JP2003276190A - Ink jet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording head in which a piezoelectric actuator 4 can be deformed depending on the applying voltage by preventing the deformation from being impeded or absorbed and ink drop ejection characteristics (ejection speed, ejection quantity) can be enhanced. <P>SOLUTION: In an ink jet recording head 20 formed by bonding the top surface of the barrier wall of a channel member 6 and the piezoelectric actuator 4 through an adhesive layer 7, a projecting part 7a of the adhesive layer 7 is formed at the corner part of the piezoelectric actuator 4 and each barrier wall 5 wherein the width V of the projecting part 7a is set between 0 and one third of the width W of a channel 10, and the Young's modulus of the adhesive layer 7 is set in the range of 0.1-5.0 GPa. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for various printers and recorders for printing characters and images by ejecting ink droplets from fine ink ejection holes, facsimiles, or for forming patterns in the textile printing or ceramics fields. The present invention relates to an inkjet recording head mounted on a recording device such as a printing machine.

[0002]

2. Description of the Related Art In recent years, with the spread of multimedia, a non-impact type recording apparatus using an ink jet method or a thermal transfer method has been developed in place of the impact type recording apparatus, and its application range is in various industrial fields and general fields. It is spreading in the household field.

Among such non-impact recording apparatuses, the recording apparatuses using the ink jet method are attracting attention in the future because they are easy to produce multiple gradations and colors and have low running costs.

FIG. 4 shows a conventional ink jet recording head 40 used in a recording apparatus using an ink jet system.
An example is shown.

In this ink jet recording head 40, a plurality of partition walls 25 are provided side by side, and the ink flow path 3 is provided between the partition walls 25.
The flow path member 26 has a common electrode 21 formed on substantially the entire one main surface of the piezoelectric ceramic plate 23 and a plurality of individual electrodes 22 formed on the other main surface. By joining the top surface of each partition wall of the piezoelectric element 26 and the piezoelectric actuator 24 with the adhesive layer 27, the flow path 30 of the flow path member 26 is closed to form an ink chamber. Reference numeral 29 is an ink ejection hole formed on the bottom surface of each flow path 30 of the flow path member 26.

Then, a voltage is applied between the individual electrode 22 and the common electrode 21 of the piezoelectric actuator 24 arranged on each flow path 30 to bend the piezoelectric actuator 24, thereby adding ink in the flow path 30. It was designed to eject ink droplets from the ink ejection holes 29 (see Japanese Patent Laid-Open No. 10-151739).

Further, as in the ink jet recording head 40 shown in FIG. 4, in a structure in which the piezoelectric actuator 24 is bonded on the flow path member 26 to press the ink in the flow path 30, the deformation of the piezoelectric actuator 24. In order to eject the ink droplets from the ink ejection holes 29 with good responsiveness, it is necessary that the piezoelectric actuator 24 is firmly joined to the partition wall 25 so as not to restrain the deformation of the piezoelectric actuator 24.
Therefore, conventionally, the piezoelectric actuator 24 and the flow path member 26
An epoxy resin-based thermosetting adhesive having a Young's modulus of about 7 GPa was used for the adhesive layer 27 that joins and.

[0008]

By the way, in the ink jet recording head 40 shown in FIG.
When the piezoelectric actuator 24 and the piezoelectric actuator 24 are bonded via the adhesive layer 27, since the entire top surface of the partition wall is firmly bonded to the piezoelectric actuator 24 via the adhesive layer 27, a large amount of adhesive is applied. Therefore, the protruding portion 27a of the adhesive layer 27 is formed at the corner portion formed by the piezoelectric actuator 24 and the partition wall 25.

