Liquid ejection head

Abstract

The present disclosure relates to a liquid ejection head that improves the straightness of liquid droplets ejected from a nozzle. The liquid ejection head is a liquid ejection head having a nozzle that ejects liquid, the nozzle including a first nozzle portion that ejects liquid, the first nozzle portion having: a plurality of protrusion portions that protrude toward a central axis of the nozzle with an inner side surface as a reference, the inner side surface being a portion of a side surface in a direction in which liquid is ejected from the first nozzle portion, i.e., an ejection direction; and a scallop structure having a concave-convex on the inner side surface, the liquid wettability of at least one convex portion of the scallop structure in the inner side surface being higher than the liquid wettability of at least one concave portion of the scallop structure in the inner side surface.

Description

Technical Field

[0001] This disclosure relates to liquid ejection heads. Background Technology

[0002] Patent document 1 describes an irregularly shaped nozzle whose cross-sectional shape is different from that of a circle.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-66159

[0004] When tailing occurs, the droplets ejected from the nozzle separate into a main droplet and satellite droplets. If the satellite droplets land at a different position than the main droplets on the recording medium or other objects, the image quality of the recorded image or other objects will be degraded.

[0005] Therefore, as described in Patent Document 1, it has been considered to reduce the amount of satellite droplets by working on the shape of the nozzle.

[0006] However, in the technology described in Patent Document 1, the straightness of the ejected droplets may become unstable due to the position of the curved liquid surface formed before ejection.

[0007] Therefore, it is required that the suppression of satellite droplets and the straightness of ejected droplets coexist. Summary of the Invention

[0008] To solve the above technical problems, the preferred embodiment of this disclosure relates to a liquid ejector head having a nozzle for ejecting liquid. The nozzle has a first nozzle portion for ejecting liquid, the first nozzle portion having: a plurality of protrusions protruding toward the central axis of the nozzle with reference to an inner side surface, the inner side surface being a portion of the side surface along the direction of liquid ejection from the first nozzle portion, i.e., the ejection direction; and a scallop-shaped structure having concave and convex surfaces on the inner side surface, wherein the hydrophilicity of at least one protrusion of the scallop-shaped structure on the inner side surface is higher than the hydrophilicity of at least one concave surface of the scallop-shaped structure on the inner side surface. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing an example of the configuration of the liquid ejection device according to the first embodiment.

[0010] Figure 2 This is an exploded perspective view of the liquid ejector head according to the first embodiment.

[0011] Figure 3 yes Figure 2 Sectional view along line AA in the diagram.

[0012] Figure 4 This is a cross-sectional view of the nozzle in the first embodiment.

[0013] Figure 5 This is a top view of the nozzle in the first embodiment.

[0014] Figure 6 yes Figure 5 Sectional view along line AA in the diagram.

[0015] Figure 7 yes Figure 5 BB line section view.

[0016] Figure 8 This is an illustration of a nozzle with a scalloped structure omitted and a uniformly hydrophilic wall surface.

[0017] Figure 9 This is an illustration of a nozzle with a scallop-shaped structure and a uniformly hydrophilic wall surface.

[0018] Figure 10 This is an illustration of an example of a drive signal.

[0019] Figure 11 It was used Figure 10 The diagram illustrates the meniscus under the indicated drive signal.

[0020] Figure 12 This is a cross-sectional view of the nozzle in the second embodiment.

[0021] Figure 13 This is a top view of the nozzle in Variation Example 1.

[0022] Figure 14 This is a top view of the nozzle in variation example 2.

[0023] Explanation of reference numerals in the attached figures

[0024] 10…liquid container, 20…control module, 21…control unit, 30…transport mechanism, 40…moving mechanism, 41…carriage, 42…conveyor belt, 50…liquid ejection head, 51…convex portion, 51-1…first convex portion, 51-2…second convex portion, 51-3…third convex portion, 52…concave portion, 53…convex portion, 54…concave portion, 61…lyophilic film, 62…lyophilic film, 71…lyophobic film, 72…lyophobic film, 100…liquid ejection apparatus, 510…communication substrate, 520…pressure chamber substrate, 530…nozzle plate, 540…vibration absorbing body, 550…vibration plate, 560…piezoelectric element, 570…protection substrate, 580…housing, 590…wiring substrate, 600…drive circuit, C1…pressure chamber, CS1…scallop-shaped structure, CS2…scallop-shaped structure, Com…drive signal, DN…ejection direction, EE1…expansion element, EE3…vibration damping element, EM1…expansion maintaining element, ER1…contraction maintaining element, ES1…contraction element, FN…nozzle surface, HL…introduction port, LC…imaginary straight line, LV-1…imaginary straight line, LV-2…imaginary straight line, Ln1…first nozzle row, Ln2…second nozzle row, M…recording medium, ME…meniscus, N…nozzle, N-A…nozzle, N-B…nozzle, N-C…nozzle, N-X…nozzle, N-Y…nozzle, N1…first nozzle portion, N1A…first nozzle portion, N2…second nozzle portion, N2A…second nozzle portion, N2B…second nozzle portion, NS1…side surface, NS2…side surface, Na…communication flow path, OP…opening, P1…ejection pulse, PC…central axis, PR…protruding portion, PR-1…protruding portion, PR-2…protruding portion, R…reservoir, R1…flow path, R2…flow path, RE1…first region, RE2…second region, Ra…supply flow path, S…space, SD…inner side surface, SD-1…inner side surface, SD-2…inner side surface, SI…control signal, TL1…period, TL2…period, V0…intermediate potential, V1…potential, V2…potential, W1…diameter, W2…diameter. Detailed Description of Embodiments

[0025] Hereinafter, preferred embodiments according to the present disclosure will be described with reference to the accompanying drawings. It should be noted that in the drawings, the size and scale of each part are appropriately different from the actual ones, and some parts are schematically shown for ease of understanding. In addition, unless otherwise specified in the following description that limits the scope of the present disclosure, the scope of the present disclosure is not limited to these embodiments.

[0026] It should be noted that, for convenience, the following explanation will use intersecting X-axis, Y-axis, and Z-axis. Furthermore, in the following description, one direction along the X-axis is the X1 direction, and the opposite direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 and Y2 directions. The Y1 or Y2 direction is an example of the "first direction." Additionally, the opposite directions along the Z-axis are the Z1 and Z2 directions. The Z1 direction is an example of the "second direction." Hereinafter, observations along the Z1 or Z2 direction will sometimes be referred to as "top-down observations."

[0027] Here, typically, the Z-axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z-axis may not be a vertical axis. Furthermore, the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, but are not limited to this; for example, they can intersect at an angle between 80° and 100°.

[0028] 1. First Implementation Method

[0029] 1-1: Overall Composition of the Liquid Ejection Device

[0030] Figure 1 This is a schematic diagram illustrating a configuration example of the liquid ejection device 100 according to the first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects ink, an example of a "liquid," as droplets toward a recording medium M. The recording medium M is, for example, printing paper. It should be noted that the recording medium M is not limited to printing paper, and may be any printing material such as resin film or cloth.

