Nozzle plate, liquid droplet ejection head, and liquid droplet ejection apparatus

Abstract

The nozzle plate (110) is provided with a plurality of nozzle flow paths (111). The nozzle flow path (111) is provided with: a nozzle tapered section (1112) in which the flow path area gradually increases from a first surface (Ba) toward a second surface (Bb) facing the first surface (Ba); and a linear communication section (1113) which is provided continuously from the second surface (Bb) and which is substantially parallel to the pair of opposing surfaces (1113a). In the second surface (Bb), the length of the linear communication section (1113) in the first direction along the pair of opposing surfaces (1113a) is longer than the length of the linear communication section in the second direction orthogonal to the first direction. The nozzle tapered section (1112) is provided with a pair of stepped surfaces (1112b) along the second direction, the stepped surfaces (1112b) forming steps on the tapered surface (1112a) with the nozzle opening (N) therebetween. The stepped surface (1112b) is a drooping surface or an inclined surface which forms a smaller angle with an axis parallel to the nozzle center axis than the tapered surface (1112a).

Description

Technical Field

[0001] The present invention relates to a nozzle plate, a liquid drop ejection head and a liquid drop ejection device. Background Art

[0002] Conventionally, as shown in Patent Document 1, a nozzle channel having nozzle openings is formed on a nozzle plate of a droplet ejection head of a droplet ejection device. Then, liquid such as ink passes through the nozzle channel and is ejected from the nozzle openings as droplets.

[0003] Patent Document 1: Japanese Patent No. 5519263

[0004] However, in order to form a high-resolution image, it is necessary to arrange the nozzle openings on the nozzle plate at a high density. On the other hand, in order to ensure the ejection characteristics of the droplets, it is necessary to ensure a certain volume of the nozzle flow path.

[0005] In order to make the nozzle openings high-density and ensure the volume of the nozzle flow path, it is considered to set the openings on the surface opposite to the droplet ejection surface to be elongated in one direction. However, when the openings are set to be elongated, it is found that there is a tendency for more under-injection to occur compared with the nozzle flow path in which the openings are set to be square.

[0006] This is believed to be caused by the shape of the meniscus that causes the liquid to return greatly to the nozzle flow path when the liquid droplets are ejected in large droplets at high speed. Fig.24A as well as Fig. 24B As shown, the expansion mode of the meniscus is different between the short side and the long side. As a result, it is considered that the shape of the meniscus becomes unstable, resulting in insufficient injection. Summary of the invention

[0007] An object of the present invention is to provide a nozzle plate, a liquid droplet ejection head, and a liquid droplet ejection device that can achieve both high density of nozzle openings and appropriate ejection characteristics.

[0008] The invention described in claim 1 is a nozzle plate having a plurality of nozzle channels, wherein the nozzle channels have nozzle openings for ejecting liquid droplets formed on a first surface of a substrate, wherein:

[0009] The nozzle flow path has:

[0010] The nozzle tapered portion has a flow path area that is orthogonal to the ejection direction of the liquid droplets, which gradually increases from the first surface toward a second surface opposite to the first surface; and

[0011] A straight connecting portion is connected to the end of the second surface side of the nozzle tapered portion, and a pair of opposite surfaces of the straight connecting portion are substantially parallel.

[0012] In the second surface, the length of the linear connection portion in a first direction along the pair of opposing surfaces is longer than the length in a second direction orthogonal to the first direction.

[0013] The nozzle tapered portion includes: a tapered surface inclined from the end of the first direction toward the center of the nozzle opening; and a pair of step surfaces, which form steps on the tapered surface with the nozzle opening sandwiched therebetween.

[0014] The step surface is a drooping surface parallel to the nozzle center axis or an inclined surface whose angle with an axis parallel to the nozzle center axis is smaller than that of the tapered surface.

[0015] The invention described in the second technical solution is the nozzle plate described in the first technical solution, wherein:

[0016] The distance between the pair of step surfaces in the cross section in the first direction passing through the center of the nozzle opening is equal to the length in the second direction.

[0017] The invention described in the third technical solution is the nozzle plate described in the first technical solution or the second technical solution, wherein:

[0018] The length from the first surface to the end of the step surface on the second surface side is equal to or greater than the maximum height of the meniscus rise.

[0019] The invention described in claim 4 is the nozzle plate described in claim 3, wherein:

[0020] The length from the first surface to the end of the step surface on the second surface side is 20 μm or more.

[0021] The invention described in claim 5 is the nozzle plate described in claim 3, wherein:

[0022] The length from the first surface to the end of the step surface on the second surface side is 60 μm or less.

[0023] The invention described in claim 6 is the nozzle plate described in claim 1 or claim 2, wherein:

[0024] The nozzle flow path includes a nozzle straight portion continuous with an end portion of the nozzle tapered portion on the first surface side.

[0025] The angle between the plane constituting the straight portion of the nozzle and the axis parallel to the center axis of the nozzle is substantially constant.

[0026] The flow passage area of ​​the end portion of the nozzle straight portion on the first surface side is smaller than or equal to the flow passage area of ​​the end portion on the second surface side.

[0027] The invention described in claim 7 is the nozzle plate described in claim 1 or claim 2, wherein:

[0028] The substrate is made of single crystal silicon.

[0029] The nozzle tapered portion is composed of a portion of the {100} surface and the {111} surface.

[0030] The linear connecting portion is constituted by a part of the {100} plane.

[0031] The invention described in claim 8 is the nozzle plate described in claim 1 or claim 2, wherein:

[0032] A planar portion having a surface parallel to the first surface and the second surface is provided between an end portion of the linear communication portion on the first surface side and an end portion of the nozzle tapered portion on the second surface side.

[0033] The invention described in the ninth technical solution is a liquid droplet ejection head mounted on a liquid droplet ejection device, wherein:

[0034] A nozzle plate according to the first or second aspect is provided.

[0035] The invention described in the tenth technical solution is a liquid droplet ejection device, wherein:

[0036] A liquid drop ejection head according to the ninth technical solution is provided.

[0037] According to the present invention, it is possible to provide a nozzle plate, a liquid droplet ejection head, and a liquid droplet ejection device that can achieve both high density of nozzle openings and appropriate ejection characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic perspective view of a liquid droplet ejection device.

[0039] Figure 2 It is an exploded perspective view showing the main parts of the droplet ejection head.

[0040] Figure 3 This is a perspective cross-sectional view of one nozzle flow path in the first embodiment.

[0041] Figure 4A is based on Figure 3 Side cross-sectional view of the IVA-IVA line.

[0042] Figure 4B is based on Figure 3 Side cross-sectional view of the IVB-IVB line.

[0043] Figure 5 It is a side cross-sectional view of a nozzle flow path having multiple steps.

[0044] Fig. 6A It is a side cross-sectional view showing a state of introducing liquid into the nozzle flow path of the present invention.

[0045] Figure 6B It is a side cross-sectional view showing a state of introducing liquid into the nozzle flow path of the present invention.

[0046] Figure 7 It is a side sectional view and a top view which show the manufacturing method of the nozzle plate of 1st Embodiment.

[0047] Figure 8 This is a perspective cross-sectional view of one nozzle flow path according to the second embodiment.

