JP7600585B2 - LIQUID DISCHARGE HEAD, LIQUID DISCHARGE UNIT, AND DEVICE FOR DISCHARGING LIQUID - Google Patents

Description

The present invention relates to a liquid ejection head, a liquid ejection unit, and a device for ejecting liquid.

As image forming devices such as printers, facsimiles, copiers, plotters, and combination machines thereof, devices that eject liquid using a liquid ejection head that ejects ink droplets (e.g., inkjet recording devices) are known.

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, to protect the head from external forces such as contact with cleaning members such as wipers and collisions with the recording medium (ejection target) in the event of a jam (see, for example, Patent Document 1).

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 deviation in the landing position of droplets and mistification of droplets before landing.
In response to this, Japanese Patent Laid-Open No. 2003-233663 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.

A device that ejects liquid is a device that is capable of ejecting liquid onto an object onto which the liquid can adhere. Here, "an object onto which the liquid can adhere" means an object 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.

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.

The present invention aims to provide a liquid ejection head that can prevent ejection failures and damage regardless of the surface condition, such as fuzziness, of the recording medium onto which the liquid is to be ejected.

In order to solve the above problems, the liquid ejection head of the present invention comprises a nozzle plate having a nozzle for ejecting liquid droplets, and a cover member having an opening exposing the nozzle and covering at least the outer periphery of the nozzle, the cover member being joined with an adhesive and having a plurality of convex portions protruding in the direction of droplet ejection in the peripheral region of the opening and in a region outside the peripheral region of the opening.

The present invention provides a liquid ejection head that can prevent ejection failures and damage regardless of the surface condition, such as fuzziness, of the recording medium onto which the liquid is to be ejected.

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. 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. FIG. 1A and 1B are schematic plan views showing a first embodiment (A) and a second embodiment (B) of a cover member of a liquid ejection head according to the present embodiment. FIG. 2 is an explanatory cross-sectional view taken along a direction perpendicular to the nozzle arrangement direction of the liquid ejection head. FIG. 2 is a cross-sectional explanatory diagram taken along the nozzle arrangement direction of the liquid ejection head. FIG. 2 is an external perspective view of the liquid ejection head. FIG. 2 is an explanatory cross-sectional view taken along a direction perpendicular to the nozzle arrangement direction of the liquid ejection head. FIG. 1 is an explanatory diagram illustrating an example of an apparatus for discharging liquid. 10 is a plan view illustrating a head unit included in the liquid ejecting device of FIG. 9 . FIG. 2 is a block diagram illustrating a liquid circulating device that constitutes the liquid supply device. FIG. 2 is a plan view illustrating a main part of the device for discharging liquid. FIG. 2 is a side view illustrating a main part of the device for discharging liquid. FIG. 2 is a plan view illustrating a main portion of an example of a liquid ejection unit. FIG. 2 is a front view illustrating a main portion of an example of a liquid ejection unit.

The liquid ejection head, liquid ejection unit, and 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 embodiments shown below, and can be modified within the scope of what a person skilled in the art can imagine, including other embodiments, additions, modifications, deletions, etc., and any aspect is within the scope of the present invention as long as it achieves the functions and effects of the present invention.

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

The 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 convex portion 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.

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 when the adhesive that has overflowed due to the pressure applied during joining, or the replenished adhesive, spreads approximately evenly 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 Figure 3).

The formation of the fillet-shaped portion 45 increases the adhesive strength between the cover member 40 and the liquid ejection head 100 body, preventing peeling due to external forces such as the collision of the recording medium.

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.

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 it is preferable that the latter convex portion 44 is 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.

The convex portion 44 preferably extends at least in a direction perpendicular to the scanning direction (arrow D) of the liquid ejection head 100 .
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. In other words, in a state 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 fuzz from coming into contact with the nozzle 4, and also makes it possible to eject liquid onto a surface smoothed by the convex portion 44.

4A and 4B are schematic plan views 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.

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, etc.
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.

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 may 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 droplets are ejected.

Incidentally, when forming an image by ejecting ink from the liquid ejection head 100, in order to obtain high image quality, it is necessary for the liquid droplets ejected from the nozzles 4 to travel straight in a direction perpendicular to the nozzle plate 1.
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, there is a risk that droplets will 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.

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.

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.

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

Here, integration includes, for example, the liquid ejection head, functional parts, and mechanism being fixed to each other by fastening, bonding, engagement, etc., and one being held movably relative to the other. The liquid ejection head, functional parts, and mechanism may also be configured to be detachable from each other.

For example, some liquid ejection units have a liquid ejection head and a head tank integrated together. Others have a liquid ejection head and a head tank integrated together by connecting them to each other with a tube or the like. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

There are also liquid ejection units in which the liquid ejection head and carriage are integrated.

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. In other liquid ejection units, the liquid ejection head, carriage, and main scanning movement mechanism are integrated.

In some liquid ejection units, 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, integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

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 from a liquid storage source is supplied to the liquid ejection head via this tube.

