Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-09-18
2004-03-16
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S085000
Reexamination Certificate
active
06705712
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an ink jet recording device which includes a recording head being movable in the widthwise direction of a recording sheet of paper, and ejects from the recording head ink droplets toward a recording sheet in accordance with print data, thereby printing an image on the recording sheet. More specifically, the invention relates to an ink cartridge to which a cleaning process is effectively applicable for sucking ink from the nozzle apertures of the recording head to restore the printing function of the recording head, and an ink jet recording device using the ink cartridge, and a method for controlling the cleaning of the recording head of the ink jet recording device.
BACKGROUND ART
The ink jet recording device includes an ink jet recording head for receiving ink from an ink cartridge and a sheet feeder for moving a recording sheet relative to the recording head. The recording head mounted on a carriage ejects ink droplets onto the recording sheet while being moved in the widthwise direction of the recording sheet, thereby executing recording.
The recording head which is able to eject black ink and color ink of yellow, cyan and magenta is mounted on the carriage, so that not only text printing with black ink but also full color printing by varying a ejecting ratio of color ink can be executed.
The recording head mentioned above suffers from a problem in that print failure may occur due to increased ink viscosity or solidification of ink, which will be caused, for instance, due to evaporation of solvent from nozzle apertures, adhered dust, entry of air bubbles, etc. because the recording head is designed to eject ink, pressurized in a pressure generating chamber, as ink droplets from the nozzles toward a recording sheet.
To cope with this, the following function is incorporated. When the nozzle apertures are clogged or an ink cartridge is exchanged, a nozzle formed surface of the recording head is sealed with a capping system. In this state, a suction pump applies a negative pressure to the nozzle formed surface to suck ink from the nozzle apertures. In this way, the clogging in the nozzle apertures or the like due to ink solidification, and ink ejection failure due to the entry of air bubbles into the ink passage are eliminated. This operation is called a cleaning operation.
In performing the cleaning operation, it is effective to generate a fastest possible ink flow within an ink passage, for example, the ink passage ranging from the ink cartridge to the nozzle apertures of the recording head. This also makes it possible to discharge the air bubbles, present in the passage, together with the ink whose viscosity is increased.
In this approach, however, to increase a velocity of the ink in the cleaning operation, the performance of the suction pump must be increased to produce a large negative pressure. This requires the size increase of the pump and the motor for driving the pump, resulting in inevitable increase in cost and size of the entire device.
Further, since a large amount of ink is ejected from the recording head, the lifetime of the ink cartridge is reduced, and the user is compelled to accept an increase of running cost.
To cope with the problem, there is proposed a recording device in JP-A-4-1055, for example. In the proposal, a valve unit operable for opening and closing is located in an ink passage ranging from the ink cartridge to the recording head. In the cleaning operation, the valve unit is put in a closing state, and a negative pressure is applied to the capping system. When a negative pressure increases, the valve unit is opened so that a velocity of the ink flowing within the recording head is instantaneously increased.
In the proposal, there is no need of providing a suction pump specially designed to produce a large negative pressure. Therefore, it is estimated that the ink solidified or increased in its viscosity at positions near the nozzles of the recording head will readily be discharged. Further, the ink is instantaneously sucked from the nozzles. Therefore, it is estimated that the discharging of a relatively small amount of ink will provide a satisfactory cleaning operation.
Many ink jet recording devices as mentioned above are each constructed such that ink cartridges containing black and color ink are detachably attached to the carriage on which the recording head is mounted, from its top. Each ink cartridge is constructed to supply ink to the recording head via a hollow ink supplying needle (referred to frequently as a hollow needle) as an ink introducing portion which is mounted faceup on the carriage.
In the ink jet recording device, the ink passages within the recording head are very fine in structure. Accordingly, the ink to be supplied from the ink cartridge to the recording head must be in such a clean state that foreign matter, e.g., dust, is completely removed from the ink.
If such foreign material as dust is contained in the ink, the clogging problem will arise: the ink passage of the recording head, in particular an extremely thin ink supply port, the nozzle apertures, and the like are clogged with the foreign material. Where the clogging problem arises, the recording head cannot perform a proper ink ejecting operation. In most cases, it is impossible to restore the function of the recording head.
To solve the clogging problem, it is a common practice that a filter for filtering out foreign materials is located at a position upstream of the recording head in the ink passage, e.g., between the hollow needle and the head case for supporting the needle, thereby preventing foreign matters from flowing to the head side.
FIG. 1
shows a structure showing its state. In the figure, reference numeral
21
indicates a hollow needle, which is mounted on the ink cartridge. The hollow needle
21
leads the ink from the ink cartridge storing the ink therein to the recording head. The top end of the hollow needle
21
is sharpened, and its tip is opened to form ink introducing holes
21
a
. The hollow needle
21
, which is closely joined to a packing member being made of rubber and mounted on the ink cartridge, introduces the ink from the ink cartridge via the ink introducing holes
21
a
. The base end of the hollow needle
21
radially and downwardly expands, and hence a tapered space
21
b
is formed within the base end.
Another space
20
f
is formed also in a case
20
a
of the recording head on which the base of the hollow needle
21
is mounted. A filter member
22
is placed between the base of the hollow needle
21
and the head case
20
a
that enclose those spaces. An effective area of the filter member
22
is increased by forming the spaces above and below the filter member
22
, thereby suppressing a dynamic pressure (pressure loss) of the filter member.
As seen also from the structure shown in
FIG. 1
, in a state that the ink passage formed in the hollow needle
21
and the filter member
22
are arranged in the gravity direction, an air bubble A, as shown in FIG.
1
(A), is left within the tapered space
21
b
which is located within the hollow needle
21
and above the filter member
22
, when the ink passage within the recording head is first filled up with ink. Also when the ink cartridge is exchanged with another one, an air bubble A enters the space
21
b
above the filter member
22
and stays within the space
21
b.
In a case where the printing process is executed in a state that the air bubble A stays and a state of the printing is in a full duty (all the nozzle apertures simultaneously eject droplets at the highest frequency), the air bubble A staying upstream of the filter member
22
slowly moves to a position near the filter member
22
, together with the ink flow, and it is put in a state that it balances with the velocity of ink flow.
When the full duty printing further continues, the air bubble A comes in contact with the filter member, a slight part of the air bubble passes through the filter member
22
and reaches the ink passage within the recording head, and it sta
Hara Kazuhiko
Hayakawa Hitoshi
Naka Takahiro
Sema Kiyotaka
Shinada Satoshi
Seiko Epson Corporation
Sughrue & Mion, PLLC
Vo Anh T. N.
LandOfFree
Ink cartridge, ink jet recording device using the same, and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink cartridge, ink jet recording device using the same, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink cartridge, ink jet recording device using the same, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3266020