EP4676745A1

EP4676745A1 - Liquid ejection head, liquid ejection apparatus, and method of manufacturing liquid ejection head

Info

Publication number: EP4676745A1
Application number: EP24713760.7A
Authority: EP
Inventors: Atsushi Takeuchi; Gregory John Mcavoy
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2023-03-06
Filing date: 2024-03-05
Publication date: 2026-01-14
Also published as: JP2024125632A; WO2024185761A1; CN120712182A

Abstract

A liquid ejection head 1 includes a nozzle 2 configured to eject a liquid; an individual liquid chamber 4 communicating with the nozzle; and an actuator 5 provided on a nozzle forming wall 110 of the individual liquid chamber 4, the liquid in the individual liquid chamber 4 being ejected from the nozzle by driving the actuator, wherein a partition wall 120a for dividing a liquid flow path 3a and 3b is disposed at an opening 4a of the individual liquid chamber 4, the opening 4a being located on a liquid supply side of the individual liquid chamber 4 and facing the nozzle forming wall 110.

Description

LIQUID EJECTION HEAD, LIQUID EJECTION APPARATUS, AND METHOD OF MANUFACTURING LIQUID EJECTION HEAD

The present disclosure generally relates to a liquid ejection head, a liquid ejection apparatus, and a method of manufacturing a liquid ejection head.

A related-art liquid ejection head is known. The related-art liquid ejection head includes a nozzle configured to eject liquid, an individual liquid chamber configured to communicate with the nozzle, and an actuator provided in a nozzle forming wall of the individual liquid chamber, and configured to eject the liquid in the individual liquid chamber from the nozzle by driving the actuator.

For example, Patent Document 1 discloses a liquid ejection head including a nozzle plate (nozzle forming wall) in which a plurality of nozzles and actuators are formed, and an ink pressure chamber structure in which a plurality of ink pressure chambers (individual liquid chambers) communicating with the plurality of nozzles are formed. Each actuator is formed in an annular shape coaxial with the corresponding nozzle, and is driven to pressurize the ink in each ink pressure chamber.

[PTL 1]　　Japanese Patent No. 6027914

However, in the related art liquid ejection head in which the actuators are provided on the nozzle forming wall of the individual liquid chambers, an ejection failure may be likely to occur due to air bubbles generated in the individual liquid chambers.

Accordingly, one aspect of the present disclosure is to provide a liquid ejection head that includes a nozzle configured to eject a liquid; an individual liquid chamber communicating with the nozzle; and an actuator provided in a nozzle forming wall of the individual liquid chamber, the liquid in the individual liquid chamber being ejected through the nozzle by driving the actuator, wherein a partition wall for dividing a flow path is disposed at an opening of the individual liquid chamber, the opening being located on a liquid supply side of the individual liquid chamber and facing the nozzle forming wall.

Advantageous Effect of the Invention

According to the present disclosure, with respect to a so-called nozzle plate vibration type liquid ejection head with an actuator provided in a nozzle forming wall of an individual liquid chamber, it is possible to prevent ejection failure due to air bubbles remaining in the individual liquid chamber.

FIG. 1 is a cross-sectional view schematically illustrating a nozzle plate vibration type liquid ejection head according to an embodiment. FIG. 2 is a perspective view schematically illustrating a nozzle surface of the liquid ejection head. FIG. 3 is an enlarged sectional view illustrating a peripheral configuration of one individual liquid chamber in the liquid ejection head. FIG. 4 is a front view schematically illustrating an internal structure of the liquid ejection head, which is a sectional view taken along a liquid ejection direction so as to pass through a liquid supply port of a frame portion of the liquid ejection head. FIG. 5 is a plan view schematically illustrating the internal structure of the liquid ejection head, which is a sectional view taken along line A-A′ in FIG. 1. FIG. 6 is an enlarged plan view illustrating the internal structure of the liquid ejection head, which is a sectional view taken along line B-B′ in FIG. 1. FIG. 7 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 8 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 9 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 10 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 11 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 12 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 13 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 14 is a sectional view illustrating a manufacturing process of the liquid ejection head. FIG. 15 is a sectional view schematically illustrating a liquid ejection head according to a first modification. FIG. 16 is a plan view schematically illustrating an internal structure of the liquid ejection head, which is a sectional view taken along line A-A′ in FIG. 15. FIG. 17 is a cross-sectional view schematically illustrating a liquid ejection head according to a second modification. FIG. 18 is an enlarged plan view illustrating an internal structure of a liquid ejection head according to a third modification, which is a sectional view corresponding to a section taken along line B-B′ in FIG. 1. FIG. 19 is a cross-sectional view schematically illustrating a liquid ejection head according to a fourth modification. FIG. 20 is a cross-sectional view schematically illustrating another example of the liquid ejection head according to the fourth modification. FIG. 21 is a schematic explanatory view illustrating a printing apparatus according to an embodiment. FIG. 22 is a plan view illustrating an example of a head unit of the printing apparatus. FIG. 23 is a plan view illustrating a main part of another printing apparatus. FIG. 24 is a side view illustrating a main part of the printing apparatus of the present example. FIG. 25 is a plan view illustrating a main part of a liquid ejection unit of the present example. FIG. 26 is a front view illustrating the liquid ejection unit of the present example.

Hereinafter, embodiments in which the present invention is applied to a liquid ejection head provided in a liquid ejection apparatus will be described. The present invention is not limited to the embodiments described below, and can be modified within the scope that can be conceived by those skilled in the art including other embodiments, additions, alterations, deletions, and the like. Any of the aspects is included in the scope of the present invention as long as the effects of the present disclosure are achieved.

The liquid ejection head according to the present embodiment is a nozzle plate vibration type liquid ejection head that ejects liquid in an individual liquid chamber from a nozzle by varying the pressure of the individual liquid chamber by an actuator, which is provided in a nozzle plate having the nozzle. The nozzle plate vibration type liquid ejection head has a feature that such a liquid ejection head can eject droplets with a smaller force than a general unimorph type piezoelectric head (a piezoelectric head that discharges liquid by vibrating a surface facing a wall (nozzle forming wall) having a communication portion communicating with a nozzle of an individual liquid chamber), and thus it is possible to achieve power saving of the actuator.

When the nozzle density is increased, a space for laying out wiring for applying a voltage is limited, and it appears difficult to construct the wiring on the surface of the substrate. By constructing the wiring and a drive circuit in the substrate, it is possible to lay out the wiring even in a configuration in which the nozzle density is high. Generally, lead zirconate titanate (PZT) is widely used as a material of a piezoelectric element used as an actuator because of its high piezoelectric characteristics. However, when a piezoelectric film is formed on a substrate on which wiring and a driving circuit are formed, the temperature for forming and crystallizing PZT needs to be 600°C or higher. Therefore, when PZT is used as a material of a piezoelectric element, the driving circuit and the wiring in the substrate may not withstand high temperature. Therefore, in a configuration in which wiring and a driving circuit are constructed in a substrate, a piezoelectric material having a lower film forming temperature than PZT is required as the piezoelectric material, and a material having lower piezoelectric characteristics than PZT is inevitably selected. However, since the nozzle plate vibration method described above has a feature that the liquid droplets can be ejected with a smaller force than that of a general unimorph type piezoelectric head, it is possible to satisfactorily eject the liquid even when a material having lower piezoelectric characteristics than PZT is selected. Therefore, even a piezoelectric material such as a non-lead material, which has a low film-forming/crystallization temperature but has a small power, can satisfactorily discharge a liquid. This allows wiring and a driving circuit to be formed in the substrate, and thus, the density can be increased. Further, the nozzle plate vibration method can reduce the volume of the individual liquid chamber, and thus the head can be miniaturized.

FIG. 1 is a cross-sectional view schematically illustrating a nozzle plate vibration type liquid ejection head according to the present embodiment. FIG. 2 is a perspective view schematically illustrating a nozzle surface of the liquid ejection head of the present embodiment. The liquid ejection head 1 includes a nozzle plate 110, an individual liquid chamber substrate 100, and a flow path substrate 120. In addition, the liquid ejection head 1 includes a frame portion 140 and the like as described later.

