Nozzle plate, droplet dispensing head, droplet dispensing device, and method for manufacturing the nozzle plate

Abstract

Provided is a nozzle plate 110 provided with a substrate B, a nozzle flow path 111 penetrating the substrate B and having a nozzle opening part N for ejecting a liquid droplet, and a discharge flow path C for discharging a liquid from the nozzle flow path 111, wherein the nozzle flow path 111 has a nozzle taper part 1112 of which the flow path area representing a cross-sectional area orthogonal to a liquid ejecting direction gradually narrows toward an ejection surface Ba of the substrate B from which a liquid is ejected, and the discharge flow path C is provided in the middle of the nozzle taper part 1112 when seen from an ejection surface side.

Description

Technical Field

[0001] The present invention relates to a nozzle plate, a droplet discharge head, a droplet discharge device, and a method for manufacturing a nozzle plate.

Background Art

[0002] Conventionally, in a droplet discharge head of a droplet discharge device, by providing a circulation flow path for returning a liquid from a nozzle flow path that supplies a liquid such as ink to a nozzle opening to a common flow path, it is possible to recover bubbles near the nozzle opening together with the liquid (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described droplet discharge head, a circulation flow path is formed in a straight nozzle flow path substantially perpendicular to the droplet discharge surface of the nozzle plate. In such a structure, particularly when discharging large droplets or driving at high speed, the drawing of the liquid meniscus becomes large and the shape of the meniscus tends to become unstable, and the ejection may become unstable.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a nozzle plate, a droplet discharge head, a droplet discharge device, and a method for manufacturing a nozzle plate in which ejection is stable under a wider range of conditions with respect to the droplet amount and ejection speed.

Means for Solving the Problems

[0006] One aspect of the present invention for solving the above problems is Made of single-crystal siliconA nozzle plate comprising a substrate, a nozzle channel provided through the substrate and having a nozzle opening for ejecting droplets, and a discharge channel for discharging liquid from the nozzle channel, The nozzle channel has a nozzle tapered section in which the channel area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually narrows as it approaches the discharge surface from the substrate where the droplet is discharged. And a straight connecting portion that is continuous with the end of the nozzle tapered portion opposite to the discharge surface, Equipped with, The aforementioned nozzle tapered portion It is formed by four {111} faces, The shape is either pyramidal, conical, or elliptical. The aforementioned straight connecting portion is formed by four {100} surfaces, The aforementioned discharge channel is located in the middle of the nozzle tapered section when viewed from the discharge surface side. Furthermore, the invention described in claim 2 is a nozzle plate described in claim 1, The discharge channel is formed to be located at the corner where the two {100} surfaces of the straight connecting section intersect. Furthermore, the invention described in claim 3 is the nozzle plate described in claim 1, The discharge channel is formed to be located at the boundary of the adjacent nozzle tapered portion. Furthermore, the invention described in claim 4 is a nozzle plate comprising a substrate, a nozzle channel provided through the substrate and having a nozzle opening for ejecting droplets, and a discharge channel for discharging liquid from the nozzle channel, The nozzle flow path comprises one or more nozzle tapered sections, the flow path area, which is a cross-sectional area perpendicular to the droplet discharge direction, gradually narrows as it approaches the discharge surface from which the droplet is discharged from the substrate. The aforementioned discharge channel is provided in the middle of one of the nozzle tapered sections when viewed from the discharge surface side.

[0007] Furthermore, claims 5 The invention described in claim 1 Any one of the four terms from The nozzle plate described above, The shape of the nozzle tapered portion is either pyramidal, conical, or elliptical.

[0008] Furthermore, claims 6 The invention described in claim 1 Any one of the four terms from The nozzle plate described above, The nozzle flow path includes a nozzle straight section that is continuous with the end of the nozzle tapered section on the discharge surface side.

[0009] Furthermore, claims 7 The invention described in the claim 6 The nozzle plate described above, The nozzle straight section has a maximum flow path area that is less than or equal to the flow path area at the end of the nozzle tapered section on the discharge surface side.

[0010] Also, the invention according to claim 8 is the nozzle plate according to claim 1 Any one of the four terms from wherein the distance from the discharge surface to the discharge flow path is 5 μm or more and 200 μm or less.

[0011] 9 Also, the invention according to claim Any one of the four terms from is the nozzle plate according to claim 1 wherein the taper angle, which is the angle between the slope of the nozzle taper portion and an axis parallel to the nozzle central axis, is 15° or more and 75° or less.

[0012] 10 9 Also, the invention according to claim is the nozzle plate according to claim wherein the taper angle is 30° or more and 60° or less.

[0013] 11 9 Also, the invention according to claim is the nozzle plate according to claim

[0017] wherein the nozzle flow path includes a plurality of continuous nozzle taper portions having different taper angles. Any one of the four terms from

[0018] Also, the invention according to claim 12 is a droplet discharge head mounted on a droplet discharge device, which includes the nozzle plate according to claim 1 wherein the nozzle plate according to claim 1 is provided.

[0019] Also, the invention according to claim 13 is a droplet discharge device, which includes the droplet discharge head according to claim 12.

[0019] Also, the invention according to claim 14 is the droplet discharge device according to claim 13, wherein the driving frequency is 30 kHz or more and 100 kHz or less.

[0020] 13 ​The droplet dispensing device described above, The amount of liquid droplets discharged from the nozzle opening is 30 pL or more and 300 pL or less.

[0021] Furthermore, the invention described in claim 16 is a method for manufacturing a nozzle plate of a droplet dispensing head, A first step involves uniformly forming a surface mask layer on the first surface of a single-crystal silicon substrate whose surface crystal orientation is {100} plane, A second step involves forming a circular or polygonal opening pattern, which will serve as a nozzle opening, on the surface mask layer. A third step involves forming a through-hole in the substrate located beneath the opening pattern by dry etching from the surface, A fourth step involves enlarging the through-hole by anisotropic wet etching of the substrate to form a nozzle tapered portion, The method includes a fifth step of forming a discharge channel by performing deep etching by dry etching up to the middle of the nozzle tapered portion.

[0022] Furthermore, the invention described in claim 17 is a method for manufacturing a nozzle plate as described in claim 16, The second step involves forming a nozzle straight section by dry etching partway through the substrate beneath the opening pattern from the surface. A mask layer is formed on the side surface of the nozzle straight section.

[0023] Furthermore, the invention described in claim 18 is a method for manufacturing a nozzle plate as described in claim 16 or 17, The fourth step involves enlarging the through-hole by anisotropic wet etching of the substrate, thereby forming the nozzle tapered portion and the straight connecting portion.

