CHAPTER 4 IMAGE FORMATION SYSTEMCOPYRIGHT © 1999 CANON INC. CANON NP6317 REV.0 APR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON) 4-5III. PRIMARY/TRANSFER CORONA CURRENT ANDGRID BIAS VOLTAGE CONTROL SYSTEMA. OutlineThe circuit shown in Figure 4-102 controls the primary/transfer coronal current and the biasvoltage of the grid of the primary corona. Main functions are as follows:1. Switching primary/transfer corona current ON/OFF2. Maintaining primary/transfer corona current constant3. Switching primary corona grid bias voltage4. Switching primary corona grid bias ON/OFFIn order to eliminate the effect of changes in atmospheric conditions on the effectiveness of thecorona discharge, the current to the primary corona wire is maintained constant.The primary corona and transfer corona currents are switched ON and OFF by the HVT ONcommand (HVTON).The grid bias voltage is switched by the GRID ON signal (GRDON).B. Switching Primary/Transfer Corona Current ON/OFFa. When HVTON=1,Differential amplifier goes OFF.Variable pulse width oscillator goes OFF.High-voltage transformer goes OFF.b. When HVTON=0,Differential amplifier goes ON.Variable pulse width oscillator goes ON.High-voltage transformer goes ON.
