TWI819087B - inkjet head - Google Patents

Abstract

[Project] Provide a highly reliable inkjet head. [Solution] An inkjet head, including: a piezoelectric element; a vibration plate; and a bonding material layer disposed between the piezoelectric element and the vibration plate, and joining the piezoelectric element and the vibration plate, and the bonding material layer contains hardness The beads are taller than the diaphragm, and the film thickness of the adhesive layer is smaller than the particle size of the beads.

Description

inkjet head

Field of invention This disclosure relates to an inkjet head.

Background of the invention In the manufacturing process of electronic devices or optical devices, printing is often used to form fine patterns on a substrate. In the printing of fine patterns, it is necessary to reduce the size and increase the density of a series of flow paths, piezoelectric elements, vibration plates, etc. involved in discharging the ink-formed material. In addition, a technology for miniaturizing and increasing the density of piezoelectric elements has been disclosed in the past (for example, see Patent Document 1).

Patent Document 1 discloses a liquid ejection head in which the width of the adhesion layer following the conductive layer is narrowed in the lead-out wiring for driving the piezoelectric elements, so that even if the piezoelectric elements are arranged at high density, the liquid ejection head can be Prevents short circuits between adjacent lead wires. Prior technical literature patent documents

Patent Document 1: Japanese Patent Application Publication No. 2018-027711 Patent Document 2: Japanese Patent Application Publication No. 10-34919

Summary of the invention The problem to be solved by the invention However, when ejecting ink using an inkjet head, the vibration plate and the piezoelectric element must be reliably connected. For example, if the reliability of this joint is low, there may be a problem that the diaphragm is peeled off from the piezoelectric element, and the designed ink ejection accuracy cannot be maintained.

Therefore, an object of this disclosure is to provide a highly reliable inkjet head. means to solve problems

An aspect of the inkjet head in the present disclosure includes: a piezoelectric element; a vibration plate; and a bonding material layer disposed between the piezoelectric element and the vibration plate, and joining the piezoelectric element and the vibration plate, and The adhesive material layer contains beads having a higher hardness than the diaphragm, and the film thickness of the adhesive material layer is smaller than the particle diameter of the beads. Invention effect

According to one aspect of the present disclosure, a highly reliable inkjet head can be provided.

Form used to implement the invention [Intellectual insights that form the basis of revelation] As a method of forming fine patterns at low cost, the printing method in which a material of a desired pattern is inked and then printed on a base material, and the inkjet method which does not require special preparation of a printing plate are attracting attention. However, in recent years, with the demand for miniaturization of patterns formed by the inkjet method, the pitch between the nozzles of the nozzle row has become smaller, and along with this, the area of the joint portion of the components constituting the inkjet head has also become smaller.

As a result, the joint strength of the joint portion of each member is likely to decrease. In an inkjet head using a piezoelectric element, the joint portion between the piezoelectric element and the vibration plate will move at a high speed in conjunction with the driving of the piezoelectric element. To vibrate, the piezoelectric element is driven to generate pressure in the ink chamber, and the vibration plate transmits the driven displacement as vibration to the ink chamber. Therefore, in the joint portion between the piezoelectric element and the diaphragm, there is a problem that the joint strength is particularly reduced, and the piezoelectric element and the diaphragm are easily peeled off, resulting in low reliability.

Regarding this subject, the following prior art has been disclosed and will be explained using FIG. 1 . FIG. 1 is an enlarged cross-sectional view of the joint between the piezoelectric element and the vibration plate in the conventional inkjet head 100a.

Patent Document 2 discloses a technology for roughening the joint surface between the joint portion 82a of the diaphragm 8a and the piezoelectric element 5a as shown in FIG. 1 . In this technology, by roughening the surface of the joint portion 82a, the adhesive material enters the roughened surface (joint surface) and hardens, thereby forming the adhesive material layer 9a. Therefore, the anchoring effect can be obtained to improve joint strength. However, since the roughening step is performed using chemical or electrochemical treatment after the vibration plate 8a is formed, it is very complicated. In addition, since the diaphragm 8a is an extremely thin member of several μm to tens of μm, the process margin of the roughening amount becomes narrow, making it difficult to control the process. That is, if there is unevenness in the manufacturing process, the joint surface between the joint portion 82a and the piezoelectric element 5a will be too rough, causing the film thickness to become too thin, resulting in pinholes, or insufficient roughening to obtain sufficient film thickness. The issue of joint strength.

The present disclosure solves the above-mentioned problems in the conventional technology, and aims to provide a highly reliable inkjet head by improving the bonding strength between the diaphragm and the piezoelectric element at low cost without requiring additional steps such as a roughening step.

In order to achieve the above object, an inkjet head according to an aspect of the present disclosure includes: a piezoelectric element; a vibrating plate; and a bonding material layer disposed between the piezoelectric element and the vibrating plate, and joining the piezoelectric element and the vibrating plate. , and the adhesive layer contains beads with a higher hardness than the diaphragm, and the film thickness of the adhesive layer is smaller than the particle size of the beads.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, the embodiments described below are all embodiments showing comprehensiveness or specific examples. The numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, steps, step sequences, etc. shown in the following embodiments are only examples and are not intended to limit the present disclosure. Moreover, among the structural requirements in the following embodiments, structural requirements that are not described in the independent claims are described as arbitrary structural requirements.

