| 摘要 |
<p>PURPOSE:To reduce power consumption without lowering the accuracy of detection by selecting rectangular wave having waveform so as to reduce tertiary harmonic that becomes the cause of lowering of the accuracy of detection due to rectangular wave driving. CONSTITUTION:As an input coil 3 is excited and driven by the rectangular wave, electric power efficiency is nearly 100%. Further, an outside capacitor 30 and a resistor 31 of a monostable multivibrator 24 are adjusted to make the width T of pulses outputted by the monostable multivibrator 24 (2pi)/3. Consequently, a signal F becomes the rectangular wave current of positive direction and negative direction while sandwiching the period of cessation of pi/3, and does not contain tertiary harmonic component that deteriorates the accuracy of detection. Accordingly, high power efficiency can be obtained without lowering the accuracy of detection. By selecting the value of a capacitor 22 to make the capacitor 22 and the input coil 3 cause series resonance to basic frequency, the harmonic component of higher order is further lowered and the accuracy is improved.</p> |
