Electrical Signal Conversion (Moving Picture)

Television cuts an image from a TV camera into thin thread-like slices, and transmits them one at a time sequentially. At the receiving end these slices are collected, arranged in order, and displayed on a cathode ray tube. This allows as many as 30 still pictures to be recorded per second and projected in succession, giving the appearance of motion.

How Does a Television Work? Sending (TV Camera) An optical image is captured in the form of varying densities of electrons and electrical charges from which it can be converted into stronger or weaker current and voltage levels forming an electrical signal (video signal).The image taken by the camera is divided into 525 lines, which are sent one at a time as the video signal. The lines into which the image is divided are called raster lines.

Receiving (Cathode Ray Tube) The cathode ray tube or CRT consists of an electron gun, a control unit and a fluorescent screen. An electron beam controlled by the video signal is directed at the fluorescent screen where it projects the video image by generating light according to the form of the video signal.

	Return to the Gakushukan Home Page
	Back	Forward