Liquid discharge head and liquid discharge device

Abstract

To suppress influence of crosstalk, while suppressing deterioration in nozzle density.SOLUTION: In a liquid discharge head 1, actuators are provided respectively in a plurality of individual flow paths 4 communicated with a plurality of nozzles 2 respectively, and a common flow path 3 facing respective opening parts 4a of the plurality of flow paths positioned at a side opposing to a nozzle formation wall 110 of the plurality of individual flow paths is provided. In the common flow path, members 121a for detouring, which make a first in-liquid pressure propagation path length LB between the opening parts longer than a second in-liquid pressure propagation path length LA between the opening part of the individual path 4A of the other adjacent nozzle 2A and the opening part of the individual flow path of a target nozzle, are arranged between the opening parts of the individual flow paths 4B of some adjacent nozzles 2B of the plurality of adjacent nozzles arranged adjacent to the target nozzle 2S and the opening parts of the individual flow path 4S of the target nozzle, where a difference between the path length LB and the path length LA is a predetermined path length difference ΔL.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and an apparatus for ejecting liquid.

[0002] Conventionally, a liquid ejection head is known that includes a plurality of nozzles for ejecting liquid, a plurality of individual flow paths each connected to the plurality of nozzles, a plurality of actuators provided for each of the plurality of individual flow paths, and a common flow path facing each opening of the plurality of individual flow paths located on the side facing the nozzle forming wall of the plurality of individual flow paths.

[0003] For example, Patent Document 1 discloses a liquid ejection head including a nozzle plate (nozzle forming wall) on which a plurality of nozzles and actuators are formed, a substrate on which a plurality of cylindrical individual flow paths are formed, each of which communicates with the plurality of nozzles, and a damper member. The actuator is formed in a circular ring shape concentric with the nozzle, and is driven to pressurize the liquid in each individual flow path. The damper member is an elastic member provided on the surface of the substrate opposite to the surface on which the nozzle plate is provided, and a plurality of cylindrical damper chambers having the same inner diameter as each individual flow path are provided facing each individual flow path. The common flow path communicates with each individual flow path via each damper chamber of the damper member. The pressure wave of the liquid generated in each individual flow path by the actuator drive is absorbed by the elastic deformation of the damper member, thereby suppressing the influence of crosstalk in which the pressure wave propagates to other individual flow paths. Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a liquid ejection head in which an actuator is provided on each nozzle forming wall of multiple individual flow paths, while the conventional configuration can suppress the effects of crosstalk, it is difficult to increase the number of nozzles per unit area (increase nozzle density). [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides a liquid ejection head comprising a plurality of nozzles for ejecting liquid, a plurality of individual flow paths each connected to the plurality of nozzles, a plurality of actuators provided for each of the plurality of individual flow paths, and a common flow path facing each opening of the plurality of individual flow paths located on the side facing a nozzle forming wall of the plurality of individual flow paths, and driving the actuators to eject liquid in the individual flow paths from the nozzles, wherein a bypass member is disposed within the common flow path between an opening of an individual flow path corresponding to a part of a plurality of adjacent nozzles adjacent to a target nozzle and an opening of an individual flow path corresponding to the target nozzle, the bypass member making a first liquid internal pressure propagation path length between the openings longer than a second liquid internal pressure propagation path length between an opening of an individual flow path corresponding to another adjacent nozzle of the plurality of adjacent nozzles and the opening of an individual flow path corresponding to the target nozzle, and the difference between the first liquid internal pressure propagation path length and the second liquid internal pressure propagation path length is configured to be a predetermined path length difference. Effect of the Invention

[0006] According to the present invention, in a liquid ejection head in which an actuator is provided on each of the nozzle forming walls of a plurality of individual flow paths, it is possible to suppress the effects of crosstalk while suppressing a decrease in nozzle density. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view that illustrates a schematic internal structure of a liquid ejection head according to an embodiment, and is a cross-sectional view taken along the line CC'. [Diagram 2] FIG. 2 is a front view showing a schematic internal structure of the liquid ejection head, and is a cross-sectional view taken along the line AA'. [Diagram 3] FIG. 2 is a side view showing a schematic internal structure of the liquid ejection head, and is a cross-sectional view taken along the line BB'. [Figure 4] FIG. 2 is a front view showing a schematic internal structure of the liquid ejection head, and is a cross-sectional view taken along the line DD'. [Diagram 5] FIG. 2 is a side view showing a schematic internal structure of the liquid ejection head, and is a cross-sectional view taken along the line E-E'. [Figure 6] FIG. 2 is a side view showing a schematic internal structure of the liquid ejection head, and is a cross-sectional view taken along the line FF'. [Figure 7] FIG. 4 is an enlarged cross-sectional view showing the periphery of one individual flow path in the liquid ejection head. [Figure 8] FIG. 13 is a plan view that illustrates the internal structure of a liquid ejection head according to a modified example, and is a cross-sectional view taken along the line CC'. [Figure 9] FIG. 13 is a side view, and a cross-sectional view taken along line BB', that illustrates a schematic internal structure of a liquid ejection head according to a modified example. [Figure 10] 1A is a graph comparing pressure fluctuations occurring in an individual flow path of a nozzle of interest when there is no crosstalk pressure and when there is crosstalk pressure in a comparative example, and FIG. 1B is a graph comparing pressure fluctuations occurring in an individual flow path of a nozzle of interest when there is no crosstalk pressure and when there is crosstalk pressure in an embodiment. [Figure 11] 1A is an explanatory diagram showing an example in which an actuator is disposed on a nozzle plate, FIG. 1B is an explanatory diagram showing an example in which an actuator is disposed inside a nozzle plate, and FIG. 1C is an explanatory diagram showing an example in which an actuator is disposed near a nozzle plate. [Figure 12] FIG. 1 is a schematic explanatory diagram of a printing apparatus according to an embodiment. [Figure 13] FIG. 2 is a plan view illustrating an example of a head unit of the printing apparatus. [Figure 14] FIG. 13 is an explanatory plan view of a main portion of another printing device. [Figure 15] FIG. 2 is a side view illustrating a main part of the printing apparatus according to the embodiment. [Figure 16] FIG. 2 is a plan view illustrating a main part of the liquid ejection unit according to the embodiment. [Figure 17] FIG. 2 is a front view of the liquid ejection unit according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment in which the present invention is applied to a liquid ejection head provided in an apparatus for ejecting liquid will be described. It should be noted that the present invention is not limited to the embodiments described below, and can be modified, added, modified, deleted, or otherwise altered within the scope of what can be conceived by a person skilled in the art. As long as the functions and effects of the present invention are achieved in any aspect, it is within the scope of the present invention.

[0009] The liquid ejection head in this embodiment is a nozzle plate vibration type liquid ejection head that ejects liquid in an individual flow path from a nozzle by varying the pressure of the individual flow path with an actuator provided on a nozzle plate having nozzles. The nozzle plate vibration type has the characteristic that droplets can be ejected with a smaller force than a general unimorph type piezo head (which ejects liquid by vibrating a surface facing a wall (nozzle forming wall) having a communication port that communicates with the nozzle of the individual flow path), and can reduce the power consumption of the actuator.

[0010] When the nozzle density is increased, the space for laying out the wiring for voltage application is limited, making it difficult to construct the wiring on the surface of the substrate. By constructing wiring and drive circuits inside the substrate, it is possible to lay out the wiring even in a configuration with a high nozzle density. In general, lead zirconate titanate (PZT) is widely used as a material for piezoelectric elements used as actuators due to its high piezoelectric properties. However, when forming a piezoelectric film on a substrate on which wiring and drive circuits are constructed, the film formation and crystallization temperature of PZT is required to be 600°C or higher, so if PZT is used as a material for the piezoelectric elements, the drive circuit and its wiring in the substrate will not be able to withstand high temperatures. Therefore, in a configuration in which wiring and drive circuits are constructed inside the substrate, a piezoelectric material with a lower film formation temperature than PZT is required, and it is inevitable to select a material with lower piezoelectric properties than PZT. However, the nozzle plate vibration method described above has the characteristic that droplets can be ejected with a smaller force than a general unimorph type piezo head, so even if a material with lower piezoelectric properties than PZT is selected, it is possible to eject liquid well. Therefore, even piezoelectric materials with low power but low film formation and crystallization temperatures such as lead-free materials can be used to eject liquid well. This allows wiring and drive circuits to be built inside the substrate, making high density possible. Furthermore, the nozzle plate vibration method allows the volume of individual flow paths to be reduced, making it possible to miniaturize the head.