[0031] like Figure 1 As shown, the liquid ejection device 100 includes: a liquid container 10, a control module 20, a conveying mechanism 30, a moving mechanism 40, and a plurality of liquid ejection heads 50. The control module 20 is an example of a "control unit".

[0032] Liquid container 10 stores ink. Specific examples of liquid container 10 include a box detachable from the liquid dispensing device 100, a bag-shaped ink pouch made of a flexible film, and an ink canister for refilling ink. It should be noted that the type of ink stored in liquid container 10 is arbitrary.

[0033] The control module 20 controls the operation of various elements of the liquid dispensing device 100. The control module 20 includes, for example, processing circuits such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and storage circuits such as semiconductor memory. Here, the control module 20 outputs a drive signal Com for driving the liquid dispensing head 50 and a control signal SI for controlling the drive of the liquid dispensing head 50. Through such a drive signal Com and control signal SI, the control module 20 controls the dispensing action from the liquid dispensing head 50.

[0034] In this embodiment, the control module 20 functions as the control unit 21. The control unit 21 controls the position of the meniscus ME of the first nozzle portion N1 formed in the nozzle N (described later). For example, the control unit 21 controls the operation of a mechanism that adjusts the pressure (back pressure) of the ink supplied from the liquid container 10 to the liquid ejector head 50. Thus, the position of the meniscus ME is controlled by the control unit 21.

[0035] Under the control of the control module 20, the conveying mechanism 30 conveys the recording medium M along the Y-axis.

[0036] Under the control of the control module 20, the moving mechanism 40 causes the liquid nozzle 50 to reciprocate along the X-axis. The moving mechanism 40 has a carriage 41 that houses the liquid nozzle 50 and an annular conveyor belt 42 on which the carriage 41 is fixed. It should be noted that, in addition to the liquid nozzle 50, the aforementioned liquid container 10 can also be mounted on the carriage 41.

[0037] Under the control of the control module 20, multiple liquid ejector heads 50 eject ink supplied from the liquid container 10 from multiple nozzles N onto the recording medium M. This ejection is performed in parallel with the reciprocating movement of the liquid ejector heads 50 of the conveying mechanism 30 and the moving mechanism 40 of the recording medium M, thereby forming an image caused by the ink on the surface of the recording medium M.

[0038] exist Figure 1 In the example shown, there are four liquid nozzles 50. It should be noted that the number of liquid nozzles 50 is not limited to this. Figure 1 The examples shown are arbitrary; they can be a single head, or multiple heads of three or fewer, or more than five. Furthermore, the configuration of multiple liquid nozzles 50 is not limited to... Figure 1 The examples shown are arbitrary.

[0039] 1-2: Liquid ejector head

[0040] Figure 2 This is an exploded perspective view of the liquid ejector head 50 according to the first embodiment. Figure 3 yes Figure 2 The image shows a cross-sectional view along line AA. The following describes an example of the configuration of the liquid ejector head 50.

[0041] like Figure 2 as well as Figure 3 As shown, the liquid ejector head 50 has a plurality of nozzles N that eject ink in the ejection direction DN. In this embodiment, the ejection direction DN is the Z2 direction.

[0042] The liquid ejector head 50 has a plurality of nozzles N, which are divided into a first nozzle column Ln1 and a second nozzle column Ln2 arranged at intervals from each other along the X-axis. The first nozzle column Ln1 and the second nozzle column Ln2 are each a set of a plurality of nozzles N arranged in a straight line along the Y-axis.

[0043] The liquid nozzles 50 are configured to be approximately symmetrical about each other along the X-axis. However, the positions of the plurality of nozzles N in the first nozzle row Ln1 and the plurality of nozzles N in the second nozzle row Ln2 can be either identical or different along the Y-axis. Figure 2 as well as Figure 3 The example illustrates a configuration in which multiple nozzles N of the first nozzle array Ln1 and multiple nozzles N of the second nozzle array Ln2 are positioned in a manner consistent with each other along the Y-axis.

[0044] like Figure 2 as well as Figure 3 As shown, the liquid ejector head 50 includes: a connecting substrate 510, a pressure chamber substrate 520, a nozzle plate 530, a vibration absorber 540, a vibrating plate 550, a plurality of piezoelectric elements 560, a protective substrate 570, a housing 580, and a wiring substrate 590.

[0045] The connecting substrate 510 and the pressure chamber substrate 520 are sequentially stacked along the Z1 direction to form a flow path for supplying ink to a plurality of nozzles N. In a region located further along the Z1 direction than the stack formed by the connecting substrate 510 and the pressure chamber substrate 520, a vibrating plate 550, a plurality of piezoelectric elements 560, a protective substrate 570, a housing 580, a wiring substrate 590, and a drive circuit 600 are provided. On the other hand, in a region located further along the Z2 direction than the stack, a nozzle plate 530 and a vibration absorber 540 are provided. The components of the liquid ejector head 50 are generally long, plate-shaped parts in the Y direction, joined together, for example, by an adhesive. The components of the liquid ejector head 50 will be described below.

[0046] The nozzle plate 530 is a plate-shaped component having a plurality of nozzles N respectively provided with a first nozzle row Ln1 and a second nozzle row Ln2. Each of the plurality of nozzles N is a through hole through which ink passes. Here, the surface of the nozzle plate 530 facing the Z2 direction is the nozzle surface FN. The nozzle plate 530 is manufactured, for example, by processing a silicon single-crystal substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, other known methods and materials may also be appropriately used in the manufacture of the nozzle plate 530. Furthermore, the cross-sectional shape of the nozzles N is an irregular shape different from a circle. Reference will be made later based on... Figure 4 as well as Figure 5 Describe the cross-sectional shape of nozzle N.

[0047] On the connecting substrate 510, a flow path R1, multiple supply flow paths Ra, and multiple connecting flow paths Na are respectively provided for the first nozzle array Ln1 and the second nozzle array Ln2. Flow path R1 is a flow path shared with the multiple nozzles N, and is a flow path that communicates with the multiple nozzles N and is located upstream of the nozzles N. It is composed of an elongated hole extending in the Y-axis direction when viewed from above along the Z-axis. The supply flow paths Ra and connecting flow paths Na are flow paths composed of through holes formed by each nozzle N. Each supply flow path Ra is connected to flow path R1.

[0048] The connecting substrate 510 is manufactured in the same manner as the aforementioned nozzle plate 530, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. However, other known methods and materials may also be appropriately used in the manufacture of the connecting substrate 510.

[0049] The pressure chamber substrate 520 is a plate-shaped component having multiple pressure chambers C1, referred to as cavities, respectively provided for the first nozzle array Ln1 and the second nozzle array Ln2. The multiple pressure chambers C1 are arranged along the Y-axis. Each pressure chamber C1 is an elongated space formed for each nozzle N, extending along the X-axis when viewed from above. Liquid ejected from the nozzle N fills such pressure chambers C1.

