Principle Television

1. Television

The English word ''Television'' is said to be derived from the Greek ''Tel''( long distance) and the latin ''Vidio''(see) . In Japan, the word ''Television'' is now used as a japanese language, as well as so called ''Te-re-bi'' or TV.
We are aware that movie picture is moving little by little, though it consists of separated still picture. It seems as it is moving by rapid replacement of still picture one after another. It is because of after image, ( the characteristic that, when you are seeing some image, the image will be left even after it di sappears suddenly ). The image will stand still for a moment, 0.05―0.1 seconds, but it looks as a continous motion without any break because of the after image . Scenes of movie are replaced 24 times per second, while those of television, 30 times.

2. Picture element
In general, the element which composes one picture is called picture element . When we watch a picture on newspaper, other printed matters, etc , we can see a lot of small dots, bright and dark, making a picture, which is called picture element in camera processing .

3. Decomposition and composition of picture
But it is imposible to change one scane into electric signal whole at a time . In fact, one scane decomposed into the lot of picture element and one element having a certain brignes is changed into one electrical signal. This consecutive electric signals ( video signal ) are transmitted on the waves .and on the receiving side, the signals are received to be composed ìn the same order as decomposition. In addition, both the starting point and speed of the decomposìtion and composition should agree to each other completely.