Liquid ejection head, head module, head unit, liquid ejection unit, and liquid ejection device

Abstract

To provide a liquid discharge head capable of suppressing generation of discharge bending regardless of a complex manufacturing step and regardless of a position of a meniscus in a nozzle hole.SOLUTION: A liquid discharge head 100 is equipped with a nozzle substrate 30 formed with a nozzle hole 6 discharging liquid, a liquid chamber 5 communicating with the nozzle hole 6, a vibration plate 3 that forms a part of a wall surface of the liquid chamber 5, and pressure generating means (piezoelectric element) 2 that is formed on a back surface of a surface opposing to the liquid chamber 5 of the vibration plate 3, and pressurizes the liquid in the liquid chamber. The pressurized liquid is discharged from the nozzle hole 6 as droplets. Assuming a vertical distance in a liquid discharging direction between a first line segment extending from a displacement center R indicating the maximum displacement amount of a deformation area 3a of the vibration plate 3 in the liquid discharging direction and a second line segment extending from a center position of the nozzle hole 6 in the liquid discharging direction as a gap g, the gap q is 40 μm or less.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head, a head module, a head unit, a liquid ejection unit, and an apparatus for ejecting liquid. [Background technology]

[0002] 2. Description of the Related Art As an example of a device for ejecting liquid, an inkjet printer is known, which ejects minute droplets of ink from a liquid ejection head and causes them to land on a recording medium, thereby forming an image pattern.

[0003] A liquid ejection head is equipped with a pressure generating means that applies ejection pressure to the liquid in a liquid chamber that communicates with the nozzle holes. Known examples of pressure generating means include a piezoelectric element that includes a thin-film piezoelectric material. In a structure in which a piezoelectric element and a diaphragm are bonded together, applying a voltage between electrodes formed on both sides of the thin-film piezoelectric material causes the piezoelectric material to contract in the planar direction, while the diaphragm does not contract, resulting in bending deformation. A liquid ejection head using this method bends and deforms the wall of the liquid chamber that generates pressure facing the ejection port, thereby increasing or decreasing the volume of the liquid chamber and ejecting liquid.

[0004] The amount of displacement of the diaphragm, which receives force from the piezoelectric element, is not uniform, and therefore the direction of the pressure applied to the ink liquid filling the liquid chamber is not perpendicular to the surface of the diaphragm throughout. As a result, even if the nozzle holes are drilled perpendicular to the wall of the liquid chamber, the ink droplets are not ejected perpendicular to the inkjet head, but are ejected at an angle, resulting in a problem of misalignment in the printing position. If the ejected ink droplets are curved, the wider the printing gap, the greater the difference in landing position, which affects print quality.

[0005] To address this issue, technologies have been proposed to correct the deflection of the ejection by tilting the nozzle hole or diaphragm, and to correct the flow of liquid leading up to droplet ejection by increasing the length of the nozzle (see, for example, Patent Document 1).

[0006] Patent Document 1 discloses a configuration in which the central axis of the nozzle is tilted toward the central normal of the diaphragm, or the diaphragm itself is tilted, in order to eliminate deflection when ink droplets are ejected, so that the ink droplets are ejected perpendicular to the inkjet head. Summary of the Invention [Problem to be solved by the invention]

[0007] However, conventional techniques for eliminating deflection of the ejection direction have the problem that they require complex manufacturing processes, such as forming the base nozzle hole, the vibration plate, etc. at an angle. Furthermore, there are problems with increasing the length of the nozzle, such as an increase in fluid resistance, a decrease in the meniscus return speed, and a decrease in response frequency. Furthermore, there is also the problem that the degree of ejection deflection changes depending on the position of the meniscus within the nozzle hole.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a liquid ejection head that can suppress the occurrence of deflected ejection without using complicated manufacturing processes and regardless of the position of the meniscus inside the nozzle hole. [Means for solving the problem]

