Liquid dispensing head

Abstract

To provide a liquid discharge head that ensures the strength of the flow path and improves discharge performance. [Solution] A liquid discharge head according to one embodiment comprises a plurality of flow path substrates having openings or grooves that constitute a flow path including a pressure chamber communicating with a nozzle and a resistance flow path communicating with the pressure chamber, and at least one of the flow path substrates has a first reinforcing wall portion in the pressure chamber, and the distance between one end of the first reinforcing wall portion and the edge of the nozzle is 75 μm to 175 μm.

Description

Technical Field

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[0001] Embodiments of the present invention relate to a liquid ejection head.

Background Art

[0002] In a liquid ejection head such as an inkjet head, a diaphragm is deformed by using an actuator composed of a piezoelectric body such as PZT (lead zirconate titanate), and the pressure chamber facing the diaphragm is deformed to eject ink from a nozzle communicating with the pressure chamber. The liquid ejection head includes a plurality of actuators joined to the diaphragm and a flow path portion that forms a plurality of pressure chambers facing the diaphragm and flow paths communicating with the pressure chambers. In the flow path portion of such an inkjet head, there is a type in which a plurality of flow path substrates having slits of a predetermined shape are laminated to form the flow path portion. When a thin plate is used to provide viscous resistance to the ink in the flow path portion, it is difficult to ensure strength and it is also difficult to ensure the positional accuracy of bonding.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a liquid ejection head that can ensure the strength of the flow path portion and improve the ejection performance.

Means for Solving the Problems

[0005] A liquid discharge head according to one embodiment comprises a plurality of flow path substrates, each having an opening or groove that constitutes a flow path including a pressure chamber communicating with a nozzle and a resistance flow path communicating with the pressure chamber, wherein at least one of the flow path substrates has a first reinforcing wall portion within the pressure chamber, and the distance between one end of the first reinforcing wall portion and the edge of the nozzle is 75 μm to 175 μm. [Brief explanation of the drawing]

[0006] [Figure 1] A cross-sectional view showing a part of the configuration of an inkjet head according to the first embodiment. [Figure 2] A cross-sectional view showing a part of the configuration of the inkjet head. [Figure 3] A plan view showing the configuration of multiple rows of the first channel substrate of the inkjet head. [Figure 4] A plan view showing the configuration of one row of the first channel substrate of the inkjet head. [Figure 5] A plan view showing the configuration of multiple rows of the second flow channel substrate of the inkjet head. [Figure 6] A plan view showing the configuration of one row of the second flow channel substrate of the inkjet head. [Figure 7] This is an explanatory diagram showing the location of the reinforcing wall portion of the inkjet head. [Figure 8] This diagram illustrates the relationship between the distance from the nozzle to the reinforcing wall in the inkjet head and AL (Acid Alt). [Figure 9] This diagram illustrates the relationship between the distance from the nozzle to the reinforcing wall of the inkjet head, the ejection speed, and the droplet volume. [Figure 10] This diagram illustrates the distance from the nozzle to the reinforcing wall of the inkjet head, as well as the variations in velocity and volume between channels. [Figure 11] This is an explanatory diagram showing the location of the reinforcing wall portion of the inkjet head. [Figure 12] This diagram illustrates the distance from one end of the reinforcing wall in the inkjet head, as well as the variation in velocity and volume between channels. [Figure 13]An explanatory diagram showing the position of the second reinforcing wall portion of an inkjet head according to another embodiment. [Figure 14] This diagram illustrates the distance from the resistance channel of the reinforcing wall in the inkjet head, as well as the variations in velocity and volume between channels. [Modes for carrying out the invention]

[0007] The inkjet head 1, which is a liquid ejection head according to the first embodiment, will be described below with reference to Figures 1 to 14. Figure 1 is a cross-sectional view showing a part of the configuration of the inkjet head 1 according to the first embodiment, and Figure 2 is a cross-sectional view showing a part of the configuration of the inkjet head 1. Figure 3 is a plan view of multiple rows of the first flow channel substrate of the inkjet head 1, and Figure 4 is a plan view showing the configuration of one row of the first flow channel substrate. Figure 5 is a plan view of multiple rows of the second flow channel substrate, and Figure 6 is a plan view showing the configuration of one row of the second flow channel substrate. Figures 7 to 10 are explanatory diagrams showing the distance from the nozzle to the first reinforcing wall portion of the second flow channel substrate, and the characteristics of AL, ejection speed, and ejection volume. Figures 11 and 12 are explanatory diagrams showing the distance between the first reinforcing wall portion of the second flow channel substrate and one end which is the nozzle-side end of the resistance flow channel, and the characteristics of ejection speed and ejection volume. Figures 13 and 14 are explanatory diagrams showing the distance from the resistance flow channel to the second reinforcing wall portion of the second flow channel substrate, and the characteristics of ejection speed and ejection volume. In the figures, arrows X, Y, and Z indicate three mutually orthogonal directions. In this embodiment, X is the parallel direction of the nozzle 51 and pressure chamber 31, Y is the extension direction (unidirectional), and Z is along the axial direction of the nozzle. For explanatory purposes, the components in each figure are enlarged, reduced, or omitted as appropriate.

[0008] As shown in Figures 1 and 2, the inkjet head 1 comprises an actuator unit 20, a diaphragm 30, a flow channel member 40 as a flow channel unit having a plurality of flow channel substrates 401, 402, a nozzle plate 50 as a nozzle unit having a plurality of nozzles 51, and a manifold 47 as a structural unit. As an example, in this embodiment, the inkjet head 1 shows an example where the stacking direction of the piezoelectric layer 211, the vibration direction of the piezoelectric element 21, and the vibration direction of the diaphragm 30 are all aligned with the Z direction. In this embodiment, on the back side of the nozzle plate 50, a flow channel structure is formed by the diaphragm 30 and the flow channel member 40 to form an ink flow channel 35 within the head 1. The inkjet head 1 is a circulating type that circulates liquid in a predetermined flow channel including a pressure chamber, for example. The inkjet head 1 is installed in a liquid ejection device such as an inkjet recording device.

