JP2006076128A - Inkjet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording head which is free from deformation variation of diaphragms and is superior in ink delivery efficiency. <P>SOLUTION: Recessed parts 18 having a specified dimension are provided on the surface of the diaphragm 12 according to a given arrangement pitch. In this embodiment, for example, the recessed parts (one side: 30 μm, depth: 5 μm) are arranged at a pitch of 120 μm. The range shown by a broken line is a range where a piezoelectric element 20 is bonded. Namely, the recessed parts 18 are provided on the connecting surface with the piezoelectric element 20 and on its periphery. As shown in the drawing (a), the surplus adhesive agent 22 is absorbed by the recessed parts 18 provided on the bonding surface of the diaphragm 12, in connecting the diaphragm 12 to the piezoelectric element 20 with an adhesive agent 22. Thus, the surplus adhesive agent 22 is squeezed out around the piezoelectric element 20 and is cured, preventing the bonding area/shape between the diaphragm 12 and the piezoelectric element 20 from being varied. When the displacement amount of the piezoelectric element 20 is constant, the displacement of the diaphragm 12 is constant, eliminating the deformation variation of the diaphragm of the inkjet recording head. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording head including a vibration plate that pressurizes ink to generate a pressure wave, and a piezoelectric element that is bonded to the vibration plate and vibrates the vibration plate.

  Piezoelectric ink jet recording head, that is, an ink jet recording head having a structure forming a part of a pressure chamber and a piezoelectric element bonded to deform the vibration plate. There is a problem that excess adhesive protrudes between the two.

  For example, as shown in FIG. 8, when the piezoelectric element 100 is bonded to the diaphragm 102 with the adhesive 104, the excess adhesive 104 protrudes from the end of the piezoelectric element 100 and the amount thereof varies. Since the protruding portion of the adhesive 104 varies, the rigidity of the diaphragm 102 also varies, and the displacement of the piezoelectric element 100 is constant, whereas the deformation of each diaphragm 102 varies. Variations also occur in the characteristics of the discharged drops.

  In bonding the piezoelectric element and the diaphragm as described above, for example, a method of managing the coating amount of the adhesive material in order to suppress the protrusion of the adhesive material has been proposed, but the effect is not sufficient.

  Further, as shown in FIG. 9, an island part (convex step) 108 is provided on the joint surface of the diaphragm 106, and the protruding adhesive 104 is accommodated in the side wall of the island part 108 to suppress variation in variation of the diaphragm 106. A structure has also been proposed. However, in this structure, only the joint surface (active part) of the diaphragm 106 is thick, and the rigidity of the surrounding inactive part is relatively lowered. Therefore, when the pressure is applied by the piezoelectric element, the pressure efficiency of the pressure chamber is increased. It will decline.

  Alternatively, as shown in FIG. 10, an island portion 211 for escaping the adhesive that protrudes from the joint portion of the diaphragm with the piezoelectric element is provided, and a concave portion 212 is provided therein, whereby the adhesive 204 that flows out to the diaphragm 210 is provided. A method has also been proposed in which the recess 212 absorbs and prevents the adhesive 204 from flowing out to the diaphragm 210 (see, for example, Patent Document 1).

  There is also an example in which a concave portion for accommodating the protruding adhesive is provided on the piezoelectric element side. For example, as shown in FIG. 11, a relief groove 315 is formed over the entire periphery of the end portion of the piezoelectric element 303 as a storage means for storing excess adhesive 305 when the diaphragm 304 and the piezoelectric element 303 are bonded. . The escape groove 315 can absorb the adhesive 305 flowing out and prevent the adhesive 305 flowing out from the end face of each piezoelectric element 303 from overflowing (see, for example, Patent Document 2).

  Alternatively, in order to prevent the adhesive applied only to the active part of the piezoelectric element from protruding from the active part to the surrounding inactive part region, by providing adhesive escape grooves on both sides of the active part, the protruding adhesive There has also been proposed a method of forming an adhesive escape groove that flows into the adhesive escape groove without flowing out to an adjacent inactive portion (see, for example, Patent Document 3).

