Lightweight, compact detector of sudden changes in concentration of a gas
First Claim
1. Apparatus for signalling a sudden increase in the concentration of a selected gas comprising:
- sensor means for producing a change in an electrical sensing signal in response to the detection of a change in the concentration of a selected gas;
first and second amplifying means of unequal overall gain, each amplifying means receiving said sensing signal and having substantially different time constants, for generating first and second output signals, respectively, in response to said sensing signal;
means for comparing the magnitude of said first output signal to the magnitude of said second output signal and for generating an alarm signal when the relative magnitudes of said first and second output signals are inverted; and
means receiving said alarm signal for producing a warning in response to the generation of an alarm signal.
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Accused Products
Abstract
Lightweight, compact apparatus for detecting sudden changes in the concentration of at least one selected gas provides a warning when said gas concentration increases suddenly. In one embodiment, a chemically sensitive field effect transistor provides a sensing signal two amplifiers having different overall gains and widely different time constants. Detection of sudden gas concentration changes causes the relative magnitudes of the amplifier output signals to be inverted triggering a warning. The apparatus may occupy less than 1.25 cubic inches and weigh less than 4 ounces so that it may be worn by an individual throughout his work place.
32 Citations
16 Claims
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1. Apparatus for signalling a sudden increase in the concentration of a selected gas comprising:
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sensor means for producing a change in an electrical sensing signal in response to the detection of a change in the concentration of a selected gas; first and second amplifying means of unequal overall gain, each amplifying means receiving said sensing signal and having substantially different time constants, for generating first and second output signals, respectively, in response to said sensing signal; means for comparing the magnitude of said first output signal to the magnitude of said second output signal and for generating an alarm signal when the relative magnitudes of said first and second output signals are inverted; and means receiving said alarm signal for producing a warning in response to the generation of an alarm signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A portable electrical apparatus for signalling a sudden increase in the concentration of a selected gas comprising:
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a chemically sensitive field effect transistor for producing a change in an electrical sensing signal in response to the detection of a change in the concentration of a selected gas; first and second amplifiers having unequal overall gains ans substantially different time constants, each amplifier receiving said sensing signal, for generating first and second output signals, respectively, in response to said sensing signal; means for comparing the magnitude of said first output signal to the magnitude of said second output signal and for generating an alarm signal when the relative magnitudes of said first and second output signals are inverted; an alarm receiving said alarm signal for producing a warning in response to the generation of an alarm signal; and a battery for supplying electrical power to said apparatus. - View Dependent Claims (15, 16)
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Specification