[0048] Fig. 9A is based on Figure 8 Side cross-sectional view of the IXA-IXA line.

[0049] Fig. 9B is based on Figure 8 Side cross-sectional view of the IXB-IXB line.

[0050] Fig. 10A This is an example of a nozzle flow path including the nozzle straight portion of the present invention.

[0051] Fig. 10B This is an example of a nozzle flow path including the nozzle straight portion of the present invention.

[0052] Fig. 10C This is an example of a nozzle flow path including the nozzle straight portion of the present invention.

[0053] Fig. 10D This is an example of a nozzle flow path including the nozzle straight portion of the present invention.

[0054] Fig.10E This is an example of a nozzle flow path that does not include the nozzle straight portion of the present invention.

[0055] Fig.10F This is an example of a nozzle flow path that does not include the nozzle straight portion of the present invention.

[0056] Figure 10G This is an example of a nozzle flow path that does not include the nozzle straight portion of the present invention.

[0057] Fig.11 It is a side sectional view and a top view which show the manufacturing method of the nozzle plate of 2nd Embodiment.

[0058] Fig. 12A FIG. 4 is a perspective cross-sectional view of a nozzle flow path of another example.

[0059] Fig. 12B FIG. 4 is a perspective cross-sectional view of a nozzle flow path of another example.

[0060] Fig.13 FIG. 4 is a side sectional view of a nozzle flow path of another example.

[0061] Fig.14 FIG. 4 is a perspective cross-sectional view of a nozzle flow path of another example.

[0062] Fig.15 It is a side sectional view and a top view which show the manufacturing method of the nozzle plate of another example.

[0063] Fig.16A This is a side cross-sectional view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 1 as viewed from the long side.

[0064] Fig. 16B This is a plan view of one nozzle flow channel and an intermediate structure serving as the nozzle flow channel of Example 1 as viewed from the bonding surface side.

[0065] Fig.17A This is a side cross-sectional view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 2 as viewed from the long side.

[0066] Fig. 17B This is a plan view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 2 as viewed from the bonding surface side.

[0067] Fig.18A This is a side cross-sectional view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel according to Example 3, as viewed from the long side.

[0068] Fig.18B This is a plan view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 3 as viewed from the bonding surface side.

[0069] Fig.19A This is a side cross-sectional view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 4 as viewed from the long side.

[0070] Fig.19B This is a plan view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel according to Example 4, as viewed from the bonding surface side.

[0071] Fig. 20A This is a side cross-sectional view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 5 as viewed from the long side.

[0072] Fig. 20B This is a plan view of one nozzle flow channel and an intermediate structure constituting the nozzle flow channel of Example 5 as viewed from the bonding surface side.

[0073] Fig.21A This is a side cross-sectional view of one nozzle flow channel of Comparative Example 1 and an intermediate structure serving as the nozzle flow channel, as viewed from the long side.

[0074] Fig.21B This is a plan view of one nozzle flow channel of Comparative Example 1 and an intermediate structure serving as the nozzle flow channel as viewed from the bonding surface side.

[0075] Fig.22A This is a side cross-sectional view of one nozzle flow channel of Comparative Example 2 and an intermediate structure serving as the nozzle flow channel, as viewed from the long side.

[0076] Fig. 22B This is a plan view of one nozzle flow channel of Comparative Example 2 and an intermediate structure serving as the nozzle flow channel as viewed from the bonding surface side.

[0077] Fig.23A This is a side cross-sectional view of one nozzle flow channel of Comparative Example 3 and an intermediate structure serving as the nozzle flow channel, as viewed from the long side.

[0078] Fig. 23B This is a plan view of one nozzle flow channel of Comparative Example 3 and an intermediate structure serving as the nozzle flow channel as viewed from the bonding surface side.

[0079] Fig.24A It is a side cross-sectional view showing a state in which liquid is introduced into a nozzle flow path having an elongated opening and no stepped surface.

[0080] Fig. 24B A side cross-sectional view showing a state in which a liquid is introduced into a nozzle flow path having an elongated opening and no stepped surface. DETAILED DESCRIPTION

[0081] Hereinafter, the preferred embodiment of the present invention will be described with reference to the accompanying drawings. However, the scope of the invention is not limited to the illustrated examples. In addition, in the following description, the same symbols are used for parts having the same functions and structures, and their descriptions are omitted.

[0082] In addition, the Miller indices describing the crystal planes and directions are generally defined as follows, and this specification also follows this definition.

[0083] (hkl): specific surface

[0084] [hkl]: Equivalent surface

[0085] [hkl]: Specific direction

[0086] <h k l> : Equivalent direction

[0087] In the method of displaying Miller indices, the symbol for indicating a negative exponent is generally a bar on the exponent, as in (1) and (2) of the following mathematical formula 1. However, in this specification, for convenience, it is expressed as in (1') and (2') below.

[0088] [Mathematical formula 1]

[0089]

[0090] (hk l)…(1′)

[0091] [hk l]…(2′)

[0092] [Inkjet recording device]

[0093] First, as a liquid droplet ejection device according to the present embodiment, a configuration example of an inkjet recording device 1 including an inkjet head 10 as a liquid droplet ejection head is disclosed.

[0094] In the following description, as shown in the respective figures, the conveying direction of the recording medium P in the inkjet recording device 1 is defined as the front-rear direction. In addition, the direction perpendicular to the front-rear direction on the conveying surface of the recording medium P is defined as the left-right direction. In addition, the direction in which the ink is ejected and which is perpendicular to the front-rear direction and the left-right direction is defined as the up-down direction. In addition, the inkjet head 10 is also described in the direction based on the state in which it is installed in the inkjet recording device 1.

[0095] Figure 1 1 is a schematic perspective view showing an inkjet recording device 1 of the present embodiment. The inkjet recording device 1, for example, conveys a recording medium P such as paper through a plurality of units U by means of a conveying unit T having a conveying belt T1 and a conveying roller T2. A plurality of inkjet heads 10 are arranged in each unit U. Each inkjet head 10 is provided with a nozzle opening N (see Figure 2 ) ejects inks of various colors to print on the recording medium P.

[0096] <Inkjet Head>

[0097] Figure 2 It is an exploded perspective view showing the main structure of an inkjet head 10.

[0098] Specifically, the head chip 100 includes a nozzle plate 110, a flow path plate 120, a piezoelectric body plate 130, and a wiring plate 140 in this order from the bottom. Figure 2 , an FPC 200 (Flexible Printed Circuit) is shown. The FPC 200 is electrically connected to the wiring board 140 .

[0099] In addition, Figure 2 In the embodiment, the nozzle opening N is upward, that is, Figure 1 Draw it upside down.

[0100] (Head chip)

[0101] like Figure 2 As shown, the head chip 100 has a structure in which plates are stacked.

[0102] The nozzle plate 110 , the flow channel plate 120 , the piezoelectric body plate 130 , and the wiring plate 140 are all substantially rectangular plate-shaped members that are elongated in the left-right direction.

[0103] {Nozzle Plate}

[0104] In the nozzle plate 110, on the substrate B (refer to Figure 3 ) will be through the hole in the vertical direction, that is, the nozzle flow path 111 (refer to Figure 3 ) are set to form columns in the left and right directions.

