5.   Article ... "Who Says A PC Can't Injure You?"
By Joe Robson http://newbieclub.com

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A couple of years ago I had a replacement monitor delivered under
warranty. It was a big brute and came with a fancy swivel 'n tilt
stand which I'd used for the previous 10 months. But this time around
I couldn't figure out how to clip the stand into place, so I just
plonked the monitor onto my desk 'temporarily'.

After 3 days in its 'temporary' position I realized that my neck and
shoulders no longer needed periodic stretching to relieve stiffness -
especially at the end of the day. Then I realized that my fancy
monitor stand actually positioned the screen so that I had to tilt my
head slightly upward - causing aching joints. And I had been doing
that 12-14 hours a day for nearly a year! I also realized that once in
position, I had never needed to reposition it, so the super-duper
star-trek stand was merely an ornament.

Since then I've been astonished at how many times I see people using a
PC with their monitor and/or keyboard which is badly positioned - in
stores, offices and such.

So here's a few tips on how to avoid injuries when using your
computer.

What about injuries? Can you be injured using your computer, or is
this just a joke passed from one person to another? Well, you might be
amazed to know that doctors report an increase in the number of
injuries associated with computer use.

Strains, muscle pain, chronic headache, or repetitive strain injuries
may occur. Here's some tips to make life in front of the monitor more
rewarding.

Adjust your chair. When you slouch forward, problems occur with your
back, neck, shoulders, and legs. Make sure you have enough padding not
only for comfort, but for support. If you move a lot, get a chair that
swivels. Padded armrests will help if you do a lot of typing.

Adjust the height of your chair so your feet rest flat on the floor
and your thighs have enough room under the desk or table. You don't
want to hunch forward, lifting your shoulders. You may want to get a
footrest as well. Just lifting your feet a bit can make work more
pleasant.

If your keyboard is too high, you lift your shoulders in a constant
shrug during the day. This causes muscle aches in you neck and
shoulders. If you drop your wrists in an attempt to rest your arms and
shoulders, you can stretch tendons and ligaments, and press on nerves
in the hands. Position your keyboard directly in front of you, and as
close as possible. The most natural and comfortable position is right
on your lap. This may not be practical, however, but getting it right
down low really helps.

Your mother told you stand up straight, and now I'm telling you to sit
up straight. Like a lazy dog who leans over on one haunch, you may
tend to slouch. (No, I'm not saying you're a lazy dog!) Keep your
elbows near your body and your forearms parallel with the floor. Your
muscles will thank you by not complaining.

Use a light touch on your keyboard. No need to bang away at the keys
and scare the mouse. Stay relaxed throughout your entire upper body.
And hold your mouse like you would a baby kitten. Stay loose. And stay
in shape.

Your monitor should be a comfortable height. You'll find that a poorly
positioned monitor causes more fatigue than anything. Ever go home
after a day at work thinking, "What did I do to make me so tired?"
Invest in ergonomically designed furniture. You'll thank yourself.

Glare off your monitor's screen can be reduced by angling it 90
degrees to the source of light, or getting an anti glare filter. These
filters make viewing a lot easier if stray photons are the problem.

What's the ideal height for your monitor? The top edge should be at
eye level when you sit up straight, so your eyes have to look just a
little bit downward when viewing the middle of the screen.

You should be able to see the screen without tilting your head or
using your back muscles. Additionally, make sure the monitor is about
an arm's length from your eyes. You may want to change the brightness
or contrast of your screen if you have problems seeing it. Or check
with your optometrist and have your vision analyzed. You may find some
lightweight reading glasses are just the ticket.

So what if you type a lot of stuff from printed notes? Try to keep the
material as close to the monitor as possible. There are nifty devices
made to hang your notes to the left or right, so you can focus easily
without cranking your head constantly.

Don't forget to move your butt every 20 to 30 minutes. Stretching
exercises and frequent short breaks as opposed to long, infrequent
breaks. I don't know your exact situation, but if you spend much time
working with a computer, you'll appreciate "doing it right."
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You can reprint this article providing you include the following
resource;

Article by Joe Robson of The Newbie Club, once described as the
Friendliest PC Learning Site on the Web. http://newbieclub.com   

Elly Byrne
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Elly Byrne
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The Ultimate Supertip
from Harvey Segal
http://tinyurl.com/bg7h2

I've reposted this reply from another forum about the same question:

There are a couple possible noise sources.

1) Whatever the monitor uses for internal power conversion.
   My monitor gets 12VDC from a wall wart, and the 12VDC has to
   be converted in the monitor, to voltages suitable for the
   chips that control the LCD.

2) The inverter that drives the backlight.

The inverter uses a piezoelectric transformer. This article
gives some tech info on how it works.

http://focus.ti.com/lit/an/slyt107/slyt107.pdf

There are two ways to build inverters. This article shows
the magnetic alternative, as well as the piezoelectric method.

http://www.eetasia.com/ARTICLES/2005JUN/A/2005JUN13_ACC_POW_AN01.PDF

They both operate above human hearing frequency. This piezoelectric
device has a self resonant frequency of 82KHz.

http://www.steminc.com/piezo/single_layer_transf.asp

The question would be, whether a device emitting sound, above
the human hearing range, can still have a physiological effect.
Aliasing (beat note) between two oscillator noise sources
in the back of the monitor, could create a tone just above
human hearing, so there are some other possibilities when
it comes to the noise spectrum.

This article does mention that it is possible for humans
to "perceive" noise up to 120KHz.

http://en.wikipedia.org/wiki/Ultrasonic_hearing

   "Ultrasonic hearing is a recognized auditory effect which allows
    humans to perceive sounds of a much higher frequency than would
    ordinarily be audible using the physical inner ear, usually by
    stimulation of the base of the cochlea through bone induction.
    Human hearing is recognized as having an upper bound around 17-20
kHz,
    depending on the person, but ultrasonic sinusoids as high as
    120 kHz have been reported as successfully perceived."

And what that means is, it is possible for the inverter in the
monitor, to be perceptible in some way. Even if the perception
is a feeling of pain.

To distinguish between bone induction, and direct hearing, you
could try wearing hearing protection. The hearing protection
should be ineffective against this kind of noise, so if the
perception continues, then the effect could be via
conduction, rather than through the auditory canal.

If hearing protection eliminates the problem, then at least
you could suspect whatever the problem is, it is via
the auditory canal.

   Paul

julian8888...@hotmail.com wrote: