Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-06-19
2003-06-24
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C029S890100
Reexamination Certificate
active
06582058
ABSTRACT:
CROSS REFERENCE
This application claims the benefit of Korean Patent Application No. 1999-22595, filed on Jun. 16, 1999, under 35 U.S.C. §119, the entirety of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet print head and a method of manufacturing the same.
2. Description of Related Art
Inkjet print heads are widely used in various industrial fields since they can produce print at a relatively lower cost than a laser printer. They also can provide higher resolution than dot-matrix printers. For example, an inkjet print head is used to print a color filter layer of a liquid crystal display device.
However, since an inkjet print head uses a liquid ink, the liquid ink may become easily blurred on the printing paper or the printing plate and nozzles of the print head may become blocked because of the dregs in the liquid ink.
FIG. 1
shows a conventional inkjet print head. The print head
10
moves back and forth or right and left and sprays ink through nozzles
12
to print desired lines or data. However, since the print head
10
of the inkjet print uses a liquid ink, dregs of the liquid ink may remain inside the nozzle
12
.
FIG. 2
shows a configuration of the print head. As shown in
FIG. 2
, the print head comprises an ink pool
14
, a plurality of screens
16
, and a piezo element
18
. The ink pool
14
holds the printing ink, and the screens
16
are arranged between the ink pool
14
and the piezo element
18
. The piezo element
18
serves to pump the printing ink from the ink pool
14
to the nozzle
12
through a channel
20
according to a predetermined controlling signal from the external drive circuit (not shown). The piezo element
18
further serves to forward the printing ink to a direction of an arrow “a”. At this time, a lower portion of the piezo element
18
secures a big area enough to provide the piezo element
18
with a working space. Further, the channel
20
is connected with the lower portion of the piezo element
18
and becomes narrow in a direction away from the piezo element
18
.
The screens
16
are formed on a wafer or a glass substrate
1
, as shown in
FIG. 3
, and have a convex-gully shape. A concave portion between the screens
16
is a portion that is etched. The screens
16
serve to regulate the flow of the printing ink so that an excessive amount of the printing ink is not supplied from the ink pool
14
to the piezo element
18
. Accordingly, a pumping energy of the piezo element
18
is uniformly provided to the nozzle
12
, so that an appropriate amount of the printing ink is sprayed.
In the mean while, as shown in
FIGS. 4A and 4B
, since the nozzle
12
of the print head has a high hydrophilicity, i.e., a high water affinity as described above, dregs
24
of the printing ink
22
collect inside the nozzle
12
, eventually clogging the nozzle
12
. In addition, the nozzle
12
may be suddenly unblocked due to a pumping operation of the piezo element
18
, leading to an over-spraying or a misprint.
To overcome the problems described above, several conventional methods of making the nozzle have a high hydrophobicity are known.
FIG. 5
shows a drop
3
of the printing ink on the metal plate
1
. As shown in
FIG. 5
, the metal is considered to have a high hydrophobicity when a wet angle &thgr; of ink drop
3
is greater than 45°. Metals having high hydrophobicity include Ti, Cu, and Au. As shown in
FIG. 6
, to prevent dregs of the printing ink from clogging the nozzles
12
of the print head
10
, a process of either of depositing or coating a metal having a high hydrophobicity such as Ti, Cu and Au is additionally performed.
In another conventional approach, as shown in
FIG. 7
, first the print head
10
a
is located on a stage plate
21
and is secured by a head holder
25
. Then, a fluorine-based polymer such as Cytop™ or Teflon is applied to the nozzle
12
while rotating print head
10
a
about a rotation axis
23
, so that the nozzle
12
has a high hydrophobicity.
However, in the case of depositing or coating a metal having a high hydrophobicity, the metal coating film may be easily exfoliated so that the nozzle undesirably has a high hydrophilicity. Further, in the case of applying a hydrophobic material, i.e., a fluorine-base polymer to the nozzle, the nozzle of the print head may be clogged because the hydrophobic material has an inherent viscosity.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a print head of an inkjet printer which has nozzles having a high hydrophobicity, and a method of manufacturing the same.
In order to achieve the above object, an inkjet print head includes a nozzle, an ink pool temporarily holding printing ink and a first screen. The first screen has at least a convex bar column, the bar column having a plurality of spaced apart bars arranged in a longitudinal direction of the ink pool. A piezo element pumps the printing ink from the ink pool to the nozzle.
A distance between the respective convex bars is about 25 to 30 &mgr;m. The present invention further includes a second screen having a plurality of spaced apart convex bars and a channel communicating with both the nozzle and the piezo element.
The channel becomes narrower in width in a direction away from the piezo element.
The present invention further provides a method of manufacturing an inkjet print head having a nozzle plate with a plurality of nozzles. The method includes depositing an amorphous silicon layer on the nozzle plate. The amorphous silicon layer is deposited on the nozzle plate using one of chemical vapor deposition (CVD) technique, sputtering, and physical vapor deposition (PVD).
The method according to the present invention also includes heating a petroleum-based material in a heater, and coating the vaporized petroleum-based material on the nozzle plate of the print head.
The petroleum-based material is heated using an electric furnace or inflammable fuel. The petroleum-based material is, for example, a paraffin wax.
REFERENCES:
patent: 5481289 (1996-01-01), Arashima et al.
patent: 6000789 (1999-12-01), Takagi et al.
patent: 6102521 (2000-08-01), Haiko et al.
patent: 6258286 (2001-07-01), Hawkins et al.
patent: 6303042 (2001-10-01), Hawkins et al.
Choi Jaebeom
Lee Jaekyun
Yi Jonghoon
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