Print Signal Flow - Canon BJC-8500 Service Manual

Part 4: Technical Reference

1.4 Print Signal Flow

The following describes an outline of the print signal flow from when the printer
receives the print signals sent from the host computer up to when printing is executed.
a) When the host computer sends the print signals (print data and control commands)
to the printer, the print signals are received by the printer controller from the
interface, which is controlled by the printer controller.
b) The printer controller stores the print signals in the DRAM's receive buffer via the
special bus.
c) The MPU reads the print signals from the DRAM's receive buffer, and separates the
print signals into print data and control commands based upon the program in
control ROM. The MPU then processes the control commands based upon the
program in control ROM.
d) The MPU expands the print data in the DRAM's print buffer.
e) The printer controller converts the print data to serial data for each of the BJ cartridges,
and outputs the serial data to the BJ cartridges together with the control commands.
The drive circuits in the BJ cartridges convert the serial data to parallel data, and
control ink ejection based upon the control signals.
f) The MPU and the printer controller control the entire printing process by detecting BJ
cartridge and printer states, and controlling the motor drivers.
Computer
Drive Circuit
BJ Cartridge
• Black cartridge
• Color cartridge
• Photo cartridge
: Print data
: Control commands
/signals
Host
a
e
f
Figure 4-6 Print Signal Flow
Printing control on this printer is compatible with Canon extended (native)
mode. The emulation and soft emulation modes are not supported. For
this reason, print signals converted to Canon extended mode by the
printer driver are sent from the host computer.
b
c
Printer
Controller
d
e
c
d f
c
f
MPU
f
4-6
BJC-8500
DRAM
Receive
Buffer
Print
Buffer
Control ROM
Motor Drivers
Sensors
Logic Board