Acoustically ejecting a droplet of fluid from a reservoir by an acoustic fluid ejection apparatus

A method for analysis of acoustic data to determine the amount of acoustic energy necessary to increase a perturbation pulse to the level of a droplet ejection pulse, the method comprising the following steps:

• (a) delivering a perturbation pulse to the unperturbed surface of a fluid in a well to determine (1) fluid height and/or (2) the magnitude of the background noise sensed by an acoustic detector;
• (b) delivering a perturbation interrogation pulse to the fluid surface;
• (c) processing the reflected acoustic energy from the perturbation interrogation pulse;
• (d) removing low frequency noise from the signal processed in step (c) and reprocessing that signal if necessary;
• (e) determining all of the minima in the frequency spectrum of the signal output in step (d);
• and
• (f) selecting the two minima of interest, based on the frequency content of the processed signal, and determining the spacing between the two minima.

A method for analysis of acoustic data to determine the amount of acoustic energy necessary to increase a pulse to an acoustic energy level sufficient for droplet ejection, the method comprising the steps of:

• (a) delivering a perturbation pulse to the unperturbed surface of a fluid in a well to determine (1) fluid height and (2) the magnitude of the background noise;
• (b) delivering a perturbation interrogation pulse to the fluid surface;
• (c) using an analyzer to compute the FFT of the reflection of the perturbation interrogation pulse from the fluid surface;
• (d) using the analyzer to look for the presence of a low frequency preamble in the reflection of the perturbation interrogation pulse and, if a low frequency preamble is found, to remove it from the reflection and to compute the FFT of the reflection with the low frequency preamble removed;
• (e) determining all of the minima in the FFT computed in steps (c) or (d);
• and
• (f) selecting two minima of interest, taking as in input the frequency content of the perturbation pulse, and determining the spacing between the two minima selected.

A method for the analysis of acoustic data to determine the amount of additional acoustic energy necessary to change a pulse to the level of a droplet-forming pulse for a fluid surface in a well containing a fluid, the method comprising the steps of:

• (a) using a ranging pulse to determine the fluid height in the well;
• (b) sending a perturbation pulse to a fluid site near the fluid surface to perturb the fluid surface;
• (c) sending at least one further pulse to the fluid site to be reflected from the perturbed fluid surface;
• (d) using the reflected acoustic energy from the at least one further pulse of step (c) to determine a waveform for analysis;
• and
• (e) using an analyzer to process the waveform to estimate the gap between the power in the perturbation pulse and the power required for a droplet-forming pulse.