| 摘要 |
A hob comprises a substantially planar member having apertures defining hotplate regions, a glass-ceramic insert being positioned in each aperture above a radiant heating element. The use of a molded glass insert corresponding to a hotplate region offers several advantages over prior art hobs conventionally comprising a glass-ceramic sheet formed by a flat glass process which extends over a plurality of hotplate regions. Another embodiment consists of a drop-in heating unit for a hob comprising a metal can, a substrate, a resilient annular spacer, a radiant heating element and a molded glass-ceramic insert. An over-temperature thermal limiter acts to prevent the unit becoming overheated. A metal compression band extends around a downwardly protruding skirt of the insert, increasing its resistance to shock. The glass-ceramic insert has reinforcing radial spars and a profile which generally has a greater thickness of glass towards its periphery and a generally lesser thickness towards its center, the transition being provided by a curved profile. Such shaping of the insert improves both its transmissive and its conductive properties without a reduction in strength.
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