[0050] The pressure chamber substrate 520 is manufactured in the same manner as the aforementioned nozzle plate 530, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. However, other known methods and materials may also be appropriately used in the manufacture of the pressure chamber substrate 520.

[0051] Pressure chamber C1 is located between the connecting substrate 510 and the vibrating plate 550. For the first nozzle array Ln1 and the second nozzle array Ln2, multiple pressure chambers C1 are arranged in the direction along the Y-axis. Furthermore, pressure chamber C1 is connected to the connecting flow path Na and the supply flow path Ra, respectively. Therefore, pressure chamber C1 is connected to nozzle N via the connecting flow path Na and to flow path R1 via the supply flow path Ra.

[0052] More specifically, a vibrating plate 550 is disposed on the Z1-oriented surface of the pressure chamber substrate 520. The vibrating plate 550 is a plate-shaped component capable of elastic vibration, vibrated by a piezoelectric element 560. Although not shown, the vibrating plate 550 is, for example, as shown in the figure. Figure 4 As shown, the device comprises an elastic film made of silicon oxide (SiO2) and an insulating film made of zirconium oxide (ZrO2), which are sequentially stacked along the Z1 direction. The elastic film is formed, for example, by thermal oxidation of one side of a silicon single-crystal substrate. The insulating film is formed, for example, by sputtering a zirconium layer and then thermally oxidizing that layer. It should be noted that the vibrating plate 550 is not limited to the aforementioned structure consisting of a stack of elastic and insulating films; for example, it can be composed of a single layer or three or more layers.

[0053] On the Z1-oriented surface of the vibrating plate 550, multiple piezoelectric elements 560, corresponding to nozzles N, are respectively arranged for the first nozzle array Ln1 and the second nozzle array Ln2. Each piezoelectric element 560 is a passive element that deforms upon the supply of a potential corresponding to a drive signal Com, causing pressure fluctuations in the ink within the pressure chamber C1. Thus, the piezoelectric elements 560 are driven by the drive signal Com, and the volume of the pressure chamber C1 changes according to the drive of the piezoelectric elements. Each piezoelectric element 560 is elongated in the X-axis direction when viewed from above. The multiple piezoelectric elements 560 are arranged in the Y-axis direction in a manner corresponding to multiple pressure chambers C1. The piezoelectric elements 560 overlap with the pressure chambers C1 when viewed from above. The piezoelectric elements 560 apply pressure to the pressure chamber C1, which is connected to the nozzles N that eject ink.

[0054] Although not illustrated, each piezoelectric element 560 includes, for example, a first electrode, a piezoelectric body, and a second electrode, which are sequentially stacked along the Z1 direction. One of the first and second electrodes is an independent electrode separately arranged on each piezoelectric element 560, to which a drive signal Com is supplied from the control module 20. The other electrode is a strip-shaped common electrode extending continuously along the Y-axis on the multiple piezoelectric elements 560, to which a constant potential is supplied, for example. Examples of metal materials used for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu), among which one type can be used alone, or two or more types can be used in combination, such as in alloys or in layers. The piezoelectric body is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3). The piezoelectric body can be integrally disposed on the multiple piezoelectric elements 560 or independently disposed on each piezoelectric element 560.

[0055] The protective substrate 570 is a plate-shaped component disposed on the Z1-oriented surface of the vibrating plate 550, protecting the plurality of piezoelectric elements 560 and enhancing the mechanical strength of the vibrating plate 550. Here, the plurality of piezoelectric elements 560 are accommodated in the space S between the protective substrate 570 and the vibrating plate 550. The protective substrate 570 is, for example, made of resin material.

[0056] The housing 580 is a housing for storing ink supplied to multiple pressure chambers C1. The housing 580 is made of, for example, resin material. Flow paths R2 are provided in the housing 580 for the first nozzle array Ln1 and the second nozzle array Ln2, respectively. Flow paths R2 are spaces connected to the aforementioned flow paths R1, and are formed by elongated holes extending in the Y-axis direction when viewed from above along the Z-axis. Flow paths R2 communicate with nozzles N and, together with flow paths R1, function as reservoirs R for storing ink supplied to the multiple pressure chambers C1. Inlets HL for supplying ink to each reservoir R are provided on the housing 580. The ink in each reservoir R is supplied to the pressure chambers C1 via each supply flow path Ra. It should be noted that the position and number of inlets HL relative to each reservoir R are not limited to... Figure 2 as well as Figure 3 The examples are arbitrary.

[0057] The vibration absorber 540, also known as a flexible substrate, is a flexible resin film that forms the wall of the reservoir R and absorbs pressure fluctuations of the ink within the reservoir R. It should be noted that the vibration absorber 540 can also be a flexible sheet of metal. The Z1-oriented surface of the vibration absorber 540 is bonded to the connecting substrate 510 using an adhesive or similar agent.

[0058] The wiring substrate 590 is mounted on the Z1-oriented surface of the vibrating plate 550 and serves as a mounting component for electrically connecting the control module 20 to the liquid nozzle 50. The wiring substrate 590 is, for example, a flexible wiring substrate such as COF (Chip On Film), FPC (Flexible Printed Circuit), or FFC (Flexible Flat Cable). In this embodiment, a drive circuit 600 is mounted on the wiring substrate 590. Under the control of the control module 20, the drive circuit 600 switches whether to supply pulses contained in the drive signal Com output from the control module 20 to each of the plurality of piezoelectric elements 560 in the liquid nozzle 50. As described above, the wiring substrate 590 supplies the drive signal Com to drive the piezoelectric elements 560. It should be noted that the wiring substrate 590 can also be a rigid substrate. In this case, the drive circuit 600 is mounted on the rigid substrate or on a flexible substrate connected to the rigid substrate.

[0059] 1-3: Nozzle

[0060] Figure 4 This is a cross-sectional view of nozzle N in the first embodiment. Figure 5 This is a top view of nozzle N in the first embodiment. (Example) Figure 4 as well as Figure 5 As shown, nozzle N includes a first nozzle section N1 and a second nozzle section N2. They are arranged facing the ejection direction DN in the order of second nozzle section N2 and first nozzle section N1. In the illustrated example, the first nozzle section N1 and the second nozzle section N2 are adjacent to each other. It should be noted that... Figure 4 yes Figure 5 The CC line section view.

[0061] The first nozzle section N1 is an opening in the nozzle surface FN of the nozzle plate 530 that ejects ink. The first nozzle section N1 is divided by a side surface NS1 along the ejection direction DN, which is the direction from which liquid is ejected from the first nozzle section N1. Figure 5 As shown, the cross-sectional shape of the first nozzle portion N1 is such that portions of two circles overlap each other. Specifically, inner side surfaces SD-1 and SD-2 and protrusions PR-1 and PR-2 are provided on the side surface NS1 of the first nozzle portion N1. Hereinafter, without distinguishing between the inner side surfaces SD-1 and SD-2, the inner side surfaces SD-1 and SD-2 will be referred to as inner side surfaces SD. Without distinguishing between the protrusions PR-1 and PR-2, the protrusions PR-1 and PR-2 will be referred to as protrusions PR.