[0105] The nozzle opening N, which is the opening of the nozzle channel 111, is provided on the lower surface of the nozzle plate 110. That is, the lower surface of the nozzle plate 110 forms the ejection surface (first surface) Ba of the inkjet head 10. Ink is ejected from the nozzle opening N substantially perpendicularly to the ejection surface Ba.

[0106] The nozzle plate 110 and the nozzle flow path 111 will be described in detail later.

[0107] {Flow board}

[0108] The flow channel plate 120 is a plate-like member having a substantially same rectangular shape as the nozzle plate 110 when viewed from the top and bottom.

[0109] The flow channel plate 120 is provided with a through flow channel 121 and a separate discharge flow channel 122 .

[0110] The through-flow path 121 is a flow path communicating with the nozzle flow path 111 . In addition, the individual discharge flow path 122 is a flow path branched from the through-flow path 121 .

[0111] The surface of the nozzle plate 110 that faces the ejection surface Ba, that is, the bonding surface (second surface) Bb (see Figure 3 ) is bonded (fixed) to the lower surface of the flow path plate 120 via an adhesive. In addition, the lower surface of the piezoelectric body plate 130 is bonded (fixed) to the upper surface of the flow path plate 120 via an adhesive.

[0112] The flow channel plate 120 is made of, for example, a silicon substrate.

[0113] {Piezoelectric plate}

[0114] The piezoelectric plate 130 is a plate-shaped member having a substantially rectangular shape substantially similar to that of the nozzle plate 110 when viewed from the top and bottom.

[0115] The piezoelectric plate 130 is provided with a pressure chamber 131 , a common discharge flow path 132 , and a vertical discharge flow path 133 .

[0116] The pressure chamber 131 communicates with the through flow path 121. In addition, the common discharge flow path 132 communicates with the individual discharge flow paths 122. In addition, the vertical discharge flow path 133 communicates with the common discharge flow path 132.

[0117] The material of the piezoelectric plate 130 is a ceramic piezoelectric body (a member that deforms when a voltage is applied). Examples of such a piezoelectric body include PZT (lead zirconate titanate), lithium niobate, barium titanate, lead titanate, and lead metaniobate.

[0118] {Wiring board}

[0119] The wiring board 140 is a flat-plate-shaped substrate having an area larger than that of the piezoelectric plate 130 .

[0120] The wiring board 140 is provided with an ink supply flow path 141 and a discharge hole 142 .

[0121] The ink supply passage 141 communicates with an ink chamber (not shown) via a first opening 1411 as an opening on the upper surface. The ink supply passage 141 communicates with the pressure chamber 131 via a second opening 1412 on the lower surface. The discharge hole 142 communicates with the vertical discharge passage 133.

[0122] The lower surface of the wiring plate 140 is bonded to the upper surface of the piezoelectric plate 130 via an adhesive.

[0123] A plurality of wirings connected to electrodes of ink channels described later are provided on the surface of wiring board 140 bonded to piezoelectric plate 130. FPC 200 is connected to the end of wiring board 140 where the wirings are provided, for example, via ACF (Anisotropic Conductive Film).

[0124] A driving signal output from a driving circuit (not shown) is supplied to the electrodes of the ink channel via wiring 210 on the FPC 200 and wiring on the wiring board 140 .

[0125] As wiring board 140 , for example, a substrate made of glass, ceramic, silicon, or plastic is used.

[0126] (Ink channel)

[0127] When the flow path plate 120 , the piezoelectric body plate 130 , and the wiring plate 140 are bonded together, the through flow path 121 , the pressure chamber 131 , and the ink supply flow path 141 are connected together to form an ink channel.

[0128] The ink channel is provided at a position overlapping with the nozzle flow path 111 when viewed from the top and bottom. In addition, the ink channel communicates with the nozzle flow path 111. In this way, the ink channel and the nozzle flow path 111 each constitute an ink flow path.

[0129] Electrodes (not shown) are formed on the inner wall surface of the ink channel. According to the potential difference of the drive signal applied to the electrodes of the adjacent ink channels, the part of the wall surface between the ink channels composed of the piezoelectric body of the piezoelectric body plate 130 is displaced. The wall surface is repeatedly displaced in a shear mode, so that the pressure of the ink in the ink channel changes. Moreover, the volume of the pressure chamber 131 changes according to the change of the pressure, and the ink in the ink channel is ejected from the nozzle opening N. That is, the inkjet head 10 of this embodiment performs shear mode ink ejection.

[0130] (Ink discharge flow path)

[0131] In addition, the individual discharge flow path 122 , the common discharge flow path 132 , the vertical discharge flow path 133 , and the discharge hole 142 constitute an ink discharge flow path.

[0132] A portion of the ink supplied from the ink chamber to the ink channel is discharged through the ink discharge flow path to the outside of the inkjet head 10. Thus, bubbles and foreign matter in the ink channel can be discharged to the outside of the inkjet head 10 together with the ink.

[0133] In the inkjet head 10 of the present invention, the flow channel plate 120 is not an essential structure. That is, the nozzle plate 110 and the piezoelectric body plate 130 may be directly bonded.

[0134] In addition, Figure 2 , the nozzle plate 110 is shown to have only one row of nozzle openings N arranged in the left-right direction, but the present invention is not limited thereto. That is, a plurality of rows of nozzle openings N may be provided in the front-rear direction.

[0135] [First embodiment]

[0136] [Nozzle flow path]

[0137] Figure 3 This is an enlarged perspective view showing one nozzle channel 111 in the nozzle plate 110 of the first embodiment. Figure 4A is based on Figure 3 A cross-sectional view of the IVA-IVA line in FIG. 1 , that is, a straight line in the front-rear direction passing through the center of the nozzle opening N. In addition, Figure 4B is based on Figure 3 A cross-sectional view taken along line IVB-IVB, that is, a straight line passing through the center of the nozzle opening N in the left-right direction.

[0138] <Substrate>

[0139] The substrate B is a plate-shaped member made of single crystal silicon (Si) with a thickness of about 100 μm to 725 μm, for example. If a single crystal silicon substrate is used as the base material of the nozzle plate 110, the nozzle flow path 111 can be processed with high precision during the manufacturing process. Therefore, the nozzle flow path 111 with less position error and shape deviation can be formed.

[0140] In addition, the substrate B is not limited to single crystal silicon, and nickel (Ni), SUS (Steel Use Stainless Steel), etc. may also be used.

[0141] Hereinafter, single crystal silicon is used as the substrate B. In addition, the (00-1) surface of the single crystal silicon is set as the ejection surface Ba, and the (001) surface is set as the bonding surface Bb.

[0142] Therefore, if Figure 3 As shown, hereinafter, the

[001] direction is synonymous with the "upward" direction, and the "00-1" direction is synonymous with the "downward" direction. In addition, the

[100] direction is synonymous with the "front" direction, and the [-100] direction is synonymous with the "backward" direction. In addition, the

[010] direction is synonymous with the "left" direction, and the [0-10] direction is synonymous with the "right" direction.

[0143] (Nozzle flow path)

[0144] The nozzle flow path 111 is a hole that penetrates from the ejection surface Ba to the bonding surface Bb.

