Abstract: A touch control arrangement which employs a touch panel comprising a plurality of touch keys and a network of electrically connected capacitive elements; an oscillator which incorporates the network of capacitive elements in its timing circuit; and a microprocessor coupled to the output of the oscillator and operative to control various appliance operating components as determined by the frequency of the oscillator output signal. The keys of the touch panel are operatively coupled to the network of capacitive elements such that actuation of a key or pad by the user changes the equivalent capacitance of the timing circuit causing the oscillator a generate a control signal at the frequency associated with the actuated key.

Abstract: Method and apparatus for detecting the boiling point of liquids being heated by a cooking appliance and automatically reducing the output power of the heat source, once the boiling point has been reached, to a level which will sustain a desired evaporation rate, by measuring the initial weight of the liquid to be heated; energizing the heat source at a predetermined power level, periodically measuring the weight of the liquid as the heating process continues; computing the rate of change of the weight of the liquid, and reducing the power level of the heat source to a lower power level when the computed rate of change exceeds a reference rate and increasing the power level when the computed rate of change is less than the reference rate once the boiling point has been reached. The first occurrence of a measured weight decrease greater than the reference rate signifies that the boiling point of the liquid has been reached.

Abstract: A weight measuring arrangement for a cooking appliance in which a surface heating unit also functions as a scale platform. A three arm cantilever beam supports the heating unit. A set of four strain gages measures the strain of the three support arms, with one gage each being attached to each of two identical support arms and the remaining two gages being attached to the third arm, which arms are constructed such that the strain measured by each of the gages secured to the third arm is one-half that measured by each of the gages secured to the two identical arms when the ends of all three arms are equally deflected by a utensil placed on the surface unit for heating. The gages are electrically connected in a Wheatstone bridge network such that the output voltage from the bridge network is proportional to the weight of the load carried on the surface unit. This arrangement can be used to monitor the weight of the items being heated, throughout the heating period.

Abstract: An improved phase shifting device for varying the phase of the standing wave in a hollow rectangular waveguide is provided which is particularly applicable to microwave cooking appliances. A metallic septum is constructed at the end of the waveguide remote from the microwave source which extends inwardly into the waveguide from the adjacent waveguide end wall parallel to the narrow walls of the waveguide and electrically connects the broad walls of the waveguide, thereby dividing the waveguide into two sub-waveguides, each of which exhibits a cut-off characteristic at the operating frequency. The leading edge of the septum provides a short circuit termination reference point for the waveguide.

Abstract: Food thawing apparatus is disclosed specifically adapted for use in a refrigeration appliance. An enclosure having good thermal communication with surrounding environment is provided with a pair of planar electrodes defining a food thawing zone. One of the electrodes is movable to allow insertion of a frozen food load. A high frequency, relatively low wattage power supply provides uniform energy distribution throughout the feed load for gentle heating (thawing). Frequencies of 27.12 MHz or 43 MHz are suggested along with a power level of 100 watts or below, preferably 35-80 watts.

Abstract: A utensil detection arrangement for an induction heating apparatus which provides a signal indicative of an off-center position of a cooking utensil supported on a cooking surface which overlies an induction heating coil. The detection arrangement comprises a conductive loop configuration located intermediate the heating coil and the cooking utensil in a plane parallel to the plane of the cooking surface and concentric with respect to the axis of the coil. The conductive loop is linked with the magnetic flux generated by the induction heating coil, which flux changes as a result of the position of a cooking utensil with respect to the axis of the coil and thereby generates a signal which changes in amplitude as a result of utensil position.

Abstract: A microwave oven cavity excitation system for promoting time-averaged uniformity of microwave energy distribution within the cooking cavity. Circularly-polarized microwave energy is radiated from a feed waveguide into an adjacent cooking cavity by means of an aperture, such as an X-slot, in the feed waveguide properly electrically located laterally within the feed waveguide so as to nominally radiate an electric field having circular polarization properties and, overall, shaped as an approximate hemisphere. A cross-sectional slice of the field, for example in the plane of the food supported on a conventionally-located shelf, is circular in shape.

Abstract: A microwave oven including a resonant cavity humidity sensor operated by microwave energy sampled from the power produced for the cooking operation. The arrangement provides for a flow of moist air from the cooking cavity through an active resonant chamber and a flow of dry air from the atmosphere through a passive resonant chamber. Control circuitry governs the microwave energy flow into the cooking cavity in response to moisture conditions in the cavity so indicated by the sensor.

Abstract: Food thawing apparatus is disclosed specifically adapted for use in a refrigeration appliance. An enclosure having good thermal communication with surrounding environment is provided with a pair of planar electrodes defining a food thawing zone. One of the electrodes is movable to allow insertion of a frozen food load. A high frequency, relatively low wattage power supply provides uniform energy distribution throughout the food load for gentle heating (thawing). Frequencies of 27.12 MHz or 43 MHz are suggested along with a power level of 100 watts or below, preferably 35-80 watts.

Abstract: A microwave oven for cooking food by means of both microwave energy and convective heating which includes within it, a substantially closed microwave transparent container into which food to be cooked is placed, a heating element for convectively heating air, and means for blowing air past the heating element and into the container.

Abstract: A dielectric heating arrangement for drying wide wet webs of material is provided in which a rotatable drum structure is provided for supporting the web on its periphery and moving it past a stationary set of dielectric heating electrodes of the stray field type positioned close to the periphery of said drum over a substantial portion of the circumference thereof. The drum periphery comprises a series of closely spaced members which extend parallel to the axis of the drum, the outer edges of said members acting as the outer periphery of said drum on which the web is supported as it is moved past said electrodes.