[0009] For example, the inkjet head 1 is a side-shooter type four-row integrated head having two sets of head bodies, each having a pair of actuator units 20. In other words, in the inkjet head 1, four rows of nozzles are formed, each containing multiple nozzles 51 arranged in a parallel direction.

[0010] The actuator section 20 comprises, for example, a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22, which are made of piezoelectric material and arranged alternately along the row direction, and a piezoelectric structure section 26 that integrally connects these plurality of piezoelectric elements 21 and 22. In this embodiment, a nozzle 51 is provided at the center of the extension direction of the actuator section 20, and the actuator section 20 has a structure that is symmetrical on one side and the other side with respect to the nozzle 51. For example, the actuator section 20 is joined to a rectangular base.

[0011] In the actuator unit 20, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are arranged in parallel in the parallel direction at a constant interval. As an example, both the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are configured in the shape of a rectangular parallelepiped column with the same outer shape. The actuator unit 20 is divided into a plurality by a plurality of grooves 23, and the plurality of driving piezoelectric elements 21 and non-driving piezoelectric elements 22 are formed by arranging them side by side in the column direction at the same pitch.

[0012] For example, in a plan view seen from the Z direction which is the axial direction of the nozzle 51, both the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are configured in a rectangular shape such that the short side direction is along the column direction of the element row and the long side direction is along the extending direction orthogonal to the column direction and the Z direction.

[0013] The driving piezoelectric elements 21 are arranged at positions respectively facing a plurality of pressure chambers 31 formed in the flow path member 40 in the Z direction. As an example, the central positions in the column direction and the extending direction of the driving piezoelectric elements 21 and the central positions in the column direction and the extending direction of the pressure chambers 31 are arranged side by side in the Z direction.

[0014] The non-driving piezoelectric elements 22 are arranged at positions respectively facing the partition walls 42 formed in the flow path member 40 in the Z direction. As an example, the central positions in the column direction and the extending direction of the non-driving piezoelectric elements 22 and the central positions in the column direction and the extending direction of the partition walls 42 are arranged side by side in the Z direction.

[0015] For example, the laminated piezoelectric member constituting the actuator unit 20 is formed by laminating and sintering sheet-like piezoelectric materials. The actuator unit 20 forms a plurality of piezoelectric elements formed in a rectangular column shape at a predetermined interval by dicing the laminated piezoelectric member from one end face to form the grooves 23. Then, electrodes and the like are provided on the formed plurality of columnar elements, and a plurality of driving piezoelectric elements 21 and a plurality of non-driving piezoelectric elements 22 arranged alternately are formed. The plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are arranged alternately in parallel with each other across the grooves 23 in the column direction.

[0016] The piezoelectric members constituting the driving piezoelectric element 21 and the non-driving piezoelectric element 22 are, for example, laminated piezoelectric bodies. The driving piezoelectric element 21 and the non-driving piezoelectric element 22 include a plurality of laminated piezoelectric layers 211 and internal electrodes 221 and 222 formed on the main surfaces of each piezoelectric layer 211. As an example, the driving piezoelectric element 21 and the non-driving piezoelectric element 22 have the same laminated structure. And the driving piezoelectric element 2 and the non-driving piezoelectric element 22 include external electrodes 223 and 224 formed on the surface.

[0017] The piezoelectric layer 211 is composed of a piezoelectric material such as a PZT (lead zirconate titanate) - based or lead - free KNN (sodium potassium niobate) - based material. The plurality of piezoelectric layers 211 are laminated in the thickness direction along the lamination direction. For example, in the present embodiment, the thickness direction and the lamination direction of the piezoelectric layer 211 are arranged along the vibration direction (Z direction).

[0018] The internal electrodes 221 and 222 are conductive films formed in a predetermined shape from a sinterable conductive material such as silver palladium. The internal electrodes, 221 and 222 are formed in a predetermined region on the main surface of each piezoelectric layer 211. The internal electrodes 221 and 222 have different polarities. For example, one of the internal electrodes 221 is formed in a region that reaches one end of the piezoelectric layer 211 but does not reach the other end of the piezoelectric layer 211 in the extending direction (Y direction), which is a direction orthogonal to both the column direction (X direction), which is the arrangement direction of the plurality of driving piezoelectric elements 21 and the plurality of non - driving piezoelectric elements 22, and the vibration direction (Z direction). The other internal electrode 222 is formed in a region that does not reach one end of the piezoelectric layer 211 but reaches the other end of the piezoelectric layer 211 in the extending direction. The internal electrodes 221 and 222 are respectively connected to the external electrodes 223 and 224 formed on the side surfaces of the piezoelectric elements 21 and 22.

[0019] Furthermore, the laminated piezoelectric members constituting the driving piezoelectric element 21 and the non-driving piezoelectric element 22 may further have a dummy layer on either the nozzle plate 50 side or the opposite end, or both. For example, the dummy layer is made of the same material as the piezoelectric layer 211, has electrodes on only one side, and does not deform because no electric field is applied to it. For example, the dummy layer does not function as a piezoelectric body, but serves to fix the actuator unit 20 to the base, or as a polishing surface to achieve precision during or after assembly.

[0020] The external electrodes 223 and 224 are formed on the surfaces of the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22, and are formed by gathering the ends of the internal electrodes 221 and 222. For example, the external electrodes 223 and 224 are formed on one end face and the other end face in the extending direction of the piezoelectric layer 211, respectively. The external electrodes 223 and 224 are deposited using known methods such as plating or sputtering, using materials such as Ni, Cr, and Au. The external electrodes 223 and 224 are different electrodes. The external electrodes 223 and 224 are arranged on different side surfaces of the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22, respectively. Note that the external electrodes 223 and 224 may be routed to different regions within the same side surface of the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22.

