Sensitivity controlled dual input fire detector
First Claim
1. A warning device for detecting the occurrence of predetermined phenomena, comprising first detector means responsive to the phenomena for generating a first signal upon the occurrence thereof;
- second detector means responsive to the phenomena for generating a second signal upon the occurrence thereof, said first and second detector means having selected discrete sensitivities to predetermined concentrations of the phenomena to generate said first and second signals;
means for changing the sensitivity of said first detector means to the phenomena from a first to a second discrete value upon generation of said second signal;
means for changing the sensitivity of said second detector means to the phenomena from a third to a fourth discrete value upon generation of said first signal; and
means for indicating the simultaneous generation of said first and second signal.
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Accused Products
Abstract
An improved fire detector has both ionization chamber and photoelectric type products of combustion sensing devices, both of which must detect combustion for an alarm to be generated. The sensing devices are each adjusted to a quiescent sensitivity, but upon combustion being detected by one of the devices the sensitivity of the other device is automatically increased. In this manner, the detector operates very reliably to generate an alarm in the very early stages of a fire irrespective of whether the combustion process generates primarily visible or generally invisible type products of combustion, yet spurious generation of false alarm is minimized.
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Citations
14 Claims
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1. A warning device for detecting the occurrence of predetermined phenomena, comprising first detector means responsive to the phenomena for generating a first signal upon the occurrence thereof;
- second detector means responsive to the phenomena for generating a second signal upon the occurrence thereof, said first and second detector means having selected discrete sensitivities to predetermined concentrations of the phenomena to generate said first and second signals;
means for changing the sensitivity of said first detector means to the phenomena from a first to a second discrete value upon generation of said second signal;
means for changing the sensitivity of said second detector means to the phenomena from a third to a fourth discrete value upon generation of said first signal; and
means for indicating the simultaneous generation of said first and second signal. - View Dependent Claims (2, 3, 4, 5, 6)
- second detector means responsive to the phenomena for generating a second signal upon the occurrence thereof, said first and second detector means having selected discrete sensitivities to predetermined concentrations of the phenomena to generate said first and second signals;
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7. A warning device for detecting the occurrence of predetermined phenomena having concentrations of at least first and second constituents, comprising first detector means responsive to the occurrence of the phenomena to generate a first signal, said first detector means being more responsive to the occurrence of predetermined concentrations of the first constituent than of the second constituent to generate said first signal;
- second detector means response to the occurrence of the phenomena to generate a second signal, said second detector means being more responsive to the occurrence of predetermined concentrations of the second constituent than of the first constituent to generate said second signal, said first and second detector means having selected discrete sensitivities to predetermined concentrations of the first and second constituents, respectively, to generate said first and second signals;
means for increasing the sensitivity of said first detector means to the first constituent from a first to a second discrete value upon generation of said second signal;
means for increasing the sensitivity of said second detector means to the second constituent from a third to a fourth discrete value upon generation of said first signal; and
means for indicating the simultaneous generation of said first and second signals. - View Dependent Claims (8)
- second detector means response to the occurrence of the phenomena to generate a second signal, said second detector means being more responsive to the occurrence of predetermined concentrations of the second constituent than of the first constituent to generate said second signal, said first and second detector means having selected discrete sensitivities to predetermined concentrations of the first and second constituents, respectively, to generate said first and second signals;
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9. A fire detector for detecting the occurrence of products of combustion, comprising first detector means including an ionization chamber sensing device for generating a first signal upon the occurrence of products of combustion;
- second detector means including a photoelectric sensing device for generating a second signal upon the occurrence of products of combustion, said first and second detector means having selected discrete sensitivities to predetermined concentrations of products of combustion to generate said first and said second signals;
means for increasing the sensitivity of said first detector means to products of combustion from a first to a second discrete value upon said second signal being generated, whereby said first detector means generates said first signal in response to lower concentrations of products of combustion than when said second signal is not being generated;
means for increasing the sensitivity of said second detector means to products of combustion from a third to a fourth discrete value upon said first signal being generated, whereby said second detector means generates said second signal in response to lower concentrations of products of combustion than when said first signal is not being generated; and
means for indicating the simultaneous generation of said first and second signals. - View Dependent Claims (10, 11)
- second detector means including a photoelectric sensing device for generating a second signal upon the occurrence of products of combustion, said first and second detector means having selected discrete sensitivities to predetermined concentrations of products of combustion to generate said first and said second signals;
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12. A fire detector for detecting the presence of products of combustion, comprising first sensor means including an ionization chamber for generating a first signal upon the occurrence of products of combustion;
- second sensor means including a photoelectric device for generating a second signal upon the occurrence of products of combustion;
first circuit means coupled with said first and second sensor means for controlling said first sensor means so that the same generates said first signal in response to at least first discrete concentrations of products of combustion in the absence of said second signal and in response to at least second and lesser discrete concentrations of products of combustion upon generation of said second signal;
second circuit means coupled with said first and second sensor means for controlling said second sensor means so that the same generates said second signal in response to at least third discrete concentrations of products of combustion in the absence of said first signal and in response to at least fourth and lesser discrete concentrations of products of combustion upon generation of said first signal; and
means for indicating the simultaneous generation of said first and second signals.
- second sensor means including a photoelectric device for generating a second signal upon the occurrence of products of combustion;
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13. A method of detecting the occurrence of predetermined phenomena, comprising the steps of sensing the phenomena with a first detector and generating a first signal upon the occurrence thereof, sensing the phenomena with a second detector and generating a second signal upon the occurrence thereof;
- changing the sensitivity of the first detector from a first to a second discrete value upon generation of the second signal;
changing the sensitivity of the second detector from a third to a fourth discrete value upon generation of the first signal; and
indicating the simultaneous generation of the first and second signals.
- changing the sensitivity of the first detector from a first to a second discrete value upon generation of the second signal;
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14. A method of detecting the occurrence of predetermined phenomena having concentrations of at least first and second constituents, comprising the steps of sensing the phenomena with a first detector and generating a first signal upon occurrence thereof, wherein the first detector is more responsive to predetermined concentrations of the first constituent than of the second constituent to generate the first signal;
- sensing the phenomena with a second detector and generating a second signal upon occurrence thereof, wherein the second detector is more responsive to predetermined concentrations of the second constituent than of the first constituent to generate the second signal;
increasing the sensitivity of the first detector to the first constituent from a first to a second discrete value upon generation of the second signal;
increasing the sensitivity of the second detector to the second constituent from a third to a fourth discrete value upon generation of the second signal; and
indicating the simultaneous occurrence of the first and second signals.
- sensing the phenomena with a second detector and generating a second signal upon occurrence thereof, wherein the second detector is more responsive to predetermined concentrations of the second constituent than of the first constituent to generate the second signal;
Specification