Patent ID: 6300606
Filing Date: 2001-10-09
Classification: H05B

Abstract:
A method for detecting a boil dry condition of a cooking utensil or vessel placed on a cooking zone of a glass-ceramic cooking surface of a cooking unit over an associated heating element for heating the cooking zone and the cooking utensil or vessel place thereof, said associated heating element having an energy input that is adjusted by means of a heating element power control device including means to measure the temperature in the cooking zone or a derivated quantity thereof (temperature signal) and including a temperature limiting protective device with an adjustable shutoff temperature for limiting the energy input and the temperature, said method of detecting said boil dry condition comprising the steps ofa) measuring temperatures of said cooking zone to obtain respective measured temperature signal values at corresponding times;b) comparing the respective measured temperature signal values with the shutoff temperature;c) when the respective measured temperature signal values are outside of a predetermined temperature range at the shutoff temperature, calculating respective first and second differential quotients of said temperature signal values with respect to time and registering an operation of the power control deviced) when said respective first and second differential quotients are positive and when said heating element power control device has not been operated within a predetermined time interval to increase the energy input to the heating element, generating a signal indicating that said boil dry condition has been detected.