Microwave ovens with programmable control

Claim 1

A microwave oven comprising: a casing; a heating chamber provided in the casing; a door provided at an opening of the heating chamber; a magnetron for supplying a microwave energy to the heating chamber; a source circuit for energizing the magnetron; key means provided at the front panel of the casing and including numeral keys, function keys including a time key for setting or changing at least a selected cooking time, a temperature key for setting or changing selected temperature in a cooking operation, a power level key for setting or changing power levels which control cooking speed, a "heat & hold" key for setting a temperature level to be held for a selected time period, a memory key for selecting more than one stage of cooking operations prior to starting the oven so that cooking automatically progresses from one stage to the next, a start key for starting a selected cooking operation and a clear key for stopping oven operation and clearing a prior selected cooking operation; digital control logic means for encoding an operation condition determined in response to the operation of the function keys and numeral keys in said key means selectively operated by users, which comprise a key circuit and an input control unit including a key encoder for encoding an output signal of said key circuit and a key ROM supplied with the output of said key encoder; memory means having at least three memory areas for memorizing the encoded operation condition regarding the time, temperature and power level encoded by the digital control logic means, respectively; display means for displaying digitally the operation condition encoded by said digital control logic means; operation means for initiating an operation in response to the operation of said start key to energize said magnetron based on the operation condition memorized in said memory means, which includes an oscillator, a timing signal generator supplied with the output of said oscillator, and a main ROM connected to memorize a predetermined program, a status register connected to said key ROM and said main ROM, a first display control unit connected to receive the output of said status register, a second display control unit connected to said memory means, a display circuit for supplying the outputs of said first and second display control units to said display means; said second display control circuit comprising a control gate with controls interchange of data between said key ROM and said main ROM, a display register and a half adder which are supplied with the output of said control gate, a latch circuit supplied with the output of said display register, and a segment decoder for decoding the output of said latch circuit; and control means for controlling said source circuit in response to an output signal of said operation means.