Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-09-18
2002-08-13
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S094000
Reexamination Certificate
active
06431688
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an output apparatus such as an inkjet printer or facsimile machine. More particularly, the invention concerns a device for use in a thermal-compression type fluid jet apparatus employed in a printer head, the device being adapted to prevent back-flow of ink. In addition, the invention concerns a method of preventing back-flow of ink by using the foregoing apparatus.
2. Description of the Related Art
Generally, a fluid jet apparatus employed in a printer head of an output apparatus, such as an inkjet printer or a facsimile machine, ejects ink from an ink chamber outward through a nozzle by exerting physical force to the ink chamber. Such a fluid jet apparatus may be of a thermal type, a piezoelectric type, or a thermal-compression type, depending on the method of exerting physical force on the fluid. This invention concerns the thermal-compression type of apparatus.
An example of a known thermal-compression type fluid jet apparatus is shown in FIG.
1
. The fluid jetting apparatus includes a driving module
20
, a membrane
30
, and a nozzle module
40
.
The driving module
20
includes a substrate
15
, an oxide film
14
laminated onto substrate
15
, a working fluid barrier
25
having a working fluid chamber
27
, a heater
16
located in working fluid chamber
27
, and a conductor
17
connected with the heater
16
.
Nozzle module
40
includes an ink chamber barrier
45
having an ink chamber
57
, and a nozzle plate
47
connected with the upper portion of ink chamber barrier
45
. On the upper side of nozzle plate
47
, a nozzle hole
49
is formed to permit ink in the ink chamber
57
to be forced therethrough as a jet.
Membrane
30
is disposed between ink chamber barrier
45
and working fluid barrier
25
. Membrane
30
serves as a partition between the working fluid chamber and ink chamber
57
.
The working fluid (such as a heptane or the like) is charged in working fluid chamber
27
, while the ink is constantly fed into ink chamber
57
from an ink source (not shown in the drawings).
As electricity is applied to conductor
17
, heat is generated by heater
16
, and the working fluid in working fluid chamber
27
is heated, forming bubbles. The bubbles increase the pressure in working fluid chamber
27
. Accordingly, membrane
30
is upwardly bent, imposing pressure on the ink in ink chamber
57
. Accordingly, the ink in ink chamber
57
is forced through the nozzle holes
49
.
The conventional fluid jet apparatus, however, has shortcomings. First, it requires a complicated manufacturing process: first, a working fluid preparing process; second, a working fluid charging process; and third, sealing process. Further, since the organic solvent employed as the working fluid (e.g., such as a heptane) is apt to evaporate easily, there is a high possibility of having a space in the working fluid chamber. Once a space is formed in the working fluid chamber, the pressure exerted on the membrane can become insufficient during the heating operation of the heater, so that the quantity of jetted ink can not be precisely controlled.
In order to solve the above-described shortcoming of the prior art, the present inventor has disclosed an ink jet apparatus using ink as the working fluid as shown in FIG.
2
.
Referring to
FIG. 2
, a system with a driving module
120
, a membrane
130
, and a nozzle module
140
is similar to a conventional ink jetting apparatus, as shown in FIG.
1
. Accordingly, driving module
120
includes a substrate
115
, an oxide film
114
, a working fluid barrier
125
forming a working fluid chamber
127
, a heater
116
, and a conductor
117
. Nozzle module
140
includes an ink chamber barrier
145
having an ink chamber
157
, and a nozzle plate
147
having a nozzle hole
149
.
The ink jet apparatus shown in
FIG. 2
has an interconnecting hole
135
formed in membrane
130
. The ink is fed into ink chamber
157
from an external ink source (not shown), and also is fed into working fluid chamber
127
through interconnecting hole
135
. Accordingly, the ink serves as the working fluid. As heater
116
heats the ink in working fluid chamber
127
, bubbles B are produced in working fluid chamber
127
, upwardly bending the membrane
130
. Accordingly, the ink in ink chamber
157
is pressurized, and the ink is jetted through the nozzle hole
149
.
In such a fluid jet apparatus, there is no need to separately prepare the working fluid since the ink is used as the working fluid. Also, there is no need for a sealing process with respect to working fluid chamber
127
. Accordingly, some malfunctions of the fluid jet apparatus are prevented.
The above-described fluid jetting apparatus using the ink as the working fluid, however, has the following problems: First, the ink received in working fluid chamber
127
constantly serves as the working fluid. Hence, the temperature in working fluid chamber
127
keeps increasing by the repetitive heating operation of heater
116
. Accordingly, the durability of the fluid jetting apparatus is shortened. Further, as the ink is pressured by the expansion of bubbles B, which are produced by the heating operation of heater
116
, and as membrane
130
is upwardly bent, a back flow of the ink occurs from working fluid chamber
127
outside of working fluid chamber
127
through interconnecting hole
135
. Accordingly, the appropriate quantity of ink may not be maintained in working fluid chamber
127
. When the ink is next jetted through nozzle hole
149
by the heating operation of heater
116
, the jet pressure of the ink may be decreased. Accordingly, the desired quantity of ink is not jetted, and the print quality deteriorates when performing repetitious printing operations.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an improved ink jet apparatus capable of preventing occurrence of temperature increase in the working fluid chamber as a result of use of the ink to serve as the working fluid. A further object is to prevent a back flow of ink into the ink chamber and the working fluid chamber.
The present invention accomplishes the above objects in a thermal-compression type inkjet apparatus having components as described above. These components include a nozzle module having an ink chamber, a nozzle hole for permitting the ink in the ink chamber to be jetted therethrough; a driving module having a working fluid chamber, the driving module having a heater disposed in the working fluid chamber; a membrane serving as a partition between the ink chamber and the working fluid chamber. The membrane in the device of the invention is provided with an ink injecting hole for interconnecting an ink injecting passage through which ink is fed from an external ink source. Also, an interconnecting hole interconnects the working fluid chamber with the ink chamber to permit the ink in the working fluid chamber injected through the ink injecting hole to be fed into the ink chamber. Further, the ink injecting hole and/or the interconnecting hole have neck modules, respectively, for narrowing the ink injecting hole and the interconnecting hole to sizes smaller than the inner diameters of the working fluid chamber and the ink chamber.
According to the present invention, the sizes of the ink injecting hole and the interconnecting hole are narrowed to be smaller than the inner diameters of the places where the ink flows. Therefore, the back flow of ink is prevented during the ink jetting process. Further, since the ink serving as the working fluid is constantly fed into the working fluid chamber, excessive heat in the working fluid chamber is prevented, and the durability of the inkjet apparatus is improved.
REFERENCES:
patent: 4480259 (1984-10-01), Kruger et al.
patent: 5097275 (1992-03-01), Takita
Lee Sung-Hee
Shin Kyu-Ho
Bushnell , Esq. Robert E.
Samsung Electronics Ltd.
Stephens Juanita
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