Canon Color iR C3480, Service Manual

Page: 216 / 774

Chapter 6
6-10
F-6-11
6.2.3 Controlling the Laser Scanner Motor
6.2.3.1 Controlling the Speed of the Laser Scanner Motor
0013-8536
Color iR C3380G / Color iR C2880G / Color iR C3380i / Color iR C3380 / Color iR C2880i / Color iR C2880 / iR C3480 / iR C3480i / iR C3080 / iR C3080i / iR
C2550
The machine controls the laser scanner motor so that it rotates at a specific speed.
The control mechanism is governed by the motor speed control block and the reference signal generation block according to the instructions from the CPU of the
DC controller.
The motor speed control block compares the speed detection signal (FG, BD) against the reference signal generated by the reference signal generation block to
control the acceleration signal (ACC) and the deceleration signal (DEC) so that the scanner motor rotates at a specific speed.
The machine uses 2 speed detection signals with the aim of helping the laser scanner unit last longer (Notes). The FG signal is a detection signal for coarse adjust-
ment used at time of motor start-up, while the BD signal is a detection signal used to fine-adjust the motor to the target speed.
The motor control mechanism operates as follows:
1) The DC controller turns on the ACC signal, thus causing the scanner motor to rotate.
2) The DC controller uses the result of FG signal detection to control the ACC signal and the DEC signal so that the motor will rotate at a specific speed.
3) The DC controller switches from the FG signal to the BD signal; then, using the result of BD signal detection, controls the ACC signal and the DEC signal
so that the motor will continuously rotate at the target speed.
Laser Driver IC
5V
PD
LD
LC_CTL_P3(1)
LC_CTL_P3(0)
D-CON
Laser
Relay
PCB
CBk- Laser Driver
Laser Driver IC
5V
PD
LD
LC_CTL_P4(1)
LC_CTL_P4(0)