[0021] In this embodiment, as an example, the external electrode 223 is an individual electrode and the external electrode 224 is a common electrode. The external electrode 223, which serves as an individual electrode for the multiple driving piezoelectric elements 21 and the multiple non-driving piezoelectric elements 22, has an electrode layer divided by grooves 23 and is arranged independently of each other. The external electrode 224, which serves as a common electrode, has an electrode layer that is connected to each other, for example, on the side surface of the piezoelectric structure 26, and is grounded, for example. The external electrodes 223 and 224 are connected to a drive circuit, for example, via a wiring film. For example, each external electrode 223 and 224 is connected to a control unit 150 via a drive circuit and is configured to be drive-controllable. Note that the arrangement of the common electrode and individual electrodes may be reversed.

[0022] Furthermore, the vibration direction of each piezoelectric element 21, 22 is aligned with the stacking direction, and when an electric field is applied, it is displaced in the d33 direction. Each piezoelectric element 21, 22 has 3 to 50 piezoelectric layers, with each layer having a thickness of 10 μm to 40 μm, and the product of the thickness and the total number of layers being less than 1000 μm.

[0023] In the inkjet head 1, the driving piezoelectric element 21 vibrates when a voltage is applied to the internal electrodes 221 and 222 via the external electrodes 223 and 224. In this embodiment, the driving piezoelectric element 21 vibrates longitudinally along the stacking direction of the piezoelectric body layer 211. Here, longitudinal vibration refers to, for example, "vibration in the thickness direction defined by the piezoelectric constant d33". The driving piezoelectric element 21 displaces the diaphragm 30 and deforms the pressure chamber 31 due to the longitudinal vibration.

[0024] The diaphragm 30 extends along a plane perpendicular to the Z-direction, which is the vibration direction, and is bonded to one side of the piezoelectric layer 211 of the plurality of piezoelectric elements 21, 22 in the direction of vibration, i.e., the side facing the nozzle plate 50. In the Z-direction, which is the vibration direction, the diaphragm 30 faces the plurality of nozzles 51 via the pressure chamber 31. The diaphragm 30 is configured to be deformable, for example. The diaphragm 30 is bonded to the driving piezoelectric element 21 and non-driving piezoelectric element 22 of the actuator unit 20 and the manifold 47. For example, the diaphragm 30 has a vibration region 301 facing the piezoelectric elements 21, 22 and a support region facing the manifold 47. The diaphragm 30 is provided between the flow channel substrate 401 and the actuator unit 20 in the direction of vibration. The diaphragm 30 is arranged on top of the plurality of flow channel substrates 401, 402 and constitutes a part of the ink flow channel 35.

[0025] The vibration region 301 is, for example, a flat plate shaped such that its thickness direction is the vibration direction of the piezoelectric layer 211. The diaphragm 30 has a surface direction that extends in the direction of the arrangement of the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22. The diaphragm 30 is, for example, a metal plate. The diaphragm 30 has a plurality of vibrating parts that face each pressure chamber 31 and are individually displaceable. The diaphragm 30 is formed by a plurality of vibrating parts being integrally connected.

[0026] For example, the diaphragm 30 is made of nickel or SUS plate, and its thickness along the vibration direction is set to approximately 5 μm to 15 μm. In addition, the vibration region 301 may have folds or steps formed between vibration parts and adjacent parts, or between mutually adjacent vibration parts, so that multiple vibration parts can be easily displaced. The vibration region 301 is deformed by the displacement of the part positioned opposite the driving piezoelectric element 21 due to the extension and compression of the driving piezoelectric element 21. For example, since the diaphragm 30 requires a very thin and complex shape, it is formed by electroforming or the like. The diaphragm 30 is joined to the upper end surface of the actuator part 20 by adhesive or the like.

[0027] The support region of the diaphragm 30 facing the manifold 47 is a plate-shaped member positioned between the manifold 47 and the flow path substrate 401. The diaphragm 30 has a structure that is symmetrical on one side and the other side in the Y direction with respect to the nozzle 51.

[0028] The flow channel member 40 is joined to one side of the diaphragm 30.

[0029] As shown in Figures 1 to 6, the flow channel member 40 comprises a plurality of stacked flow channel substrates 401 and 402. For example, the flow channel member 40 comprises a flow channel substrate 401 as a first flow channel substrate and a flow channel substrate 402 as a second flow channel substrate, stacked together. For example, depending on the viscosity of the ink and the volume to be discharged, a plurality of flow channel substrates 401 and 402 having openings or grooves are joined together with the nozzle plate 50 and the diaphragm 30 to form a desired ink flow channel 35. The plurality of flow channel substrates 401 and 402 are arranged stacked in the stacking direction, and the openings or grooves formed in each flow channel substrate 401 and 402 constitute an ink flow channel 35 including a pressure chamber 31 communicating with a plurality of nozzles 51, a resistance flow channel 341 which is a first individual flow channel, a resistance flow channel 342 which is a second individual flow channel, a first common flow channel section 331, and a second common flow channel section 332. As an example, flow channel substrates 401 and 402 are stacked in order from the diaphragm 30 side, with the flow channel substrate 402 positioned opposite the nozzle plate 50. In this embodiment, as an example, corresponding to each of the multiple nozzles 51, a first individual flow channel, consisting of a resistance flow channel 341 on one side, a pressure chamber 31, and a second individual flow channel, consisting of a resistance flow channel 342 on the other side, are arranged in a line along the Y direction, forming multiple individual liquid chambers 36 extending in the Y direction. Then, on both sides of the multiple individual liquid chambers 36 aligned in the first direction, a first common flow channel section 331 and a second common flow channel section 332 are formed, extending in the first direction.

