Samsung SyncMaster 191T 19" LCD Display Review
Written By: Paul MachadoReview Date: July 23/2002
Product Supplied By: Samsung Canada
History of TFT LCD:
Liquid crystal was
discovered by the Austrian botanist Fredreich Rheinizer in 1888. "Liquid
crystal" is neither solid nor liquid (an example is soapy water).
In the mid-1960s, scientists showed that liquid crystals when stimulated by an
external electrical charge could change the properties of light passing through
the crystals.
The early prototypes (late 1960s) were too unstable for mass production. But all
of that changed when a British researcher proposed a stable, liquid crystal
material (biphenyl).
Today's color LCDs have a sandwich-like structure (see figure below).
What is TFT LCD Technology?:
TFT LCD (Thin Film Transistor Liquid Crystal Display) has a sandwich-like structure with liquid crystal filled between two glass plates.
TFT Glass has as many TFTs as the number of pixels displayed, while a Color Filter Glass has color filter which generates color. Liquid crystals move according to the difference in voltage between the Color Filter Glass and the TFT Glass. The amount of light supplied by Back Light is determined by the amount of movement of the liquid crystals in such a way as to generate color.
TFT LCD Electronic Aspects:
The most common
liquid-crystal displays (LCDs) in use today rely on picture elements, or pixels,
formed by liquid-crystal (LC) cells that change the polarization direction of
light passing through them in response to an electrical voltage.
As the polarization direction changes, more or less of the light is able to pass
through a polarizing layer on the face of the display. Change the voltage, and
the amount of light is changed.
There are two ways to produce a liquid-crystal image with such cells: the
segment driving method and the matrix driving method.
The segment driving method displays characters and pictures with cells defined
by patterned electrodes.
The matrix driving method displays characters and pictures in sets of dots.
1. Direct vs. multiplex driving of LCDs.