Canon LBP5050 Series, Service Manual

Page: 34 / 104

Chapter 2
2-8
F-2-14
2.4.3 Image Stabilizaton Control
2.4.3.1 Overview of the Image Stabilization Control Mechanism
0019-4455
LBP5050N / LBP5050
The machine uses its image stabilization control mechanism to prevent lowering of image quality (e.g., in the form of a faulty image) otherwise caused by changes
in the environment or deterioration of the photosensitive drum or toner.
The machine's image stabilization control mechanism may be any of 3 types: Image density corrective control (D-max control), Image halftone corrective control
(D-half control), Color Misregistration Corrective Control.
2.4.3.2 Image density correction control (D-max control)
0019-4457
LBP5050N / LBP5050
This control is to stabilize the image density of the printer engine.
If the prescribed condition is met, DC controller PCB performs D-max control in the following procedure.
1. Measure the each density detection pattern made on the ITB.
2. According to the measured density of each pattern, controls the primary charge bias and developing bias to get the appropriate density.
The following is the conditions that trigger the image density correction control
- When the power is ON
- When replacing the toner cartridge
- After replacing the toner cartridge, when the number of print exceeds the specified number (per 200 sheet)
- When the environment is changed drastically
- After printing, the specified time (300 min) elapses
ITB
TR1_1
TR1_23 TR1_23
TR1_4
TR2
ICLB
BLD1 BLD2 BLD3 BLD4
DEV1 DEV2 DEV3 DEV4
PRI
ICLR
Photosensitive drum
Primary transfer pad
DC controller
High-voltage power supply
Primary charging
high-voltage
generation circuit
Developing
high-voltage
generation circuit
Primary transfer
high-voltage
generation circuit
Cartridge
Secondary transfer
high-voltage
generation circuit
ITB cleaning brush
high-voltage
generation circuit
ITB cleaning roller
high-voltage
generation circuit
Blade
high-voltage
generation circuit
Secondary
transfer roller
ITB cleaning unit