The nozzle plate 110 is a thin film, and includes a plurality of nozzles 2 configured to eject a liquid, and piezoelectric elements 5 as electromechanical transducer elements, each of which is an annular actuator disposed around a corresponding nozzle 2. The individual liquid chamber substrate 100 includes a plurality of individual liquid chambers (also referred to as pressure chambers or pressurized liquid chambers) 4 communicating with the plurality of nozzles 2. The nozzles 2 (a vibration film 103) are each provided on a first side (a lower surface in FIG. 1) of the corresponding individual liquid chamber 4, and an opening 4a of the individual liquid chamber is disposed on a second side facing the first side. The flow path substrate 120 includes liquid flow paths 3a and 3b which communicate with each of the plurality of individual liquid chambers 4.

FIG. 3 is an enlarged sectional view illustrating a peripheral configuration of one individual liquid chamber in the liquid ejection head according to the present embodiment. The individual liquid chamber substrate 100 is a silicon on insulator (SOI) substrate, and includes a drive circuit 101 and a wiring portion 102 on a side on which the vibration film 103 is formed. The drive circuit 101 is a circuit including a transistor, a resistor, and the like. The wiring portion 102 includes a wiring portion for applying a driving waveform to a first electrode 51 and a wiring portion for applying a driving waveform to a second electrode 53. The wiring portion 102 is electrically connected to an electrical connection pad 55 via a third contact 7c opened in the vibration film 103.

The nozzle plate 110 forms a plurality of nozzles 2 and includes a nozzle forming portion (film) 111 which covers the piezoelectric elements 5. A liquid repellent film 112 may be formed on the nozzle surface of the nozzle forming portion 111. When the liquid is continuously discharged, mist generated simultaneously with the discharge adheres to the nozzle surface. When a large amount of mist adheres to the nozzle surface, the liquid ejected from the nozzle 2 may be affected by the liquid adhering to the nozzle surface and may be deviated from a desired landing position. Forming of the liquid repellent film 112 on the nozzle surface enables preventing adhesion of the liquid to the nozzle surface, and also preventing the liquid ejected from the nozzles 2 from being affected by the liquid adhering to the nozzle surface.

Each of the piezoelectric elements 5 of the nozzle plate 110 includes a first electrode 51 (also referred to as a lower electrode), a piezoelectric film 52, and a second electrode 53 (also referred to as an upper electrode). Each piezoelectric element 5 is covered with a first insulating film 8a. The first insulating film 8a is provided with a hole-shaped fourth contact 7d for electrical connection to the first electrode 51 and a hole-shaped fifth contact 7e for electrical connection to the second electrode 53.

In addition, the first insulating film 8a is provided with a first lead-out wire 9a which electrically connects the first electrode 51 of the piezoelectric element 5 to the wiring portion 102 of the individual liquid chamber substrate 100, and a second lead-out wire 9b which electrically connect the second electrode 53 of the piezoelectric element 5 to the wiring portion 102 of the individual liquid chamber substrate 100.

The first lead-out wire 9a is electrically connected to the first electrode 51 via the fourth contact 7d, and is electrically connected to the wiring portion 102 via the first contact 7a. The second lead-out wire 9b is electrically connected to the second electrode 53 via the fifth contact 7e, and is electrically connected to the wiring portion 102 via the second contact 7b. The first lead-out wire 9a and the second lead-out wire 9b are covered with a second insulating film 8b. In the present embodiment, the second insulating film 8b also covers the piezoelectric element 5, and functions to protect the piezoelectric element 5 by preventing moisture that has entered the resin-made nozzle forming portion 111 from entering the piezoelectric element 5.

Note that the first electrode 51 and the second electrode 53 may be provided with lead-out wiring portions, respectively, and may be directly connected to the wiring portion 102 in an electrode manner via a contact opened in the vibrating film. In addition, an adhesion improving film for ensuring adhesion to the nozzle forming portion 111 may be formed on the second insulating film 8b.

The liquid filled in the liquid ejection head 1 enters the nozzle 2 and forms meniscus in the nozzle. When a predetermined drive waveform (voltage) is applied to each of the electrodes 51 and 53 of the piezoelectric element 5, the piezoelectric film 52 vibrates, and the vibration film 103 vibrates in the vertical direction in FIG. 3. The vibration of the vibration film 103 causes a pressure change in the liquid in the individual liquid chamber, and the liquid is ejected from the nozzle 2.

The material of the vibration film 103 may be any material having at least insulating properties, such as SiO₂, SiN, metallic oxides, and resins. However, in order to increase the deformation, a material having a low Young modulus is desirable, and SiO₂ (silica dioxide), in consideration of the difference in the coefficient of linear expansion from the individual liquid chamber substrate 100, having a relatively small difference is most desirable as the material of the vibration film 103.

The first electrode 51 and the second electrode 53 are preferably made of a metal having a low electrical resistance and low reactivity, such as Ir or Mo. As the piezoelectric material constituting the piezoelectric film 52, in a case where the drive circuit 101 and the wiring portion 102 are built in the individual liquid chamber substrate 100 in order to improve the density as in the present embodiment, a piezoelectric material having a film formation temperature of 450°C or lower is desirable in order not to destroy the drive circuit and the wiring portion. Examples of the piezoelectric material having a film formation temperature of 450°C or lower include AlN and ScAlN having a higher piezoelectric constant than AlN.

Further, the following advantages can be obtained by using ScAlN as the piezoelectric material. That is, although the piezoelectric characteristics can be improved by aligning crystal orientation of the piezoelectric film 52, it is desirable to provide an orientation control layer between the vibration film 103 and the first electrode 51 for the orientation control. When the piezoelectric material of the piezoelectric film 52 is ScAlN, the lattice constant of the first electrode 51 made of Mo can be made close to that of ScAlN by using ScAlN also as the orientation control layer. As a result, the crystal orientation of the piezoelectric film 52 is aligned, and the piezoelectric characteristics can be improved.

FIG. 4 is a front view schematically illustrating an internal structure of the liquid ejection head 1 according to the present embodiment, which is a cross-sectional view taken along a liquid ejection direction so as to pass through a liquid supply port 33 of the frame portion 140. FIG. 5 is a plan view schematically illustrating the internal structure of the liquid ejection head 1 according to the present embodiment, which is a cross-sectional view taken along line A-A′ in FIG. 1. FIG. 6 is an enlarged plan view illustrating the internal structure of the liquid ejection head 1 according to the present embodiment, which is a cross-sectional view taken along line B-B′ in FIG. 1.

As illustrated in FIG. 4, the liquid ejection head 1 according to the present embodiment is configured by arranging a nozzle plate 110, an individual liquid chamber substrate 100, a flow path substrate 120, and a frame portion 140 in this order.

As illustrated in FIG. 5, a plurality of individual liquid chambers 4 are arranged in the individual liquid chamber substrate 100 (not illustrated in FIG. 5), and openings 4a of the respective individual liquid chambers 4 are opened in the upper surface (surface on the flow path substrate 120 side). The liquid flow paths 3a and 3b formed in the flow path substrate 120 are arranged so as to face the openings 4a of the respective individual liquid chambers 4. In the present embodiment, as an example, the size of each individual liquid chamber 4 (the diameter of the opening 4a) is 220 μm, and the width of each partition wall that divides the individual liquid chamber 4 (the sidewall of the individual liquid chamber 4) is 30 μm.

As illustrated in FIGS. 5 and 6, the flow path substrate 120 of the embodiment is provided with flow path partition walls 120a which extend so as to cross the openings 4a of the respective individual liquid chambers 4 of the individual liquid chamber substrate 100. The space separated by the flow path partition walls 120a serves as the liquid flow paths 3a and 3b. In addition, as illustrated in FIG. 5, a supply port 120b for the liquid which flows to each of the liquid flow paths 3a and 3b, and a discharge port 120c for the liquid which flows through each of the liquid flow paths 3a and 3b are formed in the flow path substrate 120. The liquid supplied from the supply port 120b flows along the upper surface of the individual liquid chamber substrate 100 in the liquid flow paths 3a and 3b as indicated by an arrow C in the drawing, and is discharged from the discharge port 120c. Note that the flow path partition wall 120a is an example of a partition wall.

As illustrated in FIG. 4, a frame portion 140 is provided on the upper surface (the surface on the opposite side to the individual liquid chamber substrate 100) of the flow path substrate 120. The supply port 120b of the flow path substrate 120 communicates with a supply liquid storage chamber 31 in the frame portion 140 via a supply communication path 32 formed in the frame portion 140.