[0009] In order to solve the above problems, the liquid ejection head of the present invention comprises a nozzle substrate in which nozzle holes for ejecting liquid are formed, a liquid chamber communicating with the nozzle holes, a vibration plate forming part of a wall surface of the liquid chamber, and a pressure generating means formed on the back surface of the vibration plate opposite to the liquid chamber, the pressure generating means pressurizing the liquid inside the liquid chamber, wherein the pressurized liquid is ejected as droplets from the nozzle holes, the pressure generating means has a restraint portion by a wiring layer at one end side in the longitudinal direction of the liquid chamber, and no restraint portion by a wiring layer at the other end side in the longitudinal direction of the liquid chamber, When the gap is defined as the distance in the direction perpendicular to the liquid ejection direction between a first line segment extending in the liquid ejection direction from the displacement center indicating the maximum displacement amount of the deformation area of the vibration plate and a second line segment extending in the liquid ejection direction from the center position of the nozzle hole, the gap is characterized by being 40 μm or less. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a liquid ejection head that can suppress the occurrence of deflected ejection without using a complicated manufacturing process and regardless of the position of the meniscus inside the nozzle hole. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of an example of a liquid ejection head. [Figure 2] FIG. 2 is a cross-sectional view of an example of a nozzle of a nozzle substrate. [Figure 3] FIG. 2 is a cross-sectional view of a nozzle of a nozzle substrate, illustrating a meniscus in the nozzle. [Figure 4] FIG. 10 is a cross-sectional view illustrating an example of a conventional liquid ejection head. [Figure 5] FIG. 10 is a cross-sectional view illustrating an example of a conventional liquid ejection head. [Figure 6] 1 is a cross-sectional view illustrating an example of a liquid ejection head according to the present invention. [Figure 7] FIG. 10 is a cross-sectional view illustrating another example of a liquid ejection head according to the present invention. [Figure 8] FIG. 10 is a cross-sectional view illustrating another example of a liquid ejection head according to the present invention. [Figure 9] 10 is a graph showing the measurement results of the amount of ejection deflection in a conventional liquid ejection head. [Figure 10] 10 is a graph showing the measurement results of the amount of ejection deflection in the liquid ejection head according to the present invention. [Figure 11] FIG. 1 is an explanatory diagram illustrating an example of an apparatus for discharging liquid. [Figure 12] 12 is an explanatory plan view of a head unit included in the liquid ejecting device of FIG. 11. FIG. [Figure 13] FIG. 2 is a plan view illustrating a main part of the device for discharging liquid. [Figure 14] FIG. 2 is a side view illustrating a main part of the device for discharging liquid. [Figure 15] FIG. 10 is a plan view illustrating a main part of an example of a liquid ejection unit; [Figure 16] FIG. 2 is a front view illustrating a main part of an example of a liquid ejection unit. [Figure 17] FIG. 2 is an exploded perspective view illustrating an example of a head module. [Figure 18] FIG. 2 is an exploded perspective view illustrating an example of a head module. [Figure 19] FIG. 4 is an explanatory diagram showing an example of a matrix arrangement of nozzles. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a liquid ejection head, a head module, a head unit, a liquid ejection unit, and a liquid ejection device according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments, and other modifications, additions, corrections, deletions, and other changes can be made within the scope of what a person skilled in the art can conceive. Any aspect is within the scope of the present invention as long as it achieves the functions and effects of the present invention.

[0013] [Liquid ejection head] The basic configuration of a liquid ejection head according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an example of a liquid ejection head to which the present invention is applied, and FIGS. 2 and 3 are cross-sectional views of nozzles on a nozzle substrate.

[0014] The liquid ejection head 100 shown in FIG. 1 is of a side shooter type that ejects liquid from nozzle holes 6 provided on the surface of the substrate. In the nozzle substrate 30, nozzle holes 6 are formed at positions corresponding to the individual liquid chambers (pressurized liquid chambers) 5.

