| 摘要 |
PURPOSE:To enable detection of the state of dew condensation or that of frosting by one element, by using as a sensor an elastic surfce wave element operating by a method of separate excitation or self-excitation. CONSTITUTION:A power source 3 is connected to the input transducer electrode 2 of an elastic surface wave element 1, while an output transducer 4 is provided opposite to the electrode 2. When the elastic surface wave element 1 thus formed and operating by a method of separate excitation is used as a sensor, the change in frequency and the change in an output level are caused by the state of dew condensation or the state of frosting. Accordingly, by reading these changes, the state of dew condensation and that of frosting can be detected. That is, the dew condensation or frosting can be discriminated by giving an output of the sensor 9 to each of comparators 11 and 12. In this way, the state of dew condensation and that of frosting can be detected by one element. A device of a self-excitation method can also be employed in the same way. |