[0011] FIG. 1 is a plan view that diagrammatically shows the internal structure of a liquid ejection head 1 in this embodiment, and is a cross-sectional view taken along the line CC'. FIG. 2 is a front view showing a schematic internal structure of the liquid ejection head 1 in this embodiment, and is a cross-sectional view taken along the line AA'. FIG. 3 is a side view that shows a schematic internal structure of the liquid ejection head 1 in this embodiment, and is a cross-sectional view taken along the line BB'. FIG. 4 is a front view showing a schematic internal structure of the liquid ejection head 1 in this embodiment, and is a cross-sectional view taken along the line DD'. FIG. 5 is a side view that diagrammatically illustrates the internal structure of the liquid ejection head 1 in this embodiment, and is a cross-sectional view taken along the line EE'. FIG. 6 is a side view that diagrammatically illustrates the internal structure of the liquid ejection head 1 in this embodiment, and is a cross-sectional view taken along the line FF'.

[0012] The liquid ejection head 1 of this embodiment includes a nozzle plate 110, an individual flow path substrate 100, a common flow path substrate 120, a damper section 130, and a frame section 140.

[0013] The nozzle plate 110 is in the form of a thin film, and has a plurality of nozzles 2 that eject liquid, and a piezoelectric element 5 as an electromechanical conversion element that is an annular actuator arranged around the nozzles 2. The individual flow path substrate 100 has a plurality of individual flow paths (also called individual flow paths or pressurized liquid chambers) 4 that respectively communicate with the plurality of nozzles 2. The nozzle 2 (vibration membrane 103) is located on one surface of each individual flow path 4, and an opening 4a of the individual flow path and a damper section 130 are arranged on the side opposite to the surface. The common flow path substrate 120 has a common flow path 3 that communicates with the plurality of individual flow paths 4.

[0014] In the nozzle plate 110 of this embodiment, a plurality of nozzle rows (five rows in the illustrated example) are arranged in the left-right direction in the figure, with the nozzles 2 being linearly arranged along the vertical direction (B row direction) in Fig. 1, which is a direction parallel to the cross section B-B' (head longitudinal direction). Therefore, the individual flow paths 4 formed in the individual flow path substrate 100 are also arranged in a plurality of nozzle rows (five rows in the illustrated example) arranged in the left-right direction in the figure, with the nozzle rows being arranged along the vertical direction (B row direction) in the figure, as shown in Fig. 1.

[0015] In addition, the nozzles between the nozzle rows are arranged so that their positions in the B row direction (the vertical direction in the figure) are shifted from each other so that high density dots (for example, 600 dpi, 1000 dpi, 1200 dpi, etc.) can be formed in a single pass. Accordingly, the individual flow paths 4 are also arranged so that their positions in the vertical direction (the B row direction) in the figure are shifted from each other between the nozzle rows, as shown in FIG. 1.

[0016] In addition, the individual flow paths 4 in this embodiment are described as having a circular cross section parallel to the substrate surface direction, but the cross section may have other shapes such as an elliptical cylinder, a polygonal cylinder, etc. In addition, the cross section does not need to be uniform across the substrate thickness direction.

[0017] FIG. 7 is an enlarged cross-sectional view showing the periphery of one individual flow path 4. As shown in FIG. The individual flow path substrate 100 is an SOI (Silicon on InsuMAtor) substrate, and has a drive circuit 101 and a wiring section 102 on the side where the vibration membrane 103 is formed. The drive circuit 101 is a circuit including transistors, resistors, etc. The wiring section 102 has a wiring section for applying a drive waveform to the first electrode 51, and a wiring section for applying a drive waveform to the second electrode 53. In addition, the wiring section 102 is electrically connected to an electrical connection pad 55 via a third contact 7c opened in the vibration membrane 103.

[0018] The nozzle plate 110 has a nozzle forming portion (film) 111 in which a plurality of nozzles 2 are formed and which covers the piezoelectric element 5, and a liquid-repellent film 112 is formed on the nozzle surface of the nozzle forming portion 111. When liquid is continuously ejected, mist generated simultaneously with the ejection adheres to the nozzle surface. If a large amount of this mist adheres to the nozzle surface, the liquid ejected from the nozzle 2 may be affected by the liquid adhering to the nozzle surface and may deviate from the desired landing position. By forming the liquid-repellent film 112 on the nozzle surface, it is possible to suppress the adhesion of liquid to the nozzle surface, and to suppress the liquid ejected from the nozzle 2 from being affected by the liquid adhering to the nozzle surface.

[0019] The piezoelectric element 5 of the nozzle plate 110 has a first electrode 51 (also referred to as a lower electrode), a piezoelectric film 52, and a second electrode 53 (also referred to as an upper electrode). The piezoelectric element 5 is covered with a first insulating film 8a. The first insulating film 8a has a hole-shaped fourth contact 7d for electrical connection to the first electrode 51 and a hole-shaped fifth contact 7e for electrical connection to the second electrode 53 formed therein.

[0020] In addition, the first insulating film 8a is formed with a first extraction wiring 9a that electrically connects the first electrode 51 of the piezoelectric element 5 and the wiring portion 102 of the individual flow path substrate 100, and a second extraction wiring 9b that electrically connects the second electrode 53 of the piezoelectric element 5 and the wiring portion 102 of the individual flow path substrate 100.

[0021] The first lead-out wiring 9a is electrically connected to the first electrode 51 via the fourth contact 7d, and is electrically connected to the wiring portion 102 via the first contact 7a. The second lead-out wiring 9b is electrically connected to the second electrode 53 via the fifth contact 7e, and is electrically connected to the wiring portion 102 via the second contact 7b. The first lead-out wiring 9a and the second lead-out wiring 9b are covered with a second insulating film 8b. In this embodiment, the second insulating film 8b also covers the piezoelectric element 5, and has a function of preventing moisture that has entered the nozzle forming portion 111 made of resin from entering the piezoelectric element 5, thereby protecting the piezoelectric element 5.

[0022] In addition, the first electrode 51 and the second electrode 53 may each be provided with an extraction wiring portion and directly connected to the wiring portion 102 in an electrode manner via a contact opened in the vibration membrane. Also, an adhesion improving film for ensuring adhesion with the nozzle forming portion 111 may be formed on the second insulating film 8b.

[0023] The liquid filling the liquid ejection head 1 enters the nozzle 2 and forms a meniscus inside the nozzle. By applying a predetermined drive waveform (voltage) to each of the electrodes 51, 53 of the piezoelectric element 5, the piezoelectric film 52 vibrates, and the vibrating film 103 vibrates in the vertical direction in Figure 7. The vibration of the vibrating film 103 generates a pressure change in the liquid in the individual flow path, and the liquid is ejected from the nozzle 2.

[0024] In addition, in the liquid ejection head 1 of this embodiment, a protective film 11 is formed on the inner circumferential surface of the nozzle 2, the inner circumferential surface of the individual flow path 4, and the bottom surface of the common flow path 3 as a surface layer that has lyophilicity with respect to the liquid ejected by the liquid ejection head 1 and prevents erosion of the liquid. In this embodiment, the liquid ejected by the liquid ejection head 1 is alkaline, and the individual flow path substrate 100 and the vibration membrane 103 that form the individual flow path 4 are made of silicon single crystal and silicon oxide. These materials are vulnerable to alkaline liquid, and are dissolved and eroded by the alkaline solution. To prevent this, a liquid-resistant protective film 11 that prevents erosion of the liquid is formed, thereby protecting the individual flow path substrate 100 and the vibration membrane 103 from the liquid.

[0025] Furthermore, the individual flow paths 4 and the nozzle 2 are formed by dry etching. Since the dry etching gas contains fluorine, a fluorine-containing surface film is formed on the inner wall surfaces of the individual flow paths 4 and the inner circumferential surface of the nozzle 2 after etching, and the inner wall surfaces of the individual flow paths 4 and the inner circumferential surface of the nozzle become liquid repellent. If the inner circumferential surface of the individual flow paths 4 is liquid repellent, the liquid does not wet and spread over the inner circumferential surface of the individual flow paths 4 when filling the individual flow paths 4, and the individual flow paths 4 are not filled well with liquid, which may result in air bubbles forming in the corners of the individual flow paths 4.

[0026] In this embodiment, the protective film 11 having lyophilicity is formed on the inner circumferential surface of the individual flow path 4 and the inner circumferential surface of the nozzle 2, so that it is possible to improve the wettability of the liquid to the inner circumferential surfaces of the individual flow path 4 and the nozzle 2. The protective film 11 only needs to have a higher lyophilicity to the liquid than the film-forming surface (the lower surface of the protective film 11) of the individual flow path 4 and the nozzle 2 on which the protective film 11 is formed. When the solvent of the liquid is aqueous, a protective film with high hydrophilicity is used, and when the solvent of the liquid is oil-based, a protective film with high lipophilicity is used, so that the protective film 11 with high lyophilicity can be formed.

[0027] The material of the vibrating membrane 103 may be any material that has at least insulating properties, such as SiO2, SiN, metal oxide, resin, etc. However, in order to increase the displacement, a material with a low Young's modulus is desirable, and considering the difference in linear expansion coefficient with the individual flow path substrate 100, SiO2 (silicon dioxide) is relatively small, making it the most desirable material for the vibrating membrane 103.

