Canon imagePRESS C1 P, Service Manual, Page: 337 / 1265

Chapter 6
6-3
3) DC controller PCB controls so that the laser scanner motor reaches its target rotation. At the same time, it forcibly emits the laser beam and detects troubles.
4) The preparation for the image formation is completed.
5) DC controller PCB produces the sub scan sync signal (See NOTE) for each color (PVREQ-Y, PVREQ-M, PVREQ-C, PVREQ-K) and sends them to the main
controller PCB.
6) The main controller PCB produces the video signal for each color based on the sub scan sync signal, send them to DC controller.
7) DC controller PCB turns on the laser beam according to the video signals.
- Basic sequence for 1-page print of full-color A4 standard paper
F-6-3
MEMO:
The sub scan sync signal (PVREQ signal) is the signal to match the toner image edge on the drum with the leading edge of the print paper.
In this machine, the timing of producing PVREQ signal varies according to the color mode.
- For full color mode
For full color mode, the image forming of four colors (Y, M, C, Bk) is necessary.
The image for each color is formed on ITB (intermediate transfer belt). To prevent color displacement, the positions of the leading edges should be matched.
For full color mode, ITBHP signal, which is the standard position for color adjustment, is detected from the ITB home position sensor when the image formation
becomes possible. PVREQ signal for each color is produced according to this signal.
- For monochrome
For monochrome, it is unnecessary to adjust color. When the image formation becomes possible, PVREQ signal is produced at the specified timing regardless
of the ITB home position signal (ITBHP signal).
6.3 Various Control
6.3.1 Controlling the Laser Activation Timing
6.3.1.1 ON/OFF Control
0012-6373
imagePRESS C1 P / imagePRESS C1 / imagePRESS C1+ (Printer) / imagePRESS C1+
The laser beam ON/OFF is performed at the laser driver PCB.
This circuit controls the laser beam ON/OFF according to the combination of the laser control signal sent from DC controller PCB.
T-6-1
[1] Start key ON (Print demand signal) [2] Laser Stop Operation
[3] Motor Stop Operation [4] Image Formation Possible
[5] Stopping [6] Accelerating
[7] Phase Control [8] At Stable Rotation
[9] Decelerating [10] A/B Laser
BD Detection/APC Control On
[11] APC Control [12] BD Detection/APC Control On
[13] Image for 1 Line [14] APC Control On
Laser control signal Operation status Laser status
CTL2A CTL1A CTL0A CTL2B CTL1B CTL0B ASW-A ASW-B
[1]
[4] [4] [4] [4]
[5] [6] [7] [8] [7] [8] [7] [8] [7] [8] [9] [5]
[10]
[11] [12] [13]
[14]
Scanner motor
ITB HP
PVREQ (Y,M,C,K)
BD
A Laser
B Laser
BD
A Laser
B Laser
K C M Y
[2] [3]