TW202023841A - Inkjet head with high reliability - Google Patents

Abstract

To provide an inkjet head with high reliability. An inkjet head includes: a piezoelectric element; a vibrating plate; and an adhesive layer allocated between the piezoelectric element and the vibrating plate, and bonding the piezoelectric element and the vibrating plate. Also, the adhesive layer contains beads with hardness greater than that of the vibrating plate, and the film thickness of the adhesive layer is smaller than the particle size of the beads.

Description

Inkjet head

Invention field The present disclosure relates to an inkjet head.

Background of the invention In the manufacturing steps of electronic devices or optical devices, most of the steps use printing to form a fine pattern on a substrate. In the printing of fine patterns, it is necessary to reduce the size and density of a series of flow paths, piezoelectric elements, and vibrating plates related to the discharge of the material that has been printed. In addition, a technique for miniaturizing and increasing the density of piezoelectric elements has been disclosed (for example, refer to Patent Document 1).

Patent Document 1 discloses a liquid ejection head, which narrows the width of the adhesion layer next to the conductive layer in the lead-out wiring used to drive the piezoelectric element, so that even if the piezoelectric elements are arranged in a high density, Suppress the short circuit between adjacent lead wires. Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2018-027711 Patent Document 2: Japanese Patent Laid-Open No. 10-34919

Summary of the invention Problems to be solved by the invention However, in the ejection of ink using an inkjet head, the vibration plate and the piezoelectric element must be surely joined. For example, when the reliability of such bonding is low, the vibration plate may peel off from the piezoelectric element, and the design ink discharge accuracy may not be maintained.

Therefore, the purpose of the present disclosure is to provide an inkjet head with high reliability. Means to solve the problem

One aspect of the inkjet head in the present disclosure includes: a piezoelectric element; a vibrating plate; and an adhesive layer, which is disposed between the piezoelectric element and the vibrating plate, and joins the piezoelectric element and the vibrating plate, and The adhesive material layer contains beads having a higher hardness than the vibration plate, 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, an inkjet head with high reliability can be provided.

The form used to implement the invention [Knowledge and insights that become the basis of disclosure] As a method of forming fine patterns at low cost, a printing method in which a material of a desired pattern is inked and then printed on a substrate, and an inkjet method that 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 with this, the area of the joint portion of each member constituting the inkjet head has also become smaller.

As a result, the bonding strength of the bonding portion of each member is easily reduced. Among them, in an inkjet head using a piezoelectric element, the bonding portion between the piezoelectric element and the vibrating plate will cooperate with the drive of the piezoelectric element to achieve high speed. To vibrate, the piezoelectric element is driven to generate pressure in the ink chamber, and the vibrating plate transmits the driven displacement to the ink chamber as vibration. Therefore, in the junction between the piezoelectric element and the vibrating plate, there is a problem in particular that the bonding strength is reduced, and the piezoelectric element and the vibrating plate are likely to be peeled off, resulting in low reliability.

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

In Patent Document 2, as shown in FIG. 1, a technique for roughening the bonding surface of the bonding portion 82a of the vibration plate 8a and the piezoelectric element 5a has been disclosed. In this technique, by roughening the surface of the joining portion 82a, the adhesive material enters the roughened surface (joining surface) and hardens to form the adhesive material layer 9a. Therefore, the anchoring effect can be obtained. To improve the bonding strength. However, since the roughening step is performed after forming the vibrating plate 8a using a chemical or electrical chemical treatment, it is very complicated. In addition, since the vibrating plate 8a is an extremely thin member of several μm to several tens of μm, the process margin of the roughening treatment amount becomes narrow, and it is very difficult to control the process. That is, if there is unevenness in the manufacturing process, the bonding surface of the bonding portion 82a and the piezoelectric element 5a will be too rough, resulting in the film thickness becoming too thin, pinholes may be generated, or insufficient roughening may not be sufficient. The issue of bonding strength.

The present disclosure is to solve the above-mentioned problems in the conventional technology, and its purpose is to improve the bonding strength between the diaphragm and the piezoelectric element at low cost without requiring additional steps such as roughening steps, and to provide an inkjet head with high reliability.

In order to achieve the above object, the inkjet head in one aspect of the present disclosure includes: a piezoelectric element; a vibrating plate; and an adhesive layer, which is arranged between the piezoelectric element and the vibrating plate, and joins the piezoelectric element and the vibrating plate Also, the adhesive layer contains beads with higher hardness than the vibration plate, and the film thickness of the adhesive layer is smaller than the particle diameter of the beads.