[0028] The first electrode 51 and the second electrode 53 are desirably made of a metal having low electrical resistance and low reactivity, preferably Ir, Mo, or the like. When the drive circuit 101 and the wiring section 102 are built into the individual flow path substrate 100 to improve density as in this embodiment, the piezoelectric material constituting the piezoelectric film 52 is desirably a piezoelectric material whose film formation temperature is 450° C. or less in order to prevent them from being destroyed. Examples of piezoelectric materials whose film formation temperature is 450° C. or less include AlN and ScAlN, which has a higher piezoelectric constant than AlN.

[0029] Furthermore, by using ScAlN as the piezoelectric material, the following advantage can be obtained. That is, the piezoelectric characteristics can be improved by aligning the crystal orientation of the piezoelectric film 52, but an orientation control layer needs to be provided between the vibration film 103 and the first electrode 51 to control the orientation. When the piezoelectric material of the piezoelectric film 52 is ScAlN, the lattice constant of the first electrode 51 made of Mo can be made closer to that of ScAlN by using ScAlN as the orientation control layer as well. As a result, the crystal orientation of the piezoelectric film 52 is aligned, making it possible to improve the piezoelectric characteristics.

[0030] As shown in FIGS. 2 to 5, the liquid ejection head 1 of this embodiment is configured by arranging a nozzle plate 110, an individual flow path substrate 100, a common flow path substrate 120, a damper section 130, and a frame section 140 in this order.

[0031] The individual flow path substrate 100 has openings 4a of each individual flow path 4 open on the upper surface (the surface facing the common flow path 3) of the area (individual flow path array) in which multiple individual flow paths 4 are arranged, and is arranged so that the common flow path 3 formed in the common flow path substrate 120 faces the openings 4a of each individual flow path 4.

[0032] In this embodiment, as an example, the size of the individual flow path 4 (diameter of the opening 4a) is 220 [μm]. The width of the partition wall partitioning the individual flow paths 4 in the A row direction arranged in a direction parallel to the cross section A-A' is 30 [μm], and the center-to-center distance MA (see FIG. 2) of the openings 4a of two individual flow paths 4 adjacent in the A row direction is 250 [μm]. Similarly, the width of the partition wall partitioning the individual flow paths 4 in the B row direction arranged in a direction parallel to the cross section B-B' (head longitudinal direction) is also 30 [μm], and the center-to-center distance MB (see FIG. 3) of the openings 4a of two individual flow paths 4 adjacent in the B row direction is also 250 [μm].

[0033] A damper section 130 is provided on the upper surface of the common flow path substrate 120 (the surface opposite to the individual flow path substrate 100). The common flow path 3 is connected to the supply liquid storage chamber 31 formed in the frame section 140 via a supply communication path 32 formed in the damper section 130. The supply communication path 32 in this embodiment is branched into a plurality of paths (three in the illustrated example) by a partition wall 130a as shown in FIG. 6. Similarly, the discharge communication path 34 in this embodiment is branched into a plurality of paths (three in the illustrated example) by a partition wall 130b as shown in FIG. 6. These partition walls 130a and 130b mainly function as reinforcing materials to ensure the mechanical strength of the damper section 130, and are also intended to supply or discharge liquid evenly to the entire area of ​​the common flow path 3 (to supply or discharge liquid evenly to each individual flow path 4). Therefore, as long as the mechanical strength of the damper portion 130 can be ensured and the liquid can be supplied or discharged without bias, the partition walls 130a, 130b (reinforcement materials) may not be provided, and the supply communication passage 32 and the discharge communication passage 34 may each be formed as a single passage.

[0034] Liquid stored in an external liquid storage unit is supplied to the liquid ejection head 1 via a liquid supply port 33 of the frame unit 140. The liquid supplied from this liquid supply port 33 is supplied from the supply liquid storage chamber 31 through a supply communication passage 32 to the common flow path 3, and is supplied from the common flow path 3 to each individual flow path 4 via the openings 4a of each individual flow path 4.

[0035] Moreover, the common flow path 3 is connected to a discharge liquid storage chamber 35 formed in the frame portion 140 via a discharge communication passage 34 formed in the damper portion 130. As a result, the liquid in the common flow path 3 passes from the discharge communication passage 34 through the discharge liquid storage chamber 35, and from the liquid discharge port 36 via an external pump or the like, and is returned to an external ink storage portion. This embodiment is a liquid discharge head 1 that uses a liquid circulation system.

[0036] According to this embodiment, it is possible to circulate the liquid in the common flow path 3. This makes it possible to eliminate air bubbles present in the flow paths in the liquid ejection head 1, such as the common flow path 3, and to prevent the liquid components from settling in the flow paths in the liquid ejection head 1, such as the common flow path 3, when using a liquid that has components that tend to settle.

[0037] In particular, in this embodiment, the supply communication passage 32 and the discharge communication passage 34 are formed on either side of the individual flow passage array on the outer side of the head in the short side direction. Therefore, the distance over which the liquid flows in the common flow passage 3 facing the individual flow passage array (the longest distance when the liquid flows from the supply communication passage 32 to the discharge communication passage 34) is minimized. Therefore, the fluid resistance of the liquid in the common flow passage 3 can be kept low.

[0038] Note that this embodiment is not limited to a liquid circulation type liquid ejection head 1, and may be configured, for example, without a configuration for discharging liquid from the common flow path 3 to the outside of the head (discharge communication passage 34, discharge liquid storage chamber 35, liquid discharge port 36).

[0039] 2 to 5, in this embodiment, the damper section 130 is composed of a damper film 61 as a damper member, a damper film holding member 62 that holds the damper film 61, and an air chamber 63 for ensuring the displacement or vibration of the damper film 61. The air chamber 63 is open to the outside air via an air vent hole 64.

[0040] The damper film 61 is made of a highly flexible material, and is disposed at a position facing the openings 4a of each individual flow path 4 (i.e., the upper surface of the individual flow path array of the individual flow path substrate 100) across the common flow path 3. That is, the damper film 61 constitutes one wall portion (upper wall surface) of the common flow path 3. With this configuration, the damper portion 130 is capable of reducing pressure fluctuations due to the crosstalk pressure generated in the common flow path 3 by the damper film 61 deforming in response to the crosstalk pressure propagating to the liquid in the common flow path 3, and thus exhibiting an effect of suppressing crosstalk (fluid crosstalk).

[0041] When the piezoelectric element 5 of the nozzle plate 110 vibrates the vibrating membrane 103 to pressurize the liquid in the individual flow paths 4, the pressure becomes a force that ejects the liquid from the nozzle 2, but a part of the pressure escapes from the opening 4a of the individual flow path 4 to the common flow path 3 and becomes crosstalk pressure. The crosstalk pressure that escapes to the common flow path 3 propagates through the liquid in the common flow path 3 and flows around to other surrounding individual flow paths 4, causing fluctuations in the pressure of the liquid in the other individual flow paths 4 and affecting the ejection of the liquid in those other individual flow paths 4 from the nozzle 2.

[0042] In the liquid ejection head 1 of this embodiment, nozzles are arranged in a two-dimensional direction, so that two or more nozzles (for example, adjacent nozzles 2A, 2B, i.e., nozzles that are affected by crosstalk) are arranged adjacent to one nozzle (for example, a nozzle of interest 2S, i.e., a nozzle that is affected by crosstalk). Therefore, the crosstalk pressures generated in the individual flow paths 4A, 4B of the two or more adjacent nozzles 2A, 2B are propagated to the individual flow path 4S of the nozzle of interest 2S.

[0043] In a liquid ejection head 1 with a high nozzle density as in this embodiment, the distance between the openings 4a (center-to-center distances MA, MB) of the individual flow paths 4 of adjacent nozzles (a target nozzle 2S and adjacent nozzles 2A, 2B) is small. Therefore, the crosstalk pressure from the individual flow paths 4A, 4B of two or more adjacent nozzles 2A, 2B reaches the individual flow path 4S of the target nozzle 2S with almost no time difference. Therefore, the crosstalk pressures from the individual flow paths 4A, 4B of two or more adjacent nozzles 2A, 2B that reach the individual flow path 4S of the target nozzle 2S have almost no phase difference with each other and reinforce each other, resulting in a large impact of crosstalk.

[0044] Specifically, the period of the crosstalk pressure is usually matched to the resonance period Tc of the individual flow path 4. Therefore, the wavelength λ of the crosstalk pressure can be calculated from λ=Tc×C using the pressure propagation speed C of the pressure propagating through the liquid in the common flow path. In a liquid ejection head 1 with a high nozzle density, the wavelength λ of the crosstalk pressure calculated in this way is much longer than the distance between the individual flow path openings (the center-to-center distances MA and MB of the openings) of adjacent nozzles (the nozzle of interest 2S and the adjacent nozzles 2A and 2B). Therefore, the crosstalk pressures from the individual flow paths 4A and 4B of the two or more adjacent nozzles 2A and 2B that reach the individual flow path 4S of the nozzle of interest 2S hardly have a phase difference with each other, and reinforce each other, resulting in a large effect of crosstalk.

