Liquid dispensing head, liquid dispensing device

Abstract

To reduce a meniscus resonance period, and suppress clogging of a nozzle hole.SOLUTION: A liquid discharge head includes a plurality of nozzle holes, and a pressure chamber communicating with the nozzle holes, wherein when an intersection of a virtual central line of the nozzle holes and an extension surface of a surface where opening ends of the nozzle holes of the pressure chambers are provided is defined as a sphere center, and lines are extended from the sphere center in both a direction opposite to the liquid discharge direction from the nozzle holes, and a nozzle arrangement direction, and in both a direction opposite to the liquid discharge direction from the nozzle holes and a direction perpendicular to the nozzle arrangement direction, a length with the shortest distance to any one surface of the pressure chamber is represented by a radius rmin, a length with the longest distance to any one surface of the pressure chamber is represented by a radius rmax, a hemisphere with the radius rmin with the sphere center as a center point is represented by a virtual hemisphere 1, and a hemisphere with the radius rmax with the sphere center as a center point is represented by a virtual hemisphere 2, a volume Vmin of the virtual hemisphere 1 is 5×105 μm3 or more and 5×106 μm3 or less, and a virtual Vmax of the virtual hemisphere 2 is 5 times or more and less than 1,000 times of the Vmin.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This invention relates to a liquid dispensing head and a liquid dispensing device equipped with a liquid dispensing head. [Background technology]

[0002] In an inkjet-type image forming apparatus, an image is formed by ejecting liquid ink from a nozzle hole into a liquid ejection head.

[0003] In such liquid ejection heads, the ink dries and thickens in and around the nozzle holes in the pressure chamber of the liquid ejection head, making the nozzle holes prone to clogging. This clogging is particularly likely to occur when using quick-drying ink.

[0004] In contrast, in the ink head described in Patent Document 1 (Japanese Patent Publication No. 2018-103616), for example, a portion of the ink supplied to the individual liquid chambers is returned to the common circulating liquid chamber via a circulation channel and circulates within the head.

[0005] By using a circulating ink head like the one in Patent Document 1, nozzle clogging due to ink drying and thickening can be suppressed. However, there was a problem that the device became larger and more expensive because it required components to circulate the ink.

[0006] Furthermore, by creating a larger pressure chamber, it is possible to suppress ink drying and viscosity increase due to drying. However, this presents problems such as the need for a larger liquid ejection head and a larger meniscus resonance period, making it impossible to handle high-speed ejection. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The present invention aims to suppress clogging of the nozzle holes by keeping the meniscus resonance period low. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a liquid ejection head including a plurality of nozzle holes for ejecting a liquid and a pressure chamber communicating with the nozzle holes. Taking the intersection point of the virtual center line of the nozzle hole and the extension plane of the surface where the opening end of the nozzle hole of the pressure chamber is provided as the center of a sphere, when extending from the intersection point in both directions of the opposite direction of the liquid ejection direction from the nozzle hole and the nozzle arrangement direction, and in both directions perpendicular to the opposite direction of the liquid ejection direction from the nozzle hole and the nozzle arrangement direction respectively, the length at which the distance to any surface of the pressure chamber becomes the shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber becomes the longest is defined as the radius rmax. When the hemisphere with the center of the sphere as the center point and the radius rmin is defined as the virtual hemisphere 1, and the hemisphere with the center of the sphere as the center point and the radius rmax is defined as the virtual hemisphere 2, the volume Vmin of the virtual hemisphere 1 is 5×10 5 μm 3 or more and 5×10 6 μm 3 or less, and the volume Vmax of the virtual hemisphere 2 is 5 times or more and less than 1000 times that of Vmin Furthermore, if the radius of the nozzle hole is r1, then rmin is 3 times or more but less than 7 times r1, and rmax is 5 times or more but less than 60 times r1. This is the gist of the present invention.

Advantages of the Invention

[0009] According to the present invention, the meniscus resonance period can be significantly reduced, and clogging of the nozzle holes can be suppressed.

Brief Description of the Drawings

[0010] [Figure 1] This is an external perspective explanatory view of a liquid ejection head according to an embodiment of the present invention. [Figure 2] This is a cross-sectional explanatory view along a direction perpendicular to the nozzle arrangement direction of the liquid ejection head. [Figure 3] This is a cross-sectional view taken along line A-A of FIG. 2. [Figure 4] This is a bottom view of the liquid ejection head. [Figure 5] This is a cross-sectional view showing the virtual hemisphere 1 and the virtual hemisphere 2 of the pressure chamber of the liquid ejection head according to the present embodiment. [Figure 6]It is a diagram for explaining the height direction distance from the center of the sphere to the upper surface of the pressure chamber. [Figure 7] It is a cross-sectional view showing virtual hemispheres 1 and 2 of the pressure chamber of a liquid ejection head according to an embodiment different from FIG. 5. [Figure 8] It is a cross-sectional view showing virtual hemispheres 1 and 2 of the pressure chamber of a liquid ejection head according to an embodiment different from FIGS. 5 and 7. [Figure 9] It is a cross-sectional view showing a liquid ejection head according to an embodiment in which the opening direction of the nozzle hole and the like are different. [Figure 10] It is a schematic configuration diagram of an image forming apparatus. [Figure 11] It is a block diagram showing the functions of the image forming apparatus of FIG. 10. [Figure 12] It is a plan explanatory view of a main part of a printing apparatus according to different embodiments. [Figure 13] It is a side explanatory view of a main part of a printing apparatus according to different embodiments. [Figure 14] It is a plan explanatory view of a main part of a liquid ejection unit according to different embodiments. [Figure 15] It is a front explanatory view of a main part of a liquid ejection unit according to different embodiments.

