LIQUID DISCHARGE HEAD, LIQUID DISCHARGE UNIT, AND DEVICE FOR DISCHARGING LIQUID

Abstract

To provide a liquid discharge head capable of preventing discharge failure or breakage, regardless of a surface state such as fluffing and the like of a recorded medium that is an object to be discharged liquid.SOLUTION: A liquid discharge head 100 is equipped with a nozzle plate 1 that has a nozzle 4 discharging droplets, and a cover member 40 that has an opening portion 41 exposing the nozzle 4 and covers at least an outer periphery of the nozzle 4. The cover member 40 has a plurality of projections 44 projecting out in a droplet discharging direction E in a peripheral edge area 42 of the opening portion 41 and an area outer than the peripheral edge area 42 of the opening portion 41.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art Known image forming apparatuses, such as printers, facsimiles, copiers, plotters, and combination machines thereof, are devices that eject liquid using a liquid ejection head that ejects ink droplets (eg, inkjet recording apparatuses).

[0003] A known configuration for liquid ejection heads is to attach a cover member to a nozzle plate in which nozzles (ink droplet ejection ports) are formed, in order to protect the head from external forces such as contact with cleaning members such as wipers or collisions with the recording medium (ejection target) in the event of a jam (see, for example, Patent Document 1).

[0004] When a cover member is attached to the nozzle plate, the thickness of the entire head increases by the thickness of the cover member, so it is necessary to ensure a sufficient distance (platen gap) so that the recording medium and the cover member do not come into contact. However, by ensuring the distance between the recording medium and the cover member, the distance from the nozzle to the recording medium also increases, which may lead to problems such as misalignment of the landing position of droplets and misting of droplets before landing. In response to this, Patent Document 1 discloses a liquid ejecting head that is capable of ensuring electrical continuity while reducing the height difference between the nozzle plate and the cover member. Summary of the Invention [Problem to be solved by the invention]

[0005] A liquid ejecting device is a device capable of ejecting liquid onto an object onto which the liquid can adhere. Here, "objects onto which the liquid can adhere" refers to objects onto which the liquid can adhere at least temporarily, and examples of such materials include paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics.

[0006] Some recording media have fuzz or other particles on the recording surface, depending on the material of the recording medium. If foreign matter such as fuzz comes into contact with the nozzles of a liquid ejection head, this can cause ejection defects or damage. The degree and length of the fuzz on the surface varies depending on the type and material of the recording medium, but even if a cover member is provided on the liquid ejection head, as long as the nozzles are exposed, it is difficult to prevent the fuzz from coming into contact with the nozzles, especially in an embodiment in which the height difference between the nozzle plate and the cover member is reduced.

[0007] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS Accordingly, an object of the present invention is to provide a liquid ejection head that is capable of preventing ejection defects and damage, regardless of the surface condition, such as fuzz, of the recording medium onto which the liquid is to be ejected. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides a liquid ejection head comprising: a nozzle plate having nozzles for ejecting liquid droplets; and a cover member having an opening for exposing the nozzles and covering at least an outer periphery of the nozzles, the cover member comprising: It is joined by adhesive, The nozzle has a plurality of projections protruding in the droplet ejection direction in a peripheral region of the opening and in a region outside the peripheral region of the opening. Effect of the Invention

