Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1996-07-16
2002-02-26
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06350027
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet cartridge for an ink jet recording apparatus wherein image information is recorded by ejecting ink or the like toward a recording medium.
2. Description of the Related Art
Heretofore, an ink jet recording apparatus wherein image information is recorded by ejecting ink or the like toward a recording medium has employed an ink jet cartridge comprising a recording head for forming droplets of the ink ejected toward the recording medium and an ink tank for containing the ink and supplying the ink to the recording head, the recording head and the ink tank being joined together.
FIG. 1
is a cross-sectional view showing the structure of one prior art ink jet cartridge.
As shown in
FIG. 1
, the prior art ink jet cartridge mainly comprises a recording head
27
from which ink is ejected toward a recording medium (not shown), and an ink tank
20
in which the ink to be ejected from the recording head
27
is stored. The ink tank
20
contains an ink absorbing member
21
for retaining the ink that is impregnated therein. Also, the ink tank
20
has an ink supply port
22
through which the ink retained by the ink absorbing member
21
is supplied to the recording head
27
, and an atmosphere communicating port
23
through which the atmosphere outside the ink tank
20
is communicated with the air inside the ink tank
20
to prevent a negative pressure in the tank inner space from rising excessively. Further, as disclosed in Japanese Patent Laid-Open No. 3-101971, the ink tank
20
is provided on its inner wall surfaces with ribs
24
to
26
which serve to distribute the ambient air introduced through the atmosphere communicating port
23
to various portions of the ink absorbing member
21
, enabling the ink impregnated in the ink absorbing member
21
to be evenly introduced to the ink supply port
22
. In a portion of the rib
24
near the atmosphere communicating port
23
, the height of the rib
24
projecting from the inner wall surface of the ink tank
20
is greater than in the other portion of the rib
24
so that the ambient air introduced through the atmosphere communicating port
23
is certainly supplied to the ink absorbing member
21
.
In the ink jet cartridge described above, the ink impregnated in the ink absorbing member
21
is supplied to the recording head
27
through the ink supply port
22
by the capillary-attraction depending on consumption of the ink in the recording head
27
. The ink is then ejected toward the recording medium from the recording head
27
. Corresponding to the amount of the ink consumed, the ambient air is introduced to the ink tank
20
through the atmosphere communicating port
23
.
In order to that the ink absorbing member
21
can properly retain the ink therein, the amount of the ink impregnated in the ink absorbing member
21
must be less than the volume of the ink absorbing member
21
, while allowing the ink absorbing member
21
to develop the capillary attraction. To this end, a vacant space (a portion A in
FIG. 1
) where the ink is not impregnated from the beginning necessarily exists in the ink absorbing member
21
. No matter where the vacant space exists, the ink absorbing member
21
can sufficiently develop its function of retaining the ink therein. But if the vacant space exists near the ink supply port
22
, the ink flow may be blocked to prevent the ink from being supplied to the recording head
27
. To avoid that the vacant space where the ink is not impregnated will exist near the ink supply port
22
, the ink is poured into the ink tank through the ink supply port
22
in the manufacture process.
The ink poured through the ink supply port
22
flows through the ink absorbing member
21
and reaches the rib
26
. Then, the ink passes gaps or guide paths formed by the ribs
26
,
25
and
24
and comes to the side near the atmosphere communicating port
23
. The ink is thus impregnated in the ink absorbing member
21
while finally leaving a vacant space in the portion A.
Here, the ink absorbing member
21
is inserted in the ink tank
20
in a compressed state.
In the prior art ink jet cartridge described above, however, because a portion of the rib
24
near the atmosphere communicating port
23
projects from the inner wall surface of the ink tank with greater height than in the other portion of the rib
24
so that the ambient air introduced through the atmosphere communicating port
23
is certainly supplied to the ink absorbing member
21
, a portion B of the ink absorbing member
21
where it bumps the above higher portion of the rib
24
is brought into a more compressed state than in the other portion of the ink absorbing member
21
when the ink absorbing member
21
is inserted in the ink tank
20
in a compressed state. Therefore, when the ink is poured into the ink tank
20
, the ink is impregnated in a more amount in the portion B of the ink absorbing member
21
.
In practical use, there occur no problems even with the ink so impregnated in the ink absorbing member. But if the ink jet cartridge is subjected to a thermal impact or a pressure reduced state while it is delivered from the manufacture factory to the user, the air near the portion A expands, whereupon the ink accumulated in the portion B is pushed out to leak into a space where the atmosphere communicating port
23
is located. In the worst case, the leaked ink is forced to exude to the outside of the ink jet cartridge, resulting in a feat that the user's hands or cloth may be stained with the ink leaked out when the user opens the cartridge package.
Also, it is thought that the cartridge package is opened under an atmospheric pressure as low as 0.7 in some cases depending on the altitude of the place where the user employs an ink jet cartridge. Under such a low atmospheric pressure, the ink may also leak to the outside of the ink jet cartridge as with the foregoing case.
To prevent the leakage of ink in those situations, a buffer chamber is generally provided between the atmosphere communicating port
23
and the ink absorbing member
21
, making it hard for the ink leaked out of the ink absorbing member
21
to exude to the outside of the ink jet cartridge. However, the volume of the buffer chamber is so very small that the function of the buffer chamber is not always developed satisfactorily.
Further, if the ink is impregnated in a portion of the ink absorbing member
21
which enters the buffer chamber, the guide paths formed by the ribs for distributing the ambient air introduced through the atmosphere communicating port
23
to various portions of the ink absorbing member are blocked off. This raises the problem that the ink impregnated in the ink absorbing member is no longer uniformly supplied to the recording head
27
.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the above-stated problems in the prior art, and its object is to provide an ink jet cartridge which can prevent an ink absorbing member from entering a buffer chamber and which can uniformly supply ink impregnated in the ink absorbing member to a recording head.
Another object of the present invention is to provide an ink jet cartridge which can prevent ink from leaking to the outside even if the cartridge is subjected to a thermal impact or a pressure reduced state.
To achieve the above objects, the present invention provides an ink tank for storing ink supplied to an ink jet recording head, the ink tank comprising an ink tank body, an ink absorbing member inserted in the ink -tank body in a compressed state, an atmosphere communicating port for communicating an inner space of the ink tank body with the atmosphere, and an ink supply port coupled to the ink jet recording head and serving as an ink supply port, wherein a corner of the ink absorbing member which would be located near the atmosphere communicating port is cut out, a portion of the ink absorbing member around the cutout area is partly released in a degree of compression as co
Iketani Masaru
Okada Masaaki
Taneya Yoichi
Le N.
Nghiem Michael
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