FLAT PANEL Displays
Screens using LED, LCD,
and Gas-Plasma are techniques engineered for displays on Lap-Top or
portable PCs. 
The biggest problem with most portable computers is displaying
information on a screen small enough to be portable yet large enough to be
viewable.
Most monitors use serious amounts of electrical power. The batteries
supplied with most LAPTOPs will not provide power to use a normal monitor
, even if the weight and size was acceptable.
When dealing with Laptop computers, power consumption and the related
problem of heat generation is the of primary concern. Each of the
technologies listed below attempts to deal with these two problems.
- Light Emitting Diodes
- LEDs have the problem of being heavy consumers of power. To
fully illuminate a screen, based on the resolution, you might need more
than 100,000 LEDs to illuminate all the proposed pixels on a screen. A
single LED may draw from 10 to 100 milliwatts (.001 watts).
Even with the small size of an LED on a screen, they still draw much
more power than is required by other technologies.
LED monitors tend to fade in strong light, and they are expensive to
fabricate, especially in larger screen sizes.
- Liquid Crystal Display
- LCDs are the primary display technology used in LAPTOP
computers. There are three types of LCDs: reflective LCDs, Backlit LCDs,
and edge lit LCDs.
While other technologies use light (energy) to display, the LCD
simply block light otherwise available to them, thereby reducing energy
usage.
To make patterns visible, they may either selectively block reflected
light (reflective LCDs), or use light generated by a secondary source
either behind or adjacent to the LCD panel.
The "back light" source is usually an electro luminescent panel. Some
laptops use cold-cathode fluorescent (CCF) for brighter, white displays.
The CCF costs more, are thicker, and more complex. An LCD color
screen can easily add enough cost to double the original cost if the LED
was monochrome.
- Gas-Plasma - This
technology is the easiest to manufacture and it produces the sharpest
images of the three technologies. However, it requires several times the
amount of power required by a LCD screen, and at high voltages.
This means you have to disperse a large amount of heat. The
Gas-Plasma displays are used primarily in AC powered portable s because
of the difficulties of synthesizing high voltages from low-voltage
batteries.
A battery would have a life cycle time of about 1 hour on a system
with a gas-plasma display.  
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