| 摘要 |
PURPOSE:To perform highly accurate measurement without the effects of temperature variation in an output resistor, heating, and the like in a simple constitution, by supplying a pulse current to the output resistor so as to offset the current in a feedback coil which generates an electromagnetic force corresponding to a load. CONSTITUTION:When a beam 22 of the balance is moved by a weighing pan 7, a feedback current IF corresponding to the load is flowed through the feedback coil 20 by a displacement sensor 1 and the like, and the position of the beam 22 is restored. By this current, a pulse D, which converts the load to a digital value and corresponds to the load, is generated through the output resistor 21, a differential amplifier 9, a comparator 10, a sawtooth wave generator 11, and the like. At the same time, the pulse current IP, which offsets the current IF, is supplied to the resistor 21 from a reference current generator 12 in correspondence with said pulse D. Only a minute compensating current is flowed to the resistor 21 through a quantizing error compensating circuit 18. In this simple constitution, the highly accurate load measurement can be performed without the effects of the temperature variation in the output resistor, heating, and the like. |
