Charging Mechanism; Controlling Pre-Exposure Led; Pre-Exposure Led Control; Primary Charging Mechanism - Canon imageRUNNER 5065 series Service Manual

Chapter 7
Purpose: to obtain the density suited to the user's needs.
Method of correction: uses the developing bias and image processing (binary density processing) according to the F-value setting.
F value
1
2
3
4
5
2. Adjusting the Density for Printing
The machine increases the developing bias to increase the print density. If increased in excess, the background can develop fogging. At the lower limit of the de-
veloping bias, the machine uses the changes in the developing bias and image processing (thickening processing) to ensure appropriate density.
Purpose: to obtain the density suited to the user's needs.
Method of correction: uses the developing bias and image processing (thickening) to suit the F-value setting.
F value
1
2
3
4
5
6
7
8
9
*1: Thickening processing may be enabled for all F values in user mode ('correct fine line').

7.5 Charging Mechanism

7.5.1 Controlling Pre-Exposure LED

7.5.1.1 Pre-Exposure LED Control

iR5065 / iR 5055 / iR5075 / / /
The machine is equipped with a pre-exposure LED used to prevent adhesion of excess toner on the photosensitive drum because of residual charges. The following
is an item associated with the pre-exposure LED control system:
1. turning on/off the pre-exposure LED
The following is the signal associated with the mechanism:
[1] Pre-exposure LED control signal; when '0', LED goes on

7.5.2 Primary Charging Mechanism

7.5.2.1 Overview

iR5065 / iR 5055 / iR5075 / / /
The following items are associated with the primary charging control system:
1. turning on/off the primary corona current
2. controlling the constant current level of the primary corona current
3. controlling the constant voltage level of the grid bias (fixed to 850 V by a valista)
The following shows the construction of the control system associated with the primary charging control system:
7-8
Developing DC bias standard value
(V)
240
220
180
140
120
Developing DC bias standard
value (V)
218
205
194
182
170
153
137
120
120
24V
PRE_LED_ON* [1]
T-7-5
Shift (V) Image processing
60 yes
40 no
0 no
-40 no
-60 yes
T-7-6
Shift (V) Thickening*1
48 no
35 no
24 no
12 no
0 no
-17 no
-33 no
-50 no
-50 yes
Pre-exposure lamp
F-7-13
Image density
lighter
darker
Image density
light
dark
0015-4487
0015-4488