[0015] The actuator substrate 10 includes a piezoelectric element 2 that generates liquid ejection energy, and a vibration plate 3 . Furthermore, on the actuator substrate 10, partition walls (pressurized liquid chamber partition walls) 4, liquid chambers 5, fluid resistance portions 7, and common liquid flow paths 9 are formed, and each liquid chamber 5 is separated by the partition walls 4.

[0016] The subframe substrate 20 is formed with a liquid supply port 66 for supplying liquid from the outside, a through-hole portion communicating with the liquid supply port, and a void portion that allows the vibration plate 3 to bend, and the through-hole portion is connected to the through-hole portion 60 of the actuator substrate 10.

[0017] The nozzle substrate 30, the actuator substrate 10, and the subframe substrate 20 are joined together to form the liquid ejection head 100.

[0018] It is important that the liquid ejection head is capable of ejecting liquid perpendicular to the ejection surface of the nozzle substrate 30. In other words, it is important that the liquid ejection head is capable of ejecting liquid perpendicular to the recording surface of a recording medium that is arranged parallel to the ejection surface. For example, if ink droplets are ejected obliquely in an inkjet recording device, streaks will appear in the image, impairing the image quality. To prevent such problems from occurring, the shape of the nozzles, which are the ejection ports for droplets (ink droplets), is extremely important.

[0019] FIG. 2 is an explanatory diagram showing a cross section of the nozzle hole 6. As shown in FIG. In the liquid ejection head of this embodiment, the nozzle hole preferably has a two-stage shape with different cross-sectional areas of the cylinder formed by the nozzle inner wall surface 31 as shown in FIG. The smaller the diameter Wa of the nozzle hole 6 in the ejection direction (outlet side), the smaller the ink droplets that can be ejected, which improves the image resolution and allows the formation of high-quality images. On the other hand, if the volume of the nozzle hole 6 is small, the fluid resistance increases and the freedom of discharge control is impaired, so by providing an introduction section with a diameter Wb larger than the diameter Wa of the nozzle outlet, the fluid resistance can be reduced.

[0020] Important elements of the nozzle shape for ejecting droplets (ink droplets) vertically include that the nozzle hole 6 is formed perpendicular to the nozzle substrate 30, that the cross-sectional shape is a perfect circle, and that the nozzle inner wall surface 31 is smooth. The nozzle holes 6 may be formed by a press method in which holes are made by pressing when the nozzle substrate 30 is a metal plate, or by a dry etching method in which holes are made by etching when the nozzle substrate 30 is a Si substrate.

[0021] From the viewpoint of high controllability of the shape of the nozzle hole 6, the dry etching method is superior. Dry etching methods include, for example, ion-assisted anisotropic etching and anisotropic etching using the Bosch process. The former has the characteristic that the deeper the hole, the thinner the diameter becomes, while the latter has the characteristic that the hole can be formed vertically while maintaining the diameter dimension. For this reason, it is preferable to form the nozzle hole 6 by dry etching using the Bosch process. By adopting a method that ensures high perpendicularity of the nozzle inner wall surface 31, it is possible to prevent the discharged droplets from bending.

[0022] FIG. 3 is a cross-sectional view of the nozzle substrate 30 including the nozzle hole 6, and is an explanatory diagram of the meniscus in the nozzle hole 6. The meniscus in the nozzle hole 6 has a difference in the position of the meniscus center, indicated by m1 in the figure, between M1, which is formed at a position close to the nozzle surface (ejection port), and M2, which has retreated toward the liquid chamber. If the nozzle hole 6 is made longer, m1 also increases, which reduces the meniscus's recovery speed and poses the problem of a lower response frequency.

[0023] 4 and 5 are explanatory longitudinal cross-sectional views of a liquid chamber 5 of a conventional liquid ejection head. The piezoelectric element (actuator) 2, which serves as pressure generating means for deforming the diaphragm 3, has a restraining portion due to a wiring layer 40 such as an electrode, and the deformation of the diaphragm 3 caused by the piezoelectric element 2 is not necessarily symmetrical left-right or top-bottom. A deformation region 3a, which schematically shows the deformed state of the diaphragm 3, is indicated by a dashed line.

