JP7028178B2 - Inkjet heads, their manufacturing methods, and inkjet printers - Google Patents

Description

The present invention relates to an inkjet head, a method for manufacturing the same, and an inkjet printer.

Conventionally, as an inkjet head that ejects ink from a nozzle, for example, there are those disclosed in Patent Documents 1 and 2. In Patent Document 1, the nozzle provided on the nozzle plate is composed of a two-stage hole consisting of a small-diameter first nozzle portion and a large-diameter second nozzle portion, and the first nozzle portion and the second nozzle portion are placed on a substrate surface. On the other hand, by providing the ink droplets vertically and coaxially, the ink droplet ejection directions are aligned with the nozzle center axis direction to exhibit stable ink ejection characteristics. Further, in Patent Document 2, in a configuration in which ink in a pressure chamber is ejected from a nozzle via a communication passage, the above-mentioned communication passage is connected to a common recovery passage via a recovery passage, whereby excess ink is shared. It is circulated through the collection path.

Japanese Patent No. 5929276 (see paragraph [0022], FIG. 2, etc.) Japanese Patent No. 5475389 (see paragraph [0047], FIG. 4, etc.)

In recent years, inkjet heads can handle various ink types, can freely change the size of droplets (especially capable of ejecting large droplets of ink), and can eject ink at high speed. Performance is required. Dye inks and pigment inks are available as ink types. In particular, when pigment inks are used, the pigments tend to settle and stay in the vicinity of the nozzles, so that nozzle clogging and ejection performance are likely to deteriorate. Further, in order to cope with ink ejection of large droplets and high-speed ejection, it is necessary to improve the characteristic (so-called refillability) of smoothly replenishing the ink in the pressure chamber into the nozzle after the ink is ejected. ..

In this regard, when the nozzle provided on the nozzle plate is composed of two-step holes as in Patent Document 1, the large diameter when ink flows from the large-diameter second nozzle portion to the small-diameter first nozzle portion. The bottom surface of the second nozzle portion (the upper surface of the first nozzle portion having a small diameter) becomes the resistance of the ink flow (because the bottom surface is orthogonal to the ink flow direction). As a result, the refillability of the ink from the pressure chamber to the nozzle is lowered, and it becomes impossible to cope with the ink ejection of large droplets and the high-speed ejection of ink. Further, since there is a surface (bottom surface of the second nozzle portion having a large diameter) orthogonal to the flow direction, the pigment tends to stay on the bottom surface when the pigment ink is used. As a result, as described above, the nozzle is likely to be clogged or the ejection performance is deteriorated due to the pigment, and the ink ejection becomes unstable (for example, the ink ejection direction and the ejection speed change).

Further, in the configuration of Patent Document 2, the recovery path for circulating the ink is formed at the substrate position away from the nozzle plate on which the nozzle is formed. Therefore, the pigment that has settled in the vicinity of the nozzle cannot be efficiently recovered via the recovery path. As a result, similarly to the above, the accumulated pigment causes clogging of the nozzle and unstable ink ejection.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to improve the refillability of ink from a pressure chamber to a nozzle to cope with large droplets and high-speed ink ejection. At the same time, even when ink containing particles (for example, pigments) that easily settle is used, excess particles that have settled in the vicinity of the nozzle are efficiently recovered, clogging of the nozzle is suppressed, and ink ejection is performed stably. It is an object of the present invention to provide an inkjet head capable of being capable of the process, an inkjet printer provided with the inkjet head, and a method for manufacturing the inkjet head.

The above object of the present invention is achieved by the following configuration or manufacturing method.

That is, the inkjet head according to one aspect of the present invention has a pressure chamber for accommodating ink, an actuator that changes the volume of the pressure chamber, a communication portion that communicates with the pressure chamber, and communication with the communication portion. A nozzle plate having a nozzle for ejecting ink flowing from the pressure chamber through the communication portion to the outside due to a volume change of the pressure chamber by the actuator, and a circulation flow path portion for circulating undischarged ink. The communication portion has at least one tapered wall, and the tapered wall has the nozzle so that the opening area of the communication portion becomes smaller from the pressure chamber side to the nozzle side. It is inclined with respect to a surface perpendicular to the thickness direction of the plate, and the circulation flow path portion is provided in the nozzle plate so as to penetrate the at least one tapered wall and communicates with the communication portion. There is.

The inkjet printer according to another aspect of the present invention includes the above-mentioned inkjet head, and ejects ink from the inkjet head toward a recording medium.

The method for manufacturing an inkjet head according to still another aspect of the present invention is the above-mentioned manufacturing method for manufacturing an inkjet head, in which the communication portion is formed by wet etching.

The method for manufacturing an inkjet head according to still another aspect of the present invention is the above-mentioned manufacturing method for manufacturing an inkjet head, in which the circulation flow path portion is formed by wet etching.

In the configuration in which the ink flowing from the pressure chamber through the communication portion of the nozzle plate is discharged from the nozzle to the outside due to the volume change of the pressure chamber by the actuator, the communication portion has at least one tapered wall. Due to the inclination of the tapered wall, the flow path resistance becomes small and the ink flows smoothly from the communication portion toward the nozzle, so that the refillability of the ink from the pressure chamber to the nozzle can be improved. Therefore, it is possible to cope with large droplets and ink ejection at high speed (such ink ejection can be easily performed).

Further, the circulation flow path portion is provided in the nozzle plate so as to penetrate the tapered wall of the communication portion, and communicates with the communication portion. That is, the circulation flow path portion is provided on the same plate as the nozzle plate on which the nozzle is provided. Therefore, the circulation flow path portion can be positioned in the vicinity of the nozzle, and even when ink containing particles that easily settle is used, the excess particles that have settled in the vicinity of the nozzle can be efficiently routed through the communication section. Can be led to recovery. As a result, it is possible to suppress the occurrence of nozzle clogging due to the particles. Further, by collecting the particles, it is possible to suppress the change in the ink ejection direction and the ejection speed due to the presence of the particles in the nozzle, and it is possible to stably eject the ink.

It is a perspective view which shows the schematic structure of the inkjet printer which concerns on one Embodiment of this invention. It is an exploded perspective view of the inkjet head provided in the said inkjet printer. It is sectional drawing of the said inkjet head cut at the part along the line (III)-(III) in FIG. It is a top view of the head chip of the above-mentioned inkjet head. It is sectional drawing of the said head tip cut at the part along the line (V)-(V) in FIG. 2 is a cross-sectional view of the ink flow path member of the inkjet head cut along the line (VI)-(VI) in FIG. 2. It is explanatory drawing which shows typically the structure of the circulation mechanism provided in the said inkjet printer. It is sectional drawing of the piezoelectric element of the said inkjet head. It is a top view which shows one configuration example of the nozzle plate of the above-mentioned inkjet head. 9A is a cross-sectional view taken along the line AA'in FIG. 9A. It is sectional drawing which shows the other structural example of the said nozzle plate. It is sectional drawing which shows the further structural example of the said nozzle plate. It is a top view which shows the other example of the communication part of the nozzle plate. It is a top view which shows the further example of the said communication part. It is a top view which shows the further example of the said communication part. It is a top view which shows the other formation position of the circulation flow path portion of the nozzle plate. It is a top view which shows the other formation position of the circulation flow path portion. It is a top view which shows the other formation position of the circulation flow path portion. It is a perspective view which shows that the head chip of a share mode type inkjet head is partially broken. FIG. 18 is a cross-sectional view taken along the line VIII-VIII in FIG. It is sectional drawing which shows a part of the manufacturing process of the pressure chamber plate of the inkjet head of FIG. It is a perspective view which shows a part of the manufacturing process of the said pressure chamber plate. It is sectional drawing at the time of completion of manufacturing of the said pressure chamber plate. It is sectional drawing which shows the shape of the drive wall at the time of ink ejection of the said pressure chamber plate.

