JP2003110159A - Stuck structure between piezoelectric ceramics sheets, and ink jet recording head using the structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that when two piezoelectric ceramic sheets 2, 3 with different thicknesses which form a stuck structure 1 are stuck through a bonding layer 4, there happens the contraction of a bonding agent, and further happen the deflection of an external periphery of the stuck structure 1 and the waviness of the same depending upon the direction of polarization processing of the piezoelectric ceramic sheets 2, 3. SOLUTION: When a thinner piezoelectric ceramic sheet 2 and a thicker piezoelectric ceramic sheet 3 both forming a stuck structure 1 are stuck via a bonding agent layer 4, the surface roughness of the surface of the thinner piezoelectric ceramic sheet on the opposite side at least to the bonded surface of the same sheet is less than 1 μm in terms of arithmetic mean roughness (Ra), and polarization processing is applied to the respective piezoelectric ceramic sheets 2, 3 from the surfaces 2b, 3b on the opposite side to the bonded surfaces 2a, 3a toward the bonded surfaces 2a, 3a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated structure of piezoelectric ceramics, which is formed by laminating two piezoelectric ceramic plates which are polarized and have different thicknesses via an adhesive layer, and an ink jet recording using the same. It is about the head.

[0002]

2. Description of the Related Art Conventionally, a pasting structure in which electrode layers and piezoelectric ceramic plates are alternately laminated has been used for actuators and buzzers. In particular, regarding actuators, position control in the submicron order has been required in recent years in the fields of precision processing and optics, and the inverse piezoelectric effect and electrostrictive effect that occur when an electric field is applied to piezoelectric ceramics for this position control. The one utilizing the displacement based on is often used, and for example, it has been recently used for an inkjet recording head.

In order to manufacture such a laminated structure, for example, two piezoelectric ceramic plates containing lead zirconate titanate or the like, which has been subjected to a polarization treatment in advance, as a main component are prepared, and the respective piezoelectric ceramic plates are bonded together. After the surface is lap-polished or surface-ground to make it flat, one of the piezoelectric ceramic plates is bonded to the adhesive surface by a squeegee method, a screen printing method, an offset printing method, etc. After the paste is applied, the other piezoelectric ceramic plate is attached and the adhesive is hardened to manufacture it.

On the other hand, as shown in FIG. 7, an ink jet recording head using a structure in which piezoelectric ceramics are adhered to each other is mainly composed of lead zirconate titanate or the like which has been subjected to polarization treatment in advance. The piezoelectric ceramic plates 44 and 45 are prepared, and the bonding surface of each piezoelectric ceramic plate is flattened by lapping or surface grinding, and then the squeegee is attached to the bonding surface of the thick piezoelectric ceramic plate 45. Method, screen printing method, offset printing method or the like, and then a paste of thermosetting adhesive is applied, and the other thin piezoelectric ceramic plate 44 is attached so that the polarization directions of the piezoelectric ceramic plates 44 face each other. After the bonding, the adhesive is heated and cured while applying pressure to manufacture the pasting structure 43, and then the pasting structure 43 is thinned from the piezoelectric ceramic plate 44 side. A plurality of grooves, one end of which is open to the middle of the piezoelectric ceramic plate 45, are engraved by a diamond wheel so that each groove serves as an ink flow path 33 and a partition wall for partitioning each groove serves as a partition wall 32. The path member 31 is manufactured, and thereafter, the vapor deposition method, the sputtering method,
A driving electrode 34 made of a metal film is formed on a side surface of the partition wall 32 by a thin film forming means such as a CVD method, and a lead wire 39 of the driving electrode made of a metal film is formed on the top surface of the flow path member 31, Then, a paste of a thermosetting adhesive is applied to the top surface of the flow path member 31 by a method such as a squeegee method, a screen printing method, an offset printing method, and a top plate 35 having an ink supply hole 36 is attached. After the combination, the adhesive is heated to cure the adhesive, and the end face of the flow path member 31 is coated with a thermosetting adhesive paste by a method such as a squeegee method, a screen printing method, an offset printing method, and the ink is ejected. In some cases, the nozzle plate 38 having the holes 37 is attached and then heated to cure the adhesive.

Then, the ink jet recording head 4
To print on a recording medium (not shown) using 0, first,
Ink is supplied from an ink tank (not shown) to each flow path 33 through an ink supply hole 35, and a drive electrode 34 is also provided.
Is energized to cause the piezoelectric ceramics forming the wall members 41 and 42 of the partition wall 32 to undergo shear mode deformation to bend and displace the partition wall 32, thereby pressurizing the ink in the flow path 33,
Ink droplets are ejected from the ink ejection holes 37 to print on a recording medium (not shown).

[0006]

However, when the two piezoelectric ceramic plates forming the pasting structure have different thicknesses, due to the shrinkage of the paste generated when the adhesive is cured,
There has been a problem that the outer peripheral portion of the thicker piezoelectric ceramic plate is warped toward the adhesive layer side, and as a result, the entire pasting structure is warped. In addition, when the piezoelectric ceramic plate is subjected to polarization treatment from the bonding surface to the surface opposite to the bonding surface, there is a problem that the warp of the pasting structure is further increased.