[0145] The nozzle flow path 111 includes a nozzle opening N, a nozzle tapered portion 1112 , and a linear communication portion 1113 from the ejection surface Ba toward the bonding surface Bb.

[0146] {Nozzle opening}

[0147] The nozzle opening N is a circular, elliptical or polygonal hole provided on the ejection surface Ba for ejecting liquid droplets. The nozzle opening N communicates with the end of the nozzle tapered portion 1112 on the ejection surface Ba side.

[0148] For example, when the shape of the nozzle opening N is circular, the diameter of the nozzle opening N is approximately 15 μm to 45 μm.

[0149] {Nozzle cone}

[0150] The nozzle tapered portion 1112 has a tapered surface 1112a of a substantially constant angle whose flow path area gradually increases from the ejection surface Ba toward the bonding surface Bb. The tapered surface 1112a is a surface inclined from the longitudinal end of the nozzle tapered portion 1112 toward the center of the nozzle opening N.

[0151] When the nozzle flow path 111 is formed by anisotropically wet etching single crystal silicon from the {100} plane, the tapered surfaces 1112a become four {111} planes.

[0152] In addition, the "flow path area" in the present invention refers to the cross-sectional area in the direction perpendicular to the vertical direction which is the ejection direction of the ink.

[0153] Figure 4A The angle formed by the tapered surface 1112a of the nozzle tapered portion 1112 and the axis parallel to the nozzle center axis, i.e., the taper angle θ 1 More than 15°.

[0154] When the substrate B is made of single crystal silicon, the taper angle θ 1 The angle becomes 45° according to the etching characteristics of Si.

[0155] If the nozzle tapered portion 1112 is provided, even when the meniscus of the ink retreats to the deep part of the nozzle channel 111 due to high-speed driving, the shape of the meniscus and the ink ejection are stabilized.

[0156] {Step surface}

[0157] In addition, at least one pair of steps is provided in the nozzle tapered portion 1112. The step surface 1112b is a drooping surface or an inclined surface that forms a step on the tapered surface 1112a of the nozzle tapered portion 1112 with the nozzle opening N interposed therebetween.

[0158] In addition, you can Figure 5 As shown, a plurality of steps are provided in the nozzle tapered portion 1112. However, in the present invention, only the surface of the nozzle tapered portion 1112 where the steps are formed, which is located closest to the nozzle opening N, is referred to as the "step surface 1112b".

[0159] If the stepped surface 1112b is provided on the nozzle tapered portion 1112, even if ink is introduced into the nozzle flow path 111, Fig. 6A as well as Figure 6B As shown, the expansion of the meniscus in the front-rear direction is also suppressed. Therefore, the stability of the meniscus shape is improved, and the nozzle flow path 111 with excellent ejection characteristics is obtained.

[0160] In addition, when the step surface 1112b is an inclined surface, the angle between the inclined surface and the axis parallel to the nozzle center axis is smaller than the taper angle θ 1 That's it.

[0161] in addition, Figure 4A The length h from the nozzle opening N to the end of the step surface 1112b on the bonding surface Bb side is shown as follows: 0 It only needs to be higher than the maximum height to which the meniscus can rise. Specifically, it is preferably 20 μm ≤ h 0 ≤60μm.

[0162] This is because it is rare for the ink to be introduced larger than 20 μm. In addition, because if h 0 >60 μm, the nozzle flow path 111 cannot ensure a sufficient volume.

[0163] In addition, the width W of the pair of step surfaces 1112b in the longitudinal direction of the cross section passing through the center of the nozzle opening N (the interval between the step surfaces 1112b) is set to 3 (Refer to Figure 4A ). In addition, the distance W between the surfaces on the long sides forming the linear connecting portion 1113 in the left-right direction is set to 2 (Refer to Figure 4B ). At this time, W 2 With W 3 The relationship is preferably W 2 ≈W 3 .

[0164] If the step surface 1112b is formed in such a relationship, the ejection characteristics of the nozzle flow path 111 are excellent. This is because a space in a plan view that is formed by the step surface 1112b and the surface of the nozzle tapered portion 1112 that is parallel to the surface forming the long side of the linear connecting portion 1113 is formed near the nozzle opening N, and has symmetry.

[0165] {Linear connection part}

[0166] The linear communication portion 1113 communicates with the end portion of the nozzle tapered portion 1112 on the bonding surface Bb side and is provided to the bonding surface Bb.

[0167] The opposite set of faces 1113a of the linear connecting portion 1113 are substantially parallel. In addition, the length of the side of the surface constituting the linear connecting portion 1113 intersecting with the bonding surface Bb along the opposite set of faces 1113a in the front-to-back direction (first direction) is longer than the length in the left-to-right direction (second direction). Figure 3 As shown, the shape of the opening of the nozzle flow path 111 on the bonding surface Bb is an elongated shape.

[0168] According to this structure, the volume of the nozzle flow path 111 can be ensured, and the nozzle openings N can be arranged at a narrow pitch according to the short side length of the elongated shape. Therefore, the density of the nozzle openings N in the nozzle plate 110 is increased.

[0169] In addition, the shape of the opening of the nozzle flow path 111 on the bonding surface Bb is not limited to a rectangle. The shape of the opening of the nozzle flow path 111 on the bonding surface Bb is not particularly limited as long as it is an elongated shape such as a hexagonal shape or an elliptical shape in which the length in the front-to-back direction is longer than the length in the left-to-right direction. However, in the case of the nozzle plate 110 in which the opening of the nozzle flow path 111 on the bonding surface Bb side is expanded by performing the third step (removal processing) described later, the opening is always rectangular.

[0170] [Method for Manufacturing Nozzle Plate According to First Embodiment]

[0171] based on Figure 7 A method for manufacturing such a nozzle plate 110 will be described.

[0172] In addition, in the following, as the substrate B, single crystal silicon is used.

[0173] The method for manufacturing the nozzle plate 110 includes, for example, Figure 7 The first to third steps are shown.

[0174] In the first step, an intermediate structure 300 having an opening hole 305 and a nozzle hole 306 described later is formed. In the second step, the intermediate structure 300 formed in the first step is anisotropically wet-etched to form the nozzle flow path 111. In the third step, the nozzle plate 110 formed in the second step is appropriately removed.

[0175] {First step: intermediate structure forming step}

[0176] (Step 1-1)

[0177] like Figure 7 As shown, the first process is further subdivided into multiple processes.

[0178] First, as step 1-1, a mask layer is formed on the surface of single crystal silicon whose surface crystal orientation is the {100} plane.

[0179] As a mask layer, any mask layer that stops the progress of etching in the second step and is not removed by etching can be used. In addition, the mask layer formed on the bonding surface Bb is set as the surface mask layer 301. In addition, the mask layer formed on the ejection surface Ba is set as the back mask layer 302.

[0180] (Step 1-2)

[0181] Next, as the 1-2 step, an elongated opening pattern 303 is formed on the (001) surface of the single crystal silicon to be the opening of the nozzle flow path 111 on the bonding surface Bb side.

[0182] Specifically, a resist layer is formed on the surface mask layer 301 of the (001) plane by a known photolithography technique. After the resist layer is formed, exposure is performed using an aligner or the like to form a resist pattern. After the resist pattern is formed, the resist pattern is used as a mask, and dry etching is performed using, for example, an RIE (Reactive Ion Etching) device to form an opening pattern 303. After the opening pattern 303 is formed, the resist pattern is removed.