[0030] The flow path member 40 is positioned between the nozzle plate 50 and the diaphragm 30. The flow path member 40 is formed by stacking and joining together a plurality of flow path substrates 401 and 402 to form a predetermined ink flow path 35 (liquid chamber) which has a plurality of pressure chambers 31, a common flow path section 331 and 332 communicating with a common chamber 32, and a plurality of resistance flow paths 341 and 342 (restriction sections) extending from the common flow path section 331 and 332 to the pressure chambers 31. In other words, the flow path member 40, by stacking a plurality of flow path substrates 401 and 402, constitutes a peripheral wall portion 41 surrounding the ink flow path 35 (liquid chamber) composed of a plurality of pressure chambers 31, a plurality of resistance flow paths 341 and 342 and a common flow path section 331 and 332, a plurality of partition wall portions 42 separating the rows of pressure chambers 31, and a side wall portion 43 separating the plurality of resistance flow paths 341 and 342. For example, the flow channel member 40 constitutes multiple rows of ink flow channels 35 corresponding to the number of nozzles. In Figures 3 and 5, the area for seven rows of pressure chambers 31 (channels) is shown, while in Figures 4 and 6, only the area for one row is shown.

[0031] In other words, the common flow channel section 33 (the upstream common flow channel section 331 and the downstream common flow channel section 332) is formed in multiple rows, and each extends along the parallel direction (X direction) of the nozzles 51, which is perpendicular to the extension direction (Y direction) in which the resistance flow channels 341, 342 and pressure chambers 31 are lined up.

[0032] The first flow channel substrate, the flow channel substrate 401, is joined to the diaphragm 30. The flow channel substrate 401 is a plate-shaped member having the same external shape as the diaphragm 30, and is composed of a metal material including SUS430, or a resin material such as silicon, as an example. The flow channel substrate 401 has a first opening 4011 that forms part of the pressure chamber 31, and a second opening 4012 that forms part of the common flow channel sections 331 and 332. For example, the first opening 4011 is located in the center of the extension direction in which the ink flow channel 35 extends, and the second openings 4012 are located at both ends. The first opening 4011 that constitutes the pressure chamber 31 is divided into multiple rows in the X direction, and beam-like sections 461 are formed between adjacent openings 4011 in the direction of alignment. On the other hand, the openings 4012 that form the common flow channel sections 331 and 332 are connected in multiple rows, and the length in the X direction is larger than that of the first opening 4011. The opening 4012 is divided into sections, for example, seven rows at a time.

[0033] The second channel substrate, channel substrate 402, is laminated on channel substrate 401 and bonded to channel substrate substrate 401. Channel substrate 402 is a plate-shaped member having the same external shape as the diaphragm 30, and is made of a metal material including SUS430 as an example, or a resin material such as silicon. Individual channel channels, namely resistance channels 341 and 342, are formed in channel substrate 402. Channel substrate 402 has a plurality of openings 4021, 4022, and 4023 that are aligned in one direction via reinforcing walls 44 and 45.

[0034] Multiple openings 4021, 4022, and 4023 form openings that penetrate in the thickness direction. Multiple openings 4021 and 4022 are arranged in a unidirectional manner via reinforcing walls 44 and 45. The flow channel substrate 402 is the substrate in which the openings are formed over the longest range in the extension direction among the multiple flow channel substrates 401 and 402. Also, for example, the openings 4021 and 4022 of the flow channel substrate 402 are configured to have a smaller width dimension than the openings 4011 formed on the other substrates 401. The thickness of the multiple flow channel substrates 401 and 402 is set according to conditions such as resistance and flow rate, but in the example shown in Figure 1, the flow channel substrate 402 in which the resistance channels 341 and 342 with small cross-sectional areas are formed is configured to be thinner than the other first flow channel substrate 401.

[0035] The openings 4021 and 4022 are composed of slit-shaped rectangular openings that are long in the Y direction, and are arranged in multiple rows in the direction of alignment. Beam-like sections 462 are formed between multiple adjacent openings 4021 and multiple openings 4022 in the direction of alignment.

[0036] For example, a first opening 4021 is located in the center of the extension direction of the ink flow path 35, second openings 4022 are located at both ends via first reinforcing wall portions 44, and third openings 4023 are located at the other end of each second opening 4022 opposite to the nozzle 51 via second reinforcing wall portions 45. The first opening 4021 that constitutes the pressure chamber 31 and the second openings 4022 that constitute the resistance flow paths 341 and 342 are divided into multiple rows in the X direction, and beam-like portions 462 are formed between adjacent openings 4021 and openings 4022 in the direction of alignment. On the other hand, the openings 4023 that form the common flow path portions 331 and 332 are connected in multiple rows, and the length in the X direction is larger than that of the first openings 4021 and 4022. The openings 4023 are divided into, for example, seven rows each.

[0037] For example, the reinforcing wall sections 44 and 45 are wall-like members that connect the beam-like sections 462 on both sides of the openings 4021 and 4022 in the width direction. In other words, the reinforcing wall sections 44 and 45 partially block and divide the slit-shaped opening of the second flow channel substrate 402, which is long in one direction.

[0038] The first reinforcing wall portion 44 (wall portion) is formed in a region that overlaps with the opening 4011 of the opposing substrate 401, but does not block the nozzle 51. In this embodiment, the first reinforcing wall portions 44 are formed on one side and the other side of the nozzle 51 within the pressure chamber 31. For example, the reinforcing wall portion 44 is positioned between the nozzle 51 and the inlet / outlet of the pressure chamber 31, which is the part where the pressure chamber 31 communicates with the resistance flow paths 341 and 342. Furthermore, the reinforcing wall portion 44 is positioned so as not to overlap with the nozzle 51, at a predetermined distance or more away from the nozzle 51, and in a position that does not block the nozzle 51.

