Smoke detection alarm system
First Claim
1. A smoke detector comprising a detector circuit including a first chamber having first and second electrodes, and a radioactive element in spaced relationship to said electrodes, said radioactive element ionizing the gas in said chamber, said first chamber being permeable both to particles to be detected and other variations in the ambient atmospheric conditions surrounding said first chamber;
- a second chamber having first and second electrodes, and a radioactive element in spaced relationship to said electrodes, said radioactive element ionizing the gas in said chamber, said second chamber being substantially impermeable to said particles to be detected but being permeable to said other variations in the ambient atmospheric conditions thereabout, said chambers being connected in series with an electrode of said first chamber being connected to an electrode of said second chamber;
means for conducting an electric current through said chambers; and
means for detecting when the resistance of said first chamber varies with respect to the resistance of said second chamber by at least a threshold amount and for providing a detector signal when smoke having a predetermined particle density is detected by said first chamber;
means for generating a signal having constant duration and periodicity;
means responsive to said detector signal for varying the duration and periodicity of said generated signal; and
means arranged to receive said generated signal from said generating means and to produce an alarm signal if the time between successive ones of said generated signals is outside a predetermined range.
4 Assignments
0 Petitions
Accused Products
Abstract
An emergency alarm system for detecting smoke in remote areas and for transmitting an indication of detected smoke, either via communications channels already within a facility being protected or by way of telemetry to an alarm indicating device. A fault detector is also provided for indicating when any component of the system becomes defective or otherwise nonfunctional. More specifically, a plurality of smoke detectors of the ion chamber type are positioned at strategic points within a facility to be protected. When any one of the smoke detectors is appropriately activated by smoke, an output in the form of a time duration modulated ultrasonic signal is generated, which is coupled via telemetry or communications channels within the facility being protected to a responder unit which is provided at a central location. If the generated signal persists longer than a predetermined time, an alarm indicator is energized to indicate that smoke is present at one of the smoke detectors. If a fault occurs, such as when one of the smoke detectors becomes disconnected, no ultrasonic signal will be generated and transmitted over the communications channels and, accordingly, a slave timer in the responder unit will not be appropriately deactivated, thereby causing a signal which energizes a fault indicator.
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Citations
8 Claims
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1. A smoke detector comprising a detector circuit including a first chamber having first and second electrodes, and a radioactive element in spaced relationship to said electrodes, said radioactive element ionizing the gas in said chamber, said first chamber being permeable both to particles to be detected and other variations in the ambient atmospheric conditions surrounding said first chamber;
- a second chamber having first and second electrodes, and a radioactive element in spaced relationship to said electrodes, said radioactive element ionizing the gas in said chamber, said second chamber being substantially impermeable to said particles to be detected but being permeable to said other variations in the ambient atmospheric conditions thereabout, said chambers being connected in series with an electrode of said first chamber being connected to an electrode of said second chamber;
means for conducting an electric current through said chambers; and
means for detecting when the resistance of said first chamber varies with respect to the resistance of said second chamber by at least a threshold amount and for providing a detector signal when smoke having a predetermined particle density is detected by said first chamber;
means for generating a signal having constant duration and periodicity;
means responsive to said detector signal for varying the duration and periodicity of said generated signal; and
means arranged to receive said generated signal from said generating means and to produce an alarm signal if the time between successive ones of said generated signals is outside a predetermined range. - View Dependent Claims (2, 3, 4, 5, 7, 8)
- a second chamber having first and second electrodes, and a radioactive element in spaced relationship to said electrodes, said radioactive element ionizing the gas in said chamber, said second chamber being substantially impermeable to said particles to be detected but being permeable to said other variations in the ambient atmospheric conditions thereabout, said chambers being connected in series with an electrode of said first chamber being connected to an electrode of said second chamber;
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6. An emergency alarm system including detector means responsive to a condition and providing a detector signal indicative of the presence or absence of said condition, means for generating a signal having constant duration and periodicity, means responsive to said detector signal when indicating the presence of said condition to vary the duration and periodicity of said generated signal, and means arranged to receive said generated signal from said generating means and to produce an alarm signal if the time between successive ones of said generated signals is outside a predetermined range.
Specification