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SEMINARON

HOW LCD WORKS

SUBMITTED TO: SUBMITTED BY

ER.RAHUL GARG ANIL ARYA

LECT. IN CSE DEPTT. 3808126

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Contents:

yIntroduction to LCD

yLiquid Crystal

yNematic Phase Liquid Crystal

yLiquid Crystal Types

yCreating an LCD

yBuilding your own LCDyBacklit Vs. Reflective

yLCD System

1.Passive Matrix2.Active Matrix

3.Color 

yLCD Advances

yApplications of LCD

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Introduction To LCD

 A liquid crystal is a material that will flow like liquid but has some

properties normally associated with solids. The LCD has the

distinct advantage of having low power requirement than the LED.

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LCD HistoryLiquid crystals were first discovered in 1888, by Austrian

botanist Friedrich Reinitzer . Reinitzer observed that

when he melted a curious cholesterol-like substance

(cholesteryl benzoate), it first became a cloudy liquidand upon cooling, the liquid turned blue before finally

crystallizing. Eighty years passed before RCA made the

first experimental LCD in 1968. Since then, LCD

manufacturers have steadily developed ingeniousvariations and improvements on the technology.

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Liquid Crystal

liquid crystals act like solids or liquids or something else? It turns out that liquid

crystals are closer to a liquid state than a

solid. It takes a fair amount of heat tochange a suitable substance from a solid

into a liquid crystal, and it only takes a little

more heat to turn that same liquid crystal

into a real liquid. This explains why liquidcrystals are very sensitive to temperature

and why they are used to make

thermometers and mood rings.

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Liquid Crystal Types

Isotropic or Nematic.

Smectic.

Cholesteric.

Ferroelectric liquid crystals.

Surface-stabilized ferroelectric liquid crystals

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Creating an LCDThere's far more to building an LCD than simplycreating a sheet of liquid crystals. The

combination of four facts makes LCDs possible:

Light can be polarized.

Liquid crystals can transmit and changepolarized light.

The structure of liquid crystals can be changed

by electric current.

There are transparent substances that canconduct electricity.

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Building Your Own LCD

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LCD Systems

Passive Matrix

 Active Matrix

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 Applications of LCD

yPROJECTION TELEVISION yDIGITAL CLOCKS and WATCHES 

yCOMPUTER MONITOR 

yLAPTOP COMPUTERS yMICROWAVE OWENS 

yCD Players 

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Color 

An LCD that can show colors must have

three subpixels with red, green and blue

color filters to create each color pixel.

the intensity of each subpixel can range

over 256 shades.

the subpixels produces a possible palette

of 16.8 million colors

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Projection vs. Conventional TV

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TYPES OF PROJECTION

REAR OR REFLACTIVE PROJECTION

FRONT OR TRANSMISSIVE

PROJECTION

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Rear or reflective projection display system

Front or transmissive projection display systems

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THANK YOU

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 ANY QUERY..