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

In addition, each figure used for description is a schematic diagram, and it is not necessarily a figure shown strictly. In addition, in each figure, the same reference numerals are given to substantially the same configuration, and the repeated description may be omitted or simplified.

(Embodiment 1) First, using FIG. 2, the first embodiment in the present disclosure will be described. Fig. 2 is a cross-sectional view showing the ink jet 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 cut along a surface along the arrangement direction of a plurality of nozzles 2 and in the direction of ink ejection. In addition, in the inkjet head 100, both ends in the arrangement direction of the plurality of nozzles 2 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 has a partition wall, and the pressure generating chamber 3 communicating with the nozzle 2 is defined by the partition wall. The piezoelectric element 5 has a driving portion 6 provided in a region corresponding to each pressure generating chamber 3 and a column portion 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 separating the flow path forming substrate 4 and the piezoelectric element 5. The inkjet head 100 is further provided with a casing (not shown), which holds the outer periphery of these members, and has a flow path for supplying ink to the flow path forming substrate 4.

In addition, an enlarged view of the part (region b shown in the figure) where the vibrating plate 8 and the piezoelectric element 5 are joined in FIG. 2(a) is shown in FIG. 2(b). As shown in FIG. 2(b), the bonding material layer 9 is used for bonding the vibration plate 8 and the piezoelectric element 5. The adhesive layer 9 contains beads 11 as shown in the figure.

>Nozzle plate 1 and nozzle 2> The nozzle plate 1 is formed by forming a plurality of nozzles 2 on a substrate in a desired number and spacing. As a method of forming a plurality of nozzles 2 on the nozzle plate 1, there are laser processing, drilling processing, pressing processing, etching method, electroforming method, 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.

In addition, 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 kind of water-repellent film has the effect of returning the ink that slightly oozes out of the vicinity of the nozzle 2 in the surface of the nozzle plate 1 due to wetting and spreading, etc., back into the nozzle 2 when the ink is discharged. For example, when the ink that has leaked near the nozzle 2 remains, the meniscus on the ink surface will collapse, which will adversely affect the next ink discharge. Therefore, the formation of a water-repellent film will help maintain stable discharge. It is very effective. As a method of forming a water-repellent film, there is a method of applying a fluorine-containing alkoxysilane solution to the nozzle plate 1 and firing it to form it, or a method of forming it by gas phase polymerization of a fluorine-containing monomer Etc., but not limited to them. In addition, the material used for the water-repellent film is not particularly limited.

As the material of the nozzle plate 1, for example, a metal or ceramic thin plate such as stainless steel can be used. Here, the nozzle plate 1 is the member closest to the side of the workpiece to be printed (that is, the object to be coated) in the inkjet head 100. Therefore, when the nozzle plate 1 is made of a ceramic thin plate, if the inkjet head 100 contacts the printed workpiece due to any failure, the nozzle plate 1 may be broken. 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 failure during ink ejection, the nozzle plate 1 can also be constructed using any of the above-mentioned materials.

In addition, although the number and interval 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, the pattern is used to improve the performance of the electronic device, optical device, etc. The shape tends to be refined. Therefore, the number of nozzles 2 required by the inkjet head 100 increases and the interval becomes smaller, so that the nozzles 2 must be denser. In particular, it may be required that the interval between the nozzles 2 be a very high density of, for example, 0.1 mm to 0.2 mm. In addition, the nozzle diameter is also reduced in accordance with 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 provided on the substrate at equal intervals in response to the partition walls of the nozzle arrangement. The space formed between each partition wall and the partition wall becomes a pressure generating chamber 3, and the pressure generating chamber 3 is supplied with ink from a common flow path (not shown) arranged in the front and back direction of the paper in FIG. 2. The flow path forming substrate 4 can also be formed by methods such as laser processing and etching.

Moreover, depending on the structure of the flow path forming substrate 4, it can also be manufactured by a method of forming a single flow path forming substrate 4 by stacking a plurality of individually processed substrates. The nozzle plate 1 and the flow path forming substrate 4 can be joined by metal joining, adhesive material, or the like. When an adhesive material is used, the type of adhesive material is not particularly limited, but a thermosetting adhesive material, a 2-component hybrid adhesive material, an ultraviolet curing adhesive material, an anaerobic adhesive material, or a combination of these can be used Adhesive materials that harden by the effect.