The main scanning movement mechanism includes the guide member alone. The supply mechanism also includes the tube alone and the loading section alone.

"Devices that eject liquid" include devices that have a liquid ejection head or liquid ejection unit and eject liquid by driving the liquid ejection head. Devices that eject liquid 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.

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.

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 to form a three-dimensional object.

In addition, a "liquid ejecting 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.

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

Materials that can receive liquid include paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, etc., as long as the liquid can be attached even temporarily.

In addition, 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 the liquid ejection head moves, and a line type device in which the liquid ejection head does not move.

Other examples of "liquid ejecting devices" include treatment liquid application devices that eject 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 spray granulation devices that spray a composition liquid in which raw materials are dispersed through a nozzle to granulate the raw material into fine particles.

In this application, the terms image formation, recording, printing, copying, printing, modeling, etc. are all synonymous.

(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 view taken along a direction perpendicular to the nozzle arrangement direction (longitudinal direction of pressure chambers) of the liquid ejection head according to the embodiment, and Figure 6 is a cross-sectional explanatory view taken along the nozzle arrangement direction.

The liquid ejection head 100 is made by laminating and bonding 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 the 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 for the head.

The nozzle plate 1 has multiple nozzles 4 that eject liquid.

The flow path plate 2 forms a number of pressure chambers 6 that communicate with a number of nozzles 4, individual supply flow paths 7 that are individual flow paths that communicate with each pressure chamber 6, and an intermediate supply flow path 8 that serves as a liquid introduction section that communicates with one or more (one in this embodiment) individual supply flow paths 7.

The vibration plate member 3 has a plurality of displaceable vibration plates (vibration regions) 30 that form the walls of the pressure chamber 6 of the flow path plate 2. Here, the vibration plate 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.

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

A piezoelectric actuator 11 including an electromechanical conversion element is disposed on the opposite side of the vibration plate member 3 from the pressure chamber 6 as a driving means (actuator means, pressure generating means) that deforms the vibration region 30 of the vibration plate member 3.

This piezoelectric actuator 11 is formed by forming grooves in a piezoelectric member bonded to a base member 13 by half-cut dicing, 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 then bonded to the protruding portions 30a, which are thick portions formed in the vibration region 30 of the vibration plate member 3.

This piezoelectric element 12 is made by alternately stacking piezoelectric layers and internal electrodes, with the internal electrodes each extending to the end faces and connected to external electrodes (end face electrodes), and flexible wiring members 15 are connected to the external electrodes.

The common flow path member 20 forms a common supply flow path 10 that connects to multiple pressure chambers 6. The common supply flow path 10 communicates with an intermediate supply flow path 8, which 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.

In this liquid ejection head 100, for example, by lowering the voltage applied to the piezoelectric element 12 from the reference potential (intermediate potential), the piezoelectric element 12 contracts, the vibration region 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.

Then, 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, 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.

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.

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

As in the previous embodiment, the individual supply flow path 7 includes two flow paths, 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 disposed 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.

The flow path plate 2 is constructed by stacking multiple plate-like members 2A to 2E, but is not limited to this.

The flow path plate 2 also 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 communication passage 5, and one or more intermediate recovery flow paths 58 that serve as liquid outlet sections that are connected to two or more individual recovery flow paths 57.

The individual recovery flow path 57 includes two flow paths, 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. The individual recovery flow path 57 includes a flow path section 57D, which is downstream of the second flow path section 57B in the circulation direction, and has the same flow path width as the third flow path section 57C.

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.

The common supply flow path 10 communicates with an intermediate supply flow path 8, which serves as a liquid introduction section, through an opening 9 provided in the vibration plate member 3, and communicates with 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, which serves as a liquid discharge section, through an opening 59 provided in the vibration plate member 3, and communicates with individual recovery flow paths 57 through the intermediate recovery flow path 58.

In addition, the common supply flow path 10 is connected to the supply port 71, and the common recovery flow path 50 is connected to the recovery port 72.

The other layer configurations of the diaphragm member 3 and the configuration of the piezoelectric actuator 11 are the same as those described above.

In this liquid ejection head 100, the piezoelectric element 12 is expanded in the stacking direction, and the vibration region 30 of the vibration plate member 3 is deformed in the direction toward the nozzle 4 to contract the volume of the pressure chamber 6, thereby pressurizing the liquid in the pressure chamber 6 and ejecting the liquid from the nozzle 4.

In addition, liquid that is not ejected from the nozzle 4 passes through the nozzle 4 and is recovered from the individual recovery flow path 57 to the common recovery flow path 50, and is then resupplied 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 nozzle 4, liquid circulates from the common supply flow path 10 to the common recovery flow path 50 via the pressure chamber 6, and is then resupplied to the common supply flow path 10 via an external circulation path.

In this way, the liquid ejection head of this embodiment can attenuate pressure fluctuations associated with liquid ejection with a simple configuration and suppress propagation to the common supply flow path 10 and the common recovery flow path 50.

