Canon Color Bubble Jet BJC-2000 Series, Service Manual

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BJC-2000
Part 4: Technical Reference
Buffer controller
The buffer controller automatically writes the received data to the receive buffer in
the DRAM, manages the remaining capacity of the print buffer, and clears the data
after it is read.
Print head controller
The print head controller converts the print data read from the DRAM's print buffer
from parallel to serial and sends it to the print head. At the same time, the printed
dots are counted for the variable control of the Heat-enable (H ENB) signal pulse
width.
The head-driving signals consist of the block enable signals (B ENB 1, 2, 3),
odd/even enable signals (OddENB/EvenENB), and heat enable signals (H ENB 0, 1,
2, 3). The block enable signals and odd/even enable signals specify the block for
time-shared drive. The heat enable signals control the eject heater's conduction
time.
I/O port
Signals for the setting statuses determined by the RESET button , cover open switch,
head temperature sensor, head ID, paper end sensor, home position sensor, and
pick-up roller sensor are input through the input ports.
Signals for operations such as BJ cartridge detection and head-driving voltage
control are output from the output ports.
2) Control ROM (IC4)
The 8 M-bit control ROM contains the printer control program .
3) DRAM (IC5)
Controlled by the MPU & Printer controller, the 4 M-bit DRAM is used as a print
buffer and working area.
4) Reset IC (IC2)
This IC detects the power voltage when power on or instantaneous power failure
occur and resets the MPU & Printer controller.
5) EEPROM (IC1)
Controlled by the MPU & Printer controller, the 1 K-bit EEPROM (Electrically
Erasable and Programmable ROM) stores various function settings such as the total
count of printed sheets and the total waste ink amount.
6) Paper feed motor driver (IC7)
Controlled by the MPU & Printer controller, the paper feed motor driver drives the
paper feed motor (controlled by the two-phase exciter) with a constant-voltage
unipolar drive. The driving IC has four identical circuits.
7) Carriage motor driver (IC6)
Controlled by the MPU & Printer controller, the carriage motor driver drives the
carriage motor (controlled by the one to two-phase exciter) with a fixed current
bipolar drive. In accordance with the switching signal from the MPU & Printer
controller, the peak current value is set to five steps and driven.
The driving IC has two identical circuits.