Toshiba 4580, Service Manual

Page: 215 / 379

6570/5570 DEVELOPER UNIT 12 - 12 Mar. 1999 © TOSHIBA TEC
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12.5.2 Operation of auto-toner sensor
(1) Functions of auto-toner sensor.
1
Initialization function:
-When the copier is set up or when the developer material is replaced-
Automatic or semi-automatic adjustment is made so that the output of the auto-toner sensor
(input value of the main CPU) will be 2.45 to 2.55V for the toner density of new developer mate-
rial.
2
Toner the density stabilization function:
-During the copying operation-
•
Toner consumption
→
toner density decreases
→
detection that the auto-toner sensor output
changes
→
toner motor drive
→
supply of toner to the developer unit from the toner hopper.
∼
Maintains toner density at a constant level.
3
Toner-empty detection, release function:
•
Detects toner-empty situation inside toner hopper
~ Drives toner motor
→
auto-toner sensor output is not changed
→
the toner density does not
change
→
judges that there is no toner (toner empty).
•
Release of toner-empty situation.
~ Toner supply
→
driving the toner motor
→
auto-toner sensor output changes
→
returning of toner
density of normal value
→
toner-empty release.
(2) Mechanism of auto-toner sensor.
The auto-toner sensor is composed of the following circuits.
•
Drive winding: Magnetic head with a high-frequency magnetic field (primary side).
Placed in developer material and forms magnetic circuit.
•
Detection winding: Receives the changes in magnetic resistance of the developer material via a
magnetic circuit (Secondary side).
•
DC conversion circuit: Converts the high-frequency output from the detection winding to a
DC signal.
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Auto-toner output V
ATS
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Magnetic
resistance
Magnetic circuit
(Developer
material)
Drive winding
Detection
winding
V
ATS
To
main LGC
Auto-toner
output
DC
conversion
circuit