[0183] In addition, Figure 7 In the example, the shape of the opening pattern 303 is set to a rectangular shape having long sides along the front-back direction, but the invention is not limited thereto. The shape of the opening pattern 303 may be, for example, a hexagonal shape, an elliptical shape, or a shape in which a semicircle having a diameter equal to that of the short side is combined with the short side of the rectangle. In this way, the shape of the opening pattern 303 may be an elongated shape in which the length in the front-back direction is longer than the length in the left-right direction.

[0184] (Steps 1-3)

[0185] Next, as the 1-3 step, the single crystal silicon below the opening pattern 303 is deep-drilled by dry etching, thereby forming the opening hole 305 .

[0186] (Step 1-4, Step 1-5)

[0187] Next, as step 1-4, a nozzle pattern 304 is formed on the (00-1) surface of the single crystal silicon to be the nozzle opening N. Furthermore, as step 1-5, the single crystal silicon under the nozzle pattern 304 is deep-drilled by dry etching to form a nozzle hole 306 .

[0188] In addition, in the above, the process is described as progressing in the order of process 1-2, process 1-3, process 1-4, and process 1-5, but the present invention is not limited thereto. It is sufficient as long as at least process 1-2 is performed before process 1-3 and process 1-4 is performed before process 1-5.

[0189] However, in the first step, the intermediate structure 300 is formed so that the depth a of the nozzle hole 306 in the

[001] direction (up and down direction) is longer than the length b from the end of the nozzle hole 306 on the bonding surface Bb side to the end of the opening hole 305 in the

[100] direction (front and back direction).

[0190] Hereinafter, this condition is referred to as "condition 1".

[0191] {Second step: anisotropic wet etching step}

[0192] Next, as a second step, anisotropic wet etching is performed from both sides of the ejection surface Ba and the bonding surface Bb of the intermediate structure 300. As a result, the opening hole 305 provided in the 1-3 step and the nozzle hole 306 provided in the 1-5 step are enlarged to form the nozzle flow path 111. At this time, if condition 1 is satisfied, the tapered surface formed from the nozzle hole 306 does not coincide with the tapered surface formed from the opening hole 305. As a result, a step surface 1112b is formed on the nozzle tapered portion 1112.

[0193] {Third process: Removal of processing steps}

[0194] Furthermore, as a third step, a removal process such as etching, grinding or polishing is performed. Specifically, for example, the diameter of the opening on the bonding surface Bb side of the nozzle flow path 111 is enlarged so that the linear connecting portion 1113 becomes a substantially vertical hole. Alternatively, the thickness of the nozzle plate 110 is adjusted to a desired size. Alternatively, the mask layer is removed.

[0195] Note that the third step is not an essential step in manufacturing the nozzle plate 110 of the first embodiment, and may be appropriately performed as needed.

[0196] [Second embodiment]

[0197] based on Figure 8 A nozzle plate 110 according to a second embodiment will be described with reference to FIG. 9 .

[0198] Figure 8 This is an enlarged perspective view showing one nozzle channel 111 in the nozzle plate 110 according to the second embodiment. Fig. 9A is based on Figure 8 A cross-sectional view of the line IXA-IXA in FIG. 1 , that is, a straight line in the front-to-back direction passing through the center of the nozzle opening N. In addition, Fig. 9B is based on Figure 8 A cross-sectional view taken along the IXB-IXB line, i.e., a straight line passing through the center of the nozzle opening N in the left-right direction.

[0199] In addition, the same reference numerals are used for the same structures as those of the nozzle plate 110 of the first embodiment, and the detailed description thereof will be omitted.

[0200] The nozzle plate 110 of the second embodiment is different from the nozzle plate 110 of the first embodiment in that the nozzle flow path 111 includes a nozzle straight portion 1111 .

[0201] {Nozzle straight line part}

[0202] The nozzle straight portion 1111 is formed continuously with the end portion of the nozzle tapered portion 1112 on the ejection surface Ba side and the nozzle opening N.

[0203] The flow path area of ​​the nozzle straight portion 1111 is always constant from the bonding surface Bb side to the ejection surface Ba side. That is, the angle θ formed by the surface forming the nozzle straight portion 1111 and the axis parallel to the nozzle center axis is 2 is 0°.

[0204] In addition, the angle θ between the nozzle straight portion 1111 and the axis parallel to the nozzle center axis is 2 The angle is not limited to 0°. The nozzle straight portion 1111 may have a tapered shape in which the flow path area gradually increases from the ejection surface Ba toward the bonding surface Bb side.

[0205] Specifically, the angle θ formed by the surface constituting the nozzle straight portion 1111 and the axis parallel to the nozzle center axis is 2 It is roughly constant at any position and 0°≤θ 2 <15°. In addition, Fig. 9A as well as Fig. 9B As shown in FIG. 1 , the diameter of the end portion of the nozzle straight portion 1111 on the bonding surface Bb side is set to D 1 , the diameter of the nozzle opening N, that is, the diameter of the end of the nozzle straight portion 1111 on the ejection surface Ba side is set to D 0 In the case of D 1 ≥D 0 That's it.

[0206] Right now, FIG. 10A to FIG. 10G In the nozzle flow path 111 shown, FIG. 10A to FIG. 10D The lower portion of the nozzle tapered portion 1112 is the "nozzle straight portion 1111" that satisfies all of the above conditions.

[0207] on the other hand, FIG. 10E to FIG. 10G The lower part of the nozzle tapered portion 1112 does not conform to the "nozzle straight portion 1111" of the present invention. Specifically, Fig.10E In, does not satisfy D 1 ≥D 0 , and does not satisfy 0°≤θ 2 <15°. In addition, Fig.10F as well as Figure 10G Although D 1 ≥D 0 , but θ 2 It is not substantially constant at any location.

[0208] In addition, FIG. 10A to FIG. 10G In the figure, the record of the step surface 1112b is omitted.

[0209] in addition, Fig. 9AThe length in the vertical direction of the nozzle straight portion 1111 shown, that is, the height L, is preferably about 5 μm to 50 μm. When the height of the nozzle straight portion 1111 is within this range, appropriate resistance is applied when the ink is ejected.

[0210] If the nozzle straight portion 1111 is provided in the nozzle flow path 111 , the resistance applied when the ink is ejected from the nozzle opening N becomes larger. This suppresses the vibration of the meniscus, so that the shape of the meniscus is further stabilized.

[0211] In addition, in W 2 ≈W 3 In the case of 1 It is represented by the following formula (3).

[0212] h 1 =h 0 -(W 2 -D 1 ) / (2tanθ 1 )-L

[0213] ≈h 0 -(W 3 -D 1 ) / (2tanθ 1 )-L…(3)

[0214] The diameter of the end of the nozzle straight portion 1111 on the bonding surface Bb side, or the diameter D of the end of the nozzle tapered portion 1112 on the ejection surface Ba side, is 1 It is represented by the following formula (4).

[0215] D 1 =D 0 +2×Ltanθ 2 …(4)

[0216] [Method for Manufacturing Nozzle Plate According to Second Embodiment]

[0217] based on Fig.11 A method for manufacturing the nozzle plate 110 according to the second embodiment will be described.

