US4081684A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Combustion product detector
Assignee: Individual
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Filing: 1975-06-30
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Granted: 1978-03-28
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Expires: 1995-06-30
Abstract
Abstract A combustion product detector contains a single ionization chamber having a radioactive source therein. It is provided with means to test the function of the device. The means includes an electrically non-conductive member which may be introduced in the ionization chamber to simulate (in effect) the presence of smoke in the chamber. Housing for the chamber is constructed and mounted to shield the components contained therein. An FET and resistors are closely coupled to a radioactive source holder and to a printed circuit board on which the housing is mounted. A metal coil spring electrically connects the non-conductive test member and the housing to discharge static. The test member may be removed readily to permit inspection and cleaning of the radioactive source surface. The device may be powered from a battery or from AC line current with or without a standby battery to automatically power the device in the event of line current failure and may be provided with a circuit to produce a signal in the event of power failure.
Inventors
- 👤 Horst K. Wieder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:22
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11; G08B17/113
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
223 words
In a device for producing a voltage change in an electrical circuit in response to the presence of combustion products in a portion of the device, the combination of: a radioactive source, said source disposed in an electrically shielded space, said shielded space being the portion of the device wherein the presence of combustion products causes said voltage change to be produced, said shielded space defined by: an electrically conductive housing member having an aperture to receive a test member and having apertures to admit combustion products to said space, and electrically conductive material in electrical contact with said housing member, a test member of electrically non-conducting material, means to slidably support said test member, said test member provided with engaging means to engage with a spring member, said test member slidably mounted in said support means and received in said aperture in said housing in a normal position wherein a portion of said test member extends into said space, said test member mounted to be slidably moved manually to extend further into said space to produce an impedance change comparable to that produced by the presence of combustion products in said space. a spring member extending into contact with said engaging means of said test member and biasing said test member toward said normal position and away from extending into said space.
Claim 2
Dependent Claim
223 words
In a device for producing a voltage change in an electrical circuit in response to the presence of combustion products in a portion of the device, the combination of: a radioactive source, said source disposed in an electrically shielded space, said shielded space being the portion of the device wherein the presence of combustion products causes said voltage change to be produced, said shielded space defined by: an electrically conductive housing member having an aperture to receive a test member and having apertures to admit combustion products to said space, and electrically conductive material in electrical contact with said housing member, a test member of electrically non-conducting material, means to slidably support said test member, said test member provided with engaging means to engage with a spring member, said test member slidably mounted in said support means and received in said aperture in said housing in a normal position wherein a portion of said test member extends into said space, said test member mounted to be slidably moved manually to extend further into said space to produce an impedance change comparable to that produced by the presence of combustion products in said space. a spring member extending into contact with said engaging means of said test member and biasing said test member toward said normal position and away from extending into said space.
Claim 3
Dependent Claim
41 words
The device of claim 1 wherein the distance said test member is moved into said chamber prior to actuation of said device to produce said impedance change tends toward being inversely proportional to the amount of contamination on said radioactive source.
Claim 4
Dependent Claim
38 words
The device of claim 1 wherein said spring member is of electrically conductive material and is in electrical contact with an external portion of said housing member to prevent accumulation of excess static charge on said housing member.
Claim 5
Dependent Claim
16 words
The device of claim 1 wherein said housing member is formed from a single flat blank.
Claim 6
Dependent Claim
58 words
The device of claim 1 wherein said means to slidably support said test member comprise laterally extending resilient finger members and said test member is laterally removable from said finger members and thence longitudinally removable from said aperture in said housing member in which it is received to expose said source through said aperture for inspection and cleaning.
Claim 7
Independent Claim
90 words
The device of claidm 1 wherein said source is a portion of a member which is a flat sheet member except for having an upwardly extending dimple therein and said dimpled source member is retained in a holding member, said holding member having a convexedly upwardly extending central portion acting to provide said dimple in said source member, a portion extending outwardly from said central portion to an upwardly extending wall portion, said wall portion extending inwardly to exert inward and downward force on the periphery of said source member.
Claim 8
Independent Claim
90 words
The device of claidm 1 wherein said source is a portion of a member which is a flat sheet member except for having an upwardly extending dimple therein and said dimpled source member is retained in a holding member, said holding member having a convexedly upwardly extending central portion acting to provide said dimple in said source member, a portion extending outwardly from said central portion to an upwardly extending wall portion, said wall portion extending inwardly to exert inward and downward force on the periphery of said source member.
Claim 9
Dependent Claim
29 words
The device of claim 1 wherein said electrically conductive material which with said housing member defines said shielded space is a layer of metal on a printed circuit board.
Claim 10
Dependent Claim
47 words
The device of claim 7 wherein a field effect transistor and two resistors are provided within said shielded space and are disposed in close proximity to said source and to said printed circuit board and the lengths of the leads of said transistor and resistors are minimized.
Claim 11
Dependent Claim
41 words
The device of claim 8 wherein said source is mounted in a holder member and said holder member is supported from said printed circuit board by at least one lead extending from at least one of said transistor and said resistors.
Claim 12
Dependent Claim
165 words
In a device for producing a voltage change in an electrical circuit in response to the presence of combustion products in a portion of the device, the combination of: a radioactive source, said source disposed in an electrically shielded space, said shielded space being the portion of the device wherein the presence of combustion products causes said voltage change to be produced, said shielded space defined by: an electrically conductive housing member having an aperture to receive a test member and having apertures to admit combustion products to said space, and electrically conductive material in electrical contact with said housing member, said electrically conductive material which with said housing member defines said shielded space is a layer of metal on a printed circuit board, a field effect transistor and two resistors are provided within said shielded space and are disposed in close proximity to said source and to said printed circuit board and the lengths of the leads of said transistor and resistors are minimized.
Claim 13
Dependent Claim
165 words
In a device for producing a voltage change in an electrical circuit in response to the presence of combustion products in a portion of the device, the combination of: a radioactive source, said source disposed in an electrically shielded space, said shielded space being the portion of the device wherein the presence of combustion products causes said voltage change to be produced, said shielded space defined by: an electrically conductive housing member having an aperture to receive a test member and having apertures to admit combustion products to said space, and electrically conductive material in electrical contact with said housing member, said electrically conductive material which with said housing member defines said shielded space is a layer of metal on a printed circuit board, a field effect transistor and two resistors are provided within said shielded space and are disposed in close proximity to said source and to said printed circuit board and the lengths of the leads of said transistor and resistors are minimized.
Claim 14
Dependent Claim
16 words
The device of claim 10 wherein said housing member is formed from a single flat blank.
Claim 15
Dependent Claim
41 words
The device of claim 10 wherein said source is mounted in a holder member and said holder member is supported from said printed circuit board by at least one lead extending from at least one of said transistor and said resistors.
Claim 16
Dependent Claim
90 words
the device of claim 10 wherein said source is a portion of a member which is a flat sheet member except for having an upwardly extending dimple therein, and said dimpled source member is retained in a holding member, said holding member having a convexedly upwardly extending central portion acting to provide said dimple in said source member, a portion extending outwardly from said central portion to an upwardly extending wall portion, said wall portion extending inwardly to exert inward and downward force on the periphery of said source member.
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) | 1981-03-27 | 1981-09-26 | 1982-03-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-27 | 1985-09-26 | 1986-03-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-27 | 1989-09-26 | 1990-03-28 | $7700.00 | Window Closed / Lapsed |