Liquid ejection head and liquid ejection device

Abstract

To improve joint force while securing sealability between a nozzle protective member and a joint member.SOLUTION: A liquid discharge head includes a nozzle plate 31 provided with nozzles for discharging liquid, a nozzle protective member 23 covering at least a part other than the nozzles in a nozzle surface 31a facing a liquid discharge direction of the nozzle plate 31, and a joint member 32 joined to the nozzle protective member 23 through an adhesive, wherein in the joint part joined to the nozzle protective member 23 in the joint member 32, a recess 80 filled with the adhesive is provided in a part 81Y extending in a shorter direction of the liquid discharge head.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] 2. Description of the Related Art As a liquid ejection device that ejects liquid, an inkjet image forming device that ejects ink onto a sheet such as paper to form an image is known.

[0003] Inkjet image forming devices are equipped with a liquid ejection head having nozzles that eject ink. When a sheet is transported to a position facing the liquid ejection head, ink is ejected from the nozzles to form an image on the sheet. If the sheet comes into contact with the nozzles at this time, the nozzles may be damaged, making it impossible to eject ink stably. For this reason, some inkjet image forming devices are provided with a nozzle protection member to protect the nozzles.

[0004] The nozzle protection member is bonded to a peripheral portion of the nozzle plate where the nozzles are provided, as well as to a bonding member such as a frame member, so that the nozzle protection member will not peel off or fall off even if it comes into contact with a sheet. For example, Patent Document 1 (JP 2011-56922 A) discloses a configuration for bonding the nozzle protection member in which a recess is provided around the entire periphery of a bonding member (flow path plate) and an adhesive is filled in the recess to bond the nozzle protection member. Summary of the Invention [Problem to be solved by the invention]

[0005] The adhesive used to bond the nozzle protection member not only prevents the nozzle protection member from peeling off, but also serves as a sealing member to prevent foreign matter such as ink from entering the interior through the gap between the nozzle protection member and the bonding member. In this regard, the configuration described in Patent Document 1 has a problem in that the recesses filled with adhesive are provided around the entire circumference of the bonding member, making sealing with the adhesive difficult. Specifically, to seal the gap between the nozzle protection member and the bonding member with adhesive, the recesses must be filled with adhesive. However, when a highly viscous adhesive is used, there is a risk of air bubbles being trapped or gaps being formed during the adhesive filling process, making it difficult to completely fill the recesses with adhesive. Therefore, if there are many recesses that need to be filled with adhesive, there is a corresponding increase in the risk of portions of the recesses not being filled with lubricant, making sealing more difficult. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides a liquid ejection head including a nozzle plate provided with nozzles for ejecting liquid, a nozzle protection member that covers at least a part of a nozzle surface of the nozzle plate facing the liquid ejection direction other than the nozzles, and a joining member that is joined to the nozzle protection member via an adhesive, wherein a joining portion of the joining member that is joined to the nozzle protection member is a portion that extends in the lateral direction of the liquid ejection head. only a recessed portion in which the adhesive is filled is provided in the liquid ejection head. [Effects of the Invention]

[0007] According to the present invention, it is possible to improve the bonding strength while ensuring the sealing performance between the nozzle protection member and the bonding member. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing the overall configuration of an inkjet image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram illustrating a control system of an inkjet image forming apparatus according to an embodiment of the present invention. [Figure 3] FIG. 2 is an exploded perspective view showing an example of the configuration of a liquid ejection head. [Figure 4] FIG. 4 is a cross-sectional view of the liquid ejection head shown in FIG. 3 in the short side direction. [Figure 5] FIG. 2 is a plan view showing an example of the configuration of a line-type head unit. [Figure 6] FIG. 10 is a plan view showing an example of the configuration of a serial type head unit. [Figure 7] 1 is a plan view showing a state in which a cover member of a liquid ejection head according to a first embodiment of the present invention has been removed. [Figure 8] 8 is a cross-sectional view of FIG. 7 taken along line II. [Figure 9] 8 is a cross-sectional view taken along line II-II in FIG. 7. [Figure 10] FIG. 10 is a schematic cross-sectional view of a liquid ejection head according to a second embodiment of the present invention. [Figure 11] FIG. 10 is a schematic cross-sectional view of a liquid ejection head according to a third embodiment of the present invention. [Figure 12] FIG. 10 is a schematic cross-sectional view of a liquid ejection head according to a fourth embodiment of the present invention. [Figure 13] FIG. 10 is a schematic cross-sectional view of a liquid ejection head according to a fifth embodiment of the present invention. [Figure 14] FIG. 10 is a schematic cross-sectional view of a liquid ejection head according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are designated by the same reference numerals as far as they can be distinguished, and descriptions thereof will be omitted once they have been described.

[0010] First, the configuration of an inkjet image forming apparatus, which is one embodiment of a liquid ejection apparatus according to the present invention, will be described with reference to Figures 1 and 2. Figure 1 is a diagram showing the overall configuration of the inkjet image forming apparatus, and Figure 2 is a diagram showing the control system of the inkjet image forming apparatus.

