Cathode ray tube apparatus having a protection circuit for protecting a cathode ray tube driving circuit and a method therefor

摘要

A cathode ray tube display apparatus having a protection circuit which cuts off supply of a synchronization signal, i.e., the horizontal and/or vertical synchronization signals, to a cathode ray tube driving circuit in response to a state signal indicating when frequencies of the synchronization signals exceed a limited range. The protection circuit prevents the cathode ray tube driving circuit from being damaged by abnormal variations in the frequencies of the synchronization signals.