Patent Application
20240316927
This application claims priority to Korean Patent Application No. 10-2023-0039048, filed on Mar. 24, 2023, and Korean Patent Application No. 10-2023-0061263, filed on May 11, 2023, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in their entirety are herein incorporated by reference.
One or more embodiments relate to an inkjet printing head, and more particularly, to an inkjet printing head having improved durability.
Metal materials such as copper, gold, and silver, ceramic, polymers, as well as general dyes, have been used as printing solutions for industrial inkjet printers. Industrial inkjet printers have been used for industrial graphics, display, solar battery technologies in a method of directly printing on various objects such as substrates, films, woven products, and displays. Particularly, in the field of display technology, processes using inkjet printers have been applied to manufacturing of color filters, orientation processes of liquid crystals, manufacturing of organic emission layers, manufacturing of quantum-dot emission-layers, and the like. An inkjet printing device includes an inkjet printing head including at least one ink transport path (or a nozzle).
However, the ink transport path is likely to be clogged as the inkjet printing head is used. To prevent the aforementioned problem, after performing a printing process, a process of physically or chemically cleaning a portion of the inkjet printing head for discharging ink may be performed. However, due to the cleaning process, the portion for discharging the ink may be damaged.
One or more embodiments include an inkjet printing head with improved durability. However, the technical goal is only an example, and the scope of the disclosure is not limited thereto.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.
According to one or more embodiments, an inkjet printing head includes: a chamber configured to store ink; a spray assembly, which is disposed under the chamber, and defines an ink transport path therein connected to an inner portion of the chamber, where ink that passes through the ink transport path is discharged to the outside through a bottom surface of the spray assembly; a first self-assembly monolayer covering the bottom surface of the spray assembly; an adhesive layer disposed between the bottom surface of the spray assembly and the first self-assembly monolayer and including a metal-carbon composition; and an inorganic material layer disposed between the adhesive layer and the first self-assembly monolayer.
The inkjet printing head may further include a second self-assembly monolayer covering at least a portion of an inner surface of the ink transport path.
The adhesive layer may include carbon 1 weight percent (wt %) to 50 wt %.
The metal-carbon composition may include aluminum oxide.
The adhesive layer may be disposed between an inner surface of the ink transport path and the second self-assembly monolayer.
The spray assembly may further include a piezoelectric element layer disposed under the chamber and a nozzle plate, which is disposed under the piezoelectric element layer and of which a bottom surface is the bottom surface of the spray assembly.
The piezoelectric element layer may define, as a portion of the ink transport layer, a first nozzle portion connected to an inner portion of the chamber, the nozzle plate may define, as another portion of the ink transport path, a second nozzle portion connected to the first nozzle portion and penetrating the bottom surface of the nozzle plate, and an average diameter of the first nozzle portion may be greater than an average diameter of the second nozzle portion.
The nozzle plate may define, as a portion of the second nozzle portion, a 2-1 nozzle portion connected to the first nozzle portion, and a 2-2 nozzle portion connected to the 2-1 nozzle portion and penetrating the bottom surface of the nozzle plate, as another portion of the second nozzle portion, and an average diameter of the 2-1 nozzle portion may be greater than an average diameter of the 2-2 nozzle portion.
A diameter of the 2-1 nozzle portion may decrease in a direction toward the 2-2 nozzle portion from the first nozzle portion.
The second self-assembly monolayer may cover an inner surface of the first nozzle portion and an inner surface of the second nozzle portion.
The inorganic material layer may include a first part disposed between the adhesive layer and the first self-assembly monolayer to cover the bottom surface of the nozzle plate and a second part disposed between the adhesive layer and the second self-assembly monolayer to cover an inner surface of the 2-2 nozzle portion.
The second self-assembly monolayer may cover an inner surface of the first nozzle portion and an inner surface of the 2-1 nozzle portion, and the first self-assembly monolayer may cover an inner surface of the 2-2 nozzle portion.
The inorganic material layer disposed between the adhesive layer and the first self-assembly monolayer may cover the bottom surface of the nozzle plate.
A deionized water (DI) contact angle of the first self-assembly monolayer may be equal to or greater than 10° and smaller than or equal to 200°.
A DI contact angle of the second self-assembly monolayer may be equal to or greater than 10° and smaller than or equal to 130°.