[0218] The method for manufacturing the nozzle plate 110 of the second embodiment is different from the method for manufacturing the nozzle plate 110 of the first embodiment in that steps 1-A to 1-C are performed between steps 1-4 and 1-5.

[0219] (Step 1-A)

[0220] After forming a mask layer in step 1-1, the nozzle pattern 304 is formed in step 1-4. After the nozzle pattern 304 is formed, dry etching is performed according to a predetermined length of the nozzle straight portion 1111 as step 1-A to form the nozzle straight hole 307.

[0221] (Step 1-B)

[0222] Next, as step 1-B, a nozzle mask layer 308 is formed along the inner surface of the nozzle linear hole 307. The method for forming the nozzle mask layer 308 is the same as the method for forming the mask layer.

[0223] (Step 1-C)

[0224] Then, as step 1-C, the nozzle mask layer 308 formed on the bottom of the nozzle linear hole 307 is removed by dry etching. Then, the nozzle mask layer 308 remains only on the side surface of the nozzle linear hole 307.

[0225] (Step 1-5, Step 1-2, Step 1-3)

[0226] After step 1-C, as step 1-5, substrate B is dry-etched to further deepen nozzle linear hole 307, thereby forming nozzle hole 306. Then, opening hole 305 is provided through steps 1-2 and 1-3.

[0227] (Second process, third process)

[0228] Then, anisotropic wet etching is performed as a second step. However, the nozzle linear hole 307 is protected by the nozzle mask layer 308. Therefore, the progress of etching of the nozzle linear hole 307 is suppressed, and the nozzle linear portion 1111 remains. As a result, the nozzle flow path 111 having the nozzle linear portion 1111 is formed.

[0229] After the second step, the third step is appropriately performed as necessary.

[0230] [Modifications]

[0231] As the step surface 1112b, it is not limited to Figure 3 , Figure 8 The two-sided structure shown can also be Fig. 12A The structure shown in FIG. 1 is a planar structure that is straight in top view. Fig. 12B The curved surface shown is convex in the forward direction.

[0232] In addition, Figure 3 In the examples, the nozzle conical portion 1112 and the straight connecting portion 1113 are connected to the nozzle flow path 111, but the invention is not limited thereto. Fig.13 As shown, the nozzle flow path 111 includes a flat surface portion 1112 c substantially parallel to the bonding surface Bb and the ejection surface Ba between the nozzle tapered portion 1112 and the linear communication portion 1113 .

[0233] In addition, Figure 3 In the examples, the nozzle tapered portion 1112 includes four tapered surfaces 1112a, but the present invention is not limited thereto.

[0234] For example, it can also be Fig.14 The nozzle flow path 111 shown is an elliptical funnel-shaped nozzle flow path 111 having a curved tapered surface.

[0235] based on Fig.15 A method for manufacturing the nozzle plate 110 including such nozzle flow paths 111 will be described.

[0236] [Method for manufacturing nozzle plate of another example]

[0237] (Step I)

[0238] First, as a first step, a resist layer 401 is formed on the bonding surface Bb of a silicon wafer having a quartz layer (mask layer) formed on the bonding surface Bb and the ejection surface Ba.

[0239] (Step II)

[0240] Next, as step II, after pressing the gray tone mask onto the resist layer 401, UV (Ultra Violet) is irradiated to expose the resist layer 401. Then, the resist layer 401 is immersed in a developer to remove the exposed part of the resist layer 401.

[0241] The gray tone mask has a distribution in light transmittance, so that a resist pattern having an inclination can be formed so that the thickness of the resist layer 401 is distributed according to the distribution. In addition, at this time, the nozzle tapered portion 1112 is provided with a step surface 1112b according to the design of the gray tone mask.

[0242] (Step III)

[0243] Next, as step III, the quartz layer is dry-etched using the resist pattern as a mask. At this time, the thickness distribution of the photoresist 402 is transferred to the quartz layer.

[0244] (Step IV)

[0245] Then, as step IV, the single crystal silicon is dry-etched using the quartz layer as a mask. At this time, the thickness distribution of the quartz layer is also transferred to the single crystal silicon.

[0246] In addition, although it depends on the etching conditions, the thickness distribution of the quartz layer and the thickness distribution of the single crystal silicon are generally about 1:50 to 1:100.

[0247] (Step V)

[0248] After dry etching is performed according to a predetermined etching amount, a resist layer 401 is formed and photosensitized on the ejection surface Ba of the silicon wafer as step V to form a resist pattern. Then, as step VI, the nozzle opening N and the nozzle straight portion 1111 are formed by dry etching to communicate with the hole provided in step IV.

[0249] Example

[0250] Next, the results of evaluating the preferred structures of the examples and comparative examples of the present invention will be described. The present invention will be specifically described below by way of examples, but the present invention is not limited thereto.

[0251] [Sample production]

[0252] A nozzle plate 110 made of single crystal silicon and having 1280 or less nozzle flow paths 111 as in each embodiment and comparative example is manufactured. Then, the nozzle plate 110 is bonded to a piezoelectric body plate having an ink flow path whose opening on the bonding surface has the same shape as the opening on the bonding surface Bb side of the nozzle plate 110, thereby forming an inkjet head 10. Then, the inkjet head 10 is mounted on the inkjet recording device 1.

[0253] FIG. 16A to FIG. 23B 1 is a diagram showing one nozzle flow path 111 in the nozzle plate 110 of each embodiment and comparative example. In each figure, the dotted line portion represents the intermediate structure 300 formed in the first step. In addition, the solid line portion represents the nozzle flow path 111 in which the opening on the bonding surface Bb side is rectangular by performing anisotropic wet etching on the intermediate structure 300 in the second step and performing removal processing in the third step so that the ground straight line connecting portion 1113 is substantially vertical.

[0254] In addition, hereinafter, the length of the long side of the opening of the nozzle flow path 111 on the bonding surface Bb side after the third step is referred to as W. 1 .

[0255] (Example 1)

[0256] like Fig.16A as well as Fig. 16B As shown, the nozzle flow path 111A of the first embodiment includes a nozzle tapered portion 1112A, a stepped surface 1112bA, and a linear communication portion 1113A.

[0257] As a specific size, W 1 =130μm, W2 =W 3 =50μm. In addition, h 0 =20μm,h 1 =10μm, D 0 =D 1 =30μm. In addition, Fig.16A As shown, a step is further provided on the tapered surface 1112aA at a position above the step surface 1112bA.

[0258] In addition, if Fig. 16B As shown, the shape of the opening pattern 303 is a rectangle. In addition, the shape of the nozzle opening N is a circle.

[0259] (Example 2)

[0260] like Fig.17A as well as Fig. 17B As shown, the nozzle flow path 111B of the second embodiment includes a nozzle straight portion 1111B, a nozzle tapered portion 1112B, a stepped surface 1112bB, and a straight connecting portion 1113B.

[0261] As a specific size, W 1 =130μm, W 2 =W 3 =50μm. In addition, h 0 =30μm, h 1 =10μm, D 0 =D 1 =30μm.

