| 摘要 |
<p>PURPOSE:To prevent the running of a video tape recorder under the dew condensed state by providing a hygroscopic swelling resin layer on a substrate, forming an electrode on the resin layer, forming a moisture sensing resistor film on the electrode, and largely delaying the recovery time of dew drops. CONSTITUTION:A hygroscopic swelling resin layer 5 comprising hygrophilic acrylic resin such as cellulose, acetate and polyvinyl alcohol is formed on a substrate 4 comprising metal or ceramics by printing, spraying or the like. Thus, a dew condensation sensor A is obtained. The sensor A is attached to a unitary camera body type video tape recorder. Since the hygroscopic swelling resin layer 5 adsorbs moisture, a moisture sensitive resistor film 7 can readily hold moisture. The film is hard to dry. Therefore, the time when the resistance value of the sensor A returns to a detecting level or less is approximately the same time when the dew drops in the cylinder in the tape recorder disappear. The cylinder does not start the rotation before the dew drops disappear.</p> |
