Canon LBP-1210 Service Manual page 108

CHAPTER 2
B. Video Interface Signals
Interface controller
PCB
J2-8
-5
-7
-6
-10
-11
• /BD (laser beam detection) signal
This signal is a synchronous signal of the horizontal scanning (main scanning): it is a reference
signal of a laser beam in the horizontal direction. It is also a clock signal of a laser beam in the
vertical direction, since it functions as a synchronous signal of the vertical scanning (sub scan-
ning).
After a speeified period from the /BD signal input, the sends the video signals, synchronized
with the /BD signal, to the laser driver to align the leading edge of an image with that of print
paper. It also adjusts the horizontal direction of the image.
• /RESET signal
This signal initializes the interface controller when the print is turned ON.
• SC (status command) signal
This signal is a bi-directional signal for serial data transmission/reception between the interface
controller and engine controller. Using this signal, the engine controller and the interface con-
troller transmit and receive status and commands.
• SCLK (serial clock) signal
This signal is a synchronous clock output from the interface controller when the engine con-
troller and interface controller transmit/receive status and commands. The commands are syn-
chronized with the falling edge of this signal, whereas the status is synchronized with the rising
edge.
• CNT0 / CNT1 (laser control) signals
These signals are output from the engine controller to the laser driver PCB through the inter-
mediate PCB. Refer to "IV. LASER/SCANNER SYSTEM" for more details.
• /ACC (scanner motor acceleration) / /DEC (scanner motor deceleration) signals
The engine controller sends these signals to the scanner motor through the intermediate PCB.
Refer to "IV. LASER/SCANNER SYSTEM" for more details.
• /BDI (laser beam input) signal
2 - 22
Intermediate PCB
J902-5 J907-11
-8 -14
-6 -12
-7 -13
-3 J901-8
-2 -9
Figure 2-3-2
Engine controller PCB
/BD J201-12
/RESET -9
SC -11
/SCLK -10
Laser driver
PCB
/VDO J801-3
VDO -2