Print Head - Brother MP-21C Service Manual

3.2

Print Head

This is an on-demand ink jet printer and ejects ink by the firing of a piezoelectric ceramic
actuator. Refer to Fig. 2.13 for the print head structure. A narrow channel filled with ink is
sandwiched between two actuators. When a voltage is applied to an electrode formed on
the surface of the actuator, ink is pulled into the channel from the manifold with the
actuator deformed as shown in the Fig. 2.13. When the voltage becomes 0, the actuator
returns to the previous position and pressure is generated in the ink in the channel. Thus,
the nozzle ejects ink drops. Ink drops are propelled forwards by this action and are fired
onto the paper held by the platen and form dots of the respective color. This printer
incorporates thirty-two ink firing mechanisms per color as explained above, 2 colors per
head with 2 print heads, 126 in total.
Piezo
Ceramic
< Head Specifications >
(1) Method
(2) Driving frequency
(3) Injection droplet amount
(4) Composition
(5) Number of ink
(6) Number of nozzles
Dummy channel
Channel
Nozzle plate
Fig. 2.13
PZT(Xaar) method with the dummy channel
3.85 KHz, 6.5 KHz, 7.7 Khz
Normal mode
Super fine mode
Separate color type
4 colors (Y/M/C/K)
128 nozzles (32 nozzles x 4 colors)
II-12
Piezo
:40 ± 5pl
:25 ± 2.5pl
Ink
Manifold