Embodiments for Carrying Out the Invention

[0011] Embodiments of the present invention will now be described with reference to the accompanying drawings. The first embodiment of the present invention will be described with reference to Figures 1 to 3. Figure 1 is an external perspective view of the liquid discharge head according to the first embodiment, Figure 2 is a cross-sectional view of the pressure chamber of the liquid discharge head according to the same embodiment along the longitudinal direction X, and Figure 3 is a cross-sectional view of the same embodiment along the nozzle arrangement direction Y. Direction Y is the arrangement direction of the plurality of nozzle holes 4, and will hereinafter be simply referred to as the nozzle arrangement direction. Direction Z is the height direction of the pressure chamber 6, and is the opening direction of the nozzle holes or the liquid discharge direction and the opposite direction. Direction Z is also the up and down direction. This up and down direction is the direction of gravity and the opposite direction when the liquid discharge head is in use, and the direction when the liquid discharge head is in use is the direction when the liquid discharge head is mounted on a device such as a liquid discharge device. The directions X, Y, and Z shown in Figure 1 are mutually orthogonal directions. Direction X is one of these mutually orthogonal directions that is different from the nozzle arrangement direction and the up and down direction. However, the longitudinal direction X of the pressure chamber 6, the nozzle arrangement direction Y, and the liquid discharge direction Z do not need to be strictly perpendicular; some degree of error is acceptable.

[0012] The liquid discharge head 100 of this embodiment comprises a nozzle plate 1, individual flow path members 2, a diaphragm member 3 as a wall member, a piezoelectric actuator 11, a common liquid chamber member 20, and a head cover 29. The nozzle plate 1, the flow path plate 2, and the diaphragm member 3 are laminated and joined together. The piezoelectric actuator 11 displaces the deformable portion 30 of the diaphragm member 3. The head cover 29 also serves as a frame member of the liquid discharge head 100.

[0013] A piezoelectric element 12 and the like are arranged inside the common liquid chamber member 20. As shown in Figure 1, the head cover 29 is attached to the top of the common liquid chamber member 20 and covers the piezoelectric element 12 and the like.

[0014] The supply port 28 supplies ink as a liquid to the common supply channel within the common liquid chamber member 20.

[0015] As shown in Figures 2 and 3, the nozzle plate 1 has a plurality of nozzle holes 4 for ejecting ink.

[0016] The fluid resistance section 7 and the intermediate supply channel 8 are defined by the flow path plate 2 and the vibrating plate member 3. In addition, the nozzle plate 1, the flow path plate 2, and the vibrating plate member 3 define a plurality of pressure chambers 6. The pressure chambers 6 communicate with the nozzle holes 4. The fluid resistance section 7 is an individual flow path leading to each pressure chamber 6. The intermediate supply channel 8 is a liquid introduction section leading to one or more (one in this embodiment) fluid resistance sections 7.

[0017] The diaphragm member 3 is constructed by laminating multiple plate materials, and in this embodiment, it is constructed by laminating two metal plates. The diaphragm member 3 also has a deformable portion 30 that faces the piezoelectric actuator 11.

[0018] The deformable portion 30 constitutes a part of the wall surface of the pressure chamber 6 and is elastically deformable by the piezoelectric actuator 11. The piezoelectric actuator 11 includes an electromechanical conversion element as a driving means (actuator means, pressure generating means). In this embodiment, the deformable portion 30 has fewer layers of plate material and a shorter length in the thickness direction than the other parts of the diaphragm member 3. Specifically, the deformable portion 30 is made of a single metal plate. Alternatively, the diaphragm member 3 may be partially deformable by making cuts in it, and the portion of this deformable part that constitutes the wall surface of the pressure chamber 6 may be designated as the deformable portion 30.

[0019] This piezoelectric actuator 11 has a piezoelectric member bonded to a base member 13, and grooves are machined into the piezoelectric member by half-cut dicing to form a required number of columnar piezoelectric elements 12 at predetermined intervals in a comb-like shape in the nozzle arrangement direction.

[0020] A support member 27 is provided at the upper part of the deformable portion 30 to support the deformable portion 30. The piezoelectric element 12 is joined to the support member 27.

[0021] This piezoelectric element 12 is constructed by alternately stacking piezoelectric layers and internal electrodes. In the piezoelectric element 12, each internal electrode is drawn out to the end face and connected to an external electrode (end face electrode), and a flexible wiring member 15 is connected to the external electrode.

[0022] The common liquid chamber member 20 forms a common liquid chamber 10 that leads to a plurality of pressure chambers 6. The common liquid chamber 10 communicates with the intermediate supply channel 8 through an opening 9 provided in the diaphragm member 3, and through the intermediate supply channel 8 it leads to the fluid resistance section 7.

[0023] The ink in the common liquid chamber 10 is supplied to the pressure chamber 6 via the intermediate supply channel 8 and the fluid resistance section 7. The ink in the pressure chamber 6 is ejected from the nozzle hole 4 to the outside of the liquid discharge head 100. In the pressure chamber 6, the direction of ink supply is from the fluid resistance section 7 side in the X direction to the nozzle hole 4 side.

[0024] In this liquid dispensing head 100, for example, the piezoelectric element 12 contracts by lowering the voltage applied to it from a reference potential (intermediate potential). This contraction of the piezoelectric element 12 causes the deformation portion 30 to deform toward the piezoelectric element 12, expanding the volume of the pressure chamber 6, and allowing ink to flow into the pressure chamber 6.

[0025] Subsequently, the voltage applied to the piezoelectric element 12 is increased, causing the piezoelectric element 12 to stretch in the stacking direction, thereby deforming the deformed portion 30 toward the nozzle hole 4 and contracting the volume of the pressure chamber 6. As a result, the ink in the pressure chamber 6 is pressurized, and the ink is ejected from the nozzle hole 4.

[0026] The liquid ejection head 100 of this embodiment is a non-circulating type liquid ejection head. In a circulating type liquid ejection head, the ink that flows into the pressure chamber 6 is circulated through a circulation channel or the like and flows back into the pressure chamber 6, but in the non-circulating type liquid ejection head 100 of this embodiment, such ink circulation is not performed. The pressure chamber 6 of this liquid ejection head 100 is provided with two openings: a nozzle hole 4 and a fluid resistance section 7.

