Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-09-01
2002-03-26
Yockey, David F. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06361159
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a print head device for use in combination with an ink cartridge mounted therein, and an ink jet printer incorporating the print head device, and the ink cartridge.
2. Prior Art
Ink jet printers have the inconvenience that an ink meniscus at nozzle tips of a print head thereof is destroyed even by a slight shock or impact (for instance, one caused by a fall of the ink jet printer from a position one or two centimeters high). The destruction of meniscus causes “thinned nozzles” which means a faulty ink-discharging action of nozzles or “angled jets” which means undesirably angled jets of ink drops, resulting in a faulty printing operation. Especially, in the case of ink jet printers of a type which has ink delivery ports of an ink cartridge connected to connecting caps of a head unit thereof in surface-to-surface contact, more particularly, a type which has seal packings interposed between the connecting caps and the ink delivery ports, respectively, the seal packings are contracted and expanded by a shock to cause pressure fluctuations within closed spaces inside the seal packings. The pressure fluctuations can propagate to ink, resulting in destruction of the ink meniscus at nozzle tips.
Users of ink jet printers which are generally commercially available are advised to carry out cleaning of a print head of their printer by manually instructing the cleaning operation thereto even when it is simply moved e.g. for a change of position where it is placed, since there is a fear that the ink meniscus at nozzle tips thereof is destroyed.
Therefore, in the case of ink jet printers of a portable type or ones which have to be frequently carried from one place to another, automatic or manual cleaning of a print head thereof is very frequently required. Such ink jet printers wastefully consume a large amount of ink, which degrades commercial value thereof.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a print head device, an ink jet printer incorporating the print head device, and an ink cartridge, which are capable of preventing an ink meniscus at nozzle tips of the print head device from being destroyed by a shock or impact applied to the ink jet printer.
To attain the above object, according to a first aspect of the invention, there is provided a print head device in which an ink cartridge storing ink therein and having an ink delivery port for delivering the ink therefrom is removably mounted for use therewith, the print head device comprising:
a seal packing arranged such that the seal packing is brought into airtight contact with the ink cartridge when the ink cartridge is mounted in the print head device, such that the seal packing encloses the ink delivery port, thereby defining an inner space within the seal packing, for airtight communication between the ink delivery port and the inner space; and
pressure fluctuation-accommodating means for accommodating pressure fluctuations within the ink delivery port and the inner space in communication with each other.
According to this print head device, when the print head device having the ink cartridge mounted therein receives a shock or impact, inertia of the ink cartridge causes expansion and contraction or compression of the seal packing, whereby the volume of the inner space inside the seal packing is fluctuated, causing pressure fluctuations within the ink delivery port and the inner space in communication with each other. However, the pressure fluctuations are accommodated by the pressure fluctuation-accommodating means. This prevents the pressure fluctuations from propagating to ink, and thereby inhibits pulsation of the ink. Thus, the print head device according to the first aspect of the invention can suitably accommodate pressure fluctuations within the ink delivery port and the inner space in communication with each other, thereby effectively preventing destruction of an ink meniscus at tips of ink nozzles. This enhances shock resistance of the print head device.
Preferably, the pressure fluctuation-accommodating means comprises an air communication passage, the air communication passage having one end open to the inner space within the seal packing and another end open to the atmosphere.
According to this preferred embodiment, the pressure fluctuations within the ink delivery port and the inner space in communication with each other are accommodated by air flows in the air communication passage.
More preferably, the print head device includes a cartridge-receiving portion for receiving the ink cartridge thereat, and the air communication passage comprises a groove formed in a surface of the cartridge-receiving portion, and a film hermetically covering the groove except for opposite ends thereof.
According to this preferred embodiment, the air communication passages can be easily formed by forming a groove in advance in the surface of the cartridge-receiving portion, and affixing a film over the groove by thermocompression bonding. Further, the air communication passages formed do not produce unacceptably concave or convex portions on the surface of the cartridge-receiving portion.
Preferably, the air communication passage extends in a meandering manner.
According to this preferred embodiment, it is possible to minimize evaporation of a solvent, such as water or the like, contained in ink.
More preferably, a drop of non-volatile sealing liquid is sealingly held in the air communication passage, for motion in accordance with air flows in the air communication passage.
According to this preferred embodiment, it is possible to prevent evaporation of a solvent contained in ink. The provision of non-volatile sealing liquid in the air communication passage is useful especially when an ink diluted by a highly volatile solvent is employed.
Alternatively, the pressure fluctuation-accommodating means comprises a pouch formed of a flexible membrane arranged in an outer space outside the seal packing, the outer space being in communication with the atmosphere, and a communication passage permitting airtight communication between the pouch and the inner space.
According to this preferred embodiment, when the print head device having the ink cartridge mounted therein receives a shock to cause expansion and contraction or compression of the seal packing, pressure in the inner space inside the seal packing is fluctuated. However, the pressure fluctuations are accommodated by air flows to and from the pouch which is formed of a flexible membrane and in communication with the inner space via the communication passage. This prevents fluctuations in the volume of the inner space inside the seal packing from developing a large pulsation of ink supplied from the ink delivery port to the ink nozzles of the print head device. Further, it is possible to positively prevent evaporation of a solvent, such as water or the like, contained in ink.
Preferably, the communication passage extends through the seal packing.
Alternatively, the ink cartridge further includes a casing, an absorbent filled in the casing, for absorbing the ink for storage, and a filter arranged between the absorbent and the ink delivery port;
the print head device further comprising a connecting portion for being inserted into the ink delivery port when the ink cartridge is mounted in the print head device such that the connecting portion pushes the filter inward, for permitting the ink delivered from the ink delivery port to flow therethrough;
the seal packing comprising a wall forming a generally hollow cylindrical shape and constructed such that the wall is bent inward when an external force is applied to the seal packing in a compressing direction, whereby the seal packing doubles as the pressure fluctuation-accommodating means.
According to this preferred embodiment, when the print head device having the ink cartridge mounted therein receives a shock to cause relative motion of the ink cartridge toward the print head device, the connecting portion of the print head device pus
Hogan & Hartson L.L.P.
Seiko Epson Corporation
Yockey David F.
LandOfFree
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