Canon iR2016 Series, Service Manual

Page: 178 / 406

Chapter 5
5-4
T-5-5
5.2.1.3 Horizontal Synchronization Control
0010-7721
iR2016 / iR2020 / iR2016i / iR2020i
The purpose of this control is to adjust the position where scanning starts in the horizontal direction (main scan direction) of the image with reference to the hori-
zontal synchronization signal (/BD) sent from the BD sensor in the laser scanner. The horizontal synchronization signal is also used as a vertical synchronization
signal to recognize the leading edge of paper. Upon detection of arrival of the fed paper at the prescribed position, the DC controller PCB starts sending the /BD
signal to the image porcessor PCB. The image processor PCB recognizes the leading edge of paper at the start of the continuous /BD signal; it recognizes the trailing
edge of paper at the end of the continuous /BD signal.
Memo:
About Generation of BD Signal
The BD sensor on the BD circuit board receives only the beam of laser B; it does not receive the beam of laser A. The BD signal is generated from the beam of
laser A.
5.2.1.4 Horizontal Synchronization Control
0011-2156
iR2016J /
The purpose of this control is to adjust the position where scanning starts in the horizontal direction (main scan direction) of the image with reference to the hori-
zontal synchronization signal (/BD) sent from the BD sensor in the laser scanner. The horizontal synchronization signal is also used as a vertical synchronization
signal to recognize the leading edge of paper. Upon detection of arrival of the fed paper at the prescribed position, the DC controller PCB starts sending the /BD
signal to the image porcessor PCB. The image processor PCB recognizes the leading edge of paper at the start of the continuous /BD signal; it recognizes the trailing
edge of paper at the end of the continuous /BD signal.
5.2.2 Controlling the Intensity of Laser Light
5.2.2.1 Automatic Photocurrent Control (APC)
0010-7722
iR2016J / iR2016 / iR2020 / / iR2016i / iR2020i
The purpose of this control is to monitor the laser beam emitted to the photodiode on the laser driver circuit board in order to adjust the light quantity.
5.2.3 Controlling the Laser Scanner Motor
5.2.3.1 Laser Scanner Motor Control
0010-7723
iR2016J / iR2016 / iR2020 / / iR2016i / iR2020i
From the moment the laser scanner motor starts to the moment it reaches the target revolution speed, the revolution speed is controlled with reference to the laser
scanner motor revolution speed signal (FG signal). After the target revolution speed is reached, the revolution speed is controlled so that the BD cycle and the laser
scanner motor revolution cycle are in the same phase.
The revolution speed of the laser scanner motor is controlled using an acceleration signal (ACC signal) and deceleration signal (DEC signal).
Laser control signal Laser
status
Description
CTL2 CTL1 CTL0 Laser A
0 0 0 OFF Laser control OFF
0 0 1
ON Laser beams can be emitted in
response to video signals.
0 1 0 ON APC over laser
0 1 1 OFF Forced stop of laser emission