[0045] Here, if the individual flow paths 4A, 4B of the two or more adjacent nozzles 2A, 2B are configured to reach the individual flow path 4S of the nozzle of interest 2S with a phase difference such that the crosstalk pressures from the individual flow paths 4A, 4B are sufficiently offset from each other, the effects of crosstalk can be suppressed. However, if the distance difference (MA-MB) between the individual flow path opening distance (opening center distance MB) between some of the two or more adjacent nozzles 2A, 2B (e.g., adjacent nozzle 2B) and the nozzle of interest 2S and the individual flow path opening distance (opening center distance MA) between another of the two or more adjacent nozzles (e.g., adjacent nozzle 2A) and the nozzle of interest 2S is set to a phase difference such that the crosstalk pressures of both are sufficiently offset from each other, the nozzle density will be significantly reduced. In other words, even if the former distance between individual flow path openings (distance between opening centers MB) is set to be greater than the latter distance between individual flow path openings (distance between opening centers MA) by, for example, the former distance between individual flow path openings (distance between opening centers MB) will be much greater than the typical distance between individual flow path openings in a liquid ejection head 1 with a high nozzle density, and the nozzle density will have to be reduced.

[0046] Therefore, in this embodiment, a bypass partition 121a serving as a bypass member for lengthening the in-liquid pressure propagation path length (path length of crosstalk pressure) between the openings 4a of the individual flow path 4B corresponding to the adjacent nozzle 2B adjacent to the focus nozzle 2S in the row B direction and the opening 4a of the individual flow path 4S corresponding to the focus nozzle 2S is disposed in the common flow path 3. The "in-liquid pressure propagation path length" here refers to the shortest path length for the crosstalk pressure generated in the individual flow path 4B of the adjacent nozzle 2B to propagate through the liquid in the common flow path 3 and reach the individual flow path 4S of the focus nozzle 2S.

[0047] By disposing such a bypass partition 121a, the crosstalk pressure generated in the individual flow path 4B of the adjacent nozzle 2B adjacent to the focus nozzle 2S in the row B direction will bypass the bypass partition 121a in the common flow path 3 and reach the individual flow path 4S of the focus nozzle 2S, as shown in Fig. 3. This makes it possible to extend the internal liquid pressure propagation path length (path length of crosstalk pressure) LB from the individual flow path 4B of the adjacent nozzle 2B to the individual flow path 4S of the focus nozzle 2S while maintaining the distance between the individual flow path openings (the distance between the opening centers MB) between the adjacent nozzle 2B and the focus nozzle 2S. As a result, without widening the distance between the individual flow path openings (the opening center distance MB) between the adjacent nozzle 2B and the nozzle of interest 2S, it is possible to make the difference (LA-LB) between the liquid pressure propagation path length LB from the individual flow path 4B of the adjacent nozzle 2B to the individual flow path 4S of the nozzle of interest 2S and the liquid pressure propagation path length LA (= the opening center distance MA) from the individual flow path 4A of the other adjacent nozzle, the adjacent nozzle 2A in the A row direction, to the individual flow path 4S of the nozzle of interest 2S, a predetermined path length difference such that the respective crosstalk pressures are sufficiently canceled out by each other.

[0048] The configuration of the common flow path 3 including the bypass partition portion 121a will be further described. 2 to 5, the common flow path substrate 120 in this embodiment is composed of a partition wall substrate 121 constituting the bypass partition wall portion 121a, and a flow path securing substrate 122. The partition wall substrate 121 and the flow path securing substrate 122 are formed in this order on the individual flow path substrate 100. The flow path securing substrate 122 is for securing a space that becomes the common flow path 3 between the partition wall substrate 121 and the damper portion 130.

[0049] As shown in Fig. 1, the partition substrate 121 has a configuration in which a plurality of long through holes 121b are arranged in the row B direction (head longitudinal direction) along the row A direction. As shown in Fig. 1, each through hole 121b is arranged across five nozzle rows extending in the row B direction (head longitudinal direction) so as to face the openings 4a of the individual flow paths 4 of five nozzles (including the target nozzle 2S and the adjacent nozzle 2A) adjacent to each other between the nozzle rows. As a result, the partition walls separating the plurality of through holes 121b form linear wall sections that linearly cross the five nozzle rows by passing between the openings 4a of the individual flow paths 4 of the nozzles (including the target nozzle 2S and the adjacent nozzle 2B) adjacent to each other in each of the five nozzle rows.

[0050] The linear wall portion is formed in the common flow path 3 between the opening 4a of the individual flow path 4S of the focused nozzle 2S and the opening 4a of the individual flow path 4B of the adjacent nozzle 2B adjacent to the focused nozzle 2S in the row B direction. Therefore, this linear wall portion functions as a bypass partition 121a that lengthens the liquid pressure propagation path length (path length of crosstalk pressure) between the openings. As a result, the crosstalk pressure generated in the individual flow path 4B of the adjacent nozzle 2B adjacent to the focused nozzle 2S in the row B direction bypasses the bypass partition 121a in the common flow path 3 and reaches the individual flow path 4S of the focused nozzle 2S, as shown in FIG. 3 as the liquid pressure propagation path length LB.

[0051] Meanwhile, in the common flow path 3, the opening 4a of the individual flow path 4S of the focused nozzle 2S and the opening 4a of the individual flow path 4A of the adjacent nozzle 2A adjacent to the focused nozzle 2S in the row A direction are connected by a through hole 121b, and no bypass partition portion 121a is arranged. Therefore, the crosstalk pressure generated in the individual flow path 4A of the adjacent nozzle 2A adjacent to the focused nozzle 2S in the row A direction reaches the individual flow path 4S of the focused nozzle 2S without detouring, as shown in FIG. 2 by the internal pressure propagation path length LA (= center-to-center distance MA of the openings).

[0052] The in-liquid pressure propagation path length LA for the crosstalk pressure in the A row direction is determined by the center-to-center distance MA of the openings of the individual flow paths 4A of the adjacent nozzle 2A adjacent to the target nozzle 2S in the A row direction. In contrast, the in-liquid pressure propagation path length LB for the crosstalk pressure in the B row direction is determined by the center-to-center distance MB of the openings of the individual flow paths 4B of the adjacent nozzle 2B adjacent to the target nozzle 2S in the B row direction and the height H of the bypass partition 121a (thickness of the partition substrate 121). Therefore, by appropriately setting the height H of the bypass partition 121a (thickness of the partition substrate 121), the difference (LA-LB) between the in-liquid pressure propagation path length LA for the crosstalk pressure in the A row direction and the in-liquid pressure propagation path length LB for the crosstalk pressure in the B row direction can be set to a predetermined path length difference ΔL such that the respective crosstalk pressures can be sufficiently offset by each other, without increasing the center-to-center distances MA and MB. The height H of the bypass partition 121a (the thickness of the partition substrate 121) is preferably, for example, 750 μm or more.

[0053] Such a predetermined path length difference ΔL is preferably set so as to satisfy the following formula (1), where Tc is the resonance period (natural vibration period) of the individual flow path 4 and C is the pressure propagation speed propagating through the liquid in the common flow path 3.

[0054]

number

[0055] By setting the difference (LA-LB) between the liquid pressure propagation path lengths LA, LB in the row A direction and row B direction so that the path length difference ΔL satisfies the above formula (1), the phase difference between the crosstalk pressures reaching the individual flow path 4S of the nozzle 2S of interest is within the range of 1 / 2±1 / 4, and a sufficient cancellation effect between the crosstalk pressures is obtained.

[0056] In this embodiment, it is preferable that the liquid pressure propagation path length LA between the opening 4a of the individual flow path 4A of the adjacent nozzle 2A adjacent to the focal nozzle 2S in the row A direction and the opening 4a of the individual flow path 4S of the focal nozzle 2S be set so as to satisfy the following equation (2).

[0057]

number

[0058] According to this embodiment, the crosstalk pressure in the A row direction and the crosstalk pressure in the B row direction have a phase difference that cancels each other out. However, since the path length of the crosstalk pressure in the A row direction (intra-liquid pressure propagation path length LA) is shorter than the path length of the crosstalk pressure in the B row direction (intra-liquid pressure propagation path length LB), the crosstalk pressure in the A row direction has a smaller attenuation rate than the crosstalk pressure in the B row direction. Therefore, even if the phase difference (ΔL=(2n-1) / 2×Tc×C) is such that the crosstalk pressure in the B row direction can just cancel the crosstalk pressure in the A row direction, the crosstalk pressure in the A row direction remains. By setting the intra-liquid pressure propagation path length LA between the opening 4a of the individual flow path 4A of the adjacent nozzle 2A in the A row direction and the opening 4a of the individual flow path 4S of the target nozzle 2S to satisfy the above formula (2), the remaining crosstalk pressure in the A row direction can stably suppress the influence of crosstalk when the target nozzle 2S is driven.

