Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-09-30
2004-09-28
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06796638
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet head for applying pressure to pressure chambers and thus ejecting ink drops from nozzles, and in particular to a multi-nozzle ink jet head for performing lead out of electrodes from a row of piezoelectric bodies using a laminate of the elements.
2. Description of the Related Art
An ink jet recording head has nozzles, ink chambers, an ink supply system, an ink tank, and transducers; by transmitting displacement/pressure generated by the transducers to the ink chambers, ink particles are ejected from the nozzles, and characters or images are recorded on a recording medium such as paper.
In a well-known form, a thin-plate-shaped piezoelectric element having the whole of one surface thereof bonded to the outer wall of an ink chamber is used as each transducer. A pulse-like voltage is applied to the piezoelectric element, thus bending the composite plate comprising the piezoelectric element and the outer wall of the ink chamber, and the displacement/pressure generated through the bending is transmitted to the inside of the ink chamber via the outer wall of the ink chamber.
A sectioned perspective view of a conventional multi-nozzle ink jet head
100
is shown in FIG.
21
. As shown in
FIG. 21
, the head
100
is constituted from a row of piezoelectric bodies
111
, individual electrodes
112
that are formed on the piezoelectric bodies, a nozzle plate
114
in which are provided nozzles
113
, ink chamber walls
117
made of a metal or a resin that, along with the nozzle plate
114
, form ink chambers
115
corresponding to the nozzles
113
, and a diaphragm
116
.
A nozzle
113
and a piezoelectric body
111
are provided for each ink chamber
115
, and the periphery of each ink chamber
115
and the periphery of the corresponding part of the diaphragm
116
are connected together strongly. A piezoelectric body
111
for which a voltage has been applied to the individual electrode
112
deforms the corresponding part of the diaphragm
116
as shown by the dashed lines in the drawing. As a result, an ink drop is ejected from the nozzle
113
.
Application of voltages to each of the piezoelectric bodies
111
is carried out separately using electrical signals from a printing apparatus main body via printed circuit boards.
FIG. 22
is a drawing showing the constitution of connections between the conventional head and the printed circuit boards. In the example of
FIG. 22
, the head
100
has 8 rows and 8 columns of nozzles
113
, i.e. of piezoelectric bodies
111
and individual electrodes
112
. Corresponding to this, flexible printed circuit boards
110
are provided for connecting the driver circuitry of the apparatus and the individual electrodes
112
together.
In this prior art, the terminals of the printed circuit boards
110
are connected to the respective individual electrodes
112
by wires
120
through wire bonding. Moreover, art in which an FPC wiring board is connected directly is also known.
Moving on, due to demands to increase printing resolution, there are demands to increase the density of the nozzle arrangement of heads. If the nozzle density is raised, then the contact spacing between terminals (individual electrodes) is reduced. For example, the nozzle density of a head using piezoelectric bodies is currently about 150 dpi, but is advancing to 180~300 dpi, and further to 360 dpi, and hence the contact spacing is becoming lower. However, currently the best contact spacing with wire bonding using semiconductor manufacturing is 150 dpi, with 300 dpi contacts being developed in the case of FPC connection.
Consequently, if electrical connection is carried out by providing contacts on top of or near to the piezoelectric bodies
111
as conventionally, then a problem of joining of neighboring contacts (shorting) may arise. Moreover, when connecting a large number of points in a short time, the load on the piezoelectric bodies
111
becomes very high, and with thin-film piezoelectric bodies there is a risk of breakage, and hence connection is extremely problematic.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a multi-nozzle ink jet head for carrying out connection at a position away from the driving parts of the pressure chambers, thus preventing there being an effect on the driving characteristics even if a load is applied during the connection.
Moreover, it is another object of the present invention to provide a multi-nozzle ink jet head for preventing a lag in the driving operation of the piezoelectric bodies relative to the input waveform even though the led out wiring parts have a piezoelectric body actuator laminated structure.
Furthermore, it is yet another object of the present invention to provide a multi-nozzle ink jet head for preventing expansion and contraction of the piezoelectric bodies at the led out wiring parts even though these wiring parts have a piezoelectric body actuator laminated structure.
To attain these objects, one form of the multi-nozzle ink jet head of the present invention has a head substrate in which are formed a plurality of nozzles and a plurality of pressure chambers, a diaphragm that also acts as a common electrode and covers the plurality of pressure chambers, piezoelectric body layers that are provided in correspondence with the pressure chambers on the diaphragm, individual electrode layers that are provided on the piezoelectric body layers and have individual electrode parts corresponding to the pressure chambers and wiring parts for the individual electrode parts, and a low-dielectric layer or an insulating layer that is provided between the piezoelectric body layers and the diaphragm in the region of the wiring parts.
Firstly, a novel multi-nozzle ink jet head structure for which a PCT application (PCT/JP/99/06960) was filed by the present applicant on Dec. 10, 1999 is a prerequisite of the present invention. With this structure, the piezoelectric body layers are provided even in regions other than the regions of the pressure chambers, and wiring parts from the individual electrodes are formed on the piezoelectric body layers, and hence connection to the outside of the head can be carried out at a position away from the row of the piezoelectric bodies of the pressure chambers.
The present invention further improves the characteristics of a head of this structure, improving the drop in the characteristics caused by the wiring parts having the piezoelectric body actuator laminated structure. That is, with the structure described above, the electrical capacitance of the wiring parts is added, and hence a lag arose in the driving operation of the piezoelectric bodies relative to the input waveform, and moreover the piezoelectric bodies expanded and contracted at the wiring parts, and hence there was a risk of structural problems (structural cross talk, breaking off of joining parts etc.) arising in the head.
With the present form of the present invention, by forming a low-dielectric layer or an insulating layer between the piezoelectric body layers and the diaphragm in the region of the wiring parts, the electrical capacitance of the wiring parts can be reduced. A lag in the driving operation due to the electrical capacitance can thus be prevented, and moreover structural problems in the head can be prevented.
Moreover, with the multi-nozzle ink jet head of the present invention, by constituting the low-dielectric layer or insulating layer from a flattening layer that flattens between the piezoelectric body layers. The layer for reducing the above-mentioned electrical capacitance can be formed during the flattening layer formation step, and hence the manufacturing process can be shortened.
The multi-nozzle ink jet head of another form of the present invention has a head substrate in which are formed a plurality of nozzles and a plurality of pressure chambers, a diaphragm that also acts as a common electrode and covers the plurality of pressure chambers, piezoelectric body layers that are provided in
Koike Shuji
Sakamoto Yoshiaki
Shingai Tomohisa
Armstrong Kratz Quintos Hanson & Brooks, LLP
Fuji Photo Film Co. , Ltd.
Nguyen Judy
LandOfFree
Multi-nozzle ink jet head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multi-nozzle ink jet head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multi-nozzle ink jet head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3231779