White Plate Dust Detection Control - Canon iR C6800 Series Service Manual

Chapter 5
If it finds dust at all 5 points (A, B, C, D, E), then it will indicate an alarm when an original is placed in the ADF,
prompting the user for cleaning. To reset, press [close].
When it starts a job, it will run the session once again and use a point with no dust or little dust as the reading position.
*1: reading position at the end of the previous job.
*2: point with no dust or little dust.
A reading reference position (1.0 mm to the left from the center of the platen roller)
B 1.0 mm to the left from the reference position
C 0.5 mm to the left from the reference position
D 0.5 mm to the right from the reference position
E 1.0 mm to the right from the reference position (center of the platen roller)
between sheets (dust correction)
The machine does not move the xenon lamp for dust detection.
If dust is detected between sheets, the machine executes dust correction by making correction on the pixels on both
sides of the area where dust is found.
MEMO:
COPIER>OPTION>BODY>DFDST L1 (level 1)
(adjustment of dust detection level between sheets)
COPIER>OPTION>BODY>DFDST L2 (level 1)
(adjustment of dust detection at job end)

5.3.5.2 White Plate Dust Detection Control

1. Overview
The machine uses a fan to cool the inside of the reader unit to prevent overheating otherwise caused by the xenon
lamp in stream reading mode. The fact, however, can cause stray dust inside the reader unit to collect on the white
plate, showing up as lines in output images.
<Timing of Control>
1 Before a Job
white plate dust detection
white plate dust correction
2 After a Job
white plate dust detection
white plate dust correction
5-18
Start key
ON
1st
SCAN
Dust detection
T-5-8
2nd
SCAN
Dust detection
F-5-29
0003-4293