  However, in the method of providing the recess in the island part as in Patent Document 1, only the joint surface (active part) of the diaphragm becomes thick and the rigidity of the peripheral inactive part is relatively lowered. At this time, the problem that the pressurization efficiency of the pressure chamber decreases cannot be solved.

  In addition, as described in Patent Documents 2 and 3, by providing a concave portion on the piezoelectric element side, it is not necessary to provide an unevenness on the diaphragm side, but it is necessary to process the piezoelectric element, so that processing cost and processing time are increased. Become.

  Therefore, the present invention suppresses the adhesive material from protruding to the periphery of the piezoelectric element by providing a concave shape on the surface of the diaphragm corresponding to the joint surface with the piezoelectric element. Thereby, the deformation variation of the diaphragm is eliminated, and the uniformity of the discharged drop (droplet) can be ensured. As a result, it is not necessary to provide an island for the escape of the adhesive material or a stepped shape only at the end of the joining surface at the piezoelectric element joining portion, which has been conventionally employed, and the diaphragm (displacement) is uniformly displaced, so that the drop (liquid Droplet ejection efficiency is also improved.

In addition, since the stress / deformation characteristics of the diaphragm can be controlled by the concave shape, for example, the rigidity of the periphery of the diaphragm, which is an inactive part of the piezoelectric element, can be increased. An effect is also obtained in avoiding pinholes.
Japanese Patent Laid-Open No. 2003-39669 (FIG. 4, pages 4 to 5) Japanese Patent Laid-Open No. 11-320875 (FIG. 1, pages 3 to 5) JP-A-6-188472 (FIG. 7, pages 3-4)

  In consideration of the above facts, the present invention has an object to provide an ink jet recording head that is excellent in ejection efficiency without variation in deformation of the diaphragm.

  The ink jet recording head according to claim 1, comprising: a vibration plate that pressurizes ink to generate a pressure wave; and a piezoelectric element that is bonded to the vibration plate and vibrates the vibration plate, A concave portion is formed on an adhesive surface of the diaphragm with the piezoelectric element.

  In the invention with the above configuration, variation in deformation of the vibration plate due to the protrusion of the adhesive can be suppressed. Therefore, it is possible to prevent the stress concentration generated from the shape of the ink jet recording head and to provide an ink jet recording head having a long life and excellent discharge efficiency.

  The inkjet recording head according to claim 2, comprising: a vibration plate that pressurizes ink to generate a pressure wave; and a piezoelectric element that is bonded to the vibration plate and vibrates the vibration plate, The diaphragm is characterized in that a concave portion is formed on and around the adhesion surface of the diaphragm with the piezoelectric element.

  In the invention with the above configuration, the recesses are formed on and around the bonding surface with the piezoelectric element, so that the strength of the periphery of the bonding surface, that is, the inactive portion and the active portion that is the bonding surface changes discontinuously. It is possible to prevent the deformation from being affected.

  An ink jet recording head according to claim 3, comprising: a vibration plate that pressurizes ink to generate a pressure wave; and a piezoelectric element that is bonded to the vibration plate and vibrates the vibration plate, A concave portion is formed on the entire surface of the diaphragm on the side of the bonding surface with the piezoelectric element.

  In the invention with the above configuration, since the concave portion is formed on the entire surface of the diaphragm, the diaphragm has no discontinuous points such as the presence or absence of island ends or concave portions, so that the reliability of the diaphragm can be ensured.

  The ink jet recording head according to claim 4 is characterized in that the arrangement pitch of the recesses is uniform.

  In the invention with the above configuration, since the arrangement pitch of the recesses is uniform, the pattern is simple, and the required alignment accuracy can be suppressed.

  The ink jet recording head according to claim 5 is characterized in that the arrangement pitch of the recesses continuously changes.

  In the invention with the above configuration, by continuously changing the arrangement pitch of the recesses, the rigidity of the diaphragm can be arbitrarily changed according to the arrangement pitch, so the stress / deformation characteristics of the diaphragm are controlled to the desired characteristics. It becomes possible.

