US4336455A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Smoke detectors
Assignee: GE Healthcare Ltd
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Filing: 1980-11-03
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Granted: 1982-06-22
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Expires: 2000-11-03
Abstract
Abstract The invention relates to smoke detectors of the kind comprising first and second electrodes defining an ionization chamber permitting entry of smoke, said ionization chamber being optionally divided into two regions by a collector electrode, a radioactive source to ionize gas in the ionization chamber and a potential difference applied across the first and second electrodes to cause an ion current to flow, which current is affected by entry of smoke, and provides an auxiliary electrode positioned in the ionization chamber, and means to maintain or create a potential difference between the first electrode and the auxiliary electrode. The auxiliary electrode may be used for testing or for adjustment of sensitivity.
Inventors
- 👤 Jack Bryant
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:44
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11; G08B17/113; G08B29/00; G08B29/12; G08B29/14; G08B29/145
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
121 words
A smoke detector comprising: first and second electrodes positioned to define therebetween an ionization chamber; a radioactive substance positioned for emitting radiation into said ionization chamber for causing ionization of a gas therein; first means for maintaining a potential difference across said first and second electrodes for causing an ion current to flow therebetween, said current being caused to vary when smoke enters said ionization chamber; second means for testing the detector or for adjusting its sensitivity, said second means comprising an auxiliary electrode located in said ionization chamber for affecting the electric field between said first and second electrodes; and third means for creating, controlling and varying an externally applied potential difference between said first electrode and said auxiliary electrode.
Claim 2
Dependent Claim
121 words
A smoke detector comprising: first and second electrodes positioned to define therebetween an ionization chamber; a radioactive substance positioned for emitting radiation into said ionization chamber for causing ionization of a gas therein; first means for maintaining a potential difference across said first and second electrodes for causing an ion current to flow therebetween, said current being caused to vary when smoke enters said ionization chamber; second means for testing the detector or for adjusting its sensitivity, said second means comprising an auxiliary electrode located in said ionization chamber for affecting the electric field between said first and second electrodes; and third means for creating, controlling and varying an externally applied potential difference between said first electrode and said auxiliary electrode.
Claim 3
Dependent Claim
28 words
A smoke detector as claimed in claim 1, wherein the area of said auxiliary electrode is approximately from 1% to 20% of the area of said first electrode.
Claim 4
Dependent Claim
101 words
A smoke detector comprising: an outer electrode; a collector electrode; an inner electrode made of or supporting a radioactive substance thereon; said outer electrode being located with respect to said collector electrode so as to define therebetween an outer ionization region capable of allowing smoke to enter therein from the surrounding atmosphere; said collector electrode and said inner electrode being located with respect to each other so as to define therebetween an inner ionization region; said collector electrode having at least one hole for allowing radiation from said radioactive substance to pass therethrough for causing ionization in both said ionization regions;
Claim 5
Dependent Claim
101 words
A smoke detector comprising: an outer electrode; a collector electrode; an inner electrode made of or supporting a radioactive substance thereon; said outer electrode being located with respect to said collector electrode so as to define therebetween an outer ionization region capable of allowing smoke to enter therein from the surrounding atmosphere; said collector electrode and said inner electrode being located with respect to each other so as to define therebetween an inner ionization region; said collector electrode having at least one hole for allowing radiation from said radioactive substance to pass therethrough for causing ionization in both said ionization regions;
Claim 6
Dependent Claim
106 words
first means for maintaining a potential difference between said outer electrode and said inner electrode, whereby said collector electrode acquires a potential which is intermediate the potentials of said outer and inner electrodes, said intermediate potential being caused to vary by entry of smoke particles into said outer ionization region; second means for testing the detector or for adjusting its sensitivity, said second means comprising an auxiliary electrode located in said outer ionization region for affecting the electric field between said outer and collector electrodes; and third means for creating, controlling and varying an externally applied potential difference between said outer electrode and said auxiliary electrode.
Claim 7
Dependent Claim
106 words
first means for maintaining a potential difference between said outer electrode and said inner electrode, whereby said collector electrode acquires a potential which is intermediate the potentials of said outer and inner electrodes, said intermediate potential being caused to vary by entry of smoke particles into said outer ionization region; second means for testing the detector or for adjusting its sensitivity, said second means comprising an auxiliary electrode located in said outer ionization region for affecting the electric field between said outer and collector electrodes; and third means for creating, controlling and varying an externally applied potential difference between said outer electrode and said auxiliary electrode.
Claim 8
Dependent Claim
25 words
A smoke detector as claimed in claim 3, wherein said auxiliary electrode is mounted parallel to and just inside, but insulated from, said outer electrode.
Claim 9
Dependent Claim
28 words
A smoke detector as claimed in claim 4, wherein the area of said auxiliary electrode is approximately from 1% to 20% of the area of said outer electrode.
Claim 10
Dependent Claim
46 words
A smoke detector as claimed in claim 3, wherein said auxiliary electrode is normally maintained at the same potential as said outer electrode, and further comprising means for testing purposes for bringing said auxiliary electrode to a predetermined potential different from that of said outer electrode.
Claim 11
Dependent Claim
29 words
A smoke detector as claimed in claim 6, further comprising means for avoiding a voltage surge on said collector electrode when the potential of said auxiliary electrode is altered.
Claim 12
Dependent Claim
36 words
A smoke detector as claimed in claim 3, further comprising means for adjusting the potential of said auxiliary electrode so that an alarm or positive response of the detector is triggered at a desired smoke density.
Claim 13
Dependent Claim
25 words
A smoke detector as claimed in claim 1 or claim 3, wherein said radioactive source has an activity of from 0.1 to 1 micro Curie.
Claim 14
Dependent Claim
24 words
A smoke detector as claimed in claim 1 or claim 3, wherein said radioactive source emits alpha-particles, beta-particles, conversion electrons, auger electrons or X-rays.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-06-21 | 1985-12-21 | 1986-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-06-21 | 1989-12-21 | 1990-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-06-21 | 1993-12-21 | 1994-06-22 | $7700.00 | Window Closed / Lapsed |