Inkjet printing method

Abstract

The present disclosure relates to an inkjet printing method for printing an image on a printing medium by discharging an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from a liquid discharge head including an element substrate, upstream and downstream flow channels, a pump, and a temperature control unit. The element substrate includes a discharge port that discharges the aqueous reaction liquid, a pressure chamber that supplies the liquid to the discharge port, and a discharge element that generates energy for discharging the liquid. An upstream flow passage supplies liquid to the pressure chamber. The downstream flow passage is in communication with the pressure chamber. A pump is in communication with the upstream flow channel and the downstream flow channel and allows liquid in the downstream flow channel to flow into the upstream flow channel. A temperature control unit heats the aqueous ink or the aqueous reaction liquid.

Description

Technical Field

[0001] The present disclosure relates to inkjet printing methods. Background Art

[0002] In recent years, inkjet printing methods have been increasingly used in the so-called signage and display field, such as printing posters and large advertisements. In this field, the characteristic is that the printing area is wide compared to home inkjet printing devices. In addition, since the image must be eye-catching, ink that can print images with high color rendering properties is required.

[0003] In the field of signs and displays, non-absorbent printing media made of vinyl chloride (VC), polytrimethylene terephthalate (PET), etc., whose surfaces have little ink absorbency, are often used. Therefore, it is necessary to suppress blurring and unevenness of images on non-absorbent printing media. Hereinafter, printing media whose surfaces have little ink absorbency are also referred to as "non-absorbent printing media." In an inkjet printing method for printing on non-absorbent printing media, it is important to suppress blurring by preventing ink dots from being repelled on the printing medium. Therefore, after the ink is applied to the printing medium, it is necessary to quickly thicken and solidify the ink.

[0004] As a method for printing on a non-absorbent printing medium, a printing 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 perspective of environmental load and safety, there is an increasing demand for a printing method capable of printing on a non-absorbent printing medium using an aqueous ink.

[0005] Examples of methods for printing on non-absorbent print media using aqueous ink include methods for evaporating water in the ink on the surface of the non-absorbent print medium and methods using a reactive liquid that condenses the components of the ink. The former does not require the provision of a device for applying the reactive liquid, and is therefore advantageous from the perspective of running costs, but requires a reduction in printing speed, and thus has poor productivity. Therefore, methods using reactive liquids are being studied.

[0006] In order to improve productivity, it is necessary to shorten the time required for maintenance of the liquid discharge head and realize continuous printing. In order to suppress the reduction of discharge performance due to thickening of the reaction liquid or ink at the discharge port that is not mainly used or solidification of the components (such as pigments and resins) in the reaction liquid or ink during continuous printing, it is necessary to maintain the liquid discharge head. Therefore, it is necessary to use a reaction liquid, and it is also necessary to have an inkjet printing method that can maintain stable discharge without interrupting printing even during long-term continuous printing.

[0007] In addition, in the past, a liquid discharge head has been proposed, which has a mechanism for causing ink to flow near a discharge port of the liquid discharge head so as to suppress ink components (such as pigments and resins) from being retained in the ink flow channel of the liquid discharge head (see Japanese Patent Laid-Open No. 2007-118611). In addition, in order to improve the cleanability of the discharge port for discharging the reaction liquid, an inkjet printing method using a liquid discharge head including a circulation flow channel has been proposed (see Japanese Patent Laid-Open No. 2020-104487).

[0008] The inventors studied various characteristics of a liquid discharge head having a mechanism for causing ink to flow near the discharge port of a liquid discharge head described in Japanese Patent Laid-Open No. 2007-118611 and an inkjet printing method using a liquid discharge head described in Japanese Patent Laid-Open No. 2020-104487. It was found that in the configuration described in Japanese Patent Laid-Open No. 2007-118611, intermittent discharge stability of the reaction liquid can be obtained to a certain extent, but image unevenness will occur. It was also found that in Japanese Patent Laid-Open No. 2020-104487, although a circulating flow channel was provided, the intermittent discharge stability of the reaction liquid was insufficient because no ink flow was generated near the discharge port. "Insufficient intermittent discharge stability of the reaction liquid" means that when the state in which the reaction liquid is not discharged for a certain period of time continues, the liquid component in the reaction liquid evaporates from a part of the discharge port, and the discharge state of the reaction liquid discharged from the discharge port gradually becomes unstable. That is, intermittent discharge stability refers to a characteristic that does not cause unstable discharge or discharge failure of the reaction liquid even in the above state and hardly causes quality degradation of the printed image. Summary of the invention

[0009] The present disclosure provides an inkjet printing method capable of maintaining stable discharge of a reaction liquid and suppressing the occurrence of image unevenness.

[0010] According to one aspect of the present disclosure, an inkjet printing method is provided, which is used to print an image on a printing medium by discharging each of aqueous ink and aqueous reactive liquid containing a reactant that reacts with the aqueous ink from a liquid discharge head, wherein the liquid discharge head includes: an element substrate, the element substrate including a discharge port for discharging the aqueous reactive liquid, a pressure chamber for supplying liquid to the discharge port, and a discharge element for generating energy for discharging the liquid; an upstream flow channel for supplying liquid to the pressure chamber; a downstream flow channel connected to the pressure chamber; a pump, the pump being connected to the upstream flow channel and the downstream flow channel; and a temperature control unit, the temperature control unit being configured to heat the aqueous ink or the aqueous reactive liquid, and the inkjet printing method includes operating the pump to cause the liquid in the downstream flow channel to flow into the upstream flow channel.

[0011] Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1A It is a perspective view for explaining the liquid discharge device.

[0013] Figure 1B is a block diagram showing a control system of the liquid discharge device.

[0014] Figure 2 is an exploded perspective view of the liquid discharge head.

[0015] Figure 3A A vertical cross section of the liquid discharge head is shown.

[0016] Figure 3B is an enlarged cross-sectional view of the discharge module.

[0017] Figure 4 This is a schematic diagram of the appearance of the cycle unit.

[0018] Figure 5 is a vertical cross-sectional view showing the circulation path.

[0019] Figure 6 is a block diagram schematically illustrating a cycle path.

[0020] Figures 7A to 7C is a cross-sectional view showing an example of a pressure regulating unit.

[0021] Fig. 8A and 8B This is a perspective view of the circulation pump.

[0022] Fig. 9 yes Fig. 8A A cross-sectional view of the circulating pump along line IX-IX is shown.

[0023] Figures 10A to 10E It is a diagram for explaining the flow of ink in the liquid discharge head.

[0024] Fig.11A and 11B is a schematic diagram showing a circulation path in the discharge unit.

[0025] Fig.12 3 is a diagram showing the opening plate 330 .

[0026] Fig.13 It is a diagram showing a discharge element substrate.

[0027] Figures 14A to 14C is a cross-sectional view showing the flow of ink in the discharge unit.

[0028] Fig.15A and 15B is a cross-sectional view showing the vicinity of the discharge port.

[0029] Fig.16A and 16B is a cross-sectional view showing a comparative example near a discharge port.

[0030] Fig.17 It is a diagram showing a comparative example of a discharge element substrate.

[0031] Fig.18A and 18B is a diagram showing a flow channel configuration of a liquid discharge head.

[0032] Fig.19 It is a diagram showing a connection state of a main body portion of a liquid discharge device and a liquid discharge head.

[0033] Fig. 20 is a diagram showing a discharge element substrate including a temperature control unit. DETAILED DESCRIPTION

[0034] The present disclosure will now be described in detail by referring to embodiments.In the following description, aqueous ink and reaction liquid for inkjet printing may be referred to simply as "ink" and "reaction liquid", respectively.

[0035] The present inventors have studied problems arising in liquid discharge heads such as those described in Japanese Patent Laid-Open Nos. 2007-118611 and 2020-104487. As a result, it is believed that by using a liquid discharge head having the following configuration and allowing the reaction liquid to flow in the liquid discharge head, the intermittent discharge stability of the reaction liquid can be improved, and the occurrence of image unevenness can be suppressed. Specifically, the liquid discharge head to be used includes: a discharge port for discharging the reaction liquid; a pressure chamber including a discharge element for generating energy for discharging the reaction liquid; an upstream flow channel for supplying liquid to the pressure chamber; a downstream flow channel connected to the pressure chamber; and a pump, the pump being connected to the upstream flow channel and the downstream flow channel and configured so that the liquid in the downstream flow channel flows into the upstream flow channel.

[0036] Will refer to Figure 5 Describe the flow of the reaction liquid. Figure 5 is a cross-sectional view showing the vicinity of a discharge port 13 in an example of a liquid discharge head of the present disclosure described later. Figure 5 The liquid discharge head shown includes: a discharge port 13 for discharging a reaction liquid; a pressure chamber 12 including a discharge element 15 that generates energy for discharging the reaction liquid; and a common supply channel 18 (upstream flow channel) and a common recovery channel 19 (downstream flow channel) that communicate with each other between the discharge port 13 and the discharge element 15 and in which the reaction liquid flows. The reaction liquid passes between the discharge port 13 and the discharge element 15 and in the common supply channel 18 and the common recovery channel 19 (along the Figure 5 When the reaction liquid does not flow, the liquid component from the meniscus at the discharge port 13 evaporates, and the reaction liquid between the discharge port 13 and the discharge element 15 gradually thickens. Therefore, if the discharge interval is long, the liquid resistance of the reaction liquid in the subsequent discharge operation increases, and the discharge of the liquid may become difficult. On the other hand, when the reaction liquid flows, the reaction liquid is Figure 5 Therefore, even if the liquid component evaporates from the meniscus, the reaction liquid is continuously supplied to between the discharge port 13 and the discharge element 15 by the flow of the reaction liquid. Therefore, the reaction liquid can be prevented from thickening and it can be difficult to cause discharge difficulties. Therefore, the intermittent discharge stability can be improved.

[0037] The flow rate (mm / s) of the reaction liquid in the pressure chamber 12 may be 1.0 mm / s or more and 50.0 mm / s or less. When the flow rate of the reaction liquid is less than 1.0 mm / s, insufficient reaction liquid is supplied to the vicinity of the meniscus, and intermittent discharge stability may not be obtained due to the influence of evaporation. When the flow rate of the reaction liquid is greater than 50.0 mm / s, the flow rate is too high, changes in the physical properties of the reaction liquid due to evaporation are prone to occur, and image unevenness cannot be fully prevented.

[0038] The inventor's research also showed that the use of a liquid discharge head in which a reaction liquid flows improves intermittent discharge stability, but the discharge balance between the reaction liquid and the ink is destroyed due to the difference in viscosity between the reaction liquid and the ink, and image unevenness may occur. In response to this problem, the inventor studied a method for solving the problem by configuring a liquid discharge device for discharging ink and reaction liquid, and obtained a method in which a temperature control unit for ink or reaction liquid is provided for the liquid discharge device. The details of the temperature control unit will be described below.

[0039] Inkjet printing method

[0040] The inkjet printing method disclosed herein is a method for printing an image on a print medium by discharging an aqueous ink and an aqueous reaction liquid described below from a liquid discharge head of an inkjet system. The method may include a reaction liquid discharge step of discharging an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from a discharge port to the print medium and an ink application step of applying the aqueous ink to overlap at least a portion of the area to which the aqueous reaction liquid is applied. In addition, the reaction liquid discharge step may be performed before the ink application step, or the ink application step and the reaction liquid discharge step may be performed in parallel. In the present disclosure, there is no need to provide a step of hardening the image by irradiating with active energy rays or the like.

[0041] There is no particular limitation on the print medium, and a transparent or colored print medium can be used. The print medium can be a poorly absorbent medium (non-absorbent medium) with low liquid medium absorbency, such as a resin film. The unit area where ink is applied to the print medium can be a multi-pass printing in which relative scanning of the liquid discharge head and the print medium is performed multiple times. In particular, when white ink is used as described below, the application of white ink to the unit area and the application of colored ink or aqueous reaction liquid to the unit area can be performed by different relative scanning. Therefore, the time required until various inks contact each other becomes longer, which tends to inhibit their mixing. The unit area can be set to an arbitrary area such as a pixel or a band.

[0042] (1) Liquid discharge device

[0043] With respect to a liquid discharge device (inkjet printing device) that can be used in the inkjet printing method of the present disclosure, a suitable embodiment of the present disclosure will now be described in detail with reference to the accompanying drawings. The following embodiments do not limit the subject matter of the present disclosure, and not all combinations of the features described in the embodiments are essential to the solution of the present disclosure. The same components are given the same figure marks. In the present embodiment, a thermal system for discharging liquid by generating bubbles through an electrothermal conversion element will be described as an example of a discharge element for discharging liquid, but the discharge element is not limited to this. The present disclosure can also be applied to a liquid discharge head that uses a discharge system that uses a piezoelectric element (piezoelectric) to discharge liquid or another discharge system. In addition, the pump, pressure control unit, etc. described below are also not limited to the configuration itself described in the embodiments and the accompanying drawings.

[0044] Liquid discharge device

[0045] Figure 1A and 1B is a diagram for explaining a liquid discharge device, and Figure 1A This is an enlarged view of the liquid discharge head and its vicinity of the liquid discharge device. Figure 1A and 1B A schematic configuration of the liquid discharge device 50 according to the present embodiment is described. Figure 1A 1 is a perspective view schematically showing a liquid discharge device using a liquid discharge head 1. The liquid discharge device 50 of the present embodiment constitutes a tandem inkjet printing device, which performs printing on a print medium P by discharging ink or a reaction liquid (described later) as a liquid while scanning the liquid discharge head 1. In the following, the "liquid" in the present disclosure includes ink and a reaction liquid containing a reactant that reacts with the ink. In addition, in the following description, the term "ink" can be used in a manner including ink and a reaction liquid. The liquid discharge head 1 is loaded on a carriage 60. The carriage 60 reciprocates along a guide shaft 51 in a main scanning direction (X direction). The print medium P is transported by conveying rollers 55, 56, 57 and 58 in a sub-scanning direction (Y direction) that intersects (orthogonally in this example) the main scanning direction. In each of the figures referenced below, the Z direction indicates a vertical direction and intersects (orthogonally in this example) an XY plane defined by the X direction and the Y direction. The liquid discharge head 1 is configured to be detachable and attached to the carriage 60 by a user.

[0046] The liquid discharge head 1 is connected by a circulation unit 54 and a discharge unit 3 described later (see Figure 2 Although a specific configuration will be described later, the discharge unit 3 is provided with a plurality of discharge ports and an energy generating element (hereinafter, referred to as a discharge element) that releases discharge energy for discharging liquid through each of the discharge ports.

[0047] The liquid discharge device 50 is provided with the ink cartridge 2 (liquid storage portion) and the external pump 21 as a liquid supply source, and the liquid stored in the ink cartridge 2 is supplied to the circulation unit 54 via the supply pipe 59 by the driving force of the external pump 21 .

[0048] The liquid discharge device 50 forms a prescribed image on the print medium P by repeating the printing scan and the conveying operation of conveying the print medium P along the sub-scanning direction. The liquid discharge head 1 loaded on the carriage 60 performs printing by discharging liquid while moving along the main scanning direction during the printing scan. The liquid discharge head 1 in the present embodiment is configured to be able to discharge four types of liquids including ink and reaction liquid. However, the configuration of the inkjet printing device in the present disclosure is not limited to an inkjet printing device that discharges four types of liquids. For example, an example is given in which black (K), cyan (C), magenta (M) and yellow (Y) ink and reaction liquid can be discharged. In this case, a full-color image can be printed by these inks. However, the liquid that can be discharged from the liquid discharge head 1 is not limited to the above-mentioned four types of ink and reaction liquid. The present disclosure can also be applied to liquid discharge heads that discharge other types of ink and reaction liquid.