[0009] According to the present invention, it is possible to provide a liquid ejection head that is capable of preventing ejection failure and damage, regardless of the surface condition, such as fuzz, of the recording medium onto which the liquid is to be ejected. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view showing an example of a main part of a liquid ejection head according to an embodiment of the present invention. [Diagram 2] 5 is a schematic diagram showing a state before a cover member of the liquid ejection head according to the embodiment is bonded to a nozzle plate. FIG. [Diagram 3] FIG. [Figure 4] 1A and 1B are plan schematic views showing a first embodiment and a second embodiment of a cover member of a liquid ejection head according to the present embodiment. [Diagram 5] FIG. 2 is an explanatory cross-sectional view taken along a direction perpendicular to the nozzle arrangement direction of the liquid ejection head. [Figure 6] FIG. 2 is a cross-sectional explanatory diagram taken along the nozzle arrangement direction of the liquid ejection head. [Figure 7] FIG. 2 is an external perspective view of the liquid ejection head. [Figure 8] FIG. 2 is an explanatory cross-sectional view taken along a direction perpendicular to the nozzle arrangement direction of the liquid ejection head. [Figure 9] FIG. 1 is an explanatory diagram illustrating an example of an apparatus for discharging liquid. [Figure 10] 10 is a plan view illustrating a head unit included in the liquid ejecting device of FIG. 9. FIG. [Figure 11] FIG. 2 is a block diagram illustrating a liquid circulating device that constitutes the liquid supply device. [Figure 12] FIG. 2 is a plan view illustrating a main part of the device for discharging liquid. [Figure 13] FIG. 2 is a side view illustrating a main part of the device for discharging liquid. [Figure 14] FIG. 2 is a plan view illustrating a main portion of an example of a liquid ejection unit. [Figure 15] FIG. 2 is a front view illustrating a main portion of an example of a liquid ejection unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A liquid ejection head, a liquid ejection unit, and a liquid ejection device according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiments, and may be modified within the scope of what a person skilled in the art can imagine, such as other embodiments, additions, modifications, deletions, etc., and any aspect is within the scope of the present invention as long as it provides the functions and effects of the present invention.

[0012] Fig. 1 is a schematic cross-sectional view of a main part showing an example of a liquid ejection head according to an embodiment of the present invention, Fig. 2 is a schematic view showing a state before a cover member of the liquid ejection head according to the embodiment is bonded to a nozzle plate, and Fig. 3 is an explanatory view of the cover member.

[0013] A liquid ejection head 100 according to the present invention comprises a nozzle plate 1 having nozzles 4 for ejecting liquid droplets, and a cover member 40 having an opening 41 exposing the nozzles 4 and covering at least the outer periphery of the nozzles 4 . The cover member 40 has a protrusion 44 that protrudes in the droplet ejection direction in a peripheral region of the opening 41 (for example, a region indicated by reference symbol 42 in FIG. 3) and in a region outside the peripheral region 42 of the opening 41. The liquid ejection direction is the direction indicated by arrow E in FIG.

[0014] As shown in FIG. 2, the cover member 40 is a member that covers the area of ​​the nozzle plate 1 other than the nozzles 4 (nozzle row), and is bonded with an adhesive. As shown in FIG. 1, a fillet-shaped portion 45 of adhesive is formed between the outer end of the cover member 40 and the main body of the liquid ejection head 100. The fillet-shaped portion 45 is formed by the adhesive that has squeezed out due to the pressure applied during bonding, or the refilled adhesive, spreading approximately uniformly between the liquid ejection head 100 and the outer end portion of the cover member 40 (for example, the area indicated by the symbol 46 in FIG. 3).

[0015] By forming the fillet-shaped portion 45, the adhesive strength between the cover member 40 and the main body of the liquid ejection head 100 is increased, so that peeling due to an external force such as a collision of a recording medium can be prevented.

[0016] The convex portion 44 of the cover member 40 is provided to come into contact with foreign matter such as fuzz that appears on the surface of the recording surface of the recording medium, and to smooth the surface by bending and pressing down the foreign matter as it moves, thereby preventing the foreign matter from coming into contact with the nozzle 4. The degree of fuzzing and the length of foreign matter such as fuzz vary depending on the material and type of recording medium, but by appropriately adjusting the height of the convex portion 44, it is possible to prevent foreign matter such as fuzz from coming into contact with the nozzle 4 without increasing the height difference between the nozzle plate 1 and the cover member 40.

[0017] The convex portion 44 of the cover member 40 is provided in the peripheral region 42 of the opening 41 and in a region outside the peripheral region 42 of the opening 41, but the latter convex portion 44 is preferably provided in the peripheral region of the outer end of the cover member 40 (for example, the region indicated by the symbol 43 in Figure 3). By increasing the intervals at which the convex portions 44 are arranged, the surface of the recording medium can be more reliably leveled.

