Canon 1000 Service Manual page 160

3. OPERATION AND TIMING
Various measurement data units may be checked in service mode.
Control display mode (DISPLAY)
Item
SGNL-S-K
REF-S-K
f. Checking the Dirt on the Window
The LED is turned on during last rotation (LSTR) after copying operation so as to measure the light
reflected from the photosensitive drum without toner on it (SGNL-D-K).
If the sensor window is soiled at this time, the value of SGNL-D-K will be small. The ratio of the
measurement to the initial value (as determined by SINIT-K) is stored in memory as the correction value and
used to correct the output of the SALT sensor.
If the measurement SGNL-D-K is 60% or less of a specific value, 'E020' will be indicated.
3-116
COPYRIGHT © 2001 CANON INC.
Developer density (DENS)
Description
Light reflected by toner layer
Intensity of direct light
Table 3-506
Photosensitive drum
Photo diode
Figure 3-546
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
Reference
192 to 352
464 to 544
Dirt on sensor window
LED