Detecting open circuits in thermo module array

摘要

Thermo modules 11, for cooling semiconductor wafers, are connected in parallel rows 10a. Each row is coupled to a voltage detection circuit 12 connected between a supply terminal 17a and an intermediate terminal 18. An open circuit at any module will cause a change in voltage such that an optical switching circuit 20 activates an audible or visual alarm circuit 14. A thermostat 30 also responds to an abnormal temperature to actuate the alarm circuit. Modifications may be made to enable the system to operate with pulse width modulation control of the thermo modules.