Canon 1130 Service Manual page 196

Each item of measurement data may be checked in service mode as follows:
Item
PT-SIG-K
PT-SIG-D
PT-REF-K
PT-REF-D
Unlike Y, M, or C toner, the copier's black toner absorbs near infrared light. As
such, the amount of black toner inside the developer cannot be detected by
REF.
shining near infrared light to the developer.
The photosensitive drum, on the other hand, reflects near infrared light, and
shining infrared light to a black toner image on the photosensitive drum will
enable detection of the concentration of toner.
The density of a black toner image will decrease (lighter) as the amount of black
toner inside the developer decreases, and the degree of reflected light will
increase.
Photodiode for
generation of
reference signal
COPYRIGHT © 2002 CANON INC.
Description
Bk toner concentration signal (Bk-SGNL)
Bk reference signal (Bk-REF)
Table6-405
Photosensitive
drum
LED
Re-
flecting
mirror
Photodiode for
measuring reflected light
Figure 6-405
CANON CLC1100/1130/1150/1160/1180 REV.2 FEB. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 6 IMAGE FORMATION SYSTEM
338±150
614±150
818±41
818±41
BK-SGNL
BKLAON
BK-REF
Adjustment value
DC driver PCB
RAM
SGNL initial value
REF initial value
Rate of
amplification
6-37