Consumer Electronics

THE SCANNING PROCESS

Scanning may be defined as the process which permits the conversion of information expressed in space and time coordinates into time variations only. Suppose, for extreme simplicity, that an optical image of a scene, perhaps on a photosensitive surface, is scanned by a beam of electrons, i.e. all points on the image are sequentially contacted by this beam, and that somehow, as a result of this scanning, through capacitive, resistive, or photoemissive effects at the surface, an electrical signal may be obtained that is directly proportional in amplitude to the brightness at the particular point being scanned by the beam. Although the picture content of the scene may be changing with time, if the scanning beam moves at such ...