However, when the adhesive layer 27 is made of a thermosetting adhesive having a high Young's modulus, the protruding portion 27a of the adhesive layer 27 is also made of a thermosetting adhesive having a high Young's modulus, and therefore, on the flow path 30. When the piezoelectric actuator 24 is deformed, the deformation causes the protrusion 2 of the adhesive layer 27 having high rigidity.
7a, the piezoelectric actuator 24
There is a problem in that it is not possible to make a desired deformation with respect to the voltage value applied to the ink, and as a result, the ink pressure in the flow path 30 decreases, and it is not possible to eject ink droplets that match the voltage value. there were.

Further, when the voltage value applied to the piezoelectric actuator 24 in order to eject a desired ink droplet is increased, the stress generated in the piezoelectric ceramic plate 23 forming the piezoelectric actuator 24 is increased, and in a severe case, the piezoelectric actuator. There was a fear that 24 would be destroyed. Moreover, increasing the applied voltage leads to an increase in power consumption, and the piezoelectric actuator 24 also generates a large amount of heat, which increases the viscosity of the ink and causes clogging of the ink ejection holes 29. There was also a fear that it would not be possible to eject ink droplets in severe times.

Further, the protruding portion 27a of the adhesive layer 27
As the width of the channel increases, the volume in the flow channel 30 decreases,
Since the flow path resistance increases, the ejection characteristics (ejection speed and ejection amount) of the ink droplet become non-uniform, and the deformation of the piezoelectric actuator 24 is further hindered. ), There was also a problem that it significantly decreased.

[0012]

In view of the above problems, the present invention has a plurality of partition walls arranged in parallel, and a flow path member having a flow path for ink between the partition walls and the above flow paths are closed. In an ink jet recording head having a piezoelectric actuator joined to a partition wall top surface of a flow path member via an adhesive layer, and an ink discharge hole communicating with each of the flow paths, the piezoelectric actuator and each partition wall are provided with the above The protruding portion of the adhesive layer is formed, the width of the protruding portion is 0 or more and 1/3 or less of the width of the flow path, and the Young's modulus of the adhesive layer is 0.1 GPa to 5.0 GPa. Is characterized by.

The Young's modulus of the adhesive layer is preferably 0.1 GPa to 3.0 GPa.

Further, it is preferable to use a material in which a second adhesive layer having a Young's modulus equal to or higher than that of the adhesive layer is provided between the adhesive layer and the partition top surface.

In the present invention, the Young's modulus of the adhesive layer means the Young's modulus after curing.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an ink jet recording head of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partially broken perspective view showing an example of the ink jet recording head of the present invention, and FIGS. 2 (a) and 2 (b).
FIG. 3 is a partial cross-sectional view for explaining the driving principle of the inkjet recording head of the present invention.

In this ink jet recording head 20, a plurality of partition walls 5 are provided side by side, and a flow path member 6 having a flow path 10 for ink between the partition walls 5 and substantially the entire one main surface of the piezoelectric ceramic plate 3. A common electrode 1 and a plurality of individual electrodes 2 on the other main surface
And the piezoelectric actuator 4 having the above-mentioned structure.
The ink chamber is configured by closing the flow channel 10 of the flow channel member 6 by joining the ink chambers. Reference numeral 9 is an ink ejection hole formed on the bottom surface of each flow path 10 of the flow path member 6, and the piezoelectric ceramic plate 3 forming the piezoelectric actuator 4 is polarized in the direction of the arrow.

At the corner portion formed by the piezoelectric actuator 4 and the partition wall 5, an adhesive layer 7 for joining the two is formed.
Has a protruding portion 7a, and the width V of the protruding portion 7a is 0 or more and 1/3 or less of the width W of the flow path 10, and
The Young's modulus of the adhesive layer 7 is 0.1 GPa to 5.0 GPa.

