Toshiba e-STUDIO520 Service Manual page 260

2) Auto-toner sensor drive circuit
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 cir-
cuit 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 out-
put ATS-1A)
Developer material
Magnetic resistance
Magnetic circuit
- When the toner density is low:
Toner ratio to the carrier in the developer material decreased
o Magnetic resistance decreased
o Detection output increased
o Auto-toner output ATS-1A increased
- When the toner density is high:
Toner ratio to the carrier in the developer material increased
o Magnetic resistance increased
o Detection output decreased
o Auto-toner output ATS-1A decreased
e-STUDIO520/600/720/850 DEVELOPER UNIT
Drive Detection
winding winding
Auto-toner sensor
DC
conversion
circuit
Fig.12-8
12 - 14
output
To the main-CPU
( LGC board )
ATS-1A
March 2005 © TOSHIBA TEC