[0062] Multiple (in this embodiment, a pair) protrusions PR, namely protrusions PR-1 and PR-2, are protrusions that project toward the central axis PC of the nozzle N with reference to the inner side surface SD, and extend along the ejection direction DN. In the illustrated example, each protrusion PR extends along the entire area of ​​the first nozzle portion N1 in the ejection direction DN.

[0063] In the first nozzle section N1, which has a shape with a pair of protrusions PR, when viewed from above, two tangent lines can be drawn that intersect the outer periphery of the first nozzle section N1 at two points. If one of these tangent lines is designated as a virtual line LV-1, and the other as a virtual line LV-2, and the two points where the virtual line LV-1 intersects the outer periphery of the first nozzle section N1 are designated as points PT-1, and the two points where the virtual line LV-2 intersects the outer periphery of the first nozzle section N1 are designated as points PT-2, then protrusion PR-1 is the portion between the two points PT-1 on the side NS1, and protrusion PR-2 is the portion between the two points PT-2 on the side NS1.

[0064] It should be noted that the virtual line LV-2 is a different line from the virtual line LV-1. In the example shown, the virtual lines LV-1 and LV-2 are parallel to each other.

[0065] When viewed from above, the first nozzle section N1 is divided into a first region RE1 and a second region RE2 by means of the protrusions PR-1 and PR-2. In the illustrated example, when viewed from above, the first nozzle section N1 is divided into the first region RE1 and the second region RE2 by the virtual straight line LC connecting the front ends of the protrusions PR-1 and PR-2.

[0066] Thus, when viewed from above, the first nozzle section N1 is divided into a first region RE1 and a second region RE2 by a pair of protrusions PR. Here, the first region RE1 and the second region RE2 are respectively shaped as a semicircle or a circle. Because each region, divided by the protrusions PR, is semicircular or circular, the portion of the droplet ejected from each region opposite to the protrusions PR has a stable shape, while the side with the protrusions PR becomes unstable. Therefore, the liquid ejected from each region clumps together on the protrusion PR side, making it difficult for the droplet to break apart.

[0067] The inner side SD is part of the side NS1. Here, in top view, the inner side SD-1 is the portion between points PT-1 and PT-2 on the first region RE1 side of the side NS1. In top view, the inner side SD-2 is the portion between points PT-1 and PT-2 on the second region RE2 side of the side NS1.

[0068] Furthermore, a scallop-shaped structure CS1 with irregularities is provided on the side NS1 of the first nozzle portion N1. That is, the first nozzle portion N1 has a scallop-shaped structure CS1 with irregularities on the side NS1. In the illustrated example, the scallop-shaped structure CS1 is provided on both the inner side SD and the protrusion PR.

[0069] Here, the convex and concave surfaces of the scallop-shaped structure CS1 in the protrusion PR are connected to the convex and concave surfaces of the scallop-shaped structure CS1 in the inner side surface SD. That is, scallop-shaped structures CS1 are provided on both the protrusion PR and the inner side surface SD. As a result, the positional deviation of the meniscus ME caused by the deviation between the convex and concave surfaces of the scallop-shaped structure CS1 in the protrusion PR and the inner side surface SD can be suppressed.

[0070] The scallop-shaped structure CS1 is formed, for example, by deep groove etching such as box machining. Therefore, the nozzle N is preferably disposed on the nozzle plate 530 made of silicon. Thus, the scallop-shaped structure CS1 can be formed on the nozzle N by box machining or the like.

[0071] The scallop-shaped structure CS1 has multiple protrusions 51 and multiple recesses 52.

[0072] The plurality of protrusions 51 are protrusions extending circumferentially along the first nozzle portion N1. The plurality of recesses 52 are grooves extending circumferentially along the first nozzle portion N1. The plurality of protrusions 51 and the plurality of recesses 52 are arranged in an alternating manner along the axial direction of the first nozzle portion N1. Here, a protrusion 51 is provided between two adjacent recesses 52. In other words, a recess 52 is provided between two adjacent protrusions 51.

[0073] The depth of the recess 52 of the scallop-shaped structure CS1 in the protrusion PR is preferably shallower than the depth of the recess 52 of the scallop-shaped structure CS1 in the inner side SD. This allows the meniscus ME to be easily maintained by the protrusion PR. Consequently, the straight-line propagation of the droplets ejected from the nozzle N is further stabilized.

[0074] It should be noted that the protruding PR may also lack the scallop-shaped structure CS1. That is, multiple protruding PRs extending along the ejection direction DN may not have the scallop-shaped structure CS1. In this case, the possibility of reduced discharge of sediments and foreign matter due to poor liquid flow between the protruding PRs can be reduced.

[0075] At least one of the plurality of protrusions 51 is provided with a hydrophilic membrane 61. In this embodiment, the hydrophilic membrane 61 is provided on each of the plurality of protrusions 51 except for the protrusion 51 located at the position closest to the opening OP of the first nozzle portion N1, i.e., the first protrusion 51-1 described later.

[0076] Here, in the plurality of protrusions PR, a hydrophilic membrane 61 is provided at a position where the protrusions PR face each other. In this way, by providing the hydrophilic membrane 61 at the position where the protrusions PR face each other face each other, the position of the meniscus ME among the plurality of protrusions PR can be stabilized.

[0077] Lipophilicity refers to a contact angle with pure water of less than 70°. The constituent material of the lipophilic membrane 61 is not particularly limited as long as it exhibits lipophilicity; examples include monomolecular membranes with terminal hydroxyl or carboxyl groups, and PPSi (polysiloxane). It should be noted that the lipophilic membrane 61 is preferably made of a material that exhibits lipophilicity to the ink. For example, it is preferable that the contact angle between the ink with a surface tension of approximately 25 mN / m and the lipophilic membrane 61 is less than 40°. It should also be noted that a protective layer made of tantalum oxide or similar material, or an adhesive layer such as a silicon plasma polymer film, can be provided between the lipophilic membrane 61 and the surface of the nozzle plate 530.

[0078] In the illustrated example, a hydrophilic film 61 is provided over the entire area of ​​the side NS1. However, in the area of ​​the side NS1 other than near the tip of the protrusion 51, the hydrophilic film 61 is covered by a hydrophobic film 71. Therefore, the hydrophilic film 61 is only exposed into the first nozzle portion N1 near the tip of the protrusion 51. As a result, the hydrophilicity of the protrusion 51 is higher than that of the recess 52 adjacent to the protrusion 51 in the ejection direction DN. In other words, the hydrophobicity of the protrusion 51 is lower than that of the recess 52 adjacent to the protrusion 51 in the ejection direction DN. As a result, the meniscus ME is easily formed by the protrusion 51. In other words, the meniscus ME is difficult to form in the recess 52.

