US 11,990,024 B2
Multi-stage firm alarm device
Ching-Kun Chen, Hsin-Chu County (TW); and Guo-Zhen Wang, Hsin-Chu County (TW)
Assigned to PIXART IMAGING INC., Hsin-Chu County (TW)
Filed by PIXART IMAGING INC., Hsin-Chu County (TW)
Filed on Aug. 1, 2022, as Appl. No. 17/878,063.
Prior Publication US 2024/0038055 A1, Feb. 1, 2024
Int. Cl. G08B 29/20 (2006.01); G08B 17/103 (2006.01); G08B 29/18 (2006.01); G08B 25/00 (2006.01)
CPC G08B 29/20 (2013.01) [G08B 17/103 (2013.01); G08B 29/185 (2013.01); G08B 25/008 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A fire alarm device, comprising:
a first light source, configured to emit light of first wavelength;
a second light source, configured to emit light of second wavelength, which is different from the light of first wavelength;
a light sensor, configured to detect the light of first wavelength and the light of second wavelength, and respectively generate a first detection signal and a second detection signal;
a first processor, configured to identify whether to generate a wakeup signal according to a standby intensity variation of the first detection signal; and
a second processor, configured to identify whether to generate a fire alarm according to a first intensity variation of the first detection signal and a second intensity variation of the second detection signal after being woken up by the wakeup signal,
wherein after the second processor is woken up by the wakeup signal, the first processor is configured to continuously record the first intensity variation of the first detection signal as a reference of identifying whether to generate the wakeup signal next time and a reference for signal calibration.