B. Detecting the Level of Toner and Controlling the Supply
Operation
The toner inside the developing assembly is monitored by the toner sensor (TS2).
When the toner inside the developing assembly falls below a specific level while the
developing clutch (CL8) remains on during copying, the developing assembly toner level
signal (
) goes ‘0’ and is communicated to the DC controller.
When the DC controller has detected the developing assembly toner level signal
(
) for 0.3 sec or more, it sends the hopper motor (toner supply) drive signal
(M11ON), causing the hopper to supply toner.
When the toner inside the developing assembly has reached a specific value and the
DC controller PCB has detected the developing assembly toner level signal (
=1)
for 0.7 sec or more, the DC controller PCB stops the hopper motor 1 (M11).
If the toner sensor (TS2) goes out of order for some reason or if a fault in the hopper
prevents supply operation and, as a result, the DC controller detects the developing
assembly toner level signal (
=0) for 120 sec or more, the DC controller will indicate
‘E020’ and stop copying operation.
The level of toner inside the hopper is monitored by the hopper toner sensor (
)
while the hopper motor 1 (M11) is operating to supply toner or while toner is being stirred.
When the toner inside the hopper falls below a specific level, the hopper level
detection signal (
) goes ‘0’. When the DC controller PCB has detected the signal for
1 sec or more, it will indicate the Add Toner message on the control panel. At this time,
the Copy Start key on the control panel will change to red.
Figure 4-202
Developing assembly
toner level detection signal (DTEP)
Hopper toner level
detection signal (TEP)
INTR
Hopper motor 1 (M11)
Developing clutch
(CL8)
SCFW SCRV SCFW SCRV
LSTR
STBY
*1
*2
*3
Add Toner
message
Add Toner message
OFF
*1 Resumes supply operation when the developing assembly toner level detection signal
= 0 has been detected for 0.3 sec or more.
*2 Suspends supply operation when the developing assembly toner level detection signal
= 1 is detected for 0.7 sec.
*3 Drives the hopper for 2.0 sec and then holds it for 1 sec, supplying toner by repeating this sequence.
Copy Start key
ON
TEP
TS1
DTEP
DTEP
DTEP
DTEP
COPYRIGHT © 1997 CANON INC. CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
4-30