[0011] 1, the image forming apparatus 100 according to this embodiment includes a sheet supply unit 1 that supplies sheets S for image formation, an image forming unit 2 that forms an image on the sheets S, a conveying unit 3 that conveys the sheets S to the image forming unit 2, a drying unit 4 that dries the sheets S, and a sheet collecting unit 5 that collects the sheets S on which the images have been formed. The image forming apparatus 100 according to this embodiment also includes a control unit 6 (see FIG. 2) that controls the sheet supply unit 1, the image forming unit 2, the conveying unit 3, the drying unit 4, and the sheet collecting unit 5.

[0012] The sheet supply unit 1 has a supply roller 11 around which a long sheet S is wound in a roll, and a tension adjustment mechanism 12 that adjusts the tension applied to the sheet S. The supply roller 11 is configured to be rotatable in the direction of the arrow shown in FIG. 1, and the sheet S is unwound by the rotation of the supply roller 11. The tension adjustment mechanism 12 has multiple rollers across which the sheet S is stretched and which apply tension. The tension of the sheet S is adjusted by moving some of these rollers, and the sheet S is unwound from the supply roller 11 with a constant tension.

[0013] The image forming unit 2 has a head unit 13, which is a liquid ejection unit that ejects liquid ink onto the sheet S, and a platen 14, which serves as a sheet support member that supports the sheet S as it is transported. The head unit 13 has multiple liquid ejection heads. An image is formed on the sheet S by ejecting ink from each liquid ejection head onto the sheet S based on image data generated by the control unit 6. Here, the ink is a liquid containing a colorant, a solvent, and crystalline resin particles dispersed in the solvent. The crystalline resin is a resin that undergoes a phase change when heated above a predetermined melting point, melting from a crystalline state into a liquid. The platen 14 is disposed opposite the head unit 13 and supports the underside of the sheet S supplied from the sheet supply unit 1. The platen 14 is also configured to be movable toward and away from the head unit 13 so that the distance between the head unit 13 and the sheet S can be maintained constant.

[0014] The conveying unit 3 has a plurality of conveying rollers 15. With the sheet S stretched between the conveying rollers 15, the conveying rollers 15 rotate, thereby conveying the sheet S to the image forming unit 2. Note that the conveying unit 3 may have other conveying means such as a conveying belt.

[0015] The drying unit 4 has a heating drum 16 that heats the sheet S to accelerate drying of the ink on the sheet S. The heating drum 16 is a cylindrical member that rotates with the sheet S wrapped around its outer surface, and has a heat source such as a halogen heater disposed inside. In addition to contact-type heating means such as the heating drum 16, non-contact-type heating means such as a hot air generator that blows hot air onto the sheet S can also be used as heating means for heating the sheet S.

[0016] The sheet collection unit 5 has a collection roller 17 that winds up and collects the sheet S, and a tension adjustment mechanism 18 that adjusts the tension applied to the sheet S. The collection roller 17 is configured to be rotatable in the direction of the arrow shown in FIG. 1, and as the collection roller 17 rotates, the sheet S is wound up into a roll and collected. The tension adjustment mechanism 18 has multiple rollers, similar to the tension adjustment mechanism 12 of the sheet supply unit 1. As some of these rollers move, the tension of the sheet S is adjusted, and the sheet S is wound up by the collection roller 17 at a constant tension.

[0017] The control unit 6 is configured by an information processing device such as a PC (Personal Computer). The control unit 6 generates image data to be formed on the sheet S, and also controls various operations of the sheet supply unit 1, image forming unit 2, conveyance unit 3, drying unit 4, and sheet collection unit 5. For example, the control unit 6 controls the rotation speeds of the supply roller 11, collection roller 17, and each conveyance roller 15, as well as the temperature of the heat source that heats the heating drum 16.

[0018] Next, an example of the configuration of a liquid ejection head will be described with reference to FIGS.

[0019] Fig. 3 is an exploded perspective view of the liquid ejection head, and Fig. 4 is a cross-sectional view of the liquid ejection head shown in Fig. 3 in the short side direction (the direction of the arrow Y in Fig. 3).

[0020] As shown in FIG. 3, the liquid ejection head 20 includes a plurality of head bodies 21, a base member 22, a cover member 23, a heat dissipation member 24, a manifold 25, a printed circuit board (PCB) 26, and a module case 27.

[0021] The head bodies 21 are held by a base member 22, which serves as a holding member. To attach the head bodies 21 to the base member 22, first, the head bodies 21 are inserted into openings 22c (see FIG. 4) provided in the base member 22. Next, the head bodies 21 are joined to a cover member 23 joined to the base member 22. The cover member 23 has holes 23a (see FIG. 3) formed therein corresponding to the head bodies 21, and the peripheral edge of the head bodies 21 is joined to the edges of the holes 23a. The head bodies 21 are then fastened and fixed to the base member 22 with screws. More specifically, flange portions of a common flow path member 35 (see FIG. 4) are provided on the front and back sides of the head bodies 21 in the longitudinal direction (the direction perpendicular to the plane of the paper in FIG. 4), and these flange portions are fastened to the base member 22 with screws. As a result, the common flow path member 35 is held by the base member 22, and the head bodies 21 are fixed. The attachment structure of the head body 21 and the base member 22 is not limited to this, and the head body 21 may be attached by adhesive, caulking, or the like.

