Liquid dispensing head

Abstract

This invention provides a liquid ejection head that suppresses variations in negative pressure and ensures good printing performance. [Solution] A liquid discharge head according to one embodiment comprises: a plurality of pressure chambers communicating with a plurality of nozzles; a first individual flow path communicating with one side of the pressure chamber in one direction and extending in that direction; a second individual flow path communicating with the other side of the pressure chamber in that direction and extending in that direction; a first common chamber communicating with the first individual flow path, extending in a direction intersecting the one direction, and having two or more supply ports communicating with the outside; and a second common chamber communicating with the second individual flow path, extending in a direction intersecting the one direction, and having two or more discharge ports communicating with the outside.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to a liquid discharge head. [Background Art]

[0002] In liquid discharge heads such as inkjet heads, a method is used in which a diaphragm is deformed using an actuator formed of a piezoelectric material such as PZT (lead zirconate titanate), thereby deforming a pressure chamber facing the diaphragm, and discharging ink from a nozzle communicating with the pressure chamber. An inkjet head includes a plurality of actuators bonded to a 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 such a flow path portion, an individual flow path that narrows the flow path cross-sectional area may be provided between the pressure chamber and a common liquid chamber. When liquid is circulated in such an inkjet head, if fluid resistance increases, variation in negative pressure is likely to occur in the nozzle row. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2019-014066 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The problem to be solved by the present invention is to provide a liquid discharge head that can suppress variation in negative pressure and ensure good printing performance. [Means for Solving the Problem]

[0005] A liquid discharge head according to one embodiment comprises: a plurality of pressure chambers communicating with a plurality of nozzles; a first individual flow path communicating with one side of the pressure chamber in one direction and extending in that direction; a second individual flow path communicating with the other side of the pressure chamber in that direction and extending in that direction; a first common chamber communicating with the first individual flow path, extending in a direction intersecting the one direction, and having two or more supply ports communicating with the outside; and a second common chamber communicating with the second individual flow path, extending in a direction intersecting the one direction, and having two or more discharge ports communicating with the outside. [Brief explanation of the drawing]

[0006] [Figure 1] A cross-sectional view showing the configuration of the head body of the inkjet head according to the first embodiment. [Figure 2] A cross-sectional view showing a part of the components of the inkjet head. [Figure 3] A cross-sectional view showing a part of the components of the inkjet head. [Figure 4] A plan view showing the configuration of the flow path section of the inkjet head. [Figure 5] Cross-sectional view of the first flow channel substrate of the inkjet head. [Figure 6] Cross-sectional view of the second flow channel substrate of the inkjet head. [Figure 7] An explanatory diagram showing the arrangement of the supply port and output port in the inkjet head. [Figure 8] An explanatory diagram showing the configuration of the inkjet head and the pressure variation in Example 1. [Figure 9] An explanatory diagram showing the configuration of the inkjet head and the pressure variation in Example 2. [Figure 10] An explanatory diagram showing the configuration of the inkjet head and the pressure variation in Example 3. [Figure 11] An explanatory diagram showing the configuration of the inkjet head and the pressure variation in Example 4. [Figure 12] An explanatory diagram showing the configuration of the inkjet head and the pressure variation in Example 5. [Figure 13]An explanatory diagram showing the printing state of the water hammer confirmation pattern using the inkjet head according to Example 1. [Figure 14] An explanatory diagram showing the printing state of the water hammer confirmation pattern using the inkjet head according to Example 1. [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 13. Figure 1 is a cross-sectional view showing the configuration of the head body 11 of the inkjet head according to the first embodiment, and Figures 2 and 3 are cross-sectional views showing the configuration of a part of the inkjet head. Figure 4 is a plan view showing the configuration of the flow channel section of the inkjet head, Figure 5 is a cross-sectional view showing the configuration of the first flow channel substrate, and Figure 6 is a cross-sectional view of the second flow channel substrate. Figure 7 is an explanatory diagram showing the arrangement of the supply port and discharge port of the inkjet head, and Figures 8 to 12 are explanatory diagrams showing the pressure variation for Examples 1, 2, 3, 4, and 5. In the figures, arrows X, Y, and Z indicate three mutually orthogonal directions, respectively. In this embodiment, X is the parallel direction of the nozzle 51 and pressure chamber 31, Y is the extension direction (one direction), and Z is along the axial direction of the nozzle. In each figure, the configuration is enlarged, reduced, or omitted as appropriate for explanatory purposes.