An embodiment of the present invention will be described below with reference to the drawings. In this specification, when the numerical range is expressed as A to B, the numerical range includes the values of the lower limit A and the upper limit B.

In the following description, an embodiment of a one-pass drawing method in which drawing is performed by a configuration using a line head (only transporting a recording medium) will be described as an example, but other drawing methods may be used. For example, a drawing method using a scan method or a drum method may be adopted.

Further, in the following description, the transport direction of the recording medium K is defined as the front-rear direction, the direction orthogonal to the transport direction on the transport surface of the recording medium K is defined as the left-right direction, and the directions perpendicular to the front-rear direction and the left-right direction are defined as the vertical direction. do.

[Outline of inkjet printer]
FIG. 1 is a perspective view showing a schematic configuration of an inkjet printer. The inkjet printer 100 includes a platen 101, a transport roller 102, line heads 103, 104, 105, 106, an ink circulation mechanism 107 (see FIG. 7), and the like. The details of the circulation mechanism 107 will be described later.

The platen 101 supports the recording medium K on the upper surface, and when the transport roller 102 is driven, the platen 101 transports the recording medium K in the transport direction (front-back direction).

The line heads 103 to 106 are provided in a long shape in the width direction (left-right direction) orthogonal to the transport direction (front-back direction) of the recording medium K, and are provided in parallel from the upstream side to the downstream side in the transport direction. ing. At least one inkjet head 1 (see FIG. 2 and the like) described later is provided inside the line heads 103 to 106, and for example, cyan (C), magenta (M), yellow (Y), and black. The ink (K) is ejected toward the recording medium K.

[Rough configuration of inkjet head]
FIG. 2 is an exploded perspective view of the inkjet head 1, and FIG. 3 is a cross-sectional view of the inkjet head 1 cut along the line (III)-(III) in FIG. The inkjet head 1 includes a head chip 2 (head substrate), a holding plate 3, a connecting member 4, an ink flow path member 5, and the like.

The head chip 2 is configured by laminating a plurality of substrates, and a nozzle 211 for ejecting ink is provided on the lowermost layer. The nozzle 211 communicates with the pressure chamber 231 that houses the ink. Further, a piezoelectric element 24 as a driving element is provided on the upper surface of the head chip 2. The details of the piezoelectric element 24 will be described later. Due to the displacement of the piezoelectric element 24, the ink filled in the pressure chamber 231 inside the head chip 2 is pressurized, and the ink droplets are ejected from the nozzle 211 to the outside.

The holding plate 3 is bonded to the upper surface of the head chip 2 by using an adhesive in order to maintain the strength of the head chip 2. Further, the holding plate 3 has an opening 31 in the central portion, and the piezoelectric element 24 on the upper surface of the head chip 2 is configured to be housed inside the opening 31.

The connecting member 4 is, for example, a wiring member made of FPC (Flexible Printed Circuits) or the like, and is adhered to the vicinity of the rear side of the upper surface of the holding plate 3 so that the width direction thereof is along the left-right direction of the holding plate 3. The connecting member 4 is electrically connected to the piezoelectric element 24 by the bonding wire 41. The bonding wire 41 is provided so as to pass through the opening 31 provided in the center of the holding plate 3. Further, the connecting member 4 is connected to the drive circuit 60 (see FIG. 8). As a result, power is supplied from the drive circuit 60 to the piezoelectric element 24 via the connecting member 4 and the bonding wire 41.

One ink flow path member 5 is joined to both ends of the upper surface of the holding plate 3 in the left-right direction. One ink flow path member 5 includes an ink supply flow path 501 for supplying ink to the inside of the head chip 2 and an ink circulation flow path 504 for discharging ink from the inside of the head chip 2. .. The other ink flow path member 5 includes an ink supply flow path 502 for supplying ink to the inside of the head chip 2 and an ink circulation flow path 503 for discharging ink from the inside of the head chip 2. ..

Hereinafter, the head tip 2, the holding plate 3, and the ink flow path member 5 will be described in detail.

[Head tip]
FIG. 4 is a plan view of the head chip 2. In FIG. 4, for convenience, the internal configuration of the head chip 2 is shown by a broken line. Further, the ink flow paths from the common supply flow path 25 to each communication hole 221 are hatched with a mesh.

The head chip 2 has a piezoelectric element 24 provided on the upper surface in a row along the left-right direction, and ink supply ports 201 and 202 for supplying ink from the ink flow path member 5 to the inside of the head chip 2. Ink circulation ports 203 and 204 for ejecting ink from the inside of the head chip 2 to the ink flow path member 5 are provided.

FIG. 5 is a cross-sectional view of the head tip 2 cut along the (V)-(V) line in FIG. The head chip 2 is configured by laminating and integrating three substrates, a nozzle plate 21, an intermediate plate 22, and a body plate 23, in this order from the bottom.

(Nozzle plate)
The nozzle plate 21 is a substrate located at the bottom layer of the head chip 2, and is composed of, for example, an SOI (Silicon on Insulator) wafer composed of three layers of a nozzle layer 21a, a bonding layer 21b, and a nozzle support layer 21c.

The nozzle layer 21a is a layer on which a nozzle 211 for ejecting ink flowing from the pressure chamber 231 through a communication portion 212 described later to the outside is formed, and is made of a Si substrate having a thickness of, for example, 10 to 50 μm. An ink-repellent film (not shown) is formed on the nozzle surface 214, which is the lower surface of the nozzle layer 21a. The bonding layer 21b is made of a SiO ₂ substrate having a thickness of, for example, 0.3 to 1.0 μm. The nozzle support layer 21c is made of a Si substrate having a thickness of, for example, 80 to 300 μm. The nozzle support layer 21c is formed with a communication portion 212 communicating with the pressure chamber 231 and a circulation flow path portion 213 communicating with the communication portion 212. That is, the nozzle 211, the communication portion 212, and the circulation flow path portion 213 are all formed on the same nozzle plate 21. The circulation flow path portion 213 is an individual circulation flow path portion provided corresponding to each pressure chamber 231, and is provided by branching from a communication portion 212 in the ink flow path from the pressure chamber 231 to the nozzle 211. , A flow path for circulating the remaining undischarged ink that has been discharged from the pressure chamber 231 and has not been discharged from the nozzle 211 is formed. The circulation flow path portion 213 communicates with the common circulation flow path 26 formed in the intermediate plate 22.

The shape of the nozzle 211 in a cross section perpendicular to the ink ejection direction is, for example, circular, but the cross-sectional shape of the nozzle 211 is not particularly limited as long as it can eject ink, and various cross-sectional shapes are used. Can be. For example, the cross-sectional shape of the nozzle 211 can be a polygonal shape such as a quadrangle or a hexagon.

Since the nozzle layer 21a and the nozzle support layer 21c are each made of a Si substrate, the nozzle layer 21a and the nozzle support layer 21c can be easily processed by dry etching or wet etching.

Since the circulation flow path portion 213 is formed by the gap portion facing the coupling layer 21b in the nozzle support layer 21c, the circulation flow path portion 213 is manufactured by being processed with high precision. After forming the void portion facing the bond layer 21b, the bond layer 21b is removed by a wet etching treatment using buffered hydrofluoric acid (BHF) or the like to make the circulation flow path portion 213 into the nozzle layer 21a. It may be formed by the facing voids.

The details of each part of the nozzle plate 21, including the shape of the communication part 212 described above, will be described later.