The liquid stored in an external liquid storage is supplied to the liquid ejection head 1 via the liquid supply port 33 of the frame portion 140. The liquid supplied from the liquid supply port 33 passes through the supply communication path 32 from the supply liquid storage chamber 31, and is supplied to each of the liquid flow paths 3a and 3b from the supply port 120b. The liquid supplied to the liquid flow paths 3a and 3b is supplied to the individual liquid chambers 4 via the openings 4a of the individual liquid chambers 4.

The discharge port 120c of the flow path substrate 120 communicates with a discharge liquid storage chamber 35 in the frame portion 140 via a discharge communication path formed in the frame portion 140. Accordingly, the liquid that has passed through the liquid flow paths 3a and 3b without being supplied to the individual liquid chambers 4 flows from the discharge port 120c to the discharge liquid storage chamber 35 via the discharge communication path, and is returned to an external ink storage from a liquid discharge port 36 via an external pump or the like.

The liquid ejection head 1 according to the present embodiment is a liquid ejection head of a liquid circulation type, and is capable of circulating liquid in the liquid ejection head 1. This makes it possible to remove air bubbles existing in the liquid ejection head 1, such as in each individual liquid chamber 4 or in each liquid flow path 3a or 3b, to the outside, and to prevent, when a liquid having components that easily settle is used, the components of the liquid from settling in the flow path in the liquid ejection head 1. Note that the liquid flow path 3a or 3b is an example of a flow path.

In a so-called nozzle plate vibration type liquid ejection head 1 with the piezoelectric elements 5 provided on the nozzle forming walls (nozzle plates 110) of the individual liquid chambers 4, air bubbles may remain at the corners of the individual liquid chambers 4 (the connection portions between the vibrating films 103, which are the lower surfaces of the individual liquid chambers 4, and sidewalls 100a of the individual liquid chambers 4). When air bubbles are accumulated in the individual liquid chambers 4, the driving forces of the piezoelectric elements 5 may not propagate properly to the liquid in the individual liquid chambers 4, which may cause a liquid ejection failure.

In the nozzle plate vibration type liquid ejection head, a liquid flow path configured to supply liquid to each individual liquid chamber 4 communicates with the opening 4a of the individual liquid chamber 4 located on the side facing the nozzle plate 110. In the related-art configuration, the entire opening 4a of the individual liquid chamber 4 communicates with one liquid flow path, and thus the movement of the liquid in the individual liquid chamber 4 is small. Therefore, for example, when the liquid is supplied from the opening 4a of the individual liquid chamber 4 into the individual liquid chamber 4 to fill the individual liquid chamber 4 with the liquid during an operation to fill the liquid ejection head with the liquid (liquid filling operation), the air bubbles generated in the corners of the individual liquid chamber 4 are likely to remain in the corners. Further, even when the liquid ejection head is in operation, the movement of the liquid in the individual liquid chamber 4 is small, and therefore, the air bubbles at the corners of the individual liquid chamber 4 continue to stay at the corners, and as a result, an ejection failure is caused.

In the present embodiment, as illustrated in FIGS. 5 and 6, the opening 4a of each individual liquid chamber 4 communicates with a plurality of (two in the present embodiment) liquid flow paths 3a and 3b separated from each other by the flow path partition wall 120a. In other words, the opening 4a of each individual liquid chamber 4 is divided into a plurality of opening portions by the flow path partition wall 120a. According to such a configuration, the liquid flows into the individual liquid chamber 4 from the plurality of liquid flow paths 3a and 3b for replenishing the liquid into the individual liquid chamber 4 after the liquid is ejected from the nozzle, or the liquid in the individual liquid chamber 4 is pushed out to the plurality of liquid flow paths 3a and 3b by the change in the pressure in the individual liquid chamber 4 due to the driving of the piezoelectric element 5. That is, the liquid flows in and out of the individual liquid chamber 4 through the plurality of liquid flow paths 3a and 3b via the openings 4a (a plurality of opening portions) of the individual liquid chamber 4.

Even when the liquid flow paths 3a and 3b have the same structure, and the opening 4a of the individual liquid chamber 4 is divided by the flow path partition wall 120a into exactly equal opening portions, the liquid flowing in and out between each of the liquid flow paths 3a and 3b and the individual liquid chamber 4 will not be the same between the liquid flow paths 3a and 3b due to manufacturing errors and differences in position within the liquid ejection head. Thus, the liquid flowing in and out of the individual liquid chamber 4 is different between the liquid flow paths 3a and 3b, and is asymmetric. Such asymmetric flowing in and out of the liquid can cause more vigorous movement of the liquid in the individual liquid chamber 4, as compared with the related-art configuration in which the entire opening 4a of the individual liquid chamber 4 communicates with one liquid flow path.

As a result, according to the embodiment, the air bubbles staying in the corners of the individual liquid chamber 4 are easily moved from the corners. Therefore, during the liquid filling operation or during the operation of the liquid ejection head, the air bubbles are discharged from the individual liquid chamber 4 to the outside through the nozzle 2, and the occurrence of the ejection failure is prevented. Further, during the liquid filling operation or during the operation of the liquid ejection head, the air bubbles are discharged from the opening 4a of the individual liquid chamber 4 to the liquid flow paths 3a and 3b, and are discharged from the discharge liquid storage chamber 35 to the outside via the discharge port 120c, and thus the occurrence of the ejection failure is prevented.

Next, a method of manufacturing the liquid ejection head of the present embodiment will be described. FIGS. 7 to 14 are cross-sectional views illustrating a manufacturing process of the liquid ejection head 1 according to the present embodiment. The liquid ejection head 1 according to the present embodiment uses a silicon on insulator (SOI) substrate 200 as the substrate, as illustrated in FIG. 7. The SOI substrate includes an active layer (a layer that will serve as an individual liquid chamber substrate 100) 201 which is formed of Si (silicon), a BOX (buried oxide layer) layer 202 which is formed of SiO₂ (silicon dioxide), and a support substrate (a layer that will serve as the flow path substrate 120) 203 which is formed of Si (silicon). A BOX layer 202 functions as an etching prevention film later.

The thickness of the active layer 201 that forms the individual liquid chamber substrate 100 (i.e., a thickness of a liquid chamber sidewall layer that forms a sidewall 100a of the individual liquid chamber 4) is preferably in a range of 1 μm or more to 200 μm or less. When the active layer 201 is less than 1 μm, the height of the individual liquid chamber 4 (a distance from a surface of the nozzle plate 110 [surface of the vibration film 103], on which nozzle 2 is formed, to the opening 4a of the individual liquid chamber 4 or the flow path partition wall 120a of the flow path substrate 120) becomes too small. When the active layer 201 exceeds 200 μm, processing accuracy may be likely to be adversely affected.

The support substrate 203 that will serve as the flow path substrate 120 (i.e., a flow path partition wall layer that forms the flow path partition wall 120a) preferably has a thickness range of 200 μm or more to 2000 μm or less. When the thickness of the support substrate 203 is less than 200 μm, the substrate is likely to be broken, and handling may be likely to be adversely affected. When the thickness of the support substrate 203 exceeds 2000 μm, processing accuracy may be likely to be adversely affected.

Next, as illustrated in FIG. 8, a part of the active layer 201 is removed by anisotropic etching from the SOI substrate 200 illustrated in FIG. 7, and then the SiO₂ is filled to form an etching prevention film 204. This process can be performed by, for example, a deep trench isolation process.

Next, as illustrated in FIG. 9, the vibration film 103 and the nozzle plate 110 (the piezoelectric element 5 and the nozzle forming portion (film) 111) are formed on the active layer 201. As these forming processes, known processes can be appropriately adopted. Subsequently, as illustrated in FIG. 10, the vibration film 103 and the nozzle plate 110 are partially removed by etching to form the nozzle 2.

Next, as illustrated in FIG. 11, the support substrate 203 is partially removed by anisotropic etching. Subsequently, as illustrated in FIG. 12, SiO₂ is formed on the remaining support substrate 203 to form an etching preventing film 205. As a result, the removed portions of the support substrate 203 serve as the liquid flow paths 3a and 3b, and the remaining portions of the support substrate 203 serve as the flow path partition walls 120a.

