SCREEN CONTROL SYSTEM OF PORTABLE TV

摘要

The device for automatically switching broadcasting channels based on the broadcasting mode includes: a microcomputer 10 for comparing a data value resulting from counting input sync signals with a reference value and generating a predetermined control signal; a switching means 20 for selectively outputting a composite video signal based on composite video signals of SECAM-L or a composite video signal of the other broadcasting modes according to the control signal; a composite video signal processing means 30 for inverting or buffering the selected composite video signal; and a sync signal detecting means 40 for detecting the presence of a sync signal out of the output signals from the composite video signal processing means 30 and outputting a detection signal to the microcomputer 10.