Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-02-09
2003-05-27
Bariow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06568791
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head that records by discharging recording droplets to a recording medium by use of the ink jet recording method for the adhesion thereof to it. The invention also relates to a method of manufacture therefor. More particularly, it relates to an ink jet recording head for discharging fine recording droplets stably at higher speeds in order to obtain images recorded in higher precision, and a method of manufacture therefor as well.
2. Related Background Art
With the ink jet recording head, recording (printing) is made by discharging the ink that serves as recording liquid from the fine discharge ports (orifices) as flying droplets which adhere to a recording medium (a paper recording sheet or the like). To structure the ink discharge unit of the ink jet recording head, there are laminated a resin member on a substrate provided with a plurality of discharge energy generating elements and lead electrodes on it in order to form a plurality of grooves that serve as ink liquid flow paths and a groove that serves as a common liquid chamber communicated with the plurality of liquid flow paths. To the resin member formed on this substrate, the glass ceiling plate provided with an ink supply opening is bonded to cover all the grooves for the formation of the liquid flow paths and the common liquid chamber.
In recent years, the above-mentioned glass ceiling plate is omitted, while the ink supply opening is added to the grooves that serve as the liquid flow paths and the common liquid chamber. Then, the resin ceiling plate is formed by means of injection molding or the like together with the orifice plate having discharge ports formed therefor. Such resin ceiling plate and the substrate provided with the discharge energy generating elements are bonded through an elastic member so that each of the discharge energy generating elements is fittingly arranged for each of the flow path grooves on the ceiling plate. In this manner, there has been developed an ink jet recording head formed by bonding the resin ceiling plate and the substrate.
FIG. 9
is a perspective view which shows the principal part of the ink jet recording head formed by bonding such resin ceiling plate and substrate. In
FIG. 9
, the second substrate that serves as the resin ceiling plate is partly broken for representation. As shown in
FIG. 9
, a plurality of discharge energy generating elements
701
for discharging ink are arranged in parallel for the first substrate
702
. On the other hand, the resin second substrate
710
is structured by the ceiling plate portion
711
and the orifice plate portion
708
. Here, the ceiling unit
711
is configured in such a manner that it is connected vertically with one surface of the orifice plate portion
708
. On one surface of the ceiling plate portion
711
, the ink supply opening
709
is arranged. Here, a hole extended from the ink supply opening
709
penetrates the ceiling plate portion
711
vertically. On the other surface of the ceiling plate portion
711
, where the hole form the ink supply opening
709
is open, there are arranged a groove extendedly in parallel with the orifice plate portion
708
to serve as the common liquid chamber to retain ink temporarily, and a plurality of grooves communicated with the common liquid chamber
706
to serve as liquid flow paths which are extended on straight lines from the common liquid chamber
706
in the direction toward the orifice plate portion
708
. On the leading edge portion of the orifice plate portion
708
to which the plurality of liquid flow paths
707
are extended, the holes are arranged to penetrate the orifice plate portion
708
. Through these holes, the liquid flow paths
707
are communicated with the outside. These through holes on the orifice plate portion
708
become the ink discharge ports
705
. The surface of the second substrate
710
, where the grooves are provided for the common liquid chamber
706
and the liquid flow paths
707
, and the surface of the first substrate
702
, where the discharge energy generating elements
701
are formed, are arranged to face each other so that the discharge energy generating elements
701
are positioned with the corresponding liquid flow paths
707
. Then, these surfaces are pressed with an elastic material (not shown) between them to bond the first substrate
702
and the second substrate
710
for the formation of the common liquid chamber
706
and the liquid flow paths
707
. The first substrate
702
bonded together with the second substrate
710
, and the wiring substrate
703
, which is provided with driving circuits installed thereon to generate electric signals to be transmitted to the first substrate
702
, are fixed on the base plate
704
, thus forming the principal part
714
of the head.
Now, with the principal part
714
of the ink jet recording head shown in
FIG. 9
, an ink jet recording head is fabricated as represented in FIG.
10
. Here, the head principal part
714
is integrally formed by the injection molding together with the grooves that become liquid flow paths
707
to supply ink (recording liquid) to the head principal part
714
, the ceiling plate portion
711
provided with the ink supply opening
709
, and the orifice plate portion
708
as shown in FIG.
10
. Then, a part of the orifice plate portion
709
, which is the plate portion of the integrally formed resin member, prepared for the formation of the discharge ports
705
, is irradiated by excimer laser from the common liquid chamber side to from them. In this manner, the second substrate
710
is produced.
Now, with reference to
FIGS. 11A
to
11
C, the description will be made of the operation of the ink jet recording head structured as described above. The interior of the common liquid chamber
706
is filled with ink supplied from the ink supply opening
709
. The interior of each of the liquid flow paths
707
is also filled with the ink that has flown into it from the common liquid chamber
706
. When each of the discharge energy generating elements
701
is supplied with electric power, thermal energy is generated as discharge energy. With the thermal energy thus generated, film boiling is created in ink on each of the discharge energy generating elements
701
, hence air bubbles being formed in the liquid flow paths, respectively. By the development of each air bubble, ink that resides between the corresponding discharge energy generating element
701
and discharge port
705
is pressed toward the discharge port
705
. Then ink is discharged from the discharge port
705
.
However, the progress of recording technologies, particularly the progress in making the precision of recorded images more precise, is remarkable in recent years. As a result, it has been demanded to make recorded images highly precise not only in the conventional resolutions of from 360×360 dpi (dot per inch) and 600×600 dpi to 720×720 dpi, but also, in the extremely high resolution of 1200×600 dpi or the like.
In order to materialize highly precise images recorded by use of an ink jet recording head, it is necessary to make the recording droplets extremely small when discharged from each of the discharge ports. However, there is a problem encountered that it is very difficult to discharge the extremely fine recording droplets stably at high speeds by use of the ink jet recording head produced by the conventional art. Now, hereunder, such problem will be discussed with reference to
FIGS. 11A
to
11
C which illustrate the conventional techniques.
In other words, there is a need for making the diameter of each discharge port smaller in order to make each recording droplet a small one. Then, when the discharge port is made smaller, the residing region of the fluid resistance component (the step
730
in
FIGS. 11A
to
11
C) becomes larger in the portion that connects the discharge port with the liquid flow path. As a result, due to the presence of this fluid resistanc
Hosaka Ken
Ishimatsu Shin
Takenouchi Masanori
Bariow John
Brooke Michael S
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