Main Motor Control Circuit - Toshiba e-STUDIO167 Service Manual

9.4

Main Motor Control Circuit

The main motor, which is a DC motor driven by control signals from the MAIN board, drives the drum,
developer unit, feed roller, transport roller and registration roller. A driving PC board is embedded in this
motor to perform the following controls.
MAIN board
+24VCOV-OFF
+5V
MMTRCKA
SoC
MMTRPLL-1
MMTRCCW-1
MMTRBK-0
ASIC
MMTR-0
1) The ASIC outputs the control signals for the main motor rotation.
(MMTR-0 signal: Motor rotation command, MMTRCCW-1 signal: Rotation direction)
2) The main motor is rotated by the excitation phase-switching section exciting each phase of the main
motor.
3) Hall elements A, B and C detect the rotation position of the motor (rotor).
4) The excitation phase-switching section switches the excitation of each phase.
(The motor keeps rotating by repeating from 2 to 4.)
5) An FG (Frequency Generator) pulse is generated by the rotation of the motor.
6) The FG pulse and the reference clock (MMTRCKA) from the SoC are compared in terms of the
phase and speed, and the difference is added to the excitation phase-switching section. Fluctua-
tions in the power supply voltage are also added to the value.
7) According to the result of step 6, the switching timing of the excitation phase-switching section is
changed and the FG pulse and the reference clock are controlled to make them equal. This will
make the main motor rotate at a constant speed. (Lock range)
8) When the motor is in the lock range, the excitation phase-switching section outputs the MMTRPLL-1
signal in the "L" level to the ASIC.
9) When MMTRBK-0 signal from the ASIC becomes "L" level, the motor is braked. When the MMTR-0
signal becomes "H" level, the motor is stopped.
e-STUDIO167/207/237
DRIVE UNIT
Main motor
Wave
Phase
correction
comparator
Speed
comparator
Lock
protection
circuit
[ ]
PC board section
+5V +24VCOV-OFF
Difference
Voltage
detection
circuit
Excitation
phase
switching
section
Difference
Rotation
Rotor
control
position
detection
Fig. 9-2
© February 2007 TOSHIBA TEC CORPORATION All rights reserved
9 - 4
[ ]
Motor section
FG pulse
Phase V
Phase W Phase U
A C
B
Hall elements