Inkjet recording method

Abstract

To provide an inkjet recording method which can maintain discharging of reaction liquid stably and suppress occurrence of image irregularity.SOLUTION: In an inkjet recording method, a liquid discharging head discharges aqueous ink and aqueous reaction liquid containing a reactant that reacts to the aqueous ink, respectively to record an image on a recording medium. The liquid discharging head has: a discharge port for discharging the aqueous reaction liquid; an element substrate which has a pressure chamber for supplying liquid to the discharge port and a discharging element for generating energy for discharging liquid; an upstream-side flow passage for supplying liquid to the pressure chamber; a downstream-side flow passage communicated with the pressure chamber; and a pump, communicated with the upstream-side flow passage and the downstream-side flow passage, which is configured to flow liquid in the downstream-side flow passage into the upstream-side flow passage, which further is provided with temperature adjusting means configured to be able to heat the aqueous ink or the aqueous reaction liquid.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an inkjet recording method. [Background technology]

[0002] In recent years, inkjet recording methods have been increasingly used in the field of sign and display, such as printing posters and large-format advertisements. In this field, inkjet recording devices are characterized by a larger recording area than home inkjet recording devices. In addition, since images need to be eye-catching, inks that can record images with high color development are required.

[0003] In the sign and display field, non-absorbent recording media, whose surfaces are made of polyvinyl chloride (PVC) or polyethylene terephthalate (PET), and whose ink absorption properties are almost nonexistent, are often used. For this reason, it is necessary to suppress bleeding and unevenness of images on non-absorbent recording media. Hereinafter, recording media whose surfaces are almost ink-absorbent will also be referred to as "non-absorbent recording media." In the inkjet recording method for recording on non-absorbent recording media, it is important to suppress bleeding by preventing ink dots from being repelled by the recording medium. To achieve this, it is necessary to rapidly thicken and fix the ink after it is applied to the recording medium.

[0004] As a method for recording on a non-absorbent recording medium, a recording method using a solvent-based ink containing an organic solvent as a main component or a curable ink containing a polymerizable monomer is known. However, in recent years, from the viewpoints of environmental load and safety, there is an increasing need for a recording method that can record on a non-absorbent recording medium using a water-based ink.

[0005] Methods for recording on non-absorbent recording media using aqueous ink include a method for evaporating the water content of the ink on the surface of the non-absorbent recording media, and a method for using a reaction liquid that aggregates the ink components. The former is advantageous in terms of running costs because there is no need to provide a means for applying the reaction liquid, but it requires a slower recording speed, which reduces productivity. For this reason, a method using a reaction liquid is being considered.

[0006] In order to improve productivity, it is necessary to shorten the time required for maintenance of the liquid ejection head and enable continuous recording. Maintenance of the liquid ejection head is necessary to prevent the viscosity of the reaction liquid or ink in the ejection ports that are not used during continuous recording from increasing, or the components such as pigments and resins in the reaction liquid or ink from sticking, resulting in a decrease in ejection performance. Therefore, there is a demand for an inkjet recording method that uses a reaction liquid and maintains stable ejection without interruption even during long-term continuous recording.

[0007] A liquid ejection head equipped with a mechanism for moving the ink in the vicinity of the ejection orifices of the liquid ejection head has been proposed in the past in order to suppress retention of ink components such as pigments and resins in the ink flow paths of the liquid ejection head (see Patent Document 1). Also, an inkjet recording method using a liquid ejection head having a circulation flow path has been proposed in order to improve the cleaning recovery of the ejection orifices that eject reaction liquid (see Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2007-118611 A [Patent Document 2] JP 2020-104487 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present inventors have studied various characteristics of the liquid ejection head having a mechanism for flowing ink near the ejection port of the liquid ejection head described in Patent Document 1, and the ink jet recording method using the liquid ejection head described in Patent Document 2. As a result, it was found that in Patent Document 1, the intermittent ejection stability of the reaction liquid can be obtained to a certain extent, but image unevenness occurs. In addition, in Patent Document 2, even if a circulation flow path is provided, the ink is not flowed near the ejection port, so that the intermittent ejection stability of the reaction liquid is insufficient. "Insufficient intermittent ejection stability of the reaction liquid" means that when a state in which the reaction liquid is not ejected for a certain period of time continues, the liquid components in the reaction liquid evaporate from some of the ejection ports, and the ejection state of the reaction liquid from those ejection ports gradually becomes unstable. In other words, intermittent ejection stability refers to a characteristic in which the ejection of the reaction liquid does not become unstable or non-ejection occurs even in such a case, and the recorded image is not easily disturbed.

[0010] The present invention, which solves the above problems, has an object to provide an inkjet recording method capable of maintaining stable ejection of a reaction liquid and suppressing the occurrence of image unevenness. [Means for solving the problem]

[0011] The present invention, which solves the above-mentioned problems, is an inkjet recording method in which an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink are ejected from a liquid ejection head to record an image on a recording medium, wherein the liquid ejection head includes an element substrate having an ejection port for ejecting the aqueous reaction liquid, a pressure chamber for supplying liquid to the ejection port, and an ejection element for generating energy for ejecting the liquid, an upstream flow path for supplying liquid to the pressure chamber, a downstream flow path communicating with the pressure chamber, and a pump communicating with the upstream flow path and the downstream flow path and configured to cause the liquid in the downstream flow path to flow into the upstream flow path, and further includes a temperature adjustment means configured to be able to heat the aqueous ink or the aqueous reaction liquid. Effect of the Invention

[0012] According to the present invention, it is possible to provide an inkjet recording method capable of maintaining stable ejection of a reaction liquid and suppressing the occurrence of image unevenness. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a liquid ejection device. [Diagram 2] FIG. 2 is an exploded perspective view of the liquid ejection head. [Diagram 3] 2A and 2B are a longitudinal section of a liquid ejection head and an enlarged cross-sectional view of an ejection module. [Figure 4] FIG. 2 is a schematic view showing the appearance of a circulation unit. [Diagram 5] FIG. [Figure 6] FIG. 4 is a block diagram showing a schematic diagram of a circulation path. [Figure 7] FIG. 4 is a cross-sectional view showing an example of a pressure adjusting means. [Figure 8] FIG. 2 is an external perspective view of a circulation pump. [Figure 9] 9 is a cross-sectional view of the circulating pump shown in FIG. 8(a) taken along line IX-IX. [Figure 10] 3A and 3B are diagrams illustrating the flow of ink in a liquid ejection head. [Figure 11] FIG. 4 is a schematic diagram showing a circulation path in the discharge unit. [Figure 12] FIG. 3 shows an aperture plate 330. [Figure 13] FIG. 2 is a diagram showing a discharge element substrate. [Figure 14] 5A and 5B are cross-sectional views showing the ink flow in the ejection unit. [Figure 15] FIG. 4 is a cross-sectional view showing the vicinity of a discharge port. [Figure 16] FIG. 11 is a cross-sectional view showing a comparative example near the ejection port. [Figure 17] 11A and 11B are diagrams showing a comparative example of a discharge element substrate. [Figure 18] FIG. 2 is a diagram showing a flow path configuration of a liquid ejection head. [Figure 19] 2A and 2B are diagrams illustrating a connection state between a main body of the liquid ejection device and a liquid ejection head. [Figure 20] FIG. 4 is a diagram showing a discharge element substrate having a temperature adjusting means. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in detail below with reference to preferred embodiments. In the following description, the aqueous inkjet ink and reaction liquid may be simply referred to as "ink" and "reaction liquid".

[0015] The present inventors have studied the problems that arise in the liquid ejection heads described in Patent Documents 1 and 2. As a result, they have considered that by using a liquid ejection head having the configuration described below and flowing the reaction liquid in the liquid ejection head, it is possible to improve the intermittent ejection stability of the reaction liquid and suppress the occurrence of image unevenness. Specifically, a liquid ejection head is used that includes an ejection port for ejecting the reaction liquid, a pressure chamber having an ejection element for generating energy for ejecting the reaction liquid, an upstream flow path for supplying liquid to the pressure chamber, a downstream flow path communicating with the pressure chamber, and a pump communicating with the upstream flow path and the downstream flow path and configured to cause the liquid in the downstream flow path to flow into the upstream flow path.

[0016] The flow of the reaction liquid will be described with reference to FIG. 5. FIG. 5 is a cross-sectional view showing the vicinity of the discharge port 13 in one example of the liquid discharge head of the present invention described later. The liquid discharge head shown in FIG. 5 includes a discharge port 13 for discharging the reaction liquid, a pressure chamber 12 having a discharge element 15 that generates energy for discharging the reaction liquid, and a common supply flow path 18 (upstream flow path) and a common recovery flow path 19 (downstream flow path) that communicate between the discharge port 13 and the discharge element 15 and through which the reaction liquid flows. The reaction liquid flows between the discharge port 13 and the discharge element 15 to the common supply flow path 18 and the common recovery flow path 19 (in the direction of the arrow in FIG. 5). If the reaction liquid does not flow, evaporation of the liquid component from the meniscus of the discharge port 13 progresses, and the reaction liquid present between the discharge port 13 and the discharge element 15 gradually becomes more viscous. For this reason, if the discharge pause time is long, the fluid resistance of the reaction liquid increases during the next discharge operation, which may make it difficult to discharge the reaction liquid. On the other hand, when the reaction liquid flows, the reaction liquid moves in the direction of the arrow in Fig. 5, so that even if liquid components evaporate from the meniscus, the flow of the reaction liquid allows the reaction liquid to be continuously supplied between the discharge port 13 and the discharge element 15. This prevents the reaction liquid from thickening, making it less likely that a state in which it is difficult to discharge will occur. This improves the intermittent discharge stability.

[0017] The flow velocity (mm / s) of the reaction liquid in the pressure chamber 12 is preferably 1.0 mm / s or more and 50.0 mm / s or less. If the flow velocity of the reaction liquid is less than 1.0 mm / s, the supply of the reaction liquid near the meniscus is insufficient, and the reaction liquid is affected by evaporation, and intermittent ejection stability may not be obtained. If the flow velocity of the reaction liquid exceeds 50.0 mm / s, the flow velocity is too high, and the physical properties of the reaction liquid are likely to change due to evaporation, and image unevenness may not be sufficiently suppressed.

[0018] The inventors have found through their research that, while the use of a liquid ejection head that allows the reaction liquid to flow improves the intermittent ejection stability, the difference in viscosity between the reaction liquid and the ink can cause the ejection balance between the reaction liquid and the ink to be lost, resulting in image unevenness. In response to this problem, the inventors have researched a solution using a liquid ejection device that ejects ink and reaction liquid, and have come up with a method of providing the liquid ejection device with a temperature adjustment device for the ink or reaction liquid. Details of the temperature adjustment device will be described later.

[0019] <Inkjet recording method> The inkjet recording method of the present invention is a method for recording an image on a recording medium by ejecting an aqueous ink and an aqueous reaction liquid described below from an inkjet liquid ejection head. It is preferable to have a reaction liquid ejection step of ejecting an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from an ejection port onto the recording medium, and an ink application step of applying an aqueous ink so as to overlap at least a part of the area to which the aqueous reaction liquid is applied. Furthermore, it is more preferable to have a reaction liquid ejection step before the ink application step, or to carry out the ink application step and the reaction liquid ejection step in parallel. It is to be noted that in the present invention, it is not necessary to provide a step of curing the image by irradiation with active energy rays or the like.

[0020] The recording medium is not particularly limited, but a transparent or colored recording medium can be used. The recording medium may be a poorly absorbing medium (non-absorbing medium) having low absorbency of the liquid medium, such as a resin film. Multi-pass recording is preferable in which ink is applied to a unit area of ​​the recording medium by multiple relative scans of the liquid ejection head and the recording medium. In particular, when using a white ink as described later, it is preferable to apply the white ink to the unit area and the color ink or the aqueous reaction liquid by different relative scans. This increases the time until the inks come into contact with each other, making it easier to suppress mixing. The unit area can be set as any area, such as one pixel or one band.

[0021] (1)Liquid discharge device Hereinafter, a preferred embodiment of the present disclosure will be described in detail with reference to the attached drawings with respect to a liquid ejection device (inkjet recording device) that can be used in the inkjet recording method of the present invention. Note that the following embodiment does not limit the subject matter of the present disclosure, and not all combinations of features described in the present embodiment are necessarily essential to the solution of the present disclosure. Note that the same components are given the same reference numbers. In this embodiment, an example is described in which a thermal method is adopted in which an electrothermal conversion element is used to generate bubbles to eject liquid as an ejection element for ejecting liquid, but this is not limited thereto. The present invention can also be applied to a liquid ejection head that employs an ejection method that ejects liquid using a piezoelectric element (piezo) or another ejection method. Furthermore, the pump and pressure adjustment means described below are not limited to the configurations themselves described in the embodiment and drawings.

[0022] <Liquid discharge device> FIG. 1 is a diagram for explaining a liquid ejection device, and is an enlarged view of a liquid ejection head of the liquid ejection device and its surroundings. First, a schematic configuration of a liquid ejection device 50 in this embodiment will be described with reference to FIG. 1. FIG. 1(a) is a perspective view that shows a liquid ejection device using a liquid ejection head 1. The liquid ejection device 50 in this embodiment constitutes a serial type inkjet recording device that performs recording on a recording medium P by ejecting ink as a liquid or a reaction liquid (described later) while scanning the liquid ejection head 1. Hereinafter, the "liquid" in this disclosure includes ink and a reaction liquid containing a reactant that reacts with the ink. In addition, in the following description, "ink" may be used to include ink and a reaction liquid. The liquid ejection head 1 is mounted on a carriage 60. The carriage 60 reciprocates along a guide shaft 51 in a main scanning direction (X direction). The recording medium P is transported in a sub-scanning direction (Y direction) that intersects (orthogonal in this example) with the main scanning direction by transport rollers 55, 56, 57, and 58. In each of the figures referred to below, the Z direction indicates the vertical direction, and intersects (in this example, is perpendicular to) the XY plane defined by the X and Y directions. The liquid ejection head 1 is configured to be detachable and attachable to the carriage 60 by the user.

[0023] The liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 (see FIG. 2) described later. The specific configuration will be described later, but the ejection unit 3 is provided with a plurality of ejection ports and energy generating elements (hereinafter referred to as ejection elements) that generate ejection energy for ejecting liquid from each ejection port.

[0024] The liquid ejection device 50 is also provided with an ink tank 2 (liquid storage section) which is a liquid supply source, and an external pump 21, and the liquid stored in the ink tank 2 is supplied to the circulation unit 54 via a supply tube 59 by the driving force of the external pump 21.

[0025] The liquid ejection device 50 forms a predetermined image on the recording medium P by repeating a recording scan in which the liquid ejection head 1 mounted on the carriage 60 moves in the main scanning direction while ejecting liquid to perform recording, and a transport operation in which the recording medium P is transported in the sub-scanning direction. The liquid ejection head 1 in this embodiment is configured to be capable of ejecting four types of liquid including ink and a reaction liquid described later. However, the configuration of the inkjet recording device in the present invention is not limited to one that ejects four types of liquid. For example, a configuration that can eject black (K), cyan (C), magenta (M), and yellow (Y) inks and a reaction liquid can be exemplified, and in this case, a full-color image can be recorded by using these inks. In addition, the liquid that can be ejected from the liquid ejection head 1 is not limited to the above four types of ink and reaction liquid. The present disclosure is also applicable to liquid ejection heads for ejecting other types of ink and reaction liquid. In other words, the types and number of liquids ejected from the liquid ejection head are not limited.

[0026] Furthermore, the liquid ejection device 50 is provided with a cap member (not shown) capable of covering the ejection port surface on which the ejection ports of the liquid ejection head are formed, at a position offset in the X direction from the transport path of the recording medium P. The cap member covers the ejection port surface of the liquid ejection head 1 during non-recording operations, and is used to prevent the ejection ports from drying out, to protect the ejection ports, and for the purpose of suctioning liquid from the ejection ports, etc.