[0022] As shown in Figure 4, the head main body 21 includes a nozzle plate 31 on which nozzles 30 are provided, a flow path substrate 32 on which individual liquid chambers 41 communicating with the nozzles 30 are formed, a vibration plate 33 including a piezoelectric element 40, a holding substrate 34 laminated on the vibration plate 33, and a common flow path member 35 as a frame member laminated on the holding substrate 34.

[0023] In addition to the individual liquid chambers 41, the flow path substrate 32 is formed with supply-side individual flow paths 42 that communicate with the individual liquid chambers 41, and recovery-side individual flow paths 43 that communicate with the individual liquid chambers 41. The holding substrate 34 is formed with supply-side intermediate individual flow paths 44 that communicate with the supply-side individual flow paths 42 via the openings 33a of the vibration plate 33, and recovery-side intermediate individual flow paths 45 that communicate with the recovery-side individual flow paths 43 via the openings 33b of the vibration plate 33.

[0024] A supply-side common flow path 46 communicating with the supply-side intermediate individual flow path 44 and a recovery-side common flow path 47 communicating with the recovery-side intermediate individual flow path 45 are formed in the common flow path member (frame member) 35. The supply-side common flow path 46 communicates with a supply port 48 via a flow path 51 of the manifold 25. On the other hand, the recovery-side common flow path 47 communicates with a recovery port 49 via another flow path 52 of the manifold 25.

[0025] The printed circuit board 26 and the piezoelectric element 40 of the head main body 21 are connected via a flexible wiring member 50. In addition, a driver IC (drive circuit) 53 is mounted on the flexible wiring member 50.

[0026] The base member 22 is preferably made of a material with a low linear expansion coefficient. Examples of materials with a low linear expansion coefficient include 42 alloy (an alloy made of iron with nickel added) and invar. When the base member 22 is made of such a material, even if the temperature of the base member 22 rises due to heat generation from the liquid ejection head 20, the amount of expansion of the base member 22 is small, making it less likely for the nozzles to shift position, and thus suppressing deviation of the ink ejection position. Furthermore, by making the nozzle plate 31 and the diaphragm 33 out of a silicon single crystal substrate and making the linear expansion coefficient approximately the same as that of the base member 22, it is possible to further reduce nozzle position deviation due to thermal expansion.

[0027] FIG. 5 is a plan view showing an example of the configuration of the head unit.

[0028] In the example shown in FIG. 5, the head unit 13 includes two liquid ejection heads 20. Each liquid ejection head 20 is disposed such that its short-side direction (arrow Y direction) is aligned with the sheet conveyance direction A and its long-side direction (arrow X direction) is aligned perpendicular to the sheet conveyance direction A. Here, the "long-side direction" of the liquid ejection head 20 refers to the long-side direction (arrow X direction) of the liquid ejection head 20 extending in one direction when the liquid ejection head 20 is viewed from a direction perpendicular to the nozzle surface 31a on which the nozzles 30 (see FIG. 4) are exposed, as shown in FIG. 5. Furthermore, the "short-side direction" of the liquid ejection head 20 refers to the direction (arrow Y direction) perpendicular to the long-side direction of the liquid ejection head 20 when the liquid ejection head 20 is viewed from a direction perpendicular to the nozzle surface 31a. Furthermore, the "long-side direction" and "short-side direction" of the liquid ejection head 20 described below have the same meaning.

[0029] The head unit 13 shown in Figure 5 is a so-called line-type head unit, and when the sheet S is transported to a position opposite the head unit 13, an image is formed on the sheet S by ejecting ink from the nozzles of each head body 21 without the head unit 13 moving relative to the transported sheet S.

[0030] In addition to such a line-type head unit, there is also a so-called serial-type head unit in which ink is ejected while the liquid ejection head is moved in the main scanning direction (sheet width direction).

[0031] Figure 6 is a diagram showing an example of the configuration of a serial type head unit 60. As shown in Figure 6, the serial type head unit 60 includes a carriage 62 that carries a liquid ejection head 61, a guide member (guide rod) 63 for guiding the carriage 62 in the main scanning direction, which is the sheet width direction B, and a drive device 64 for moving the carriage 62.

[0032] The drive device 64 includes, for example, a motor 65 as a drive source, and a timing belt 68 wound around a drive pulley 66 and a driven pulley 67. When the motor 65 is driven and the drive pulley 66 rotates, the timing belt 68 moves in an orbit, causing the carriage 62 to move in the main scanning direction along the guide member 63. In addition, by switching the rotation direction of the motor 65 between one direction and the opposite direction, the carriage 62 can move back and forth in the main scanning direction.