The inorganic material may include silicon (Si), the first self-assembly monolayer may include a first composition, in which a first head group including Si faces the inorganic material layer and which includes a first tail group in which a hydrophobic function group is exposed outside, and the first head group and the first tail group may be connected to each other by a first carbon chain.
The inkjet printing head may further include a second self-assembly monolayer covering at least a portion of an inner surface of the ink transport path, the second self-assembly monolayer may include a second compound in which a second head group including Si faces the inorganic material layer and which includes a second tail group in which a hydrophobic function group is exposed outside, and the second head group and the second tail group are connected to each other by a second carbon chain, and a length of the first carbon chain may be less than or equal to a length of the second carbon chain.
The ink may include an ink composition including zinc (Zn).
The ink may include zinc selenide (ZnSe).
The chamber may include a mesh layer arranged in parallel with the bottom surface of the spray assembly in the chamber, and a metal layer disposed under the mesh layer in parallel with the mesh layer in the chamber, wherein a surface of the mesh layer and a surface of the metal layer may be coated with the second self-assembly monolayer, and the adhesive layer may further be disposed between the surfaces of the mesh layer and the coated second self-assembly monolayer and between the metal layer and the coated second self-assembly monolayer.
The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, “a”, “an,” “the,” and “at least one” do not denote a limitation of quantity, and are intended to include both the singular and plural, unless the context clearly indicates otherwise. For example, “an element” has the same meaning as “at least one element,” unless the context clearly indicates otherwise. “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the disclosure, the expression “at least one of a, b or c” indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
In the following embodiments, when a portion such as a layer, a film, an area, or a component is “on” or “above” another portion, the portion may be “directly” on the other portion, or other components may be located therebetween. In the drawings, the sizes of components may be exaggerated or reduced for convenience of description. For example, since the size and thickness of each component is arbitrarily shown in the drawings for convenience of description, the disclosure is not necessarily limited to those illustrated.
An x-axis, a y-axis, and a z-axis are not limited to three axes on an orthogonal coordinate system, and may be interpreted as a wide meaning including the same. For example, the x-axis, y-axis, and z-axis may be orthogonal to one another, but may also refer to different directions that are not orthogonal to one another.
It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein. Hereinafter, an inkjet printing head according to an embodiment will be described in detail according to the descriptions.
The inkjet printing head according to an embodiment may be used for printing devices configured to print using ink such as a quantum-dot ink composition.
As shown in
The ink for the inkjet printing head may be injected into the chamber IC through an ink inlet IL and may be discharged from the chamber IC to the outside through an ink outlet OL. Like this, the ink may mainly move through a route of the ink inlet IL—the chamber IC—the ink outlet OL. The ink inlet IL may penetrate the first housing HS1 and communicate the chamber IC to inject the ink into the chamber IC, and the ink outlet OL may penetrate the first housing HS1 and communicate the chamber IC to discharge the ink from the chamber IC. The ink inlet IL and the ink outlet OL may be open or closed according to necessity, and opening and closing thereof may be manually or automatically controlled.
The chamber IC for storing the ink may include a first chamber IC1 connected to the ink inlet IL and the ink outlet OL, a second chamber IC2 separated from the first chamber IC1 by a mesh layer 160, and a third chamber IC3 in which at least a central area thereof is separated from the second chamber IC2 by a metal layer 140. Therefore, the second chamber IC2 and the third chamber IC3 may share a connected space in an area outside the metal layer 140 in which the metal layer 140 is not arranged.
The ink may be filtered by the mesh layer 160 in the first chamber IC1 and move to the second chamber IC2. The ink that has moved to the second chamber IC2 may have been removed of impurities after the filtering. The ink may move from the second chamber IC2 to the third chamber IC3, and due to the metal layer 140 separating at least the central area of the third chamber IC3 from the second chamber IC2, the ink may move to the spray assembly NA through the area outside the metal layer 140 (i.e., a space in which the second chamber IC2 and the third chamber IC3 are connected to each other). The ink may be discharged to the outside of the spray assembly NA through the ink transport path of the spray assembly NA.
The spray assembly NA may discharge the ink outside through a bottom surface BTL of the spray assembly NA. The ink transport path NZ may penetrate the bottom surface BTL of the spray assembly NA. The ink transport path NZ, which is a nozzle, may be controlled to discharge an appropriate amount of ink to the outside.