[0024] 4 and 5, the right end of the piezoelectric element 2 is constrained due to contact of the upper electrode with the wiring layer 40. For this reason, the displacement center R in the deformation region 3a of the diaphragm 3 is shifted to the left from the center position based on the piezoelectric element 2 and the liquid chamber 5. Furthermore, an imaginary line P, which is an extension of the displacement center R in the liquid ejection direction, does not overlap with the nozzle hole 6, which is the ejection port. The central axis of the nozzle hole 6 in the figure is indicated by Q. The gap between the imaginary line P and the central axis Q is, for example, about 65 μm.

[0025] The displacement center R refers to the position that indicates the maximum displacement amount of the amplitude of the diaphragm 3. It can be indicated by a point on the cross section of the diaphragm 3 in the short side direction and the long side direction.

[0026] FIG. 5 is a diagram also showing the meniscus. When ink is ejected in this state, when the position of the meniscus changes between M1 and M2, the direction of the pressure propagating from the displacement center R to the center of the meniscus also changes, and as a result, the ejection direction of the resulting ink droplets deviates from the perpendicular direction of the head. As shown in FIG. 5, when the position of the meniscus changes between M1 and M2, a difference indicated by m2 occurs on the recording medium S, which is the ejection surface.

[0027] FIG. 9 shows the results of measuring the amount of deflection of ink droplets ejected from a conventional liquid ejection head. The amount of bending was measured using a particleizer (for taking ejection images) and the binary processing program SOGAS (for calculating the center of gravity of ejected droplets) under the following conditions. Drive condition: 10kHz Simple pull waveform ·Temperature: 23℃ Step-by-step drive (4 steps / row x 2 rows = 8 steps) As a result of the measurement, the average value of the discharge deflection was -0.32°, and 3σ was 0.25°. In this way, the amount of ink ejection deflection is large and the overall variation is also large, which may make it difficult to form high-quality images.

[0028] FIG. 6(A) is an explanatory cross-sectional view in the longitudinal direction of a liquid chamber 5 of a liquid ejection head according to the present invention, and FIG. 6(B) is a view also showing the meniscus. As shown in Figure 6, the liquid ejection head of this embodiment comprises a nozzle substrate 30 in which a nozzle hole 6 for ejecting liquid is formed, a liquid chamber 5 communicating with the nozzle hole 6, a vibration plate 3 forming part of the wall surface of the liquid chamber 5, and a pressure generating means (piezoelectric element) 2 formed on the back surface of the vibration plate 3 opposite the liquid chamber 5, and pressurizing the liquid inside the liquid chamber, and in this liquid ejection head in which the pressurized liquid is ejected as droplets from the nozzle hole 6, when the gap g is defined as the distance in the direction perpendicular to the liquid ejection direction between a first line segment extending in the liquid ejection direction from the displacement center R indicating the maximum displacement amount of the deformation region 3a of the vibration plate 3, and a second line segment extending in the liquid ejection direction from the center position of the nozzle hole 6, the gap g is 40 μm or less.

[0029] Through detailed studies by the inventors, it has been found that misalignment can be suppressed by setting the gap g to 40 μm or less. Furthermore, it is preferable that the gap g is 20 μm or less. In this case, misalignment can be further suppressed.

[0030] The distance (gap g) between the first line segment and the second line segment in the direction perpendicular to the liquid ejection direction can also be said to be the gap between the imaginary line P and the central axis Q. In the example of the prior art described above, the gap between the imaginary line P and the central axis Q is about 65 μm, which is not included in the present invention.

[0031] Furthermore, by setting the gap g to 40 μm or less, even if the meniscus position changes between M1 and M2, the direction of the pressure propagating from the displacement center R to the center of the meniscus does not change, or the change in the direction of the pressure can be made very small. As a result, the ejection direction of the ink droplets does not deviate from the direction perpendicular to the head. As shown in Figure 6(B), even if the meniscus position changes between M1 and M2, there is no deviation in the ejection position on the ejected surface, the recording medium S.

