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US 4,786,773 AGranted
Systems and methods for determining doneness of microwave-heated bodies
AssigneeAlcan International Limited
InventorRichard M. Keefer
Life of this patent
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AssigneeAlcan International Limited
InventorRichard M. Keefer
Estimating the term…
For determining doneness of a body of food or other material heated in a microwave oven, a device including an indicator that changes appearance at a predetermined temperature, mounted on an outwardly-facing major surface of a thin-gauge metal element which is disposed in the oven so as to receive heat from the body. The metal element may be mounted on the lid or other wall of a container holding the body in the oven; the lid may be microwave-transmissive and may hold the metal element spaced above the body. The indicator may include a substance that melts at the predetemined temperature to reveal an underlying color or pattern on the metal element surface. In use, the device is placed in a microwave oven together with the body and is observed visually, for detection of the change of appearance, which occurs when the indicator reaches a temperature corresponding to adequate doneness of the body.
A system for indicating doneness of a body of material heated by microwave energy, comprising a thin electrically conductive metal element having first and second opposed extended surfaces;
A method of determining the doneness of a body of material heated by microwave energy comprising placing, in a microwave oven for heating, said body together with a thin electrically conductive metal element having first and second opposed extended surfaces and bearing on its first surface indicator means for producing a visually observable change of appearance upon being heated to a predetermined elevated temperature or maintained at such temperature for a predetermined time, said element being supported in the oven, in substantially fixed relation to and externally of the body with the indicator means positioned to be externally visible, such that the element receives heat from the body by conduction and/or radiation when the body is heated, the dimensions of the element and the disposition of the indicator means thereon being such as substantially to shield the indicator means from temperature-elevating irradiation by microwave energy;
Dependencies are inferred from the claim text.