| 摘要 |
PURPOSE:To prevent the display of an abnormal wave form part when delay sweep is finished, by a method wherein an unblanking period is finished in synchronous relation to the termination of a main sweep unblanking period and a sweep termination pulse is delayed by a delay circuit. CONSTITUTION:When a delay sweep signal generating circuit 3 initiates sweepage in response with a delay sweep trigger pulse and the sweep termination pulse from a main sweep signal generating circuit 1 is inputted through a delay circuit 2, a sweep signal change-over circuit 4 selects a main sweep saw tooth wave A and a delay sweep saw tooth wave D to supply the same to a horizontal shaft amplifier circuit 5. On the other hand, an unblanking signal control change- over circuit 6 supplies a main sweep unblanking signal F to a brightness circuit 7 in a main sweep mode and, in a delay sweep mode, it is generated only for a period when both of delay sweep and main sweep unblanking signals are simultaneously generated. By this mechanism, even if an abnormal wave form part is generated by a delay sweep termination pulse, it is not displayed on a CRT tube surface. |
