Chemetron

Donald G Moore

William H Kuntz

A control circuit is provided for a microwave oven in which a crystal rectifier is responsive to variations in the level of the electromagnetic field within the oven cavity when items of different energy absorption or reflection characteristics are placed in the oven. The electric current developed by the crystal is employed to generate a ramp type electrical signal which is compared with a fixed reference voltage to control the termination of microwave power to the oven. Compensation for the nonlinear relationship between crystal current and the level of the electromagnetic field within the oven is provided. In addition, compensation for the initial temperature of the food item which is placed in the oven is provided. Provision is also made for physically shaping and/or partially shielding individual food items relative to a reference food item so that the same triggering level of the control circuit is effective to bring all of the food items to the desired condition at different time intervals depending upon the field strength level within the oven which is established when the food item is placed therein.

Method of automatically rethermalizing previously prepared food for

Method of preparing food items for subsequent rethermalization in a

Apparatus for providing temperature equalization cycles for a microwave

An electromagnetic oven is provided with a control system comprising a ferrite sensor located within the oven, a magnetic property detector coupled to the sensor, and control means responsive to signals from the detector. The sensor is positioned on a tray together with the items to be heated and this assembly is preferably cooled to a uniform low temperature before the tray is placed in the oven. The sensor is thus subjected to the same thermal environment as the items on the tray so that when the tray is placed in the oven the time required for the sensor to reach its Curie point and shut off the oven is dependent upon the thermal 'history' of the items on the tray.

Method for automatically heating variable numbers and sizes of food

An adjusting and tuning arrangement is provided in a microwave oven to adjust the energy distribution to various areas of the oven cavity such as defined areas or the area of a sensor assembly on a tray inserted in the oven and also to balance the distribution of energy between the load articles on the tray and the sensor assembly or between various load articles. Two electrically conductive planar elements are positioned inside and project into the cavity to accomplish the tuning. The planar elements are arranged one above the other at predetermined angular orientations and are also each independently rotatable about one edge.

Microwave oven adjusting (energy distribution) and tuning arrangement

A tray for use in an electromagnetic oven supplying differing quantities of electromagnetic energy to a variety of load items which are located within the oven cavity. A food or material bearing tray inserted into the oven positions a conductive energy shield to interfit with elements on the tray to isolate selected items from the electromagnetic energy. The conductive shield cooperates with a shaped interior wall of the oven to provide a desired non-uniform distribution of electromagnetic energy over those regions of the tray which are not shielded. An improved sensor assembly located on the tray controls an assembly in the oven to inhibit and terminate the heat cycle as desired. The tray further includes conductive base strips with upstanding flange members defining the shielded region with the base strips recessed into the surface of the tray to prevent energy from entering into this shielded area. Where the upstanding flanges meet the base strip, a molded lip is provided in the tray surface to form a seal preventing food and miscellaneous other materials from accumulating or entering this area. The tray is provided with extending portions or feet located at the edges of the tray that contact supporting rails in a storage rack upon insertion and removal. The feet facilitate handling of the loaded trays when stacked and maintain the trays in a nearly level manner during insertion and removal. The feet have a surface designed to cooperate with the contacting surfaces of the storage racks.

Sensor and tray arrangement

A method and apparatus for inspecting the location and orientation of a sensor assembly in a tray-sensor arrangement adapted to be placed in a microwave oven. The sensor assembly which includes a ferromagnetic element that absorbs energy when placed in the oven and changes its characteristics when a predetermined amount of energy has been absorbed, is tested in the completely assembled tray by accurately positioning the tray in predetermined relation to an oscillating circuit whose operating frequency is responsive to the presence of the ferromagnetic sensing element. The output frequency of the oscillating circuit indicates whether or not the sensor assembly has been properly assembled and positioned on the tray. The oscillator circuit includes a frequency determining element which produces a distinctly different frequency when the sensor is not properly positioned in the assembly or is omitted from the assembly. The output frequency of the oscillating circuit is supplied to an electronic meter such as a counter or frequency meter to display the operating frequency, or acceptable range of frequencies, to provide an indication of the acceptability of the sensor assembly and tray.

Method and apparatus for sensor assembly inspection

Electronic microwave oven control system and method of preparing food

A plurality of food items are assembled on a tray together with a ferromagnetic mass which is positioned at a predetermined location on the tray and is arranged to change from a ferromagnetic to a paramagnetic state when a predetermined quantity of microwave energy has been received thereby. The food items are held in predetermined positions relative to themselves and the ferromagnetic mass by means of a templet which acts as a retaining means for the food items.

Arrangement for simultaneously heating a plurality of comestible items

An electromagnetic oven is provided with a control system comprising a ferrite sensor located within the oven, a magnetic property detector coupled to the sensor, and control means responsive to signals from the detector.

Sensor-detector assembly for microwave oven

A system for thermally reconstituting plural item meals in an oven with a cavity to which electromagnetic energy is supplied uses differently shielded or unshielded food containers to partially control the energy received by each food item from the cavity so as to place all of the items in a condition for consumption in the same controllable time interval. A template carried on a tray positions the food items relative to each other and to the cavity so as to further control the energy distribution to the food items. An electromagnetic energy sampling sensor carried on the tray automatically terminates the heating cycle. In one oven control, the sensor carried on the tray is a magnetic or ferrite mass which controls a magnetically responsive switch mounted in the oven to initiate the heating cycle and which is heated to its Curie point when the food items are properly heated to release the switch and terminate the heating cycle. The described method of preparing the plural item meal on the tray includes the steps of positioning the food items on the tray to distribute between them the energy available in the cavity, repositioning the items to compensate for changed cavity energy distribution resulting from the first positioning of the items on the tray, and positioning the sensor on the tray such that it reaches its Curie point when all of the template located food components reach a condition suitable for consumption.

Method of heating comestibles

An electromagnetic oven supplies differing quantities of electromagnetic heating energy to a variety of load items or the like all of which are located within the oven cavity. In one embodiment, a food bearing tray has a first region substantially shielded from the electromagnetic heating energy by means of a conductive shield which cooperates with a shaped interior wall of the oven to provide a desired nonuniform distribution of electromagnetic energy over those regions of the tray which are not shielded. A much higher energy concentration is developed, for example, at a region near a distended wall so that a food item located in that region is heated to a higher temperature than other food items upon the tray and in other regions.

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Glencoe, IL, United States of America

Donald G Moore