Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-03-10
2001-02-20
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06190008
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to an inkjet head, and more particularly, to a bubble remover for an inkjet head comprising an ink tank, an ink reservoir having a nozzle array, and an ink supply path for introducing ink from the ink tank to the ink reservoir, and a method for removing bubbles thereof.
2. Description of the Related Art
FIG. 7
is a sectional view illustrating a conventional inkjet head and a maintenance mechanism disclosed in, for example, Japanese Patent Laid-open Application No. Hei 5-220970.
First, the inkjet head is described. Numerals
1
,
2
, and
7
of the figure denote a nozzle array where a plurality of nozzles are provided, an opening for directly sucking ink from an ink reservoir
3
, and an ink cartridge as an ink tank, respectively. The ink reservoir
3
has the nozzle array
1
formed of the plurality of nozzles, and is normally filled with ink supplied from the ink tank
7
. A numeral
4
denotes an ink supply path for introducing ink from the ink tank
7
to the ink reservoir
3
.
Next, the maintenance mechanism is described. A cap portion
8
is detachably attached to the distal end side of the nozzles of the nozzle array
1
, and sucks ink via the nozzles from the ink reservoir
3
. A numeral
9
denotes a second cap portion for sucking ink via the opening
2
from the ink reservoir
3
. Numerals
15
and
16
are solenoid valves for opening and closing suction paths extendedly provided from the first and second cap portions
8
and
9
, respectively. A numeral
17
denotes a suction pump for sucking ink via the suction paths from the first and second cap portions
8
and
9
.
A conventional inkjet head and a conventional maintenance mechanism are constructed as mentioned in the above. Ink suction ordinarily conducted for maintenance (hereinafter referred to as ordinary ink suction) is carried out by, after closing the solenoid valve
16
leading to the second cap portion
9
and opening the solenoid valve
15
leading to the first cap portion
8
, actuating the suction pump
17
to suck ink via the nozzles from the ink reservoir
3
, thereby discharging bubbles
19
inside the ink reservoir
3
, particularly those generated in the vicinity of the region where the nozzle array
1
is provided on the base side, to the side of the first cap portion
8
together with the sucked ink.
However, the bubbles
19
in the ink reservoir
3
which can not be removed by the ordinary ink suction in the construction mentioned in the above are dealt with by special ink suction described in the following.
First, the solenoid valve
15
leading to the first cap portion
8
is closed, and the solenoid valve
16
leading to the second cap portion
9
is opened. Then, the suction pump
17
is actuated to directly suck ink in the ink reservoir
3
not via the nozzles but through the suction path via the opening
2
and the solenoid valve
16
. This special ink suction makes ink in the ink tank
7
continue to flow from the ink supply path
4
through the ink reservoir
3
into the opening
2
during the suction continues. The bubbles
19
in the vicinity of the region where the nozzle array
1
is provided, which is a connecting portion between the ink reservoir
3
and the nozzles, are washed away by the continuous ink flow toward the opening
2
, and, eventually, the bubbles
19
are taken out on the side of the second cap portion
9
via the opening
2
.
With the conventional construction mentioned in the above, since the special ink suction, which is sucking operation not via the nozzles but from the opening
2
provided on the side of one end of the ink reservoir
3
, can be conducted other than the ordinary ink suction for maintenance which is sucking operation via the nozzles, two kinds of ink flows can be generated in the ink reservoir
3
. The bubbles
19
generated in or moved into the regions of the ink flows can be washed away by the ink flows.
However, the bubbles
19
generated in or moved into a region out of the two kinds of ink flows mentioned in the above, particularly relatively fine bubbles
19
generated in and attached to the vicinity of the region where the nozzle array
1
is provided on the base side, have strong adhesion. There was a problem that, since it is difficult for the conventional ink flows to wash such bubbles away or separate them from the place where they adhere and they are difficult to float in the ink flows, they can not be easily removed.
Further, since the conventional method requires continuous ink flow in order to remove the bubbles
19
, there is a problem of diseconomy, i.e., waste of ink.
SUMMARY OF THE INVENTION
The present invention is made to solve the above problems, and an object of the present invention is to provide a bubble remover for an inkjet head capable of, without wasting ink, removing bubbles which can not be removed by a conventional ink flow (suction), and a method for removing bubbles thereof.
According to one aspect of the present invention, an inkjet head comprising an ink tank, an ink reservoir having a nozzle array, and an ink supply path for introducing ink from the ink tank into the ink reservoir is characterized by further comprising a supply control valve for opening and closing the ink supply path, a vent hole provided with a vent control valve for making the ink reservoir in communication with the external, an ink suction means for sucking ink from the ink reservoir, and a suction control means for making the ink suction means suck ink from the ink reservoir with the supply control valve closed and with the vent control valve open.
According to another aspect of the present invention, a method for removing bubbles of an inkjet head comprising an ink tank, an ink reservoir having a nozzle array, and an ink supply path for introducing ink from the ink tank into the ink reservoir is characterized in that ink is sucked from the ink reservoir as the outside air is introduced by an ink suction means into the ink reservoir via a vent hall for making the ink reservoir in communication with the external, negative pressure being applied to the ink reservoir by the suction of ink, with the ink supply path closed and with the vent hall open.
According to still another aspect of the present invention, an inkjet head comprises an ink tank, an ink reservoir having a nozzle array, and an ink supply path for introducing ink from the ink tank into the ink reservoir is characterized by further comprising a tilt means for tilting the inkjet head such that ink filling the ink reservoir flows back toward the ink supply path to retreat at least from the region where the nozzle array is provided in the ink reservoir and a vent hall provided with a vent control valve for making the ink reservoir in communication with the external such that the retreat of ink is facilitated.
REFERENCES:
patent: 5757399 (1998-05-01), Murayama et al.
patent: 803362 (1997-10-01), None
patent: 4-1055 (1992-01-01), None
patent: 5-220970 (1993-08-01), None
patent: 6-55742 (1994-03-01), None
Fukumoto Hiroshi
Iwashita Yoshitaka
Matsuo Hirohumi
Tokumaru Susumu
Le N.
Mitsubishi Denki & Kabushiki Kaisha
Nghiem Michael
Sughrue Mion Zinn Macpeak & Seas, PLLC
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