Measuring The Concentration Of Black Toner (Patch Detection) - Canon 1130 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.
*See 4. "Detecting Dirt on the Window."
The following is the flow of operations used to measure the concentration of black toner:
*When measuring the concentration of color toner, PT-SIG-M/C/Y and PT-REF-M/C/Y are
measured.
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COPYRIGHT © 2002 CANON INC.
Start key ON
Detects dirt on the window
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 (P/D-SGNL-K)
and initial reference signal (P/D-REF-K) (at time of installation,
replacement of developer or toner concentration sensor)
Start key ON
Rotates the photosensitive drum.
Detects dirt on the window
Forms a sample image on the photosensitive drum.
LED ON (shines on the photosensitive drum)
Measures the concentration of developer for copying operation
(PT-SIG-K/D) and
Measures the reference (PT-REF-K/D) for copying operation.*
Compares the initial data and copy data, and
Computes the change in toner concentration
CANON CLC1100/1130/1150/1160/1180 REV.2 FEB. 2002 PRINTED IN JAPAN (IMPRIME AU JAPON)