TITLE
    Side-by-Side Monitors Can Interfere with each Other
Article ID:
Created:
Modified: 		5771
6/17/90
6/29/90
TOPIC



    I have a customer who bought an Apple RGB monitor and an Apple Two-Page
    Monochrome monitor to sit side-by-side. The monitors interfere with each
    other, so badly that I'm ready to send each of them back and buy third-party
    products. Anyway, what can be done to have both those monitors side-by-side
    without any screen warping?

DISCUSSION

    We found the following in the Technical Information Library using "monitor and
    interference" as a search string:

    Apple Two-Page Monochrome Monitor: Images Vibrate

    Interference between two monitors placed side-by-side can cause images on the
    monitors to vibrate. The reason is that, when placed side-by-side, monitors
    can magnetically interfere with each other, causing the image on one or both
    monitors to appear to vibrate slightly. This interference problem is most
    often seen when an RGB color monitor is placed next to a large-screen
    monochrome monitor. The amount of interference can also vary depending on the
    user's environment.

    Moving the monitors further apart, especially the rear ends, usually reduces
    the vibration effect.

    Technical Reason For Picture Vibrating
    --------------------------------------
    The cause of this shimmering effect lies in the vertical refresh rate, the
    number of times a monitor repaints the screen each second. When this rate
    differs significantly between monitors, the interference described above can
    occur. There is often a large difference between RGB and monochrome monitors.
    Thus, the vibration effect most often occurs with this combination. Because
    other factors are involved, it is possible for two monitors with the same
    refresh rate to exhibit this effect, although this is less frequent.

    Shielding monitors so as to prevent this type of interference would add a great
    deal to the cost of each monitor. Further, by shielding a monitor you can
    prevent the monitor from interfering with other monitors, but other monitors
    could still interfere with it. Apple is investigating a number of technologies
    to prevent this interference in the future and plans to incorporate them as
    they become feasible.

    We are sorry that we cannot solve your problem at this time, but you may see an
    improvement if:

    - the orientation of the monitors is reversed

    - the monitors are separated by 8-10 inches

    - a metallic plane (foil-wrapped cardboard, for example) is placed between the
    monitors.



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