Toshiba e-studio550 Service Manual page 217

14. 5. Fuser Motor Drive
14. 5. 1. Outline of operation
Wave
shaping
Reference
frequency
(HTRCK)
HTRML
Control
HTRMT
signal
(1) The LGC transmits control signals for the fuser motor rotation (HTRMT:Motor rotation command).
(2) The excited phase switching unit excites each phase on the fuser motor.
(3) Hall elements A to C are used to detect the rotation position of the motor (or rotor).
(4) The excited phase switching unit switches the excitation for each phase. (By repeating steps (2)
through (4) above, the motor keeps rotating.)
(5) An FG pulse is generated by the rotation of the fuser motor.
(6) The phases and velocities of the FG pulse and the reference frequency from the LGC are compared,
and the differences are added up. In addition to this are added the fluctuations in the supply voltage
(Signal generation).
(7) The switching timing for the excited phase switching unit is changed to match the signal obtained in
step (6). That is, control ensures that the FG pulse and reference frequency are equal.
motor rotates at a constant speed (locked range state).
(8) When the HTRML signal changes to "H" level, the fuser motor stops rotating.
(9) During standby, the HTRML level changes to "L" if the temperature of the pressure roller drops below the
reference temperature, and the fuser motor rotates at a low speed.
JUNE 2002 © TOSHIBA TEC
+5.1V
Difference
Phase
comparator
Current
detecting
Speed
circuit
comparator
Difference
Rotation
control
M/DC-HTR-340N
14 - 11
+36A
Excited
W
phase
switching
A
unit
Roter
position
detection
Fuser motor
U, V, W : Phase
A, B, C : Hall element
Fuser motor rotates.
e-STUDIO550/650/810 FUSER UNIT
FG pulse
V
U
C
B
The fuser