High frequency droplet ejection device and method
In general, in one aspect, the invention features a method for driving a droplet ejection device having an actuator, including applying a multipulse waveform that includes two or more drive pulses to the actuator to cause the droplet ejection device to eject a single droplet of a fluid, wherein a frequency of the drive pulses is greater than a natural frequency, fj, of the droplet ejection device.
1. A method for driving a droplet ejection device having an actuator, comprising:
applying a multipulse waveform comprising two or more drive pulses to the actuator to cause the droplet ejection device to eject a single droplet of a fluid, wherein each of the two or more drive pulses has an amplitude, the amplitude of a final pulse of the two or more drive pulses being greater than the amplitude of an earlier pulse of the two or more drive pulses,
wherein a frequency of the drive pulses is greater than a natural frequency, f j , of the droplet ejection device.
2. The method of claim 1 , wherein the multipulse waveform has three drive pulses.
3. The method of claim 1 , wherein the multipulse waveform has four drive pulses.
4. The method of claim 3 , wherein the amplitude of each drive pulse of the four drive pulses has a relative value with the fourth drive pulse having the greatest amplitude and relative value of 1.0, the first drive pulse having a value between 0.25 and 1.0, the second drive pulse having a value between 0.5 and 1.0, and the third drive pulse having a value between 0.5 and 1.0.
5. The method of claim 1 , wherein the frequency of the drive pulses is greater than about 1.3 f j .
6. The method of claim 5 , wherein the frequency of the drive pulses is greater than about 1.5 f j .
7. The method of claim 1 , wherein the two or more drive pulses comprise one or more bipolar pulses.
8. The method of claim 1 , wherein the two or more drive pulses comprise one or more unipolar pulses.
9. The method of claim 1 , wherein the droplet ejection device comprises a pumping chamber and the actuator comprises a piezoelectric material and is configured to vary the pressure of the fluid in the pumping chamber in response to the drive pulses.
10. A method for driving a droplet ejection device having an actuator, comprising:
applying a multipulse waveform comprising two or more fire pulses to the actuator to cause the droplet ejection device to eject a single droplet of a fluid,
wherein each fire pulse of the two or more fire pulses causes the fluid to protrude from a nozzle of the droplet ejection device, and a frequency of the fire pulses is greater than a natural frequency, f j , of the droplet ejection device.
11. The method of claim 10 , wherein the multipulse waveform has four fire pulses.
12. The method of claim 10 , wherein the frequency of the fire pulses is greater than about 1.3 f j .
13. The method of claim 10 , wherein the individual pulses of the two or more fire pulses have different pulse periods.
14. The method of claim 10 , wherein the two or more fire pulses comprise one or more bipolar pulses.
15. The method of claim 10 , wherein the two or more fire pulses comprise one or more unipolar pulses.
16. The method of claim 10 , wherein the droplet ejection device comprises a pumping chamber and the actuator comprises a piezoelectric material configured to vary a pressure of the fluid in the pumping chamber in response to the fire pulses.
17. A method for driving a droplet ejection device having an actuator, comprising:
applying a multipulse waveform comprising two or more drive pulses to the actuator to cause the droplet ejection device to eject a single droplet of a fluid,
wherein each pulse has a pulse width, the pulse width of the final pulse being greater than the pulse width of an earlier pulse of the two or more drive pulses, and a frequency of the drive pulses is greater than a natural frequency, f j , of the droplet ejection device.
18. The method of claim 17 , wherein the multipulse waveform has four drive pulses.
19. The method of claim 18 , wherein the four drive pulses have a total pulse width, and each pulse width represents a decimal fraction of the total pulse width, the pulse width of a first drive pulse is 0.15 to 0.25, the pulse width of a second drive pulse is 0.2 to 0.3, the pulse width of a third drive pulse is 0.2 to 0.3, and the pulse width of a fourth pulse is 0.2 to 0.3 of the total pulse width.
20. The method of claim 17 , wherein the frequency of the drive pulses is greater than about 1.3 f j .
21. The method of claim 20 , wherein the frequency of the drive pulses is greater than about 1.5 f j .
22. The method of claim 17 , wherein the individual pulses of the two or more drive pulses have different pulse periods.
23. The method of claim 17 , wherein the two or more drive pulses comprise one or more bipolar pulses.
24. The method of claim 17 , wherein the two or more drive pulses comprise one or more unipolar pulses.