[0033] In such a serial type head unit 60, ink is ejected from the liquid ejection head 61 in accordance with an image signal while the carriage 62 moves in the main scanning direction, thereby forming an image of one line on the stationary sheet S. Then, while the sheet S moves a predetermined amount at a time in the direction of arrow A in FIG. 6, the carriage 62 moves back and forth and the ink is ejected repeatedly, thereby forming images sequentially on the sheet S.

[0034] Depending on the temperature environment, such as during product transportation, the temperature of the head unit (liquid ejection head) may change significantly. When this happens, the components constituting the head unit expand and contract as the temperature of the head unit changes. The differences in the linear expansion coefficients of the components cause distortion and loads at the joints between the components. In particular, the cover member 23 is subjected to a large load. If the joints of the cover member 23 can no longer withstand the load, the cover member 23 will peel off. If the cover member 23 peels off, ink or other foreign matter may enter the head main body 21 through the peeled portion of the cover member 23, causing a malfunction or operational failure. For example, if ink enters the head main body 21 through the peeled portion of the cover member 23 and adheres to an electrically conductive portion such as the flexible wiring member 50 (see FIG. 4 ) inside the head main body 21, a malfunction due to a current leak may occur. Furthermore, if ink that has entered the interior adheres to the piezoelectric element 40 (see Figure 4) inside the head main body 21, the ink may subsequently solidify and prevent the piezoelectric element 40 from operating properly, which may result in poor ink ejection.

[0035] Thus, peeling of the cover member 23 can cause various problems such as malfunctions or breakdowns, etc. Therefore, in the embodiment of the present invention, the following configuration is adopted.

[0036] Fig. 7 is a plan view showing a state in which a cover member of the liquid ejection head according to the first embodiment of the present invention has been removed, Fig. 8 is a cross-sectional view taken along line II in Fig. 7, and Fig. 9 is a cross-sectional view taken along line II-II in Fig. 7. The basic structure of the liquid ejection head according to this embodiment is almost the same as that of the liquid ejection head shown in Figs. 3 and 4, and therefore, explanations of parts that have already been explained will be omitted where appropriate.

[0037] As shown in Figures 7 to 9, the liquid ejection head 20 according to this embodiment includes a nozzle plate 31 provided with nozzles 30 (see Figure 4), a cover member 23 as a nozzle protection member that protects the nozzles 30, a flow path substrate 32 as a flow path forming member in which supply side individual flow paths 42 (see Figure 4) and recovery side individual flow paths 43 (see Figure 4) are formed, a common flow path member 35 as a frame member, and a base member 22 as a holding member that holds the common flow path member 35, etc.

[0038] 7, the direction of arrow X indicates the longitudinal direction of the liquid ejection head 20, and the direction of arrow Y indicates the lateral direction of the liquid ejection head 20. Furthermore, in Figures 8 and 9, the direction of arrow Z indicates the liquid ejection direction in which liquid (ink) is ejected from the nozzles of the nozzle plate 31. That is, in Figures 8 and 9, the nozzle surface 31a, on which the nozzles of the nozzle plate 31 are exposed, faces upward.

[0039] The cover member 23 covers at least a portion of the nozzle surface 31a other than the nozzles. In this embodiment, the cover member 23 covers the edge of the nozzle surface 31a and the area in the vicinity thereof.

[0040] Here, if the central side of the nozzle surface 31a (the right side in Fig. 8) is defined as the "inside" and the opposite side (the left side in Fig. 8) is defined as the "outside," then, as shown in Fig. 8, the outer portion of the cover member 23 is adhered to the base member 22 via adhesive 54. The base member 22 is disposed around the nozzle plate 31, the flow path substrate 32, and the common flow path member 35, and the outer portion of the cover member 23 is adhered to a surface 220 of this base member 22 facing the liquid ejection direction Z.

[0041] On the other hand, the inner portion of the cover member 23 is adhered to the nozzle plate 31 and the flow path substrate 32 via adhesive 55. The flow path substrate 32 is arranged on the side opposite the nozzle surface 31a of the nozzle plate 31 (the lower surface side of the nozzle plate 31 in FIG. 8), and a part of it protrudes outward from the edge of the nozzle plate 31. The cover member 23 is adhered to this part of the flow path substrate 32 protruding outward and to the periphery of the edge of the nozzle plate 31.

[0042] In this way, the inner and outer portions of the cover member 23 are adhered to the respective components via the adhesives 54, 55, and the gaps between the respective components and the cover member 23 are sealed with the adhesives 54, 55, thereby preventing ink and other foreign matter from entering the interior through these gaps. However, as described above, when the various components of the liquid ejection head 20 expand or contract due to temperature changes, loads are applied to the joints of the cover member 23, and there is a risk that the cover member 23 will peel off.