[0027] The liquid discharge head 100 may have a configuration with one row of nozzles arranged with nozzle holes 4, as shown in Figure 4(a), or it may have multiple rows, as shown in Figure 4(b). In addition, the nozzle rows may be arranged in parallel, as shown in Figure 4(b), or in a staggered pattern. Furthermore, as shown in Figure 4(c), multiple liquid discharge heads 100 may be arranged to form a head unit 103. Furthermore, as shown in Figure 4(d), a pair of adjacent liquid discharge heads 100 may be arranged in a staggered pattern within the head unit 103. However, the configuration is not limited to these, and the optimal arrangement of nozzle holes 4 and liquid discharge heads 100 can be selected as appropriate.

[0028] In this embodiment of a non-circulating liquid ejection head, there was a problem in that ink clogging occurred in the nozzle holes due to the thickening or drying of the ink in and around the nozzle holes. This problem was particularly noticeable when water-based pigment inks or quick-drying inks were used as the liquid in the liquid ejection head.

[0029] The thickening of the ink due to drying, as described above, spreads from the ink near the nozzle, so the larger the volume of the pressure chamber 6 centered on the nozzle hole, the smaller its effect. However, if the pressure chamber 6 is made too large, the meniscus resonance period becomes large, which makes it impossible to handle high-speed ejection. Therefore, in this embodiment, the size of the pressure chamber 6 is defined as shown below.

[0030] Figure 5(a) shows the spherical center D, which is the intersection point of the virtual center line B of the nozzle hole 4 and the virtual extension surface C of the surface 6a of the pressure chamber 6 where the opening end of the nozzle hole 4 is located. With this spherical center D as the center point, virtual hemispheres 1 and 2 formed on the pressure chamber 6 side are shown by dashed lines.

[0031] As shown by the arrows in Figure 5(a), when extending in five directions from the sphere center D in the height direction of the pressure chamber 6 (or the direction opposite to the liquid discharge direction from the nozzle hole 4), as shown by the arrows in Figure 5(b), both directions in the Y direction (nozzle arrangement direction) and both directions in the X direction (longitudinal direction of the pressure chamber, or directions perpendicular to both the direction opposite to the liquid discharge direction from the nozzle hole 4 and the nozzle arrangement direction), the length at which the distance to any surface of the pressure chamber 6 is shortest is defined as radius rmin, and the length at which the distance to any surface of the pressure chamber 6 is longest is defined as radius rmax. In this case, virtual hemisphere 1 is a hemisphere formed on the pressure chamber side with radius rmin, with the sphere center D as the center point. Virtual hemisphere 2 is a hemisphere formed on the pressure chamber side with radius rmax, with the sphere center D as the center point. When determining radius rmin and radius rmax, "any surface of the pressure chamber 6" excludes the surface 6a where the opening end of the nozzle hole 4 is provided. The virtual center line B of the nozzle hole 4 is a center line that extends in a direction parallel to the extension direction of the nozzle hole 4.

[0032] Here, we will explain in more detail the distance from the sphere center D to the upper surface of the pressure chamber 6 when extended in the height direction of the pressure chamber 6. That is, as in the liquid discharge head of this embodiment shown in Figure 6, when the deformable portion 30 of the diaphragm member 3 is provided at a position extended in the height direction of the pressure chamber 6 from the sphere center D, the position of the upper surface of the pressure chamber 6 changes depending on the state of the deformable portion 30. However, in this case, the surface extended from the non-deformable portion of the pressure chamber 6 is taken as a virtual extension surface J, and the distance from the sphere center D to this virtual extension surface J is taken as the distance when extended in the height direction of the pressure chamber 6 from the sphere center D, and the radius rmax or rmin is determined accordingly. Alternatively, when the deformable portion 30 is in a non-driven state by the piezoelectric element 12 as a drive unit, the distance from the sphere center D to the deformable portion 30 may be taken as the distance when extended in the height direction of the pressure chamber 6 from the sphere center D.

[0033] In this embodiment, the volume Vmin of the virtual hemisphere 1 is 5 × 10 5 μm 3 The above 5 x 10 6 μm 3Hereinafter, a pressure chamber 6 is provided such that the volume Vmax of the virtual hemisphere 2 is not less than 5 times and less than 1000 times the volume Vmin of the virtual hemisphere 1. By setting the volume Vmin of the virtual hemisphere 1 to be 5×10 5 μm 3 or more, and setting the volume Vmax of the virtual hemisphere 2 to be not less than 5 times the volume Vmin of the virtual hemisphere 1, a space having a certain spread from the spherical center D which is the virtual center of the nozzle hole 4 is formed in the pressure chamber 6. Thus, drying of the ink in the pressure chamber 6 and thickening due to drying can be suppressed as described above, and clogging of the nozzle hole 4 can be suppressed. Also, the number of air discharges for suppressing drying of the ink can be reduced. Also, by setting the volume Vmin of the virtual hemisphere 1 to 5×10 6 μm 3 or less, and setting the volume Vmax of the virtual hemisphere 2 to be less than 1000 times the volume Vmin of the virtual hemisphere 1, the size of the pressure chamber 6 in the vicinity of the nozzle hole 4 can be suppressed to a certain level or less. Thereby, the meniscus resonance period can be suppressed to a certain level or less.

[0034] As described above, in the present embodiment, by providing the size of the pressure chamber 6 in the vicinity of the nozzle hole 4 with an appropriate size, while suppressing drying of the ink in the pressure chamber and thickening due to drying, the meniscus resonance period can be suppressed to a certain level or less, and the liquid ejection head can cope with high-speed ejection. Also, compared with a circulation type liquid ejection head, the above effects can be obtained with a cheap and simple configuration, and miniaturization and cost reduction of the liquid ejection head can be realized.

