PROPERTY SECURITY SYSTEM

• US 3,609,742 A
• Filed: 02/07/1969
• Issued: 09/28/1971
• Est. Priority Date: 02/07/1969
• Status: Expired due to Term

• Current Assignee: Hugh D. Burdick
• Original Assignee: Hugh D. Burdick
• Inventors: Burdick, Hugh D.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Mooney, Robert J.
• Application Number:
  US04/797,441
• Time in Patent Office: 963 Days
• Field of Search: 340/310,216,280,276
• US Class Current: 340/538
• CPC Class Codes: G08B 13/1409 for removal detection of electrical appliances by detecting their physical disconnection from an electrical system, e.g. using a switch incorporated in the plug connector
• CPC Class Codes: G08B 25/06 using power transmission lines

Abstract

Property security apparatus for producing a pulsed perceptible signal, audible and/or visual, at a detection location whenever electrical apparatus, such as a television set, is disconnected from a convenience outlet socket at a remote location. A sensing switch at the outlet socket closes in response to withdrawal of an electric power cord plug therefrom, and such closure initiates the production of a coded sequence of pulses of a radiofrequency signal that is coupled to the electric power circuit with the latter serving as a transmission line for the pulsed radiofrequency signal to the detection location. Means is provided at the detection location for pulsing a perceptible signal generator in synchronism with the detection of radiofrequency pulses. The sequence of radiofrequency pulses are uniquely coded whereby identification of the particular sensing switch can be made, when a plurality of combined sensing switch and radiofrequency signaling units are employed at a plurality of different locations.

Claims

1. In a property security system for signaling the occurrence of a predetermined condition evidenced by closure of a sensing switch, an improved apparatus comprising means for producing a radiofrequency signal output, a first electric switch means operatively coupled to the signal producing means for selectively preventing signal output, an electric circuit adapted to be connected to a source of alternating current electric power, a second electric switch means in said electric circuit, switch actuating means operable during electrical energization thereof cyclically to open and close said second electric switch means with the closure interval being several times longer in duration than the open interval and said switch actuating means being also operable during electrical energization thereof cyclically to cause, during said closure interval, the repetitious occurrence of a predetermined sequence of opening and closing of said first electric switch means, said switch actuating means being in said electric circuit for energization therefrom, and said sensing switch being in the said electric circuit in electrical parallel and electrical series with the second electric switch means and said switch actuating means respectively.

2. The combination of claim 1, including an electric power distributing circuit means for delivering alternating current electric power to a pair of positions remote from each other, said first electric circuit being disposed adjacent one of such positions and being connected tO said power circuit means whereby the latter constitutes a source of alternating current electric power therefor, and radiofrequency coupling means at said one position for introducing the radiofrequency signal output into said power circuit means whereby radiofrequency signal output is transmitted by the power circuit means to the other of said positions, and radiofrequency signal detecting and signaling means coupled to the power circuit means at the other of said positions for concurrently producing, during radiofrequency signal detection, a perceptible signal.

3. The combination of claim 2, wherein the power circuit means includes a female power outlet socket adapted to receive thereinto the prongs of a male power plug, said sensing switch being normally closed, and means for opening said sensing switch in response to a male power plug being received in said socket, whereby the predetermined condition signaled by the system is the absence of a power cord plug from the socket.

4. The combination of claim 1, wherein said first electric switch means is a single pole, single throw electric switch, and wherein the second electric switch means is a rotary electric switch, and wherein said switch actuating means comprises an electric motor, means drivingly connecting the motor to the rotary electric switch for rotating the latter, rotary cam means provided with a circularly arranged array of cam lobes operative during rotation thereof to open and close the single pole, single throw electric switch, and means drivingly connecting the motor to the cam means for rotating the latter.

5. The combination of claim 4, including a second electric circuit adapted to be connected to a source of electrical power, and said second electric circuit including in electrical series said means for producing a radiofrequency output and said single pole, single throw electric switch, whereby a radiofrequency signal output can be produced only during closure of the last mentioned switch.

6. The combination of claim 5, wherein the second electric circuit is in electrical parallel with said motor, the arrangement being such that a radiofrequency signal output will be produced when and only when the single pole, single throw switch is closed and the motor is concurrently energized.

7. The combination of claim 1, including a female electric power outlet socket means, having a pair of electric terminals, for guidingly receiving the prongs of a power cord male plug thereinto and for electrically connecting said terminals to plug prongs received thereinto, said sensing switch being comprised of a fixed contact electrically and mechanically connected to one of said terminals, a second contact, a resilient member fixed to the socket means and carrying the second contact, said member being flexible and yieldingly urging the second contact into engagement with the fixed contact, and said resilient member being disposed in the travel path of a male plug prong received in the socket means, whereby said second contact is disengaged from the fixed contact when a male plug is received within the socket means, and said electric circuit being connected to the terminals of the socket means with the second electric switch means being connected to said one of the terminals.

8. The combination of claim 7, including an electric power distributing circuit means for delivering alternating current electric power to a pair of positions remote from each other, said socket means being at one of said positions with the terminals thereof being connected to the electric power distributing circuit means, radiofrequency coupling means at said one position for introducing the radiofrequency signal output into said power circuit means whereby radiofrequency signal output is transmitted by the power circuit means to the other of said positions, and radiofrequency signal detecting and signaling means coupled to the power circuit means at the other of said positions for concurrently producing, during radiofrequency detection, a perceptible signal.

9. The combination of claim 8, wherein the detecting and signaling means comprises a direct current power supply means connected to the power circuit means, a radiofrequency signal detecting means connected to the power supply means for energization and operative to produce a direct electric current output in response to and concurrently with detection of a radiofrequency signal, a perceptible signal generating means connected to the detecting means for generating a perceptible signal in response to and concurrently with direct current output by the detecting means.