[0032] Furthermore, the liquid ejection head according to this embodiment can be obtained by aligning the displacement center R of the deformation region 3a of the vibration plate 3 with the position of the nozzle hole 6, without performing complex processing in the manufacturing process. According to this embodiment, it is possible to suppress the occurrence of ejection deflection without using complex manufacturing processes and regardless of the position of the meniscus inside the nozzle hole.

[0033] In addition, in the liquid ejection head of this embodiment, when viewed in a plane from the liquid ejection direction, the distance between the displacement center R, which indicates the maximum displacement amount of the deformation area 3a of the vibration plate 3, and the center position of the nozzle hole 6 is 40 μm or less.

[0034] Next, another example of this embodiment will be described. In this embodiment, in plan view from the liquid ejection direction, it is preferable that the displacement center R, which indicates the maximum displacement amount of the deformation region 3a of the vibration plate 3, is located inside the nozzle hole 6. In other words, it is preferable that the displacement center R, which indicates the maximum displacement amount of the deformation region 3a of the vibration plate 3, and the position of the nozzle hole 6 overlap in plan view.

[0035] 7(A) and 8 are explanatory cross-sectional views in the longitudinal direction of the liquid chamber 5 of the liquid ejection head according to this example, and Fig. 7(B) is a schematic plan view of the vibration plate 3 in the liquid ejection direction from the nozzles. In Fig. 7(B), the conventional nozzle position is indicated by the symbol 6a.

[0036] As shown in FIGS. 7 and 8, in the liquid ejection head according to this example, the displacement center R indicating the maximum displacement amount of the deformation region 3a of the vibration plate 3 and the position of the nozzle hole 6 overlap in a plan view. The term "planar view" refers to a planar view in the direction of liquid ejection from the nozzles.

[0037] FIG. 8 is a diagram also showing the meniscus. Even if the position of the meniscus changes between M1 and M2, the direction of the pressure propagating from the displacement center R to the center of the meniscus does not change, so the ejection direction of the ink droplets does not deviate from the head perpendicular direction. As shown in FIG. 8, even if the position of the meniscus changes between M1 and M2, no deviation occurs in the ejection position on the recording medium S, which is the ejection receiving surface.

[0038] The liquid ejection head of this example is obtained by aligning the displacement center R of the deformation area 3a of the vibration plate 3 with the position of the nozzle hole 6 without performing complex processing in the manufacturing process, thereby making it possible to further suppress the occurrence of ejection bending regardless of the position of the meniscus within the nozzle hole 6.

[0039] Furthermore, in this embodiment, it is more preferable that the displacement center R of the vibration plate 3 overlaps with the central axis Q of the nozzle hole 6. In other words, it is more preferable that an imaginary line P extending from the displacement center R in the liquid ejection direction overlaps with the central axis Q of the nozzle hole 6. By doing so, it is possible to further suppress the occurrence of deflected ejection.

[0040] Next, in the examples of the liquid ejection heads shown in FIGS. 7 and 8, the results of measuring the amount of deflection of ejected ink droplets, which is the difference in how the droplets are deflected when they fly, are shown in FIG. The measurement was carried out in the same manner as the measurement for the conventional liquid ejection head shown in FIG. As a result of the measurement, the average value of the discharge deflection was -0.13°, and 3σ was 0.19°. In this way, the amount of deflection of the ink ejection is small and the overall variation is also small, making it possible to form high-quality images. At this time, the gap between the imaginary line P and the central axis Q was 5 μm.

[0041] Similarly, the same measurements were performed on a liquid ejection head with a 20 μm gap between the virtual line P and the central axis Q. As a result, the average amount of ejection deflection was -0.23°. As can be seen from these results, positional deviation can be further reduced by reducing the gap.