[0079] Thus, the hydrophilicity of the protrusion 51 of the scallop-shaped structure CS1 in the inner side SD is higher than that of the concave portion 52 of the scallop-shaped structure CS1 in the inner side SD.

[0080] The term "liquid repellency" refers to a contact angle of 100° or more with pure water. The constituent material of the liquid repellent film 71 is not particularly limited as long as it exhibits liquid repellency; examples include fluorinated resins such as PFPE (perfluoropolyether) and monolayers with fluorine-terminated groups. It should be noted that the liquid repellent film 71 is preferably made of a material that exhibits liquid repellency to ink. For example, the contact angle between an ink with a surface tension of approximately 25 mN / m and the liquid repellent film 71 is preferably 60° or more.

[0081] In this embodiment, a hydrophobic film 71 with hydrophobic properties is provided in each recess 52. As a result, the meniscus ME is difficult to form in the recess 52, and therefore the meniscus ME is relatively easy to form from the protrusion 51. Consequently, the position of the meniscus ME can be made more stable.

[0082] In the illustrated example, a hydrophobic film 72 is provided on the nozzle surface FN of the nozzle plate 530. This suppresses ink adhesion to that surface. The hydrophobic film 72, like the hydrophobic film 71, is made of, for example, a fluorinated resin material. It should be noted that the hydrophobic film 72 can be formed together with the hydrophobic film 71, or it can be formed separately from the hydrophobic film 71.

[0083] Here, a hydrophobic film 72 is provided on the surface of the protrusion PR facing the ejection direction DN. Therefore, the surface of the protrusion PR facing the ejection direction DN is hydrophobic, thus preventing foreign matter such as dust or paper dust from adhering to this surface. It should be noted that the hydrophobic film 72 may be provided only on the portion of the protrusion PR in the nozzle surface FN, or only around the opening OP.

[0084] It should be noted that the hydrophobic film 72 is preferably formed by connecting the hydrophobic film 71. By providing the hydrophobic films 71 and 72 without gaps at the edge of the opening OP of the first nozzle section N1, it is possible to suppress the adhesion of droplets and mist to the edge and to appropriately suppress the spraying curvature of the ejected liquid.

[0085] It should be noted that, as a configuration that makes the hydrophilicity of the protrusion 51 higher than that of the concave portion 52, examples include a configuration in which a hydrophilic membrane 61 is provided on the protrusion 51 and a hydrophobic membrane 71 is provided on the concave portion 52, a configuration in which a hydrophilic membrane 61 is provided on the protrusion 51 and a configuration in which a hydrophilic membrane 61 is not provided on the concave portion 52, and a hydrophobic membrane 71.

[0086] The configuration of providing a hydrophilic film 61 on the protrusion 51 and a hydrophobic film 71 on the recess 52 is achieved, for example, by sequentially forming the hydrophilic film 61 and the hydrophobic film 71 on the side of the scallop-shaped structure CS1, and then removing the hydrophobic film 71 by plasma treatment with high penetration, thereby exposing the hydrophilic film 61 on the protrusion 51. It should be noted that the manufacturing method is not limited to this example and is arbitrary. Furthermore, there are no particular limitations on the film-forming methods for the hydrophilic film 61 and the hydrophobic film 71, and known film-forming methods can be used.

[0087] It should be noted that the hydrophilic film 61 only needs to be provided in at least one protrusion 51 so as to be exposed inside the nozzle N, and it only needs to be provided in the protrusion 51 where a meniscus ME is formed. In addition, the hydrophilic film 61 may be provided only on the protrusion 51, or it may not be provided on the protrusion 51. If it is in a state where it is covered by a film with lower hydrophilicity than the hydrophilic film 61 or a hydrophobic film 71 in the recess 52, it may also be provided on the recess 52.

[0088] The hydrophobic film 71 may be provided in at least one recess 52 in such a way that it is exposed inside the nozzle N. For example, the hydrophobic film 71 may be formed on the protrusion 51 on which the meniscus ME is formed, and on the recess 52 adjacent to the protrusion 51 on which the meniscus ME is formed, or the hydrophobic film 71 may not be formed on the recess 52 away from the protrusion 51 on which the meniscus ME is formed.

[0089] The second nozzle section N2 is an orifice located between the pressure chamber C1 and the first nozzle section N1. The diameter W2 of the second nozzle section N2 is larger than the diameter W1 of the first nozzle section N1. Thus, by having the second nozzle section N2, liquid can be easily supplied to and displaced from the first nozzle section N1. Furthermore, since the second nozzle section N2 exists in addition to the scallop-shaped structure CS1 of the first nozzle section N1, the supply and displacement of liquid to the first nozzle section N1 becomes easier, and the accumulation of foreign matter generated in the first nozzle section N1 in the recess 52 of the scallop-shaped structure CS1 can be further suppressed. As a result, the position of the meniscus ME in the first nozzle section N1 can be stabilized.

[0090] A scallop-shaped structure CS2 with irregularities is provided on the side surface NS2 of the second nozzle section N2. That is, the second nozzle section N2 has a scallop-shaped structure CS2 with irregularities on the side surface NS2. The side surface NS2 is a surface along the ejection direction DN. The scallop-shaped structure CS2 is formed, for example, by deep groove etching during box machining.

[0091] The scallop-shaped structure CS2 has multiple protrusions 53 and multiple recesses 54. The multiple protrusions 53 are annular protrusions extending circumferentially along the second nozzle portion N2. The multiple recesses 54 are annular grooves extending circumferentially along the second nozzle portion N2. The multiple protrusions 53 and multiple recesses 54 are arranged alternately along the axial direction of the second nozzle portion N2. Here, a protrusion 53 is provided between two adjacent recesses 54. In other words, a recess 54 is provided between two adjacent protrusions 53.

[0092] Each protrusion 53 is provided with a hydrophilic film 62. Therefore, by using a drive signal Com that introduces a waveform similar to the meniscus ME, even when the meniscus ME in the region defined by the protrusion PR moves to the second nozzle N2, the hydrophilic nature of the protrusion 53 of the second nozzle N2 prevents air bubbles from entering or accumulating in the second nozzle N2. It should be noted that the hydrophilic film 62 may be provided in at least one of the protrusions 53.

[0093] In this embodiment, the hydrophilic membrane 62 is provided over the entire area of ​​the side NS2. Therefore, the hydrophilic membrane 62 is also provided in each recess 54. This further suppresses the accumulation of foreign matter or air bubbles in the second nozzle portion N2. It should be noted that the hydrophilic membrane 62 only needs to be provided in at least one of the plurality of recesses 54.

[0094] As for the constituent material of the hydrophilic membrane 62, there are no particular limitations as long as it can achieve hydrophilicity. Similar to the hydrophilic membrane 61, examples include monomolecular membranes with terminal hydroxyl or carboxyl groups, and PPSi (polysiloxane). It should be noted that the hydrophilic membrane 62 can be formed together with the hydrophilic membrane 61, or it can be formed separately from the hydrophilic membrane 61. It should also be noted that a protective layer made of tantalum oxide or similar material, or a bonding layer such as a silicon plasma polymer film, can be provided between the hydrophilic membrane 62 and the surface of the nozzle plate 530.