[0018] The convex portion 44 preferably extends at least in a direction perpendicular to the scanning direction of the liquid ejection head 100 (arrow D). Moreover, it is preferable that the protrusion 44 extends in a direction perpendicular to the arrangement direction of the plurality of nozzles 4 (nozzle row). Furthermore, it is preferable that the convex portion 44 is provided at least on the downstream side in the scanning direction (arrow D) of the liquid ejection head 100. That is, in a mode in which the liquid ejection head 100 is mounted on an apparatus, it is preferable that the liquid ejection head 100 scans so that the convex portion 44 is at the front. This makes it possible to more reliably prevent the fluff from coming into contact with the nozzle 4, and also makes it possible to eject the liquid onto a surface smoothed by the protrusions 44.

[0019] 4A and 4B are plan schematic diagrams showing examples of a cover member 40 of a liquid ejection head according to the present embodiment, with FIG. 4A showing a first embodiment and FIG. 4B showing a second embodiment. The arrangement of the convex portion 44 is not limited to these, but may be, for example, as shown in Figure 4(A) in which the convex portion 44 is arranged only in the longitudinal direction perpendicular to the scanning direction of the liquid ejection head 100, or as shown in Figure 4(B) in which the convex portion 44 is arranged around the entire periphery of the peripheral region 42 of the opening 41 and the peripheral region 43 of the outer end of the cover member 40.

[0020] The method for forming the convex portion 44 is not particularly limited, but examples include a method in which the convex portion 44 is formed integrally with the cover member 40 by drawing or the like, and a method in which the convex portion 44 is formed by joining a separate member using welding or an adhesive or the like. The material of the protrusion 44 formed as a separate member may be the same as or different from the material of the cover member 40. Examples of the material of the protrusion 44 include metal and resin.

[0021] If the convex portion 44 comes into contact with the recording surface of the recording medium, there is a risk that the image formed by the ejection of liquid will be soiled, resulting in a decrease in quality. Therefore, when the liquid ejection head 100 is mounted on the device, it is preferable that the convex portion 44 does not come into contact with the recording surface of the recording medium onto which the liquid droplets are ejected.

[0022] Incidentally, when forming an image by ejecting ink from the liquid ejection head 100, it is necessary for the liquid droplets ejected from the nozzles 4 to travel straight in a direction perpendicular to the nozzle plate 1 in order to obtain high image quality. However, if the surface of the nozzle plate 1 is not sufficiently cleaned or if it is driven continuously for a long period of time, droplets may accumulate around the nozzle 4, particularly at the step with the opening 41 of the cover member 40. If the accumulated droplets gradually increase and adhere to the periphery of the nozzle 4, they may be pulled by the adhered liquid, causing the ejection to bend.

[0023] In order to prevent such problems, it is preferable to apply an ink-repellent treatment to the surface of the cover member 40 and the surface of the nozzle plate 1 except for the side surface of the opening 41, and to apply an ink-philic treatment to the side surface of the opening 41. By making the side surfaces of the opening 41 ink-philic rather than providing an ink-repellent layer, an evacuation area for excess droplets is formed, and highly linear ejection can be achieved for a long period of time. In addition, when the liquid to be ejected is a liquid other than ink, it is preferable to similarly apply a treatment to the surface of the cover member 40, excluding the side of the opening 41, and the surface of the nozzle plate 1 to repel the liquid, and to apply a treatment to the side of the opening 41 to give it affinity with the liquid.

[0024] As described above, according to the liquid ejection head of the present embodiment, ejection defects and damage can be prevented regardless of the surface condition of the recording medium, such as fuzziness. An example of a liquid ejection head to which the present invention can be applied, and a liquid ejection unit and an apparatus for ejecting liquid that include a liquid ejection head according to the present invention will be described below.

[0025] A "liquid ejection unit" is a liquid ejection head integrated with functional parts and mechanisms, and includes a collection of parts related to ejecting liquid. For example, a "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.