The ink jet recording head 2
In order to eject ink droplets from 0 and perform recording, as shown in FIG. 2A, a voltage is applied between the individual electrode 2 and the common electrode 1 of the piezoelectric actuator 4 arranged on the flow path 10. In addition, the piezoelectric actuator 4 is curved so that the individual electrode 2 side is convex, and the flow path 10 is depressurized to fill the flow path 10 with ink. Next, when the piezoelectric actuator 4 is de-energized, the curved piezoelectric actuator 4 tries to return to its original state by the elastic action as shown in FIG. 2B, but due to the restoring force at this time, Channel 1
The ink of 0 can be pressurized and ejected as an ink droplet from the ink ejection hole 9, as shown in FIG.
By repeating the operation of (b), ink droplets are continuously ejected from the ink ejection holes 9.

At this time, in the ink jet recording head 20 of the present invention, since the piezoelectric actuator 4 and the partition wall 5 are firmly adhered to each other, the protruding portion of the adhesive layer 7 is formed in the corner portion formed by the piezoelectric actuator 4 and the partition wall 5. 7a, but the width V of the protruding portion 7a is 0 or more, the flow path 1
Since the Young's modulus of the adhesive layer 7 is set to 0.1 / 3 or less of the width W of 0 and the adhesive layer 7 is set to 0.1 GPa to 5.0 GPa, the volume in the flow path 10 is not significantly reduced,
Further, since the piezoelectric actuator 4 on the flow path 10 is not significantly hindered from being deformed, the piezoelectric actuator 4 can be deformed in accordance with the applied voltage, and as a result, desired ink ejection characteristics (ejection speed, ejection speed, It is possible to eject an ink droplet having a discharge amount).

That is, the piezoelectric actuator 4 and the flow path member 6
In order to firmly adhere the partition wall 5 of the partition wall 5, the adhesive layer 7 needs to be interposed on the entire top surface of the partition wall. For that purpose, the adhesive layer is formed on the corner portion formed by the piezoelectric actuator 4 and the partition wall 5. The protruding portion 7a of 7 should be formed, and the Young's modulus of this adhesive layer 7 is 5 GPa.
When the value exceeds, the rigidity of the protruding portion 7a becomes too high, and the deformation of the piezoelectric actuator 4 located on the flow path 10 is hindered. As a result, the ink pressure in the flow path 10 decreases and the applied voltage is commensurate with the applied voltage. This is because the ink ejection characteristics cannot be obtained, and conversely, the Young's modulus of the adhesive layer 7 is 0.1 G.
If it is less than Pa, the rigidity of the adhesive layer 7 itself becomes too small, and the deformation of the piezoelectric actuator 4 is absorbed by the adhesive layer 7, so that the pressure of the ink in the flow path 10 is reduced and the applied voltage is reduced. This is because a suitable ink ejection characteristic cannot be obtained. The Young's modulus of the adhesive layer 7 is preferably 0.1 GPa to 3.0 GPa.

The width V of the protruding portion 7a of the adhesive layer is set to 0 or more and 1/3 or less of the width W of the flow channel 10 because the width V of the protruding portion 7a of the adhesive layer 7 is set to the flow channel 10. Width of 1 /
When it exceeds 3, the ratio of the protruding portion 7a of the adhesive layer 7 in the flow channel 10 becomes too large, the volume in the flow channel 10 decreases, and the Young's modulus of the protruding portion 7a is 0.1 GPa to 5. Even if it is in the range of 0 GPa, the deformation of the piezoelectric actuator 4 located on the flow channel 10 is hindered, and as a result, the ink pressure in the flow channel 10 decreases,
This is because the ink ejection characteristics matching the applied voltage cannot be obtained, and conversely, the width V of the protruding portion 7a of the adhesive layer 7 is 0.
When it becomes smaller (when there is no protruding portion 7a and the side surface of the adhesive layer 7 is on the same surface as or inside the side surface of the partition wall 5),
Since the area occupied by the adhesive layer 7 is not small, it also affects the deformation of the piezoelectric actuators 4 on the adjacent flow channels 10, causing variations in the ejection characteristics of the ink droplets ejected from the respective flow channels 10. This is because the bonding strength between the partition wall 5 and the piezoelectric actuator 4 is lowered, and the adhesive layer 7 may be peeled off due to the stress acting due to the deformation of the piezoelectric actuator 4. Therefore, it is preferable that the protruding portion 7a of the adhesive layer 7 be The width V is preferably 0 or more and 1/5 or less of the width W of the flow channel 10.