In addition, each figure used for explanation is a schematic diagram and may not necessarily be a precise illustration. In addition, in each drawing, substantially the same components are assigned the same reference numerals, and repeated descriptions may be omitted or simplified.

(Embodiment 1) First, Embodiment 1 of the present disclosure will be described using FIG. 2 . FIG. 2 is a cross-sectional view showing the inkjet head 100 according to Embodiment 1 of the present disclosure.

>Inkjet head 100> FIG. 2( a ) is a cross-sectional view of the inkjet head 100 of the present disclosure, showing a cross-section taken along a plane along the arrangement direction of the plurality of nozzles 2 and the direction in which the ink is ejected. In addition, in the inkjet head 100, both ends of the plurality of nozzles 2 in the arrangement direction are cut off and omitted. The inkjet head 100 of this embodiment includes at least a nozzle plate 1 , a flow path forming substrate 4 , a piezoelectric element 5 , a vibration plate 8 , and a base 10 .

In addition, a plurality of nozzles 2 are formed on the nozzle plate 1 . The flow path forming substrate 4 is provided with a partition wall, and the pressure generating chamber 3 connected to the nozzle 2 is defined by the partition wall. The piezoelectric element 5 has a driving part 6 provided in a region corresponding to each pressure generating chamber 3 and a column part 7 provided in a region corresponding to each partition wall of the flow path forming substrate 4 .

The vibration plate 8 is provided at a position that separates the flow path forming substrate 4 and the piezoelectric element 5 . The inkjet head 100 further includes a casing (not shown) that holds the outer periphery of these components and has a flow path for supplying ink to the flow path forming substrate 4 .

In addition, FIG. 2(b) is an enlarged view of the portion where the diaphragm 8 and the piezoelectric element 5 are joined (region b shown in the figure) in FIG. 2(a) . As shown in FIG. 2(b) , the bonding material layer 9 is used to join the diaphragm 8 and the piezoelectric element 5 . The adhesive layer 9 includes beads 11 as shown in the figure.

>Nozzle plate 1 and nozzle 2> The nozzle plate 1 is a thing in which a plurality of nozzles 2 are formed on a substrate at a desired number and intervals. Examples of methods for forming the plurality of nozzles 2 on the nozzle plate 1 include laser processing, drilling, pressing, etching, electroforming, and the like. Considering the freedom of processing of the shape of the nozzle 2 and the ease of shape control, the nozzle 2 is preferably formed by laser processing.

Alternatively, a water-repellent film may be formed on the surface of the nozzle plate 1 on the side facing the object to be coated. This water-repellent film has the function of causing the ink on the surface of the nozzle plate 1 that has slightly seeped out near the nozzle 2 due to moisture expansion or the like to return to the nozzle 2 when the ink is discharged. For example, when there is residual ink seeping out near the nozzle 2, the meniscus on the surface of the ink will collapse, which will have a negative impact on the next ink discharge. Therefore, the formation of a water-repellent film is critical to maintaining stable discharge. is very effective. As a method of forming the water-repellent film, there is a method of applying an alkoxysilane solution containing fluorine to the nozzle plate 1 and then firing it, or a method of forming it by gas phase polymerization of a monomer containing fluorine. etc., but are not limited to such. In addition, the material used for the water-repellent film is not particularly limited.

The material of the nozzle plate 1 can be, for example, a thin plate of metal such as stainless steel or ceramic. Here, the nozzle plate 1 is the member of the inkjet head 100 that is closest to the workpiece to be printed (that is, the object to be coated). Therefore, when the nozzle plate 1 is made of a ceramic thin plate, if the inkjet head 100 comes into contact with the printed workpiece due to any malfunction, the nozzle plate 1 may break. Therefore, the nozzle plate 1 should be made of metal such as stainless steel. good. In addition, if there is no possibility of such a malfunction occurring during ink discharge, the nozzle plate 1 can also be made of any of the above-mentioned materials.

In addition, the number and spacing of the plurality of nozzles 2 formed on the nozzle plate 1 are determined according to the pattern shape of the electronic device, optical device, etc. to be produced. However, in order to improve the performance of the electronic device, optical device, etc., the pattern The shape tends to become more refined. Therefore, the number of nozzles 2 required for the inkjet head 100 increases and the spacing becomes smaller, so the density of the nozzles 2 must be increased. In particular, it may be required that the spacing of the nozzles 2 be very high density, for example, around 0.1 mm to 0.2 mm. In addition, the nozzle diameter is also reduced in response to the miniaturized pattern shape. For example, a very small nozzle 2 of 10 μm to 20 μm is required.

>Pressure generating chamber 3 and flow path forming substrate 4> The flow path forming substrate 4 is a member in which partition walls are provided at equal intervals in accordance with the arrangement of the nozzles. The space formed between each partition wall becomes the pressure generating chamber 3. In the pressure generating chamber 3, ink is supplied from a common flow path (not shown) arranged in the front-rear direction of the paper in Fig. 2 . The flow path forming substrate 4 can also be formed by laser processing, etching, or other techniques.

In addition, depending on the structure of the flow path forming substrate 4, it can also be manufactured by overlapping a plurality of individually processed substrates to form one flow path forming substrate 4. The nozzle plate 1 and the flow path forming substrate 4 can be joined by metal bonding, an adhesive material, or the like. When using an adhesive material, the type of the adhesive material is not particularly limited, but a thermosetting adhesive material, a two-liquid mixed adhesive material, an ultraviolet curing adhesive material, an anaerobic adhesive material, or a combination of these can be used Adhesive materials that are hardened by the effect.

