Patent ID: 9702752
Date: 2017-07-11
CPC Classifications: G01G

Claim:
1. An electromagnetically force-compensating force-measuring apparatus, comprising: a support coil mounted in a permanent magnet arrangement and through which a force-dependent coil current generated by a controller flows during operation as an output, and an integrating analog/digital (A/D) converter configured to convert an electrical signal, representative of the coil current and applied to a measurement voltage input of the A/D converter, into a digital output signal, wherein the A/D converter is connected at a reference voltage input of the A/D converter to a reference voltage source which has two reference voltages of the same magnitude and opposite polarity relative to one another, and alternately connects each of the two reference voltages via a reference voltage switch to an integrator of the A/D converter, wherein a ratio of intervals in which the reference voltages are each respectively connected to the integrator within a measuring clock cycle provides a measure of the coil current that flows during the operation, and wherein the output of the controller is connected, via a first heating resistor which is thermally coupled to the support coil, to an output of a voltage amplifier, the input of which amplifier is connected to an output of the reference voltage switch, wherein a current/voltage converter is connected downstream of the support coil, an output of the current/voltage converter being connected to the measurement voltage input of the A/D converter and, via an inverter and a second heating resistor, to the input of the voltage amplifier, wherein a resistance value of the first heating resistor is equal to a resistance value of the support coil, a resistance value of the second heating resistor is equal to a conversion factor of the current/voltage converter and a gain factor of the voltage amplifier is equal to a ratio of the resistance value of the first heating resistor to the resistance value of the second heating resistor.