In the present invention, the protrusion 7a of the adhesive layer 7 at the corner formed by the piezoelectric actuator 4 and the partition wall 5 means that in the case of the ink jet recording head 20 shown in FIG. In the longitudinal direction, not only the case where the adhesive layer 7 has the protruding portion 7a over the entire corner portion with the piezoelectric actuator 4 but also the case where the adhesive layer 7 has the protruding portion 7a partially is included.

Further, the width V of the protruding portion 7a of the adhesive layer 7
Is greater than or equal to 0 and less than or equal to 1/3 of the width W of the flow path 10, it is difficult to adjust the amount of protrusion of the adhesive layer 7, and the partition wall 5
Since there is variation in the longitudinal direction of the partition wall 5, it means that the width V of the protruding portion 7a that protrudes is in the range of 0 or more and 1/3 or less of the width W of the flow path 10 in the entire region of the partition wall 5 in the longitudinal direction.

Further, a protruding portion 7a of the adhesive layer 7 is formed at a corner portion formed by the piezoelectric actuator 4 and the partition wall 5.
By providing the adhesive layer, the adhesive area can be increased and the adhesive strength can be improved. Therefore, peeling of the adhesive layer 7 due to the deformation of the piezoelectric actuator 4 can be prevented, and the reliability of the inkjet recording head 20 can be improved. In addition, since the side surface of the protruding portion 7a of the adhesive layer 7 is formed into a curved surface due to the surface tension at the time of curing, even if bubbles that adversely affect the ink ejection characteristics are mixed in the flow channel 10, It is possible to form a structure in which bubbles are unlikely to accumulate in the inside 10.

The Young's modulus after curing of the adhesive layer 7 was measured by pressing a thin film hardness measuring indenter against the adhesive layer 7.

The Young's modulus after curing is from 0.1 GPa to
As the adhesive forming the adhesive layer 7 in the range of 5.0 GPa, a thermosetting adhesive such as phenol resin, epoxy resin, melamine resin, polyurethane resin, acrylic resin or silicone resin can be used.

Further, in order to efficiently convert the deformation of the piezoelectric actuator 4 into a volume change in the flow channel 10 and suppress the stress acting on the adhesive layer 7 and the piezoelectric actuator 4 to be low, the thickness T of the adhesive layer 7 is set. It is preferable to make it as thin as possible, preferably 2 μm to 30 μm, and further 2 μm to 2
The thickness is preferably 0 μm, preferably 2 μm to 10 μm, and more preferably 2 μm to 5 μm.

Next, a method of manufacturing the ink jet recording head 10 of the present invention shown in FIG. 1 will be described.

First, in order to form the flow path member 6, a metal,
Prepare a ceramic sintered body, a single crystal body, or a plate-shaped body made of silicon or glass, etc., and after arranging a plurality of grooves side by side on this plate-shaped body by, for example, grinding or etching, etc. Then, laser processing such as excimer laser or YAG laser or etching processing is performed to perforate the fine holes to form grooves for ink flow paths 10, partition walls for partition walls 5, and fine holes for ink discharge holes 9. The flow path member 6 is manufactured.

The material for forming the plate-like body is not particularly limited, and when a metal is used, for example, stainless steel, titanium, nickel, copper, aluminum alloy or the like can be used, and a ceramic sintered body can be used. When used,
An alumina-based sintered body, a silicon oxide-based sintered body, an aluminum nitride-based sintered body, a silicon nitride-based sintered body, or the like can be used.

