Detection of products of combustion

Abstract

A self-contained, self-powered, early warning fire detector and alarm of small size and attractive appearance especially adapted for use in residences; the detector including readily accessible sensitivity control and operability test means, and having a standby power source which additionally serves to monitor the primary power source and inform occupants of malfunction of the primary power source.

We claim: 
     
       1. In a warning device having a primary power source, an alarm unit connected to said source and a load unit connected to said source; a supervisory circuit comprising a secondary power source, a capacitor in series with said secondary source, means coupling said capacitor to one side and said secondary source to the other side of said load unit to sense the voltage drop thereacross, trigger means responsive upon charging of said capacitor for connecting said alarm unit with said secondary source, said capacitor being charged by said second source when the voltage drop across said load unit falls below a predetermined value and when charged triggering said trigger means, said trigger means during discharge of said capacitor causing said secondary source to energize said alarm unit .[.whereby the alarm unit,.]. whereby the alarm unit emits periodic alarms of short duration when the output of the primary source falls below a predetermined value. 
     
     
       2. In a device as set forth in claim 1, said primary source comprising a battery and said secondary source comprising a standby battery for the primary source battery. 
     
     
       3. In a warning device having a power source, means for detecting a predetermined condition and thereupon emitting a signal, an amplifier having a power input connected to said source and a signal input connected to said detecting means for amplifying the signal, a trigger device connected to the amplifier to be triggered upon reception of the predetermined amplified signal, and an alarm unit connected to said trigger device to be energized when the latter is triggered, the improvement comprising, in combination with rate of change detecting means, a plurality of capacitor banks adapted to be connected selectively to the amplifier power input, and switch means for selectively adding said capacitor banks to the amplifier power input to vary the time constants and thus the detecting sensitivity of the device. 
     
     
       4. In a device as set forth in claim 3, said switch means comprising a plural position switch including a plurality of positions for selectively adding capacitor banks to the amplifier input and a further position for bypassing said trigger device and directly connecting said alarm unit to the power source, said switch means in its said further position in the absence of an alarm serving to test the operability of the alarm, and following an alarm serving to trip said trigger device and thereby reset the same. 
     
     
       5. In a device as set forth in claim 4, wherein the device includes a load unit connected to the primary source; a supervisory circuit comprising a secondary power source, a capacitor in series with said secondary source, means coupling said capacitor to one side and said secondary source to the other side of said load unit to sense the voltage drop thereacross, second trigger means responsive upon charging of said capacitor for connecting said alarm unit in series with said secondary source, said capacitor being charged by said secondary source when the voltage drop across said load unit falls below a predetermined value and when charged triggering said second trigger means, said second trigger means during discharge of said capacitor causing said secondary source to energize said alarm unit, whereby the alarm unit emits periodic alarms of short duration when the output of the primary source falls below a predetermined value. .Iadd. 6. A warning device comprising a power source, said power source comprising a battery, means energized by said power source for providing first and second audible warnings, said first audible warning being sensually discernably different than said second audible warning, said providing means having an operative state in which either said first warning or said second warning is provided and an inactive state in which neither said first warning nor said second warning is provided,   means for detecting the presence of combustion,   first means responsive to said detecting means upon the detection of the presence of combustion for placing said providing means in its operative state and for causing said providing means to provide said first warning,   means for establishing a first voltage representative of the output voltage of said battery,   means for monitoring said first voltage, said monitoring means including means for establishing a reference voltage and means for comparing said first voltage to said reference voltage, said establishing means comprising a diode, and   second means responsive to said comparing means for placing said providing means in its operative state and for causing said providing means to provide said second warning when said first voltage differs from said   
     
