| 摘要 |
An apparatus of shielding a very low frequency (VLF) electric field on the front face of a cathode ray tube (CRT) in a video appliance. The apparatus includes a signal detection section, connected to the flyback transformer, for detecting an anode voltage applied to the anode of the CRT; an inversion-amplifying section for inversion-amplifying the anode voltage detected by the signal detection section; a waveform-shaping section for waveform-shaping the negative polarity pulse signal induced from the induction coil; a signal synthesizing section for synthesizing the negative polarity pulse signal inputted from the waveform-shaping section with an output signal of the inversion amplifying section; an output amplifying section for amplifying the synthesized negative polarity pulse signal inputted from the signal synthesizing section; and an open-loop antenna, mounted on a predetermined portion of the CRT, for radiating the synthesized negative polarity pulse signal inputted from the output amplifying section. The VLF electric field generated from the CRT is offset by the electric field caused by the synthesized negative polarity pulse radiated through the open-loop antenna.
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