[0008] As shown in Figures 1 to 3, 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, and 403, a nozzle plate 50 as a nozzle unit having a plurality of nozzles 51, and a manifold 45 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 configured by the diaphragm 30 and the flow channel member 40 to form an ink flow channel 35 (flow channel) inside 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, as shown in Figure 7, the inkjet head 1 is a side-shooter type four-row integrated head having two sets of head bodies 11, 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 parallel.

[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 section 20, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are arranged in the parallel direction at regular intervals. As an example, both the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are formed into rectangular parallelepiped columnar shapes having the same outer shape. The actuator section 20 is divided into a plurality of parts by the plurality of grooves 23, and the plurality of driving piezoelectric elements 21 and non-driving piezoelectric elements 22 are formed arranged in the column direction at the same pitch.

[0012] For example, when viewed in a plan view from the Z direction, which is the axial direction of the nozzle 51, the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are each configured in a rectangular shape in which the short-side direction follows the column direction of the element row, and the longitudinal direction follows an extending direction orthogonal to the column direction and the Z direction.

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

[0014] The non-driving piezoelectric elements 22 are arranged at positions respectively facing the partition wall sections 42 formed in the flow path member 40 in the Z direction. As an example, the center positions of the non-driving piezoelectric element 22 in the column direction and the extending direction, and the center positions of the partition wall section 42 in the column direction and the extending direction are arranged aligned in the Z direction.

[0015] For example, the laminated piezoelectric member constituting the actuator section 20 is formed by laminating sheet-shaped piezoelectric materials and sintering the same. The actuator section 20 forms the plurality of piezoelectric elements formed in a rectangular column shape at predetermined intervals 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 the plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 that are alternately arranged are formed. The plurality of driving piezoelectric elements 21 and the plurality of non-driving piezoelectric elements 22 are alternately arranged in parallel in the column direction with the grooves 23 interposed therebetween.

[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 comprise 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. Further, the driving piezoelectric element 21 and the non-driving piezoelectric element 22 comprise external electrodes 223 and 224 formed on surfaces thereof.

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

[0018] The internal electrodes 221 and 222 are conductive films formed into a predetermined shape from a calcinable conductive material such as silver-palladium. The internal electrodes 221 and 222 are formed in predetermined regions on the main surfaces of each piezoelectric layer 211, and have opposite polarities to each other. For example, one internal electrode 221 extends to one end of the piezoelectric layer 211 in the extension direction (Y direction), which is a direction orthogonal to both the row direction (X direction) that 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), and is formed in a region that does not reach the other end of the piezoelectric layer 211. The other internal electrode 222 does not extend to one end of the piezoelectric layer 211 in the extension direction, and is formed in a region that reaches the other end of the piezoelectric layer 211. 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 consists of 3 to 50 layers, with 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 45. For example, the diaphragm 30 has a vibration region 301 facing the piezoelectric elements 21, 22 and a support region 302 facing the manifold 45. 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, 403 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 302 is a plate-shaped member positioned between the manifold 45 and the flow path substrate 401. The vibrating plate 30 has a structure that is symmetrical on one side and the other side in the Y direction with respect to the nozzle 51. For example, the vibrating plate 30 has an opening 303 that connects the common liquid chambers 321, 322 and the common flow path sections 331, 332. The common liquid chamber 321 and the common flow path section 331 form the first common chamber 371 on the supply side, and the common liquid chamber 322 and the common flow path section 332 form the second common chamber 372 on the discharge side.