[0035] In the embodiment shown in Figure 5, the radius rmin is the length in the direction Z from the sphere center D to the pressure chamber 6 near the nozzle hole 4, and the radius rmax is the length in the longitudinal direction X from the sphere center D to the vicinity of the nozzle hole 4. In other words, the length in the direction Z from the sphere center D to the wall surface of the pressure chamber 6 is smallest, and the length in the direction X from the sphere center D to the wall surface of the pressure chamber 6 is large. However, the present invention is not limited to this. For example, in the pressure chamber 6 shown in Figures 7(a) and 7(b), the length in the direction Y from the sphere center D is smallest, and the length in the direction X is largeest. Even in this case, by setting the volume Vmin of virtual hemisphere 1 and the volume Vmax of virtual hemisphere 2 as described above, it is possible to suppress the drying and thickening of the ink in the pressure chamber 6, and to keep the meniscus resonance period below a certain level.

[0036] Furthermore, in the embodiments shown in Figures 8(a) and 8(b), the nozzle holes 4 are positioned towards one side of direction X, with radius rmin being the length of one side of direction X and radius rmax being the length of the other side of direction X. Even with this arrangement, by setting the sizes of virtual hemispheres 1 and 2 as described above, it is possible to suppress the drying and thickening of the ink in the pressure chamber 6 and to keep the meniscus resonance period below a certain level.

[0037] Furthermore, as shown in Figure 5(a), if the radius of the nozzle hole 4 is radius r1, it is preferable to set the radius rmin of the virtual hemisphere 1 to be between 3 and 7 times the radius r1, and the radius rmax of the virtual hemisphere 2 to be between 5 and 60 times the radius r1. This allows the size of the pressure chamber 6 near the nozzle hole 4 to be set to an appropriate size relative to the size of the nozzle hole 4 from which the ink is ejected, thereby suppressing drying and thickening of the ink in and near the nozzle hole 4 while keeping the meniscus resonance period small. The radius r1 of the nozzle hole 4 referred to here is the radius at the position where the nozzle hole 4 is narrowest (its cross-section is smallest) at each position in the extending direction of the nozzle hole 4. The radius r1 is measured using transmitted light with a microscope.

[0038] Furthermore, the area A of the surface 6a where the opening end of the nozzle hole 4 of the pressure chamber 6 is provided is 5 × 10 4 μm 2 The above 2 x 105 μm 2 The following is preferable: By setting the size of the pressure chamber 6 near the nozzle hole 4 to an appropriate size, it is possible to suppress drying and thickening of the ink in and near the nozzle hole 4 while keeping the meniscus resonance period small. In particular, the number of times dry ink is ejected from the nozzle hole 4 can be reduced.

[0039] The volume V1 of the pressure chamber 6 is preferably 10 nl or less. This allows the meniscus resonance period to be kept small. The range E shown in Figures 5(a) and 5(b) is the range of the pressure chamber 6, and the volume V1 of the pressure chamber 6 is the volume of the space up to the boundary with the fluid resistance section 7, within the space formed by the nozzle plate 1, flow path plate 2, diaphragm member 3, etc. However, the hole portion of the nozzle hole 4 is not included, and the volume of the pressure chamber 6 is calculated using the extended surface C of surface 6a as one surface. In other words, the volume of the pressure chamber 6 is the volume of range E when the fluid resistance section 7 and nozzle hole 4 are filled. In this embodiment, the fluid resistance section 7 is an ink passage that communicates with the pressure chamber 6 and has a smaller cross-sectional area perpendicular to its longitudinal direction than the pressure chamber 6 and the intermediate supply passage 8 on the ink supply side.

[0040] Furthermore, the thickness of the nozzle plate 1 (thickness h in Figure 2) is preferably 25 μm or more and 45 μm or less. This promotes the supply of ink vehicle to the nozzle hole 4 and suppresses the drying of ink in and around the nozzle hole 4. This thickness also reduces the meniscus resonance period.

[0041] Furthermore, the area of ​​nozzle hole 4 is 300 μm². 2 More than 360μm 2 The following is preferable: By making the area of ​​the nozzle hole 4 small, evaporation of moisture from the nozzle hole 4 becomes less likely. Therefore, drying of the ink in and around the nozzle hole 4 can be suppressed. In addition, the meniscus resonance period can be reduced. The area of ​​the nozzle hole 4 is the area of ​​the cross-section perpendicular to the extending direction of the nozzle hole 4, and is the area where the cross-section of the nozzle hole 4 is smallest at each position in the extending direction of the nozzle hole 4. This area is also measured using transmitted light with a microscope.

[0042] Furthermore, the experimental results of measuring the number of empty droplets and the meniscus resonance period Tc for the liquid discharge heads of four examples and four comparative examples in which each of the above parameters was varied are explained using Table 1 below. The number of empty droplets was determined by continuously discharging an image with a width of 27 inches and an empty discharge portion at the end onto a blank sheet of paper using an image forming apparatus, and measuring the number of empty droplets required to prevent nozzle clogging after continuous discharging for 3.5 hours. ◎ indicates that 1 to 2 empty droplets are required, ○ indicates 3 to 4 droplets, and × indicates 5 or more droplets. The meniscus resonance period Tc was less than 3.2 μs for ◎ and 3.2 μs or more for ×. [Table 1]

[0043] As shown in Table 1, in Examples 1 to 4, the volume Vmin of virtual hemisphere 1 is particularly high, as mentioned above (5 × 10⁻⁶). 5 μm 3 The above 5 x 10 6 μm 3 The values ​​are set within the following range, with Vmax / Vmin set within the range of 5 to 1000. Conversely, in Comparative Examples 1 to 4, these values ​​are set outside the above range. As a result, in Examples 1 to 4, good results were obtained for both the number of empty ejections and the meniscus resonance period Tc, while in Comparative Examples 1 to 4, either the number of empty ejections or the meniscus resonance period Tc was poor. More specifically, in Comparative Example 1, where the volume Vmin of virtual hemisphere 1 was small, the number of empty ejections increased. Also, in Comparative Examples 2 and 3, where the values ​​of Vmin and Vmax / Vmin were large and the pressure chamber 6 was large, the meniscus resonance period increased. Thus, by setting the volume Vmin and Vmax / Vmin within an appropriate range as in Examples 1 to 4, it is possible to suppress ink drying and viscosity increase due to drying in the pressure chamber 6, and to reduce the meniscus resonance period.