Next, in order to form the piezoelectric actuator 4, a piezoelectric ceramic plate 3 made of lead zirconate titanate (PZT), lead magnesium niobate (PMN), lead nickel niobate (PNN) or the like is prepared. Au, Pt, Pd, Ag, on almost the entire one main surface of the piezoelectric ceramic plate 3,
Common electrode 1 made of a metal such as Cr or Ni or an alloy thereof
And the individual electrodes 2 made of a metal such as Au, Pt, Pd, Ag, Cr, or Ni or their alloys are formed on the other main surface of the piezoelectric ceramic plate 3 at a predetermined interval. It is manufactured by applying a voltage between each individual electrode 2 and the common electrode 1 to perform polarization processing.

In forming the common electrode 1 and the individual electrode 2, well-known thin film forming means such as a printing method, a vacuum deposition method, an ion plating method, a sputtering method, a CVD method, a PVD method may be used.

Further, the Young's modulus after curing is 0.1 GPa.
To 5.0 GPa in the range of a thermosetting adhesive such as a phenol resin, an epoxy resin, a melamine resin, a polyurethane resin, an acrylic resin, or a silicone resin as a main agent, and an amine-based or phenol-based curing agent mixed therewith. Prepare an adhesive and apply it to the partition wall top surface of the flow path member 6 with a dispenser, or apply the adhesive to a flexible film such as a polyimide film or PET film for the partition wall 5 of the flow path member 6. As described above, it is applied by screen printing or the like, and is brought into contact with the partition wall top surface of the flow path member 6, and then a roller is pressed against the film and rotated several times to transfer the adhesive to the partition wall top surface. The adhesive may be either a one-component mixed type or a two-component mixed type.

At this time, it is desirable that the viscosity of the adhesive at 23 ° C. be as high as about 2000 cps in consideration of workability so that the adhesive does not hang down on the side wall of the partition wall. The viscosity may be adjusted by mixing a filler such as an inorganic powder or a silane coupling agent with a metallic coupling agent and an organic solvent, or by adjusting the ratio of the main agent of the adhesive to the curing agent.

Next, after the piezoelectric actuator 4 and the flow path member 6 are aligned, the adhesive 7 is heat-cured in a state where they are adhered and pressed to obtain the ink jet recording head 20 shown in FIG.

At this time, the width V of the protruding portion 7a of the adhesive layer 7 is set so that the pressing force applied after the piezoelectric actuator 4 and the flow path member 6 are bonded together is temporarily made higher than a predetermined pressure. And then the adhesive is hardened by applying a predetermined pressure, or after the piezoelectric actuator 4 and the flow path member 6 are bonded together, the adhesive is extruded by applying vibration or centrifugal force. , It should be cured.

Next, another embodiment of the present invention will be described with reference to FIG.
It will be explained based on. Note that FIG. 3 shows only the main part.

In this embodiment, the Young's modulus shown in FIG. 1 is between 0.1 GPa and 5.0 GPa and between the adhesive layer 7 and the top surface of the partition wall. The second adhesive layer 8 having is provided in a range not more than the width of the partition top surface.

As described above, the second adhesive layer having a Young's modulus between the piezoelectric actuator 4 and the top surface of the partition wall is equal to or higher than that of the adhesive layer 7 having a Young's modulus in the range of 0.1 GPa to 5.0 GPa. By providing 8, the rigidity of the adhesive layer between the piezoelectric actuator 4 and the partition wall 5 can be further increased, so that the deformation of the piezoelectric actuator 4 can be prevented from being absorbed by the adhesive layer, The deformation of the piezoelectric actuator 4 corresponding to the applied voltage can be obtained. As a result, the ink pressure applied to the ink in the flow path 10 can be improved, and thus the ink ejection characteristics and responsiveness can be further improved.

As the material forming the second adhesive layer 8, the same kind of adhesive as the adhesive forming the adhesive layer 7 can be used, and the amount of the curing agent added is adjusted or It suffices to add a filler such as an inorganic powder so that the Young's modulus after curing becomes equal to or higher than that of the adhesive layer 7.