Next, as illustrated in FIG. 13, the BOX layer 202 serving as the etching prevention film is partially removed to expose portions of the active layer 201. Then, as illustrated in FIG. 14, portions of the active layer 201 surrounded by the vibration film 103, the etching prevention film 204, and the BOX layer 202 are removed from the exposed portions of the active layer 201 by isotropic etching. The spaces from which the active layer 201 are removed will serve as the individual liquid chambers 4. The active layer 201 is Si, whereas the etching prevention film 204 and the BOX layer 202 are SiO₂, and thus, the etching prevention film 204 and the BOX layer 202 serve as etching stop layers. Although not illustrated, the drive circuit 101 and the wiring portion 102 are formed before the nozzle plate 110 (the piezoelectric element 5 and the nozzle forming portion (film) 111) is formed. As these forming processes, known processes can be appropriately adopted.

Manufacturing the individual liquid chambers 4 and liquid flow paths 3a and 3b in this manner provides the following advantages.

First, there is an advantage that the dimensional accuracy of the width D of the individual liquid chamber 4 can be increased. That is, since the etching prevention film 204 functions as an etching stop layer, for example, the variation in the width D of the individual liquid chamber 4 in the wafer during etching is small, and the processing accuracy is high. In the nozzle plate vibration type liquid ejection head 1, the vibration characteristics of the nozzle plate 110 (the vibration film 103) greatly affect the width D of the individual liquid chamber 4, and therefore, it is important that the processing accuracy of the width D be high. Further, the high processing accuracy of the widths D of the individual liquid chambers 4 is advantageous in that the positional accuracy of the nozzles 2 with respect to the individual liquid chambers 4 (the sidewalls 100a of the individual liquid chambers 4) is also high.

In addition, there is an advantage that the positional accuracy of the flow path partition wall 120a with respect to the openings 4a of the individual liquid chamber 4 (the sidewall 100a of the individual liquid chamber 4) can be easily increased. The configuration of the liquid ejection head 1 according to the present embodiment may also be obtained by separately etching the individual liquid chamber substrate 100 forming the sidewall 100a of the individual liquid chamber 4 and the flow path substrate 120 forming the flow path partition wall 120a of the liquid flow paths 3a and 3b, and bonding the formed sidewall 100a of the individual liquid chamber 4 and flow path partition wall 120a of the liquid flow paths 3a and 3b together. However, in this case, when the substrates 100 and 120 are bonded to each other, high alignment accuracy of the flow path partition wall 120a with respect to the openings 4a of the individual liquid chamber 4 (the sidewall 100a of the individual liquid chamber 4) is required, which takes a substantial amount of work and effort. In contrast, in the method of the present embodiment described above, the sidewall 100a of the individual liquid chamber 4 and the flow path partition wall 120a of the liquid flow paths 3a and 3b are formed by repeating etching on one substrate (SOI substrate 200). Therefore, the positional accuracy of the flow path partition wall 120a with respect to the openings 4a of the individual liquid chamber 4 (the sidewall 100a of the individual liquid chamber 4) can be easily increased.

First Modification

Next, a modification of the liquid ejection head 1 according to the present embodiment (hereinafter, this modification will be referred to as "first modification") will be described. In the liquid ejection head 1 according to the above-described embodiment, the liquid flow paths 3a and 3b communicating with the individual liquid chamber 4 are both supply flow paths configured to supply a liquid to the individual liquid chamber 4. However, in the liquid ejection head 1 according to the first modification, the liquid flow paths 3a and 3b communicating with the individual liquid chamber 4 are the supply flow path and a discharge flow path respectively, the discharge flow path being configured to discharge the liquid from the individual liquid chamber.

FIG. 15 is a cross-sectional view schematically illustrating a liquid ejection head according to the first modification. FIG. 16 is a plan view schematically illustrating an internal structure of the liquid ejection head, which is a sectional view taken along line A-A′ in FIG. 15. In the following description, the description overlapping with the above-described embodiment will be appropriately omitted.

In the first modification, as in the above-described embodiment, as illustrated in FIGS. 15 and 16, the opening 4a of each individual liquid chamber 4 communicates with a plurality of (two in the first modification) liquid flow paths 3a and 3b separated from each other by the flow path partition wall 120a. In other words, the opening 4a of each individual liquid chamber 4 is divided into a plurality of opening portions by the flow path partition wall 120a. However, in the first modification, one liquid flow path 3a connected to the individual liquid chamber 4 serves as a supply flow path configured to supply the liquid to the individual liquid chamber 4, and the other liquid flow path 3b connected to the individual liquid chamber 4 serves as a discharge flow path configured to discharge the liquid from the individual liquid chamber 4.

The nozzles 2 in the liquid ejection head 1 according to the first modification are arranged in two dimensional directions. Specifically, as illustrated in FIG. 16, a plurality of nozzle rows, each of which is configured by linearly arranging the nozzles 2 along the horizontal direction in the drawing, are arranged in the vertical direction in the drawing. In FIG. 16, three nozzle rows each with five linearly arranged nozzles 2 are arranged, as an example, for simplicity of description. As illustrated in FIG. 16, the nozzles in each nozzle row are arranged so that the positions of the nozzles in the nozzle row direction (the horizontal direction in the drawing) are shifted from each other. As a result, the adjacent direction (first direction) of the nozzles that are adjacent to each other between the nozzle rows is not orthogonal to the nozzle row direction (second direction), but is inclined.

In the flow path substrate 120 of the first modification, as illustrated in FIG. 16, the plurality of liquid flow paths 3a and 3b connected to each of the individual liquid chambers 4 of the nozzles adjacent to each other in the first direction (nozzles that are adjacent to each other between the nozzle rows) are separated by a corresponding one of the common flow path partition walls 120a. In this configuration, the common flow path partition walls 120a are arranged side by side in the second direction (the horizontal direction or the nozzle row direction in FIG. 16). In the first modification, end portions of the common flow path partition walls 120a extending in the first direction are connected by partition walls 120d that separate the supply flow paths 3a from the discharge flow paths 3b. With such a configuration, among the spaces separated by the flow path partition walls 120a and the partition walls 120d, a space communicating with the supply port 120b serves as a supply flow path 3a, and a space communicating with the discharge port 120c serves as the discharge flow path 3b, and the spaces are thus in a state of being separated from each other. Note that the common flow path partition wall 120a is an example of a common partition wall, and the partition wall 120d is an example of an end partition wall.

In the first modification, the liquid supplied from the supply port 120b flows along the upper surface of the individual liquid chamber substrate 100 in the supply flow paths 3a as indicated by arrows C1 in the drawing, and the liquid is supplied to each individual liquid chamber 4 from one (one opening portion connected to the supply flow path 3a) of two opening portions into which the opening 4a of each individual liquid chamber 4 is divided. Further, the liquid in each individual liquid chamber 4 that is not ejected from the nozzle 2 is discharged from the other side (side connected to the discharge flow path 3b) of the two opening portions into which the opening 4a of each individual liquid chamber 4 is divided. The liquid discharged from each individual liquid chamber 4 flows along the upper surface of the individual liquid chamber substrate 100 in the discharge flow path 3b and is discharged from the discharge port 120c.

According to the first modification, a flow of liquid flowing into the opening 4a of the individual liquid chamber 4 from the supply flow path 3a and a flow of liquid flowing from the opening 4a of the individual liquid chamber 4 out to the discharge flow path 3b can be created, and thus it is possible to replace the liquid in the individual liquid chamber 4. Therefore, the liquid in the individual liquid chamber 4 can be moved more actively than in the configuration of the above-described embodiment in which all the plurality of liquid flow paths connected to the openings 4a of the individual liquid chamber 4 are the supply flow paths 3a. As a result, the air bubbles in each individual liquid chamber 4 are easily moved and discharged from the individual liquid chamber 4, making it possible to further prevent the occurrence of the discharge failure.

Second Modification

Next, another modification of the liquid ejection head 1 according to the present embodiment (hereinafter, this modification is referred to as "second modification") will be described. In the liquid ejection head 1 according to the embodiment and the first modification described above, the liquid flows along the upper surface of the individual liquid chamber substrate 100 in the plurality of liquid flow paths 3a and 3b connected to each individual liquid chamber 4. When the number of nozzles of the liquid ejection head 1 is large and the number of individual liquid chambers 4 connected to one liquid flow path 3a or 3b is large, so that the route becomes long, the loss of liquid flowing through the liquid flow path 3a or 3b cannot be ignored, and there is a possibility that the supply of liquid will be insufficient. This is particularly significant when the viscosity of the liquid is high and when the ejection is performed at a high frequency.