[0095] Figure 6 as well as Figure 7 This is a schematic diagram of the first nozzle section N1 in the first embodiment. Figure 6 yes Figure 5 The sectional view along line AA schematically shows the section at the inner side surface SD. Figure 7 yes Figure 5 The BB-line sectional view schematically shows the cross-section at the protrusion PR. Figure 6 as well as Figure 7 For ease of explanation, only the portion of the hydrophilic membrane 61 exposed within the first nozzle portion N1 is shown schematically, and the illustrations of the hydrophobic membranes 71 and 72 are omitted.

[0096] like Figure 6 as well as Figure 7 As shown, the plurality of protrusions 51 include a first protrusion 51-1, a second protrusion 51-2, and a third protrusion 51-3.

[0097] The first protrusion 51-1 is the protrusion 51 located closest to the opening OP of the first nozzle portion N1 among the plurality of protrusions 51. The second protrusion 51-2 is one of the plurality of protrusions 51. In the illustrated example, the second protrusion 51-2 is the protrusion 51 adjacent to the first protrusion 51-1. The third protrusion 51-3 is the protrusion 51 located further away from the opening OP of the first nozzle portion N1 than the second protrusion 51-2 among the plurality of protrusions. In the illustrated example, the third protrusion 51-3 is the protrusion 51 adjacent to the second protrusion 51-2. It should be noted that the second protrusion 51-2 may also be a protrusion 51 other than the protrusion 51 adjacent to the first protrusion 51-1. Furthermore, the third protrusion 51-3 can be any protrusion 51 located further away from the opening of the first nozzle portion N1 than the second protrusion 51-2, or it can be any protrusion 51 other than the protrusion 51 adjacent to the second protrusion 51-2.

[0098] In the liquid ejector head 50, the presence of the protrusion PR allows for slitting of the droplets ejected from the nozzle N or alteration of the droplet velocity. This reduces the amount of satellite droplets. Furthermore, by providing a scallop-shaped structure CS1 on the inner side SD, the position of the meniscus ME can be structurally stabilized compared to a configuration without the scallop-shaped structure CS1. Moreover, since the protrusion 51 of the scallop-shaped structure CS1 has higher hydrophilicity than the concave portion 52, the meniscus ME is more easily formed on the protrusion 51 than the concave portion 52, thus further stabilizing the position of the meniscus ME. Therefore, even when slitting of the droplets ejected from the nozzle N, instability of the droplets ejected from the nozzle N can be suppressed, resulting in improved straight-line propagation of the droplets ejected from the nozzle N.

[0099] In addition, such as Figure 6 As shown, by providing a hydrophilic membrane 61 on the protrusion 51 of the scallop-shaped structure CS1 in the inner side SD, the position of the meniscus ME in the first nozzle section N1 can be more stabilized compared to a configuration without the hydrophilic membrane 61. As a result, the straightness of the droplets ejected from the nozzle N can be further improved.

[0100] Furthermore, by forming a hydrophobic film with hydrophobic properties on the recess 52 of the scallop-shaped structure CS1 in the inner side SD, the hydrophilicity of the protrusion 51 can be relatively improved. As a result, the position of the meniscus ME in the first nozzle portion N1 can be more stabilized through the protrusion 51.

[0101] In addition, such as Figure 7 As shown, by having a scallop-shaped structure CS1 in multiple protrusions PR, the flow rate of ink flowing between the protrusions PR can be slowed down. As a result, since it is easy to add gaps in the droplets ejected from the nozzle N, the amount of satellite droplets can be appropriately reduced.

[0102] exist Figure 6 as well as Figure 7 In the diagram, the meniscus ME formed in the second convex portion 51-2 is represented by a solid line, and the meniscus ME formed in the third convex portion 51-3 is represented by a double-dotted line.

[0103] In this embodiment, the first protrusion 51-1 divides the opening OP, and no hydrophilic membrane 61 is provided on the first protrusion 51-1. Therefore, it is difficult for the meniscus ME to form on the first protrusion 51-1. As a result, leakage or adhesion of liquid to the area around the opening of the first nozzle portion N1 can be suppressed.

[0104] The control unit 21 changes the position of the meniscus ME corresponding to the positions of the plurality of protrusions 51. Therefore, when adjusting the natural vibration period of the liquid near the nozzle N, the amount of liquid filling the nozzle N changes due to the control of back pressure. Thus, by reducing the mass of liquid within the nozzle N, the natural vibration period can be shortened. Furthermore, when adjusting the ejection rate or ejection speed of the liquid from the nozzle N, the natural vibration period changes due to the control of back pressure. Therefore, the optimal length of the duration of the terminal potential of the expansion element in the drive signal changes, allowing control of the mass of liquid within the nozzle N or the ejection speed. Moreover, when adjusting the ejection characteristics caused by manufacturing deviations in the length of the nozzle N, the amount of ink filling the nozzle N changes due to the control of back pressure, thus effectively controlling the nozzle length.

[0105] The control unit 21 is capable of executing a first mode and a second mode. The first mode is a mode where the back pressure of the liquid at the nozzle N is a first back pressure. The second mode is a mode where the back pressure of the liquid at the nozzle N is a second back pressure, which is higher than the first back pressure. Thus, the liquid ejector head 50 has both the first mode and the second mode.

[0106] In the first mode, a meniscus ME is formed on the second protrusion 51-2. In the second mode, a meniscus ME is formed on the third protrusion 51-3. Therefore, if it is desired to reduce the amount of liquid ejected from the nozzle N, the second mode allows the meniscus ME to be positioned closer to the second nozzle section N2. Conversely, if it is desired to increase the amount of liquid ejected from the nozzle N, the first mode allows the meniscus ME to be positioned on the opening OP side. Here, since the side with higher back pressure is more likely to supply liquid to the nozzle N, stability is improved. For example, if it is desired to increase the ejection frequency of liquid from the nozzle N in a high-speed mode, the second mode allows the meniscus ME to be positioned on the second nozzle section N2 side. Conversely, if it is desired to reduce the ejection frequency of liquid from the nozzle N compared to a normal printing mode, the first mode allows the meniscus ME to be positioned on the opening OP side. Furthermore, as another example, during the printing mode of a serial printer when the carriage 41 is moved, by switching to the second mode and positioning the meniscus ME on the side of the second nozzle N2, liquid leakage can be reduced. On the other hand, during the maintenance mode of a serial printer when the carriage 41 is stopped, by switching to the first mode and positioning the meniscus ME on the side of the opening OP, maintenance can be performed effectively.

[0107] Figure 8 This is an illustration of a nozzle NX that omits the scallop-shaped structure CS1 and has uniform hydrophilicity on its wall surface. Figure 9 This is an illustration of a nozzle NY that has a scallop-shaped structure CS1 and uniform hydrophilicity on its wall surface.

