GB337904A - Improvements in or relating to alarm devices - Google Patents
Improvements in or relating to alarm devicesInfo
- Publication number
- GB337904A GB337904A GB2847229A GB2847229A GB337904A GB 337904 A GB337904 A GB 337904A GB 2847229 A GB2847229 A GB 2847229A GB 2847229 A GB2847229 A GB 2847229A GB 337904 A GB337904 A GB 337904A
- Authority
- GB
- United Kingdom
- Prior art keywords
- reception
- receiver
- intensity
- room
- relating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
- G08B13/24—Electrical actuation by interference with electromagnetic field distribution
- G08B13/2491—Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Burglar Alarm Systems (AREA)
Abstract
337,904. Dicker, S. G. S., (Naamlooze Vennootschap Philips' Gloeilampenfabrieken). Sept. 19, 1929. Burglar and l i k e alarms. - An alarm device for safeguarding rooms and other spaces comprises a transmitter 1 and a receiver 2 for ultrashort waves, of the order of one metre, arranged in a room so that a definite oscillatory condition arises which is varied by anyone entering the room, the reception-intensity being at once affected and an acoustic or optical alarm 3 operated. The receiver is preferably arranged at a point where normally the reception-intensity is a maximum.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2847229A GB337904A (en) | 1929-09-19 | 1929-09-19 | Improvements in or relating to alarm devices |
FR698774D FR698774A (en) | 1929-07-27 | 1930-07-09 | Alarm device |
US471214A US2038878A (en) | 1929-07-27 | 1930-07-28 | Alarm device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB2847229A GB337904A (en) | 1929-09-19 | 1929-09-19 | Improvements in or relating to alarm devices |
Publications (1)
Publication Number | Publication Date |
---|---|
GB337904A true GB337904A (en) | 1930-11-13 |
Family
ID=10276173
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB2847229A Expired GB337904A (en) | 1929-07-27 | 1929-09-19 | Improvements in or relating to alarm devices |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB337904A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE909950C (en) * | 1942-01-08 | 1954-04-26 | Blaupunkt Elektronik G M B H | Arrangement for securing routes and air spaces |
DE1058648B (en) * | 1939-03-13 | 1959-06-04 | Phil Alexander Gibsone Derzeit | Method for searching for or aiming at ferromagnetic bodies or for controlling objects in the direction of ferromagnetic bodies |
GB2249651A (en) * | 1990-11-06 | 1992-05-13 | Racal Guardall | Security system |
-
1929
- 1929-09-19 GB GB2847229A patent/GB337904A/en not_active Expired
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1058648B (en) * | 1939-03-13 | 1959-06-04 | Phil Alexander Gibsone Derzeit | Method for searching for or aiming at ferromagnetic bodies or for controlling objects in the direction of ferromagnetic bodies |
DE909950C (en) * | 1942-01-08 | 1954-04-26 | Blaupunkt Elektronik G M B H | Arrangement for securing routes and air spaces |
GB2249651A (en) * | 1990-11-06 | 1992-05-13 | Racal Guardall | Security system |
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