| 摘要 |
A heater assembly includes first and second flexible layers and first, second, third, and fourth flexible electrical resistance heating elements connected in series and positioned between the first and second flexible layers. The first, second, third and fourth heating elements form a plurality of heating zones having different watt densities so that heat is non-uniformly produced by the heating zones. In a preferred embodiment, the first, second, third, and fourth heating zones are concentric circles and the outer most first heating zone has a watt density higher than the inner most fourth heating zone.
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