[0026] Here, integration includes, for example, a liquid ejection head, a functional part, and a mechanism that are fixed to each other by fastening, bonding, engaging, etc., and one is held movably relative to the other. Also, the liquid ejection head, the functional part, and the mechanism may be configured to be detachable from each other.

[0027] For example, there are liquid ejection units in which the liquid ejection head and the head tank are integrated together, and there are also liquid ejection units in which the liquid ejection head and the head tank are 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.

[0028] Furthermore, there is a liquid ejection unit in which the liquid ejection head and the carriage are integrated.

[0029] In some liquid ejection units, the liquid ejection head is movably supported by a guide member that constitutes a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated together, and in some liquid ejection units, the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated together.

[0030] 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 the liquid ejection head is attached, thereby integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

[0031] In addition, some liquid ejection units have a head tank or a liquid ejection head to which a flow path component is attached, and a tube is connected to the liquid ejection head, 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.

[0032] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0033] 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.

[0034] This "liquid ejecting device" can also include means for feeding, transporting, and discharging items onto which liquid can be attached, as well as pre-processing devices and post-processing devices.

[0035] For example, examples of "devices that eject liquid" include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0036] In addition, the term "liquid ejection device" is not limited to devices that use ejected liquid to visualize meaningful images such as letters and figures. For example, it also includes devices that form patterns that have no meaning in themselves and devices that create three-dimensional images.

[0037] "Something to which a liquid can adhere" means something to which a liquid can adhere at least temporarily, something to which the liquid adheres and sticks, something to which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording media, electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all things to which a liquid can adhere.

[0038] The material to which the liquid can adhere may be any material to which the liquid can adhere, even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, or ceramics.

[0039] Furthermore, the "liquid ejection device" may be a device in which a liquid ejection head and an object to which liquid can be attached move relatively, but is not limited to this. Specific examples include a serial type device in which a liquid ejection head moves, a line type device in which a liquid ejection head does not move, etc.

[0040] Other examples of "liquid ejecting devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0041] In the present application, the terms image formation, recording, printing, imprinting, printing, modeling, and the like are all synonymous.

[0042] (Liquid ejection head) An embodiment of a liquid ejection head to which the present invention can be applied will be described with reference to Figures 5 and 6. Figure 5 is a cross-sectional explanatory diagram taken along a direction (longitudinal direction of pressure chambers) perpendicular to the nozzle arrangement direction of the liquid ejection head according to the embodiment, and Figure 6 is a cross-sectional explanatory diagram taken along the nozzle arrangement direction.

[0043] The liquid ejection head 100 is formed by laminating and joining a nozzle plate 1, a flow path plate 2 which is an individual flow path member, and a vibration plate member 3 which serves as a wall member. It also includes a piezoelectric actuator 11 which displaces a vibration region (vibration plate) 30 of the vibration plate member 3, and a common flow path member 20 which also serves as a frame member of the head.

[0044] The nozzle plate 1 has a plurality of nozzles 4 for ejecting liquid.

[0045] The flow path plate 2 forms a plurality of pressure chambers 6 communicating with a plurality of nozzles 4, individual supply flow paths 7 which are individual flow paths communicating with each of the pressure chambers 6, and an intermediate supply flow path 8 which serves as a liquid introduction section communicating with one or more (one in this embodiment) individual supply flow paths 7.

[0046] The diaphragm member 3 has a plurality of displaceable diaphragms (vibration regions) 30 that form the wall surfaces of the pressure chambers 6 of the flow path plate 2. Here, the diaphragm member 3 has a two-layer structure (not limited to this) and is composed of a first layer 3A that forms a thin portion from the flow path plate 2 side and a second layer 3B that forms a thick portion.

[0047] A deformable vibration region 30 is formed in the first layer 3A, which is a thin portion, in a portion corresponding to the pressure chamber 6. Within the vibration region 30, a convex portion 30a, which is a thick portion that is bonded to the piezoelectric actuator 11, is formed in the second layer 3B.

[0048] A piezoelectric actuator 11 including an electromechanical conversion element is disposed on the opposite side of the diaphragm member 3 to the pressure chamber 6 as a driving means (actuator means, pressure generating means) for deforming the vibration area 30 of the diaphragm member 3.

