PURPOSE: To attain miniaturization and light weight and to reduce noise generated at the transmission of charging signal, by operating a switching transistor (TR) just before the leading edge and trailing edge of a polarity inverting pulse so as to decrease the level of a signal current.
CONSTITUTION: A low pass filter is arranged between a contact of a polarity inverting relay and a channel, and switching TR is arranged between the polarity inverting relay and a power supply respectively and the switching TR is operated just before the pulse leading and trailing of the said polarity inversion. In inverting the polarity of the channel, since no current flows to the channel, no noise is generated. Then, the 2nd pulse is applied to a filter F and the collector current of a TR1 is decreased gradually. The line current is inverted through the polarity inversion in this case and an MP relay is restored while the current of the channel is zero. The noise is reduced remarkably by controlling the waveform of the current in this way, but a slightly rapid changing point remains in the waveform, which might cause a noise, then the waveform is smoothed further with an LPF.
ITOU SHIYOUJI
TAKASAKI TAKATOMO
NAGATO TAKASHI
Next Patent: EVALUATING SYSTEM OF PICTURE QUALITY