[0039] In other words, the first reinforcing wall section 44 is a connecting wall section that is located within the pressure chamber 31 and spans the beam-like sections 462 in the X direction between elongated slit rows composed of openings 4021 and 4022 aligned in one direction, connecting the beam-like sections 462.

[0040] Furthermore, the second reinforcing wall section 45 is provided at a position opposite to the common flow channel sections 331 and 332. The reinforcing wall section 45 is provided upstream of the inlet of the resistance channel 341 and downstream of the outlet of the downstream resistance channel 342. The second reinforcing wall section 45 is located within the common channel sections 331 and 332 and is a connecting wall that spans the beam-like sections 462 in the X direction between multiple rows of elongated slit-shaped openings 4022 and multiple rows of wider openings 4023, connecting the beam-like sections 462.

[0041] For example, the thickness of the reinforcing wall portions 44 and 45 in the stacking direction is the same as the thickness of the flow channel substrate 402 in the stacking direction. Therefore, it is configured to be the same height as the height of the resistance flow channels 341 and 342.

[0042] The reinforcing walls 44 and 45 are formed, for example, by etching the material while excluding the parts that will become the reinforcing walls 44 and 45 when forming the openings 4021 to 4023. The reinforcing walls 44 and 45 become support members that support the beam-shaped parts 462 of the flow channel substrate 402 by being connected to the multiple beam-shaped parts 462. In other words, the flow channel substrate 402, which is the second flow channel substrate, has the longest flow channel formed thereon and also has the reinforcing walls 44 and 45 as reinforcing walls.

[0043] The reinforcing walls 44 and 45 are positioned to have minimal impact on the ejection performance of the inkjet head 1. In this embodiment, the first reinforcing wall 44 in the pressure chamber 31 is positioned such that the distance L1 from the edge of the nozzle 51 is 75 μm or more. For example, one end of the reinforcing wall 44 in the pressure chamber 31 is located in the range of 75 μm to 175 μm from the edge of the nozzle 51.

[0044] On the other hand, the second reinforcing wall 45, which is provided on the side opposite to the pressure chamber 31 with respect to the resistance flow path 34 (the upstream resistance flow path 341 and the downstream resistance flow path 342), is positioned such that the distance L3 from the other end of the resistance flow path 34 is 200 μm or more.

[0045] Here, Figure 7 is an explanatory diagram showing the arrangement of the first reinforcing wall portion 44, and Figure 8 is a graph showing the relationship between L1, the distance from one end of the first reinforcing wall portion 44 to the edge of the nozzle 51, and AL (Acoustic Length), which is half the natural vibration period determined by the shape of the nozzle and flow path and the physical properties of the ink.

[0046] Figure 8 shows that stable AL can be obtained when the distance of the reinforcing wall portion 44 from the edge of the nozzle 51 is 75 μm or more. In other words, even if the position of the reinforcing wall portion 44 is somewhat varied, stable AL can be obtained, so it is shown that it is good to set the distance of the reinforcing wall portion 44 from the edge of the nozzle 51 to 75 μm or more.

[0047] Furthermore, in the case of single-nozzle drive, the discharge speed and droplet volume are not significantly affected by the position of the reinforcing wall portion 44 of the flow path substrate 402. However, when multiple-channel nozzles 51 are driven, it is conceivable that inter-channel variations in discharge speed and droplet volume may occur depending on the position of the reinforcing wall portion 44.

[0048] Figure 9 shows the relationship between the distance L1 from the edge of the nozzle to one end of the reinforcing wall and the inter-channel variation in discharge velocity and droplet volume. In Figure 9, the variation was calculated as the difference between the maximum and minimum values.

[0049] As shown in Figure 9, the position of the reinforcing wall 44 in the pressure chamber 31 is such that the distance L1 from the edge of the nozzle 51 is 75 μm to 175 μm, thereby suppressing both the variation in discharge velocity and droplet volume between channels. Therefore, in this embodiment, the position of the reinforcing wall 44 in the pressure chamber 31 is set to a position of approximately 75 μm to 175 μm from the edge of the nozzle 51.

[0050] Furthermore, it is preferable that the reinforcing wall portion 44 is positioned such that the distance L2 (Figure 11) between the reinforcing wall portion 44 and one end of the resistance flow path 34 on the pressure chamber side is appropriately large. Figure 12 shows the relationship between the distance L2 from one end of the resistance flow path 34 on the pressure chamber side to the reinforcing wall portion 44 and the inter-channel variations in discharge velocity and droplet volume.

[0051] As shown in Figure 12, if the distance L2 between one end of the resistance channel 34 connected to the pressure chamber 31 and the other end of the first reinforcing wall 44 opposite to the nozzle 51 side is set to approximately 200 μm to 300 μm, it can be seen that variations in discharge velocity and droplet volume between pressure chambers (channels) are suppressed. Therefore, in this embodiment, the distance L2 between the other end of the reinforcing wall 44 on the resistance channel side and one end of the resistance channel 341, i.e., the boundary between the resistance channel 34 and the pressure chamber 31, in the extending direction, is set to a position where they are separated by 200 μm or more.

[0052] Based on the above, when the reinforcing wall portion 44 of the flow path substrate 402 that determines the height of the resistance flow path is provided inside the pressure chamber 31, its position should not be too close to the nozzle 51 or too close to the resistance flow path 34. The position of the reinforcing wall portion 44 inside the pressure chamber 31 should be such that the distance L1 from the edge of the nozzle 51 is 75 μm to 175 μm, and the distance L2 between the reinforcing wall portion 44 and one end of the resistance flow path 341 on the ink supply side is 200 μm or more. This makes it possible to reinforce the flow path substrate while maintaining performance.

