Alarm sensor

• US 7,242,297 B2
• Filed: 02/16/2005
• Issued: 07/10/2007
• Est. Priority Date: 02/16/2005
• Status: Active Grant

• Current Assignee: William R. Vogt
• Original Assignee: William R. Vogt
• Inventors: Vogt, William R.
• Primary Examiner(s): Lee; Benjamin C.
• Assistant Examiner(s): Tang; Son
• Application Number:
  US11/058,867
• Publication Number:
  US 20060192676A1
• Time in Patent Office: 874 Days
• Field of Search: None
• US Class Current: 340/547
• CPC Class Codes: G08B 13/08 by opening, e.g. of door, of window, of drawer, of shutter, of curtain, of blind
• CPC Class Codes: H01H 36/0046 Limit switches, also fail-safe operation or anti-tamper considerations

Abstract

An alarm system sensor (10) monitoring movement of an object (D) and placing the system into alarm when the object moves more than a predetermined distance from a predetermined position. First and second reed switches (16, 18) are located in a predetermined orientation relative to each other and in tandem to the object. Bias magnets (24, 26) are used with the reed switches. A magnet (20) is movable with the object and produces a force simultaneously sensed by both reed switches. This force maintains both reed switches in a state keeping the alarm system in a non-alarm condition so long as the object substantially remains in its predetermined position. The object, when it moves, moves toward one of the reed switches and away from the other reed switch. Movement of the object more than the predetermined distance results in the force sensed by one of the reed switches increasing and the force sensed by the other reed switch decreasing. Either change in sensed force activates the appropriate reed switch causing the alarm system to go into alarm.

Claims

1. A sensor for use in an alarm system to monitor movement of an object and to place the system into alarm when the object moves more than a predetermined distance from a predetermined position comprising:

a first reed switch and a second reed switch, both reed switches being located in a predetermined orientation relative to each other and to the object;

bias means comprising a first magnet for the first reed switch and a second and separate magnet for the second reed switch; and

,

force means including a third magnet which is movable with the object and produces a force simultaneously sensed by both reed switches, said third magnet and said first and second magnets together producing a null field for each of said first and second reed switches when the obiect is in a predetermined position, and said force means maintaining both reed switches in a state which maintains the alarm system in a non-alarm condition so long as the object substantially remains in its predetermined position, but movement of the object more than the predetermined distance resulting in the force means increasing its force sensed by one of the reed switches and decreasing its force sensed by the other reed switch, either of which conditions causes the alarm system to go into alarm.

2. The sensor of claim 1 in which the first reed switch is mounted in tandem with the second reed switch relative to the movement of the object whereby when the object moves, its movement is substantially toward one of the reed switches and substantially away from the other reed switch.

3. A sensor for use in an alarm system to monitor movement of an object and to place the system into alarm when the object moves more than a predetermined distance from a predetermined position comprising:

a first reed switch and a second reed switch, both reed switches being located in a predetermined orientation relative to each other and to the object, and each reed switch having a predetermined upper and lower limit with respect to which the object can move before an output from the respective reed switch puts the system in an alarm condition;

bias means comprising a first magnet for the first reed switch and a second and separate magnet for the second reed switch; and

,

force means including a third magnet movable with the object and producing a force simultaneously sensed by both reed switches, said force means maintaining both reed switches in a state which maintains the alarm system in a non-alarm condition so long as the object substantially remains in its predetermined position, but movement of the object more than the predetermined distance resulting in the force means increasing its force sensed by one of the reed switches and decreasing its force sensed by the other reed switch, either of which conditions, when it exceeds at least one of the predetermined limits for the reed switches causes the alarm system to go into alarm.

4. The sensor of claim 3 in which the first reed switch is mounted in tandem with the second reed switch relative to the movement of the object, whereby when the object moves, its movement is substantially toward one of the reed switches and substantially away from the other reed switch.

5. The sensor of claim 3 in which the bias means, in conjunction with the force means produces a null force for each reed switch when the object is in its predetermined position.

6. A sensor for use in an alarm system to monitor movement of an object and to place the system into alarm when the object moves more than a predetermined distance from a predetermined position comprising:

a first reed switch and a second reed switch, both reed switches being located in a predetermined orientation relative to each other and to the object;

bias means comprising a separate magnet for each reed switch; and

,

a third magnet movable with the object and producing a force simultaneously sensed by both reed switches, the force produced by the third magnet maintaining both reed switches in a state which places the alarm system in a non-alarm condition so long as the object substantially remains in its predetermined position, the object, when it moves, moving substantially toward one of the reed switches and substantially away from the other reed switch, with movement of the object more than the predetermined distance resulting in the force sensed by one of the reed switches increasing and the force sensed by the other reed switch decreasing, either change in sensed force causing the alarm system to go into alarm.

7. The sensor of claim 6 in which each reed switch has a predtermined upper and lower limit with respect to which the object can move before an output from the respective reed switch puts the system in an alarm condition, and movement of the object more than the predetermined distance resulting in the third magnet increasing the force sensed by one of the reed switches and decreasing the force sensed by the other reed switch, either of which condition, when it exceeds at least one of the predetermined limits for the respective reed switch causes the alarm system to go into alarm.

8. The sensor of claim 6 in which the first reed switch is mounted in tandem with the second reed switch relative to the movement of the object.

9. The sensor of claim 8 in which the bias means, in conjunction with the third magnet produces a null force for each reed switch when the object is in its predetermined position.

10. A sensor for use in an alarm system to monitor movement of an object and to place the system into alarm when the object moves more than a predetermined distance from a predetermined position comprising:

a first sensing means and a second sensing means both of which are located in a predetermined orientation relative to each other and to the object;

bias means simultaneously acting upon both sensing means and,

force means movable with the object and producing a force simultaneously sensed by both sensing means, said force means and said bias means maintaining a substantially null force on both sensing means while the objects substantially remains in its predetermined position whereby the alarm system remains in a non-alarm condition, but movement of the object more than the predetermined distance resulting in the force means simultaneously increasing its force to which one of the sensing means is subjected and decreasing its force to which the other sensing means is subjected whereby, when the resultant force to which either of the sensing means is subjected passes a preset limit for that sensing means, the sensing means causes the alarm system to go into alarm.

11. The sensor of claim 10 in which the first and second sensing means are each reed switches mounted in tandem with each other, the bias means includes a separate magnet for each reed switch, and the force means includes a third magnet.

12. The sensor of claim 11 in which the positioning of a fourth and compromising magnet adjacent the object as the object moves, and in proximity to the reed switches, so to attempt to defeat the sensor, provides sufficient force, together with the force to which the reed switches are subjected by the third magnet, as the object moves, to cause one of the reed switches to place the alarm system into alarm.