[0027] 1(a) shows an example in which the liquid ejection head 1 is provided with four circulation units 54 corresponding to the four types of liquid, but it is sufficient that the liquid ejection head 1 is provided with a circulation unit 54 corresponding to the type of liquid to be ejected. Also, multiple circulation units 54 may be provided for the same type of liquid. In other words, the liquid ejection head 1 can be configured to include one or more circulation units. It is also possible to have a configuration in which only at least one reaction liquid is circulated, rather than circulating all four types of liquid.

[0028] FIG. 1B is a block diagram showing a control system of the liquid ejection device 50. The CPU 103 functions as a control means for controlling the operation of each part of the liquid ejection device 50 based on a program such as a processing procedure stored in the ROM 101. The RAM 102 is used as a work area when the CPU 103 executes processing. The CPU 103 receives image data from a host device 400 outside the liquid ejection device 50, controls the head driver 1A, and controls the driving of the ejection elements provided in the ejection unit 3. The CPU 103 also controls the drivers of various actuators provided in the liquid ejection device. For example, the CPU 103 controls a motor driver 105A of a carriage motor 105 for moving the carriage 60, a motor driver 104A of a conveying motor 104 for conveying the recording medium P, and the like. The CPU 103 also controls a pump driver 500A for driving a circulation pump 500 described later, a pump driver 21A of an external pump 21, and the like. Although FIG. 1B shows a form in which processing is performed upon receiving image data from the host device 400, processing may be performed by the liquid ejection device 50 independently of data from the host device 400.

[0029] <Basic configuration of liquid ejection head> Fig. 2 is an exploded perspective view of the liquid ejection head 1 of this embodiment. Fig. 3 is a cross-sectional view taken along line IIIa-IIIa of the liquid ejection head 1 shown in Fig. 2, Fig. 3(a) is an overall vertical cross-sectional view of the liquid ejection head 1, and Fig. 3(b) is an enlarged view of the ejection module 300 shown in Fig. 3(a). The basic configuration of the liquid ejection head 1 of this embodiment will be described below mainly with reference to Fig. 2 and Fig. 3, and also with reference to Fig. 1 as appropriate.

[0030] 2, the liquid ejection head 1 includes a circulation unit 54 and an ejection unit 3 for ejecting ink supplied from the circulation unit 54 onto a recording medium P. The liquid ejection head 1 in this embodiment is fixedly supported on a carriage 60 of the liquid ejection device 50 by positioning means and electrical contacts (not shown) provided on the carriage 60. The liquid ejection head 1 ejects ink while moving together with the carriage 60 in the main scanning direction (X direction) shown in FIG. 1, and performs recording on the recording medium P.

[0031] A supply tube 59 is provided on the external pump 21 connected to the ink tank 2, which is a supply source of ink (see FIG. 1). A liquid connector (not shown) is provided on the tip of the supply tube 59. When the liquid ejection head 1 is mounted on the liquid ejection device 50, the liquid connector provided on the tip of the supply tube 59 is airtightly connected to a liquid connector insertion port 53a, which is a liquid inlet port provided on a head housing 53 of the liquid ejection head 1. This forms an ink supply path from the ink tank 2 to the liquid ejection head 1 via the external pump 21. In this embodiment, since four types of liquid are used, four sets of the ink tank 2, the external pump 21, the supply tube 59, and the circulation unit 54 are provided corresponding to each liquid, and four ink supply paths corresponding to each liquid are independently formed. In this way, the liquid ejection device 50 of this embodiment is provided with a liquid supply system to which liquid is supplied from the ink tank 2 provided outside the liquid ejection head 1. Note that the liquid ejection device 50 of this embodiment is not provided with an ink recovery system that recovers the liquid in the liquid ejection head 1 to the ink tank 2. Therefore, the liquid ejection head 1 is provided with a liquid connector insertion port 53a for connecting a supply tube 59 of the ink tank 2, but is not provided with a connector insertion port for connecting a tube for recovering ink from the liquid ejection head 1 to the ink tank 2. A liquid connector insertion port 53a is provided for each ink.

[0032] 3, 54A indicates a circulation unit for the first ink, 54B indicates a circulation unit for the second ink, 54C indicates a circulation unit for the third ink, and 54D indicates a circulation unit for the reaction liquid. Each circulation unit has substantially the same configuration, and in this embodiment, when there is no particular need to distinguish between each circulation unit, they are all referred to as circulation unit 54.

[0033] 3, when the liquid ejection head has both the ink circulation unit 54 and the reaction liquid circulation unit 54, the reaction liquid circulation unit 54 is preferably arranged at an end in the arrangement direction in which the multiple circulation units 54 are arranged. In the recording operation, after the reaction liquid is applied to the recording medium by a reaction liquid ejection process in which the aqueous reaction liquid is ejected from the ejection port onto the recording medium, it is preferable to perform an ink application process in which an aqueous ink is applied so as to overlap at least a part of the area where the aqueous reaction liquid is applied. In this case, efficient recording is possible by arranging the reaction liquid circulation unit at the end.

[0034] 2 and 3(a), the discharge unit 3 includes two discharge modules 300, a first support member 4, a second support member 7, an electric wiring member (electric wiring tape) 5, and an electric contact substrate 6. As shown in FIG. 3(b), the discharge module 300 includes a silicon substrate 310 having a thickness of 0.5 to 1 mm, and a plurality of discharge elements 15 provided on one side of the silicon substrate 310. In this embodiment, the discharge elements 15 are configured by electrothermal conversion elements (heaters) that generate thermal energy as discharge energy for discharging liquid. Electric power is supplied to each discharge element 15 via electric wiring formed on the silicon substrate 310 by a film formation technique.

[0035] Further, an ejection port forming member 320 is formed on the surface (lower surface in FIG. 3(b)) of the silicon substrate 310. In the ejection port forming member 320, a plurality of pressure chambers 12 corresponding to a plurality of ejection elements 15 and a plurality of ejection ports 13 for ejecting liquid are formed by photolithography. Furthermore, a common supply flow path 18 and a common recovery flow path 19 are formed in the silicon substrate 310. Further, in the silicon substrate 310, a supply connection flow path 323 that communicates the common supply flow path 18 with each pressure chamber 12, and a recovery connection flow path 324 that communicates the common recovery flow path 19 with each pressure chamber 12 are formed. In this embodiment, one ejection module 300 is configured to eject two types of liquid. That is, of the two ejection modules shown in FIG. 3(a), the ejection module 300 located on the left side of the figure ejects the first ink and the second ink, and the ejection module 300 located on the right side of the figure ejects the third ink and the reaction liquid. Note that this combination is an example, and any combination of inks and reaction liquids may be used. One ejection module may be configured to eject one type of liquid, or three or more types of liquid. The two ejection modules 300 do not have to eject the same number of types of liquid. One ejection module 300 may be provided, or three or more ejection modules 300 may be provided. Furthermore, in the example shown in FIG. 3, two ejection port arrays extending in the Y direction are formed for one type of liquid. A pressure chamber 12, a common supply flow path 18, and a common recovery flow path 19 are formed for each of the multiple ejection ports 13 that constitute each ejection port array.

[0036] A liquid supply port and a liquid recovery port, which will be described later, are formed on the back surface (upper surface in FIG. 3(b)) of the silicon substrate 310. The liquid supply port supplies liquid from a liquid supply flow path 48 to the multiple common supply flow paths 18, and the liquid recovery port recovers liquid from the multiple common recovery flow paths 19 to a liquid recovery flow path 49.

[0037] The liquid supply port and liquid recovery port referred to here refer to openings that supply and recover liquid during forward liquid circulation, which will be described later. That is, during forward liquid circulation, liquid is supplied from the liquid supply port to each common supply flow path 18, and liquid is recovered from each common recovery flow path 19 to the liquid recovery port. However, liquid circulation may also be performed in which liquid flows in the reverse direction. In this case, ink is supplied from the liquid recovery port described above to the common recovery flow path 19, and liquid is recovered from the common supply flow path 18 to the liquid supply port.

[0038] As shown in FIG. 3(a), the back surface (upper surface in FIG. 3(a)) of the ejection module 300 is adhesively fixed to one surface (lower surface in FIG. 3(a)) of the first support member 4. A liquid supply flow path 48 and a liquid recovery flow path 49 are formed in the first support member 4, penetrating from one surface to the other surface. One opening of the liquid supply flow path 48 is connected to the aforementioned liquid supply port in the silicon substrate 310, and one opening of the liquid recovery flow path 49 is connected to the aforementioned liquid recovery port in the silicon substrate 310. The liquid supply flow path 48 and the liquid recovery flow path 49 are provided independently for each type of liquid.

[0039] A second support member 7 having an opening 7a (see FIG. 2) through which the discharge module 300 is inserted is adhesively fixed to one surface of the first support member 4 (the upper surface in FIG. 3(a)). The second support member 7 holds an electrical wiring member 5 electrically connected to the discharge module 300. The electrical wiring member 5 is a member for applying an electrical signal to the discharge module 300 for discharging liquid. The electrical connection between the discharge module 300 and the electrical wiring member 5 is sealed with a sealant (not shown) and is protected from corrosion by liquid and external impacts.

[0040] Furthermore, an electrical contact board 6 is thermocompression bonded to an end 5a (see FIG. 2) of the electrical wiring member 5 using an anisotropic conductive film (not shown), and the electrical wiring member 5 and the electrical contact board 6 are electrically connected. The electrical contact board 6 has an external signal input terminal (not shown) for receiving an electrical signal from the liquid ejection device 50.

[0041] Furthermore, a joint member 8 (FIG. 3(a)) is provided between the first support member 4 and the circulation unit 54. A supply port 88 and a recovery port 89 are formed in the joint member 8 for each type of liquid. The supply port 88 and the recovery port 89 communicate the liquid supply flow path 48 and the liquid recovery flow path 49 of the first support member 4 with the flow paths formed in the circulation unit 54. In FIG. 3(a), the supply port 88A and the recovery port 89A correspond to the first ink, and the supply port 88B and the recovery port 89B correspond to the second ink. Furthermore, the supply port 88C and the recovery port 89C correspond to the third ink, and the supply port 88D and the recovery port 89D correspond to the reaction liquid.

[0042] The openings at one end of each of the liquid supply flow channels 48 and the liquid recovery flow channels 49 of the first support member 4 have a small opening area that matches the liquid supply port and the liquid recovery port in the silicon substrate 310. In contrast, the openings at the other end of each of the liquid supply flow channels 48 and the liquid recovery flow channels 49 of the first support member 4 have a shape that is expanded to the same opening area as the large opening area of ​​the joint member 8 formed to match the flow channels of the circulation unit 54. By adopting such a configuration, it is possible to suppress an increase in flow channel resistance to the liquid collected from each recovery flow channel. However, the shapes of the openings at one end and the other end of each of the liquid supply flow channels 48 and the liquid recovery flow channels 49 are not limited to the above example.

[0043] In the liquid ejection head 1 having the above configuration, the liquid supplied to the circulation unit 54 passes through the supply port 88 of the joint member 8 and the liquid supply flow path 48 of the first support member 4, and flows from the liquid supply port of the ejection module 300 into the common supply flow path 18. The liquid then flows from the common supply flow path 18 into the pressure chamber 12 via the supply connection flow path 323, and a portion of the liquid that has flowed into the pressure chamber is ejected from the ejection port 13 by driving the ejection element 15. The remaining liquid that has not been ejected passes from the pressure chamber 12 through the recovery connection flow path 324 and the common recovery flow path 19, and flows from the liquid recovery port into the liquid recovery flow path 49 of the first support member 4. The liquid that has flowed into the liquid recovery flow path 49 then flows into the circulation unit 54 via the recovery port 89 of the joint member 8, and is recovered.

[0044] <Components of the circulation unit> 4 is a schematic external view of one circulation unit 54 corresponding to one type of liquid applied to the recording apparatus of this embodiment. In addition to the circulation pump 500, the circulation unit 54 preferably has a filter 110, a first pressure adjustment means 120, and a second pressure adjustment means 150. These components are connected by respective flow paths as shown in FIGS. 5 and 6, and constitute a circulation path that supplies and recovers liquid to and from the discharge module 300 in the liquid discharge head 1.

[0045] <Circulation path inside the liquid ejection head> FIG. 5 is a vertical cross-sectional view showing a schematic circulation path of one type of liquid (one color ink or reaction liquid) in the liquid ejection head 1. In order to explain the circulation path more clearly, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in FIG. 5 are simplified. Therefore, the relative positions of each component are different from the configuration in FIG. 19 described later. FIG. 6 is a block diagram showing the circulation path shown in FIG. 5. As shown in FIG. 5 and FIG. 6, the first pressure adjustment means 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure adjustment means 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure adjustment means 120 is configured to have a relatively higher control pressure than the second pressure adjustment means 150. In this embodiment, the two pressure adjustment means 120 and 150 are used to achieve circulation within a certain pressure range in the circulation path. Also, the ink is configured to flow through the pressure chamber 12 (ejection element 15) at a flow rate according to the pressure difference between the first pressure adjustment means 120 and the second pressure adjustment means 150. Below, the circulation path in the liquid ejection head 1 and the flow of liquid within the circulation path will be described with reference to Figures 5 and 6. Note that the arrows in each figure indicate the direction in which the liquid flows.

[0046] First, the connection state of each component of the liquid ejection head 1 will be described.

[0047] An external pump 21 that sends liquid contained in an ink tank 2 (FIG. 6) provided outside the liquid ejection head 1 to the liquid ejection head 1 is connected to a circulation unit 54 via a supply tube 59 (FIG. 1). A filter 110 is provided in a flow path (inflow flow path) located upstream of the circulation unit 54. A liquid supply path (inflow flow path) located downstream of the filter 110 is connected to a first valve chamber 121 of a first pressure adjustment means 120. The first valve chamber 121 communicates with a first pressure control chamber 122 via a communication port 191A that can be opened and closed by a valve 190A shown in FIG. 5. The inflow flow path is a flow path through which liquid in an ink tank 2 provided outside the liquid ejection head 1 flows into the liquid ejection head 1 to supply the liquid to the pressure chamber 12.

[0048] The first pressure control chamber 122 is connected to the supply flow path 130, the bypass flow path 160, and the pump outlet flow path 180 of the circulation pump 500. The supply flow path 130 is connected to the common supply flow path 18 via the liquid supply port provided in the discharge module 300. The bypass flow path 160 is connected to a second valve chamber 151 provided in the second pressure adjustment means 150. The second valve chamber 151 is connected to the second pressure control chamber 152 via a communication port 191B that is opened and closed by a valve 190B shown in FIG. 5. Note that FIGS. 5 and 6 show an example in which one end of the bypass flow path 160 is connected to the first pressure control chamber 122 of the first pressure adjustment means 120, and the other end of the bypass flow path 160 is connected to the second valve chamber 151 of the second pressure adjustment means 150. Note that one end of the bypass flow path 160 may be connected to the supply flow path 130, and the other end of the bypass flow path may be connected to the second valve chamber 151.

[0049] The second pressure control chamber 152 is connected to the recovery passage 140. The recovery passage 140 is connected to the common recovery passage 19 via the aforementioned liquid recovery port provided in the ejection module 300. Furthermore, the second pressure control chamber 152 is connected to the circulation pump 500 via a pump inlet passage 170. In addition, in FIG. 5, 170a denotes the inlet of the pump inlet passage 170.

[0050] Next, a description will be given of the flow of liquid in the liquid ejection head 1 having the above configuration. As shown in Fig. 6, the liquid contained in the ink tank 2 is pressurized by an external pump 21 provided in the liquid ejection device 50, and is supplied to the circulation unit 54 of the liquid ejection head 1 as a positive pressure liquid flow.