[0053] Next, Figures 13 and 14 show the position of the second reinforcing wall portion 45 of the flow channel substrate 402, which is on the opposite side of the pressure chamber 31 across the resistance flow channel 34. Since this reinforcing wall portion 45 is also provided within the same substrate 402, its thickness is the same as the height of the resistance flow channels 341 and 342. Figure 14 shows the relationship between the distance L3 (Figure 13) between the other end of the resistance flow channel 34 and one end of the reinforcing wall portion 45 on the resistance flow channel 34 side, and the variation in droplet velocity and volume between pressure chambers 31 (between channels). According to Figure 14, it is preferable that the distance between the reinforcing wall portion 45 and the resistance flow channel 341 be appropriately separated, and it can be seen that the variation between channels is suppressed when the distance is about 200 μm.

[0054] For example, in this embodiment, the openings 4021, 4022, and 4023 are positioned to overlap at least a portion of the openings 4011 and 4012 of the other flow channel substrate 401, and communicate with these openings 4011 and 4012.

[0055] In the flow channel member 40, multiple pressure chambers 31 are formed by the first openings 4011 and 4021 of multiple flow channel substrates 401 and 402 that are aligned and communicating in the stacking direction. The multiple pressure chambers 31 are spaces formed on one side of the vibration region 301 of the diaphragm 30, and each pressure chamber 31 communicates with a nozzle 51 formed on the nozzle plate 50. In addition, the pressure chambers 31 are closed on the opposite side of the nozzle plate 50 by the diaphragm 30.

[0056] Multiple pressure chambers 31 communicate with common chambers 321 and 322 via resistance passages 341 and 342 and common passage sections 331 and 332. Each pressure chamber 31 holds liquid supplied from common chambers 321 and 322, and the liquid is discharged from the nozzle 51 by deforming due to the vibration of a vibrating plate 30 that forms part of the pressure chamber 31.

[0057] In the flow channel member 40, the second openings 4012 and third openings 4023 of multiple flow channel substrates 401 and 402 that are aligned and communicating in the stacking direction constitute common flow channel sections 331 and 332 on both sides of the pressure chamber in the Y direction.

[0058] The common flow channels 331 and 332 are flow channels that communicate with the other ends of the multiple resistance flow channels 341 and 342 in the flow direction. The common flow channels 331 and 332 are formed, for example, between the diaphragm 30 and the nozzle plate 50 and communicate with the common chamber 32 of the manifold 47.

[0059] Furthermore, in the flow channel member 40, resistance channels 341 and 342 are formed by an opening 4022 in part of the flow channel substrate 402. The resistance channels 341 and 342 connect each pressure chamber 31 with the common flow channel section 331 and 332 and extend in the Y direction, which is the flow direction. The resistance channels 341 and 342 on both sides are configured to have a smaller width dimension perpendicular to the extension direction, which is the flow direction, than the common flow channel section 331 and 332 and the pressure chamber 31, resulting in a narrower cross-section of the flow channel.

[0060] Here, each flow channel substrate 401, 402 has a structure that is symmetrical on one side and the other side in the Y direction with respect to the nozzle 51, and the flow channel lengths and flow channel cross-sectional shapes perpendicular to the Y direction of the resistance flow channels 341, 342 arranged on both sides in the Y direction with respect to the central pressure chamber 31 are configured to be the same. In addition, in the flow channel member 40, the central parts of the beam-shaped portion 461 of the stacked flow channel substrate 401 and the beam-shaped portion 462 of the flow channel substrate 402 form partition walls 42 that separate the multiple pressure chambers 31.

[0061] The partition wall 42 is a wall-like member that separates the multiple pressure chambers 31 in the parallel direction. The partition wall 42 is positioned opposite the non-driven piezoelectric element 22 via the diaphragm 30 and is supported by the non-driven piezoelectric element 22. Multiple partition wall sections 42 are provided at the same pitch as the parallel pitch of the multiple pressure chambers 31.

[0062] In the flow channel member 40, a side wall portion 43 is formed by a part of the beam-shaped portion 462 of the flow channel substrate 402, separating the multiple resistance flow channels 341, 342.

[0063] The side wall portion 43 is a wall-like member that separates the multiple resistance flow paths 341 and 342 in the direction of alignment. For example, the side wall portion 43 is provided in communication with both sides of the pressure chamber 31. The side wall portion 43 is configured such that the flow resistance of the resistance flow paths 341 and 342 is greater than that inside the pressure chamber 31, and the flow cross-sectional area of ​​the resistance flow paths 341 and 342 is smaller than that inside the pressure chamber 31. Multiple side wall portions 43 are provided at the same pitch as the alignment of the multiple pressure chambers 31.

[0064] In this embodiment, the inkjet head has two head bodies, and each head body is provided with two rows of actuator units 20, each having a nozzle row in which a plurality of nozzles 51 are arranged in the X direction, and a pressure chamber row in which a plurality of pressure chambers 31 are arranged in the X direction. Thus, the inkjet head 1 has a total of four rows of nozzles 51 and actuator units 20.

[0065] The common flow path section 33 includes, for example, a first common flow path section 331 that communicates with one opening of a plurality of pressure chambers 31 formed in the actuator section 20 (the supply-side inlet of the pressure chamber 31), and a second common flow path section 332 that communicates with the secondary-side opening of the plurality of pressure chambers 31 (the discharge-side outlet of the pressure chamber 31).

[0066] Specifically, a first common flow path section 331 extending in the X direction is provided in communication with a plurality of individual flow paths extending in the second direction (Y direction), which are composed of a pressure chamber 31 and resistance flow paths 341, 342, on one end of the individual flow path in the second direction (Y direction), and a second common flow path section 332 extending in the X direction is provided on the other end of the individual flow path.