[0044] In the above embodiment, we have illustrated the case where the above configuration of this embodiment is provided to a non-circulating liquid discharge head, but we are not limited to this, and the above configuration of this embodiment may also be provided to a circulating liquid discharge head.

[0045] In the above embodiment, the case where the longitudinal direction of the pressure chamber 6 is perpendicular to the vertical direction and the nozzle arrangement direction was shown, but the present invention is not limited to this. For example, as shown in Figure 9, in this embodiment, the longitudinal direction Z of the pressure chamber 6 is the same as the vertical direction and the ink ejection direction from the nozzle holes 4. Also, the longitudinal direction Z is perpendicular to the arrangement direction Y of the nozzle holes 4.

[0046] In this embodiment as well, similar to the previously described embodiment, when the lines are extended in a total of five directions from the sphere center D in the direction opposite to the liquid discharge direction from the nozzle hole 4 (upward in Figure 9), both directions in the Y direction which is the nozzle arrangement direction from the sphere center D, and both directions in the X direction which is perpendicular to these directions from the sphere center D, the length at which the distance to any surface of the pressure chamber 6 is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber 6 is longest is defined as the radius rmax. Virtual hemispheres 1 and 2 are set using these radii rmin and rmax, and the volume Vmin of virtual hemisphere 1 is 5 × 10⁻⁶. 5 μm 3 The above 5 x 10 6 μm 3 Below, the volume Vmax of virtual hemisphere 2 is set to be between 5 and 1000 times the volume Vmin of virtual hemisphere 1. This suppresses ink drying and viscosity increase due to drying in the pressure chamber, while keeping the meniscus resonance period below a certain level, allowing the liquid ejection head to handle high-speed ejection.

[0047] In the liquid ejection head 100 of the above embodiment, it is preferable to use a water-based pigment ink. Furthermore, in the liquid ejection head 100 of the above embodiment, it is preferable to use a quick-drying ink. These inks tend to thicken and dry easily, and are prone to clogging of the nozzle holes. However, the configuration of the pressure chamber in this embodiment can effectively suppress clogging of the nozzle holes. The water-based pigment ink referred to here is an ink that contains at least water, an organic solvent, and a pigment.

[0048] There are no particular restrictions on the water content in the ink, and it can be appropriately selected depending on the purpose. However, from the viewpoint of ink drying properties and ejection reliability, 10% by mass or more and 90% by mass or less is preferred, and 20% by mass to 60% by mass is more preferred.

[0049] The organic solvents included in the ink are not particularly limited, and water-soluble organic solvents can be used. Examples include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.

[0050] Specific examples of water-soluble organic solvents include, for example, ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, and 1,5-pentanediol. Polyhydric alcohols such as pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, petriol, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether. Examples include polyhydric alcohol alkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-butyrolactone; amides such as formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide; amines such as monoethanolamine, diethanolamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; propylene carbonate; and ethylene carbonate.

[0051] It is preferable to use an organic solvent with a boiling point of 250°C or lower, as it not only functions as a wetting agent but also provides good drying properties.

[0052] There are no particular restrictions on the content of organic solvents in the ink, and it can be appropriately selected depending on the purpose. However, from the viewpoint of ink drying properties and ejection reliability, it is preferable that the content be between 10% by mass and 60% by mass, and more preferably between 20% by mass and 60% by mass.

[0053] Ink pigments can be inorganic or organic. These may be used individually or in combination of two or more. Mixed crystals may also be used. Examples of pigments include black, yellow, magenta, cyan, white, green, orange, and metallic pigments such as gold and silver.

[0054] As inorganic pigments, titanium dioxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chromium yellow can be used, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method.

[0055] In addition, organic pigments such as azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye type chelates, acid dye type chelates, etc.), nitro pigments, nitroso pigments, and aniline black can be used. Of these pigments, those with good affinity for the solvent are preferred. Other uses such as resin hollow particles and inorganic hollow particles are also possible.

[0056] Specific examples of pigments include carbon blacks (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, or metals such as copper, iron (CI Pigment Black 11), and titanium dioxide, as well as organic pigments such as aniline black (CI Pigment Black 1).

[0057] Furthermore, for color applications, we have CI Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104, 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, and CI Pigment O Range 5, 13, 16, 17, 36, 43, 51, CI Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B(Ca)), 48:3, 48:4, 49:1, 52:2, 53:1, 57:1 (Brilliant Carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88 , 101 (Bengara), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, CI Pigment Violet 1 (Rhodamine Lake), 3, 5:1, 16, 19, 23, 38; CI Pigment Blue 1, 2, 15 (Phthalocyanine Blue), 15:1, 15:2, 15:3, 15:4 (Phthalocyanine Blue), 16, 17:1, 56, 60, 63; CI Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc. are available.

[0058] The pigment content in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, from the viewpoint of improving image density, good fixation and ejection stability.

[0059] Figure 10 illustrates an example of the configuration of an image forming apparatus 200, which is a liquid dispensing device equipped with the liquid dispensing head of the above embodiment. The image forming apparatus 200 includes a control unit 102, a head unit 103, an image inspection unit 104, an unwinder 105, a drying unit 106, and a rewinder 107.

[0060] The image forming apparatus 200 forms an image by ejecting ink droplets onto the paper P1. Here, the paper P1 is an example of a recording medium, for example, a roll of paper in this embodiment. The ink is an example of a liquid droplet. In Figure 10, direction J is perpendicular to the width direction of the paper P1 and indicates the direction from the supply side to the discharge side of the paper P1 within the image forming apparatus 200. The width direction is perpendicular to the plane of the paper in Figure 10.