[0051] The liquid supplied to the circulation unit 54 passes through the filter 110 to remove foreign matter such as dust and air bubbles, and then flows into the first valve chamber 121 provided in the first pressure adjustment means 120. The pressure of the liquid drops due to pressure loss when passing through the filter 110, but the pressure of the liquid at this stage is positive. Thereafter, when the valve 190A is in the open state, the liquid that has flowed into the first valve chamber 121 passes through the communication port 191A and flows into the first pressure control chamber 122. Due to the pressure loss when passing through the communication port 191A, the liquid that has flowed into the first pressure control chamber 122 switches from positive pressure to negative pressure.

[0052] Next, the flow of liquid in the circulation path will be described. The circulation pump 500 operates to pump the liquid sucked from the pump inlet flow path 170 on the upstream side to the pump outlet flow path 180 on the downstream side. Therefore, when the pump is driven, the liquid supplied to the first pressure control chamber 122 flows into the supply flow path 130 and the bypass flow path 160 together with the liquid sent from the pump outlet flow path 180. Note that, although details will be described later, in this embodiment, a piezoelectric diaphragm pump using a piezoelectric element attached to a diaphragm as a driving source is used as a circulation pump capable of sending liquid. The piezoelectric diaphragm pump is a pump that changes the volume of the pump chamber by inputting a driving voltage to a piezoelectric element, and sends liquid by alternately moving two check valves due to pressure fluctuations.

[0053] The liquid that has flowed into the supply flow channel 130 flows from the liquid supply port of the ejection module 300 through the common supply flow channel 18 into the pressure chamber 12, and some of the liquid is ejected from the ejection port 13 by driving (heat generation) the ejection element 15. The remaining liquid that has not been used for ejection flows through the pressure chamber 12, passes through the common recovery flow channel 19, and then flows into the recovery flow channel 140 connected to the ejection module 300. The liquid that has flowed into the recovery flow channel 140 flows into the second pressure control chamber 152 of the second pressure adjustment means 150.

[0054] On the other hand, the liquid that has flowed from the first pressure control chamber 122 into the bypass flow passage 160 flows into the second valve chamber 151, and then passes through the communication port 191B and flows into the second pressure control chamber 152. The liquid that has flowed into the second pressure control chamber 152 via the bypass flow passage 160 and the liquid recovered from the recovery flow passage 140 are sucked into the circulation pump 500 through the pump inlet flow passage 170 by driving the circulation pump 500. The liquid sucked into the circulation pump 500 is sent to the pump outlet flow passage 180 and flows into the first pressure control chamber 122 again. Thereafter, the liquid that has flowed into the second pressure control chamber 152 from the first pressure control chamber 122 via the supply flow passage 130 through the discharge module 300 and the liquid that has flowed into the second pressure control chamber 152 via the bypass flow passage 160 flow into the circulation pump 500. Then, the liquid is sent from the circulation pump 500 to the first pressure control chamber 122. In this manner, the liquid is circulated in the circulation path.

[0055] As described above, in this embodiment, the circulation pump 500 can circulate the liquid along the circulation path formed in the liquid ejection head 1. This makes it possible to suppress thickening of the liquid and accumulation of sedimentation components of the colorant liquid in the ejection module 300, and makes it possible to maintain good fluidity of the liquid in the ejection module 300 and ejection characteristics at the ejection port.

[0056] Moreover, the circulation path in this embodiment is configured to be completed within the liquid ejection head 1. Therefore, the length of the circulation path can be significantly shortened and the volume within the circulation path can be reduced compared to when the liquid is circulated between the ink tank 2 provided outside the liquid ejection head and the liquid ejection head 1. This makes it possible to circulate the liquid using a small circulation pump such as a piezoelectric pump.

[0057] Furthermore, the connection flow path between the liquid ejection head 1 and the ink tank 2 is configured to include only a flow path for supplying liquid. In other words, a configuration is adopted in which a flow path for recovering liquid from the liquid ejection head 1 to the ink tank 2 is not required. Therefore, only a tube for supplying liquid is required to connect the ink tank 2 and the liquid ejection head 1, and a tube for recovering liquid is not required. Therefore, the inside of the liquid ejection device 50 can be simplified with a reduced number of tubes, and the entire device can be made compact. Furthermore, by reducing the number of tubes, it is possible to reduce the pressure fluctuation of the liquid caused by the oscillation of the tubes accompanying the main scanning of the liquid ejection head 1. In addition, the oscillation of the tubes during the main scanning of the liquid ejection head 1 becomes a driving load of the carriage motor that drives the carriage 60. Therefore, by reducing the number of tubes, the driving load of the carriage motor is reduced, and it is possible to simplify the main scanning mechanism including the carriage motor and the like. Furthermore, since it is not necessary to recover liquid from the liquid ejection head to the ink tank, the external pump 21 can also be made compact. In this way, according to this embodiment, the liquid ejection device 50 can be configured to be circulatable, while achieving miniaturization and cost reduction.

[0058] The flow rate at which the reaction solution is circulated (circulation flow rate) is preferably 1.0 mL / min to 10.0 mL / min, and more preferably 2.0 mL / min to 5.0 mL / min.

[0059] <Pressure Adjustment Means> FIG. 7 is a diagram showing an example of a pressure adjustment means. The configuration and operation of the pressure adjustment means (first pressure adjustment means 120, second pressure adjustment means 150) built into the above-mentioned liquid ejection head 1 will be described in more detail with reference to FIG. 7. The first pressure adjustment means 120 and the second pressure adjustment means 150 have substantially the same configuration. For this reason, the following description will be given taking the first pressure adjustment means 120 as an example, and the second pressure adjustment means 150 will only be described with the reference numerals of the parts corresponding to the first pressure adjustment means in FIG. 7. In the case of the second pressure adjustment means 150, the first valve chamber 121 described below will be read as the second valve chamber 151, and the first pressure control chamber 122 will be read as the second pressure control chamber 152.

[0060] The first pressure adjustment means 120 has a first valve chamber 121 and a first pressure control chamber 122 formed in a cylindrical housing 125. The first valve chamber 121 and the first pressure control chamber 122 are separated by a partition wall 123 provided in the cylindrical housing 125. However, the first valve chamber 121 communicates with the first pressure control chamber 122 via a communication port 191 formed in the partition wall 123. The first valve chamber 121 is provided with a valve 190 that switches between communication and blocking between the first valve chamber 121 and the first pressure control chamber 122 at the communication port 191. The valve 190 is held at a position facing the communication port 191 by a valve spring 200, and has a configuration that allows it to come into close contact with the partition wall 123 by the biasing force of the valve spring 200. When the valve 190 comes into close contact with the partition wall 123, the flow of liquid through the communication port 191 is blocked. In order to increase the close contact with the partition wall 123, it is preferable that the portion of the valve 190 that comes into contact with the partition wall 123 is made of an elastic material. A valve shaft 190a that is inserted into the communication port 191 protrudes from the center of the valve 190. By pressing this valve shaft 190a against the biasing force of a valve spring 200, the valve 190 moves away from the partition wall 123, allowing the flow of liquid through the communication port 191. Hereinafter, the state in which the valve 190 blocks the flow of liquid through the communication port 191 will be referred to as the "closed state", and the state in which the flow of liquid through the communication port 191 is allowed will be referred to as the "open state".

[0061] The opening of the cylindrical housing 125 is closed by the flexible member 230 and the pressure plate 210. The first pressure control chamber 122 is formed by the flexible member 230, the pressure plate 210, the peripheral wall of the housing 125, and the partition wall 123. The pressure plate 210 is configured to be displaceable in accordance with the displacement of the flexible member 230. The materials of the pressure plate 210 and the flexible member 230 are not particularly limited, but for example, the pressure plate 210 can be configured from a resin molded part, and the flexible member 230 can be configured from a resin film. In this case, the pressure plate 210 can be fixed to the flexible member 230 by thermal welding.

[0062] A pressure adjustment spring 220 (biasing member) is provided between the pressure plate 210 and the partition wall 123. The pressure plate 210 and the flexible member 230 are biased by the biasing force of the pressure adjustment spring 220 in a direction in which the internal volume of the first pressure control chamber 122 expands, as shown in FIG. 7(a). When the pressure in the first pressure control chamber 122 decreases, the pressure plate 210 and the flexible member 230 are displaced in a direction in which the internal volume of the first pressure control chamber 122 decreases against the pressure of the pressure adjustment spring 220. When the internal volume of the first pressure control chamber 122 decreases to a certain amount, the pressure plate 210 abuts against the valve shaft 190a of the valve 190. When the internal volume of the first pressure control chamber 122 further decreases thereafter, the valve 190 moves together with the valve shaft 190a against the biasing force of the valve spring 200, and moves away from the partition wall 123. As a result, the communication port 191 is in an open state (the state shown in FIG. 7(b)).

[0063] In this embodiment, the connection in the circulation path is set so that the pressure in the first valve chamber 121 when the communication port 191 is in the open state is higher than the pressure in the first pressure control chamber 122. As a result, when the communication port 191 is in the open state, liquid flows from the first valve chamber 121 to the first pressure control chamber 122. This liquid inflow displaces the flexible member 230 and the pressure plate 210 in a direction in which the internal volume of the first pressure control chamber 122 increases. As a result, the pressure plate 210 moves away from the valve shaft 190a of the valve 190, and the valve 190 is brought into close contact with the partition wall 123 by the biasing force of the valve spring 200, and the communication port 191 is in the closed state (the state of FIG. 7(c)).

[0064] In this manner, in the first pressure adjustment means 120 of this embodiment, when the pressure in the first pressure control chamber 122 decreases to a certain pressure or below (for example, when the negative pressure becomes stronger), liquid flows in from the first valve chamber 121 via the communication port 191. This prevents the pressure in the first pressure control chamber 122 from decreasing any further. Therefore, the pressure in the first pressure control chamber 122 is controlled to be kept within a certain range.

[0065] Next, the pressure in the first pressure control chamber 122 will be described in more detail.

[0066] Consider a state in which the flexible member 230 and the pressure plate 210 are displaced in response to the pressure in the first pressure control chamber 122 as described above, and the pressure plate 210 comes into contact with the valve shaft 190a, opening the communication port 191 (the state shown in FIG. 7(b)). At this time, the relationship of the forces acting on the pressure plate 210 is expressed by the following equation 1. P2×S2+F2+(P1-P2)×S1+F1=0...Equation 1 Furthermore, rearranging Equation 1 for P2 gives P2 = -(F1 + F2 + P1 × S1) / (S2-S1) Equation 2. P1: Pressure (gauge pressure) of the first valve chamber 121 P2: Pressure (gauge pressure) of the first pressure control chamber 122 F1: Valve spring force 200 F2: Spring force of the pressure adjusting spring 220 S1: Pressure receiving area of ​​valve 190 S2: Pressure receiving area of ​​the pressure plate 210 Here, the spring force F1 of the valve spring 200 and the spring force F2 of the pressure adjustment spring 220 are positive (leftward in FIG. 7) in the direction pressing the valve 190 and the pressure plate 210. In addition, the pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122 are configured so that P1 satisfies the relationship P1≧P2.

[0067] The pressure P2 in the first pressure control chamber 122 when the communication port 191 is in the open state is determined by formula 2, and when the communication port 191 is in the open state, due to the relationship P1≧P2 being configured, liquid flows from the first valve chamber 121 into the first pressure control chamber 122. As a result, the pressure P2 in the first pressure control chamber 122 does not decrease any further, and P2 is maintained within a certain pressure range.

[0068] On the other hand, as shown in FIG. 7(c), when the pressure plate 210 is not in contact with the valve shaft 190a and the communication port 191 is closed, the relationship of the forces acting on the pressure plate 210 is expressed by Equation 3. P3×S3+F3=0...Equation 3 Now, rearrange Equation 3 for P3 as follows: P3 = -F3 / S3...Equation 4. F3: The spring force of the pressure adjusting spring 220 when the pressure plate 210 and the valve shaft 190a are not in contact with each other P3: pressure (gauge pressure) in the first pressure control chamber 122 when the pressure plate 210 and the valve shaft 190a are not in contact with each other S3: The pressure-receiving area of ​​the pressure plate 210 when the pressure plate 210 and the valve 190 are not in contact with each other Here, FIG. 7(c) shows a state in which the pressure plate 210 and the flexible member 230 are displaced to the right side of the figure to the limit of their displacement. The pressure P3 in the first pressure control chamber 122, the spring force F3 of the pressure adjustment spring 220, and the pressure receiving area S3 of the pressure plate 210 change according to the amount of displacement while the pressure plate 210 and the flexible member 230 are displaced to the state of FIG. 7(c). Specifically, when the pressure plate 210 and the flexible member 230 are in the right direction in FIG. 7 compared to FIG. 7(c), the pressure receiving area S3 of the pressure plate 210 becomes smaller, and the spring force F3 of the pressure adjustment spring 220 becomes larger. As a result, the pressure P3 in the first pressure control chamber 122 becomes smaller according to the relationship of Equation 4. Therefore, according to Equation 2 and Equation 4, the pressure in the first pressure control chamber 122 gradually increases from the state of FIG. 7(b) to the state of FIG. 7(c) (i.e., the negative pressure becomes weaker and approaches the positive pressure side). That is, from a state in which the communication port 191 is open, the pressure plate 210 and the flexible member 230 gradually displace to the left, and the pressure in the first pressure control chamber 122 gradually increases until the internal volume of the first pressure control chamber 122 finally reaches its limit of displacement. In other words, the negative pressure weakens.

[0069] <Circulation pump> Next, the configuration and operation of the circulation pump 500 built into the above-mentioned liquid ejection head 1 will be described in detail with reference to FIGS.

[0070] FIG. 8 is an external perspective view of the circulation pump 500. FIG. 8(a) is an external perspective view showing the front side of the circulation pump 500, and FIG. 8(b) is an external perspective view showing the rear side of the circulation pump 500. The outer shell of the circulation pump 500 is composed of a pump housing 505 and a cover 507 fixed to the pump housing 505. The pump housing 505 is composed of a housing body 505a and a flow path connecting member 505b adhesively fixed to the outer surface of the housing body 505a. The housing body 505a and the flow path connecting member 505b each have a pair of through holes communicating with each other at two different positions. The pair of through holes provided at one position forms a pump supply hole 501, and the pair of through holes provided at the other position forms a pump discharge hole 502. The pump supply hole 501 is connected to the pump inlet flow path 170 connected to the second pressure control chamber 152, and the pump discharge hole 502 is connected to the pump outlet flow path 180 connected to the first pressure control chamber 122. The liquid supplied from pump supply hole 501 passes through a pump chamber 503 (see FIG. 9) described below, and is discharged from pump discharge hole 502.

[0071] FIG. 9 is a cross-sectional view of the circulating pump 500 shown in FIG. 8(a) taken along line IX-IX. A diaphragm 506 is joined to the inner surface of a pump housing 505, and a pump chamber 503 is formed between the diaphragm 506 and a recess formed on the inner surface of the pump housing 505. The pump chamber 503 communicates with a pump supply hole 501 and a pump discharge hole 502 formed in the pump housing 505. A check valve 504a is provided in the middle of the pump supply hole 501, and a check valve 504b is provided in the middle of the pump discharge hole 502. Specifically, the check valve 504a is arranged so that a part of the check valve 504a can move leftward in the figure in a space 512a formed in the middle of the pump supply hole 501. A part of the check valve 504b is arranged so that it can move rightward in the figure in a space 512b formed in the middle of the pump discharge hole 502.

