Mixed-mode photo-amplifier for particle counter

• US 9,157,847 B2
• Filed: 03/15/2014
• Issued: 10/13/2015
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Particles Plus, Inc.
• Original Assignee: Particles Plus, Inc.
• Inventors: Pariseau, David, Horban, Ivan
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): RAHMAN, MD M
• Application Number:
  US14/214,903
• Publication Number:
  US 20140285801A1
• Time in Patent Office: 577 Days
• Field of Search: 356/338
• US Class Current: 1/1
• CPC Class Codes: G01N 15/0205 by optical means
• CPC Class Codes: G01N 15/1459 the analysis being performed on a sample stream
• CPC Class Codes: G01N 2015/0046 in gas, e.g. smoke
• CPC Class Codes: G01N 2015/1486 Counting the particles

Abstract

An airborne, gas, or liquid particle sensor with a mixed-mode photo-amplifier front-end. The photo-amplifier uses pulse-height for the high-gain channel and integrates the pulse-energy for the low-gain channel to provide for a larger dynamic range for larger size particles.

Claims

1. A particle counter system comprising:

at least one airstream chamber;

at least one light source focused into a beam that passes through the airstream chamber;

at least one photo-detector within the airstream chamber, the photo-detector detects changes in light as airborne particulates pass through the beam;

at least one high-gain amplifier in communication with the photo-detector, the high-gain amplifier converts signals from the photo-detector into amplified electrical pulses;

at least one particulate size channel, where volume of air and light intensity are used in conjunction with the amplified electrical pulses to infer particulate counts for the particulate size channel; and

at least one low-gain amplifier in communication with the high-gain amplifier which produces electrical pulses whose amplitudes are a function of a pulse-width of the high-gain amplifier.

2. The system in claim 1, wherein the output of the high-gain amplifier is a linear output based on the pulse-width of the high-gain amplifier'"'"'s output.

3. The system in claim 2, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged through a fixed resistance.

4. The system in claim 2, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged through a variable resistance.

5. The system in claim 2, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged through a programmable resistance.

6. The system in claim 2, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged from a precision voltage source.

7. The system in claim 1, wherein the output of the high-gain amplifier is based on a capacitor charged as a function of the pulse-width of the high-gain amplifier'"'"'s output.

8. The system in claim 7, wherein a size threshold, which is associated with a particle size not calibrated for, is determined using the capacitor'"'"'s characteristic charge curve and at least two other calibration points.

9. A particle counter system comprising:

at least one liquid chamber;

at least one light source focused into a beam that passes through the liquid chamber;

at least one photo-detector within the liquid chamber, the photo-detector detects changes in light as airborne particulates pass through the beam;

at least one high-gain amplifier in communication with the photo-detector, the high-gain amplifier converts signals from the photo-detector into amplified electrical pulses;

at least one particulate size channel, where volume of air and light intensity are used in conjunction with the amplified electrical pulses to infer particulate counts for the particulate size channel; and

at least one low-gain amplifier in communication with the high-gain amplifier which produces electrical pulses whose amplitudes are a function of a pulse-width of the high-gain amplifier.

10. The system in claim 9, wherein the output of the high-gain amplifier is a linear output based on the pulse-width of the high-gain amplifier'"'"'s output.

11. The system in claim 10, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged through a fixed resistance.

12. The system in claim 10, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged through a variable resistance.

13. The system in claim 10, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged through a programmable resistance.

14. The system in claim 10, further comprising a capacitor that is electrically connected to the high-gain amplifier'"'"'s output, wherein the capacitor is charged from a precision voltage source.

15. The system in claim 9, wherein the output of the high-gain amplifier is based on a capacitor charged as a function of the pulse-width of the high-gain amplifier'"'"'s output.

16. The system in claim 15, wherein a size threshold, which is associated with a particle size not calibrated for, is determined using the capacitor'"'"'s characteristic charge curve and at least two other calibration points.