| 摘要 |
<p>A heating unit comprises a thermochromic temperature indicator and a heating element. The indicator comprises a thick film electrically resistive indicator track (2) having a defined pattern printed on a substrate (4) and a layer (6) of a thermochromic material applied to the substrate (4) so as to cover and surround the defined pattern. The heating unit further comprises means for responding to passage of current in the heating element by generating a current in the indicator track. Accordingly, when the heating element becomes hot, so does the indicator track, and a colour-change area showing the defined pattern becomes visible.</p> |