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

[0029] As shown in Figures 1 to 4, the flow channel member 40 comprises a plurality of stacked flow channel substrates 401, 402, and 403. For example, the flow channel member 40 comprises a first flow channel substrate 401 and a flow channel substrate 402, both configured to be the same shape, and a second flow channel substrate 403, both stacked together. Depending on the viscosity of the ink and the volume to be discharged, for example, a plurality of flow channel substrates 401, 402, and 403 having openings or grooves are joined together with the nozzle plate 50 and the diaphragm 30 to form a desired ink flow channel 35. Multiple flow channel substrates 401, 402, and 403 are arranged in stacking direction, and openings or grooves formed in each flow channel substrate 401, 402, and 403 constitute an ink flow channel 35 that includes a pressure chamber 31 communicating with multiple nozzles 51, a resistance flow channel 341 (first resistance flow channel section) which is a first individual flow channel, a resistance flow channel 342 (second resistance flow channel section) which is a second individual flow channel, a first common flow channel section 331 which constitutes part of the first common chamber 371, and a second common flow channel section 332 which constitutes part of the second common chamber 372. As an example, the flow channel substrates 401, 402, and 403 are stacked in order from the diaphragm 30 side, and the flow channel substrate 403 is positioned opposite the nozzle plate 50. As an example, in this embodiment, corresponding to each of the multiple nozzles 51, the resistance flow channel 341 on one side which is the first individual flow channel, the pressure chamber 31, and the resistance flow channel 342 on the other side which is the second individual flow channel are arranged side by side along the Y direction, forming multiple individual liquid chambers 36 extending in the Y direction. Then, on both sides in the Y direction of the multiple individual liquid chambers 36 arranged 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, 402, and 403 to form a predetermined ink flow path 35 (liquid chamber) which has a plurality of pressure chambers 31, a plurality of resistance flow paths 341, 342 (restriction sections) communicating with the plurality of pressure chambers 31, and a common flow path 331, 332 communicating with the plurality of resistance flow paths 341, 342. In other words, the flow path member 40, by stacking the plurality of flow path substrates 401, 402, and 403, constitutes a peripheral wall portion 41 surrounding the ink flow path 35 (liquid chamber) which is composed of a plurality of pressure chambers 31, a plurality of resistance flow paths 341, 342 and a common flow path portion 331, 332, a plurality of partition wall portions 42 separating the rows of the plurality of pressure chambers 31, and a side wall portion 43 separating the plurality of resistance flow paths 341, 342. For example, the flow channel member 40 constitutes multiple rows of ink flow channels 35 corresponding to the number of nozzles, but in Figures 4 to 6, only the area of ​​one row is shown.

[0031] For example, inside the flow path member 40 of each head body 11, a predetermined ink flow path 35 is formed that passes through a plurality of pressure chambers 31, each communicating with a plurality of nozzles 51. The ink flow path 35 is a liquid flow path. In this embodiment, each of the two head bodies 11 has two actuator units 20, and each head body 11 has a common flow path 33 having two first common flow path units 331 for supplying ink, formed outside the pair of actuator units 20 and extending in the X direction, and one second common flow path unit 332, formed between the pair of actuator units 20 and extending in the X direction. A total of three rows of common flow path units 331, 332, 331 are formed: one between the two actuator units 20 corresponding to the two rows of nozzles 51, and two on both sides of the two rows of actuator units 20. Furthermore, the common flow channels 331, 332, and 331 may have portions partitioned off to form individual flow channels for each row of nozzles 51 and pressure chambers 31, or they may constitute a continuous flow channel spanning multiple rows in the X direction. For example, the common flow channels 331, 332, and 331 are in communication with a common liquid chamber 32 formed in the manifold 45.

[0032] In other words, multiple rows of common flow channels 33 are formed, each extending 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 aligned.

[0033] 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 made 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, 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-shaped sections 461 are formed between adjacent openings 4011 in the direction of alignment. The openings 4012 that form the common flow channel sections 331, 332 may be long openings in the X direction that connect multiple rows.

[0034] The first flow channel substrate, the flow channel substrate 402, is joined to the flow channel substrate 401. The flow channel substrate 402 is a plate-shaped member having the same shape as the flow channel substrate 401, and is made of a metal material including SUS430, or a resin material such as silicon, as an example. The flow channel substrate 402 has a first opening 4021 that forms part of the pressure chamber 31, and a second opening 4022 that forms part of the common flow channel sections 331 and 332. For example, the first opening 4021 is located in the center of the extension direction in which the ink flow channel 35 extends, and the second openings 4022 are located at both ends. The first opening 4021 that constitutes the pressure chamber 31 is divided into multiple rows in the X direction, and beam-like sections 462 are formed between adjacent openings 4021 in the direction of alignment. On the other hand, the openings 4022 that form the common flow channel sections 331 and 332 may be long openings in the X direction that are connected in multiple rows.

[0035] The second channel substrate, channel substrate 403, is laminated on channel substrate 402 and bonded to channel substrate 402. Channel substrate 403 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 403. Channel substrate 403 has a plurality of openings 4031, 4032, and 4033 that are aligned in one direction via a connecting wall portion 44.