[0049] That is, the type and amount of liquid discharged from the liquid discharge head are not limited.

[0050] The liquid discharge device 50 is provided with a cap member (not shown) capable of covering the discharge port surface of the liquid discharge head, wherein the discharge port is formed at a position deviated in the X direction from the conveying path of the printing medium P. The cap member covers the discharge port surface of the liquid discharge head 1 during non-printing operation and is used for drying prevention and protection of the discharge port, operation of sucking liquid from the discharge port, and the like.

[0051] Figure 1A The liquid discharge head 1 shown is an example in which four circulation units 54 corresponding to four types of liquids are provided to the liquid discharge head 1, and it is sufficient to provide the circulation unit 54 according to the type of liquid to be discharged. A plurality of circulation units 54 may be provided for the same type of liquid. That is, the liquid discharge head 1 may be configured to include one or more circulation units. This configuration may be used to circulate only at least one reaction liquid, rather than all four types of liquids.

[0052] Figure 1B1 is a block diagram showing a control system of the liquid discharge device 50. The CPU 103 is used as a control device for controlling the operation of various parts of the liquid discharge device 50 based on a program such as a processing procedure stored in the ROM 101. When the CPU 103 performs processing, the RAM 102 is used as a work area, etc. The CPU 103 receives image data from a host device 400 outside the liquid discharge device 50 to control the head driver 1A, and controls the driving of the discharge element provided to the discharge unit 3. The CPU 103 also controls the drivers of various actuators provided in the liquid discharge device. For example, the CPU 103 controls a motor driver 105A such as a carriage motor 105 for moving the carriage 60 and a motor driver 104A for a conveying motor 104 for conveying the print medium P. In addition, the CPU 103 controls a pump driver 500A such as a pump driver 500 for driving the circulation pump 500 described later and a pump driver 21A for driving the external pump 21. Figure 1B A configuration for executing processing of image data received from the host device 400 is shown, but processing may be executed by the liquid discharge device 50 not based on data from the host device 400 .

[0053] Basic configuration of liquid discharge head

[0054] Figure 2 is an exploded perspective view of the liquid discharge head 1 of the present embodiment. Figure 3A yes Figure 2 FIG. 1 is a cross-sectional view of the liquid discharge head 1 taken along line IIIA-IIIA. Figure 3A is an overall vertical sectional view of the liquid discharge head 1, and Figure 3B yes Figure 3A FIG. 3 is an enlarged view of the discharge module 300 shown in FIG. Figure 2 , Figure 3A and Figure 3B and appropriate reference Figure 1A and Figure 1B A basic configuration of the liquid discharge head 1 in this embodiment will be described.

[0055] like Figure 2 As shown in FIG. 1 , the liquid discharge head 1 is configured to include a circulation unit 54 and a discharge unit 3 for discharging ink supplied from the circulation unit 54 onto a printing medium P. The liquid discharge head 1 according to the present embodiment is fixed to and supported by the carriage 60 by a positioning device (not shown) and an electrical contact provided to the carriage 60 of the liquid discharge device 50. The liquid discharge head 1 is moved along the carriage 60 together with the carriage 60. Figure 1A The ink is discharged to perform printing on the printing medium P while moving in the main scanning direction (X direction) shown.

[0056] The supply tube 59 is provided to the external pump 21 connected to the ink cartridge 2 (see Figure 1A ). A liquid connector (not shown) is provided at the end of the supply pipe 59. When the liquid discharge head 1 is loaded onto the liquid discharge device 50, the liquid connector provided to the end of the supply pipe 59 is airtightly connected to the liquid connector insertion port 53a, which is an inlet for liquid provided to the head housing 53 of the liquid discharge head 1. Thus, an ink supply path is formed starting from the ink cartridge 2, passing through the external pump 21 and reaching the liquid discharge head 1. In the present embodiment, since four types of liquids are used, four groups of ink cartridges 2, external pumps 21, supply pipes 59 and circulation units 54 are provided to correspond to the four types of liquids, respectively, and four ink supply paths corresponding to the corresponding liquids are independently formed. Therefore, the liquid discharge device 50 of the present embodiment includes a liquid supply system to which liquid is supplied from the ink cartridge 2 provided outside the liquid discharge head 1. The liquid discharge device 50 of the present embodiment does not include an ink recovery system for recovering the liquid in the liquid discharge head 1 in the ink cartridge 2. Therefore, the liquid discharge head 1 is provided with a liquid connector insertion port 53a for connecting the supply tube 59 of the ink cartridge 2, but is not provided with a connector insertion port for connecting with a tube for recovering the ink in the liquid discharge head 1 in the ink cartridge 2. The liquid connector insertion port 53a is provided for each ink.

[0057] exist Figure 3A 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. These circulation units have substantially the same configuration, and when the circulation units are not particularly distinguished, they are all referred to as the circulation unit 54 in this embodiment.

[0058] like Figure 3A and Figure 3B As shown, when the liquid discharge head includes both the circulation unit 54 for ink and the circulation unit 54 for the reaction liquid, the circulation unit 54 for the reaction liquid can be located at the end in the arrangement direction of the plurality of circulation units 54. In the printing operation, the reaction liquid is applied to the printing medium by the reaction liquid discharge step of discharging the aqueous reaction liquid from the discharge port to the printing medium, and then the ink application step of applying the aqueous ink can be performed in a manner overlapping at least a portion of the area where the aqueous reaction liquid is applied. In such a case, the circulation unit for the reaction liquid is located at the end, which makes it possible to perform efficient printing.

[0059] exist Figure 2 and Figure 3AIn the embodiment, 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. Figure 3B As shown, 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 surface of the silicon substrate 310. The discharge element 15 in this embodiment is composed of an electrothermal conversion element (heater) that generates heat energy as discharge energy for discharging liquid. Power is supplied to each discharge element 15 through an electric wiring formed on the silicon substrate 310 by a film forming technology.

[0060] The outlet forming member 320 is formed on the surface of the silicon substrate 310 ( Figure 3B In the discharge port forming component 320, a plurality of pressure chambers 12 corresponding to a plurality of discharge elements 15 and a plurality of discharge ports 13 for discharging liquid are formed by photolithography technology. In addition, in the silicon substrate 310, a common supply channel 18 and a common recovery channel 19 are formed. In addition, in the silicon substrate 310, a supply connection channel 323 communicating between the common supply channel 18 and each pressure chamber 12 and a recovery connection channel 324 communicating between the common recovery channel 19 and each pressure chamber 12 are formed. In the configuration of the present embodiment, one discharge module 300 performs the discharge of two types of liquids. That is, in Figure 3A Of the two discharge modules shown, the discharge module 300 located on the left side of the figure discharges the first ink and the second ink, and the discharge module 300 located on the right side of the figure discharges the third ink and the reaction liquid. This combination is an example, and the ink and the reaction liquid may be any combination. A configuration in which one discharge module discharges one type of liquid may be adopted, or a configuration in which one discharge module discharges three or more types of liquids may be adopted. The two discharge modules 300 do not need to discharge the same number of types of liquids. A configuration including one discharge module 300 may be adopted, or a configuration including three or more discharge modules 300 may be adopted. In addition, in Figure 3A and 3B In the example shown, two discharge port arrays extending in the Y direction are formed for one type of liquid. A pressure chamber 12, a common supply channel 18, and a common recovery channel 19 are formed for each of the plurality of discharge ports 13 constituting each discharge port array.

[0061] A liquid supply port and a liquid recovery port described later are formed on the rear surface ( Figure 3B The liquid supply port supplies liquid from the liquid supply channel 48 to the plurality of common supply channels 18, and the liquid recovery port recovers liquid from the plurality of common recovery channels 19 to the liquid recovery channel 49.

[0062] The liquid supply port and liquid recovery port mentioned in this article refer to openings for supplying liquid and recovering liquid during the forward liquid circulation described later. That is, in the forward liquid circulation, liquid is supplied from the liquid supply port to each common supply channel 18, and liquid is recovered from each common recovery channel 19 to the liquid recovery port. However, a liquid circulation in which the liquid flows in the reverse direction can also be performed. In this case, liquid is supplied from the above-mentioned liquid recovery port to the common recovery channel 19, and liquid is recovered from the common supply channel 18 to the liquid supply port.

[0063] like Figure 3A As shown, the rear surface ( Figure 3A The top surface of the first support member 4 is bonded and fixed to one surface ( Figure 3A bottom surface in the middle).

[0064] The first supporting member 4 is formed with a liquid supply channel 48 and a liquid recovery channel 49 penetrating from one surface thereof to the other surface. One opening of the liquid supply channel 48 communicates with the above-mentioned liquid supply port of the silicon substrate 310, and one opening of the liquid recovery channel 49 communicates with the above-mentioned liquid recovery port of the silicon substrate 310. The liquid supply channel 48 and the liquid recovery channel 49 are independently provided for each type of liquid.

[0065] With opening 7a (see Figure 2 ) is used to allow the discharge module 300 to be inserted into the second support member 7, which is adhesively fixed to one surface of the first support member 4 ( Figure 3A top surface in the ).

[0066] The second supporting member 7 holds the electric wiring member 5 electrically connected to the discharge module 300. The electric wiring member 5 is a member for applying an electric signal for discharging liquid to the discharge module 300. The electrical connection portion between the discharge module 300 and the electric wiring member 5 is sealed with a sealing material (not shown) and protected from liquid corrosion and external impact.

[0067] The electric contact substrate 6 is thermally compressed to the end portion 5a of the electric wiring member 5 using an anisotropic conductive film (not shown). Figure 2 ) to electrically connect between the electric wiring member 5 and the electric contact substrate 6. The electric contact substrate 6 includes an external signal input terminal (not shown) for receiving an electric signal from the liquid discharge device 50.

[0068] In addition, the joint part 8 ( Figure 3A) is disposed between the first support member 4 and the circulation unit 54. The joint member 8 is formed with a supply port 88 and a recovery port 89 for various types of liquids. The supply port 88 and the recovery port 89 communicate between the liquid supply channel 48 and the liquid recovery channel 49 of the first support member 4 and the flow channel formed in the circulation unit 54. Figure 3A 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. 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.

[0069] The opening at one end of each of the liquid supply channel 48 and the liquid recovery channel 49 of the first support member 4 has a small opening area adjusted according to the liquid supply port and the liquid recovery port in the silicon substrate 310. In contrast, the shape of the opening at the other end of each of the liquid supply channel 48 and the liquid recovery channel 49 of the first support member 4 has an expanded opening area, which is the same as the large opening area of ​​the joint member 8 formed to adjust the flow channel of the circulation unit 54. In such a configuration, the increase in the flow channel resistance to the liquid recovered from each recovery channel can be suppressed. However, the shape of the opening at one end and the opening at the other end of each of the liquid supply channel 48 and the liquid recovery channel 49 is not limited to the above example.

[0070] In the liquid discharge head 1 having the above-described configuration, the liquid supplied to the circulation unit 54 passes through the supply port 88 of the joint member 8 and the liquid supply channel 48 of the first support member 4, and flows into the common supply channel 18 through the liquid supply port of the discharge module 300. Subsequently, the liquid flows from the common supply channel 18 into the pressure chamber 12 through the supply connection channel 323, and a portion of the liquid that has flowed into the pressure chamber is discharged from the discharge port 13 by the drive of the discharge element 15. The remaining liquid that is not discharged flows out of the pressure chamber 12, passes through the recovery connection channel 324 and the common recovery channel 19, and flows into the liquid recovery channel 49 of the first support member 4 through the liquid recovery port. Then, the liquid that has flowed into the liquid recovery channel 49 flows into the circulation unit 54 through the recovery port 89 or the joint member 8 and is recovered.

[0071] Components of a circulation unit

[0072] Figure 4 5 is a schematic diagram of the appearance of a circulation unit 54 corresponding to a type of liquid applied to the printing device of this embodiment. In addition to the circulation pump 500, the circulation unit 54 may also include a filter 110, a first pressure control unit 120 and a second pressure control unit 150. These components are as follows: Figure 5 and Figure 6The liquid discharge module 300 is connected to each flow channel and constitutes a circulation path for performing supply and recovery of liquid to the liquid discharge module 300 in the liquid discharge head 1 .

[0073] Circulation path in liquid discharge head

[0074] Figure 5 1 is a vertical cross-sectional view schematically showing a circulation path for one type of liquid (one color of ink or reaction liquid) configured in the liquid discharge head 1. In order to more clearly illustrate the circulation path, the Figure 5 The relative positions of the various components (such as the first pressure control unit 120, the second pressure control unit 150 and the circulation pump 500) in FIG. Therefore, the relative positions of the various components are different from those described later. Fig.19 Configuration in . Figure 6 It is schematically shown Figure 5 The block diagram of the loop path shown in Figure 5 and Figure 6 As shown, the first pressure control unit 120 includes a first valve chamber 121 and a first pressure control chamber 122. The second pressure control unit 150 includes a second valve chamber 151 and a second pressure control chamber 152. The first pressure control unit 120 is configured so that the control pressure is relatively higher than the control pressure of the second pressure control unit 150. In the present embodiment, circulation within a certain pressure range is achieved in the circulation path by using these two pressure control units 120 and 150. It is configured so that the ink flows in the pressure chamber 12 (discharge element 15) at a flow rate obtained according to the pressure difference between the pressures in the first pressure control unit 120 and the second pressure control unit 150. Now, reference will be made to Figure 5 and Figure 6 The circulation path in the liquid discharge head 1 and the flow of the liquid in the circulation path are described. The arrows in the respective drawings indicate the direction in which the liquid flows.

[0075] The connection state of the respective components in the liquid discharge head 1 will be described.

[0076] The external pump 21 is connected to the circulation unit 54 through a supply pipe 59 ( FIG. 1 ), and the external pump 21 pumps the ink stored in the ink cartridge 2 ( FIG. 1 ) provided outside the liquid discharge head 1. Figure 6 ) is delivered to the liquid discharge head 1. The flow channel (inlet flow channel) located upstream of the circulation unit 54 is provided with a filter 110. The liquid supply path (inlet flow channel) located downstream of the filter 110 is connected to the first valve chamber 121 of the first pressure control unit 120. The first valve chamber 121 is connected to the first pressure control chamber 122 through the communication port 191A, and the communication port 191A can be Figure 5The valve 190A shown opens and closes. The inlet flow channel is a flow channel into the liquid discharge head 1 for supplying the liquid in the ink cartridge 2 provided outside the liquid discharge head 1 to the pressure chamber 12.

[0077] The first pressure control chamber 122 is connected to the supply channel 130, the bypass flow channel 160, and the pump outlet channel 180 of the circulation pump 500. The supply channel 130 is connected to the common supply channel 18 through the above-mentioned liquid supply port provided to the discharge module 300. The bypass flow channel 160 is connected to the second valve chamber 151 provided in the second pressure control unit 150. The second valve chamber 151 is connected to the second pressure control chamber 152 through the communication port 191B, and the communication port 191B is connected to the second pressure control chamber 152. Figure 5 Valve 190B is shown open and closed. Figure 5 and Figure 6 An example is shown in which one end of the bypass flow channel 160 is connected to the first pressure control chamber 122 of the first pressure control unit 120 and the other end of the bypass flow channel 160 is connected to the second valve chamber 151 of the second pressure control unit 150. One end of the bypass flow channel 160 may be connected to the supply channel 130, and the other end of the bypass flow channel may be connected to the second valve chamber 151.

