JOURNAL OF MAGNETIC SHIELD CASE STUDIES

Lead May Shield Superman… But Not Electromagnetic Interference
Case #22804

A prestigious New York hotel had upgraded its check-in and reservation computers to modern PC's with color CRT monitors. Everything functioned smoothly except for the all-important screen in the manager's office, which was nearly impossible to read due to its wavy image. CRT monitor disturbances are typically described as swimming, waving, shimmering or jittering displays. Whatever name you call it, this rose was a big thorn for the manager, whose responsibility for the hotel's entire operation was routinely tied to her computer.

Electromagnetic interference was suspected, so a field survey was performed. The culprit proved to be interference stemming from a power company electrical vault located under the sidewalk outside of the hotel. Magnetic field strengths up to 60 milligauss were found at the monitor's location. This field was certainly enough to cause image distortion, as some monitors may be disturbed by as little as 10 milligauss.

Pinpointing the problem was simpler than finding a solution. Based on bad advice, the hotel had an aluminum box constructed to surround the monitor. It didn't work. Then a lead box was tried, with the same result. The monitor was protected from Superman's X-ray vision, but NOT from the electromagnetic interference. Interference and distortion continued unabated. The customer, very frustrated and skeptical, and by this time poorer but no wiser, turned to Magnetic Shield Corporation for help.

With our considerable breadth of experience in magnetic shielding, particularly for CRT monitors, we knew that the solution was straightforward and immediately at hand. We proposed a standard 5-sided ImageGuard® CRT shield. Constructed of military specification grade CO-NETIC AA® alloy, the enclosure blocks electromagnetic interference to restore a monitor's display integrity. ImageGuard CRT shields install in minutes with no adjustments of the monitor required.

Our total support included discussion with the customer about our background in providing magnetic shielding solutions. We described our experience in supplying CRT monitor shields for such demanding applications as steel mill arc furnace control rooms, displays that must operate near MRI (Magnetic Resonance Imaging) or NMR (Nuclear Magnetic Resonance) machines, and computer monitors engulfed by the electromagnetic fields from an electric power generating station. After listening to us, the hotel manager ordered and installed the ImageGuard CRT shield, which corrected her problem.

To provide our customers with even faster, simplified solutions, Magnetic Shield Corporation now has ImageGuard II CRT monitor shields available off-the-shelf.