[0059] That is, the adjacent nozzle that is most affected by crosstalk with respect to the driven nozzle (focus nozzle 2S) is the adjacent nozzle 2A in the A-row direction, which has the shortest internal pressure propagation path length (path length of crosstalk pressure). Therefore, most of the crosstalk pressure in the A-row direction that remains after cancellation by the crosstalk pressure in the B-row direction is due to the crosstalk pressure from the adjacent nozzle 2A. Therefore, if the crosstalk pressure from the adjacent nozzle 2A in the A-row direction just strengthens the pressure fluctuation (pressure fluctuation caused by driving the piezoelectric element 5 of the focus nozzle 2S) that occurs in the individual flow path 4S of the driven nozzle (focus nozzle 2S), the crosstalk pressure in the A-row direction that remains after cancellation by the crosstalk pressure in the B-row direction will excessively increase the amplitude of the pressure fluctuation that occurs in the individual flow path 4S of the focus nozzle 2S, and there is a high possibility that the liquid ejection speed will deviate significantly from the desired ejection speed. Conversely, if the crosstalk pressure from the adjacent nozzle 2A in the A row direction just weakens the pressure fluctuations occurring in the individual flow path 4S of the nozzle of interest 2S, the crosstalk pressure in the A row direction that remains after being offset by the crosstalk pressure in the B row direction will excessively reduce the amplitude of the pressure fluctuations occurring in the individual flow path 4S of the nozzle of interest 2S, which may result in the liquid ejection speed deviating significantly from the desired ejection speed or may result in non-ejection.

[0060] When the above-mentioned formula (2) is satisfied, the phase difference between the crosstalk pressure from the adjacent nozzle 2A in the A row direction and the pressure fluctuation occurring in the individual flow path 4S of the target nozzle 2S is within the range of 1 / 4±1 / 8. Therefore, the phase of the crosstalk pressure in the A row direction remaining after being offset by the crosstalk pressure in the B row direction is different from the phase difference that just strengthens the pressure fluctuation occurring in the individual flow path 4S of the target nozzle 2S (i.e., there is no phase difference) and the phase difference that just weakens the pressure fluctuation (i.e., the phase difference is shifted by 1 / 2). As a result, it is possible to avoid excessively increasing or decreasing the amplitude of the pressure fluctuation occurring in the individual flow path 4S of the target nozzle 2S, and it is possible to stably suppress the influence of crosstalk on the target nozzle 2S.

[0061] Furthermore, if a specified path length difference ΔL is set to satisfy the following equation (3), then in theory, the phase difference between the crosstalk pressures reaching the individual flow path 4S of the nozzle 2S of interest will be 1 / 2, and the crosstalk pressures will cancel each other out.

[0062]

number

[0063] According to this embodiment, the crosstalk pressures from the individual flow paths 4A and 4B of the adjacent nozzles 2A and 2B that reach the individual flow path 4S of the nozzle of interest 2S are sufficiently offset with each other, so that the influence of the crosstalk on the liquid ejection of the nozzle of interest 2S (ejection defects such as fluctuations in the ejection speed of the liquid and ejection failures) is suppressed. Moreover, according to this embodiment, by using the bypass partition 121a, a predetermined path length difference ΔL that can sufficiently offset the crosstalk pressure can be realized without widening the center-to-center distances MA and MB of the openings. Therefore, without widening the nozzle pitch in the row A direction or row B direction (or by only slightly widening the nozzle pitch), the crosstalk pressure that reaches the individual flow path 4S of the nozzle of interest 2S can be sufficiently offset, and the influence of the crosstalk on the liquid ejection of the nozzle of interest 2S can be suppressed.

[0064] In particular, according to this embodiment, the influence of structural crosstalk (surface vibration) can also be suppressed. That is, the vibration generated when the actuator is driven generates a surface vibration that bends the entire substrate, and this surface vibration generates a pressure distribution in the common flow path 3, which generates structural crosstalk in addition to the crosstalk (fluid crosstalk) caused by the propagation of the crosstalk pressure described above. The configuration in which the common flow path substrate includes the partition wall substrate 121 and the bypass partition wall portion 121a is disposed in the common flow path 3 as in this embodiment has a higher rigidity as a substrate structure than a configuration in which the common flow path substrate does not have the partition wall substrate 121 and the bypass partition wall portion 121a is not disposed in the common flow path 3. The higher the rigidity, the smaller the amplitude of the generated surface vibration becomes, and the vibration frequency can also be shifted to the high frequency side (a frequency band farther away from the liquid ejection frequency). Therefore, according to this embodiment, by disposing the bypass partition wall portion 121a, it is possible to suppress the influence of structural crosstalk (surface vibration) (ejection defects such as fluctuations in the liquid ejection speed and non-ejection).

[0065] Fig. 10 is a graph comparing pressure fluctuations occurring in the individual flow path 4S of the target nozzle 2S when only the target nozzle 2S is driven (when there is no crosstalk pressure) and when not only the target nozzle 2S but also the adjacent nozzles 2A and 2B are driven (when there is crosstalk pressure). The graph in Fig. 10(a) is for a comparative example in which the bypass partition 121a is not arranged and the difference (LA-LB) between the internal liquid pressure propagation path lengths LA and LB in the row A direction and row B direction is zero, while the graph in Fig. 10(b) is for this embodiment in which the bypass partition 121a is arranged and the difference (LA-LB) between the internal liquid pressure propagation path lengths LA and LB in the row A direction and row B direction satisfies the above formula (3).

[0066] In the comparative example shown in FIG. 10(a), when crosstalk pressure is applied, the amplitude of the pressure fluctuation occurring in the individual flow path 4S of the target nozzle 2S is stronger and the phase is shifted compared to when only the target nozzle 2S is driven. In contrast, in the present embodiment shown in FIG. 10(b), even when crosstalk pressure is applied, the pressure fluctuation occurring in the individual flow path 4S of the target nozzle 2S has the same amplitude as when only the target nozzle 2S is driven, and there is almost no phase shift. Therefore, according to the present embodiment, even when only the target nozzle 2S is driven (when crosstalk pressure is not applied), and even when not only the target nozzle 2S but also the adjacent nozzles 2A and 2B are driven (when crosstalk pressure is applied), the discharge speed and discharge timing are not shifted, and liquid can be discharged at the desired discharge speed and discharge timing.

[0067] Furthermore, according to this embodiment, there is an advantage that the ability to supply liquid from the common flow path 3 to each of the individual flow paths 4 can be easily ensured. That is, the damper section 130 provided to suppress the influence of crosstalk (fluid / structure crosstalk) is disposed closer to the opening 4a of the individual flow path 4, the more effective the crosstalk suppression. However, if the damper section 130 is disposed too close to the opening 4a of the individual flow path 4, the height of the common flow path 3 is lowered, and the liquid does not easily flow in the common flow path 3, which reduces the liquid supply capacity to each individual flow path 4, resulting in poor discharge or non-discharge due to insufficient liquid supply to each individual flow path 4. In this embodiment, the influence of crosstalk is suppressed by disposing the bypass partition section 121a in the common flow path 3, so that the influence of crosstalk is suppressed even if the damper section 130 is not disposed too close to the opening 4a of the individual flow path 4. Therefore, the influence of crosstalk can be suppressed without causing insufficient liquid supply capacity to each individual flow path 4.

[0068] In particular, in this embodiment, as shown in FIG. 6, the supply communication passage 32 for supplying liquid to the common flow passage 3 is provided at one end of the head short side direction perpendicular to the B row direction (head longitudinal direction), and the discharge communication passage 34 for discharging liquid from the common flow passage 3 is provided at the other end of the head short side direction. With this configuration, the flow of liquid in the common flow passage 3 flows from the supply communication passage 32 along the head short side direction toward the discharge communication passage 34. At this time, in the common flow passage 3 in this embodiment, a long through hole 121b is arranged along the A row direction so as to pass through the opening 4a of the individual flow passage 4 of the nozzle aligned in the A row direction. The A row direction in which this through hole 121b extends forms a small angle with the head short side direction and is approximately parallel to the head short side direction. Therefore, the liquid flowing in the common flow passage 3 in the head short side direction can flow smoothly through each through hole 121b without being hindered by the bypass partition wall portion 121a. Therefore, even if the bypass partition 121a is provided in the common flow path 3, the liquid supply capability from each of the through holes 121b to each of the individual flow paths 4 can be maintained.

[0069] Furthermore, even if a bypass partition section 121a is provided within the common flow path 3, the ability to supply liquid from each long through hole 121b to each individual flow path 4 can be maintained, so that the damper section 130 can be brought closer to the opening 4a of the individual flow path 4, thereby achieving a further crosstalk suppression effect.