[0067] The two first common flow channels 331 and the one second common flow channel 332 each communicate with the common chamber 32 in the manifold 47 at both ends in the first direction. For example, the first common flow channels 331 and the second common flow channel 332 are provided with supply ports or discharge ports as connection ports, and these supply ports or discharge ports connect to the common chamber 32 in the manifold 47.

[0068] The nozzle plate 50 is constructed as a rectangular plate with a thickness of approximately 10 μm to 100 μm, made of a metal such as SUS or Ni, or a resin material such as polyimide. The nozzle plate 50 is positioned on one side of the flow path member 40 so as to cover the opening on one side of the pressure chamber 31. The nozzle plate 50 has a plurality of nozzles 51 for discharging droplets. The plurality of nozzles 51 are holes that penetrate the nozzle plate 50 in the thickness direction. The nozzles 51 are arranged in a plurality in the same first direction as the direction in which the pressure chambers 31 are arranged, forming a nozzle row. Each nozzle 51 is provided at a position corresponding to the plurality of pressure chambers 31.

[0069] The manifold 47 is a so-called manifold and is a structure that is joined to the diaphragm 30 together with the piezoelectric elements 21 and 22. The manifold 47 is provided on the side of the diaphragm 30 opposite to the flow channel member 40, and in this embodiment, for example, it is positioned adjacent to the actuator section 20. The manifold 47 constitutes the outer casing of the inkjet head 1. The manifold 47 also forms a liquid flow channel inside. In this embodiment, the manifold 47 is joined to the other side of the diaphragm 30, forming a common chamber 32 between it and the diaphragm 30.

[0070] The common chamber 32 is formed inside the manifold 47. For example, inside the manifold 47, a supply-side common chamber 321 and a discharge-side common chamber 322 are formed. Each common chamber 321 and 322 is provided with a supply port and a discharge port, respectively, and is connected to an external supply pipe and discharge pipe, which in turn connect to a cartridge outside the head.

[0071] For example, common chambers 321 and 322 are connected to the pressure chamber 31 via supply and discharge ports, common flow channels 331 and 332, and resistance flow channels 341 and 342.

[0072] In the inkjet head 1 configured as described above, an ink flow path 35 is formed by the nozzle plate 50, manifold 47, flow path member 40, and diaphragm 30. This flow path 35 includes a plurality of pressure chambers 31 communicating with a plurality of nozzles 51, a plurality of individual liquid chambers 36 each composed of resistance flow paths 341 and 342 communicating with the plurality of pressure chambers 31, and a common liquid chamber 37 composed of common flow path sections 331 and 332 and common chambers 321 and 322 formed in the manifold 47. For example, the common chambers 321 and 322 communicate with the cartridge. Ink is supplied to each pressure chamber 31 in the flow path member 40 through the common chamber 321, or ink discharged from the pressure chambers 31 is recovered to the cartridge through the common chamber 322.

[0073] For example, resistance channels 341 and 342 are arranged on both sides of the pressure chamber 31 in the extending direction, and a common liquid chamber, consisting of a common channel section 33 and a common chamber 32, is arranged continuously at the other end of the resistance channels 341 and 342 in the extending direction.

[0074] All piezoelectric elements 21 are connected by wiring so that a voltage can be applied. In the inkjet head 1, when the control unit 150 applies a driving voltage to electrodes 221 and 222 using a driver IC, the piezoelectric elements 21 to be driven vibrate in the stacking direction, that is, in the thickness direction of each piezoelectric layer 211. In other words, the piezoelectric elements 21 vibrate longitudinally.

[0075] Specifically, the control unit 150 applies a drive voltage to the internal electrodes 221 and 222 of the piezoelectric element 21 to be driven, thereby selectively driving the piezoelectric element 21. By combining the tensile and compressive deformations of the piezoelectric element 21, the control unit 150 deforms the diaphragm 30, changing the volume of the pressure chamber 31, thereby drawing liquid from the common chamber 32 and discharging it from the nozzle 51.

[0076] Furthermore, the ink supplied to the pressure chamber 31 is ejected from the nozzle 51, and is also recovered into the cartridge via the other side's resistance channels 341, 342, the second common channel section 332, and the discharge side's common chamber 322. In other words, in the inkjet head 1, one side in the extension direction is the inflow side (supply side), and the other side is the outflow side (recovery side), and the ink circulates in the ink channel 35.

[0077] The inkjet head 1 according to this embodiment includes piezoelectric elements 21 positioned opposite the pressure chamber 31, and these piezoelectric elements 21 are connected by wiring so that a voltage can be applied. The control unit 150 sends a drive signal to the driver IC using an image signal corresponding to the image data, and applies a drive voltage to the internal electrodes 221 and 222 of the piezoelectric element 21 to be driven, thereby selectively deforming the piezoelectric element 21. By combining the tensile and compressive deformation of the diaphragm 30, the volume of the pressure chamber 31 is changed, and liquid is discharged.

[0078] For example, the control unit 150 alternately performs pulling and compressing operations. In the inkjet head 1, when pulling to increase the internal volume of the target pressure chamber 31, the target piezoelectric element 21 is contracted, while the non-target piezoelectric elements are not deformed. Also, in the inkjet head 1, when compressing to decrease the internal volume of the target pressure chamber 31, the target piezoelectric element 21 is extended, while the non-target piezoelectric elements 22 are not deformed.

[0079] According to the inkjet head 1 of the above embodiment, the reinforcing wall portion 44 of the flow channel substrate 402 is provided in the pressure chamber 31, and the position of the reinforcing wall portion 44 is set to a distance L1 from the edge of the nozzle 51 of 75 μm to 175 μm, thereby stabilizing AL and suppressing variations in ejection speed and ejection volume between pressure chambers (channels), making it possible to reinforce the flow channel substrate while maintaining ejection performance.