     
        reference voltage by a predetermined amount. .Iaddend. .Iadd.7.  A warning device as defined in claim 6 further comprising means for interrupting said first warning..Iaddend..Iadd.8. A warning device as defined in claim 7 wherein said interrupting means comprises manually manipulative means for resetting said first means to interrupt the placing of said providing means in its operative state by said first means..Iaddend. .Iadd. 9. A warning device as defined in claim 6 wherein said battery comprises a 10.7 volt battery. .Iaddend..Iadd. 10. A warning device as defined in claim 6 wherein said first warning comprises a substantially constant signal. .Iaddend. .Iadd. 11. A warning device comprising a power source, said power source comprising a battery, means energized by said power source for providing first and second audible warnings, said first audible warning comprising a substantially constant signal and said second audible warning comprising a periodic signal, said providing means having an operative state in which either said first warning or said second warning is provided and an inactive state in which neither said first warning nor said second warning is provided,   means for detecting the presence of combustion,   first means responsive to said detecting means upon the detection of the presence of combustion for placing said providing means in its operative state and for causing said providing means to provide said first warning,   means for monitoring the output voltage of said battery, said monitoring means including means for establishing a reference voltage and means for comparing at least a portion of said output voltage to said reference voltage, and   second means responsive to said comparing means for placing said providing means in its operative state and for causing said providing means to provide said second warning when said portion of said output voltage differs from said reference voltage by a predetermined amount. .Iaddend. .Iadd. 12. A warning device as defined in claim 11 wherein said periodic signal comprises a signal that is alternately audible for a first time period and substantially inaudible for a second time period, said first time period being substantially less than said second time period. .Iaddend..Iadd. 13. A warning device as defined in claim 12 wherein said providing means comprises a single audible horn for providing both said first and second audible warnings. .Iaddend. .Iadd. 14. A warning device comprising a power source, said power source comprising a battery,   means energized by said power source for providing first and second audible warnings, said providing means having an operative state in which either said first warning or said second warning is provided and an inactive state in which neither said first warning nor said second warning is provided,   means for detecting the presence of combustion,   first means responsive to said detecting means upon the detection of the presence of combustion for placing said providing means in its operative state and for causing said providing means to provide said first warning,   means for monitoring the output voltage of said battery, said monitoring means including means for establishing a reference voltage and means for comparing at least a portion of said output voltage to said reference voltage, said establishing means comprising a zener diode, and   second means responsive to said comparing means for placing said providing means in its operative state and for causing said providing means to provide said second warning when said portion of said output voltage differs from said reference voltage by a predetermined amount. .Iaddend.   
     
