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GB337904A - Improvements in or relating to alarm devices - Google Patents

Improvements in or relating to alarm devices

Info

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
Application number
GB2847229A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Philips Gloeilampenfabrieken NV filed Critical Philips Gloeilampenfabrieken NV
Priority to GB2847229A priority Critical patent/GB337904A/en
Priority to FR698774D priority patent/FR698774A/en
Priority to US471214A priority patent/US2038878A/en
Publication of GB337904A publication Critical patent/GB337904A/en
Expired legal-status Critical Current

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.
GB2847229A 1929-07-27 1929-09-19 Improvements in or relating to alarm devices Expired GB337904A (en)

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)

* Cited by examiner, † Cited by third party
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

Cited By (3)

* Cited by examiner, † Cited by third party
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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