The focusing of cathode ray tubes for television receivers

The object of the paper is to summarize the various effects which control the focus of a television picture from the point of view of a receiver designer. (Any effects connected with tube design are neglected.) The cause of deflection defocusing and the resultant aberrations are discussed and remedies set out The divergence of the focusing field from a convex lens and the effects of the position of the field on focus control are detailed. The effect of supply potential variation on E.H.T. and focus field are dealt with and finally E.H.T. supply regulation is considered.