  The ink jet recording head according to claim 6 is characterized in that the size of the concave portion is uniform.

  In the invention with the above configuration, the size of the recess is uniform, so the pattern is simple, and the cost of the mask used can be reduced.

  The ink jet recording head according to claim 7 is characterized in that the size of the recess continuously changes.

  In the invention with the above configuration, by continuously changing the size of the recess, the rigidity of the diaphragm can be arbitrarily changed according to the size of the recess, so that the stress / deformation characteristics of the diaphragm can be changed to desired characteristics. Control becomes possible.

  According to an eighth aspect of the present invention, there is provided an ink jet recording head comprising a communication path that communicates the recesses.

  In the invention of the above configuration, the amount of the adhesive is partially excessive due to the communication path that connects the recesses, and it is possible to cope with the amount of adhesive that cannot be absorbed by the individual recesses by letting it escape to the surrounding recesses. .

  The ink jet recording head according to claim 9 is characterized in that at least one of the recesses communicated by the communication path communicates with the atmosphere.

  In the invention with the above configuration, even when the amount of outgas generated when the adhesive solidifies, it can be dealt with by exhausting it from the recess to the atmosphere via the communication path.

  The ink jet recording head according to claim 10 is characterized in that the recess is formed by etching.

  In the invention with the above configuration, when the concave portion is formed in the diaphragm, it is sufficient to change the mask pattern and the etching depth of the diaphragm, so that it is not necessary to add a new process, and manufacturing cost and time can be saved. it can.

  Since the present invention has the above-described configuration, an ink jet recording head having no variation in deformation of the vibration plate and excellent discharge efficiency can be obtained.

  FIG. 1 shows the structure of the diaphragm of the ink jet recording head according to the first embodiment of the present invention.

  As shown in FIGS. 1A and 1B, concave portions 18 having predetermined dimensions are provided on the surface of the diaphragm 12 according to a predetermined arrangement pitch. For example, in this embodiment, square-shaped concave portions (one side 30 μm, depth 5 μm) are arranged at a pitch of 120 μm on a diaphragm 12 made of SUS and having a thickness of about 20 μm. A piezoelectric element 20 having an element size of 600 μm square and a thickness of about 35 μm is adhered thereon. A range indicated by a broken line is a range to which the piezoelectric element 20 is bonded. That is, the recess 18 is provided on the joint surface with the piezoelectric element 20 and the periphery thereof.

  As a result, as shown in FIG. 1A, when the diaphragm 12 and the piezoelectric element 20 are joined with the adhesive 22, the excess adhesive 22 is absorbed by the recess 18 provided on the adhesion surface of the diaphragm 12. The For this reason, it is possible to prevent the excess adhesive 22 from protruding around the piezoelectric element 20 and solidifying, and the contact area / shape between the diaphragm 12 and the piezoelectric element 20 from varying.

  For this reason, if the amount of variation of the piezoelectric element 20 is constant, the displacement of the diaphragm 12 is also constant, and an ink jet recording head free from variations in deformation of the diaphragm can be obtained.

  Needless to say, the shape of the recess 18 is not limited to a square as in the present embodiment, and various shapes such as a circle, a rectangle, and a triangle can be selected and applied according to the purpose and cost.

  FIG. 2 shows the structure of the diaphragm of the ink jet recording head according to the second embodiment of the present invention.

  As shown in FIG. 2, the point that recesses 18 having predetermined dimensions are provided on the surface of the diaphragm 12 in accordance with a predetermined arrangement pitch is the same as in the first embodiment. The range indicated by the broken line is the range to which the piezoelectric element 20 is bonded. In this embodiment, the recess 18 is not limited to the bonding surface to the piezoelectric element 20 and its periphery, but is provided over the entire surface to be bonded to the piezoelectric element 20. It has been.

  In the present embodiment, the recesses 18 may have the same shape and the same arrangement pitch on the entire surface, but the active part and the periphery to be joined to the piezoelectric element 20 can be changed by consciously changing the shape and / or arrangement pitch of the recesses 18 depending on the location. It is possible to change the rigidity of the inactive part.

