Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2003-03-20
2004-12-07
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S030000
Reexamination Certificate
active
06827422
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid suction apparatus for sucking a liquid from a plurality of nozzle openings of a liquid ejecting head and a liquid ejecting apparatus having this liquid suction apparatus.
2. Description of the Related Art
As a typical example of a conventional liquid ejecting apparatus, there is an ink jet printer having an ink jet printing head for image recording. As other liquid ejecting apparatuses, for example, an apparatus having a color material jet head used for manufacturing a color filter of a liquid crystal display, an apparatus having an electrode material (conductive paste) jet head used for forming electrodes of an organic EL display or an FED (Face Emission Display), an apparatus having a biological organic substance jet head used for manufacturing biological chips, and an apparatus having a sample jet head as a precise pipette may be cited.
An ink jet printer as a typical example of a liquid jet recorder makes comparatively small noise during printing and moreover can form small dots in high density, so that it has been used recently in various types of printing including color printing.
Such an ink jet printer generally has a printing head (liquid ejecting head) which is loaded on a carriage and moves back and forth in the width direction (head scanning direction) of a recording medium such as recording paper and a feed means for moving the recording medium in the direction (medium feed direction) perpendicular to the head scanning direction.
In the ink jet printer, printing is executed by ejecting ink drops (liquid drops) from the printing head to the recording medium in correspondence with print data. And, the printing head loaded on the carriage is structured so as to eject various colors of ink, for example, black, yellow, cyan, and magenta, thus not only text printing by black ink but also full color printing can be executed by changing the ejection rate of each ink.
Since the aforementioned printing head prints by ejecting ink pressurized in a pressure chamber as ink drops from the nozzle opening toward the recording medium, a problem arises that for example, by increasing of the ink viscosity caused by evaporation of a solvent from the nozzle opening, setting of ink, attachment of dust, moreover inclusion of air bubbles, defective printing is caused.
Therefore, when the nozzle opening of the printing head is clogged or when an ink cartridge is exchanged, the nozzle opening forming face of the printing head is sealed by the cap member, and ink is sucked and ejected from the nozzle opening by negative pressure from a suction pump (tube pump), thus a liquid suction apparatus for executing a cleaning operation for preventing defective ink ejection due to clogging by ink setting in the nozzle opening or inclusion of air bubbles into the ink feed path is generally included in the ink jet printer.
A conventional liquid suction apparatus, for example, described in Japanese Patent Laid-Open Publication No. 2001-096758, has a suction pump and a cap member connected to the suction pump for sealing a nozzle forming face of a printing head. And, in the conventional liquid suction apparatus, in a state that the nozzle forming face is sealed by the cap member, a liquid (air, ink) is ejected from the inside of the cap member by the suction pump. By doing this, due to a negative pressure generated inside the cap member, ink in the printing head and on the upstream side thereof is sucked and the printing head is internally cleaned.
By this cleaning operation (ink suction operation), filling the printing head with ink, suction and ejection of deteriorated ink from the printing head, and ejection of air bubbles generated in the ink in the printing head are carried out, and the ink filling state in the printing head is kept normal, and good printing is made possible.
Further, the suction pump is operated by an instruction from the controller in the printer or the host computer, thus the negative pressure generation time and negative pressure generation amount can be controlled.
FIG. 18
shows a state that the nozzle forming face of the printing head of the conventional ink jet printer is sealed by the cap member and a cap member
60
is in contact with a nozzle forming face
23
of a printing head
9
in which a plurality of nozzle openings
22
are formed. Inside the cap member
60
, a filter member
62
is arranged in close contact with the bottom of the cap member
60
. A liquid (air, ink) in the cap member
60
is sucked and ejected by a pump
61
.
In the conventional ink jet printer shown in
FIG. 18
, not only in a case of execution of cleaning but also in a case that the ink jet printer is in a non-printing state, the nozzle forming face
23
of the printing head
9
is sealed by the cap member
60
. The filter member
62
installed in the cap member
60
is in a wet state due to ink ejected from the printing head
9
at the time of cleaning or flashing. Therefore, when the nozzle forming face
23
of the printing head
9
is sealed by the cap member
60
, the humidity in the cap member
60
is increased, and the moisture retention effect in the neighborhood of the nozzle openings
22
is increased, thus the setting of ink in the nozzle openings
22
can be suppressed.
In the conventional liquid suction apparatus aforementioned, as shown in
FIG. 18
, the filter member
62
is arranged in close contact with the inner bottom of the cap member
60
. Therefore, in the entire filter member
62
, in the neighborhood of an ejection port
63
formed in the bottom of the cap member
60
, comparatively high suction force is reserved for a liquid (air, ink), while in the area away from the ejection port
63
, no sufficient suction force can be obtained. Namely, the suction force for ink flowing down on the top of the filter member
62
differs depending on the position in the entire filter member
62
and ink concentratedly passes through the part in the neighborhood of the ejection port
63
. In this case, the filter function of the entire filter member
62
cannot be used effectively, and the filter member
62
is locally deteriorated rapidly in the neighborhood of the ejection port
63
as well, thus a problem arises that the life span of the filter member
62
is shortened.
Furthermore, in the conventional liquid suction apparatus, after ending of filling of ink after exchanging the ink cartridge or even after the nozzle opening is recovered from clogging, as long as the negative pressure generating unit is operated, the ink suction flow rate is not suppressed and ink is continuously sucked from the nozzle opening.
In cleaning of a printing head having a plurality of nozzle openings, particularly a plurality of nozzle openings for different ink kinds, due to the structure of ink flow path or the composition factor of ink, the negative pressure and ink suction rate necessary for cleaning may be different for each nozzle opening or nozzle opening group. Therefore, in the conventional liquid suction apparatus, there is a problem imposed that depending on the difference in the required time for recovery of clogging or filling of ink for each nozzle opening or each nozzle opening group, an amount of ink larger than necessary is sucked for the easily recoverable nozzle opening or nozzle opening group and although there is a non-recovered or non-filled nozzle, the suction operation is ended at the point of time when the total suction amount reaches a set value. Further, there is another problem imposed that due to ink suction from a nozzle opening recovered from clogging, the negative pressure in the cap member is reduced, thus the effective transfer of negative pressure to a nozzle opening which is not recovered from clogging yet is prevented.
Further, the operation of the negative pressure generating unit is controlled on the basis of information such as the continuous non-printing time of the printer. However, the ink clogging state is affected by various factors including the temperature and humid
Hsieh Shih-Wen
Seiko Epson Corporation
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