Liquid ejection head

Abstract

A liquid ejection head is provided that is capable of buffering pressure fluctuations in the head with a damper and performing stable ejection. The liquid ejection head of the embodiment has a plurality of pressure chambers, a common liquid chamber, an expanded common liquid chamber, and a damper. The plurality of pressure chambers communicate with nozzles, respectively. The common liquid chamber is formed along the arrangement direction of the plurality of pressure chambers and communicates with the respective pressure chambers. The expanded common liquid chamber expands the end portion of the common liquid chamber in a direction orthogonal to the arrangement direction of the pressure chambers, and forms a queue to the column of the pressure chambers. The damper is provided to the expanded common liquid chamber.

Description

Technical Field

[0001] Embodiments of the present invention relate to liquid ejection heads. Background Technology

[0002] A liquid ejector head is known to supply a predetermined amount of liquid to a predetermined location. The liquid ejector head is, for example, mounted on an inkjet printer, a 3D printer, or a dispensing device. An inkjet printer ejects droplets of ink from an inkjet head, forming images or the like on the surface of a recording medium. A 3D printer ejects droplets of modeling material from a modeling material ejector head and solidifies them, thereby forming a three-dimensional model. A dispensing device ejects droplets of a sample and supplies a predetermined amount to multiple containers or the like.

[0003] The liquid ejector head has multiple channels for ejecting liquid. Each ejection channel has a nozzle for ejecting liquid, a pressure chamber connected to the nozzle, and an actuator for changing the volume of the pressure chamber. The liquid ejector head selects the channel from the multiple ejection channels and drives the actuator of the selected ejection channel to eject the liquid.

[0004] As a method for supplying liquid to a liquid nozzle, a circulating supply method is employed, in which the liquid circulates between the liquid tank and the liquid nozzle. In this method, if the circulating flow rate inside the nozzle is less than the total flow rate when liquid is ejected from multiple nozzles, water hammer may occur, affecting the stability of the meniscus of the liquid within the nozzle required for stable ejection. As a countermeasure, a vibration damper is installed in the common liquid chamber connected to each pressure chamber to buffer pressure fluctuations, but the vibration damping effect is insufficient.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2023-77734

[0008] Patent Document 2: Japanese Patent Application Publication No. 2018-144474

[0009] Patent Document 3: Japanese Patent Application Publication No. 2021-185050

[0010] Patent Document 4: Japanese Patent Application Publication No. 2009-090674

[0011] Patent Document 5: Japanese Patent Application Publication No. 2022-024735 Summary of the Invention

[0012] The technical problem that the invention aims to solve

[0013] The technical problem to be solved by the present invention is to provide a liquid ejector head that can use a shock absorber to buffer pressure changes inside the head and make stable ejection.

[0014] Technical solutions for solving technical problems

[0015] The liquid ejector head according to an embodiment of the present invention includes multiple pressure chambers, a common liquid chamber, an expanding common liquid chamber, and a vibration damper. The multiple pressure chambers are respectively connected to a nozzle. The common liquid chamber is formed along the arrangement direction of the multiple pressure chambers and is connected to each of the pressure chambers. The expanding common liquid chamber expands at its end in a direction orthogonal to the arrangement direction of the pressure chambers, forming a column of pressure chambers. The vibration damper is disposed in the expanding common liquid chamber. Attached Figure Description

[0016] Figure 1 This is an overall configuration diagram of an inkjet printer equipped with the inkjet head of the first embodiment.

[0017] Figure 2 This is a 3D view of the inkjet head mentioned above.

[0018] Figure 3 This is a partially enlarged cross-sectional view of the head of the aforementioned inkjet head.

[0019] Figure 4 This is a partially enlarged cross-sectional view of the head of the aforementioned inkjet head.

[0020] Figure 5 This is a top view showing a partial magnification of the head of the inkjet printhead.

[0021] Figure 6 This is a partially enlarged cross-sectional view of the head of the aforementioned inkjet head.

[0022] Figure 7 This is an explanatory diagram illustrating the results of a simulation of the pressure changes within the aforementioned head.