That is, the spray assembly NA may be arranged under the chamber IC, may define the ink transport path NZ therein connected to inside of the chamber IC, and may discharge the ink, which has passed through the ink transport path NZ, through the bottom surface BTL.
The spray assembly NA may include the piezoelectric element layer 121 and a nozzle plate 111 disposed under the piezoelectric element layer 121. The piezoelectric element layer 121 may include a piezoelectric material, e.g., lead zirconate titanate (“PZT”). The piezoelectric element layer 121 may be controlled in response to an electrical signal delivered from the driving circuit BD, and may include a piezoelectric actuator configuration known in the field. In an embodiment, the nozzle plate 111 may include an organic material such as polyimide (PI), and may include a metal material such as stainless use steel (“SUS”), iron (Fe), chromium (Cr), and nickel (Ni). The nozzle plate 111 may extend in a horizontal direction (i.e., D2 in
The spray assembly NA may define the ink transport path NZ therein penetrating the piezoelectric element layer 121 and the nozzle plate 111. The ink transport path NZ may have a bottleneck structure. Accordingly, a pressure of the ink discharged through the ink transport path NZ may increase while transported through the ink transport path NZ
As shown in
The bottom surface BTL of the spray assembly NA may be covered by the first self-assembly monolayer 230. That is, the bottom surface BTL of the spray assembly NA may be coated and protected by the first self-assembly monolayer 230.
The first self-assembly monolayer 230 may include a first compound including a first head group including silicon (Si) and a first tail group exposed outside. In this case, the first head group and the first tail group may be connected to each other by a first carbon chain.
The first head group may include a structure in which at lest one of Methoxy (—OCH3), chlorine (Cl), and hydrogen (—H) si is coupled to a central Si. The first head group may be arranged to face the bottom surface BTL of the spray assembly NA, and may be adhere to the inorganic material layer 220 to be described later.
In an embodiment, the first tail group may include a structure in which at least one of —F, —CF, —CF2, and —CF3 is coupled to a central carbon (C). The first tail group may be hydrophobic and prevent condensation of the ink. A DI contact angle of the first self-assembly monolayer 230 including the first tail group may be equal to or greater than 10° and smaller than or equal to 200°. That is, desirably, the first tail group may include a function group including fluoride (F). Accordingly, the first tail group has a lower adsorption ratio, and accordingly, the possibility that impurities are likely to remain on a surface decreases. As used herein, the “DI contact angle” is defined as a “contact angle of deionized water”.
The first carbon chain may have a chain structure including eight or more and fifty or less carbon atoms. The number of carbon atoms in the first carbon chain may be modified according to necessity. The first carbon chain may be arranged in parallel to other neighboring carbon chains.
The first self-assembly monolayer 230 may be formed using sputtering method, physical vapor deposition (“PVD”) method, chemical vapor deposition (“CVD”) method, or the like.
The adhesive layer 210 may be disposed between the bottom surface BTL of the spray assembly NA and the first self-assembly monolayer 230. The adhesive layer 210, which is one of layers included in the coating layers of the multi-layered structure, may adhere a target of coating to other layers. To adhere to various components, the adhesive layer 210 may include a metal-carbon composition.
In an embodiment, for example, the adhesive layer 210 may include carbon of 1 weight percent (wt %) to 50 wt %. By containing a certain amount of carbon, the metal-carbon composition may be more durable the adhesive layer 210 including the metal or the metal oxide.
In an embodiment, for example, the adhesive layer 210 may include an aluminum oxide (AlxOx), and may include a function group coupled to AlxOx and including C. The metal-carbon composition of the adhesive layer 210 may include a hydrocarbon function group (CxHx) coupled to aluminum (AI). Accordingly, the adhesive layer 210 according to an example may include AlxOx(CxHx). When the hydrocarbon function groups (CxHx) are further added to the metal-carbon composition, oxygen (O) atoms may be removed as much as the amount of added hydrocarbon function groups.
In an embodiment, for example, contents of compositions included in the adhesive layer 210 may be in numerical ranges as shown in Table 1 below.
—Numerical ranges of contents of compositions included in the adhesive layer 210—
Here, a reference of calculating wt % is a total weight of the adhesive layer 210 that is a target of composition analysis, and other elements such as hydrogen, in addition to Al, C, and O, may be further included in the adhesive layer 210.
