The density at the five points shown in Figure 4-109 is measured, and the results are
sent to the DC controller PCB, which in turn determines the intensity of the scanning
lamp during copying. (The points of measurement differ between right pick-up and left
pick-up.)
Figure 4-110 shows changes in the intensity of the scanning lamp in relation to the
density of originals.
If the density of a specific original is higher (darker) than the Test Sheet and lower
(lighter) than a newspaper, the intensity of the scanning lamp varies between F5 and F9
of copy density indication.
If it is lighter than the Test Sheet, the intensity will be an equivalent of F5; if it is darker
than a newspaper, the intensity will be an equivalent of F9.
Figure 4-109 Points of Measurement on an Original
Figure 4-110
Test Sheet
Newspaper
Lighter
F9
equivalent
F5
equivalent
Original
density
Darker
Scanning lamp intensity
about 100mm
25mm
98mm
L1
9
12 14.6 22.2
3
2
1
RDF feeding direction
(b) Right Pick-Up
RDF feeding direction
(a) Left Pick-Up
L2
L2
L2
L2
15~20mm
L1: about 32 mm (1st)
about 45 mm (2nd and subsequent; LTR)
about 41 mm (2nd and subsequent; A4)
about 30 mm (2nd and subsequent; B5)
about 32 mm (2nd and subsequent; others)
L2: 2.4 mm (1st)
4.8 mm (2nd and subsequent)
COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
4-9