Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-09-19
2002-02-12
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06345883
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from the inventor's application THERMAL-COMPRESS TYPE INK JETTING APPARATUS filed with the Korean Industrial Property Office on Nov. 4, 1999 and there duly assigned Ser. No. 48554/1999.
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, etc., and more particularly to a thermal-compression type fluid jetting apparatus employed in a printer head of an output apparatus.
2. Description of the Prior Art
Generally, a fluid jetting apparatus employed in a printer head of an output apparatus such as an inkjet printer or a facsimile machine, etc., ejects ink in an ink chamber outward through a nozzle by exerting physical force to the ink chamber. Such a fluid jetting apparatus may be of a thermal type, a piezoelectric type, or a thermal-compression type in accordance with the method of exerting physical force on the fluid.
One example of a thermal-compression type fluid jetting 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 includes a substrate
15
, an oxide film
14
laminated on substrate
15
, a working fluid barrier
25
having a working fluid chamber
27
, a heater
16
disposed in working fluid chamber
27
, and a conductor
17
connected with heater
16
.
The nozzle module 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 ink chamber
57
to be jetted therethrough.
The membrane is located between ink chamber barrier
45
and working fluid barrier
25
. The membrane serves as a partition between the working fluid chamber and the ink chamber.
The working fluid such as a heptane or the like, is charged in working fluid chamber
27
, while ink is constantly fed into ink chamber
57
from an ink source (which is not shown in the drawings).
FIGS. 2 and 3
show an operating process of a conventional ink jetting apparatus of FIG.
1
. As electricity is applied to conductor
17
, heat is generated from heater
16
, and working fluid in working fluid chamber
27
is heated, forming bubbles. The bubbles cause pressure in working fluid chamber
27
to increase. Accordingly, membrane
30
is upwardly expanded, pressuring ink in ink chamber
57
. Accordingly, the ink in ink chamber
57
is jetted through nozzle holes
49
.
Then, as the electricity supply to heater
16
is ceased, as shown in
FIG. 3
, bubbles B contract. Accordingly, membrane
30
recovers its initial shape, and pressure in ink chamber
57
is decreased. The ink expressed outward through nozzle hole
49
is separated from the ink in the form of an ink drop I, and is jetted out of ink chamber
57
. In this way, ink jetting is performed by the repetitious heating operation of heater
16
.
Bubbles B are produced by the heat energy at different temperatures depending on the material type used as the working fluid. For example, according to the Homogeneous Nucleation theory, heptane produces bubbles at the temperature of 214° C., while water produces bubbles at the temperature of 270-310° C. In order to perform a repetitious printing operation, heater
16
of the ink jetting apparatus undergoes numerous heating and cooling processes, which means that the high cooling speed of heater
16
determines the high quality of the ink jetting apparatus.
In a conventional ink jetting apparatus, when heater
16
begins the heating operation, the bubble B is produced instantly, and covers the whole area of the heater
16
as shown in FIG.
2
. Here, since a bubble B has low heat conductivity, when the electricity supply to heater
16
is ceased, bubble B contracts from the farthest area from where the bubble is in contact with heater
16
. Accordingly, it takes a longer time for bubble B to disappear than to be produced, and the ink jetting apparatus can not be operated rapidly. In the event that heater
16
re-starts the heating operation before the complete disappearance of bubble B, the pressure control in working fluid chamber
27
is disturbed by the presence of bubble B, and the stability in driving the ink jetting apparatus deteriorates.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an ink jetting apparatus capable of performing high-speed printing operations by providing for rapid disappearance of the bubbles during the heating operation of the heater.
The above object is accomplished by a thermal-compression type ink jetting apparatus according to the present invention, including: a nozzle module having an ink chamber for reserving ink, and a nozzle hole for permitting ink in the ink chamber to be jetted therethrough; a driving module having a working fluid chamber charged with the working fluid, a heater disposed in the working fluid chamber, a conductor for supplying electricity to the heater from an external power source, and at least one fin located on the heater and heated by the heater; and a membrane serving as a partition between the ink chamber and the working fluid chamber, the membrane being curved into the ink chamber by the pressure of a bubble which is produced while heating the working fluid to jet the ink in the ink chamber through a nozzle hole.
The fins are in the shape of plates, and are arranged on the heater in a parallel, or latticed arrangement. Preferably, the fins have a height of less than 70% of distance between the heater and the membrane, and are made of metal such as aluminum, copper, nickel, silver, or gold.
According to the present invention, since the bubbles are divided by a plurality of fins located on the heater, they disappear rapidly. As a result, high-speed driving of the ink jetting apparatus becomes possible, and stable driving of the ink jetting apparatus is performed.
REFERENCES:
patent: 5666140 (1997-09-01), Mitani et al.
Ha Yong-Ung
Shin Su-Ho
Bushnell , Esq. Robert E.
Gordon Raquel Yvette
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