Scanner System - Canon LBP-1210 Service Manual

C. Scanner System
Figure 2-4-4 shows the scanner motor control circuit.
Engine controller PCB
IC201
CPU
+24VA
/ACC 70
Frequency
comparator
/DEC 69
Standard
clock
X201
X1 14
Oscillator
X0 13
The scanner motor is a 3-phase DC brushless motor with a built-in Hall device. This motor is
unified with the drive circuit.
When the printer is turned ON, the CPU (IC201) on the engine controller divides the oscilla-
tion frequency of the crystal oscillator (X201) in order to generate a reference clock.
When a print command is sent from the interface controller, the CPU sets the SCANNER
MOTOR ACCELERATION (/ACC) signal "L". With this /ACC signal set "L", the scanner driver IC
starts rotating the scanner motor. The scanner motor keeps accelerating its rotation speed as
long as the signal remains "L".
The CPU forces laser to emit while the scanner motor is rotating. With this scanner motor
rotation, the /BDI signal is sent from the BD sensor to the CPU via the intermediate PCB. The
CPU controls the rotation number of the scanner motor comparing the /BDI signal cycle with
the reference clock in the frequency comparator installed in the CPU. The rotation number is
brought to its specified value by controlling the /ACC signal. This operation lasts until the scan-
ner motor reaches its specified rotation number. To stop the scanner motor, the /DEC signal is
set "L" to decelerate the motor's rotation.
The CPU judges whether the scanner motor is rotating at the specified speed by detecting the
/BDI signal.
Intermediate PCB
J201-16 /BDI J907-7 J901-7
J201-19 J907-4 J905-1 J802-1
J201-22 /ACC J907-1 J905-2
J201-21 /DEC J905-3
J907-2
J201-20
J907-3 J905-4
Figure 2-4-4
Laser/scanner unit
J801-7
BD sensor
+24VA
Scanner driver IC
J802-2
Integration
circuit
J802-3
J802-4
Scanner motor
CHAPTER 2
Drive
circuit
M
2 - 33