Patent Application
20130147881
The present teachings relate to the field of ink jet printing devices and, more particularly, to high a density piezoelectric ink jet print head and methods of making a high density piezoelectric ink jet print head.
Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet technology can use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored as they can use a wider variety of inks and eliminate problems with kogation.
Piezoelectric ink jet print heads typically include a flexible diaphragm and a piezoelectric element attached to the diaphragm. When a voltage is applied to the piezoelectric element, typically through electrical connection with an electrode electrically coupled to a voltage source, the piezoelectric element deflects causing the diaphragm to flex toward a nozzle (aperture or jet) which increases pressure within an ink chamber and expels a quantity of ink from the chamber through the nozzle. As the diaphragm returns to a relaxed state, it flexes away from the nozzle which decreases pressure within the chamber and draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
Increasing the printing resolution of an ink jet printer employing piezoelectric ink jet technology is a goal of design engineers. Increasing the jet density of the piezoelectric ink jet print head can increase printing resolution. One way to increase the jet density is to eliminate manifolds which are internal to a jet stack. With this design, it is preferable to have a single port through the back of the jet stack for each jet. The port functions as a pathway for the transfer of ink from the reservoir to each ink jet chamber. Because of the large number of jets in a high density print head, the large number of ports, one for each jet, must pass vertically through the diaphragm and between the piezoelectric elements.
Manufacturing a high density ink jet print head assembly having an external manifold has required new processing methods. Methods for manufacturing a print head which use less equipment, fewer processing stages, and reduced materials, and the print head resulting from the method, 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 of the present teachings, a method for forming an ink jet printhead can include providing a diaphragm comprising a plurality of openings therethrough, attaching a piezoelectric array comprising a plurality of piezoelectric actuators to the diaphragm, attaching a pre-formed film spacer to the diaphragm at locations directly between adjacent piezoelectric actuators, wherein the pre-formed film spacer is pre-formed prior to attachment to the diaphragm, comprises a polymer layer, and does not directly overlie the plurality of piezoelectric actuators. The method can further include electrically coupling an electrical interconnect to the plurality of piezoelectric actuators, wherein the film spacer and the plurality of piezoelectric actuators are directly interposed between the diaphragm and the electrical interconnect.
In another embodiment, an ink jet printhead can include a diaphragm comprising a plurality of openings therethrough, a piezoelectric actuator array attached to the diaphragm, a pre-formed film spacer attached to the diaphragm at locations directly between adjacent piezoelectric actuators, wherein the pre-formed film spacer comprises a polymer layer and does not directly overlie the plurality of actuators. The ink jet printhead can further include an electrical interconnect electrically coupled to the plurality of actuators, wherein the film spacer and the plurality of piezoelectric actuators are directly interposed between the diaphragm and the electrical interconnect.
In another embodiment, a printer can include an ink jet printhead having a diaphragm comprising a plurality of openings therethrough, a piezoelectric actuator array attached to the diaphragm, a pre-formed film spacer attached to the diaphragm at locations directly between adjacent piezoelectric actuators, wherein the pre-formed film spacer comprises a polymer layer and does not directly overlie the plurality of actuators, and an electrical interconnect electrically coupled to the plurality of actuators, wherein the film spacer and the plurality of piezoelectric actuators are directly interposed between the diaphragm and the electrical interconnect. The printer can further include a housing which encloses the ink jet 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.
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, a bookmaking machine, a facsimile machine, a multi-function machine, a plotter, etc. The word “polymer” encompasses any one of a broad range of carbon-based compounds formed from long-chain molecules including thermosets, thermoplastics, resins such as polycarbonates, epoxies, and related compounds known to the art.
The formation of a printhead having a plurality of piezoelectric transducers (PZT's) has included various structures and technologies, for example as discussed in U.S. patent Ser. No. 13/011,409, titled “Polymer Layer Removal on PZT Arrays Using A Plasma Etch,” filed Jan. 21, 2011 and incorporated herein by reference in its entirety.
Next, a process to expose the tops of actuators 802 can be performed. In this process, a patterned mask 814 such as a photoresist layer having openings 816 therethrough which expose the piezoelectric actuators 802 can be formed as depicted, for example using a photolithographic process. The structure of
Subsequently, the interstitial layer 812 of
Next, a laser ablation process can be performed from the bottom side of the
In a first laser ablation process, openings through the inlet/outlet plate 810, the body plate 806, and/or the diaphragm 804 itself can be used as a mask to form a self-aligned ink port 908 during an etch. This embodiment can employ the use of a laser beam which is wider than the width of the opening through the diaphragm 804, such that the laser beam is directed onto one or more of the inlet/outlet plate 810, the body plate 806, and the diaphragm 804. In this laser ablation process, the diaphragm 804 can be exposed during the laser ablation process such that ink contacts the diaphragm 804 as it flows through the ink ports 908 during use of the printhead.
In a second laser ablation process, contacting one or more of structures 810, 806, 804 is not desired. In this process, the laser beam can pass through a mask to narrow the beam to a diameter less than a diameter of the opening in the diaphragm 804. The laser beam can be directed through the diaphragm opening so that only structures 808, 812, and 900 are contacted by the laser. In this embodiment, the laser contacts the diaphragm attach adhesive 808 first, then the interstitial layer 812, then the standoff layer 900. In this embodiment, sidewalls of the ink port opening 908 can include the diaphragm attach adhesive 808, the interstitial layer 812, and the standoff layer 900, while neither the stainless steel sidewalls of the openings through the diaphragm 804 nor other portions of the stainless steel diaphragm 804 are exposed by the ink port 908, and ink does not contact the diaphragm 804 as it flows through the ink ports 908 during use of the printhead.
