SNAP ACTION TYPE INERTIA SWITCH WITH VIBRATION AMPLICATION AND ACTUATOR MEANS

• US 3,862,386 A
• Filed: 09/29/1972
• Issued: 01/21/1975
• Est. Priority Date: 09/29/1972
• Status: Expired due to Term

• Current Assignee: Robert A. Hall
• Original Assignee: Robert A. Hall
• Inventors: Hall, Robert A.
• Primary Examiner(s): Scott, James R.
• Application Number:
  US05/293,354
• Time in Patent Office: 844 Days
• Field of Search: 200/6B,61.45R,61.5,61.51 340/261,262,266 73/71,490,514,517R,517AV
• US Class Current: 200/61.45R
• CPC Class Codes: G08B 13/1654 using passive vibration detection systems

Abstract

A device for detecting vibration of a surface on which the device is mounted includes a pair of levers mounted so that movement of one of them about a first pivot causes amplified movement of the other about a second pivot. The first lever is pivoted at one end about the first pivot and integral with a mass that tends to remain stationary, because of its inertia, when the surface vibrates. The end of that lever opposite its pivot engages the second lever at a point relatively close to the second pivot. The end of the second lever opposite the second pivot is highly sensitive to vibration in that it moves a considerable distance in response to a small relative movement of the surface with respect to the mass. The free end of the second lever normally holds an alarm-actuating mechanism in a cocked condition but releases it, so that a single-pole, double-throw switch is operated and an alarm is given, in response to vibration exceeding a predetermined intensity. The alarmactuating mechanism is released also in response to separation of the device from the surface. The device is useful in burglary detection, for example in detecting breakage of glass (the device can replace the foil often used for this purpose) and in detecting attempts to burglarize steel or concrete vaults and other enclosures made of relatively strong, rigid materials.

Claims

1. A detector for mounting on a surface to detect vibration of the surface, comprising:

a mass, mounting means for mounting the mass movably with respect to the surface so that the mass can remain relatively stationary when the surface vibrates, mechanical amplifying means responsive to the relative movement of the mass with respect to the surface for amplifying the relative movement and producing a mechanically-amplified output, and indicator means responsive to the mechanically-amplified output for indicating when vibration of the surface exceeding a predetermined intensity has occurred, wherein the mounting means comprises first pivot means and first lever means pivoted about thE first pivot means and integral with the mass, wherein the mechanical amplifying means comprises second pivot means and second lever means pivoted about the second pivot means, the first lever means engaging the second lever means, at a point relatively close to the second pivot means, in such a manner that movement of the first lever means about the first pivot means causes movement of the second lever means about the second pivot means, and wherein the indicator means responds to movement of a portion of the second lever means relatively far from the second pivot means.

2. In a detector that can assume alternately a cocked condition and an actuated condition and that can be mounted on a surface to detect vibration of the surface when the surface or adjacent structure is attacked, an improvement that prevents circumvention of the detector by removing it from the surface before the attack and that comprises latch means for latching the detector in the cocked condition, actuating means for releasing the latch means in response to vibration of the surface exceeding a predetermined intensity, thus permitting the detector to assume the actuated condition, indicator means providing an indication in response to the assumption of the actuated condition, plunger means movable between first and second positions and permitting, in the first position, latching of the detector in the cocked condition by the latch means and preventing, in the second position, latching of the detector in the cocked condition, and biasing means biasing the plunger means towards the second position, the plumger means being forced to the first position when the detector is mounted on the surface, so that the detector can be latched in the cocked condition in the absence of vibration exceeding the predetermined intensity when the detector is mounted on the surface but cannot be latched in the cocked condition, and hence assumes the actuated condition, when the detector is removed from the surface and the biasing means moves the plunger means to the second position.

3. In a detector for mounting on a surface to detect vibration of the surface, an improvement that prevents circumvention of the detector by electrically shunting it and that comprises relay means, a power supply, three terminal means, three contact means respectively electrically connected to the three terminal means, one of the contact means being normally closed with respect to a second and open with respect to the third of the contact means, thereby placing the relay means in circuit with the power supply, and means responsive to vibration of the surface exceeding a predetermined intensity for opening the first contact means with respect to the second and closing the first contact means with respect to the third, thereby shorting the relay means, the means responsive to vibration of the surface comprising a relatively stationary mass mounted movably with respect to the surface so that the mass can remain relatively stationary when the surface vibrates.

4. A detector for mounting on a surface to detect vibration of the surface, comprising:

a first lever, first pivot means mounting said first lever for pivotal movement, a second lever, second pivot means mounting said second lever for pivotal movement, and latch means engageable with said second lever at a point spaced apart from said second pivot for holding said detector in a cocked condition, said first lever engaging said second lever at a point relatively close to said second pivot as compared to the separation between said latch means and said second pivot, said first lever responding to vibration of said surface exceeding a predetermined intensity by pivoting about said first pivot and causing pivoting of greater amplitude by said second lever about said second pivot, whereby said latch means is actuated to permit said detector to move in an actuated condition.

5. A detector according to claim 1 wherein the indicator means comprises a flag visible outside the detEctor and movable in response to the mechanically-amplified output.

6. A detector according to claim 1 wherein the indicator means comprises an audible alarm and electrical switch means for actuating the alarm, the electrical switch means being actuated in response to the mechanically-amplified output.