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CHAPTER 4 IMAGE PROCESSING SYSTEM
4-14
COPYRIGHT
©
1999 CANON INC. CANON imageRUNNER 600 REV.1 JAN. 2000 PRINTED IN U.S.A.
2. Density Adjustment during Printing
The image data is in binary form when printing starts, and the data does not possess density
information. To adjust the density of images during printing, the copier corrects the laser intensity
and the developing bias as follows:
Table 4-302 Correction Table for Scanner Input
Table 4-303 Correction Table for PDL Input
Laser power
correction value
Vdc correction
value
1
9
3
5
7
-20V
F value
Density
Darker
Lighter
×0.8
×1.0
×1.2
×1.5
The developing bias is reduced earlier than the laser
power to prevent fogging.
Corrects the laser powerand the developing bias
according to the selected F value.
The laser power is increased to
ensure firm toner deposit.
The developing bias is not increased
to prevent fogging.
1
2
3
4
5
6
7
8
9
×0.8
×0.9
×1.0
×1.1
×1.2
×1.3
×1.4
×1.5
×1.5
+40V
+30V
+10V
+20V
Density
Darker
Lighter
The bias is corrected to increase
the contrast.
Laser power
correction value
Vdc correction
value
VD correction
value
F value
The laser power is increased for
F=5 (standard laser power) as
compared with the level used for
scanner input to ensure reproduction of
fine lines narrower than a single pixel.