[0023] Figure 8 This is an explanatory diagram illustrating the results of a simulation of the pressure changes within the aforementioned head.

[0024] Figure 9 This is an explanatory diagram illustrating the results of a simulation of the pressure changes within the aforementioned head.

[0025] Figure 10 This is a partially enlarged cross-sectional view of the head of the inkjet head in the second embodiment. Detailed Implementation

[0026] The liquid ejector head according to the embodiment will now be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals are used for the same components in all the drawings.

[0027] (First Implementation)

[0028] Taking an image forming apparatus equipped with a liquid ejector head according to the first embodiment as an example, an inkjet printer 10 that prints images onto a recording medium will be described. Figure 1 A simplified view of the inkjet printer 10 is shown. Inside the housing 11, the inkjet printer 10 includes: a cartridge 12 for storing a sheet S (an example of a recording medium), an upstream transport path 13 for the sheet S, a conveyor belt 14 for transporting the sheet S removed from the cartridge 12, multiple inkjet heads 100-103 for ejecting ink droplets toward the sheet S on the conveyor belt 14, a downstream transport path 15 for the sheet S, an ejection tray 16, and a control board 17. An operation unit 18, serving as a user interface, is located on the upper side of the housing 11.

[0029] Image data printed on sheet S is generated, for example, by computer 200, which is an external connection device. The image data generated by computer 200 is transmitted to control board 17 of inkjet printer 10 via cable 201 and connectors 202 and 203.

[0030] Pick-up roller 204 feeds sheets S one by one from cassette 12 to upstream conveyor path 13. Upstream conveyor path 13 consists of feed roller pairs 131 and 132, and sheet guide plates 133 and 134. Sheets S are conveyed via upstream conveyor path 13 to the upper surface of conveyor belt 14. Arrow 104 in the figure shows the conveying path of sheet S from cassette 12 to conveyor belt 14.

[0031] The conveyor belt 14 is a mesh-like annular belt with numerous through holes formed on its surface. Three rollers—drive roller 141, driven rollers 142, and 143—support the conveyor belt 14 for free rotation. A motor 205 rotates the conveyor belt 14 by rotating the drive roller 141. The motor 205 is an example of a drive device. Figure 105 shows the direction of rotation of the conveyor belt 14. A negative pressure container 206 is disposed on the back side of the conveyor belt 14. The negative pressure container 206 is connected to a pressure-reducing fan 207. The fan 207 creates a negative pressure inside the negative pressure container 206 through the airflow, adsorbing and holding the sheet S onto the upper surface of the conveyor belt 14. Figure 106 shows the direction of airflow.

[0032] As an example of a liquid ejector head, inkjet heads 100-103 are configured to face the sheet S held on the conveyor belt 14, for example, with a small gap of 1 mm. Inkjet heads 100-103 eject droplets of ink towards the sheet S. The inkjet heads 100-103 print images as the sheet S passes underneath. Each inkjet head 100-103 has the same structure except for the color of the ejected ink. The ink colors are, for example, cyan, magenta, yellow, and black.

[0033] Inkjet heads 100-103 are connected to ink tanks 315-318 and ink supply pressure adjustment devices 321-324 via ink flow paths 311-314, respectively. Each ink supply pressure adjustment device 321-324 adjusts the pressure inside each inkjet head 100-103 to a negative pressure relative to atmospheric pressure, for example, -1.2 kPa, to prevent ink from leaking from the nozzles 24 (see reference) of the inkjet heads 100-103 during standby. Figure 2 Leakage. The ink in each ink tank 315-318 is supplied by circulating between each inkjet head 100-103 and each ink tank 315-318 through ink supply pressure adjustment devices 321-324.

[0034] After image formation, sheet S is conveyed from conveyor belt 14 to downstream conveyor path 15. Downstream conveyor path 15 consists of feed roller pairs 151, 152, 153, and 154, and sheet guide plates 155 and 156 that define the conveying path of sheet S. Sheet S is conveyed from discharge port 157 to discharge tray 16 via downstream conveyor path 15. Arrow 107 in the figure shows the conveying path of sheet S.