[0036] The multiple openings 4031, 4032, and 4033 form openings that penetrate in the thickness direction. The multiple openings 4031 and 4032 are arranged in a unidirectional manner via a connecting wall portion 44. The flow channel substrate 403 is the substrate in which the openings are formed over the longest range in the extension direction among the multiple flow channel substrates 401, 402, and 403. Also, for example, the openings 4031 and 4032 of the flow channel substrate 403 are configured to have a smaller width dimension than the openings 4011 formed in the other substrates 401 and 402. The thickness of the multiple flow channel substrates 401, 402, and 403 is set according to conditions such as resistance and flow rate, but in the example shown in Figures 1 and 2, the flow channel substrate 403 in which the resistance flow channels 341 and 342 with small cross-sectional areas are formed is configured to be thinner than the other first flow channel substrates 401 and 402.

[0037] The openings 4031 and 4032 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 463 are formed between multiple adjacent openings 4031 and multiple openings 4032 in the direction of alignment.

[0038] For example, a first opening 4031 is located in the center of the extension direction of the ink flow path 35, second openings 4032 are located at both ends via connecting walls 44, and third openings 4033 are located at the ends of the second openings 4032 on both sides via connecting walls 44. The first opening 4031 that constitutes the pressure chamber 31 and the second openings 4032 that constitute the resistance flow paths 341 and 342 are partitioned into multiple rows in the X direction, and beam-like sections 463 are formed between adjacent openings 4031 and openings 4032 in the direction of alignment. The openings 4033 that form the common flow path sections 331 and 332 may be connected in multiple rows, forming an opening shape that is long in the X direction.

[0039] For example, the connecting wall portion 44 is a wall-like member that connects the beam-like portions 463 on both sides of the openings 4031 and 4032 in the width direction. In other words, the connecting wall portion 44 partially blocks and divides the slit-shaped opening of the second flow channel substrate 403, which is long in one direction.

[0040] The connecting wall portion 44 (wall portion) is formed in an area that overlaps with the openings 4021 and 4022 of the opposing substrate 402, but does not block the nozzle 51. In this embodiment, within the pressure chamber 31, connecting wall portions 44 are formed on one side and the other side of the nozzle 51. For example, the connecting 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. The connecting wall portion 44 is also positioned so as not to overlap with the nozzle 51, at a predetermined distance or more away from the nozzle 51, and does not block the nozzle 51. In this embodiment, the connecting wall portion 44 is also provided at positions opposite to the common flow path portions 331 and 332. The connecting wall portion 44 is formed, for example, by etching when forming the openings 4031 to 4033, excluding the portion that will become the connecting wall portion 44. The connecting wall portion 44 becomes a support member that supports the beam-shaped portions 463 of the flow path substrate 403 by connecting the multiple beam-shaped portions 463. In other words, the flow path substrate 403, which is the second flow path substrate, has the longest flow path formed therein and also has the connecting wall portion 44 as a reinforcing portion.

[0041] For example, in this embodiment, the openings 4031, 4032, and 4033 are positioned to overlap at least some of the openings 4011, 4012, 4021, and 4022 of the other flow channel substrates 401 and 402, and communicate with these openings 4011, 4012, 4021, and 4022.

[0042] In the flow channel member 40, multiple pressure chambers 31 are formed by the first openings 4011, 4021, and 4031 of multiple flow channel substrates 401, 402, and 403 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.

[0043] Multiple pressure chambers 31 communicate with common liquid 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 the common liquid 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.

[0044] In the flow channel member 40, the second openings 4012, 4022 and third opening 4033 of a plurality of flow channel substrates 401, 402, and 403 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.

[0045] The common flow channels 331 and 332 are flow channels that communicate with the 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 liquid chamber 32 of the manifold 45.

[0046] Furthermore, in the flow channel member 40, resistance channels 341 and 342 are formed by an opening 4032 in part of the flow channel substrate 403. 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 flow channel cross-section.

[0047] Here, each flow channel substrate 401, 402, and 403 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 and 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 beam-shaped portions 461 of the stacked flow channel substrates 401 and 402, and the central portions of the beam-shaped portion 463 of the flow channel substrate 403 form partition walls 42 that separate the multiple pressure chambers 31.

[0048] 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.

[0049] In the flow channel member 40, the beam-shaped portion 463 of the flow channel substrate 403 forms a side wall portion 43 that separates the multiple resistance flow channels 341, 342.