The flow path forming substrate 4 can be made of metal such as stainless steel or ceramics. However, when a thermosetting adhesive material is used to join the nozzle plate 1, in order to prevent deviation or warping caused by the difference in thermal expansion coefficient, the nozzle plate 1 and the flow path are The path forming substrate 4 is preferably made of the same material. In addition, the nozzle plate 1 and the flow path forming substrate 4 are preferably made of stainless steel.

>Piezoelectric element 5> The piezoelectric element 5 is composed of a front electrode, a back electrode, an internal electrode, and a piezoelectric body. More specifically, the piezoelectric element 5 is configured by laminating a plurality of unit elements in the order of a piezoelectric body, an internal electrode connected to a front electrode, a piezoelectric body, and an internal electrode connected to a back electrode. . Therefore, the internal electrodes connected to the front electrode and the back electrode respectively form two types of comb-shaped internal electrodes that interlock with each other, and the piezoelectric body composed of lead zirconate titanate or the like is in a form in between. Lamination.

The front electrode and the back electrode are arranged on the side surfaces of a long shape composed of laminated piezoelectric layers, and the same type of internal electrodes included in each unit element are electrically connected to the two types of internal electrodes respectively. More specifically, the piezoelectric layer laminated here is a rectangular parallelepiped, and front electrodes and back electrodes are formed on the opposite sides of the rectangular parallelepiped (the front and back of the paper in FIG. 2 ).

In other words, the two types of internal electrodes are formed so that the respective layers constituting the laminated unit elements are alternately partially overlapped, and are arranged so that the two types of internal electrodes are alternately connected to the front electrode and the back electrode along the longitudinal direction.

In the piezoelectric element 5, internal electrodes connected to the front electrode and internal electrodes connected to the back electrode are alternately arranged along the longitudinal direction. Therefore, when a potential difference occurs between the front electrode and the back electrode, the piezoelectric element 5 It will expand and contract upward and downward on the paper in Figure 2 in response to the potential difference.

In addition, a plurality of channels corresponding to the arrangement of the nozzle 2 are arranged in the piezoelectric element 5 . There are grooves between each channel, but these grooves are formed by cutting processing in order to divide the plurality of channels after the piezoelectric element 5 is integrally formed. Each channel is separated and insulated by this groove. . In addition, the channel is composed of a driving part 6 and a column part 7. The driving part 6 is disposed under the pressure generating chamber 3 and is connected to a flexible cable. It is driven in response to an input signal to produce displacement of the channel. The column part 7 7 is arranged under the partition wall of the flow path forming substrate 4 and supports the flow path forming substrate 4 . In addition, the driving part 6 and the column part 7 are arranged alternately. The piezoelectric element 5 is supported by a base 10 serving as a base, and the base 10 is made of ceramics, metal, or the like.

>Vibration plate 8> The vibrating plate 8 vibrates due to the displacement generated by the driving part 6 of the piezoelectric element 5 and changes the volume inside the pressure generating chamber 3, thereby generating pressure in the ink filled inside the pressure generating chamber 3. Ink is ejected from nozzle 2.

Here, in this embodiment, the diaphragm 8 is made of resin. By forming the diaphragm 8 with a soft resin, when the diaphragm 8 is joined to the piezoelectric element 5 described below, the tops of the beads kneaded in the bonding material will slightly sink into the resin diaphragm 8 . Thereby, the adhesive material layer 9 can obtain an anchoring effect, thereby improving the bonding strength between the adhesive material layer 9 and the diaphragm 8 .

The material of the resin constituting the diaphragm 8 is not particularly limited. However, since the pressure generating chamber 3 side of the diaphragm 8 is the surface that contacts the ink, a material with high chemical resistance is preferred. Examples of such materials include polyamide, polyimide, polyamideimide, polyetherimide, polyethertriene, polyetherketone, polyetheretherketone, and fluororesin. . In particular, polyimide is widely used in electronic circuits, and products that can be easily finely processed using photolithography techniques such as coating and etching have been developed and can be suitably used for the purposes of the present disclosure. In addition, since the most suitable material of the diaphragm 8 changes depending on the solvent or functional material used in the ink, the diaphragm 8 can be formed by appropriately selecting various materials that are not limited.

In addition, the vibration plate 8 has a thickness that can vibrate due to the displacement generated by the driving part 6 of the piezoelectric element 5 and can change the volume inside the pressure generating chamber 3, thereby filling the pressure generating chamber. 3. The film thickness of the internal ink that generates pressure is not particularly limited. For example, as long as it is about 1 μm or more and 100 μm or less, the most suitable film thickness can be selected based on the softness of the resin constituting the diaphragm 8 and the ink ejection characteristics of the diaphragm 8 .

In addition, the hardness of the diaphragm 8 is such that the beads 11 described below can sink into it. For example, the diaphragm 8 can be suitably used as long as the Young's modulus is 1 GPa or more and 10 GPa or less. When the Young's modulus of the diaphragm 8 is smaller than 1 GPa, the beads 11 described later will sink into the diaphragm 8 too easily, making it difficult to control the pressing force when joining the diaphragm 8. Also, when the Young's modulus is larger than 10 GPa , the beads 11 will not be able to fully sink into the diaphragm 8 .