(Intermediate plate)
The intermediate plate 22 is made of a glass substrate having a thickness of, for example, about 100 to 300 μm, and has a communication hole 221 at a position corresponding to the communication portion 212 of the nozzle plate 21. The communication hole 221 is formed so as to penetrate the intermediate plate 22 in the thickness direction and communicate the pressure chamber 231 and the communication portion 212, and serve as an ink flow path when ejecting ink. By adjusting the shape of the ink flow path in the communication hole 221 such as narrowing the diameter of the communication hole 221 in the middle of the flow path direction, the kinetic energy applied to the ink in the ink ejection can be adjusted. Further, the intermediate plate 22 is provided with a common circulation flow path 26 in which the ink flowing from the plurality of circulation flow path portions 213 formed in the nozzle support layer 21c merges.

Borosilicate glass (for example, Tempax glass) is preferably used as the glass substrate constituting the intermediate plate 22.

(Body plate)
The body plate 23 is composed of a pressure chamber layer 23a and a vibration layer 23b. The pressure chamber layer 23a is made of a Si substrate having a thickness of, for example, about 100 to 300 μm. The pressure chamber layer 23a communicates with the communication hole 221 of the intermediate plate 22 to supply ink to a plurality of pressure chambers 231 having a substantially circular shape in a plan view and a plurality of pressure chambers 231 in common. The common supply flow path 25, the common supply flow path 25, and each pressure chamber 231 are individually communicated with each other, and an inlet 232 for supplying the ink in the common supply flow path 25 to the pressure chamber 231 is formed. The inlet 232 has a constricted portion whose flow path is narrower than that of the pressure chamber 231, so that the pressure applied to the pressure chamber 231 is difficult to escape from the inlet 232 side. The constricted portion may have a flow path narrower than that of the pressure chamber 231, and its shape can be appropriately changed.

The vibrating layer 23b is a thin elastically deformable Si substrate having a thickness of, for example, about 20 to 30 μm, and is laminated on the upper surface of the pressure chamber layer 23a. Further, in the vibrating layer 23b, the upper surface of the pressure chamber 231 functions as a diaphragm 233, and the diaphragm 233 vibrates according to the operation (expansion / contraction) of the piezoelectric element 24 provided on the upper surface of the diaphragm 233, and the pressure chamber 231 vibrates. Pressure can be applied to the ink inside.

Further, the vibrating layer 23b has a damper 234 formed on the upper surface of the common supply flow path 25 and a damper 235 formed on the upper surface of the common circulation flow path 26. The dampers 234 and 235 are capable of being slightly elastically deformed, for example, when pressure is applied to the pressure chamber 231 at one time and ink flows into the common circulation flow path 26 at one time. It is provided to prevent sudden pressure changes.

In the above configuration, the ink flows as follows. First, ink is supplied to the common supply flow path 25 from the ink supply ports 201 and 202 of FIG. Next, the ink branches from the common supply flow path 25 and flows in order to the inlet 232, the pressure chamber 231, the communication hole 221, the communication portion 212, and the circulation flow path portion 213 corresponding to each nozzle 211. Next, the ink from each circulation flow path portion 213 merges at the common circulation flow path 26, the ink is discharged from the ink circulation flow paths 203 and 204, and the ink is circulated through the ink circulation flow paths 503 and 504 (see FIG. 2). It is returned to the sub tank 63 (see FIG. 7).

[Holding plate]
As shown in FIGS. 2 and 3, the holding plate 3 is bonded to the upper surface of the head chip 2 with an adhesive, and is composed of a Si substrate or a glass substrate having a thickness of, for example, about 0.5 to 3.0 mm. There is. By using a Si substrate or a glass substrate for the holding plate 3, the linear expansion rate is close to that of the substrate constituting the head chip 2. Therefore, when a thermosetting adhesive or the like is used as the adhesive and a joining method accompanied by heating is used. However, the warp between the holding plate 3 and the head tip 2 is suppressed.

The plan view shape of the holding plate 3 is formed to be larger than that of the head tip 2 in both the front-rear direction and the left-right direction. In particular, both ends of the holding plate 3 in the left-right direction project more than the head tip 2. An opening 31 having a size capable of surrounding all the piezoelectric elements 24 arranged on the upper surface of the head chip 2 when joined to the head chip 2 is formed through the central portion of the holding plate 3. ing.

The opening 31 is formed in a rectangular shape extending along the left-right direction, can surround the entire piezoelectric element 24 inside the opening 31, and is provided with inks provided at both ends of the upper surface of the head chip 2. It is formed in a size that does not reach the positions of the supply ports 201 and 202 and the ink circulation ports 203 and 204. When the holding plate 3 is viewed in a plan view, each nozzle 211 formed on the nozzle plate 21 is located inside the opening 31.

The lower half of the opening 31 of the holding plate 3 is formed so that the space is larger than that of the upper half. The outer shape of the lower half of the opening 31 is the piezoelectric element 24, the common supply flow path 25 provided in the front-rear direction of the piezoelectric element 24, and the common circulation when the holding plate 3 and the head tip 2 are joined. It is formed in a size including the flow path 26 inside.

Further, as shown in FIG. 2, the ink supply ports 201 and 202 and the ink circulation ports 203 and 204 provided on the upper surface of the head chip 2 are surrounded by one each in the vicinity of both ends in the left-right direction of the holding plate 3. Through holes 301, 302, 303, and 304 having a size that can be used are formed. The through holes 301 to 304 are used as ink flow paths that communicate between the ink flow path member 5 and the head chip 2, respectively.

[Ink flow path member]
The ink flow path member 5 is formed of a synthetic resin such as PPS (polyphenylene sulfide resin) in a box shape having an open lower surface, and is arranged one by one at both ends of the upper surface of the holding plate 3 in the left-right direction. There is.

Hereinafter, since the ink flow path members 5 provided on the left and right have the same configuration, only the schematic configuration of the ink flow path member 5 on the right side will be described, and the description of the ink flow path member 5 on the left side will be omitted.

FIG. 6 is a cross-sectional view of the ink flow path member 5 cut along the line (VI)-(VI) in FIG. The ink flow path member 5 is provided with an ink supply flow path 501 that functions as a flow path for ink supply and an ink circulation flow path 504 that functions as a flow path for discharging ink. Inside the ink flow path member 5, impurities such as dust and air bubbles in the ink passing through the inside of the ink flow path member 5 are removed from each of the ink supply flow path 501 and the ink circulation flow path 504. A filter 51 is provided. For the filter 51, for example, a metal mesh such as stainless steel is used, and the filter 51 is adhered to the resin in the ink flow path member 5. The ink supplied from the ink supply flow path 501 flows through the filter 51 and the through hole 301 in order to the ink supply port 201. Further, the ink discharged from the ink circulation port 204 reaches the ink circulation flow path 504 in order through the through hole 304 and the filter 51.

[Circulation mechanism]
Next, the ink circulation mechanism 107 will be described. FIG. 7 is an explanatory diagram schematically showing the configuration of the circulation mechanism 107. The circulation mechanism 107 includes a supply sub-tank 62, a circulation sub-tank 63, ink flow paths 72, 73, 74, and pumps 81, 82.

The ink supply flow path 501 of the ink flow path member 5 is connected to the supply sub-tank 62 via the ink flow path 72. As a result, ink is supplied from the supply sub-tank 62 to the inside of the ink flow path member 5, and ink is supplied to the inside of the head chip 2 through the through hole 301 (see FIG. 6) and the ink supply port 201 (see FIG. 6). Can be supplied.

