Liquid Crystal Display (LCD)
LCD are passive
display devices characteristics by very low power consumption and good contrast
ratio. The liquid crystal display does not emit light or generate light. It requires
an external or internal light source. Although LED give off light but LCD are
not light sources but controls light. LCD a reflect part of surround by light.
Principle
The molecules in
ordinary liquids normally have random orientations. In liquid crystals, the
molecules are oriented in liquid crystals, the molecules are oriented in a
definite crystal pattern when an electric field is applied to these crystals
the molecules which are approximately cigar shaped, tend to aligns themselves
perpendicular to the field. Charge carriers flowing through the liquid disturb
the molecular alignment and cause a turbulence within the liquid, this is
illustrated in below fig
. Molecules In Liquid Crystels
When not
activated, the liquid crystal is transparent.