[0042] Furthermore, the liquid ejection head of this embodiment preferably includes a plurality of nozzle holes 6, and the plurality of nozzle holes 6 are preferably arranged in a matrix. An example of a matrix arrangement is shown in FIG. By arranging the nozzle holes 6 in a matrix, it is possible to increase the nozzle density and reduce crosstalk, and it is also possible to achieve a smaller head.

[0043] [Head module] Next, an example of a head module according to the present invention will be described with reference to Figures 17 and 18. Figure 17 is an exploded perspective view of the head module, and Figure 18 is an exploded perspective view of the head module as seen from the nozzle surface side. The head module according to the present invention is formed by arranging a plurality of the liquid ejection heads according to the present invention described above.

[0044] The head module 200 includes a plurality of heads 100 which are liquid ejection heads that eject liquid, a base member 103 that holds the plurality of heads 100, and a cover member 113 that serves as a nozzle cover for the plurality of heads 100. The head module 200 also includes a heat dissipation member 104, a manifold 105 that forms a flow path for supplying liquid to a plurality of heads, a printed circuit board (PCB) 106 that connects to the flexible wiring member 101, and a module case 107.

[0045] [Head unit, liquid ejection unit, liquid ejection device] An example of a device for ejecting liquid according to the present invention will be described with reference to Fig. 11, and an example of a head unit will be described with reference to Fig. 12. Fig. 11 is a schematic explanatory diagram of a device for ejecting liquid, and Fig. 12 is a plan explanatory diagram of an example of a head unit provided in the device of Fig. 11.

[0046] The liquid ejection device according to the present invention includes the liquid ejection head 100 according to the present invention described above.

[0047] The printing device 500, which is a device for ejecting liquid, includes an input means 501 for inputting a continuous body 510 such as continuous paper or sheet material, which is a recording medium; a guide and conveying means 503 for guiding and conveying the continuous body 510 inputted from the input means 501 to a printing means 505; the printing means 505 for printing by ejecting liquid onto the continuous body 510 to form an image; a drying means 507 for drying the continuous body 510; and an output means 509 for outputting the continuous body 510.

[0048] The continuous body 510 is fed from the original winding roller 511 of the carrying-in means 501 , guided and conveyed by the rollers of the carrying-in means 501 , the guide and conveying means 503 , the drying means 507 and the carrying-out means 509 , and wound up by the winding roller 591 of the carrying-out means 509 .

[0049] In the printing means 505, this continuum 510 is transported on a transport guide member 559 opposite the head unit 550 and head unit 555, an image is formed by liquid ejected from the head unit 550, and post-processing is performed by processing liquid ejected from the head unit 555.

[0050] The head unit is, for example, a row of head modules each including an array of the liquid ejection heads according to the present invention. Here, in the head unit 550, for example, full line type head arrays 551A, 551B, 551C, and 551D (hereinafter referred to as "head array 551" when no distinction is made between colors) for four colors are arranged from the upstream side in the transport direction.

[0051] Each head array 551 is a liquid ejection means, and ejects liquid of black K, cyan C, magenta M, or yellow Y onto the conveyed continuum 510. Note that the types and numbers of colors are not limited to these.

[0052] The head array 551 is, for example, a liquid ejection head (also simply referred to as a "head") 100 according to the present invention arranged in a staggered pattern on a base member 552, but is not limited to this.

[0053] Next, another example of a printing device as a device for ejecting liquid according to the present invention will be described with reference to Figures 13 and 14. Figure 13 is an explanatory plan view of the main parts of the device, and Figure 14 is an explanatory side view of the main parts of the device.

[0054] The printing device 500 is a serial type device, and a carriage 403 is moved back and forth 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 and movably holds the carriage 403. The main scanning motor 405 then moves the carriage 403 back and forth in the main scanning direction via a timing belt 408 hung between a drive pulley 406 and a driven pulley 407.

