Liquid container

Details Liquid container Liquid container

1999-05-04

2003-01-07

Nguyen, Judy (Department: 2861)

Incremental printing of symbolic information

Ink jet

Fluid or fluid source handling means

Reexamination Certificate

active

06502931

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a liquid container, a method of manufacturing the container, the package of the container, an ink jet head cartridge in which the container and a recording head are made integral with each other, and a liquid discharge recording apparatus, and particularly to a liquid container suitably utilized in the field of ink jet recording or the like.
2. Related Background Art
Generally, an ink tank as a liquid container used in the field of ink jet recording is provided with a construction for adjusting the holding force of ink stored in the ink tank to well effect the supply of the ink to a recording head for discharging the ink. This holding force is for making the pressure of the ink discharging portion of the recording head negative relative to the atmosphere and is therefore called negative pressure.
As one of the easiest methods for generating such negative pressure, mention may be made of a method of providing a porous member such as urethane foam or an ink absorbing member such as felt in the ink tank, and utilizing the capillary force (ink absorbing force) of the ink absorbing member. For example, Japanese Laid-Open Patent Application No. 6-15839 discloses a construction in which a plurality of fibers differing in density from one another are compressed and packed in the whole of an ink tank in the order of high-density fiber and low-density fiber toward a supply path to a recording head. The high-density fiber has a great number of fibers per unit area and has a strong ink absorbing force, and the low-density fiber has a small number of fibers per unit area and has a weak ink absorbing force. The seams among the fibers are brought into pressure contact with each other so as to prevent the intermission of ink caused by the mixing of air.
On the other hand, the applicant of the basic application has proposed in Japanese Laid-Open Patent Application No. 7-125232, Japanese Laid-Open Patent Application No. 6-40043, etc. an ink tank provided with a liquid containing chamber of which the ink containing amount per unit area is increased in spite of an ink absorbing member being utilized and which can realize stable ink supply.
FIG. 1A
of the accompanying drawings is a schematic cross-sectional view showing the construction of an ink tank utilizing the above-described construction. The interior of an ink cartridge
10
is partitioned into two spaces by a partition wall (
38
) having a communicating hole (communicating portion)
40
. One of the two spaces provides a liquid containing chamber
36
hermetically sealed except the communicating hole
40
of the partition wall
38
and directly holding ink
25
therein, and the other space provides a negative pressure generating member containing chamber
34
containing a negative pressure generating member
32
therein. A wall surface forming this negative pressure generating member containing chamber
34
is formed with an atmosphere communicating portion (atmosphere communicating port)
12
for effecting the introduction of the atmosphere into the container resulting from the consumption of ink, and a supply port
14
for supplying the ink to a recording head portion, not shown. In
FIGS. 1A and 1B
, the area in which the negative pressure generating member holds the ink is indicated by hatching. The ink contained in the space is indicated by net lines.
In the above-described structure, when the ink in the negative pressure generating member
32
is consumed by the recording head, not shown, air is introduced from the atmosphere communicating port
12
into the negative pressure generating member containing chamber
34
, and enters the liquid containing chamber
36
through the communicating hole
40
of the partition wall
38
. Instead of this, the negative pressure generating member
32
in the negative pressure generating member containing chamber
34
is filled with the ink from the liquid containing chamber
36
through the communicating hole of the partition wall (this will hereinafter be referred to as the gas-liquid exchanging operation). Accordingly, even if the ink is consumed by the recording head, the negative pressure generating member
32
is filled with the ink in conformity with the consumed amount, and the negative pressure generating member
32
holds a predetermined amount of ink therein and keeps the negative pressure relative to the recording head substantially constant and therefore, the ink supply to the recording head becomes stable. Such an ink tank which is compact and has high use efficiency has been commercialized by the applicant of the basic application and is still used in practice.
In the example shown in
FIG. 1A
, an atmosphere introducing groove
50
as a structure for expediting the introduction of the atmosphere is provided near the communicating portion between the negative pressure generating member containing chamber and the ink containing chamber, and a space (buffer chamber)
44
free of the negative pressure generating member by ribs
42
is provided near the atmosphere communicating portion.
Also, the applicant of the basic application has proposed in Japanese Laid-Open Patent Application No. 8-20115 an ink tank using as the negative pressure generating member of the ink tank a fiber comprising olefin resin having thermoplasticity. This ink tank is excellent in ink storing stability and is also excellent in recycling property because the ink tank housing and the fibrous material are formed of the same kind of material.
Now, the inventors have zealously studied about a construction using a fibrous material as the negative pressure generating member of the ink tank shown in
FIG. 1A
with a result that it has been found that the following fact may pose a problem.
That is, when supposing the state before the start of use such as during distribution, the liquid containing chamber has been positioned and left upwardly in the direction of gravity relative to the negative pressure generating member containing chamber, as shown in
FIG. 1B
of the accompanying drawings, it has been found that by the air being introduced into the liquid containing chamber through the communicating portion, the liquid in the liquid containing chamber may leak to the negative pressure generating member and the ink
25
may overflow to the buffer chamber. If the ink thus overflows to the buffer chamber, the ink may overflow through the atmosphere communicating port to thereby stain a user's hand or the ink may drop from the liquid supply port to stain the user's hand or the like when the seal is broken.
The above-noted problem is considered to arise from the following characteristics of the ink absorbing member using fibers as compared with a porous material such as conventional urethane foam:
(1) since porosity is great, the pressure loss of ink movement is small;
(2) the difference between the advancing angle of contact and the retreating angle of contact of the ink with the fiber is small; and
(3) in the case of the ink absorbing member using the fibers, a capillary force is created in the gaps among the fibers and therefore, the difference in the local strength of the capillary force on the scale of the cell (about 80 to 120 &mgr;m) of urethane sponge is small as compared with an ink absorbing member formed by cell film being removed after urethane foam is foamed.
This problem peculiar to a construction utilizing a fiber material as the negative pressure generating member has been recognized by the inventors for the first time.
SUMMARY OF THE INVENTION
It is a first object of the present invention to provide a liquid container which utilizes a fibrous material as a negative pressure generating member and yet solves the above-noted problem.
It is a second object of the present invention to provide a liquid container having a liquid containing chamber having both of the above-described compactness and high use efficiency and free of inadvertent inflow of liquid from the liquid containing chamber to a negative pressure generating m

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