Electric microscales

摘要

In microscales having a beam (1) supported by a taut band, the sag of the taut band (2) varies as a function of the load. This leads to changes in sensitivity when the coil (3) of the electromagnetic compensation system thereby comes in the permanent magnet system (4) into a field domain of slightly different magnetic field strength. This change in sensitivity is now electrically corrected by providing two preferably inductive position sensors (5, 6) on the beam (1) to the left and right of the axis (2) of rotation, and by providing circuit elements which form the difference between and the mean value of the output signals of the two position sensors (5, 6). The difference signal is then fed as a measure of the angular position of the beam (1) to the control amplifier of the electromagnetic compensation system, while the mean-value signal is fed as a measure of the sag of the taut band (2) to a correction unit for the sensitivity of the scales. The correction unit contains, inter alia, a circuit for generating a non-linear characteristic in order to simulate the nonlinear spatial dependence of the magnetic field strength in the permanent magnet system (Fig. 1.). <IMAGE>