[0049] This piezoelectric actuator 11 is formed by forming grooves by half-cut dicing in a piezoelectric member bonded onto a base member 13, and forming a required number of columnar piezoelectric elements 12 in a comb shape at specified intervals in the nozzle arrangement direction. The piezoelectric elements 12 are bonded to protruding portions 30a, which are thick portions formed in the vibration region 30 of the vibration plate member 3.

[0050] This piezoelectric element 12 is formed by alternately laminating piezoelectric layers and internal electrodes, with the internal electrodes being drawn out to the end faces and connected to external electrodes (end face electrodes), and flexible wiring member 15 being connected to the external electrodes.

[0051] The common flow path member 20 forms a common supply flow path 10 that communicates with the multiple pressure chambers 6. The common supply flow path 10 communicates with an intermediate supply flow path 8 that serves as a liquid introduction section via an opening 9 provided in the vibration plate member 3, and communicates with the individual supply flow paths 7 via the intermediate supply flow path 8.

[0052] In this liquid ejection head 100, for example, by lowering the voltage applied to the piezoelectric element 12 from a reference potential (intermediate potential), the piezoelectric element 12 contracts, the vibration area 30 of the vibration plate member 3 is pulled, and the volume of the pressure chamber 6 expands, causing liquid to flow into the pressure chamber 6.

[0053] Thereafter, the voltage applied to the piezoelectric element 12 is increased to expand the piezoelectric element 12 in the stacking direction, and the vibration region 30 of the vibration plate member 3 is deformed in the direction toward the nozzle 4, thereby contracting the volume of the pressure chamber 6, whereby the liquid in the pressure chamber 6 is pressurized and the liquid is ejected from the nozzle 4.

[0054] An example of a circulation type liquid ejection head will be described with reference to FIGS. The liquid ejection head 100 of this embodiment is formed by laminating and bonding a nozzle plate 1, a flow path plate 2, and a vibration plate member 3 serving as a wall member. It also includes a piezoelectric actuator 11 that displaces a vibration region (vibration plate) 30 of the vibration plate member 3, and a common flow path member 20 that also serves as a frame member of the head.

[0055] The flow path plate 2 forms a plurality of pressure chambers 6 each connected to a plurality of nozzles 4 via a nozzle connecting passage 5, a plurality of individual supply flow paths 7 each connected to the plurality of pressure chambers 6 and also serving as fluid resistance sections, and one or more intermediate supply flow paths 8 serving as liquid introduction sections connected to two or more individual supply flow paths 7.

[0056] As in the above embodiment, the individual supply flow path 7 includes two flow path sections, a first flow path section 7A and a second flow path section 7B, which have a higher fluid resistance than the pressure chamber 6, and a third flow path section 7C, which is arranged between the first flow path section 7A and the second flow path section 7B and has a lower fluid resistance than the first flow path section 7A and the second flow path section 7B.

[0057] The flow path plate 2 is formed by stacking a plurality of plate-like members 2A to 2E, but is not limited to this.

[0058] In addition, the flow path plate 2 forms a plurality of individual recovery flow paths 57 along the surface direction of the flow path plate 2, each of which is connected to a plurality of pressure chambers 6 via a nozzle connecting passage 5, and an intermediate recovery flow path 58 which serves as one or more liquid discharge portions connected to two or more individual recovery flow paths 57.

[0059] The individual recovery flow path 57 includes two flow path sections, a first flow path section 57A and a second flow path section 57B, which have a higher fluid resistance than the pressure chamber 6, and a third flow path section 57C, which is disposed between the first flow path section 57A and the second flow path section 57B and has a lower fluid resistance than the first flow path section 57A and the second flow path section 57B. In the individual recovery flow path 57, a flow path section 57D, which is downstream of the second flow path section 57B in the circulation direction, has the same flow path width as the third flow path section 57C.

[0060] The common flow path member 20 forms a common supply flow path 10 and a common recovery flow path 50. In this embodiment, the common supply flow path 10 is composed of a flow path portion 10A that is aligned with the common recovery flow path 50 in the nozzle arrangement direction, and a flow path portion 10B that is not aligned with the common recovery flow path 50.

