Liquid Crystal Display(LCD)

A liquid crystal display(LCD) draws its definition from its name itself. It is a combination of two states of matter, the solid and the liquid. liquid crystal display(LCD) uses a liquid crystal to produce a visible image. liquid crystal display(LCD) are super-thin technology display screens that are generally used in laptop computer screens, TVs, cell phones, and portable video games. LCD’s technologies allow displays to be much thinner when compared to a cathode ray tube (CRT) technology.

Liquid Crystal Display(LCD

The liquid crystal display screen works on the principle of blocking light rather than emitting light. LCDs require a backlight as they do not emit light them. We always use devices which are made up of LCD’s displays which are replacing the use of cathode ray tube.  Cathode ray tube draws more power compared to LCDs and is also heavier and bigger.

The principle behind the liquid crystal display(LCD) is that when an electrical current is applied to the liquid crystal molecule, the molecule tends to untwist. This causes the angle of light which is passing through the molecule of the polarized glass and also causes a change in the angle of the top polarizing filter. As a result, a little light is allowed to pass the polarized glass through a particular area of the liquid crystal display(LCD).

Thus that particular area will become dark compared to others. The LCD works on the principle of blocking light. While constructing the LCDs, a reflected mirror is arranged at the back. An electrode plane is made of indium-tin-oxide which is kept on top and a polarized glass with a polarizing film is also added on the bottom of the device. The complete region of the LCD has to be enclosed by a common electrode and above it should be the liquid crystal matter.

Next comes the second piece of glass with an electrode in the form of the rectangle on the bottom and, on top, another polarizing film. It must be considered that both the pieces are kept at the right angles. When there is no current, the light passes through the front of the LCD it will be reflected by the mirror and bounced back. As the electrode is connected to a battery the current from it will cause the liquid crystals between the common-plane electrode and the electrode shaped like a rectangle to untwist. Thus the light is blocked from passing through. That particular rectangular area appears blank.


The advantages of liquid crystal display include the following.

LCD’s consumes less amount of power compared to CRT and LED

LCD’s are consist of some microwatts for display in comparison to some mill watts for LED’s

LCDs are of low cost

Provides excellent contrast

LCD’s are thinner and lighter when compared to cathode-ray tube and LED


The disadvantages of liquid crystal display include the following.

Require additional light sources

Range of temperature is limited for operation

Low reliability

Speed is very low

LCD’s need an AC drive

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