Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-08-07
2002-07-16
Nghiem, Michael (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06419349
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid storage container, a liquid ejecting device and a liquid ejecting apparatus with improved liquid supply property.
The present invention can be applied to a facsimile equipped with a copying unit and a communication unit, a word processor equipped with a printing unit etc. and moreover a printing apparatus for an industrial use combined with various processing units as well as an ordinary printing apparatus.
2. Brief Description of the Related Arts
Generally speaking an ink tank (a tank built in a recording head and an exchangeable tank is included) equipped into a printing apparatus in an ink-jet recording method, has a constitution capable of adjusting holding property of ink (Here a liquid used for enhancing a recording quality and so on is included in ink.) stored in the ink tank so as to supply the ink in a good condition to a recording head to eject ink. Since the holding property renders a pressure at ejection ports of the recording head negative against the atmosphere, it is called a negative pressure. (Hereinafter a member that generates such negative pressure is also referred as a “negative pressure generating member”.)
As one of the easiest ways to generate the negative pressure, a method to utilize a capillary effect of the negative pressure generating member formed out of polyurethane foam equipped in the ink tank is often employed.
The applicant proposed in a laid-open Japanese patent No. 8-20115 an ink tank which employs fibers out of a polyolefine thermoplastic resin having various excellent properties against ink as the negative pressure generating member (A negative pressure generating member employed such fibers is also referred as “a fiber absorber”.)
This ink tank bears not only excellent storage stability but also an excellent recycling property, since the tank body and the negative pressure generating member are formed out of the same kind of material.
The applicant also proposed in laid-open Japanese patents No. 7-125232 and No. 6-40043 etc., an ink tank comprised of a compartment accommodating the negative pressure generating member and a compartment accommodating ink together so as to improve volume efficiency of ink in the ink tank (Hereinafter the tank comprised in this way is referred as “an ink tank with double compartments”.).
FIG. 15
shows a sectional schematic constitutional view of the above-mentioned ink tank with double compartments. The inner part of an ink tank
1
constituted in the above-mentioned way is divided by a separating wall
2
having a connecting opening
10
into two compartments one of which is virtually closed except the connecting opening
10
of the separating wall
2
and is used as a liquid accommodating compartment
3
for holding ink directly, and the other compartment is used as a negative pressure generating member accommodating compartment
4
for accommodating a negative pressure generating member
5
. On walls comprising the negative pressure generating member accommodating compartment
4
, an opening
6
is formed on a top wall
4
a
for importing air and an opening
8
for ink supply bearing a ink exporting member
7
is formed on a bottom wall
4
b
for supplying ink to a unshown recording head. In
FIG. 15
a portion of the negative pressure generating member
5
which holds ink is shown as an area below a wave formed line. And accommodated ink in the liquid accommodating compartment is depicted with broken lines.
In the above-mentioned structure when ink is consumed at the unshown recording head, the air is imported into the negative pressure generating member accommodating compartment
4
via the opening
6
and enters into the liquid accommodating compartment
3
via the connecting opening
10
on the separating wall
2
. In return, ink flows from the ink accommodating compartment
3
via the connecting opening
10
into the negative pressure generating accommodating compartment
4
and filled in the negative pressure generating member
5
. (Hereinafter this movement is referred as “a gas/liquid exchange movement.”) Consequently, even if ink is consumed at the recording head it is filled in the negative pressure generating member
5
in response to a consumed amount of ink so as to hold a constant amount of ink in the negative pressure generating member
5
and so as to keep the negative pressure against the recording head constant, thus a stable ink supply is attained.
As shown in
FIG. 15
spaces where the negative pressure generating member is not filled, are formed by ribs
9
around the opening
6
connected with the atmosphere, namely buffer compartments
11
and an air importing portion
12
to enhance importing air, is formed around the connecting opening
10
between the negative pressure generating member compartment
4
and the liquid accommodating compartment
3
.
In the above-mentioned ink tank with double compartments, contacting portions of the negative pressure generating member
5
with the separating wall
2
, particularly a portion of the negative pressure generating member
5
contacting with the air importing portion
12
have a important role for determining an ink supplying property.
Namely, when a contact between the negative pressure generating member
5
and the separating wall
2
is so intimate that the negative pressure generating member
5
in the vicinity of the air importing portion
12
becomes denser, namely, the capillary effect of the portion is raised higher than surrounding portions. As a result, even ink held in the negative pressure generating member
5
is consumed, ink held around the air importing portion
12
is not consumed so that finally the air is not imported into the liquid accommodating compartment
3
and in some cases the ink supplying movement is finished as the ink remains in the liquid accommodating compartment
3
.
Usually the negative pressure generating member
5
employed in the ink tank with double compartment has to be inserted into the negative pressure generating member accommodating compartment
4
after compressing the member. Namely, the forced insertion after the compression is necessary to avoid forming unnecessary air gaps that may cause ink drips, when gaps are formed between inner walls of the ink tank and the negative pressure generating member
5
and when the gaps are directly connected with the air. Since there is a probability that a displacement of the negative pressure generating member
5
may occur due to an unexpected fall of the ink tank, it is necessary to fix the negative pressure generating member
5
by the aide of elastic force derived from insertion of the compressed negative pressure generating member
5
with a larger size by a certain margin. However, in this case, as mentioned above, since a density of the portion of the negative pressure generating member
5
around the separating wall
2
becomes higher, in some cases the ink supply may be interrupted.
As measures against the above-mentioned ink interruption, a structure where a density in the portion of the negative pressure generating member
5
corresponding to the air importing portion
12
is reduced by forming the air importing portion
12
inner than the face of the separating wall
2
, namely, by forming a negative pressure relaxing portion
13
is proposed. By introducing such structure having the negative pressure relaxing portion a stable gas/liquid exchange is attained due to the enhanced air import.
When the polyurethane foam is employed as the negative pressure generating member
5
, a negative pressure relaxing effect is attained by forming the above-mentioned relaxing structure since the polyurethane foam can be pushed into such relaxing structure.
However, the applicant and others have found that in some cases the negative pressure relaxing structure does not function well when a fibrous absorber is employed as the negative pressure generating member in the above-mentioned ink tank with double compartments. Namely, as shown in
FIGS. 16A and 16B
a por
Iwanaga Shuzo
Udagawa Kenta
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Nghiem Michael
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