MIXED-MODE PHOTO-AMPLIFIER FOR PARTICLE COUNTER

• US 20140285801A1
• Filed: 03/15/2014
• Published: 09/25/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Particles Plus, Inc.
• Original Assignee: Particles Plus, Inc.
• Inventors: PARISEAU, David, HORBAN, Ivan
• Granted Patent: US 9,157,847 B2
• Time in Patent Office: Days
• US Class Current: 356/338
• 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 particle sensor; and

at least one photo amplifier, which is in communication with the at least one particle sensor, for producing an output that includes;

at least one high-gain output; and

at least one low-gain output; and

at least one high-gain module, wherein the high-gain module provides an output used to generate the low-gain output based on a pulse-width of the high-gain output.

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

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

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

8. The system in claim 7, wherein a size threshold, which 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 photo-amplifier comprising:

a photo detector;

a high-gain amplifier coupled to the photo detector, wherein the high-gain amplifier produces a high-gain output; and

a high-gain device coupled to the high-gain amplifier, wherein the high-gain device includes;

a threshold comparator;

a charge accumulator coupled to the threshold comparator; and

a low-gain amplifier that is coupled to the charge accumulator, wherein when light is detected at the photo detector, an output of a low-gain amplifier is a function of a pulse-width associated with the high-gain output of the high-gain amplifier.

10. The photo-amplifier of claim 9, wherein the charge accumulator is a capacitor.

11. The photo-amplifier of claim 10, wherein the capacitor is charged through a resistance.

12. The photo-amplifier of claim 11, wherein the resistance is a fixed resistance.

13. The photo-amplifier of claim 11, wherein the resistance is a variable resistance.

14. The photo-amplifier of claim 11, wherein the resistance is a programmable resistance.

15. The photo-amplifier of claim 10, wherein the capacitor is charged from a precision voltage.

16. A device comprising:

at least one processor; and

a memory including computer program code that, when executed by the at least one processor, directs the apparatus to;

generate a signal representing light detected at a photo detector;

produce a high-gain output from a high-gain amplifier using the signal; and

produce a low-gain output from a low-gain amplifier using, at least one of, the signal and a high-gain function of a pulse-width of the high-gain output.