[0078] The second pressure control chamber 152 is connected to the recovery channel 140. The recovery channel 140 is connected to the common recovery channel 19 through the above-mentioned liquid recovery port provided in the discharge module 300. In addition, the second pressure control chamber 152 is connected to the circulation pump 500 through the pump inlet channel 170. Figure 5 , reference numeral 170 a indicates an inlet of the pump inlet passage 170 .

[0079] Next, the flow of liquid in the liquid discharge head 1 having the above-described configuration will be described. Figure 6 As shown, the liquid stored in the ink cartridge 2 is pressurized by the external pump 21 provided in the liquid discharge device 50, and is supplied to the circulation unit 54 of the liquid discharge head 1 as a positive-pressure liquid flow.

[0080] The liquid supplied to the circulation unit 54 passes through the filter 110 to remove foreign matter such as dust and bubbles, and then flows into the first valve chamber 121 provided in the first pressure control unit 120. Although the pressure of the liquid decreases due to pressure loss when passing through the filter 110, the liquid pressure at this stage is in a positive pressure state. Subsequently, when the valve 190A is in an open state, the liquid flowing into the first valve chamber 121 passes through the communication port 191A and flows into the first pressure control chamber 122. The liquid flowing into the first pressure control chamber 122 switches from a positive pressure state to a negative pressure state due to pressure loss when passing through the communication port 191A.

[0081] Next, the flow of liquid in the circulation path will be described. The circulation pump 500 operates to deliver the liquid sucked from the pump inlet channel 170 on the upstream side to the pump outlet channel 180 on the downstream side. Therefore, the liquid supplied to the first pressure control chamber 122 flows into the supply channel 130 and the bypass flow channel 160 together with the liquid delivered from the pump outlet channel 180 by driving the pump. Although the details will be described later, in the present 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 delivering liquid. The piezoelectric diaphragm pump is a pump that delivers liquid by applying a driving voltage to the piezoelectric element to change the volume of the pump chamber and thereby alternately moving two check valves through pressure changes.

[0082] The liquid flowing into the supply channel 130 passes through the common supply channel 18 and flows into the pressure chamber 12 through the liquid supply port of the discharge module 300, and a part of the liquid is discharged from the discharge port 13 by the driving (heat generation) of the discharge element 15. The remaining liquid not used in the discharge flows in the pressure chamber 12, passes through the common recovery channel 19, and then flows into the recovery channel 140 connected to the discharge module 300. The liquid flowing into the recovery channel 140 flows into the second pressure control chamber 152 of the second pressure control unit 150.

[0083] In contrast, the liquid flowing into the bypass flow channel 160 from the first pressure control chamber 122 flows into the second valve chamber 151, then passes through the communication port 191B, and flows into the second pressure control chamber 152. The liquid flowing into the second pressure control chamber 152 through the bypass flow channel 160 and the liquid recovered from the recovery channel 140 are sucked into the circulation pump 500 via the pump inlet channel 170 by the driving of the circulation pump 500. The liquid sucked into the circulation pump 500 is transported to the pump outlet channel 180 and flows into the first pressure control chamber 122 again. Thereafter, the liquid flowing into the second pressure control chamber 152 from the first pressure control chamber 122 through the supply channel 130 and then through the discharge module 300 and the liquid flowing into the second pressure control chamber 152 through the bypass flow channel 160 flow into the circulation pump 500. The liquid is then transported from the circulation pump 500 to the first pressure control chamber 122. Thus, circulation of the liquid in the circulation path is performed.

[0084] As described above, in the present embodiment, the liquid can be circulated along the circulation path formed in the liquid discharge head 1 by the circulation pump 500. Therefore, the thickening of the liquid and the accumulation of the sedimentation components of the colorant liquid in the discharge module 300 can be suppressed, and the fluidity of the liquid in the discharge module 300 and the good state of the discharge characteristics in the discharge port can be maintained.

[0085] The circulation path in this embodiment adopts a configuration completed in the liquid discharge head 1. Therefore, when the liquid circulates between the ink cartridge 2 provided outside the liquid discharge head and the liquid discharge head 1, the length of the circulation path can be significantly shortened, and the volume in the circulation path can be reduced. Therefore, the circulation of the liquid can be performed with a small-sized circulation pump such as a piezoelectric pump.

[0086] In addition, the connection channel of the liquid discharge head 1 and the ink cartridge 2 is configured to include only a flow channel for supplying liquid. That is, a configuration that does not require a flow channel for recovering liquid from the liquid discharge head 1 to the ink cartridge 2 is adopted. Therefore, it is sufficient to provide only a tube for liquid supply connected between the ink cartridge 2 and the liquid discharge head 1, and a tube for liquid recovery is not required. Therefore, the interior of the liquid discharge device 50 can have a simple configuration with a reduced number of tubes, and miniaturization of the entire device can be achieved. In addition, the reduction in the number of tubes can reduce the pressure change of the liquid caused by the vibration of the tube caused by the main scanning of the liquid discharge head 1. The vibration of the tube during the main scanning of the liquid discharge head 1 becomes a driving load of the carriage motor that drives the carriage 60. Therefore, the reduction in the number of tubes reduces the driving load of the carriage motor, and the main scanning mechanism including the carriage motor can be simplified. In addition, since it is not necessary to recover the liquid from the liquid discharge head to the ink cartridge, the size of the external pump 21 can also be reduced. Therefore, according to the present embodiment, while being configured so as to allow the liquid to circulate in the liquid discharge device 50, miniaturization and cost reduction can be achieved.

[0087] The flow rate for circulating the reaction liquid (circulation flow rate) is preferably 1.0 mL / min or more and 10.0 mL / min or less, and more preferably 2.0 mL / min or more and 5.0 mL / min or less.

[0088] Pressure control unit

[0089] Fig. 7A , Figure 7B and Figure 7C is a diagram showing an example of a pressure control unit. FIG. 7A to FIG. 7C , the configuration and function of the pressure control unit (the first pressure control unit 120 and the second pressure control unit 150) built in the above-mentioned liquid discharge head 1 will be described in more detail. The first pressure control unit 120 and the second pressure control unit 150 have basically the same configuration. Therefore, hereinafter, the first pressure control unit 120 will be described as an example, and with respect to the second pressure control unit 150, Figures 7A to 7C In the second pressure control unit 150 , the first valve chamber 121 to be described below is replaced by the second valve chamber 151 , and the first pressure control chamber 122 is replaced by the second pressure control chamber 152 .

[0090] The first pressure control unit 120 includes 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 from each other by a partition 123 provided in the cylindrical housing 125. However, the first valve chamber 121 is communicated with the first pressure control chamber 122 through a communication port 191 formed in the partition 123. The first valve chamber 121 is provided with a valve 190 that switches the communication and cutoff 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 is configured to be in close contact with the partition 123 by the biasing force of the valve spring 200. When the valve 190 is in close contact with the partition 123, the flow of liquid in the communication port 191 is cut off. In order to enhance the close contact with the partition 123, the contact portion of the valve 190 with the partition 123 may be formed of an elastic material. The valve shaft 190a inserted into the communication port 191 is provided in a protruding state at the center portion of the valve 190. The valve 190 is separated from the partition 123 by pressing the valve shaft 190a to overcome the biasing force of the valve spring 200, and liquid can flow in the communication port 191. Hereinafter, a state in which the flow of liquid through the communication port 191 is cut off by the valve 190 is referred to as a "closed state", and a state in which liquid flows through the communication port 191 is referred to as an "open state".

[0091] The opening portion of the cylindrical housing 125 is closed by the flexible member 230 and the pressing plate 210. The flexible member 230, the pressing plate 210, the peripheral wall of the housing 125 and the partition 123 form the first pressure control chamber 122. The pressing plate 210 is configured to be displaceable with the displacement of the flexible member 230. The materials of the pressing plate 210 and the flexible member 230 are not particularly limited. For example, the pressing plate 210 may be formed of a resin molded product, and the flexible member 230 may be formed of a resin film. In this case, the pressing plate 210 may be fixed to the flexible member 230 by thermal welding.

[0092] The pressure adjustment spring 220 (biasing member) is provided between the pressing plate 210 and the partition 123. The biasing force of the pressure adjustment spring 220 applies force to the pressing plate 210 and the flexible member 230 in the direction in which the internal volume of the first pressure control chamber 122 increases, such as Fig. 7A shown.

[0093] When the pressure in the first pressure control chamber 122 decreases, the pressing plate 210 and the flexible member 230 are displaced against the pressure of the pressure regulating spring 220 so that the internal volume of the first pressure control chamber 122 decreases. When the internal volume of the first pressure control chamber 122 decreases to a certain volume, the pressing plate 210 abuts against the valve shaft 190a of the valve 190. Subsequently, when the internal volume of the first pressure control chamber 122 decreases, the valve 190 moves together with the valve shaft 190a against the biasing force of the valve spring 200 and separates from the partition 123. As a result, the communication port 191 becomes an open state ( Figure 7B status shown).

[0094] In the present embodiment, the connection in the circulation path is set so that the pressure in the first valve chamber 121 is higher than the pressure in the first pressure control chamber 122 when the communication port 191 is in the open state.

[0095] Therefore, when the communication port 191 becomes an open state, liquid flows from the first valve chamber 121 into the first pressure control chamber 122. This liquid flow displaces the flexible member 230 and the pressing plate 210, so that the internal volume of the first pressure control chamber 122 increases. As a result, the pressing plate 210 is separated from the valve shaft 190a of the valve 190, the valve 190 is in close contact with the partition 123 by the biasing force of the valve spring 200, and the communication port 191 becomes a closed state ( Figure 7C status shown).

[0096] Therefore, in the first pressure control unit 120 of the present embodiment, when the pressure in the first pressure control chamber 122 is reduced to a certain pressure or less (for example, when the negative pressure becomes strong), the liquid flows from the first valve chamber 121 into the first pressure control chamber 122 through the communication port 191. Therefore, it is configured so that the pressure of the first pressure control chamber 122 does not further decrease. Therefore, the first pressure control chamber 122 is controlled to maintain the pressure within a certain range.

[0097] Next, the pressure in the first pressure control chamber 122 will be described in more detail.

[0098] As described above, considering the open state of the communication port 191 ( Figure 7B 190a), in which the flexible member 230 and the pressing plate 210 are displaced in response to the pressure in the first pressure control chamber 122, and the pressing plate 210 abuts against the valve shaft 190a. In this case, the relationship of the forces acting on the pressing plate 210 is expressed by the following formula 1:

[0099] P2×S2+F2+(P1-P2)×S1+F1=0 Formula 1

[0100] In addition, regarding P2, formula 1 is rearranged to give the following formula:

[0101] P2= -(F1+F2+P1×S1) / (S2-S1) Formula 2

[0102] P1: pressure of the first valve chamber 121 (gauge pressure);

[0103] P2: pressure of the first pressure control chamber 122 (gauge pressure);

[0104] F1: Spring force of valve spring 200;

[0105] F2: Spring force of the pressure regulating spring 220;

[0106] S1: the pressure receiving area of ​​valve 190; and

[0107] S2: The pressure receiving area of ​​the pressing plate 210 .

[0108] Here, the spring force F1 of the valve spring 200 and the spring force F2 of the pressure regulating spring 220 press the valve 190 and the pressing plate 210 ( FIG. 7A to FIG. 7C The left direction in the first valve chamber 121 is defined as positive. The pressure P1 in the first valve chamber 121 and the pressure P2 in the first pressure control chamber 122 are configured so that the pressure P1 ≥ P2 has a relationship.

[0109] The pressure P2 in the first pressure control chamber 122 when the communication port 191 becomes the open state is determined by Formula 2, and is configured so that when the communication port 191 becomes the open state, the relationship of P1 ≥ P2 is established. Therefore, the 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 further decrease, and the pressure P2 is maintained within a certain range.

[0110] In contrast, Figure 7C As shown, when the pressing plate 210 is not in contact with the valve shaft 190a and the communication port 191 is in a closed state, the relationship of the force acting on the pressing plate 210 is expressed by Formula 3:

[0111] P3×S3+F3=0 Formula 3

[0112] Here, regarding P3, formula 3 is sorted out to give the following formula:

[0113] P3=-F3 / S3 Formula 4

[0114] F3: spring force of the pressure regulating spring 220 when the pressing plate 210 and the valve shaft 190a are in a non-contact state;

[0115] P3: the pressure (gauge pressure) of the first pressure control chamber 122 when the pressing plate 210 and the valve shaft 190a are in a non-contact state; and

[0116] S3: The pressure receiving area of ​​the pressing plate 210 when the pressing plate 210 and the valve 190 are in a non-contact state.

[0117] here, Figure 7C The state in which the pressing plate 210 and the flexible member 230 are displaced to the right in the figure and reach the limit of possible displacement is shown. The pressure P3 in the first pressure control chamber 122, the spring force F3 of the pressure regulating spring 220, and the pressure receiving area S3 of the pressing plate 210 change according to the displacement amount until the pressing plate 210 and the flexible member 230 are displaced to the limit of possible displacement. Figure 7C Specifically, Figure 7C In contrast, when the pressing plate 210 and the flexible member 230 are Figure 7B When the pressure plate 210 is on the right side, the pressure area S3 of the pressing plate 210 decreases, and the spring force F3 of the pressure regulating spring 220 increases. As a result, the pressure P3 in the first pressure control chamber 122 decreases according to the relationship of Formula 4. Figure 7B The status shown changes to Figure 7C During the state shown, the pressure in the first pressure control chamber 122 gradually increases (that is, the negative pressure weakens and approaches the positive pressure side) according to Formula 2 and Formula 4. That is, the pressing plate 210 and the flexible member 230 gradually shift to the left direction from the state where the communication port 191 is in the open state, 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 the limit of possible displacement. That is, the negative pressure weakens.

[0118] Circulation pump

[0119] Next, we will refer to Fig. 8A , Figure 8B and Fig. 9 The configuration and function of the circulation pump 500 built in the above-described liquid discharge head 1 are described in detail.

[0120] Fig. 8A and 8B It is a perspective view of the appearance of the circulation pump 500. Fig. 8A is a perspective view showing the appearance of the front side of the circulation pump 500, and Figure 8B 1 is a perspective view showing the appearance of the rear side of the circulation pump 500 .

[0121] The housing 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 channel connecting component 505b bonded and fixed to the outer surface of the housing body 505a. A pair of through holes that are connected to each other are arranged at two different positions in each of the housing body 505a and the flow channel connecting component 505b. A pair of through holes arranged at one position forms a pump supply hole 501, and a pair of through holes arranged at another position forms a pump discharge hole 502. The pump supply hole 501 is connected to the pump inlet channel 170, which is connected to the second pressure control chamber 152, and the pump discharge hole 502 is connected to the pump outlet channel 180, which is connected to the first pressure control chamber 122. The liquid supplied through the pump supply hole 501 passes through the pump chamber 503 described later (see Fig. 9 ) and is discharged through the pump discharge hole 502.

