The primary charging bias is generated to charge the surface of the photosensitive drum to an even negative potential as preparatory work for image formation.

The bias is generated by the primary charging AC high-voltage generation circuit and the primary charging DC high-voltage generation circuit of HVT1.

The primary charging AC high-voltage generation circuit is used to generate the AC bias applied to the primary charging roller. It generates 4 types of biases

(PRI_AC_Y, PRI_AC_MJ, PRI_AC_C, PRI_AC_Bk), independent among individual colors.

The primary charging DC high-voltage generation circuit is used to generate the DC bias applied to the primary charging roller. It generates 2 types of biases

(PRI_DC_YMC, PRI_DC_Bk) for color and Bk.

The AC and DC biases that have been generated by these circuits are combined at such times as specified for application to the primary charging roller of the drum

unit.

The level of the primary charging bias varies in keeping with the instructions from the DC controller.

7.2.3 Generation of the Developing Bias

/ / / / iR C3380i / iR C3380 / iR C2880i / iR C2880

The developing bias is used to retain toner over the static image formed on the surface of the photosensitive drum.

The bias is generated by the 2 circuits of HVT1: developing AC high-voltage generation circuit and DC high-voltage generation circuit.

The developing AC high-voltage generation circuit is used to generate the AC bias applied to the developing cylinder, producing 2 types of biases for color and Bk

(DEV_AC_YMC, DEV_AC_Bk).

The developing DC high-voltage generation circuit is used to generate the DC bias applied to the developing cylinder, producing 2 types of biases for color and Bk

(DEV_DC_YMC, DEV_DC_Bk).

7-10

[3]

[2]

[1]

[4]

[6]

[8]

HVT1

[5]

[7]

[9]