Canon iR5570 Series, Руководство по обслуживанию

Страница: 188 / 684

Chapter 6
6-4
6.3 Various Controls
6.3.1 Controlling the Laser Activation Timing
6.3.1.1 Generating the Sync Signal
0009-4068
The BD signal used to synchronize the video signal in laser scanning direction is generated by the BD PCB with reference to the laser beam reflected by
the BD mirror mounted on the laser beam optical path. The CCD/AP PCB reads the image signal from the CCD, and sends it to the controller block. The
controller block, in response, executes image processing, and sends the result as a video signal to the laser driver PCB by way of the DC controller PCB
and as the laser intensity control signal to the laser unit.
6.3.1.2 Flow of the Sync Signal
0009-4069
[1] BD signal (upon detection of laser light, '0').
[2] phase matching is executed with reference to the printer, and the synch signal is generated.
[3] reads the image data from the image memory in keeping with the printer sync signal.
[4] video signal
[5] converts the 2-pixel parallel signal into a signal-pixel serial signal.
[6] laser drive signal (drives the laser unit according to the video signal).
F-6-3
ERROR DODE:
E100
Issued when the BD signal is not detected within a specific period of time after the laser has been turned on.
6.3.2 Controlling the Intensity of Laser Light
6.3.2.1 Controlling the Laser Intensity
0009-4070
The laser driver circuit serves to drive the semi-conductor laser with reference to the laser drive signal (LD) coming from the DC controller PCB.
The laser drive circuit is associated with the following items of control:
1. laser activation control
2. laser intensity control (APC control)
3. laser intensity control to suit the drum surface potential
The various signals have the following meanings and functions:
[1] laser drive signal
[2] sample laser activation signal; for each scan, it turns on the laser for sampling of light intensity (for imaging)
[3] laser activation enable signal; after the Start key has been pressed, it goes '0'when the laser is ready for activation.
[4] laser write start signal; when paper reaches the laser write start sensor (PS28) mounted in front of the registration roller, the machine starts laser write
operation.
[5] the machine monitors the intensity of laser light upon its activation (for sampling), and feeds the appropriate value to the laser drive circuit.
[6] the machine controls the output so that the value that has been fed and the reference value from the DC controller are identical.
[7] laser intensity reference signal; it serves as the laser activation reference (determined as a result of potential control by the DC controller).
BD PCB
DC controller
PCB
BD* [1]
J2701 J116
J1015
J122
J122 J117
J101
J1015
GND
5V
VIDEO [4] LD [6]
PHSYNC[3]
4
3
2
1
A20
1
2
3
4
Laser
drive PCB
Control block
Sync
signal
generation
[2]
Parallel/
serial
conversion
[5]
Memory
control
A21