Power frequency magnetic fields and computer monitor instability

Owing to the increased use of electronic loads, the harmonic content of the magnetic field in buildings has increased and it is therefore of interest to study how the harmonics (i.e. 150 Hz magnetic fields) will affect the st ability of the picture on the monitor screen. Another frequency of interest to study is 16.7 Hz, the frequency used by the Swedish railway. Ten volunt eers were asked to judge the occurrence of jitter on a 15-in. color monitor screen, refresh rate 72.2 Hz, at different amplitudes and frequencies of t he vertical applied magnetic held. The tested screen had a highest sensitiv ity to 150 Hz external magnetic field, followed by 60, 16.7 and 50 Hz. In a static magnetic held the screen had a sensitivity (displacement) of 0.031 +/- 0.006 mm per applied microtesla. (C) 1998 Elsevier Science Ltd. All rig hts reserved.