| 摘要 |
PURPOSE:To uniform the quantity of heat generated in the force coil of an electronic balance and improve the accuracy thereof by changing over the current supplied to said force coil, alternately with a given cycle. CONSTITUTION:The force coil displacement resulting from a load is detected by means of a displacement sensor 3 and amplified before being inputted through a PID controller 5 to a voltage-time difference converter 6. The waveform of the current supplied to a force coil 2 from a constant-current source 7 becomes a waveform repeated alternately in the positive and negative directions. When the load is positive, a positive current is supplied on the average. Similarly, when the load is zero, the force coil 2 is supplied with a current repeated alternately in the positive and negative directions, but an average current becomes zero. An up/down counter 11 is actutated to count in the up direction by the positive current supplied to the force coil 2, and in the down direction by the negative current. Said counted value is displayed on a display device 12, as a load. |
