High sensitivity smoke detecting apparatus using a plurality of sample gases for calibration

Abstract

A smoke detecting apparatus for a fire alarm has: a smoke chamber into which smoke to be detected is introduced, a light emitting lamp disposed in the smoke chamber, a light receiving element disposed in the smoke chamber so as to receive the light emitted from the light emitting lamp, an A/D converting circuit for converting the output signal from the light receiving element into a digital signal, a memory for storing data therein, a computing device for storing in said memory, as first calibration data, the output data from the A/D converting circuit when the smoke chamber is filled with a first reference gas, storing in said memory, as second calibration data, the-output data from the A/D converting circuit when the smoke chamber is filled with a second reference gas, and computing a proper smoke density corresponding to the output data from the A/D converting circuit on the basis of the first and second calibration data and the output data from the A/D converter circuit, and a display device for displaying the smoke density computed by the computing device.

Dependencies are inferred from the claim text.