Patent Grant
9278542
The present teachings relate to the field of ink jet printing devices and, more particularly, to a printhead having a filter and a printer including the printhead.
Drop-on-demand ink jet technology is widely used in the printing industry. Printers using drop-on-demand ink jet technology can include the use of a printhead that ejects an ink from a plurality of nozzles in a nozzle plate (i.e., aperture plate). Various ejection technologies may be used to eject ink droplets from the plurality of nozzles including, for example, thermal ejection, electrostatic ejection, or piezoelectric ejection.
The manufacture and storage of printheads and ink can generate an amount of debris and contamination within the printhead and ink that can block ink channels within the printhead and the nozzles in the nozzle plate. These blockages can result in poor printer performance and lead to replacement of the printhead. To reduce or prevent blockage of the ink channels and nozzles, the printhead is manufactured to include a particulate filter or “rock screen.” The particulate filter is a layer within an interior of the printhead that includes a plurality of holes that are smaller than the anticipated size of the contamination. The particulate filter is typically manufactured as part of a printhead manifold, where the printhead manifold incorporates a plurality of laminated layers including the particulate filter layer. Thus, the particulate filter is built well within the printhead interior. The ink enters a printhead ink inlet from an ink reservoir where it is routed through the ink channels in the upper manifold, through the particulate filter, through the ink channels in the lower manifold, and then ejected from the nozzles in the nozzle plate during printing. The particulate filter is designed to last the lifetime of the printhead.
A particulate filter for an ink jet printhead that has advantages over a conventional particulate filter would be desirable.
The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor to delineate the scope of the disclosure. Rather, its primary purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description presented later.
In an embodiment, a printhead can include a printhead body having a first ink inlet, a first plurality of ink channels in fluid communication with the first ink inlet, and a nozzle plate including a first plurality of nozzles in fluid communication with the first plurality of ink channels. The printhead may further include a filter assembly removably attached to the printhead body with at least one mechanical fastener, the filter assembly including a first plate including a first ink inlet, a second plate including a first ink outlet in fluid communication with the first ink inlet of the first plate, and a first ink filter interposed between the first plate and the second plate. The first plate, the second plate, and the first ink filter may be attached together, where the first ink outlet is in fluid communication with the first ink inlet of the printhead body.
In another embodiment, a printer can include a printhead body having a first ink inlet, a first plurality of ink channels in fluid communication with the first ink inlet, and a nozzle plate including a first plurality of nozzles in fluid communication with the first plurality of ink channels. The printhead may further include a filter assembly removably attached to the printhead body with at least one mechanical fastener, the filter assembly including a first plate including a first ink inlet, a second plate including a first ink outlet in fluid communication with the first ink inlet of the first plate, and a first ink filter interposed between the first plate and the second plate. The first plate, the second plate, and the first ink filter may be attached together, where the first ink outlet is in fluid communication with the first ink inlet of the printhead body. The printer can further include a housing that houses the printhead.
The accompanying drawings, which are incorporated in, and constitute a part of this specification, illustrate embodiments of the present teachings and, together with the description, serve to explain the principles of the disclosure. In the figures:
It should be noted that some details of the FIGS. have been simplified and are drawn to facilitate understanding of the present teachings rather than to maintain strict structural accuracy, detail, and scale.
Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
As used herein, unless otherwise specified, the word “printer” encompasses any apparatus that performs a print outputting function for any purpose, such as a digital copier, bookmaking machine, facsimile machine, a multi-function machine, electrostatographic device, etc.
As discussed above, a conventional particulate filter for an ink jet printhead is formed within an interior of the printhead and is designed to last the lifetime of the printhead. However, the particulate filter area is limited by the cross-sectional area of the printhead reservoir, as well as by the location and space requirements of, for example, other internally packaged printhead components, fluid paths, and air paths. Conventional particulate filters thus have a finite capacity per unit area for holding debris, and a finite functional life for a given size. The functional life of the filter thereby limits the functional life of the printhead, which will vary with different fluids and printheads of varying particle content. Printhead performance decreases once the filter capacity has been exhausted, at which time the printhead must be replaced. Replacement of the printhead is expensive and may lead to decreased customer satisfaction and brand loyalty.
An embodiment of the present teachings includes a printhead having a removable and consumer-replaceable particulate filter (i.e., an ink filter), where the lifetime of the ink filter does not limit the lifetime of the printhead. Further, the capacity of the ink filter is not limited by available space within the interior of the printhead, nor by the location of ink channels within the interior of the printhead. A printhead according to the present teachings includes a filter assembly such as an external filter assembly (EFA) that is mechanically attached to a printhead body, wherein the printhead body includes the printhead manifold and a nozzle plate attached to the printhead body. The EFA may be separated from the printhead manifold once the EFA has become blocked with debris and contamination, or becomes otherwise unsuitable as a filter.