[0035] Next, the structure of inkjet heads 100 to 103 will be explained. (Refer to the following...) Figures 2-6 The inkjet head 100 will be described, but inkjet heads 101 to 103 also have the same structure as inkjet head 100.

[0036] like Figure 2 As shown, the inkjet head 100 includes a head 2, which serves as an example of a liquid ejection section. The head 2 is connected to a flexible printed wiring board 21. The flexible printed wiring board 21 is connected to a printing substrate 22.

[0037] The head 2 has a nozzle plate 23. Nozzles 24 of each ink ejection channel are arranged along a first direction, such as the X direction, of the nozzle plate 23. The nozzle density is set, for example, in the range of 150 to 1200 dpi. Four rows of nozzles 24 are arranged in a second direction, such as the Y direction. The internal structure of the ink-circulating head 2 will be described later, but the four rows of nozzles 24 are configured with a shared ink circulation system of two rows per group. Therefore, two sets of ink supply paths 311 and ink recovery paths 331 are provided. A pair of ink supply paths 311 and ink recovery paths 331 are provided at both ends of the head 2 in the X direction. The head 2 is connected to an ink supply pressure adjustment device 321 via the ink supply paths 311 and ink recovery paths 331. The arrangement of the nozzles 24 is not limited to four rows and can be increased or decreased.

[0038] The flexible printed wiring board 21 is equipped with a driver IC (Integrated Circuit) 3 (hereinafter referred to as the driver IC). The driver IC 3, which serves as the control unit of the inkjet head 100, temporarily stores printing data and provides drive signals to each ejection channel to eject ink at a predetermined time. The printing data is transmitted from the control board 17, which is equipped with a CPU, which serves as the control unit of the inkjet printer 10, via the printing board 22.

[0039] Figures 3-6 It is a cross-sectional view of head 2, etc. Figure 3 yes Figure 5 AA sectional view. Figure 4 yes Figure 5 BB cross-sectional view. Figure 5 yes Figure 3 The C-direction view. Figure 6 yes Figure 5 A DD cross-sectional view. The nozzle plate 23 is joined to one side of the flow path plate 4. The nozzle plate 23 is, for example, a rectangular plate formed of a resin such as polyimide or a metal such as stainless steel. The vibrating plate 41 is joined to one side of the flow path plate 4 on the opposite side of the nozzle plate 23. The vibrating plate 41 has flexibility to deform when an external force is applied. The vibrating plate 41 is, for example, a rectangular plate formed of a flexible polyimide film or a metal.

[0040] The flow path plate 4 is, for example, composed of two plates 411 and 412, each having openings and grooves, stacked along the Z direction. Pressure chambers 42 for each ejection channel are formed on the flow path plate 4. These pressure chambers 42 are arranged at the positions of each nozzle 24 and are connected to each nozzle 24. As an example, the pressure chambers 42 form rectangular openings in the flow path plates 4 (411, 412) extending along a third direction, such as the Z direction, and the openings on both sides in the Z direction are blocked by the nozzle plate 23 and the vibrating plate 41, thereby creating a space for filling ink. The pressure chambers 42 are, for example, formed in a groove shape along the Y direction.

[0041] In the ink circulation head, one end of each pressure chamber 42 in the Y direction (ink supply side) is connected to the supply-side common liquid chamber 6 via a resistance flow path 43 and an ink inlet 44 formed on the flow path plate 4, and further via an ink supply port 45 formed on the vibrating plate 41. As an example, the supply-side common liquid chamber 6 is formed within a frame 61 that is joined to one side of the vibrating plate 41. It is not limited to this and may also be formed on the flow path plate 4. The supply-side common liquid chamber 6 is an ink supply manifold formed along the arrangement direction (X direction) of the pressure chambers 42 and connected to each pressure chamber 42. The ink supply port 62, which supplies ink to the supply-side common liquid chamber 6, is located at one end in the arrangement direction of the multiple pressure chambers 42, and in the example shown, at one end in the X direction. The ink supply port 62 is connected to the ink supply path 311. The supply-side common liquid chamber 6 is an example of a common liquid chamber. The ink supply port 62 is an example of a liquid supply port.