Further, the ink circulation flow path 504 of the ink flow path member 5 is connected to the circulation sub-tank 63 via the ink flow path 73. As a result, the ink discharged into the ink flow path member 5 through the ink supply port 204 (see FIG. 6) and the through hole 304 (see FIG. 6) of the head chip 2 can be discharged to the circulation sub-tank 63. can.

The supply sub-tank 62 and the circulation sub-tank 63 are provided at different positions in the vertical direction (gravity direction) with respect to the position reference plane provided with the common supply flow path 25 and the common circulation flow path 26 inside the head tip 2. ing. Then, the ink inside the head tip 2 can be circulated with respect to the position reference plane by the pressure P1 due to the head difference from the supply sub tank 62 and the pressure P2 due to the head difference from the circulation sub tank 63.

Further, the supply sub-tank 62 is connected to the circulation sub-tank 63 via the ink flow path 74, and the ink can be returned from the circulation sub-tank 63 to the supply sub-tank 62 by the pump 82.

Further, the supply sub-tank 62 is connected to the main tank 61 via the ink flow path 71, and ink can be supplied from the main tank 61 to the supply sub-tank 62 by the pump 81.

Therefore, the pressure P1 and the pressure P2 are adjusted by appropriately adjusting the head difference between the supply sub-tank 62 and the circulation sub-tank 63 and the positions of the respective sub tanks in the vertical direction (gravity direction), and the head tip is adjusted at an appropriate circulation flow velocity. 2 The ink inside can be circulated. A valve may be provided in the path of the circulation flow path, and the ink circulation may be stopped by closing the valve at the time of ink ejection.

[Details of piezoelectric element]
The piezoelectric element used in this embodiment is not particularly limited as long as it can eject ink from a nozzle. Hereinafter, the details of the piezoelectric element 24, which is an example of the piezoelectric element, will be described.

FIG. 8 is a cross-sectional view of the piezoelectric element 24. The piezoelectric element 24 is supported by the body plate 23 of the head chip 2, and is formed by laminating a lower electrode 241, a piezoelectric thin film 242 (piezoelectric body), and an upper electrode 243 in this order from the head chip 2 side. There is.

The lower electrode 241 is a common electrode commonly provided in a plurality of pressure chambers 231 and is formed of a layer made of platinum (Pt) having a thickness of, for example, about 0.1 μm. The lower electrode 241 may have a close contact layer made of titanium (Ti) or titanium oxide (TiOx) between the Pt layer and the head tip 2.

The piezoelectric thin film 242 is made of a ferroelectric thin film such as PZT (lead zirconate titanate), and is provided corresponding to each pressure chamber 231. The film thickness of the piezoelectric thin film 242 is, for example, 1 μm or more and 10 μm or less. The film forming method of the piezoelectric thin film 242 includes a chemical film forming method such as a CVD method (Chemical Vapor Deposition), a physical method such as a sputtering method and an ion plating method, a liquid phase growth method such as a sol-gel method, and printing. Various methods such as a method can be used.

The upper electrode 243 is an individual electrode provided corresponding to each pressure chamber 231 and is formed of a layer made of platinum (Pt) having a thickness of, for example, about 0.1 μm. The upper electrode 243 may have an adhesion layer between the Pt layer and the piezoelectric thin film 242. Further, the upper electrode 243 may be formed by using gold (Au) instead of Pt.

The piezoelectric element 24 is connected to the drive circuit 60 via a connecting member 4 (see FIG. 3). The drive circuit 60 is a drive control unit that controls the piezoelectric element 24, generates a drive signal for driving the piezoelectric element 24, and supplies the drive signal to the piezoelectric element 24. The drive circuit 60 may be provided in the inkjet head 1, is provided outside the inkjet head 1 and inside the inkjet printer 100, and is electrically connected to the piezoelectric element 24 of the inkjet head 1. You may.

The piezoelectric element 24 is driven based on a drive signal supplied from the drive circuit 60. That is, when a drive signal (drive voltage) is applied from the drive circuit 60 to the lower electrode 241 and the upper electrode 243, the piezoelectric thin film 242 is in a direction perpendicular to the thickness direction according to the potential difference between the lower electrode 241 and the upper electrode 243. Expands and contracts. Then, due to the difference in length between the piezoelectric thin film 242 and the diaphragm 233, a curvature is generated in the diaphragm 233, and the diaphragm 233 is displaced (curved, vibrated) in the thickness direction.

Therefore, if the ink is stored in the pressure chamber 231, the volume of the pressure chamber 231 changes due to the vibration of the vibrating plate 233 described above when the ink is ejected, and the ink in the pressure chamber 231 changes due to this volume change. It flows into the nozzle 211 through the communication hole 221 and the communication portion 212, and is discharged to the outside as ink droplets from the nozzle 211. On the other hand, when the ink is not ejected, the undischarged ink is circulated by the circulation mechanism 107 described above.

From the above, the body plate 23 having the pressure chamber 231 and the piezoelectric element 24 vibrate the vibrating plate 233 covering the pressure chamber 231 by the expansion and contraction of the piezoelectric body when a voltage is applied to the piezoelectric body (piezoelectric thin film 242). Therefore, it can be said that the bend mode type actuator that changes the volume of the pressure chamber 231 is configured.

[Details of each part of the nozzle plate]
Next, the details of each part of the nozzle plate 21 described above will be described. 9A is a plan view showing a configuration example of the nozzle plate 21, and FIG. 9B is a cross-sectional view taken along the line AA'in FIG. 9A. The communication portion 212 formed on the nozzle plate 21 has four tapered walls 212a, and the outer shape of the communication portion 212 defined by the four tapered walls 212a is a quadrangular pyramid (here, a regular quadrangular pyramid or a quadrangular pyramid). It is almost equal to the shape defined by the side surface of. That is, the four tapered walls 212a correspond to the four side surfaces of the quadrangular pyramid (the surfaces excluding the bottom surface facing the apex). The nozzle 211 is located at a portion of the communication portion 212 corresponding to the apex of the quadrangular pyramid, and the communication portion 212 and the nozzle 211 communicate with each other. In the communication portion 212, the portion corresponding to the bottom surface of the quadrangular pyramid is an opening through which ink flows from the communication hole 221 (see FIG. 5) toward the communication portion 212.

The tapered wall 212a is inclined with respect to the surface S1 perpendicular to the thickness direction of the nozzle plate 21 so that the opening area of the communication portion 212 becomes smaller from the pressure chamber 231 side toward the nozzle 211 side. The circulation flow path portion 213 is provided in the nozzle plate 21 so as to penetrate the tapered wall 212a of any of the four, and communicates with the communication portion 212.

The nozzle plate 21 having the above configuration can be manufactured, for example, as follows. First, a Si substrate is prepared as the nozzle plate 21. The thickness of the Si substrate is, for example, 150 μm. This Si substrate is deep-drilled by a bosh process using an ICP (Inductively Coupled Plasma) device to form a nozzle 211 having a height in the thickness direction of, for example, 10 to 50 μm. Here, as the nozzle 211, a straight nozzle 211a having a constant opening diameter in the ink ejection direction is formed.

Next, anisotropic etching is performed by wet etching on the surface of the Si substrate opposite to the nozzle 211 side. When the surface of the Si substrate (the surface perpendicular to the thickness direction of the substrate) is the Si (100) surface, etching the Si substrate with a chemical such as KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide) results in an etching rate. The slow Si (111) surface is exposed, a tapered wall 212a appears along the Si (111) surface, and a communication portion 212 having a quadrangular pyramid outer shape is formed. At this time, if the inclination angle of the tapered wall 212a with respect to the surface S1 is α (°), α = 54.7 °. The surface S1 is parallel to the Si (100) surface. By forming the communication portion 212 by wet etching in this way, the tapered communication portion 212 can be easily obtained.