FIG. 17 is a cross-sectional view schematically illustrating a liquid ejection head according to a second modification. The liquid ejection head 1 according to the second modification is an example in which both the liquid flow paths 3a and 3b communicating with the individual liquid chamber 4 are supply flow paths configured to supply liquid to the individual liquid chamber 4, as in the above-described embodiment. However, flow path inlets 120e of the liquid flow paths 3a and 3b are located on a side facing flow path outlets 120f of the supply flow paths 3a and 3b connected to the opening 4a of the individual liquid chamber 4 (i.e., two opening portions divided from the opening 4a of the individual liquid chamber 4). In the liquid ejection head 1 according to the second modification, a common liquid chamber 120g configured to store the liquid to be supplied to the supply flow paths 3a and 3b is provided so as to face the flow path inlets 120e of the supply flow paths 3a and 3b.

According to the second modification, the lengths of the paths through which the liquid flows in the liquid flow paths 3a and 3b are determined by the thicknesses of the flow path partition walls without depending on the number of nozzles of the liquid ejection head 1. Accordingly, even when the number of nozzles is large, the pressure loss is small and smooth liquid flow in and out is implemented. As a result, the movement of the liquid in the individual liquid chamber 4 becomes more active, and the air bubbles in the individual liquid chamber 4 are moved and easily discharged from the individual liquid chamber 4, which makes it possible to further prevent the occurrence of the discharge failure.

Third Modification

Next, still another modification (hereinafter, referred to as "third modification") of the liquid ejection head 1 according to the present embodiment will be described. In the liquid ejection head 1 according to the above-described embodiment and the first and second modifications, the number of the liquid flow paths 3a and 3b connected to each individual liquid chamber 4 is two. In the liquid ejection head 1 according to the third modification, the number of the liquid flow paths 3a and 3b connected to each individual liquid chamber 4 is four. The basic configuration of the liquid ejection head 1 according to the third modification is the same as that of the above-described embodiment, and is an example in which both of the liquid flow paths 3a and 3b communicating with the individual liquid chambers 4 are supply flow paths configured to supply liquid to the individual liquid chambers 4.

FIG. 18 is an enlarged plan view illustrating an internal structure of the liquid ejection head according to a third modification, which is a sectional view corresponding to a section taken along line B-B′ in FIG. 1. In the liquid ejection head 1 according to the third modification, as illustrated in FIG. 18, the opening 4a of each individual liquid chamber 4 communicates with a plurality of (four in the third modification) liquid flow paths 3a, 3b, 3c, and 3d separated from each other by the flow path partition walls 120a1 and 120a2. In other words, the opening 4a of each individual liquid chamber 4 is divided into a plurality of (four) opening portions by the flow path partition walls 120a1 and 120a2.

Specifically, in the configuration in which the nozzles 2 are two dimensionally arranged as in the above-described embodiment, the flow path substrate 120 of the third modification is described. As illustrated in FIG. 18, the liquid flow paths connected to the individual liquid chambers 4 of the nozzles adjacent to each other in the adjacent direction (first direction) between the nozzle rows (nozzles adjacent to each other between the nozzle rows) are separated by the first common flow path partition wall 120a1. In addition, in the flow path substrate 120 of the third modification, as illustrated in FIG. 18, the liquid flow paths connected to the individual liquid chambers 4 of the nozzles adjacent to each other in the nozzle row direction (second direction) (nozzles adjacent to each other within the nozzle row) are separated by the second common flow path partition wall 120a2. In the liquid ejection head 1 according to the third modification, an intersection between the first flow path partition wall 120a1 and the second flow path partition wall 120a2 is configured to face the opening 4a of each individual liquid chamber 4.

Thus, in the third modification, as illustrated in FIG. 18, the opening 4a of each individual liquid chamber 4 communicates with four liquid flow paths 3a, 3b, 3c, and 3d separated from each other by the flow path partition walls 120a1 and 120a2. In other words, the opening 4a of each individual liquid chamber 4 is divided into four opening portions by the flow path partition walls 120a1 and 120a2.

According to the third modification, the number of liquid flow paths 3a, 3b, 3c, and 3d connected to the opening 4a of each individual liquid chamber 4 is large, which makes it possible to increase the number of places where the liquid flows in and out of the individual liquid chamber 4. Accordingly, the movement of the liquid in the individual liquid chamber 4 is complicated, and the air bubbles in the individual liquid chamber 4 are moved and easily discharged from the individual liquid chamber 4, which makes it possible to further prevent the occurrence of the discharge failure.

In the third modification, the number of the liquid flow paths 3a, 3b, 3c, and 3d connected to the opening 4a of each individual liquid chamber 4 is four. However, the number of the liquid flow paths can be appropriately set, and may be three, or five or more.

Fourth Modification

Next, still another modification (hereinafter, referred to as "fourth modification") of the liquid ejection head 1 according to the embodiment will be described. In the liquid ejection head 1 according to the embodiment and the first and second modifications, opening areas or opening shapes of the liquid flow paths 3a and 3b connected to the individual liquid chambers 4 are the same. In the liquid ejection head 1 according to the third modification, the opening areas or the opening shapes of the liquid flow paths 3a and 3b connected to the individual liquid chambers 4 are different.

FIG. 19 is a cross-sectional view schematically illustrating a liquid ejection head according to the fourth modification. The liquid ejection head 1 according to the fourth modification is an example in which both of the liquid flow paths 3a and 3b communicating with the individual liquid chambers 4 are supply flow paths configured to supply liquid to the individual liquid chambers 4, as in the above-described embodiment. However, the opening areas or opening shapes of the flow path outlets of the liquid flow paths 3a and 3b connected to the opening 4a of the individual liquid chamber 4 (i.e., two opening portions obtained by dividing the opening 4a of the individual liquid chamber 4) are configured to be different from each other as illustrated in FIG. 19.

Specifically, as illustrated in FIG. 19, in the flow path substrate 120 of the fourth modification, the flow path partition wall 120a extending across the opening 4a of each individual liquid chamber 4 of the individual liquid chamber substrate 100 is disposed across a position deviated from the opening center of the opening 4a. Accordingly, the opening area of the flow path outlet of the liquid flow path 3a connected to the opening 4a of the individual liquid chamber 4 is larger than the opening area of the flow path outlet of the liquid flow path 3b connected to the opening 4a of the individual liquid chamber 4. As a result, an entrance C3 and an exit C4 through which the liquid flows in and out of the individual liquid chamber 4 can be deliberately made asymmetric, which enables the liquid to move more actively in the individual liquid chamber 4. This enables the bubbles in the individual liquid chamber 4 to be moved and easily discharged from the individual liquid chamber 4. Thus, it is possible to further prevent the occurrence of the discharge failure.

The configuration of the fourth modification is also useful in the configuration in which the common liquid chamber 120g is provided as in the second modification described above, for example, as illustrated in FIG. 20.

Next, an example of a liquid ejection apparatus according to the present disclosure will be described with reference to FIGS. 21 and 22. FIG. 21 is a schematic explanatory view illustrating a printing apparatus, which is an ink jet recording apparatus that is an image forming apparatus as a liquid ejection apparatus according to the present embodiment. FIG. 22 is a plan view illustrating an example of a head unit of the printing apparatus according to the embodiment.

The printing apparatus 500 which is a liquid ejection apparatus includes a carrying-in unit 501 which carries in a continuous body 510, and a guiding-transporting unit 503 which guides and transports the continuous body 510 carried in from the carrying-in unit 501 to a printing unit 505. The printing apparatus 500 also includes the printing unit 505 that performs printing for forming an image by discharging liquid onto the continuous body 510, a drying unit 507 that dries the continuous body 510, a carrying-out unit 509 that carries out the continuous body 510, and the like.

The continuous body 510 is fed from a root winding roller 511 of the carrying-in unit 501, guided and transported by the respective rollers of the carrying-in unit 501, the guiding-transporting unit 503, the drying unit 507, and the carrying-out unit 509, and wound by a winding roller 591 of the carrying-out unit 509. In the printing unit 505, the continuous body 510 is transported on a transporting-guiding member 559 so as to face the head unit 550, and an image is printed on the continuous body 510 by the liquid ejected from the head unit 550.

In the printing apparatus 500 of the embodiment, the head unit 550 includes two head modules 100A and 100B according to the embodiment described above in a common base member 552.

When a head array direction is defined as a direction in which the liquid ejection heads 1 are aligned in a direction orthogonal to a transport direction of the head modules 100A and 100B, liquids of the same color are ejected by head rows 1A1 and 1A2 of the head module 100A. Similarly, head rows 1B1 and 1B2 of the head module 100A are configured as a set, the head rows 1C1 and 1C2 of the head module 100B are configured as a set, and the head rows 1D1 and 1D2 of the head module 100B are configured as a set, and each of the head rows ejects liquid of a required color.

