US3735138A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detector
Assignee: Honeywell Inc
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Filing: 1971-10-27
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Granted: 1973-05-22
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Expires: 1991-10-27
Abstract
Abstract An improved ionization type smoke detector which is specifically designed to be independent of variations in atmospheric pressure and to be highly sensitive to smoke. A number of factors are involved in choosing optimum design parameters for an ionization smoke detector which has minimum sensitivity to pressure and which also has a maximum sensitivity to the presence of smoke. Several equations are described which aid in the design.
Inventors
- 👤 G Rork
- 👤 A Schlachter
- 👤 F Simon
- 👤 R Stryk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 21:09
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11; G08B17/113; H; H01; H01J; H01J41/00; H01J41/02; H01J41/08
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
134 words
A single chamber pressure independent ionization type device for detecting products-of-combustion, the device being of the type where a unidirectional interelectrode current flows between a pair of electrodes and the occurrence of products-of-combustion causes a current change I, the improved device comprising: a pair of electrodes having a geometrical factor A, which geometrical factor includes electrode spacing and electrode size, a radioactive source having a radioactive intensity capable of producing a rate of ion pair production equivalent to a saturation current Is of about 450 to about 650 picoamperes, voltage supply means providing an interelectrode operating current I of about 200 to about 500 picoamperes, at an operating voltage V and said geometry factor A, saturation current Is, operating current I, operating voltage V, and operating pressure P being interrelated according to the relations
Claim 2
Dependent Claim
134 words
A single chamber pressure independent ionization type device for detecting products-of-combustion, the device being of the type where a unidirectional interelectrode current flows between a pair of electrodes and the occurrence of products-of-combustion causes a current change I, the improved device comprising: a pair of electrodes having a geometrical factor A, which geometrical factor includes electrode spacing and electrode size, a radioactive source having a radioactive intensity capable of producing a rate of ion pair production equivalent to a saturation current Is of about 450 to about 650 picoamperes, voltage supply means providing an interelectrode operating current I of about 200 to about 500 picoamperes, at an operating voltage V and said geometry factor A, saturation current Is, operating current I, operating voltage V, and operating pressure P being interrelated according to the relations
Claim 3
Dependent Claim
5 words
I Is -(Po/2) (dIs/dp) Po
Claim 4
Dependent Claim
5 words
I Is -(Po/2) (dIs/dp) Po
Claim 5
Dependent Claim
13 words
I AV2 Mu 2 ( square root (2Is/AV2 Mu 2) +1 -1 )
Claim 6
Dependent Claim
13 words
I AV2 Mu 2 ( square root (2Is/AV2 Mu 2) +1 -1 )
Claim 7
Dependent Claim
13 words
I AV2 Mu 2 ( Square Root (2Is/AV2 Mu 2) +1 -1 )
Claim 8
Dependent Claim
13 words
I AV2 Mu 2 ( Square Root (2Is/AV2 Mu 2) +1 -1 )
Claim 9
Independent Claim
72 words
A method for designing a pressure independent ionization type products-of-combustion sensing device which, in addition to allowing the specifying of pressure independence, concurrently allows the specifying of arbitrary values of sensitivIty and of operating voltage within a restricted range, the method comprising the steps of a. specifying (1) pressure independence, (2) an arbitrary value of sensitivity, (3) and an arbitrary operating voltage; b. substituting the specified values into the three simultaneous equations
Claim 10
Independent Claim
72 words
A method for designing a pressure independent ionization type products-of-combustion sensing device which, in addition to allowing the specifying of pressure independence, concurrently allows the specifying of arbitrary values of sensitivIty and of operating voltage within a restricted range, the method comprising the steps of a. specifying (1) pressure independence, (2) an arbitrary value of sensitivity, (3) and an arbitrary operating voltage; b. substituting the specified values into the three simultaneous equations
Claim 11
Dependent Claim
13 words
I AV2 Mu 2 ( Square Root (2Is/AV2 Mu 2) +1 -1 )
Claim 12
Dependent Claim
13 words
I AV2 Mu 2 ( Square Root (2Is/AV2 Mu 2) +1 -1 )
Claim 13
Dependent Claim
49 words
So 2 (Is -1/2Is - 1) ( Delta Mu o / Mu o) c. Solving the above three simultaneous equations to derive values of saturation current Is, operating current I and geometry A; d. utilizing the derived values and the specified operating voltage in the design of the device.
Claim 14
Dependent Claim
49 words
So 2 (Is -1/2Is - 1) ( Delta Mu o / Mu o) c. Solving the above three simultaneous equations to derive values of saturation current Is, operating current I and geometry A; d. utilizing the derived values and the specified operating voltage in the design of the device.
Claim 15
Dependent Claim
26 words
So 2 (Is - 1/2Is - 1) ( Delta Mu o/ Mu o) thereby causing said operating current to be essentially independent to variations in pressure.
Claim 16
Dependent Claim
26 words
So 2 (Is - 1/2Is - 1) ( Delta Mu o/ Mu o) thereby causing said operating current to be essentially independent to variations in pressure.
Claim 17
Dependent Claim
26 words
So 2 (Is - 1/2Is - 1) ( Delta Mu o/ Mu o) thereby causing said operating current to be essentially independent to variations in pressure.
Claim 18
Dependent Claim
26 words
So 2 (Is - 1/2Is - 1) ( Delta Mu o/ Mu o) thereby causing said operating current to be essentially independent to variations in pressure.
References Cited (Backward Citations)
US3448261A
Cited
US3521263A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |