JP2019136961A - Inkjet head and method for manufacturing the same - Google Patents

Abstract

To provide an inkjet head that can discharge ink from each nozzle always at the same speed and with the same volume, and to provide a method for manufacturing the same.SOLUTION: An inkjet head 11 includes: a piezoelectric element 102; a vibrating plate 103; an ink chamber plate 107 including a plurality of ink chambers 104; and a nozzle plate 106 including a plurality of nozzles 105, which are arranged in this order. An adhesive agent 108 containing a bead 109 is provided in any one of the clearances between the piezoelectric element 102 and the vibrating plate 103, between the vibrating plate 103 and the ink chamber plate 107 and between the ink chamber plate 107 and the nozzle plate 106.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inkjet head and a manufacturing method thereof.

  The drop-on-demand ink jet head can apply a necessary amount of ink when necessary according to an input signal. In particular, a piezoelectric drop-on-demand ink jet head is usually connected to an ink supply flow path, and includes a plurality of pressure chambers (ink chambers) having nozzles and ink filled in the pressure chambers. And a piezo element that applies pressure to.

  In a piezo ink jet head, pressure is applied to ink in a pressure chamber due to mechanical distortion of the piezo element caused by applying a drive voltage to the piezo element, and ink is ejected from the nozzle. Piezo-type ink jet heads can be roughly classified into three types: a shear mode type, a push mode type, and a bend mode type, depending on how the piezoelectric element is distorted. In particular, the bend mode type using a piezoelectric element having a laminated structure can generate a strong force at a low voltage, and is expected to be developed for manufacturing electronic devices such as organic EL displays and liquid crystal panels (for example, Patent Document 1).

  In addition, in an inkjet head, it is known to increase the length of the nozzle in the ink discharge direction (hereinafter referred to as the nozzle length) in order to improve the straightness of the ink droplets discharged from the nozzle. However, when the nozzle length is increased, ink tends to stay in the nozzle. If the ink tends to stay in the nozzle, nozzle clogging is likely to occur when air bubbles or foreign matter are mixed in the ink.

  On the other hand, a technique is known in which an ink discharge channel that communicates with a pressure chamber is provided in an inkjet head, and ink discharged from the pressure chamber flows into the ink discharge channel (see, for example, Patent Document 2).

  In such an ink circulation type inkjet head, a predetermined volume of ink supplied from the ink supply channel to the pressure chamber is discharged from the nozzle, and ink remaining in the pressure chamber is discharged to the ink discharge channel. As a result, ink accumulation can be prevented and the problem of nozzle clogging can be solved.

JP 2001-121893 A JP 2009-22214 A

  However, in the ink jet head, when the volumes of a plurality of ink chambers are not uniform, the resonance period of each ink chamber shifts and the speed and volume of ink ejected from each nozzle vary.

  The variation in the volume of the ink chamber is caused by the variation in the thickness of the members constituting the ink chamber. The variation in the thickness of the ink chamber occurs, for example, in a polishing process of a plate constituting the ink chamber.

  In addition, in the inkjet head, when the height of the piezo elements is not uniform, variations in the bonding area between the piezo elements and the diaphragm and variations in initial pressure occur. All of these variations cause variations in the speed and volume of ink ejected from each nozzle.

  An object of the present invention is to provide an ink jet head capable of making the speed and volume of ink ejected from each nozzle uniform and a method for manufacturing the same.

  In an inkjet head according to one aspect of the present invention, a piezoelectric element, a vibration plate, an ink chamber plate including a plurality of ink chambers, and a nozzle plate including a plurality of nozzles are arranged in this order, and the piezoelectric head An adhesive including a spherical member is provided in a gap between the element and the vibration plate, between the vibration plate and the ink chamber plate, or between the ink chamber plate and the nozzle plate. .

  An ink jet head manufacturing method according to an aspect of the present invention is an ink jet head manufacturing method including a plurality of ink chambers and a plurality of nozzles respectively provided corresponding to the plurality of ink chambers. The adhesive including a spherical member is applied to a portion of the surface of the plate-shaped mask member on which the openings are formed, other than the plurality of openings, and each adhesive applied to the mask member is Applying to each of the portions between the plurality of ink chambers in the ink chamber plate through the opening, placing a vibration plate on each adhesive applied between the ink chambers, the vibration plate and the ink chamber Adhere to the plate.

  According to the present invention, the speed and volume of ink ejected from each nozzle can be made uniform.

Sectional drawing of the inkjet head which concerns on Embodiment 1. FIG. Sectional drawing of the inkjet head which concerns on Embodiment 2. FIG. Sectional drawing of the inkjet head which concerns on Embodiment 3. FIG. Sectional drawing of the inkjet head which concerns on Embodiment 4. FIG. FIG. 6 is a top view for explaining a method of manufacturing an inkjet head according to a fifth embodiment. Sectional drawing explaining the manufacturing method of the inkjet head which concerns on Embodiment 5. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
An ink jet head 11 according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an inkjet head 11 according to the first embodiment.

  The ink jet head 11 discharges ink from the nozzle 105 by converting an electric signal applied to the piezo element (piezoelectric element) 102 into displacement, vibrating the diaphragm 103, and applying a pressure wave to the ink in the ink chamber 104. Let

  The ink chamber 104 is formed in the ink chamber plate 107 by, for example, etching.

  The nozzle 105 is formed on the nozzle plate 106 by, for example, etching or laser processing.

  In this embodiment, the ink chamber plate 107 and the nozzle plate 106 are joined (also referred to as adhesion) by injecting the adhesive 108 into the gap 202 a between the ink chamber plate 107 and the nozzle plate 106.

  In the adhesive 108, spherical beads 109 (an example of a spherical member) are mixed. By sandwiching the beads 109 between the ink chamber plate 107 and the nozzle plate 106, the height of the joint between the ink chamber plate 107 and the nozzle plate 106 can be made uniform to the diameter (diameter) of the beads 109. it can.

  The ink chamber plate 107 is formed by stacking a plurality of metal plates patterned by, for example, etching. For this reason, the ink chamber plate 107 may be deformed on the bonding surface with the nozzle plate 106 depending on the bonding state and shape of each metal plate.

  In such a case, if the beads 109 having a uniform diameter are used, the nozzle plate 106 is deformed following the ink chamber plate 107. Due to this deformation, the state of the pressure field from the ink chamber 104 to the nozzle 105 changes, so that a difference occurs in the resonance state for each nozzle 105.

  As a result, variations occur in the speed (hereinafter referred to as “discharge speed”) and volume (hereinafter referred to as “discharge volume”) of the ink discharged from each nozzle 105. Furthermore, since the directions of the nozzles 105 vary, the angle of ink ejected from the nozzles 105 (hereinafter referred to as ejection angle) also varies.

  Therefore, the inkjet head 11 of the present embodiment is configured to match the diameter of the beads 109 with the deformed portion of the ink chamber plate 107 (the gap between the ink chamber plate 107 and the nozzle plate 106). That is, in the inkjet head 11, beads 109 having a large diameter are arranged in a portion where the gap between the ink chamber plate 107 and the nozzle plate 106 is large, and in a portion where the gap between the ink chamber plate 107 and the nozzle plate 106 is small, A bead 109 having a small diameter is arranged.

  Since the gap between the ink chamber plate 107 and the nozzle plate 106 is about 0.5 μm to 2.5 μm, the difference between the larger diameter of the beads 109 and the smaller diameter may be designed to be 2 μm. For example, the larger diameter can be designed as 6 μm and the smaller diameter as 4 μm.

  The diameter of the beads 109 can be increased to about 20 μm that does not hinder the bonding between the ink chamber plate 107 and the nozzle plate 106. Of course, this is not the case when the width and height of the joint portion are increased.

  According to the present embodiment, it is possible to prevent a difference from occurring in the resonance state for each nozzle 105. Therefore, the discharge speed and discharge volume for each nozzle 105 can be made uniform.

(Embodiment 2)
An ink jet head 12 according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of the inkjet head 12 according to the second embodiment. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

  The ink jet head 12 has a thin film piezoelectric element 201 integrated with the diaphragm 103 as a driving unit. In this embodiment, the ink chamber plate 107 and the vibration plate 103 are joined by injecting the adhesive 108 into the gap 202 b between the ink chamber plate 107 and the vibration plate 103.

  The thickness of the thin film piezoelectric element 201 is, for example, 10 to 50 μm. Due to its thinness, the thin film piezoelectric element 201 is deformed following the ink chamber plate 107 when the ink chamber plate 107 is deformed.

  The surface layer of the ink chamber plate 107 is removed by polishing, for example, for the purpose of removing the contaminated layer on the surface thereof. However, depending on the polishing method, the center portion of the ink chamber plate 107 may be thinner by 1 μm to 2 μm than the end portion. Thus, when the thickness of the ink chamber plate 107 varies, the volume of the ink chamber 104 varies. As a result, the discharge speed and the discharge volume vary for each nozzle 105.

  Therefore, the inkjet head 12 of the present embodiment is configured such that the diameter of the beads 109 is matched with the deformed portion of the ink chamber plate 107 (the gap 202b between the ink chamber plate 107 and the vibration plate 103). That is, in the inkjet head 12, beads 109 having a large diameter are arranged in a portion where the gap between the ink chamber plate 107 and the vibration plate 103 is large, and in a portion where the gap between the ink chamber plate 107 and the vibration plate 103 is small, A bead 109 having a small diameter is arranged.

  Also in the present embodiment, as in the first embodiment, the gap between the ink chamber plate 107 and the vibration plate 103 is about 0.5 μm to 2.5 μm. What is necessary is just to design so that the difference with a diameter may be 2 micrometers.

  According to the present embodiment, the volume of each ink chamber 104 can be made constant, and the thin film piezo element 201 can be adhered to the diaphragm 103 flatly. Therefore, the discharge speed and discharge volume for each nozzle 105 can be made uniform.

(Embodiment 3)
The ink jet head 13 according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of the inkjet head 13 according to the third embodiment. In FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

  The piezo element 102 may be warped by several μm during its manufacture. In order to remove the warp, the piezo element 102 may be polished in the manufacturing process of the inkjet head 13. However, it is difficult to completely flatten the warp, and undulations of 1 to 4 μm remain.

  On the other hand, in the inkjet head 13, the discharge speed and the discharge volume change according to the area of the bonding surface between the piezo element 102 and the diaphragm 103. Therefore, a method is conceivable in which an adhesive is applied to a wider range than the adhesive surface on the piezoelectric element 102 side, and the area of the adhesive surface is defined by the area of the protrusion provided on the piezoelectric element 102 or the diaphragm 103.

  In this method, a flexible adhesive can be used so that the protruding adhesive does not affect ink ejection. Therefore, in the present embodiment, as shown in FIG. 3, by injecting a flexible adhesive 301 into the gap 202c between the diaphragm 103 and the piezoelectric element 102, the diaphragm 103 and the piezoelectric element 102 are bonded. Join. Here, the flexible adhesive 301 is an adhesive having flexibility after bonding, and includes an elastic (rubber) component such as silicon rubber. The flexible adhesive 301 preferably has an elastic (rubber) component as a main component of 10% by volume or more.

  However, if the height of the piezoelectric element 102 varies, the joining height 302 (height of the gap 202 c) by the flexible adhesive 301 also varies from nozzle to nozzle 105.

