Abstract

The detector has first and second circuits which are interconnected. The first circuit senses the emission of a flame at least in the wavelength range of carbon dioxide and produces square-wave signals corresponding to the flicker frequency. The second circuit senses short wavelength emission with a wavelength shorter than 3 μm and produces square-wave signals corresponding to the flicker frequency of the emission. The interconnecting means permits the alarm means to be activated only when the first circuit signals and the second circuit signals are present simultaneously and with the same direction, to indicate that the flicker frequency is the same for both emissions. An integrator prevents spurious coinciding signals from resulting in an alarm and a reset circuit periodically resets the integrator. Various specific photoelectric means are described.

Other References

• Report of Fire Research Institute of Japan, No. 30, Dec., 1969