[0043] 7, a plurality of recesses 80 are provided in the flow path substrate 32, which serves as a joining member to which the cover member 23 is joined. Each recess 80 is provided in a joining portion (a portion that protrudes outward beyond the nozzle plate 31) of the flow path substrate 32 that is joined to the cover member 23. As shown in FIGS. 8 and 9, the recess 80 according to this embodiment is formed in a cubic or rectangular parallelepiped shape having a bottom surface 80a and four side surfaces 80b to 80e that are orthogonal (including "orthogonal") to the bottom surface 80a, and is open toward the liquid ejection direction Z. Note that, of the joining portion of the flow path substrate 32, the portion other than the recesses 80 is a planar joining portion (joining surface).

[0044] As described above, in this embodiment, since a plurality of recesses 80 are provided in the joints of the flow path substrate 32, when the adhesive 55 is applied to the joints of the flow path substrate 32, the adhesive 55 enters and fills the recesses 80, as shown in Figures 8 and 9. Furthermore, the adhesive 55 is applied to other portions (planar joints) of the flow path substrate 32 in addition to the recesses 80, and adhesives 54, 55 are also applied to the joints of the nozzle plate 31 and the base member 22. Then, the cover member 23 is pressed onto the adhesives 54, 55, and thereafter the adhesives 54, 55 are hardened, thereby joining the cover member 23 to the respective members (flow path substrate 32, nozzle plate 31, and base member 22).

[0045] At this time, an anchor effect is obtained by the adhesive 55 hardening within the recess 80, particularly in the area where the recess 80 is provided. That is, the adhesive 55 hardens while remaining inside the recess 80, thereby increasing the bonding strength compared to when flat surfaces are bonded together. Therefore, in this embodiment, the bonding strength between the cover member 23 and the flow path substrate 32 is improved compared to a configuration in which no recess is provided in the bonding portion, making it less likely that the cover member 23 will peel off.

[0046] Furthermore, in order to confirm the bonding strength due to the anchor effect as described above, a bonding strength evaluation test was conducted for the comparative example shown in Fig. 14 and the configuration according to this embodiment. The comparative example has the same configuration as this embodiment, except that no recess 80 is provided at the bonding portion of the flow path substrate 32. The temperature of each liquid ejection head according to the comparative example and this embodiment was changed between 30°C and 70°C, and this temperature change cycle was repeated a total of 10 times to confirm whether or not peeling of the cover member 23 occurred.

[0047] As a result, in the comparative example, peeling of the cover member 23 occurred in half of the cases. In the other comparative examples, peeling of the cover member 23 did not occur, but the bonded state of the cover member 23 was somehow maintained. In contrast, in this embodiment, peeling of the cover member 23 did not occur at all. This confirmed that the configuration of this embodiment can effectively suppress peeling of the cover member 23.

[0048] In this embodiment, the adhesive 55 is applied over the entire periphery of the flow path substrate 32 (the entire joint), but the recess 80 is provided only in a portion 81Y of the joint of the flow path substrate 32 that extends in the short-side direction of the liquid ejection head 20 (see FIG. 7). The reason why the recess 80 is provided only in the portion 81Y that extends in the short-side direction, rather than the entire joint, is that a particularly large load is applied to this portion.

[0049] In a longitudinally shaped liquid ejection head such as that of this embodiment, a test was conducted in advance to confirm changes in stress due to temperature changes, and it was found that a large load was generated particularly in the portion extending in the lateral direction of the liquid ejection head. From this, it can be said that, of the bonded portion around the entire periphery of the flow path substrate 32, the portion 81Y extending in the lateral direction is particularly prone to peeling of the cover member 23. Therefore, in this embodiment, a recess 80 is provided in the portion 81Y extending in the lateral direction of the bonded portion of the flow path substrate 32, where peeling of the cover member 23 is particularly likely to occur. This improves the bonding strength in the portion 81Y extending in the lateral direction due to the anchor effect of the adhesive 55 filled in the recess 80, thereby effectively preventing the cover member 23 from peeling.

[0050] On the other hand, among the joints of the flow path substrate 32, a portion 81X extending in the longitudinal direction of the liquid ejection head 20 is not provided with a recess 80 (see FIG. 7). Therefore, the portion 81X extending in the longitudinal direction is a flat joint surface that is free of recesses 80 over its entirety. In this way, among the joints of the flow path substrate 32, no recesses 80 are provided among the portion 81X extending in the longitudinal direction in order to improve the sealing performance by the adhesive.

[0051] Generally, a joint having a recess is more likely to have air bubbles or gaps when adhesive is applied than a flat joint (joint surface). Furthermore, in a configuration in which the cover member 23 is joined to the flow path substrate 32, as in the present embodiment, it is necessary to apply a thick layer of adhesive and reduce the pressure applied to the flow path substrate 32 so that the flow path substrate 32 is not damaged by the pressure applied when joining the cover member 23. Therefore, in this embodiment, an adhesive with a certain degree of viscosity must be used. However, if the viscosity of the adhesive is high, it becomes increasingly difficult to fill the recess 80 with the adhesive, increasing the risk of air bubbles or gaps forming. While some types of adhesives are less likely to form air bubbles or gaps, the number of such adhesives is limited, which restricts the range of adhesives that can be selected.