Further, the Si substrate is dry-etched or wet-etched to form a circulation flow path portion 213 that communicates with the communication portion 212. In particular, when the circulation flow path portion 213 is formed by wet etching, the etching surface becomes a smooth crystal plane, and a good circulation flow path portion 213 having a small flow path resistance is formed. Further, in the case of wet etching, the side surface of the circulation flow path portion 213 is inclined with respect to the Si (100) surface to reduce the flow path resistance, so that the ink easily flows through the circulation flow path portion 213 and is easily circulated. .. Further, it becomes easy to adjust the flow path resistance of the circulation flow path portion 213.

As an example of specific specifications, the thickness of the Si substrate is about 100 to 300 μm, preferably 150 μm or less. The hole diameter N of the nozzle 211 is about 10 to 50 μm, preferably about 20 to 30 μm, and the height h1 of the nozzle 211 (the length in the thickness direction of the nozzle plate 21) is 10 to 50 μm, preferably 20. It is about 30 μm. The length W of the circulation flow path portion 213 in the flow path direction is about 600 to 1500 μm, the height h2 of the circulation flow path portion 213 is about 80 to 200 μm, and the width of the circulation flow path portion 213 (FIG. 9B). The length in the depth direction) is about 20 to 50 μm.

As described above, in the nozzle plate 21, the communication portion 212 communicating with the nozzle 211 has a tapered wall 212a. In this way, by forming the side surface of the communication portion 212 into a tapered shape and connecting it to the side surface of the nozzle 211, there is no surface perpendicular to the ink flow path direction as in the case where the nozzle is configured with the conventional two-step hole. , The flow path resistance of the ink becomes small, and the ink flows smoothly from the communication portion 212 toward the nozzle 211. As a result, the refillability of the ink from the pressure chamber 213 to the nozzle 211 can be improved, and it becomes possible to easily cope with the ink ejection of large droplets and the ink ejection at high speed. Further, by improving the refillability, the ink meniscus of the nozzle 211 can be stably held.

Further, the circulation flow path portion 213 is provided in the nozzle plate 21 so as to penetrate the tapered wall 212a of the communication portion 212, and communicates with the communication portion 212. By providing the circulation flow path portion 213 on the same plate as the nozzle plate 21 provided with the nozzle 211, the circulation flow path portion 213 can be positioned in the vicinity of the nozzle 211. As a result, even when ink containing particles that easily settle (for example, pigment) is used, excess particles that have settled in the vicinity of the nozzle 211 are efficiently guided to the circulation flow path portion 213 via the communication portion 212 and recovered. be able to. As a result, it is possible to suppress the occurrence of clogging of the nozzle 211 due to the particles. Further, by collecting the particles, it is possible to suppress the change in the ink ejection direction and the ejection speed due to the presence of the particles in the nozzle, and it is possible to stably eject the ink.

Further, when high-speed ink ejection is performed, the amount of air bubbles entrained from the nozzle 211 also increases, but in the present embodiment, since the circulation flow path portion 213 is located near the nozzle 211, the entrained air bubbles are efficiently circulated. It can be guided to the flow path portion 213 and collected. This makes it possible to prevent a meniscus break due to the entrained air bubbles.

Here, if the inclination angle α of the tapered wall 212a with respect to the surface S1 is too small, the tapered wall 212a approaches the horizontal, so that the flow path resistance of the ink increases and there is a concern that the refillability deteriorates. On the contrary, if the inclination angle α is too large, the opening area of the communication portion 212 becomes small (the hole diameter of the nozzle 211 is constant), so that the adhesive used for adhering the nozzle plate 21 and the intermediate plate 22 is the communication portion. There is a risk of getting into 212 and blocking it. Considering the above, it is desirable that the inclination angle α of the tapered wall 212a is 30 ° or more and 60 ° or less.

In the above, an example in which the nozzle 211 is formed by the straight nozzle 211a has been described. In this case, since the straight nozzle 211a can be formed by deep-drilling Si using the well-established Bosch process, stable production is possible. However, the nozzle 211 is not limited to such a straight nozzle 211a.

10 and 11 are cross-sectional views showing another configuration example of the nozzle plate 21. The nozzle 211 may be configured to include a tapered nozzle 211b. At this time, the nozzle 211 may be configured by connecting the tapered nozzle 211b and the straight nozzle 211a as shown in FIG. 10, or may be configured by the tapered nozzle 211b alone as shown in FIG. May be good. The tapered nozzle 211b is configured such that the side surface 211b ₁ is inclined with respect to the surface S2 perpendicular to the thickness direction of the nozzle plate 21 so that the opening area becomes smaller toward the ink ejection side of the nozzle 211 from the pressure chamber 231 side. It is a nozzle that has been made.

When forming the taper nozzle 211b, the Bosch process is applied and Si deep digging is performed while tapering. Although it is difficult to manufacture, it is expected to improve the ink ejection characteristics. In addition, efficient ink ejection is possible, and the ejection voltage can be lowered as compared with the case of the straight nozzle 211a (ink can be ejected with a small ejection voltage).

Here, when the inclination angle of the side surface 211b ₁ of the taper nozzle 211b with respect to the surface S2 is β (°), if α> β, when the ink from the communication portion 212 flows through the nozzle 211, the taper nozzle 211b There is a concern that the side surface 211b ₁ becomes a flow path resistance and the refillability is deteriorated. Therefore, it is desirable to satisfy α <β.

In particular, from the viewpoint of surely suppressing the increase in flow path resistance and surely improving the refillability, it is desirable to satisfy α <β and then β> 60 °, and satisfy β ≧ 70 °. It is more desirable, and it is further desirable to satisfy 80 ° ≤ β ≤ 85 °.

Further, the smaller the height h1 (see FIG. 9B) of the nozzle 211 along the thickness direction of the nozzle plate 21, the better the refillability to the nozzle 211. In this respect, the height h1 of the nozzle 211 is preferably 50 μm or less.

[Variations in the shape of the communication part]
In the above, the case where the outer shape of the communication portion 212 defined by the tapered wall 212a is substantially equal to the shape defined by the side surface of the regular quadrangular pyramid among the quadrangular pyramids has been described, but the communication portion 212 has such a shape. Not limited.

12 to 14 are plan views showing another example of the communication portion 212. Here, for convenience of the description below, one of the two directions perpendicular to each other in the plane perpendicular to the thickness direction of the nozzle plate 21 (for example, in the plane S1) is defined as the X direction, and the other direction (X). The direction perpendicular to the direction) is the Y direction.

As shown in FIG. 12, the outer shape of the communication portion 212 may be horizontally long in the X direction, and the bottom surface may be substantially equal to the shape defined by the side surface of the horizontally long square cone (rectangular cone). As shown in FIG. 13, the shape may be substantially equal to the shape defined by the side surface of the cone, or as shown in FIG. 14, the shape is horizontally long in the X direction and the bottom surface is a horizontally long cone (elliptical pyramid). It may be substantially equal to the shape defined by the sides. In the shape of the communication portion 212 of FIGS. 13 and 14, the number of tapered walls 212a is one. In addition, although not shown, the outer shape of the communication portion 212 may be substantially the same as the shape defined by the side surface of the polygonal pyramid other than the quadrangular pyramid, and two tapered walls 212a having different inclination angles α are provided in the circumferential direction. Alternatively, it may have a shape in which three pieces are connected. In any case, if the communication portion 212 has at least one of the above-mentioned tapered walls 212a, the flow path resistance of the ink becomes smaller than in the case where the nozzle is formed by the two-step hole as in the conventional case. The effects of the above-described embodiment can be obtained, such as improving the refillability of the ink from the pressure chamber 213 to the nozzle 211.