However, the features of the adhesive layer 210 may be controlled by adjusting the content of carbon, and the control on the content of carbon may be simultaneously performed with control on a content of oxygen. For example, one oxygen in a covalent bond with Al may be debonded, and a carbon atom may be in a covalent bond with Al, in the place of the oxygen that has been debonded. Accordingly, when the content of carbon may increase, a content of oxygen may decrease, and the content of carbon and the content of oxygen may be inversely proportional.
In an embodiment, for example, a thickness of the adhesive layer 210 may be equal to greater than about 10 nanometers (nm) and less than or equal to about 50 nm. As a distance between a top surface and the bottom surface BTL of the bottom surface BTL may be about 75 um, the adhesive layer 210 may be considerably thinner than the nozzle plate 111.
The adhesive layer 210 may be formed using sputtering method, CVD method, atomic layer deposition (“ALD”) method, or the like. However, as other components (e.g., the nozzle plate 111 including PA) may be influenced in a high-temperature process, the adhesive layer 210 may also be formed using low-temperature CVD method or ALD method.
The inorganic material layer 220 may be disposed between the adhesive layer 210 and the first self-assembly monolayer 230. In an embodiment, the inorganic material layer 220 may include an intermediate layer including silicon (Si). As described above, the first head group of the first self-assembly monolayer 230 may be arranged to face the inorganic material layer 220. As the first head group includes Si that is a same material as the inorganic material layer 220, adhesion between the inorganic material layer 220 and the first self-assembly monolayer 230 may be enhanced.
As shown in
At least the portion of the inner surface of the ink transport path NZ may be covered by the second self-assembly monolayer 240. That is, at least the portion of the inner surface of the ink transport path NZ may be coated and protected by the second self-assembly monolayer 240.
The second self-assembly monolayer 240 may include a second compound which includes a second head group including Si and a second tail group exposed outside. In this case, the second head group and the second tail group may be connected to each other by a second carbon chain.
The second head group may include a structure in which at least one of —OCH3, Cl, and —H are coupled to a central Si. The second head group may be arranged to face the inner surface of the ink transport path NZ.
The second tail group may have a structure in which at least one of —H, —CH, —CH2, —CH3, —F, —CF, —CF2, and —CF3 is coupled to a central C. The second tail group may be hydrophobic and prevent condensation of ink. A DI contact angle of the second self-assembly monolayer 240 including the second tail group may be equal to or greater than 10° and smaller than or equal to 130°. Desirably, the second tail group may include hydrocarbon. As the second self-assembly monolayer 240 is to be formed in the ink transport path NZ, the second self-assembly monolayer 240 may include a material that costs less and is easier to form than a material of the first self-assembly monolayer 230 formed on the bottom surface BTL.
The second carbon chain may have a chain structure including two or more and fifty or less carbons atoms. The number of carbon atoms in the second carbon chain may be different according to necessity. The second carbon chain may be arranged in parallel to other neighboring carbon chains.
For example, the number of carbon atoms included in the second carbon chain may be less than or equal to the number of carbon atoms included in the first carbon chain. This is because the first carbon chain, which is arranged to face the outside of the spray assembly NA, may need a structure firmer than a structure of the second carbon chain.
In an embodiment, for example, the DI contact angle of the second self-assembly monolayer 240 including the second tail group may be smaller than or equal to the DI contact angle of the first self-assembly monolayer 230 including the first tail group. This is because the first self-assembly monolayer 230 is arranged on the bottom surface BTL facing the outside of the spray assembly NA and thus hydrophobicity stronger than hydrophobicity of the second self-assembly monolayer 240 may be required for the first self-assembly monolayer 230.
The adhesive layer 210 may be disposed between the bottom surface BTL and the second self-assembly monolayer 240 of the spray assembly NA. The adhesive layer 210, which is a layer same as the adhesive layer 210 described above, may include a layer obtained by extension of the adhesive layer 210 disposed between the bottom surface BTL of the spray assembly NA and the first self-assembly monolayer 230. Therefore, the features of the adhesive layer 210 disposed between the bottom surface BTL of the spray assembly NA and the second self-assembly monolayer 240 are as described above.
For example, the second self-assembly monolayer 240 may be formed using sputtering method, PVD method, CVD method, or the like.
As described above, the spray assembly NA may include the piezoelectric element layer 121 disposed under the chamber IC and the nozzle plate 111 disposed under the piezoelectric element layer 121. A bottom surface of the nozzle plate 111 may include a bottom surface of the spray assembly NA, or may be included in at least a portion of the bottom surface BTL of the spray assembly NA.