[0122] Fig. 9 yes Fig. 8A IX-IX line cross-sectional view of the circulation pump 500 shown in FIG. The diaphragm 506 is joined to the inner surface of the pump housing 505, and the pump chamber 503 is formed between the diaphragm 506 and the recess formed on the inner surface of the pump housing 505. The pump chamber 503 is connected to the pump supply hole 501 and the pump discharge hole 502 formed in the pump housing 505. The check valve 504a is arranged at the middle part of the pump supply hole 501, and the check valve 504b is arranged at the middle part of the pump discharge hole 502. Specifically, the check valve 504a is arranged so that it can move to the left side in the figure in the space 512a partially formed at the middle part of the pump supply hole 501. The check valve 504b is arranged so that it can move to the right side in the figure in the space 512b partially formed at the middle part of the pump discharge hole 502.

[0123] When the volume of the pump chamber 503 is increased by the displacement of the diaphragm 506 to reduce the pressure in the pump chamber 503, the check valve 504a is separated from the opening of the pump supply hole 501 in the space 512a (i.e., moved to the left in the figure). The check valve 504a is separated from the opening of the pump supply hole 501 in the space 512a and becomes an open state that allows the liquid in the pump supply hole 501 to flow. By pressurizing the pump chamber 503 due to reducing the volume of the pump chamber 503 through the displacement of the diaphragm 506, the check valve 504a is in close contact with the wall around the opening of the pump supply hole 501. Therefore, the check valve 504a becomes a closed state in which the flow of liquid in the pump supply hole 501 is cut off.

[0124] In contrast, by reducing the pressure in the pump chamber 503, the check valve 504b is brought into close contact with the wall around the opening of the pump housing 505, and becomes a closed state in which the flow of liquid in the pump discharge hole 502 is cut off. When pressure is applied to the pump chamber 503, the check valve 504b is separated from the opening of the pump housing 505 and moves to the space 512b side (that is, moves to the right in the figure), and liquid can flow in the pump discharge hole 502.

[0125] The check valves 504a, 504b may be made of any material that can deform in response to the pressure in the pump chamber 503, and may be formed of, for example, an elastic material such as EPDM and elastomer, or a film or polypropylene sheet, etc. However, the material is not limited thereto.

[0126] As described above, the pump chamber 503 is formed by joining the pump housing 505 and the diaphragm 506. Therefore, the pressure in the pump chamber 503 is changed by the deformation of the diaphragm 506. For example, the diaphragm 506 is displaced to the pump housing 505 side (in the figure, it is displaced to the right side) to reduce the volume of the pump chamber 503, and the pressure in the pump chamber 503 is thereby increased. Therefore, the check valve 504b arranged to face the pump discharge hole 502 becomes an open state, and the liquid in the pump chamber 503 is discharged. In this case, since the check valve 504a arranged to face the pump supply hole 501 is in close contact with the wall around the pump supply hole 501, the liquid is prevented from flowing back from the pump chamber 503 to the pump supply hole 501.

[0127] In contrast, when the diaphragm 506 is displaced in the direction in which the pump chamber 503 expands, the pressure in the pump chamber 503 decreases. Therefore, the check valve 504a arranged to face the pump supply hole 501 becomes an open state to supply liquid to the pump chamber 503. In this case, the check valve 504b arranged in the pump discharge hole 502 is in close contact with the wall around the opening formed in the pump housing 505 to close the opening. Therefore, the liquid is prevented from flowing back from the pump discharge hole 502 to the pump chamber 503.

[0128] Therefore, in the circulation pump 500, the diaphragm 506 is deformed to change the pressure in the pump chamber 503, thereby performing the suction and discharge of the liquid. In this case, if the bubbles penetrate into the pump chamber 503, even when the diaphragm 506 is displaced, the pressure change in the pump chamber 503 will be reduced due to the expansion and contraction of the bubbles, thereby reducing the liquid feed amount. Therefore, the pump chamber 503 is arranged parallel to gravity, so that the bubbles that penetrate into the pump chamber 503 tend to gather at the top of the pump chamber 503, and the pump discharge hole 502 is arranged above the center of the pump chamber 503. Therefore, the ability to discharge the bubbles inside the pump can be improved, and the flow rate can be stabilized.

[0129] Flow of liquid in the liquid discharge head

[0130] FIG. 10A to FIG. 10E 2 is a diagram for explaining the flow of liquid in the liquid discharge head. FIG. 10A to FIG. 10E , the circulation of the liquid in the liquid discharge head 1 will be described. In order to more clearly describe the liquid circulation path, the FIG. 10A to FIG. 10E The relative positions of the components in the embodiment (such as the first pressure control unit 120, the second pressure control unit 150 and the circulation pump 500). Therefore, the relative positions of the components are different from those described later. Fig.19 Configuration shown. Fig. 10A The flow of liquid when the printing operation is performed by discharging the liquid from the discharge port 13 is schematically shown. The arrows in the drawings indicate the flow of liquid. In the present embodiment, when the printing operation is performed, both the external pump 21 and the circulation pump 500 are started to be driven. In a state where the printing operation is not performed, both the external pump 21 and the circulation pump 500 can be driven. The external pump 21 and the circulation pump 500 can be driven in connection with each other, but can also be driven separately and independently.

[0131] During the printing operation, the circulation pump 500 is in the "ON" state (driving state), and the liquid flowing out of the first pressure control chamber 122 flows into the supply channel 130 and the bypass flow channel 160. The liquid flowing into the supply channel 130 passes through the discharge module 300, and then flows into the recovery channel 140, and then is supplied to the second pressure control chamber 152.

[0132] On the other hand, the liquid flowing from the first pressure control chamber 122 into the bypass flow channel 160 flows into the second pressure control chamber 152 through the second valve chamber 151. The liquid flowing into the second pressure control chamber 152 passes through the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180, and then flows into the first pressure control chamber 122 again. In this case, based on the relationship of the above formula 2, the control pressure of the first valve chamber 121 is set to be higher than the control pressure in the first pressure control chamber 122. Therefore, the liquid in the first pressure control chamber 122 is supplied to the discharge module 300 again through the supply channel 130 without flowing into the first valve chamber 121. The liquid flowing into the discharge module 300 passes through the recovery channel 140, the second pressure control chamber 152, the pump inlet channel 170, the circulation pump 500, and the pump outlet channel 180, and then flows into the first pressure control chamber 122 again.

[0133] As described above, the liquid circulation completed within the liquid discharge head 1 is performed.

[0134] In the above-mentioned liquid circulation, the circulation amount (flow rate) of the liquid in the discharge module 300 is determined by the pressure difference between the control pressures of the first pressure control chamber 122 and the second pressure control chamber 152. The pressure difference is set to a circulation amount that can suppress the thickening of the liquid near the discharge port in the discharge module 300. The amount of liquid consumed by printing is supplied to the first pressure control chamber 122 from the ink cartridge 2 through the filter 110 and the first valve chamber 121. The mechanism for supplying the consumed liquid will be described in detail. The liquid in the circulation path reduces the amount of liquid consumed by printing, thereby reducing the pressure in the first pressure control chamber. As a result, the liquid in the first pressure control chamber 122 is also reduced. The reduction of the liquid in the first pressure control chamber 122 leads to a reduction in the internal volume of the first pressure control chamber 122. By this reduction in the internal volume of the first pressure control chamber 122, the communication port 191A becomes an open state, and the liquid is supplied to the first pressure control chamber 122 from the first valve chamber 121. When the liquid passes through the communication port 191A from the first valve chamber 121, a pressure loss is generated in the supplied liquid, and the liquid flows into the first pressure control chamber 122 to switch the liquid from a positive pressure state to a negative pressure state. Then, the liquid flows from the first valve chamber 121 into the first pressure control chamber 122 to increase the pressure in the first pressure control chamber, which increases the internal volume of the first pressure control chamber, resulting in a closed state of the communication port 191A. Therefore, the open state and the closed state of the communication port 191A are repeated according to the consumption of the liquid. When the liquid is not consumed, the communication port 191A remains in a closed state.

[0135] Fig. 10B The flow of liquid immediately after the printing operation ends and the circulation pump 500 is switched to the "OFF" state (stop state) is schematically shown. When the printing operation ends and the circulation pump 500 is switched to "OFF", the pressure in the first pressure control chamber 122 and the pressure in the second pressure control chamber 152 are both the control pressures during the printing operation. Fig. 10B As shown, the movement of the liquid occurs according to the pressure difference between the pressure of the first pressure control chamber 122 and the pressure of the second pressure control chamber 152. Specifically, the flow of the liquid that is supplied from the first pressure control chamber 122 to the discharge module 300 through the supply channel 130 and then passes through the recovery channel 140 and reaches the second pressure control chamber 152 continues. In addition, the flow of the liquid that passes through the bypass flow channel 160 and the second valve chamber 151 from the first pressure control chamber 122 to the second pressure control chamber 152 also continues.

[0136] Liquid is supplied from the ink cartridge 2 to the first pressure control chamber 122 through the filter 110 and the first valve chamber 121 by the amount of liquid moved from the first pressure control chamber 122 to the second pressure control chamber 152 by the above-mentioned liquid flow. Therefore, the internal volume of the first pressure control chamber 122 is kept constant. According to the relationship of the above-mentioned formula 2, when the internal volume of 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 area S1 of the valve 190, and the pressure area S2 of the pressing plate 210 are kept constant. Therefore, the pressure in the first pressure control chamber 122 is determined in response to the change of the pressure (gauge pressure) P1 in the first valve chamber 121. Therefore, when the pressure P1 in the first valve chamber 121 does not change, the pressure P2 in the first pressure control chamber 122 is kept at the same pressure as the control pressure during the printing operation.

[0137] In contrast, the pressure in the second pressure control chamber 152 changes with time in response to the change in the internal volume due to the inflow of liquid from the first pressure control chamber 122. Specifically, the pressure in the second pressure control chamber 152 changes with time in response to the change in the internal volume due to the inflow of liquid from the first pressure control chamber 122. Fig. 10B The status shown is as follows Fig. 10C The period of time during which the second valve chamber 151 and the second pressure control chamber 152 are not in communication with each other due to the closed state of the communication port 191 changes according to Formula 2. Then, the pressing plate 210 and the valve shaft 190a are not in contact with each other, and the communication port 191 is in the closed state. Fig. 10D As shown, liquid flows from the recovery channel 140 into the second pressure control chamber 152. The inflow of liquid displaces the pressing plate 210 and the flexible member 230, and the pressure in the second pressure control chamber 152 changes according to Formula 4 until the internal volume of the second pressure control chamber 152 reaches a maximum value. That is, the pressure increases.

[0138] When the status changes to Fig. 10C In the state shown, the flow of liquid from the first pressure control chamber 122 to the second pressure control chamber 152 through the bypass flow passage 160 and the second valve chamber 151 does not occur. Therefore, only the flow of the liquid in the first pressure control chamber 122 supplied to the discharge module 300 through the supply passage 130, then passing through the recovery passage 140 and reaching the second pressure control chamber 152 occurs. As described above, the movement of liquid from the first pressure control chamber 122 to the second pressure control chamber 152 occurs in response 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 and the pressure in the first pressure control chamber 122 become the same, the movement of the liquid stops.

[0139] When 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 Fig. 10D When the second pressure control chamber 152 is Fig. 10D When the circulation pump 500 is expanded, a reservoir portion capable of storing liquid is formed in the second pressure control chamber 152. Fig. 10D The transition time between the states shown may vary depending on the shape and size of the flow channel and the properties of the liquid, but is approximately 1 to 2 minutes. Fig. 10D The state in which the liquid is stored in the reservoir portion as shown starts to drive the circulation pump 500, and the circulation pump 500 supplies the liquid in the reservoir portion to the first pressure control chamber 122. Fig. 10E As shown in FIG. 1 , the amount of liquid in the first pressure control chamber 122 increases, and the flexible member 230 and the pressing plate 210 are displaced in the expansion direction. Fig. 10A As shown, the state changes in the cycle path.

[0140] In the above description, although Fig. 10A The example of the printing operation is described, but the circulation of the liquid can be performed without the printing operation as described above. Moreover, in such a case, the operation and stop of the circulation pump 500 are generated as follows. FIG. 10A to FIG. 10E Liquid flow shown.

[0141] As described above, the present embodiment uses an example in which the communication port 191B in the second pressure control unit 150 becomes an open state when the circulation pump 500 is driven to circulate the liquid, and becomes a closed state when the circulation of the liquid stops, but is not limited thereto. The control pressure may be set so that the communication port 191B in the second pressure control unit 150 is in a closed state even when the circulation pump 500 is driven to circulate the liquid. Hereinafter, the bypass flow channel 160 and its function will be described in detail.

[0142] The bypass flow channel 160 connected between the first pressure control unit 120 and the second pressure control unit 150 is provided, for example, to prevent the discharge module 300 from being affected by a negative pressure stronger than a predetermined value generated in the circulation path. The bypass flow channel 160 may also be provided to supply liquid to the pressure chamber 12 from both sides of the supply channel 130 and the recovery channel 140.

[0143] An example of providing the bypass flow channel 160 to prevent the discharge module 300 from being affected by a negative pressure stronger than a predetermined value will now be described. For example, the properties of the liquid (such as viscosity) may change in response to changes in ambient temperature. If the viscosity of the liquid changes, the pressure loss in the circulation path also changes. For example, if the viscosity of the liquid decreases, the amount of pressure loss in the circulation path also decreases. As a result, the flow rate of the circulation pump 500 driven by a certain driving amount increases to increase the flow rate flowing in the discharge module 300. At the same time, since the discharge module 300 is maintained at a constant temperature by a temperature control unit (not shown, described later), the viscosity of the liquid in the discharge module 300 remains constant even if the ambient temperature changes. The flow rate of the liquid flowing in the discharge module 300 increases, while the viscosity of the liquid in the discharge module 300 does not change. Therefore, the negative pressure in the discharge module 300 is enhanced due to flow resistance. The negative pressure in the discharge module 300 thus becomes stronger than a predetermined value to destroy the meniscus of the discharge port 13, and external air is sucked into the circulation path, resulting in the risk of not being able to perform normal discharge. Even if the meniscus is not broken, the negative pressure of the pressure chamber 12 becoming stronger than a predetermined value may affect the discharge.

[0144] Therefore, in the present embodiment, a bypass flow channel 160 is formed in the circulation path. By providing the bypass flow channel 160, when the negative pressure becomes stronger than a predetermined value, since the liquid also flows in the bypass flow channel 160, the pressure in the discharge module 300 can be kept constant. Therefore, for example, the control pressure can be set so that the communication port 191B in the second pressure control unit 150 remains in a closed state even during the driving of the circulation pump 500, and the control pressure in the second pressure control unit can be set so that when the negative pressure is stronger than a predetermined value, the communication port 191 of the second pressure control unit 150 becomes an open state. That is, during the driving of the circulation pump 500, even when the pump flow rate changes due to the viscosity change caused by the environmental change, as long as the meniscus does not collapse or the predetermined negative pressure is maintained, the communication port 191B can be in a closed state.

[0145] An example will now be described in which the bypass flow channel 160 is provided for supplying liquid to the pressure chamber 12 from both sides of the supply channel 130 and the recovery channel 140. A pressure change in the circulation path can also occur by the discharge operation of the discharge element 15. This is because the discharge operation generates a force that draws the liquid into the pressure chamber.

[0146] Now, when high duty printing is continued, the point that the liquid to be supplied to the pressure chamber 12 is supplied from both sides (supply channel 130 side and recovery channel 140 side) will be described. Although the definition of duty may vary due to various conditions, in this article, a state of printing one ink droplet of 4 pL on a grid of 1200 dpi is regarded as 100%. High duty printing is, for example, printing at a duty of 100%.

