POWER SOURCE UNIT OF VIDEO APPARATUS

摘要

PURPOSE:To make a power source unit small-size and light without giving bad influences to video by making the switching period of the power source circuit into a prescribed value. CONSTITUTION:The commercial AC output passing through rectification smoothing circuit 2 is switched at a period such as frequency (2m+1)/2XfH where AC-DC converter 3, where the level controlling feedback signal dependent upon the comparison between the reference voltage of comparison circuit 7 and the commercial AC output above and the feedback control signal outputted from oscillator 10 and pulse width modulator 9 are applied, is interleaved to horizontal synchronizing frequency fH of video signals, and becomes a fixed-polarity pulse voltage including no harmonic components which give influences onto video in a prescribed level at a prescribed frequency. As a result, a DC output for video apparatus including ripple which does not influence visually is generated from rectification smoothing circuit 5.