| 摘要 |
Detecting fire according to scattered light principle includes emitting pulsed radiation of first and second wavelengths respectively along first and second radiation axes into a measuring volume, and separately measuring radiation scattered on particles in the measuring volume under a forward scattering angle of more than 90[deg] and a backward scattering angle of less than 90[deg]. Detecting fire according to scattered light principle includes emitting pulsed radiation of first wavelength along a first radiation axis into a measuring volume, emitting pulsed radiation of second wavelength shorter than the first wavelength along a second radiation axis into the measuring volume, and measuring radiation scattered on particles located in the measuring volume under a forward scattering angle of more than 90[deg] and a backward scattering angle of less than 90[deg]. The forward and backward scattered radiation of first and second wavelengths are measured separately from each other. An independent claim is also included for a scattered-light fire detector comprising a measuring chamber which communicates with the ambient air and delimits a measuring volume, a first light emitting diode (LED) (1.1a) that emits infrared radiation into the measuring volume, a second LED (1.1b) that emits blue light into the measuring volume from a different direction than the first LED, first and second photodetectors (1.2a, 1.2b) situated opposite of each other on a common main axis with respect to each other to measure the radiation scattered by particles situated in the measuring volume. Radiation axes of the first and second LEDs enclose an acute angle of less than 90[deg] with the main axis and intersect in a point situated on the main axis and in the center of the measuring volume. |