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

>Piezo 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 composed of a plurality of unit elements stacked in the order of a piezoelectric body, an internal electrode connected to the front electrode, a piezoelectric body, and an internal electrode connected to the back electrode. . Therefore, the internal electrodes respectively connected to the front electrode and the back electrode will form two kinds of comb-shaped internal electrodes that are interlocking with each other, and the piezoelectric body composed of lead zirconate titanate will be in a form in between. Buildup.

The front electrode and the back electrode are arranged on the side surface of the elongated shape formed by the laminated piezoelectric body layer, and respectively electrically connect the same type of internal electrodes included in each unit element to the two types of internal electrodes. More specifically, the laminated piezoelectric layer is a rectangular parallelepiped, and among the sides of the rectangular parallelepiped, a front electrode and a back electrode are formed on the surfaces opposite to each other (the front and back of the paper in FIG. 2).

In other words, the two types of internal electrodes are formed such that the layers constituting the unit elements of the build-up layer overlap each other partially, and are arranged such 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, the internal electrodes connected to the front electrode and the 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 upwards and downwards on the paper in Figure 2 according to its potential difference.

In addition, a plurality of channels corresponding to the arrangement of the nozzle 2 are arranged in the piezoelectric element 5 in a row. There are grooves between each channel, but this kind of groove is formed by cutting the plurality of channels after integrally forming the piezoelectric element 5, and the channels are separated and insulated by the groove. . In addition, the channel is composed of a driving part 6 and a pillar part 7. The driving part 6 is arranged under the pressure generating chamber 3 and is connected to a flexible cable. It is driven in response to an input signal to generate displacement of the channel. 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 alternately arranged. The piezoelectric element 5 is supported by a base 10 serving as a base, and the base 10 is made of ceramic, metal, or the like.

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

Here, in this embodiment, the diaphragm 8 is made of resin. By forming the vibrating plate 8 with a soft resin, when the vibrating plate 8 is joined to the piezoelectric element 5 described later, the top of the beads that have been kneaded in the adhesive material slightly sink into the vibrating plate 8 made of resin. Thereby, the bonding material layer 9 can obtain an anchoring effect, and the bonding strength between the bonding material layer 9 and the vibration plate 8 can be improved.

Although the material of the resin constituting the vibration plate 8 is not particularly limited, since the pressure generating chamber 3 side of the vibration plate 8 is the surface that contacts the ink, it is preferably a material with high chemical resistance. For example, as such a material, polyamide, polyimide, polyimide, polyetherimide, polyether ketone, polyether ketone, polyether ether ketone, and fluororesin can be exemplified. . In particular, polyimide is widely used for electronic circuit applications, and products that can be easily microfabricated using photoetching techniques such as coating or etching have also been developed and can be suitably used for the purposes of the present disclosure. In addition, since the most suitable material of the vibration plate 8 will vary depending on the solvent or functional material used in the ink, various materials that are not limited can be appropriately selected to form the vibration plate 8.

In addition, in terms of the thickness of the vibrating plate 8, as long as it can be vibrated by the displacement generated by the driving portion 6 of the piezoelectric element 5, and the volume inside the pressure generating chamber 3 can be changed, thereby filling the pressure generating chamber 3 There is no particular limitation on the film thickness of the internal ink generating pressure. 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 from the softness of the resin constituting the diaphragm 8 and the ink discharge characteristics of the diaphragm 8.

In addition, the hardness of the vibration plate 8 is the hardness at which the beads 11 described later can sink. For example, any vibration plate 8 having a Young's modulus of 1 GPa or more and 10 GPa or less can be suitably used. When the Young's modulus of the vibrating plate 8 is smaller than 1 GPa, the beads 11 described later will fall into the vibrating plate 8 too easily, which makes it difficult to control the pressing force when the vibrating plate 8 is joined. In addition, when it is larger than 10 GPa At this time, the beads 11 cannot sufficiently sink into the vibration plate 8.

>Adhesive layer 9> The bonding material layer 9 is a bonding layer having a predetermined film thickness (layer thickness), and is formed by curing the bonding material used when bonding the piezoelectric element 5 and the vibration plate 8. Therefore, the adhesive layer 9 is arranged between the piezoelectric element 5 and the vibration plate 8. In addition, in the present disclosure, the term "adhesive agent and adhesive material layer 9" refers to an uncured material as an adhesive material, and a material coated and cured to a predetermined film thickness as an adhesive material layer 9.