[0262] In addition, if Fig.17A as well as Fig. 17B As shown, in this embodiment, a rhombus-shaped nozzle pattern 304 with a diameter of 10 μm is formed in the first to fourth steps. In addition, in this embodiment, the nozzle opening N is expanded into a circular shape with a diameter of 30 μm in the third step. Therefore, a nozzle straight portion 1111B with L=10 μm is formed.

[0263] In addition, if Fig. 17B As shown, the shape of the opening pattern 303 is a hexagonal shape.

[0264] (Example 3)

[0265] like Fig.18A as well as Fig.18B As shown, the nozzle flow path 111C of the third embodiment includes a nozzle straight portion 1111C, a nozzle tapered portion 1112C, a step surface 1112bC, and a straight connecting portion 1113C.

[0266] As a specific size, W 1 =130μm, W 2 =W3 =50μm. In addition, h 0 =50μm,h 1 =10μm. In addition, D 0 =D 1 =30μm, L=30μm.

[0267] In addition, if Fig.18A as well as Fig.18B As shown, in this embodiment, a circular nozzle pattern 304 with a diameter of 10 μm is formed in the first to fourth steps. In this embodiment, the nozzle opening N is expanded into a circular shape with a diameter of 30 μm in the third step.

[0268] In addition, if Fig.18B As shown, the shape of the opening pattern 303 is a hexagonal shape.

[0269] (Example 4)

[0270] like Fig.19A as well as Fig.19B As shown, the nozzle flow path 111D of the fourth embodiment includes a nozzle straight portion 1111D, a nozzle tapered portion 1112D, a stepped surface 1112bD, and a straight connecting portion 1113D.

[0271] As a specific size, W 1 =130μm, W 2 =W 3 =50μm. In addition, h 0 =60μm,h 1 =20μm. In addition, D 0 =D 1 =30μm, L=30μm.

[0272] In addition, if Fig.19A as well as Fig.19B As shown, in this embodiment, a circular nozzle pattern 304 with a diameter of 10 μm is formed in the first to fourth steps. In this embodiment, the nozzle opening N is expanded into a circular shape with a diameter of 30 μm in the third step.

[0273] In addition, if Fig.19B As shown, the shape of the opening pattern 303 is a shape in which a semicircle having a diameter equal to the width of the short side is combined with the short side of the rectangle.

[0274] (Example 5)

[0275] like Fig. 20A as well as Fig. 20B As shown, the nozzle flow path 111E of the fifth embodiment includes a nozzle straight portion 1111E, a nozzle tapered portion 1112E, a step surface 1112bE, and a straight connecting portion 1113E.

[0276] As a specific size, W 1 =130μm, W 2 =W 3 =50μm. In addition, h 0 =50μm,h 1 =10μm.

[0277] In addition, if Fig. 20A as well as Fig. 20B As shown, in this embodiment, a square nozzle pattern 304 with a diameter of 10 μm is formed in the first to fourth steps. In this embodiment, the nozzle opening N is expanded into a circular shape with a diameter of 30 μm in the third step.

[0278] In addition, if Fig. 20A As shown, in this embodiment, in the third step, the nozzle straight portion 1111E is made into a tapered shape, so that θ 2 =8°. Therefore, D 1 =40μm, D 0 =30μm, L=35μm.

[0279] In addition, if Fig. 20B As shown, the shape of the opening pattern 303 is a rectangle.

[0280] (Example 6)

[0281] like Fig.21A as well as Fig.21B As shown, the nozzle flow path 111F of the sixth embodiment includes a nozzle tapered portion 1112F, a stepped surface 1112bF, and a linear communication portion 1113F.

[0282] As a specific size, W 1 =130μm, W 2 =W 3 =50μm. In addition, h 0 =15μm, h 1 =5μm, D 0 =D 1 =30μm. In addition, Fig.21A As shown, a step is also provided at a position above the step surface 1112bF in the tapered surface 1112aF.

[0283] In addition, if Fig.21B As shown, the shape of the opening pattern 303 is a shape in which a semicircle having a diameter equal to the width of the short side is combined with the short side of the rectangle. In addition, the shape of the nozzle opening N is a circle.

[0284] (Example 7)

[0285] like Fig.22A as well as Fig. 22B As shown, the nozzle flow path 111G of the seventh embodiment includes a nozzle tapered portion 1112G, a step surface 1112bG, and a linear communication portion 1113G.

[0286] As a specific size, W 1 =130μm, W 2 =W 3 =50μm. In addition, h 0 =65μm,h 1 =55μm, D 0 =D 1 =30μm. In addition, Fig.22A As shown, a step is also provided at a position above the step surface 1112bG in the tapered surface 1112aG.

[0287] In addition, if Fig. 22B As shown, the shape of the opening pattern 303 is a rectangle. In addition, the shape of the nozzle opening N is a circle.

[0288] (Comparative Example 1)

[0289] like Fig.23A as well as Fig. 23B As shown in FIG. 1 , the nozzle flow path 111F of Comparative Example 1 only includes a nozzle tapered portion 1112H and a linear connecting portion 1113H. Fig.23A As shown, in this comparative example, the dimensions are made uniform in the first step so that a=b. Therefore, the nozzle tapered portion 1112H does not include the step surface 1112b.

[0290] As a specific size, W 1 =130μm, W 2 =50μm. In addition, D 0 =D 1 =30μm.

[0291] In addition, if Fig. 23B As shown, the shape of the opening pattern 303 is a hexagonal shape. In addition, the shape of the nozzle opening N is a circle.

[0292] (Comparative Example 2)

[0293] The nozzle flow path 111 is formed by a conventionally known method.

[0294] That is, the nozzle flow path 111 includes the nozzle tapered portion 1112 and the linear connecting portion 1113. However, the nozzle tapered portion 1112 does not include the step surface 1112b. In addition, the opening of the nozzle flow path 111 on the bonding surface Bb side is W 1 =50,W 2 =50μm square.

[0295] The following Test 1 and Test 2 were performed using the inkjet recording apparatus 1 equipped with the inkjet head 10 including the nozzle plates 110 of the above-described Examples 1-7 and Comparative Examples 1-2.

[0296] [Test 1. Emission angle test]

[0297] UV ink heated to a viscosity of 8 cP was ejected at a driving voltage with an average droplet velocity of about 6 m / s. At this time, the angle between the nozzle center axis and the ejected liquid, i.e. the ejection angle, was evaluated for 1,280 nozzles to be within ± a few degrees.

[0298] [Test 2. Upper speed limit test]

[0299] At a driving frequency of 40kHz, the ejection speed of the UV ink heated to a viscosity of 8cP is increased from 5m / s. Moreover, the ejection speed of the nozzle opening N that produces insufficient ejection is measured when more than 5 nozzles out of 100 nozzles produce insufficient ejection. In addition, when the ejection speed is above 9m / s, insufficient ejection is not easy to occur even if the ejection speed is high, but it is more preferably good to have an ejection speed of above 10m / s, and more preferably excellent to have an ejection speed of above 11m / s. Therefore, as for the stability of the curved liquid surface, less than 9m / s is evaluated as "C", 9m / s or more and less than 10m / s is evaluated as "B", 10m / s or more and less than 11m / s is evaluated as "A", and 11m / s or more is evaluated as "AA".

[0300] Table 1 shows the results of Test 1 and Test 2.