>Adhesive material layer 9> The bonding material layer 9 is a bonding layer having a predetermined film thickness (layer thickness) and is formed by hardening the bonding material used when bonding the piezoelectric element 5 and the diaphragm 8 . Therefore, the adhesive layer 9 is disposed between the piezoelectric element 5 and the diaphragm 8 . In addition, in this disclosure, the adhesive and the adhesive material layer 9 are described as uncured ones as the adhesive material, and those that are applied and cured with a predetermined film thickness are described as the adhesive material layer 9 .

Types of adhesive materials that can be used for the adhesive layer 9 include thermosetting adhesive materials, two-liquid mixed adhesive materials, ultraviolet curing adhesive materials, anaerobic adhesive materials, or hardening by the combined effect of these. Adhesive materials, etc. In particular, an epoxy adhesive material, which is a thermosetting adhesive material, can form a relatively high-hardness adhesive layer 9 after hardening, so that the displacement of the piezoelectric element 5 can be transmitted to the vibration plate 8 without attenuation, so it is suitable for use. Here, the adhesive layer 9 contains beads 11 as mentioned above.

>Bead 11> The beads 11 contained in the bonding material layer 9 have a higher hardness than the diaphragm 8 and are kneaded into the bonding material before hardening. As the beads 11 kneaded in the adhesive material, ceramic beads such as zirconia, alumina, and silica, glass beads, metal beads, etc. can be used. In particular, beads used as spacer beads for liquid crystal displays have high particle size accuracy and can be suitably used. An example of such beads is "HIPRESICA (manufactured by Ube Exsymo Co., Ltd.)" and the like.

The particle size of the beads 11 is determined by the thickness (film thickness 91) of the adhesive layer 9 to be formed, but for example, a particle size of several μm or more and several tens of μm or less may be used. In addition, the relationship between the film thickness 91 of the adhesive layer 9 and the particle diameter of the beads 11 is that the film thickness 91 of the adhesive layer 9 is smaller than the particle diameter of the beads 11 .

In addition, the hardness of the beads 11 is such that the beads 11 can sink into the diaphragm 8 described above. For example, beads 11 having a Young's modulus of 30 GPa or more can be suitably used. In addition, when the Young's modulus of the beads 11 is 30 GPa or less, the penetration into the diaphragm is insufficient as will be described later.

>Effect> The adhesive material in which the beads 11 are kneaded is applied to the piezoelectric element 5 or the diaphragm 8 by screen printing, flexo printing, gravure printing, or the like. In addition, when applying the adhesive material on the piezoelectric element 5 side, the adhesive material can be applied as a solid film to a flat surface, and then the piezoelectric element 5 can be pressed against the flat surface, and the adhesive material can be transferred to the contact surface. surface for coating.

Then, the piezoelectric element 5 and the vibrating plate 8 are aligned and pressed, and then by a hardening method suitable for each bonding material used, the bonding material is cured to form a connection between the piezoelectric element 5 and the vibrating plate 8 . Adhesive material layer 9 for joining panels 8 .

Here, as shown in FIG. 2( b ), when pressed, the top of the bead 11 on the diaphragm 8 side sinks into the diaphragm 8 which is softer than the bead 11 , deforming the surface and forming a recess 90 in the diaphragm 8 . , In addition, the adhesive material will also enter the recess 90 .

Here, the film thickness 91 of the adhesive layer 9 is set so as not to consider the recessed portion 90 in which the beads 11 sink. That is, the film thickness 91 is the separation distance between the opposing surfaces of the piezoelectric element 5 and the diaphragm 8 . Therefore, the film thickness 91 of the adhesive layer 9 becomes smaller than the particle diameter of the beads 11 by the portion in which the beads 11 sink.

Due to the adhesive material entering the recessed portion 90 , the hardened adhesive material layer 9 can obtain an anchoring effect, thereby improving the bonding strength to the diaphragm 8 . That is, after hardening, the applied bonding material forms: a layer between the opposing surfaces of the piezoelectric element 5 and the vibration plate 8, with a film thickness 91 used for bonding; and a layer that enters the recessed portion 90 to obtain the anchoring effect. part. Therefore, due to the above-mentioned anchoring effect, the adhesive material layer 9 already adhered to the piezoelectric element 5 can be firmly adhered to the vibration plate 8. Therefore, the joint strength of the piezoelectric element 5 and the vibration plate 8 is high and reliable. High performance inkjet head 100.

As described above, the inkjet head 100 in this embodiment includes the piezoelectric element 5; the vibration plate 8; and the bonding material layer 9, which is disposed between the piezoelectric element 5 and the vibration plate 8 and joins the piezoelectric element 5 As with the diaphragm 8 , the adhesive layer 9 contains beads 11 having a higher hardness than the diaphragm 8 , and the film thickness 91 of the adhesive layer 9 is smaller than the particle size of the beads 11 .

In the inkjet head 100 having such a structure, since the adhesive layer 9 firmly adheres to the diaphragm 8 due to the anchoring effect, peeling of the diaphragm 8 from the adhesive layer 9 can be suppressed. Therefore, the bonding strength between the piezoelectric element 5 and the diaphragm 8 on the other side to which the adhesive layer 9 is bonded becomes higher, and a highly reliable inkjet head can be realized.