[0042] The other end (ink recovery side) of each pressure chamber 42 in the Y direction communicates with the common liquid chamber 63 on the recovery side via the resistance flow path 46 and ink discharge section 47 formed on the flow path plate 4, and further via the ink discharge port 48 formed on the vibrating plate 41. As an example, the common liquid chamber 63 on the recovery side is formed within a frame 64 that engages with one side of the vibrating plate 41. It is not limited to this and may also be formed on the flow path plate 4. The common liquid chamber 63 on the recovery side is an ink recovery manifold formed along the arrangement direction (X direction) of the pressure chambers 42 and communicating with each pressure chamber 42. An ink recovery port 65, which discharges ink from the common liquid chamber 63 to the head 2, is provided on the other end side in the arrangement direction of the multiple pressure chambers 42, and in the example shown, on the other end side in the X direction. The ink recovery port 65 is connected to the ink recovery path 331. The common liquid chamber 63 on the recovery side is an example of a common liquid chamber. The ink recovery port 65 is an example of a liquid recovery port.

[0043] The ink supply side resistance flow path 43 has, for example, a portion 431 that reduces the flow path cross-section by being narrower than the pressure chamber 42 in the X direction and imparts flow path resistance, and a portion 432 that, for example, changes the flow direction from plate 411 to plate 412 and imparts flow path resistance. Similarly, the ink recycling side resistance flow path 46 has, for example, a portion 461 that reduces the flow path cross-section by being narrower than the pressure chamber 42 in the X direction and imparts flow path resistance, and a portion 462 that, for example, changes the flow direction from plate 411 to plate 412 and imparts flow path resistance.

[0044] As already described, the four rows of nozzles 24 arranged on the nozzle plate 23 are configured with a shared ink circulation system in pairs. The supply-side common liquid chamber 6 is shared by two rows of pressure chambers 42 that are connected to each nozzle 24. Therefore, a supply-side common liquid chamber 6 is arranged between the two rows of pressure chambers 42, and its volume is increased by making its width in the Y direction larger than that of the recovery-side common liquid chamber 63, based on the amount shared. Two recovery-side common liquid chambers 63, which are connected to the pressure chambers 42 of each row, are arranged on the opposite side to the supply-side common liquid chamber 6, sandwiching the pressure chambers 42 of each row.

[0045] The other end of the common liquid chamber 63 on the recovery side, i.e., the end of the ink recovery port 65 on the X direction, expands in a direction orthogonal to the arrangement direction (X direction) of the pressure chambers 42 (Y direction), forming a queue of expanded common liquid chambers 70 to the column of pressure chambers 42. Figure 1 As illustrated, when multiple inkjet heads 100-103 are arranged within the inkjet printer 10 for printing, increasing the width of the sheet S in the transport direction (Y direction) will worsen the printing accuracy. Therefore, by forming the expansion common liquid chamber 70 in the same row as the pressure chamber 42, the width of the head 2 in the Y direction does not increase. It should be noted that in Figure 5 In this example, as a preferred embodiment, an expanded common liquid chamber 70 is shared by two recovery-side common liquid chambers 63. The ink recovery port 65 is connected to the expanded common liquid chamber 70.

[0046] Vibration dampers 7 that buffer pressure fluctuations within the head 2 are preferably provided in one or more of the expansion common liquid chamber 70. Alternatively, vibration dampers 71 and 72 may be provided in both the supply-side common liquid chamber 6 and the recovery-side common liquid chamber 63. It is also possible that only one of the vibration dampers 71 in the supply-side common liquid chamber 6 or the vibration damper 72 in the recovery-side common liquid chamber 63 is provided.

