Patent ID: 8677155

Claim:
An intrusion detection system for a split case device, comprising: a tamper switch pressed against a circuit board inside a split case of the device when top and bottom casings of said case are mechanically secured to each other, wherein the tamper switch comprises an outer actuator member, an intermediate actuator member and an inner actuator member, each of said three members having an electrically conductive surface at one end and said conductive surfaces being electrically connected between themselves; wherein the circuit board comprises an outer conductive contact, an intermediate conductive contact and an inner conductive contact on top of which corresponding conductive surfaces of the three members of the tamper switch are placed, the inner contact being situated inside the intermediate contact and the intermediate contact being situated inside the outer contact, the three conductive contacts being electrically isolated from each other and wired to a tamper detection circuitry; wherein on releasing of the split case the outer member makes electrical contact with the outer conductive contact of the circuit board, meanwhile the intermediate and inner actuator members do not respectively make contact with the intermediate and inner conductive contacts of the circuit board; wherein the end of the inner actuator member covered with conductive material projects further than the end of the intermediate actuator member covered with conductive material in such a way that: in an assembled disposition the inner actuator member contacts with the inner conductive contact of the circuit board, the outer actuator member contacts with the outer conductive contact of the circuit board, and the conductive surface of the intermediate actuator member is at a distance from the intermediate conductive contact of the circuit board; and the intermediate actuator member only contacts the intermediate conductive contact of the circuit board when the tamper switch supports a pressure superior to the pressure supported in assembled disposition; wherein the tamper detection circuitry triggers a tamper responsive mechanism if: the electrical connection created by the tamper switch in assembled disposition between the outer and inner conductive contacts of the circuit board is broken, or there is a short-circuit between the intermediate conductive contact and the inner or the outer conductive contacts of the circuit board.