Furthermore, when the diaphragm 8 is pressed by the beads 11 kneaded in the adhesive material, the diaphragm 8 , which has a lower hardness than the beads 11 (easily deformed), deforms to form a recessed portion 90 , so that the adhesive material enters the recessed portion 90 . Therefore, the adhesive material including the portion that enters the recessed portion 90 is hardened to form the adhesive material layer 9. Therefore, the diaphragm 8 does not need to be roughened, and the inkjet head 100 can be easily manufactured.

Furthermore, for example, the diaphragm 8 may be made of resin.

This allows the diaphragm 8 to be made of a resin having a lower hardness than ceramics, glass, metal, or the like that can be suitably used as the beads 11 , thereby expanding the selection possibilities of the beads 11 having a higher hardness than the diaphragm 8 .

(Embodiment 2) Next, Embodiment 2 of the present disclosure will be described using FIG. 3 . FIG. 3 shows an inkjet head 100b according to Embodiment 2 of the present disclosure.

>Inkjet head 100b> FIG. 3(a) is a cross-sectional view of the inkjet head 100b of the present disclosure, showing a cross-section in the same cross-section as FIG. 2(a).

The inkjet head 100b of this embodiment includes at least a nozzle plate 1, a flow path forming substrate 4, a piezoelectric element 5, a vibration plate 8b, and a base 10.

In addition, a plurality of nozzles 2 are formed on the nozzle plate 1 . The flow path forming substrate 4 is provided with a partition wall, and the pressure generating chamber 3 connected to the nozzle 2 is defined by the partition wall. The piezoelectric element 5 has a driving part 6 provided in a region corresponding to each pressure generating chamber 3 and a column part 7 provided in a region corresponding to each partition wall of the flow path forming substrate 4 .

The vibration plate 8 b is provided at a position that separates the flow path forming substrate 4 and the piezoelectric element 5 . The inkjet head 100 further includes a casing (not shown) that holds the outer periphery of these components and has a flow path for supplying ink to the flow path forming substrate 4 .

The above is the same structure as Embodiment 1, but this embodiment is different from Embodiment 1 in the structure of the diaphragm 8b. More specifically, the vibrating plate 8 b includes a vibrating portion 81 and a joint portion 82 corresponding to the shape of the joint with the piezoelectric element 5 and thickened in a convex shape toward the piezoelectric element 5 side than the vibrating portion 81 . Therefore, the bonding material layer 9b is disposed between the bonding portion 82 of the piezoelectric element 5 and the vibration plate 8b, and the bonding portion 82 and the piezoelectric element 5 are bonded by the bonding material layer 9b.

FIG. 3(b) is an enlarged view of the joint portion (region b2 shown in the figure) between the vibration plate 8b and the piezoelectric element 5 in FIG. 3(a). The vibration plate 8b and the piezoelectric element 5 are bonded using the bonding material layer 9b and the beads 11. In addition, as a comparative example, an enlarged view of the same portion as the area b2 of the inkjet head (that is, the same structure as in Embodiment 1) without the joint portion 82 is shown in FIG. 3(c).

In Embodiment 1, the thickness of the diaphragm 8 is, for example, about 1 μm to 100 μm. As mentioned above, when pressed, the top of the bead 11 on the diaphragm 8 side sinks into the diaphragm 8 which is softer than the bead 11 to deform the surface and form a recess 90 in the diaphragm 8 . At this time, for example, if the diaphragm 8 is relatively thin, as shown in FIG. 3(c) , the thickness of the diaphragm 8 corresponding to the sinking amount will appear as a tiny amount on the surface of the diaphragm 8 on the flow path forming substrate 4 side. Appeared through transformation 83. Therefore, the vibration characteristics of the diaphragm 8 , that is, the discharge characteristics of the inkjet head 100 may vary depending on the degree of deformation 83 of each nozzle 2 .

The above-described deformation 83 is that the thickness of the diaphragm 8 becomes smaller as the thickness of the diaphragm 8 becomes thicker, thereby suppressing uneven discharge characteristics. However, if the thickness of the diaphragm 8 is increased, the rigidity of the diaphragm 8 increases, so the piezoelectric The displacement of element 5 will become difficult to convey.

>Effect> Therefore, in this embodiment, as mentioned above, the vibration plate 8b is provided with: the vibration part 81; and the joint part 82, which corresponds to the joint position and shape with the piezoelectric element 5 and is larger than the vibration part 82 as shown in FIG. 3(b). 81 is further thickened into a convex shape toward the piezoelectric element 5 side. Thereby, deformation 83 of the surface of the diaphragm 8b on the flow path forming substrate 4 side caused by the sinking of the beads 11 can be suppressed without increasing the thickness of the vibrating portion 81.

In addition, the film thickness 92 of the adhesive layer 9b at this time is smaller than the particle size of the beads 11. In addition, as in Embodiment 1, the film thickness 92 of the adhesive layer 9b is determined by the separation distance between the opposing surfaces of the piezoelectric element 5 and the diaphragm 8b, regardless of the recess 90b in which the beads 11 sink.

