Canon Color imageRUNNER C4580, Service Manual

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Chapter 9
9-23
F-9-17
9.5.4 Discharge Current Level Control
- The machine controls the level of discharge current so as to ensure the optimum level in keeping with changes
in temperature/humidify. (The term "discharge current"refers to the current that occurs between the primary
charging roller and the photosensitive drum.) The current is controlled to a level that enables prevention of
faulty images in a high humidity environment and, at the same time, permits collection of toner remaining
from transfer to the developing assembly. Operation
1. An AC bias is applied to the primary charging assembly; the level of current occurring at the time is measured
by the high-voltage PCB (HV1-SUB) and is sent to the CPU on the DC controller PCB as feedback.
2. The roller is charged using the AC charging bias corrected by the CPU.
- Frequency of AC Bias on Primary Corona Roller is adjustable by its Processing Speed
9.5.5 ATVC Control (transfer bias level correction)
The ATVC control mechanism is used to determine the optimum level of transfer voltage for transfer of images
from the photosensitive drum to the ITB, and from the ITB to paper.
The level of transfer voltage is corrected in relation to changes in temperature/humidity, deterioration of rollers,
and types of paper.
Description of Control
1. A reference voltage is applied to the transfer roller, and the level of current that occurs in response is checked
by the high-voltage PCB and communicated to the CPU on the DC controller PCB as feedback.
2. The machine executes transfer using a transfer voltage which is the result of correction by the CPU.
T-9-20
Item Description
Primary transfer Applies a reference voltage to the primary charging roller.
Uses the high-voltage PCB (HV-2) to check the level of current, and the result is fed back to the
CPU for determination of the optimum level.
Secondary transfer Applies a reference voltage to the secondary transfer external roller.
Uses the high-voltage PCB (HV-3) to check the level of current, and the result is fed back to the
CPU for determination of the optimum level.
SALT sensor
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M
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Bk