| 摘要 |
PURPOSE:To omit a reference generating means and to minimize the errors in comparing a displacement conversion output and a reference voltage, by using an FET in controlling a power source which charges capacitors for converting the mechanical displacement into an electric signal. CONSTITUTION:Capacitors to be measured C10 and C20 are charged by a DC voltage VCG which is stored in a capacitor C0 through switches S11 and S21 and the FET circuit. A sum ic1+ic2 of the charging currents for the capacitors to be measured C10 and C20 is smoothed by a parallel circuit of a resistor R2 and capacitor C2. The DC voltage comprising the product of said sum of the smoothed currents and the resistance R2 is applied between the source and the gate of the FETT1. The FETT1 is operated as a constant current element. |