In addition, it is conceivable that with the above-mentioned structure, if the pressing force when joining the piezoelectric element 5 and the vibrating plate 8 b becomes uneven, the bonding material will be excessively squashed and the width of the piezoelectric element 5 will be larger than the width of the piezoelectric element 5 . (The length of the piezoelectric element 5 in the arrangement direction of the nozzles 2) is further widened and overflows, and an overflow portion 93 is generated. In addition, it is expected that such an overflow portion 93 will be formed even if the coating amount of the adhesive material is shifted. The overflow portion 93 can be designed not to contact the vibrating portion 81 according to the height of the joint portion 82 relative to the vibrating portion 81 . Therefore, it is also possible to simultaneously obtain an effect of suppressing the vibration characteristics from being inhibited from being hindered in the operation of the vibrating portion 81 when the bonding material is hardened.

In addition, as a method of manufacturing the resin-made vibration plate 8b composed of the vibration part 81 and the joint part 82 as above, for example, a method of half-etching a resin film by photolithography, a method of using a photosensitive material such as The method is produced by laminating a pattern of polyimide photosensitive resin, and the method is produced by transferring the shape of the joint portion 82 from a mold to a resin film using a process such as imprint or embossing.

As described above, the diaphragm 8b included in the inkjet head 100b in this embodiment includes the vibrating part 81 and the joint part 82, which is thicker than the vibrating part 81 in a convex shape toward the piezoelectric element 5 side, and The bonding portion 82 and the piezoelectric element 5 are bonded via the adhesive layer 9b.

(Embodiment 3) Next, Embodiment 3 of the present disclosure will be described using FIG. 4 . FIG. 4 is a cross-sectional view showing an inkjet head 100c according to Embodiment 3 of the present disclosure.

>Inkjet head 100c> Figure 4 is an enlarged view of the area b2 in Figure 3 (that is, the same as Figure 3(b)). However, compared with Figure 3(b), in Figure 4, the piezoelectric element 5c is in contact with the vibration. The opposing joint surface of the plate 8b (the surface on the side of the diaphragm 8b) has a recessed portion 51. That is, this embodiment is different from Embodiment 2 in that the recessed portion 51 is provided (formed) on the joint surface of the piezoelectric element 5c. The recessed portion 51 has a size that allows a part of the beads 11 kneaded in the adhesive material to enter. Therefore, at least part of the beads 11 is disposed in the recessed portion 51 .

Therefore, the beads 11 included in the bonding material layer 9c include beads 11 located on the surface of the piezoelectric element 5c (the joint surface other than the recessed portion 51) and beads 12 located in the recessed portion 51. different. In addition, although it will be described later, the bead 11 located on the surface of the piezoelectric element 5c is something which sinks into the diaphragm 8b by the pressing force similarly to Embodiment 1 and Embodiment 2.

>Effect> By appropriately adjusting the shape or arrangement density of the recessed portions 51 described above, when pressing is performed to join the piezoelectric element 5c and the diaphragm 8b, the top of the bead 11 on the surface of the piezoelectric element 5c on the diaphragm 8b side The diaphragm 8 will be trapped in the joint 82 of the diaphragm 8 which is softer than the beads 11 . The sinking of the beads 11 deforms the surface of the joint portion 82 of the diaphragm 8b and forms a recessed portion 90b in the diaphragm 8b. On the other hand, the bead 12 located in the recessed portion 51 is in contact with the joint portion 82 of the diaphragm 8 at the top of the diaphragm 8b side, but does not sink. In this embodiment, the adhesive layer 9c having such a structure can be formed.

At this time, the film thickness 94 of the adhesive layer 9c is smaller than the particle size of the beads 11 located on the surface of the piezoelectric element 5c. In addition, the film thickness 94 is still small relative to the particle diameter of the beads 12 located in the recessed portion. That is, when the bead 11 sinks into the diaphragm 8b, the bead 12 becomes as if it sinks into the piezoelectric element 5c side, and the adhesive material also enters the recessed part 51.

In addition, similar to the above-described embodiment, the film thickness 94 of the adhesive layer 9c does not take into account the recessed portion 90b in which the beads 11 sink, and does not take into account the recessed portion 51. It is determined by the opposition between the piezoelectric element 5c and the vibration plate 8b. The distance between the surfaces is specified. By having the above structure, the adhesive material layer 9c sunk into the recess 90b created by the beads 11 on the surface of the piezoelectric element 5c can obtain an anchoring effect on the diaphragm 8b, thereby improving the adhesive strength. In addition, since the adhesive material layer 9c also contains the adhesive material that enters the recessed portion 51 and is hardened, an anchoring effect can also be obtained for the piezoelectric element 5c.

In addition, the presence of the beads 12 located in the recessed portion 51 makes it easier to control the film thickness 94 during pressing to join the piezoelectric element 5c and the vibration plate 8b. More specifically, the film thickness 94 is set by gradually reducing the film thickness 94 by applying a pressing force to join the piezoelectric element 5c and the diaphragm 8b. However, the film thickness 94 is set to the diaphragm 8b side of the bead 12. In the top position, the stress will vary relative to the applied pressure. That is, it can be easily confirmed by torque management or the like that the film thickness 94 has been set to the top position of the bead 12, and the control of the film thickness 94 becomes easy.

This ease of control of the film thickness 94 can prevent the bonding material from being excessively squashed by the pressing force for joining the piezoelectric element 5c and the vibrating plate 8b, thereby preventing the bonding material from widening wider than the width of the piezoelectric element 5c.

