Method for automatically setting the correct phase of the charge pulses in an electrostatic flow sorter
First Claim
1. An electrostatic particle sorting system, comprising:
- (a) flow means for establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong;
(b) optical detection means for optically detecting said particles at least at said particle sensing point;
(c) perturbation means for perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a break point at which said stream becomes a series of discrete droplets;
(d) droplet charging means for relatively charging selected ones of said droplets as they are formed at said break point;
(e) synchronization means for performing said relative charging at a preselected time with respect to the phase of formation of said discrete droplets at said break point, said synchronization means comprising;
(i) sheath sensing means for sensing at least the light scatter of said stream at a sheath sensing point therealong subsequent to said perturbation, and for producing a surface character output signal which is proportional thereto; and
(ii) surface character analysis means for analyzing at least the phase of said surface character output signal;
and wherein said droplet charging means comprises charge pulse generation means for providing a charge pulse in a preselected phased relationship to said phase of said surface character output signal.
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Abstract
In order to initiate the charging of droplets at a specific point in time with respect to the formation of those droplets in an electrostatic flow sorting system, the charge phase of the system of the present invention is continuously and automatically adjusted by droplet break point monitoring. The charge phase is therefore flow rate and fluid velocity independent. The break point is monitored by a light source which is focused onto the jet stream at the droplet formation break point, or close to it, and the modulation of light caused by the scatter induced by the sheath stream portion as it passes the focused beam of light is detected via the use of a suitable electro-optical detector. From the output of the electro-optical detector, after appropriate signal conditioning, an electrical wave form is obtained which shape depends upon the shape of the fluid column passing the focus beam. Using this conditioned detector output, the charge pulse phase is automatically controlled to occur at a set point in time with respect to a transition point on the waveform thus obtained. Additionally, in order to compensate for large flow rate variations, the focused beam detector can be automatically repositioned to track with the breakpoint. The correct phase of the charge pulse will accordingly continue to be derived from the breakpoint electrical waveform. Alternatively, by monitoring the jet stream at points above or below the breakpoint, the phase adjustment is possible, however, somewhat fluid velocity dependent.
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Citations
16 Claims
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1. An electrostatic particle sorting system, comprising:
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(a) flow means for establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) optical detection means for optically detecting said particles at least at said particle sensing point; (c) perturbation means for perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a break point at which said stream becomes a series of discrete droplets; (d) droplet charging means for relatively charging selected ones of said droplets as they are formed at said break point; (e) synchronization means for performing said relative charging at a preselected time with respect to the phase of formation of said discrete droplets at said break point, said synchronization means comprising; (i) sheath sensing means for sensing at least the light scatter of said stream at a sheath sensing point therealong subsequent to said perturbation, and for producing a surface character output signal which is proportional thereto; and (ii) surface character analysis means for analyzing at least the phase of said surface character output signal; and wherein said droplet charging means comprises charge pulse generation means for providing a charge pulse in a preselected phased relationship to said phase of said surface character output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electrostatic particle sorting method comprising the steps of:
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(a) establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) optically detecting said particles at least at said particle sensing point; (c) perturbing said stream at a preselected perturbation point with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream becomes a series of discrete droplets; (d) relatively charging said selected ones of said droplets as they are formed at said breakpoint; and (e) synchronizing said relative charging at a preselected time with respect to the phase of formation of said discrete droplets at said breakpoint, said synchronization step comprising the steps of; (i) sensing at least the light scatter characteristics of said stream at a sheath sensing point defined therealong subsequent to said perturbation point, and generating a surface character output signal which is proportional thereto; and (ii) analyzing said surface character output signal at least to determine the phase of said surface character output signal; and (f) generating a charge pulse in a preselected phased relationship with respect to the phase of the surface character output signal detected in step (e)(ii) above. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An electrostatic particle sorting system, comprising:
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(a) flow means for establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) detection means for detecting said particles at least at said particle sensing point; (c) perturbation means for perturbing said stream with at least a preselected frequency and amplitude to cause said stream to form a break point at which said stream becomes a series of discrete droplets; (d) droplet charging means for relatively charging selected ones of said droplets as they are formed at said break point; (e) synchronization means for performing said relative charging at a preselected time with respect to the phase of formation of said discrete droplets at said break point, said synchronization means comprising; (i) sheath sensing means for sensing at least the light scatter of said stream at a sheath sensing point therealong subsequent to said perturbation, and for producing a surface character output signal which is proportional thereto; and (ii) surface character analysis means for analyzing at least the phase of said surface character output signal; and wherein said droplet charging means comprises charge pulse generation means for providing a charge pulse in a preselected phased relationship to said phase of said surface character output signal.
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16. An electrostatic particle sorting method comprising the steps of:
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(a) establishing the flow of a continuous particle containing stream comprising at least a particle containing core stream portion and a surrounding sheath stream portion, said stream having a particle sensing point defined therealong; (b) detecting said particles at least at said particle sensing point; (c) perturbing said stream at a preselected perturbation point with at least a preselected frequency and amplitude to cause said stream to form a breakpoint at which said stream becomes a series of discrete droplets; (d) relatively charging said selected ones of said droplets as they are formed at said breakpoint; and (e) synchronizing said relative charging at a preselected time with respect to the phase of formation of said discrete droplets at said breakpoint, said synchronization step comprising the steps of; (i) sensing at least the light scatter characteristics of said stream at a sheath sensing point defined therealong subsequent to said perturbation point, and generating a surface character output signal which is proportional thereto; and (ii) analyzing said surface character output signal at least to determine the phase of said surface character output signal; and (f) generating a charge pulse in a preselected phased relationship with respect to the phase of the surface character output signal detected in step (e)(ii) above.
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Specification