How the LCD TV Works?!



Unique qualities of the device


This type of TV is lighter and thinner than CRT TVs of the same display size, and much like plasma can be made to a large size and very small size. This is where its use originally stemmed from as it can be made to be the smallest size of operational TV, as this technology is used in mobile electronic devices such as phones and calculators. They have a large market potential, with today still being a very strong competitor to the other types of TV technologies.

Over the years this technology did not do so well, and slowly began to pick up in the market as more research was carried out upon it, which led it up to where it is now. Having a strong foot in the market due to its a lower power consumption (than plasma) and is lighter than both plasma and CRT TVs, making it a strong competitor in today’s market.

How they operate is polarising liquid crystals in a certain direction, this new direction will allow light to pass out though the device, however when not polarized the crystals block all of the light being emitted out from the device, a further investigation will made to outline this in our next section.

Features & Functionality


CFL (compact fluorescent lamp) or CFT (compact fluorescent tube) produce the back lighting required for these systems, the light from them is then passed through the liquid crystals and then a color filter. The color filet outlines the pixels used in the design, as the more color filters there are the more pixels this type of TV will have. The light is then modulated by polarizing the liquid crystals, this causes only certain configurations of color to be emitted from the color filter as only certain light is allowed to pass through it. Each pixel (inside of the colour filter) has 3 sub pixels to them in 3 different colours of red, blue and green.

As the light CFL light shines through these pixels made up from the colours the liquid crystals will then deform allowing the colours we desire though while blocking the other colours. Here each sub pixel can have up to 256 shades of a color, which can produce very sharp pictures required

The liquid crystal configurations for polarizing, can be arranged in two different ways they are:

  • Passive matrix


The passive matrix is simply a grid of electrodes linked up to pixel colours, they are arranged in coulombs and rows upon the screen. The LCD controller then modulates the voltages applied to these pixel colours so create an image. However a drawback from this is a slow response time and imprecise voltage control which produces blurred pictures.


  • Active matrix

The active matrix is a construction of thin film transistors (TFT) which are small switching transistors and capacitors arranged in a matrix structure of rows and columns to address each individual pixel in rows. To switch a particular pixel on, the row is switched on then the charge is sent to the correct column. As all of the other rows are switched off only the capacitor at that pixel receives the charge required to switch the pixel on, the capacitor is then able to hold this charge till the next cycle.





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