In addition, since the piezoelectric element 5c is not a material with a smooth surface like the resin constituting the diaphragm 8b, but is a sintered body of ceramic, it has an uneven structure originally, and is processed into a smooth surface by grinding the uneven structure. until it can be joined. Therefore, just by appropriately optimizing the degree of smoothing by grinding (leaving the uneven structure to remain), a smooth surface (surface) suitable for bonding can be formed on the piezoelectric element 5c, and at the same time, a depression can be formed (remaining) locally. Department 51. Therefore, in the formation of the recessed portion 51 , an additional step for forming the recessed portion 51 is not particularly necessary, and a reduction in processing time due to partial omission of grinding can also be expected.

In addition, the diaphragm 8 in FIG. 4 is illustrated as having the joint portion 82 as in FIG. 3(b) . However, in this embodiment, the piezoelectric element 5 c and the diaphragm may be joined without the joint portion 82 . composition.

As explained above, the piezoelectric element 5c included in the inkjet head 100c in this embodiment has the recessed portion 51 on the joint surface facing the vibration plate 8b, and at least a part (bead 12) of the beads 11 and 12 is arranged on in the recessed portion 51 .

Thereby, the bonding material that has entered the recessed portion 51 will harden, so the bonding material layer 9c can obtain an anchoring effect on the piezoelectric element 5c, thereby improving the bonding strength with the piezoelectric element 5c. In addition, the beads 12 that have entered the recessed portion 51 can easily control the film thickness 94 to a position that contacts the surface of the piezoelectric element 5c side of the joint portion 82 of the diaphragm 8b.

(Embodiment 4) Embodiment 4 of the present disclosure will be further described below using FIG. 5 . FIG. 5 shows an inkjet head 100d according to Embodiment 4 of the present disclosure.

>Inkjet head 100d> FIG. 5 is an enlarged view of area b2 in FIG. 3 (ie, FIG. 3(b) ), and a cross-sectional view showing the same points as in FIG. 4 . In FIG. 5 , it is not shown in FIG. 3( b ) that the beads 11 are made of a single particle size. Instead, it is shown that a thing with a particle size distribution is used, or a plurality of single particle sizes are used. When the beads 11 and the like are mixed, the diaphragm 8b and the piezoelectric element 5 are joined together.

That is, the beads used in this embodiment include at least the first beads 13 and the second beads 14 having different particle sizes. This point is different from other implementation forms described above.

The adhesive material in which the first beads 13 with the largest particle diameter among beads of a plurality of particle sizes and the second beads 14 with a smaller particle diameter than the first beads 13 are kneaded are coated in the same manner as in Figure 2(b) and so on. The material is applied to the piezoelectric element 5 and, in the case of a structure including the joint portion 82 , the material is applied to either the piezoelectric element 5 or the joint portion 82 . Then, the piezoelectric element 5 and the vibrating plate 8b are aligned and pressed. By using a hardening method suitable for each bonding material used, the bonding material is cured to join the piezoelectric element 5 and the vibrating plate 8b. Plate 8b.

In addition, the diaphragm 8b in FIG. 5 is illustrated as having the joint portion 82 as in FIG. 3(b) . However, in this embodiment, the piezoelectric element 5c may be joined without the joint portion 82. with vibrating plate.

>Effect> By appropriately adjusting the concentration (bead number concentration) of the first beads 13 and the second beads 14, when the piezoelectric element 5 is pressed to join the diaphragm 8b, the top of the first bead 13 on the diaphragm 8b side will The diaphragm 8b, which is softer than the first bead 13, is sunk into the diaphragm 8b to form a recessed portion 90b on the surface of the diaphragm 8b. On the other hand, although the top of the second bead 14 on the side of the diaphragm 8b is in contact with the diaphragm 8b, it does not sink.

That is, the relationship between the film thickness 95 of the first bead 13 , the second bead 14 , and the adhesive material layer 9 d is that the film thickness 95 of the adhesive material layer 9 d is smaller than the particle diameter of the first bead 13 , and the film thickness 95 of the first bead 13 is smaller than the particle diameter of the first bead 13 . The particle diameter is larger than the particle diameter of the second beads 14 . In this embodiment, the adhesive layer 9d having such a structure can be formed.

At this time, the film thickness 95 of the adhesive layer 9d is smaller than the particle diameter of the first beads 13. In addition, the film thickness 95 is substantially consistent with the particle diameter of the second beads 14 . That is, while the first bead 13 sinks into the diaphragm 8b, the second bead 14 is sandwiched between the surface of the piezoelectric element 5 and the surface of the joint portion 82 where the recessed portion 90b is not formed.

In addition, similar to the above-described embodiment, the film thickness 94 of the adhesive layer 9c is determined by the separation distance between the opposing surfaces of the piezoelectric element 5 and the diaphragm 8b, regardless of the recessed portion 90b in which the beads 11 sink.

The presence of the second beads 14 makes it easier to control the film thickness 95 than in the case of a single particle size. More specifically, the film thickness 95 is set by gradually reducing the film thickness 95 by applying a pressing force to join the piezoelectric element 5 and the vibration plate 8 b. However, the film thickness 95 is set to the particle size of the second beads 14 In position, the stress will change relative to the applied pressure. That is, it can be easily confirmed that the film thickness 95 has reached the particle size of the second beads 14 by torque management or the like, and the control of the film thickness 95 becomes easy.