In order to obtain an adhesive structure as shown in FIG. 3, an adhesive having a Young's modulus after curing equal to or higher than that of the adhesive layer 7 is applied to the top surface of the partition wall and heat-cured to form a second adhesive. Agent layer 8
After forming, a large amount of an adhesive having a Young's modulus after curing in the range of 0.1 GPa to 5.0 GPa is applied on the adhesive layer 8 and the piezoelectric actuator 4 is bonded while being pressed. At this time, the adhesive is made to stick out to the corner portion between the piezoelectric actuator 4 and the partition wall 5. After that, the adhesive can be obtained by heating and curing the adhesive to form the adhesive layer 7.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, in the ink jet recording head 20 shown in FIG. Although the individual electrode 2 and the common electrode 1 are formed on the upper and lower sides of the plate 1, a laminated piezoelectric actuator in which a plurality of layers of a piezoelectric ceramic layer, a common electrode layer, a piezoelectric ceramic layer, and an individual electrode are integrally laminated is used. By using the laminated piezoelectric actuator in this way, a small voltage
Since a large displacement amount can be obtained, the ejection speed of ink droplets can be improved, which is preferable.

Needless to say, modifications and improvements may be made without departing from the scope of the present invention.

[0046]

(Example) (Example 1) Here, the piezoelectric actuator 4
An experiment was conducted to compare the ejection performance of ink droplets when the inkjet recording head 20 shown in FIG.

In the experiment, the flow path member 6 and the piezoelectric actuator 4 forming the ink jet recording head 20 were manufactured as follows.

First, the flow path member 6 is formed by anisotropically etching a plate-like body made of silicon by arranging 50 grooves having a width of 120 μm, a length of 4 mm and a depth of 300 μm in parallel at a pitch of 240 μm, and A flow path member 6 having a groove as an ink flow path 10, a wall partitioning the groove as a partition wall 5, and a minute hole as an ink discharge hole 9 is formed by drilling a minute hole having a diameter of about 20 μm by laser processing at a predetermined position on the bottom surface. Was produced.

The piezoelectric actuator 4 is 20 mm × 4 m
A piezoelectric ceramic plate 3 made of lead zirconate titanate (PZT) in the form of an m × 0.1 mm plate was prepared, and a common electrode 1 made of an Au—Pd alloy was formed on the entire one main surface.
Is formed by the screen printing method, and the individual electrode 2 made of Au having a width of 80 μm, a length of 1 mm and a thickness of 2 μm is formed on the other main surface by the screen printing method.
After forming 50 pieces at the same interval as above, a direct current voltage was applied between each individual electrode 2 and the common electrode 3 to perform polarization treatment in the plate thickness direction of the piezoelectric ceramic plate 1.

Next, as shown in Table 1, 12 kinds of epoxy adhesives having different Young's moduli after curing within the range of 0.01 GPa to 10 GPa were prepared, and on a flexible polyimide film. After applying a thin and even coating to the channel member 6, the roller is pressed against the polyimide film for several rotations, and then the polyimide film is peeled off to remove the adhesive from the channel member 6. It was transferred to the top surface of the partition wall. Then, after the piezoelectric actuator 4 is aligned, it is attached to the flow path member 6, and the adhesive is heat-cured by holding the both at a temperature of 160 ° C. for about 2 hours while pressing them, to obtain a sample. The inkjet recording head 20 of was manufactured. In each sample, the adhesive layer 7 for bonding the piezoelectric actuator 4 and the partition wall 5 was configured to protrude, and the protrusion width 7a was adjusted to be 1/3 of the width W of the flow channel 10.

Then, using each of the obtained ink jet recording heads 20, an experiment was conducted in which ink droplets were continuously ejected to check the ejection speed of the ink droplets.

