Electromagnetic Deflection Coils

Deflection coils are electromagnetic coils that steer the electron beam in a cathode-ray tube or image pickup tube, produce magnetic fields. That changes with time and bends the path of the electron beam so that the phosphor dots, illuminated on the screen will change with a time in a pattern. These coils are ideal for application in crt displays like computer and television, and small coils are for audio and video recorder. Electromagnetic deflection coils are used in television crt construction because they do not have to penetrate the glass envelope of the tube, thus decreasing the production costs and increasing tube reliability. The internal coils are the horizontal deflection coils and the external coils are the vertical deflection coils. They are positioned to cause the magnetic field produced to be in vertical or horizontal plane. The coils that produce a horizontal field are called the vertical deflection coil and which produce the vertical field is called the horizontal deflection coil.