[0047] A preferred example of a vibration damper is a diaphragm-type pressure vibration damper. The vibration damper 7 of the expanding common liquid chamber 70 is configured such that two openings are formed in the upper part of the expanding common liquid chamber 70, and each opening is sealed using two flexible diaphragms 73. Pressure fluctuations can be buffered by the flexible diaphragms 73 flexing relative to pressure vibrations propagating within the head 2. Preferably, the vibration damper 7 forms quadrilateral openings and is sealed by quadrilateral diaphragms 73 with a similar shape to the openings. A more preferred vibration damper shape is square. This is because, in the case of a quadrilateral, the damping effect is proportional to the fifth power of the shorter side and the first power of the longer side; the damping effect is dominated by the shorter side, therefore a square with the shorter side equal to the longer side is most efficient. An example of the dimensions of a square vibration damper 7 is an opening with a width of 3 mm in the X direction and a length of 3 mm in the Y direction. Since a circle also has a shorter side equal to the longer side, a circle with a diameter of 3 mm can be used instead of a quadrilateral, for example. In addition, although a polygon with the short side equal to the long side can also be used, a quadrilateral or a circle is preferred for ease of manufacturing. The film 73 that seals the opening is, for example, a film formed of a resin such as polyimide. Preferably, it is a polyimide film with a Young's modulus E = 9.12 GPa and a thickness of 5 μm or less.

[0048] It should be pointed out that, in Figure 5 In the example, as a preferred embodiment, the two common liquid chambers 63 on the recovery side share an expanded common liquid chamber 70, and two vibration dampers 7 are provided in a manner corresponding to each common liquid chamber 63 on the recovery side. However, this is not a limitation, and the number of vibration dampers 7 in the expanded common liquid chamber 70 can be increased or decreased.

[0049] The vibration damper 71 in the supply-side common liquid chamber 6 and the vibration damper 72 in the recovery-side common liquid chamber 63 are preferably diaphragm-type vibration dampers. The vibration damper 71 in the supply-side common liquid chamber 6 is configured such that an opening along the long side direction (X direction) is formed in the upper part of the supply-side common liquid chamber 6, and the opening is sealed using a flexible strip-shaped film 74. The vibration damper 71 is formed to a length at least corresponding to the pressure chambers 42 at both ends. Similarly, the vibration damper 72 in the recovery-side common liquid chamber 63 is configured such that an opening along the long side direction (X direction) is formed in the upper part of the recovery-side common liquid chamber 63, and the opening is sealed using a flexible strip-shaped film 75. The films 74 and 75 sealing the opening are, for example, films formed of resins such as polyimide. Preferably, they are polyimide films with a Young's modulus E = 3.4 GPa and a thickness of 25 μm or less. As an example, the vibration damper 71 of the supply-side common liquid chamber 6 and the vibration damper 72 of the recovery-side common liquid chamber 63 have a width of 4m or more in the Y direction.

[0050] Figures 7-9It is a simulation of the pressure variation when the width W (expansion width) of the damper 7 in the X direction of the expansion common liquid chamber 70 and the thickness t of the membrane 73 are changed as parameters. Figure 8 It is Figure 7 The diagonal section acts as a damper, and a graph showing the pressure variation results when the width W in the X direction is changed to 0 mm (no damper), 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, and 4 mm is used as a damper. The vertical axis of the graph represents the pressure variation P [Pa], and the coordinate points on the horizontal axis represent... Figure 7 The pressure variation values ​​at each observation point are shown. As a calculation condition, film 73 was set as a polyimide film with Young's modulus E=9.12GPa and thickness t=5μm, and the structure of head 2 was simulated by the finite element method.

[0051] like Figure 8 As shown, when W=0mm (without dampers), the pressure fluctuations exceeded 1400Pa at several points. In contrast, by installing dampers 7 in the expansion common liquid chamber 70, the pressure fluctuations can be mitigated. That is, it is effective as a water hammer countermeasure. In particular, it is effective in the range of width W=3mm to 4mm. Especially, it is good at 3mm. This is because the supply (IN) side and the recovery (OUT) side are approximately symmetrical. It should be noted that the supply (IN) side does not have a parameter like width W and the structure is the same, so the pressure fluctuation results in each simulation are the same.

