Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-04-02
2001-10-02
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06296346
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for jetting ink of an ink-jet print head, and more particularly, to an apparatus for jetting ink by utilizing lamb wave and manufacturing the same.
2. Description of the Prior Art
An apparatus for jetting ink applied to a conventional ink-jet print head ejects a desired amount of the ink through a nozzle by exerting a physical force to the ink received in an ink chamber. Generally, such apparatuses are grouped by the type of system used to eject the ink, for example a piezoelectric system, a thermal system, and an electromagnetic system, etc.
Companies such as Canon and Hewlett-Packard Co. are well known for providing thermal print heads. As shown in
FIG. 1
, the thermal print head includes a lower insulating layer
14
, a heating element
16
, electrodes
18
, an upper insulating layer
20
, and a protecting layer
22
which are sequentially stacked on a printed circuit board (PCB)
12
. Passage walls
23
are installed between a nozzle plate
24
and the protecting layer
22
to form an ink chamber
26
. The ink chamber
26
is connected to a reservoir (not shown), and both electrodes
18
are connected to a driving signal generator
28
.
When the driving signal generator
28
applies a driving signal to the electrodes
18
, the heating element
16
is heated, and ink
27
within the ink chamber
26
is boiled. At this time, bubbles
29
are produced within the ink chamber
26
, and the bubbles
29
push the ink
27
out of a nozzle
25
of the nozzle plate
24
, thereby producing an ink jet
30
.
Companies such as Epson are well known for providing piezoelectric print heads. As shown in
FIG. 2
, a piezoelectric print head includes a PCB
42
, a diaphragm
44
, a piezoelectric element
46
, a spacer
48
and a nozzle plate
50
. An ink chamber
54
is formed by the diaphragm
44
, the piezoelectric element
46
and the nozzle plate
50
. The interior of the ink chamber
54
is filled with ink
53
. When the driving signal generator
52
applies a driving signal to the piezoelectric element, the piezoelectric element
46
mechanically expands and contracts. The expanding and contracting action of the piezoelectric element
46
causes the ink within the ink chamber
54
to be ejected from the nozzle
51
, thereby producing an ink jet
55
.
An electro-magnetic print head includes a magnet driver attached to an outer side of a nozzle, and a magnetically active diaphragm plate for sealing an ink chamber. The ink is ejected by a pressure which is exerted when the magnetically active diaphragm plate is deformed by a magnetic field generated by the magnet driver.
Although conventional print heads are generally thought to be acceptable, they are not without shortcomings. Specifically, piezoelectric print heads are expensive and have a complex structure. Thermal print heads are slow because of the time required to heat the ink, and the heating process deteriorates the ink. Further, the thermal print head has a complex structure making production difficult thus deteriorating the productivity. Finally, an electro-magnetic print head has a lower print quality than the other types of print heads because an induction current causes ink to be inadvertently ejected out of nozzles which are adjacent to the nozzles through which ink is intended to be ejected from.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an apparatus for jetting ink having a simple structure for easier manufacture, high quality print-out, and long durability.
Another object of the present invention is to provide an apparatus for jetting ink having a simple structure produced by simple processes so as to decrease a manufacturing cost.
In order to accomplish these objects, the apparatus for jetting ink of present invention includes an ink chamber having nozzles, an ejecting force source for supplying an ejecting force so as to eject the ink within the ink chamber through the nozzles, wherein the ejecting force is a lamb wave.
The ejecting force source includes electrodes for applying a predetermined voltage, and a lamb wave generating board for generating the lamb wave by means of the voltage applied from the electrodes. The electrodes are inter-digital transducers (IDT) disposed along the upper surface of the lamb wave generating board. Preferably, the electrodes are arranged such that the same produce reinforcement interferences of lamb waves at the predetermined positions of the lamb wave generating board. Here, the predetermined positions of lamb wave generating board are aligned with the nozzles. The lamb wave generating board is a piezoelectric element, and preferably, has a C-axis orientation of high piezoelectric efficiency.
Preferably, a transfer board is disposed between the lamb wave generating board and the ink chamber. The transfer board is a material that has a larger modulus of elasticity and a larger fatigue limit, such as ceramic, metal, and the like. More preferably, a grounded electrode is disposed between the lamb wave generating board and the ink chamber in order to enhance the lamb wave generating efficiency.
Another object of the present invention is accomplished by a method for producing the apparatus for jetting ink according to the present invention including a step of forming the transfer board on the silicon board, a step of forming the grounded electrode on the transfer board, a step of forming a pattern of electrodes on the lamb wave generating board, a step of forming a chamber on a side of the silicon board that faces away from the transfer board, and a step of forming nozzles in the ink chamber. The ink chamber may be formed by lithographic, and a wet etching processes.
Thus, as the voltage is applied to the IDT electrodes, the lamb wave is generated from the lamb wave generating board, and the ink within the chamber is ejected out of the nozzles by the lamb wave. Accordingly, the apparatus for jetting ink has a simple structure, enhanced durability, and the ink reserved in the apparatus does not deteriorate.
The above and other features of the invention including various and novel details of construction and combination of parts will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular apparatus for ejecting ink embodying the invention is shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in varied and numerous embodiments without departing from the scope of the invention.
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patent: 5988799 (1999-11-01), Abe et al.
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Japanese Abstract No. 09-183225, dated Jul. 15, 1997.
Japanese Abstract No. 06-050870, dated Feb. 25, 1994.
Choi Byoung-Lyong
Nam Seung-ho
Seo O-Gweon
Song Young-Jin
Gordon Raquel Yvette
Samsung Electronic Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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