[0147] When the high load rate printing is continued, the amount of liquid flowing from the pressure chamber 12 through the recovery channel 140 into the second pressure control chamber 152 is reduced. On the other hand, since the circulation pump 500 sends out a certain amount of liquid, the balance between the inflow and outflow in the second pressure control chamber 152 is destroyed, the liquid in the second pressure control chamber 152 is reduced, the negative pressure in the second pressure control chamber 152 becomes strong, and the second pressure control chamber 152 contracts. The amount of liquid flowing into the second pressure control chamber 152 through the bypass flow channel 160 increases due to the strengthening of the negative pressure in the second pressure control chamber 152, and the second pressure control chamber 152 is stabilized in a state where the outflow and inflow are balanced. Therefore, the result is that the negative pressure in the second pressure control chamber 152 becomes strong according to the load rate. As described above, in the configuration in which the communication port 191B is in a closed state during the operation of the circulation pump 500, the communication port 191B becomes an open state according to the load rate, and liquid flows from the bypass flow channel 160 into the second pressure control chamber 152.

[0148] When the high-load rate printing is further continued, the amount of liquid flowing from the pressure chamber 12 through the recovery channel 140 into the second pressure control chamber 152 decreases, while the amount of liquid flowing through the bypass flow channel 160 and flowing from the communication port 191B into the second pressure control chamber 152 increases. When this state further progresses, the amount of liquid flowing from the pressure chamber 12 through the recovery channel 140 into the second pressure control chamber 152 becomes zero, and all the liquid flowing out to the circulation pump 500 becomes the liquid flowing into the second pressure control chamber 152 through the communication port 191B. When this state further progresses, the liquid at this time flows back into the pressure chamber 12 from the second pressure control chamber 152 through the recovery channel 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 pass through the bypass flow channel 160 and flow into the second pressure control chamber 152 from the communication port 191B. In this case, the pressure chamber 12 is filled with the liquid in the supply channel 130 and the liquid in the recovery channel 140, and discharge is performed.

[0149] This backflow of liquid that occurs when the printing duty ratio is high is a phenomenon caused by providing the bypass flow channel 160. In the above, although an example has been described in which the communication port 191B in the second pressure regulating unit becomes an open state in response to the backflow of liquid, the backflow of liquid may also occur when the communication port 191B in the second pressure regulating unit is in an open state. In addition, in a configuration in which the second pressure regulating unit is not provided, the backflow of liquid may occur by providing the bypass flow channel 160.

[0150] Configuration of discharge unit

[0151] Fig.11A and 11B : is a schematic diagram showing a circulation path for one color liquid in the discharge unit 3 of the present embodiment. Fig.11A is an exploded perspective view taken from the first supporting member 4 side of the discharge unit 3, and Fig. 11B 3 is an exploded perspective view taken from the discharge module 300 side of the discharge unit 3. The arrows of the supply (IN) opening and the recovery (OUT) in the figure indicate the liquid flow. The liquid flow will be described only for one color, but the flow of other colors is the same. Fig.11A and 11B The second supporting member 7 and the electric wiring member 5 are omitted in the figure, and description thereof is also omitted in the following description of the configuration of the discharge unit. Fig.11A The first support member 4 is along Figure 3A The discharge module 300 includes a discharge element substrate 340 and an opening plate 330 . Fig.12 is a diagram showing an opening plate 330, and Fig.13 3 is a diagram showing the discharge element substrate 340 .

[0152] From the circulation unit 54 through the joint component 8 (see Figure 3A ) supplies liquid to the discharge unit 3. The path of the liquid from passing through the joint part 8 until returning to the joint part 8 will now be described. In the following drawings, the joint part 8 is omitted.

[0153] The discharge module 300 includes a discharge element substrate 340 and an opening plate 330 composed of a silicon substrate 310, and also includes a discharge port forming member 320. The discharge element substrate 340, the opening plate 330, and the discharge port forming member 320 overlap and engage with each other so that flow channels of various liquids communicate with each other to form the discharge module 300, and are supported by the first support member 4. The discharge module 300 is supported by the first support member 4 to form the discharge unit 3.

[0154] The discharge element substrate 340 includes a discharge port forming member 320, and the discharge port forming member 320 includes a plurality of discharge port columns, each of which is composed of a plurality of discharge ports 13 and discharges a portion of the liquid supplied through the liquid flow channel in the discharge module 300 from the discharge ports 13. The liquid that is not discharged is recovered from the liquid flow channel in the discharge module 300.

[0155] like Fig.11A , Fig. 11B and Fig.12 As shown, the opening plate 330 includes a plurality of arranged liquid supply ports 311 and a plurality of arranged liquid recovery ports 312. Fig.13 and FIG. 14A to FIG. 14C As shown, the discharge element substrate 340 includes a plurality of arranged supply connection channels 323 and a plurality of arranged recovery connection channels 324. The discharge element substrate 340 also 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 channel in the discharge unit 3 is connected by connecting the liquid supply channel 48 and the liquid recovery channel 49 (see Figure 3A ) is formed by communicating with a flow channel provided in the discharge module 300. The support member supply port 211 is a cross-sectional opening forming the liquid supply channel 48, and the support member recovery port 212 is a cross-sectional opening forming the liquid recovery channel 49.

[0156] The liquid to be supplied to the discharge unit 3 is supplied from the circulation unit 54 (see Figure 3A ) side is supplied to the liquid supply channel 48 of the first support member 4 (see Figure 3A The liquid passing through the support member supply port 211 in the liquid supply channel 48 passes through the liquid supply channel 48 (see Figure 3A ) and the liquid supply port 311 of the opening plate 330 are supplied to the common supply channel 18 of the discharge element substrate 340, and enter the supply connection channel 323. The channel up to this point is the supply side flow channel. Subsequently, the liquid passes through the pressure chamber 12 of the discharge port forming member 320 (see Figure 3B ) and flows to the recovery connecting channel 324 of the recovery side flow channel. The details of the flow of liquid in the pressure chamber 12 will be described later.

[0157] In the recovery side flow channel, the liquid entering the recovery connection channel 324 flows into the common recovery channel 19. Subsequently, the liquid flows from the common recovery channel 19 into the liquid recovery channel 49 of the first support member 4 through the liquid recovery port 312 of the opening plate 330, passes through the support member recovery port 212, and is recovered in the circulation unit 54.

[0158] The area without the liquid supply port 311 and the liquid recovery port 312 in the opening plate 330 corresponds to the area for separating the support member supply port 211 and the support member recovery port 212 from each other in the first support member 4. This area does not include the first support member 4 and the opening. When the discharge module 300 and the first support member 4 are bonded to each other, such an area serves as a bonding area.

[0159] exist Fig.12 In the embodiment, the opening plate 330 is provided with a plurality of columns, each column consisting of a plurality of openings arranged in the X direction and arranged in the Y direction, wherein the openings are arranged so that the supply (IN) openings and the recovery (OUT) openings are alternately arranged in the Y direction and staggered by half a pitch in the X direction. Fig.13 In the discharge element substrate 340, the common supply channel 18 connected to the plurality of supply connection channels 323 arranged in the Y direction and the common recovery channel 19 connected to the plurality of recovery connection channels 324 arranged in the Y direction are alternately arranged in the X direction. The common supply channel 18 and the common recovery channel 19 are divided by the type of liquid, and the number of the common supply channels 18 and the common recovery channels 19 to be arranged depends on the number of discharge port columns of the various liquid types. The supply connection channels 323 and the recovery connection channels 324 are also arranged in a number corresponding to the number of the discharge ports 13. It is not necessarily a one-to-one correspondence, and one supply connection channel 323 and one recovery connection channel 324 may correspond to a plurality of discharge ports 13.

[0160] The above-mentioned opening plate 330 and discharge element substrate 340 overlap and engage with each other so that the flow channels of various liquids communicate with each other to form the discharge module 300, and are supported by the first support member 4 to form the liquid flow channel including the above-mentioned supply channel and recovery channel.

[0161] FIG. 14A to FIG. 14C is a cross-sectional view showing the flow of liquid in the discharge unit at different parts of the discharge unit 3 . Fig.14A It is along Fig.11A XIVA-XIVA is a cross section taken along the line XIVA-XIVA of FIG. 4 and shows a cross section of a portion where the liquid supply passage 48 and the liquid supply port 311 communicate with each other in the discharge unit 3 . Fig. 14B It is along Fig.11A XIVB-XIVB is a cross section taken along the line XIVB-XIVB and shows a cross section of a portion where the liquid recovery passage 49 and the liquid recovery port 312 communicate with each other in the discharge unit 3. Fig. 14C It is along Fig.11A XIVC-XIVC is a cross section taken along the line XIVC-XIVC of FIG. 4 and shows a cross section of a portion where the liquid supply port 311 and the liquid recovery port 312 are not in communication with the flow channel of the first supporting member 4 .

[0162] In a supply channel for supplying a liquid, such as Fig.14A As shown, liquid is supplied from the portion where the liquid supply passage 48 of the first support member 4 and the liquid supply port 311 of the opening plate 330 overlap and communicate with each other. In the recovery passage for recovering liquid, as shown in FIG. Fig. 14B As shown, liquid is recovered from the portion where the liquid recovery channel 49 of the first support member 4 and the liquid recovery port 312 of the opening plate 330 overlap and communicate with each other. Fig. 14C As shown, in a portion of the discharge unit 3, the opening plate 330 also includes an area where no opening is provided. In such an area, no liquid is supplied and recovered between the discharge element substrate 340 and the first support member 4. Fig.14A As shown, liquid is supplied in the area where the liquid supply port 311 is provided, and as shown in FIG. Fig. 14B As shown, liquid is recovered in the area provided with the liquid recovery port 312. In the present embodiment, although an example of a configuration using the opening plate 330 has been described, a configuration not using the opening plate 330 may be adopted. In the example of the configuration, flow channels corresponding to the liquid supply channel 48 and the liquid recovery channel 49 may be formed in the first supporting member 4, and the discharge element substrate 340 may be bonded to the first supporting member 4.

[0163] Fig.15A and 15B is a cross-sectional view showing the vicinity of the discharge port 13 in the discharge module 300, and Fig.16A and 16B : is a cross-sectional view showing a discharge module having a configuration in which the common supply passage 18 and the common recovery passage 19 are widened in the X direction as a comparative example. Fig.15A , Fig. 15B , Fig.16A and Fig. 16B The thick arrows shown in the common supply channel 18 and the common recovery channel 19 indicate the fluctuation of the liquid in the configuration using the serial liquid discharge device 50. The liquid that passes through the common supply channel 18 and the supply connection channel 323 and is supplied to the pressure chamber 12 is discharged from the discharge port 13 by driving the discharge element 15. When the discharge element 15 is not driven, the liquid is recovered from the pressure chamber 12 to the common recovery channel 19 through the recovery connection channel 324 as a recovery channel.

[0164] In the configuration using the tandem type liquid discharge device 50, when the liquid thus circulated is discharged, the discharge of the liquid is at least affected by the liquid fluctuation in the liquid flow path caused by the main scanning of the liquid discharge head 1. Specifically, the influence of the liquid fluctuation in the liquid flow path can be expressed as a difference in the liquid discharge amount and a deviation in the discharge direction. Fig.16A and 16BAs shown, when the common supply channel 18 and the common recovery channel 19 have a cross-sectional shape that is wider in the X direction as the main scanning direction, the liquid in the common supply channel 18 and the common recovery channel 19 tends to receive an inertial force in the main scanning direction, and a large fluctuation occurs in the liquid. As a result, the fluctuation of the liquid may affect the discharge of the liquid from the discharge port 13. If the common supply channel 18 and the common recovery channel 19 are widened in the X direction, the distance between different types of liquids is widened, which may reduce printing efficiency.

[0165] Therefore, the common supply channel 18 and the common recovery channel 19 of this embodiment are arranged in Fig.15A and 15B The common supply channel 18 and the common recovery channel 19 extend in the Y direction in the cross section shown, and also extend in the Z direction perpendicular to the X direction which is the main scanning direction. In such a configuration, the flow channel width of each of the common supply channel 18 and the common recovery channel 19 in the main scanning direction can be reduced. By reducing the flow channel width of each of the common supply channel 18 and the common recovery channel 19 in the main scanning direction, the liquid fluctuation caused by the inertial force (thick black arrow in the accompanying drawing) acting on the liquid in the common supply channel 18 and the common recovery channel 19 during scanning to the opposite side of the main scanning direction can be reduced. Therefore, the influence of liquid fluctuation on liquid discharge can be suppressed. In addition, the cross-sectional area is increased by extending the common supply channel 18 and the common recovery channel 19 in the Z direction, and the flow channel pressure loss is thereby reduced.

[0166] As described above, it is configured so that the liquid fluctuation in the common supply channel 18 and the common recovery channel 19 during the main scanning is reduced by reducing the flow channel width of each of the common supply channel 18 and the common recovery channel 19 in the main scanning direction, but this does not mean that the fluctuation will disappear. Therefore, in order to suppress the difference in the discharge of various types of liquids (such a difference may still occur due to the reduction of fluctuation), in the present embodiment, it is configured so that the common supply channel 18 and the common recovery channel 19 are arranged to overlap in the X direction.

[0167] As described above, in the present embodiment, the supply connection channel 323 and the recovery connection channel 324 are provided corresponding to the discharge port 13, and the supply connection channel 323 and the recovery connection channel 324 are arranged so as to be in a corresponding relationship in the X direction with the discharge port 13 therebetween. Therefore, the common supply channel 18 and the common recovery channel 19 have a non-overlapping portion in the X direction, and if the corresponding relationship between the supply connection channel 323 and the recovery connection channel 324 in the X direction is destroyed, the flow and discharge of the liquid in the pressure chamber 12 in the X direction will be affected. The influence increased by the liquid fluctuation can further affect the discharge of the liquid from each discharge port.

[0168] Therefore, by arranging the common supply channel 18 and the common recovery channel 19 to overlap in the X direction, the liquid fluctuations in the common supply channel 18 and the common recovery channel 19 during the main scan are substantially the same at any position where the discharge port 13 is arranged in the Y direction. As a result, the pressure difference generated in the pressure chamber 12 between the common supply channel 18 side and the common recovery channel 19 side does not vary significantly, and stable discharge can be performed.

[0169] Some liquid discharge heads for circulating liquid are configured so that the flow channel for supplying liquid to the liquid discharge head and the flow channel for recovering liquid are the same. However, in the present embodiment, the common supply channel 18 and the common recovery channel 19 are different flow channels. The supply connection channel 323 and the pressure chamber 12 are connected to each other, the pressure chamber 12 and the recovery connection channel 324 are connected to each other, and the liquid is discharged from the discharge port 13 of the pressure chamber 12. That is, the pressure chamber 12, which is configured as a path for connecting between the supply connection channel 323 and the recovery connection channel 324, includes the discharge port 13. Therefore, in the pressure chamber 12, a liquid flow from the supply connection channel 323 side to the recovery connection channel 324 side is generated, and the liquid in the pressure chamber 12 is effectively circulated. By effectively circulating the liquid in the pressure chamber 12, the liquid in the pressure chamber 12, which tends to be affected by the evaporation of the liquid through the discharge port 13, can be kept in a fresh state.

