Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-03-31
2002-01-22
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C015S247000, C015S246000
Reexamination Certificate
active
06340219
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ink jet recording apparatus comprising a head maintenance unit for maintaining the jetting characteristic of a recording head.
An ink jet recording apparatus comprises: a recording head mounted on a carriage reciprocating in a main scanning direction; and recording medium feeder for feeding a recording medium such as a recording sheet intermittently a predetermined amount in a subscanning direction at one time for jetting ink drops from the recording head to the opposed recording medium for recording while moving the recording head in the main scanning direction.
A monochrome ink jet recording apparatus normally is equipped with one recording head. A full-color ink jet recording apparatus is equipped with a black ink recording head for jetting black ink and color recording heads for jetting color inks of yellow, cyan, magenta, etc. Such a configuration is disclosed in Japanese Patent Publication No. 7-132615A, for example.
The principle of jetting ink from each recording head of the ink jet recording apparatus is as follows: As well known, ink is pressurized by a predetermined pressure in a pressure generating chamber and based on the pressure, ink is jetted as an ink drop of controlled size to the recording medium from each nozzle orifice in a nozzle formation face. Therefore, the ink jetting characteristic from each nozzle orifice of the recording head needs to be maintained constant and if the ink jetting characteristic varies, degradation of the record quality results.
The ink jetting characteristic of the recording head varies because of a rise in viscosity caused by evaporation and drying of ink in the nozzle orifices, ink hardening, clogging, deposition of dust, mixing of air bubbles, etc. Thus, the ink jet recording apparatus is provided with a head maintenance unit for excluding the variation causes of the ink jetting characteristic to maintain the ink jetting characteristic of the recording head constant for maintaining the jetting characteristic of the recording head.
First, the head maintenance unit comprises a capping unit. At the non-recording time, the capping unit seals the nozzle formation face for isolating the nozzle orifices from the outside, thereby suppressing drying of ink and arise in ink viscosity.
If the capping unit seals the nozzle formation face, clogging the nozzle orifices, mixing air bubbles into an ink flow passage, etc., cannot completely be prevented. Then; second the head maintenance unit comprises a suction pump capable of forcibly sucking and discharging ink from the nozzle orifices to remove clogging of the nozzle orifice and the mixed air bubbles. With the suction pump, negative pressure is made to act on the nozzle orifices in a state in which the capping unit seals the nozzle formation face, and ink is forcibly sucked and discharged from the nozzle orifices for removing the clogging, the mixed air bubbles, etc. Normally, the forcible ink sucking and discharging processing with the suction pump is executed when the record operation is restarted after the recorder halts for a long time or the user, who recognizes degradation of the record image quality, operates a dedicated switch on an operation panel.
If the forcible ink sucking and discharging processing with the suction pump is executed as described above, ink may be scattered and deposited on the nozzle formation face of the recording head and a meniscus of ink in each nozzle orifice is disordered. A foreign substance easily adheres to the nozzle orifices of the recording head over time. Then, third the head maintenance unit comprises a wiper for wiping the nozzle formation face as required.
The wiper has a plate-like wiping member made of a composite material comprising a wiping material made of an elastic plate of rubber, etc., on one side and a rubbing member having the same shape as the wiping material, made of felt, etc., on an opposite side and a holder for pinching and supporting the base end side of the wiping member. While the margin of the tip side of the wiping member is pressed elastically against the nozzle formation face, the wiping member is relatively reciprocated for cleaning the nozzle formation face. For example, the wiping material is pressed against the nozzle formation face at the forth or back motion time, and the rubbing material is pressed against the nozzle formation face at the back or forth motion time, thereby cleaning the nozzle formation face.
The cleaning operation with the wiping material of the wiping member is called “wiping operation.” The “wiping operation” takes an important role of uniforming, namely, stabilizing a meniscus of ink in each nozzle orifice in addition to wiping ink deposited on the nozzle formation face. Thus, the force of elastically pressing the margin of the wiping material against the nozzle formation face must be set to a soft and appropriate strength to such an extent that the meniscus can be stabilized reliably; this is a first technical demand.
The cleaning operation with the rubbing member of the wiper is called “rubbing operation.” The “rubbing operation” has a role of scraping off a foreign substance fixedly secured to the nozzle formation face. Thus, the force of pressing the margin of the rubbing material against the nozzle formation face must be set large to such an extent that the foreign substance fixedly secured to the nozzle formation face can be scraped off; this is a second technical demand.
However, hitherto, to meet the first and second technical demands for the wiper, a wiping member easily bent and a rubbing member harder to bend than the wiping member have been used only in combination. Thus, naturally there is a limit and both the technical demands are not easy to meet sufficiently.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an ink jet recording apparatus which has a head maintenance unit for maintaining the jetting characteristic of a recording head and can easily and sufficiently meet the first and second technical demands for the wiping member of the wiper, one of the head maintenance units.
To the end, according to a first aspect of the invention, there is provided an ink jet recording apparatus comprising:
a recording head; and
a wiping unit for wiping a nozzle formation face of the recording head including:
a slider reciprocally moving in a direction parallel with the nozzle formation face;
a wiper supported by the slider, one end of which is pressed against the nozzle formation face as a wiping operation when the slider moves in a first direction, while as a rubbing operation when the slider moves in a second direction opposed to the first direction;
a supporter for rotatably supporting the other end of the wiper on the slider;
a spring for urging the wiper toward the nozzle formation face while keeping an attitude of the wiper directed by a reaction force generated when the wiping operation is executed; and a rotation limitter for restricting the rotation of the wiper such that the wiper is rigidly supported by the slider when the rubbing operation is executed.
According to the configuration, during the wiping operation, the wiper is pressed against the nozzle formation face of the recording head using the elastic forces of both the wiper itself and the spring, so that the first technical demand that the wiper must be pressed against the nozzle formation face with a soft and appropriate strength to such an extent that a meniscus of ink in the nozzle orifice can be stabilized reliably as compared with the structure in the related art wherein the wiper is pressed by the elastic force of only the wiper itself can be met easily and sufficiently.
During the rubbing operation, the rotation limitter restricts rotation of the wiper for placing the wiper in a rigid support state, so that the wiper is strongly pressed against the nozzle formation face and thus the foreign substances fixedly secured to the nozzle formation face can be scraped off reliably; the second technical demand can be met easily and sufficient
Aruga Yoshiharu
Kumagai Toshio
Barlow John
Seiko Epson Corporation
Sughrue & Mion, PLLC
Tran Ly T
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