[0061] The common supply flow path 10 communicates with an intermediate supply flow path 8 serving as a liquid introduction portion through an opening 9 provided in the vibration plate member 3, and communicates with the individual supply flow paths 7 through the intermediate supply flow path 8. The common recovery flow path 50 communicates with an intermediate recovery flow path 58 serving as a liquid outlet portion through an opening 59 provided in the vibration plate member 3, and communicates with an individual recovery flow path 57 through the intermediate recovery flow path 58.

[0062] In addition, the common supply flow path 10 communicates with a supply port 71 , and the common recovery flow path 50 communicates with a recovery port 72 .

[0063] Other aspects such as the layer configuration of the diaphragm member 3 and the configuration of the piezoelectric actuator 11 are similar to those described above.

[0064] In this liquid ejection head 100, the piezoelectric element 12 is stretched in the stacking direction, and the vibration area 30 of the vibration plate member 3 is deformed in a direction toward the nozzle 4, thereby contracting the volume of the pressure chamber 6, thereby pressurizing the liquid in the pressure chamber 6 and ejecting the liquid from the nozzle 4.

[0065] Furthermore, liquid that is not ejected from the nozzles 4 passes through the nozzles 4, is recovered from the individual recovery flow paths 57 to the common recovery flow path 50, and is then re-supplied from the common recovery flow path 50 to the common supply flow path 10 via an external circulation path. Even when liquid is not being ejected from the nozzles 4, liquid circulates from the common supply flow path 10 to the common recovery flow path 50 via the pressure chambers 6, and is then re-supplied to the common supply flow path 10 via an external circulation path.

[0066] In this manner, the liquid ejection head of the present embodiment can attenuate pressure fluctuations accompanying liquid ejection with a simple configuration, and suppress propagation of the pressure fluctuations to the common supply flow path 10 and the common recovery flow path 50.

[0067] (Liquid ejection device) Next, an example of a liquid ejecting device according to the present invention will be described with reference to Figures 9 and 10. Figure 9 is a schematic explanatory diagram of the device, and Figure 10 is a plan explanatory diagram of an example of a head unit of the device. The liquid ejection device according to the present invention includes the liquid ejection head 100 according to the present invention described above. In the liquid ejecting device of this embodiment, the convex portion 44 of the cover member 40 of the liquid ejection head 100 does not contact the recording surface of the recording medium onto which the droplets are ejected, and the convex portion 44 is provided on the leading side in the direction of movement relative to the recording surface of the recording medium onto which the droplets are ejected.

[0068] The printing device 500, which is an apparatus for ejecting liquid, is equipped with an input means 501 for transporting a continuous body 510 such as continuous paper or sheet material, which is a recording medium, a guide and transport means 503 for guiding and transporting the continuous body 510 transported from the input means 501 to a printing means 505, the printing means 505 for ejecting liquid onto the continuous body 510 to print an image, a drying means 507 for drying the continuous body 510, and an ejection means 509 for ejecting the continuous body 510.

[0069] The continuous body 510 is sent out from the original winding roller 511 of the carrying-in means 501 , guided and transported by the rollers of the carrying-in means 501 , the guiding and transporting means 503 , the drying means 507 , and the carrying-out means 509 , and taken up by the take-up roller 591 of the carrying-out means 509 .

[0070] This continuous body 510 is transported in the printing means 505 on a transport guide member 559 opposite the head unit 550 and head unit 555, an image is formed by liquid ejected from the head unit 550, and post-processing is performed with processing liquid ejected from the head unit 555.

[0071] Here, in the head unit 550, for example, full line type head arrays 551A, 551B, 551C, and 551D for four colors (hereinafter, referred to as "head array 551" when no distinction is made between colors) are arranged from the upstream side in the transport direction.

[0072] Each head array 551 is a liquid ejection means, and ejects liquid of black K, cyan C, magenta M, and yellow Y onto the transported continuum 510. The types and number of colors are not limited to these.

