| 摘要 |
PURPOSE:To enable elimination of complicated adjustment regardless of changes in the phase relationship due to aging, temperature variation and the like by forming a synchronous detection signal with a sum signal as reference phase from the combination of outputs of a receiving coil. CONSTITUTION:As synchronous detection signals eF and eS of differential signals ePF and ePS of an induced voltage are formed in an output sum e1+e'2/2 of receiving coils 13a and 13b, even when the phase of the induced voltages e1 and e2 vary to e''1 and e''2 due to temperature variation, aging and the like, synchronous detection signals e'F and e'S are formed following these changes. Therefore, as synchronous detection signals eF and eS are formed with a composite voltage of the induced voltages e1+e2 of the receiving coils 13a and 13b as reference phase synchronous detectors 16a and 16b can be always operated on the optimum phase condition even when the phase of induced voltages of the receiving coils 13a and 13b change due to aging, temperature variation and the like. |
