How do TVs work?

Answer 1

There are many resources that offer detailed and very technical descriptions of television technology. It is a complex system and there is space here for no more than a very brief summary.

Television cameras convert light into electrical signals. The signal they generate is a stream of data that represents the amount of red, green and blue in the image. The light coming into the camera is sampled at the top left of the image first and then all the way across the image to the right. The next samples will do the same but slightly lower. The process is repeated until the bottom of the image is reached and then the light sampling begins all over again. The number of lines that are sampled can be 480 or 576 for standard definition signals and 1080 for high definition. In either case, the signal that is output from the camera describes the image it sees 50 or 60 times each second.

Studios capture these signals and after they have been mixed with other camera outputs and titles, the signal is broadcast. It is carried over cable or radio links and received at the television.

The television uses the same signal to draw an image. Starting from the top left, the brightness levels in the electrical signal are used to produce red, green and blue dots across the screen. The next line is then drawn and so on down the screen until the image is complete. As soon as the image is drawn on the whole screen, the process starts over and it is this repeating process that creates the moving image.

There are many details of television signal capture, process and display that are left out of this description. For those who want to know more, topics that can be researched should include PAL and NTSC color encoding, interlaced television signals, SD and HD signal resolution, CRT television operation, LCD television operation and plasma television operation. There are numerous answers on this site that deal with some of these topics and of course there is lots more elsewhere on the internet.