[0024] Furthermore, the invention described in claim 19 is also described in claim 16 or 17 A method for manufacturing a nozzle plate as described above, The first step involves uniformly forming the surface mask layer on the first surface of the substrate and on the second surface which is opposite to the first surface. The fifth step involves removing the discharge channel mask layer from the side and bottom surfaces of the discharge channel. A sixth step is to form an exhaust channel pattern on the surface mask layer on the second surface, A seventh step involves forming the discharge channel by dry etching partway through the substrate beneath the discharge channel pattern from the surface, An eighth step of forming the discharge channel mask layer on the side and bottom surfaces of the discharge channel is performed between the first and second steps. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a nozzle plate, a droplet ejection head, a droplet ejection device, and a method for manufacturing a nozzle plate that enable stable ejection under a wider range of conditions regarding droplet volume and ejection speed. [Brief explanation of the drawing]

[0026] [Figure 1] This is a schematic perspective view of the droplet dispensing device according to this embodiment. [Figure 2] This is a schematic side cross-sectional view of the droplet dispensing head according to this embodiment. [Figure 3A] This is an enlarged plan view showing the nozzle flow path of the nozzle plate according to this embodiment. [Figure 3B] Figure 3A is a cross-sectional view of the nozzle plate along the line IIIB-IIIB. [Figure 4A] This is an enlarged plan view showing the nozzle flow path of a modified nozzle plate. [Figure 4B] Figure 4A is a cross-sectional view of the nozzle plate along the IVB-IVB line. [Figure 5] This is an enlarged plan view showing the nozzle flow path of a modified nozzle plate. [Figure 6] This is a cross-sectional view of a modified nozzle plate. [Figure 7]This is an enlarged plan view showing the nozzle flow path of a modified nozzle plate. [Figure 8] This is a cross-sectional view of a nozzle plate showing the main steps of the manufacturing method of the nozzle plate according to the first embodiment. [Figure 9] This is a cross-sectional view of a nozzle plate showing the main steps of the manufacturing method of the nozzle plate according to the second embodiment. [Figure 10] This is a cross-sectional view of a nozzle plate showing the main steps of the manufacturing method of a nozzle plate according to the third embodiment. [Figure 11] This is a cross-sectional view of a nozzle plate showing the main steps of a method for manufacturing a nozzle plate, including the step of forming a straight section of the nozzle. [Modes for carrying out the invention]

[0027] Preferred embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, components having the same function and configuration will be denoted by the same reference numerals, and their descriptions will be omitted.

[0028] [Droplet discharge device] First, as a droplet ejection device according to this embodiment, we disclose an example configuration of an inkjet recording device 1 equipped with an inkjet head 10, which is a droplet ejection head. In the following explanation, as shown in each figure, the transport direction of the recording medium P in the inkjet recording device 1 will be described as the front-to-back direction, the direction perpendicular to the transport direction on the transport surface of the recording medium P will be described as the left-to-right direction, and the direction perpendicular to the front-to-back and left-to-right directions (ink ejection direction) will be described as the up-and-down direction. The inkjet head 10 will also be described in terms of the direction relative to its state when mounted in the inkjet recording device 1.

[0029] Figure 1 is a schematic perspective view showing an inkjet recording apparatus 1 according to this embodiment. The inkjet recording apparatus 1 transports a recording medium P, such as paper, in the forward and backward direction by a transport unit T, which includes, for example, a transport belt T1 and transport rollers T2, passing through a plurality of units U. Each unit U is equipped with a plurality of inkjet heads 10, and ink of each color is ejected from each inkjet head 10 to print on the recording medium P. The inkjet recording apparatus 1 according to this embodiment can perform stable droplet ejection even with a relatively wide drive frequency range of 10 kHz to 100 kHz. Furthermore, the inkjet recording apparatus 1 according to this embodiment can perform stable droplet ejection even with a relatively wide droplet volume range of 10 pL to 300 pL.

[0030] [Inkjet head] Figure 2 is a schematic side cross-sectional view of one inkjet head 10 as seen from the side. The inkjet head 10 consists of a head chip 11, a common ink chamber 12, a support substrate 13, a wiring member 14, a drive unit 15, etc. Although Figure 2 shows a cross-section of the inkjet head 10 in a plane including the four nozzle openings N, detailed descriptions related to the nozzle flow path 111, which will be described later, have been omitted.

[0031] [Head Tip] The head chip 11 is configured to eject ink from the nozzle opening N. Multiple (four in Figure 2) plate-shaped substrates are stacked on the head chip 11. The lowest plate on the head chip 11 is the nozzle plate 110. The nozzle plate 110 is provided with a plurality of nozzle channels 111 (see Figure 3B) having the structure according to the present invention. Ink is ejected from the nozzle opening N, which is the opening of the nozzle channel 111, substantially perpendicular to the ejection surface Ba, which is the exposed surface of the nozzle plate 110. On the adhesive surface Bb (see Figure 3B), which is the surface of the nozzle plate 110 facing the ejection surface Ba, for example, a piezoelectric plate 120, a diaphragm 130, a spacer substrate 140, and a wiring substrate 150 are bonded and laminated in order toward upward.

[0032] The piezoelectric plate 120, the diaphragm 130, the spacer substrate 140, and the wiring board 150 are provided with ink channels that communicate with the nozzle openings N, and these channels are opened on the exposed side (upper side) of the wiring board 150. A common ink chamber 12 is provided on the exposed surface of the wiring board 150 so as to cover all the openings. The ink stored in the ink chamber forming member (not shown) of the common ink chamber 12 is supplied to each nozzle opening N through the ink channels from the opening in the wiring board 150. Then, a pressure chamber provided so as to penetrate the piezoelectric plate 120 deforms together with the diaphragm 130 due to the displacement (deformation) of the piezoelectric element in the storage section adjacent to the pressure chamber, and a pressure change is applied, causing the ink to be ejected downward as droplets from the nozzle openings N.

[0033] [Nozzle Plate] Figure 3A is an enlarged plan view showing one nozzle channel 111 as seen from the adhesive surface Bb side of the nozzle plate 110. Figure 3B is a cross-sectional view showing one nozzle channel 111 along the line IIIB-IIIB in Figure 3A. As shown in Figure 3B, the nozzle plate 110 is provided on a substrate B with a nozzle channel 111 having a nozzle opening N and a discharge channel C that is continuous with the nozzle channel 111.

[0034] (substrate) Substrate B is, for example, a plate-shaped member made of single-crystal silicon (Si) with a thickness of approximately 100 μm to 725 μm. By using single-crystal silicon as substrate B, the nozzle channel 111 can be processed with high precision during the manufacturing process. Therefore, it is possible to form a nozzle channel 111 with minimal positional errors and variations in shape.

[0035] (Nozzle flow path) The nozzle channel 111 is a through-hole that penetrates from the discharge surface Ba of the substrate B to the adhesive surface Bb. As shown in Figure 3B, for example, the nozzle channel 111 comprises a nozzle opening N, a nozzle straight section 1111, a nozzle tapered section 1112, and a straight connecting section 1113, extending from the discharge surface Ba to the adhesive surface Bb.

