Etching a substrate: processes – Forming or treating thermal ink jet article
Reexamination Certificate
1998-04-07
2001-08-28
Mills, Gregory (Department: 1763)
Etching a substrate: processes
Forming or treating thermal ink jet article
C347S068000, C347S069000, C347S065000, C347S071000, C347S085000
Reexamination Certificate
active
06280642
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to an ink jet head, and more particularly to an ink jet head particularly suitable for high-density printing and a process for producing the same. The ink jet head of the present invention can be advantageously used in the head section in ink jet printers which have become popular in recent years.
2. Background Art
In recent years, in office automation (OA) equipment, such as word processors, personal computers, and facsimile machines, various measuring instruments, such as medical measuring instruments, and other devices, ink jet printers have been extensively used for printing information at a high density. As is well known in the art, in the ink jet printers, ink droplets are ejected from head sections of the printers and are deposited directly onto a recording medium, such as recording paper, to perform monochrome or color printing. The ink jet printers have many advantages such as printing can be performed on even a three-dimensional recording medium, running cost is low since plain paper can be used as the recording medium, the head can be simply loaded, the step of transfer, fixation and the like is unnecessary, color printing is easily performed, and a sharp color printed image can be provided. The ink jet head can be classified into several types according to the method for ejecting ink droplets from the head. For example, in an ink jet head of a piezoelectric system, a piezoelectric element is used as pressurizing means. In this case, electrostrictive effect provided by this piezoelectric element is utilized to create a pressure wave within an ink chamber, filled with an ink, in the head section, permitting the ink to be ejected through a nozzle in the head section. In an ink jet head of a bubble jet system, a heating element is used as the pressurizing means, and the heating element is heated to form a bubble, permitting an ink to be ejected through a nozzle in the head section. Further, an ink jet head of a static electricity-driven ejection system is also known wherein ink droplets are ejected by utilizing static electricity. The ink jet head according to the present invention can be advantageously applied to ink jet heads of these and other systems.
The conventional ink jet head generally comprises: a plurality of ink chambers which are disposed at equidistant spaces and function as ink flow passages and pressurizing chambers for ejecting ink; and a nozzle plate mounted on the front end of the ink chambers and equipped with nozzles, for ejecting an ink, corresponding to the ink chambers; and pressurizing means for pressurizing ink within the ink chamber in response to the demand for printing. The pressurizing means has a driving element for creating a driving force for pressurizing the ink chamber. The driving element is a piezoelectric element in one case and a heating element in another case.
The structure of the ink jet head will be described in more detail. For example, as can be understood from
FIG. 1
showing an exploded view of the ink jet head, an ink jet head
10
of the piezoelectric system comprises several members. An ink chamber member
11
has a plurality of ink chambers
12
which serve as an ink flow passage and as a pressurizing chamber for ejecting an ink. A nozzle plate
13
is mounted on the front end of the ink chamber member
11
and is equipped with nozzles
14
, for ejecting an ink, corresponding to the ink chambers
12
. As described above, the ink pressurized within the ink chamber
12
can be ejected as droplets through the bore of the nozzle
14
. In the ink chamber member
11
shown in the drawing, pressurizing means is mounted on the open face of the ink chamber
12
. In the example shown in the drawing, the pressurizing means comprises a diaphragm
15
for creating a change in volume of the ink chamber
12
, a piezoelectric element
17
as a driving element for distorting the diaphragm
15
, and a base
18
for fixing the piezoelectric element
17
.
The ink chamber member
11
has a plurality of ink chambers
12
, in a deep groove form, serving both as ink flow passages and as pressurizing chambers for ejecting an ink, and the ink chambers
12
correspond respectively to nozzles
14
formed in the nozzle plate
13
and are designed so that a corresponding nozzle is disposed in one ink chamber. The ink chambers
12
are disposed at equidistant spaces and parallel to one another using a partition for separating adjacent ink chambers from each other. In this case, in order to enhance the resolution of the ink jet head, the spacing between the ink chambers
12
formed in the ink chamber member
11
should be narrowed. The ink chamber member
11
can be generally joined to the nozzle plate
13
with the aid of an adhesive.
The diaphragm
15
is a component characteristic of an ink jet head
10
of a piezoelectric system. When the piezoelectric element
17
is stretched by the electrostrictive effect, the diaphragm
15
is flexed to create a change in volume within the ink chamber
12
. A reduction in the volume within the ink chamber
12
causes the ink filled into the chamber to be pressurized, and a part of the ink is ejected as droplets successively through the nozzle
14
. The diaphragm
15
generally comprises a sheet having a small thickness of about 3 to 5 &mgr;m and, provided on one side thereof, islands
16
each comprising a protrusion having a height of about 20 &mgr;m. Upon stretching of the piezoelectric element
17
by the electrodistrictive effect, the islands
16
function to surely transmit the distortion created by the stretching to the ink chamber
12
. For this reason, the islands
16
are disposed so as to form a laminate together with the respective corresponding ink chambers
12
and the corresponding portions of the piezoelectric element
17
. The ink chamber member
11
and the diaphragm
15
can also be joined to each other with the aid of an adhesive.
The piezoelectric elements
17
correspond respectively to the ink chambers
12
in the ink chamber member
11
and are separated from one another in order to avoid influencing other ink chambers
12
. The piezoelectric elements
17
separated from one another are fixed onto a base
18
. In general, the piezoelectric elements
17
separated from one another are prepared by joining piezoelectric elements, which are not initially in a separated state, to a base with the aid of an adhesive and then selectively separating the piezoelectric elements alone from one another by cutting. After the formation of an integral assembly of the piezoelectric elements and the base, the piezoelectric elements may be joined respectively to corresponding islands, formed on the diaphragm, with the aid of an adhesive.
In the above and other ink jet heads, the performance of the ink chambers serving both as ink flow passages and as pressurizing chambers for ejecting ink directly influences printing properties and hence is very important. At the outset, an ink chamber member constituting the ink chambers will be described. The ink chamber member in the conventional piezoelectric ink jet head has been generally produced by injection-molding an organic material, for example, “Epox” (tradename of an epoxy resin). The ink chamber member constituted by the organic material, however, has poor rigidity, posing problems including that satisfactory pressure cannot be applied to the ink at the time of pressurizing.
Another method for producing the ink chamber member is such that a powder of an oxide, such as ZrO
2
, is used instead of the organic material and the powder is molded by powder injection molding into an ink chamber member. In this method, however, use of a mold is necessary, and a very large pressure should be applied at the time of filling of the mold with the powder as the raw material, making it difficult to use a mold having a structure fine enough to form fine ink chambers.
Etching also may be mentioned as a method suitable for the formation of fine ink chambers. For example, according to this method, a groove pattern
Ikeda Tomoo
Shirai Yoshimasa
Yamamoto Etsuo
Citizen Watch Co. Ltd.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Mills Gregory
Zervigon Rudy
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