Note: Descriptions are shown in the official language in which they were submitted.
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INK CARTRIDGE
FIELD OF THE INVENTION AND RELATED ART
This is a divisional application of Canadian
Patent Application Serial No. 2,130,300, filed on
August 17, 1994, and entitled "Ink Cartridge".
The present invention relates to an ink
cartridge for containing ink to supplied to a recording
head, which is detachably mountable to the recording
head, or to the recording apparatus.
An ink jet recording apparatus, particularly
an ink jet recording apparatus using thermal energy for
ejecting ink, is widely used with various apparatuses
such as printers, facsimile machines, copying machines
or the like, as a means for recording on a recording
material.
From the standpoints of apparatus downsizing,
cost reduction, maintenance free or the like, a
cartridge type recording means in which a recording
head and an ink container are connected and are
detachably mountable to a carriage in a recording
apparatus.
The cartridge type recording means includes
two types, in one of which the recording head and the
ink container are unified, and in the other of which
the recording head and the ink container are separate
but are unified on the carriage. Recently, the service
life of a recording head is extended as compared with
the ink capacity of the ink container, the latter type
cartridge is noted.
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As for the structures of the exchangeable ink
containers, there are various types, in one of which
an ink absorbing material occupies substantially the
entirety of the ink containing space to provide the
recording head with a desired vacuum, which will be
called hereinafter "full-sponge type". In another
type, the ink absorbing material occupies
approximately one half of the ink containing space.
This has been proposed for the purpose of increasing
the ink capacity. This will be called "half-sponge
type".
In a further example, the inside of the ink
container is filled with the liquid ink only for the
purpose of further increasing the ink capacity, in
which the vacuum is provided by another mechanism.
This will be called "full-ink type".
Among these types, the present invention is
directed to a half-sponge type cartridge with which
the ink capacity is relatively large, and the vacuum
generation is relatively easy.
Referring to Figure 1, there is shown an
example of a half sponge type ink cartridge in a
perspective sectional view. The main body 1 of the
ink cartridge is provided with an ink supply port 2
for connection with an ink jet recording head, and an
air vent 10 for introducing the ambient air, provided
above the ink supply port 2. It comprises a vacuum
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producing material containing portion 4 for containing
the vacuum producing member such as a water absorbing
sponge or the like for retaining the recording ink,
and an ink accommodating portion 6 for containing ink,
adjacent the vacuum producing material accommodating
portion 4 through a rib 5. An ink containing portion
6 and the vacuum producing material accommodating
portion 4 are in fluid communication with each other
through a clearance 8 formed between the rib 5 and the
bottom surface. The bottom surface of the ink
container 6 is provided with an ink supply port 7 for
filling the initial ink. After the filling of the
ink, the port 7 is sealed by an unshown sealing
member.
With the structures described above, the ink
supplied into the ink container 6 through the supply
port 7 is also retained in a desired region of the
negative pressure generating member 3 in the negative
pressure generating material accommodating portion 4.
It is supplied to a recording head through an unshown
ink supply tube contacted to the material 4, through
the ink supply port 2. In accordance with the amount
of ink consumption, the material 3 absorbs the ink in
the ink containing portion 6, and a corresponding
amount of air is introduced into the ink container 6
from the air vent 10 through the accommodating portion
4, thus maintaining the ink supply to the recording
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head.
The ink container 6 is constituted by
orthogonal flat walls, so that a relatively large
amount of the ink can be contained. The bottom
surface of the ink container 6 is flat to provide
smooth flow of the ink.
Because of the recent downsizing and the
transportability of the recording apparatus, the
position of the recording apparatus varies very much,
for example, when the recording apparatus is not used,
it may be placed upside down. In addition, it can be
placed for a long term under various ambient
conditions. These situations increase the possibility
of leakage of the ink from the ink cartridge.
Figure 2 illustrates ink leakage when the ink
cartridge is placed upside down, and ambient condition
change occurs.