[0072] When diaphragm 506 is displaced to increase the volume of pump chamber 503 and reduce the pressure in pump chamber 503, check valve 504a moves away from the opening of pump supply hole 501 in space 512a (i.e., moves to the left in the figure). When check valve 504a moves away from the opening of pump supply hole 501 in space 512a, the check valve 504a enters an open state that allows the flow of liquid through pump supply hole 501. When diaphragm 506 is displaced to decrease the volume of pump chamber 503 and reduce the pressure in pump chamber 503, check valve 504a comes into close contact with the wall surface surrounding the opening of pump supply hole 501. As a result, the check valve 504a enters a closed state that blocks the flow of liquid through pump supply hole 501.

[0073] On the other hand, when the pump chamber 503 is depressurized, the check valve 504b comes into close contact with the wall surface surrounding the opening of the pump housing 505 and enters a closed state in which it blocks the flow of liquid through the pump discharge hole 502. When the pump chamber 503 is pressurized, the check valve 504b moves away from the opening of the pump housing 505 toward the space 512b (i.e., moves to the right in the figure), thereby allowing the flow of liquid through the pump discharge hole 502.

[0074] The material of each of the check valves 504a and 504b may be any material that can deform in response to the pressure in the pump chamber 503, and may be, for example, an elastic member such as EPDM or elastomer, or a film or thin plate such as polypropylene, but is not limited to these.

[0075] As described above, pump chamber 503 is formed by joining pump housing 505 and diaphragm 506. Therefore, the pressure in pump chamber 503 changes as diaphragm 506 deforms. For example, when diaphragm 506 is displaced toward pump housing 505 (displaced to the right in the figure) and the volume of pump chamber 503 decreases, the pressure in pump chamber 503 increases. As a result, check valve 504b arranged opposite pump discharge hole 502 opens, and liquid in pump chamber 503 is discharged. At this time, check valve 504a arranged opposite pump supply hole 501 is in close contact with the wall surface surrounding pump supply hole 501, so that backflow of liquid from pump chamber 503 to pump supply hole 501 is suppressed.

[0076] Conversely, when the diaphragm 506 is displaced in the direction in which the pump chamber 503 expands, the pressure in the pump chamber 503 decreases. As a result, the check valve 504a arranged opposite the pump supply hole 501 opens, and liquid is supplied to the pump chamber 503. At this time, the check valve 504b arranged in the pump discharge hole 502 comes into close contact with the wall surface surrounding the opening formed in the pump housing 505 to close the opening. As a result, backflow of liquid from the pump discharge hole 502 to the pump chamber 503 is suppressed.

[0077] In this way, in the circulation pump 500, the diaphragm 506 deforms to change the pressure in the pump chamber 503, thereby suctioning and discharging liquid. At this time, if bubbles are mixed into the pump chamber 503, even if the diaphragm 506 is displaced, the pressure change in the pump chamber 503 is reduced due to the expansion and contraction of the bubbles, and the amount of liquid delivered decreases. Therefore, the pump chamber 503 is arranged parallel to gravity so that bubbles mixed into the pump chamber 503 can easily gather above the pump chamber 503, and the pump discharge hole 502 is arranged above the center of the pump chamber 503. This makes it possible to improve the discharge of bubbles in the pump and stabilize the flow rate.

[0078] <Liquid flow inside the liquid ejection head> FIG. 10 is a diagram for explaining the flow of liquid in the liquid ejection head. The circulation of liquid in the liquid ejection head 1 will be explained with reference to FIG. 10. In order to more clearly explain the liquid circulation path, the relative positions of each component (first pressure adjustment means 120, second pressure adjustment means 150, circulation pump 500, etc.) in FIG. 10 are simplified. Therefore, the relative positions of each component are different from the configuration in FIG. 19 described later. FIG. 10(a) is a schematic diagram showing the flow of liquid when a recording operation is performed in which liquid is ejected from the ejection port 13 to perform recording. Note that the arrows in the figure indicate the flow of liquid. In this embodiment, when a recording operation is performed, both the external pump 21 and the circulation pump 500 start to be driven. Note that the external pump 21 and the circulation pump 500 may be driven when no recording operation is performed. In addition, the external pump 21 and the circulation pump 500 do not need to be driven in conjunction with each other, and may be driven independently.

[0079] During the recording operation, the circulation pump 500 is ON (driven), and the liquid flowing out from the first pressure control chamber 122 flows into the supply flow path 130 and the bypass flow path 160. The liquid that flows into the supply flow path 130 passes through the ejection module 300, then flows into the recovery flow path 140, and is then supplied to the second pressure control chamber 152.

[0080] On the other hand, the liquid that has flowed into the bypass flow path 160 from the first pressure control chamber 122 flows into the second pressure control chamber 152 via the second valve chamber 151. The liquid that has flowed into the second pressure control chamber 152 passes through the pump inlet flow path 170, the circulation pump 500, and the pump outlet flow path 180, and then flows into the first pressure control chamber 122 again. At this time, the control pressure by the first valve chamber 121 is set higher than the control pressure of the first pressure control chamber 122 based on the relationship of the above-mentioned formula 2. Therefore, the liquid in the first pressure control chamber 122 is supplied to the discharge module 300 again via the supply flow path 130 without flowing into the first valve chamber 121. The liquid that has flowed into the discharge module 300 flows into the first pressure control chamber 122 again via the recovery flow path 140, the second pressure control chamber 152, the pump inlet flow path 170, the circulation pump 500, and the pump outlet flow path 180. As described above, the liquid circulation that is completed within the liquid discharge head 1 is performed.

[0081] In the above liquid circulation, the circulation amount (flow rate) of the liquid in the discharge module 300 is determined by the difference in the control pressure between the first pressure control chamber 122 and the second pressure control chamber 152. This pressure difference is set so as to be a circulation amount capable of suppressing thickening of the liquid near the discharge port in the discharge module 300. In addition, the liquid consumed by the recording is supplied from the ink tank 2 to the first pressure control chamber 122 via the filter 110 and the first valve chamber 121. The mechanism by which the consumed liquid is supplied will be described in detail. By reducing the liquid from the circulation path by the amount of the liquid consumed by the recording, the pressure in the first pressure control chamber is reduced, and as a result, the liquid in the first pressure control chamber 122 is also reduced. With the reduction in the liquid in the first pressure control chamber 122, the internal volume of the first pressure control chamber 122 is reduced. With this reduction in the internal volume of the first pressure control chamber 122, the communication port 191A is opened, and the liquid is supplied from the first valve chamber 121 to the first pressure control chamber 122. This supplied liquid experiences a pressure loss when passing from first valve chamber 121 through communication port 191A, and as it flows into first pressure control chamber 122, the positive pressure liquid switches to a negative pressure state. As liquid flows from first valve chamber 121 into first pressure control chamber 122, the pressure inside the first pressure control chamber increases, increasing the internal volume of the first pressure control chamber and closing communication port 191A. In this way, communication port 191A alternates between an open state and a closed state depending on the consumption of liquid. If no liquid is consumed, communication port 191A is maintained in a closed state.

[0082] FIG. 10B is a schematic diagram showing the flow of liquid immediately after the recording operation is completed and the circulation pump 500 is turned off (stopped). When the recording operation is completed and the circulation pump 500 is turned off, the pressures of the first pressure control chamber 122 and the second pressure control chamber 152 are both at the control pressure during the recording operation. Therefore, the movement of liquid occurs according to the pressure difference between the pressures of the first pressure control chamber 122 and the second pressure control chamber 152 as shown in FIG. 10B. Specifically, the flow of liquid continues to occur in which the liquid is supplied from the first pressure control chamber 122 to the ejection module 300 via the supply flow path 130, and then reaches the second pressure control chamber 152 via the recovery flow path 140. The flow of liquid also continues to occur from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass flow path 160 and the second valve chamber 151.

[0083] The amount of liquid that moves from the first pressure control chamber 122 to the second pressure control chamber 152 by these liquid flows is supplied to the first pressure control chamber 122 from the ink tank 2 via the filter 110 and the first valve chamber 121. Therefore, the content volume in the first pressure control chamber 122 is kept constant. From the relationship of the above-mentioned formula 2, when the content volume in the first pressure control chamber 122 is constant, the spring force F1 of the valve spring 200, the spring force F2 of the pressure adjustment spring 220, the pressure receiving area S1 of the valve 190, and the pressure receiving area S2 of the pressure plate 210 are kept constant. Therefore, the pressure in the first pressure control chamber 122 is determined according to the change in the pressure (gauge pressure) P1 in the first valve chamber 121. Therefore, when there is no change in the pressure P1 in the first valve chamber 121, the pressure P2 in the first pressure control chamber 122 is kept at the same pressure as the control pressure during the recording operation.

[0084] On the other hand, the pressure of the second pressure control chamber 152 changes over time according to the change in the content volume caused by the inflow of liquid from the first pressure control chamber 122. Specifically, from the state of FIG. 10(b) until the communication port 191 is closed and the second valve chamber 151 and the second pressure control chamber 152 are not in communication with each other as shown in FIG. 10(c), the pressure of the second pressure control chamber 152 changes according to Equation 2. Thereafter, the pressure plate 210 and the valve shaft 190a are not in contact with each other and the communication port 191 is closed. Then, as shown in FIG. 10(d), liquid flows from the recovery passage 140 into the second pressure control chamber 152. This inflow of liquid displaces the pressure plate 210 and the flexible member 230, and the pressure of the second pressure control chamber 152 changes according to Equation 4 until the internal volume of the second pressure control chamber 152 reaches its maximum. That is, it rises.

[0085] 10(c), no liquid flows from the first pressure control chamber 122 to the second pressure control chamber 152 via the bypass flow path 160 and the second valve chamber 151. Therefore, after the liquid in the first pressure control chamber 122 is supplied to the discharge module 300 via the supply flow path 130, only a flow occurs to reach the second pressure control chamber 152 via the recovery flow path 140. As described above, the movement of liquid from the first pressure control chamber 122 to the second pressure control chamber 152 occurs according to the pressure difference between the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152. Therefore, when the pressure in the second pressure control chamber 152 becomes equal to the pressure in the first pressure control chamber 122, the movement of liquid stops.

[0086] In addition, in a state where the pressure in the second pressure control chamber 152 is equal to the pressure in the first pressure control chamber 122, the second pressure control chamber 152 expands to a state shown in FIG. 10(d). When the second pressure control chamber 152 expands as shown in FIG. 10(d), a storage portion capable of storing liquid is formed in the second pressure control chamber 152. Note that the time from when the circulation pump 500 is stopped to when the state shown in FIG. 10(d) is transitioned to is about 1 to 2 minutes, which may vary depending on the shape and size of the flow path and the properties of the liquid. When the circulation pump 500 is driven from the state shown in FIG. 10(d) where the liquid is stored in the storage portion, the liquid in the storage portion is supplied to the first pressure control chamber 122 by the circulation pump 500. As a result, the amount of liquid in the first pressure control chamber 122 increases as shown in FIG. 10(e), and the flexible member 230 and the pressure plate 210 are displaced in the expansion direction. Then, when the circulation pump 500 continues to be driven, the state inside the circulation path changes as shown in FIG. 10(a).

[0087] 10(a) is an example of the liquid circulation during the recording operation, but as described above, the liquid may be circulated without the recording operation. Even in this case, the liquid flows as shown in FIGS. 10(a) to 10(e) according to the driving and stopping of the circulating pump 500.

[0088] As described above, in this embodiment, the communication port 191B in the second pressure adjustment means 150 is in an open state when the circulation pump 500 is driven to circulate the liquid, and is in a closed state when the circulation of the liquid stops, but this is not limited to the above example. The control pressure may be set so that the communication port 191B in the second pressure adjustment means 150 is in a closed state even when the circulation pump 500 is driven to circulate the liquid. Hereinafter, the role of the bypass flow path 160 will be specifically described.

[0089] The bypass flow path 160 connecting the first pressure adjustment means 120 and the second pressure adjustment means 150 is provided to prevent the negative pressure generated in the circulation path from being stronger than a predetermined value, for example, from being affected by the discharge module 300. The bypass flow path 160 is also provided to supply liquid to the pressure chamber 12 from both sides of the supply flow path 130 and the recovery flow path 140.

[0090] First, an example will be described in which the bypass flow path 160 is provided to prevent the negative pressure from being stronger than a preset value and thus affecting the discharge module 300. For example, the characteristics (e.g., viscosity) of the liquid may change due to a change in the environmental temperature. When the viscosity of the liquid changes, the pressure loss in the circulation path also changes. For example, when the viscosity of the liquid decreases, the pressure loss in the circulation path decreases. As a result, the flow rate of the circulation pump 500 driven at a constant drive amount increases, and the flow rate through the discharge module 300 increases. On the other hand, since the discharge module 300 is kept at a constant temperature by a temperature adjustment means (not shown, to be described later), the viscosity of the liquid in the discharge module 300 is maintained constant even if the environmental temperature changes. While the viscosity of the liquid in the discharge module 300 does not change, the flow rate of the liquid flowing through the discharge module 300 increases, and the negative pressure in the discharge module 300 increases due to flow resistance. In this way, if the negative pressure in the discharge module 300 becomes stronger than the default value, the meniscus of the discharge port 13 may be destroyed, and external air may be drawn into the circulation path, preventing normal discharge. Even if the meniscus is not destroyed, the negative pressure in the pressure chamber 12 may become stronger than the default value, affecting discharge.

[0091] For this reason, in this embodiment, the bypass flow path 160 is formed in the circulation path. By providing the bypass flow path 160, when the negative pressure becomes stronger than a preset value, liquid also flows through the bypass flow path 160, so that the pressure of the discharge module 300 can be kept constant. Therefore, for example, the communication port 191B in the second pressure adjustment means 150 may be configured with a control pressure that maintains the closed state even when the circulation pump 500 is being driven. Then, the control pressure in the second pressure adjustment means may be set so that the communication port 191 in the second pressure adjustment means 150 is in an open state when the negative pressure becomes stronger than a preset value. In other words, if the meniscus does not collapse even when the flow rate of the pump is changed due to a viscosity change such as an environmental change, or if a predetermined negative pressure is maintained, the communication port 191B may be in a closed state when the circulation pump 500 is driven.

[0092] Next, an example will be described in which the bypass flow path 160 is provided to supply liquid to the pressure chamber 12 from both the supply flow path 130 and the recovery flow path 140. Pressure fluctuations in the circulation path can also occur due to the ejection operation of the ejection element 15. This is because a force that draws liquid into the pressure chamber is generated by the ejection operation.

[0093] Hereinafter, it will be explained that when high duty recording is continued, the liquid supplied to the pressure chamber 12 is supplied to both the supply flow path 130 side and the recovery flow path 140 side. Note that the definition of duty can change depending on various conditions, but here, the state in which one 4pl ink droplet is recorded on a 1200dpi grid is treated as 100%. High duty recording means, for example, recording at a duty of 100%.

[0094] If recording at a high duty continues, the amount of liquid flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow path 140 decreases. On the other hand, since the circulation pump 500 discharges liquid at a constant rate, the balance between the inflow and outflow in the second pressure control chamber 152 is lost, the liquid in the second pressure control chamber 152 decreases, the negative pressure in the second pressure control chamber 152 becomes stronger, and the second pressure control chamber 152 shrinks. Then, as the negative pressure in the second pressure control chamber 152 becomes stronger, the inflow amount of liquid flowing into the second pressure control chamber 152 through the bypass flow path 160 increases, and the second pressure control chamber 152 becomes stable with the inflow and outflow balanced. As a result, the negative pressure in the second pressure control chamber 152 becomes stronger according to the duty. Furthermore, as described above, when the circulation pump 500 is driven, in a configuration in which the communication port 191B is in a closed state, the communication port 191B opens depending on the duty, and liquid flows from the bypass flow path 160 into the second pressure control chamber 152.