  Since the flexible adhesive 301 expands and contracts, when the joining height 302 is large, the displacement generated by the piezo element 102 is not easily transmitted to the diaphragm 103. On the other hand, when the joining height 302 is small, the displacement generated by the piezo element 102 reaches the diaphragm 103 without being substantially attenuated.

  That is, when the flexible adhesive 301 is used in order to avoid variations in ink ejection due to the area of the adhesive surface, it is affected by variations in the joint height 302.

  Therefore, in order to reduce the influence due to the stretchability of the flexible adhesive 301 even if the joining height 302 varies, in the inkjet head 13 of the present embodiment, the beads 109 having different diameters according to the joining height 302, The beads 109 are arranged so that the density of the beads 109 in the flexible adhesive 301 is different.

  For example, when the difference in the bonding height 302 between the nozzles 105 is 2 μm, beads 109 having a diameter of 6 μm are arranged at a high density in the flexible adhesive 301 having a high bonding height 302, and the bonding height 302 is In the low flexible adhesive 301, beads 109 having a diameter of 3 μm are arranged at a low density.

  According to the present embodiment, when the flexible adhesive 301 is used in order to avoid variations in ink ejection due to the area of the bonding surface between the piezo element 102 and the diaphragm 103, the variation in the joint height 302 is changed. The impact can be reduced.

(Embodiment 4)
An ink jet head 14 according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of the inkjet head 14 according to the fourth embodiment. In FIG. 4, the same components as those in FIGS. 1 and 3 are denoted by the same reference numerals, and description thereof will be omitted.

  This embodiment is effective when the thickness of the ink chamber plate 107 varies (see Embodiment 1) and the height of each piezo element 102 varies (see Embodiment 3). .

  First, the ink chamber plate 107 and the vibration plate 103 are joined by injecting the hard adhesive 401 into the gap 202 d between the ink chamber plate 107 and the vibration plate 103. Here, the hard adhesive 401 is an adhesive that hardens after bonding, and is an adhesive that has few male elasticity (rubber) components, such as an epoxy adhesive. The hard adhesive 401 preferably has no elastic (rubber) component as a main component of 10% by volume or more.

  At this time, beads 109 having different diameters are arranged in the hard adhesive 401 so that the vibration plate 103 is flat and the undulation of the ink chamber plate 107 is canceled.

  For example, beads 109 having a diameter of 4 μm are disposed in the hard adhesive 401 having a high joining height 402 (height of the gap 202d) between the ink chamber plate 107 and the vibration plate 103. On the other hand, the beads 109 are not disposed in the hard adhesive 401 having a low joining height 402. Since rigidity is required in the subsequent process, it is preferable to keep the joint height 402 as low as possible.

  Next, the diaphragm 103 and the piezoelectric element 102 are joined by injecting the flexible adhesive 301 into the gap 202e between the diaphragm 103 joined to the ink chamber plate 107 and the piezoelectric element 102. Also at this time, beads 109 having different diameters are bonded to the flexible adhesive 301 in accordance with the joint height 403 (height of the gap 202e) between the diaphragm 103 and the piezoelectric element 102 so as not to break the plane of the diaphragm 103. Place in.

  For example, when the difference in bonding height 403 between the nozzles 105 is 4 μm, for example, beads 109 having a diameter of 4 μm are arranged in the flexible adhesive 301 having a high bonding height 403 and the bonding height 403 is low. For example, beads 109 having a diameter of 2 μm are arranged in the flexible adhesive 301 in which the bonding height 403 is an average height.

  Further, by pressing the piezo element 102 into the flexible adhesive 301 having an average height, the beads 109 are sunk into the piezo element 102 by about 0.5 μm, and the bonding height 403 is adjusted. May be.

  According to the present embodiment, it is possible to obtain the effects described in the first and third embodiments.

(Embodiment 5)
A method of manufacturing the ink jet head according to the fifth embodiment will be described with reference to FIGS. FIG. 5 is a top view of the inkjet head, and FIG. 6 is a cross-sectional view of the inkjet head.