[0108] In nozzle NX, the position and orientation of the meniscus ME are unstable. Because the wall of nozzle NX lacks the scalloped structure CS1 and is uniformly hydrophilic, the surface energy difference of the wall is small. Therefore, the position of the meniscus ME is not energy-stable, resulting in instability in its position and orientation. Furthermore, due to this instability, the deviation of the natural vibration period of the liquid near nozzle NX becomes larger.

[0109] In nozzle NY, compared to nozzle NX, the scallop-shaped structure CS1 provides a more stable position and orientation of the meniscus ME. However, due to the uniform hydrophilicity of the wall surface, the position and orientation of the meniscus ME are prone to change within the recess 52.

[0110] In contrast, in the aforementioned nozzle N, by providing a hydrophilic film 61 on the protrusion 51 of the scallop-shaped structure CS1, the meniscus ME is more easily and structurally stable to form on the protrusion 51 than the concave portion 52, thus making the position and orientation of the meniscus ME more stable.

[0111] Figure 10 This is an illustration of an example of the drive signal Com. The drive signal Com is as follows: Figure 10 As shown, this includes the ejection pulse P1.

[0112] The ejection pulse P1 is a pulse used to eject ink as droplets from nozzle N. The ejection pulse P1 causes pressure fluctuations in the ink within pressure chamber C1 by supplying it to piezoelectric element 560, thereby ejecting ink from nozzle N. Figure 8 In the example shown, the ejected pulse P1 sequentially includes an expansion element EE1, an expansion maintenance element EM1, a contraction element ES1, a contraction maintenance element ER1, and a damping element EE3.

[0113] The expansion element EE1 is a potential element that changes its potential from an intermediate potential V0 to a potential V1 to reduce the pressure inside the pressure chamber C1. That is, the expansion element EE1 causes the pressure chamber C1 to expand, introducing liquid into the pressure chamber C1 from the first nozzle section N1 and the supply flow path Ra. The expansion maintenance element EM1 is a potential element connected to the expansion element EE1 and maintaining the potential V1 during TL1. The contraction element ES1 is connected to the expansion maintenance element EM1 and is a potential element that changes its potential from V1 to a predetermined terminal potential by increasing the pressure inside the pressure chamber C1. The contraction maintenance element ER1 is located after the contraction element ES1 and is a potential element that maintains a potential V2 above the terminal potential of the contraction element ES1 during TL2. That is, the contraction element ES1 causes the pressure chamber C1 to contract, causing liquid to be ejected from the first nozzle section N1. The damping element EE3 is a potential element that reduces the pressure in the pressure chamber C1 by changing the terminal potential of the contraction sustaining element ER1 to the intermediate potential V0. When the contraction sustaining element ER1 is supplied to the piezoelectric element 560, it dampens the pressure vibration generated in the pressure chamber C1.

[0114] Figure 11 Is using Figure 10 The diagram illustrates the meniscus ME when the drive signal Com is shown. In this case, as... Figure 11 As shown by the double-dotted line, after the meniscus ME is introduced into the pressure chamber C1 side by the expansion element EE1, as... Figure 11 As shown by the solid line, the liquid is displaced by the contraction element ES1 in a manner that causes the liquid to be ejected from the first nozzle part N1.

[0115] Thus, especially when liquid is ejected by providing a drive signal Com that generates the waveform of the ejected liquid after it is introduced into the nozzle N, the position of the meniscus ME is stabilized, thereby suppressing the bending of the ejected liquid from the nozzle N. In particular, in the configuration with protrusions PR, when the position of the meniscus ME is different in each region distinguished by the protrusions PR, it is possible to suppress the droplets from falling in a separated state or to suppress the reduction of the droplets' straightness.

[0116] 2. Second Implementation Method

[0117] The second embodiment of this disclosure will now be described. For elements that function and operate the same as in the first embodiment as in the embodiments illustrated below, the reference numerals used in the description of the first embodiment will be used, and detailed descriptions will be omitted where appropriate.

[0118] Figure 12 This is a cross-sectional view of the nozzle NA in the second embodiment. The nozzle NA is constructed in the same way as the nozzle N in the first embodiment, except that it has a second nozzle portion N2A instead of the second nozzle portion N2 in the first embodiment.

[0119] The second nozzle section N2A has a tapered shape that decreases in diameter towards the first nozzle section N1. Therefore, even when a large stretching waveform is required to generate a high ejection volume, air bubbles can be prevented from being entrained in the nozzle N.

[0120] The second nozzle section N2A has a scallop-shaped structure CS2 with irregularities. Each protrusion 53 in the scallop-shaped structure CS2 of the second nozzle section N2A is provided with a hydrophilic membrane 62. This further suppresses the accumulation of foreign matter or air bubbles in the second nozzle section N2.

[0121] According to the third embodiment described above, by stabilizing the position of the curved surface ME formed within the nozzle NA, the straightness of the droplets ejected from the nozzle NA can be improved.

[0122] 3. Variations

[0123] The methods illustrated above can be modified in various ways. Specific modifications applicable to the aforementioned methods are shown below. Methods selected from the following examples can be appropriately combined within a non-conflicting scope.

[0124] 3-1: Variation Example 1

[0125] Figure 13 This is a top view of nozzle NB in ​​variation example 1. (Example:) Figure 13As shown, the cross-sectional shape of the first nozzle section N1 of the nozzle NB is a shape connecting two circles. In this first nozzle section N1, inner side surfaces SD-1 and SD-2 and protrusions PR-1 and PR-2 are also provided on the side surface NS1. Furthermore, when the first nozzle section N1 of Modified Example 1 is divided into a first region RE1 and a second region RE2 by a pair of protrusions PR when viewed from above, the first region RE1 and the second region RE2 are respectively shaped as a semicircle or a circle.

[0126] 3-2: Variation Example 2

[0127] Figure 14 This is a top view of nozzle NC in variation example 2. (Example:) Figure 14 As shown, the cross-sectional shape of the first nozzle portion N1 of the nozzle NC is such that the width of a circle is locally narrowed in one direction. In this first nozzle portion N1, inner side surfaces SD-1 and SD-2 and protrusions PR-1 and PR-2 are also provided on the side surface NS1. Furthermore, in modified example 2, when the first nozzle portion N1 is divided into a first region RE1 and a second region RE2 by a pair of protrusions PR, the first region RE1 and the second region RE2 are respectively shaped along a semicircle or a circle.

[0128] 3-3: Variation Example 3

[0129] The number of protrusions PR is not limited to two, but can also be three or more. For example, the cross-sectional shape of the first nozzle part N1 can also be trilobal, quadrilobal, star-shaped, etc.

[0130] 3-4: Variation Example 4

[0131] In the foregoing embodiments, a nozzle N is illustrated by having two parts with different diameters, but this is not a limitation. The nozzle N may consist only of a first nozzle portion of a certain width or a cone shape, or the nozzle N may have three or more parts with different diameters. That is, in the foregoing embodiments, a nozzle N is illustrated by having second nozzle portions N2 and N2B, but this is not a limitation. The second nozzle portions N2 and N2B may be omitted, and a third portion with a diameter different from that of the first nozzle portions N1 and N1A and the second nozzle portions N2 and N2B may be added.