[0050] 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.

[0051] As shown in Figures 7 and 8, the inkjet head according to this embodiment has two head bodies 11, and each head body 11 is provided with two rows of actuator sections 20, each having a nozzle row with multiple nozzles 51 arranged in the X direction and a pressure chamber row with multiple pressure chambers 31 arranged in the X direction, so that the inkjet head 1 has a total of four rows of nozzles 51 and actuator sections 20. In each head body 11, two supply-side common flow channels 331 are formed on the outside of the two actuator sections 20, one on each side. In addition, one discharge-side common flow channel 332 is formed between the two rows of actuator sections 20. That is, the central discharge-side common flow channel 332 is shared by the two actuator sections 20. For example, the common flow channels 331 and 332 are set so that the sum of the volumes of the common flow channel 332 and the common flow channel 331 is equal. For example, the height dimensions are equal, and the width dimension is set such that the width of the central shared common channel section 332 is greater than the width of the common channel sections 331 on both sides, for example, twice as much.

[0052] 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).

[0053] 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.

[0054] The two first common flow channels 331 and the one second common flow channel 332 each communicate with a common liquid chamber 32 in the manifold 45.

[0055] 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.

[0056] The manifold 45 is a structure that is joined to the diaphragm 30 together with the piezoelectric elements 21 and 22. The manifold 45 is provided on the side opposite to the piezoelectric elements 21 and 22, the diaphragm 30, and the flow path member 40, and in this embodiment, for example, it is positioned adjacent to the actuator unit 20. The manifold 45 constitutes the outer casing of the inkjet head 1. The manifold 45 also forms a liquid flow path inside. In this embodiment, the manifold 45 is joined to the other side of the diaphragm 30, forming a common liquid chamber 32 between it and the diaphragm 30. The manifold 45 may also be formed by a damper member that is partially flexible. For example, the manifold 45 includes a frame member that forms a flow path that becomes the common chambers 321 and 322 and has an opening that opens toward the opposite side of the nozzle plate 50 in the stacking direction, and a damper film 451 that closes the opening of the frame member.

[0057] The common liquid chamber 32 is formed inside the manifold 45. For example, inside the manifold 45, a supply-side common liquid chamber 321 is formed, which is part of the first common chamber 371, and a discharge-side common liquid chamber 322 is formed, which is part of the second common chamber 372. Each common liquid chamber 321 and 322 is provided with a supply port 321a and a discharge port 322a, respectively, which are connected to external supply and discharge pipes, and via the supply and discharge pipes, are connected to the outside of the head. For example, the supply-side common liquid chamber 321 is formed inside the manifold 45 and communicates with the first common flow path section 331. The discharge-side common liquid chamber 322 is formed inside the manifold 45 and communicates with the second common flow path section 332. That is, the common liquid chambers 321 and 322 communicate with the pressure chamber 31 via the common flow path sections 331 and 332 and the resistance flow paths 341 and 342.

[0058] For example, the supply port 321a and the discharge port 322a are flow paths formed in the frame member of the manifold 45. For example, the supply port 321a and the discharge port 322a are through holes formed from the inner wall portion of the frame member of the manifold 45 facing the ends in the X direction of the common liquid chambers 321 and 322, to the surface of the manifold 45 opposite to the nozzle plate 50. For example, the supply port 321a and the discharge port 322a are formed in positions that avoid the damper film 451.

[0059] In the inkjet head 1 configured as described above, an ink flow path 35 is formed by the nozzle plate 50, manifold 45, 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 chamber 37 composed of common flow path sections 331 and 332 and common liquid chambers 321 and 322 formed in the manifold 45. For example, the common liquid 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 liquid chamber 321, or ink discharged from the pressure chambers 31 is recovered to the cartridge through the common liquid chamber 322.

[0060] 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 is arranged continuously from the ends of the resistance channels 341 and 342 in the extending direction, consisting of a common channel section 33 and a common liquid chamber 32.

[0061] 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.

[0062] 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 liquid chamber 32 and discharging it from the nozzle 51.

[0063] 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 and 342, the second common channel section 332, and the discharge side's common liquid 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.

[0064] Here, the driving operation for driving the inkjet head 1 will be described. The inkjet head 1 according to this embodiment includes piezoelectric elements 21 arranged opposite to 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. Then, by combining the deformation of the diaphragm 30 in the tensile direction and the deformation in the compressive direction, the volume of the pressure chamber 31 is changed, and liquid is discharged.

