Smoke detector
AssigneeCega, Inc.
InventorChristian C. Petersen
Life of this patent
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Abstract
Smoke detector apparatus characterized in the utilization of solid state components in conjunction with standard primary batteries as a power source. Operating under photo-optical principles, the apparatus incorporates a solid state detector which, while having a low current drain characteristic, exhibits dark current phenomena. A stabilization network is provided to accommodate for this phenomena which includes an amplifier having a transistor stage and means for clamping that stage in a partially forwardly biased state. Detection of smoke causes the amplifier to generate a signal output as a step function.
Claims18
Surveillance apparatus for detecting the presence of aerosols within an environment comprising:
- light emitting means energizable to provide a region of radiation:
- oscillator means for energizing said light emitting means during surveillance intervals of short duration, said surveillance interval energization being effected at a sampling frequency having a period substantially greater than a said surveillance interval;
- detector means, characterized by the presence of temperature dependent dark current phenomena and exhibiting a first signal condition in response thereto, said detector means further being characterized in having a high rate of response to the presence of aerosol within said region of radiation and exhibiting a second signal condition in correspondence therewith;
- stabilization network means responsive to discriminate said first signal condition, as steady state in nature, from said second signal condition, and including amplifier means coupled with said detector means and comprising a transistor stage and bias clamping means for retaining said transistor stage in a partially forwardly biased condition in the presence of said first signal condition, said amplifier means being responsive to said second signal condition to generate a detect signal output as a step function;
- and
- means responsive to said detect signal output for generating an alarm signal.
Surveillance apparatus for detecting the presence of smoke within an environment comprising:
- emitting means energizable to provide a region of radiation;
- oscillator means for energizing said source from a battery power supply during intervals of surveillance, said surveillance interval energization being carried out at a predetermined sampling frequency;
- detector means, characterized in having a high rate of response to the presence of smoke within said region of radiation and exhibiting a predetermined signal condition in correspondence therewith;
- means responsive to said predetermined signal condition to generate a transient voltage output signal;
- gate means operatively coupled with said power supply having an input coupled for response to said output signal, having an input triggering value characteristic substantially linear over a predetermined normal operational range of voltage values applied from said power supply thereto, exhibiting an input triggering voltage value characteristic nonlinearly approaching said applied voltage values when said values are below said normal operational range and for generating an output signal in the presence of a triggering level voltage at its input;
- control means for applying a threshold voltage at said input having a value representing a percentage of the value of voltage of said power supply, said threshold voltage value determining the level of said voltage output signal required to effect a said triggering of said gate means to establish the sensitivity thereof, whereby the said sensitivity of said gate means is enhanced when said power supply voltage values are below said normal range;
- and
- means responsive to said gate means output signal for generating an alarm signal.
Dependencies are inferred from the claim text.