[0052] As described above, it is difficult to fill the recess 80 with adhesive, and there is a high risk of air bubbles or gaps occurring when a highly viscous adhesive is used, but by limiting the portion where the recess 80 is provided to only the portion 81Y of the joint that extends in the short direction, as described above, it is possible to reduce the risk of air bubbles or gaps occurring. In other words, by limiting the recess 80, where air bubbles or gaps are likely to occur, to the minimum necessary area, air bubbles or gaps are less likely to occur between the joints, thereby improving sealing performance.

[0053] Furthermore, according to this embodiment, sealing between the cover member 23 and the flow path substrate 32 can be ensured without selecting an adhesive that is unlikely to cause air bubbles or gaps within the recess 80 as the adhesive for joining the cover member 23 and the flow path substrate 32. This allows for a wider range of adhesives to be selected, thereby alleviating the problem of limitations on the range of adhesives that can be selected. Furthermore, when the recess 80 is provided in a limited area as in this embodiment, the amount of adhesive required to fill the recess 80 is smaller than when the recess 80 is provided over the entire joint, thereby reducing costs.

[0054] As described above, according to this embodiment, by providing the recesses 80 only in the portion 81Y extending in the lateral direction, which is subject to a particularly large load, it is possible to achieve both improved bonding strength and ensure sealing. This effectively prevents foreign matter from entering the liquid ejection head, reducing the risk of malfunction and breakdown of the liquid ejection head, thereby improving reliability. Note that the recesses 80 may be provided not only in the portion 81Y extending in the lateral direction but also over a portion of the portion 81X extending in the longitudinal direction, as long as they do not extend around the entire circumference of the flow path substrate 32. Even in this case, it is possible to improve sealing compared to when the recesses 80 are provided around the entire circumference of the flow path substrate 32.

[0055] The recesses 80 can be provided over the entire portion 81Y extending in the short side direction, but in order to improve sealing performance, it is preferable that the recesses 80 are provided in part of the portion 81Y extending in the short side direction, as shown in Fig. 7. Furthermore, the number of recesses 80 provided in each portion 81Y extending in the short side direction is not limited to two (see Fig. 7), but may be one, three or more. Furthermore, the recesses 80 may be formed in a rectangular shape when viewed from the liquid ejection direction Z, or may be circular or have other shapes.

[0056] Next, an embodiment different from the above-described embodiment (first embodiment) will be described. In the following description, differences from the above-described embodiment will be mainly described, and other parts will be omitted as they are basically configured in the same way.

[0057] FIG. 10 is a schematic cross-sectional view of a liquid ejection head according to a second embodiment of the present invention.

[0058] 10, the base member 22 (see FIG. 8) is not provided. Therefore, in this embodiment, a cover member 23 is joined to a common flow path member (frame member) 35 instead of the base member 22. More specifically, the common flow path member 35 has a peripheral wall portion 35b that is disposed around (outside) the nozzle plate 31 and the flow path substrate 32 and protrudes in the liquid ejection direction Z, and the cover member 23 is adhered to a surface 350 of this peripheral wall portion 35b that faces the liquid ejection direction Z with an adhesive 56. Note that in the embodiment (first embodiment) shown in FIG. 8, of the base member 22, particularly the upper portion in the figure corresponds to the peripheral wall portion 22b that is disposed around the nozzle plate 31 and the flow path substrate 32.

[0059] As described above, the second embodiment differs from the above-described embodiments in that the base member 22 is not provided and the cover member 23 is joined to the peripheral wall portion 35b of the common flow path member 35. However, even with this configuration, there is a risk that the cover member 23 will peel off when each member expands or contracts due to a change in temperature of the liquid ejection head. Therefore, in this embodiment, as in the above-described embodiments, a recess 80 is provided only in a portion 81Y (see FIG. 7) extending in the short direction of the liquid ejection head 20, of the joining portion of the flow path substrate 32 to which the cover member 23 is joined. This makes it possible to achieve both improved joining strength and ensure sealing performance, effectively suppressing the intrusion of foreign matter into the liquid ejection head, and thereby improving reliability.

[0060] FIG. 11 is a schematic cross-sectional view of a liquid ejection head according to a third embodiment of the present invention.

[0061] 11, the recess 80 is configured to open at an end surface 320 facing the outside (the side opposite to the center of the nozzle surface) of the flow path substrate 32. That is, the recess 80 according to this embodiment does not have a side surface 80b (see FIG. 8) that is arranged on the outside of the recess 80 according to the first embodiment.