As the types of adhesives that can be used for the adhesive layer 9, thermosetting adhesives, two-component hybrid adhesives, ultraviolet curing adhesives, anaerobic adhesives, or curing by a combination of these can be used The adhesive material and so on. In particular, a thermosetting adhesive material, namely an epoxy adhesive material, can form a relatively high-hardness adhesive material layer 9 after hardening. Therefore, the displacement of the piezoelectric element 5 can be transmitted to the vibration plate 8 without attenuation, which is suitable for use. Here, the adhesive layer 9 contains beads 11 as described above.

>Beads 11> The beads 11 contained in the adhesive material layer 9 are beads having a higher hardness than the vibration plate 8 and are kneaded in the adhesive material before hardening for use. As the beads 11 kneaded in the adhesive material, ceramic beads such as zirconia, alumina, and silica, glass beads, metal beads, or the like can be used. In particular, beads used as spacer beads for liquid crystal displays have high particle size accuracy and can be suitably used. As an example of such beads, "HIPRESICA (Ube Exsymo (stock) system)" and the like can be cited.

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 substance of several μm or more and several tens of μm or less can 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 the hardness that can sink into the aforementioned vibration plate 8. For example, any 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 bead 11 is 30 GPa or less, it is insufficient to sink the diaphragm as described later.

>Effects> The adhesive material kneaded with the beads 11 is applied to the piezoelectric element 5 or the vibration plate 8 by screen printing, flexo printing, gravure printing, or the like. Moreover, when the adhesive material is applied to the side of the piezoelectric element 5, the adhesive material may be applied as a solid film to a plane, and then the piezoelectric element 5 is pressed to the plane, and the adhesive material is transferred to the abutting The surface is coated by this.

Then, the piezoelectric element 5 and the vibrating plate 8 are aligned, and after pressing, the adhesive material will be cured by a hardening method suitable for each adhesive material used to form the piezoelectric element 5 and the vibration plate. Adhesive material layer 9 to which plates 8 are joined.

Here, as shown in FIG. 2(b), when pressed, the top of the bead 11 on the side of the vibrating plate 8 sinks into the vibrating plate 8 softer than the bead 11 to deform the surface, and a recess 90 is formed in the vibrating plate 8 In addition, the adhesive material will enter the recess 90.

Here, the film thickness 91 of the adhesive layer 9 is made so as not to consider the recess 90 into which the bead 11 sinks. That is, the film thickness 91 is the distance separating the facing surfaces of the piezoelectric element 5 and the vibration plate 8 from each other. Therefore, the film thickness 91 of the adhesive layer 9 becomes smaller than the particle size of the beads 11 by the portion where the beads 11 sink.

With the adhesive material that has entered the recess 90, the cured adhesive material layer 9 can obtain an anchoring effect, and the adhesive strength to the vibration plate 8 can be improved. That is, after the coated adhesive material is cured, the layer between the facing surfaces of the piezoelectric element 5 and the vibrating plate 8 has a film thickness of 91 used for bonding; and a layer that enters the recess 90 to obtain an anchoring effect section. Therefore, by the above-mentioned anchoring effect, the adhesive layer 9 that has been bonded to the piezoelectric element 5 can be firmly bonded to the vibrating plate 8. Therefore, the bonding strength between the piezoelectric element 5 and the vibrating plate 8 is high, and reliability can be achieved. High performance inkjet head 100.

As described above, the inkjet head 100 in this embodiment includes: the piezoelectric element 5; the vibrating plate 8; and the adhesive layer 9, which is arranged between the piezoelectric element 5 and the vibrating plate 8, and the piezoelectric element 5 is bonded. In contrast to the vibration plate 8, the adhesive layer 9 contains beads 11 having a higher hardness than the vibration plate 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 configuration, since the adhesive layer 9 is firmly attached to the diaphragm 8 by the anchoring effect, the vibration plate 8 can be prevented from peeling from the adhesive layer 9. Therefore, the bonding strength between the piezoelectric element 5 and the vibration plate 8 on the other side to which the adhesive layer 9 is bonded becomes high, and a highly reliable inkjet head can be realized.

In addition, when the vibrating plate 8 is pressed by the beads 11 kneaded in the adhesive material, the vibrating plate 8 having a lower hardness (easy to deform) than the beads 11 is deformed to form a recess 90, and the adhesive material enters the recess 90. Therefore, the adhesive material is hardened to form the adhesive material layer 9 including the part that has entered the recessed portion 90. Therefore, the vibration plate 8 does not need to be roughened, and the inkjet head 100 can be easily manufactured.

