Piezoelectric devices and methods and circuits for driving same
First Claim
1. A drive circuit which produces a drive signal for a device having a piezoelectric actuator, the piezoelectric actuator forming a part of the drive circuit and serving to shape a waveform of the drive signal, the drive circuit comprising:
- a pulse generator configured to generate digital pulses;
a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets having a frequency greater than an ability of the piezoelectric actuator to mechanically respond; and
wherein the piezoelectric actuator, by a capacitive nature of the piezoelectric actuator, integrates the charge packets to shape the waveform of the drive signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A drive circuit (18) produces a drive signal for a pump (10) having a piezoelectric actuator (14), with the piezoelectric actuator (14) forming a part of the drive circuit (18) and serving to shape a waveform of the drive signal. The drive circuit (18) comprises a pulse generator (100) which generates pulses; a converter circuit (102) which receives the pulses and produces charge packets at a rate which equals a desired drive frequency; and, the piezoelectric actuator (14). The piezoelectric actuator (14) receives the charge packets and, by its capacitive nature, integrates the charge packets to shape the waveform of the drive signal. Preferably, the piezoelectric actuator (14) integrates the charge packets to yield a drive field that approximates a sine wave. In one non-limiting example embodiment, the pulse generator (100) comprises a microcontroller-based pulsed width modulator (PWM) circuit (116) and the converter circuit (102) comprises a flyback circuit.
-
Citations
33 Claims
-
1. A drive circuit which produces a drive signal for a device having a piezoelectric actuator, the piezoelectric actuator forming a part of the drive circuit and serving to shape a waveform of the drive signal, the drive circuit comprising:
-
a pulse generator configured to generate digital pulses; a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets having a frequency greater than an ability of the piezoelectric actuator to mechanically respond; and wherein the piezoelectric actuator, by a capacitive nature of the piezoelectric actuator, integrates the charge packets to shape the waveform of the drive signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A piezoelectrically-operated apparatus comprising:
-
a piezoelectric actuator which is responsive to a drive signal; and a drive circuit which applies the drive signal to the piezoelectric actuator as a series of digital pulses, wherein the drive circuit further comprises; a pulse generator configured to generate digital pulses; a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets having a frequency greater than an ability of the piezoelectric actuator to mechanically respond; and wherein the piezoelectric actuator, by a capacitive nature of the piezoelectric actuator, integrates the charge packets to shape a waveform of the drive signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A drive circuit which produces a drive signal for a piezoelectric actuator, the drive circuit comprising:
-
a generator configured to generate a pulse train and a polarity drive signal, the polarity drive signal having either a first polarity value or a second polarity value; a transformer comprising a transformer core;
a transformer primary; and
a transformer secondary;power switching element configured to receive the pulse train and to selectively apply current to the transformer primary for storing magnetic flux in the transformer core during a pulse of the pulse train and to generate a flyback positive charge on the transformer primary and the transformer secondary at the end of a pulse; a switching network connected between the generator and the transformer secondary and configured, at the end of the pulse; when the polarity drive signal has the first polarity value, to allow current to flow from the transformer secondary to the piezoelectric actuator in a positive direction step in potential; when the polarity drive signal has the second polarity value, to store at least some of the flyback positive charge in parasitic capacitance of the transformer so that the transformer produces a bounce charge of opposite polarity that permits current to flow out of the piezoelectric actuator and thereby induce a negative direction step in potential on the piezoelectric actuator. - View Dependent Claims (23, 24, 25, 26, 27, 28)
-
-
29. A drive circuit which produces a drive signal for a piezoelectric actuator, the drive circuit comprising:
-
a generator configured to generate a pulse train; a transformer comprising a transformer core;
a transformer primary; and
a transformer secondary;power switching element configured to receive the pulse train and to selectively apply current to the transformer primary for storing magnetic flux in the transformer core during a pulse of the pulse train and to generate a flyback positive charge on the transformer primary and the transformer secondary at the end of the pulse; a switching network connected between the generator and the transformer secondary and configured, at the end of the pulse, when the polarity drive signal has the second polarity value, to store at least some of the flyback positive charge in parasitic capacitance of the transformer so that the transformer produces a bounce charge of opposite polarity that permits current to flow out of the piezoelectric actuator and thereby induce a negative direction step in potential on the piezoelectric actuator. - View Dependent Claims (30, 31, 32, 33)
-
Specification