More particularly, it is placed upside down
in a thermostatic chamber under 60 °C. The ink hardly
moves when the ink is not used at all, that is, the
ink container 6 is full of the ink. However, if the
ink in the ink container 6 decreases to provide a gap
between the ink level surface and the internal surface
of the cartridge body, the water vapor from the ink is
condensed into dew deposited on the bottom surface
which is now at the top. Then, since the vacuum
producing portion 4 which is under a negative pressure
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absorbs the dew through the clearance 8. By repeating
these steps, the ink moves from the ink container 6 to
the portion 4, with the result that the container 4 is
filled with the ink. When this state is reached, the
ink may leak through the ink supply port 2 or the air
vent 10.
Since the corners of the ink accommodating
portion are not rounded so that the ink is taken by
the capillary force provided by the corners, so that
the ink moves into the vacuum producing material
accommodating portion 4 by the negative pressure
therein.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the
present invention to provide an improved ink
cartridge.
It is another object of the present invention
to provide an ink cartridge with which the ink does
not leak even if it is placed upside down:
It is a further object of the present
invention to provide an ink cartridge with which the
ink does not leak even if the ambient condition
changes.
It is a yet further object of the present
invention to provide an ink cartridge with which the
ink movement is substantially prevented toward a
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vacuum generating material accommodating portion, so
that the ink does not leak through an ink supply port
or an air vent.
According to an aspect of the present
invention, there is provided an ink cartridge for
supplying ink to a recording head, comprising: a
vacuum producing material accommodating portion for
accommodating a vacuum producing material; an ink
containing portion for containing ink, adjacent the
material accommodating portion, with which the ink
containing portion is in fluid communication through
an opening at a bottom portion; an ink supply opening
for permitting supply of the ink, in the material
accommodating portion; an inward projection in the ink
containing portion; and the projection is not less
than 0.2 mm away from a boundary between the material
accommodating portion and the ink containing portion.
According to this aspect, the dew drops
deposited on the bottom surface in the ink container
are prevented from moving to the vacuum producing
material accommodating portion and are returned to the
ink container.
According to another aspect of the present
invention, corners in the ink container is curved,
thus preventing occurrence of the capillary force.
Therefore, the ink is not moved up, thus further
preventing the movement of the ink. Therefore, the
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ink leakage can be further prevented.
These and other objects, features and
advantages of the present invention will become more
apparent upon a consideration of the following
description of the preferred embodiments of the
present invention taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective sectional view of a
conventional ink cartridge.
Figure 2 is a sectional view illustrating
leakage of the ink in the conventional ink cartridge.
Figure 3 is a perspective sectional view of
an ink cartridge according to an embodiment of the
present invention.
Figure 4 is a sectional view of an ink
cartridge according to the embodiment of the present
invention.
Figure 5 illustrates prevention of the ink
leakage according to the present invention.
Figure 6 is a sectional view of an ink
cartridge according to another embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 3 is a perspective sectional view of
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an ink cartridge according to an embodiment of the
present invention, Figure 4 is a cross-sectional view
of the same, and Figure 5 illustrates the prevention
of the ink leakage in the embodiment. The same
reference numerals as in Figures 1 and 2 are assigned
to the elements having the corresponding functions,
and the detailed description thereof is omitted for
simplicity.
In this embodiment, the ink container portion
6 in fluid communication with the vacuum producing
material accommodating portion 4 through a clearance 8
at the bottom portion, is provided with a partition
rib 12 extending in a top half portion and one or more
plate-like projections 13 extending from the bottom
into the inside.
The corner formed by adjacent side inner
surfaces of the ink containing portion 6, a corner
formed by an internal side surface of the ink
containing portion 6 and the projection 13, and a
corner formed between an internal side surface and the
partition rib 13, are curved so that smooth surface is
formed therebetween. The curvature is determined such
that the capillary force is not produced by the
corners.
The ink cartridge is placed upside down in a
thermostatic chamber under 60 °C. As will be
understood from Figure 5, the dew drops produced by
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evaporation of the ink in the ink containing portion 6
fall along the projection 13, and do not move into the
vacuum producing material accommodating portion 4.