[0070] In this embodiment, the influence of crosstalk is suppressed by arranging the bypass partition 121a in the common flow path 3, and the damper unit 130 is also used to suppress the influence of crosstalk, but this is not limited to the above. For example, if the influence of crosstalk can be sufficiently eliminated by simply arranging the bypass partition 121a in the common flow path 3, a configuration without arranging the damper unit 130 can be adopted. In this case, the arrangement of the damper unit 130 will not cause a shortage in the liquid supply capacity to each individual flow path 4.

[0071] In the present embodiment, the dimensions of the through-hole 121b of the partition substrate 121 are set to be equal to or larger than the dimensions of the openings 4a of the individual flow paths 4, and the through-hole 121b of the partition substrate 121 is formed to include the entire openings 4a of the individual flow paths 4, but this is not limited thereto. For example, as shown in Fig. 8 and Fig. 9, the dimensions of the through-hole 121b of the partition substrate 121 may be formed to be smaller than the dimensions of the openings 4a of the individual flow paths 4. In this case, the opening area of ​​the openings 4a of the individual flow paths 4 is narrowed and the fluid resistance is increased, so that the crosstalk pressure coming from the openings 4a of the individual flow paths 4 can be suppressed, and as a result, the influence of crosstalk in the individual flow path 4S of the focused nozzle 2S can be suppressed.

[0072] In this embodiment, an example of a liquid ejection head 1 using a nozzle plate vibration method has been described, but the present invention is not limited to a driving method, etc., as long as the liquid ejection head has a common flow path that faces the openings of the individual flow paths located on the side opposite the nozzle plate (nozzle forming wall).

[0073] For example, the actuator of the nozzle plate vibration type liquid ejection head may be disposed on the nozzle plate 110 (nozzle forming wall) as shown in FIG. 11(a), may be disposed in the nozzle plate 110 as shown in FIG. 11(b), or may be disposed near the nozzle plate 110 (near the nozzle plate 110 in the individual flow path 4) as shown in FIG. 11(c). The actuator may be a piezoelectric element 5, which is an electromechanical conversion element that displaces the nozzle plate 110 (nozzle forming wall) as shown by the arrow A in the figure, or a thermomechanical conversion element such as a bimetal, as shown in FIG. 11(a) and FIG. 11(b), or may be replaced with a driving means such as a heater element 5' that generates bubbles B in the liquid in the individual flow path 4 as shown in FIG. 11(c). The configurations of the actuators exemplified in FIG. 11(a) to (c) all simplify the flow path configuration, and the flow path configuration from the individual flow path 4 to the nozzle 2 can be manufactured with one part. Therefore, it is easy to realize a small-sized, high-density, low-cost, and high-definition liquid ejection head.

[0074] Next, an example of a liquid ejecting device according to the present invention will be described with reference to FIGS. FIG. 12 is a schematic explanatory diagram of a printing apparatus, which is an inkjet recording apparatus, which is an image forming apparatus serving as an apparatus for discharging liquid in this embodiment. FIG. 13 is an explanatory plan view of an example of a head unit of the printing device of this embodiment.

[0075] A printing device 500 which is an apparatus for discharging this liquid includes a carry-in means 501 for carrying in a continuum 510, and a guide / conveyance means 503 for guiding and conveying the continuum 510 carried in from the carry-in means 501 to a printing means 505. The printing device 500 also includes a printing means 505 for printing the continuum 510 by discharging liquid onto the continuum 510 to form an image, a drying means 507 for drying the continuum 510, and a conveyance means 509 for conveying the continuum 510 out.

[0076] The continuous web 510 is sent out from a main winding roller 511 of the carry-in means 501, guided and transported by the rollers of the carry-in means 501, the guide and transport means 503, the drying means 507, and the carry-out means 509, and taken up by a take-up roller 591 of the carry-out means 509. In the printing means 505, the continuous web 510 is transported on a transport guide member 559 facing the head unit 550, and an image is printed by liquid ejected from the head unit 550.

[0077] In a printing device 500 of this embodiment, a head unit 550 includes the two head modules 100A and 100B according to this embodiment described above, mounted on a common base member 552.

[0078] When the direction in which the liquid ejection heads 1 are arranged in a direction perpendicular to the transport direction of the head modules 100A and 100B is defined as the head arrangement direction, the head arrays 1A1 and 1A2 of the head module 100A eject liquid of the same color. Similarly, the head arrays 1B1 and 1B2 of the head module 100A are grouped together, the head arrays 1C1 and 1C2 of the head module 100B are grouped together, and the head arrays 1D1 and 1D2 are grouped together, and each ejects liquid of a required color.

[0079] Next, another example of a printing apparatus as a liquid ejecting apparatus according to the present invention will be described with reference to FIGS. FIG. 14 is an explanatory plan view of the main part of the printing apparatus of this embodiment. FIG. 15 is an explanatory side view of the main part of the printing apparatus of this embodiment.

[0080] The printing device 500 of this example is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by a main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is hung between left and right side plates 491A and 491B to movably hold the carriage 403. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via a timing belt 408 hung between a drive pulley 406 and a driven pulley 407.

[0081] This carriage 403 is equipped with a liquid ejection unit 440 that integrates the liquid ejection head 1 according to the present invention and a head tank 441. The liquid ejection head 1 ejects liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 1 is mounted with a nozzle row made up of a plurality of nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ejection direction facing downward. The liquid ejection head 1 is connected to a liquid circulation device, and liquid of the required color is circulated and supplied.

[0082] The printing device 500 includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412 as a transport means, and a sub-scanning motor 416 for driving the transport belt 412. The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid ejection head 1. The transport belt 412 is an endless belt that is stretched between a transport roller 413 and a tension roller 414. The paper 410 can be attracted by electrostatic attraction or air suction. The transport belt 412 moves in a circular motion in the sub-scanning direction by the transport roller 413 being rotated and driven by the sub-scanning motor 416 via a timing belt 417 and a timing pulley 418.

[0083] Furthermore, a maintenance and recovery mechanism 420 that maintains and recovers the liquid ejection head 1 is disposed on one side of the carriage 403 in the main scanning direction, beside the conveyor belt 412. The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface of the liquid ejection head 1, a wiper member 422 that wipes the nozzle surface, and the like. In addition, the main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the conveyor mechanism 495 are attached to a housing that includes side plates 491A and 491B and a back plate 491C.

[0084] In the printing device 500 configured in this manner, the paper 410 is fed onto and adsorbed to the conveyor belt 412, and the paper 410 is conveyed in the sub-scanning direction by the circular movement of the conveyor belt 412. Then, by driving the liquid ejection head 1 in response to an image signal while moving the carriage 403 in the main scanning direction, liquid is ejected onto the stationary paper 410 to form an image.

[0085] Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 16 is a plan view illustrating the main parts of the liquid discharge unit of this embodiment.

[0086] This liquid ejection unit 440 is composed of a housing portion consisting of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid ejection head 1, which are components that make up the device that ejects the liquid.

[0087] It is also possible to configure a liquid discharge unit in which the above-mentioned maintenance and recovery mechanism 420 is further attached to, for example, the side plate 491B of this liquid discharge unit 440.

[0088] Next, still another example of the liquid discharge unit according to the present invention will be described with reference to FIG. FIG. 17 is a front view illustrating the liquid discharge unit of this embodiment.

[0089] This liquid discharge unit 440 is composed of a liquid discharge head 1 to which a flow path part 444 is attached, and a tube 456 connected to the flow path part 444 .

[0090] The flow path part 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path part 444. Furthermore, a connector 443 for electrically connecting with the liquid ejection head 1 is provided on the upper part of the flow path part 444.

[0091] In the present application, the liquid to be ejected may have a viscosity and surface tension that allows it to be ejected from the head, and is not particularly limited, but it is preferable that the viscosity of the liquid is 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, calcium, or an edible material such as a natural dye, etc. These may be used, for example, in applications such as inkjet ink, surface treatment liquid, a liquid for forming a component of an electronic element or a light-emitting element, a resist pattern for an electronic circuit, a material liquid for three-dimensional modeling, etc.

[0092] A "liquid ejection unit" is a liquid ejection head integrated with functional parts and mechanisms, and includes a collection of parts related to ejecting liquid. For example, a "liquid ejection unit" includes a combination of a liquid ejection head and at least one of the following components: a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, a main scanning movement mechanism, and a liquid circulation device.

[0093] Here, integration includes, for example, a liquid ejection head, a functional part, and a mechanism that are fixed to each other by fastening, bonding, engaging, etc., and one is held movably relative to the other. Also, the liquid ejection head, the functional part, and the mechanism may be configured to be detachable from each other.

[0094] For example, there are liquid ejection units in which the liquid ejection head and the head tank are integrated together, and there are also liquid ejection units in which the liquid ejection head and the head tank are integrated together by being connected to each other by a tube, etc. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

[0095] Furthermore, there is a liquid ejection unit in which the liquid ejection head and the carriage are integrated.

