Rapidly responding, false detection immune alarm signal producing smoke detector

A rapidly responding, false detection immune smoke detector of a light obscuration type, comprising:

• a light reflective imaging assembly including a pair of spaced-apart, opposed light reflecting surfaces between which a concentration of smoke particles can enter;
• a light source from which a light beam propagates in a direction for reflection by the light reflecting surfaces, the light beam reflecting off each one of the pair of light reflecting surfaces as it propagates through the light reflective imaging assembly, the light beam exiting the light reflective imaging assembly having an intensity corresponding to the concentration of smoke particles present between the light reflecting surfaces;
• and
• a light detector positioned to receive a light beam representing the concentration of smoke particles in the light reflective imaging assembly.

A false detection immune, light obscuration type smoke detector that is capable of detecting particles of different sizes, comprising:

• a light reflective imaging assembly including a pair of spaced-apart, opposed light reflecting surfaces between which gas-borne particles can enter;
• first and second light sources from which respective first and second light beams of different wavelengths propagate in directions for reflection by the light reflecting surfaces, the first and second light beams reflecting off each one of the pair of light reflecting surfaces as the first and second light beams propagate through the light reflective imaging assembly, the first and second light beams exiting the light reflective imaging assembly having intensities corresponding to concentrations of gas-borne particles of different ranges of sizes present between the light reflecting surfaces, the first and second ranges of sizes being determined by the wavelengths of, respectively, the first and second light beams;
• and
• a light detector positioned to receive a light beam representing at least one of the first and second ranges of sizes of the gas-borne particles in the light reflective imaging assembly.

A smoke detector of an obscuration type configured for placement of its optical components within the interior of an air duct having a duct side wall with an exterior surface, the smoke detector monitoring the quality of air flowing in an air flow direction through the interior of the air duct, comprising:

• a light reflective imaging assembly including a pair of spaced-apart, opposed light reflecting surfaces between which a concentration of smoke particles can enter and an optical axis extends;
• a support configured to extend through an opening in the duct side wall and having first and second ends, the first end holding the light reflective assembly within the interior of the air duct in a desired orientation that positions the optical axis transversely of the direction of air flow within the air duct, and the second end being mechanically coupled to the side wall to secure the support and thereby set the light reflective assembly in the desired orientation;
• a light source from which a light beam propagates in a direction for reflection by the light reflecting surfaces, the light beam reflecting off each one of the pair of light reflecting surfaces as it propagates through the light reflective imaging assembly, the light beam exiting the light reflective imaging assembly having an intensity corresponding to the concentration of smoke particles present between the light reflecting surfaces;
• and
• a light detector positioned to receive a light beam representing the concentration of smoke particles in the light reflective imaging assembly.

A rapidly responding, false detection immune smoke detector of a light obscuration type, comprising:

• a light source from which a light beam propagates;
• a light detector having a light receiving surface with a light detecting area and producing a signal in response to light incident on the light receiving surface;
• a light reflective imaging assembly in optical association with the light source and the light detector, the imaging assembly including first and second spaced-apart optical components having respective first and second opposed light reflecting surfaces forming between them a spatial region that smoke particles can occupy, the first and second optical components having light directing properties that cooperate to reflect the light beam between the first and second light reflecting surfaces and to direct the light beam toward the light detector for incidence on its light receiving surface and thereby cause the light detector to produce a signal corresponding to a concentration of the smoke particles occupying the spatial region;
• and
• circuitry operatively associated with the light detector to acquire during a data gathering time interval data from the signal corresponding to the concentration of the smoke particles occupying the spatial region, the data gathering time interval being long as compared to the time of a slow fire, and the circuit determining an adjustment value for application to the signal produced by the light detector in response to a change in the acquired data that, in the absence of smoke, is greater than a preassigned operational tolerance after the data gathering time interval.