Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!antonyc From: antonyc@nntp-server.caltech.edu (Antony Chan) Newsgroups: comp.sys.ibm.pc.hardware Subject: Re: QUESTION: Using a VGA monitor on its side? Message-ID: <1991Apr1.010551.15637@nntp-server.caltech.edu> Date: 1 Apr 91 01:05:51 GMT References: <91087.155337REIDMP@MAINE.BITNET> <1991Mar31.052527.9958@nntp-server.caltech.edu> Organization: California Institute of Technology, Pasadena Lines: 55 antonyc@nntp-server.caltech.edu (Antony Chan) writes: >iisakkil@vipunen.hut.fi (Mika R Iisakkila) writes: >>REIDMP@MAINE.BITNET (Reid M. Pinchback) writes: >>> When I set the VGA monitor on its side, there is a strange distortion of >>> colour. >>> 1. What causes the colour distortion? >> It's the magnetic field of the Earth. The VGA pixels are so >>close to each other, that this weak magnetic field is enough to make >>electron beams to land on wrong pixels (=phosphor dots of wrong >>colour). The monitor contains numerous magnets, which are adjusted >>to compensate for the magnetic field. The calibration has of course >>been made to work in the normal position of the monitor. Actually, if >>you took your monitor to somewhere on the southern hemiglobe (sp?), >>say Australia, the colours would be distorted while the monitor is >>standing normally on the table! after a bit more thought, it seems to me that the only way turning a monitor on its side could be affected by the earth's magnetic field is if the dots have looser tolerances in the up-down direction than the left-right direction. i.e. if the electron goes too high or too low, it's not as bad as if they go too far right or left. since in a uniform field the electron will try to circle the magnetic field lines, in its normal orientation the beam will be either slightly to high or too low depending on which way its facing. on its side the beam will also either be slightly too high or too low, but this translates into too far left or right to the screen. ascii graphics follow: --------------------- | ^ | ----------------------- (mag fld lines) | | | ^ | --------->---- | | | | --------->---- ---| | | too high or low | --------->---- | | | | | --------->---- | | too far left or | | v | --------->---- ---| right | ----------------------- | | | | | | ------------ | v | (this one is the monitor --------------------- you're looking at now, and north is to your right) actually, i have only considered electron beams heading either straight north/south (no effect from earth's mag. field) and straight east/west (bends up/down). anything else involves a helix that is too much for me to think about during spring break. oh, and that australia thing just can't be right. it would only make a difference if you considered gravitational effects. (everyone knows that australians stand on their heads) :)