[0170] If it is necessary to discharge at a high flow rate by connecting the two flow channels (the common supply channel 18 and the common recovery channel 19) to the pressure chamber 12, the liquid can also be supplied from the two flow channels. That is, compared with the configuration in which the supply and recovery of the liquid are performed with only one flow channel, the configuration in this embodiment has the advantage of being able to circulate the liquid efficiently and also corresponding to the high flow rate discharge.

[0171] In addition, when the common supply channel 18 and the common recovery channel 19 are arranged closer to each other in the X direction, the influence of liquid fluctuation is less likely to occur. Ideally, the distance between the flow channels is 75 to 100 μm.

[0172] Fig.17 FIG. 3 is a diagram showing a discharge element substrate 340 as a comparative example. Fig.17 , the supply connection channel 323 and the recovery connection channel 324 are omitted. Since the liquid receiving the heat energy of the discharge element 15 in the pressure chamber 12 flows into the common recovery channel 19, the liquid having a relatively high temperature relative to the temperature of the liquid in the common supply channel 18 flows. In this case, in this comparative example, as Fig.17The α portion surrounded by the dotted line in FIG. 3 has a portion where only the common recovery channel 19 exists in a portion of the discharge element substrate 340 in the X direction. In this case, the temperature locally rises at this portion to cause uneven temperature in the discharge module 300, which may affect discharge.

[0173] In the common supply channel 18, a liquid having a relatively low temperature relative to the temperature of the liquid in the common recovery channel 19 flows. Therefore, when the common supply channel 18 and the common recovery channel 19 are adjacent to each other, in the vicinity thereof, the temperatures in the common supply channel 18 and the common recovery channel 19 cancel each other to suppress a temperature rise. Therefore, the common supply channel 18 and the common recovery channel 19 may have substantially the same length, exist at a position overlapping in the X direction, and be adjacent to each other.

[0174] Fig.18A and 18B 1 is a diagram showing the flow channel configuration of the liquid discharge head 1 corresponding to three types of discharged liquids. Fig.18A As shown in FIG. 1 , the liquid discharge head 1 has a circulation flow channel for the corresponding type of ink (liquid). The pressure chamber 12 is arranged along the X direction (that is, the main scanning direction of the liquid discharge head 1). Fig.18B As shown, the common supply channel 18 and the common recovery channel 19 are provided along the discharge port row in which the discharge ports 13 are arranged so as to extend in the Y direction and sandwich the discharge port row therebetween.

[0175] Connection between the main body and the liquid discharge head

[0176] Fig.19 7 is a schematic configuration diagram showing in more detail the connection state of the ink cartridge 2 and the external pump 21 with the liquid discharge head 1 provided in the main body portion of the liquid discharge device 50 of the present embodiment, and the arrangement of the circulation pump, etc. The liquid discharge device 50 in the present embodiment has a configuration in which, when a malfunction occurs in the liquid discharge head 1, only the liquid discharge head 1 can be easily replaced. Specifically, the liquid discharge device 50 includes a liquid connection portion 700 that can easily perform connection and disconnection between the supply pipe 59 connected to the external pump 21 and the liquid discharge head 1. Therefore, only the liquid discharge head 1 can be easily attached to and detached from the liquid discharge device 50.

[0177] like Fig.19As shown, the liquid connection portion 700 includes a liquid connector insertion port 53a provided in a protruding state to the head housing 53 of the liquid discharge head 1 and a cylindrical liquid connector 59a that can be inserted into the liquid connector insertion port 53a. The liquid connector insertion port 53a is fluidly connected to a liquid supply channel (inlet flow channel) formed in the liquid discharge head 1 and is connected to the first pressure control unit 120 through the above-mentioned filter 110. The liquid connector 59a is provided to the end of the supply pipe 59 connected to the external pump 21, and the external pump 21 pressurizes and supplies the liquid in the ink cartridge 2 to the liquid discharge head 1.

[0178] As mentioned above Fig.19 The liquid discharge head 1 shown can be easily attached, disassembled and replaced through the liquid connecting portion 700. However, when the sealing performance between the liquid connector insertion port 53a and the liquid connector 59a is reduced, the liquid supplied by the external pump 21 under pressure may leak from the liquid connecting portion 700. If the leaked liquid adheres to the circulation pump 500, etc., there is a risk of causing a malfunction of the electrical system. Therefore, in the present embodiment, the circulation pump, etc. are arranged as described below.

[0179] Arrangement of circulation pumps, etc.

[0180] like Fig.19 As shown, in the present embodiment, in order to prevent the liquid leaking from the liquid connecting portion 700 from adhering to the circulation pump 500, the circulation pump 500 is arranged above the liquid connecting portion 700 in the gravity direction. That is, the circulation pump 500 is arranged above the liquid connector insertion port 53a, which is the inlet for the liquid in the liquid discharge head 1, in the gravity direction. In addition, the circulation pump 500 is arranged at a position where it does not contact the components constituting the liquid connecting portion 700.

[0181] Therefore, even if liquid leaks from the liquid connecting portion 700, since the liquid flows in the horizontal direction as the opening direction of the liquid connector 59a or flows downward in the gravity direction, it is possible to prevent the liquid from reaching the circulation pump 500 located above in the gravity direction. In addition, since the circulation pump 500 is located at a position away from the liquid connecting portion 700, the risk of the liquid traveling through the components and reaching the circulation pump 500 is also reduced.

[0182] The electrical connection portion 515 for electrically connecting between the circulation pump 500 and the electrical contact substrate 6 via the flexible wiring member 514 is disposed above the liquid connection portion 700 in the gravity direction. Therefore, the risk of electrical failure caused by liquid from the liquid connection portion 700 can be reduced.

[0183] In this embodiment, since the wall 53 b of the head housing 53 is provided, even if liquid is ejected from the opening 59 b of the liquid connecting portion 700 , the liquid can be blocked and the risk of the liquid reaching the circulation pump 500 or the electrical connecting portion 515 can be reduced.

[0184] The circulation system of the liquid may be configured so that the ink circulates in an area including the downstream of the external pump (first external pump) 21 to the carriage 60. In such a case, the ink may also be stirred in a flow channel other than the liquid discharge head 1 of the liquid discharge device 50. In particular, when applied to a circulation system for white ink containing titanium oxide, an excessive increase in the manufacturing cost of the device and an increase in the size of the device can be suppressed while further obtaining the effect of suppressing the sedimentation of the ink containing titanium oxide.

[0185] Temperature Control Unit

[0186] In the printing method disclosed in the present invention, the liquid discharge head is configured to discharge aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink. Here, due to the viscosity difference between the aqueous ink and the aqueous reaction liquid, the discharge balance between the aqueous reaction liquid and the aqueous ink is destroyed, and image unevenness may occur. Generally, the viscosity of many aqueous inks containing colorant particles, resins, etc. is lower than the viscosity of the aqueous reaction liquid. Therefore, as described above, in the printing method disclosed in the present invention, at least one of the ink or the reaction liquid is heated with a temperature control unit to adjust the viscosity of the discharged liquid. Therefore, the discharge balance between the aqueous reaction liquid and the aqueous ink is adjusted to achieve the effect of suppressing image unevenness.

[0187] Examples of the temperature control unit include a heater for controlling the temperature of the discharged liquid arranged in contact with the liquid discharge head, and a heater for liquid discharge (electrothermal conversion element). The heating of the discharged liquid by the heater for ink discharge can be performed by, for example, repeatedly applying a current that does not cause liquid discharge. The viscosity of the liquid is reduced by heating the liquid in the liquid discharge head. The discharge balance between the aqueous reaction liquid and the aqueous ink is adjusted by adjusting the temperature so as to reduce the viscosity difference between the ink and the reaction liquid, and obtain the effect of suppressing image unevenness.

[0188] The viscosity of the discharged liquid is reduced by heating to make it easy to supply (refill) the liquid, and an effect is also obtained in which stable continuous discharge and liquid circulation can be achieved.

[0189] In the inkjet printing method of the present disclosure, in particular, the ink (whose viscosity tends to be higher than the viscosity of the reaction liquid) can be heated to a temperature higher than the printing environment temperature (for example, about 25°C) by the above-mentioned temperature control unit in the liquid discharge head, and then the ink is discharged. Specifically, the ink is preferably heated to 30°C or more and 80°C or less, and more preferably heated to 35°C or more and 70°C or less. That is, the temperature of the ink when discharged, that is, the temperature T1 (°C) of the ink after heating, can be 30°C or more and 80°C or less, or can be 35°C or more and 70°C or less.

[0190] In the present embodiment, the discharge element substrate 340 includes a heater for heating the liquid near the discharge element. In this example of the configuration, the discharge element substrate 340 is divided into a plurality of regions, and a temperature control heater and a temperature sensor are provided in each section. Fig. 20 is a diagram showing a discharge element substrate 340, and is Fig.13 The rear side of the substrate is shown. Fig. 20 In the embodiment, a temperature control heater 801 and a temperature sensor 802 as a temperature control unit are provided near the discharge element 15 in each section of the discharge element substrate 340. In this case, the CPU 103 (see Figure 1B ) The temperature is controlled using these temperature control heaters 801 and temperature sensors 802 based on the temperature set for each area. That is, the CPU 103 drives the temperature control heater 801 only in the area where the detection temperature of the temperature sensor 802 is the target temperature or lower. By performing such temperature control to reduce the change in the discharge amount due to the temperature change, the temperature change in the printing element substrate 10 and the temperature change between the plurality of discharge element substrates 340 are kept within a certain range, and the density unevenness in the printed image can be suppressed. As the temperature sensor, a diode sensor, an aluminum sensor, etc. can be used.

[0191] In addition, as described above, in the printing method of the present disclosure, the circulation path of the discharged liquid is configured to be completed in the liquid discharge head. Therefore, compared with the configuration in which the discharged liquid circulation is performed between the liquid discharge head and the outside thereof, the total volume of the circulation path can be reduced. As a result, the time required for stabilizing the temperature of the liquid in the circulation path can be shortened and the productivity can be improved. In addition, since the liquid in the circulation path is hardly cooled, the driving frequency of the temperature control heater can be reduced, and the power consumption required to maintain the liquid temperature can also be reduced.

[0192] The total volume of ink flowing in one circulation path is preferably 30 mL or less, more preferably 15 mL or less, and preferably 5 mL or more. That is, the volume of the liquid flowing in the circulation path is preferably 5 mL or more and 30 mL or less, more preferably 5 mL or more and 15 mL or less.

[0193] When the discharge element substrate 340 includes a temperature control unit configured to heat the ink and a temperature control unit configured to heat the reaction liquid, the temperature control units provided in the discharge element substrate 340 may be arranged for each discharge port array corresponding to different types of discharge liquids. A plurality of temperature control units (e.g., temperature control heaters) may be arranged in one discharge port array.

[0194] The discharge port array for discharging ink can be configured to discharge multiple types of ink (for example, three colors of cyan, magenta and yellow) from one array. By providing a discharge port array corresponding to ink (first discharge port array) and a discharge port array corresponding to reaction liquid (second discharge port array), the temperature of the ink and the temperature of the reaction liquid are controlled separately, and it is easier to adjust and achieve discharge balance.

[0195] The discharge module 300 for discharging ink and the discharge module 300 for discharging reaction liquid can be separated from each other. That is, the liquid discharge head 1 may include a plurality of discharge modules 300, including a discharge module 300 for discharging ink (first element substrate) and a discharge module 300 for discharging reaction liquid (second element substrate). In this case, the temperature of the ink and the temperature of the reaction liquid can be more effectively controlled respectively.

[0196] When the viscosity of the ink at the printing environment temperature (e.g., about 25° C.) is higher than the viscosity of the reaction liquid, the adjustment temperature t1 of the ink adjusted by the temperature control unit is set to be higher than the adjustment temperature t2 of the reaction liquid. In contrast, when the viscosity of the ink at the printing environment temperature is lower than the viscosity of the reaction liquid, the adjustment temperature t1 of the ink is set to be lower than the adjustment temperature t2 of the reaction liquid.

[0197] The temperature control unit may be provided in the discharge unit 3 instead of in the discharge element substrate 340, or may be provided in the circulation unit (provided in the circulation unit 54). In either case, the temperature control unit may be arranged on the upstream side in the liquid circulation path, that is, in the path where the liquid flows from the circulation pump 500 into the pressure chamber 12. When the temperature control unit is provided in the discharge unit 3, the temperature control unit may be provided at each of the supply port 88, the liquid supply channel 48, the common supply channel 18, and the supply connection channel 323.

[0198] The temperature control unit may be configured so that the discharged liquid can be heated in the ink cartridge 2 or the supply tube 59 outside the liquid discharge head 1. In such a case, a temperature control unit may be provided for each of the ink and the reaction liquid.

[0199] The configuration including a cooling mechanism for cooling the discharged liquid can also be considered as a temperature control unit. The viscosity of the ink at the printing environment temperature is usually higher than the viscosity of the reaction liquid, but the temperature of the reaction liquid increases due to energy, etc. during discharge, and the viscosity of the reaction liquid may become too low compared to the viscosity of the ink. In such a case, the viscosity of the reaction liquid can be controlled by reducing the temperature of the reaction liquid using a cooling mechanism such as a Peltier device and a fan, and the discharge balance between the reaction liquid and the ink is adjusted.

[0200] (2) Reaction liquid

[0201] Various components and the like used in the aqueous reaction liquid of the present disclosure will now be described in detail.

[0202] Reactant

[0203] The reaction liquid contacts with the ink and reacts with the ink to condense the components in the ink (resin and components with anionic groups such as self-dispersing pigments), and the reaction liquid contains a reactant. Examples of reactants include polyvalent metal salts, organic acids, and cationic resins. Any reactant can be added to the reaction liquid within the range of giving the desired characteristics, such as storage stability, intermittent discharge stability, and image unevenness suppression of the reaction liquid.

[0204] In a reaction liquid containing a polyvalent metal salt, the polyvalent metal salt (i.e., a compound composed of a divalent or higher-valent metal ion and an anion) dissociates in the reaction liquid and becomes a polyvalent metal ion, which can aggregate the dispersed colorant through the action of anionic groups contained in the ink.

[0205] Examples of polyvalent metal ions include: divalent metal ions such as Ca 2+ , Cu 2+ 、Ni 2+ Mg 2+ , Sr 2+ , Ba 2+ and Zn 2+ ; and trivalent metal ions, such as Fe 3+ Cr 3+ , Y 3+ and Al 3+ In order to obtain a reaction liquid containing polyvalent metal ions, a polyvalent metal salt (which may be a hydrate) composed of polyvalent metal ions and anions may be used. Examples of anions include inorganic anions such as Cl - Br - ,I - , ClO - 、ClO2 - 、ClO3 - 、ClO4- 、NO2 - 、NO3 - 、SO4 2- 、CO3 2- 、HCO3 - PO4 3- 、HPO4 2- and H2PO4 - ; and organic 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 liquid can be 1.0 mass % or more and 20.0 mass % or less based on the total mass of the reaction liquid.

[0206] The solubility (g / 100 mL) of the polyvalent metal salt in water at 25° C. may be 25.0 g / 100 mL or more. When the solubility is less than 25.0 g / 100 mL, the dissolved state of the polyvalent metal salt in the reaction liquid tends to be unstable, and the polyvalent metal salt tends to precipitate. Since the precipitated polyvalent metal salt may reduce its reactivity with the ink, image unevenness cannot be fully suppressed. The solubility may be 50.0 g / 100 mL or less.

