Canon Color imageRUNNER C5180 Series, Service Manual, Page: 186 / 851

Chapter 6
6-19
(2) 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)
6.3.5.2 White Plate Dust Detection Control
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.
1. Timing of Control
(1) Before a Job
(a) white plate dust detection
(b) white plate dust correction
(2) After a Job
(a) white plate dust detection
(b) white plate dust correction
F-6-29
2. Particulars of Control
(1) White Plate Dust Detection
The machine compares the shading coefficient obtained from shift shading and the shading coefficient
obtained from fixed shading to identify the presence/absence of dust and, if any, coordinates and width of
the area.
(2) White Plate Dust Correction
If the machine detects dust as a result of white plate dust detection, it corrects the shading coefficient of
the area using the shading coefficient of both sides so as to decrease the effects of the presence of dust. It
executes shading correction using the coefficient it obtains after correction.
If the result of white plate dust detection indicates the presence of dust, the shading coefficient of the area
in question will be corrected by the coefficients of its adjacent areas during shading correction with the
aim of reducing the effects of the presence of dust. Thereafter, shading correction will be executed using
the corrected coefficient.
Dust detection
Dust detection
Start key
ON
1st
SCAN 2nd
SCAN