The piezoelectric element layer 121 may define, as a portion of the ink transport path NZ, a first nozzle portion NZ1 connected to the inner portion of the chamber IC. The first nozzle portion NZ1 may penetrate the piezoelectric element layer 121. The first nozzle portion NZ1 may be connected to the third chamber IC3 described above, and may receive the ink from the third chamber IC3 and transport the ink. The first nozzle portion NZ1 may be defined by an inner surface of the piezoelectric element layer 121, the adhesive layer 210 covering the inner surface of the piezoelectric element layer 121, and/or the second self-assembly monolayer 240.
An inner surface of the first nozzle portion NZ1 may further include a separate coating layer. In an embodiment, for example, the inner surface of the first nozzle portion NZ1 may be coated with an Al compound layer. An example of the Al compound may include AIOF. The Al compound may be damaged by particles in the ink. According to occasions, the Al compound may be peeled off by the particles in the ink and cause clogging of the first nozzle portion NZ1. Accordingly, the inner surface of the first nozzle portion NZ1 has to be further coated.
An average diameter of the first nozzle portion NZ1 may be greater than an average diameter of a second nozzle portion NZ2 to be described later. Like this, as the average diameter of the first nozzle portion NZ1 is greater than the average diameter of the second nozzle portion NZ2 to be described later, the ink moving from the first nozzle portion NZ1 to the second nozzle portion NZ2 may receive a higher pressure and be discharged outside the spray assembly NA. As used herein, the “diameter” is measured in a plan view (i.e., view in a vertical direction D1).
The nozzle plate 111 may include, as another portion of the ink transport path NZ, the second nozzle portion NZ2 connected to the first nozzle portion NZ1 and penetrating the bottom surface of the nozzle plate 111. The nozzle plate 111 may define: a 2-1 nozzle portion NZ2-1 connected to the first nozzle portion NZ1, as a portion of the second nozzle portion NZ2; and a 2-2 nozzle portion NZ2-2 connected to the 2-1 nozzle portion NZ2-1 and penetrating the bottom surface of the nozzle plate 111, as another portion of the second nozzle portion NZ2.
The second nozzle portion NZ2 may be defined by an inner surface of the nozzle plate 111, the adhesive layer 210 covering the inner surface of the nozzle plate 111, and/or the second self-assembly monolayer 240.
The 2-1 nozzle portion NZ2-1 may be defined by an inner side inclining toward the bottom surface of the nozzle plate 111 in the inner surface of the nozzle plate 111. Accordingly, a diameter of the 2-1 nozzle portion NZ2-1 may decrease in a direction from the first nozzle portion NZ1 toward the 2-2 nozzle portion NZ2-2.
The 2-2 nozzle portion NZ2-2 may be defined by a through hole extending from an end of the inner surface inclining toward the bottom surface of the nozzle plate 111 in the inner surface of the nozzle plate 111 to the bottom surface of the nozzle plate 111. The 2-2 nozzle portion NZ2-2 may be defined as a portion of the inner surface of the nozzle plate 111, i.e., an inner surface of a portion from an end of the 2-1 nozzle portion NZ2-1 to the bottom surface of the nozzle plate 111, and the 2-2 nozzle portion NZ2-2 may include a portion of an ink transport path extending in a vertical direction (e.g., D1 in
Here, an average diameter of the 2-1 nozzle portion NZ2-1 may be greater than an average diameter of the 2-2 nozzle portion NZ2-2. That is, according to structures of the 2-1 nozzle portion NZ2-1 and the 2-2 nozzle portion NZ2-2, the ink moving from the 2-1 nozzle portion NZ2-1 to the 2-2 nozzle portion NZ2-2 may receive a higher pressure and be discharged outside the spray assembly NA. That is, the 2-1 nozzle portion NZ2-1 and the 2-2 nozzle portion NZ2-2 may together form a bottleneck structure.
Here, the inorganic material layer 220 described not only may be arranged between the adhesive layer 210 and the first self-assembly monolayer 230 to cover the bottom surface of the nozzle plate 111, but also may be arranged between the adhesive layer 210 and the second self-assembly monolayer to cover an inner surface of the 2-2 nozzle portion NZ2-2.
