Canon LASER SHOT LBP-1210, Руководство по обслуживанию

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C. Scanner System
Figure 2-4-4 shows the scanner motor control circuit.
Figure 2-4-4
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.
CHAPTER 2
2 - 33
M
X0
70
69
14
13
J801-7
/ACC
/DEC
X1
X201
IC201
CPU
J901-7
J905-1 J802-1
J802-2
J802-3
J905-2
J905-3
J802-4
J905-4
J201-16 J907-7
J907-4
J907-1
J907-2
J907-3
J201-19
J201-22
J201-21
J201-20
/ACC
/DEC
/BDI
Engine controller PCB
BD sensor
Oscillator
Standard
clock
Frequency
comparator
Laser/scanner unit
Integration
circuit
Drive
circuit
Scanner driver IC
Scanner motor
Intermediate PCB
+24VA
+24VA