[0061] The control unit 102 is a control device that controls the image forming apparatus 200. The unwinder 105 and rewinder 107 are synchronized by a control signal T1 output by the control unit 102 and transport the paper P1 at a predetermined speed. The unwinder 105, rewinder 107, and the multiple transport rollers 108 constitute the transport mechanism 150.

[0062] The head unit 103 includes line heads 131, 132, 133, and 134. Each of the line heads 131 to 134 is an example of a droplet dispensing head. Each of the line heads 131 to 134 is equipped with a liquid dispensing head according to the embodiment described above.

[0063] As the paper P transported by the unwinder 105 and rewinder 107 passes directly beneath the head unit 103, each of the line heads 131, 132, 133, and 34 ejects ink based on image information, applying ink to the paper P1 to form an image. For example, line head 131 can eject black ink, line head 132 can eject cyan ink, line head 133 can eject magenta ink, and line head 134 can eject yellow ink.

[0064] The drying unit 106 is a heating drum that heats the ink applied to the paper P1 by the head unit 103 while transporting the paper P1. The drying unit 106 evaporates the water and other liquid components in the ink by heating, fixing the ink onto the paper P1 and fixing the image onto the paper P1.

[0065] The image inspection unit 104 reads the image fixed on the paper P1 and performs image inspection. The control unit 102 receives the received signal T2, which includes image inspection data from the image inspection unit 104, and can perform various correction processing using the image inspection data.

[0066] The image forming apparatus 200 can have other functional parts added as appropriate, in addition to the configuration shown in Figure 10. For example, a pre-processing unit can be added between the unwinder 105 and the head unit 103 to perform pre-processing before image formation, or a post-processing unit can be added between the drying unit 106 and the rewinder 107 to perform post-processing before image formation. The pre-processing unit includes a processing liquid application process that applies a processing liquid to the paper P1 to suppress bleeding by reacting with the ink, but there are no particular restrictions on the content of the pre-processing. The post-processing unit also includes a cooling mechanism for cooling the paper, but there are no particular restrictions on the content of the post-processing.

[0067] Referring to Figure 11, the functional configuration of the control unit 102 of the image forming apparatus 200 will be explained. Figure 11 is a block diagram illustrating an example of the functional configuration of the control unit 102.

[0068] As shown in Figure 11, the control unit 102 includes a temperature control unit 501, a transport speed control unit 502, a head ejection control unit 503, and an image inspection device control unit 504. The control unit 102 can realize these functions by having the CPU load a program stored in ROM or the like into RAM and execute it.

[0069] The temperature control unit 501 controls the temperature of the drying unit 106. The transport speed control unit 502 is an example of a moving unit that moves the head unit 103 and the paper relative to each other in the transport direction. The transport speed control unit 502 controls the transport speed of the transport mechanism 150, which consists of an unwinder 105, a rewinder 107, and transport rollers 108, etc. The head ejection control unit 503 outputs a drive voltage waveform to eject ink from each of the line heads 131 to 134. The image inspection device control unit 504 controls the image inspection unit 104.

[0070] When performing image formation, the temperature control unit 501 starts temperature control so that the drying unit 106 reaches the desired temperature. The transport speed control unit 502 starts transporting the paper P1 to coincide with the timing when the drying unit 106 reaches the desired temperature and is ready for image formation. When the transport speed of the paper P1 by the transport speed control unit 502 becomes approximately constant and the drying unit 106 is within the desired temperature range, the head ejection control unit 503 outputs a drive voltage waveform to each of the line heads 131 to 134 of the head unit 103 to eject ink. The image forming apparatus 200 can form an image on the paper P1 with the ink ejected from each of the line heads 131 to 34.

[0071] The ink ejection timing for each line head 131 to 134 is pre-optimized based on the landing position read by the image inspection unit 104 during the image formation process. The ink ejection timing can also be adjusted by performing an image inspection during image formation.

[0072] Next, another example of a printing apparatus as a liquid dispensing device according to the present invention will be described with reference to Figures 12 and 13. Figure 12 is a plan view illustrating the main parts of the apparatus, and Figure 13 is a side view illustrating the main parts of the apparatus.

[0073] This printing apparatus 500 is a serial type apparatus, and the carriage 403 reciprocates in the main scanning direction K by the 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 stretched across the left and right side plates 491A and 491B and holds the carriage 403 in a movable position. The carriage 403 is then reciprocated in the main scanning direction K by the main scanning motor 405 via the timing belt 408 stretched between the drive pulley 406 and the driven pulley 407.

[0074] The carriage 403 is equipped with a liquid discharge unit 300 that integrates a liquid discharge head 100 and a head tank 441 according to the present invention. The liquid discharge head 100 of the liquid discharge unit 300 discharges liquids of various colors, such as yellow (Y), cyan (C), magenta (M), and black (K). The liquid discharge head 100 has a nozzle row consisting of multiple nozzles arranged in a sub-scanning direction L perpendicular to the main scanning direction K, and is mounted with the discharge direction facing downward. The main scanning direction K is the direction X in the liquid discharge head described above, and the sub-scanning direction L is the direction Y in the liquid discharge head described above.

[0075] The printing apparatus 500 includes a transport mechanism 495 for transporting paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

[0076] The conveyor belt 412 attracts the paper 410 and transports it to a position opposite the liquid discharge head 100. This conveyor belt 412 is an endless belt and is stretched between the conveyor roller 413 and the tension roller 414. Attraction can be performed by electrostatic attraction or air suction.

[0077] Then, the conveyor belt 412 moves in a circular motion in the sub-scanning direction L as the conveyor rollers 413 are rotated by the sub-scanning motor 416 via the timing belt 417 and timing pulley 418.

[0078] Furthermore, a maintenance and recovery mechanism 420 for maintaining and recovering the liquid discharge head 100 is positioned on one side of the carriage 403 in the main scanning direction K, next to the conveyor belt 412.