[0055] This carriage 403 is equipped with a liquid ejection unit 440 that integrates a liquid ejection head 100 according to the present invention and a head tank 441. The liquid ejection head 100 of the liquid ejection unit 440 ejects liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 100 is mounted with a nozzle row consisting of multiple nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ejection direction facing downward.

[0056] This printing apparatus 500 is equipped with 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.

[0057] The conveyor belt 412 attracts the paper 410 and conveys it at a position facing the liquid ejection head 100. The conveyor belt 412 is an endless belt that is stretched between a conveyor roller 413 and a tension roller 414. The paper can be attracted by electrostatic attraction or air suction.

[0058] The conveyor belt 412 moves in a circular motion in the sub-scanning direction when the conveyor roller 413 is rotationally driven by a sub-scanning motor 416 via a timing belt 417 and a timing pulley 418 .

[0059] Furthermore, a maintenance and recovery mechanism 420 for performing maintenance and recovery of the liquid ejection head 100 is disposed on one side of the conveyor belt 412 on one side of the carriage 403 in the main scanning direction.

[0060] The maintenance and recovery mechanism 420 is made up of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzles are formed) of the liquid ejection head 100, a wiper member 422 that wipes the nozzle surface, and the like.

[0061] The main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the transport mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

[0062] In the printing device 500 configured in this manner, the paper 410 is fed onto the conveyor belt 412 and adsorbed thereon, and the paper 410 is conveyed in the sub-scanning direction by the circular movement of the conveyor belt 412.

[0063] Therefore, by driving the liquid ejection head 100 in accordance with 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.

[0064] Another example of the liquid discharge unit according to the present invention will be described with reference to FIGS. The liquid ejection device according to the present invention includes the liquid ejection head 100 according to the present invention described above.

[0065] Examples of liquid ejection units include a liquid ejection head integrated with at least one of the following: a head tank that stores liquid to be supplied to the liquid ejection head; a carriage that mounts the liquid ejection head; a supply mechanism that supplies liquid to the liquid ejection head; a maintenance and recovery mechanism that maintains and recovers the liquid ejection head; and a main scanning movement mechanism that moves the liquid ejection head in the main scanning direction.

[0066] FIG. 15 is a plan view illustrating a main part of an example of a liquid ejection unit. This liquid ejection unit 440 is composed of the components that make up the device for ejecting the liquid, including 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 100.

[0067] It is also possible to configure a liquid discharge unit in which the above-described maintenance and recovery mechanism 420 is further attached to, for example, the side plate 491B of this liquid discharge unit 440.

[0068] FIG. 16 is an explanatory front view showing an example of a liquid ejection unit. This liquid ejection unit 440 is composed of a liquid ejection head 100 to which a flow path part 444 is attached, and a tube 456 connected to the flow path part 444 .

[0069] 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. A connector 443 for electrically connecting with the liquid ejection head 100 is provided on the upper part of the flow path part 444.

[0070] In this application, a "liquid ejecting device" refers to a device that includes a liquid ejection head or a liquid ejection unit and ejects liquid by driving the liquid ejection head. In addition to the above examples, liquid ejecting devices include not only devices that can eject liquid onto objects onto which the liquid can adhere, but also devices that eject liquid into air or liquid. 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.

[0071] For example, examples of "liquid ejecting devices" include image forming devices that eject ink to form images on paper, and three-dimensional modeling devices (three-dimensional modeling devices) that eject modeling liquid onto a powder layer formed from layers of powder in order to create a three-dimensional object (a three-dimensional model). Furthermore, 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.

[0072] The above-mentioned "object onto which a liquid can adhere" means an object onto which a liquid can adhere at least temporarily, an object onto which the liquid can adhere and stick, an object onto which the liquid can penetrate, etc. Specific examples include media such as paper, recording paper, film, and cloth, electronic circuit boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects onto which a liquid can adhere.

[0073] The material of the "substance to which a liquid can adhere" may be any material to which a liquid can adhere, even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, or ceramics.

