| 摘要 |
An electrical heating pad for use with an ungrounded source voltage comprises a heating element arranged in the heating pad and defining a substantially coplanar plane and a fabric outer cover co-planarly enclosing the heating element. The heating element includes a first core made of an insulating material; a first conductive element wound around the first core using the first core as an axis; a second core made of an insulating material arranged in surrounding relation to the first core and the first conductive element; and a second conductive element wound around the second core using the second core as an axis. The first and second conductive elements are connected to each other at one ends and are connected to the ungrounded source voltage at the other ends to at least partially cancel out magnetic field generated from each conductive element. There is at least one shield layer located at one side of the coplanar plane defined by the heating element for substantially shielding electric field. In the heating pad, the second conductive element preferably generates more heat than the first conductive element. In that regard, the second conductive element has a lower total resistance than the first conductive element.
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