[0207] The reaction liquid containing the organic acid has a buffering capacity in an acidic region (less than pH 7.0, preferably pH 2.0 to 5.0), thereby effectively converting the anionic groups of the components present in the ink into an acid form to cause them to condense. Examples of organic acids include: monocarboxylic acids 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, and salts thereof; dicarboxylic acids such as oxalic acid, maleic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, itaconic acid, sebacic acid, phthalic acid, malic acid and tartaric acid, and salts and hydrogen salts thereof; tricarboxylic acids such as citric acid and trimellitic acid, and salts and hydrogen salts thereof; and tetracarboxylic acids such as pyromellitic acid, and salts and hydrogen salts thereof. When the organic acid is contained, the content (mass %) of the organic acid in the reaction liquid can be 1.0 mass % or more and 50.0 mass % or less based on the total mass of the reaction liquid.

[0208] The example of cationic resin comprises the resin with primary amine to tertiary amine structure and the resin with quaternary ammonium salt structure, specifically, there is the resin of the structure such as vinylamine, allylamine, vinyl imidazole, vinyl pyridine, dimethylaminoethyl methacrylate, ethyleneimine, guanidine, diallyl dimethyl ammonium chloride and alkylamine-epichlorohydrin condensation product.In order to increase the solubility in the reaction liquid, the combination of cationic resin and acidic compound can be used, or cationic resin can be quaternized.When comprising cationic resin, based on the gross mass of reaction liquid, the content (mass %) of cationic resin in reaction liquid can be more than 0.1 mass % and less than 10.0 mass %.

[0209] Other Ingredients

[0210] The reaction liquid may contain various other components as required. Examples of such components include the same components as additional components that can be added to the ink described later.

[0211] Physical properties of the reaction liquid

[0212] The reaction liquid that can be suitable for use in the printing method of the present disclosure is an aqueous reaction liquid applied to the inkjet system. Therefore, from the perspective of reliability, the values ​​of the physical properties can be appropriately controlled. Specifically, the surface tension of the reaction liquid at 25°C can be greater than 20mN / m and less than 60mN / m. The viscosity of the reaction liquid at 25°C can be greater than 1.0mPa·s and less than 10.0mPa·s. The pH of the reaction liquid at 25°C can be greater than 5.0 and less than 9.5, or greater than 6.0 and less than 9.0.

[0213] (3) Ink

[0214] The ink that can be used in the inkjet printing method of the present disclosure will now be described in detail by citing examples. In the present disclosure, when the compound is a salt, the salt in the ink exists as a dissociated ion, but is expressed as "containing a salt" for convenience. Titanium oxide and titanium oxide particles may be referred to as "pigment". Aqueous inks for inkjet printing may be referred to as "ink". Unless otherwise specified, physical values ​​are values ​​at room temperature (25°C). When printing an image of white ink described later, white ink may be used for background color processing of color ink. In such a case, the image may be printed by applying color inks (such as black, cyan, magenta, and yellow inks) to overlap at least a portion of the area where the white ink is applied. Alternatively, the ink may also be used for back printing, where the white ink is applied to overlap at least a portion of the area where the color ink is applied.

[0215] The ink of the present disclosure is an aqueous ink for inkjet printing, and contains a colorant dispersed by the action of anionic groups. The ink of the present disclosure does not need to be a so-called "curable ink". Therefore, the ink of the present disclosure does not need to contain a compound that can be polymerized by applying external energy such as heat and light, such as a polymerizable monomer. The components constituting the ink of the present disclosure, the physical properties of the ink, etc. will now be described in detail.

[0216] Colorants

[0217] The ink contains a colorant dispersed by anionic action. As the colorant, pigments and dyes can be used. Based on the total mass of the ink, the content (mass %) of the colorant in the ink is preferably 0.1 mass % or more and 15.0 mass % or less, and more preferably 1.0 mass % or more and 10.0 mass % or less.

[0218] Specifically, examples of the pigment include inorganic pigments such as carbon black and titanium oxide; and organic pigments such as azo, phthalocyanine, quinacridone, isoindolinone, imidazolinone, diketopyrrolopyrrole, and dioxazine.

[0219] As the dispersion system of the pigment, resin-dispersed pigments using a resin as a dispersant, self-dispersing pigments in which a hydrophilic group is bonded to the surface of the pigment particles, etc. can be used. Resin-bound pigments in which an organic group of the resin is chemically bonded to the surface of the pigment particles and microcapsule pigments in which the surface of the pigment particles is coated with a resin or the like can also be used. In particular, resin-dispersed pigments in which a resin as a dispersant is physically adsorbed to the surface of the resin particles can be used instead of resin-bound pigments and microcapsule pigments. That is, the pigment can be dispersed by a resin (resin dispersant) having an anionic group.

[0220] As a resin dispersant for dispersing the pigment in an aqueous medium, a resin dispersant that can disperse the pigment in an aqueous medium by the action of anionic groups is used. As a resin dispersant, a resin described below, particularly a water-soluble resin, can be used. The mass ratio of the content (mass %) of the pigment in the ink to the content of the resin dispersant can be 0.3 times or more and 10.0 times or less.

[0221] As a self-dispersing pigment, a pigment in which an anionic group such as a carbonate group, a sulfonic acid group or a phosphonic acid group is directly bonded or bonded to the particle surface of the pigment via another atomic group (-R-) can be used. The anionic group can be in acid form or salt form, and the salt form can be partially dissociated or completely dissociated. When the anionic group is in salt form, examples of cations that become counterions include alkali metal cations, ammonium and organic ammonium. Examples of atomic groups (-R-) include straight or branched alkylene groups with 1 to 12 carbon atoms; arylene groups, such as phenylene and naphthylene; carbonyl groups; imino groups; amide groups; sulfonyl groups; ester groups; and ether groups. Combinations of these groups can be used.

[0222] As the dye, a dye having an anionic group is used. Examples of the dye include azo, triphenylmethane, (aza)phthalocyanine, xanthene, and anthrapyridone. The colorant may be a pigment, particularly a resin-dispersed pigment.

[0223] Colorant (white ink)

[0224] The present disclosure may be applicable to an inkjet printing method using an ink containing titanium oxide as a colorant. Since titanium oxide is a white pigment, the ink may be a white ink. In an inkjet printing method utilizing a reaction liquid containing a reactant that reacts with the ink as described in the present disclosure, as described above, a non-absorbent print medium formed of vinyl chloride (VC), polyethylene terephthalate (PET), etc. is generally used. In such a case, the printing using the white ink containing titanium oxide may print an image with high color rendering, regardless of the color of the print medium itself. The colorant in the white ink containing titanium oxide will now be described.

[0225] The white ink contains titanium oxide as a colorant (pigment). The titanium oxide may be titanium oxide particles surface-treated with a specific inorganic oxide. That is, the white ink may contain titanium oxide particles (ie, titanium oxide whose surface is coated with a specific inorganic oxide).

[0226] The content (mass %) of the titanium oxide particles in the ink may be 0.10 mass % or more and 20.00 mass % or less based on the total mass of the ink. Alternatively, the content (mass %) of the titanium oxide particles in the ink may be 1.00 mass % or more and 20.00 mass % or less based on the total mass of the ink. In particular, the content (mass %) of the titanium oxide particles in the ink may be 1.00 mass % or more and 15.00 mass % or less based on the total mass of the ink.

[0227] Titanium oxide is a white pigment and has three crystal forms: rutile, anatase, and brookite. In particular, the titanium oxide may be rutile titanium oxide. Examples of industrial production methods of titanium oxide include a sulfuric acid method and a chlorine method, and the titanium oxide used in the present disclosure may be produced by any production method.

[0228] The cumulative 50% particle size based on volume (hereinafter, also referred to as average particle size) of the titanium oxide particles may be 200 nm or more and 500 nm or less. In particular, the cumulative 50% particle size based on volume of the titanium oxide particles may be 200 nm or more and 400 nm or less.

[0229] The volume-based cumulative 50% particle size (D50) of titanium oxide particles is the diameter of the particles when the total volume of the measured particles is accumulated from the small particle size side to 50% in the particle size accumulation curve. The D50 of titanium oxide particles can be measured, for example, under the following conditions: SetZero: 30 seconds, number of measurements: 3 times, measurement time: 180 seconds, shape: non-spherical, and refractive index: 2.60. As a particle size distribution measuring device, a particle size analyzer using a dynamic light scattering method can be used. The measurement conditions, etc. are not limited to the above.

[0230] Titanium oxide surface-treated with alumina and silica can be used. The surface treatment is expected to suppress photocatalytic activity and improve dispersibility. In this specification, "alumina" is a common name for aluminum oxides (e.g., Al2O3). In this specification, "silicon dioxide" is a common name for silicon dioxide and materials composed of silicon dioxide. Alumina and silica coated with titanium oxide are mainly present in the form of silicon dioxide and aluminum oxide, respectively.

[0231] Based on the total mass of the titanium oxide particles, the proportion (mass %) of titanium oxide in the titanium oxide particles can be 90.00 mass % or more. Based on the total mass of the titanium oxide particles, the proportion (mass %) of titanium oxide in the titanium oxide particles can be 98.50 mass % or less. The mass ratio of the proportion (mass %) of aluminum oxide in the titanium oxide particles to the proportion (mass %) of silicon dioxide is required to be 0.50 times or more and 1.00 times or less. When the mass ratio is less than 0.50 times or greater than 1.00 times, the discharge stability of the ink cannot be obtained. Based on the total mass of the titanium oxide particles, the proportion (mass %) of silicon dioxide in the titanium oxide particles can be 1.00 mass % or more and 4.00 mass % or less. When the proportion (mass %) of silicon dioxide is less than 1.00 mass %, the affinity with the compound represented by the general formula (1) cannot be fully obtained, and the discharge stability of the ink may become insufficient. When the ratio (mass %) of silicon dioxide is greater than 4.00 mass %, even if surface treatment is performed with aluminum oxide, the amount of the compound represented by the general formula (1) adsorbed to the titanium oxide particles cannot be suppressed, and the discharge stability of the ink may become insufficient. The ratio (mass %) of aluminum oxide in the titanium oxide particles may be 0.50 mass % or more and 4.00 mass % or less based on the total mass of the titanium oxide particles.

[0232] An example of a method for measuring the ratio of aluminum oxide and silicon dioxide in titanium oxide particles (i.e., the coating amount of aluminum oxide and silicon dioxide) includes quantitative analysis of aluminum and silicon elements by inductively coupled plasma (ICP) emission spectrometry. In such a case, the ratio can be calculated by assuming that all atoms on the coating surface are oxides and converting the obtained amounts of aluminum and silicon into their oxides (i.e., aluminum oxide and silicon dioxide). The mass ratio of the ratio of aluminum element (mass %) to the ratio of silicon element (mass %) obtained by inductively coupled plasma emission spectrometry in titanium oxide particles is 0.57 times or more and 1.13 times or less. When this value is converted into its oxide (i.e., aluminum oxide and silicon dioxide), the mass ratio of the ratio of aluminum oxide (mass %) to the ratio of silicon dioxide (mass %) in titanium oxide particles is 0.50 times or more and 1.00 times or less.

[0233] Examples of surface treatment methods for titanium oxide include wet treatment and dry treatment. For example, the surface treatment can be performed by dispersing titanium oxide in a liquid medium and then reacting it with a surface treatment agent such as sodium aluminate and sodium silicate. The desired properties can also be adjusted by appropriately changing the ratio of these surface treatment agents. In addition to aluminum oxide and silicon dioxide, the surface treatment can also use inorganic oxides such as zinc oxide and zirconium oxide or organic materials such as polyols, as long as the effects of the present disclosure are not impaired.

[0234] As long as the effect of the present disclosure is not impaired, the white ink may contain pigments other than titanium oxide. In this case, the ink may be any color ink other than white ink. Based on the total mass of the ink, the content (mass %) of the pigment other than titanium oxide in the ink is preferably 0.10 mass % or more and 5.00 mass % or less, more preferably 0.10 mass % or more and 1.00 mass % or less.

[0235] The compound represented by the general formula (1)

[0236] The ink may contain 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 the general formula (1) in the ink is preferably 0.01 mass % or more and 1.00 mass % or less, and further preferably 0.02 mass % or more and 0.50 mass % or less based on the total mass of the ink.

[0237]

[0238] (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; R4 is each 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; and a is 1 to 3, b is 0 to 2, and a+b=3).

[0239] In the general formula (1), R1, R2 and R3 are independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Examples of alkyl groups having 1 to 4 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, etc. In particular, from the perspective of easy hydrolysis, the alkyl group may be a methyl group. When R1, R2 and R3 are all alkyl groups having four or more carbon atoms, it is difficult to form a silanol group by hydrolysis, and affinity for titanium oxide particles cannot be obtained. Therefore, titanium oxide particles cannot be stably dispersed, and discharge stability of the ink cannot be obtained. "a" representing the number of R1O is 1 to 3, "b" representing the number of R2 is 0 to 2, and a+b=3. In particular, "a" can represent 3 and "b" can represent 0, that is, all three substituents of the silicon atom can be R1O.

[0240] In the general formula (1), R4 is independently an alkylene group having 2 to 4 carbon atoms. Examples of alkylene groups having 2 to 4 carbon atoms include ethylene, n-propylene, isopropylene and n-butylene. In particular, the alkylene group may be ethylene. The number of OR4 (i.e., n representing the (average) number of oxyalkylene groups) is 6 to 24. When n is less than 6, since the length of the alkylene oxide chain is too short, the repulsive force of steric hindrance cannot be fully obtained, and the discharge stability of the ink cannot be obtained. When n is greater than 24, since the length of the alkylene oxide chain is too long, the affinity increases, which makes it easier to release into an aqueous medium. Therefore, the affinity with the surface hydroxyl group of the titanium oxide particles cannot be fully obtained, and the agglomeration of the titanium oxide particles cannot be suppressed. Therefore, the titanium oxide particles cannot be stably dispersed, and the discharge stability of the ink cannot be obtained.

[0241] 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 to each other. Examples of alkylene groups having 1 to 6 carbon atoms include methylene, ethylene, n-propylene, isopropylene, n-butylene, n-pentylene and n-hexylene. In particular, the alkylene group may be n-propylene. 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, the titanium oxide particles cannot be stably dispersed, and the discharge stability of the ink cannot be obtained.

[0242] The compound represented by the general formula (1) as a dispersant for titanium oxide particles may be a compound represented by the following general formula (2). In the compound represented by the general formula (2), since the number of OR1 bonded to the silicon atom is 3, a part thereof is hydrolyzed in an aqueous medium, and three hydroxyl groups bonded to the silicon atom may be formed to increase the site having affinity with the titanium oxide particles. The compound represented by the following general formula (2) has a repeating structure of an ethylene oxide group. Therefore, the ethylene oxide chain is appropriately extended in an aqueous medium, and repulsion may be obtained due to steric hindrance.

[0243]

[0244] (In the general formula (2), R1 and R3 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and m is 8 to 24).

[0245] The mass ratio of the content (mass %) of the compound represented by the general formula (1) to the content (mass %) of the titanium oxide particles in the ink may be 0.002 times or more and 0.10 times or less. When the mass ratio is less than 0.002 times, the function of stably dispersing the titanium oxide particles is weakened, and the discharge stability of the ink may become insufficient. When the mass ratio is greater than 0.10 times, the proportion of the compound represented by the general formula (1) is too high, and condensation (self-condensation) between the molecules of the compound represented by the general formula (1) tends to occur. Therefore, the compound represented by the general formula (1) is consumed without being used as a dispersant, the function of stably dispersing the titanium oxide particles is weak, and the discharge stability of the ink may become insufficient.