Specifically, a drive frequency of 12 kHz is applied between the individual electrode 2 and the common electrode 1 of the piezoelectric actuator 4,
A voltage of 30 V is applied to pressurize the ink in the flow path 10, and the ejection speed of the ink droplets ejected from the ink ejection holes 9 is calculated by measuring the trajectory of the ink droplets using a high-speed video camera and a strobe. . Specifically, the light emission interval of the strobe was set to 1 second, the distance traveled by the ink droplet was measured on the monitor screen photographed by the camera, and the distance was divided by the issuance interval for calculation.

The results are shown in Table 1.

[0054]

[Table 1]

As can be seen from Table 1, when the Young's modulus of the adhesive layer 7 including the protruding portion 7a exceeds 5 GPa, the deformation of the piezoelectric actuator 4 is constrained and the ejection speed of ink droplets is significantly reduced.

If the Young's modulus of the adhesive layer 7 including the protruding portion 7a is less than 0.1 GPa, the deformation of the piezoelectric actuator 4 is absorbed by the adhesive layer 7 and the ejection speed of the ink droplets increases. It can be seen that it drops significantly.

On the other hand, when the Young's modulus of the adhesive layer 7 including the protruding portion 7a is in the range of 0.1 GPa to 5.0 GPa, the deformation of the piezoelectric actuator 4 may be significantly hindered or absorbed. In addition, the ejection speed of the ink droplets was 9.0 m / sec or more, which was excellent. In particular, when the Young's modulus of the adhesive layer 7 including the protruding portion 7a is in the range of 1.0 GPa to 3.0 GPa, the ejection speed of ink droplets could be increased to 10.0 m / sec or more.

As a result, the Young's modulus of the adhesive layer 7 is 0.1 GP in order to prevent the deformation of the piezoelectric actuator 4 from being absorbed and to improve the ejection characteristics of the ink droplets.
It is understood that it may be formed with an adhesive in the range of a to 5.0 GPa. (Example 2) Next, the sample No. In the ink jet recording head 20 using the adhesive layer 7 having a Young's modulus after curing of 2 GPa as shown in 6, the variation in the ejection speed of ink droplets when the width V of the protruding portion 7a of the adhesive layer 7 is changed An experiment was carried out under the same conditions as in Example 1. The width V of the protruding portion 7a of the adhesive layer 7 was adjusted by the amount of the adhesive applied to the top surface of the partition wall 5.

The results are shown in Table 2.

[0060]

[Table 2]

As can be seen from Table 2, when the width V of the protruding portion 7a of the adhesive layer 7 exceeds 1/3 of the width W of the flow channel 10,
It became difficult to maintain the ink droplet ejection speed of 9.0 m / sec or more, and the variation was large. It is considered that this is because the volume in the channel 10 becomes too small and the channel resistance becomes large.

On the other hand, the protruding portion 7a of the adhesive layer 7
By setting the width V of the ink droplet to be larger than 0 and not more than 1/3 of the width W of the flow path 10, it is possible to maintain the ejection speed of the ink droplets of 9.0 m / sec or more and reduce its variation. I was able to.

As a result of the first and second embodiments, in order to prevent the deformation of the piezoelectric actuator 4 from being hindered or absorbed, the ejection speed of the ink droplet can be increased, and the ejection can be performed more stably, the adhesive agent is used. The width V of the protruding portion 7a of the layer 7 is set to 0.
The width is set to be 1/3 or less of the width W of the flow path 10 and the Young's modulus of the adhesive layer 7 is 0.1 GPa to 5.0 GP.
It turns out that it is good to use a. (Embodiment 3) Next, as a bonding structure between the piezoelectric actuator 4 of the ink jet recording head 20 shown in FIG. 1 and the partition wall 5 of the flow path member 6, as shown in FIG. 3, two kinds of bonding having different Young's moduli after curing are used. The thing using the agent layer was prepared, and the same experiment was conducted under the same conditions as in Example 1.

The combinations of adhesive layers and the results are shown in Table 3.

[0065]

[Table 3]

As can be seen from Table 3, the adhesive layer 7 has the Young's modulus of the second adhesive layer 8 which has the protruding portion 7a.
When the Young's modulus was smaller than the Young's modulus, the ejection speed of the ink droplets decreased.

