has a resonant frequency;
a first circuit that drives the actuator at the resonant frequency, the first circuit including a current detector coupled to the tank circuit and that develops a current signal representing current flow in the circuit and a feedback capacitor coupled to the resistance for phase shifting the current signal; and
a second circuit responsive to the phase shifted current signal and a gating signal that selectively operates the first circuit in one of at least two modes of operation including a first mode that causes the actuator to be energized at a first duty cycle and a second mode that causes the actuator to be energized at a second duty cycle greater than the first duty cycle.
3 Assignments
0 Petitions
Accused Products
Abstract
A drive circuit for and method of driving a piezoelectric actuator utilizes an impedance coupled to the piezoelectric actuator, wherein the impedance and the piezoelectric actuator together form a tank circuit that has a resonant frequency. A first circuit is provided that drives the actuator at the resonant frequency and a second circuit is further provided that selectively operates the first circuit in one of at least two modes of operation including a first mode that causes the actuator to be energized at a first duty cycle and a second mode that causes the actuator to be energized at a second duty cycle.
-
Citations
45 Claims
-
1. A drive circuit for a piezoelectric actuator, comprising:
-
an impedance coupled to the piezoelectric actuator, wherein the impedance and the piezoelectric actuator together form a tank circuit that has a resonant frequency;
a first circuit that drives the actuator at the resonant frequency, the first circuit including a current detector coupled to the tank circuit and that develops a current signal representing current flow in the circuit and a feedback capacitor coupled to the resistance for phase shifting the current signal; and
a second circuit responsive to the phase shifted current signal and a gating signal that selectively operates the first circuit in one of at least two modes of operation including a first mode that causes the actuator to be energized at a first duty cycle and a second mode that causes the actuator to be energized at a second duty cycle greater than the first duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A drive circuit for a piezoelectric actuator that dispenses a volatile, comprising:
-
an impedance coupled to the piezoelectric actuator, wherein the impedance and the piezoelectric actuator together form a tank circuit that has a resonant frequency;
a first circuit that drives the actuator at the resonant frequency, the first circuit including a current detector coupled to the tank circuit and that develops a current signal representing current flow in the tank circuit and a feedback capacitor coupled to the resistance for phase shifting the current signal; and
a second circuit responsive to the phase shifted current signal and a gating signal that selectively operates the first circuit in one of at least two modes of operation including a first mode that causes the actuator to dispense volatile at a first rate and a second mode that causes the actuator to dispense volatile at a second rate greater than the first rate, wherein the first mode comprises automatically periodically energizing the actuator upon start-up of the drive circuit, and wherein the second mode temporarily overrides the first mode when the second mode is selected. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
-
29. A method of driving a piezoelectric actuator, the method comprising the steps of:
-
coupling an impedance to the piezoelectric actuator, wherein the impedance and the piezoelectric actuator together form a tank circuit that has a resonant frequency;
providing a first circuit that drives the actuator at the resonant frequency, the first circuit including a current detector coupled to the tank circuit and that develops a current signal representing current flow in the tank circuit and a feedback capacitor coupled to the resistance for phase shifting the current signal; and
providing a second circuit responsive to the phase shifted current signal and a gating signal that selectively operates the first circuit in one of at least two modes of operation including a first mode that causes the actuator to be energized at a first duty cycle and a second mode that causes the actuator to be energized at a second duty cycle greater than the first duty cycle. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
-
Specification