[0080] Furthermore, by setting the distance L2 between the reinforcing wall 44 and one end of the resistance channel 34 on the pressure chamber side to 200μm to 300μm, variations in discharge velocity and droplet volume between the pressure chambers 31 (channels) can be suppressed.

[0081] Furthermore, by reinforcing the substrate 402 that defines the thin, elongated resistive channels 341 and 342, the accuracy of the channel width can be improved, and the discharge performance can also be improved.

[0082] It should be noted that the present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention.

[0083] For example, the configuration is not limited to the form in which the reinforcing walls 44 and 45 are formed, and can be modified as appropriate. For instance, there may only be the reinforcing wall 44 inside the pressure chamber, or additional reinforcing walls may be formed in other locations.

[0084] The shape of each flow path substrate is not limited to the above embodiment. For example, although the flow path member 40 is shown as being formed from two flow path substrates 401 and 402, it may be made from three or more substrates. Also, the shape of the openings in each flow path substrate 401 and 402 is not limited to the above embodiment. For example, in the above embodiment, the first flow path substrate 401 is made from a thick plate and the second flow path substrate 402 is made from a thin plate, but it is not limited to this, and the first flow path substrate 401 may be made by stacking multiple plate members. For example, the flow path member 40 may be made using three substrates of the same thickness. In this case as well, in particular, the substrates that do not have walls surrounding the resistance flow paths 341 and 342 that define the resistance, and in which the openings that become the resistance flow paths 341 and 342 are formed, will have particularly long openings, so it is effective to form reinforcing walls 44 and 45.

[0085] Furthermore, the positions of the first flow channel substrate 401 and the second flow channel substrate 402 in the stacking direction are not limited to the above embodiment and can be changed as appropriate. For example, the first flow channel substrate, the flow channel substrate 401, may be on the nozzle plate 50 side, and the second flow channel substrate, the flow channel substrate 402, may be on the actuator section 20 side.

[0086] For example, in the above embodiment, multiple layers of piezoelectric members are stacked and the piezoelectric element 21 is driven using longitudinal vibration (d33) in the stacking direction, but the invention is not limited to this. For example, it can also be applied to a configuration in which the piezoelectric element 21 is composed of a single layer of piezoelectric member, or to a configuration in which it is driven by transverse vibration (d31).

[0087] Furthermore, the liquid to be dispensed is not limited to printing ink; for example, it could be a device that dispenses a liquid containing conductive particles for forming wiring patterns on a printed circuit board.

[0088] Furthermore, although the above embodiment shows an example of the inkjet head 1 being used in a liquid ejection device such as an inkjet recording device, it is not limited to this, and can also be used in 3D printers, industrial manufacturing machinery, and medical applications, enabling miniaturization, weight reduction, and cost reduction.

[0089] According to at least one embodiment described above, the desired flow path shape can be easily set.

[0090] In addition, several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0091] 1...Inkjet head, 20...Actuator section, 21...Driven piezoelectric element, 22...Non-driven piezoelectric element, 23...Groove, 26...Piezoelectric structure section, 30...Vibrating plate, 31...Pressure chamber, 32...Common chamber, 33...Common flow path section, 34...Resistance flow path, 35...Ink flow path, 36...Individual liquid chamber, 37...Common liquid chamber, 40...Flow path member, 41...Peripheral wall section, 42...Partition wall section, 43...Side wall section, 44...Reinforcement wall section, 45...Reinforcement wall section, 47...Manifold, 50...Nozzle plate, 51...Nozzle, 150...Control unit, 321...Common chamber, 322...Common chamber, 331...Common flow path section, 332...Common flow path section, 341...Resistance flow path, 342...Resistance flow path, 401...Flow path substrate, 402...Flow path substrate, 461...Beam-shaped section, 462...Beam-shaped section, 4011, 4012...Opening, 4021~4023...Opening.

Claims

1. The device comprises multiple flow path substrates, each having an opening or groove that constitutes a flow path including a pressure chamber communicating with a nozzle and a resistance flow path communicating with the pressure chamber, At least one of the flow path substrates has a first reinforcing wall portion within the pressure chamber, A liquid dispensing head in which the distance between one end of the first reinforcing wall and the edge of the nozzle is 75 μm to 175 μm.

2. The plurality of channel substrates are arranged stacked in the stacking direction, The first reinforcing wall portion is formed in other flow channel substrates arranged in a stacked configuration and is positioned opposite to the openings or grooves constituting the flow channel in the stacking direction. The resistance channel is configured to be narrower than the pressure chamber. The liquid discharge head according to claim 1, wherein the distance between the boundary between the resistance channel and the pressure chamber and the other end of the first reinforcing wall formed in the pressure chamber is 200 μm to 300 μm.

3. The first reinforcing wall portion is provided on a flow channel substrate among the plurality of flow channel substrates, which has a small thickness in the stacking direction and has an opening or groove that constitutes the resistance flow channel. The liquid discharge head according to claim 1, wherein the thickness of the first reinforcing wall in the stacking direction is equal to the thickness of the flow channel substrate on which the first reinforcing wall is formed in the stacking direction.

4. The first reinforcing wall portion is provided on a flow channel substrate among the plurality of flow channel substrates, which has a small thickness in the stacking direction and has an opening or groove that constitutes the resistance flow channel. The liquid discharge head according to claim 2, wherein the thickness of the first reinforcing wall in the stacking direction is equal to the thickness of the flow channel substrate on which the first reinforcing wall is formed in the stacking direction.

5. The liquid discharge head according to claim 1, wherein at least one of the flow channel substrates has a second reinforcing wall portion located in the resistive flow channel on the opposite side of the pressure chamber, and one end of the second reinforcing wall portion and the other end of the resistive flow channel are spaced 200 μm or more apart.

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