Next, another example of a printing apparatus as a liquid ejection apparatus according to the embodiment of the present invention will be described with reference to FIGS. 23 and 24. FIG. 23 is a plan view illustrating a main part of the printing apparatus of the present example. FIG. 24 is a side view illustrating the main part of the printing apparatus of the present example.

The printing apparatus 500 according to the present example is a serial type apparatus, in which a carriage 403 moves back and forth in a 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, and the like. The guide member 401 is bridged between left and right side plates 491A and 491B, and movably holds the carriage 403. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 stretched over between a driving pulley 406 and a driven pulley 407.

The carriage 403 is provided with a liquid ejection unit 440 in which the liquid ejection head 1 according to the present disclosure and a head tank 441 are integrated. The liquid ejection head 1 ejects, for example, liquids of respective colors of yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 1 is mounted with a nozzle array, which includes a plurality of nozzles aligned with an ejection direction facing downward and in a sub-scanning direction orthogonal to the main scanning direction. The liquid ejection head 1 is connected to a liquid circulation device, and liquid of a required color is supplied and circulated.

The printing apparatus 500 includes a transporting mechanism 495 for transporting a sheet 410. The transporting mechanism 495 includes a transporting belt 412 as a transporting unit and a sub-scanning motor 416 for driving the transporting belt 412. The transporting belt 412 adsorbs the sheet 410, and transports the adsorbed sheet 410 at a position facing the liquid ejection head 1. The transporting belt 412 is an endless belt, and is stretched over between a transporting roller 413 and a tension roller 414. The adsorption can be performed by electrostatic adsorption, air suction, or the like. The transporting roller 413 is driven and rotated by a sub-scanning motor 416 via a timing belt 417 and a timing pulley 418, so that the transporting belt 412 is moved circumferentially in the sub-scanning direction.

Further, a maintenance and recovery mechanism 420 for maintaining and recovering the liquid ejection heads 1 is disposed on one side of the carriage 403 in the main scanning direction and on a side of the transporting belt 412. The maintenance and recovery mechanism 420 includes, for example, a cap member 421 for capping the nozzle surface of the liquid ejection head 1, and a wiper member 422 for wiping the nozzle surface. The main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the transporting mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

In the printing apparatus 500 configured as described above, the sheet 410 is fed onto the transporting belt 412 and adsorbed thereon, and the sheet 410 is transported in the sub-scanning direction by the circulation movement of the transporting belt 412. Therefore, the liquid ejection head 1 is driven in accordance with an image signal while the carriage 403 is moved in the main scanning direction. Thus, the liquid is ejected onto the sheet 410 that has been stopped to form an image.

Next, another example of the liquid ejection unit according to the present disclosure will be described with reference to FIG. 25. FIG. 25 is a plan view illustrating a main part of the liquid ejection unit of the present example.

The liquid ejection unit 440 includes a housing portion including the side plates 491A and 491B, and the back plate 491C, the main scanning movement mechanism 493, the carriage 403, and the liquid ejection head 1, from among the members constituting the liquid ejection apparatus.

The maintenance and recovery mechanism 420 may be further attached to, for example, the side plate 491B of the liquid ejection unit 440.

Next, still another example of the liquid ejection unit according to the embodiment of the present invention will be described with reference to FIG. 26. FIG. 26 is a front view of the liquid ejection unit of the present example.

The liquid ejection unit 440 includes the liquid ejection head 1 to which a flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

The flow path component 444 is disposed inside a cover 442. The head tank 441 may be included instead of the flow path component 444. A connector 443 for electrical connection to the liquid ejection head 1 is provided on the upper portion of the flow path component 444.

In the present disclosure, the liquid to be ejected is not particularly specified as long as it has a viscosity or surface tension that allows ejection from the head, but it is preferable that the viscosity is 30 mPa・s or less, at room temperature and atmospheric pressure or by 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 coloring agent such as a dye or a pigment, a function-providing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acid, protein, or calcium, or an edible material such as a natural pigment. These materials can be used in applications such as an inkjet ink, a surface treatment liquid, a liquid for forming a constituent element of an electronic element or a light-emitting element or an electronic circuit resist pattern, and a three dimensional shaping material liquid.

The "liquid ejection unit" is a unit which has the liquid ejection head integrated with functional components and mechanisms, and which includes an assembly of components related to the discharge of liquid. For example, the "liquid ejection unit" includes a combination of the liquid ejection head and at least one of the head tank, the carriage, a supply mechanism, the maintenance and recovery mechanism, the main scanning movement mechanism, or the liquid circulation device.

Here, the term "integrated" includes, for example, a case where the liquid ejection head and the functional component or mechanism are fixed to each other by fastening, adhesion, engagement, or the like, and a case where one of them is held movably with respect to the other. The liquid ejection head, the functional component, or mechanism may be configured to be detachable from each other.

For example, as a liquid ejection unit, a liquid ejection unit in which a liquid ejection head and a head tank are integrated may be given. In addition, a liquid ejection head and a head tank which are connected to each other by a tube or the like and are integrated with each other may be given. In such configurations, a unit including a filter may be added between the head tank and the liquid ejection head of the liquid ejection unit.

Further, as the liquid ejection unit, a unit in which the liquid ejection head and the carriage are integrated may be given.

In addition, as the liquid ejection unit, a unit in which the liquid ejection head is movably held by a guide member constituting a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated may be given. In addition, a liquid ejection apparatus in which the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated may be given.

In addition, as the liquid ejection unit, a liquid ejection unit in which a cap member that is a part of the maintenance and recovery mechanism is fixed to the carriage to which the liquid ejection head is attached, and the liquid ejection head, the carriage, and the maintenance and recovery mechanism are integrated may be given.

In addition, as the liquid ejection unit, a unit in which a tube is connected to the liquid ejection head to which the head tank or the flow path component is attached, and the liquid ejection head and the supply mechanism are integrated may be given. The liquid in a liquid storage source is supplied to the liquid ejection head via the tube.

The main scanning movement mechanism also includes a single guide member. The supply mechanism also includes a single tube, and a single loading unit.

Here, the "liquid ejection unit" is described in combination with the liquid ejection head, but the "liquid ejection unit" includes a head module including the liquid ejection head described above or a head unit integrated with the functional components and mechanisms described above.

The "liquid ejection apparatus" includes an apparatus which includes a liquid ejection head, a liquid ejection unit, a head module, a head unit, and the like and which is configured to eject liquid by driving the liquid ejection head. The liquid ejection apparatus includes not only an apparatus capable of ejecting liquid to an object to which liquid can adhere but also a liquid ejection apparatus into air or liquid.

The "liquid ejection apparatus" may include systems for feeding, transporting, and discharging a sheet material to which liquid can adhere, a pre-processing apparatus, a post-processing apparatus, and the like.

For example, as the "liquid ejection apparatus", there are an image forming apparatus which is an apparatus that forms an image on a sheet by ejecting ink, and a three dimensional modeling apparatus (three dimensional shaping apparatus) which ejects shaping liquid onto a powder layer formed by layering powder in order to shape a three dimensional modeled object (three dimensional shaped object).

The "liquid ejection apparatus" is not limited to an apparatus in which a significant image such as a character or a figure is visualized by the ejected liquid. For example, the printing apparatus may form a pattern or the like that has no meaning, or may form a three dimensional image.

The "object to which the liquid can adhere" means an object to which the liquid can adhere at least temporarily, and means an object to which the liquid adheres and is fixed, an object to which the liquid adheres and permeates, or the like. Specific examples of the medium include a recording medium such as paper, recording paper, a recording sheet, a film, or cloth, an electronic component such as an electronic substrate or a piezoelectric element, and a medium such as a powder layer, an organ model, or an inspection cell. Unless otherwise specified, the medium includes all media to which a liquid adheres.

The material of "an object to which liquid can adhere" may be any material to which liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, or ceramics.

The "liquid ejection apparatus" may be an apparatus in which a liquid ejection head and an object to which liquid can be adhered are relatively moved, but is not limited thereto. Specific examples of the liquid ejection apparatus include a serial type apparatus in which a liquid ejection head is moved and a line type apparatus in which a liquid ejection head is not moved.