Moreover, for example, the vibration plate 8 may be made of resin.

Thereby, the vibration plate 8 made of resin having a hardness lower than that of ceramic, glass, metal, or the like that can be suitably used as the bead 11 can be constructed, and the selection possibilities of the beads 11 having a higher hardness than the vibration plate 8 can be expanded.

(Embodiment 2) Next, the second embodiment in this disclosure will be described using FIG. 3. Fig. 3 shows an ink jet 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 has a partition wall, and the pressure generating chamber 3 communicating with the nozzle 2 is defined by the partition wall. The piezoelectric element 5 has a driving portion 6 provided in a region corresponding to each pressure generating chamber 3 and a column portion 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 separating the flow path forming substrate 4 and the piezoelectric element 5. The inkjet head 100 is further provided with a casing (not shown), which holds the outer periphery of these members, and has a flow path for supplying ink to the flow path forming substrate 4.

The above is the same configuration as the first embodiment, but this embodiment is different from the first embodiment in the configuration of the diaphragm 8b. More specifically, the vibrating plate 8 b includes a vibrating portion 81 and a bonding portion 82 that corresponds to the bonding shape with the piezoelectric element 5 and is thicker and convex toward the piezoelectric element 5 than the vibrating portion 81. Therefore, the adhesive material layer 9b is arranged between the junction 82 of the piezoelectric element 5 and the vibration plate 8b, and the junction 82 and the piezoelectric element 5 are joined by the adhesive material layer 9b.

The enlarged view of the junction between the vibrating plate 8b and the piezoelectric element 5 in Fig. 3(a) (the area b2 shown in the figure) is Fig. 3(b). The vibrating plate 8b and the piezoelectric element 5 are joined using the adhesive layer 9b and the beads 11. In addition, as a comparative example, an enlarged view of the same part as the area b2 of the inkjet head (that is, the same configuration as in Embodiment 1) when there is no joint portion 82 is shown in FIG. 3(c).

In Embodiment 1, the thickness of diaphragm 8 is, for example, about 1 μm to 100 μm. As described above, when pressing, the top of the bead 11 on the vibrating plate 8 side is plunged into the vibrating plate 8 which is softer than the bead 11 to deform the surface, and a recess 90 is formed in the vibrating plate 8. At this time, for example, if the vibrating plate 8 is relatively thin, as shown in FIG. 3(c), the thickness of the vibrating plate 8 corresponding to the sinking amount will be small on the surface of the vibrating plate 8 on the side of the substrate 4 where the flow path is formed. Deformed 83 to appear. Therefore, the vibration characteristics of the vibration plate 8, that is, the discharge characteristics of the inkjet head 100 may vary depending on the degree of deformation 83 of each nozzle 2.

Although the above-mentioned deformation 83 is that the thicker the thickness of the vibrating plate 8 is, the smaller it becomes, and the unevenness of the discharge characteristics can be suppressed. However, if the thickness of the vibrating plate 8 is increased, the rigidity of the vibrating plate 8 will increase. The displacement of element 5 can become difficult to communicate.

>Effects> Therefore, in this embodiment, as described above, the vibrating plate 8b is provided with a vibrating portion 81; and a bonding portion 82 as shown in FIG. 3(b), corresponding to the bonding position and shape of the piezoelectric element 5, and more than the vibrating portion 81 is thicker and convex toward the piezoelectric element 5 side. Thereby, without increasing the thickness of the vibrating portion 81, it is possible to suppress the deformation 83 of the surface of the vibrating plate 8b on the side of the flow path forming substrate 4 caused by the sinking of the beads 11.

In addition, the film thickness 92 of the adhesive layer 9b at this time is smaller than the particle diameter of the beads 11. In addition, as in the first embodiment, the film thickness 92 of the adhesive layer 9b does not consider the recess 90b into which the bead 11 enters, and is defined by the distance between the opposing surfaces of the piezoelectric element 5 and the vibrating plate 8b.