[0062] As described above, in the third embodiment, the recess 80 is open toward the outside of the flow path substrate 32, and therefore, air bubbles inside the recess 80 are easily discharged to the outside through the opening. This makes it easier to fill the inside of the recess 80 with the adhesive 55, further improving the sealing performance of the adhesive 55. Note that the configuration in which the recess 80 is open toward the outside of the flow path substrate 32 as in this embodiment is not limited to the liquid ejection head 20 having the base member 22 as shown in FIG. 11, but can also be applied to a liquid ejection head 20 that does not have a base member 22 (see FIG. 10).

[0063] FIG. 12 is a schematic cross-sectional view of a liquid ejection head according to a fourth embodiment of the present invention.

[0064] 12, in addition to the configuration of the third embodiment shown in Fig. 11, the recess 80 is further configured to expand inward, and part of the recess 80 extends onto the side opposite the nozzle surface 31a of the nozzle plate 31 (the lower surface side of the nozzle plate 31 in Fig. 12). In other words, part of the recess 80 is arranged to overlap with the nozzle plate 31 when the recess 80 is viewed from a direction perpendicular to the nozzle surface 31a.

[0065] As described above, in the fourth embodiment, the recess 80 is disposed so as to partially overlap the cover member 23. Therefore, when the adhesive 55 is filled into the recess 80, the adhesive 55 penetrates into the cover member 23 toward the side opposite the nozzle surface 31a. The adhesive 55 hardens in this state, further enhancing the anchoring effect of the adhesive 55, further improving the bonding strength between the cover member 23 and the flow path substrate 32. Therefore, in this embodiment, peeling of the cover member 23 can be more effectively suppressed, thereby improving reliability. In contrast, the configuration in which the recess 80 does not overlap the cover member 23, as shown in FIGS. 7 to 9 , 10 , or 11 , has the advantage that the recess 80 can be formed in the flow path substrate 32 even after the nozzle plate 31 is assembled on the flow path substrate 32. In addition, the configuration in which a portion of the recess 80 overlaps the cover member 23 as in this embodiment is not limited to liquid ejection heads 20 having a base member 22 as shown in Figure 12, but can also be applied to liquid ejection heads 20 that do not have a base member 22 (see Figure 10), as well as configurations in which the recess 80 does not open outward (see Figures 7 to 9 and Figure 10).

[0066] FIG. 13 is a schematic cross-sectional view of a liquid ejection head according to a fifth embodiment of the present invention.

[0067] 13, in addition to the configuration of the fourth embodiment shown in FIG. 12, a part of the recess 80 is configured as a temporary bonding recess 82. This temporary bonding recess 82 is a recess filled with a temporary bonding adhesive 57 for temporarily bonding the nozzle plate 31 and the flow path substrate 32. The recess 80 and the temporary bonding recess 82 are provided, for example, one on each end side of the portion 81Y extending in the short direction. However, the number and arrangement of the recesses 80 and the temporary bonding recess 82 can be changed as appropriate.

[0068] In this way, a portion of the recess 80 may be used as the temporary bonding recess 82. In this embodiment, to bond the cover member 23, first, the temporary bonding recess 82 is filled with a temporary bonding adhesive 57, and the nozzle plate 31 and the flow path substrate 32 are temporarily bonded together. As the temporary bonding adhesive 57, for example, an ultraviolet-curable adhesive, which allows the adhesive to be easily cured, is preferred. Then, the permanent bonding adhesive 55 is applied to the temporarily bonded nozzle plate 31 and flow path substrate 32 (recess 80), and the cover member 23 is bonded to the nozzle plate 31 and the flow path substrate 32. In this way, by first temporarily bonding the nozzle plate 31 and the flow path substrate 32 and then permanently bonding them to the cover member 23, it is easy to position the respective components relative to each other. Furthermore, the configuration in which a portion of such a recess 80 is used as a temporary bonding recess 82 is not limited to a liquid ejection head 20 having a base member 22 as shown in Figure 13, but can also be applied to a liquid ejection head 20 that does not have a base member 22 (see Figure 10), as well as a configuration in which the recess 80 does not open outward (see Figures 7 to 9 and Figure 10).

[0069] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the scope of the invention.

[0070] In the present invention, a "liquid ejection head" refers to a functional component that ejects or sprays a liquid from a nozzle. The ejected liquid may have any viscosity or surface tension that allows it to be ejected from the head. While not particularly limited, it is preferable that the viscosity of the ejected liquid be 30 mPa·s or less at room temperature and pressure, or upon heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, or the like containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing agent such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, or an edible material such as a natural dye. These liquids can be used, for example, as inkjet inks, surface treatment solutions, components of electronic or light-emitting elements, liquids for forming resist patterns for electronic circuits, and liquid materials for three-dimensional modeling. The liquid ejection head may have multiple head bodies, as in the above-described embodiment, or it may have a single head body.

[0071] Energy sources for ejecting liquid include piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a vibration plate and an opposing electrode.

[0072] In the present invention, the term "liquid ejection unit" refers to a liquid ejection head integrated with functional parts and mechanisms, and includes a collection of parts related to ejecting liquid. For example, the term "liquid ejection unit" includes a combination of a liquid ejection head and at least one of the following components: a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, a main scanning movement mechanism, and a liquid circulation device.

