purity coil

purity coil

[′pyu̇r·əd·ē ‚kȯil]
(electronics)
A coil mounted on the neck of a color picture tube, used to produce the magnetic field needed for adjusting color purity; the direct current through the coil is adjusted to a value that makes the magnetic field orient the three individual electron beams so each strikes only its assigned color of phosphor dots.
References in periodicals archive ?
Separate purity coils for each of the four corners of the screen, which helps to ensure accurate color from edge to edge.