White Plate Dust Detection Control - Canon imageRUNNER 7095 Service Manual

Advise the user to clean the area where the CCD stops in stream reading if the message has appeared.
SERVICE MODE:
COPIER>OPTION>BODY>DFDST-L1 (level 1)
use it to adjust dust detection level between sheets
COPIER>OPTION>BODY>DFDST-L2 (level 1)
use it to adjust dust detection level at the end of a job

5.3.5.3 White Plate Dust Detection Control

The white plate can collect stray dust inside the reader unit, causing lines in images, and the machine is
equipped with a mechanism to check for dust on the plate and correct it to limit its effects on 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
Particulars of Control
- White Plate Dust Detection
The machine compares the data on the light reflected by the white plate at time of fixed shading and shift
shading to check for dust on the white plate while at the same time identifying the coordinates and width
of the area of dust.
- White Plate Dust Correction
If the machine detects the presence of dust, it corrects the shading correction coefficient of the area of dust
by means of a correction coefficient used for both sides of the area with dust, thus limiting the effects of
the dust.
White plate data correction
area at time of shift shading
Start key
ON
1st
SCAN
Dust detection control
White plate
Data on light reflected
Dust
by the white plate
(shift shading))
Point of white plate data
measurement at time of fixed shading
2nd
SCAN
Dust detection control
F-5-41
Data on light reflected
by the white plate
(fixed shading)
Comparison
Identifies the coordinates
of the start of dust and width
Correction Algorithm
The machine corrects the correction
coefficient of the area of dust using data
for areas on both sides
F-5-42
Chapter 5
0011-2231
5-19