What is LCD and How does it work?

LCD, What is LCD, How does LCD work, Full Form of LCD, Types of LCD, Uses of LCD, Importance of LCD

I know what is LCD? All of you must have already know about it. All of you have already heard about it somewhere and many must have used it as well. Nevertheless their maybe many such people who do not have any knowledge about it. The full form of LCD is “Liquid Crystal Display”. This is a flat panel display technology which is commonly used in TVs and Computer Monitors. Along with that, it is also used on the basis of the screen of the mobile device in laptops, tablets, and smartphones.

LCD display not only look different than CRT monitors, but they also work very differently. They are not as big and bulky as CRT monitors. Here the electrons are not fired on the glass screen, but the LCD has a backlight which provides lights to all the individual pixel which are arranged like a rectangular grid. All pixels have red, green and blue sub-pixel which can be turned on and off.

When all the sub-pixel of the pixel turned off than it appears black and when all the sub-pixels are turned on then it appears white. Million colour combinations can be found by adjusting the red, green, and blue light of all the individual levels. This was some information about LCD. Now let me tell you how it works and how many types it has and other important information. So without delay let’s start and know what is LCD and how it works?


What is LCD?

Like I have already told you that the full form of LCD is “Liquid Crystal Display”. It was first discovered in 1888. Since then till today its use has started increasing gradually. This is such a technology which is used according to the display, where you can do many things like application status, display values, program debugging. Like LED and plasma technology, the display in this too is very thin as compared to CRT technology.

LCD consumes very less power as compared to LED and gas display because they work in the principle of blocking light and not of emitting. LCD is generally made up of either a passive matrix or an active matrix display grid. The active matrix LCD also called the Film Transistor Display (FTD).In passive matrix LCD, the grid of conductors with the pixels are located at all intersections of the grid. Current is sent across two conductors on the grid for any pixel.

In an active matrix, one transistor is located at all pixel intersections so that they require less current to burn the pixel. For this reason the current can be easily switched on and off in the active matrix display, so that the screen refresh time can also be improved. Dual scanning is available in some passive matrix LCD, which means that it can scan the grid twice in the same current as it was scanning only once with the help of original technology but still active matrix is a superior technology.

Types of LCD

1. Field Effect Display (FED)

(a) This type of Field Effect Display contains “Front” and “Black” polarizer at right angles or 90° with each other.
(b) They are placed at 90 degree to each other.
(c) Without electrical excitation, the light that comes here from the “Front” polarizer generally revolves in 90° inside the fluid.

2. Dynamic Scattering Display (DSD)

(a) In this Dynamic Scattering Display mainly two pieces of glasses are sandwiched with a very thin layer of LC material.
(b) A transparent conductive coating is found on the inner faces of the glass.
(c) Therefore, as soon as voltage is applied to it, the liquid crystal molecules themselves get realigned and start moving randomly.
(d) This creates a turbulence and by which it disperses the light and ultimately a “white appearance” is seen in it.

Applications of LCD

1. Common LCD Applications:

(a) Calculators
(b) Watches
(c) Clocks
(d) Telephones

2. General Applications of LCD:

(a) Computer Monitors (Computer Screens)
(b) Instrument Panels
(c) Televisions
(d) Aircraft Cockpit Displays
(e) Signage

What is difference between LCD and LED?

1. The full form of LCD is ‘liquid crystal display’ and technically, both LED and LCD TVs are liquid crystal display. The basic technology is the same in both these television types and both of them have to layers of polarized glass through which these liquid crystals block and past light. If seen, LED TVs are a subset of LCD TVs.

2. The full form of LED is ‘light emitting diodes’ and it differs greatly from general LCD TVs, where fluorescent light are used in LCDs, while light emitting diodes are used in LED. Along with this, the placement of those lights also differs.

3. In LCD TV the fluorescent light is always located behind the screen. Whereas in an LED TV, light emitting diodes are placed behind the screen or around its edges. For these reasons, LED TVs look thinner than LCDs.

4. LED TVs run faster, have better energy efficiency and provide a cleared better picture then general LCD TVs.

Advantages of LCD

1. Sharpness- Image of LCD are very sharp in their native resolution.

2. Geometric Distortion- Zero geometric distortion is visible in the LCD in the native resolution of its panel. Minor distortion is visible in other citizens because the images have to be resealed.

3. Brightness- Due to this high peak intensity here, the image appears very bright.

4. Screen Shapes- Here the screens are completely perfectly flat.

5. Physical- They look slimmer than usual and have very small footprint. Due to which they consume very little electricity and produces less heat.

Disadvantages of LCD

1. Resolution

Here the fixed pixel resolution format of all the panels is already determined by the manufacture which cannot be change later. All other image resolutions require rescaling, which results in significant image degradation, particularly for fine text and graphics. 

2. Interference

LCDs that use analogue input require careful adjustment of pixel tracking/ phase to reduce our eliminate digital noise on an image.

3. Viewing Angle

There is limited viewing angle here. Along with this brightness, contrast, gamma and colour mixture also vary with the viewing angle. There can be more contrast and colour reversal in large angles.

4. White Saturation

The bright end intensity scale of LCD is easily overloaded, which leads to saturation and compression. To control it careful adjustment of contrast control is required.


1. What is full form of LCD?
Ans. The full form of LCD is “Liquid Crystal Display”.

2. What are the types of LCD?
Ans. Field Effect Display, Dynamic Scattering Display.

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