[0036] <Nozzle opening> The nozzle opening N is a circular or polygonal hole. The nozzle openings N are arranged in a matrix on the discharge surface Ba side of the substrate B, and the side opposite the discharge surface Ba communicates with the nozzle straight section 1111. The shape of the nozzle opening N can be circular or polygonal. If the shape of the nozzle opening N is circular, for example, the diameter can be approximately 15 μm to 45 μm.

[0037] <Nozzle straight section> As shown in Figure 3B, the nozzle straight section 1111 is formed continuously with the end of the nozzle tapered section 1112 on the discharge surface Ba side. The presence of the nozzle straight section 1111 increases the resistance when ejecting ink from the nozzle opening N, suppressing meniscus vibration and thus stabilizing the meniscus shape.

[0038] In Figure 3B, an example is shown where the flow path area, which is the cross-sectional area in the direction perpendicular to the ink discharge direction (left-right direction in Figure 3B) of the nozzle straight section 1111, is substantially constant in the vertical direction, and its maximum portion is less than or equal to the flow path area at the end of the nozzle tapered section 1112 on the discharge surface Ba side; however, the invention is not limited to this example. In other words, the angle between the surface constituting the nozzle straight section 1111 and the axis L parallel to the nozzle central axis does not have to be 0°. Also, the nozzle straight section 1111 may be composed of multiple surfaces, each having a different angle with the axis L parallel to the nozzle central axis. However, it is preferable that the maximum flow path area of ​​the nozzle straight section 1111 is less than or equal to the flow path area of ​​the end of the nozzle tapered section 1112 on the discharge surface Ba side, as this further enhances the effect of providing the nozzle straight section 1111 in improving meniscus stability.

[0039] Furthermore, the vertical length of the nozzle straight section 1111 (the height of the nozzle straight section 1111) is preferably about 5 μm to 50 μm. Having the height of the nozzle straight section 1111 within this range ensures that appropriate resistance is applied when ejecting the ink.

[0040] <Nozzle tapered section> The nozzle tapered section 1112 has a taper at a substantially constant angle such that the flow path area gradually narrows from the bonding surface Bb towards the discharge surface Ba. By providing the nozzle tapered section 1112 in the nozzle flow path 111, the meniscus shape and ink ejection can be stabilized even when the ink meniscus retracts to the back of the nozzle flow path 111 due to high-speed driving.

[0041] As shown in Figure 3B, the taper angle θ, which is the angle between the inclined surface of the nozzle taper portion 1112 and the axis L parallel to the nozzle central axis, is preferably 15° to 75°, and more preferably 30° to 60°. When the taper angle θ is within this range, the ink meniscus shape is stable, and air bubbles can be easily discharged together with the settled ink pigment.

[0042] <Straight connection section> The straight connecting portion 1113 is continuous with the end of the nozzle tapered portion 1112 on the adhesive surface Bb side and is formed to be substantially perpendicular to the discharge surface Ba.

[0043] (Discharge channel) The discharge channel C is a channel provided to communicate with the nozzle channel 111, and guides air bubbles that are discarded without being ejected from the nozzle opening N along with the settled ink pigment. As shown in Figure 3B, the discharge channel C is formed in the middle of the nozzle tapered portion 1112 when viewed from the ejection surface Ba, and is substantially parallel to the ejection surface Ba.

[0044] Let's describe the nozzle plate 110 in more detail. The substrate B has nozzle tapered sections 1112 formed on four {111} surfaces of the substrate B, and straight connecting sections 1113 formed on four {100} surfaces of the substrate B. Also, as shown in Figure 3A, the discharge channel C is formed to be located at the corner where two {100} surfaces of the straight connecting section 1113 intersect. When the nozzle plate 110 is formed in this way, the ink flow at the end of the straight connecting section 1113 is more likely to be directed towards the discharge channel C, and air bubbles that have accumulated and risen to the surface at the end of the straight connecting section 1113 are more easily discharged together with the settled ink pigment.

[0045] Furthermore, it is preferable that the discharge channel C be formed to be located at the boundary between adjacent nozzle tapered sections 1112, as shown in Figure 5, for example. This is because settled ink pigment tends to accumulate at the boundary between nozzle tapered sections 1112.

[0046] Furthermore, as shown in Figure 3B, it is preferable to connect the discharge channel C to a location where the taper height h, which is the distance from the plane parallel to the discharge surface Ba to the discharge channel C, is between 5 μm and 200 μm, and more preferably to connect the discharge channel C to a location where the taper height h is between 20 μm and 100 μm. When the taper height h is within this range, the meniscus shape of the ink becomes stable. In addition, air bubbles can be easily discharged together with the settled ink pigment. Furthermore, if the nozzle flow path 111 includes a nozzle straight section 1111, the taper height h includes the height of the nozzle straight section 1111.

[0047] Furthermore, as shown in Figure 2, when the nozzle plate 110 is bonded to another plate to form an inkjet head 10, a common discharge channel (not shown) that communicates with a plurality of discharge channels C may be provided on the other plate, and the common discharge channel may be connected to a common ink chamber 12 via a pump (not shown), so that ink circulates between the common ink chamber 12 and the nozzle channel 111.

[0048] Furthermore, although the nozzle plate 110 is assumed to be bonded to the piezoelectric plate 120 in the above description, this is not the only option. In other words, another plate may be provided between the nozzle plate 110 and the piezoelectric plate 120. Also, the method of joining the nozzle plate 110 and the other plate may be either bonding or joining, and is not limited to this method.

[0049] Furthermore, while the above example illustrates a nozzle flow path 111 comprising a nozzle opening N, a nozzle straight section 1111, a nozzle tapered section 1112, and a straight connecting section 1113, the example is not limited to this. As shown in Figure 6, the nozzle flow path 111 only needs to include at least a nozzle opening N and a nozzle tapered section 1112.

[0050] Furthermore, substrate B is not limited to single-crystal silicon; SUS (Steel Use Stainless) or polyimide may also be used.

[0051] Furthermore, although Figure 3A illustrates the case where the nozzle tapered portion 1112 is pyramidal, it is not limited to this. That is, the nozzle tapered portion 1112 may be conical or elliptical conical as shown in Figure 4A, and it is sufficient that the shape of the side cross-section is tapered as shown in Figure 3B.

[0052] Furthermore, Figure 3B illustrates a nozzle flow path 111 in which both ends of a single nozzle tapered section 1112 are continuous with the ends of a nozzle straight section 1111 and a straight connecting section 1113, respectively, but the invention is not limited to this configuration. For example, as shown in Figure 4B, the ends of multiple nozzle tapered sections 1112 with different taper angles θ may be arranged to be continuous with each other. By using such a nozzle flow path 111, the meniscus shape and ink ejection can be made more stable.

