Patent ID: 8143559

Claim:
In a heating pad having a heating element, the improvement comprising: a control circuit including a central processing unit operatively connected to the heating element by a switch, the central processing unit supplying current to the heating element and controlling movement of the switch between a first closed position wherein the central processing unit is electrically coupled to the heating element and an open position wherein central processing unit is isolated from the heating element an isolation device operatively connecting the control circuit to a power source; and a comparator operatively connected to the isolation device and interconnecting the heating element to the central processing unit, the comparator providing a signal to the central processing unit corresponding to a temperature of the heating element; wherein: the central processing unit adjusts the current supplied to the heating element to maintain the heating element at a desired temperature; the central processing unit moves the switch to the open position in response to the heating element exceeding a first temperature limit; and the isolation device isolating the control circuit from the power source in response to the heating element exceeding a second temperature limit.