[0079] The maintenance and recovery mechanism 420 consists of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 100, and a wiper member 422 that wipes the nozzle surface.

[0080] The main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the transport mechanism 495 are mounted on a housing that includes side plates 491A, 491B, and a back plate 491C.

[0081] In the printing apparatus 500 configured in this way, the paper 410 is fed onto the transport belt 412 and picked up, and the paper 410 is transported in the sub-scanning direction L by the circumferential movement of the transport belt 412.

[0082] Therefore, by moving the carriage 403 in the main scanning direction K and driving the liquid ejection head 100 in accordance with the image signal, liquid is ejected onto the stationary paper 410 to form an image.

[0083] Next, another example of the liquid dispensing unit according to the present invention will be described with reference to Figure 14. Figure 14 is a plan view illustrating the main parts of the unit.

[0084] The liquid discharge unit 300 comprises 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 discharge head 100, which are components of the liquid discharge device.

[0085] Furthermore, a liquid dispensing unit can also be constructed by attaching the aforementioned maintenance and recovery mechanism 420 to, for example, the side plate 491B of the liquid dispensing unit 300.

[0086] Next, yet another example of the liquid dispensing unit according to the present invention will be described with reference to Figure 15. Figure 15 is a front view of the unit.

[0087] This liquid discharge unit 300 consists of a liquid discharge head 100 to which a flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

[0088] The flow path component 444 is located inside the cover 442. A head tank 441 (see Figure 13) can be included instead of the flow path component 444. Furthermore, a connector 443 for electrical connection to the liquid discharge head 100 is provided on the upper part of the flow path component 444.

[0089] The aforementioned liquid dispensing units and liquid dispensing devices can also be equipped with the aforementioned liquid dispensing head 100. This reduces the meniscus resonance period, suppresses ink viscosity increase and drying in and near the nozzle hole, and prevents clogging of the nozzle hole.

[0090] In this application, the discharged liquid is not particularly limited as long as it has a viscosity and surface tension that can be discharged from the head, but it is preferable that its viscosity becomes 30 mPa·s or less at room temperature and atmospheric pressure, or when heated or cooled. More specifically, it is a solution, suspension, emulsion, etc. containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a polymerizable compound, a resin, a functional material such as a surfactant, a biocompatible material such as DNA, amino acids or proteins, calcium, or an edible material such as a natural pigment. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic elements and light-emitting elements or electronic circuit resist patterns, and material liquids for 3D molding.

[0091] The energy source for discharging liquid includes piezoelectric actuators (multilayer piezoelectric elements and thin-film piezoelectric elements), thermal actuators using electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a diaphragm and a counter electrode.

[0092] A "liquid dispensing unit" is a liquid dispensing head with integrated functional components and mechanisms, and includes an assembly of parts related to liquid dispensing. For example, a "liquid dispensing unit" may include a combination of a liquid dispensing head with at least one of the following components: a head tank, carriage, supply mechanism, maintenance and recovery mechanism, and main scanning and moving mechanism.

[0093] Here, integration includes, for example, cases where the liquid dispensing head and functional components or mechanisms are fixed to each other by fastening, bonding, engaging, etc., or where one is held movably relative to the other. Furthermore, the liquid dispensing head and functional components or mechanisms may be configured to be detachable from each other.

[0094] For example, some liquid dispensing units have a liquid dispensing head and head tank integrated into one unit. Others have a liquid dispensing head and head tank integrated into one unit, connected to each other by tubes or similar means. In these liquid dispensing units, a unit including a filter can also be added between the head tank and the liquid dispensing head.

[0095] Additionally, some liquid dispensing units have an integrated liquid dispensing head and carriage.

[0096] Furthermore, some liquid dispensing units integrate the liquid dispensing head and the scanning mechanism by movably holding the liquid dispensing head in a guide member that constitutes part of the scanning mechanism. Others integrate the liquid dispensing head, carriage, and main scanning mechanism.

[0097] Furthermore, some liquid dispensing units integrate the liquid dispensing head, carriage, and maintenance / recovery mechanism by fixing a cap component, which is part of the maintenance / recovery mechanism, to a carriage to which the liquid dispensing head is attached.

[0098] Furthermore, some liquid discharge units have a head tank or a liquid discharge head to which flow path components are attached, to which a tube is connected, integrating the liquid discharge head and the supply mechanism.

[0099] The main scanning movement mechanism shall include the guide member alone. The supply mechanism shall also include the tube alone and the loading section alone.

[0100] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

[0101] The term "liquid" includes not only ink but also paint.

[0102] In this application, "liquid dispensing device" refers to a device that includes a liquid dispensing head or a liquid dispensing unit and drives the liquid dispensing head to dispense liquid. A liquid dispensing device includes not only devices that can dispense liquid onto objects to which liquid can adhere, but also devices that dispense liquid into air or into liquid.

[0103] This "liquid dispensing device" may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc.

[0104] For example, "liquid ejection devices" include image forming devices that eject ink to form images on paper, and three-dimensional molding devices that eject molding liquid into a powder layer formed in layers to create three-dimensional objects.

[0105] Furthermore, the term "liquid dispensing device" is not limited to those that visualize meaningful images such as letters or figures through the dispensed liquid. For example, it also includes devices that form patterns that do not have meaning in themselves, or devices that create three-dimensional images.

[0106] The term "materials to which liquid can adhere" above refers to materials to which liquid can adhere, at least temporarily, including materials that adhere and solidify, or materials that adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0107] The materials referred to as "materials to which liquid can adhere" above include paper, thread, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere to them, even temporarily.

[0108] Furthermore, while "liquid dispensing device" includes devices in which the liquid dispensing head and the object to which the liquid can adhere move relative to each other, it is not limited to these. Specific examples include serial-type devices in which the liquid dispensing head moves, and line-type devices in which the liquid dispensing head does not move.

