Monitors: Influence of External Magnetic Fields

Magnetic fields can present image distortion or jitter on a computer monitor. External fields can impinge upon the monitor's internal magnetic field, which controls the electron beams writing the image on the screen. The external field interferes with or disrupts the internal field, causing the screen image to jitter, distort, drift, or to lose color quality.

Typical sources of external fields include common electrical equipment placed near the affected monitor, such as another monitor, video systems, scanners, fluorescent or task lights, electric clocks--just about anything that can be plugged in and turned on. Not so obvious sources include nearby power lines, transformers, switch panels, or wall and floor wiring.

Another source of external fields could come from metal cabinets that can build up a magnetic field over time. This magnetic field can easily be removed by using a degaussing coil on all the metal cabinets or desks that are near the display.