     
        .Iadd. 15.  A warning device as defined in claim 14 wherein said comparing means comprises a unijunction transistor for comparing said portion of said output voltage to said reference voltage. .Iaddend..Iadd. 16. A warning device as defined in claim 15 wherein said unijunction transistor includes a first terminal electrically connected through first series resistive means to the anode of said zener diode, the cathode of said zener diode being directly electrically connected to a first output terminal of said power source. .Iaddend..Iadd. 17. A warning device as defined in claim 16 wherein said unijunction transistor includes a second terminal electrically connected through a path including second series resistive means to a second output terminal of said power source. .Iaddend. .Iadd. 18. A warning device comprising means for detecting the presence of combustion,   means for emitting an audible signal, said emitting means having an active state in which said audible signal is emitted and an inactive state in which said audible signal is not emitted,   first means responsive to said detecting means upon the detection of the presence of combustion for placing said emitting means in said active state and for maintaining said emitting means in said active state and   second means for placing said emitting means in said active state and for maintaining said emitting means in said active state and for simultaneously resetting said first means to interrupt the placing and the maintaining of said emitting means in said active state by said first means. .Iaddend..Iadd. 19. A warning device as defined in claim 18 wherein said second means comprises a manually manipulative means. .Iaddend..Iadd. 20. A warning device as defined in claim 18 further comprising a power source for energizing said emitting means, said power source comprising a battery, and means for monitoring the output voltage of said battery and third means responsive to said monitoring means for placing said emitting means in said active state when said output voltage equals a nonzero, reference value. .Iaddend. .Iadd. 21. A warning device as defined in claim 20 wherein said monitoring means comprises means for establishing a reference voltage and means for comparing at least a portion of said output voltage to said reference voltage, said nonzero reference value being a voltage having a predetermined voltage difference between said portion of said output voltage and said reference voltage. .Iaddend..Iadd. 22. A warning device as defined in claim 21 wherein said power source comprises a 10.7 volt battery. .Iaddend..Iadd. 23. A warning device as defined in claim 21 wherein said third means comprises means for conditioning said emitting means to emit a periodic signal. .Iaddend..Iadd. 24. A warning device as defined in claim 23 wherein said periodic signal comprises a signal that is alternately audible for a first time period and substantially inaudible for a second time period, said first time period being substantially less than said second time period. .Iaddend..Iadd. 25. A warning device as defined in claim 21 wherein said establishing means comprises a zener diode. .Iaddend..Iadd. 26. A warning device as defined in claim 25 wherein said comparing means comprises a unijunction transistor for comparing at least said portion of said output voltage to said reference voltage. .Iaddend. .Iadd. 27. A warning device as defined in claim 26 wherein said unijunction transistor includes a first terminal electrically connected through first series resistive means to the anode of said zener diode, the cathode of said zener diode being directly electrically connected to a first output terminal of said power source. .Iaddend..Iadd. 28. A warning device as defined in claim 27 wherein said unijunction transistor includes a second terminal electrically connected through a path including second series resistive means to a second output terminal of said power source. .Iaddend..Iadd. 29. A warning device as defined in claim 28 wherein said battery includes two output terminals and wherein said first output terminal comprises the more electrically positive one of said two output terminals of said battery and wherein said second output terminal comprises the more electrically negative one of said two output terminals of said battery. .Iaddend..Iadd. 30. A warning device comprising   a power source, said power source comprising a battery,   means for emitting an audible signal, said emitting means having an active state in which said audible signal is emitted and an inactive state in which said audible signal is not emitted,   means for detecting the presence of combustion,   first means responsive to said detecting means for placing said emitting means in said active state and for maintaining said emitting means in said active state,   means for monitoring the output voltage of said battery and   second means responsive to said monitoring means for placing said emitting means in said active state when said output voltage equals a nonzero, reference value, said second means including means for conditioning said   
     
     
        emitting means to emit a periodic signal. .Iaddend..Iadd. 31.  A warning device as defined in claim 30 further comprising means for resetting said first means to interrupt the placing and the maintaining of said emitting means in said active state by said first means. .Iaddend..Iadd. 32. A warning device as defined in claim 31 wherein said resetting means comprises manually manipulative means. .Iaddend..Iadd. 33. A warning device as defined in claim 30 wherein said monitoring means comprises means for establishing a reference voltage. .Iaddend..Iadd. 34. A warning device as defined in claim 33 wherein said monitoring means further comprises means for comparing said output voltage to said reference voltage. .Iaddend. .Iadd. 35. A warning device as defined in claim 34 wherein said battery comprises a 10.7 volt battery. .Iaddend..Iadd. 36. A warning device as defined in claim 34 wherein said periodic signal comprises a signal that is alternately audible for a first time period and substantially inaudible for a second time period, said first time period being substantially less than said second time period. .Iaddend..Iadd. 37. A warning device as defined in claim 34 wherein said establishing means comprises a zener diode. .Iaddend..Iadd. 38. A warning device as defined in claim 37 wherein said comparing means comprises a unijunction transistor for comparing said output voltage to said reference voltage. .Iaddend..Iadd. 39. A warning device as defined in claim 37 wherein said unijunction transistor includes a first terminal electrically connected through series resistive means to the anode of said zener diode, the cathode of said zener diode being directly electrically connected to a first output terminal of said power source. .Iaddend. .Iadd. 40. A warning device as defined in claim 39 wherein said unijunction transistor includes a second terminal electrically connected through a path including second series resistive means to a second output terminal of said power source. .Iaddend.