Smoke detecting apparatus
First Claim
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1. 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.
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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.
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Citations
9 Claims
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1. Smoke detecting apparatus comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification