Abstract: Refrigeration system control systems and methods for protecting a refrigerant motor/compressor, for example in an air conditioner, against conditions of excessive loading. The systems and methods of the invention recognize and distinguish between conditions of high operating load and insufficient condenser airflow, and take appropriate action for each. High operating load conditions are responded to by providing a motor/compressor cool-down interval, followed by a restart, so that an air conditioner remains operating at its maximum capacity, consistent with the field conditions. Insufficient condenser airflow conditions are responded to by eventually terminating operation of the motor/compressor until, for example, a service technician is called. Operation is based on a recognition that excessive loading conditions are manifested much sooner when the cause is insufficient condenser airflow than when the cause is a high operating load.

Abstract: Calibrated methods and systems for protecting refrigerant motor/compressors against overload and loss of refrigerant conditions, independent of compressor and system size, while avoiding the need for a plurality of sensors. The disclosed methods and systems are generic in the sense that they may be employed in a variety of different air conditioner or heat pump models of different sizes and capacities, without being specifically tailored for a particular model, although a factory calibration adjustment is required. The disclosed methods and systems sense loading on the compressor motor, and make control decisions based thereon. A permanent compressor motor reference loading is established when the refrigeration system has a known correct refrigerant charge and the motor/compressor has a known load. This is typically accomplished in the factory after a predetermined stabilization interval has elapsed following initial start up of the motor/compressor.

Abstract: An excitation system structurally compatible with a low profile streamlined microwave oven appliance configuration, comprising a generally planar antenna member disposed between the bottom wall and a support shelf centered laterally in the oven cavity and extending over a substantial portion of the bottom wall. An open peripheral region is defined between the front, back, side and bottom oven cavity walls and the peripheral edge of the antenna member. A plurality of radiating apertures are formed in the antenna member and arranged in a triangular fashion such that straight lines connecting the centers of any three closely adjacent apertures intersect to define an equilateral triangle.

Abstract: An improved electronic power control arrangement for a cooking appliance equipped with an automatic surface unit operable in a Fry Mode to heat a utensil to a steady state temperature range corresponding to the temperature setting selected by the user. Two error signals are established by the electronic controller as functions of the difference between the user selected temperature and the sensed utensil temperature. The controller controls energization of the automatic surface unit as a function of the first error signal during the heat-up phase to rapidly bring the sensed utensil temperature to the selected steady state temperature range and as a function of the second relatively larger error signal during operation in the steady state phase to rapidly return the sensed utensil temperature to the selected range if it should drop below the selected range during steady state operation.

Abstract: An automatic boil point prediction arrangement for a cooking appliance having an automatic surface unit, in which the surface unit is operated at a predetermined power level at least until the sensed utensil temperature rises to a predetermined threshold temperature. The heat up time required for the sensed utensil temperature to reach the threshold temperature is measured and an estimate of the additional completion time required for the water in the utensil to reach its boil point is established as a function of the heat-up time. A signal is generated upon expiration of this completion time to inform the user that boiling has begun.

Abstract: Disclosed are apparatus and methods for controlling the defrosting of the outdoor heat exchange coil of a heat pump. In general, the disclosed apparatus and methods use the differencee between the outdoor heat exchanger and the outdoor ambient temperature to determine when to initiate a defrosting operation. Only a single sensor is employed, this single sensor being positioned at least proximate the outdoor heat exchanger such that the sensor responds to ambient temperature when the heat pump is first started and the heat exchanger is free of frost, and such that the sensnor becomes surrounded with frost as frost builds up on the heat exchanger during operation. At the beginning of a run the sensor is employed to read the ambient temperature, which is memorized. As frost builds, the sensor begins to reflect the temperature of the heat exchanger as the sensor becomes increasingly insulated by the frost from the surrounding air.

Abstract: Disclosed are refrigeration system control systems and methods for compressor motor protection and defrost control. The disclosed systems and methods are generic in the sense that they are self-calibrating and so may be employed in a variety of different air conditioner or heat pump models of different sizes and capacities, without being specifically tailored for a particular model. The disclosed systems and methods sense loading on the compressor and evaporator fan motors, preferably by sensing the voltage across the capacitor-run winding of an AC induction motor and normalizing with respect to line voltage. The self-calibrating capability is implemented by taking advantage of the changing loads as a function of time on both the compressor and fan motors during both normal and abnormal operation of a refrigeration system. In overview, a reference value of motor loading is established for each motor at certain times during an ON cycle.

Abstract: An improved excitation system for a microwave oven employing a circular rotating disk antenna configured to radiate peripherally from its outermost edge to provide backgound radiation in the oven cavity. Primary microwave energy radiation is emitted from a pair of transverse radiating slots formed in the disk antenna. A first slot is positioned radially outwardly relative to the second slot. The first slot alternately functions as a relatively strongly coupled series and shunt radiating slot and the second slot concurrently alternately functions as a moderately coupled shunt and series slot with each quarter revolution of the disk antenna. Both slots are louvered for improved coupling to the load being heated in the cavity.

Abstract: A power control arrangement for a cooking appliance equipped with an automatic surface unit, the energization of which under normal operating conditions is controlled in accordance with a closed loop control strategy as a function of the sensed utensil temperature and the user selected temperature setting. The control arrangement is operative to detect a failure of the sensor circuit for the automatic surface unit and operative upon detection of such a failure to control energization of the surface unit in accordance with an open loop control strategy only as a function of the user selected setting. A user discernible signal is provided alerting the user to the sensor circuit failure. By this arrangement the user is informed of the malfunction and is able to use the automatic surface unit as a standard surface unit until the failure can be repaired.

