US3838283A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization smoke detector
Assignee: Bevaknings AB Securitas
•
Filing: 1972-10-18
•
Granted: 1974-09-24
•
Expires: 1992-10-18
Abstract
Abstract An ionization smoke detector having an open and a closed chamber which are interconnected by a thin metallic membrane, constituting a common electrode. The membrane is urged against the periphery of an opening between the chambers by means provided on a removable cover defining the open chamber. A single source of radiation is provided in the closed chamber.
Inventors
- 👤 I Andersson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:13
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/62; G01N27/64
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
109 words
An ionization smoke detector comprising, a. A housing having a first ionization chamber closed to ambient air and an opening therein, b. a single source of radiation located in said first ionization chamber, c. an air permeable cover having a second ionization chamber therein releasably attached to said housing, d. a thin metallic membrane covering said opening in said housing, said membrane being a radiation permeable wall and a measuring electrode common to said first and second ionization chambers, and e. means affixed to said air permeable cover to urge said membrane against the peripheral edge of said opening to provide air tight sealing of said first ionization chamber.
Claim 2
Dependent Claim
109 words
An ionization smoke detector comprising, a. A housing having a first ionization chamber closed to ambient air and an opening therein, b. a single source of radiation located in said first ionization chamber, c. an air permeable cover having a second ionization chamber therein releasably attached to said housing, d. a thin metallic membrane covering said opening in said housing, said membrane being a radiation permeable wall and a measuring electrode common to said first and second ionization chambers, and e. means affixed to said air permeable cover to urge said membrane against the peripheral edge of said opening to provide air tight sealing of said first ionization chamber.
Claim 3
Dependent Claim
27 words
The smoke detector, of claim 1 wherein a substantially air tight insert member (6) is connected to the housing and in which insert said opening is provided.
Claim 4
Dependent Claim
20 words
The smoke detector according to claim 1 wherein the source of radiation includes the isotope Krypton 85 or Argon 39.
Claim 5
Dependent Claim
41 words
The smoke detector according to claim 1 wherein the source of radiation comprises a closed tube, filled with a gaseous isotope emitting Beta -radiation, positioned adjacent the membrane and having its longitudinal axis substantially parallel with the plane of the membrane.
Claim 6
Dependent Claim
32 words
The smoke detector according to claim 1 wherein said membrane (9) is gas tight secured to a second membrane (19) and that the radiation emitting substance is provided between said two membranes.
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) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |