Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-09-06
2003-11-25
Stephens, Juanita (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S047000, C347S094000
Reexamination Certificate
active
06652079
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head, which is used in a recording apparatus for discharging recording liquid such as ink from a discharge port to form liquid droplets and perform recording operation, and a method of manufacturing the same. Incidentally, the ink jet recording head of the present invention can be applied to an apparatus such as a copying machine, a facsimile machine having a communication system and a wordprocessor having a printing unit in addition to a general printing apparatus, and further to an industrial recording apparatus that is compositely combined with various processing apparatuses.
2. Related Background Art
An ink jet recording apparatus is a recording apparatus of a so-called non-impact recording system and has a characteristic that it generates little noise at the time of printing and is capable of performing high-speed recording and recording on various recording media. Thus, the ink jet recording apparatus is widely employed as an apparatus for bearing a recording mechanism for a printer, a copying machine, a facsimile machine, a wordprocessor and the like.
As a representative ink discharge method in a recording head that is mounted in such an ink jet recording apparatus, there are known a method using an electromechanical transducing body such as a piezoelectric element, a method of irradiating an electromagnetic wave such as laser to cause ink to heat and discharging ink droplets by an action of the heating, a method of heating ink by an electrothermal conversion element having a heating resistor and discharging ink droplets by an action of film boiling, or the like.
Among these methods, the ink jet recording head using an electrothermal conversion element has an electrothermal conversion element provided in a recording liquid chamber, supplies an electric pulse being a recording signal to the element to cause it to heat, thereby giving thermal energy to ink, and utilizes a bubble pressure at the time of bubbling (boiling) of recording liquid caused then by phase change of the recording liquid to discharge ink liquid from a micro discharge port and record an image on a medium to be recorded. The ink jet recording head using an electrothermal conversion element generally includes a nozzle in which a discharge port for discharging ink droplets is opened, and an ink flow path and a common liquid chamber for supplying ink to this nozzle.
Such an ink jet recording head is usually mounted on a carriage of a recording apparatus main body. The recording apparatus main body includes conveying means for conveying a medium to be recorded such that it passes a position opposing a discharge port surface of the ink jet recording head mounted on the carriage. The carriage is configured to be movable in a direction perpendicular to a direction of conveying a medium to be recorded.
A recording operation in such a recording apparatus is performed by repeating main scanning for discharging ink at a predetermined period while moving the ink jet recording head and sub-scanning for conveying a medium to be recorded by a predetermined length.
FIGS. 45A and 45B
are schematic views showing a nozzle part of a conventional ink jet recording head.
FIG. 45A
is a plan view showing a discharge port forming member in a transparent state and
FIG. 45B
is a sectional view cut along the line
45
B—
45
B of FIG.
45
A. Reference symbol G denotes a central line of an ink flow path.
The ink jet recording head shown in
FIGS. 45A and 45B
includes a common liquid chamber
154
connected to an ink supply port
156
. On both sides of the common liquid chamber
154
, a plurality of electrothermal conversion elements
151
for causing ink to bubble to discharge the ink and a plurality of circular pressure chambers
155
having centers in common with the electrothermal conversion elements
151
are provided side by side. An ink flow path
153
is provided between the common liquid chamber
154
and each pressure chamber
155
. A discharge port
152
is opened in a position opposing each electrothermal conversion element
151
.
In this ink jet recording head, positions in a printing direction (carriage moving direction) of sets of the discharge port
152
and the electrothermal conversion element
151
that are adjacent to each other are shifted from one another by an offset equivalent to a distance that a carriage (not shown) moves during a lagged time of driving timing between each driving block. For simplicity of illustration, in
FIGS. 45A and 45B
, an ink jet recording head in which four driving blocks are allocated to each nozzle is shown, and an arrangement of the discharge port
152
in a printing direction periodically changes for every four nozzles in a direction of a row of discharge openings.
Then, if numbers are given to the driving blocks in the ascending order from the one to be driven first, in the example shown in
FIGS. 45A and 45B
, a driving block
1
is allocated to the discharge port
152
at the upper right and the discharge port
152
apart from it by the number of nozzles of integer times of four, a driving block
2
is allocated to the discharge ports
152
on the left of them, a driving block
3
is allocated to the discharge ports
152
on the left of the driving block
2
, and a driving block
4
is allocated to the discharge ports
152
on the left of the driving block
3
. With such a configuration, the driving blocks
1
to
4
are sequentially driven in the ascending order, whereby it becomes possible to discharge ink and cause the ink discharged from these discharge ports
152
to be applied on a recording medium in one row.
In a nozzle of the configuration shown in
FIGS. 45A and 45B
, since a central line of an ink flow path
163
and a central line of the electrothermal conversion element
151
coincide with each other, a flow of ink heading to the pressure chamber
155
from the common liquid chamber
154
through the ink flow path
163
is generated in line symmetry with respect to the central line of the electrothermal conversion element
151
. Thus, bubbles generated by heating the ink by the electrothermal conversion element
151
disappear steadily on the electrothermal conversion element
151
in symmetry with respect to its central line. Although bubble disappearance positions are dispersed to corners (four corners in total) of a heating area of the electrothermal conversion element
151
in some cases, each bubble disappearance position is fixed even in such cases.
When the bubbles disappear, an impact force due to collapse of cavitation is generated. In the nozzle structure in which bubble disappearance positions are stable as in the above-mentioned conventional art, since a specific part of the electrothermal conversion element
151
is subject to an impact force due to the collapse of cavitation, the electrothermal conversion element
151
is susceptible to damages and hense its durable life is shortened.
SUMMARY OF THE INVENTION
The present invention has been devised in view of the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide an ink jet recording head that is capable of avoiding damages due to cavitation of an electrothermal conversion element and thus extending its life.
In order to attain the above-mentioned object, an ink jet recording head according to the present invention is an ink jet recording head comprising: a plurality of ink discharge ports for discharging ink; a plurality of electrothermal conversion elements that are provided to be associated with each of the ink discharge ports, respectively, for bubbling and discharging the ink; a plurality of pressure chambers for containing the electrothermal conversion elements and providing spaces for heating and bubbling the ink; a common liquid chamber for supplying ink to the plurality of pressure chambers; and a plurality of ink flow paths for communicating the pressure chambers with the common liquid chamber, which is characterized in that the in
Inoue Ryoji
Kaneko Mineo
Oikawa Masaki
Tsuchii Ken
Yabe Kenji
LandOfFree
Ink jet recording head with extended electrothermal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet recording head with extended electrothermal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet recording head with extended electrothermal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3184992