[About the formation position of the circulation flow path]
As shown in FIGS. 12 and 14, a quadrangular pyramid or an ellipse having a horizontally long bottom surface such that the outer shape of the communication portion 212 defined by the tapered wall 212a has a width in the X direction relatively larger than that in the Y direction. When substantially equal to the shape defined by the side surface of the cone, the circulation flow path portion 213 is provided in the nozzle plate 21 so as to penetrate the tapered wall 212a on one end side in the X direction in which the outer shape of the communication portion 212 is horizontally long. , May communicate with the communication unit 212. In this case, since the formation pitch of the nozzle 211 can be narrowed in the Y direction, it is possible to realize an inkjet head 1 capable of ejecting small and high-definition ink.

15 and 16 are plan views showing other formation positions of the circulation flow path portion 213. As shown in the figure, the outer shape of the communication portion 212 is substantially equal to the shape defined by the side surface of a horizontally long quadrangular pyramid or elliptical pyramid such that the width in the X direction is relatively larger than that in the Y direction. In this case, the circulation flow path portion 213 is provided on the nozzle plate 21 so as to penetrate the tapered wall 212a located on one end side in the Y direction different from the X direction in which the outer shape of the communication portion 212 is horizontally long, and the communication portion 212 is provided. You may communicate with. In this case, in order to avoid interference between the circulation flow path portion 213 and the communication portion 212 that does not communicate with the circulation flow path portion 213 in the Y direction, the circulation flow path portion 213 extending in the Y direction is bent in the X direction at the bent portion 213a. It is necessary to bend it into a shape.

As shown in FIGS. 15 and 16, when the circulation flow path portion 213 communicates with the communication section 212 at one end side in the Y direction, the circulation flow path section communicates with the communication section 212 at one end side in the X direction. The connection portion 213b between the 213 and the communication portion 212 is arranged at a position closer to the nozzle 211. As a result, the particles that have settled in the vicinity of the nozzle 211 can be more efficiently guided to the circulation flow path portion 213 via the communication portion 212 and recovered. As a result, the effects of preventing clogging of the nozzle 211 and stabilizing ink ejection can be reliably obtained.

FIG. 17 is a plan view showing still another formation position of the circulation flow path portion 213. As shown in the figure, when the outer shape of the communication portion 212 is substantially equal to the shape defined by the side surface of the quadrangular pyramid, the circulation flow path portion 213 connects the connecting portions 212b of the two adjacent tapered walls 212a and 212a. It may be provided on the nozzle plate 21 so as to penetrate and communicate with the communication portion 212. By forming the circulation flow path portion 213 at the diagonal portion of the communication portion 212 (the portion corresponding to the corner portion of the bottom surface of the quadrangular pyramid), the flow path resistance smoothly changes from the communication portion 212 to the circulation flow path portion 213. , The circulation efficiency is improved. Further, when the outer shape of the communicating portion 212 is substantially equal to the shape defined by the side surface of the quadrangular pyramid, the connecting portion 212b of the adjacent tapered walls 212a and 212a becomes a corner portion, and therefore the particles (pigment) in the ink are formed in this corner portion. Etc.) tend to stay. Therefore, by forming the circulation flow path portion 213 so as to penetrate the connecting portion 212b, the particles that stay at the position where they are likely to stay can be surely guided to the circulation flow path portion 213 and recovered by circulation.

Further, as shown in the figure, the circulation flow path portion 213 may have a flow path changing section 213c. The flow path changing section 213c is a bending section that changes the flow path direction of the undischarged ink flowing from the communication section 212 between the inflow direction and the outflow direction. By providing the flow path changing portion 213c in the circulation flow path portion 213, the length of the circulation flow path portion 213 is adjusted so that the optimum flow path resistance can be obtained for ink ejection and circulation of undischarged ink. Can be done. That is, the optimum design for discharge and circulation becomes possible.

In the configurations of FIGS. 15 and 16, the flow path direction of the undischarged ink flowing from the communication section 212 to the circulation flow path section 213 is changed from the Y direction to the X direction at the bending section 213a. It can be said that the portion 213a also has the same function as the flow path changing portion 213c shown in FIG. Therefore, it can be said that the optimum design for discharge and circulation can be realized for the configurations of FIGS. 15 and 16.

[About share mode actuator]
In the above, the inkjet head 1 provided with the bend mode type actuator utilizing the bending deformation of the diaphragm due to the expansion and contraction of the piezoelectric body has been described. However, the configuration of the nozzle plate 21 of the present embodiment described above is the share mode type actuator. It can also be applied to an inkjet head equipped with.

FIG. 18 is a perspective view showing a partially broken head chip 2 of the share mode type inkjet head 1. The arrow in the figure indicates the flow of ink, and the broken line arrow indicates the flow of undischarged ink during circulation. Further, FIG. 19 is a cross-sectional view taken along the line VIII-VIII in FIG. The broken line arrow shown in FIG. 18 corresponds to the solid line arrow in FIG.

The head tip 2 is configured by joining the nozzle plate 21 and the pressure chamber plate 27. The pressure chamber plate 27 is a share mode type actuator that changes the volume of the pressure chamber by shear deformation of the piezoelectric body generated by applying an electric field in a direction orthogonal to the polarization direction of the piezoelectric body. In the pressure chamber plate 27, a plurality of pressure chambers 231 are arranged in a staggered manner, and a common circulation flow path 26 is formed.

The nozzle plate 21 is formed with a communication portion 212 having a tapered wall 212a, a nozzle 211 communicating with the communication portion 212, and a circulation flow path portion 213. The circulation flow path portion 213 is provided in the nozzle plate 21 through the tapered wall 212a and communicates with the communication portion 212. Further, the circulation flow path portion 213 also communicates with the common circulation flow path 26 of the pressure chamber plate 27.

As described above, since the communication portion 212 of the nozzle plate 21 has the tapered wall 212a and the circulation flow path portion 213 penetrates the tapered wall 212a and communicates with the communication portion 212, the ink to the nozzle 211 is inked. It is possible to easily cope with ink ejection of large droplets and ink ejection at high speed by improving the refillability of the nozzle 211, suppress clogging of the nozzle 211, and stably eject ink. ..

In particular, in the share mode type actuator, since each pressure chamber 231 is formed in a rectangular cross section as shown in FIG. 18, it is defined by the tapered wall 212a from the viewpoint of reducing the flow path resistance and improving the refillability. It is considered desirable that the outer shape of the communicating portion 212 is similar to or close to the cross-sectional shape of the pressure chamber 231 in a plan view. That is, it is considered desirable that the outer shape of the communication portion 212 is substantially equal to the shape defined by the side surface of a horizontally long quadrangular pyramid or a cone (elliptical pyramid).

Next, the method for manufacturing the pressure chamber plate 27 described above will be described. FIG. 20 is a cross-sectional view showing a manufacturing process of the pressure chamber plate 27. First, two piezoelectric element substrates 272a and 272b are joined on the lower substrate 271 in this order. As the piezoelectric element material used for the piezoelectric element substrates 272a and 272b, known piezoelectric element materials such as PZT that are deformed by applying a voltage can be used. The piezoelectric element substrates 272a and 272b are laminated so that their polarization directions (indicated by arrows) are opposite to each other, and are bonded onto the lower substrate 271 using an adhesive.

