IMPROVED TOUCH CONTROL ARRANGEMENT FOR AN ELECTRICAL APPLIANCE

摘要

An improved touch control circuit arrangement for electrical appliances having one or more electrical loads to be individually controlled in accordance with user selected power settings. Each load has associated with it a power relay for coupling the load to an external power supply. Each relay is coupled to a latch circuit operative when set to close the relay and when reset to open the relay. The touch control arrangement includes a matrix array of touch keys having an input line for each row and an output line for each column to facilitate the multiplexing of touch key information to the microprocessor in conventional fashion. However, the OFF keys are continuously enabled and coupled to the reset input of the associated latch circuit such that user actuation of an OFF key directly resets the relay control circuit for the associated load. This enables the user to turn off the load independent of the microprocessor. Each ON key is coupled to the set input of its associated latch circuit such that both actuation of the ON key and an enable signal from the microprocessor are required to set the latch circuit. This prevents the inadvertent closure of the relays such as might otherwise result from microprocessor failure.