[0053] Furthermore, the discharge channel C is formed in the middle of the nozzle tapered section 1112 because the boundary between one nozzle tapered section 1112 and another channel is a step, making the meniscus prone to instability. Therefore, as described above, when multiple nozzle tapered sections 1112 with different taper angles θ are arranged to be continuous within a single nozzle channel 111, it is preferable to avoid providing the discharge channel C at the boundary of the continuous nozzle tapered sections 1112.

[0054] Furthermore, the discharge channel C only needs to be formed in a continuous manner with the end of the nozzle tapered portion 1112 on the adhesive surface Bb side.

[0055] Furthermore, the number of discharge channels C connected to a single nozzle channel 111 is not limited to one; as shown in Figure 7, multiple discharge channels C may be connected. When multiple discharge channels C are connected to a single nozzle channel 111, it becomes easier to discharge air bubbles together with the settled ink pigment. The shape of the discharge channel C is not limited to a straight line as shown in Figure 3A, etc., but may also be curved or diagonal. In addition, it is also possible for the discharge channel C to branch into multiple discharge channels C along the way, or for multiple discharge channels C to merge along the way.

[0056] Furthermore, although the above example illustrates a nozzle plate 110 attached to an inkjet head 10 that ejects ink, the liquid ejected from the nozzle plate 110 is not limited to ink.

[0057] [Effects of the invention] As described above, the nozzle plate 110 according to this embodiment comprises a substrate B, a nozzle channel 111 that penetrates the substrate B and has a nozzle opening N for ejecting droplets, and a discharge channel C for discharging liquid from the nozzle channel 111. The nozzle channel 111 has a nozzle tapered section 1112 in which the channel area, which is a cross-sectional area perpendicular to the direction of droplet ejection, gradually narrows as it approaches the discharge surface Ba from the substrate B, and the discharge channel C is provided in the middle of the nozzle tapered section 1112 when viewed from the discharge surface Ba side. With this configuration, even when ejecting large droplets or performing high-speed operation, the meniscus shape is more easily stabilized by the nozzle tapered section 1112. As a result, injection stability can be improved. In addition, by providing a discharge channel C in the middle of the nozzle tapered section 1112, the settled ink pigment can be more easily raised compared to when the discharge channel is provided in the middle of a nearly vertical ink channel, and can be easily discharged together with air bubbles.

[0058] Furthermore, the nozzle flow path 111 includes a nozzle straight section 1111 that is continuous with the end of the nozzle tapered section 1112 on the discharge surface Ba side. This configuration increases resistance during droplet ejection, suppresses meniscus vibration, and improves meniscus stability, thereby improving injection performance.

[0059] Furthermore, the nozzle straight section 1111 has a maximum flow path area that is less than or equal to the flow path area at the end of the nozzle tapered section 1112 on the discharge surface Ba side. According to this configuration, the effect of improving meniscus stability by providing the nozzle straight section 1111 can be further enhanced.

[0060] Furthermore, in the nozzle plate 110 according to this embodiment, the distance from the discharge surface Ba to the discharge channel C is 5 μm or more and 200 μm or less. This configuration improves meniscus stability, thereby enhancing injection performance. Furthermore, it becomes easier to expel air bubbles along with the settled ink pigment.

[0061] Furthermore, in the nozzle plate 110 according to this embodiment, the taper angle θ, which is the angle between the inclined surface of the nozzle tapered portion 1112 and the axis L parallel to the nozzle central axis, is 15° or more and 75° or less, and more preferably 30° or more and 60° or less. This configuration improves meniscus stability, thereby enhancing injection performance. Furthermore, it becomes easier to expel air bubbles along with the settled ink pigment.

[0062] Furthermore, the nozzle flow path 111 of the nozzle plate 110 according to this embodiment includes a plurality of continuous nozzle tapered sections 1112 with different taper angles θ. This configuration allows for greater meniscus stability and further improves injection stability.

[0063] Furthermore, in the nozzle plate 110 according to this embodiment, the substrate B is made of single-crystal silicon, and the nozzle channel 111 includes a straight communication portion 1113 that is continuous with the end of the nozzle tapered portion 1112 opposite to the discharge surface Ba, the nozzle tapered portion 1112 is formed of four {111} surfaces, and the straight communication portion 1113 is formed of four {100} surfaces. According to this configuration, the nozzle plate 110 can be manufactured with high precision, reducing positional errors and shape variations, thereby improving injection stability.

[0064] Furthermore, the discharge channel C according to this embodiment is formed to be located at the corner where the two {100} surfaces of the straight connecting section 1113 intersect. This configuration makes it easier to collect air bubbles that accumulate at the end of the straight connecting section 1113 and rise to the surface.

[0065] Furthermore, the discharge channel C is formed to be located at the boundary of the adjacent nozzle tapered section 1112. This configuration makes it easier to collect the liquid that accumulates at the boundary of the adjacent nozzle tapered section 1112.

[0066] [Manufacturing method for nozzle plates] [First Embodiment] Next, a manufacturing method for the nozzle plate 110 according to the first embodiment described above will be explained. The method for manufacturing a nozzle plate according to the first embodiment is a method for manufacturing a nozzle plate 110 that includes a nozzle channel 111 in which at least a nozzle opening N and a nozzle tapered portion 1112 are formed, and a discharge channel C. The method for manufacturing a nozzle plate according to the first embodiment proceeds through the first step (S-1) to the fifth step (S-5) shown in Figure 8 and below.

[0067] (1st step) First, as the first step (Figure 8 S-1), a surface mask layer 112 is uniformly formed on the first surface (extrusion surface Ba) of a single-crystal silicon substrate B whose surface crystal orientation is {100} plane.

[0068] <Surface mask layer> There are no particular restrictions on the material used to form the surface mask layer 112. For example, oxides such as SiO2 (silicon oxide), metal plating with Al (aluminum) or Cr (chromium), or resins can be used to form the surface mask layer 112.

[0069] As for the method of forming the surface mask layer 112, for example, a thermal oxidation method or a CVD (Chemical Vapor Deposition) method can be applied to form the surface mask layer 112 composed of SiO2. Preferably, SiO2 is formed by the thermal oxidation method. This is because SiO2 has good adhesion to Si and has the effect of preventing side etching during anisotropic wet etching, which will be described later.

[0070] The surface mask layer 112 may be a single layer as shown in Figure 8, or it may be a multilayer structure.

[0071] (2nd process) Next, in the second step (Figure 8 S-2), a circular or polygonal opening pattern 113, which will become the nozzle opening N, is formed on the surface mask layer 112.

[0072] Specifically, a resist pattern is first formed on the surface mask layer 112 using a well-known photolithography technique.

[0073] <Resistance Pattern> Positive or negative photoresists can be used to form the resist pattern. Known materials can be used as positive and negative photoresists. For example, ZPN-1150-90 manufactured by Nippon Zeon Co., Ltd. can be used as a negative photoresist. OFPR-800LB and OEBR-CAP112PM manufactured by Tokyo Ohka Kogyo Co., Ltd. can be used as positive photoresists.