[0052] Figure 9 This is a graph showing the results of simulations where the thickness t of the polyimide film was changed to 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, and 50 μm. The width W is set as... Figure 8 The simulation results were good at 3mm. For example... Figure 9 As shown, the thinner the polyimide film thickness t, the greater the effect of mitigating pressure fluctuations, making it an effective measure against water hammer. In particular, a thickness t = 5 μm is ideal. This is because the supply (IN) and recovery (OUT) sides are approximately symmetrical.

[0053] Return the description Figure 3 The actuator that drives the ink ejection process will be described. As an example of an actuator, a piezoelectric actuator 5 is disposed on one side of a vibrating plate 41 opposite to the pressure chamber 42. The piezoelectric actuators 5 of each ejection channel, sandwiching the vibrating plate 41, are arranged opposite the pressure chamber 42. The piezoelectric actuators 5 and the vibrating plate 41 are joined, for example, by an adhesive. Each piezoelectric actuator 5 is fixed by engaging its Z-direction side, opposite to the vibrating plate 41, with a support member 7. Specifically, as... Figure 3As shown, the piezoelectric actuator 5 is, for example, a stacked piezoelectric actuator formed by alternately stacking a piezoelectric element 51, a first internal electrode 52, and a second internal electrode 53. The first internal electrode 52 and the second internal electrode 53 are conductive films formed on the main surface of the piezoelectric element 51, respectively. The first internal electrode 52 is formed on one end face of the piezoelectric actuator 5 in the Y direction and is connected to a first external electrode 54 formed on that end face. The second internal electrode 53 is formed on the other end face of the piezoelectric actuator 5 in the Y direction and is connected to a second external electrode 55 formed on that end face.

[0054] The dummy layer 58 is made of the same material as the piezoelectric element 51. The dummy layer 58 has no internal electrodes and is not subjected to an electric field, therefore it does not deform. The dummy layer 58 serves as the base for fixing the piezoelectric actuator 5 to the support member 68 (see reference). Figure 4 This can be used as a grinding allowance to achieve precision during or after assembly. Specifically, such as... Figure 4 As shown, the support column 50 can also be arranged with slots 59 spaced apart from each other in the piezoelectric actuators 5 of each ejection channel. The support column 50 can be constructed as a dummy actuator, formed in the same way as the piezoelectric actuator 5 for driving. The support column 50 is, for example, arranged at a position corresponding to the spacer wall 40 between adjacent pressure chambers 42. The support column 50 can also be formed by other components instead of a dummy actuator. The piezoelectric actuator 5 and the support column 50 are formed as an integral actuator block 500 through a dummy layer 58 (see reference). Figure 5 ).

[0055] The piezoelectric element 51 is formed of a lead-containing piezoelectric material such as lead zirconate titanate (PZT) or a lead-free piezoelectric material such as sodium potassium niobate. The first internal electrode 52 and the second internal electrode 53 are formed into films of conductive materials that can be sintered, such as silver and palladium. The first external electrode 54 and the second external electrode 55 are formed into films using known methods such as plating or sputtering, using materials such as Ni, Cr, and Au.

[0056] Each piezoelectric actuator 5 has its first external electrode 54 connected to a separate wiring on the flexible printed wiring board 21. Conversely, each piezoelectric actuator 5 has its second external electrode 55 connected to a common wiring (not shown) and, for example, connected to ground (GND) via the flexible printed wiring board 21. With a ground potential applied to the second external electrode 55 on the common terminal side, the drive IC 3 applies a drive voltage to the first external electrode 54 on the individual terminal side. As a result, the piezoelectric actuator 5 deforms (elongates or contracts) in the Z direction due to the inverse piezoelectric effect, and the volume of the pressure chamber 42 can be changed by flexing the vibrating plate 41. The drive IC 3 ejects ink from the nozzle 24 by combining multiple voltages (e.g., 20V, 10V, 0V) into a drive waveform and controlling the volume and pressure of the pressure chamber 42.

