Introduction

A regular PAL television changes the picture at a frequency of 50 Frames Per Second (FPS) or 50Hz. The illusion of movement in the picture is produced by the successive frame changes of the picture 50 times per Second. A 50 FPS (50Hz) Cathode Ray Television (CRT) creates the picture with an electron scan and there is a visible flicker that is sensed by the human eye.

The Human eye is at occasionally sensitive to this frequency depending on the intensity of darkness, the speed of the image, and the degree of brightness thus you will occasionally notice the picture flicker on a 50Hz TV. The flicker becomes more apparent on larger screen.

How 100 hertz used to work

A 100 hz TV operates at twice the Frames Per Second (100FPS) by producing a replica of every frame and inserting it after the previous one. The result of this doubling of the scan frequency to 100Hz and inserting a copy frame is that this problem was eliminated as far as the eye perceived it. The result of this is to significantly lower the flicker.

How does 100hz work on LCD and Plasma Tv ?

LCD and Plasma televisions dont produce flickering because they don’t produce the picture with an electron scan. However LCD TV’s still benefit from 100Hz because advanced digital circuitry creates an extra frame or middle image. This is done by the TV inventing an extra frame using complex interpolation and motion compensation calculations to work out what the extra fields and frames look like rather than inserting a replica frame. (e.g. the second frame is not the same as the first frame).

However even at 100 FPS the picture still does not deliver a entirely smooth picture particularly with fast motion images. Some television manufactures attempt to reduce this further by employing digital picture processing. Typically there is still a little blurring on quick moving images but the benefits are clearer and better-defined surfaces, sharper pictures, and smoother movement than is possible from 50 Frames Per Second Plasma and LCD televisions.

e.g. For a football that travels ten pixels from left to right between frames one, two and three, the 100 hertz TV will digitally create two further frames between one and two, and two and three, between which the ball will move five pixels. This will result in five frames where the football moves a total of ten pixels i.e. the original frames one, two and three plus the digitally created frames inserted between one and two, and in between two and three. The result of this is that the eye sees an image that moves smoother than before.

100hz improves the picture

100Hz televisions have a clear benefit of eliminating the majority of ghosting effects now and then seen in LCD TVs. The ghosting effect caused by the next image being shown before the previous one has faded away. Plasma television also benefits from 100hz because the extra middle frame smoothes motion on the screen

Most leading manufactures have now got 100Hz LCD and Plasma televisions including Panasonic, JVC, Samsung, Toshiba, Sony, Philips, LG, Pioneer, and Hitachi.

200hz the next generation

A range of 200hz TVs have been produced by Sony which digitally inserts three further frames between the original 50Hz frames. Hence speedy moving sequences are delivered with a more fluid, sharper and smoother picture than 50 hertz or even 100 hertz TVs.

Additional benefit for photosensitive epilepsy sufferers

Scientific studies have proven that for patients with photosensitive epilepsies 100Hz televisions can help prevent seizures when playing video games or watching Tv.

Armadeus Cornelius is an AV enthusiast and expert with nearly 20 years experience in consumer electronics.His website at www.digitaldirect.co.uk offers 100Hz and 200Hz TVs and a large selection of AV products at rock bottom prices. For your convenience you may also find these links useful Televisions 100Hz and 37 LCD 100Hz TV

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