Canon BJC 6000 - Color Inkjet Printer, Service Manual

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4.2.2 Logic Components
a) Printer controller
The printer controller incorporates the interface controller, print head controller,
buffer controller, DRAM controller, stepping motor controller and I/O ports and
operates in sync with the 25MHz external clock input.
Interface controller
Receives 8-bit parallel data sent from the host computer in sync with the data
strobe pulse (STROBE) through BUSY/ACKNLG handshake. Data received from
the interface will be stored in the receive buffer in the DRAM and analyzed by the
printer controller.
Print head controller
Reads the print data from the DRAM's print buffer and converts this parallel data
into serial data to send to the print head. At the same time, it counts the printing
dots needed to control the variable pulse width of the Heat ENABLE signal
(Pre/Main pulse width).
The printer controller's head drive signals include the Odd/Even ENABLE signal,
Block ENABLE signal, Heat Select signal, and Heat ENABLE signal. The printer
controller uses the Odd/Even ENABLE signal, Block ENABLE signal, and Heat
Select signal to select the discharge heaters inside the nozzle by time sharing, and
varies the pulse width of the Heat ENABLE signal to determine how long the
discharge heater to be heated should remain driven. When the head drive voltage
is on, the printer controller also uses the HDATA signal to send the head ID, rank
resistor value as 6-bit serial input data from BJ cartridges.
Part 4: Technical Reference
BJC-6000
4-38
ROM
CN401
CN402
CN602
CN603
CN404
DRAM
MPU
Printer Controller
Buzzer
EEPROM
TH201
CN403
Cover Sensor
Paper End Sensor
POWER Switch
RESUME Switch
LED
Motor Driver
Figure 4-33 Control Board