[0246] The compound represented by the general formula (1) forms a hydrogen bond with the surface hydroxyl group of the titanium oxide particles, and it is inferred that a part of it forms a covalent bond through a dehydration reaction. However, in the present disclosure, the compound represented by the general formula (1) can disperse the titanium oxide particles even if a covalent bond with the titanium oxide particles is not formed. That is, the amount of the compound represented by the general formula (1) that forms a covalent bond with the titanium oxide particles is very small and can be ignored. Therefore, the compound represented by the general formula (1) that is covalently bonded to the titanium oxide particles is not included in the content of the titanium oxide particles. As a result of the research of the present inventors, it was found that if the amount of the compound represented by the general formula (1) that is covalently bonded to the titanium oxide particles is too large, the discharge stability of the ink is reduced.

[0247] The reason for the above situation is inferred as follows. Since electrostatic attraction generally becomes less effective in liquid media with high dielectric constants such as water, the titanium oxide particles move freely without being significantly affected by the surrounding environment. However, if the compound represented by the general formula (1) is covalently bonded to the titanium oxide particles, the hydrophilic portion (OR4 portion) of the general formula (1) structure forms a hydrogen bond with the water molecule. As a result, the movement of the titanium oxide particles may be affected. Therefore, in the case where the liquid is deformed due to instantaneous pressure, such as during the discharge of inkjet printing, the above characteristics manifest as a difference in discharge characteristics. Therefore, the amount (mass %) of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles as a mass ratio to the content (mass %) of the titanium oxide particles can be 0.001 times or less. When the mass ratio is greater than 0.001 times, the discharge stability of the ink may become insufficient. The mass ratio can be 0.0001 times or less. The amount of the compound represented by the general formula (1) covalently bonded to the titanium oxide particles can be calculated by thermogravimetric analysis, etc.

[0248] Resin

[0249] The ink may contain a resin. Examples of the resin include acrylic resins, polyurethane resins, and urea resins. In particular, the resin may be an acrylic resin. Based on the total mass of the ink, the content (mass %) of the resin in the ink is preferably 1.00 mass % or more and 25.00 mass % or less, further preferably 3.00 mass % or more and 15.00 mass % or less, and particularly preferably 5.00 mass % or more and 15.00 mass % or less.

[0250] The ink may contain resins in the application to improve various properties of the printed image, such as wear resistance and concealment. Examples of the resin form 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 resin particles dispersed in an aqueous medium. The resin particles do not need to contain a colorant.

[0251] In this specification, "resin is water-soluble" means that when the resin is neutralized with an amount of alkali equal to the acid value, the resin exists in an aqueous medium without forming particles whose particle size can be measured by a dynamic light scattering method. Whether the resin is water-soluble can be judged by the following method. A liquid containing a resin (resin solid content: 10% by mass) neutralized with an alkali equivalent to the acid value (e.g., sodium hydroxide and potassium hydroxide) is prepared. Subsequently, the prepared liquid is diluted 10 times (based on volume) with pure water to prepare a sample solution.

[0252] The particle size of the resin in the sample solution is measured by a dynamic light scattering method. When no particles with a certain particle size are observed, it can be judged that the resin is water-soluble. The measurement conditions in this case can be set to, for example, SetZero: 30 seconds, number of measurements: 3 times, and measurement time: 180 seconds. As a particle size distribution measuring device, a particle size analyzer by a dynamic light scattering method (for example, trade name: UPA-EX150, manufactured by Nikkiso Co., Ltd.) can be used. The particle size distribution measuring device, measurement conditions, etc. are not limited to the above.

[0253] The acid value of the water-soluble resin is preferably 80 mg KOH / g or more and 250 mg KOH / g or less, and more preferably 100 mg KOH / g or more and 200 mg KOH / g or less. When resin particles are used, the acid value can be 0 mg KOH / g or more and 50 mg KOH / 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 polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0254] Aqueous medium

[0255] The ink is an aqueous ink containing water as an aqueous medium. The ink may contain an aqueous medium, which is water or a solvent mixture of water and a water-soluble organic solvent. As water, deionized water (ion exchange water) may be used. Based on the total mass of the ink, the content (mass %) of water in the ink may be 50.00 mass % or more and 95.00 mass % or less.

[0256] There is no particular limitation on the water-soluble organic solvent as long as it is water-soluble (for example, soluble in water at any ratio at 25°C). Specifically, monovalent or polyhydric alcohols, alkylene glycols, glycol ethers, nitrogen-containing polar compounds, sulfur-containing polar compounds, etc. can be used. Based on the total mass of the ink, the content (mass %) of the water-soluble organic solvent in the ink is preferably 3.00 mass % or more and 50.00 mass % or less, and further preferably 10.00 mass % or more and 40.00 mass % or less. When the content (mass %) of the water-soluble organic solvent is less than 3.00 mass %, the ink adheres to the inkjet printing device, and sufficient anti-adhesion may not be obtained. When the content (mass %) of the water-soluble organic solvent is greater than 50.00 mass %, poor ink supply may occur.

[0257] Other additives

[0258] In addition to the above-mentioned additives, the ink may contain surfactants, pH regulators, corrosion inhibitors, preservatives, antifungal agents, antioxidants, reduction inhibitors, evaporation promoters, chelating agents, etc. as required. In particular, the ink may contain surfactants. The content (mass %) of the surfactant in the ink is preferably 0.10 mass % or more and 5.00 mass % or less based on the total mass of the ink, and further preferably 0.10 mass % or more and 2.00 mass % or less. Examples of surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants. In particular, since surfactants are used to adjust the various physical properties of the ink, the surfactant may be a nonionic surfactant that has a low affinity for titanium oxide particles and can show an effect with a small amount.

[0259] Physical properties of ink

[0260] Since the ink is applied to the inkjet system, its physical properties can be appropriately controlled. 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. The viscosity of the ink at 25°C can be 1.0 mPa·s or more and 10.0 mPa·s or less. The pH of the ink at 25°C can be 7.0 or more and 9.0 or less. When the pH of the ink is within the above range, because the hydrolysis of the compound represented by the general formula (1) causes the generation of silanol groups to continue, the weak affinity between the titanium oxide particles and the compound represented by the general formula (1) is effectively manifested. The pH of the ink can be measured with a general pH meter equipped with a glass electrode.

[0261] Example

[0262] The present disclosure will now be described in more detail with reference to Examples and Comparative Examples, but the present disclosure is not limited in any way to the following Examples as long as it does not exceed the gist of the present disclosure. Unless otherwise specified, "parts" and "%" regarding the amount of ingredients are based on mass. The dispersion of titanium oxide particles is referred to as "pigment dispersion".

[0263] Preparation of titanium oxide

[0264] Commercially available rutile titanium oxide particles that had been surface treated in advance were used. The cumulative 50% particle size (D ) based on volume of the titanium oxide particles was measured by a dynamic light scattering method using a particle size analyzer (trade name: Nanotrac WaveII-EX150, manufactured by Microtracbel). 50 ). The characteristics of various titanium oxide particles are shown in Table 1.

[0265] Table 1: Characteristics of titanium oxide particles

[0266]

[0267] Preparation of pigment dispersion

[0268] Pigment dispersion 1

[0269] A styrene-methyl methacrylate-methacrylic acid copolymer (resin 1) having an acid value of 150 mg KOH / g and a weight average molecular weight of 10,000 is provided. An aqueous solution of resin 1 is prepared by neutralizing 20.0 parts of resin 1 with potassium hydroxide in an amount equimolar to the acid value of the resin and adding an appropriate amount of pure water thereto, wherein the content (solid content) of the resin is 20.0%. Ion exchange water is mixed with 40.0 parts of titanium oxide particles 1 and 40.0 parts of an aqueous solution of resin 1 so that the total amount of the components is 100.0 parts, and a homogenizer is used for preliminary dispersion. Subsequently, a dispersion treatment (main treatment) is carried out at 25° C. for 12 hours in a paint vibrator using 0.5 mm zirconium beads. The zirconium oxide beads are removed by filtration, and an appropriate amount of ion exchange water is added to the filtrate as needed to prepare a pigment dispersion 1, wherein the content of titanium oxide particles is 40.0%, and the content of the resin dispersion (resin 1) is 8.0%.

[0270] Ink preparation

[0271] A mixture of 25.0 parts of the pigment dispersion liquid 1 and the components shown below was stirred. Subsequently, pressure filtration was performed with a membrane filter having a pore diameter of 5.0 μm (manufactured by Sartorius AG) to prepare an ink 1.

[0272] The details of the various mixing ingredients are as follows:

[0273] Acrylic resin particles (trade name: Vinyblan 2685, manufactured by Nissin Chemical Industry Co., Ltd., resin particle content: 30%): 20.0 parts;

[0274] Diethylene glycol: 10.0 parts;

[0275] Diethylene glycol isobutyl ether: 10.0 parts;

[0276] Fluorinated surfactant (trade name: Capstone FS-3100, manufactured by Chemours): 1.0 part; and

[0277] Ion exchange water: 34.0 parts.

[0278] The viscosity of ink 1 (Pa·s) and the density of the liquid component (g / cm 3 ) are 8Pa·s and 1.16g / cm 3 .

[0279] Preparation of reaction liquid

[0280] The components shown below were mixed and sufficiently stirred, and the mixture was pressure-filtered through a cellulose acetate filter (manufactured by Advantec Co., Ltd.) having a pore diameter of 3.0 μm to prepare a reaction liquid 1.

[0281] Magnesium sulfate: 2.0%;

[0282] 1,2-Butanediol: 20.0%;

[0283] Fluorinated nonionic surfactant (trade name: Capstone FS3100, manufactured by LEHVOSS Group): 0.5%;

[0284] Preservative (trade name: PROXEL GXL(S), manufactured by Arch Chemicals Co., Ltd.): 0.2%; and

[0285] Ion exchange water: 77.3%.

[0286] When magnesium sulfate is added, magnesium sulfate heptahydrate is used to add the above-mentioned amount of magnesium sulfate.

[0287] Liquid discharge head

[0288] Head 1

[0289] As Figures 2 to 5 The liquid discharge head shown and including a temperature control heater for each discharge port array in the discharge element substrate 340 and a temperature sensor as a temperature control unit is prepared as the head 1 .

[0290] Head 2

[0291] A head 2 having the same configuration as the head 1 except that the temperature control unit is not provided is prepared as the head 2 .

[0292] Evaluate

[0293] Ink 1 and reaction liquid 1 were set into an inkjet printing apparatus equipped with head 1 or head 2, and the ink was discharged in an environment of temperature 25°C and relative humidity 50%. It was confirmed that the effects of the present disclosure were sufficiently obtained in the inkjet printing apparatus equipped with head 1.

[0294] According to the present disclosure, it is possible to provide an inkjet printing method capable of maintaining stable discharge of a reaction liquid and capable of suppressing the occurrence of image unevenness.

[0295] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An inkjet printing method for printing an image on a printing medium by discharging each of an aqueous ink and an aqueous reaction liquid containing a reactant that reacts with the aqueous ink from a liquid discharge head, wherein The liquid discharge head include: an element substrate including a discharge port for discharging the aqueous reaction liquid, a pressure chamber for supplying the liquid to the discharge port, and a discharge element for generating energy for discharging the liquid; an upstream flow passage for supplying liquid to the pressure chamber; a downstream flow passage in communication with the pressure chamber; a pump in communication with the upstream flow passage and the downstream flow passage; and a temperature control unit configured to heat the aqueous ink or the aqueous reactive liquid, and The inkjet printing method includes operating the pump to cause the liquid in the downstream flow channel to flow into the upstream flow channel.

2. The inkjet printing method according to claim 1, wherein include: discharging the aqueous reaction liquid from the discharge port to the printing medium; as well as The aqueous ink is applied to the printing medium so as to overlap at least a portion of a region where the aqueous reactive liquid is applied. 3 . The inkjet printing 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 inkjet printing method according to claim 1 , wherein the temperature control unit is provided in the element substrate. 5 . The inkjet printing method according to claim 4 , wherein the element substrate includes a temperature sensor, the inkjet printing method further comprising measuring a temperature of the discharge element substrate via the temperature sensor.

6. The inkjet printing method according to claim 4, wherein The element substrate includes a first discharge port array in which a plurality of discharge ports for discharging the aqueous ink are arranged, and a second discharge port array in which a plurality of discharge ports for discharging the aqueous reaction liquid are arranged, and The temperature control unit is provided for each of the first discharge port array and the second discharge port array.

7. The inkjet printing method according to claim 1, wherein The element substrate includes a plurality of discharge port columns, and the discharge ports arranged in the plurality of discharge port columns include a first discharge port column and a second discharge port column. The second discharge port row is located at an end of the arrangement direction of the plurality of discharge port rows, and The inkjet printing method includes discharging the aqueous ink from a plurality of discharge ports in the first discharge port array, and discharging the aqueous reaction liquid from a plurality of discharge ports in the second discharge port array.

8. The inkjet printing method according to claim 1, wherein The liquid discharge head include: a plurality of element substrates, the plurality of element substrates comprising a first element substrate and a second element substrate, The second element substrate is located at an end of the arrangement direction of the plurality of element substrates, and The inkjet printing method includes discharging the aqueous ink from the first element substrate, and discharging the aqueous reaction liquid from the second element substrate.

9. The inkjet printing method according to claim 1, wherein The liquid discharge head include: a discharge unit, the discharge unit including the element substrate; as well as a circulation unit including the pump and configured to circulate the liquid between the circulation unit and the discharge unit, and The temperature control unit is disposed in the circulation unit.

10. The inkjet printing method according to claim 9, wherein the circulation unit is provided for each type of liquid discharged from the discharge port. 11 . The inkjet printing method according to claim 1 , further comprising operating the pump so that a volume of the liquid flowing in the circulation path is 5.0 mL or more and 30 mL or less. 12 . The inkjet printing method according to claim 1 , wherein the temperature control unit is provided outside the liquid discharge head.

13. The inkjet printing method according to claim 1, wherein a liquid storage portion is connected to the liquid discharge head through a tube configured to supply the aqueous ink or the aqueous reaction liquid to the liquid discharge head.

14. The inkjet printing method according to claim 8, wherein the temperature control unit is provided in the liquid storage part.

15. The inkjet printing method of claim 1, wherein the pump is a piezoelectric pump.

16. The inkjet printing method according to claim 1, further comprising scanning the liquid discharge head while discharging the liquid. 17 . The inkjet printing method according to claim 5 , wherein the liquid discharge head further comprises a first pressure regulating unit configured to adjust the pressure of the liquid in the upstream flow channel.

18. The inkjet printing method according to claim 11, wherein the first pressure management unit includes a first valve chamber, a first pressure control chamber, a first opening communicating between the first valve chamber and the first pressure control chamber, and a first valve configured to open and close the first opening.

19. An inkjet printing method according to claim 12, wherein the first pressure control chamber includes a first pressing plate, a portion of the surface of the first pressing plate is formed by a first flexible component and a first biasing component, the first flexible component is configured to be able to shift and to shift in conjunction with the first flexible component, the first biasing component applies force to the first pressing plate in the direction of increasing the volume of the first pressure control chamber and is configured to enable the first valve to open and close in response to the displacement of the first pressing plate and the first flexible component.

20. The inkjet printing method of claim 1, wherein the aqueous ink comprises titanium oxide.

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