| 摘要 |
<p>In a display device a magnetic field is detected by a DC biased bridge circuit (1,2,3,4) having at least one resistor (1,2,3,4) whose value depends on the magnetic field. The resistor (1,2,3,4) is of the type which makes that the characteristic of magnetic field versus the DC output voltage of the bridge, has an undetermined sign. To circumvent this problem, a so-called inversion coil (5) is used which sends alternating magnetic pulses to the resistor. As a result, the bridge provides an AC signal whose curve is representative of the value and the sign of the magnetic fields under test. This AC signal is detected in a switching circuit (9), synchronous with the magnetic pulses, to produce an appropriate detection signal. The detection signal can be applied to compensation coils (15) via an amplifier (16) for compensating the magnetic field under test. <IMAGE></p> |