  The mask 500 is a metal thin plate, for example. The mask 500 has a plurality of mesh portions 501 (an example of openings) formed by punching.

  First, the adhesive 502 is applied on the mask 500 using, for example, a dispenser (not shown). Here, as shown in FIG. 6, in the ink chamber plate 107, the end portion is thicker than the center portion (the joining height of the end portion is lower than the joining height of the center portion). Therefore, only the adhesive 502 not containing beads is applied to the end of the ink chamber plate 107 (an example of the portion between the ink chambers), and the central portion of the ink chamber plate 107 (an example of the portion between the ink chambers) An adhesive 502 including beads 504 having a diameter of 3 μm is applied, and a bead 503 having a diameter of 2 μm is provided at an intermediate portion (an example of a portion between the ink chambers) between the center portion and the end portion of the ink chamber plate 107. The adhesive 502 containing is applied.

  Thereafter, by operating a squeegee (not shown) in the squeegee operating direction 505, each adhesive 502 applied on the mask 500 passes through each mesh portion 501, and as shown in FIG. Is transcribed.

  Thereafter, the mask 500 is removed, and the vibration plate 103 is placed on each adhesive 502 transferred to the ink chamber plate 107 to bond the ink chamber plate 107 and the vibration plate 103.

  As described above, an ink jet head in which the volume of the ink chamber 104 is uniform between the nozzles 105 can be created.

  If the opening diameter of the mesh portion 501 can be reduced to about 2 μm, an adhesive 502 in which beads having various diameters are mixed is applied on the mask 500, and the opening diameter is changed for each nozzle 105. The size of the beads can be selected according to the opening diameter of the mesh portion 501.

  In addition, this invention is not limited to description of the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning.

  The inkjet head of the present invention can be widely applied as an industrial inkjet head.

11, 12, 13, 14 Inkjet head 102 Piezo element 103 Diaphragm 104 Ink chamber 105 Nozzle 106 Nozzle plate 107 Ink chamber plate 108, 502 Adhesive 109, 503, 504 Bead 201 Thin film piezo element 202a-202e Gap 301 Flexible adhesion Agent 302 Bonding height 401 Hard adhesive 402, 403 Bonding height 500 Mask 501 Mesh part 505 Squeegee operating direction

Claims (6)

A piezoelectric element;
A diaphragm,
An ink chamber plate with a plurality of ink chambers;
A nozzle plate having a plurality of nozzles, arranged in this order,
An adhesive including a spherical member is provided in a gap between the piezoelectric element and the diaphragm, between the diaphragm and the ink chamber plate, or between the ink chamber plate and the nozzle plate. Was,
Inkjet head. The gap includes a first gap and a second gap that is longer than the first gap,
The diameter of the spherical member contained in the adhesive provided in the second gap is larger than the diameter of the spherical member contained in the adhesive provided in the first gap,
The inkjet head according to claim 1. The piezoelectric element is a thin film piezoelectric element.
The inkjet head according to claim 1 or 2. The adhesive provided in the gap between the piezoelectric element and the diaphragm is a flexible adhesive,
The inkjet head according to any one of claims 1 to 3. The density of the spherical member contained in the adhesive provided in the first gap is different from the density of the spherical member contained in the adhesive provided in the second gap.
The inkjet head according to any one of claims 2 to 4. A method of manufacturing an inkjet head comprising a plurality of ink chambers and a plurality of nozzles provided corresponding to the plurality of ink chambers,
Applying an adhesive containing a spherical member to a portion of the surface of the plate-shaped mask member on which a plurality of openings are formed, other than the plurality of openings,
Each adhesive applied to the mask member is applied to each of a plurality of ink chamber portions in the ink chamber plate through the openings.
Placing a diaphragm on each adhesive applied between the ink chambers, and bonding the diaphragm and the ink chamber plate;
A method for manufacturing an inkjet head.