Measuring The Concentration Of Black Toner (Patch Detection) - Canon CLC 1120 Service Manual

CHAPTER 6 IMAGE FORMATION SYSTEM
The following is the flow of operations used to control the concentration of black toner:

3. Measuring the Concentration of Black Toner (patch detection)

A sample black toner image (patch image) formed on the photosensitive drum is measured
using a LED and a sensor, and the result is read as the black toner concentration signal and the
reference signal. Then, a comparison is made of these signals, window dirt correction value, and
initial value stored in RAM to compute the change in concentration.
The following is the flow of operations used to measure the concentration of black toner:
*When measuring the concentration of color toner, SGNL-M/C/Y and REF-M/C/Y are
measured.
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COPYRIGHT © 1999 CANON INC.
Copy Start key ON
for every copy
Measures the concentration of black copies.
Determines the amount of black toner to
supply according to the change in concentration.
Sets the initial developer concentration signal (SGNL-K/D) and
initial reference signal (REF-K/D) (at time of installation,
replacement of developer or toner concentration sensor)
Copy Start key ON
Rotates the photosensitive drum.
Forms a sample image on the photosensitive drum.
LED ON (shines on the photosensitive drum)
Measures the concentration of developer for copying operation
(SGNL-K/D) and
Measures the reference (REF-K/D) for copying operation.*
Compares the initial data and copy data, and
Computes the change in toner concentration
CANON CLC1120/1130/1150 REV.0 MAR. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)