| 摘要 |
PURPOSE:To simplify a circuit configuration, by omitting an oscillator, a rectifier and a comparator. CONSTITUTION:On a magnetic distortion ribbon 1 which has been supported by supporting bodies 2A, 2B are provided an elastic wave energizing coil 12 and a detection coil 13, which have been wound around a rodlike magnetic core. The magnetic pole direction of the coils 12, 13 and a bias magnet 5 are set in the same dirction of the ribbon width, so that a ribbon width resonance is generated. Between the coils 12, 13 is connected an amplifier 14, an output is applied to the coil 12, a detection signal which the coil 13 obtains is positive-fed-back to the amplifier 14, an oscillator is constituted, and is oscillated by 250KHz being a width resonance frequency. In case when frost falls on the magentic distrotion ribbon 1, as for its transmission characteristic, a porpagation loss increases, an output decreases, and if gain of one-round becomes <''1'', the oscillation stops. Whether the oscillation which is obtained from an output terminal 11 exists or not corresponds to whether frost falls or not. |
