Scanning Coils of Television

Actually the main duty of the video section is to scan the picture on the screen so that the viewers can watch them. For this only purpose the vast arrangement is needed. The scanning coil is the most important component for the video section. It is located on the base of the CRT. The electron beam produced by the electron gun is finally directed by the scanning coil with different frequencies. The scanning coil is nothing but just a device to produce magnetic field. This magnetic field deflects the electron beam to and fro. We know that the scanning process is analogous to writing on the paper with a pen. That is, it needs to go first towards horizontally and then vertically. For these purposes there need two different coils. One is horizontal scanning coil and another is vertical scanning coil. These two coils are named as ‘Yoke’ together. This yoke is fixed outside the tube and close to the neck of the tube just before it begins to flare out. For two different types scanning there need two different types of scanning coil. One is the horizontal and another is the vertical scanning coil.

Horizontal scanning coil:

                 The scanning coil which is used to move or deflect the electron beam from left to right or from right to left of the tube is called the horizontal scanning coil. It is split in two sections and mounted above and below the beam axis. The frequency at which he horizontal scanning coil moves from left to right and back to left again is 15750HZ or 15625HZ (considering 525 lines for a successive pair of fields).

Vertical scanning coil:

                  The scanning coil which is used to move or deflect the electron beam from top to bottom or bottom to top is called the vertical scanning coil. It is also split into two sections mounted in the left and right of the neck of the CRT. It gradually pulls the beam downward while the horizontal scanning coil sweeps the beam across the face of the CRT. It operates in low frequencies (50 to 60 HZ).