Additionally, when the ink cartridge is
placed upside down, the corners extending vertically
are rounded so that the capillary force is not
produced, thus assuring the movement of the ink from
the ink containing portion 6 into the accommodating
portion 4, with certainty.
As show in Figures 4 and 5, the projection 13
is disposed away from the rib 5 by c and has a height
b. In order to permit use-up of the ink containing
portion 6, a part of the projection 13 is cut away.
In the example of Figure 4, opposite ends of the
Projection 13 provide the gap.
The height b of the projection 13 is so
selected that the evaporated ink does not easily go
over the projection 14, more particularly, it is
approx. 1 - 3 mm. In it is too high, the ink supply
during the normal recording may be deteriorated
particularly when the quantity of the ink reduces,
since the ink supply is permitted only through the
cut-away portion.
The height a of the clearance 8 between the
rib 5 and the ink cartridge is approx. 1.5 mm, and the
height b is preferably larger than the height a, since
then, the circumvention of the evaporated ink can be
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properly prevented.
As regards the distance c between the rib 5
and the projection 13, if it is too short, the ink
supply during the normal recording is deteriorated
because of increased flow resistance and the
resulting poor air-liquid exchange. If it is too
long, the evaporated ink limitation effect is
insufficient. More particularly, if the distance c
is long, the evaporated ink is condensed on the
Portion, and may reach the material accommodating
portion 4. For these reasons, it is preferably
approx. 0.2 - 1.5 mm.
The structure is particularly usable with
the half-sponge type ink cartridge. For example, it
is usable in a recording head cartridge having an
integral ink container. It is also usable for a
large size ink containing chamber, as shown in Figure
6.
In Figure 6, the ink containing chamber 6 is
Provided around the vacuum producing material
accommodating portion 4. In this example, the ink
containing portion 6 is generally L-shaped having
faces common with the material accommodating portion
4.
The L-shaped ink containing portion 6 is
provided with first and second projections indicated
by reference numerals 13-1 and 13-2. The projection
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13-1 generally divides the ink containing portion into
large parts 6-1 and 6-2 to prevent circumvention of
the evaporated ink from the ink containing portion
6-1. The projection 13-2 is intended to prevent
circumvention of the evaporated ink from the ink
containing portion 6-2.
Each of the projections 13-1 and 13-2 is
provided with a groove or grooves to permit
consumption of the entirety of the ink from the ink
containing portions 6-1 and 6-2.
For these projections 13-1 and 13-2, the
height b, the clearance 8 and the distance c are
determined under substantially the same conditions as
in Figure 5 embodiment.
In addition, the intersection between
internal walls of the ink cartridge are curved to
prevent the circumvention of the ink along the
corners, and therefore, it is preferable.
In the foregoing, the description has been
made as to the structure in which the ink cartridge is
placed upside down. However, the ink cartridge may be
placed another way, for example, the material
accommodating portion 4 is at the bottom, the ink
containing portion 6 is at the bottom.
Therefore, it would be considered that the
optimum position of the projection 13 is different
depending on in what way the ink cartridge is placed.
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However, if the projection 13 is provided on the
bottom surface when the ink cartridge is used, the ink
leakage can be effectively prevented.
As described in the foregoing, according to
the present invention, even if the ink cartridge is
placed upside down under high temperature room such as
60 °C, the dew droplets produced by the evaporation of
the ink in the ink containing portion falls along the
projection from the bottom surface of the ink
containing portion, and therefore, do not move into
the vacuum producing material accommodating portion.
By providing a curved surface at the meeting
portions of the vertical inner surfaces, the
capillary action does not occur at the corners
otherwise formed, so that the movement of the ink
from the ink containing portion into the vacuum
producing material accommodating portion can be
prevented with further certainty. Therefore, even if
the ink cartridge is kept under the above-described
extreme conditions, the ink leakage through the ink
supply port or the air vent can be prevented, while
the ink can be supplied into the recording head is
stability during the recording operation, thus
improving the reliability.
While the invention has been described with
reference to the structures disclosed herein, it is
not confined to the details set forth and this
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application is intended to cover such modifications or
changes as may come within the purposes of the
improvements or the scope of the following claims.
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