| 摘要 |
PURPOSE:To securely judge whether a bowl is existing or not even if the electric source voltage varies by detecting the inverted value of the DC level rectified from AC and the zero-cross point of AC and inputting the lag pulses to a judging means. CONSTITUTION:DC rectified from a DC source 6 is made flat and smooth by a filter 8. The high-frequency waves generated by putting on and off of the flat DC by the use of a switching element 11 is actuated on a resonance circuit 10 composed of a heating coil 3 and a resonance condenser 9 to induction-heat the bottom of bowl 2. The zero-cross point of AC is detected by a ZVP generator 14 and inputted in a judging means 15 after a lag time 17 of a specified interval. Also, the output level of DC voltage is inverted 13 to input into the judging means 15. The bowl is judged from both inputs by the judging means 15 as to whether the bowl is existing or not. If a bowl is existing, the switching element 11 is put on and off through a controller 12 and if it is not existing, it is kept to be put off. In this way, the judgement as to whether a bowl is existing or not can be securely done, even if the electric source voltage varies. |