[0065] 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.

[0066] In this embodiment, the inkjet head 1 has two or more rows of nozzles, and in the head body 11 of the inkjet head 1, either the first common flow channel 331 or the second common flow channel 332 is formed between the two rows of nozzles, and the other of the first common flow channel 331 or the second common flow channel 332 is formed on the outside of the two rows of nozzles. In addition, either the first common liquid chamber 321 or the second common liquid chamber 322 in the manifold 45 is formed in a region corresponding to the space between the two rows of nozzles, and the other of the first common liquid chamber 321 or the second common liquid chamber 322 is formed on the outside of the two rows of nozzles. Furthermore, there are two first common liquid chambers 321 and one second common liquid chamber 322 extending in the X direction. The common liquid chambers 321 and 322 each have a supply port 321a or an outlet port 322a as connection ports. Therefore, in the inkjet head 1, the supply port 321a and the discharge port 322a are provided in two or more locations.

[0067] In this embodiment, as a specific example, supply ports 321a are formed at both ends in the X direction of the two common liquid chambers 321, and discharge ports 322a are formed at both ends in the X direction of the central common liquid chamber 322.

[0068] According to the inkjet head 1 of the embodiment described above, by having two or more supply ports and discharge ports in the first common flow channel section and the second common flow channel section extending in the first direction, pressure variations can be suppressed.

[0069] Figure 8 is a graph showing the flow path configuration and pressure variation according to Example 1 of this embodiment. Figures 9 to 12 are graphs showing the flow path configuration and pressure variation according to Comparative Examples 1 to 4.

[0070] Embodiment 1 is an example in which four supply ports and two discharge ports are provided, and common flow channels 331 and 332 that communicate with each other at both ends in the Y direction extend in the X direction, and supply ports and discharge ports are provided at both ends in the X direction of each common flow channel 331 and 332, respectively.

[0071] As shown in Figure 9, the inkjet head 1A according to Comparative Example 1 includes a head body 11A with a supply port 321a and an outlet port 322a at only one end in the X direction of each of the three common chambers 321, 322, and 321. The supply ports 321a of the two supply common chambers 321 on both sides are located at one end in the X direction, and the outlet port 322a of the central discharge common chamber 322 is located at the end opposite to the supply port 321a.

[0072] As shown in Figure 10, the inkjet head 1B in Comparative Example 2 includes a head body 11B having a supply port 321a and an output port 322a at only one end in the X direction of each of the three common chambers 321, 322, and 321. The supply ports 321a of the two supply common chambers 321 on both sides and the output port 322a of the central output common chamber 322 are all located at one end in the X direction.

[0073] The inkjet head 1C according to Comparative Example 3, as shown in Figure 11, comprises a head body 11C in which, in each of the two common chambers 321, a supply port 321a is provided only at one end in the X direction, and the central common flow channel 322 has discharge ports 322a at both ends. The supply ports 321a of the two supply common chambers 321 on both sides are located at one end in the X direction.

[0074] The inkjet head 1D according to Comparative Example 4, as shown in Figure 12, comprises a head body 11D in which two common chambers 321, 321 each have supply ports 321a at both ends in the X direction, and the central common chamber 322 has an output port 322a at only one end. In Comparative Examples 1 to 4, the configuration was the same as that of the inkjet head 1 in the above embodiment, except for the arrangement of the supply port 321a and the discharge port 322a.

[0075] Comparing Figures 8 to 12, Figure 8 shows less pressure variation compared to Figures 9 to 12. This indicates that variations in nozzle negative pressure are suppressed by having two or more supply ports 321a or discharge ports 322a in each common flow path. Furthermore, in the above embodiment, miniaturization is possible by providing a single common flow path corresponding to two rows of nozzles.

[0076] Figures 13 and 14 are explanatory diagrams showing the printing results when a water hammer confirmation pattern is printed on inkjet head 1. Large pressure variations can cause delays in print output due to water hammer, but as shown in Figures 13 and 14, it can be confirmed that there was no delay in print output due to the effects of water hammer when printing with the confirmation pattern for checking water hammer.

[0077] 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.

