Tamper sensing method and apparatus

摘要

A tamper sensing circuit is provided for an electrical device wherein an enclosure may be opened to access data by a user that does not possess the ability to achieve normal access by satisfying data security measures such as use of a password. A screw used to secure enclosure halves together is connected by a conductive coating at the enclosure member surface into which the screw is threaded to connect a tamper sensing circuit to the device ground potential. A tamper sensing circuit output node is maintained at the circuit ground potential as long as the screw is in electrical contact with the enclosure conductive coating. When the screw is disengaged from the enclosure member threaded opening, the output node is no longer grounded and rises to a supplied electrical potential indicating tampering and enabling appropriate corrective action. The conductive coating on the enclosure member which connects the screw to circuit ground may be applied or may already be present to suppress electromagnetic interference.