In addition, as the "liquid ejection apparatus", a treatment liquid applying apparatus which ejects a treatment liquid onto a sheet in order to apply the treatment liquid onto a surface of the sheet for the purpose of reforming the surface of the sheet may be given. Also, a spray granulation apparatus that sprays a composition liquid in which a raw material is dispersed in a solution through the nozzles to granulate fine particles of the raw material may be given.

In the present application, the terms "image formation", "recording", "typing", "graphic forming", "printing", "shaping", and the like are used synonymously.

The above description is an example, and each of the following aspects has a unique effect.

First Aspect

A first aspect is a liquid ejection head 1 that includes a nozzle 2 configured to eject a liquid (e.g., ink), an individual liquid chamber 4 communicating with the nozzle, and an actuator (e.g., piezoelectric element 5) provided on a nozzle forming wall (e.g., a nozzle plate 110) of the individual liquid chamber, such that the liquid in the individual liquid chamber is ejected from the nozzle by driving the actuator. A plurality of liquid flow paths 3a, 3b, 3c, and 3d separated from each other by flow path partition walls 120a are connected to an opening 4a of the individual liquid chamber, where the opening 4a is located on a side facing the nozzle forming wall. In the liquid ejection head of a so-called nozzle plate vibration type in which the actuator is provided on a nozzle forming wall of the individual liquid chamber, air bubbles may remain in the individual liquid chamber, particularly, at corners of the individual liquid chamber (a connection portion between the nozzle forming wall and a sidewall of the individual liquid chamber). When the air bubbles remain in the individual liquid chamber, the driving force of the actuator may not propagate properly to the liquid in the individual liquid chamber, which may cause liquid ejection failure. In the nozzle plate vibration type liquid ejection head, a supply flow path (liquid flow path) configured to supply liquid to the individual liquid chamber communicates with the opening of the individual liquid chamber located on the side facing the nozzle forming wall. In the related art configuration, the entire opening of the individual liquid chamber communicates with one supply flow path, and thus the liquid substantially uniformly enters (flows in) and exits (flows out) from the entire opening of the individual liquid chamber. Therefore, the movement of the liquid in the individual liquid chamber is small, and for example, when the liquid is filled into the individual liquid chamber by supplying the liquid from the opening of the individual liquid chamber into the individual liquid chamber at the time of filling the liquid into the liquid ejection head, the air bubbles are likely to remain at the corners of the individual liquid chamber. In addition, since the liquid in the individual liquid chamber moves little even during the operation of the liquid ejection head, the air bubbles at the corners of the individual liquid chamber or the like remain at the corners, and as a result, ejection failure is caused. According to this aspect, the plurality of liquid flow paths separated from each other by the flow path partition wall are connected to the opening of the individual liquid chamber. According to this configuration, since the plurality of liquid flow paths through which the liquid flows in and out between the individual liquid chamber and the opening are provided, the inflow and outflow of the liquid with respect to the opening of the individual liquid chamber is likely to be asymmetric between the plurality of liquid flow paths. Therefore, the liquid in the individual liquid chamber is easily moved as compared with the related art configuration in which the entire opening of the individual liquid chamber communicates with one supply flow path and the liquid substantially uniformly enters (flows in) and exits (flows out) from the entire opening of the individual liquid chamber. As a result, the air bubbles at the corners of the individual liquid chambers are easily moved from the corners of the individual liquid chamber, and the air bubbles are discharged from the individual liquid chamber during the liquid filling operation or during the operation of the liquid ejection head, thereby preventing the occurrence of ejection failure.

Second Aspect

A second aspect is the liquid ejection head 1 according to the first aspect, wherein all of the plurality of liquid flow paths are supply flow paths configured to supply a liquid to the individual liquid chamber. In the liquid ejection head having a simple configuration without a discharge flow path configured to discharge a liquid from a liquid flow path, the liquid in the individual liquid chamber is particularly unlikely to move, and air bubbles are likely to remain in the individual liquid chamber. According to this aspect, since the plurality of liquid flow paths configured to supply the liquid to the opening of the individual liquid chamber are provided, the inflow (flow) of the liquid to the opening of the individual liquid chamber is likely to be asymmetric between the plurality of liquid flow paths (supply flow paths), and the liquid in the individual liquid chamber is likely to move. Therefore, even in the liquid ejection head having such a simple configuration, it is possible to prevent the occurrence of ejection failure due to the retention of the air bubbles by making it easy to move the air bubbles in the individual liquid chamber.

Third Aspect

A third aspect is the liquid ejection head according to the second aspect, wherein the nozzle includes a plurality of nozzles, the individual liquid chamber is provided for each of the nozzles, the actuator is provided for each of the individual liquid chambers, and the plurality of liquid flow paths are provided for each of the individual liquid chambers, and wherein flow path inlets 120e of the supply flow paths are located on a side facing flow path outlets 120f of the supply flow paths connected to an opening of the individual liquid chamber, and the flow path inlets 120e of the supply flow paths face a common liquid chamber 120g configured to store the liquid to be supplied to each of the supply flow paths of the plurality of liquid flow paths. According to this aspect, the flow path inlets of the liquid flow paths into which the liquid flows from the common liquid chamber and the flow path outlets of the liquid flow paths from which the liquid flow out to the individual liquid chambers are disposed at positions facing each other. Thus, the lengths of the paths through which the liquid flows in the liquid flow paths are determined by the thicknesses of the flow path partition walls without depending on the number of nozzles of the liquid ejection head 1, and are short, so that even when the number of nozzles of the liquid ejection head is large, the pressure loss is small, and smooth entrance and exit of the liquid are implemented. Therefore, the movement of the liquid in the individual liquid chambers become more active, and the air bubbles in the individual liquid chambers are moved and easily discharged from the individual liquid chambers, and thus it is possible to further prevent the occurrence of the discharge failure.

Fourth Aspect

A fourth aspect is the liquid ejection head according to the first aspect, wherein the plurality of liquid flow paths include a supply flow path configured to supply the liquid to the individual liquid chamber and a discharge flow path configured to discharge the liquid from the individual liquid chamber. According to this aspect, it is possible to create a flow of liquid flowing in from the supply flow path and a flow of liquid flowing out to the discharge flow path with respect to the opening of the individual liquid chamber so as to replace the liquid in the individual liquid chamber. Therefore, the liquid in the individual liquid chamber can be moved more actively than in a configuration in which all the plurality of liquid flow paths connected to the opening of the individual liquid chamber are the supply flow paths. As a result, the air bubbles in the individual liquid chamber are easily moved and discharged from the individual liquid chamber, and thus it is possible to further prevent the occurrence of the discharge failure.

Fifth Aspect

A fifth aspect is the liquid ejection head according to the fourth aspect, wherein the nozzles are arranged in two dimensional directions, the individual liquid chamber is provided for each of the nozzles, the actuator is provided for each of the individual liquid chambers, and the plurality of liquid flow paths are provided for each of the individual liquid chambers, wherein the plurality of liquid flow paths connected to each of the individual liquid chambers of the nozzles that are adjacent to each other in a first direction (e.g., a direction in which the nozzles are adjacent to each other between nozzle rows) are separated by a corresponding one of common flow path partition walls 120a, and end portions of the common flow path partition walls 120a extending in the first direction are connected by partition walls 120d, the common flow path partition walls 120a being arranged side by side in a second direction (e.g., a nozzle row direction) intersecting the first direction, and the partition walls 120d separating the supply flow paths from the discharge flow paths. According to this aspect, with a simple configuration, one of the spaces separated by the flow path partition wall 120a and the partition wall 120d can be used as the supply flow path, and the other space can be used as the discharge flow path.

Sixth Aspect

A sixth aspect is the liquid ejection head according to any one of the first to fifth aspects, wherein among walls partitioning the individual liquid chamber, a liquid chamber sidewall layer (e.g., the individual liquid chamber substrate 100) forms a sidewall 100a located on a side orthogonal to a liquid ejection direction from the nozzle, and a flow path partition wall layer (e.g., the flow path substrate 120) forms the flow path partition wall, wherein the liquid chamber sidewall layer and the flow path partition wall layer are made of Si (silicon), and wherein the liquid chamber sidewall layer and the flow path partition wall layer are connected by a SiO₂ layer. According to this aspect, it is possible to form the sidewall of the individual liquid chamber and the flow path partition wall of the liquid flow path by repeating etching on one substrate (SOI substrate) using a silicon on insulator (SOI) substrate. Therefore, compared to a case where the liquid chamber sidewall layer and the flow path partition wall layer are formed by being bonded to each other, it is possible to easily increase the positional accuracy of the flow path partition wall with respect to the opening of the individual liquid chamber (the sidewall of the individual liquid chamber).

