Sharp AR-651 (serv.man15) Service Manual ▷ View online
AR-651/810 DEVELOPER UNIT 12 - 9
12. 5. Auto-toner Sensor Circuit
12. 5. 1. General description
(1) Functions of auto-toner circuit
• Detection of the toner density in the developer material
~ density lowered toner supplied
• Detection of the toner being empty in the toner cartridge
(2) Configuration of auto-toner circuit
• Auto-toner sensor
: Detecting the toner density
• Control section
: Controlling to keep the developer material toner density constant
• New toner supply motor
: Supplying new toner to the developer material
• Display unit
: Displaying the toner empty status
• Recycle toner hopper motor
: Supplying the recycle toner to the developer material
촞
BC-RAM
IC32
CPU
IC6
GA
IC27
PWA-SYS
PWA-LGC
CPU
IC58
IC58
95C063F
GA
IC56
LCA301
IC18
MB88347
TA8428
IC38
TA8428
IC37
Control panel
New
toner
toner
Toner
motor
motor
Auto-toner sensor
Developer material
Developer unit
Toner cartridge
Control
voltage
signal
Toner density signal
D/A
converter
Operation/control section
Display unit
Hopper
motor
motor
Recycle
toner
toner
Recycle toner hopper
Main
AR-651/810 DEVELOPER UNIT 12 - 10
12. 5. 2. Operation of auto-toner sensor
(1) Functions of the auto-toner sensor
a. Initializing function: When the copier is set up or when the developer material is replaced
The 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 material.
b. Toner density stabilizing function: During the printing operation
Through the following phases, the toner density is kept constant.
Toner consumed
촞
Toner density decreased
촞
Output change of the auto-toner sensor depending on the humidity detected
촞
Recycle toner hopper and new toner supply motor driven
촞
Toner supplied to the developer unit from the recycle toner hopper and toner cartridge
c. Toner-empty detection, release function
Toner-empty detection in the toner cartridge.
New toner supply motor driven
촞
Output of the auto-toner sensor not changed
촞
Toner density not changed
촞
Toner-empty detected
Toner-empty release
New toner supply motor driven
촞
Toner supplied from the toner cartridge
촞
Output of the auto-toner sensor changed
촞
Toner density recovering to its normal value
촞
Toner-empty released
(2) Operation of the auto-toner sensor
The auto-toner sensor is composed of the following circuits.
Drive winding
: Magnetic head (primary side) with a high-frequency magnetic field,
which forms a magnetic circuit in the developer material
Detection winding
: Receiving the changes in the magnetic resistance of the developer
material via a magnetic circuit (secondary side)
DC conversion circuit : Converting the high-frequency output from the detection winding to a
DC signal
Magnetic resistance
Drive
winding
Detection
winding
DC
conversion
circuit
conversion
circuit
(Developer material)
Magnetic circuit
Auto-toner output
Main CPU
(LGC)
V
ATS
AR-651/810 DEVELOPER UNIT 12 - 11
When the toner density is low:
Toner ratio to the carrier in the developer material decreased
촞
Magnetic resistance decreased
촞
Detection output increased
촞
Auto-toner output V
ATS
increased
When the toner density is high:
Toner ratio to the carrier in the developer material increased
촞
Magnetic resistance increased
촞
Detection output decreased
촞
Auto-toner output V
ATS
decreased
AR-651/810 DEVELOPER UNIT 12 - 12
12. 6. Disassembly and Replacement
[A] Toner cartridge drive unit
(A-1) Toner cartridge drive unit
(1) Open the front cover and take off the toner
cartridge and front side inner cover.
(2) Loosen 1 screw and take off the bracket.
(3) Disconnect 1 connector.
(4) Pull down the fixing pin and turn it 90 degrees.
(5) Pull out the toner cartridge drive unit about 30
degrees and take it off toward the direction of
the arrow.
(A-2) Toner cartridge switch
(1) Disconnect 2 connectors, remove 2 screws
and take off the toner cartridge switch.
(A-3) New toner supply motor
(1) Remove 3 screws and take off the top cover.
(2) Disconnect 1 connector, remove 2 screws
and take off the new toner supply motor.
Fixing pin
Top cover
New toner
supply motor
supply motor
Connector
Toner cartridge switch
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