Patent Grant
10046570
The present invention relates to a filter device for filtering ink for delivery to at least one drop forming unit of a print-head in a printing apparatus and to an ink supply system including such a filter device. The invention also relates to a printing apparatus that includes such an ink filter device and/or ink supply system.
In printing apparatuses known to the applicant, especially in printing apparatuses that employ ink of the melt type (i.e. ink which is liquid at an elevated temperature and is generated by melting solid ink elements, such as so-called toner pearls or ink pearls), solid ink pearls are melted by a melting device and fed through a filter via a collection chamber into a reservoir, from which a drop forming unit of a print-head is supplied with ink. The filter is employed to remove particles such as non-melted ink or contaminants from the liquid ink before the ink reaches the reservoir to avoid jetting instability or blockages in the drop forming unit, especially in the drop forming nozzles.
In conventional printing apparatus employing a melt-type of ink, the melting device is located fixed relative to the filter. Accordingly, the ink fed to the filter from the melting device tends to flow via the same path from the collection chamber to the reservoir, which usually is a direct path from the location where the ink enters. This has the disadvantage, however, that ink which accumulates in other areas of the collection chamber tends to remain for longer periods of time and these areas are only poorly supplied with fresh ink. This may create so-called “dead zones” within the chamber in which very little renewal of the ink takes place and the ink becomes prone to degradation. In particular, such dead zones may prevent proper operation of the ink supply system as the older ink may produce a different print quality and may also generate particles through crystallisation. The development of such dead zones can significantly shorten the lifetime of the printing apparatus.
In view of the above, an object of the present invention is to provide a new and improved filter device for filtering ink for delivery to at least one drop forming unit of a print-head in a printing apparatus, and a new and improved ink supply system in a printing apparatus.
In accordance with the present invention, a filter device for filtering ink for delivery to at least one drop forming unit of a print-head in a printing apparatus as recited in claim 1 is provided. The invention also provides an ink supply system as recited in claim 10 and a printing apparatus as recited in claim 12. Advantageous or preferred features of the invention are recited in the dependent claims.
According to one aspect, therefore, the present invention provides a filter device for filtering ink for delivery to at least one drop forming unit of a print-head in a printing apparatus. The filter device comprises an inlet for admission of ink to the filter device; a first filter member adjacent the inlet for filtering the ink as it enters the filter device; a collection chamber for collecting the ink after the ink passes through the first filter member, wherein the collection chamber is arranged below the first filter member, when the filter device is mounted in the printing apparatus; and an outlet for delivering the ink from the collection chamber to a reservoir for supplying the at least one drop forming unit. The collection chamber comprises at least one flow directing member which defines at least one predetermined flow path for flowing at least a part of the ink around the flow directing member to the outlet.
In this way, the present invention provides a filter device for the ink in which freshly melted ink entering the collection chamber necessarily follows or is compelled to follow the predetermined flow path through and/or around the collection chamber towards the outlet. As a result, from the location where the ink passes through the first filter member, the ink is directed along the predetermined flow path towards the outlet through the chamber, especially via a circuitous or indirect flow path. In other words, this filter device is able to inhibit the formation of “dead zones” in the collection chamber in which older ink accumulates and very little renewal the ink takes place. This is achieved by providing a predetermined flow path through or around the collection chamber along which mixing with the older ink may take place. Due to the predetermined flow path, the freshly melted ink should not reach the reservoir via the outlet much earlier than other ink already present in the reservoir. That is, the at least one predetermined flow path is configured to ensure that the ink flows to the reservoir more or less in the order of entry through the inlet. The invention thus contributes to maintaining full functionality of the filter device over its service life. Indeed, the service life of the filter device may be significantly extended.
It will be appreciated that the concept of the filter device according to the present invention is not limited to application in an ink supply system of a printer or to application of a melt-type of ink. Rather, the filtering device may also be employed with any other liquid supply system, and especially with any liquid which is prone to degradation and/or particle formation over time, for instance through crystallization.
In an embodiment, the collection chamber is substantially covered by the first filter member such that the ink passes or seeps downwards (when mounted in an apparatus) through the first filter member into the collection chamber. The at least one flow directing member is configured to direct the ink entering the collection chamber at any location to the outlet along the at least one predetermined flow path. Advantageously, at least some of the ink may thereby travel or flow substantially over a full length of the predetermined flow path. The flow directing element may be configured to guide the ink through areas of the collection chamber which may otherwise be prone to the formation of dead zones, thereby inhibiting their formation.
In an embodiment, the directing member(s) divides the collection chamber into at least one channel. In this way, the at least one channel defines a respective one of the at least one predetermined flow path around the flow directing member through the collection chamber to the outlet. The at least one channel may therefore be realised simply by dividing the collection chamber via the flow directing member into at least one channel in a simple to manufacture and effective manner.
