Generating Primary Charging Bias; Generating Developing Bias; Generating Transfer Bias; Overview - Canon LBP6000 Series Service Manual

Table of Contents

Engine controller

CPU

2.4.2.2 Generating Primary Charging Bias

LBP3100 / LBP3010B

The primary charging bias (PRI) is a DC negative bias that is output to apply an even negative potential to the surface of the photosensitive drum. The primary

charging high-voltage generating circuit in the high-voltage power supply circuit generates this bias.

The high-voltage power supply circuit applies the generated primary charging bias to the primary charging roller at a specified timing.

The primary charging bias varies in conjunction with the developing bias according to the information of image density sent from the main controller.

2.4.2.3 Generating Developing Bias

LBP3100 / LBP3010B

The developing bias is a DC negative bias that is output to affix toner to the static latent images formed on the photosensitive drum. This bias is a development DC

and AC superimposed bias and generated by the development high-voltage generating circuit in the high-voltage power supply circuit.

The high-voltage power supply circuit applies the generated developing bias to the developing cylinder at a specified timing.

The developing bias varies in conjunction with the primary charging bias according to the information of image density sent from the main controller.

2.4.2.4 Generating Transfer Bias

LBP3100 / LBP3010B

Transfer bias (TR) is a bias that is output to transfer toner to papers. There are two types of bias; DC positive bias and DC negative bias, and generated by the transfer

high-voltage generating circuit in the high-voltage power supply circuit. The DC positive bias is output at the time of toner transfer, and the DC negative bias at the

time of cleaning the photosensitive drum.

The high-voltage power supply circuit applies the generated transfer bias to the transfer roller according to each print sequence.

Each print sequence is described below.

- Cleaning bias:

The bias to move (clean) the toner attached to the transfer roller to the photosensitive drum at the time of warming up or last rotation sequence.

The transfer negative bias is applied to the transfer roller.

- Paper intervals bias:

The bias to prevent the toner remained on the photosensitive drum from attaching to the transfer roller at paper intervals during continuous printing. A minor

transfer positive bias is applied to the transfer roller.

- Print bias:

The bias to transfer the toner on the surface of the photosensitive drum to papers at the time of print sequence. The transfer positive bias is applied to the transfer

roller.

2.4.2.5 Overview

LBP6000 / LBP6000B

This circuit is comprised of the circuits that apply biases to the primary charging roller, developing cylinder, transfer roller, and the fixing control circuit. The CPU

of the engine controller controls the high-voltage power supply circuit to generate these biases. The fixing control circuit executes heater control of the fixing as-

sembly according to the instruction by the CPU of the engine controller.

The following is the block diagram of this circuit.

High-voltage power supply

Primary

charging

high-voltage

generation

circuit

Developing

high-voltage

generation

circuit