Toshiba 1550, Service Manual

Page: 125 / 212

1550/1560 DEVELOPER 10 - 12 Mar. 1998 © TOSHIBA
Operation of auto-toner sensor
(1) Functions of auto-toner sensor
A
Initialization adjustment function:
– When new settings are entered or when developer is replaced. –
Automatic or semi-automatic adjustment is made so that the output of the auto-toner sensor
will be 2.3 – 2.5 V (input of IC8) against the toner density of the new developer material.
B
Toner density stabilization function:
– During copying operation –
• Toner consumption
→
toner density decreases
→
auto-toner sensor output changes are
detected
→
toner motor is driven
→
toner is supplied to developer unit from toner cartridge.
~ The toner density is maintained at a constant level.
C
Toner-empty detection and release function:
• Detects toner-empty state inside toner cartridge
~ Drives toner motor
→
auto-toner sensor output is not changed
→
toner density does not
change
→
judges that there is no toner (toner empty)
• Release of toner-empty state
~ Toner cartridge replacement
→
drives toner motor
→
auto-toner sensor output changes
→
toner density returns to normal value
→
toner-empty state is released.
(2) Operation of auto-toner sensor
The auto-toner sensor is composed of the following circuits:
• Drive winding: Magnetic head which receives a high-frequency magnetic field (primary
side). When placed in developer material, it 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 emitted from the detection winding
to a DC signal.
644474448
644474448
Auto-toner output VATS
V
ATS
Drive
winding
Magnetic circuit
Auto-toner
output
To microprocessor
DC
conversion
circuit
Detection
(Developer
material)
Magnetic
resistance