In an embodiment, the at least one flow directing member comprises an elongate projection (or wall) arranged inside the collection chamber and upstanding from a base of the collection chamber. In particular, the elongate projection may be integrally formed with the collection chamber. That is, the flow directing member and the collection chamber can be formed together as a unitary part or component. For example, such a part or component could be fabricated from a polymer material and/or manufactured by means of injection moulding.
In an embodiment, the collection chamber, and especially walls of the collection chamber, may cooperate with the at least one flow directing member to form the at least one channel. In other words, the flow directing member(s) may cooperate with one or more side walls of the collection chamber to define or form the at least one predetermined flow path through and/or around the chamber, and especially through one or more turns or bends of the flow path. For example, an end of the flow directing member within the collection chamber may cooperate with one or more side walls of the chamber to form a turn or bend in the predetermined flow path. Thus, walls of the collection chamber may, at least partially, serve as walls of the at least one channel. Alternatively, the at least one flow directing member could exclusively form the at least one channel.
In an embodiment, the flow directing member is formed by an elongate projection or wall inside the chamber and upstanding from a base of the chamber, and the elongate projection or wall extends substantially parallel to the opposite side walls of the chamber. The opposite side walls may be connected to each other at ends thereof by short side walls and the elongate projection or wall terminates or ends before reaching either or both of the short side walls. In this way, the opposite side walls, the short side wall and the elongate projection may together form a turn or bend in the predetermined flow path. Other kinds and forms of turn or bend are also possible. For example, a turn or bend could be formed by two adjacent angularly arranged walls and a flow directing member positioned in the acute angle thereof. Furthermore, a curved arrangement of walls is possible.
In an embodiment, the flow directing member is connected to a side wall of the collection chamber to form a barrier. That is, the flow directing member may be connected to a side wall of the collection chamber to obstruct a direct flow path from a location of seepage of the ink to the outlet. In this way, the direct path is obstructed and the ink is directed or guided along the predetermined flow path to the outlet, thereby avoiding the formation of dead zones.
In an embodiment, the first filter member is configured to function as a pressure lock. The filter device is thereby configured so that the ink may only exit the collection chamber through the outlet if new ink seeps through the first filter member and enters the collection chamber. In other words, a small amount of ink remains in the filter, closing all pores or holes of the filter device. In this way, a desired under-pressure in the ink supply system downstream of the filter device is maintained. The pressure lock function of the filter element may be based on a capillary effect of the pores or holes of the filter device, which are wetted by the ink. In this way, an integral functionality of the first filter member, combining the function of filtering the ink on one hand, and regulating the pressure downstream of the filter device, may be realised.
In an embodiment, the pressure lock has a breaking pressure in the range of more than 1 mbar. Preferably, the breaking pressure is higher than 5 mbar and more preferably higher than 10 mbar. Such a breaking pressure may be provided by a selecting a size of the pores or holes of the first filter member adapted to the surface tension of the ink. Further, as apparent to those skilled in the art, the size of the pores or holes is selected such that particles that may form an obstruction downstream of the filter device are prevented from passing through the filter device.
According to another aspect, the invention provides an ink supply system for supplying ink to at least one drop forming unit of a print-head in a printing apparatus. The ink supply system comprises an ink melting device for melting solid ink elements, especially toner pearls, to form liquid ink and a filter device according to any one of the embodiments described above for filtering the liquid ink from the melting device. The ink supply system further comprises a reservoir for storing the liquid ink received from the filter device for delivery to the at least one drop forming unit.
As discussed above, the invention is configured to avoid formation of dead zones in the collection chamber of the filter device. As fresh ink from the melting device entering the collection chamber necessarily follows the at least one predetermined flow path, the ink can be guided along a specific, especially circuitous or indirect, path towards the outlet. In this way, full functionality of the filter device and of the ink supply system is maintained over its service life.
To feed a drop forming unit of a print-head of a printing apparatus with melted ink, solid ink elements are melted by the melting device and fed through the filter device into the reservoir, from which the drop forming unit is then supplied. By virtue of the filter device, of course, particles or other contaminants are removed from the liquid ink before the ink reaches the reservoir. In this way, blockage or jet instability in the drop forming unit, and especially in the drop forming nozzles, of the print-head are avoided.
In a preferred embodiment, the ink supply system further comprises a second filter member for filtering the liquid ink flowing from the reservoir for delivery to the at least one drop forming unit. In this way, an additional safety device in form of the second filter member is provided to remove any remaining particles from the ink.
According to a further aspect, the present invention provides a printing apparatus comprising a filter device according to any one of the embodiments described above. Alternatively or in addition, the printing apparatus comprises an ink supply system according to any one of the embodiments described above.
For a more complete understanding of the invention and the advantages thereof, exemplary embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawing figures, in which like reference characters designate like parts and in which:
The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate particular embodiments of the invention and together with the description serve to explain the principles of the invention. Other embodiments of the invention and many of the attendant advantages of the invention will be readily appreciated as they become better understood with reference to the following detailed description.
