; (C) Flat Screen Displays
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(C) Flat Screen Displays


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									(C) Flat Screen Displays

       The future of the Video Display Terminal is bleak.
Every manufacture would like you to believe that their model
is the flattest. Some are flat in only one direction, most
“flat screen” monitors are slightly curved. Even when the
tube face is flat there are problems with focusing. In fact
the flatter a screen the more problematical focusing can be.
The middle of the screen is closer to the electron guns then
the edges are and some how everything needs to be in focus.

       There are many techniques used to focus the beams,
the most common being called dynamic beam focusing which is
employed in better units to keep that image focused no
matter where the beam is.

       There is another technology now found mostly in
laptops, about to replace the aging picture tube. Solid
state flat panel displays are going to get bigger and
cheaper over time. They come in a variety of flavors,
exhibit sharp bright colors and are distortion free. Plus
these units have the added benefits of zero electromagnetic
emissions, low weight and power consumption, zero
distortion, no color bleeding and many other advantages.
Gone are the horizontal and vertical retraces and their
associated screen flicker, the radiation, the high heat
associated with large monitors.

       There are currently four or five different types of
flat screen panels.

(c) Liquid Crystal Displays

       This display works just like the hand held calculator
displays. They were slow to respond and only readable
straight on, you remember them? Liquid Crystal Displays
(LCD) have come along way since then. They now come in many
forms both color and monochrome. They work by filtering out
light that shines through them (back light or reflected
light). Using a liquid that responds by changing its
polarity to light in the presence of an electric current
flowing through it. This liquid is sandwiched between two
sheets of plastic or one glass and one plastic.

(d)Passive Single and Dual Scan LCD

(d)Active Matrix Displays
       My favorite and also one of the most promising state-
of-the-art technologies is the Active Matrix Display. This
display is bright, fast and is being produced in reasonable
quantities. However yields are low due to the overwhelming
number of transistors (over 1 million) deposited on the thin
film, each and every one must work or the display is junk.
I wonder what they do with the junk displays? Current
yields are at 20%. The largest current size is 10.5” but
this should change by the time you read this (BTYRT). This
type of display simply (not) uses thin film transistors
(TFT) to directly control thin film electrodes in triads
etched into a film or photographic pattern called a matrix
film, which displays color points of light that make up the
picture. Every pixel element is in perfect focus because
every pixel is right on or near the surface of the screen.
The whole assembly is a sandwich of glass, silicon and

       Like monochrome monitors, monochrome thin film
displays have only one transistor for each point of light
(addressable pixel). Color units have three transistors per
pixel, lowering the overall resolution but adding color.

****Editors - There is actually several types of TFT and I
would like to get more detailed information on this and
update this section later. --Dh

(d)Passive Matrix Displays

       Passive Matrix or Stacked-panel passive matrix
displays work by stacking two or more LCD panels that are
tuned to block or subtract portions of the color spectrum
from full color light passing through (back light) them.
These stacked panels are not yet suitable for laptops or
desktop displays because they require special back lighting
using mirrors and reflectors. They do not have the low
yields that active matrix displays have. And are a very
promising young technology.

(d)Electro-luminesent Displays


(d)Field Emission Displays

**** Editors I will expand on the above -different types of
displays after a little more research, it seems there are
many ways to make a thousand points of light... -DH

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