[0078] For example, in the above embodiment, a supply port 321a is formed in the common liquid chamber 321 and common flow path section 331 that constitute the first common chamber 371 on the supply side, and a discharge port 322a is formed in the common liquid chamber 322 of the common liquid chamber 322 and common flow path section 332 that constitute the second common chamber 372 on the discharge side, but the embodiment is not limited to this. For example, the supply port and discharge port may be formed in the common flow path sections 331 and 332, respectively. Also, in the above embodiment, a common flow path section 331 and 332 connected to a plurality of individual flow paths 34 is formed within the flow path member 40 between the common liquid chambers 321 and 322 and the individual flow paths 34, but the embodiment is not limited to this. For example, the common liquid chambers 331 and 332 of the manifold 45 may be arranged in communication with individual flow paths partitioned for each pressure chamber.

[0079] For example, in the above embodiment, a structure is illustrated in which there are two first common flow channels on both sides on the supply side and one second common flow channel in the center on the discharge side, but the structure is not limited to this, and the reverse may also be the case.

[0080] The shape of each channel substrate is not limited to the above embodiment. For example, although the channel member 40 is shown to be formed from three channel substrates 401, 402, and 403, it may also be from two or four or more substrates. Furthermore, the shape of the openings in each channel substrate 401 and 402 is not limited to the above embodiment.

[0081] Furthermore, the positions of the first flow channel substrates 401 and 402 and the second flow channel substrate 403 in the stacking direction are not limited to the above embodiment and can be changed as appropriate. For example, the first flow channel substrates, 401 and 402, may be on the nozzle plate 50 side, and the second flow channel substrate, 403, may be on the actuator section 20 side.

[0082] 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).

[0083] 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.

[0084] 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.

[0085] According to at least one embodiment described above, variations in negative pressure can be suppressed, and good printing performance can be ensured.

[0086] 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]

[0087] 1...Inkjet head, 11...Head body, 20...Actuator unit, 21...Drive piezoelectric element, 22...Non-drive piezoelectric element, 23...Groove, 26...Piezoelectric structure, 30...Diaphragm, 31...Pressure chamber, 32...Common liquid chamber, 33...Common flow path section, 35...Ink flow path, 36...Individual liquid chamber, 37...Common chamber, 371...First common chamber, 372...Second common chamber, 40...Flow path member, 41...Peripheral wall section, 42...Partition wall section, 43...Side wall section, 44...Connecting wall section, 45...Manifold, 50...Nozzle plate, 51...Nozzle, 150...Control unit, 211 ...piezoelectric layer, 221...internal electrode, 222...internal electrode, 223...external electrode, 224...external electrode, 301...vibration region, 302...support region, 321...first common liquid chamber, 321a...supply port, 322...second common liquid chamber, 322a...discharge port, 331...common flow path section, 332...common flow path section, 341...resistive flow path, 342...resistive flow path, 401...flow path substrate, 402...flow path substrate, 403...flow path substrate, 461, 462, 463...beam-shaped section, 4011, 4012, 4021, 4022, 4031, 4032, 4033...opening.

Claims

1. Multiple pressure chambers communicating with multiple nozzles, A first individual flow path communicating with one side of the pressure chamber in one direction and extending in that direction, A second individual flow path communicates with the other side in the same direction as the pressure chamber and extends in the same direction, A first common chamber having two or more supply ports that communicate with the first individual flow path, extend in a direction intersecting the aforementioned one direction, and communicate with the outside, A second common chamber is provided, which communicates with the second individual flow path, extends in a direction intersecting the aforementioned one direction, and has two or more discharge ports that communicate with the outside. Liquid dispensing head.

2. The supply ports are provided on both sides of the first common chamber in a direction intersecting the aforementioned one direction. The liquid discharge head according to claim 1, wherein the discharge ports are provided on both sides of the second common chamber in a direction intersecting the one direction.

3. Having two or more rows of nozzles, Either the first common chamber or the second common chamber is formed between the two rows of nozzles, The liquid discharge head according to claim 1, wherein the other of the first common chamber or the second common chamber is formed on the outside of the two rows of nozzles, respectively.

4. This is a circulating type in which the liquid is circulated in a flow path including the pressure chamber that communicates with the nozzle, The first individual flow path comprises a first resistance flow path section having a flow path cross-section smaller than that of the pressure chamber. The second individual flow path comprises a second resistance flow path section having a flow path cross-section smaller than that of the pressure chamber. The liquid discharge head according to claim 2, wherein the first individual flow path, the pressure chamber, and the second individual flow path are arranged sequentially along the one direction.

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