Susceptors capable of balancing stress and effectiveness

Abstract

An outer portion of one or more layers of microwave interactive material, which is for becoming hot when exposed to microwave energy, is arranged in a manner that seeks to advantageously control heating, so that the outer portion of the microwave interactive material can safely be adjacent the periphery of a turntable tray. The turntable tray can be heated by the microwave interactive material so that a peak thermally induced stress occurs in the turntable tray at a position proximate the periphery of the tray. The layer(s) of microwave interactive material are configured in a manner so that the peak thermally induced stress is less than a predetermined amount.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims the benefit of U.S. Provisional Application No. 60 / 691,885, which was filed Jun. 17, 2005. The entire disclosure of U.S. Provisional Application No. 60 / 691,885, which was filed Jun. 17, 2005, is incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] The present invention generally relates to microwave energy interactive materials (“microwave interactive materials”) and, more specifically, to the shape of susceptors. [0003] Microwave ovens are frequently used to heat food. As a result, the number of food items and constructs (e.g., packages) available for use with a microwave oven is increasing. It is well known for such a construct to include a layer of microwave energy interactive material (“microwave interactive material”) that is for interacting with microwave energy in a manner that reduces, enhances or otherwise alters the effectiveness of a microwave oven. There are several types of micro...

AI Technical Summary

Benefits of technology

[0015] In accordance with an aspect of the present invention, the layer(s) of microwave interactive material are configured in a manner that seeks to restrict heating of the periphery of the turntable tray by the microwave interactive material.

[0017] In accordance with one embodiment of the present invention, the periphery of the layer of microwave interactive material is absent of acute corners (e.g., absent of a corner formed by edges that meet at an angle of 90 degrees or less). In contrast, the corners of the layer of microwave interactive material can be beveled (e.g. rounded, truncated, or the like) so that they seek to limit the peak thermally induced stress in the turntable tray.

[0018] The at least one layer of microwave interactive material can include first and second layers of microwave interactive material. For example, the first layer can be substantially continuous, whereas the second layer can be discontinuous (e.g., patterned), with the second layer being adjacent and extending outwardly from the periphery of at least a portion of the first layer. Per unit area, the second layer absorbs less microwave energy, and thereby becomes less hot, as compared to the first layer. This arrangement seeks to limit the peak thermally induced stress in the turntable tray.

[0021] More specifically, an example of an aspect of the present invention is the configuring of the periphery of one or more layers of microwave interactive material, which is for becoming hot when exposed to microwave energy, in a manner that seeks to advantageously control heating, so that the periphery of the microwave interactive material can typically safely be adjacent the periphery of a turntable tray.

Problems solved by technology

In particular, corners of the susceptor may be proximate the periphery of the turntable tray, and heat transferred from those corners of the susceptor to the turntable tray can lead to damaging thermally induced stress in the turntable tray, namely proximate the periphery of the turntable tray.

Even a relatively small susceptor that is sufficiently off-center on a relatively large turntable tray can cause the peak thermally induced stress to be disadvantageously located at, or proximate, the perimeter of the turntable tray.

It can be disadvantageous to have peak thermally induced stress that is located at, or proximate, the perimeters of turntable trays.

For example, fractures and cracks tend to initiate at the edges of turntable trays because stress-enhancing defects, such as chips, are common at the edges of turntable trays.

Bringing stress-enhancing defects and the peak thermally induced stresses together increases the possibility of fracturing turntable trays made of glass, and the like.

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