Scanner Unit
○Purpose: Here we study the control performed by the scanner
motor unit.
1. Outline
The scanner motor unit reflects the laser beams by a revolving
polygon mirror, irradiating the beams onto the photosensitive
drums.
The scanner motor unit is controlled by the DC controller. When the
scanner motor unit receives a drive signal from the DC controller, it drives the
scanner motor to turn the polygon mirror.
Below, we explain the part configuration of the scanner motor unit.
1] Scanner Motor Unit
[2] Polygon Mirror
[3] Scanner Motor
[4] SD Circuit Board
-The MAIN CHG signal is used only
with the iR3570/4570 models
(not with the iR2270/2870 models).
Next, we explain the control performed by the scanner motor
unit.
2. Scanner Motor Revolution
Control
a. Outline
This control turns the scanner motor with a target number of
revolutions (motor speed).
The revolution of the laser scanner motor is driven by a scanner
motor acceleration signal (ACC) and a scanner motor deceleration signal (DEC)
sent from the DC controller. The number of revolutions of the scanner motor is
detected by the scanner motor speed signal (/P FGOUT), which is the feedback
signal from the scanner motor unit.
Below we explain the sequence of the scanner motor.
1) When printing begins, the DC controller sends out an ACC signal to
accelerate the scanner motor.
2) The DC controller monitors the /P FGOUT signal to check whether
the target motor speed has been attained by the scanner motor.
3) Once the scanner motor has reached its target motor speed, the
controller sends either an ACC signal or a DEC signal in order to stabilize the
number of revolutions of the scanner motor at the target motor
speed.
4) When the printing is completed, the DC controller
sends a DEC signal to decelerate the scanner motor.
If a printing command is given while the scanner motor is
decelerating, the DC controller immediately sends an ACC signal to re-start the
scanner motor.
b. Speed Control
The scanner motor of the iR3570/4570 models is equipped with two
speed settings: "High Speed" and "Low Speed."
The switching between these two settings is carried out by a
speed-switching signal (MAIN CHG).
When the scanner motor driver receives the MAIN CHG signal from the
DC controller, it switches the target speed of the scanner
motor.
Because the iR3570/4570 models are equipped with two types of feeding
speed (normal speed and low speed), the motor speed of the scanner motor also
needs to be switched according to the feeding speed.
3. Failure Detection
This unit also detects any failures of the scanner motor.
Conditions of failure are described
below:
a. Conditions of Failure
1) BD Error
Image-formation is enabled (i.e., the scanner motor is operating
normally and the laser is emitted), but the cumulative number of times the unit
fails to detect BD signal input has reached a certain fixed
value.
2) Scanner Motor Failure
∙ The scanner motor is turned on, but its target motor speed is not
reached after a certain period of time.
∙ The scanner motor has transitioned to its normal motor speed, but the
scanner motor has deviated from its target motor speed for a period of
time.
∙ The scanner motor speed has been switched, but the its target motor
speed is not reached after a certain period of time.
b. Measures to Take
1) BD Error
The error message "E100-0000" is shown, disabling the
printing.
2) Scanner Motor Failure
The error message "E110-0001," "E110-0002," or "E110-0003" is shown,
disabling the printing.
c. Method of Repair
1) BD Error
If it happens frequently, replace the laser scanner unit or the DC
controller.
2) Scanner Motor Failure
Replace the laser scanner unit or the DC
controller.
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