[0095] Then, when recording at a higher duty is continued, the amount of liquid flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow passage 140 decreases, and instead the amount of liquid flowing into the second pressure control chamber 152 from the communication port 191B via the bypass flow passage 160 increases. As this state progresses further, the amount of liquid flowing from the pressure chamber 12 into the second pressure control chamber 152 through the recovery flow passage 140 becomes zero, and all the liquid flowing out to the circulation pump 500 becomes the liquid flowing in from the communication port 191B. As this state progresses further, this time the liquid flows back from the second pressure control chamber 152 into the pressure chamber 12 through the recovery flow passage 140. In this state, the liquid flowing out from the second pressure control chamber 152 to the circulation pump 500 and the liquid flowing out to the pressure chamber 12 flow into the second pressure control chamber 152 from the communication port 191B through the bypass flow passage 160. In this case, the pressure chamber 12 is filled with the liquid in the supply flow passage 130 and the liquid in the recovery flow passage 140, and is discharged.

[0096] The backflow of liquid that occurs when the printing duty is high is a phenomenon that occurs due to the provision of the bypass flow path 160. In addition, in the above, an example has been described in which the communication port 191B in the second pressure adjustment means is opened in response to the backflow of liquid, but backflow of liquid may also occur when the communication port 191B in the second pressure adjustment means is open. Even in a configuration that does not include the second pressure adjustment means, the provision of the bypass flow path 160 may cause the backflow of liquid.

[0097] <Configuration of the discharge unit> FIG. 11 is a schematic diagram showing a circulation path for one color of liquid in the discharge unit 3 of this embodiment. FIG. 11(a) is an exploded perspective view of the discharge unit 3 seen from the first support member 4 side, and FIG. 11(b) is an exploded perspective view of the discharge unit 3 seen from the discharge module 300 side. The arrows indicated by IN and OUT in the figure indicate the flow of liquid, and the flow of liquid for only one color will be described, but the other colors flow in the same manner. Also, the second support member 7 and the electric wiring member 5 are omitted in FIG. 11, and are also omitted in the following description of the configuration of the discharge unit. Also, the first support member 4 in FIG. 11(a) shows a cross section taken along line XI-XI in FIG. 3. The discharge module 300 includes a discharge element substrate 340 and an aperture plate 330. FIG. 12 is a diagram showing the aperture plate 330, and FIG. 13 is a diagram showing the discharge element substrate 340.

[0098] The discharge unit 3 is supplied with liquid from the circulation unit 54 via a joint member 8 (see FIG. 3). The path of the liquid from when the liquid passes through the joint member 8 until when the liquid returns to the joint member 8 will be described. Note that the joint member 8 will be omitted from the following drawings.

[0099] The discharge module 300 includes a discharge element substrate 340, which is a silicon substrate 310, and an aperture plate 330, and further includes a discharge port forming member 320. The discharge element substrate 340, the aperture plate 330, and the discharge port forming member 320 are overlapped and joined together so that the flow paths of the liquids communicate with each other to form the discharge module 300, which is supported by a first support member 4. The discharge module 300 is supported by the first support member 4 to form a discharge unit 3. The discharge element substrate 340 includes a discharge port forming member 320, which includes a plurality of discharge port rows in which a plurality of discharge ports 13 are arranged in a row, and discharges a portion of the liquid supplied through the liquid flow path in the discharge module 300 from the discharge port 13. The liquid that is not discharged is collected through the liquid flow path in the discharge module 300.

[0100] As shown in Figs. 11 and 12, the aperture plate 330 includes a plurality of aligned liquid supply ports 311 and a plurality of aligned liquid recovery ports 312. As shown in Figs. 13 and 14, the ejection element substrate 340 includes a plurality of aligned supply connection channels 323 and a plurality of aligned recovery connection channels 324. The ejection element substrate 340 further includes a common supply channel 18 communicating with the plurality of supply connection channels 323 and a common recovery channel 19 communicating with the plurality of recovery connection channels 324. The flow channels in the ejection unit 3 are formed by communicating a liquid supply channel 48 and a liquid recovery channel 49 (see Fig. 3) provided in the first support member 4 with a flow channel provided in the ejection module 300. The support member supply port 211 is a cross-sectional opening that forms the liquid supply channel 48, and the support member recovery port 212 is a cross-sectional opening that forms the liquid recovery channel 49.

[0101] The liquid supplied to the discharge unit 3 is supplied to the liquid supply flow path 48 (see FIG. 3(a)) of the first support member 4 from the circulation unit 54 (see FIG. 3(a)). The liquid that flows through the support member supply port 211 in the liquid supply flow path 48 is supplied to the common supply flow path 18 of the discharge element substrate 340 via the liquid supply flow path 48 (see FIG. 3(a)) and the liquid supply port 311 of the opening plate 330, and enters the supply connection flow path 323. This is the supply side flow path. Thereafter, the liquid flows through the pressure chamber 12 (see FIG. 3(b)) of the discharge port forming member 320 to the recovery connection flow path 324 of the recovery side flow path. The flow of the liquid in the pressure chamber 12 will be described in detail later.

[0102] In the recovery side flow path, the liquid that has entered the recovery connection flow path 324 flows into the common recovery flow path 19. The liquid then flows from the common recovery flow path 19 through the liquid recovery port 312 of the opening plate 330 to the liquid recovery flow path 49 of the first support member 4, and is recovered into the circulation unit 54 via the support member recovery port 212.

[0103] The area of ​​the aperture plate 330 without the liquid supply port 311 or the liquid recovery port 312 corresponds to the area for separating the support member supply port 211 and the support member recovery port 212 in the first support member 4. Moreover, this area does not have an opening in the first support member 4 either. Such an area is used as an adhesion area when the discharge module 300 and the first support member 4 are adhered to each other.

[0104] In FIG. 12, the aperture plate 330 has a plurality of rows of apertures arranged in the X direction, and the supply (IN) apertures and the recovery (OUT) apertures are arranged alternately in the Y direction so as to be shifted by half a pitch in the X direction. In FIG. 13, the discharge element substrate 340 has a common supply flow path 18 communicating with a plurality of supply connection flow paths 323 arranged in the Y direction, and a common recovery flow path 19 communicating with a plurality of recovery connection flow paths 324 arranged in the Y direction, arranged alternately in the X direction. The common supply flow paths 18 and the common recovery flow path 19 are separated for each type of liquid, and further, the number of common supply flow paths 18 and common recovery flow paths 19 is determined according to the number of discharge port rows for each type of liquid. In addition, the supply connection flow paths 323 and the recovery connection flow paths 324 are also arranged in the number corresponding to the discharge ports 13. It is not necessarily required that there is a one-to-one correspondence, and one supply connection flow path 323 and one recovery connection flow path 324 may correspond to a plurality of discharge ports 13.

[0105] Such an aperture plate 330 and an ejection element substrate 340 are overlapped and joined so that the flow paths of each liquid are connected to form an ejection module 300, and by being supported by the first support member 4, a liquid flow path is formed that has a supply flow path and a recovery flow path as described above.

[0106] Figures 14(a) to (c) are cross-sectional views showing the liquid flow in different parts of the discharge unit 3. Figure 14(a) is a cross-section shown at XIVa-XIVa in Figure 11(a) and shows a cross-section of a part where the liquid supply channel 48 and the liquid supply port 311 in the discharge unit 3 communicate with each other. Also, Figure 14(b) is a cross-section shown at XIVb-XIVb in Figure 11(a) and shows a cross-section of a part where the liquid recovery channel 49 and the liquid recovery port 312 in the discharge unit 3 communicate with each other. Also, Figure 14(c) is a cross-section shown at XIVc-XIVc in Figure 11(a) and shows a cross-section of a part where the liquid supply port 311 and the liquid recovery port 312 do not communicate with the channel of the first support member 4.

[0107] In the supply flow path for supplying the liquid, as shown in FIG. 14(a), the liquid is supplied from a portion where the liquid supply flow path 48 of the first support member 4 and the liquid supply port 311 of the aperture plate 330 overlap and communicate with each other. In the recovery flow path for recovering the liquid, as shown in FIG. 14(b), the liquid is recovered from a portion where the liquid recovery flow path 49 of the first support member 4 and the liquid recovery port 312 of the aperture plate 330 overlap and communicate with each other. In addition, as shown in FIG. 14(c), in the discharge unit 3, there is also a region where the aperture plate 330 does not have an aperture. In such a region, the liquid is not supplied or recovered between the discharge element substrate 340 and the first support member 4. As shown in FIG. 14(a), the liquid is supplied in the region where the liquid supply port 311 is provided, and as shown in FIG. 14(b), the liquid is recovered in the region where the liquid recovery port 312 is provided. Note that, in the present embodiment, the configuration using the aperture plate 330 has been described as an example, but a form without using the aperture plate 330 may be used. For example, a configuration may be used in which flow paths corresponding to the liquid supply flow path 48 and the liquid recovery flow path 49 are formed in the first support member 4, and the ejection element substrate 340 is joined to the first support member 4.

[0108] 15(a) and 15(b) are cross-sectional views showing the vicinity of the ejection port 13 in the ejection module 300, and FIG. 16 is a cross-sectional view showing an ejection module having a configuration in which the common supply flow path 18 and the common recovery flow path 19 are expanded in the X direction as a comparative example. Note that the thick arrows shown in the common supply flow path 18 and the common recovery flow path 19 in FIG. 15 and FIG. 16 indicate the oscillation of the liquid in a configuration in which a serial type liquid ejection device 50 is used. The liquid supplied to the pressure chamber 12 via the common supply flow path 18 and the supply connection flow path 323 is ejected from the ejection port 13 by driving the ejection element 15. When the ejection element 15 is not driven, the liquid is recovered from the pressure chamber 12 to the common recovery flow path 19 via the recovery connection flow path 324, which is a recovery flow path.

[0109] In a configuration using a serial type liquid ejection device 50, when ejection is performed from the circulating liquid in this manner, the ejection of the liquid is influenced by the oscillation of the liquid in the liquid flow path due to the main scanning of the liquid ejection head 1 to a certain extent. Specifically, the influence of the oscillation of the liquid in the liquid flow path may appear as a difference in the ejection amount of the liquid or a deviation in the ejection direction. As shown in FIG. 16, when the common supply flow path 18 and the common recovery flow path 19 have a cross-sectional shape that is wide in the X direction, which is the main scanning direction, the liquid in the common supply flow path 18 and the common recovery flow path 19 is easily subjected to an inertial force in the main scanning direction, and a large oscillation occurs in the liquid. As a result, there is a risk that the oscillation of the liquid will affect the ejection of the liquid from the ejection port 13. Furthermore, if the common supply flow path 18 and the common recovery flow path 19 are widened in the X direction, the distance between different types of ink will be increased, and the recording efficiency may decrease.

[0110] Therefore, the common supply flow path 18 and the common recovery flow path 19 of this embodiment extend in the Y direction in the cross section shown in FIG. 15, but are also configured to extend in the Z direction perpendicular to the X direction, which is the main scanning direction. With this configuration, the width of each flow path in the main scanning direction of the common supply flow path 18 and the common recovery flow path 19 can be reduced. By reducing the width of each flow path in the main scanning direction of the common supply flow path 18 and the common recovery flow path 19, the swaying of the liquid due to the inertial force (indicated by the thick black arrow in the figure) acting on the liquid in the common supply flow path 18 and the common recovery flow path 19 in the opposite direction to the main scanning direction during the main scanning is reduced. This makes it possible to suppress the effect of the swaying of the liquid on the discharge of the liquid. In addition, by extending the common supply flow path 18 and the common recovery flow path 19 in the Z direction, the cross-sectional area is increased, and the flow path pressure loss is reduced.

[0111] As described above, by reducing the width of each of the common supply flow path 18 and the common recovery flow path 19 in the main scanning direction, the oscillation of the liquid in the common supply flow path 18 and the common recovery flow path 19 during main scanning is reduced, but the oscillation is not eliminated. Therefore, in order to suppress differences in ejection for each type of liquid that may still occur even with the reduced oscillation, in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are configured to be disposed at positions that overlap in the X direction.

[0112] As described above, in this embodiment, the supply connection flow path 323 and the return connection flow path 324 are provided corresponding to the discharge port 13, and the supply connection flow path 323 and the return connection flow path 324 are arranged side by side in the X direction with the discharge port 13 in between. Therefore, there are portions where the common supply flow path 18 and the common return flow path 19 do not overlap in the X direction, and if the corresponding relationship in the X direction between the supply connection flow path 323 and the return connection flow path 324 is lost, this will affect the flow and discharge of liquid in the X direction in the pressure chamber 12. If the influence of the fluctuation of the liquid is added to this, it may further affect the discharge of liquid from each discharge port.

[0113] Therefore, by arranging the common supply flow path 18 and the common recovery flow path 19 at positions where they overlap in the X direction, the liquid fluctuation during main scanning in the common supply flow path 18 and the common recovery flow path 19 becomes approximately equal at any position in the Y direction where the ejection ports 13 are arranged. As a result, the pressure difference between the common supply flow path 18 side and the common recovery flow path 19 side generated in the pressure chamber 12 does not vary greatly, and stable ejection can be performed.

[0114] In addition, in some liquid ejection heads that circulate liquid, the flow path that supplies liquid to the liquid ejection head and the flow path that recovers the liquid are configured as the same flow path, but in this embodiment, the common supply flow path 18 and the common recovery flow path 19 are configured as separate flow paths. The supply connection flow path 323 and the pressure chamber 12 are connected to each other, and the pressure chamber 12 and the recovery connection flow path 324 are connected to each other, and liquid is ejected from the ejection port 13 of the pressure chamber 12. In other words, the pressure chamber 12, which is a path that connects the supply connection flow path 323 and the recovery connection flow path 324, is configured to have the ejection port 13. Therefore, a liquid flow that flows from the supply connection flow path 323 side to the recovery connection flow path 324 side is generated in the pressure chamber 12, and the liquid in the pressure chamber 12 is efficiently circulated. By efficiently circulating the liquid in the pressure chamber 12, the liquid in the pressure chamber 12, which is easily affected by the evaporation of the liquid from the ejection port 13, can be kept fresh.

[0115] Furthermore, since the two flow paths, the common supply flow path 18 and the common recovery flow path 19, are connected to the pressure chamber 12, if it becomes necessary to eject the liquid at a high flow rate, it is possible to supply the liquid from both flow paths. In other words, compared to a configuration in which the supply and recovery of the liquid are configured with only one flow path, the configuration of this embodiment has the advantage that not only can the circulation be performed efficiently, but also that it can accommodate ejection at a high flow rate.

[0116] Furthermore, the common supply flow path 18 and the common recovery flow path 19 are less susceptible to influences due to fluctuations of the liquid when they are disposed close to each other in the X direction. It is preferable that the distance between the flow paths is set to 75 μm to 100 μm.

[0117] Fig. 17 is a diagram showing an ejection element substrate 340 as a comparative example. Note that in Fig. 17, the supply connection flow path 323 and the recovery connection flow path 324 are omitted. Since the liquid that has received thermal energy from the ejection elements 15 in the pressure chambers 12 flows into the common recovery flow path 19, the liquid flows at a relatively high temperature compared to the temperature of the liquid in the common supply flow path 18. At this time, in the comparative example, there is a portion where only the common recovery flow path 19 exists in a part in the X direction of the ejection element substrate 340, such as the α portion surrounded by the dashed line in Fig. 17. In this case, the temperature locally increases in that portion, causing temperature unevenness in the ejection module 300, which may affect ejection.

[0118] A liquid with a relatively low temperature flows through the common supply flow path 18 relative to the common recovery flow path 19. Therefore, when the common supply flow path 18 and the common recovery flow path 19 are adjacent to each other, the temperatures in the common supply flow path 18 and the common recovery flow path 19 are partially offset in the vicinity thereof, suppressing a temperature rise. Therefore, it is preferable that the common supply flow path 18 and the common recovery flow path 19 are adjacent to each other and have approximately the same length, and are positioned so as to overlap each other in the X direction.

