DEVICE FOR BLOCKING VLF ELECTRIC FIELD RADIATED FROM CRT OF VIDEO DISPLAY SYSTEM

摘要

PURPOSE: A device for blocking VLF(Very Low Frequency) electric field radiated from a CRT of a video display system is provided to detect the electric field with a flyback transformer and apply it to an antenna set at the corner of the CRT to offset electric field formed around the CRT. CONSTITUTION: A device for blocking VLF electric field radiated from a CRT(12) of a video display system includes a signal detector(13) one end of which is connected to the secondary coil of a flyback transformer(11) to detect anode voltage, and an inversion-amplifier(14) for inversion-amplifying the detected anode voltage. The device further includes a buffer(15) for correcting waveform of a flyback pulse to apply the pulse to a signal mixer(16). The signal mixer mixes the flyback pulse with the inversion-amplified signal. An output amplifier(17) amplifies the output signal of the signal mixer to generate negative electric field through an antenna(T1) so as to block electric field radiated from the front side of the CRT.