  For example, the concave portion 18 of the inactive portion of the diaphragm 12 is shallower or the pitch is roughened to relatively increase the rigidity of the inactive portion of the diaphragm 12 as compared with the active portion, thereby handling during machining operations. It is possible to obtain an ink jet recording head with high ejection efficiency while providing effects such as improvement in performance and avoiding pinholes in the diaphragm material.

  FIG. 3 shows the structure of the diaphragm of the ink jet recording head according to the third embodiment of the present invention.

  As shown in FIG. 3, mesh-shaped recesses 18 are provided on the surface of the diaphragm 12 with a predetermined size and a predetermined arrangement pitch. For example, in the present embodiment, the recesses 18 having a width of 15 μm and a depth of 5 μm are provided in a shape that covers the bonding surface and the periphery of the piezoelectric element 20 with an arrangement pitch of 120 μm.

  In the case of the mesh-shaped recess 18 as in this embodiment, even when the diaphragm 12 and the piezoelectric element 20 are bonded to each other, even if the adhesive 22 is locally large, all the recesses 18 communicate with each other. As a result, the adhesive 22 quickly spreads over the entire joining surface, and the protrusion and variation of the adhesive 22 can be suppressed.

  Also in the present embodiment, as in the second embodiment, the shape (depth, width) and / or the arrangement pitch of the recesses 18 are consciously changed depending on the location, so that the active portion joined to the piezoelectric element 20 and the surrounding area are not affected. It is possible to change the rigidity of the active part.

  FIG. 4 shows the structure of the diaphragm of the ink jet recording head according to the fourth embodiment of the present invention.

  As shown in FIG. 4, concentric recesses 18 are provided on the surface of the diaphragm 12 with a predetermined size and a predetermined arrangement pitch. In the present embodiment, when the shape of the piezoelectric element 20 is a circle or an ellipse, the adhesive 22 protrudes from the periphery of the piezoelectric element 20 and solidifies by providing the concave portion 18 having a shape suitable for the piezoelectric element 20. It is possible to prevent the contact area / shape with the element 20 from varying.

  In this embodiment, the concave portion 18 is concentric. However, the same effect can be obtained in various modifications such as a spiral shape like a groove of a record board or a combination of radial grooves in a spider web shape. .

  Also in the present embodiment, similarly to the second embodiment, the shape (depth, width) and / or the arrangement pitch of the recesses 18 are consciously changed depending on the location, so that the active portion joined to the piezoelectric element 20 and the peripheral portion It is possible to change the rigidity of the inactive portion.

  FIG. 5 shows a method of manufacturing an ink jet recording head according to the present invention.

  First, as shown in FIG. 5A, a resist 14A is applied to the piezoelectric element bonding side surface of the diaphragm 12, and patterning is performed for the work alignment reference hole 16 and the adhesive escape recess 18. A resist 14B is applied to the entire pressure chamber side.

  Next, as shown in FIG. 5B, the piezoelectric element bonding side of the diaphragm 12 is etched. Thereby, the recess 18 is formed.

  Next, as shown in FIG. 5C, the resist 14B on the piezoelectric element bonding side of the diaphragm 12 is removed. A resist 14D is applied to the pressure chamber side of the diaphragm 12 and patterning for the reference hole 16 is performed. A resist 14C is applied to the entire surface of the piezoelectric element bonding side.

  Next, as shown in FIG. 5D, the diaphragm 12 is etched from the pressure chamber side. Thereby, the reference hole 16 (through hole) is formed.

  Finally, as shown in FIG. 5E, the resists 14C and 14D on the piezoelectric element bonding side and pressure chamber side are removed, and the diaphragm 12 is formed. In this case, for example, the recess 18 has a width of 15 μm and a depth of 5 μm with respect to a piezoelectric element having a width of 800 μm.

  Here, in the case where the depth of the concave portion 18 is not less than ½ of the plate thickness of the diaphragm 12, the diaphragm 12 may be etched simultaneously from both sides as described below.

