Alarm switch having resilient gripping structure for sensing unauthorized movement of a door

Claim 1

An alarm switch mounted by means of a support for actuation by relative movement between the support and a member such as a door or window comprising: switching means carried by the support; an operating arm for the switching means extending from the support and carried thereby, said arm being adapted to be pulled a limited distance relative to the support for actuating the switching means to complete an alarm circuit; and interengageable gripping members on the arm and said member for pulling the arm said limited distance relative to the support to actuate the switching means when there is relative movement between the member and the support, and said gripping members automatically disengaging to free the member from the arm when the relative movement between the member and the support is greater than said limited distance, said gripping members being selectively disengageable to permit relative movement between the support and said member without actuating the alarm switch, said switching means comprising at least one switch having an operating member adapted to be pushed in to close the switch and to be pushed in again to open the switch, said arm being engageable with said operating member to push it in to close the switch when said member moves relative to the support, the gripping members then disengaging and the switch remaining closed.