[0057] Next, an example of the operation of the inkjet head 100 configured as described above will be explained. The flow paths and pressure chamber 42 of the inkjet head 100 are pre-filled with ink. Furthermore, for example, if the inkjet printer 10 is powered on or released from sleep mode, the ink supply pressure regulating device 321 is activated, causing the ink to circulate between the inkjet head 100 and the ink tank 315. At this time, the ink is heated to a predetermined temperature by a temperature regulator (not shown) such as a heater. The predetermined ink circulation flow rate is, for example, 2 to 20 ml / min. The predetermined temperature is selected, for example, from a range of 20 to 50°C.

[0058] If ink circulation begins, the ink flowing in from the ink supply port 62 within the head 2 flows towards the supply-side common liquid chamber 6. Then, the ink is supplied from the supply-side common liquid chamber 6, which serves as an ink supply manifold, to each pressure chamber 42 via the resistance flow path 43 of each ejection channel. The ink passing through each pressure chamber 42 converges in the recovery-side common liquid chamber 63, which serves as an ink recovery manifold, via the resistance flow path 46, and is discharged from the ink recovery port 65.

[0059] The drive IC3 selects the ink ejection channel and applies a drive voltage to the piezoelectric actuator 5. The piezoelectric actuator 5, with the applied drive voltage, elongates / contracts in the Z direction due to the inverse piezoelectric effect, changing the volume of the pressure chamber 42, thereby ejecting ink from the nozzle 24. The decision of which channel's piezoelectric actuator 5 to drive is based on printing data. Sometimes, all ejection channels' piezoelectric actuators 5 are driven. Therefore, if the ink circulation flow rate within the head 2 is less than the total ejection flow rate when ejected from multiple ejection channels, the variation in ink flow rate in the common liquid chamber 63 before and after ejection has a significant impact, potentially causing abrupt pressure fluctuations. However, this embodiment buffers these pressure fluctuations by forming an expanded common liquid chamber 70 and providing a damper 7. Therefore, it is effective to place the damper 7 of the expanded supply liquid chamber 70 next to the ink recovery port 65, where pressure fluctuations are concentrated (due to the concentration of fluctuations across all ejection channels).

[0060] (Second Implementation)

[0061] Next, the inkjet head 100 of the second embodiment will be described. The inkjet head 100 of the second embodiment is mainly the same as that of the first embodiment, except that a vibration damper 8 is also provided on the ink supply side. Therefore, for configurations identical to those of the first embodiment, the same reference numerals are used, and detailed descriptions are omitted.

[0062] like Figure 10As shown, in the second embodiment, the inkjet head 100 expands the other end of the supply-side common liquid chamber 6, i.e., the end of the ink supply port 62 in the X direction, in a direction orthogonal to the arrangement direction (X direction) of the pressure chambers 42 (Y direction), and forms the expanded common liquid chamber 80 in a row of the pressure chambers 42. In this case, by forming the expanded common liquid chamber 80 in the same row as the pressure chambers 42, the width of the head 2 in the Y direction does not increase. As a preferred example, Figure 10 The other end of the supply-side common liquid chamber 6 is expanded to both sides in the Y direction to form an expanded common liquid chamber 80. The ink supply port 62 is connected to the expanded common liquid chamber 80.

[0063] One or more dampers 8 are preferably provided in the expansion common liquid chamber 80. A preferred example of the damper 8 is a diaphragm-type pressure damper. The damper 8 is configured, for example, to form two openings in the upper part of the expansion common liquid chamber 80 and to seal each opening using two flexible films 81. The damper 8 preferably forms quadrilateral openings and is sealed using quadrilateral films 81 with a similar shape to the openings. A more preferred shape of the damper is square. An example of the dimensions of a square damper 8 is a width of 3 mm in the X direction and a length of 3 mm in the Y direction. For example, a circle with a diameter of 3 mm can be used instead of a quadrilateral. Alternatively, it can be a polygon with the shorter side equal to the longer side. The film 81 that seals the openings is, for example, a film formed of a resin such as polyimide. Preferably, it is a polyimide film with a Young's modulus E = 9.12 GPa and a thickness of 5 μm or less.

