| 摘要 |
A geomagnetism sensor (2) outputs the vertical magnitude of geomagnetism as a detection signal (Vy). An A-D converter (5) converts the detection signal (Vy) into digital data which in turn is supplied to a CPU (6) together with data from a memory (1). The CPU (6) performs a computation based on a vertical deflection signal (VH), the data from the memory (1) and the detection signal (Vy) to provide parameters (hposi, yvj, vcancel) for determining current values to be supplied to a deflection yoke (13), a convergence correction coil (14) and a beam landing correction coil (15). D-A converters (7-9) convert these parameters into analog signals. Drive circuits (10-12) receives the analog signals provided by conversion to generate current for driving the deflection yoke (13), the convergence correction coil (14) and the beam landing correction coil (15). Image variations under the influence of the vertical component of geomagnetism are automatically corrected.
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