This ease of control of the film thickness 95 can prevent the bonding material from being excessively flattened by the pressure of joining the piezoelectric element 5 and the vibrating plate 8 b and expanding to a width wider than the width of the piezoelectric element 5 for bonding and hardening. . Therefore, it is possible to suppress the problem that the adhesive material that overflows and hardens interferes with the vibration of the diaphragm 8b. In addition, the second beads 14 may further include beads with a plurality of particle sizes. That is, as long as the film thickness 95 can be determined based on the largest particle diameter among the second beads 14 and the second beads 14 are smaller than a predetermined particle diameter intended to be used as the film thickness 95 . In other words, the particle size of the second beads 14 is easier to control than that of the first beads 13 , so inexpensive beads (with rough particle size control) can also be used.

Furthermore, when the second beads 14 having a plurality of particle sizes are used as described above, the film thickness 95 can be set to match which particle size of the second beads 14 is to be set, and more can be performed by applying the pressure. stage control.

As explained above, the beads 11 included in the inkjet head 100d in this embodiment include the first beads 13 and the second beads 14 with different particle diameters. The film thickness 95 is smaller than the particle diameter of the first beads 13, and the aforementioned The particle diameter of the first beads 13 is larger than the particle diameter of the second beads 14 .

Thereby, the film thickness 95 can be easily controlled without the recessed portion 51 in the piezoelectric element 5. Therefore, the reliability of the bonding between the piezoelectric element 5 and the vibrating plate 8b can be ensured, and desired discharge can be easily achieved. Features of the inkjet head.

(Other embodiments) The embodiments have been described above, but the present disclosure is not limited to the above-mentioned embodiments.

In addition, in the above-mentioned embodiment, the structural elements constituting the inkjet head are exemplified, but the functions of the structural elements included in the inkjet head may be allocated to a plurality of parts constituting the inkjet head.

In addition, each embodiment may be obtained by subjecting each embodiment to various modifications that are imaginable by a person of ordinary skill in the technical field to which the present invention belongs, or by arbitrarily combining the configurations of each embodiment within the scope that does not deviate from the gist of the present disclosure. The forms realized by the requirements and functions are also included in this disclosure.

For example, this disclosure shows an example in which the diaphragms 8 and 8 b are made of resin. However, any material may be used to form the diaphragms as long as the material has a lower hardness than the beads 11 and 13 .

Furthermore, for example, although the diaphragm 8b is composed of the vibrating part 81 and the joint part 82, the joint part 82 may not be provided. For example, when the deformation 83 has a size (thickness) that is negligible relative to the thickness of the diaphragm, such a joint portion 82 does not need to be provided. Alternatively, a piezoelectric element having displacement characteristics capable of vibrating a diaphragm having a sufficient thickness such that deformation 83 can be ignored may be provided.

In addition, a plurality of embodiments from Embodiment 1 to Embodiment 4 can be arbitrarily combined to realize a highly reliable inkjet head. industrial availability

Since the present disclosure can provide a highly reliable inkjet head, it can form patterns of electronic devices or optical devices at low cost, which is very useful.

1:Nozzle plate 2:Nozzle 3: Pressure generating chamber 4: Flow path forming substrate 5, 5a, 5c: Piezoelectric element 6:Driving department 7: Pillar 8, 8a, 8b: Vibration plate 9, 9a, 9b, 9c, 9d: Adhering material layer 10:Abutment 11, 12: beads 13: 1st bead 14: 2nd bead 51: Depression 81:Vibration Department 82, 82a: joint 83:Transformation 90, 90b: concave part 91, 92, 94, 95: film thickness 93: Overflow Department 100, 100a, 100b, 100c, 100d: inkjet head b, b2: area

FIG. 1 is an enlarged cross-sectional view of a conventional inkjet head. FIG. 2 is a cross-sectional view of the inkjet head according to Embodiment 1. FIG. 3 is a cross-sectional view of the inkjet head according to Embodiment 2. FIG. 4 is an enlarged cross-sectional view of the inkjet head according to Embodiment 3. FIG. Fig. 5 is an enlarged cross-sectional view of the inkjet head according to the fourth embodiment.

1:Nozzle plate

2:Nozzle

3: Pressure generating chamber

4: Flow path forming substrate

5: Piezoelectric element

6:Driving department

7: Pillar

8:Vibration plate

9: Adhere to the material layer

10:Abutment

11: beads

90: concave part

91:Film thickness

b: area

Claims (4)

An inkjet head includes: a piezoelectric element; a vibration plate; and a bonding material layer disposed between the piezoelectric element and the vibration plate, and joining the piezoelectric element and the vibration plate, and the bonding material layer contains Beads having a higher hardness than the diaphragm, and a film thickness of the adhesive layer smaller than a particle diameter of the first bead included in the beads, and the piezoelectric element has a recessed portion on a joint surface facing the diaphragm. , a portion of the first bead exceeding the film thickness is accommodated in the recessed portion. The inkjet head of claim 1, wherein the vibration plate is made of resin. The inkjet head according to claim 1 or 2, wherein the vibration plate is provided with: a vibration part; and a joint part that is thicker and convex than the vibration part toward the piezoelectric element side, and is joined by the adhesive material layer The aforementioned joint portion and the aforementioned piezoelectric element. The inkjet head of claim 1 or 2, wherein the beads further include second beads smaller in diameter than the first beads.

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