[0119] 18(a) and (b) are diagrams showing the flow path configuration of a liquid ejection head 1 compatible with three types of ejection liquid. As shown in FIG. 18(a), the liquid ejection head 1 is provided with a circulation flow path for each type of ink (liquid). The pressure chambers 12 are provided along the X direction, which is the main scanning direction of the liquid ejection head 1. As shown in FIG. 18(b), the common supply flow path 18 and the common recovery flow path 19 are provided along the ejection port row in which the ejection ports 13 are arranged, and extend in the Y direction so as to sandwich the ejection port row between the common supply flow path 18 and the common recovery flow path 19.

[0120] <Connection between the main body and the liquid ejection head> 19 is a schematic diagram showing in more detail the connection state between the ink tank 2 and external pump 21 provided in the main body of the liquid ejection device 50 of this embodiment and the liquid ejection head 1, and the arrangement of the circulation pump, etc. The liquid ejection device 50 of this embodiment has a configuration that allows the liquid ejection head 1 alone to be easily replaced when a malfunction occurs in the liquid ejection head 1. Specifically, it has a liquid connection part 700 that allows the supply tube 59 connected to the external pump 21 to be easily connected and disconnected from the liquid ejection head 1. This makes it possible to easily attach and detach only the liquid ejection head 1 to and from the liquid ejection device 50.

[0121] 19, the liquid connection part 700 has a liquid connector insertion port 53a protruding from the head housing 53 of the liquid ejection head 1, and a cylindrical liquid connector 59a into which the liquid connector insertion port 53a can be inserted. The liquid connector insertion port 53a is fluidly connected to a liquid supply flow path (inflow flow path) formed in the liquid ejection head 1, and is connected to the first pressure adjustment means 120 via the above-mentioned filter 110. In addition, the liquid connector 59a is provided at the tip of a supply tube 59 connected to an external pump 21 that pressurizes and supplies the liquid in the ink tank 2 to the liquid ejection head 1.

[0122] 19, the liquid ejection head 1 can be easily attached, detached, and replaced by the liquid connection part 700. However, if the sealing performance between the liquid connector insertion port 53a and the liquid connector 59a is reduced, there is a risk that the liquid supplied under pressure by the external pump 21 will leak from the liquid connection part 700. If the leaked liquid adheres to the circulation pump 500 or the like, a malfunction may occur in the electrical system. Therefore, in this embodiment, the circulation pump and the like are arranged as follows.

[0123] <Location of circulating pumps, etc.> As shown in FIG. 19, in this embodiment, in order to prevent the liquid leaking from the liquid connection part 700 from adhering to the circulation pump 500, the circulation pump 500 is disposed above the liquid connection part 700 in the direction of gravity. That is, the circulation pump 500 is disposed above the liquid connector insertion port 53a, which is the liquid inlet port of the liquid ejection head 1, in the direction of gravity. Furthermore, the circulation pump 500 is disposed at a position where it is not in contact with the members constituting the liquid connection part 700. As a result, even if liquid leaks from the liquid connection part 700, the liquid flows in the horizontal direction, which is the opening direction of the liquid connector 59a, or downward in the direction of gravity, so that it is possible to prevent the liquid from reaching the circulation pump 500, which is located above in the direction of gravity. In addition, since the circulation pump 500 is disposed at a position away from the liquid connection part 700, the possibility that the liquid will reach the circulation pump 500 by running down the members is also reduced.

[0124] Furthermore, electrical connection part 515, which electrically connects circulation pump 500 and electrical contact board 6 via flexible wiring member 514, is provided above liquid connection part 700 in the direction of gravity. This reduces the possibility of electrical trouble caused by liquid from liquid connection part 700.

[0125] Furthermore, in this embodiment, since the wall portion 53b of the head housing 53 is provided, even if liquid ejects from the opening 59b of the liquid connection portion 700, the liquid can be blocked, reducing the possibility of the liquid reaching the circulation pump 500 or the electrical connection portion 515.

[0126] <Temperature adjustment means> In the recording method of the present invention, the liquid ejection head is configured to eject an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink. Here, due to the difference in viscosity between the aqueous ink and the aqueous reaction liquid, the ejection balance between the aqueous reaction liquid and the aqueous ink may be lost due to this difference in viscosity, resulting in image unevenness. In general, aqueous ink containing colorant particles, resin, etc. often has a lower viscosity than the aqueous reaction liquid. Therefore, as described above, in the recording method of the present invention, the viscosity of the ejection liquid is adjusted by heating at least one of the ink or the reaction liquid using a temperature adjustment means. This makes it possible to achieve an ejection balance between the aqueous reaction liquid and the aqueous ink, thereby suppressing image unevenness.

[0127] Examples of the temperature adjustment means include a heater for adjusting the temperature of the discharged liquid, which is arranged so as to be in contact with the liquid discharge head, and a heater for liquid discharge (electrothermal conversion element). To heat the discharged liquid using a heater for ink discharge, for example, it is sufficient to repeatedly pass an electric current that is not enough to discharge the liquid. By heating the liquid in the liquid discharge head, the viscosity of the liquid decreases. By adjusting the temperature so that the difference in viscosity between the ink and the reaction liquid is reduced, the discharge balance between the aqueous reaction liquid and the aqueous ink can be achieved, and image unevenness can be suppressed. In addition, by lowering the viscosity of the discharged liquid by heating, it becomes easier to supply (refill) the liquid, and the effect of enabling stable continuous discharge and liquid circulation can be obtained.

[0128] In the inkjet recording method of the present invention, it is preferable to heat the ink, which often has a higher viscosity than the reaction liquid, to a temperature higher than the recording environment temperature (for example, around 25° C.) in the liquid ejection head by the above-mentioned temperature adjustment means and eject the ink. Specifically, it is preferable to heat the ink to a temperature between 30° C. and 80° C., and more preferably between 35° C. and 70° C. That is, the temperature of the ink during ejection, that is, the temperature T1 (° C.) of the ink after heating, is preferably between 30° C. and 80° C., and more preferably between 35° C. and 70° C.

[0129] In this embodiment, the discharge element substrate 340 is provided with a heater for heating the liquid around the discharge element. As an example, the discharge element substrate 340 is divided into a plurality of regions, and a temperature adjustment heater and a temperature sensor are provided for each region. FIG. 20 is a diagram showing the discharge element substrate 340, showing the opposite side to FIG. 13. In FIG. 20, a temperature adjustment heater 801 and a temperature sensor 802 as temperature adjustment means are provided for each region in the discharge element substrate 340 near the discharge element 15. In this case, the CPU 103 (see FIG. 1(b)) uses the temperature adjustment heater 801 and the temperature sensor 802 to adjust the temperature based on the temperature set for each region. That is, the CPU 103 drives the temperature adjustment heater 801 only for the region where the temperature detected by the temperature sensor 802 is equal to or lower than the target temperature. Moreover, by performing such temperature control, the temperature variation in the recording element substrate 10 and the temperature variation among the multiple ejection element substrates 340 can be suppressed within a predetermined range, thereby reducing the variation in the ejection amount caused by the temperature variation, and suppressing density unevenness in the printed image. Note that a diode sensor, an aluminum sensor, or the like can be used as the temperature sensor.

[0130] Furthermore, as described above, in the recording method of the present invention, the circulation path of the ejection liquid is configured to be completed within the liquid ejection head. Therefore, the total volume of the circulation path can be made smaller than in a configuration in which the circulation of the ejection liquid is performed between the liquid ejection head and the outside. As a result, the time required to stabilize the liquid temperature in the circulation path can be shortened, and productivity can be improved. In addition, since the liquid is less likely to be cooled in the circulation path, the frequency of driving the temperature adjustment heater can be reduced, and the power consumption required to maintain the temperature of the liquid can also be reduced.

[0131] The total volume of ink flowing through one circulation path is preferably 30 mL or less, more preferably 15 mL or less, and more preferably 5 mL or more. That is, the volume of liquid flowing through the circulation path is preferably 5 mL or more and 30 mL or less, and more preferably 5 mL or more and 15 mL or less.

[0132] When the ejection element substrate 340 has a temperature adjustment means configured to be able to heat the ink and a temperature adjustment means configured to be able to heat the reaction liquid, the temperature adjustment means provided on the ejection element substrate 340 are preferably arranged for each ejection port array corresponding to different types of ejection liquid. A plurality of temperature adjustment means such as a temperature adjustment heater may be arranged in one ejection port array. Also, an ejection port array configured to eject ink may be configured to eject a plurality of types of ink (for example, three colors of cyan, magenta, and yellow) from one array. By each of the ejection port array (first ejection port array) corresponding to the ink and the ejection port array (second ejection port array) corresponding to the reaction liquid having a temperature adjustment means, it becomes easier to adjust the temperature of each of the ink and the reaction liquid and to more uniform the ejection balance.

[0133] It is also preferable that the ejection module 300 for ejecting ink and the ejection module 300 for ejecting reaction liquid are separate. That is, it is preferable that the liquid ejection head 1 has a plurality of ejection modules 300 including an ejection module 300 (first element substrate) for ejecting ink and an ejection module 300 (second element substrate) for ejecting reaction liquid. In this case, the temperature adjustment of each of the ink and reaction liquid can be performed more efficiently.

[0134] When the viscosity of the ink is higher than that of the reaction liquid at the recording environment temperature (for example, around 25° C.), the adjustment temperature t1 of the ink by the temperature adjustment means is set higher than the adjustment temperature t2 of the reaction liquid. On the other hand, when the viscosity of the ink is lower than the viscosity of the reaction liquid at the recording environment temperature, the adjustment temperature t1 of the ink is set lower than the adjustment temperature t2 of the reaction liquid.

[0135] The temperature adjustment means may be provided in the discharge unit 3 other than the discharge element substrate 340, or may be provided in the circulation unit (inside the circulation unit 54). In either case, the temperature adjustment means is preferably disposed on the upstream side of the liquid circulation path, that is, in the path in which the liquid flows from the circulation pump 500 to the pressure chamber 12. When the temperature adjustment means is disposed in the discharge unit 3, it is preferably disposed in the supply port 88, the liquid supply flow path 48, the common supply flow path 18, and the supply connection flow path 323.

[0136] The temperature adjustment means may be configured to be capable of heating the ejection liquid in the ink tank 2 or the supply tube 59 outside the liquid ejection head 1. In this case, it is preferable to provide separate temperature adjustment means for the ink and the reaction liquid.

[0137] As a temperature adjustment means, a configuration including a cooling mechanism for cooling the ejection liquid is also conceivable. At the recording environment temperature, the ink often has a higher viscosity than the reaction liquid, but it is conceivable that the temperature of the reaction liquid may become high due to the energy used during ejection, and the viscosity of the reaction liquid may become too low compared to the ink. In such a case, the viscosity of the reaction liquid may be adjusted by lowering the temperature of the reaction liquid using a cooling mechanism such as a Peltier element or a fan, making it possible to achieve an ejection balance with the ink.

[0138] (2) Reaction solution Each component used in the aqueous reaction liquid of the present invention will be described in detail below.

[0139] (Reactant) The reaction liquid reacts with the ink upon contact with the ink to aggregate the components in the ink (components having anionic groups, such as resins and self-dispersing pigments), and contains a reactant, examples of which include polyvalent metal salts, organic acids, cationic resins, etc. Any reactant can be added to the reaction liquid within a range in which desired properties, such as storage stability of the reaction liquid, intermittent ejection stability, and suppression of image unevenness, can be obtained.

[0140] In a reaction liquid containing a polyvalent metal salt, the polyvalent metal salt is a compound formed by bonding a divalent or higher metal ion and an anion, and dissociates in the reaction liquid to become polyvalent metal ions, which can aggregate the dispersed colorant by the action of the anionic groups contained in the ink.

[0141] Examples of polyvalent metal ions include Ca. 2+ , Cu 2+ , Ni 2+ , Mg 2+ , Sr 2+ , B.A. 2+ , and Zn 2+ Divalent metal ions such as Fe 3+ , Cr 3+ , Y 3+ , and Al 3+ In order to add a polyvalent metal ion to the reaction solution, a polyvalent metal salt (which may be a hydrate) formed by combining a polyvalent metal ion with an anion can be used. Examples of the anion include Cl. - , Br - , I - , ClO - , ClO2 - , ClO3 - , ClO4 - , NO2 - , NO3 - , SO4 2- , CO3 2- , HCO3 - , PO4 3- , HPO4 2- , and H2PO4 - Inorganic anions such as HCOO - , (COO - )2, COOH(COO - ), CH3COO - , C2H5COO - , CH3CH(OH)COO - , C2H4(COO - )2, C6H5COO - , C6H4(COO - )2, and CH3SO3 -The content (mass %) of the polyvalent metal salt in the reaction solution is preferably 1.0 mass % or more and 20.0 mass % or less based on the total mass of the reaction solution.

[0142] The solubility (g / 100 mL) of the polyvalent metal salt in water at 25° C. is preferably 25.0 g / 100 mL or more. If the solubility is less than 25.0 g / 100 mL, the dissolved state of the polyvalent metal salt in the reaction liquid tends to become unstable, and the polyvalent metal salt tends to precipitate. The precipitated polyvalent metal salt may reduce the reactivity with the ink, and image unevenness may not be sufficiently suppressed. The solubility is preferably 50.0 g / 100 mL or less.

[0143] The reaction liquid containing an organic acid has a buffering ability in the acidic range (less than pH 7.0, preferably pH 2.0 to 5.0), and thus efficiently converts the anionic groups of the components present in the ink into an acid form and causes them to aggregate. Examples of the organic acid include monocarboxylic acids and salts thereof, such as formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, glycolic acid, lactic acid, salicylic acid, pyrrole carboxylic acid, furan carboxylic acid, picolinic acid, nicotinic acid, thiophene carboxylic acid, levulinic acid, and coumaric acid; dicarboxylic acids and salts and hydrogen salts thereof, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid, and tartaric acid; tricarboxylic acids and salts and hydrogen salts thereof, such as citric acid and trimellitic acid; and tetracarboxylic acids and salts and hydrogen salts thereof, such as pyromellitic acid. When an organic acid is added, the content (mass %) of the organic acid in the reaction liquid is preferably 1.0 mass % or more and 50.0 mass % or less based on the total mass of the reaction liquid.

[0144] Examples of the cationic resin include resins having a structure of primary to tertiary amines and resins having a structure of quaternary ammonium salts. Specific examples include resins having a structure of vinylamine, allylamine, vinylimidazole, vinylpyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyldimethylammonium chloride, and alkylamine-epichlorohydrin condensate. In order to increase the solubility in the reaction solution, the cationic resin may be used in combination with an acidic compound or the cationic resin may be subjected to a quaternary treatment. When the cationic resin is added, the content (mass%) of the cationic resin in the reaction solution is preferably 0.1 mass% or more and 10.0 mass% or less based on the total mass of the reaction solution.

[0145] (Other Ingredients) The reaction liquid may contain various other components as necessary, including the same components as those that can be contained in the ink described below.

[0146] (Properties of reaction solution) The reaction liquid that can be suitably used in the recording method of the present invention is an aqueous reaction liquid applied to the inkjet method. Therefore, from the viewpoint of reliability, it is preferable to appropriately control the physical property values. Specifically, the surface tension of the reaction liquid at 25°C is preferably 20 mN / m or more and 60 mN / m or less. In addition, the viscosity of the reaction liquid at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the reaction liquid at 25°C is preferably 5.0 or more and 9.5 or less, more preferably 6.0 or more and 9.0 or less.

