| 摘要 |
<p>PURPOSE:To improve the workability of measuring work, by automatically compensating the fluctuations of base currents supplied to a light-emitting diodes in the optical partially potentiometer which measures voltage by utilizing light. CONSTITUTION:When a light-emitting diode LEDA1 in an A system is radiated by a variable DC power source VB, the light therefrom is received by a light- receiving diode PDA2 at the high-tension side by an optical fiber OFA1. As a result, a transistor Tr1 is turned on, and base currents and signal currents from a signal source S flow to a LEDA2 at the high-tension side so that the light be emitted. Luminescence from the LEDA2 is received by a PDA1, and amplified by an operational amplifier OP1, and output VOUT is obtained at an output terminal. A LEDB1 in a B system emits light at the same time as the LEDA1 is radiated, and the polarity of optical currents obtained through an OFB1, a PDB2, an OFB2 and a PDB1 is inverted by an operational amplifier OP2. The resulting optical currents are inputted to the operational amplifier OP1. The A system and the B system are symmetrical except the signal source S so that base currents are denied. Since elements in the A and B systems have the same characteristics, variations corresponding to base currents therein are automatically denied.</p> |