[0301] [Table 1]

[0302]

[0303] [evaluate]

[0304] Comparing Example 1 with Comparative Example 1, it can be seen that by providing the step surface 1112 b in the nozzle tapered portion 1112 , the nozzle flow path 111 having excellent meniscus stability is achieved.

[0305] In addition, when comparing Example 1 with Example 6, it can be seen that the length h from the nozzle opening N to the end of the step surface 1112b on the bonding surface Bb side is 0 Preferably, it is 20 μm or more. In addition, when comparing Example 4 with Example 7, it can be seen that the length h from the nozzle opening N to the end of the step surface 1112b on the bonding surface Bb side is 0 It is preferably 60 μm or less.

[0306] In addition, when comparing Example 1 with Examples 2 to 5, it is found that the flow path resistance is increased and the driving voltage is increased by providing the nozzle straight portion 1111. On the other hand, it is found that the nozzle straight portion 1111 provides a nozzle flow path 111 with a stable ejection angle.

[0307] In addition, when Example 5 is compared with Example 3 in particular, it can be seen that by making the nozzle straight portion 1111 into a tapered shape, the flow path resistance is reduced and the driving voltage is reduced.

[0308] Furthermore, when comparing Comparative Example 1 with Comparative Example 2, it is found that by making the opening of the nozzle flow channel 111 on the bonding surface Bb side in the nozzle plate 110 into an elongated shape, the flow channel resistance is reduced and the driving voltage is reduced.

[0309] [Technical Effect]

[0310] As described above, the nozzle plate 110 of the present embodiment is provided with a pair of step surfaces 1112 b in the nozzle tapered portion 1112 .

[0311] According to this structure, the shape of the meniscus in the nozzle flow path 111 is suppressed from expanding in only one direction. Fig. 6A as well as Figure 6B As shown in FIG. 1 , the expansion mode of the meniscus shape is made uniform. As a result, the stability of the meniscus shape is improved, and the nozzle flow path 111 with excellent ejection characteristics is obtained.

[0312] In addition, the distance W between the pair of step surfaces 1112b in the cross section in the longitudinal direction passing through the center of the nozzle opening N is 3 The distance W in the left-right direction, that is, the second direction, between a pair of surfaces constituting the long sides of the bonding surface Bb among the surfaces constituting the linear connecting portion 1113 is 2 About the same.

[0313] According to this structure, a space that is roughly square in plan view and is formed by the stepped surface 1112b and the surface of the nozzle tapered portion 1112 that is parallel to the surface forming the long side of the nozzle straight portion 1111 is formed near the nozzle opening portion N, and has symmetry. Therefore, the nozzle flow path 111 has excellent ejection characteristics.

[0314] The length h from the ejection surface Ba to the end of the step surface 1112b on the bonding surface Bb side is 0 It is above the maximum height to which the meniscus rises.

[0315] According to this structure, by introducing the ink to a position above the step surface 1112b, it is possible to prevent the meniscus from being destroyed and the ejection characteristics from being deteriorated.

[0316] The length h from the ejection surface Ba to the end of the step surface 1112b on the bonding surface Bb side is 0 Specifically, it is 20 μm or more and 60 μm or less.

[0317] According to this structure, the nozzle flow path 111 is formed to achieve both discharge characteristics and volume assurance.

[0318] In addition, the nozzle flow path 111 is provided with a nozzle straight portion 1111 .

[0319] According to this structure, the nozzle flow path 111 is provided with more excellent discharge characteristics.

[0320] In addition, the nozzle plate 110 is formed of a single crystal silicon substrate.

[0321] According to this structure, the nozzle flow path 111 is formed with high precision.

[0322] As mentioned above, although embodiment and its modification example of this invention were described, the description content in the said embodiment and modification example is a preferable example of this invention, and is not limited to this.

[0323] Industrial Applicability

[0324] The present invention can be used for a nozzle plate, a liquid droplet ejection head, and a liquid droplet ejection device that can achieve both high density of nozzle openings and appropriate ejection characteristics.

[0325] Explanation of the reference numerals: 1… inkjet recording device (liquid droplet ejection device); 10… inkjet head (liquid droplet ejection head); 110… nozzle plate; 111… nozzle flow path; 1111… nozzle straight portion; 1112… nozzle conical portion; 1112a… conical surface; 1112b… step surface; 1112c… plane portion; 1113… straight connecting portion; 1113a… a set of opposing surfaces; N… nozzle opening; B… substrate; Ba… ejection surface (first surface); Bb… bonding surface (second surface).

Claims

1. A nozzle plate comprising a plurality of nozzle channels, wherein the nozzle channels have nozzle openings for ejecting liquid droplets formed on a first surface of a substrate, in, The nozzle flow path comprises: The nozzle tapered portion has a flow path area that is orthogonal to the ejection direction of the liquid droplets, which gradually increases from the first surface toward a second surface opposite to the first surface; and A straight connecting portion is connected to the end of the nozzle tapered portion on the second surface side, and a pair of opposing surfaces of the straight connecting portion are substantially parallel. In the second surface, the length of the linear connection portion in a first direction along the pair of opposing surfaces is longer than the length in a second direction orthogonal to the first direction. The nozzle tapered portion includes: a tapered surface inclined from an end portion in the first direction toward a center of the nozzle opening; and a pair of stepped surfaces, forming steps on the tapered surface with the nozzle opening sandwiched therebetween. The step surface is a drooping surface parallel to the nozzle center axis or an inclined surface whose angle with an axis parallel to the nozzle center axis is smaller than that of the tapered surface.

2. The nozzle plate according to claim 1, in, The distance between the pair of step surfaces in a cross section in the first direction passing through the center of the nozzle opening is equal to the length in the second direction.

3. The nozzle plate according to claim 1 or 2, in, The length from the first surface to the end of the step surface on the second surface side is equal to or greater than the maximum height of the meniscus rise.

4. The nozzle plate according to claim 3, in, The length from the first surface to the end of the step surface on the second surface side is 20 μm or more.

5. The nozzle plate according to claim 3, in, The length from the first surface to the end of the step surface on the second surface side is 60 μm or less.

6. The nozzle plate according to claim 1 or 2, in, The nozzle flow path includes a nozzle straight portion continuous with an end portion of the nozzle tapered portion on the first surface side. The angle between the surface constituting the straight portion of the nozzle and the axis parallel to the center axis of the nozzle is substantially constant. The flow path area of ​​the end portion of the nozzle straight portion on the first surface side is smaller than or equal to the flow path area of ​​the end portion on the second surface side.

7. The nozzle plate according to claim 1 or 2, in, The substrate is composed of single crystal silicon. The nozzle tapered portion is composed of a portion of the {100} surface and the {111} surface. The linear connecting portion is formed by a portion of the {100} plane.

8. The nozzle plate according to claim 1 or 2, in, A planar portion having a surface parallel to the first surface and the second surface is provided between an end portion of the linear communication portion on the first surface side and an end portion of the nozzle tapered portion on the second surface side.

9. A liquid droplet ejection head, mounted on a liquid droplet ejection device, in, A nozzle plate according to claim 1 or 2.

10. A liquid droplet ejection device, in, A liquid droplet ejection head according to claim 9 is provided.

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