Patent ID: 9207209
Filing Date: 2015-12-08
Classification: G01N,G08B,H03M

Abstract:
1. A method for detecting smoke, comprising the steps of: determining a voltage on a conductive screen with a delta-sigma analog-to-digital converter, wherein the conductive screen is located between a first ion chamber and a second ion chamber, wherein the first ion chamber is open to smoke ingress and the second ion chamber is closed to smoke ingress; and detecting a presence of smoke by: applying a first voltage potential to the first and second ion chambers at a first polarity; determining a first voltage on the conductive screen caused by the first voltage potential at the first polarity; applying a second voltage potential to the first and second ion chambers at a second polarity; determining a second voltage on the conductive screen caused by the second voltage potential at the second polarity; determining a voltage difference between the first and the second voltages; and detecting the presence of smoke when the voltage difference changes by a certain amount.