The piezoelectric element layer 121 may adhere to the nozzle plate 111 by an adhesive material layer 113. The adhesive material layer 113 may include, e.g., a layer including epoxy. A surface of the adhesive material layer 113 may adhere to a bottom surface of the piezoelectric element layer 121, and another surface of the adhesive material layer 113 may adhere to the top surface of the nozzle plate 111.
In addition, a metal electrode layer 122 may be disposed on a top surface of the piezoelectric element layer 121. The metal electrode layer 122 may include a metal material such as Al. The metal electrode layer 122 may be electrically connected to the driving circuit BD described above and receive an electrical signal from the driving circuit BD. The metal electrode layer 122 may be configured to deliver an electrical signal to the piezoelectric element layer 121 according to the electrical signal that has been received.
A side surface of the piezoelectric element layer 121 and the bottom surface of the piezoelectric element layer 121 may be coated by an organic coating layer 124. In an embodiment, for example, the organic coating layer 124 may include a parylene coating layer. Parylene may protect the piezoelectric element layer 121 from numerous harmful materials, and particularly, due to low moisture permeability, has an excellent effect in waterproof or moisture-proof.
A transparent layer 123 may be disposed on the top surface of the piezoelectric element layer 121 and a top surface of the organic coating layer 124 covering the top surface of the piezoelectric element layer 121. In an embodiment, for example, the transparent layer 123 may include glass component. An additional organic coating layer 124′ may be disposed on a top surface of the transparent layer 123. For example, the additional organic coating layer 124′ may include a layer identical to the organic coating layer 124 described above, i.e., a parylene coating layer.
Like this, the adhesive layer 210 described above may cover the organic coating layer 124, which coats the piezoelectric element layer 121 and the transparent layer 123, and the additional organic coating layer 124′. More particularly, the adhesive layer 210 may cover a side surface of the organic coating layer 124 and side surfaces and a top surface of the additional organic coating layer 124′ covering the top surface of the piezoelectric element layer 121 and the transparent layer 123. In addition, the adhesive layer 210 may also cover a side surface of the transparent layer 123 exposed between the organic coating layer 124 and the additional organic coating layer 124′. Furthermore, the adhesive layer 210 may also cover a side surface of the adhesive material layer 113 exposed between the piezoelectric element layer 121 (or the organic coating layer 124) and the nozzle plate 111.
A silicon oxide film 112 may be disposed on the bottom surface of the nozzle plate 111. In an embodiment, for example, the silicon oxide film 112 may include SiOC. The ink transport path NZ (the second nozzle portion NZ2 and the 2-1 nozzle portion NZ2-1) may penetrate the silicon oxide film 112 and the nozzle plate 111.
For example, the silicon oxide film 112 may be formed using sputtering method, PVD method, or the like.
According to an embodiment, the PFA layer may be disposed on a bottom surface of the silicon oxide film 112. However, as the PFA layer is fragile to physical impacts, the aforementioned multi-layered coating layer (e.g., the adhesive layer 210, the inorganic material layer 220, and the first self-assembly monolayer 230) may be formed after removing the PFA layer. That is, after purchasing a complete product in which the PFA layer is formed, may only remove the PFA layer and form the multi-layered coating layer in the place of the PFA layer that has been removed.
Hereinafter, the PFA layer disclosed in the inkjet printing device according to the Comparative Example may include a coating layer used in an inkjet printing head 1024i SHE model (a model launched after the second half of 2019) manufactured by KONICA MINOLTA, Inc., which is a coating layer including CFO as a composition.
The ink discharged from the inkjet printing head described above may include a quantum-dot ink composition. The ink according to the present embodiment may include a (quantum-dot) ink composition including zinc (Zn). In an embodiment, for example, the ink may include zinc selenide (ZnSe).
The ZnSe may be a material mainly used for a green-based or red-based quantum-dot ink composition. Like in the following experiments, when an ink including ZnSe is used, clogging in the inner portion of the nozzle may occur due to particles included in the ink. Therefore, the inkjet printing head according to the present embodiment may be used with the ink including the quantum-dot ink composition including Zn.
Although not shown, a planarization layer (not shown) may be disposed between the silicon oxide film 112 and the adhesive layer 210. In an embodiment, for example, the planarization layer (not shown) may include parylene. As described above, the organic coating layer 124 including parylene may be arranged with reference to the piezoelectric element layer 121, and therefore, the planarization layer (not shown) may be disposed between the silicon oxide film 112 and the adhesive layer 210 to cover the bottom surface of the nozzle plate 111.
