Electroluminescent Panels
These panels use zinc sulfide or other materials that emit fluorescence when voltage is applied to them.
EL displays use thin-film phosphors, which emit light when subjected to an electrical field.

Light Emitting Diode
By joining two types of semiconductors, LEDs emit light when a current is passed through them. These devices are capable of converting a flow of electrons into light, with excellent brightness.

Vacuum Fluorescent Displays
This is a type of vacuum tube composed of positive, negative and grid like electrodes. Positive electrodes and fluorescent material are separated into display unit on a glass substrate, and thermoelectrons are emitted from separate negative electrode filaments in another location. These thermoelectrons are accelerated by the grid located between them and impacts on the target display unit.

Plasma Display Panels
This is a type of two-electrode vacuum tube, which operates on much the same principle as a household fluorescent light.
An inert gas such as argon or neon is injected between the two glass plates on which transparent electrodes have been formed, and the glass is illuminated by generating a discharge. These have high contrast and are relatively easily applied to color displays.

Field Emission Display
An FED projects picture using the same light emitting principle as a CRT. A FED removes electrons from a cathode, and makes them collide with fluorescent material applied to the cathode, thus emitting light. While the cathode of a CRT uses a point electron source, a FED uses a surface electron source.

OLED
The most promising new Flat Panel Display technology is Organic Light Emitting Diodes (OLED). OLEDs, which produce light using the electron/hole combination method as in LEDs, the frequencies of light absorbed by the light emitting materials lie mostly outside the visible light spectrum, making OLEDs transparent when switched off and highly efficient emitters, and transmitters, of light when switched on.

Non Emissive Displays

Liquid Crystal Display
A Liquid Crystal Display consists of an array of tiny segments (pixels) that can be manipulated to present information. Liquid Crystal Display is an Electro-optical device that uses crystalline liquid sandwiched between two super thin, grooved glass plates that changes incident or some other external light source into a visible display consisting of numbers, letters, dots or graphics.

Liquid crystals are organic molecules that have crystal-like properties but that are liquid at normal temperature. Because the intermolecular forces are weak, the molecules can be oriented by weak electromagnetic fields. The liquid crystal molecules used in LCDs also have an optical anisotropy (different indices of refraction for different axes of the molecule) that is used to create visible images.

Passive Matrix Displays
Passive Matrix technology utilizes the properties of the Liquid Crystal material, which is sandwiched between the two glass plates on which the electrodes are patterned. There are no sandwiching elements controlling the pixels. Pixels are turned on/off by biasing the row and column electrodes.
There are 3 types of Passive Matrix Displays – Segment Displays, Character Displays and Graphic Displays.

Active Matrix Displays
Active Matrix technology utilizes an active element (Thin Film Transistor), attached to each pixel to switch each one on/off. This technology offers best performance of any LCD with full color with high quality and fast response time. These displays are also commonly called as TFT displays, based on their technology.

Controller
To accept external display information and send it to the appropriate LCD drivers.
There are two main types of controllers:
Analog – More colors, simple interface, almost for any analog RGB source
Digital – Low power, Low cost

Backlight
To generate a consistent, uniform light source.
The light generated from the back light is focused through the LCD. These are the largest power-consuming component in a LCD. Back light also largely contributes towards the weight and the thickness of the panel.

Inverter
To provide high voltages and current required by the back light bulb.
Inverter generates voltages from 450 ~ 600 Vac. Startup voltages may exceed 1000Vac.
Dimming capabilities are a function of the inverter design.

Mechanical frame
To provide mechanical housing to hold LCD panel. TCP Drivers, Interface electronics, Back light system and in some cases the inverter.
This also helps to reduce the EMI and is a large contributor to the weight of a LCD module.