In addition, it is conceivable that with the above-mentioned configuration, when the pressing force of the piezoelectric element 5 and the vibrating plate 8b is uneven, the adhesive material will be excessively crushed and will be wider than the width of the piezoelectric element 5. (The length of the piezoelectric element 5 in the arrangement direction of the nozzles 2) becomes wider and overflows, and an overflow portion 93 is generated. Moreover, even if it is a deviation of the coating amount of the adhesive material, etc., such an overflow portion 93 is expected to be formed. The overflow portion 93 may be designed not to contact the vibration portion 81 according to the height of the joint portion 82 relative to the vibration portion 81. Therefore, it is also possible to simultaneously obtain an effect of suppressing unevenness in the vibration characteristics due to hindering the operation of the vibrating portion 81 when the adhesive material is cured.

In addition, as a method of manufacturing the resin vibration plate 8b composed of the vibrating part 81 and the bonding part 82 as described above, for example, a method of half-etching a resin film by photoetching, such as photosensitive A method of making a pattern of polyimide photosensitive resin by layering, and a method of making the shape of the junction 82 from a mold to a resin film by a method such as imprinting or embossing.

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

(Embodiment 3) Next, the third embodiment in this 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)), but compared to Figure 3(b), in Figure 4, the piezoelectric element 5c is The facing joint surface of the plate 8b (the surface on the side of the vibration plate 8b) has a recess 51. That is, the present embodiment is different from the second embodiment in that the bonding surface of the piezoelectric element 5c has (formed) the recess 51. Such a recess 51 has a size that allows a part of the beads 11 kneaded in the adhesive material to enter. Therefore, at least a part of the beads 11 is arranged in the recess 51.

Therefore, there is a point that the beads 11 included in the adhesive layer 9c have the beads 11 located on the surface of the piezoelectric element 5c (except the recessed portion 51 in the bonding surface) and the beads 12 located on the recessed portion 51. different. In addition, although described later, the bead 11 located on the surface of the piezoelectric element 5c is a thing that sinks into the vibrating plate 8b by pressing force similarly to the first and second embodiments.

>Effects> By appropriately adjusting the shape or arrangement density of the recesses 51 described above, when the piezoelectric element 5c and the vibration plate 8b are pressed together, the top of the bead 11 on the surface of the piezoelectric element 5c on the side of the vibration plate 8b It will sink into the joint 82 of the vibration plate 8 which is softer than the bead 11. The intrusion of the beads 11 deforms the surface of the joint 82 of the vibration plate 8b, and forms a recess 90b in the vibration plate 8b. On the other hand, although the bead 12 located in the recessed part 51 contacts the junction part 82 of the vibration plate 8 at the top of the vibration plate 8b side, it does not sink. In this embodiment, the adhesive layer 9c of 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. Moreover, even with respect to the particle diameter of the beads 12 located in the depressed portion, the film thickness 94 is still small. That is, when the bead 11 is trapped in the vibration plate 8b, the bead 12 is in a form as if trapped in the side of the piezoelectric element 5c, and the adhesive material also enters the recessed portion 51.

In addition, similar to the above-mentioned embodiment, the film thickness 94 of the adhesive layer 9c does not take into account the recess 90b into which the beads 11 enter, and the recess 51 is not taken into consideration. It is determined by the opposing direction of the piezoelectric element 5c and the vibration plate 8b. The separation distance between the faces is specified. With the above-mentioned configuration, the adhesive layer 9c trapped in the concave portion 90b formed by the bead 11 located on the surface of the piezoelectric element 5c can obtain an anchoring effect on the vibration plate 8b, and the adhesive strength can be improved. In addition, since the adhesive material layer 9c also includes the adhesive material that enters the recess 51 and is hardened, it is also possible to obtain an anchoring effect on the piezoelectric element 5c.

In addition, the presence of the beads 12 in the recessed portion 51 facilitates the control of the film thickness 94 during pressing to join the piezoelectric element 5c and the vibration plate 8b. In more detail, although the film thickness 94 is gradually reduced by applying a pressing force that joins the piezoelectric element 5c and the vibrating plate 8b, the film thickness 94 is set to be on the vibrating plate 8b side of the bead 12 In the top position, the stress relative to the applied pressure will change. That is, it can be easily confirmed that the setting of the film thickness 94 has reached the position of the top of the bead 12 by torque management, etc., and the control of the film thickness 94 becomes easy.

