| 摘要 |
<p>PURPOSE:To improve an S/N ratio by performing an adjustment of the balance of the output voltages of secondary coils at the stage of manufacturing and by limiting the drift of the output signal of an eddy current sensor caused by a temperature change to a small range. CONSTITUTION:In coils wound concentrically on a bobbin 3, secondary coils 2 provided on both sides of a primary coil 1 are wound respectively on rings 5 which are engaged with the outer surface of the bobbin 3 slidably and comprise a non-conductive and non-magnetic substance respectively. After subjecting the secondary coils 2 to a differential connection, the position of the rings 5 are adjusted while monitoring an AC voltmeter 6 so that the output voltage of the secondary coils 2 subjected to the differential connection goes to zero volt in the state that a voltage of a preset frequency is applied to the primary coil 1 by an oscillator 8. When the positions giving zero volt are determined, the rings 5 are molded with an epoxy resin, etc. Since the balance of the output voltages of the secondary coils 2 is adjusted at the stage of manufacturing in this manner, the residual voltage of the secondary coils 2 subjected to the differential connection can be made to be about zero. Thereby, an S/N ratio can be improved by limiting the drifting quantity of the output signal due to a temperature change to a small range.</p> |