It will be appreciated that common and/or well understood elements that may be useful or necessary in a commercially feasible embodiment are not necessarily depicted in order to facilitate a more abstracted view of the embodiments. The elements of the drawings are not necessarily illustrated to scale relative to each other. It will further be appreciated that certain actions and/or steps in an embodiment of a method may be described or depicted in a particular order of occurrences while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used in the present specification have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study, except where specific meanings have otherwise been set forth herein.
With reference firstly to
In this particular exemplary embodiment, the collection chamber 4 has a generally rectangular form with four side walls 8-11; namely opposite longer walls 8, 10 and opposite shorter walls 9, 11. In other embodiments, the collection chamber 4 may be formed with any shape suitable for collecting the ink after it has passed through the filter member 3. The chamber 4 is covered by the first filter member 3 so that ink passes or seeps downwards through the first filter member 3 into the collection chamber 4.
The collection chamber 4 has an outlet 5 for delivering the ink from the collection chamber 4 to a reservoir (not shown) for supplying at least one drop forming unit of a print-head (not shown). Furthermore, the collection chamber 4 includes a flow directing member 6 which defines a predetermined flow path for the ink through and around the collection chamber 4 to the outlet 5. In particular, the flow directing member 6 is provided in the form of an elongate projection or wall that divides the collection chamber 4 to form a channel 7, which in turn defines the predetermined flow path indicated by the arrows. In this way, the flow directing member 6 directs or guides the ink entering the collection chamber 4 from the inlet 2 (or indeed at any location) towards the outlet 5 along the predetermined flow path. In this example, the chamber 4 includes a single continuous and circuitous flow path as denoted by the arrows.
As is apparent from
With reference now also to
In this embodiment, both of the end regions 12, 14 of the flow directing member 6 are free standing (i.e. not connected to a side wall 8-11) within the chamber 4. In this way, the elongate wall which forms the flow directing member 6 cooperates at its first end region 12 with side walls 8, 9, 10 of the collection chamber 4 to guide or direct the flow path through a first turn or bend around the collection chamber 4, as was the case in the embodiment of
Referring now to drawing
Similar to the embodiment of
The first filter member 3 is configured to function as a pressure lock to regulate the ink flow. This is realized in that the pores or holes of the first filter member 3 are small enough to allow a capillary effect to hold the ink in the wetted pores or holes of the filter member 3. In this way, the ink may only exit the collection chamber 4 through the outlet 5 if new ink seeps through the first filter member 3 and enters the collection chamber 4 for pressure compensation inside the chamber 4. Thus, the amount of incoming ink may be held equal to the amount of outgoing ink and the ink flow can be regulated. For example, the pressure lock may have a breaking pressure of 10 mbar, for example, or maybe even higher. This is achieved, dependent on the surface tension properties of the ink, by a predetermined maximum passable diameter of the pores or holes of the first filter member 3, for example of 10 μm, dependent on the ink supply system downstream of the filter member 3. As the size of holes or pores of the filter material is mainly relevant for the capillary effect, the total size or surface of the filter member 3 does not limit the pressure lock function. The size of the filter member 3 may be selected to provide multiple paths for the ink to avoid dead zones of the collection chamber 4. Moreover, the larger the size of the filter member 3, the more particles may be collected by the filter member 3 without completely blocking the filter member 3.
With reference to
Finally, referring to
Although specific embodiments of the invention are illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations exist. It should be appreciated that the exemplary embodiment or exemplary embodiments are examples only and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.
It will also be appreciated that in this document the terms “comprise”, “comprising”, “include”, “including”, “contain”, “containing”, “have”, “having”, and any variations thereof, are intended to be understood in an inclusive (i.e. non-exclusive) sense, such that the process, method, device, apparatus or system described herein is not limited to those features or parts or elements or steps recited but may include other elements, features, parts or steps not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the terms “a” and “an” used herein are intended to be understood as meaning one or more unless explicitly stated otherwise. Moreover, the terms “first”, “second”, “third”, etc. are used merely as labels, and are not intended to impose numerical requirements on or to establish a certain ranking of importance of their objects.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16151049 | Jan 2016 | EP | regional |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4463359 | Ayata | Jul 1984 | A |
| 5696546 | Narang et al. | Dec 1997 | A |
| 6388231 | Andrews | May 2002 | B1 |
| 6932462 | Watanabe | Aug 2005 | B2 |
| 20030197767 | Dudenhoefer | Oct 2003 | A1 |
| 20050243145 | Essen | Nov 2005 | A1 |
| 20060007281 | Sonnichsen et al. | Jan 2006 | A1 |
| 20080266370 | Haines et al. | Oct 2008 | A1 |
| 20110277303 | Mallory et al. | Nov 2011 | A1 |
| 20140285595 | Atwood et al. | Sep 2014 | A1 |
| 20140292933 | Hagiwara et al. | Oct 2014 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 169 720 | Jan 1986 | EP |
| 2 216 177 | Aug 2010 | EP |
| 2 946 932 | Nov 2015 | EP |
| WO 0103935 | Jan 2001 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20170197428 A1 | Jul 2017 | US |