[0096] In some liquid ejection units, the liquid ejection head is movably supported by a guide member that constitutes a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated together, and in some liquid ejection units, the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated together.

[0097] Furthermore, there is a liquid ejection unit in which a cap member, which is part of the maintenance and recovery mechanism, is fixed to a carriage on which the liquid ejection head is attached, thereby integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

[0098] In addition, some liquid ejection units have a head tank or a liquid ejection head to which a flow path component is attached, and a tube is connected to the liquid ejection head, integrating the liquid ejection head with a supply mechanism. Liquid is supplied from a liquid storage source to the liquid ejection head via this tube.

[0099] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0100] Note that, here, the "liquid ejection unit" is described in combination with a liquid ejection head, but the "liquid ejection unit" also includes a head module or head unit including the liquid ejection head described above, which is integrated with the functional components and mechanisms described above.

[0101] The term "liquid ejection device" includes devices that are equipped with a liquid ejection head, a liquid ejection unit, a head module, a head unit, etc., and that eject liquid by driving the liquid ejection head. Liquid ejection devices include not only devices that can eject liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0102] This "liquid ejecting device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0103] For example, examples of "devices that eject liquid" include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0104] In addition, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves and devices that create three-dimensional images.

[0105] The above-mentioned "object to which liquid can adhere" means an object to which liquid can adhere at least temporarily, and to which the liquid adheres and sticks, or to which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording media, electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects to which liquid can adhere.

[0106] The material of the above-mentioned "object to which liquid can adhere" may be any material to which liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics.

[0107] Furthermore, the "liquid ejection device" may be a device in which a liquid ejection head and an object to which liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which a liquid ejection head moves, a line type device in which a liquid ejection head does not move, etc.

[0108] Other examples of "liquid ejecting devices" include treatment liquid application devices that eject treatment liquid onto paper to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There are also spray granulation devices that spray a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0109] In the present application, the terms image formation, recording, printing, imprinting, printing, modeling, and the like are all synonymous.

[0110] The above description is merely an example, and each of the following aspects provides unique effects. [First aspect] The first aspect is a liquid ejection head 1 including a plurality of nozzles 2 for ejecting liquid, a plurality of individual flow paths 4 each connected to the plurality of nozzles, a plurality of actuators (e.g., piezoelectric elements 5) provided for each of the plurality of individual flow paths, and a common flow path 3 facing each opening 4a of the plurality of individual flow paths located on the side facing a nozzle forming wall (e.g., a nozzle plate 110) of the plurality of individual flow paths, and driving the actuators to eject liquid in the individual flow paths from the nozzles, and in the common flow path, a portion of a plurality of adjacent nozzles 2A, 2B adjacent to a target nozzle 2S is provided. A bypass member (e.g., a bypass partition portion 121a) is arranged between the opening of an individual flow path 4B corresponding to B and the opening of an individual flow path 4S corresponding to the target nozzle 2S, which makes a first liquid-internal pressure propagation path length LB between the openings longer than a second liquid-internal pressure propagation path length LA between the opening of an individual flow path 4A corresponding to another adjacent nozzle 2A among the multiple adjacent nozzles and the opening of the individual flow path 4S corresponding to the target nozzle 2S, and is configured so that the difference (LA-LB) between the first liquid-internal pressure propagation path length LB and the second liquid-internal pressure propagation path length LA is a predetermined path length difference ΔL. When the walls of the flow paths from the common flow path to each individual flow path are made of a damper member made of an elastic material, as in the case of conventional liquid ejection heads, it is necessary to secure a space for arranging the damper member having a relatively wide width (length in a direction perpendicular to the flow path direction from the common flow path to each individual flow path). Therefore, it is difficult to shorten the distance between the openings of adjacent individual flow paths (distance between individual flow path openings), and therefore difficult to shorten the distance between nozzles, and difficult to increase the number of nozzles per unit area (increase nozzle density). On the other hand, in a typical liquid ejection head, two or more nozzles (adjacent nozzles) are arranged adjacent to one nozzle (nozzle of interest). Therefore, liquid pressure waves (crosstalk pressure) caused by actuator drive in the individual flow paths of the two or more adjacent nozzles are propagated to the individual flow path of the nozzle of interest. In recent liquid ejection heads with high nozzle density, the distance between the openings of the individual flow paths of adjacent nozzles (nozzle of interest and adjacent nozzles) is small. Therefore, the crosstalk pressure from the individual flow paths of the two or more adjacent nozzles reaches the individual flow path of the nozzle of interest with almost no time difference. Therefore, the crosstalk pressures from the individual flow paths of the two or more adjacent nozzles that reach the individual flow path of the nozzle of interest have almost no phase difference with each other and reinforce each other, resulting in many crosstalk effects (such as fluctuations in the liquid ejection speed). More specifically, since the period of the crosstalk pressure is normally matched to the resonance period Tc of the individual flow paths, the wavelength λ of the crosstalk pressure can be calculated from λ = Tc × C, where C is the pressure propagation speed propagating through the liquid in the common flow path. In recent liquid ejection heads with high nozzle density, the wavelength λ of the crosstalk pressure calculated in this way is much longer than the distance between the individual flow path openings of adjacent nozzles (a target nozzle and adjacent nozzles). Therefore, the crosstalk pressures from the individual flow paths of two or more adjacent nozzles that reach the individual flow paths of the target nozzle have almost no phase difference with each other and reinforce each other, resulting in a large effect of crosstalk. Here, if the crosstalk pressures from the individual flow paths of two or more adjacent nozzles reach the individual flow paths of the nozzle of interest with a phase difference that sufficiently cancels each other out, the effect of crosstalk can be suppressed. However, if the difference in distance between the individual flow path openings between some of the two or more adjacent nozzles and the nozzle of interest and the individual flow path openings between the other of the two or more adjacent nozzles and the nozzle of interest is set to a phase difference that sufficiently cancels out the crosstalk pressures of both, the nozzle density will be significantly reduced. In other words, even if the distance between the former individual flow path openings is made larger than the distance between the latter individual flow path openings by, for example, the shortest phase difference (λ / 2), the distance between the former individual flow path openings will be much larger than the distance between the individual flow path openings of adjacent nozzles in recent liquid ejection heads with high nozzle density, and the nozzle density will be inevitably reduced. Therefore, in this embodiment, a bypass member is disposed in the common flow path between an opening of an individual flow path corresponding to a part of the adjacent nozzles among the plurality of adjacent nozzles adjacent to the nozzle of interest and an opening of an individual flow path corresponding to the nozzle of interest, so as to make the first liquid pressure propagation path length (path length of crosstalk pressure) between the openings longer than the second liquid pressure propagation path length between the opening of an individual flow path corresponding to the other adjacent nozzles among the plurality of adjacent nozzles and the opening of an individual flow path corresponding to the nozzle of interest. The "liquid pressure propagation path length" here means the shortest path length for the crosstalk pressure generated in the individual flow path of the adjacent nozzle to propagate through the liquid in the common flow path and reach the individual flow path of the nozzle of interest. By disposing such a bypass member, the crosstalk pressure generated in the individual flow path of the part of the adjacent nozzle will bypass the bypass member in the common flow path and reach the individual flow path of the nozzle of interest. As a result, for example, even while maintaining the distance between the individual flow path openings between the partial adjacent nozzle and the nozzle of interest, the arrangement of the bypass member makes it possible to extend the first liquid internal pressure propagation path length (path length of crosstalk pressure) from the individual flow path of the partial adjacent nozzle to the individual flow path of the nozzle of interest. Therefore, even if the distance between the individual flow path openings between the partial adjacent nozzle and the nozzle of interest is not increased much or at all, it is possible to set the difference between the first liquid internal pressure propagation path length from the individual flow path of the partial adjacent nozzle to the individual flow path of the nozzle of interest and the second liquid internal pressure propagation path length from the individual flow path of the other adjacent nozzle to the individual flow path of the nozzle of interest to a predetermined path length difference that allows the respective crosstalk pressures to be sufficiently offset by each other. Therefore, according to this aspect, it is possible to suppress the effects of crosstalk while suppressing a decrease in nozzle density.

[0111] [Second aspect] The second aspect is characterized in that, in the first aspect, the predetermined path length difference ΔL is set so as to satisfy the formula (1) when the resonance period of the individual flow paths is Tc and the pressure propagation speed propagating through the liquid in the common flow path is C. According to this, the phase difference between the crosstalk pressures reaching the individual flow paths of the nozzle of interest is within the range of 1 / 2±1 / 4, and a sufficient canceling effect between the crosstalk pressures is obtained.

[0112] [Third aspect] The third aspect is characterized in that, in the first or second aspect, the bypass member is not positioned between the opening of the individual flow path 4A corresponding to the other adjacent nozzle 2A and the opening of the individual flow path 4S corresponding to the focus nozzle 2S. According to this, it becomes possible to set the predetermined path length difference ΔL to be long, and it becomes easy to suppress the influence of crosstalk while suppressing a decrease in nozzle density.