[0147] (3) Ink Hereinafter, the ink that can be used in the inkjet recording method of the present invention will be described in detail with reference to preferred embodiments. In the present invention, when the compound is a salt, the salt is dissociated into ions and exists in the ink, but for convenience, it is expressed as "containing salt". Titanium oxide and titanium oxide particles may be simply described as "pigment". In addition, water-based ink for inkjet may be simply described as "ink". Physical property values ​​are values ​​at room temperature (25°C) unless otherwise specified. In addition, when recording an image with white ink, which will be described later, white ink may be used as a base treatment for color ink. In that case, color ink (ink such as black, cyan, magenta, yellow, etc.) may be applied so as to overlap at least a part of the area where the white ink is applied, and an image may be recorded. In addition, it can also be used for back printing in which white ink is applied so as to overlap at least a part of the area where the color ink is applied.

[0148] The ink of the present invention is an aqueous ink for inkjet printing containing a coloring material that is dispersed by the action of an anionic group. The ink of the present invention does not need to be a so-called "curable ink". Therefore, the ink of the present invention does not need to contain a compound such as a polymerizable monomer that can be polymerized by the addition of external energy such as heat or light. The components constituting the ink of the present invention and the physical properties of the ink are described in detail below.

[0149] (Colorant) The ink contains a coloring material that is dispersed by anionic action. Pigments and dyes can be used as the coloring material. The content (mass %) of the coloring material in the ink is preferably 0.1% by mass or more and 15.0% by mass or less, and more preferably 1.0% by mass or more and 10.0% by mass or less, based on the total mass of the ink.

[0150] Specific examples of pigments include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolone, diketopyrrolopyrrole, and dioxazine.

[0151] As a method for dispersing pigments, resin-dispersed pigments using resin as a dispersant, self-dispersed pigments in which hydrophilic groups are bonded to the pigment particle surface, etc. can be used. In addition, resin-bonded pigments in which organic groups containing resin are chemically bonded to the pigment particle surface, and microcapsule pigments in which the pigment particle surface is coated with resin, etc. can be used. Among them, it is preferable to use resin-dispersed pigments in which a resin as a dispersant is physically adsorbed onto the pigment particle surface, rather than resin-bonded pigments or microcapsule pigments. In other words, it is preferable that the pigment is dispersed by a resin (resin dispersant) having an anionic group.

[0152] The resin dispersant for dispersing the pigment in the aqueous medium is one that can disperse the pigment in the aqueous medium by the action of anionic groups. The resin dispersant may be a resin as described below, particularly a water-soluble resin. The content (mass%) of the pigment in the ink is preferably 0.3 to 10.0 times the mass ratio of the content of the resin dispersant.

[0153] As the self-dispersing pigment, an anionic group such as a carboxylic acid group, a sulfonic acid group, or a phosphonic acid group can be used, which is bonded to the particle surface of the pigment directly or via another atomic group (-R-). The anionic group may be either an acid type or a salt type, and when it is a salt type, it may be either a partially dissociated state or a completely dissociated state. When the anionic group is a salt type, examples of the cation that serves as the counter ion include an alkali metal cation, ammonium, and organic ammonium. Specific examples of the other atomic group (-R-) include a linear or branched alkylene group having 1 to 12 carbon atoms; an arylene group such as a phenylene group or a naphthylene group; a carbonyl group; an imino group; an amide group; a sulfonyl group; an ester group; and an ether group. In addition, it may be a group that is a combination of these groups.

[0154] The dye used has an anionic group. Specific examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, and anthrapyridone dyes. The coloring material is preferably a pigment, and more preferably a resin-dispersed pigment.

[0155] (Colorant (white ink)) The present invention can also be suitably used in an inkjet recording method using an ink containing titanium oxide as a coloring material. This ink is preferably a white ink because titanium oxide is a white pigment. In an inkjet recording method using a reaction liquid containing a reactant that reacts with the ink, as in the present invention, a non-absorbent recording medium made of polyvinyl chloride (PVC) or polyethylene terephthalate (PET) is often used, as described above. In such a case, by performing recording using a white ink containing titanium oxide, it becomes possible to record an image with high color development regardless of the color of the recording medium itself. Hereinafter, the coloring material in the white ink containing titanium oxide will be described.

[0156] The white ink contains titanium oxide as a coloring material (pigment). The titanium oxide may be titanium oxide particles that have been surface-treated with a specific inorganic oxide. In other words, the white ink may contain titanium oxide particles that are titanium oxide whose surfaces are coated with a specific inorganic oxide. The content (mass%) of the titanium oxide particles in the ink is preferably 0.10% by mass or more and 20.00% by mass or less based on the total mass of the ink. Furthermore, the content (mass%) of the titanium oxide particles in the ink is more preferably 1.00% by mass or more and 20.00% by mass or less based on the total mass of the ink. In particular, the content (mass%) of the titanium oxide particles in the ink is particularly preferably 1.00% by mass or more and 15.00% by mass or less based on the total mass of the ink.

[0157] Titanium oxide is a white pigment, and has three crystal forms: rutile, anatase, and brookite. Among them, rutile titanium oxide is preferred. Titanium oxide can be industrially produced by the sulfuric acid method and the chlorine method, and the titanium oxide used in the present invention may be produced by either method.

[0158] The volume-based cumulative 50% particle diameter (hereinafter also referred to as the average particle diameter) of the titanium oxide particles is preferably 200 nm or more and 500 nm or less. In particular, the volume-based cumulative 50% particle diameter of the titanium oxide particles is more preferably 200 nm or more and 400 nm or less. The volume-based cumulative 50% particle diameter (D50) of the titanium oxide particles is the diameter of the particle that is 50% of the total volume of the measured particles when integrated from the small particle diameter side in a particle diameter integration curve. The D50 of the titanium oxide particles can be measured under the following conditions, for example: SetZero: 30 seconds, number of measurements: 3 times, measurement time: 180 seconds, shape: non-spherical, refractive index: 2.60. A particle size analyzer using a dynamic light scattering method can be used as the particle size distribution measuring device. Of course, the measurement conditions are not limited to those described above.

[0159] Titanium oxide that has been surface-treated with alumina and silica may be used. The surface treatment is expected to suppress photocatalytic activity and improve dispersibility. In this specification, "alumina" is a general term for oxides of aluminum such as aluminum oxide. In this specification, "silica" is a general term for silicon dioxide or a substance composed of silicon dioxide. Most of the alumina and silica that coat titanium oxide are present in the form of silicon dioxide and aluminum oxide.

[0160] The ratio (mass%) of titanium oxide in the titanium oxide particles is preferably 90.00% by mass or more based on the total mass of the titanium oxide particles. The ratio (mass%) of titanium oxide in the titanium oxide particles is preferably 98.50% by mass or less based on the total mass of the titanium oxide particles. The ratio (mass%) of alumina in the titanium oxide particles must be 0.50 times or more and 1.00 times or less in mass ratio to the ratio (mass%) of silica. If the mass ratio is less than 0.50 times or more than 1.00 times, the ink ejection stability cannot be obtained. The ratio (mass%) of silica in the titanium oxide particles is preferably 1.00% by mass or more and 4.00% by mass or less based on the total mass of the titanium oxide particles. If the ratio (mass%) of silica is less than 1.00% by mass, the affinity with the compound represented by general formula (1) cannot be obtained sufficiently, and the ink ejection stability may not be obtained sufficiently. If the proportion (mass%) of silica exceeds 4.00% by mass, the amount of the compound represented by general formula (1) adsorbed to the titanium oxide particles cannot be suppressed even if the titanium oxide particles are surface-treated with alumina, and sufficient ink ejection stability may not be obtained. The proportion (mass%) of alumina in the titanium oxide particles is preferably 0.50% by mass or more and 4.00% by mass or less based on the total mass of the titanium oxide particles.

[0161] The proportion of alumina and silica in titanium oxide particles, i.e., the amount of alumina and silica coating, can be measured by, for example, quantitative analysis of aluminum and silicon elements by inductively coupled plasma (ICP) emission spectrometry. In this case, it is assumed that all atoms coating the surface are oxides, and the obtained values ​​of aluminum and silicon can be calculated by converting them to their oxides, i.e., alumina and silica. The proportion (mass%) of aluminum element in titanium oxide particles obtained by inductively coupled plasma emission spectrometry is 0.57 times or more and 1.13 times or less in mass ratio to the proportion (mass%) of silicon element. When this value is converted to its oxides, i.e., alumina and silica, the proportion (mass%) of alumina in titanium oxide particles is 0.50 times or more and 1.00 times or less in mass ratio to the proportion (mass%) of silica.

[0162] Surface treatment methods for titanium oxide include wet treatment and dry treatment. For example, titanium oxide can be dispersed in a liquid medium and then reacted with a surface treatment agent such as sodium aluminate or sodium silicate to perform surface treatment, and the desired characteristics can be achieved by appropriately changing the ratio of these surface treatment agents. In addition to alumina and silica, inorganic oxides such as zinc oxide and zirconia, and organic substances such as polyols can also be used for surface treatment, as long as the effects of the present invention are not impaired.

[0163] As long as the effect of the present invention is not impaired, the white ink may contain other pigments besides titanium oxide. In this case, the ink may be of a color other than white ink. The content (mass %) of the other pigments in the ink is preferably 0.10 mass % or more and 5.00 mass % or less, and more preferably 0.10 mass % or more and 1.00 mass % or less, based on the total mass of the ink.

[0164] (Compound represented by general formula (1)) The ink preferably contains a compound represented by the following general formula (1) as a dispersant for dispersing titanium oxide particles: The content (mass %) of the compound represented by general formula (1) in the ink is preferably 0.01 mass % or more and 1.00 mass % or less, and more preferably 0.02 mass % or more and 0.50 mass % or less, based on the total mass of the ink.

[0165] [ka]

[0166] (In general formula (1), R1, R2, and R3 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Each R4 is independently an alkylene group having 2 to 4 carbon atoms. X is a single bond or an alkylene group having 1 to 6 carbon atoms. n is 6 to 24. a is 1 to 3, b is 0 to 2, and a+b=3.) In the general formula (1), R1, R2, and R3 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-butyl group. Among them, a methyl group is preferable from the viewpoint of ease of hydrolysis. If R1, R2, and R3 are each an alkyl group having more than 4 carbon atoms, it becomes difficult to form a silanol group by hydrolysis, and affinity with titanium oxide particles is not obtained. Therefore, the titanium oxide particles cannot be stably dispersed, and the ink ejection stability is not obtained. a, which represents the number of R1O, is 1 to 3, and b, which represents the number of R2, is 0 to 2, and a+b=3. Among them, it is preferable that a is 3 and b is 0, that is, all three substituents of the silicon atom are R1O.

[0167] In the general formula (1), R4 is independently an alkylene group having 2 to 4 carbon atoms. Examples of the alkylene group having 2 to 4 carbon atoms include an ethylene group, an n-propylene group, an i-propylene group, and an n-butylene group. Among them, an ethylene group is preferable. The number of OR4, that is, n (average value) representing the number of alkylene oxide groups, is 6 to 24. When n is less than 6, the length of the alkylene oxide chain is too short, so that the repulsive force due to steric hindrance is not sufficiently obtained, and the ink ejection stability is not obtained. When n is more than 24, the length of the alkylene oxide chain is too long, so that the hydrophilicity is increased and the ink is easily liberated in the aqueous medium. Therefore, the affinity with the surface hydroxyl group of the titanium oxide particles is not sufficiently obtained, and the aggregation of the titanium oxide particles cannot be suppressed. Therefore, the titanium oxide particles cannot be stably dispersed, and the ink ejection stability is not obtained.

[0168] In the general formula (1), X is a single bond or an alkylene group having 1 to 6 carbon atoms. When X is a single bond, it means that the silicon atom and OR4 are directly bonded. Examples of the alkylene group having 1 to 6 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an i-propylene group, an n-butylene group, an n-pentylene group, and an n-hexylene group. Of these, an n-propylene group is preferable. When X is an alkylene group having more than 6 carbon atoms, the hydrophobicity of the compound represented by the general formula (1) becomes too high, so that the titanium oxide particles cannot be stably dispersed, and the ink ejection stability cannot be obtained.

[0169] The compound represented by general formula (1), which is a dispersant for titanium oxide particles, is preferably a compound represented by the following general formula (2). The compound represented by general formula (2) has three OR1s bonded to silicon atoms, so that a part of it can be hydrolyzed in an aqueous medium to form three hydroxyl groups bonded to silicon atoms, thereby increasing the portion having affinity with titanium oxide particles. In addition, the compound represented by the following general formula (2) has a repeating structure of ethylene oxide groups. Therefore, the ethylene oxide chains can be appropriately extended in an aqueous medium, and a repulsive force due to steric hindrance can be obtained.

[0170] [ka]

[0171] (In general formula (2), R1 and R3 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. m is an integer of 8 to 24.) The content (mass%) of the compound represented by general formula (1) in the ink is preferably 0.002 times or more and 0.10 times or less in mass ratio to the content (mass%) of titanium oxide particles. If the mass ratio is less than 0.002 times, the effect of stably dispersing titanium oxide particles is weakened, and the ink ejection stability may not be sufficiently obtained. If the mass ratio is more than 0.10 times, the proportion of the compound represented by general formula (1) becomes too high, and condensation (self-condensation) between molecules of the compound represented by general formula (1) is likely to occur. Therefore, the compound represented by general formula (1) is consumed without acting as a dispersant, and the effect of stably dispersing titanium oxide particles is weakened, and the ink ejection stability may not be sufficiently obtained.

[0172] The compound represented by the general formula (1) forms hydrogen bonds with the surface hydroxyl groups of the titanium oxide particles, but some of them are thought to form covalent bonds through a dehydration reaction. However, in the present invention, the compound represented by the general formula (1) can disperse the titanium oxide particles even if it does not form a covalent bond with the titanium oxide particles. In other words, the amount of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles is very small and can be ignored. Therefore, the content of the titanium oxide particles does not include the compound represented by the general formula (1) covalently bonded. As a result of the investigation by the present inventors, it was found that if the amount of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles is too large, the ejection stability of the ink decreases. The reasons for this are considered to be as follows. In general, in a liquid medium with a high dielectric constant such as water, electrostatic attraction is less likely to work, so that the titanium oxide particles move freely without being affected much by the surrounding environment. However, when the compound represented by the general formula (1) forms a covalent bond with the titanium oxide particles, the hydrophilic portion (OR4 portion) of the structure of the general formula (1) forms a hydrogen bond with the water molecules, which may affect the movement of the titanium oxide particles. Therefore, in a situation where the liquid is deformed by instantaneous pressure, such as during inkjet ejection, the above characteristics appear as differences in ejection characteristics. For this reason, the amount (mass%) of the compound represented by general formula (1) covalently bonded to the titanium oxide particles is preferably 0.001 or less in mass ratio to the titanium oxide particle content (mass%). If the mass ratio exceeds 0.001, the ink ejection stability may not be sufficient. The mass ratio may be 0.000. The amount of the compound represented by general formula (1) covalently bonded to the titanium oxide particles can be calculated by thermogravimetric analysis or the like.

[0173] (resin) The ink may contain a resin. Examples of the resin include acrylic resin, urethane resin, and urea resin. Of these, acrylic resin is preferred. The content (mass%) of the resin in the ink is preferably 1.00% by mass or more and 25.00% by mass or less, and more preferably 3.00% by mass or more and 15.00% by mass or less, based on the total mass of the ink. Of these, the content of 5.00% by mass or more and 15.00% by mass or less is particularly preferred.

[0174] The resin can be contained in the ink for the purpose of improving various properties of the recorded image, such as abrasion resistance and hiding power. Examples of the form of the resin include block copolymers, random copolymers, graft copolymers, and combinations thereof. The resin may be a water-soluble resin that can be dissolved in an aqueous medium, or may be resin particles that are dispersed in an aqueous medium. The resin particles do not need to encapsulate a coloring material.