Next, a plurality of parallel grooves are ground over the two piezoelectric element substrates 272a and 272b using a dicing blade or the like. As a result, the drive walls 272 whose polarization directions are opposite to each other in the height direction are juxtaposed on the lower substrate 271. Each groove is ground from one end of the piezoelectric element substrates 272a and 272b to the other end at substantially the same constant depth to form a straight ink channel 273. The ink channel 273 is a portion corresponding to the pressure chamber 231.

Instead of using the lower substrate 271, a thick piezoelectric element substrate 272a is used, and a plurality of parallel grooves extending from the thin piezoelectric element substrate 272b side to the middle part of the thick piezoelectric element substrate 272a are ground. A drive wall 272 whose polarization direction is opposite in the height direction may be formed. In this case, the drive wall 272 and the lower substrate portion can be integrally formed.

Subsequently, a drive electrode 274 is formed on the inner surface of each ink channel 273. The metal forming the drive electrode 274 includes nickel (Ni), cobalt (Co), copper (Cu), aluminum (Al) and the like, but from the viewpoint of electrical resistance, it is preferable to use Al or Cu, which corrodes. It is preferable to use Ni in terms of strength, strength and cost. Examples of the method for forming the drive electrode 274 include a vapor deposition method, a sputtering method, a plating method, a method using a vacuum device such as a CVD (chemical vapor deposition method), and the like.

After that, as shown in FIG. 21, the upper substrate 275 is bonded to the drive wall 272 (piezoelectric element substrates 272a and 272b) with an adhesive. Here, when the same substrate material as the piezoelectric material constituting the drive wall 272 is depolarized and used as the upper substrate 275 and the lower substrate 271, warpage due to the difference in the coefficient of thermal expansion due to the influence of heat during driving is generated. Deformation can be prevented.

Next, by cutting the substrate obtained above along a plurality of cut lines C1, C2, ... Along the plane orthogonal to the length direction of the ink channel 273, the upper substrate 275 and the drive wall 272 are formed. A plurality of harmonica type substrates 276 formed by joining the lower substrate 271 and the lower substrate 271 can be obtained.

Subsequently, as shown in FIG. 22, the two substrates 276 and 276 are bonded so that the two upper substrates 275 and 275 face each other and the positions of the ink channels 273 are displaced between the upper and lower stages. By laminating with the agent, a pressure chamber plate 27 in which each ink channel 273 (pressure chamber 231) is arranged in a staggered manner is obtained.

FIG. 23 is a cross-sectional view showing the shape of the drive wall 272 when the ink is ejected from the pressure chamber plate 27. In the pressure chamber plate 27, the drive electrode 274 (see FIG. 20) is electrically connected to a drive circuit (not shown) and is perpendicular to the drive wall 272 (piezoelectric element substrates 272a / 272b) via the drive electrode 274 in the polarization direction. When an electric field in the direction is applied, the drive wall 272 undergoes shear deformation as shown in FIG. 23, whereby the volume of the ink channel 273 sandwiched between the adjacent drive walls 272 and 272, that is, the pressure chamber 231 changes. Due to such volume deformation of the pressure chamber 231, the ink in the pressure chamber 231 is ejected from the nozzle 211 (see FIG. 18).

〔supplement〕
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the gist of the invention.

The method for manufacturing an inkjet head, an inkjet printer, and an inkjet head according to the present embodiment described above can be expressed as follows.

The inkjet head of the present embodiment has a pressure chamber for accommodating ink, an actuator that changes the volume of the pressure chamber, a communication portion that communicates with the pressure chamber, and the communication portion that communicates with the communication portion. The nozzle plate is provided with a nozzle for ejecting ink flowing from the pressure chamber through the communication portion to the outside due to a change in the volume of the pressure chamber, and a nozzle plate having a circulation flow path portion for circulating undischarged ink. The communication portion has at least one tapered wall, and the tapered wall is in the thickness direction of the nozzle plate so that the opening area of the communication portion becomes smaller from the pressure chamber side to the nozzle side. The circulation flow path portion is provided on the nozzle plate so as to penetrate the at least one tapered wall and communicates with the communication portion.

The outer shape of the communication portion defined by the tapered wall may be substantially equal to the shape defined by the side surface of any of a quadrangular pyramid, a cone, and an elliptical pyramid.

The outer shape of the communication portion defined by the tapered wall is substantially equal to the shape defined by the side surface of the quadrangular pyramid, and the circulation flow path portion penetrates the connecting portion of the two adjacent tapered walls. It may be provided on the nozzle plate and communicate with the communication portion.

The outer shape of the communication portion defined by the tapered wall is substantially equal to the shape defined by the side surface of a horizontally long quadrangular pyramid or elliptical cone, and the circulation flow path portion is perpendicular to the thickness direction of the nozzle plate. The nozzle plate is provided on the nozzle plate so as to penetrate the tapered wall on one end side in the direction in which the outer shape of the communicating portion is horizontally long among the two directions perpendicular to each other in the plane, and communicates with the communicating portion. May be good.

The outer shape of the communication portion defined by the tapered wall is substantially equal to the shape defined by the side surface of a horizontally long quadrangular pyramid or elliptical cone, and the circulation flow path portion is perpendicular to the thickness direction of the nozzle plate. The nozzle plate is provided on the nozzle plate so as to penetrate the tapered wall at one end side in a direction different from the direction in which the outer shape of the communicating portion is horizontally long among the two directions perpendicular to each other in the plane. It may be communicated.

It is desirable that the inclination angle of the tapered wall with respect to the plane perpendicular to the thickness direction of the nozzle plate is 30 ° or more and 60 ° or less.

The nozzle may be a straight nozzle having a constant opening diameter.

The nozzle may include a tapered nozzle whose side surface is inclined with respect to a surface perpendicular to the thickness direction of the nozzle plate so that the opening area becomes smaller toward the ink ejection side from the pressure chamber side. ..

The angle of inclination of the tapered wall of the communication portion with respect to the surface perpendicular to the thickness direction of the nozzle plate is α (°), and the inclination angle of the side surface of the tapered nozzle with respect to the surface perpendicular to the thickness direction of the nozzle plate. When the tilt angle is β (°)
α <β
Is desirable.

β> 60 °
Is desirable.

The height of the nozzle along the thickness direction of the nozzle plate is preferably 50 μm or less.

It is desirable that the circulation flow path portion has a flow path changing section that changes the flow path direction of the undischarged ink flowing from the communication section.

The actuator may be of a bend mode type in which the volume of the pressure chamber is changed by vibrating the diaphragm covering the pressure chamber by the expansion and contraction of the piezoelectric body when a voltage is applied to the piezoelectric body.

The actuator may be a share mode type in which the volume of the pressure chamber is changed by shear deformation of the piezoelectric body generated by applying an electric field in a direction orthogonal to the polarization direction of the piezoelectric body.

The inkjet printer of the present embodiment includes the above-mentioned inkjet head, and ejects ink from the inkjet head toward the recording medium.

The method for manufacturing an inkjet head according to the present embodiment is the above-mentioned manufacturing method for manufacturing an inkjet head, and the communication portion may be formed by wet etching. Further, the circulation flow path portion may be formed by wet etching.

The inkjet head of the present invention can be used for an inkjet printer.