As described above, the second self-assembly monolayer 240 may cover the inner surface of the first nozzle portion NZ1 and an inner surface of the 2-1 nozzle portion NZ2-1, and the first self-assembly monolayer 230 may cover the inner surface of the 2-2 nozzle portion NZ2-2. That is, the first self-assembly monolayer 230 not only may cover the bottom surface BTL of the spray assembly NA but also may cover the inner surface of the 2-2 nozzle portion NZ2-2.
As shown in
A surface of the mesh layer 160 and a surface of the metal layer 140 may be coated or covered with the second self-assembly monolayer 240-1 and 240-2 described above. In this case, an entire portion of an inner surface of each mesh hole included in a mesh structure of the mesh layer 160 may be coated or covered with the second self-assembly monolayer 240.
The adhesive layer 210-2 and 210-1 described above may be disposed between the surface of the mesh layer 160 and the coated second self-assembly monolayer 240-2 and between the surface of the metal layer 140 and the coated second self-assembly monolayer 240-1. The inorganic material layer 220 described above may be arranged between the adhesive layer 210-1 and 210-2 and the second self-assembly monolayer 240-1 and 240-2 in another embodiment.
Instead, the bottom surface BTL of the spray assembly NA of the inkjet printing head according to the Comparative Example may be covered with a PFA layer. The PFA layer may cover a bottom surface of the nozzle plate 111 including PI and the like, and the silicon oxide film 112 may be disposed between the PFA layer and the bottom surface of the nozzle plate 111 included in the Comparative Example.
In addition, according to occasions, a portion of the inner surface of the ink transport path NZ disclosed in the inkjet printing device according to the Comparative Example may be covered by a layer including AlOF and/or Pt.
Generally, an ink composition including zinc is included in a large amount in a green-based ink composition. As shown in
Generally, although not as much as in the green-based ink composition, the ink composition including Zn is included in a large amount in a red-based ink composition. As shown in
Generally, an ink composition including Zn is seldom included in a blue-based ink composition. Accordingly, as shown in
As shown in
According to
In the case of the inkjet printing head, after performing a printing operation, a physical maintenance and cleaning process may be applied. A position to which the physical maintenance and cleaning is applied is the bottom surface BTL of the spray assembly NA, i.e., a position through which the ink is discharged from the inkjet printing head. In a case where the bottom surface BTL of the spray assembly NA is coated with a PFA layer in the related art, when the physical maintenance and cleaning process is applied, the coating is relatively easily peeled off compared with the first self-assembly monolayer 230. Accordingly, application of the physical maintenance and cleaning process may influence a hole of the inkjet printing head through which the ink is discharged, or may physically influence the bottom surface BTL of the spray assembly NA. This may have harmful influences on printing accuracy when spraying the ink discharged from the inkjet printing head. To prevent and minimize such harmful influences, it is desirable that a layer for protecting the bottom surface BTL of the spray assembly NA is the first self-assembly monolayer 230.
The abrasion-resistance evaluations of
Referring to
Referring to
Although
Referring to
Ratios of composition of elements included in the adhesive layer 210 included in the inkjet printing head according to an embodiment used in
The ratio of composition shown in
Referring to
In addition, adsorption ratios of Ag and Al in each of the PI layer, the first self-assembly monolayer 230, and the second self-assembly monolayer 240 are as shown in Table 3. A fluoride-based material is used for the first tail group of the first self-assembly monolayer 230 used in Table 3, the second tail group of the second self-assembly monolayer 240 includes hydrocarbon, and a length of the first carbon chain of the first self-assembly monolayer 230 is greater than a length of the second carbon chain of the second self-assembly monolayer 240.
According to Table 3, as a result of comparing adsorption ratios of Ag and Al with reference to the PI layer, it is found that an expected adsorption ratio of the first self-assembly monolayer 230 is about 4% with reference to the PI layer and an expected adsorption ratio of the second self-assembly monolayer 240 is about 72% with reference to the PI layer. That is, as a layer having a lower adsorption ratio is used, the layer does not adsorb Ag or Al in the ink, and thus, clogging in the ink transport path NZ may be reduced.
As described above, according to an embodiment, an inkjet printing head with improved durability may be implemented. However, the scope of the disclosure is not limited thereto.
It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0039048 | Mar 2023 | KR | national |
| 10-2023-0061263 | May 2023 | KR | national |