[0132] 3-5: Variation Example 5

[0133] In the aforementioned embodiments, although a scallop-shaped structure CS2 is provided on the side NS2 of the second nozzle portions N2 and N2B, it is not limited to this method, and the scallop-shaped structure CS2 may be omitted.

[0134] 3-6: Variation Example 6

[0135] In the aforementioned embodiment, a first protrusion 51-1 is provided in the first nozzle portion N1, but this is not a limitation, and the first protrusion 51-1 may be omitted. That is, in the ejection direction DN, it may also be configured such that there is a recess instead of a protrusion between the opening OP and the second protrusion 52-2.

[0136] Therefore, since the second protrusion 51-2 is located further inside the opening OP of the first nozzle part N1, even if a meniscus ME is formed on the second protrusion 51-2, it is possible to prevent liquid from leaking out or adhering to the area around the opening of the first nozzle part N1.

[0137] Furthermore, in this method, it is preferable to form a hydrophobic film 71 provided in the recess 52 facing the opening OP and a hydrophobic film 72 provided on the nozzle surface FN connected together. Therefore, by providing the hydrophobic films 71 and 72 without gaps at the edge of the opening OP of the first nozzle portion N1, it is possible to suppress the adhesion of droplets and mist to the edge and to appropriately suppress the jetting curvature of the ejected liquid.

[0138] 3-7: Variation Example 7

[0139] Among the foregoing embodiments, a serial liquid ejection device 100 is exemplified in which the carriage 541 carrying the liquid ejection head 50 reciprocates, but this disclosure is also applicable to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the recording medium M.

[0140] 3-8: Variation Example 8

[0141] The liquid ejection apparatus 100 illustrated in the foregoing embodiments can be used not only in printing equipment but also in various other equipment such as fax machines and copiers; the application of this disclosure is not particularly limited. However, the application of the liquid ejection apparatus is not limited to printing. For example, a liquid ejection apparatus that ejects a solution of color material is used as an apparatus for manufacturing color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection apparatus that ejects a solution of conductive material is used as an apparatus for manufacturing wiring and electrodes for forming wiring substrates. In addition, a liquid ejection apparatus that ejects a solution of organic matter related to living organisms is used, for example, as an apparatus for manufacturing biochips.

Claims

1. A liquid ejector head, characterized in that, The liquid ejector head has a nozzle for ejecting liquid. The nozzle has a first nozzle portion for ejecting liquid. The first nozzle portion has: Multiple protrusions protrude toward the central axis of the nozzle with reference to the inner side surface, which is a portion of the side surface along the direction in which liquid is ejected from the first nozzle portion, i.e., the ejection direction. as well as The scallop-shaped structure has irregularities on its inner side. The hydrophilicity of at least one protrusion of the scallop-shaped structure on the inner side surface is higher than that of at least one concave portion of the scallop-shaped structure on the inner side surface.

2. The liquid ejector head according to claim 1, characterized in that, At least one protrusion of the scallop-shaped structure on the inner side is provided with a hydrophilic membrane.

3. The liquid ejector head according to claim 1, characterized in that, At least one recess of the scallop-shaped structure in the inner side surface is provided with a hydrophobic membrane.

4. The liquid ejector head according to any one of claims 1 to 3, characterized in that, The plurality of protrusions extend along the ejection direction and have a scallop-shaped structure including concave and convex features.

5. The liquid ejector head according to claim 4, characterized in that, The convex and concave shapes of the scallop-shaped structure in the protrusion are connected to the convex and concave shapes of the scallop-shaped structure in the inner side surface.

6. The liquid ejector head according to claim 5, characterized in that, The depth of the recessed portion of the scallop-shaped structure in the protrusion is shallower than the depth of the recessed portion of the scallop-shaped structure in the inner side surface.

7. The liquid ejector head according to any one of claims 1 to 3, characterized in that, The plurality of protrusions extend along the ejection direction and do not have a scallop-shaped structure.

8. The liquid ejector head according to claim 7, characterized in that, Among the plurality of protrusions, a hydrophilic membrane with hydrophilic properties is provided at positions where the protrusions are opposite to each other.

9. The liquid ejector head according to any one of claims 1 to 3, characterized in that, A hydrophobic film with hydrophobic properties is provided on the surface of the protrusion facing the ejection direction.

10. The liquid ejector head according to claim 1, characterized in that, The nozzle is disposed on a nozzle plate made of silicon.

11. The liquid ejector head according to claim 1, characterized in that, The liquid ejector head has a pressure chamber, and the liquid ejected from the first nozzle portion fills the pressure chamber. The nozzle has a second nozzle portion located between the pressure chamber and the first nozzle portion, and the diameter of the second nozzle portion is larger than the diameter of the first nozzle portion.

12. The liquid ejector head according to claim 11, characterized in that, The second nozzle portion has a scallop-shaped structure including concave and convex features. At least one protrusion of the scallop-shaped structure in the second nozzle portion is provided with a hydrophilic membrane.

13. The liquid ejector head according to claim 1, characterized in that, The liquid ejector head has: Piezoelectric elements are driven by a driving signal; and A pressure chamber is filled with liquid ejected from the first nozzle, and the volume of the pressure chamber changes according to the actuation of the piezoelectric element. The driving signal includes: The element that expands the pressure chamber to introduce liquid from the first nozzle into the pressure chamber side; and The element that causes the pressure chamber to contract, thereby causing liquid to be ejected from the first nozzle.

14. The liquid ejector head according to claim 1, characterized in that, The plurality of protrusions are a pair of protrusions that project toward the central axis of the first nozzle portion, with the inner side surface as a reference. When viewed from above, the first nozzle portion is divided into a first region and a second region by the pair of protrusions. The first region and the second region are respectively shaped like a semicircle or a circle.

15. The liquid ejector head according to any one of claims 1 to 3, characterized in that, Before the liquid is ejected from the first nozzle portion, a meniscus of the liquid is formed in at least one portion of the plurality of protrusions. The wettability of at least one portion of the plurality of protrusions is higher than the wettability of at least one portion of the plurality of recesses adjacent to at least one of the plurality of protrusions.

16. A liquid ejector head, characterized in that, The liquid ejector head is equipped with a nozzle for ejecting liquid. The nozzle includes a first nozzle portion for ejecting the liquid, the first nozzle portion comprising: Multiple protrusions protrude toward the central axis of the nozzle relative to the inner side surface, which is a portion of the side surface along the direction in which the liquid is ejected from the first nozzle portion, i.e., the ejection direction; as well as The scallop-shaped structure has multiple protrusions and multiple recesses on its inner side. Before the liquid is ejected from the first nozzle portion, a meniscus of the liquid is formed on the first of the plurality of protrusions. The wettability of the first convex portion is higher than that of the concave portion adjacent to the first convex portion.

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