2. Turning On and Off DC Component of the Developing Bias and Controlling theVoltage LevelThe developing DC bias ON command (DPON*) generated by the DC controller isused to turn on and off the DC component of the developing bias. The level of the voltageis controlled by the DC bias control command (DCBC).• When the DC component of the developing bias is on,DPON*=0→The remote circuit turns on.→The amplifier circuit turns on.→The DC drive circuit turns on.→The DC high-voltage transformer turns on. (developing DC biasoutput)• When the developing bias DC component is off,DPON*=1→The remote circuit turns off.→The amplifier circuit turns off.→The DC drive circuit turns off.→The DC high-voltage transformer turns off.As shown in Figure 4-109, the voltage level of the DC component of the developingbias is controlled by varying the voltage of the DCBC command (analog) generated bythe DC controller to suit the setting (output from the AE sensor) of the Copy Density key.The level of the DC voltage generated by the high-voltage power supply varies accordingto the level of the DCBC command.With the exception of during copying operation (SCFW), the machine applies a DCbias of about -320 V, thereby preventing undesirable adhesion of toner in areas betweensheets of copy paper and fogging in copy images.Figure 4-1094-12CHAPTER 4 IMAGE FORMATION SYSTEMCOPYRIGHT © 1997 CANON INC. CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)F1 F9-100-500Developing DC bias (V)Copy density
