TABLE OF CONTENTS The emission and control of electron streams is essential to the technologies of television. The electron gun is a critical element of all cathode ray tube (CRT) devices. Furthermore, the control of electron beam scanning is an integral part of all tube-based video cameras and all CRTs.
There are two basic methods of deflection of an electron beam in a vacuum device:
A transverse electrostatic field
A transverse electromagnetic field
The choice of electrostatic or electromagnetic deflection is influenced by a number of factors including:
The required electron beam deflection speed. At deflection intervals of less than 10 s, electrostatic deflection is usually considered superior to electromagnetic deflection. At deflection intervals of less than 5 s, electrostatic deflection is used almost exclusively.
Electron beam spot size. High-resolution displays typically utilize electromagnetic deflection systems. For applications requiring resolution of more than 600 television lines, and for luminance above 150 candela per square meter, electromagnetic deflection is preferred because of the higher accelerating potential that may be used. This higher potential permits smaller practical spot size and higher luminance output from the CRT.
Tube geometry. Devices using electromagnetic deflection are typically shorter than their electrostatic deflection counterparts. A wide-angle magnetic deflection tube can be 30 percent shorter than an equivalent electrostatic deflection device.
Electron optics and deflection systems are key technologies that enabled the first all-electronic (i.e., nonmechanical)...