The EFA 102 is removably attached to, and in fluid communication with, a printhead body 104 of the printhead 100. In an embodiment, the EFA 102 is removably attached to the printhead body 104 using at least one (i.e., one or more) mechanical fasteners 106 such as bolts, pins, clamps, etc. The EFA 102 includes at least one EFA ink inlet 108, where each EFA ink inlet 108 may be in fluid communication with at least one ink reservoir (not individually depicted for simplicity) that is external to the EFA 102 and printhead body 104. Each EFA ink inlet 108 may allow the introduction and filtering of a different ink, for example two different ink compositions, viscosities, and/or colors, into the EFA 102.
Throughout this document, a reference number ending in “A” is a structure that corresponds to, channels, or identifies, a first ink, for example first ink 400A as depicted in
The EFA first plate 302 can include a first ink cavity 310A and the third EFA plate 306 can further include a second ink cavity 310B. The EFA second plate 304 can include a first recess 312A that receives a first seal 314A, and a second recess 312B that receives a second seal 314B. Each of the seals 314A, 314B may be, for example, an O-ring formed from a flexible material such as a high-temperature silicone or other flexible polymer, or another suitable synthetic or natural material.
In this embodiment, the second ink filter 308B, at least in part, defines a first ink passthrough channel 316A and the first ink filter 308A defines, at least in part, a second ink passthrough channel 316B. The first ink passthrough channel 316A allows the first ink 400A to be channeled from the third EFA plate 306, through the first ink passthrough channel 316A in the second filter 308B, to the EFA second plate 304 without being filtered by the second filter 308B. Similarly, the second ink passthrough channel 316B allows the second ink 400B to be channeled from the EFA first plate 302, through the second passthrough channel 316B in the first filter 308A, to the third EFA plate 306 without being filtered by the first filter 308A.
During operation of the EFA 102, the first ink 400A is introduced into the EFA first ink inlet 108A under the influence of an upstream positive pressure. Due to the resistance of the flow of the first ink 400A through the first filter 308A, the first ink 400A first flows into, and fills, the first ink cavity 310A in the EFA first plate 302. Once the first ink 400A fills the first ink cavity 310A, continued pressure forces the first ink 400A through the first filter 308A, which filters the first ink 400A. The first ink 400A then flows through the EFA third plate 306, out of the third plate first ink outlet 318A, through the first ink passthrough channel 316A in the second filter 308B, and through the EFA second plate 304. Subsequently, the first ink 400A flows out of the EFA first ink outlet 300A and into the printhead body first ink inlet 200A, where it is routed to, and ejected from, one or more of the nozzles 712 (
During a printing operation, the second ink 400B is introduced into the EFA second ink inlet 108B under the influence of an upstream positive pressure. The second ink 400B flows through the second ink passthrough channel 316B in the first filter 308A without being filtered, and then out of the third plate second ink outlet 318B. Due to the resistance of the flow of the second ink 400B through the second filter 308B, the second ink 400B first flows into, and fills, the second ink cavity 310B in the EFA third plate 306. Once the second ink 400B fills the second ink cavity 310B, continued pressure forces the second ink 400B through the second filter 308B, which filters the second ink 400B. The second ink 400B then flows through the EFA second ink outlet 300B and into the printhead body second ink inlet 200B, where it is routed to ink channels 708 (
The first seal 314A and the second seal 314B may reduce or prevent leakage of the first ink 400A and the second ink 400B respectively from between the EFA 102 and the printhead body 104 during the transfer of ink from the EFA 102 to the printhead body 104.
During operation of the printhead 100, the first ink 400A is located within the first ink inlet 108A and the first ink cavity 310A of the first plate 302, the third plate first ink outlet 318A defined by the EFA third plate 306, the first ink passthrough channel 316A defined by the second filter 308B, the first ink outlet 300A of the second plate 304, and the first ink inlet 200A of the printhead body 104. Similarly, the second ink 400B is located within the second ink inlet 108B of the first plate 302, the second ink passthrough channel 316B defined by the first filter 308A, the second ink cavity 310B defined by the third plate 306, the second ink outlet 300B of the second plate 304, and the second ink inlet 200B of the printhead body 104.