[0113] [Fourth aspect] The fourth aspect is characterized in that, in the third aspect, the second liquid pressure propagation path length LA is set so as to satisfy the formula (2) when the resonance period of the individual flow path is Tc and the pressure propagation speed propagating through the liquid in the common flow path is C. This makes it possible to stably suppress the influence of crosstalk on the nozzle of interest 2S.

[0114] [Fifth aspect] A fifth aspect is characterized in that, in any of the first to fourth aspects, the multiple nozzles are arranged to form multiple nozzle rows extending parallel to the head longitudinal direction (e.g., the B row direction), and the bypass member is composed of a linear wall portion (e.g., a partition wall separating multiple through holes 121b) arranged to cross the multiple nozzle rows in a straight line, passing between the openings of the individual flow paths 4S, 4B corresponding to the target nozzle 2S and some of the adjacent nozzles 2B in each of the multiple nozzle rows. This allows the head rigidity to be increased more than in a configuration in which bypass members are individually provided between the individual flow path openings between each nozzle, and also makes it possible to suppress the effects of structural crosstalk (surface vibration) (such as fluctuations in the liquid ejection speed and ejection defects such as non-ejection).

[0115] [Sixth aspect] The sixth aspect is characterized in that, in the fifth aspect, a liquid supply port (e.g., a supply communication passage 32) that supplies liquid to the common flow path is provided at one end side of the head in a short side direction perpendicular to the head longitudinal direction, and a liquid discharge port (e.g., a discharge communication passage 34) that discharges liquid from the common flow path is provided at the other end side of the head in the short side direction. When the bypass member is formed of a straight wall portion, the straight wall portion significantly impedes the flow of liquid flowing in a direction perpendicular to the straight line direction (direction crossing the nozzle rows) of the straight wall portion, and the liquid supply capacity to each individual flow path may be insufficient. On the other hand, in the space between the straight wall portions (through hole 121b), the liquid is likely to flow along the straight line direction (direction crossing the nozzle rows) of the straight wall portion. According to this embodiment, the liquid supplied from the liquid supply port to the common flow path flows in the common flow path along the head short side direction to the liquid discharge port. The flow direction in this common flow path (head short side direction) is a direction parallel to the direction crossing the nozzle rows extending parallel to the head longitudinal direction, or a direction that forms a small angle with this direction. Therefore, the liquid flowing in the common flow path 3 from the liquid supply port to the liquid discharge port in the head short side direction can flow smoothly in the space between the straight wall portions (through hole 121b) without being hindered by the straight wall portion (bypass member). Therefore, even if a configuration is adopted in which straight wall portions (detouring members) are provided in the common flow path, the ability to supply liquid from the spaces between the straight wall portions (the through-holes 121b) to the individual flow paths can be maintained.

[0116] [Seventh aspect] The seventh aspect is characterized in that, in any one of the first to sixth aspects, a damper member (e.g., damper portion 130) is provided on the side of the common flow path facing the openings of the multiple individual flow paths. According to this, the effect of reducing the crosstalk pressure by the damper member can be exerted together with the effect of canceling the crosstalk pressure by the bypass member, so that it becomes possible to further suppress the influence of crosstalk.

[0117] [Eighth aspect] An eighth aspect is the seventh aspect, characterized in that the minimum distance between the opening and the damper member is equal to or less than the minimum center-to-center distance between the openings in two adjacent individual flow paths. In this embodiment, the minimum distance between each opening of the multiple individual flow paths and the damper member is configured to be equal to or less than the center-to-center distance between the openings of two adjacent individual flow paths. With this configuration, the crosstalk pressure from the opening of each individual flow path can reach the damper member before the majority of the crosstalk pressure from the opening of each individual flow path flows through the liquid in the common flow path to the opening of another adjacent individual flow path. This makes it possible to reduce the effect of the crosstalk pressure reaching the opening of another individual flow path from each individual flow path on the pressure fluctuation of the liquid in the other individual flow path, thereby suppressing crosstalk.

[0118] [Ninth aspect] A ninth aspect is characterized in that in any one of the first to eighth aspects, the detour member has a height of 750 μm or more. This makes it possible to suppress the effects of crosstalk while suppressing a decrease in nozzle density, even in recent liquid ejection heads that have a high nozzle density.

[0119] [Tenth aspect] A tenth aspect is a device for ejecting liquid, characterized in that it comprises the liquid ejection head according to any one of the first to ninth aspects. According to this aspect, it is possible to provide a liquid ejecting device that can suppress the influence of crosstalk while suppressing a decrease in nozzle density. [Explanation of symbols]

[0120] 1: Liquid ejection head 2: Nozzle 2A, 2B: Adjacent nozzles 2S: Nozzle of interest 3: Common flow path 4, 4A, 4B, 4S: Individual flow paths 4a: Opening 5: Piezoelectric element 5': Heater element 31: Supply liquid storage chamber 32: Supply communication path 33:Liquid supply port 34:Discharge communication path 35: Discharge liquid storage chamber 36:Liquid outlet 51:First electrode 52: Piezoelectric film 53:Second electrode 61: Damper film 62: Damper film retaining member 63: Air chamber 64: Atmospheric vent hole 100: Individual channel board 101: Drive circuit 102:Wiring section 103: Vibrating membrane 110: Nozzle plate 120: Common channel board 121: Partition board 121a: Detour bulkhead 121b: Through hole 122: Flow path securing substrate 130: Damper section 140: Frame section LA, LB: Pressure propagation path length in liquid MA, MB: Distance between opening centers ΔL: Path length difference [Prior art documents] [Patent documents]

[0121] [Patent Document 1] Patent Publication No. 2021-41569

Claims

1. a plurality of nozzles for ejecting liquid; a plurality of individual flow paths respectively communicating with the plurality of nozzles; a plurality of actuators provided for the plurality of individual flow paths; a common flow path facing each opening of the plurality of individual flow paths, the common flow path being located on a side of the plurality of individual flow paths facing the nozzle forming wall, a liquid ejection head that ejects liquid in the individual flow paths from the nozzles by driving the actuators, a bypass member is disposed within the common flow path between an opening of an individual flow path corresponding to a part of adjacent nozzles among a plurality of adjacent nozzles adjacent to a target nozzle and an opening of an individual flow path corresponding to the target nozzle, the bypass member making a first internal liquid pressure propagation path length between the openings longer than a second internal liquid pressure propagation path length between an opening of an individual flow path corresponding to another adjacent nozzle among the plurality of adjacent nozzles and the opening of an individual flow path corresponding to the target nozzle; A liquid ejection head characterized in that the difference between the first internal liquid pressure propagation path length and the second internal liquid pressure propagation path length is configured to be a predetermined path length difference.

2. 2. The liquid ejection head according to claim 1, a liquid ejection head characterized in that the predetermined path length difference ΔL is set so as to satisfy the following formula (1), where Tc is the resonance period of the individual flow paths and C is the pressure propagation speed propagating through the liquid in the common flow path: [Equation 1] Here, n is a natural number.

3. 3. The liquid ejection head according to claim 1, A liquid ejection head characterized in that the detour member is not disposed between the opening of the individual flow path corresponding to the other adjacent nozzle and the opening of the individual flow path corresponding to the target nozzle.

4. 4. The liquid ejection head according to claim 3, A liquid ejection head characterized in that the second liquid pressure propagation path length LA is set to satisfy the following equation (2), when the resonance period of the individual flow path is Tc and the pressure propagation speed propagating through the liquid in the common flow path is C: [Equation 2] Here, n is a natural number.

5. 3. The liquid ejection head according to claim 1, the plurality of nozzles are arranged to form a plurality of nozzle rows extending parallel to the longitudinal direction of the head, A liquid ejection head characterized in that the bypass member is composed of a linear wall portion that is arranged to cross the multiple nozzle rows in a straight line, passing between openings of individual flow paths that correspond to the target nozzle and some of the adjacent nozzles in each of the multiple nozzle rows.

6. 6. The liquid ejection head according to claim 5, a liquid supply port for supplying liquid to the common flow channel is provided at one end side of the head in a lateral direction perpendicular to the head longitudinal direction, A liquid ejection head, characterized in that a liquid outlet for discharging liquid from the common flow path is provided on the other end side of the head in the short direction.

7. 3. The liquid ejection head according to claim 1, A liquid ejection head according to claim 1, wherein a damper member is provided on the side of the common flow path that faces the openings of the plurality of individual flow paths.

8. 8. The liquid ejection head according to claim 7, A liquid ejection head, characterized in that the minimum distance between the opening and the damper member is equal to or less than the minimum center-to-center distance between the openings in two adjacent individual flow paths.

9. 3. The liquid ejection head according to claim 1, A liquid ejection head characterized in that the height of the detour member is 750 μm or more.

10. A liquid ejection device comprising the liquid ejection head according to claim 1 or 2.

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