Toshiba e-STUDIO281c Service Manual page 277

3) Operations of black auto-toner sensor
The black 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 (auto-toner output
ATS)
Developer material Developer material
Drive
Magnetic resistance Magnetic resistance
winding
Magnetic circuit
When the toner density is low:
Toner ratio to the carrier in the developer material decreases.
→ Magnetic resistance decreases.
→ Detection output increases.
→ Auto-toner output V
When the toner density is high:
Toner ratio to the carrier in the developer material increases.
→ Magnetic resistance increases.
→ Detection output decreases.
→ Auto-toner output V
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Detection
winding
Fig. 12-6
increases.
ATS
decreases.
ATS
12 - 7
Auto-toner sensor
DC
output
conversion
circuit
ATS
e-STUDIO281c/351c/451c
To the engine-CPU
( LGC board )
DEVELOPER UNIT
12