Toshiba 4580, Service Manual

Page: 211 / 379

6570/5570 DEVELOPER UNIT 12 - 8 Mar. 1999 © TOSHIBA TEC
[B] Developer motor drive
(1) The LGC transmits control signals for the developer motor rotation (DEVON: motor rotation com-
mand).
(2) The excitation phase switching unit excites each phase on the developer motor.
→
Developer motor
rotates.
(3) Hall elements A to C are used to detect the rotational position of the motor (or rotor).
(4) The excitation phase switching unit switches the excitation for each phase (By repeating steps (2)
through (4) above, the motor keeps rotating.).
(5) The FG pulse is generated by the rotation of the developer motor.
(6) The phases and velocities of the FG pulse and the reference frequency from the LGC are compared,
and the differences are added. Further to this are added the fluctuations in the power supply voltage
(Signal generation).
(7) Changes the switching timing for the excitation phase switching unit to match the signal amount
obtained in step (6).
That is, the FG pulse and reference frequency are controlled to be equal.
→
The developer motor
rotates at a constant speed (Locked range state.).
(8) When the DEVON signal changes to “H” level, the developer motor stops.
Phase
comparator
Voltage
detection
circuit
Rotation
control
Roter
position
detector
Excited
phase
switching
unit
Speed
comparator
Wave
shaping
Control
signal
Difference
Difference
Reference
requency
DEVON
DEVCK
+24VA
FG pulse
W-phase
V-phase
U-phase
A, B, C: Hall element
C
Developer motor
(M13)
B
A