Because the EFA 102 is a separate subassembly from the printhead manifold in the printhead body 104, the ink filter area is not limited by the cross-sectional area of the printhead reservoir, nor by the location and space requirements of, for example, other internally packaged printhead body components, fluid paths, or air paths. The first ink cavity 310A and the second ink cavity 310B allow the inks 400A, 400B respectively to physically contact a large area of the filters 308A, 308B respectively before they are filtered. Thus almost the entire area of the filters 308A, 308B are used for filtering. The relatively large surface area filters 308A, 308B thereby decrease clogging compared to filtering across a smaller surface area such as a conventional printhead particulate filter that is formed within a small area of the printhead manifold. While the filter area of an embodiment will depend on the filter design, a EFA filter in an embodiment of the present teachings may have a filtering area of from about 645 mm2 or higher for each ink type 400A, 400B. In an embodiment, the EFA may provide a filter 308 having a filter surface area that is six times the filter surface area of a conventional filter within the same footprint. However, it will be understood that a filter having a smaller or even larger filter surface area may also be designed in accordance with an embodiment of the present teachings, and filter embodiments having other areas, either larger or smaller than 645 mm2, are also contemplated.
Once the EFA 102 has reached its end of life, which may be because of filter clogging, a routine maintenance schedule, or because of other factors, the EFA 102 may be removed and replaced with a new or otherwise different EFA, for example by the printer user. In an embodiment, the one or more mechanical fasteners 106 are unbolted, unpinned, unclamped, etc., to allow the separation and removal of the EFA 102 from the printhead body 104. The replacement EFA is then attached to the printhead body 104 using the one or more mechanical fasteners 106, and printing may then be resumed. In an embodiment, the EFA 102 may be returned to the factory for reconditioning, where the EFA 102 is disassembled, the filters 308A, 308B are replaced, and the reconditioned EFA 102 is reused. In another embodiment, the depleted EFA 102 may be discarded or recycled.
The EFA plates 302-306 may be manufactured from a metal such as steel, aluminum, etc., or a polymer that can withstand temperatures encountered during use, for example, 150° C. or above. The filters 308 may be manufactured from a stainless steel mesh, or another sufficient natural or synthetic porous material. The plates 302-306 and the filters 308 may be laminated together using conventional stack and glue operations, for example, by applying heat and pressure with a press to cure the bonding agent. In an embodiment, a liquid adhesive such as Sylgard® available from Dow Corning of Midland, Mich., may be dispensed onto the plates 302-306 and filters 308 in a pattern matching ridges that define the fluidic cavities 310A, 310B. The plates 302-306 and filters 308 are then stacked and clamped under pressure, then the adhesive (not individually depicted for simplicity) is cured in an oven at sufficient temperatures. In another embodiment, a pressure-sensitive adhesive may be die cut to size and then clamped under pressure to bond the EFA 102 together.
In the embodiment of
In
In the
During an operation such as printing, the first ink (for example first ink 400A,
Also during an operation such as printing, the second ink (for example second ink 400B,
During the printing and storage of the first ink 400A and the second ink 400B, pressure and/or adhesive between the ridge 610 and the second plate 606 prevents the two inks from crossing the ridge 610, entering the adjacent cavity, and mixing, or other cross-contamination. Thus in
In
While the description above describes the EFA 102 with reference to filtering a fluid where the fluid is liquid ink, the EFA 102 may be used for filtering another fluid within a printhead, for example, air or another gas or gases. In an embodiment, the first ink 400A and the second ink 400B may instead be a first fluid 400A and a second fluid 400B, where one of the fluids is a liquid and the other of the fluids is a gas, or where both of the fluids are gases.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present teachings are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5. In certain cases, the numerical values as stated for the parameter can take on negative values. In this case, the example value of range stated as “less than 10” can assume negative values, e.g. −1, −2, −3, −10, −20, −30, etc.
While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it will be appreciated that while the process is described as a series of acts or events, the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and/or concurrently with other acts or events apart from those described herein. Also, not all process stages may be required to implement a methodology in accordance with one or more aspects or embodiments of the present teachings. It will be appreciated that structural components and/or processing stages can be added or existing structural components and/or processing stages can be removed or modified. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of” is used to mean one or more of the listed items can be selected. As used herein, the term “one or more of” with respect to a listing of items such as, for example, A and B, means A alone, B alone, or A and B. The term “at least one of” is used to mean one or more of the listed items can be selected. Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term “conformal” describes a coating material in which angles of the underlying material are preserved by the conformal material. The term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. Other embodiments of the present teachings will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims.
Terms of relative position as used in this application are defined based on a plane parallel to the conventional plane or working surface of a workpiece, regardless of the orientation of the workpiece. The term “horizontal” or “lateral” as used in this application is defined as a plane parallel to the conventional plane or working surface of a workpiece, regardless of the orientation of the workpiece. The term “vertical” refers to a direction perpendicular to the horizontal. Terms such as “on,” “side” (as in “sidewall”), “higher,” “lower,” “over,” “top,” and “under” are defined with respect to the conventional plane or working surface being on the top surface of the workpiece, regardless of the orientation of the workpiece.
| Number | Name | Date | Kind |
|---|---|---|---|
| 7448741 | von Essen | Nov 2008 | B2 |
| 8201928 | Gerner | Jun 2012 | B2 |