Abstract: A power control arrangement particularly applicable to a multiple surface unit cooking appliance providing a griddle heated by the combination of a standard surface unit and an automatic surface unit. Temperature information for the standard surface unit is provided by a counter implemented in the controller which is incremented and decremented at rates which cause the count to approximately track the griddle temperature proximate the surface unit.

Abstract: A power control and diagnostic arrangement illustratively embodied in an electric range having multiple surface heating units which are selectively coupled to an AC power supply by commutated relay switching circuitry. The commutated relay switching circuitry includes two switching networks. Each network includes a diode commutated master relay serially connected to a pair of pilot relays. Each pilot relay is serially connected to one of the surface units. Timing and control circuitry periodically interrupts operation of the power circuit in a normal mode to operate in a diagnostic mode. In the diagnostic mode the relays are switched in a predetermined sequence to test for a short circuit failure of the master relays or commutated diodes, an open circuit failure of the diodes, an open circuit failure of the master relays, a short circuit failure of the pilot relays and an open circuit failure of any individual pilot relay.

Abstract: 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.

Abstract: A test initiating device connectible to the power cord of an electronically controlled appliance for initiating appliance operation in either a normal operating mode or a self-diagnostic test mode. When so connected the test device is selectively switchable between a first state in which the device is operative to suppress power signal half cycles of one polarity and a second state in which the power signal from the power supply is coupled to the appliance control circuit essentially unchanged. The appliance control circuit includes circuitry operative to generate interrupt pulses marking the pulsations of the power signal applied to the control circuit. Logic circuitry monitors the pulse rate of these interrupt pulses.

Abstract: A duty cycle power control circuit for a magnetron including a power transformer having a primary winding, a secondary anode winding for supplying anode voltage to the magnetron and a secondary filament winding for energizing the filament of the magnetron. In the illustrative embodiment the power transformer primary winding comprises a main winding and a serially connected standby winding. Duty cycle controlled switching devices are effective in a standby state to connect the main winding in series with the standby winding across an external power supply and are effective in the power on state to disconnect the standby winding and connect the main winding directly across the external power supply.

Abstract: Apparatus and method for detecting a failure in an automatic defrost system for a refrigerator. A current sensor means monitors the current supplied to the defrost heater and generates an "on" signal when current is sensed in the defrost heater circuit. A microprocessor determines the "off" time, that is the time between successive "on" signals, and compares this time to a predetermined reference time longer than the normal "off" time. A user discernible signal is generated upon detection of an "off" time greater than the reference time, signifying to the user that the defrost system is not operating properly, and corrective action may be necessary.

Abstract: An improved over-temperature warning system for a refrigerator/freezer appliance comprises a temperature sensor responsive to the temperature in the freezer compartment of the appliance and logic circuitry responsive to the sensor operative to detect a first over-temperature condition when the sensed temperature is greater than a first reference temperature and less than a second reference temperature and to detect a second over-temperature condition when the sensed temperature is greater than the second reference temperature. The logic circuitry times the duration of the first and second over-temperature conditions and provides a user discernible warning signal when the first condition exceeds a first predetermined time period or when the second over-temperature condition exceeds a second predetermined time period shorter than the first time period.

Abstract: A display arrangement for a cooking appliance using a heater energy counter based power control system which provides a user discernible signal signifying that the appliance heating element has reached the steady state temperature associated with the user selected power setting. The heater energy counter is selectively incremented or decremented at a rate in accordance with the selected power setting such that the count rate is approximately proportional to the rate of increase or decrease respectively of the temperature of the heating element for the power setting selected. When so incremented and decremented the count of the counter provides an approximation of the actual heating element temperature. The display arrangement generates a user discernible signal when the count of the heater energy counter indicates that the associated heating element has approximately reached the steady state temperature for the selected power setting.

Abstract: Apparatus and a method for detecting fault conditions in an automatic icemaker system of the type having an ice forming mold and an electric motor and mold heater which are energized during ice cube ejection cycles. A current sensor monitors current in the icemaker motor and mold heater circuit and generates an "on" signal when current is detected. A microprocessor measures the duration of the "on" signals and the elapsed time between successive of "on" signals. A diagnostic code is displayed signifying a fault condition in the icemaker circuit when the time between successive "on" signals is less than the normal time required to freeze cubes or the duration of an "on" cycle exceeds the normal ejection time.

Abstract: Method and apparatus for testing microwave oven cavities during the oven fabrication process after the cavity forming operation is complete. The cavity to be tested is positioned front frame resting on a test plate containing a non-protruding microwave power source and choke/ferrite attenuators. The power source radiates into the interior of the cavity and microwave leakage is measured at the cavity exterior.

Abstract: A capacitive attenuator type touch switch cell arrangement employs a touch responsive pad or electrode and a receiver electrode of comparable surface area on opposing surfaces of a dielectric substrate for capacitive coupling therebetween, which capacitive coupling is alterable by the human touching of or proximate to the touch pad. A scan signal is coupled from signal generating circuitry to the touch responsive pad by a separate transmitting capacitor. Signal detection circuitry senses the signal coupled to the receiver electrode to detect attenuation of the coupled signal signifying the touching of the touch pad. The use of a separate capacitor to provide the transmitting capacitance reduces the touch pad area requirement, thereby permitting closer spacing of touch switch cells for greater switch density on a control panel.