| 摘要 |
PURPOSE:To enable to separate the vertical synchronizing signal more stable than the composite synchronizing signal, by combining two types of integration circuits and comparators. CONSTITUTION:The composite synchronizing signal v1 included with horizontal and vertical synchronizing signals is integrated at the integration circuit 1 having comparatively smaller time constant. Then, the output signal v2 having the waveform in which the wedge type opposite pulse SP' is inserted to the part corresponding to the notch pulse SP inserted in the vertical synchronism Vss, is output. Next, this output is compared at the comparator 2 having slightly lower threshold level TL-1 than the minimum level LL of the pulse SP' to output the signal v3. This is integrated at the integration circuit 3 having comparatively greater time constant to obtain the vertical synchronizing signal smooth like the signal v4. Further, as required, the pulse waveform can be shaped via the comparator 4. |
