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Enviromental Issues
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| Screen radiation is a pollutant. There is no concrete evidence that
screen radiation can cause illness. However, artificially generated radiation
must be unwelcome in our environment. Consequently, industry standards
have been developed for acceptable radiation levels. Since the early nineties,
the Swedish MPR-2 standard established limits for monitor electrostatic
radiation.
The next standard was the stricter TCO-92. It limits the permitted amount
of low level radiation and establishes standards for electrical and fire
safety. Usually TCO means Total Cost of Ownership but here it refers
to the Swedish Confederation of Professional Employees (Tjänstmännens
Central Organisation). They defined strong standards for emissions.
Finally, we have TCO-95, which is the strictest standard. Similar to
TCO-92, it also includes regulations on ergonomics (including refresh rates),
maximum energy consumption, environmentally friendly production and recycling
facilities. The best screens comply with this standard. Screens adhering
to the TCO standards are more expensive. Obviously since they are better
screens.
The flat TFT screens do not emit any radiation at all and they
consume considerably less energy than the radiating screens. This is another
indication that TFT may be the standard screen of the future.
The VESA DPMS system is an energy saving technology, which includes
both screen and video card. A modern 17” screen consumes about 100 watt
in normal use. With DPMS the screen switches to two energy saving modes.
First, power consumption drops to 25 watts and finally again drops to 8
watt. |
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LCD Screens
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The big, heavy traditional monitors will eventually be phased out.
In a few years they will be replaced by the thin and "soft" LCD (Liquid
Crystal Display) screens! It may be a few years before this technology
will be dominating, but it is bound to happen. The LCD screens are excellent,
and they are available and the prices have gone down. Today a 15" LCD costs
as much as a 17" CRT monitor did 4 years ago. The LCD screen is flat, since
it contains no cathode ray tube (CRT). Instead the screen image is generated
on a flat plastic disk.
LCD screens are also called "soft" screens, since their images have
a softer quality than those from traditional CRT monitors. The image does
not flicker thus causing less eye strain. At the same time the LCD screen
is by far the most environmentally safe product. These flat screens emit
zero radiation, and they consume significantly less power than the
traditional monitors.
A big advantage in the LCD screen is that it does not flicker. Traditional
CRT monitors flicker all the time which is not ideal. Of course the best
CRT monitors have a high refresh rate (85 Hz or more), which provides a
very stable image with no noticeable flicker. But the LCD screen does not
flicker at all. They have a refresh rate of 0 Hz! Modern research has shown
that a steadily illuminated screen image is a very important element in
a good work environment. The eye responds to all light impressions, and
the brain interprets all light impressions continually. When a mediocre
monitor flickers, the brain will continually receive superfluous light
impressions "noise" to sort out. Thus the brain works permanent overtime
interpreting the screen flicker. No wonder that people get tired from watching
their monitors.
Please notice that looking at LCD displays, you may read information
like:
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Pixel Frequency 65MHz
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Horizontal 30 ~ 50KHz
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Vertical: 55 ~ 70Hz
This indicates that there is a refresh rate, but it is only working
when the screen image is changing. So if you move a window across
the screen, the changes will be updated with a refresh rate of 70 Hz or
what ever you choose. |
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Luminous Plastic
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| The monitor technology is advancing very rapidly. The latest development
comes from a British invention LEP - Light Emitting Plastic . It
is an ordinary thin, flexible plastic (polymer), which is sandwiched together
with a thin film of indium tin oxide and aluminum. Thin-film transistors
control the oxide layer, causing the huge plastic polymer molecules to
become light emitting.
These LEP screens should have these advantages:
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They are completely flat and lightweight.
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They consume only small amounts of electric power.
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They do not require background illumination, which the LCD crystals do.
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They emit light, which is visible from all angles of view.
These screens are not expected to be available before year 2002, but there
are clear indications that they will come. Currently work is being done
with prototypes, which have a resolution of 200 dpi. That corresponds to
a resolution of 2200 X 1600 pixels in a 15" screen. So we can look forward
to an extremely high screen resolution. |
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