[0073] Head array 551 is, for example, liquid ejection heads (also simply referred to as "heads") 100 according to the present invention arranged in a staggered pattern on base member 552, but is not limited to this.

[0074] Next, an example of a liquid circulating device will be described with reference to FIG. Fig. 11 is a block diagram of the circulation device. Note that, although only one liquid ejection head (referred to as "head" in the figure) 100 is shown here, when multiple heads are arranged, the supply side liquid path and the recovery side liquid path will be connected to the supply side and recovery side of the multiple heads, respectively, via a manifold or the like.

[0075] The liquid circulation device 600 is composed of a supply tank 601, a recovery tank 602, a main tank 603, a first liquid feed pump 604, a second liquid feed pump 605, a compressor 611, a regulator 612, a vacuum pump 621, a regulator 622, a supply side pressure sensor 631, and a recovery side pressure sensor 632.

[0076] Here, the compressor 611 and the vacuum pump 621 constitute a means for generating a pressure difference between the pressure in the supply tank 601 and the pressure in the recovery tank 602 .

[0077] The supply side pressure sensor 631 is located between the supply tank 601 and the head 100, and is connected to a supply side liquid path connected to the supply port 71 of the head 100. The recovery side pressure sensor 632 is located between the head 100 and the recovery tank 602, and is connected to a recovery side liquid path connected to the recovery port 72 of the head 100.

[0078] One side of the recovery tank 602 is connected to the supply tank 601 via a first liquid feed pump 604 , and the other side of the recovery tank 602 is connected to the main tank 603 via a second liquid feed pump 605 .

[0079] As a result, liquid flows into the head 100 from the supply tank 601 through the supply port 71, is recovered through the recovery port 72 to the recovery tank 602, and the liquid is sent from the recovery tank 602 to the supply tank 601 by the first liquid delivery pump 604, thereby forming a circulation path through which the liquid circulates.

[0080] Here, a compressor 611 is connected to the supply tank 601 and is controlled so that a supply side pressure sensor 631 detects a predetermined positive pressure. On the other hand, a vacuum pump 621 is connected to the recovery tank 602 and is controlled so that a recovery side pressure sensor 632 detects a predetermined negative pressure.

[0081] This allows liquid to be circulated through the head 100 while maintaining a constant negative pressure at the meniscus.

[0082] Furthermore, when liquid is discharged from the nozzles 4 of the head 100, the amount of liquid in the supply tank 601 and the recovery tank 602 decreases. Therefore, the second liquid feed pump 605 is used to replenish the recovery tank 602 with liquid from the main tank 603 as appropriate.

[0083] The timing of refilling the liquid from the main tank 603 to the recovery tank 602 can be controlled based on the detection results of a liquid level sensor installed in the recovery tank 602, such as refilling the liquid when the liquid level in the recovery tank 602 falls below a predetermined level.

[0084] Next, another example of a printing device as a device for ejecting liquid according to the present invention will be described with reference to Figures 12 and 13. Figure 12 is an explanatory plan view of the main parts of the device, and Figure 13 is an explanatory side view of the main parts of the device.

[0085] The printing device 500 is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by a main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is hung between left and right side plates 491A and 491B to movably hold the carriage 403. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via a timing belt 408 hung between a drive pulley 406 and a driven pulley 407.

[0086] A liquid ejection unit 440 is mounted on this carriage 403, which integrates the liquid ejection head 100 according to the present invention and a head tank 441. The liquid ejection head 100 of the liquid ejection unit 440 ejects liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 100 is mounted with a nozzle row made up of a plurality of nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ejection direction facing downward.

[0087] The liquid ejection head 100 is connected to the above-mentioned liquid circulation device 600, and liquid of a desired color is circulated and supplied.

[0088] The printing apparatus 500 includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

[0089] The conveyor belt 412 attracts the paper 410 and conveys it to a position facing the liquid ejection head 100. The conveyor belt 412 is an endless belt, and is stretched between a conveyor roller 413 and a tension roller 414. The paper can be attracted by electrostatic attraction or air suction.

