WINDOW SECURITY SYSTEM

• US 3,634,845 A
• Filed: 03/27/1968
• Issued: 01/11/1972
• Est. Priority Date: 03/27/1968
• Status: Expired due to Term

• Current Assignee: Robert Colman
• Original Assignee: Robert Colman
• Inventors: Colman, Robert
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Bobbitt, J. Michael
• Application Number:
  US04/716,544
• Time in Patent Office: 1,385 Days
• Field of Search: 340/274,276,273 200/61.08,61.62,61.84,61.93 250/71.5
• US Class Current: 340/508
• CPC Class Codes: G08B 13/04 by breaking of glass

Abstract

A window protection system in which a pair of electrically conductive strips extend across a window with a bias voltage source connected across one end of the strips and an alarmactuating circuit connected across the other end of the strips, the alarm-actuating circuit being capable of energizing the alarm if the strips are broken or if they are bridged; and a battery which converts ray energy from radioactive materials to electricity through the intermediary of visible light.

Claims

1. A window protection alarm system comprising at least one pair of electrically conductive strips extending across a window, means at one end of said strips for connecting a bias voltage across the pair of strips, an alarm, an electrical alarm actuation control circuit including a voltage responsive alarmactuating switch also connected across the pair of strips at the other end thereof, said alarm-actuating switch being responsive to said bias voltage to maintain said alarm deactuated, said switch further being responsive to removal of said bias voltage from across said strips to produce actuation of said alarm whereby said window is protected by alarm actuation upon either short circuiting or open circuiting of said strips, said alarmactuating switch including a resistor connected serially along one of said conductors, a first, PNP-type transistor having its collector connected via a capacitor to one side of said resistor and its emitter connected directly to the other of said conductors, and a second, NPN-type transistor having its emitter connected directly to the other side of said resistor and its collector connected via a further resistor to said other electrical conductor, the base and collectors of said transistors being cross-connected

2. A window protection alarm system as in claim 1 wherein said means for connecting a bias source comprises a bias Source holding means mounted on a window casing and a cord including a pair of wires extending from said holding means to said strips whereby said strips may carry a bias voltage even when the window is partially opened.

3. A window protection alarm system as in claim 2 wherein there is provided in conjunction with said electrical alarm actuation control circuit a further switch for disabling said alarm actuation control circuit.

4. A window protection alarm system as in claim 3 wherein said further switch is key operated.

5. A window protection alarm system as in claim 1 wherein said electrical alarm actuation control circuit comprises a single alarm-actuating switch and a plurality of individual window protection circuits each including a pair of said electrically conductive strips, means for connecting a bias voltage source across said strips at one end thereof in each pair and means for connecting said alarm-actuating switch across said strips at the other end of each pair of strips.

6. A window protection alarm system as in claim 5 wherein said means connecting said alarm-actuating switch across each pair of strips comprises individual switch means connected across each of said pairs of strips and operable to prevent control of alarm actuation by the short circuiting or open circuiting of their respective strips.

7. A window protection alarm system as in claim 1 wherein said alarm actuation control circuit further comprises a pair of electrical conductors connected at one end, respectively, to said other end of each of said strips, and means connecting the opposite ends of said conductors across a source of electrical power, said alarm-actuating switch being responsive to a change in electrical impedance across said conductors to switch to an alarm-actuating condition.

8. A window protection alarm system as in claim 7 wherein said alarm-actuating switch includes a relay having its coil connected serially along one of said conductors, said relay having switch contacts connected to actuate said alarm when said coil is energized and means responsive to a change in impedance across said conductors to electrically connect said leads and permit current to flow through said relay.

9. A window protection alarm system as in claim 7 wherein said window protection circuit includes a sensor switch electrically connected across said one end of said electrical conductors, said sensor switch being normally closed and held to open condition by the application thereto of bias voltage applied via said strips.

10. A window protection alarm system as in claim 9 wherein said sensor switch comprises a transistor having its emitter and collector terminals connected respectively to said conductors and one of said terminals and its base connected respectively to said other end of said strips.

11. A window protection alarm system as in claim 1 wherein said bias voltage source comprises a photovoltaic cell connected across said one end of said electrically conductive strips and arranged to have light incident thereon.

12. A window protection alarm system according to claim 2 wherein said strips extend side by side in parallel fashion across said window.

13. A window protection alarm system as in claim 1 wherein said bias voltage comprises a ray energy voltage-generating means.

14. A window protection alarm system as in claim 13 wherein said voltage-generating means comprises a radioactive isotope, a phosphor adjacent to and responsive to radiation from said isotope for generating visible light and a photovoltaic cell adjacent to said phosphor for generating a voltage in response to light from said phosphor.

15. A window protection system according to claim 1 wherein said strips are in the form of an electrically conductive transparent coating on the surface of said window.

16. A window protection alarm system as in claim 15 wherein said electrically conductive coating comprises tin oxide. 17 A window protection alarm system as in claim 15 wherein said Pane including said transparent coating is further covered over with a transparent electrically nonconductive protective coating.

18. A window protection alarm system as in claim 17 wherein said protective coating comprises silicon monoxide.