Seventh Aspect

A seventh aspect is the liquid ejection head according to any one of the first to sixth aspects, wherein opening areas or opening shapes of the plurality of liquid flow paths connected to the opening of the individual liquid chamber are different from each other. According to this aspect, it is possible to actively make the entrance and exit of the liquid with respect to the individual liquid chamber asymmetric, and it is possible to cause more vigorous movement of the liquid in the individual liquid chamber. Therefore, the bubbles in the individual liquid chamber are moved and easily discharged from the individual liquid chamber, and thus it is possible to further prevent the occurrence of the discharge failure.

Eighth Aspect

An eighth aspect is the liquid ejection head according to any one of the first to seventh aspects, wherein among walls partitioning the individual liquid chamber, a liquid chamber sidewall layer forms a sidewall located on a side orthogonal to a liquid ejection direction from the nozzle, and a thickness of the liquid chamber sidewall layer is in a range of 1 μm or more to 200 μm or less. According to this configuration, the ejection operation at a high frequency can be facilitated within a range in which processing accuracy may be unlikely to be affected.

Ninth Aspect

A ninth aspect is the liquid ejection head according to any one of the first to eighth aspects, wherein a flow path partition wall layer forms the flow path partition wall, and a thickness of the flow path partition wall layer is in a range of 200 μm or more to 2000 μm or less. According to this aspect, it is possible to make handling less likely to be affected by problems during the manufacturing process, within a range in which processing accuracy is not easily affected.

Tenth Aspect

A tenth aspect is a liquid ejection apparatus that includes the liquid ejection head according to any one of the first to ninth aspects. According to this aspect, it is possible to implement a liquid ejection apparatus in which the occurrence of ejection failure due to the retention of bubbles in the individual liquid chambers is prevented.

Eleventh Aspect

An eleventh aspect is a method of manufacturing a liquid ejection head 1, wherein the liquid ejection head 1 includes a nozzle 2 configured to eject a liquid (e.g., ink), an individual liquid chamber 4 communicating with the nozzle, and an actuator (e.g., piezoelectric element 5) provided on a nozzle forming wall (e.g., nozzle plate 110) of the individual liquid chamber, wherein the liquid in the individual liquid chamber is ejected from the nozzle by driving the actuator.
The method includes forming a flow path partition wall 120a for separating a plurality of liquid flow paths from each other, the plurality of liquid flow paths being connected to an opening 4a of the individual liquid chamber located on a side facing the nozzle forming wall. According to this aspect, it is possible to manufacture a liquid ejection apparatus in which the occurrence of ejection failure due to the retention of air bubbles in the individual liquid chamber is prevented.

The present application is based on and claims priority to Japanese patent application No. 2023-033572 filed on March 6, 2023, with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.

1　　liquid ejection head
2　　nozzle
3a-3d　　liquid flow path
4　　individual liquid chamber
4a　　opening
5　　piezoelectric element
31　　supply liquid storage chamber
32　　supply communication path
33　　liquid supply port
35　　discharge liquid storage chamber
36　　liquid discharge port
51　　first electrode
52　　piezoelectric film
53　　second electrode
100　　individual liquid chamber substrate
100a　　sidewall
101　　drive circuit
102　　wiring portion
103　　vibrating film
110　　nozzle plate
111　　nozzle forming portion
112　　liquid repellent film
120　　flow path substrate
120a　　flow path partition wall
120a1　　first flow path partition wall
120a2　　second flow path partition wall
120b　　supply port
120c　　discharge port
120d　　partition wall
120e　　flow path inlet
120f　　flow path outlet
120g　　common liquid chamber
140　　frame portion
200　　SOI substrate
201　　active layer
202　　BOX layer
203　　support substrate
204,205　　etching prevention film
500　　printing apparatus

Claims

　　　　A liquid ejection head comprising:
　　　　a nozzle configured to eject a liquid;
　　　　an individual liquid chamber communicating with the nozzle; and
　　　　an actuator provided in a nozzle forming wall of the individual liquid chamber, the liquid in the individual liquid chamber being ejected through the nozzle by driving the actuator,
　　　　wherein a partition wall for dividing a flow path is disposed at an opening of the individual liquid chamber, the opening being located on a liquid supply side of the individual liquid chamber and facing the nozzle forming wall.
　　　　The liquid ejection head according to claim 1, wherein the flow path includes a plurality of flow paths, and the plurality of flow paths are supply flow paths configured to supply the liquid to the individual liquid chamber.
　　　　The liquid ejection head according to claim 2,
　　　　wherein the nozzle includes a plurality of nozzles,
　　　　the individual liquid chamber is provided for each of the nozzles,
　　　　the actuator is provided for each of the individual liquid chambers, and
　　　　the plurality of flow paths are provided for each of the individual liquid chambers,
　　　　wherein flow path inlets of the supply flow paths are located on a side facing flow path outlets of the supply flow paths, the supply flow paths being connected to the opening of the individual liquid chamber, and
　　　　wherein the flow path inlets of the supply flow paths face a common liquid chamber, the common liquid chamber being configured to store the liquid to be supplied to each of the supply flow paths of the plurality of flow paths.
　　　　The liquid ejection head according to claim 1,
　　　　wherein the flow path includes a plurality of flow paths, and
　　　　wherein the plurality of flow paths include a supply flow path and a discharge flow path, the supply flow path being configured to supply the liquid to the individual liquid chamber, and the discharge flow path being configured to discharge the liquid from the individual liquid chamber.
　　　　The liquid ejection head according to claim 4,
　　　　wherein the nozzle includes a plurality of nozzles, the plurality of nozzles being arranged in two dimensional directions,
　　　　the individual liquid chamber is provided for each of the nozzles,
　　　　the actuator is provided for each of the individual liquid chambers, and
　　　　the plurality of flow paths are provided for each of the individual liquid chambers,
　　　　wherein the plurality of flow paths connected to each of the individual liquid chambers of the nozzles are separated by a corresponding one of common partition walls, the nozzles being adjacent to each other in a first direction, and
　　　　wherein end portions of the common partition walls extending in the first direction are connected by end partition walls, the common partition walls being arranged side by side in a second direction intersecting the first direction, the end partition walls each separating the supply flow path from the discharge flow path.
　　　　The liquid ejection head according to any one of claims 1 to 5,
　　　　wherein among walls partitioning the individual liquid chamber, a liquid chamber sidewall layer forms a sidewall located on a side orthogonal to a liquid ejection direction from the nozzle and a flow path partition wall layer forms the partition wall,
　　　　wherein the liquid chamber sidewall layer and the flow path partition wall layer are made of Si, and
　　　　wherein the liquid chamber sidewall layer and the flow path partition wall layer are connected to each other by a SiO₂ layer.
　　　　The liquid ejection head according to any one of claims 1 to 5, wherein opening areas or opening shapes of the plurality of flow paths connected to the opening of the individual liquid chamber are different from each other.
　　　　The liquid ejection head according to any one of claims 1 to 5,
　　　　wherein among walls partitioning the individual liquid chamber, a liquid chamber sidewall layer forms a sidewall located on a side orthogonal to a liquid ejection direction from the nozzle, and
　　　　wherein a thickness of the liquid chamber sidewall layer is in a range of 1 μm or more to 200 μm or less.
　　　　The liquid ejection head according to any one of claims 1 to 5,
　　　　wherein a flow path partition wall layer forms the partition wall, and
　　　　wherein a thickness of the flow path partition wall layer is in a range of 200 μm or more to 2000 μm or less.
　　　　A liquid ejection apparatus comprising:
　　　　the liquid ejection head according to any one of claims 1 to 5.
　　　　A method of manufacturing a liquid ejection head, the liquid ejection head including a nozzle configured to eject a liquid, an individual liquid chamber configured to communicate with the nozzle, and an actuator provided in a nozzle forming wall of the individual liquid chamber, the liquid in the individual liquid chamber being ejected through the nozzle by driving the actuator, the method comprising:
　　　　forming a partition wall for dividing a liquid flow path at an opening of the individual liquid chamber, the opening being located on a liquid supply side of the individual liquid chamber and facing the nozzle forming wall.