[0073] Here, "integrated" includes, for example, a liquid ejection head and a functional part or mechanism fixed to each other by fastening, bonding, engaging, etc., or one held movably relative to the other. The liquid ejection head, functional part, or mechanism may also be configured to be detachable from each other.

[0074] For example, some liquid ejection units have a liquid ejection head and a head tank integrated together, while others have a liquid ejection head and a head tank integrated together by being connected to each other by a tube, etc. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

[0075] Furthermore, there is a liquid ejection unit in which the liquid ejection head and the carriage are integrated.

[0076] In some liquid ejection units, the liquid ejection head is movably held by a guide member that constitutes part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated together. In other liquid ejection units, the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated together.

[0077] Furthermore, there is a liquid ejection unit in which a cap member, which is part of the maintenance and recovery mechanism, is fixed to a carriage on which a liquid ejection head is attached, thereby integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

[0078] In some liquid ejection units, a tube is connected to a head tank or a liquid ejection head equipped with a flow path component, integrating the liquid ejection head with a supply mechanism. Liquid is supplied from a liquid storage source to the liquid ejection head via this tube.

[0079] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0080] The term "liquid ejection device" includes devices that have a liquid ejection head or a liquid ejection unit and eject liquid by driving the liquid ejection head. Liquid ejection devices include not only devices that can eject liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0081] This "liquid ejection device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0082] For example, examples of "liquid ejection devices" include image forming devices, which are devices that eject ink to form images on paper, and three-dimensional modeling devices (three-dimensional modeling devices), which eject modeling liquid onto a powder layer formed from layers of powder in order to create a three-dimensional object (a three-dimensional model).

[0083] Furthermore, the term "liquid ejection device" is not limited to devices that visualize meaningful images such as letters and figures using ejected liquid. For example, it also includes devices that form patterns that have no meaning in themselves, and devices that create three-dimensional images.

[0084] The above-mentioned "object onto which a liquid can adhere" refers to an object to be transported onto which a liquid can adhere at least temporarily, such as an object onto which the liquid adheres and sticks, or an object onto which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, electronic circuit boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects onto which a liquid can adhere.

[0085] The material of the "liquid-adherable object" may be any material to which the liquid can be attached, even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, or ceramics.

[0086] Furthermore, the "sheet" may be a continuous sheet formed into a long length (such as roll paper), or a sheet that has been pre-cut to a predetermined size (such as cut paper). Furthermore, the present invention is also applicable to devices that transport objects other than sheets.

[0087] Furthermore, the term "liquid ejection device" includes, but is not limited to, a device in which a liquid ejection head and an object onto which liquid can be attached move relatively. Specific examples include a serial type device in which the liquid ejection head moves (see FIG. 6) and a line type device in which the liquid ejection head does not move (see FIG. 5).

[0088] Other examples of "liquid ejection devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that sprays a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials. [Explanation of symbols]

[0089] 20 Liquid ejection head 22 Base material 23 Cover member (nozzle protection member) 30 nozzles 31 Nozzle plate 31a Nozzle surface 32 Flow path substrate (flow path forming member) 55 Adhesive 57 Temporary bonding adhesive 80 recess 81X Longitudinal extending portion 81Y Part extending in the short direction 82 Temporary joint recess 100 Image forming device (liquid ejection device) 220 Surface facing the liquid discharge direction S sheet (transported object) [Prior art documents] [Patent documents]

[0090] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-56922

Claims

1. a nozzle plate provided with nozzles for discharging liquid; a nozzle protection member that covers at least a portion of a nozzle surface of the nozzle plate that faces the liquid ejection direction, other than the nozzles; a liquid ejection head including a joining member joined to the nozzle protection member via an adhesive, A liquid ejection head characterized in that a recess into which the adhesive is filled is provided only in a portion of the joining portion of the joining member that is joined to the nozzle protection member and that extends in the short direction of the liquid ejection head.

2. A liquid ejection head as described in Claim 1, wherein the joining member is a flow path forming member that is arranged on the side opposite the nozzle surface of the nozzle plate and forms a flow path for liquid supplied to the nozzle.

3. A liquid ejection head as described in claim 1 or 2, wherein the recess opens on an end face facing opposite to the center of the nozzle surface of the joining member.

4. A liquid ejection head described in any one of claims 1 to 3, wherein the recess is arranged to overlap the nozzle plate when viewed from a direction perpendicular to the nozzle surface.

5. A liquid ejection head described in any one of claims 1 to 3, wherein the recess is arranged so as not to overlap with the nozzle plate when viewed from a direction perpendicular to the nozzle surface.

6. A liquid ejection head described in any one of claims 1 to 5, wherein a portion of the recess constitutes a temporary bonding recess filled with temporary bonding adhesive for temporarily bonding the nozzle plate and the bonding member.

7. A liquid ejection device comprising a liquid ejection head described in any one of claims 1 to 6.

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