| 摘要 |
<p>An electric blanket 10 has a healing element 11 with inner and outer co-axial conductors 12,13 separated by a low melting point insulator 14 and surrounded by an outer insulator 15. A two-core supply cable 19 includes a switch 23 and a fuse 22 which blows if the insulator 14 breaks down. The element 11 is the only electrical component mounted directly on the flexible blanket 10. The temperature of the element 11 may be controlled by a semiconductor switch responsive to a comparison between current sensed by a series resistor, which depends on the temperature of the element, with a reference level. The reference level may be held high for an initial period to ensure rapid heating. The control may include a clock and sample circuit (Fig.7, not shown). The layout of a heating element for a personal heating pad is also described, (Fig.5, not shown).</p> |