The ease of control of the film thickness 94 can suppress the disadvantage that the adhesive material is excessively crushed by the pressing force of the bonded piezoelectric element 5c and the vibrating plate 8b and expands to be 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 vibrating plate 8b, but a sintered body of ceramics, it originally has an uneven structure and is processed to be smooth by grinding the uneven structure. Can be joined. Therefore, just by optimizing the degree of smoothing by grinding (leaving the uneven structure), it is possible to form a smooth surface (surface) suitable for bonding on the piezoelectric element 5c, and at the same time form (remain) depressions locally部51. Therefore, in the formation of the depressed portion 51, an additional step for forming the depressed portion 51 is not particularly required, and it is also expected that the processing time will be reduced due to the partial omission of grinding.

In addition, the vibrating plate 8 of FIG. 4 is the same as that of FIG. 3(b), although the case where the bonding portion 82 is depicted, the present embodiment may also bond the piezoelectric element 5c and the vibrating plate without the bonding portion 82 The composition.

As described above, the piezoelectric element 5c included in the inkjet head 100c in this embodiment has a recess 51 on the bonding surface facing the vibration plate 8b, and at least a part of the beads 11 and 12 (beads 12) are arranged in In the recess 51.

As a result, the adhesive material that has entered the recessed portion 51 is hardened, so that the adhesive material layer 9c can obtain an anchoring effect on the piezoelectric element 5c, and the adhesive strength with the piezoelectric element 5c can be improved. In addition, the beads 12 that have entered the recessed portion 51 can easily control the film thickness 94 at the position on the piezoelectric element 5c side surface of the junction 82 of the vibration plate 8b.

(Embodiment 4) Hereinafter, FIG. 5 is further used to describe Embodiment 4 in this disclosure. Fig. 5 shows an ink jet head 100d according to Embodiment 4 of the present disclosure.

>Inkjet head 100d> FIG. 5 is an enlarged view of the region b2 in FIG. 3 (that is, FIG. 3(b)), and a cross-sectional view showing the same points as FIG. 4. In Fig. 5, it is not the composition made of beads 11 having a single particle size as shown in Fig. 3(b), but it shows that a particle size distribution is used, or multiple single particle sizes are used. In the case of a mixture of the beads 11 and the like, the vibrating plate 8b and the piezoelectric element 5 are joined.

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

The adhesive material that kneaded the first bead 13 with the largest particle size among the beads with a plurality of particle sizes and the second bead 14 with a smaller particle size than the first bead 13 is coated in the same manner as in Fig. 2(b). It is applied to the piezoelectric element 5, and in a configuration including the bonding portion 82, it is applied to either the piezoelectric element 5 or the bonding portion 82. Then, the piezoelectric element 5 and the vibrating plate 8b are aligned, and after pressing, the adhesive material will be cured by a hardening method suitable for each bonding material used to bond the piezoelectric element 5 and the vibration plate.板8b.

In addition, the vibrating plate 8b in FIG. 5 is the same as that in FIG. 3(b), although it is depicted with the bonding portion 82, the present embodiment may also be used for bonding the piezoelectric element 5c without the bonding portion 82. Composition with vibration plate.

>Effects> By appropriately adjusting the concentration (bead number concentration) of the first beads 13 and the second beads 14, when the piezoelectric element 5 and the vibrating plate 8b are pressed together, the top of the first bead 13 on the vibrating plate 8b side It sinks into the vibration plate 8b which is softer than the 1st bead 13, and the recessed part 90b is formed in the surface of the vibration plate 8b. On the other hand, the second bead 14 is in contact with the diaphragm 8b at the top on the side of the diaphragm 8b, but it does not sink.

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

At this time, the film thickness 95 of the adhesive layer 9d is smaller than the particle size of the first beads 13. In addition, the film thickness 95 is approximately the same with respect to the particle diameter of the second beads 14. That is, while the first beads 13 sink into the vibrating plate 8b, the second beads 14 are sandwiched between the surface of the piezoelectric element 5 and the surface of the junction 82 where the recess 90b is not formed.

In addition, as in the above-mentioned embodiment, the film thickness 94 of the adhesive layer 9c does not consider the recess 90b into which the bead 11 enters, and is defined by the distance between the opposing surfaces of the piezoelectric element 5 and the vibrating plate 8b.

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

The ease of control of the film thickness 95 can prevent the bonding material from being excessively crushed by the pressure of the bonded piezoelectric element 5 and the vibrating plate 8b, and expanding to be wider than the width of the piezoelectric element 5 for bonding and hardening. . Therefore, it is possible to suppress the problem that the overflowing and hardened adhesive material hinders the vibration of the diaphragm 8b. In addition, the second beads 14 may further include beads of a plurality of particle sizes. That is, as long as the film thickness 95 can be determined by the largest particle diameter among the second beads 14, and the second beads 14 have a particle diameter less than the predetermined particle diameter to be used as the film thickness 95. In other words, compared with the first beads 13, the particle size of the second beads 14 is easier to manage, and therefore inexpensive (rough particle size management) beads can also be used.