[0074] The resist layer is formed by coating it to a predetermined thickness using a spin coater or similar device. Afterward, a pre-baking process is performed at 110°C for 90 seconds.

[0075] To improve adhesion, HMDS (hexamethyldisilazane) treatment may be applied before resist coating. HMDS treatment involves an organic material called hexamethyldisilazane; for example, OAP (hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) can be used. Similar to resist coating, it may be applied using a spin coater, or exposure to hexamethyldisilazane vapor can also be expected to improve adhesion.

[0076] After the resist layer is formed, the resist layer is exposed using a predetermined mask and an aligner or the like. For example, in the case of a contact aligner, the exposure is approximately 50 mJ / cm². 2 This is done with a light intensity of [specified]. Afterwards, the resist is immersed in a developer (for example, NMD-3 manufactured by Tokyo Ohka Kogyo Co., Ltd. for 60 to 90 seconds) to remove the photosensitive portion of the resist layer, thereby forming a resist pattern on the surface mask layer 112.

[0077] After the resist pattern is formed, the surface mask layer 112 is dry-etched (DE1) using the resist pattern as a mask to form an opening pattern 113. After the opening pattern 113 is formed, the resist pattern is removed.

[0078] <Dry etching> Dry etching (DE1) can be performed using dry etching equipment such as RIE (Reactive Ion Etching) equipment or ICP (Inductively Coupled Plasma)-RIE etching equipment, which employs an inductively coupled discharge method. Process gases such as CHF3 (trifluoromethane) and CF4 (tetrafluoride methane) can also be used.

[0079] For example, using the RIE-100C dry etching system manufactured by Samco Corporation, a slit pattern can be formed by etching for a predetermined time under the conditions of a CHF3 gas flow rate of 80 sccm, a pressure of 3 Pa, and an RF power of 90 W.

[0080] <Removal of resist pattern> Furthermore, the resist pattern can be removed by methods such as a wet process using acetone or an acid solution, or a dry process using oxygen plasma.

[0081] (3rd step) Next, in the third step (Figure 8 S-3), a through-hole is formed in the substrate B located beneath the opening pattern 113 by dry etching (DE2) from the surface.

[0082] In this case, dry etching (DE2) can be performed using an ICP-RIE etching apparatus that employs an inductively coupled plasma discharge method.

[0083] Furthermore, by using the Bosch process, which involves cyclically repeating film deposition and etching using process gases such as SF6 (sulfur hexafluoride), C4F8 (cyclobutane octafluoride), and O2 (oxygen), it is possible to form highly accurate, vertical through-holes.

[0084] (4th step) Next, in the fourth step (Figure 8 S-4), the nozzle tapered portion 1112 is formed by enlarging the through hole by anisotropic wet etching (WE1).

[0085] <Anisotropic wet etching> In the fourth step, anisotropic wet etching (WE1), an alkaline aqueous solution such as KOH (potassium hydroxide), TMAH (tetramethylammonium hydroxide), or EDP (ethylenediamine pyrocatechol) is used. Since substrate B is single-crystal silicon, the nozzle tapered portion 1112 becomes a {111} plane with an extremely slow etching rate, and a nozzle tapered portion 1112 with a taper angle θ of 35.3° is formed.

[0086] (5th step) Finally, in the fifth step (Figure 8 S-5), a mask layer is formed at a predetermined location in the middle of the nozzle tapered section 1112. Next, an discharge channel pattern, which will become the discharge channel C, is formed on the mask layer. Furthermore, the substrate B beneath the discharge channel pattern is dry-etched (DE2) to perform deep etching and form the discharge channel C. The mask layer can be formed by spray coating or electrodeposition resist. Furthermore, similar to the second step described above (Figure 8 S-2), the discharge channel pattern can be patterned onto the mask layer using photolithography techniques.

[0087] [Effects of the invention] As described above, according to the manufacturing method of the nozzle plate 110 of the first embodiment, the nozzle tapered portion 1112 is formed by anisotropic wet etching of the single-crystal silicon substrate B. Therefore, compared to the case in which the nozzle tapered portion 1112 is formed by the Bosch process, a nozzle plate 110 can be manufactured without scallop formation and with low surface roughness. As a result, a nozzle plate 110 with excellent meniscus stability and high injection stability can be manufactured.

[0088] Furthermore, since substrate B is single-crystal silicon, microfabrication on the micrometer order can be performed using dry etching and photolithography techniques.

[0089] Furthermore, since etching stops at the {111} plane of the single-crystal silicon, the taper angle θ stabilizes at 35.3°, making it less likely for variations in shape to occur among the multiple nozzle channels 111 in a single nozzle plate 110.

[0090] [Second Embodiment] Next, the manufacturing method of the nozzle plate 110 according to the second embodiment will be explained with reference to Figure 9. Detailed explanations of steps 1 through 3 and 5, which overlap with the manufacturing method of the nozzle plate 110 according to the first embodiment, will be omitted.

[0091] (4th step) In the third step (Figure 9 S-3), through holes are formed by dry etching (DE2). Then, in the fourth step (Figure 9 S-4), anisotropic wet etching (WE2) is used to enlarge the through holes and form the nozzle tapered portion 1112 and the straight connecting portion 1113.

[0092] Specifically, when anisotropic wet etching (WE1) is performed, the etching proceeds with the straight communication portion 1113 remaining, and as time passes, the straight communication portion 1113 recedes in the left-right direction, forming the nozzle tapered portion 1112. Therefore, in the fourth step according to the second embodiment, by performing anisotropic wet etching (WE2) with time control so that it stops earlier than the anisotropic wet etching (WE1) according to the first embodiment, the straight communication portion 1113 can be formed in the nozzle flow path 111.

[0093] [Effects of the invention] According to the manufacturing method of the nozzle plate 110 as described above, a through hole formed from one opening pattern 113 is enlarged for each nozzle flow path 111 to form a nozzle tapered portion 1112 and a straight connecting portion 1113. Therefore, a nozzle plate 110 can be manufactured having a nozzle flow path 111 in which the nozzle tapered portion 1112 and the straight connecting portion 1113 are continuous without misalignment. Such a nozzle plate 110 ensures that the ink flow maintains symmetry and the injection angle is stable. Furthermore, it reduces the likelihood of stagnation in the nozzle flow path 111 and improves bubble removal.

[0094] [Third Embodiment] Next, the manufacturing method of the nozzle plate 110 according to the third embodiment will be explained with reference to Figure 10. Detailed explanations of steps 2 through 4, which overlap with the manufacturing method of the nozzle plate 110 according to the first embodiment, will be omitted.