[0074] The "liquid" is not particularly limited as long as it has a viscosity and surface tension that allows it to be ejected from a head, but it is preferably one whose viscosity is 30 mPa·s or less at room temperature and normal pressure, or upon heating or cooling. 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 functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, or an edible material such as a natural colorant. These can be used, for example, as inkjet inks, surface treatment liquids, liquids for forming components of electronic devices or light-emitting elements, or electronic circuit resist patterns, and material liquids for 3D modeling.

[0075] Furthermore, the "liquid ejection device" may be a device in which a liquid ejection head and an object onto 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, and a line type device in which a liquid ejection head does not move.

[0076] Other examples of "liquid ejecting devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials. [Explanation of symbols]

[0077] 2. Piezoelectric element 3 Vibration plate 3a Deformation area 4 Bulkhead 5 Liquid chamber 6 nozzle holes 7 Fluid resistance section 9 Common liquid flow path 10 Actuator board 20 Subframe board 30 nozzle board 31 Nozzle inner wall surface 40 wiring layer 60 through hole 66 Liquid supply port 100 Liquid ejection head 200 Head Module 440 Liquid Dispensing Unit 500 Liquid ejection device (printing device) R Displacement center Q Nozzle hole central axis [Prior art documents] [Patent documents]

[0078] [Patent Document 1] Japanese Patent Application Publication No. 7-117224

Claims

1. a nozzle substrate in which nozzle holes for ejecting liquid are formed; a liquid chamber communicating with the nozzle hole; a vibration plate forming a part of the wall surface of the liquid chamber; a pressure generating means formed on a surface of the vibration plate opposite to the surface facing the liquid chamber, the pressure generating means pressurizing the liquid inside the liquid chamber, wherein the pressurized liquid is ejected as droplets from the nozzle holes, the pressure generating means has a restraint portion by a wiring layer at one end side in the longitudinal direction of the liquid chamber, and no restraint portion by a wiring layer at the other end side in the longitudinal direction of the liquid chamber, A liquid ejection head characterized in that, when the gap is defined as the distance in a direction perpendicular to the liquid ejection direction between a first line segment extending in the liquid ejection direction from the displacement center indicating the maximum displacement amount of the deformation area of the vibration plate and a second line segment extending in the liquid ejection direction from the center position of the nozzle hole, the gap is 40 μm or less.

2. A liquid ejection head as described in Claim 1, characterized in that the deformation of the vibration plate caused by the pressure generating means is asymmetrical in the longitudinal cross section of the liquid chamber.

3. 3. The liquid ejection head according to claim 1, wherein, in a plan view seen from the liquid ejection direction, a displacement center showing a maximum displacement amount of a deformation region of the vibration plate is located within the nozzle hole.

4. 4. A liquid ejection head according to claim 1, wherein the gap is 20 [mu]m or less.

5. 5. The liquid ejection head according to claim 1, wherein the displacement center of the vibration plate and the central axis of the nozzle hole overlap.

6. 6. The liquid ejection head according to claim 1, wherein the plurality of nozzle holes are arranged in a matrix.

7. A head module comprising a plurality of liquid ejection heads according to any one of claims 1 to 6 arranged in an array.

8. A head unit, characterized in that head modules each including a plurality of liquid ejection heads according to any one of claims 1 to 6 are arranged side by side.

9. A liquid ejection unit comprising the liquid ejection head according to any one of claims 1 to 6.

10. The liquid ejection unit described in claim 9, characterized in that the liquid ejection head is integrated with at least one of a head tank that stores liquid to be supplied to the liquid ejection head, a carriage that mounts the liquid ejection head, a supply mechanism that supplies liquid to the liquid ejection head, a maintenance and recovery mechanism that maintains and recovers the liquid ejection head, and a main scanning movement mechanism that moves the liquid ejection head in the main scanning direction.

11. A liquid ejection device comprising the liquid ejection head according to any one of claims 1 to 6.

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