Operating switch of microwave oven and control circuit thereof

Claim 1

A microwave oven, comprising: a housing forming a cooking chamber; a magnetron for generating cooking pulses for cooking food in said cooking chamber; and a control mechanism connected to said magnetron for operating said magnetron, comprising: a first switch mounted on said housing for setting a first cooking function, said first switch including: a first shaft rotatable about an axis and axially movable inwardly along said axis against a spring bias, a manually rotatable first knob affixed to an outer end of said first shaft and exposed on an outer surface of said housing, a rotatable electrical contact structure rotatable with said first shaft, and a stationary electrical contact structure affixed to said housing and engageable with said rotatable contact structure, one of said rotatable and stationary contact structures being flexible to permit electric contact to be maintained while said shaft is being inwardly moved along said axis; a second switch mounted on said housing for setting a second cooking function; said switch including a second shaft rotatable about said axis and telescopingly arranged around said first shaft to permit said first shaft to be moved axially relative thereto, and a manually rotatable second knob affixed to said second shaft and exposed on an outer surface of said housing; and a third switch mounted inside of said housing and including an element arranged to be depressed along said axis by said first shaft when said first shaft is inwardly moved along said axis; said first knob being of smaller cross section than said second knob and normally extending outwardly past said second knob along said axis, said first knob being depressible inwardly along said axis to move said first shaft axially inwardly, said first knob being telescopingly insertable into said second knob when inwardly depressed.