(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 above-described liquid ejection head 100 according to the present invention.
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.

The printing device 500, which is a device that ejects liquid, includes an input means 501 that inputs a continuous web 510 such as continuous paper or sheet material that is a recording medium, a guide and conveyance means 503 that guides and conveys the continuous web 510 input from the input means 501 to a printing means 505, a printing means 505 that ejects liquid onto the continuous web 510 to print an image, a drying means 507 that dries the continuous web 510, and an ejection means 509 that ejects the continuous web 510.

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 guide and transport means 503, the drying means 507, and the carrying-out means 509, and then wound up by the winding roller 591 of the carrying-out means 509.

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

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

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

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

Next, an example of a liquid circulating device will be described with reference to FIG.
11 is a block diagram of the circulation device. Note that, although only one liquid ejection head (represented 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 are connected to the supply side and recovery side of the multiple heads, respectively, via a manifold or the like.

The liquid circulation device 600 is composed of a supply tank 601, a recovery tank 602, a main tank 603, a first liquid delivery pump 604, a second liquid delivery 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.

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.

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.

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

As a result, liquid flows from the supply tank 601 through the supply port 71 into the head 100, is collected from the collection port 72 into the collection tank 602, and the first liquid supply pump 604 sends the liquid from the collection tank 602 to the supply tank 601, thereby forming a circulation path through which the liquid circulates.

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

This allows liquid to circulate through the head 100 while maintaining a constant negative pressure at the meniscus.

In addition, when liquid is ejected from the nozzle 4 of the head 100, the amount of liquid in the supply tank 601 and the recovery tank 602 decreases. Therefore, the second liquid supply pump 605 is used to replenish liquid from the main tank 603 to the recovery tank 602 as appropriate.

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.

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 a plan view of the main parts of the device, and Figure 13 is a side view of the main parts of the device.

The printing device 500 is a serial type device, and the carriage 403 is moved back and forth in the main scanning direction by the 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, 491B and holds the carriage 403 movably. The carriage 403 is then moved back and forth in the main scanning direction by the main scanning motor 405 via the timing belt 408 hung between the drive pulley 406 and driven pulley 407.

This carriage 403 is equipped with a liquid ejection unit 440 that 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 consisting of multiple nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ejection direction facing downward.

The liquid ejection head 100 is connected to the liquid circulation device 600 described above, and liquid of the required color is circulated and supplied.

This printing device 500 is equipped with a transport mechanism 495 for transporting paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

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 that is stretched between a conveyor roller 413 and a tension roller 414. The paper can be attracted by electrostatic attraction or air suction.

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

Furthermore, a maintenance and recovery mechanism 420 that maintains and recovers the liquid ejection head 100 is arranged on one side of the carriage 403 in the main scanning direction, beside the conveyor belt 412.

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

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

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

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

(Liquid ejection 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 above-described liquid ejection head 100 according to the present invention.

FIG. 14 is a plan view illustrating a main portion of an example of a liquid ejection unit.
Among the components that make up the device for discharging the liquid, this liquid ejection unit 440 is composed of 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.

It is also possible to configure a liquid ejection unit by further attaching the aforementioned maintenance and recovery mechanism 420 to, for example, the side plate 491B of this liquid ejection unit 440.

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 .

The flow path part 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path part 444. A connector 443 is provided on the upper part of the flow path part 444 to electrically connect to the liquid ejection head 100.

1 Nozzle plate 4 Nozzle 40 Cover member 41 Opening 44 Convex portion 45 Fillet-shaped portion 100 Liquid ejection head 440 Liquid ejection unit 500 Apparatus for ejecting liquid (printing apparatus)

JP 2006-68981 A

Claims (10)

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. The liquid ejection head according to claim 1, characterized in that the cover member has the convex portion on the peripheral region of the opening and on the peripheral region of the outer end of the cover member. The liquid ejection head according to claim 1 or 2, characterized in that the convex portion extends at least in a direction perpendicular to the scanning direction of the liquid ejection head. The liquid ejection head according to any one of claims 1 to 3, characterized in that the convex portion is provided at least on the downstream side in the scanning direction of the liquid ejection head. 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. A liquid ejection head according to any one of claims 1 to 5, characterized in that the surface of the cover member excluding the side of the opening and the surface of the nozzle plate are treated with an ink repellent treatment, and the side of the opening of the cover member is treated with an ink repellent treatment. A liquid ejection unit comprising a liquid ejection head according to any one of claims 1 to 6. A liquid ejection device comprising a liquid ejection head according to any one of claims 1 to 6. The liquid ejection device according to claim 8, characterized in that the convex portion of the cover member of the liquid ejection head does not come into contact with the recording surface of the recording medium onto which the droplets are ejected. The liquid ejection device according to claim 8 or 9, characterized in that the convex portion of the cover member of the liquid ejection head is provided on the leading side in the movement direction relative to the recording surface of the recording medium onto which the droplets are ejected.

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