[0109] Other types of "liquid dispensing devices" include processing liquid coating devices that dispense processing liquid onto the surface of paper for purposes such as modifying the paper surface, and injection granulation devices that granulate fine particles of raw materials by spraying a compositional liquid, in which raw materials are dispersed in a solution, through a nozzle.

[0110] In this application, the terms image formation, recording, printing, copying, printing, and shaping are all considered synonymous.

[0111] Examples of the present invention are as follows: <1> Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5 × 10 5 μm 3 The above 5 x 10 6 μm 3 The following is a liquid dispensing head characterized in that the volume Vmax of the virtual hemisphere 2 is 5 times or more but less than 1000 times Vmin. <2> If the radius of the nozzle hole is r1, rmin is between 3 and 7 times r1, and rmax is between 5 and 60 times r1. <1> This is the liquid dispensing head described. <3> The area A of the surface of the pressure chamber where the opening end of the nozzle hole is provided is 5 × 10 4 μm 2 The above 2 x 10 5 μm 2 The following is <1> or <2> This is the liquid dispensing head described. <4> The volume V1 of the pressure chamber is 10 nl or less. <1> from <3> It is one of the liquid dispensing heads described above. <5> Having a nozzle plate that forms the nozzle hole, The thickness of the nozzle plate is 25 μm or more and 45 μm or less. <1> from <4> It is one of the liquid dispensing heads described above. <6> The area of ​​the cross-section perpendicular to the extending direction of the nozzle hole is 300 μm². 2 More than 360μm 2The following is <1> from <5> It is one of the liquid dispensing heads described above. <7> This is a non-circulating liquid dispensing head that does not circulate the liquid. <1> from <6> It is one of the liquid dispensing heads described above. <8> The liquid is an ink containing water, an organic solvent, and a pigment. <1> from <7> It is one of the liquid dispensing heads described above. <9> <1> from <8> This is a liquid dispensing device equipped with one of the liquid dispensing heads described above. [Explanation of symbols]

[0112] 100 liquid dispensing heads 1 Nozzle plate 3. Diaphragm component 4 nozzle holes 6. Pressure Chamber 6a The surface on which the opening end of the nozzle hole of the pressure chamber is provided. D Sphere center S1 Virtual Hemisphere 1 S2 virtual hemisphere 2 X Longitudinal direction of the pressure chamber (direction perpendicular to the nozzle arrangement direction and the direction of liquid discharge from the nozzle holes) Y nozzle arrangement direction Z (up and down direction - direction of liquid discharge from the nozzle hole and the opposite direction) [Prior art documents] [Patent Documents]

[0113] [Patent Document 1] Japanese Patent Publication No. 2018-103616

Claims

1. Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5 × 10 ５ μm ３ The above 5 x 10 ６ μm ３ In the following, the volume Vmax of the virtual hemisphere 2 is 5 times or more but less than 1000 times Vmin, If the radius of the nozzle hole is r1, A liquid dispensing head characterized in that rmin is 3 times or more but less than 7 times r1, and rmax is 5 times or more but less than 60 times r1.

2. Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5 × 10 ５ μm ３ The above 5 x 10 ６ μm ３ In the following, the volume Vmax of the virtual hemisphere 2 is 5 times or more but less than 1000 times Vmin, A liquid discharge head characterized in that the area A of the surface of the pressure chamber on which the opening end of the nozzle hole is provided is 5 × 10⁴ μm² or more and 2 × 10⁵ μm² or less.

3. Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5×10 ５ μm ３ or more and 5×10 ６ μm ３ or less. The volume Vmax of the virtual hemisphere 2 is 5 times or more and less than 1000 times that of Vmin, A liquid discharge head characterized in that the volume V1 of the pressure chamber is 10 nl or less.

4. Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5 × 10 ５ μm ３ The above 5 x 10 ６ μm ３ In the following, the volume Vmax of the virtual hemisphere 2 is 5 times or more but less than 1000 times Vmin, The nozzle plate has the nozzle hole that forms the nozzle hole, A liquid dispensing head characterized in that the thickness of the nozzle plate is 25 μm or more and 45 μm or less.

5. Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5 × 10 ５ μm ３ The above 5 x 10 ６ μm ３ In the following, the volume Vmax of the virtual hemisphere 2 is 5 times or more but less than 1000 times Vmin, A liquid dispensing head characterized by being a non-circulating type liquid dispensing head that does not circulate the liquid.

6. Multiple nozzle holes for dispensing liquid, A liquid discharge head comprising a pressure chamber communicating with the nozzle hole, Let the intersection of the virtual center line of the nozzle hole and the extension plane of the surface of the pressure chamber where the opening end of the nozzle hole is provided be the center of the sphere. When extensions are drawn from this intersection in the direction opposite to the liquid discharge direction from the nozzle hole, in both directions of the nozzle arrangement, and in both directions perpendicular to the opposite direction of the liquid discharge direction from the nozzle hole and the nozzle arrangement direction, the length at which the distance to any surface of the pressure chamber is shortest is defined as the radius rmin, and the length at which the distance to any surface of the pressure chamber is longest is defined as the radius rmax. If the hemisphere with the center of the sphere as its center point and radius rmin is defined as virtual hemisphere 1, and the hemisphere with the center of the sphere as its center point and radius rmax is defined as virtual hemisphere 2, The volume Vmin of the virtual hemisphere 1 is 5 × 10 ５ μm ３ The above 5 x 10 ６ μm ３ In the following, the volume Vmax of the virtual hemisphere 2 is 5 times or more but less than 1000 times Vmin, The liquid ejection head is characterized in that the liquid is an ink containing water, an organic solvent, and a pigment.

7. The area of ​​the cross-section perpendicular to the extending direction of the nozzle hole is 300 μm². ２ 360 μm or more ２ The liquid dispensing head according to claim 1, wherein the following applies:

8. A liquid dispensing device comprising a liquid dispensing head according to any one of claims 1 to 7.

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