In addition, when using the second beads 14 having a plurality of particle sizes as described above, it is possible to set the film thickness 95 consistent with which particle size of the second beads 14 by applying pressure. Stage control.

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

Thereby, when the piezoelectric element 5 does not have the recessed portion 51, the film thickness 95 can be easily controlled. Therefore, the bonding reliability of the piezoelectric element 5 and the vibration plate 8b can be ensured, and the desired discharge can be easily realized. Characteristic inkjet head.

(Other embodiments) Above, the embodiment has been described, but the present disclosure is not limited to the above embodiment.

In addition, in the above-mentioned embodiment, the constituent elements constituting the inkjet head have been exemplified, but each function of the constituent elements of the inkjet head may be distributed to a plurality of parts constituting the inkjet head.

In addition, various modifications that can be imagined by those skilled in the art to which the present invention pertains are applied to each embodiment, or by arbitrarily combining the configurations of each embodiment within the scope not departing from the gist of the present disclosure The forms realized by the requirements and functions are also included in this disclosure.

For example, in this disclosure, an example in which the vibration plates 8 and 8b are composed of resin is shown. However, any material may be used to form the vibration plates as long as it is a material with a hardness lower than that of the beads 11 and 13.

Also, for example, although the vibration plate 8b is composed of the vibrating portion 81 and the joining portion 82, the joining portion 82 may not be provided. For example, when the deformation 83 has a size (thickness) that is negligible with respect to the thickness of the vibration plate, such a joint 82 may not be provided. Alternatively, it is also possible to provide a piezoelectric element having a displacement characteristic that is capable of vibrating a vibrating plate having a sufficient thickness such that the deformation 83 can be ignored.

In addition, it is also possible to arbitrarily combine a plurality of forms among Embodiments 1 to 4 to realize an inkjet head with high reliability. Industrial availability

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

1: Nozzle plate 2: nozzle 3: Pressure generating chamber 4: Flow path forming substrate 5, 5a, 5c: piezoelectric element 6: Drive 7: Column 8, 8a, 8b: vibration plate 9, 9a, 9b, 9c, 9d: Adhesive layer 10: Abutment 11, 12: beads 13: Bead 1 14: 2nd bead 51: Depressed part 81: Vibration Department 82, 82a: Joint 83: Deformation 90, 90b: recess 91, 92, 94, 95: film thickness 93: Overflow 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 ink jet head of the first embodiment. Fig. 3 is a cross-sectional view of the ink jet head of the second embodiment. Fig. 4 is an enlarged cross-sectional view of the ink jet head of the third embodiment. Fig. 5 is an enlarged cross-sectional view of the ink jet head of the fourth embodiment.

1: Nozzle plate

2: nozzle

3: Pressure generating chamber

4: Flow path forming substrate

5: Piezoelectric element

6: Drive

7: Column

8: Vibration plate

9: Adhesive layer

10: Abutment

11: beads

90: recess

91: film thickness

b: area

Claims (5)

An inkjet head with: Piezoelectric element Vibrating plate; and The next material layer is arranged between the piezoelectric element and the vibrating plate, and joins the piezoelectric element and the vibrating plate, In addition, the adhesive material layer contains beads having a higher hardness than the vibration plate, and the film thickness of the adhesive material layer is smaller than the particle diameter of the beads. The inkjet head of claim 1, wherein the aforementioned vibration plate is made of resin. Such as the inkjet head of claim 1 or 2, wherein the aforementioned vibration plate has: Vibration department; and The junction part is thicker and convex toward the piezoelectric element side than the vibration part, In addition, the bonding portion and the piezoelectric element are bonded by the adhesive layer. An inkjet head according to any one of claims 1 to 3, wherein the piezoelectric element has a recessed portion on the joint surface facing the vibrating plate, At least a part of the beads is arranged in the recessed portion. The inkjet head according to any one of claims 1 to 3, wherein the aforementioned beads comprise a first bead and a second bead with different particle diameters, The film thickness is smaller than the particle size of the first beads, and the particle size of the first beads is larger than the particle size of the second beads.

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