| 摘要 |
PURPOSE:To improve heat efficiency by providing an electrode for transferring a signal when an object to be heated is placed on a base, a circuit for determining the location or the size of the object by means of variation of the signal and a controller for changing heating area of a heating coil in response to the output of the circuit. CONSTITUTION:An electrode 10 is placed under a base plate 9 at the location where is almost the center of a heating coil 1. Electrodes 11a, 11b, 12a, 12b, 13a and 13b are disposed at the periphery of the electrode 10. Pulse signals are applied to the electrode 10 from a pulse generator 14. The pulse signals from the electrode 10 are received by the electrodes and a reception signal is supplied to a judging circuit 15. A signal from the judging circuit 15 is received by a heating coil controller 16 to change heating area of the heating coil 1. The heating area of the heating coil 1 is canceled to be non-heated state so as to inhibit heating under low heating efficiency when an object to be heated is displaced against the upper face of the heating coil 1. |
