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US 4,665,311 AGranted
Smoke detecting apparatus
OwnerMartin T. Coleinventor
Life of this patent
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Abstract
A light sensing apparatus comprising a solid-state photocell responsive to low levels of light connected to an impedance matching buffer stage, a gain controlled amplifier stage and an output amplifier stage; a gain control network controlled by a temperature sensor for receiving an amplified signal from said output stage, the gain being adjustable to compensate for temperature dependance of the photocell signal.
Claims9
Smoke detecting apparatus comprising:
- light sensing, solid state photocell means for producing signals in response to light;
- impedance matching buffer stage amplifier means responsive to said signals for producing an amplified signal at an impedance level adapted for further processing;
- gain controlled amplifier stage means responsive to said amplified signal and to a gain controlling signal for producing a gain controlled signal;
- output amplifier stage means responsive to said gain controlled signal for producing an output signal;
- temperature sensor means for producing a temperature signal indicative of ambient temperature;
- gain control network means responsive to said temperature signal and to said output signal for producing said gain controlling signal;
- said gain control network means being adjustable to compensate for temperature dependence of the said signals produced by said light sensing solid state photocell means;
- and
- means to deliver said gain controlling signal to said gain controlled amplifier stage means.
6 more elements
Dependencies are inferred from the claim text.