Etching a substrate: processes – Forming or treating thermal ink jet article
Reexamination Certificate
2000-07-25
2002-12-31
Gulakowski, Randy (Department: 1746)
Etching a substrate: processes
Forming or treating thermal ink jet article
C216S049000, C216S095000, C216S100000, C347S068000, C347S070000, C347S071000, C347S072000
Reexamination Certificate
active
06500354
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet printer head actuator in which a chamber plate has chamber walls defining ink chambers and having a cross-sectional area at its portion coupled to a vibrating plate, larger than the cross-sectional area at its portion opposite to the vibrating plate, thereby achieving an increase in the bonding strength of the chamber plate resulting in an improvement in the performance and ink jetting efficiency of the printer head. The present invention also relates to a method for fabricating such an inkjet printer head actuator.
2. Description of the Prior Art
As well known, an inkjet printer head is a part of an inkjet printer for jetting or firing ink in the form of droplets using an actuator such as a piezoelectric element.
Generally, drop-on-demand (DOD) type printer heads are most widely used for inkjet printers. Such DOD type printer heads are configured to jet or fire droplets of a recording solution onto paper under atmospheric pressure on demand. Use of such DOD type printer heads has increased in that they require no electric charge or deflection of droplets of a recording solution and in that easy printing is achieved, as compared to printer heads of earlier types.
Typical jetting systems of such DOD type printer heads include a heating type jetting system using a resistor and a vibration type jetting system using a piezoelectric element.
The heating type jetting system is also known as a thermal bubble jet type jetting system. Referring to
FIG. 1
, a typical configuration of such a heating type jetting system is illustrated. As shown in
FIG. 1
, this heating type jetting system includes a chamber a
1
for containing a recording solution therein, and a nozzle a
2
provided at the top portion of the chamber al in such a fashion that it is open to a recording sheet (for example, paper). Opposite to the nozzle a
2
, a resistor a
3
is provided at the bottom portion of the chamber a
1
.
When voltage of a certain level from a voltage source not shown is applied to the resistor a
3
, the recording solution contained in the chamber a
1
is vaporized while being heated by the resistor a
3
, thereby creating a bubble. Expansion of this bubble creates a pressure forcing a certain amount of the recording solution to be pushed out from the chamber a
1
through the nozzle a
2
. Thus, jetting of the recording solution onto the recording sheet is achieved.
However, such a heating type jetting system involves a problem in that the chemical ingredients of the recording solution itself may vary due to the heat generated from the resistor a
3
. Such a chemical variation may result in a plugging-up of the nozzle a
2
. Furthermore, there is a drawback in that the resistor a
3
is reduced in its use life span due to repetitive voltage application thereto.
On the other hand, the vibration type jetting system is also known as a piezo transducer type jetting system. Referring to
FIG. 2
, a typical configuration of such a vibration type jetting system is illustrated. As shown in
FIG. 2
, this vibration type jetting system includes a chamber b
1
for containing a recording solution therein, a nozzle b
2
provided at the top portion of the chamber b
1
in such a fashion that it is open to a recording sheet (for example, paper), and a piezoelectric element b
3
provided at the bottom portion of the chamber b
1
opposite to the nozzle b
2
.
The vibration type jetting system is different from the heating type jetting system in that a recording solution is jetted using the piezoelectric element b
3
having a compact structure, in place of the resistor a
3
used in the heating type jetting system.
When voltage of a certain level is applied to the piezoelectric element b
3
, a deformation in the piezoelectric element b
3
occurs, thereby resulting in an instantaneous volume variation in the chamber b
1
. As a result, the recording solution is forced out of the chamber b
1
through the nozzle b
2
. Thus, the recording solution is jetted onto the recording sheet.
Recently, such a vibration type jetting system using a piezoelectric element has been widely used because it can prevent a chemical variation of the recording solution, thereby achieving a more stable jetting of the recording solution, as compared to the heating type jetting system.
Referring to
FIG. 3
, a conventional inkjet printer head is illustrated which is configured to use the above mentioned vibration type jetting system. In
FIG. 3
, the reference numeral
1
denotes a nozzle plate formed with nozzles for jetting droplets of ink. The reference numeral
2
is a channel plate
2
formed over the nozzle plate
1
.
A chamber plate
3
is layered over the channel plate
2
. The chamber plate
3
has vertical through holes open at both ends thereof and adapted to define chambers
3
a
. A vibrating plate
4
is layered over the chamber plate
3
to cover the chambers
3
a
. Piezoelectric elements
5
are attached to the upper surface of the vibrating plate
4
at regions corresponding to the chambers
3
a
, respectively.
Generally, the formation of the chamber plate
3
is achieved by forming a green sheet using a ceramic material in accordance with a screen printing process, forming chambers
3
a
at the green sheet in accordance with a punching process, and then sintering the punched green sheet.
In the chamber plate
3
fabricated in the above mentioned manner, there are a plurality of uniformly spaced chambers
3
a
arranged in a matrix array. These chambers
3
a
have substantially vertical side walls.
Each of the chambers
3
a
is closed at the bottom thereof by the channel plate
2
and at the top thereof by the vibrating plate
4
. The piezoelectric elements
5
attached to the vibrating plate
4
are arranged at regions corresponding to the chambers
3
a
, respectively.
In the above mentioned structure, each chamber
3
a
has the same cross-sectional area at the bottom and top thereof. In other words, each side wall of each chamber
3
a
has the same thickness at its upper and lower ends. Due to such a structure, the vibrating plate
4
exhibits an insufficient bending strain when the piezoelectric elements
5
are strained. As a result, an insufficient ink jetting force is generated. For this reason, the above mentioned structure has a drawback in that it is impossible to achieve a high printing efficiency.
Referring to
FIG. 4
, another conventional inkjet printer head is illustrated which is configured to use the above mentioned vibration type jetting system. This printer head includes a nozzle plate
10
, and a channel plate
20
layered over the nozzle plate
10
, as in the case of
FIG. 3. A
chamber plate
30
having chambers
31
is formed over the channel plate
20
in accordance with an electro-forming process. A vibrating plate
40
is layered over the chamber plate
30
to cover the chambers
31
. Piezoelectric elements
50
are attached to the upper surface of the vibrating plate
40
at regions corresponding to the chambers
31
, respectively.
In this structure, each chamber
31
formed at the chamber plate
30
has a cross-sectional area increasing gradually as it extends downwardly from the top thereof to the bottom thereof. In other words, each side wall of each chamber
31
has a thickness decreasing gradually as it extends downwardly from its upper end to its lower end.
Due to such a structure, the bending strain of the vibrating plate
40
generated when the piezoelectric elements
5
are strained is smaller than that in the case of FIG.
3
. This is because the cross-sectional area of the chamber
31
at the top thereof near the vibrating plate
40
is smaller than that in the case of FIG.
3
. As a result, an insufficient ink jetting force is generated which is smaller than that in the case of FIG.
3
.
In this structure, therefore, the printing efficiency is further degraded. Moreover, this structure has a very small bonding area between the channel plate
20
and chamber plate
30
because each chamber wall of the chamb
Joung Jae Woo
Lee Seung Don
Darby & Darby
Gulakowski Randy
Samsung Electronics Co,. Ltd.
Smetana J
LandOfFree
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