Ejector devices, methods, drivers, and circuits therefor

A drive waveform for oscillating a piezoelectric mechanism, comprising a first drive signal and a second drive signal, wherein the second drive signal is separated from the first drive signal by a relaxation period, for allowing the piezoelectric mechanism oscillation to be reduced to a defined amplitude.

A system comprising:

• a droplet ejector assembly including a piezoelectric actuator coupled to a droplet generator plate having a plurality of openings therethrough, the droplet generator plate defining a fluid-filled droplet generator plate when the openings are filled with fluid;
• a drive signal generator electrically coupled to the piezoelectric actuator, the drive signal generator being configured to generate a drive signal for driving the piezoelectric actuator, and
• a controller electrically coupled to the actuator and the drive signal generator, wherein the controller is configured to control the drive signal to drive the piezoelectric actuator at a resonance frequency of the droplet generator assembly.

A method of operating a droplet ejector assembly, the method comprising:

• applying a drive signal to a droplet ejector assembly including a piezoelectric actuator coupled to a fluid-loaded droplet generator plate;
• determining a resonance frequency of the ejector assembly based on accumulated magnitude or peak value of a feedback signal from the piezoelectric actuator, and
• controlling the drive signal to drive the piezoelectric actuator at a resonance frequency of the ejector assembly.

A droplet ejection device comprising:

• an ampoule or reservoir of fluid;
• an ejector assembly comprising a droplet generator plate and a piezoelectric actuator coupled to the droplet generator plate, wherein the droplet generator plate is in fluid communication with the reservoir, such that the droplet generator plate is loaded with the fluid, and
• a driver coupled to the piezoelectric actuator, wherein the driver is configured to generate at least first and second drive signals at different first and second drive frequencies, wherein the drive signals are coupled to the piezoelectric actuator to oscillate the ejector assembly at one or more resonance frequencies.

A method of providing a drive waveform for maximizing the physical displacement of a mechanical load coupled to a piezoelectric actuator, the method comprising:

• providing two or more input signals, and
• combining the input signals to produce a combined drive signal, wherein the two or more input signals are selected such that the combined drive signal has a frequency equal to at least one resonant frequency of the mechanical load coupled to the piezoelectric actuator.

A piezoelectric ejector device for ejecting droplets of fluid, comprising

• an ejector mechanism including a piezoelectric actuator and a droplet generator plate, and
• driver electronics for driving the actuator, the electronics including a microcontroller configured to perform auto-tuning of the ejector mechanism by identifying and setting an optimum spray frequency.