[0064] If an expanded common liquid chamber 70 is formed on the ink recycling side and a vibration damper 7 is provided, pressure fluctuations can be mitigated, as described above. This effect has also been confirmed through simulation. In this embodiment, by further forming an expanded common liquid chamber 80 on the ink supply side and providing a vibration damper 8, pressure fluctuations can also be mitigated on the ink supply side. It should be noted that... Figure 10 In the example, although both the expansion common liquid chamber 80 and the vibration damper 8 on the ink supply side and the expansion common liquid chamber 70 and the vibration damper 7 on the ink recovery side are provided, it is also possible to provide only the expansion common liquid chamber 80 and the vibration damper 8 on the ink supply side. Furthermore, if the expansion common liquid chamber 80 and the vibration damper 8 are provided on the ink supply side, pressure fluctuations can be mitigated even if the width of the supply-side common liquid chamber 6 and the vibration damper 71 in the Y direction is reduced.

[0065] As explained above, according to any of the above embodiments, an inkjet head 100 can be provided that can buffer pressure fluctuations within the head 2 using dampers 7 and 8, resulting in stable ejection.

[0066] It should be noted that the piezoelectric actuator 5 is not limited to a stacked type consisting of multiple piezoelectric elements 51. The piezoelectric element 51 can also be a single-layer piezoelectric actuator. Furthermore, the actuator's operation when a driving voltage is applied is not limited to longitudinal vibration. Moreover, it is not limited to on-demand injection. Piezoelectric methods can also be applied to continuous injection methods.

[0067] In the above embodiment, the inkjet head 100 of the inkjet printer 10 was described as an example of a liquid ejection device, but the liquid ejection device may also be a modeling material ejection head of a 3D printer or a sample ejection head of a dispensing device.

[0068] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented 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, and are included within the scope of the invention as described in the claims and their equivalents.

[0069] Explanation of reference numerals in the attached figures

[0070] 10: Inkjet printer; 100-103: Inkjet head; 24: Nozzle; 4: Flow path plate; 42: Pressure chamber; 6: Supply side common flow path; 5: Piezoelectric actuator; 63: Recycle side common flow path; 7: Vibration damper; 70: Expansion common liquid chamber; 71: Vibration damper; 72: Vibration damper; 8: Vibration damper; 80: Expansion common liquid chamber.

Claims

1. A liquid ejector head, characterized in that, have: Multiple pressure chambers, each connected to a nozzle; A common liquid chamber is formed along the arrangement direction of the plurality of pressure chambers and is connected to each of the pressure chambers; Expand the common liquid chamber by expanding the end of the common liquid chamber in a direction orthogonal to the arrangement direction of the pressure chambers, thereby forming a queue to the column of the pressure chambers; as well as A shock absorber is disposed in the expanded common liquid chamber.

2. The liquid ejector head according to claim 1, characterized in that, The common liquid chamber is a recovery-side common liquid chamber, which recovers the circulating liquid flow that has passed through the pressure chamber. The expanded common liquid chamber is formed by expanding the end on the liquid recovery port side.

3. The liquid ejector head according to claim 1, characterized in that, The common liquid chamber is a supply-side common liquid chamber, which supplies liquid to the pressure chamber. The expanded common liquid chamber is formed by expanding the end on the liquid supply port side.

4. The liquid ejector head according to claim 1, characterized in that, The common liquid chamber comprises a recovery-side common liquid chamber and a supply-side common liquid chamber. The recovery-side common liquid chamber recovers the circulating liquid flow that has passed through the pressure chamber, while the supply-side common liquid chamber supplies liquid to the pressure chamber. The vibration damper is provided on both the expanded common liquid chamber formed by expanding the end of the common liquid chamber on the liquid recovery port side and the expanded common liquid chamber formed by expanding the end of the common liquid chamber on the liquid supply port side.

5. The liquid ejector head according to claim 1, characterized in that, In addition to the vibration damper in the expanded common liquid chamber, vibration dampers are also provided in the common liquid chamber along the arrangement direction of the pressure chambers.

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