1 Inkjet head 21 Nozzle plate 23 Body plate (actuator)
24 Piezoelectric element (actuator)
27 Pressure chamber plate (actuator)
100 Inkjet printer 211 Nozzle 211a Straight nozzle 211b Tapered nozzle 211b ₁ Side surface 212 Communication part 212a Tapered wall 212b Connecting part 213 Circulation flow path part 213a Bending part (flow path changing part)
213c Flow path change part 231 Pressure chamber

Claims (16)

An actuator that has a pressure chamber for accommodating ink and changes the volume of the pressure chamber,
A nozzle that communicates with the pressure chamber, a nozzle that communicates with the communication portion, and ejects ink that flows from the pressure chamber through the communication portion to the outside due to a volume change of the pressure chamber by the actuator, and a nozzle that does not eject. A nozzle plate having a circulation flow path portion for circulating the ink of
The communication portion has at least one tapered wall connected to the side surface of the nozzle.
The tapered wall is inclined with respect to a surface perpendicular to the thickness direction of the nozzle plate so that the opening area of the communication portion becomes smaller from the pressure chamber side to the nozzle side.
The circulation flow path portion is provided in the nozzle plate so as to penetrate the at least one tapered wall, and communicates with the communication portion .
The outer shape of the communication portion defined by the tapered wall is substantially equal to the shape defined by the side surface of any of a quadrangular pyramid, a cone, and an elliptical pyramid .
In the communication portion, the portion corresponding to the bottom surface of any one of the quadrangular pyramid, the cone, and the elliptical cone is an opening through which ink flowing from the pressure chamber toward the communication portion passes.
The actuator is a share mode type actuator that changes the volume of the pressure chamber by shear deformation of the piezoelectric body generated by applying an electric field in a direction orthogonal to the polarization direction of the piezoelectric body. An actuator that has a pressure chamber for accommodating ink and changes the volume of the pressure chamber,
The communication portion communicating with the pressure chamber and the communication portion communicating with the actuator are used. Due to the volume change of the pressure chamber, the ink flowing from the pressure chamber through the communication portion is sent to the outside. Nozzle pre with a nozzle for ejecting and a circulation flow path portion for circulating undischarged ink Equipped with
The communication portion has at least one tapered wall connected to the side surface of the nozzle. ,
The tapered wall opens the communication portion from the pressure chamber side toward the nozzle side. Inclined with respect to the plane perpendicular to the thickness direction of the nozzle plate so that the area is small. the law of nature,
The circulation flow path portion penetrates the at least one tapered wall. It is provided in the communication part and communicates with the communication part.
The outer shape of the communication portion defined by the tapered wall is defined by the side surface of the quadrangular pyramid. Approximately the same shape as
The circulation flow path portion has the nose so as to penetrate the connecting portion of the two adjacent tapered walls. It is provided on the plate and communicates with the communication part.
In the communication portion, the portion corresponding to the bottom surface of the quadrangular pyramid is from the pressure chamber to the communication portion. An inkjet head, which is an opening through which ink flows toward. An actuator that has a pressure chamber for accommodating ink and changes the volume of the pressure chamber,
The communication portion communicating with the pressure chamber and the communication portion communicating with the actuator are used. Due to the volume change of the pressure chamber, the ink flowing from the pressure chamber through the communication portion is sent to the outside. A nozzle pre with a nozzle for ejecting and a circulation flow path portion for circulating undischarged ink. Equipped with
The communication portion has at least one tapered wall connected to the side surface of the nozzle. ,
The tapered wall opens the communication portion from the pressure chamber side toward the nozzle side. Inclined with respect to the plane perpendicular to the thickness direction of the nozzle plate so that the area is small. the law of nature,
The circulation flow path portion penetrates the at least one tapered wall. It is provided in the communication part and communicates with the communication part.
The outer shape of the communication portion defined by the tapered wall is a quadrangular pyramid or ellipse having a horizontally long bottom surface. Approximately equal to the shape defined by the sides of the cone,
The circulation flow path portion has two directions perpendicular to each other in a plane perpendicular to the thickness direction of the nozzle plate. Of these, so as to penetrate the tapered wall at one end side in the direction in which the outer shape of the communicating portion becomes horizontally long. Provided on the nozzle plate to communicate with the communication portion,
In the communication portion, the portion corresponding to the bottom surface of the quadrangular pyramid or the elliptical cone is the pressure. An inkjet head, which is an opening through which ink flowing from the chamber toward the communication portion passes. De. An actuator that has a pressure chamber for accommodating ink and changes the volume of the pressure chamber,
The communication portion communicating with the pressure chamber and the communication portion communicating with the actuator are used. Due to the volume change of the pressure chamber, the ink flowing from the pressure chamber through the communication portion is sent to the outside. Nozzle pre with a nozzle for ejecting and a circulation flow path portion for circulating undischarged ink Equipped with
The communication portion has at least one tapered wall connected to the side surface of the nozzle. ,
The tapered wall opens the communication portion from the pressure chamber side toward the nozzle side. Inclined with respect to the plane perpendicular to the thickness direction of the nozzle plate so that the area is small. the law of nature,
The circulation flow path portion penetrates the at least one tapered wall. It is provided in the communication part and communicates with the communication part.
The outer shape of the communication portion defined by the tapered wall is a quadrangular pyramid or ellipse having a horizontally long bottom surface. Approximately equal to the shape defined by the sides of the cone,
The circulation flow path portion has two directions perpendicular to each other in a plane perpendicular to the thickness direction of the nozzle plate. Of these, the tapered wall is formed on one end side in a direction different from the direction in which the outer shape of the communicating portion is horizontally long. It is provided on the nozzle plate so as to penetrate, and communicates with the communication portion.
In the communication portion, the portion corresponding to the bottom surface of the quadrangular pyramid or the elliptical cone is the pressure. An inkjet head, which is an opening through which ink flowing from the chamber toward the communication portion passes. De. The angle of inclination of the tapered wall with respect to the plane perpendicular to the thickness direction of the nozzle plate is 3. The inkjet head according to any one of claims 1 to 4, wherein the temperature is 0 ° or more and 60 ° or less. The nozzle is a straight nozzle having a constant opening diameter, according to any one of claims 1 to 5. The inkjet head described. The opening area of the nozzle decreases from the pressure chamber side toward the ink ejection side. As described above, the taper whose side surface is inclined with respect to the surface perpendicular to the thickness direction of the nozzle plate. The inkjet head according to any one of claims 1 to 5, which comprises a slur. The inclination of the tapered wall of the communication portion with respect to the plane perpendicular to the thickness direction of the nozzle plate. The inclination angle is α (°), and the thickness of the nozzle plate on the side surface of the tapered nozzle. When the tilt angle with respect to the plane perpendicular to the direction is β (°),
α <β
The inkjet head according to claim 7. β> 60 °
The inkjet head according to claim 8. The height of the nozzle along the thickness direction of the nozzle plate is 50 μm or less. The inkjet head according to any one of Items 1 to 9. The circulation flow path portion is a flow that changes the flow path direction of the undischarged ink flowing from the communication flow path portion. The inkjet head according to any one of claims 1 to 10, which has a path changing portion. The actuator is moved forward by the expansion and contraction of the piezoelectric body when a voltage is applied to the piezoelectric body. By vibrating the diaphragm that covers the pressure chamber, the volume of the pressure chamber is changed. The inkjet head according to any one of claims 2 to 4, which is a type of inkjet head. The actuator is generated by applying an electric field in a direction orthogonal to the polarization direction of the piezoelectric body. A share mode type that changes the volume of the pressure chamber by shear deformation of the piezoelectric body. Item 4. The inkjet head according to any one of Items 2 to 4. The inkjet head according to any one of claims 1 to 13 is provided, and the ink jet is provided. An inkjet printer that ejects ink from the head toward the recording medium. An inkjet that manufactures the inkjet head according to any one of claims 1 to 13. It ’s a head manufacturing method.
A method for manufacturing an inkjet head, in which the communication portion is formed by wet etching. An inkjet that manufactures the inkjet head according to any one of claims 1 to 13. It ’s a head manufacturing method.
A method for manufacturing an inkjet head, in which the circulation flow path portion is formed by wet etching.

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