Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-10-10
2004-03-09
Stephens, Juanita (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S063000
Reexamination Certificate
active
06702428
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Patent Application No. 2001-62947, filed Oct. 12, 2001, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bubble-jet type ink-jet printhead, and more particularly, to a bubble-jet type ink-jet printhead having a recess formed on a substrate on which a bottom surface of an ink chamber is disposed.
2. Description of the Related Art
In general, ink-jet printheads are devices printing in a predetermined color image by ejecting a small volume of a droplet of printing ink at a desired position on a recording sheet. Ink ejection mechanisms of an ink-jet printer are largely categorized into two different types: an electro-thermal transducer type (bubble-jet type) in which a heat source is employed to form a bubble in ink to cause the ink to be ejected, and an electro-mechanical transducer type in which ink is ejected by a change in ink volume due to deformation of a piezoelectric element.
In the above-mentioned ink-jet printheads, ink is supplied to an ink chamber from an ink reservoir through an ink passage. Ink filled in the ink chamber is heated by a heating element in the ink chamber and is ejected in a droplet shape through a nozzle by a pressure of the bubble generated by the heating element.
FIG. 1
is a schematic perspective view illustrating a structure of a conventional bubble-jet type ink-jet printhead, and
FIG. 2
is a cross-sectional view illustrating the conventional bubble-jet type ink-jet printhead shown in FIG.
1
.
Referring to
FIG. 1
, the conventional bubble-jet type ink-jet printhead includes a base plate
10
formed of several different material layers stacked on a substrate
11
of
FIG. 2
, a barrier wall
20
which is stacked on the base plate
10
and defines an ink chamber
22
and an ink passage
26
, and a nozzle plate
30
stacked on the barrier wall
20
. The ink chamber
22
is filled with ink, and a heater (
13
of
FIG. 2
) which generates the bubble in the ink by heating the ink, is provided under a bottom surface
24
of the ink chamber
22
. The ink passage
26
is a path for supplying ink to the ink chamber
22
and is connected to an ink reservoir (not shown). A plurality of nozzles
32
through which ink is ejected, is formed at a location corresponding to a center of the ink chamber
22
on the nozzle plate
30
.
Referring to
FIG. 2
, the conventional bubble-jet type ink-jet printhead having the above structure of
FIG. 1
includes an adiabatic layer
12
which prevents a thermal energy generated by a heater
13
from being discharged toward the substrate
11
, is formed on the substrate
11
formed of silicon. The adiabatic layer
12
is generally formed of a silicon oxide layer deposited on the substrate
11
. The heater
13
which generates the bubble in the ink by heating the ink in the ink chamber
22
, is formed on the adiabatic layer
12
. The heater
13
is deposited by sputtering a tantalum-aluminum alloy in a thin film shape, for example. A conductor
14
transmitting a current to the heater
13
is formed on the heater
13
. The conductor
14
is formed of an aluminum-copper alloy, for example.
Passivation layers
15
a
and
15
b
for passivating the heater
13
and the conductor
14
are formed on the heater thin film
13
and the conductor
14
. The passivation layers
15
a
and
15
b
prevent the heater
13
and the conductor
14
from oxidizing or directly contacting ink and are formed of two layers, such as a first passivation layer
15
a
formed of a silicon nitride layer and a second passivation layer
15
b
formed of a silicon carbide layer. An anticavitation layer
16
is formed on the second passivation layer
15
b
where the ink chamber
22
is formed. The anticavitation layer
16
prevents the heater
13
from being damaged by a high atmospheric pressure generated when the bubble in the ink chamber
22
is removed, by forming the bottom surface
24
of the ink chamber
22
on an upper side of the anticavitation layer
16
, and a tantalum thin film is generally used for the anticavitation layer
16
.
The barrier wall
20
defines the ink chamber
22
and the ink passage
26
and is stacked on the base plate
10
that is formed of several different layers stacked on the substrate
11
. The barrier wall
20
is coated through lamination for heating, pressurizing, and compressing a photosensitive polymer on the base plate
10
, followed by patterning. In this case, a coating thickness of the photosensitive polymer is about between 25 &mgr;m and 35 &mgr;m and is determined by a height of the ink chamber
22
required by a volume of the ink droplet ejected.
The nozzle plate
30
on which the plurality of nozzles
32
are formed, is stacked on the barrier wall
20
. The nozzle plate
30
is formed of polyimide or nickel and is heated and pressurized on the barrier wall
20
and attached to the barrier wall
20
using adhesion of the photosensitive polymer forming the barrier wall
20
.
In the above structure of the conventional bubble-jet type ink-jet printhead, the photosensitive polymer forming the barrier wall
20
is used to attach the base plate
10
to the nozzle plate
30
and surrounds the ink chamber
22
. Ink filled in the ink chamber
22
contains water of about between 60% and 70%, and water soaks not only into an adhesion interface among the base plate
10
, the barrier wall
20
, and the nozzle plate
30
but also into the photosensitive polymer forming the barrier wall
20
. This phenomenon causes the delamination between elements of the ink-jet printhead and thus is a main factor in causing a defect of the ink-jet printhead.
Also, a crosstalk that affects the formation of bubbles and ejection characteristics of ink due to an atmospheric pressure applied to the adjacent ink chamber
22
through the ink passage
26
during ink ejection, may occur easily.
Also, the nozzle plate
30
adheres to the barrier wall
20
after the barrier wall
20
is formed on the base plate
10
. Hence, if the height of the barrier wall
20
is large, the barrier wall
20
may be easily deformed when the nozzle plate
30
is heated and pressurized on the barrier wall
20
to be attached to the barrier wall
20
. As a result, a misalignment among the nozzle
32
, the ink chamber
22
, and the heater
13
occurs, and thus results in poor performances of the ink-jet printhead.
SUMMARY OF THE INVENTION
To solve the above and other problems, it is an object of the present invention to provide a bubble-jet type ink-jet printhead which prevents delamination and improves ejection characteristics of ink droplets by reducing a height of a barrier wall of an ink chamber by forming a recess on a substrate on which a bottom surface of an ink chamber is disposed.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects, there is provided an ink-jet printhead. The ink-jet printhead includes a base plate including a substrate on which a recess is formed to a predetermined depth, an adiabatic layer formed on the substrate, a heater which is formed on the adiabatic layer and generates a thermal energy, and a passivation layer which is formed on the heater and passivates the heater, a barrier wall which is stacked on the base plate and defines an ink chamber disposed on the recess and having a recessed bottom surface and an ink passage which communicates with the ink chamber, and a nozzle plate stacked on the barrier wall and having nozzles through which ink is ejected, formed at a location corresponding to a center of the ink chamber.
Here, the recess is formed by wet or dry etching a predetermined surface of the substrate on which the ink chamber is to be formed, and a depth of the recess is between 1 &mgr;m and 20 &mgr;
Cho Seo-hyun
Jung Myung-song
Kim Kyong-il
Kim Tae-kyun
Ko Sang-cheol
Staas & Halsey , LLP
Stephens Juanita
LandOfFree
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