Smoke detector
A smoke detector replaces the americium source of alpha particles with a field emission device using carbon nanotubes as the field emitters, or some other field emitter, in order to provide an ionization of the air potentially caring smoke particles through the smoke detector.
1. A smoke detector comprising:
a field emitter material positioned on a first substrate;
an electric field operable for activating the field emitter material to emit electrons into a passageway;
a sensor with electrodes positioned relative to the passageway and operable to sense ions created by the emitted electrons; and
a signal coupled to the sensor that is generated when a current created by the ions passes a predetermined threshold level.
2. The smoke detector as recited in claim 1 , wherein the signal is generated when the current created by the ions falls below the predetermined threshold level when smoke particles enter the passageway.
3. The smoke detector as recited in claim 1 , wherein the field emitter material comprises carbon nanotubes.
4. The smoke detector as recited in claim 1 , wherein the substrate is in a form of a grid with holes formed therein through which a gas to be sensed is allowed to pass.
5. The smoke detector as recited in claim 4 , further comprising multiple grids on which the field emitter material is positioned, each such grid having holes formed therein through which the gas to be sensed is allowed to pass.
6. A smoke detector comprising:
a first substrate with a first conductor layer deposited thereon, and a second conductor layer deposited thereon, the first and second conductor layers electrically separated from each other;
a first field emitter material deposited on the first conductor layer, but not on the second conductor layer;
a second substrate with a third conductor layer deposited thereon, and a fourth conductor layer deposited thereon, the third and fourth conductor layers electrically separated from each other;
a second field emitter material deposited on the third conductor layer, but not on the fourth conductor layer;
a voltage source with one electrode coupled to the first and third conductor layers, and a second electrode coupled to the second and fourth conductor layers, the one and second electrodes having opposite polarities from each other;
a sensor with electrodes positioned relative to a passageway and operable to sense ions created by electrons emitted by the first and second field emitter materials into the passageway; and
a signal coupled to the sensor that is generated when a current created by the ions passes a predetermined threshold level.
7. The smoke detector as recited in claim 6 , wherein the signal is generated when the current created by the ions falls below the predetermined threshold level when smoke particles enter the passageway.
8. The smoke detector as recited in claim 6 , wherein the field emitter material comprises carbon nanotubes.
9. The smoke detector as recited in claim 6 , wherein the substrate is in a form of a grid with holes formed therein through which a gas to be sensed is allowed to pass.
10. The smoke detector as recited in claim 9 , further comprising multiple grids on which the field emitter material is positioned, each such grid having holes formed therein through which the gas to be sensed is allowed to pass.
11. The smoke detector as recited in claim 6 , wherein the first and second substrates are in forms of longitudinal wires.
12. A smoke detector comprising:
a field emitter material positioned on a first substrate;
an electric field operable for biasing the field emitter material to pull electrons from a gas present in a passageway;
a sensor with electrodes positioned relative to the passageway and operable to sense ions created by the pulled electrons; and
a signal coupled to the sensor that is generated when a current created by the ions passes a predetermined threshold level.
13. The smoke detector as recited in claim 12 , wherein the signal is generated when the current created by the ions falls below the predetermined threshold level when smoke particles enter the passageway and absorb the ions.
14. The smoke detector as recited in claim 13 , wherein the substrate is in a form of a grid with holes formed therein through which a gas to be sensed is allowed to pass.
15. The smoke detector as recited in claim 14 , further comprising multiple grids on which the field emitter material is positioned, each such grid having holes formed therein through which the gas to be sensed is allowed to pass.
16. The smoke detector as recited in claim 12 , wherein the field emitter material comprises carbon nanotubes.
17. A smoke detector comprising:
a first substrate with a first conductor layer deposited thereon, and a second conductor layer deposited thereon, the first and second conductor layers electrically separated from each other;
a first field emitter material deposited on the first conductor layer, but not on the second conductor layer;
a second substrate with a third conductor layer deposited thereon, and a fourth conductor layer deposited thereon, the third and fourth conductor layers electrically separated from each other;
a second field emitter material deposited on the third conductor layer, but not on the fourth conductor layer;
a voltage source with one electrode coupled to the first and third conductor layers, and a second electrode coupled to the second and fourth conductor layers, the one and second electrodes having opposite polarities from each other;
a sensor with electrodes positioned relative to a passageway and operable to sense ions created by electrons pulled by the first and second field emitter materials from the passageway; and
a signal coupled to the sensor that is generated when a current created by the ions passes a predetermined threshold level.
18. The smoke detector as recited in claim 17 , wherein the signal is generated when the current created by the ions falls below the predetermined threshold level when smoke particles enter the passageway and absorb the ions.
19. The smoke detector as recited in claim 18 , wherein the field emitter material comprises carbon nanotubes.
20. The smoke detector as recited in claim 19 , wherein the substrate is in a form of a grid with holes formed therein through which a gas to be sensed is allowed to pass.
21. A method for detecting particles in a gas comprising:
activating an electric field on a field emitter material to emit electrons into a passageway containing the gas;
sensing a change in current in electrodes positioned in proximity to the passageway, the change in current created by ions produced by the emitted electrons; and
activating a signal when the current passes a predetermined threshold level.
22. The method as recited in claim 21 , wherein the signal is generated when the current falls below the predetermined threshold level when smoke particles enter the passageway.
23. The method as recited in claim 21 , wherein the field emitter material comprises carbon nanotubes.
24. A method comprising:
biasing a field emitter material to pull electrons from a gas present in a passageway;
sensing a change in current in electrodes positioned in proximity to the passageway, the change in current created by ions produced by the pulled electrons; and
activating a signal when the current passes a predetermined threshold level.
25. The method as recited in claim 24 , wherein the signal is generated when the current falls below the predetermined threshold level when smoke particles enter the passageway and absorb the ions.
26. The method as recited in claim 24 , wherein the field emitter material comprises carbon nanotubes.