Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-08-07
2001-02-27
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S035000, C347S092000
Reexamination Certificate
active
06193355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recorder for recording images etc., on recording media with ejected ink, and more specifically relates to an ink jet recorder having a purging device for purging the recording head and a flushing device for removing air bubbles inside the recording head.
2. Description of the Related Art
Ink jet printers have been typically known as ink jet recorders for use in recording characters, images etc., on recording media such as paper etc., with ejected ink.
As shown in
FIG. 8
, a typical ink jet printer uses an ink cartridge P
1
for storage of ink which can be removably mounted in a recording head unit P
3
having a recording head P
2
, so that ink cartridge P
1
is attached to recording head P
2
by mounting it to recording head unit P
3
. The mounted ink cartridge P
1
supplies recording head P
2
with ink, which in turn is ejected from an ejection nozzle P
4
provided in recording head P
2
, thus performing printing of characters etc. Provided inside recording head P
2
is ink channels (not shown) which are defined with side-walls made up of piezoelectric elements so that ink compressed by the alternation of the intra-channel volume will be ejected from nozzle P
4
.
When predetermined conditions are satisfied during the operation of the ink jet printer, for example, automatically or by user interaction, ejecting nozzle P
4
is subjected to a so-called purging operation, by which ink inside nozzle P
4
is sucked from the ejection side of ejecting nozzle P
4
, that is, nozzle tip P
5
having openings or ejection holes (not shown).
The specific operation of purging comprises: covering nozzle tip P
5
with a suction cap P
6
; applying a negative pressure within suction cap P
6
by an unillustrated suction pump; and sucking the ink from ink cartridge P
1
and recording head P
2
by way of suction cap P
6
so as to displace the ink to the outside.
This purging operation is performed when an unused ink cartridge P
1
is replaced or initially attached, in order to initially introduce the ink inside unused cartridge P
1
into recording head P
2
. Alternatively, it is also performed in order to prevent mal-ejection of ink during the operation of the ink jet printer. A purging operation for the former purpose in particular is referred to as an initial purge or initial ink introduction purge.
When the user has mounted an unused ink cartridge P
1
as a replacement or for initial setup, air will enter recording head P
2
. More specifically, there is a commutation passage between the ink feed port on the ink cartridge P
1
and the ink inlet port on the recording head P
2
, and air will enter this commutation passage when ink cartridge P
1
is mounted into recording head P
2
.
In a typical configuration, a filter is provided at the ink inlet port of recording head P
2
, aimed mainly at the prevention of foreign substances entering recording head P
2
.
Accordingly, when the aforementioned purging operation (initial purge) is performed after replacement of an ink cartridge P
1
so that ink is rapidly sucked from the nozzle tip P
5
of ejection nozzle P
4
by means of suction cap P
6
, air within the aforementioned commutation passage rushes in and passes through the filter attached at the ink inlet port of recording head P
2
, generating a number of air bubbles. The air bubbles rapidly mix with the ink inside recording head P
2
, resultantly leaving air bubbles inside the ink channels and ejection nozzle P
4
.
In general, when ink jet printers of this type are shipped from the factory, recording head P
2
is charged with a liquid for preservation (to be referred to as a storage solution) having properties similar to the ink but containing no pigment and dye.
For this reason, also when the aforementioned purging operation is performed after the user has initially attached an ink cartridge P
1
to recording head P
2
, air inside the aforementioned commutation passage rushes in and passes through the filter attached at the ink inlet port of recording head P
2
, and the air rushes in and mixes with the ink inside recording head P
2
, resultantly generating a great deal of air bubbles and hence leaving the air bubbles inside the ink channel and ejection nozzle P
4
.
In ink jet printers of this type, there are cases where ink cartridge P
1
has a filter at its ink feed port. This filter prevents entrance of foreign substances inside cartridge P
1
into recording head P
2
and also prevents ink leakage by making use of the surface tension of ink acting on the pores of the filter. Also in this case, when, upon the implementation of purging, ink inside ink cartridge P
1
rushes through the filter provided at the ink feed port, into the aforementioned commutation passage containing air, a great number of air bubbles will be generated, resultantly leaving the air bubbles inside the ink channels and ejection nozzle P
4
.
Air bubbles remaining inside the ink channels and ejection nozzle P
4
hinder the increase in pressure for ink to be ejected out, causing mal-ejection and hence degradation of recording image.
SUMMARY OF THE INVENTION
In view of what has been discussed above, it is therefore an object of the present invention to provide an ink jet recorder which can prevent residual air bubbles within the recording head after replacement or initial attachment of an ink cartridge.
In accordance with one aspect of the invention, an ink jet recorder is provided which comprises: a recording head having an ink inlet port, a filter provided at the ink inlet port and a nozzle for ejecting ink onto recording media; an ink cartridge detachably attached to the recording head for supplying ink to the inlet port of the recording head; a purging device for purging the nozzle from the exterior of the recording head; a carriage for holding the recording head and conveying it across the width of a recording medium and an area outside thereof; an ink receiver disposed in the area outside the width of the recording medium, for receiving ink ejected for flushing; and a controller which controls the carriage and recording head in such a manner that, before purging is started by the purging device, the carriage is moved to a position where the recording head opposes the ink receiver and therein the recording head ejects ink for flushing.
The ink jet recorder of the invention, is configured so that the controller makes the nozzle active so as to eject ink toward the ink receiver for flushing operation before the purging device starts actual purging. Therefore, in accordance with the ink jet recorder of the invention, after replacement or initial attachment of an ink cartridge, initial introduction of ink can be completed successfully without leaving any air bubbles within the recording head.
As has been already described, in an ink jet printer of this type, when the ink cartridge is attached to the recording head, air will enter the joint passage between the ink feed port of the ink cartridge and ink inlet port of the recording head for receiving the ink supply from the ink feed port. Therefore, if purging is performed immediately after replacement or initial attachment of an ink cartridge as in the conventional configuration, the air having entered the joint passage will rush in and pass through the filter attached to the ink inlet port of the recording head, and mix rapidly with the liquid (ink or the aforementioned storage solution), producing a great deal of air bubbles. Further in the case where a filter is also attached to the ink feed port of the ink cartridge, ink inside the ink cartridge will rush in and pass through the filter attached at the ink feed port of the ink cartridge, and rapidly mix with the air within the joint passage, producing a further increased amount of air bubbles.
In contrast, in the ink jet recorder of the invention, the controller controls the recording head and carriage so as to perform the flushing operation by ejecting ink toward the ink receiver before purging. Therefore, even if air has entered
Brother Kogyo Kabushiki Kaisha
Le N.
Nguyen Judy
Oliff & Berridg,e PLC
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