Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-09-12
2004-02-24
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000, C347S034000
Reexamination Certificate
active
06695431
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an liquid jet apparatus which includes a liquid jet head, such as a recording head for an ink jet type recording apparatus, an electrode member ejection head for an electrode forming apparatus, an organic substance jet head for a bio chip manufacture apparatus, etc., and includes a liquid collection unit adapted to receive liquid droplets jetted when a flushing drive signal is supplied to this liquid jet head, the ink collection unit being placed on a movement path of the liquid jet head.
For example, a serial printing type ink jet recording apparatus, which is one kind of the liquid jet apparatus, includes a liquid jet head (hereinafter, referred as “ink jet type recording head”), which is mounted on a carriage and scans in a main scanning direction which is a width direction of a target (hereinafter, referred as “recording paper”), and a paper feed unit for conveying recording paper in a secondary scanning direction, which is perpendicular to the main scanning direction of the recording head. Liquid (hereinafter, referred as “ink droplets”) are jetted from the recording head according to print data to thereby perform printing on the recording paper.
Such an ink jet type recording head is adapted to perform printing by jetting ink, which is pressurized in a pressure generating chamber, onto printing paper from nozzle orifices as ink droplets, and thus has a problem that a printing failure occurs owing to increase in ink viscosity and solidification of ink, which are caused by evaporation of ink solvent from the nozzle orifices, and to adhesion of dust to and entrainment of bubbles into ink. Thus, such a type of a recording apparatus includes a capping unit for sealing the nozzle orifices of the recording head during non-printing time, and also has a wiping member for wiping and cleaning a nozzle formation face as occasion arises.
The capping unit has not only the function of serving as a cover for preventing ink in the nozzle orifices of the recording head from being dried during printing is stopped, but also the function of receiving, when clogging of the nozzle orifices occurs, a negative pressure from a suction pump and then sucking and discharging ink from the nozzle orifices to thereby eliminate problems in that clogging of the nozzle orifices is caused owing to the solidification of ink, and that an ink jet failure is caused by entrainment of bubbles into ink passage.
A process of forcibly sucking and discharging ink so as to eliminate the problems of the clogging of the recording head and the state, in which the entrainment of the bubbles into the ink passage is caused, is referred to as a cleaning operation. This operation is performed, for instance, in the cases that printing is resumed after the long stop of the recording apparatus, and that when a user is aware of the deterioration in picture quality, the user operates, for example, a cleaning switch. Further, upon completion of sucking and discharging ink from the recording head, an operation of wiping the nozzle formation face of the recording head with the wiping member constituted by an elastic plate, such as a rubber plate, is performed.
The recording apparatus has the function of jetting ink droplets by applying a drive signal, which is irrelevant to printing, to the recording head. This is referred to as a flushing operation, and performed every predetermined cycle for the purpose of recovering an irregular meniscus caused in the vicinity of each of the nozzle orifices of the head and preventing an occurrence of clogging due to increase in viscosity of ink in a nozzle orifice, at which there are few opportunities to jet ink droplets during printing, by using the wiping member to thereby perform a wiping operation.
FIG. 6
shows an example of a conventional ink jet type recording apparatus configured so that during a flushing operation, ink droplets are jetted toward a flushing region formed on a movement path of the recording head. In
FIG. 6
, reference numeral
1
designates a carriage. This carriage
1
is configured in such a way as to perform reciprocating motions in an axial direction through a timing belt driven by a carriage motor (not shown) by being guided by a guide shaft
4
supported by a left-hand side frame
2
and a right-hand side frame
3
.
An ink jet type recording head
5
is mounted on the carriage
1
in such a manner as to be directed downwardly. A black ink cartridge
6
and a color ink cartridge
7
, which are used for supplying ink to the recording head
5
, are detachably mounted on an upper part thereof. A paper feed member
8
is disposed under the recording head
5
correspondingly to the main scanning direction, and configured so that sheets of recording paper
9
put on this paper feed member
8
can be sequentially transported by a paper feed unit (not shown) in a secondary scanning direction of the recording head
5
, which is perpendicular to the main scanning direction thereof.
In the figure, reference numeral
10
denotes a capping unit placed on a non-printing region (including a home position), and configured so that when the recording head
5
moves to a place just thereabove, the capping unit
10
can upwardly move and seal the nozzle formation face of the recording head
5
. Further, a suction pump
11
for giving a negative pressure to the internal space of the capping unit
10
is placed in close vicinity to the capping unit
10
.
The capping unit
10
has not only the function of serving as a cover, which prevents ink in the nozzle orifices of the recording head
5
from being dried during printing is stopped, as above described, but also the function of serving as a cleaning unit that causes a negative pressure from the suction pump
11
to act upon the recording head
5
thereby to suck and discharge ink therefrom. A wiping member
12
constituted by an elastic plate, such as a rubber plate, is disposed in a printing region adjacent to the capping unit
10
, and configured so that when the carriage
1
performs reciprocating motions between the home position and the capping unit
10
, a wiping operation of wiping the nozzle formation face of the recording head
5
.
On the other hand, a flushing region
13
is formed in the proximity of the other end opposed to the capping unit
10
through a central printing region. This flushing region
13
is constituted by an opening hole formed in such a way as to penetrate the paper feed member
8
. A part of a waste liquid absorber
14
for absorbing and holding ink discharged from the capping unit
10
through the suction pump
11
is disposed on the internal bottom part of the opening hole constituting the flushing region
13
.
Meanwhile, the aforementioned recording apparatus is configured so that flushing is periodically performed in order to prevent an occurrence of a jet failure due to increase in viscosity of ink in a disused nozzle. Especially, in the latest model of such a recording apparatus, tens of flushing shots are performed at each nozzle every several seconds on average. This flushing operation is performed in order to prevent an occurrence of color mixture after the cleaning operation, or at the time of commencing printing, or during printing, so that several to tens of thousands of shots may be periodically jetted from each nozzle.
In the case that an opening hole is formed in the paper feed member
8
as the flushing region
13
, as illustrated in
FIG. 6
, the distance from the nozzle formation face of the recording head
5
to the waste liquid absorbing member
14
is several tens of millimeters. Therefore, a flying distance of an ink droplet inevitably increases. Thus, apart of ink droplets jetted from the nozzle orifice of the recording head become mist (that is, atomized ink) owing to air resistance before reaching the absorbing member
14
. The mist floats, as indicated by arrows. Consequently, this causes a problem in that the inside and outside of the apparatus including recording paper are contaminated.
The ink droplets jetted from the nozzl
Hsieh Shih-Wen
Seiko Epson Corporation
Sughrue & Mion, PLLC
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