3. OPERATION AND TIMINGCOPYRIGHT © 2001 CANON INC. CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)3-116Various measurement data units may be checked in service mode.Control display mode (DISPLAY)Developer density (DENS)Item Description ReferenceSGNL-S-K Light reflected by toner layer 192 to 352REF-S-K Intensity of direct light 464 to 544Table 3-506f. Checking the Dirt on the WindowThe LED is turned on during last rotation (LSTR) after copying operation so as to measure the lightreflected 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 themeasurement to the initial value (as determined by SINIT-K) is stored in memory as the correction value andused 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.Figure 3-546Photo diode LEDPhotosensitive drum Dirt on sensor window