[0095] (1st step) First, in the first step (Figure 10 S-1), a surface mask layer 112 is uniformly formed on the first surface of a single-crystal silicon substrate B, whose surface crystal orientation is {100} plane, and on the second surface opposite the first surface (i.e., the ejection surface Ba and the bonding surface Bb).

[0096] (6th step) Next, in the sixth step (Figure 10 S-6), a discharge channel pattern 114 is formed on the surface mask layer 112 of the adhesive surface Bb. The discharge channel pattern 114 can be formed using the same material and method as the opening pattern 113 in the second step of the manufacturing method of the nozzle plate 110 according to the first embodiment.

[0097] (7th process, 8th process) Next, in the seventh step (Figure 10 S-7), the substrate B beneath the discharge channel pattern 114 is deep-etched by dry etching (DE2) to form the discharge channel C. Then, in the eighth step (Figure 10 S-8), a discharge channel mask layer 115 is formed on the side and bottom surfaces of the discharge channel C, and the surface mask layer 112 formed on the adhesive surface Bb is removed. The discharge channel mask layer 115 can be formed using the same material and method as the surface mask layer 112. The surface mask layer 112 can be removed by etching using an RIE apparatus or the like until it is completely removed. However, because the discharge channel mask layer 115 is located on the side walls and bottom, it is more difficult to remove than the surface mask layer 112.

[0098] (2nd process, 3rd process, 4th process) Next, the second step (Figure 10 S-2) to the fourth step (Figure 10 S-4) are carried out in the same manner as in the first embodiment described above. In the second step (Figure 10 S-2), an opening pattern 113 is formed by dry etching (DE1) on the surface mask layer 112 on the discharge surface Ba side. In the third step (Figure 10 S-3), through holes are formed by dry etching (DE2) the substrate B beneath the opening pattern 113. In the fourth step (Figure 10 S-4), the through-hole is enlarged by anisotropic wet etching (WE1) to form the nozzle tapered portion 1112. At this time, the progress of anisotropic wet etching (WE1) is suppressed in the discharge channel mask layer 115, so the discharge channel C formed in the seventh step (Figure 10 S-7) remains unetched.

[0099] (5th step) Finally, in the fifth step (Figure 10 S-5), the remaining discharge channel mask layer 115 in the discharge channel C is removed, and the nozzle tapered portion 1112 and the discharge channel C are connected.

[0100] [Effects of the invention] As described above, according to the manufacturing method of the nozzle plate 110 according to the third embodiment, the discharge channel C can be formed on the adhesive surface Bb of the flat substrate B by forming the discharge channel pattern 114 and performing dry etching (DE2). Therefore, compared to the case where a mask layer is formed on the nozzle tapered portion 1112 and dry etching (DE2) is performed, processing is easier and the nozzle plate 110 can be manufactured with good dimensional accuracy. In addition, it becomes easier to maintain parallelism between the discharge channel C and the discharge surface Ba.

[0101] Although not shown in Figure 10, in the fourth step (Figure 10 S-4) of the manufacturing method for the nozzle plate 110 according to the third embodiment, the straight communication portion 1113 may be formed in the nozzle channel 111 by performing anisotropic wet etching (WE2) with time control, similar to the fourth step (Figure 9 S-4) according to the second embodiment.

[0102] Furthermore, although this is not described in the manufacturing method of the nozzle plate 110 according to the first to third embodiments, as shown in Figure 11, in the second step (Figure 11 S-2), the substrate B below the opening pattern 113 may be partially deep-etched by dry etching (DE2) to form the nozzle straight portion 1111, and a mask layer may be provided on the side surface of the nozzle straight portion 1111. By doing so, the nozzle straight portion 1111 will remain unetched during the anisotropic wet etching (WE1 or WE2) in the fourth step (Figure 11 S-4), and a nozzle channel 111 with the nozzle straight portion 1111 can be formed.

[0103] Furthermore, by performing dry etching (DE2) while changing the processing conditions (e.g., time, power, pressure, gas flow rate, etc.), a nozzle straight section 1111 can be formed, which is composed of multiple surfaces that each make a different angle with an axis L parallel to the nozzle's central axis.

[0104] Furthermore, a protective film may be formed on the nozzle plate 110 for long-term use in ink ejection. In this case, after the fifth step, a step is performed to form a protective film that covers the surface, including the inside of the nozzle channel 111.

[0105] As a protective film, any material that does not dissolve upon contact with the ink should be used. For example, metal oxide films (tantalum pentoxide, hafnium oxide, niobium oxide, titanium oxide, zirconium oxide, etc.), metal silicate films containing silicon in the metal oxide film (tantalum silicate, hafnium silicate, niobium silicate, titanium silicate, zirconium silicate, etc.), or the materials used to form the mask layer can be selected and used. Alternatively, organic films such as polyimide, polyamide, and parylene may be used as the protective film. The thickness of the protective film is not particularly limited, but can be, for example, 0.05 μm to 20 μm. [Examples]

[0106] Next, the results of evaluating preferred configurations for examples and comparative examples of the present invention will be described. The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0107] [Create a sample] A nozzle plate 110 with a thickness of 300 μm and having 1000 nozzle channels 111 that satisfy the conditions of each of the following embodiments and comparative examples is joined with other plates to form an inkjet head 10, and the inkjet head 10 is mounted in an inkjet recording device 1.

[0108] (Example 1) A conical nozzle tapered section 1112 with a taper angle θ of 45° was formed on a stainless steel substrate B using a laser. Then, a discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba, such that the taper height h was 100 μm. The nozzle opening N was formed to be circular with a diameter of 40 μm.

[0109] (Example 2) A nozzle straight section 1111 with a height of 10 μm and a diameter of 40 μm is formed to be continuous with the end of the nozzle tapered section 1112 on the discharge surface Ba side. Other conditions are the same as in Example 1.

[0110] (Example 3) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 4 μm. Other conditions are the same as in Example 1. (Example 4) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 5 μm. Other conditions are the same as in Example 1. (Example 5) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 19 μm. Other conditions are the same as in Example 1. (Example 6) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 20 μm. Other conditions are the same as in Example 1. (Example 7) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 100 μm. Other conditions are the same as in Example 1. (Example 8) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 101 μm. Other conditions are the same as in Example 1. (Example 9) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 200 μm. Other conditions are the same as in Example 1. (Example 10) A discharge channel C was formed at a point in the middle of the nozzle tapered section 1112, as viewed from the discharge surface Ba side, such that the taper height h is 201 μm. Other conditions are the same as in Example 1. (Example 11) The nozzle tapered portion 1112 was formed such that the taper angle θ was 76°. Other conditions are the same as in Example 1. (Example 12) The nozzle tapered portion 1112 was formed so that the taper angle θ was 75°. Other conditions are the same as in Example 1. (Example 13) The nozzle tapered portion 1112 was formed such that the taper angle θ was 61°. Other conditions are the same as in Example 1. (Example 14) The nozzle tapered portion 1112 was formed so that the taper angle θ was 60°. Other conditions are the same as in Example 1. (Example 15) The nozzle tapered portion 1112 was formed so that the taper angle θ was 30°. Other conditions are the same as in Example 1. (Example 16) The nozzle tapered portion 1112 was formed so that the taper angle θ was 29°. Other conditions are the same as in Example 1. (Example 17) The nozzle tapered portion 1112 was formed so that the taper angle θ was 15°. Other conditions are the same as in Example 1. (Example 18) The nozzle tapered portion 1112 was formed so that the taper angle θ was 14°. Other conditions are the same as in Example 1.

