| 摘要 |
PURPOSE:To separate electrically a television camera part and a power source part by means of a low-priced isolation transformer without fail by superimposing an output signal from the television camera part on a carrier at the prescribed frequency higher than that of a video signal component. CONSTITUTION:The oscillation frequency f0 of an oscillator 24 is set to a far higher frequency than the frequency hand of the video signal of the output signal of a CCD 14. A multiplier 22 AM-modulates (carrier suppression modulation) the output signal from the CCD 14 with the signal from the oscillator 24 as a carrier signal. Since the compared frequency width (=frequency width/ central frequency) of the output signal of the multiplier 22 is small, the isolation transformer 26 passes the output signal of the multiplier 22 without distortion. Thus the low-priced isolation transformer 26 can electrically separate the tip of an endoscope which is liable to contact a human body from a power source without fail, and a pressure proofing value and a leakage current value can lie within a safe range. |
