Cathode-ray tube computer monitors 'flicker' as the electron beam
scans relatively slowly down the face of the tube, then quickly flies
back to the top, with the whole process repeating quickly. I
understand that this 'flickering' is postulated to be the cause of
many ills attributed to extended computer use.

Briefly, (an in-depth technical description is unnecessary, just a
very brief overview), how do the newer flat screen LCD type full size
colour monitors operate (or for that matter, the laptop display panels
which have been around for a while)? i.e. on a microscopic scale, in
what manner are the pixels constructed, and by what means are they
operated?

Does their method of operation mean that they produce no flickering
(assuming a stationary display of desktop icons, GUI etc) - and hence
none of the potential for the ills which might be attributable to the
flicker innate in the design of a cathode ray display?

Hello gan!

As you surmised at the end of your question, it would appear that LCD
displays don't precisely have a screen flicker because of the way they
work - either the cells are on or they're not:

"Q: What does "refresh rate" mean to me in an LCD monitor?

A: For LCD monitors, the refresh rate is much less relevant. LCD
monitors display a stable, flicker-free image at 60Hz. There are no
visible differences between 85Hz and 60Hz.

Q: What does Refresh Rate mean for LCDs?

A: Unlike CRT display technology in which the speed the electron beam
is swept from the top to the bottom of the screen determines flicker,
an active matrix display uses an active element (TFT) to control each
individual pixel and thus refresh rate is not really applicable to LCD
technology."

Phillips LCD Monitor FAQ
http://www.lcdmonitor.philips.com/faq_general.php

"A CRT has three electron guns whose streams must converge faultlessly
in order to create a sharp image. There are no convergence problems
with an LCD panel, because each cell is switched on and off
individually. This is one reason why text looks so crisp on an LCD
monitor. There's no need to worry about refresh rates  and flicker
with an LCD panel - the LCD cells are either on or off, so an image
displayed at a refresh rate as low as between 40-60Hz should not
produce any more flicker than one at a 75Hz refresh rate."

Refresh Rate: Flat Panel (LCD) vs. CRT monitors
http://home.houston.rr.com/djsmith7/refresh.htm  

The same page discusses the configuration and operation of an LCD
panel:

"An LCD consists of two polarising filters with their lines arranged
perpendicular (at 90 degrees) to each other, which, as described
above, would block all light trying to pass through. But in-between
these polarisers are the twisted liquid crystals. Therefore light is
polarised by the first filter, twisted through 90 degrees by the
liquid crystals, finally allowing it to completely pass through the
second polarising filter. However, when an electrical voltage is
applied across the liquid crystal, the molecules realign vertically,
allowing the light to pass through untwisted but to be blocked by the
second polariser. Consequently, no voltage equals light passing
through, while applied voltage equals no light emerging at the other
end."

Refresh Rate: Flat Panel (LCD) vs. CRT monitors
http://home.houston.rr.com/djsmith7/refresh.htm  

For a little more information about how LCDs work, I headed for one of
my favorite places on the Web - HowStuffWorks.com.  They have a habit
of explaining everything in an easy to understand format.

For the whole story on LCDs, start here:

How LCDs Work
http://computer.howstuffworks.com/lcd.htm

...but pay particular attention to this part, which discusses active
matrix displays and continues on to the operation of color LCD:

"Active-matrix LCDs depend on thin film transistors (TFT). Basically,
TFTs are tiny switching transistors and capacitors. They are arranged
in a matrix on a glass substrate. To address a particular pixel, the
proper row is switched on, and then a charge is sent down the correct
column. Since all of the other rows that the column intersects are
turned off, only the capacitor at the designated pixel receives a
charge. The capacitor is able to hold the charge until the next
refresh cycle. And if we carefully control the amount of voltage
supplied to a crystal, we can make it untwist only enough to allow
some light through. By doing this in very exact, very small
increments, LCDs can create a gray scale. Most displays today offer
256 levels of brightness per pixel."

LCD Systems
http://computer.howstuffworks.com/lcd4.htm

(The page also includes a nifty visual explanation of how pixels are
controlled in an LCD color display.)

Some other pages of interest:

The LCD FAQ (very comprehensive, and quite easy to understand)
http://www.microtipsusa.com/products/faq.html

How is the LCD in a laptop computer so bright?
http://computer.howstuffworks.com/question580.htm 
	
LCD Displays and Fluorescent Light
http://www.cloanto.com/users/mcb/19960719lcd.html 

This was great fun to look into for you!  Of course, if you need me to
look for additional information or just need a bit more assistance,
please don't hesitate to ask for a clarification.  I'll be happy to
help!

--Missy

Search terms: [ "refresh rate" LCD ], and look-up of LCD on HSW

Thanks for a thorough answer, confirming that there is less of a
problem with flicker on LCD displays, and also illuminating some
technical aspects I should look at when choosing. New monitor time
here I think (said he, rubbing his CRT-strained eyes :)

Keep in mind that most if not all LCD monitors have a 'native'
resolution, in other words 'one' resolution where they look best.  If
you want to use a different resolution then the 'native' one, it may
look blurry(text/graphics). And just to clarify this further, if you
just love running 800x600 and the 'native' resolution is 1024x768,
then that's where you may run into the problems I mentioned above.
Unlike a CRT, which could really care less what resolution you use,
within it's specs.

I still think game players still would rather have a CRT than an
LCD..Decent CRT's that display a faster refresh rate >75hz, usually
don't flicker that badly. Personally I prefer a CRT(not that you
care), but they do have advantages, in fact, I just bought a 17" pure
flat CRT for $130.00 today and being on a budget, that helps a lot. 
Good luck with your purchase, whichever you choose.

Actually apart from the screen flicker, in case of a crt monitor,
there is production of
x-rays(although minimal, depends on how the focusing beam current is
limited),
static(due to the face of the crt acting as a high voltage capacitor)
that apart from
a high electric field produces ions and ozone due to corona discharge.
 There is
also possibility of high electromagnetic field(from the high voltage
deflection plate
transformer and the yokes(if used for deflection)).  But most of these
could be reduced
the eliminated by the use of a electrostatic metalized glass filter
connected to ground.
In case of a LCD monitor, the voltage used to drive the LCD TFT
elements are not that
high. The only high voltage production is due to the backlight
flourescent tube.  Unlike
the high voltage of the CRT, it is not that harmful due to the
relatively low voltage/current and
higher frequencies involved.  The only downside I think is about the
amount of light output
(an electron excited phospor produces more vibrant color output) and
the contrast ratio
achievable(the metalized tft element might absorb part of the light,
apart from the ability to
completely turn off light which is limited by the polarization
efficiency and reflections from
light leakage).