[0111] (Example 19) On a single-crystal silicon substrate B, a square pyramidal nozzle tapered section 1112 with a taper angle θ of 35.3° and formed by four {111} faces, and a straight connecting section 1113 formed by four {100} faces were formed by anisotropic wet etching. Then, a discharge channel C was formed at a point in the middle of the nozzle tapered section 1112 as viewed from the discharge surface Ba, such that the taper height h is 100 μm. The nozzle opening N was formed to be a square shape with sides of 40 μm.

[0112] Furthermore, in this embodiment 19, two nozzle plates 110 were prepared: one with a discharge channel C formed at the corner of the two {100} faces of the straight communication section 1113, as shown in Figure 3A, and another with a discharge channel C formed at the boundary of the adjacent nozzle tapered section 1112, as shown in Figure 5.

[0113] (Comparative Example 1) A stainless steel substrate B, on which a 10 μm long straight connecting section 1113 was formed using a laser, was bonded to another plate on which a discharge channel C was formed. In other words, the nozzle plate 110 of Comparative Example 1 does not have a nozzle tapered portion 1112 in the nozzle flow path 111. Also, the discharge flow path C is formed in a plate other than the nozzle plate 110. (Comparative Example 2) A stainless steel substrate B, on which a conical nozzle taper portion 1112 with a taper angle θ of 45° was formed using a laser, was bonded to another plate on which a discharge channel C was formed. In other words, in Comparative Example 2, the nozzle plate 110 has a nozzle tapered portion 1112 formed in the nozzle flow path 111, but the discharge flow path C is not formed in the middle of the nozzle tapered portion 1112 when viewed from the discharge surface Ba side, but is formed at the boundary portion.

[0114] The following tests 1-2 were performed using an inkjet recording device 1 equipped with an inkjet head 10 having the nozzle plates 110 of the above Examples 1-19 and Comparative Examples 1-2.

[0115] [Test 1. Upper speed limit test for meniscus stability] A water-based ink with a viscosity of approximately 5 cP at room temperature was filled into the inkjet head 10, and the ink was ejected from a drive frequency of 40 kHz while increasing the ejection speed from 5 m / s so that the amount of ink droplet ejected from the nozzle opening N was 10 pL. The ejection speed at which the meniscus became unstable and ejection failures occurred in 5 or more of the 100 nozzle openings N was measured. The evaluation was as follows: "◎◎" if the ejection speed was 12 m / s or higher, "◎" if it was less than 12 m / s and 11 m / s or higher, "〇" if it was less than 11 m / s and 10 m / s or higher, "△" if it was less than 10 m / s and 9 m / s or higher, and "×" if it was less than 9 m / s and 7 m / s or higher.

[0116] [Test 2. Nozzle clogging test during circulation] A water-based white ink with a viscosity of approximately 5 cP at room temperature and a high specific gravity that makes it prone to sedimentation and aggregation was circulated through the inkjet head 10. An injection test was performed for 60 minutes at an injection speed of 6 m / s, with a drive frequency of 10 kHz and an ink droplet volume of 10 pL ejected from the nozzle opening N. The number of nozzle openings N out of 1000 that experienced injection failure due to ink clogging was then measured. The evaluation was as follows: "◎" if the number of nozzle openings N with injection failure was 0, "〇" if it was 1, "△" if it was 2 or 3, and "×" if it was 4 or more.

[0117] The results of Test 1-2 are shown in Table I.

[0118] [Table 1]

[0119] In Test 2, when the discharge channel C was formed at the corner where the two {100} surfaces of the straight connecting section 1113 intersect in Example 19, the result was "○", and the floating bubbles were well discharged. Also, when the discharge channel C was formed at the boundary of the adjacent nozzle tapered section 1112 in Example 19, the result was "◎".

[0120] [evaluation] Comparing Examples 1-19 with Comparative Example 1, it can be seen that by providing a nozzle tapered portion 1112 in the nozzle flow path 111 of the nozzle plate 110, meniscus stability can be improved, and therefore the upper limit injection speed can also be increased. Furthermore, comparing Examples 1-19 with Comparative Example 2, it can be seen that by providing a discharge channel C in the middle of the nozzle tapered section 1112 when viewed from the discharge surface Ba side, air bubbles can be easily discharged from the nozzle channel 111 along with the settled ink pigment, making ink clogging at the nozzle opening N less likely to occur.

[0121] In particular, comparing Example 1 and Example 2, it can be seen that by providing a nozzle straight section 1111 in the nozzle flow path 111, meniscus stability can be further improved and the upper limit of injection speed can also be increased. This is because the resistance applied when ejecting ink from the nozzle opening N increases, suppressing meniscus vibration.

[0122] Furthermore, comparing Examples 3-10, the preferred taper height h is 5 μm to 200 μm, and the more preferred taper height h is 20 μm to 100 μm. It can be seen that the upper limit injection velocity can be increased by having the taper height h within this range.

[0123] Furthermore, comparing Examples 11-18, the preferred taper angle θ is 15° to 75°, and the more preferred taper angle θ is 30° to 60°. It can be seen that having the taper angle θ within this range allows for a higher injection limit speed. It can also be seen that it becomes easier to circulate air bubbles together with the settled ink pigment, making nozzle clogging less likely.

[0124] Furthermore, comparing Example 1 and Example 19, it can be seen that the substrate B may be single-crystal silicon or SUS. Also, it can be seen that the cross-sectional shape of the nozzle tapered portion 1112 and the shape of the nozzle opening N are not particularly limited.

[0125] Next, the following tests 3-4 were performed using an inkjet recording device 1 equipped with an inkjet head 10 having the nozzle plate 110 of Example 1 and Comparative Example 1 described above.

[0126] [Test 3. Suitable drive frequency test] The upper limit speed test for meniscus stability shown in Test 1 was performed while varying the drive frequency of the inkjet recording device 1 from 10 kHz to 100 kHz. The evaluation criteria are the same as for Test 1.

[0127] [Test 4. Test for suitable droplet volume] The upper limit speed test for meniscus stability shown in Test 1 was performed while varying the amount of liquid droplets discharged from the nozzle opening N from 10 pL to 300 pL. The evaluation criteria are the same as for Test 1.

[0128] The results of Test 3 and Test 4 are shown in Tables II and III, respectively.

