US 11,676,466 B2
Self-calibrating fire sensing device
Christopher Dearden, Melton Mowbray (GB); Michael Barson, Nuneaton (GB); and Benjamin Wolf, Leicester (GB)
Assigned to Honeywell International Inc., Charlotte, NC (US)
Filed by Honeywell International Inc., Morris Plains, NJ (US)
Filed on Aug. 19, 2020, as Appl. No. 16/997,743.
Prior Publication US 2022/0058929 A1, Feb. 24, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. G08B 17/107 (2006.01); G01N 15/06 (2006.01); G08B 29/28 (2006.01); G01N 15/00 (2006.01)
CPC G08B 17/107 (2013.01) [G01N 15/06 (2013.01); G08B 29/28 (2013.01); G01N 2015/0046 (2013.01); G01N 2015/0693 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A self-calibrating fire sensing device, comprising:
an adjustable particle generator and a variable airflow generator configured to generate aerosol having a particular particle size and optical scatter properties at a controllable density level;
a first transmitter light-emitting diode (LED) configured to emit a first light that passes through the aerosol;
a second transmitter LED configured to emit a second light that passes through the aerosol;
a photodiode configured to:
detect a scatter level of the first light that passes through the aerosol; and
detect a scatter level of the second light that passes through the aerosol; and
a controller configured to calibrate a gain of the photodiode based on the detected scatter level of the first light, the detected scatter level of the second light, and the controllable aerosol density level.