Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Utility Patent
1998-03-26
2001-01-02
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Utility Patent
active
06168265
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet print head provided in an ink-jet printing device for ejecting liquid ink from nozzles onto a recording paper in order to form desired images on the recording paper.
2. Description of the Related Art
Ink-jet type printing devices are well-known in the art for their relatively simple construction and their high-speed and high-quality printing capabilities. These ink-jet printing devices employ ink-jet print heads therein.
SUMMARY OF THE INVENTION
One conceivable example of the ink-jet print head includes an actuator for selectively ejecting liquid ink in droplets. The actuator is made from a piezoelectric ceramic material, and is designed to have upper and lower end surfaces. The actuator is formed with a plurality of ejection channels. Each ejection channel extends between the upper and lower end surfaces. Each ejection channel is opened on the upper end surface to have an inflow end for receiving liquid ink flowing therein, and is opened also on the lower end surface to have an outflow end for flowing the liquid ink out of the ejection channel. The ejection channels are arranged in several (two, for example) rows. In each row, corresponding ejection channels are arranged in line. The two rows of the ejection channels are apart from each other with a predetermined distance.
A nozzle plate is attached to the lower end surface (outflow end surface) of the actuator. The nozzle plate is formed with a plurality of nozzle holes for ejecting liquid ink. The nozzle plate is attached to the actuator so that each nozzle hole is in fluid communication with an outflow end of a corresponding ejection channel.
A manifold is attached to the upper end surface (inflow end surface) of the actuator. The manifold is formed with an ink supply channel to supply liquid ink from an ink supply source (ink tank) to the ejection channels. The ink supply channel is opened at one surface of the manifold. The manifold is therefore attached to the actuator so that the opened ink supply channel is in fluid communication with the inflow ends of the ejection channels.
The ink-jet print head with the above-described structure is disposed at a downward slant of about 45 degrees, for example, so that the nozzle plate faces slantedly downwardly and the manifold is located above the nozzle plate. The actuator is partially applied with electric fields, thereby being partially transformed. The transformation in the actuator causes changes in the volume of a desired ejection channel. When the volume of the ejection channel is decreased, the liquid ink in that channel is ejected slantedly downwardly from the nozzle holes and onto a printing paper. When the volume of the ejection channel is increased, ink from the ink supply source is introduced into the ejection channel via the ink supply channel.
Problems in ink ejection can, however, occur when air bubbles are formed and retained in the ink-jet print head or when drops of ink are deposited on the surface of the nozzle plate. To maintain good quality ink ejection, a purge device is provided on the ink-jet printing device to remove by suction liquid ink containing those air bubbles from the ink-jet print head.
It is conceivable to provide two types of ink-jet print heads. In the first type of ink-jet print head, the ink supply channel has a single ink supply path in the manifold. That is, the single ink supply path is formed to extend along the two channel rows, and is opened to communicate with the inflow ends of all the ejection channels. In the second type of ink-jet recording head, on the other hand, the ink supply channel is formed to have two ink supply paths. In this type of print head, each ink supply path is formed to extend along a corresponding channel row, and is opened to communicate with the inflow ends of all the ejection channels in the corresponding channel row.
FIG. 1
shows a conceivable structure of the ink-jet print head of the first type, wherein a single ink supply channel (path)
116
is provided in the manifold
117
to supply ink to two rows of ink ejection channels
113
.
More specifically, the ink-jet print head is constructed from the manifold
117
, the actuator
114
, and the nozzle plate
111
. The actuator
114
has upper and lower end surfaces opposite to each other. The actuator
114
is formed with a plurality of ejection channels
113
. Each ejection channel
113
extends between the upper and lower end surfaces. The ejection channel
113
therefore is opened at the upper surface to define an inflow end
113
i
for receiving ink flowing to the ejection channel
113
. The ejection channel
113
is opened also at the lower end surface to define an outflow end
113
o
for flowing ink out of the ejection channel
113
.
The plurality of ejection channels
113
are arranged in two rows parallel to each other. The two rows of channels
113
and
113
are separated from each other by a predetermined amount of distance. Accordingly, the upper end surface of the actuator
113
includes: a central area
171
defined between the two rows of ejection channels
113
; and a pair of outer side areas
170
which are separated from the central area
171
and which sandwich the central area
171
therebetween. Each outer side area
170
is defined outside of the corresponding row of ejection channels
113
.
Each ejection channel
113
in each row is a hollow space defined between an outer side inner wall
151
, which extends from an inner edge of a corresponding outer side area
170
, and an inner side inner wall
150
which extends from an outer edge of the central area
171
. A distance D is provided between the outer side inner walls
151
in the two rows of ejection channels
113
.
The manifold
117
is connected to the upper end surface (inflow end surface) of the actuator
114
. The single ink supply channel
116
is formed in the manifold
117
, and is opened at the surface, where the manifold
117
is attached to the actuator
114
. The manifold
117
is connected to the actuator
114
so that the ink supply channel
116
is in fluid communication with the inflow ends
113
i
of the ejection channels
113
. As apparent from
FIG. 1
, the ink supply channel
116
is approximately arc-shaped. That is, the ink supply channel
116
is defined by an inner wall
216
which is curved into an approximately arc-shape. The ink supply channel
116
has a width W on the surface of the manifold
117
where the ink supply channel
116
is opened. More specifically, the manifold
117
has a pair of outer side areas
259
on the surface where the manifold
117
is connected to the actuator
114
. The opened end of the ink supply channel
116
is located between the pair of outer side areas
259
. The width W, defined as a distance between inner edges of the two outer side areas
259
, is larger than the distance D between the outer side inner walls
151
of the ejection channels
113
in the two rows.
The nozzle plate
111
is connected to the lower end surface (outflow end surface) of the actuator
114
. The nozzle plate
111
is formed with a plurality of nozzle holes
112
. The nozzle plate
111
is connected to the actuator
114
such that each of the outflow ends
113
o
leads to a corresponding nozzle hole
112
. With the above-described structure, liquid ink supplied from an ink supply source (not shown) is introduced via the ink supply channel
116
into the inflow ends
113
i
of the ejection channels
113
, and is ejected from the nozzle holes
112
.
When the manifold
117
and the actuator
114
having the above-described structures are joined together, the outer side areas
259
of the manifold
117
are bonded to the outer side areas
170
of the actuator
114
with adhesive. Because the width W of the ink supply channel
116
is larger than the distance D between the outer side inner walls
150
, a pair of margin portions
110
are provided on the pair of outer side areas
170
. Each margin portion
110
extends along a corresponding row of ejectio
Brother Kogyo Kabushiki Kaisha
Le N.
Nghiem Michael
Oliff & Berridg,e PLC
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