Induction heating apparatus having timing means responsive to temporary removal of cooking implement

Claim 1

An induction heating apparatus comprising; a d.c. power supply circuit, a static power inverter connected to the d.c. power supply circuit for producing a high-frequency oscillating current, an induction heating unit having a plurality of heater coils connected to the static power inverter for producing a commutating magnetic field around each of the heater coils, capacitors respectively connected in series with the heater coils, a plurality of first switches each connected between the static power inverter and each of the heater coils, a plurality of second switches each provided in the vicinity of each of the plurality of the heater coils and responsive to removal of a load to be heated from its corresponding heater coil to be rendered open, a plurality of timing circuits respectively connected in series with the second switches, each of the timing circuits producing an output signal in response to a condition in which the corresponding one of the second switches is kept open for a predetermined period of time, a switch control circuit having input terminals connected to the timing circuits, being linked with the first switches through respective linkage linking the first switches to the switch control circuit, and being actuated by the output signal from each of the timing circuits so that the first switch associated with the timing circuit delivering the output signal is rendered open, and a plurality of third switches connected in series and provided between junctions defined by the capacitors and the heater coils, each of the third switches being linked to the switch control circuit through respective said linkages for being rendered open when the first switch associated with the timing circuit delivering the output signal is rendered open by means of the switch control circuit.