The most popular way of generating an image on any modern day television is by the use of LCD television technology (liquid crystal display).
The ever changing and fluid nature of a picture is a constant challenge for any television and this is how an lcd television does it.
An lcd television has a back light permanently turned on, which is the source of a televisions brightness. To create brightness and darkness it must be able to limit or increase flow of this light.
The cylindrical property of a crystal allows light to flow through it. The twisted element of a crystal allows the regulation of the amount of light passing through. The amount of twist is dependent on the amount of electrical current passing through. Increase the current to tighten the crystal and therefore reduce/prevent light passing through ie dark scenes. Decrease the current to relax the crystal and allow light to flow through freely ie light colours. The complete restriction of light is impossible on this method though as however much current is passed into a crystal it can never fully prevent light passing through. Also, the close proximity of other pixels means light seepage to neighbouring crystals although this is kept to a minimum with polarized glass (see later). This is why it is well documented that LCD televisions cannot achieve and will not achieve a real true black.
To create colour in an lcd tv, the pixel has three coloured sub crystals which are made up of the primary colours (red, green, blue). The relationship between these crystals generates the colour and hue of the pixel ie the contrast ratio.
The lcd television panel is made up of two polarized pieces of glass called mother glass. They are polarized to create further focus for each individual pixel to give razor sharp accuracy as well as create separation between pixels. The internal of one of the sheets of glass is polymer coated to secure the many crystals required in any modern day lcd tv.
The distribution of information through the lcd tv is via a transparent matrix of thin film transistors. This network co ordinates the feed of current through the lcd television panel and thus controls each individual pixel and resultant picture. It must do this rapidly due to the nature of television ie it is constantly moving. This process can be performed upto 100 times a second.
An lcd television is a complex piece of equipment, that requires multiple processes to correspond instantaneously. The inability to create a true black is always an issue due to light bleed but with further developments in LED specific pixel lighting technology as opposed to a blanket back light the challenge is on to create the perfect screen.
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