Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-03-20
2004-01-27
Meier, Stephen D. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S056000
Reexamination Certificate
active
06682185
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to liquid drop jet heads and ink jet recording apparatuses, and more particularly, to a liquid drop jet head used for an ink jet recording apparatus and the ink jet recording apparatus used as a picture recording apparatus or picture forming apparatus.
2. Description of the Related Art
An ink jet recording apparatus is used as a picture forming apparatus or picture recording apparatus such as a printer, facsimile, or copy machine. An ink jet head is used for the ink jet recording apparatus as a liquid drop jet head. The ink jet head includes a nozzle, a liquid room, and a pressure generating means. An ink drop is jetted out by the nozzle. The nozzle is connected to the liquid room. The liquid room is called a pressurized liquid room, pressure room, jet room, or ink channel. The ink in the liquid room is pressurized by the pressure generating means. The ink drop is jetted out from the nozzle due to the pressure in the liquid room generated by the pressure generating means.
There are several types of ink jet heads such as a piezo type, a bubble type (thermal type) or an electrostatic type. In the piezo type ink jet head, the ink drop is jetted out by deforming or displacing a vibration board forming a wall surface of the liquid room with a electric machine conversion element such as a piezoelectric element. In the bubble type ink jet head, the ink drop is jetted out by a bubble generated by boiling an ink film with an electric heat conversion element. In the static electricity type ink jet head, the ink drop is jetted out by deforming the vibration board with an electrostatic force caused by the vibration board (or an electrode united with the vibration board) forming the wall surface of the liquid room and an electrode facing the vibration board.
In a related art ink jet head, a liquid room and a common liquid room connected to the liquid room are made of photosensitive resin, resin mold, metal, glass or others. However, since the liquid room made of resin has low rigidity, cross talk is apt to occur between neighboring liquid rooms so that it is not possible to obtain a high quality picture. On the other hand, a liquid room made of metal or glass has high rigidity so that the problem regarding cross talk is small. However, since it is difficult for the liquid room made of metal or glass to be processed, it is difficult to meet a demand that the ink jet head have a high density to obtain a high quality picture.
In order to solve the above mentioned problems, for example, it is proposed to form the liquid room or the common liquid room by anisotropic-etching of a silicon substrate (silicon wafer), in Japanese Laid-Open Patent Applications No. 7-132595 and No. 7-276626. The silicon has a high rigidity and can be fine-processed by anisotropic-etching. Particularly, it is possible to form a perpendicular wall surface by using the silicon wafer of a surface direction of (110), so that the liquid room can be arranged with high density.
FIG. 1
is a plan view for explaining a configuration of the liquid room of a related art ink jet head. The liquid room structure of the related art shown in
FIG. 1
is made by anisotropic-etching of the silicon substrate of the surface direction of (110). Plural liquid rooms
201
, a common liquid room
202
and an ink supply opening part
203
are arranged in the liquid room structure. Each of the liquid rooms
201
has a configuration of a parallelogram on a plane level. The common liquid room
202
has a polygonal configuration consisting of plural parallelograms on a plane level. The common liquid room
202
is connected to the liquid rooms
201
by a fluid resister part (ink supply channel) not shown in FIG.
1
. The ink is supplied from outside of the ink jet head to the common room
202
by the ink supply opening part
203
.
When the liquid room
201
or the common liquid room
202
is formed by anisotropic-etching of the silicon substrate, the configuration of the liquid room
201
or the common liquid room
202
is formed only in a direction along a crystal direction due to anisotropy of the silicon substrate. Therefore, although the liquid rooms
201
are formed at a side of the direction along the crystal direction of the silicon substrate, the common liquid room
202
having a larger area than the liquid rooms
201
has a configuration tightly consisting of the tightly spaced plural parallelograms formed to a direction of the row of the liquid rooms
201
. Therefore, as shown in
FIG. 1
, the common liquid room
202
has wall surface parts
202
a
and
202
b
which are along the row of the liquid rooms
201
and which have a configuration of saw teeth.
Meanwhile, a bubble often gets into the liquid room or the common liquid room in the ink jet head, when an ink tank is exchanged or due to an external vibration. Because of this, a bubble discharge method is applied as an operation for recovering reliability in an ink jet recording apparatus. In the method, the ink is absorbed from the nozzle or an outlet for the bubble, so that the bubble is removed together with the ink.
However, as described above, the wall surface of the common liquid room has the configuration of the saw teeth on a plane level. Therefore, a current speed of the ink supplied from the ink supply opening part
203
is reduced by the wall surfaces
202
a
and
202
b
of the common room
202
. As a result, a bubble B adheres to a corner part of the wall surfaces
202
a
and
202
b
, the wall surfaces
202
a
and
202
b
having the configuration of saw teeth, so that the bubble B is not discharged. The bubble B may be left even if the bubble discharge method is applied as the operation for recovering reliability.
In this case, a bubble discharge may be improved by cutting the corner part of the wall surfaces
202
a
and
202
b
obliquely. However, there is a still problem in that the speed of the ink is reduced at an area remote from the ink supply opening part
203
by the wall surfaces
202
a
and
202
b
having the configuration of saw teeth during the operation the bubble discharge method. As a result, it is not possible to discharge the bubble completely.
Furthermore, during the ink jet operation, the ink is not sufficiently supplied to a liquid room remote from the ink supply opening part
203
so that bad jetting may result.
In addition, generally, a common liquid room connected to plural liquid rooms has a large opening area. Particularly, the opening area is further increased as the number of the nozzles increases for the high density and high speed recording. As a result, the strength of the ink jet head is reduced so that a yield rate is reduced due to damage of the ink jet head during assemble.
Furthermore, the common liquid room has a large opening part. Therefore, when a nozzle board is connected, the nozzle board is bent, damaged, or incorrectly-connected due to a non-uniform load while connecting, at the common liquid room.
SUMMARY OF THE INVENTION
Accordingly, it is a general object of the present invention to provide a novel and useful liquid drop jet head, ink cartridge, and ink jet recording apparatus in which one or more of the problems described above are eliminated.
Another and more specific object of the present invention is to provide a liquid drop jet head, by which a bubble saved in a common liquid room is discharged smoothly, and by which liquid is supplied to all liquid rooms sufficiently and stable jetting of a liquid drop is implemented during an operation of jetting of the liquid drop. It is also the object of the present invention to provide an ink cartridge into which the liquid drop jet head is integrated, and an ink jet recording apparatus where the liquid drop jet head is loaded.
The above objects of the present invention are achieved by a liquid drop jet head, including a nozzle jetting a liquid drop, a liquid room connected to the nozzle, a common liquid room connected to the liquid room, a supply opening part supplying the liquid to the commo
Fujii Mitsumi
Hashimoto Kenichiro
Katoh Tomomi
Maki Tsuneo
Yamaguchi Kiyoshi
Cooper & Dunham LLP
Do An H.
Meier Stephen D.
Ricoh & Company, Ltd.
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