Upgrading & Fixing Laptops DUMmIES

Taking a Brief Aside into Technology ........................................................

Quickly, let me explore just enough about video display technology so that

you shop wisely or make sound troubleshooting decisions.

In its most simplified descriptions, a video monitor works like this:

1. The computer produces a stream of data (made up of 0s and 1s) that
   describes the image to be displayed onscreen.


2. The information creates the equivalent of a page of information within a
   block of memory within the computer or on a video adapter.


3. A page of information is sent from the computer’s video port to the
   monitor.


4. The monitor decodes the data stream to identify a particular position on
   the screen as well as its color and brightness.


5. Electronics on the monitor use a magnetic field to move a stream of elec-
   trons across, down, and then back up again across the inside face of
   glass tube that is coated with special phosphors (which momentarily
   glow when hit by the stream).

In its most simplified descriptions, an LCD is very similar, only different:

The laptop produces a page in much the same way as a desktop com-

puter and sends the signal within its closed case to a specialized piece

of electronics, which reverses the intensities and colors.

Protected behind a clear plastic front panel and a solid back panel is a

sheet filled with an unusual substance called liquid crystal,which exists

somewhere between a liquid and solid state. These crystals are ther-

motropic,meaning they change their state based on temperature. In most

designs, the crystals allow light to pass through them in their natural

state and block the light (appearing dark) when touched by electricity.

At the base of the panel is a small fluorescent lamp that serves as a

backlight. The screen appears completely white if all of the LCD’s pixels

are in their off, or clear, orientation.

Many older laptops do not have a backlight and are instead reflective,

meaning that they rely on light bouncing off the back of the screen. In

the best conditions (a well-lit office) reflective screen is good, but when

lights are low (think of that airplane seatback tray) the image can be dif-

ficult to see. A few modern machines allow the user to turn the backlight

on or off to save battery power; most current machines have software

settings that give full brightness when the laptop is plugged in to an AC

outlet and turn down the lamp when the battery is running the show.

188 Part III: Laying Hands on the Major Parts