| 摘要 |
PURPOSE:To calibrate automatically the sensitivity with high reliability, by multiplying a counter output value, which is inreased or reduced in accordance with the result of the comparison between the output value for the input of a calibrating reference signal and a reference output value, by the output of a measuring amplifier. CONSTITUTION:When a sensitivity calibrating command signal is inputted, an FF5 is set, and a switch 13 is turned on, and a calibrating reference input is inputted from a voltage generator 14 to a measuring amplifier 1. An output a' is obtained as an output voltage E0 through a multiplying D/A converter 2. The voltage E0 is compared with a reference value Es in a comparator 3, and contents of a counter 4 are increased or reduced in accordance with the result of the comparison. Since the output of the counter 4 is outputted to the D/A converter 2, the output E0 coincides with the reference value Es. When they coincide with each other, the comparator 3 is inverted, and the FF5 is reset, thus terinating the calibration. Thus, the manual work is unnecessary, and the reliability is improved because there are no movable parts. |