Subsequent to forming the ink port opening 908, the in-process printhead structure 910 of
Reference will now be made in detail to the 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.
Reducing the complexity of a manufacturing process can result in higher yields. Further, a process which uses less manufacturing equipment, requires fewer materials, and reduces manufacturing time can result in a lower cost product. For example, the process used to form the
After forming a structure similar to that depicted in
In the present embodiment, the film spacer 200 covers the opening 112 through the diaphragm 104 as depicted in
After forming a structure similar to that depicted in
Subsequently, an electrical interconnect 400 such as a printed circuit board (PCB), flexible (flex) circuit, or flex cable assembly can be attached to the
In an embodiment, the adhesive 300 is conductive and electrical coupling between each bump 402 and one of the piezoelectric actuators 102 is established through the conductive adhesive 300. In this embodiment, the conductive adhesive 300 can also physically secure the electrical interconnect 400 to the piezoelectric actuators 102 as well as enabling electrical communication between each piezoelectric actuator 102 and the bump 402. In this embodiment using a conductive adhesive 300, each bump 402 may or may not physically contact one of the piezoelectric actuators 102, as electrical communication can be established by the conductive adhesive 300.
In another embodiment, the adhesive 300 can be a nonconductor. In this embodiment, electrical coupling between each bump 402 and one of the piezoelectric actuators 102 can be established through physical contact between each bump 402 and one of the piezoelectric actuators 102, for example using a plurality of asperities as discussed in U.S. patent application Ser. No. 13/097,182 which was incorporated by reference above. In this embodiment, each bump 402 physically contacts one of the piezoelectric actuators 102. Electrical contact between each bump 402 and one of the piezoelectric actuators 102 is established through physical contact between the two structures. In this embodiment, the nonconductive adhesive 300 can physically secure the electrical interconnect 400 to the plurality of piezoelectric actuators 102.
In yet another embodiment, the use of adhesive 300 between each bump 402 and one of the piezoelectric actuators 102 can be omitted. In this embodiment, each bump 402 can be held in physical contact with one of the piezoelectric actuators 102 by the adjacent mechanical bond between the electrical interconnect 400 and film spacer 200. In this embodiment, electrical contact between each bump 402 and its associated piezoelectric actuator 102 is established through physical contact between the two structures 402, 102, and is secured by the mechanical attachment of the electrical interconnect 400 to the film spacer 200.
Subsequently, the openings 112 through which ink passes during operation of the printhead can be cleared using a laser beam 500 output by a laser 502 as depicted in
The completed printhead can include various structures. For example,
The second adhesive layer 612 can first be attached to either the interconnect layer 400 or the polymer layer 608, and then to the other of the interconnect layer 400 or the polymer layer 608 to secure the electrical interconnect 400 to the polymer layer 608. In another embodiment, no adhesive is formed between the electrical interconnect 400 and the film spacer 200, in which case the electrical interconnect 400 is physically attached to the piezoelectric actuators by adhesive 300. It will be understood that a completed printhead can have additional structures which are not depicted for simplicity, and various depicted structures can be removed or modified.
Further, the diaphragm attach adhesive 658 can be patterned prior to attachment to the diaphragm 104. In this embodiment, a width of openings 660 through the diaphragm attach adhesive 658 can be wider than a width of openings 112 through the diaphragm 104. Additionally, the width of openings 112 through the diaphragm 104 are wider than a width of opening 656 through layers 652, 650, 654, and 400. The plurality of openings 660 through the diaphragm attach adhesive 658 align with the plurality of openings 112 through the diaphragm, and are targeted to be concentric therewith.
In the
In an embodiment, opening 660 through diaphragm attach adhesive 108 can have a width of between about 100 μm and about 250 μm, or between about 125 μm and about 225 μm, or between about 150 μm and about 200 μm, for example about 175 μm. Opening 112 through the diaphragm 104 can have a width of between about 75 μm and about 225 μm, or between about 100 μm and about 200 μm, or between about 125 μm and about 175 μm, for example about 150 μm. Opening 656 through the adhesive 652, the film spacer 650, the standoff layer 654, and the conductive interconnect 400 can have a width of between about 25 μm and about 175 μm, or between about 50 μm and about 150 μm, or between about 75 μm and about 125 μm, for example about 100 μm.
Additionally, an opening 656 which can be selectively formed to a desired size and which is smaller than the opening 112 within the diaphragm 104 may also be useful to provide a mechanism for tuning the flow of ink within the printhead (i.e., for tuning the fluidic circuit) without a redesign of the diaphragm 104. After forming opening 658, the aperture plate 600 can be attached to the inlet/outlet plate 110 using adhesive 606.
Once manufacture of the printhead is complete, one or more printheads according to the present teachings can be installed in a printer.
As will be understood by the disclosure herein, a printhead according the an embodiment of the present teachings can be formed without the requirement for a polymer de-gas stage in a de-gas chamber to de-gas a liquid or paste interstitial material layer, a planarization stage using a flat plate within a heated press to planarize an interstitial material layer, a polymer cure in a cure oven to cure a liquid or paste interstitial material into a solid interstitial layer, and a plasma etch process within an etch chamber to remove a solid interstitial layer to expose the piezoelectric actuators. The material of the film spacer, such as a polyimide film or other polymer, may be more compatible with ink during use of the printhead than other materials such as a two part paste which can form an interstitial layer.
Also, as depicted in
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. 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.