  FIG. 6 shows a manufacturing method in another embodiment of the ink jet recording head according to the present invention.

First, as shown in FIG. 6A, a resist 14 is formed on the piezoelectric element bonding side surface of the diaphragm 12.
A, resist 14B is applied to the side of the pressure chamber, and patterning is performed for the recess 18 and the reference hole 16, respectively.

  Next, as shown in FIG. 6B, etching is performed simultaneously from both surfaces of the diaphragm 12. At this time, the width of the etching pattern for the reference hole 16 is narrower than that in FIG. 5A in order to prevent so-called over-etching in which the etching progresses in the lateral direction and the diameter of the hole increases with the progress of etching. It is.

  Finally, as shown in FIG. 6C, after the etching is completed, the resist 14A and the resist 14B are removed.

  FIG. 7 shows a method for bonding a diaphragm and a piezoelectric element according to the present invention.

  As shown in FIG. 7, the piezoelectric element 20 is fixed on the rigid plate 26 with the resin layer 24 interposed therebetween. An adhesive 22 is applied to the piezoelectric element 20 on the side in contact with the vibration plate 12, and is in pressure contact with the vibration plate 12 that has finished forming the ink flow path.

  At this time, since the diaphragm 12 is provided with the concave portion 18 that absorbs the excessive adhesive 22 as described above, the adhesive 22 protrudes around the piezoelectric element 20 at the time of bonding, and the vibration plate 12 is activated. There is no variation in rigidity around the part.

2A and 2B are a plan view and a cross-sectional view illustrating the structure of the ink jet recording head according to the first embodiment of the invention. It is a top view which shows the structure of the inkjet recording head which concerns on the 2nd form of this invention. It is a top view which shows the structure of the inkjet recording head which concerns on the 3rd form of this invention. It is a top view which shows the structure of the inkjet recording head which concerns on the 4th form of this invention. It is sectional drawing which shows the manufacturing method of the inkjet recording head which concerns on this invention. It is sectional drawing which shows the manufacturing method of the inkjet recording head which concerns on this invention. It is sectional drawing which shows the manufacturing method of the inkjet recording head which concerns on this invention. It is a figure which shows the structure of the conventional inkjet recording head. It is a figure which shows the structure of the conventional inkjet recording head. It is a figure which shows the structure of the conventional inkjet recording head. It is a figure which shows the structure of the conventional inkjet recording head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording head 12 Diaphragm 16 Reference hole 18 Concave part 20 Piezoelectric element 22 Adhesive

Claims (10)

A diaphragm that pressurizes the ink and generates a pressure wave;
A piezoelectric element that is bonded to the diaphragm and vibrates it;
An ink jet recording head comprising:
An ink jet recording head, wherein a concave portion is formed on an adhesive surface of the diaphragm with the piezoelectric element.
A diaphragm that pressurizes the ink and generates a pressure wave;
A piezoelectric element that is bonded to the diaphragm and vibrates it;
An ink jet recording head comprising:
An ink jet recording head, wherein a concave portion is formed on an adhesion surface of the vibration plate to the piezoelectric element and its periphery.
A diaphragm that pressurizes the ink and generates a pressure wave;
A piezoelectric element that is bonded to the diaphragm and vibrates it;
An ink jet recording head comprising:
An ink jet recording head, wherein a concave portion is formed on the entire surface of the vibration plate on the side of the bonding surface with the piezoelectric element.
4. The ink jet recording head according to claim 1, wherein the arrangement pitch of the recesses is uniform.
4. The ink jet recording head according to claim 1, wherein the arrangement pitch of the recesses continuously changes.
6. The ink jet recording head according to claim 1, wherein the size of the recess is uniform.
6. The ink jet recording head according to claim 1, wherein the size of the concave portion changes continuously.
The ink jet recording head according to claim 1, further comprising a communication path that communicates the recesses.
9. The ink jet recording head according to claim 8, wherein at least one of the recesses communicated by the communication path communicates with the atmosphere.
The ink jet recording head according to claim 1, wherein the concave portion is formed by etching.

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