Method and apparatus for uniform heating in a microwave oven
AssigneeWhirlpool Corporation
InventorsPer Törngren, Ulf Nordh, Håkan Carlsson, Roland Ekinge
Life of this patent
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Abstract
A microwave oven and a method for heating a load which is placed therein. According to the invention a predetermined mode in the cavity of a microwave oven is fed by means of an associated feeding port which is arranged to feed essentially the intended mode only, the feeding of a mode other than the intended, predetermined mode being essentially prevented.
Claims20
A microwave oven comprising a cavity that is defined by an enclosing surface and adapted to receive a load to be heated, and a microwave source which is connected to the cavity for feeding microwaves to the cavity, which cavity is provided with at least two feeding ports wherein the cavity is designed to support at least two modes which are separately feedable through at least a respective feeding port and the separately feedable modes exhibits essentially non-overlapping heating patterns, and each one of the feeding ports is arranged to feed energy to a respective predetermined mode in the cavity, while feeding of energy to a mode other than the predetermined associated mode is essentially prevented, the feeding ports being placed at such a location that mainly one single mode is feedable by means of each feeding port and a transmission line in the form of a stripline or a microstrip, wherein the transmission line has a slot in its ground plane at a location that at least partly overlaps the feeding port at the same time as the transmission line exhibits a maximum current at the slot, whereby the magnetic field in the transmission line is let into the cavity and, thus, feeds energy to it.
A method for heating by means of energy in the form of microwaves, a load in the cavity of a microwave oven, wherein a first feeding port feeds energy to a first predetermined mode in the cavity, and a second feeding port feeds energy to a second predetermined mode in the cavity in such a manner that the first mode is essentially unaffected by the energy which is fed from the second feeding port, and the second mode is essentially unaffected by the energy which is fed from the first feeding port, wherein the first and the second feeding port sequentially feeds microwaves to the cavity in such a manner that only one of the first and second feeding port feeds energy into the cavity at any one instant, wherein the modes have essentially non-overlapping heating patterns, whereby a first mode provides heating of mainly a first subset of the load and a second mode provides heating of mainly a second subset of the load, the subsets being essentially non-overlapping, wherein reflected microwave power from at least one of the feeding ports is measured, and wherein the result of the measurement is used for controlling the feeding of microwaves to the cavity.
Dependencies are inferred from the claim text.