Ink feeder

Details Ink feeder Ink feeder

1998-11-16

2001-07-10

Le, N. (Department: 2861)

Incremental printing of symbolic information

Ink jet

Fluid or fluid source handling means

C347S086000

Reexamination Certificate

active

06257712

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an ink feeder for supplying ink from a main ink tank to an ink subtank via an ink supply port, and supplying ink from the ink subtank to a print head via an ink outlet in an ink-jet printer or other device.
2. Description of the Related Art
A conventional ink feeder for supplying ink from a main ink tank to an ink subtank via an ink supply port, and supplying ink from the ink subtank to a print head via an ink outlet, is disclosed in Japanese Published Examined Patent Application No. Sho 63-44064.
As shown in
FIGS. 9 and 10
, the ink subtank of a conventional ink feeder is provided to supply ink, that is supplied from a main tank
208
via a tube
209
and an ink inlet
206
A of a capillary tube
206
, to a print head via an ink outlet
207
A of a capillary tube
207
under a predetermined pressure. The interior of a casing
201
of the ink subtank stores ink, and is partitioned into multiple ink chambers A
1
and A
2
by a partition wall
203
. The partition wall
203
has an upper communicating part
204
which allows the movement of air in its upper part, and a lower communicating hole
205
provided with resistant action which allows the movement of ink in its lower part. In the ink feeder disclosed in the above patent application, the ink subtank is filled with a large quantity of ink due to the partition wall
203
and the resistant action of the lower communicating hole
205
. As shown in
FIG. 10
, the ink inlet
206
A, the lower communicating hole
205
and the ink output
207
A are approximately aligned.
In this type of ink feeder, to maintain printing quality, air, that is, a bubble in the ink, is separated in the ink subtank to prevent the bubble from flowing on the side of the print head, and the pressure of ink which acts upon the print head is set to a predetermined value based upon the positional relationship between the level of ink in the ink subtank and the print head.
However, a bubble may not be separated from the ink and may enter the print head, depending upon the position and the size of the lower communicating hole of the partition wall. However, the ink feeder that is provided with the lower communicating hole provided with resistant action and disclosed in the above patent application is subject to various problems. Specifically, it takes too long to fill the ink subtank with ink, the start of printing is delayed until the level of each ink chamber is equal, the level of each ink chamber becomes uneven, the supplement of ink is delayed and the pressure of ink which acts upon the print head is off a set value as ink is consumed, and printing quality is often deteriorated.
As shown in
FIG. 8
, for example, an ink subtank
101
previously devised by the inventors of the present invention is provided with a casing
102
that has an upper opening for storing ink and a cover
103
for closing the upper opening of the casing
102
. The interior of the casing
102
is partitioned into first to third ink chambers
110
,
111
and
112
by partition walls
108
and
109
, that are respectively provided with upper communicating parts
104
and
105
which allow the movement of air in its upper part, and lower communicating holes
106
and
107
which allow the movement of ink in its lower part. Air is separated from the ink by making ink, that is supplied from an ink supply port
101
A, meander in each ink chamber
110
to
112
in the ink subtank
101
, so that only ink is moved to the print head via an ink outlet
101
B.
An ink sensor
113
, for detecting the quantity of ink, is provided at the first ink chamber
110
. An air communicating hole
114
, which exposes the third ink chamber to the air, is provided at a portion of the cover
103
that is opposite to the third ink chamber
112
. When the ink sensor
113
detects that ink in the ink subtank
101
is decreasing as ink is jetted from the print head, a delivery device, such as a pump, is driven and ink is supplied from a main ink tank (not shown).
Since, in this type of ink subtank, ink supplied from the main ink tank is supplied to the print head under predetermined pressure, the positional relationship between the level of ink in the ink subtank and the print head effects the pressure in the print head and printing quality.
In the ink subtank
101
that has multiple ink chambers
110
to
112
, when the ink subtank is carried, or an impact is applied to it, the level of ink in each ink chamber fluctuates. Ink may thus pass the upper communicating parts
104
and
105
, and an ink film may be formed in the upper communicating parts
104
and
105
by the surface tension of ink when the ink passes. When the ink film is formed in the upper communicating parts
104
and
105
as described above, the ink chambers
110
and
111
each become a closed space. Since the level in the ink chamber
110
is unchanged independent of the state of ink in another ink chamber, if the ink chamber
110
that is provided with the ink sensor
113
becomes a closed space, for example, the ink sensor
113
is kept in either an on or off state.
If the ink sensor
113
is off, it is judged that there is not much ink, the pump is driven, and ink is supplied to the first ink chamber
110
via the ink supply port
101
A. However, since the ink chamber
110
is a closed space and the level of ink is hardly changed, the supply of ink from the main ink tank is continued. As a result, ink flows into the second and third ink chambers
111
and
112
, respectively, via the lower communicating holes
106
and
107
, ink is excessively supplied, each level of the second and third ink chambers
111
and
112
rises, and ink may overflow to the exterior via the air communicating hole
114
.
In the meantime, if the ink sensor
113
is on, it is judged that ink remains in the ink chamber, and ink is not supplied to the first ink chamber
110
. However, since the first ink chamber
110
is a closed space, the level of ink is hardly changed even if ink is consumed because of the supply of ink to the print head and ink continues to not be supplied. As a result, ink is not supplied, only ink in the second and third ink chambers
111
and
112
continues to be consumed. Finally, the amount of ink in both ink chambers
111
and
112
becomes low, and it may occur that ink cannot be supplied to the print head and the amount of ink may become low. Even if no extreme state occurs, the level of each ink chamber cannot be controlled, pressure in the print head is changed and such a state has an effect upon printing quality.
SUMMARY OF THE INVENTION
The invention is provided to solve the above problems, and its object is to provide an ink feeder for securely separating a bubble from ink, enabling ink to promptly flow into each ink chamber and the smooth supply of ink that hardly includes a bubble to the print head. Another object is to provide an ink feeder, wherein ink can be securely supplied without ink overflowing due to the excessive supply of ink or without the amount of ink becoming low.
The invention is embodied in the following embodiments and the following effect is produced.
In an ink feeder according to the invention for supplying ink from a main ink tank to an ink subtank via an ink supply port, and supplying ink from the ink subtank to a print head via an ink outlet, the ink subtank includes a casing that stores ink, and at least one partition wall that partitions the casing and forms multiple ink chambers. The at least one partition wall has an upper communicating part which allows the movement of air in an upper part of the ink chambers, and a lower communicating hole which allows the movement of ink in a lower part of the ink chambers. The ink supply port, the lower communicating hole of the at least one partition wall and the ink outlet are disposed so as not to be aligned, and the ink subtank is formed so that ink meanders.
According to the invention, ink meanders from the ink supply port to the ink outlet via the lower communicating hole in the ink sub

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