[0129] [Table 2]

[0130] [Table 3]

[0131] [evaluation] As shown in Table II, an inkjet recording device 1 equipped with a conventional inkjet head 10 having a nozzle plate 110 could not effectively eject droplets unless the drive frequency was set to 20 kHz or less. However, it can be seen that an inkjet recording device 1 equipped with an inkjet head 10 having a nozzle plate 110 according to this embodiment can effectively eject droplets even when the drive frequency is increased to at least 100 kHz.

[0132] Furthermore, as shown in Table III, an inkjet recording device 1 equipped with a conventional inkjet head 10 having a nozzle plate 110 could not perform effective droplet ejection unless the amount of droplet ejected from the nozzle opening N was set to 20 pL or less. However, it can be seen that an inkjet recording device 1 equipped with an inkjet head 10 having a nozzle plate 110 according to this embodiment can perform effective droplet ejection even when the amount of droplet ejected from the nozzle opening N is increased to 300 pL. [Industrial applicability]

[0133] The present invention can be used in a nozzle plate, droplet ejection head, droplet ejection device, and a method for manufacturing a nozzle plate, which provides stable ejection under a wider range of conditions regarding droplet volume and ejection speed. [Explanation of Symbols]

[0134] 1. Droplet ejection device (inkjet recording device) 10. Droplet ejection head (inkjet head) 110 Nozzle Plate 111 Nozzle flow path 1111 Nozzle Straight Section 1112 Nozzle tapered section 1113 Straight connecting section 112 Surface mask layer 113 Opening Patterns 114 Discharge channel patterns 115 Discharge channel mask layer B substrate Ba First surface (discharge surface) Bb second side (adhesive side) C Discharge channel N Nozzle opening L: An axis parallel to the nozzle's central axis. θ Taper angle DE1, DE2 dry etching WE1, WE2 Anisotropic Wet Etching

Claims

1. A nozzle plate comprising a substrate made of single-crystal silicon, a nozzle channel provided through the substrate and having a nozzle opening for ejecting droplets, and a discharge channel for discharging liquid from the nozzle channel, The nozzle flow path comprises a nozzle tapered section in which the flow path area, which is a cross-sectional area perpendicular to the droplet discharge direction, gradually narrows as it approaches the discharge surface from which the droplets of the substrate are discharged, and a straight connecting section that is continuous with the end of the nozzle tapered section opposite to the discharge surface. The nozzle tapered portion is formed by four {111} surfaces, and its shape is either pyramidal, conical, or elliptical. The straight connecting portion is formed by four {100} surfaces, The nozzle plate is characterized in that the discharge channel is provided in the middle of the nozzle tapered portion when viewed from the discharge surface side.

2. The nozzle plate according to claim 1, wherein the discharge channel is formed to be located at the corner where the two {100} surfaces of the straight connecting portion intersect.

3. The nozzle plate according to claim 1, wherein the discharge channel is formed to be located at the boundary of the adjacent nozzle tapered portion.

4. A nozzle plate comprising a substrate, a nozzle channel provided through the substrate and having a nozzle opening for discharging droplets, and a discharge channel for discharging liquid from the nozzle channel, The nozzle flow path comprises one or more nozzle tapered sections, the flow path area, which is a cross-sectional area perpendicular to the droplet discharge direction, gradually narrows as it approaches the discharge surface from which the droplet is discharged from the substrate. The discharge channel is a nozzle plate provided in the middle of one of the nozzle tapered sections when viewed from the discharge surface side.

5. The nozzle plate according to any one of claims 1 to 4, wherein the shape of the nozzle tapered portion is pyramidal, conical, or elliptical cone.

6. The nozzle plate according to any one of claims 1 to 4, wherein the nozzle flow path comprises a nozzle straight portion continuous with the end of the nozzle tapered portion on the discharge surface side.

7. The nozzle plate according to claim 6, wherein the nozzle straight portion has a maximum flow path area that is less than or equal to the flow path area at the end of the nozzle tapered portion on the discharge surface side.

8. The nozzle plate according to any one of claims 1 to 4, wherein the distance from the discharge surface to the discharge channel is 5 μm or more and 200 μm or less.

9. The nozzle plate according to any one of claims 1 to 4, wherein the taper angle, which is the angle between the inclined surface of the nozzle taper portion and the axis parallel to the nozzle central axis, is 15° or more and 75° or less.

10. The nozzle plate according to claim 9, wherein the taper angle is 30° or more and 60° or less.

11. The nozzle plate according to claim 9, wherein the nozzle flow path comprises a plurality of continuous nozzle tapered portions having different taper angles.

12. A droplet dispensing head mounted on a droplet dispensing device, A droplet dispensing head comprising a nozzle plate according to any one of claims 1 to 4.

13. A droplet dispensing device, A droplet dispensing device comprising the droplet dispensing head described in claim 12.

14. The droplet dispensing device according to claim 13, wherein the driving frequency is 30 kHz or more and 100 kHz or less.

15. The droplet dispensing device according to claim 13, wherein the amount of droplets discharged from the nozzle opening is 30 pL or more and 300 pL or less.

16. A method for manufacturing a nozzle plate of a droplet dispensing head, A first step involves uniformly forming a surface mask layer on the first surface of a single-crystal silicon substrate whose surface crystal orientation is {100} plane, A second step involves forming a circular or polygonal opening pattern, which will serve as a nozzle opening, on the surface mask layer. A third step involves forming a through-hole in the substrate located beneath the opening pattern by dry etching from the surface, A fourth step involves enlarging the through-hole by anisotropic wet etching of the substrate to form a nozzle tapered portion, A method for manufacturing a nozzle plate, comprising a fifth step of forming a discharge channel by performing deep etching by dry etching up to the middle of the nozzle tapered portion.

17. The second step involves forming a nozzle straight section by dry etching partway through the substrate beneath the opening pattern from the surface. The method for manufacturing a nozzle plate according to claim 16, wherein a mask layer is formed on the side surface of the nozzle straight portion.

18. The method for manufacturing a nozzle plate according to claim 16 or 17, wherein the fourth step involves enlarging the through-hole by anisotropic wet etching of the substrate to form the nozzle tapered portion and the straight connecting portion.

19. The first step involves uniformly forming the surface mask layer on the first surface of the substrate and on the second surface which is opposite to the first surface. The fifth step involves removing the discharge channel mask layer from the side and bottom surfaces of the discharge channel. A sixth step involves forming a discharge channel pattern on the surface mask layer on the second surface, which will serve as the discharge channel. A seventh step involves forming the discharge channel by dry etching partway through the substrate beneath the discharge channel pattern from the surface, A method for manufacturing a nozzle plate according to claim 16 or 17, wherein an eighth step of forming the discharge channel mask layer on the side surface and bottom surface of the discharge channel is performed between the first step and the second step.

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