3 ] Head/Carriage Unit - Brother MFC620CN Service Manual

[ 3 ] Head/carriage unit
The head/carriage unit consists of a front end (ink-jet head) and a back end (buffer and air vent
unit).
The front end consists of metal plates laminated together and etched to form ink flow channels.
(See illustration.)
Piezoelectric ceramic actuators generate the spray pressure. The response of individual front ends
to applied voltages and waveforms varies, however, because of the nature of piezoelectric materials,
fluctuation in manufacturing accuracy, and other factors. The front end therefore leaves the
production line with a bar code giving property data. The manufacturer writes this data to the
EEPROM on the main PCB incorporating this unit to insure consistent performance without
fluctuations.
These labels appear on the head/carriage unit itself and on the lower cover of the machine.
Replacing the head/carriage unit requires writing 12 of the 13 property data digits on the label
included with the new unit into the EEPROM with maintenance mode function code 68 and
applying the new property label on the lower cover. Replacing the main PCB requires similar
property data updates.
Front end
Metal plates
Nozzle plate
Piezoelectric plate
Filter
COF
Front end ASSY
osses
3-13
Property label for
head/carriage unit
Property code
(13-digit)
Head/carriage unit
Confidential