| 摘要 |
<p>A thermographic indicator device constructed or adapted for use as a road sign or marking comprises a substrate on which there is provided one or more zones of a thermographic material arranged in a form to give visual indication of a condition of incipient freezing in an environment in which it is intended for use. The thermographic material suitably comprises a liquid crystal capsule slurry which changes colour in the range of 3 DEG to -13 DEG C.</p> |
