LCD TVs – What you need to know before you buy
January 26th, 2009. Published under Television. No Comments.
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.
At the rear of an LCD television is a backlight which shines through the LCD panel. To create the different timbres and contrasts of colour, the LCD panel must be able to restrict the amount of light passing through.
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.
As regards creating colour the pixels are subdivided into three coloured crystals based on the primary colours. The interaction between these red, green and blue crystals produces the lcd televisions colour palette or the lcd tv`s contrast ratio!
The matrix of liquid crystals are placed between two pieces of glass which are polarized to focus the light source and give pixel perfect razor sharpness to the proceedings.
Across the whole internal construct of an lcd tv`s panel is a matrix of micro thin transparent transistors. The matrix feeds information via electrical currents to each individual pixel which then controls the feed of information and ultimately the colour and temperature of an individual pixel. This then ultimately creates, over the whole matrix within the lcd television, the image.
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.