Toshiba e-studio550 Service Manual page 180

12. 4. 2. Developer motor
Wave
shaping
DEVCK
Reference
requency
Control
DEVON
signal
(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 (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 com-
pared, 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.
JUNE 2002 © TOSHIBA TEC
5.1V
Phase
Difference
comparator
Current
detection
circuit
Speed
comparator
Difference
Rotation
control
12 - 7
+24VA
Excited
W-phase
phase
switching
unit
A
Roter
position
detector
e-STUDIO550/650/810 DEVELOPER UNIT
FG pulse
V-phase
U-phase
C
B
Developer motor
(M13)
A, B, C: Hall element