[0090] The conveyor belt 412 moves in a circular motion in the sub-scanning direction as the conveyor rollers 413 are rotated by a sub-scanning motor 416 via a timing belt 417 and a timing pulley 418 .

[0091] Furthermore, a maintenance and recovery mechanism 420 for performing maintenance and recovery of the liquid ejection head 100 is disposed on one side of the conveyor belt 412 on one side of the carriage 403 in the main scanning direction.

[0092] The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (surface on which nozzles are formed) of the liquid ejection head 100, a wiper member 422 that wipes the nozzle surface, and the like.

[0093] The main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the transport mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

[0094] In the printing device 500 configured in this manner, the paper 410 is fed onto the conveyor belt 412 and adsorbed thereon, and the paper 410 is conveyed in the sub-scanning direction by the circular movement of the conveyor belt 412.

[0095] Therefore, by driving the liquid ejection head 100 in response to an image signal while moving the carriage 403 in the main scanning direction, liquid is ejected onto the stationary paper 410 to form an image.

[0096] (Liquid Discharge Unit) Another example of the liquid discharge unit according to the present invention will be described with reference to FIGS. The liquid ejection device according to the present invention includes the liquid ejection head 100 according to the present invention described above.

[0097] FIG. 14 is a plan view illustrating a main portion of an example of a liquid ejection unit. This liquid ejection unit 440 is composed of, among the components that make up the device that ejects the liquid, a housing portion consisting of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid ejection head 100.

[0098] It is also possible to configure a liquid discharge unit in which the above-mentioned maintenance and recovery mechanism 420 is further attached to, for example, the side plate 491B of this liquid discharge unit 440.

[0099] FIG. 17 is a front view illustrating an example of a liquid ejection unit. The liquid ejection unit 440 is composed of a liquid ejection head 100 to which a flow path part 444 is attached, and a tube 456 connected to the flow path part 444 .

[0100] The flow path part 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path part 444. Furthermore, a connector 443 for electrically connecting with the liquid ejection head 100 is provided on the upper part of the flow path part 444. [Explanation of symbols]

[0101] 1 Nozzle plate 4 Nozzles 40 Cover member 41 Opening 44 Convex 45 Fillet shape part 100 Liquid ejection head 440 Liquid Dispensing Unit 500 Liquid ejecting device (printing device) [Prior art documents] [Patent documents]

[0102] [Patent Document 1] JP 2006-68981 A

Claims

1. a nozzle plate having nozzles for ejecting droplets; a cover member having an opening for exposing the nozzle and covering at least an outer periphery of the nozzle; The cover member is bonded with an adhesive, and has a convex portion that protrudes in the droplet ejection direction in the peripheral region of the opening and in a region outside the peripheral region of the opening.

2. The liquid ejection head according to claim 1 , wherein the cover member has the convex portion on a peripheral region of the opening and on a peripheral region of an outer end of the cover member.

3. 3. The liquid ejection head according to claim 1, wherein the convex portion extends at least in a direction perpendicular to a scanning direction of the liquid ejection head.

4. 4. The liquid ejection head according to claim 1, wherein the convex portion is provided at least on a downstream side in a scanning direction of the liquid ejection head.

5. 3. The liquid ejection head according to claim 1, wherein the cover member has a fillet-shaped portion of adhesive on an outer edge of the cover member.

6. 6. A liquid ejection head according to claim 1, wherein the surface of the cover member excluding the side of the opening and the surface of the nozzle plate are treated to be ink repellent, and the side of the opening of the cover member is treated to be ink-philic.

7. A liquid ejection unit comprising the liquid ejection head according to claim 1 .

8. 7. A liquid ejection device comprising the liquid ejection head according to claim 1.

9. 9. The liquid ejecting device according to claim 8, wherein the convex portion of the cover member of the liquid ejection head does not come into contact with a recording surface of a recording medium onto which droplets are ejected.

10. 10. The liquid ejecting device according to claim 8, wherein the convex portion of the cover member of the liquid ejection head is provided on the leading side in a moving direction relative to a recording surface of a recording medium onto which droplets are ejected.

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