Advantages And Disadvantages Of Twisted Nematic LCD Technology
LCD Basics, Sharp MEG, Technologies 15/05/2018 0

Advantages And Disadvantages Of Twisted Nematic LCD Technology

The Nematic phase is one of the two major phases of liquid crystals, the other being Smetic phase. The Nematic phase is closer to a liquid substance than to a solid substance.

Twisted Nematic (TN) LCD describes a thin-film transistor LCD found in calculators, digital watches, smartphones and computer monitors.

The introduction of TN LCD technology in the 1970s was a breakthrough in display technology to help the commercialization of LCDs in electronic devices.

How It Works

TN display technology uses nematic liquid crystal placed in the midst of glass substrates dusted with ITO (indium-tin-oxide). The ITO is in turn coated with layers that rub in a direction.

Polarized light manipulation is the underlying principle in TN display technology. As light enters the TN cell, there is a twist in the polarization state with the liquid crystal director.

Advantages Of Twisted Nematic LCD Technology

The advantages in using TN panels made the TN LCD technology to be adopted for portable electronics in the 1990s.

  1. Not Expensive

TN liquid display crystal technology is easy to implement. This means inexpensive manufacturing requirements for industries and an affordable end product for consumers. This has made the use of TN LCD to serve as a good replacement for CRT and LED technologies. It is also a cheaper alternative to newer technologies like AMOLED and IPS.

  1. Power Consumption Efficiency

TN technology does not need any current requirement to function. It operates with low voltages. For this, it can be operated with batteries and other low power sources.

  1. Has A Good Refresh Rate And Response Time

The response time of a pixel is the time lapse required for a pixel to change from a state to another. The unit of measurement is milliseconds. The smaller, the better. The refresh rate, in contrast, is the frequency at which the image of a display is refreshed. It is measured in Hertz. The superior refresh rate and pixel response time give the Twisted Nematic LCD technology the capability to display faster images in a short period of time.

Disadvantages Of Twisted Nematic LCD Technology

The disadvantages of TN LCD technology can be the reason it is not being adopted for many modern applications.

1. Bad Viewing Angle

The viewing angle of TN LCD technology is low. A user has to look up from a 90-degree range for a maximum visual experience and good performance. In a lower angle range view, colors tend to be duller while images will be darker.

2. Bad Color Reproduction

Unlike LCD’s IPS and VA panels, using TN panels produces poor color reproduction. This negative aspect of TN LCD may have resulted from the restricted viewing angle. The bad color reproduction also translates to inaccuracy in color production from the TN panels. This makes TN LCD not suitable for image-oriented works such as a graphic design, video editing, and photo editing.

3. No Fixed Quality

Twisted Nematic LCD panels vary in quality from different producers. When a low-quality product is adopted, the other disadvantages will be more pronounced in the output of the implementation such as the color implementation and the viewing angle. Cheaper and poor quality TN panels can also bring out another demerit of susceptibility of dead pixels.

No doubt, TN LCD technology was a breakthrough for LCD development.

Its affordability and the change it brings into display technology are however being outshined by the incoming of superior display technologies such as IPS LCD, OLED and other latest development in display technology of today.

How LCD’s Work
LCD Basics, LCD Market, Sharp MEG, Technologies 21/03/2018 0

How LCD’s Work

Television sets use to be bulky, heavy and energy consuming before the advent of the Liquid Crystal Display (LCD) technology. LCD TVs are slim, lightweight and can be hung on walls. TVs are much like laptops now with flat screens.

This is made possible with the adoption of the LCD display technology that has long been used on our digital watches and calculators.

The Smectic phase is when the liquid crystals are cooled.

The Uniqueness Of Liquid Crystals

Liquid crystals are substances that fall between a solid and liquid material. It can be described to be an extension of the three states of matter because it is not any of those three. Just like states of matter, it can be in any of the two states it is commonly found with.

The Nematic phase is the state where it is more in the liquid state, where molecules move freely past each other along the same direction. The Smectic phase is when the liquid crystals are cooled. The molecules here form layers that are capable of sliding past each other.

LCD displays are implemented by utilizing the power of liquid crystals and polarized light.

The Working Principle Of LCD

LCD displays are implemented by utilizing the power of liquid crystals and polarized light. The images or pictures displayed on the LCD TV screen results from millions of pixels. Each pixel is a unique red, green or blue light that is switched OFF or ON to produce the picture that is seen in front of the screen.

In addition to plasma screen mode of operation, in LCD screens, the pixels get switched off or on electronically by using liquid crystals which rotates polarized light.

Applying electricity to Nematic liquid crystal straightens it out from its initial twisted-up form. This is the switching on and off process.

Polarised Light And Liquid Crystal And Composition Of The Technique

LCD screens work on a principle where the backlight is required for image display on the screen. At the back of the screen, there is a bright light which shines toward the viewer. At the front of this are the millions of pixels and sub-pixels colored blue, red and green. All pixels have polarizing glass filter at the back and another in front at 90-degrees. This makes the pixels to always appear dark.

In the midst of the two polarizing filters is the minute twisted nematic liquid crystal that untwists and twists (On and Off) through electronic means.

Each of the pixels is controlled separately by a transistor that is capable of switching it off or on several times per second.

Switching Off And On

When the nematic crystals are switched off, light passing through it is rotated at 90 degrees, giving way for light to flow pass the two polarizing filters. This makes the pixel brighter. On switching on the crystal, it does not rotate the light that is blocked by one of the two polarizers. Here the pixel appears dark.

Each of the pixels is controlled separately by a transistor that is capable of switching it off or on several times per second.

Switching On Procedure

  • The backlight of the screen shines
  • Apart from vibrating horizontal light waves, all other light waves are blocked by the horizontal polarizing filter in front of the shining light.
  • Only horizontally vibrating light waves get through.
  • The transistor switches on the pixel when electricity flow in the liquid crystal is switched off. This results in a twisted crystal. The resulting twisted crystal rotates by 90 degrees the light waves as they go past it.
  • The horizontally vibrating light waves that pass through the crystal come out vibrating horizontally.
  • All light waves are blocked by vertically polarizing filter except the ones vibrating vertically. The vibrating vertical light is now able to pass through vertical filters.
  • The pixel brightens up. The blue, red or green filters give the color of the pixel.