Patent ID: 6348677
Filing Date: 2002-02-19
Classification: H05B

Abstract:
Sensor circuit for the detection of a metal pan on a glass ceramic cooker hob provided with various independent heaters, comprising:a respective sensor loop extended over the area of each heater, a circuit part for generating a single high-frequency current applied to all the sensor loops by way of at least one supply cable, each loop generating a magnetic field of the same frequency affected by the proximity of a pan on the heater, a microprocessor, which supplies a pulse train to the circuit part for the generation of said frequency of the current, a circuit part for measuring and evaluating the resultant voltage of said current and of said magnetic field at the ends of each sensor loop, depending on the area of the sensor loop covered by the pan on each heater, said circuit for measuring and evaluating comprising a selector circuit which commutes and separates said voltage signals governed by the microprocessor and, a circuit part for the amplification and demodulation of said voltage signals, which compares each demodulated voltage signal with a predetermined reference voltage value relative to an appropriated pan diameter for each heater, a circuit part for regulating the power of each one of the heaters, depending on the result of said comparison of each voltage signal with said reference voltage.