Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-09-07
2002-11-19
Barlow, John (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S030000
Reexamination Certificate
active
06481826
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ink jet recording apparatus comprising a recording head for jetting ink drops from nozzle orifices based on print data, thereby printing on recording paper. Particularly, this invention to an ink jet recording apparatus that can prevent a print failure from occurring by suppressing volatilization of an ink solvent from the recording head during a suspend mode of the recording apparatus in order to avoid the influence of bubbles that can occur due to the surface tension of the ink solvent.
The ink jet recording apparatus is used for various types of print including color print in these days because print noise is comparatively small and moreover small dots can be formed at a high density.
The ink jet recording apparatus comprises an ink jet recording head for receiving ink supplied from an ink cartridge and a paper feeder for moving recording paper relatively to the recording head and jets ink drops onto recording paper for recording while moving the recording head on a carriage in the width direction of the recording paper.
The recording head capable of jetting black ink and color inks of yellow, cyan, and magenta is mounted on the carriage, enabling not only text print in black ink, but also full color print by changing the content percentage of the respective color inks.
Since ink pressurized in pressure generation chambers is jetted to recording paper as ink drops from nozzle orifices for printing, the recording head installed in the recording apparatus involves the problem of causing a print failure to occur because of a rise in the ink viscosity or hardening of ink caused by evaporation of an ink solvent from the nozzle orifices, deposition of dust, mixing of bubbles into an ink flow passage, or the like.
Thus, this kind of ink jet recording apparatus comprises a capping unit for sealing the nozzle formation face of the recording head in non-print mode (suspend mode) and a wiping member for wiping out and cleaning the nozzle formation face as required.
The capping unit serves as a lid for preventing ink in the nozzle orifices from being dried in the suspend mode of print; it: can suppress clogging caused by drying ink in the nozzle orifices of the recording head for providing the reliability of the print operation at the restart time of print.
Further, the capping unit also serves as a cleaner unit for sealing the nozzle formation face and sucking and discharging ink from the nozzle orifices by negative pressure generated by a suction pump, thereby resolving an ink jet failure caused by clogging caused by ink hardening in the nozzle orifices or mixing of bubbles into the ink flow passage.
To make the capping unit function effectively as a lid for preventing ink in the nozzle orifices from being dried during quiescent operation of print as described above, the related recording apparatus adopts a control sequence of jetting a predetermined amount of ink into the capping unit from the recording head just before the capping operation.
On the other hand, the capping unit stores an ink absorption material of a porous foam formed like a sheet on the inner bottom of the capping unit formed like a rectangle and ink is held by the ink absorption material, thereby maintaining the internal space of the capping unit in a wet state with the nozzle formation face sealed.
By the way, in addition to a water content, polyhydric alcohol such as glycerine or diethylene glycol as a humectant is mixed in print ink for maintaining the inside of the capping unit in a wet state.
The polyhydric alcohol has a nature of absorbing (retaining) water from the air and is used as an ink solvent to suppress an increase in viscosity of ink and hardening of ink for preventing clogging mainly in the minute nozzle orifices of the recording head.
However, in a state in which the ink absorption material of a porous foam is placed in the capping unit as described above, the water content is evaporated from the ink absorption material with the passage of time, but the above-mentioned humectant is left in the ink absorption material and the composition percentage rises gradually with the passage of the use time of the recording apparatus.
Therefore, if the humectant is left in the ink absorption material in a high composition percentage, it absorbs the water content in the internal space in the capped state of the recording head, developing a problem of drying ink in the nozzle orifices of the recording head.
Focusing attention on the adverse effect of the humectant contained in print ink and from the viewpoint, it is a first object of the invention to provide a structure wherein the ink absorption material placed on the inner bottom of the capping unit is removed and to suck and discharge ink from the recording head, the ink can be discharged promptly so that it is not left in the capping unit, and provide an ink jet recording apparatus comprising a capping unit in which a high-density humectant is not accumulated and moreover an adequately wet state can be maintained by the water content contained in the ink and make it possible to ensure reliability of print of a recording head.
On the other hand, in the structure wherein the ink absorption material placed on the inner bottom of the capping unit is removed, as described above, if sealing of the nozzle formation face of the recording head with the capping unit is released, a large bubble shaped like a so-called soup bubble appears by the surface tension of an ink solvent between the seal face of the capping unit and the nozzle formation face of the recording head; this is a problem.
It is considered that a bubble occurs because a porous member as an ink absorption member does not exist and the inside. of the capping unit is formed as comparatively smooth faces.
FIGS. 33
to
36
schematically show the situation in order.
FIG. 33
shows a state in which the nozzle formation face of the recording head is sealed with the capping unit.
FIGS. 34
to
36
show with the upper half part shown in
FIG. 33
not shown how the above-mentioned large bubble shaped like a so-called soup bubble is left in the capping unit as sealing of the nozzle formation face of the recording head with the capping unit is released.
Identical components shown in
FIGS. 33
to
36
are denoted by the same reference numerals.
First, as shown in
FIG. 33
, a nozzle plate
12
a
forming a nozzle formation face
12
a
of a recording head
12
is placed on the bottom face of a head case
12
b
forming a part of the recording head
12
and is formed with a plurality of nozzle orifices
12
c
. Actuators
12
d
, for example, implemented as piezoelectric vibrators are placed in the head case
12
b
in a one-to-one correspondence with the nozzle orifices
12
c.
Communication channels
12
e
are formed in the head case
12
b
from the nozzle orifices
12
c
and the actuators
12
d
to the top thereof.
Four hollow ink introduction needles
41
are placed upright on the top of the head case
12
b
and the communication channels
12
e
formed in the head case
12
b
are made to communicate with hollow passages of the ink introduction needles
41
.
An ink introduction hole (not shown) is made in the vicinity of the crest of each ink introduction needle
41
and ink from an ink cartridge is introduced through each ink introduction hole into the corresponding ink introduction needle
41
and is supplied via the communication flow passage
12
e
to the actuator
12
d
of the recording head
12
.
The ink introduction needle
41
at the left end shown in
FIG. 33
is provided for receiving black ink and a black ink cartridge
7
is attached toward the ink introduction needle
41
at the left end from the top.
A color ink cartridge
8
stores color inks of cyan, magenta, and yellow separately in order from left to right in FIG.
33
and is also attached toward the three remaining ink introduction needles
41
from the top as shown in FIG.
33
.
On the other hand, the capping unit
9
is made up of a holder
21
and a cap member
22
of a rubber material,
Hara Kazuhiko
Hayakawa Hitoshi
Hsieh Shih-wen
Seiko Epson Corporation
Sughrue & Mion, PLLC
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