[0175] In this specification, "a resin is water-soluble" means that when the resin is neutralized with an alkali equivalent to the acid value, the resin is present in an aqueous medium in a state in which it does not form particles whose particle size can be measured by a dynamic light scattering method. Whether or not a resin is water-soluble can be determined according to the following method. First, a liquid (resin solid content: 10 mass%) containing a resin neutralized with an alkali (sodium hydroxide, potassium hydroxide, etc.) equivalent to the acid value is prepared. Next, the prepared liquid is diluted 10 times (volume basis) with pure water to prepare a sample solution. Then, when the particle size of the resin in the sample solution is measured by a dynamic light scattering method, if particles having a particle size are not measured, the resin can be determined to be water-soluble. The measurement conditions at this time can be, for example, SetZero: 30 seconds, number of measurements: 3 times, and measurement time: 180 seconds. As a particle size distribution measurement device, a particle size analyzer using a dynamic light scattering method (for example, the product name "UPA-EX150", manufactured by Nikkiso) can be used. Of course, the particle size distribution measurement device and measurement conditions used are not limited to those described above.

[0176] The acid value of the water-soluble resin is preferably 80 mgKOH / g or more and 250 mgKOH / g or less, more preferably 100 mgKOH / g or more and 200 mgKOH / g or less. When resin particles are used, the acid value is preferably 0 mgKOH / g or more and 50 mgKOH / g or less. The weight average molecular weight of the resin is preferably 1,000 or more and 30,000 or less, more preferably 5,000 or more and 15,000 or less. The weight average molecular weight of the resin is a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0177] (aqueous medium) The ink is an aqueous ink containing water as an aqueous medium. The ink may contain water or an aqueous medium that is a mixed solvent of water and a water-soluble organic solvent. As the water, it is preferable to use deionized water (ion-exchanged water). The content (mass %) of water in the ink is preferably 50.00 mass % or more and 95.00 mass % or less based on the total mass of the ink.

[0178] The water-soluble organic solvent is not particularly limited as long as it is water-soluble (preferably, dissolves in water at any ratio at 25°C). Specifically, monohydric or polyhydric alcohols, alkylene glycols, glycol ethers, nitrogen-containing polar compounds, sulfur-containing polar compounds, etc. can be used. The content (mass%) of the water-soluble organic solvent in the ink is preferably 3.00% by mass or more and 50.00% by mass or less, and more preferably 10.00% by mass or more and 40.00% by mass or less, based on the total mass of the ink. If the content (mass%) of the water-soluble organic solvent is less than 3.00% by mass, the ink may be stuck in the inkjet recording device, and sufficient sticking resistance may not be obtained. If the content (mass%) of the water-soluble organic solvent is more than 50.00% by mass, poor ink supply may occur.

[0179] (Other additives) In addition to the above additives, the ink may contain various additives such as surfactants, pH adjusters, rust inhibitors, preservatives, antifungal agents, antioxidants, reduction inhibitors, evaporation promoters, and chelating agents, as necessary. Among these, it is preferable that the ink contains a surfactant. The content (mass%) of the surfactant in the ink is preferably 0.10% by mass or more and 5.00% by mass or less, and more preferably 0.10% by mass or more and 2.00% by mass or less, based on the total mass of the ink. Examples of surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants. Among these, nonionic surfactants are preferable because they have low affinity with titanium oxide particles and are effective in small amounts, since they are used to adjust various physical properties of the ink.

[0180] (Ink properties) Since the ink is applied to the inkjet method, it is preferable to appropriately control the physical properties of the ink. The surface tension of the ink at 25°C is preferably 10 mN / m or more and 60 mN / m or less, and more preferably 20 mN / m or more and 40 mN / m or less. The surface tension of the ink can be adjusted by appropriately determining the type and content of the surfactant in the ink. In addition, the viscosity of the ink at 25°C is preferably 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the ink at 25°C is preferably 7.0 or more and 9.0 or less. If the pH of the ink is within the above range, the generation of silanol groups due to hydrolysis of the compound represented by general formula (1) proceeds, and the weak affinity between the titanium oxide particles and the compound represented by general formula (1) is effectively exerted. The pH of the ink can be measured with a general pH meter equipped with a glass electrode or the like. EXAMPLES

[0181] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples in any way as long as it does not deviate from the gist of the invention. "Parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified. In addition, a dispersion of titanium oxide particles is referred to as a "pigment dispersion."

[0182] <Preparation of titanium dioxide> Commercially available rutile-type titanium oxide particles that had been surface-treated in advance were used. The cumulative 50% particle diameter (D 50 ) was measured using a particle size analyzer using the dynamic light scattering method (product name "Nanotrac WaveII-EX150", manufactured by Microtrack Bell). The properties of each titanium oxide particle are shown in Table 1.

[0183] [Table 1]

[0184] <Preparation of pigment dispersion> (Pigment dispersion 1) A styrene-methyl methacrylate-methacrylic acid copolymer (resin 1) with an acid value of 150 mgKOH / g and a weight average molecular weight of 10,000 was prepared. 20.0 parts of resin 1 were neutralized with potassium hydroxide in an amount equivalent to the acid value, and an appropriate amount of pure water was added to prepare an aqueous solution of resin 1 with a resin (solid content) content of 20.0%. 40.0 parts of titanium oxide particles 1, 40.0 parts of the aqueous solution of resin 1, and ion-exchanged water with a total of 100.0 parts of the components were mixed and pre-dispersed using a homogenizer. Then, using 0.5 mm zirconia beads, a dispersion treatment (main dispersion) was performed for 12 hours at 25°C using a paint shaker. The zirconia beads were filtered off, and an appropriate amount of ion-exchanged water was added as necessary to prepare a pigment dispersion 1 with a titanium oxide particle content of 40.0% and a resin dispersant (resin 1) content of 8.0%.

[0185] <Ink Preparation> 25.0 parts of Pigment Dispersion Liquid 1 and the following components were mixed and stirred, then pressure filtered using a membrane filter (manufactured by Sartorius) with a pore size of 5.0 μm to prepare Ink 1.

[0186] The details of each mixed component are given below. Acrylic resin particles (product name "Vinyblan 2685", manufactured by Nissin Chemical Industry Co., Ltd., resin particle content: 30%): 20.0 parts Diethylene glycol: 10.0 parts Diethylene glycol isobutyl ether: 10.0 parts Fluorosurfactant (product name "Capstone FS-3100", manufactured by Chemours): 1.0 part Deionized water: 34.0 parts.

[0187] Viscosity of ink 1 (Pa s) and density of liquid components (g / cm 3 ) are 8 Pa s and 1.16 g / cm 3 It was.

[0188] <Preparation of reaction solution> The components shown below were mixed and thoroughly stirred, and then pressure filtered using a cellulose acetate filter (manufactured by Advantec) with a pore size of 3.0 μm to prepare reaction solution 1. Magnesium sulfate: 2.0% 1,2-butanediol: 20.0% Fluorine-based nonionic surfactant (product name "Capstone FS3100", manufactured by LEHVOSS Group): 0.5% Preservative (product name "Proxel GXL(S)", manufactured by Arch Chemicals): 0.2% Ion-exchanged water: 77.3% When magnesium sulfate was added, magnesium sulfate heptahydrate was used and added so as to obtain the above amount of magnesium sulfate.

[0189] <Liquid ejection head> (Head 1) A liquid ejection head shown in FIGS. 2 to 5, in which a temperature adjustment heater and a temperature sensor are provided for each ejection port row on an ejection element substrate 340 as a temperature adjustment means, was prepared as head 1.

[0190] (Head 2) A head 2 was prepared with the same configuration as head 1, except that it did not have a temperature adjustment means.

[0191] <Evaluation> Ink 1 and reaction liquid 1 were set in an inkjet recording device equipped with head 1 or head 2, and the ink was ejected in an environment of 25°C and 50% relative humidity. It was confirmed that the effects of the present invention could be fully obtained in the inkjet recording device equipped with head 1.

[0192] The disclosure of this embodiment includes the following methods and configurations.

[0193] (Method 1) An inkjet recording method in which an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink are ejected from a liquid ejection head to record an image on a recording medium, comprising the steps of: The liquid ejection head includes: an element substrate having a discharge port for discharging the aqueous reaction liquid and a pressure chamber communicating with the discharge port and including a discharge element for generating energy for discharging the liquid; an upstream flow path for supplying liquid to the pressure chamber; a downstream flow passage communicating with the pressure chamber; a pump communicating with the upstream flow path and the downstream flow path and configured to cause liquid in the downstream flow path to flow into the upstream flow path; a temperature adjusting means configured to be capable of heating the aqueous ink or the aqueous reaction liquid; An ink-jet recording method comprising the steps of:

[0194] (Method 2) An inkjet recording method in which an aqueous reaction liquid containing an aqueous ink and a reactant that reacts with the aqueous ink is ejected from a liquid ejection head to record an image on a recording medium, comprising the steps of: The liquid ejection head includes: a first ejection port for ejecting the water-based ink, a first pressure chamber communicating with the first ejection port and including a first ejection element for generating energy for ejecting the water-based ink, a first upstream flow path for supplying the water-based ink to the first pressure chamber, a first downstream flow path communicating with the first pressure chamber, and a first pump communicating with the first upstream flow path and the first downstream flow path and configured to cause the water-based ink in the first downstream flow path to flow into the first upstream flow path; a second outlet for discharging the aqueous reaction liquid, a second pressure chamber communicating with the second outlet and equipped with a second discharge element for generating energy for discharging the aqueous reaction liquid, a second upstream flow path for supplying the aqueous reaction liquid to the second pressure chamber, a second downstream flow path communicating with the second pressure chamber, and a second pump communicating with the second upstream flow path and the second downstream flow path and configured to cause the aqueous reaction liquid in the second downstream flow path to flow into the second upstream flow path; An element substrate including: a temperature adjusting means configured to be capable of heating the aqueous ink or the aqueous reaction liquid; An ink-jet recording method comprising the steps of:

[0195] (Method 3) The liquid ejection head comprises a first ejection port array in which a plurality of the first ejection ports for ejecting the water-based ink are arranged, and a second ejection port array in which a plurality of the second ejection ports for ejecting the water-based reaction liquid are arranged, The inkjet recording method according to Method 2, wherein the temperature adjustment means is provided corresponding to each of the first ejection port array and the second ejection port array.

[0196] (Method 4) The inkjet recording method described in Method 2, wherein the liquid ejection head comprises a first element substrate having the first ejection port for ejecting the water-based ink, and a second element substrate having the second ejection port for ejecting the reaction liquid.

[0197] (Method 5) The inkjet recording method according to Method 4, wherein the temperature adjusting means is provided corresponding to each of the first element substrate and the second element substrate.

[0198] (Configuration 1) An inkjet recording device used to record an image on a recording medium by ejecting an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from a liquid ejection head, the inkjet recording device comprising: The liquid ejection head includes: an element substrate having a discharge port for discharging the aqueous reaction liquid and a pressure chamber communicating with the discharge port and including a discharge element for generating energy for discharging the liquid; an upstream flow path for supplying liquid to the pressure chamber; a downstream flow passage communicating with the pressure chamber; a pump communicating with the upstream flow path and the downstream flow path and configured to cause liquid in the downstream flow path to flow into the upstream flow path; a temperature adjusting means configured to be capable of heating the aqueous ink or the aqueous reaction liquid; An inkjet recording apparatus comprising: [Explanation of symbols]

[0199] 1 Liquid ejection head 12 Pressure Chamber 15 Discharge element 130 Supply Channel 140 Recovery channel 500 Circulation Pump 801 Temperature control heater 802 Temperature Sensor

Claims

1. An inkjet recording method for recording an image on a recording medium by ejecting an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from a liquid ejection head, the method comprising: The liquid ejection head includes: an element substrate having an ejection port for ejecting the aqueous reaction liquid, a pressure chamber for supplying liquid to the ejection port, and an ejection element for generating energy for ejecting the liquid; an upstream flow path for supplying liquid to the pressure chamber; a downstream flow passage communicating with the pressure chamber; a pump communicating with the upstream flow path and the downstream flow path and configured to cause liquid in the downstream flow path to flow into the upstream flow path; a temperature adjusting means configured to be capable of heating the aqueous ink or the aqueous reaction liquid; An ink-jet recording method comprising the steps of:

2. a reaction liquid ejection step of ejecting the aqueous reaction liquid from the ejection port onto the recording medium; The inkjet recording method according to claim 1 , further comprising: an ink applying step of applying the aqueous ink so as to overlap at least a portion of an area of ​​the recording medium to which the aqueous reaction liquid is applied.

3. The inkjet recording method according to claim 1 , wherein the viscosity of the aqueous ink at 25° C. is higher than the viscosity of the aqueous reaction liquid at 25° C.

4. The ink jet recording method according to claim 1 , wherein the temperature adjusting means is provided on the element substrate.

5. The ink jet recording method according to claim 4 , wherein the element substrate includes a temperature sensor configured to be able to measure a temperature of the ejection element substrate.

6. the element substrate comprises a first ejection port array in which a plurality of the ejection ports for ejecting the water-based ink are arranged, and a second ejection port array in which a plurality of the ejection ports for ejecting the water-based reaction liquid are arranged, 5. The ink jet recording method according to claim 4, wherein the temperature adjusting means is provided corresponding to each of the first ejection port array and the second ejection port array.

7. the element substrate has a plurality of ejection port arrays in which the ejection ports are arranged, the plurality of ejection opening arrays include a first ejection opening array in which a plurality of the ejection openings for ejecting the water-based ink are arranged, and a second ejection opening array in which a plurality of the ejection openings for ejecting the water-based reaction liquid are arranged, The inkjet recording method according to claim 1 , wherein the second ejection port array is disposed at an end in an arrangement direction of the plurality of ejection port arrays.

8. The liquid ejection head includes: a plurality of element substrates including a first element substrate for ejecting the water-based ink and a second element substrate for ejecting the reaction liquid; The inkjet recording method according to claim 1 , wherein the second element substrate is disposed at an end in an arrangement direction of the plurality of element substrates.

9. The liquid ejection head includes: A discharge unit including the element substrate; a circulation unit including the pump and configured to circulate liquid between the discharge unit and the circulation unit; having The ink jet recording method according to claim 1 , wherein the temperature adjusting means is provided within the circulation unit.

10. The inkjet recording method according to claim 9 , wherein the circulation unit is provided for each type of liquid ejected from the ejection port.

11. The ink jet recording method according to claim 1, wherein a volume of the liquid flowing through the circulation path is from 5 mL to 30 mL.

12. 2. The ink jet recording method according to claim 1, wherein the temperature adjusting means is provided outside the head.

13. The inkjet recording method according to claim 1 , further comprising a liquid storage section configured to supply the aqueous ink or the aqueous reactive liquid to the liquid ejection head and connected to the liquid ejection head via a tube.

14. The ink jet recording method according to claim 8 , wherein the temperature adjusting means is provided in the liquid storage section.

15. The ink jet recording method according to claim 1 , wherein the pump is a piezoelectric pump.

16. 2. The ink jet recording method according to claim 1, wherein the liquid ejection head is configured to eject the liquid while scanning in a scanning direction.

17. 6. The ink jet recording method according to claim 5, wherein the liquid ejection head further comprises a first pressure adjusting means configured to adjust the pressure of the liquid in the upstream flow path.

18. 12. The ink jet recording method according to claim 11, wherein the first pressure adjustment means comprises a first valve chamber, a first pressure control chamber, a first opening that connects the first valve chamber and the first pressure control chamber, and a first valve configured to be able to open and close the first opening.

19. 13. The ink jet recording method according to claim 12, wherein the first pressure control chamber has a surface partially constituted by a first flexible member configured to be displaceable, and includes a first pressure plate displaceable in conjunction with the first flexible member, and a first biasing member biasing the first pressure plate in a direction increasing a volume of the first pressure control chamber, and is configured to open and close the first valve in response to displacement of the first pressure plate and the first flexible member.

20. The inkjet recording method according to claim 1 , wherein the water-based ink contains titanium oxide.

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