Power control for appliance having a glass ceramic cooking surface

A power control system for a household cooking appliance of the type having a glass ceramic cooking surface for supporting loads to be heated and at least one radiant heating unit disposed beneath the glass ceramic cooking surface to heat loads supported on the cooking surface, said power control system comprising:

• temperature sensing means for sensing the temperature of the underside of the glass ceramic support surface approximate the heating unit;
• user actuable input selection means for enabling the user to select one of a plurality of power settings for the heating unit;
• at least one of said plurality of power settings having associated with it predetermined maximum and minimum reference temperatures defining a temperature band representative of the steady state temperature range of the underside of the glass ceramic support surface proximate the heating unit when heating loads at that power setting;
• and
• power control means responsive to the input selection means for operating the heating unit at a predetermined steady state power level corresponding to the user selected power setting including means responsive to said temperature sensing means operative to operate the heating unit at a power level higher than the power level corresponding to the user selected power setting when the sensed glass ceramic support surface temperature is less than said minimum reference temperature and to operate the heating unit at a power level less than the power level corresponding to the user selected power setting when the sensed glass ceramic support surface temperature is higher than the said maximum reference temperature to reach steady state operating conditions associated with the newly selected power setting.

A method of controlling the output power of a heating element in a cooking appliance of the type in which the radiant heating element is disposed beneath a glass ceramic cooking surface for supporting loads to be heated by the element, said method comprising the steps of:

• sensing the temperature of the underside of the glass ceramic support surface proximate the heating unit;
• comparing the sensed temperature to a predetermined temperature range associated with the selected power setting;
• operating the heating unit at a power level higher than the steady state power level associated with the selected power setting with the sensed glass temperature is less than the predetermined temperature range;
• applying a power level to the heating unit lower than the steady state power level associated with the selected power setting when the sensed glass temperature is greater than the predetermined range;
• and
• applying the steady state power level associated with the user selected power setting to the heating unit when the sensed temperature lies within the predetermined range associated with the selected power setting.