Interlock circuitry for microwave oven

Claim 1

Safety and interlock circuitry for use with a microwave oven having a door ad a source of microwave energy comprising; an input terminal for receiving electrical power, means for initially establishing a first circuit condition when said door is opened including first and second switch means, said first and second switch means being coupled from said input terminal and responsive to said door for each assuming a first position when said door is open and a second position when said door is closed, said first and second switch means being arranged when said door is open to establish the first circuit condition when both said first and second switch means are in their first position, means for coupling electron heating power from said input terminal to said microwave energy source in response to said first circuit condition, means for thereafter setting a second circuit condition for a preselected cooking time interval when both said door is closed and said first circuit condition is established, and means for coupling energy from said input terminal to said microwave energy source to produce microwave radiation therefrom in response to said second condition, whereby the malfunction of at least one of said first and second switch means so that either stays in its second position prevents setting of said first circuit condition thereby indicating a fault condition of said switch means.