On the other hand, by setting the Young's modulus of the second adhesive layer 8 to be equal to or more than the Young's modulus of the adhesive layer 7 having the protruding portion 7a, the ejection speed of ink droplets of 9.0 m / sec or more. I was able to get

As a result, when the piezoelectric actuator 4 and the partition top surface are joined by the two adhesive layers 7 and 8, the Young's modulus of the adhesive layer 7 on the piezoelectric actuator 4 side is 0.1 G.
It is preferable that the Young's modulus of the adhesive layer 8 on the partition wall top surface side is equal to or more than the Young's modulus of the adhesive layer 7 while providing the protruding portion 7a of the adhesive layer 7 in addition to Pa to 5.0 GPa. I understand.

[0069]

As described above in detail, according to the ink jet recording head of the present invention, a plurality of partition walls are arranged in parallel, and a flow path member having a flow path for ink between the partition walls and the above flow paths are provided. In an ink jet recording head having a piezoelectric actuator that is bonded to a partition wall top surface of a flow path member via an adhesive layer and an ink discharge hole that communicates with each flow path, a corner between the piezoelectric actuator and each partition wall The protruding portion of the adhesive layer is formed in the portion, and the width of the protruding portion is 0 or more and 1/3 or less of the width of the flow path, and the Young's modulus of the adhesive layer is 0.1 GPa to 5.0 GPa. By doing so, it is possible to prevent the deformation of the piezoelectric actuator or prevent the piezoelectric actuator from being absorbed, and it is possible to make the deformation commensurate with the applied voltage. Therefore, it is possible to increase the ink pressure in the flow path. Ejection characteristics (ejection speed, ejection amount) of ink droplets can be improved, and obtained stable discharge characteristics, as a result, it is possible to perform clean and accurate, clear printing.

The Young's modulus of the adhesive layer is 0.1 GPa.
To 3.0 GPa, or by providing a second adhesive layer having a Young's modulus equal to or higher than that of the adhesive layer between the adhesive layer and the top surface of the partition wall, the responsivity is enhanced and ink droplets are increased. It is possible to further improve the ejection characteristics of.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of an inkjet recording head of the present invention.

2A and 2B are partially enlarged sectional views for explaining the driving principle of the inkjet recording head of the present invention.

FIG. 3 is a partially enlarged cross-sectional view for explaining another example of the inkjet recording head of the present invention.

FIG. 4 is a partially cutaway perspective view showing an example of a conventional inkjet recording head.

[Explanation of symbols]

1,21: Piezoelectric ceramic plate 2,22: Individual electrodes 3, 23: common electrode 4, 24: Piezoelectric actuator 5,25: Partition wall 6, 26: flow path member 7, 27: Adhesive layer 7a, 27a: protruding portion of the adhesive layer 8: Second adhesive layer 9, 29: Ink ejection holes 10, 30: flow path 20, 40: Inkjet recording head

Claims (3)

[Claims] 1. A flow path member in which a plurality of partition walls are provided in parallel, and each partition wall has an ink flow path, and a partition wall top surface of the flow path member and an adhesive layer are interposed so as to close each flow path. In an ink jet recording head having a piezoelectric actuator bonded to each other and an ink ejection hole communicating with each of the flow paths, a protrusion portion of the adhesive layer is provided at a corner portion of the piezoelectric actuator and each partition wall, and the protrusion portion is provided. Is 0 or more and 1/3 or less of the width of the flow path, and the Young's modulus of the adhesive layer is in the range of 0.1 GPa to 5.0 GPa. 2. The Young's modulus of the adhesive layer is 1.0 GPa.
The inkjet recording head according to claim 1, which is in a range of 3.0 GPa. 3. The ink jet recording according to claim 1, wherein a second adhesive layer having a Young's modulus equal to or higher than that of the adhesive layer is provided between the adhesive layer and the partition wall. head.