Further, the thin piezoelectric ceramic plate subjected to the polarization treatment easily causes undulation, and when the piezoelectric ceramic plate having the undulation is attached to the thick piezoelectric ceramic plate, the thin piezoelectric ceramic plate causes the undulation. There is a problem in that the adhesive layer is stuck while being held, and the thickness of the adhesive layer cannot be made uniform.

Therefore, when the ink jet recording head 40 as shown in FIG. 7 is manufactured by using the pasting structure having such warpage and undulation, one partition 32 has
For example, the height of the wall members 41 and 42 and the thickness of the adhesive layer 46 that form the partition wall 32 near the ink ejection hole 37 and near the center are different, and it becomes impossible to eject ink droplets at the original ejection speed. In the juxtaposed direction, the height of the wall members 41 and 42 forming the partition wall 32 located at the end and the thickness of the adhesive layer 46, and the height and adhesion of the wall members 41 forming the partition wall 32 located near the center. Since the thicknesses of the layers 46 are different, the ejection characteristics of the ink droplets ejected from the ink ejection holes 37 located at the ends and the ejection characteristics of the ink droplets ejected from the ink ejection holes 37 located near the center can vary. There is a problem that the discharge speed and the discharge amount cannot be controlled.

[0009]

In view of the above problems, the present invention relates to a bonded structure in which two piezoelectric ceramic plates having different thicknesses are bonded to each other via an adhesive layer. The surface roughness on the surface opposite to the adhesive surface is set to 1 μm or less in terms of arithmetic average roughness (Ra), and each piezoelectric ceramic plate is polarized by the surface opposite to the adhesive surface toward the adhesive surface. It is characterized by being applied.

Further, the present invention uses the above-mentioned laminated structure of piezoelectric ceramics, and engraves a plurality of grooves from the thin piezoelectric ceramic plate side of this laminated structure to the middle of the thick piezoelectric ceramic plate, Each channel is used as an ink channel, and a channel member having a partition wall for partitioning each groove is manufactured, and a drive electrode is formed on a side surface of each partition wall of the channel member. It is characterized in that an ink jet recording head is constituted by joining nozzle plates having ink ejection holes communicating with each flow path.

In the present invention, "to perform the polarization treatment from the surface opposite to the adhesive surface toward the adhesive surface" means that a positive voltage is applied to the surface opposite to the adhesive surface of the piezoelectric ceramic plate. It means that a negative voltage is applied to each side to perform polarization processing.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

FIG. 1 is a partially cutaway perspective view showing an example of a laminated structure of piezoelectric ceramics of the present invention.

The pasting structure 1 is formed by thermosetting a thin piezoelectric ceramic plate 2 which is pre-polarized and a piezoelectric ceramic plate 3 which is pre-polarized and thicker than the piezoelectric ceramic plate 2. The surface roughness of at least the thin piezoelectric ceramic plate 2 on the surface 2b opposite to the bonding surface 2a is 1 μm or less in terms of arithmetic average roughness (Ra). In addition, the bonding surfaces 2a and 3 are attached to the piezoelectric ceramic plates 2 and 3, respectively.
Polarization processing is applied from the surfaces 2b and 3b on the side opposite to a toward the adhesive surfaces 2a and 3a.

The adhesive layer 4 of the pasting structure 1 is formed of a conductive adhesive, and the surface 2 of each piezoelectric ceramic plate 2, 3 opposite to the adhesive surfaces 2a, 3a.
Metals such as platinum, gold, palladium, rhodium, nickel and aluminum are deposited on b and 3b by vapor deposition or plating.
Alternatively, by forming an electrode layer made of an alloy mainly composed of platinum-gold, palladium-silver, platinum-palladium, etc., and applying a voltage between the electrode layer and the adhesive layer, it can be used as an actuator that vertically vibrates. In addition, it can be used as an actuator capable of strain vibration by forming the above electrode layers on both main surfaces of a thin plate obtained by cutting the pasting structure 1 in the thickness direction and applying a voltage between both electrode layers. it can.

In order to manufacture such a bonded structure 1, a substrate made of sintered piezoelectric ceramics is prepared, and double-sided lap using silicon carbide particles having a particle size of 5 to 10 μm as loose abrasive particles. Having a predetermined thickness by performing lapping by a lapping machine or by performing a surface grinding by a surface grinding machine using a diamond wheel having a diamond abrasive having a grain size of 5 to 10 μm and having a predetermined thickness and at least an adhesive surface 2a. The piezoelectric ceramic plate 2 is manufactured in which the surface roughness on the opposite surface 2b is 1.0 μm or less in terms of arithmetic average roughness (Ra).

A substrate made of sintered piezoelectric ceramics is prepared separately, and the free abrasive grains have a particle size of 5 to 10 μm.
Piezoelectric polishing is performed by lapping with a double-sided lapping machine using m silicon carbide particles, or by surface grinding with a surface grinding machine using a diamond wheel with diamond abrasive grains having a particle size of 5 to 10 μm. The piezoelectric ceramic plate 3 thicker than the ceramic substrate is manufactured.

Next, an electrode layer of silver or the like is formed on each of the bonding surface 2a of the thin piezoelectric ceramic plate 2 and the surface 2b opposite to the bonding surface 2a, and the bonding surface 2 is immersed in silicone oil.
A positive voltage is applied to the electrode layer formed on the surface 2b on the side opposite to a.
After a negative voltage is applied to the electrode layers formed on the bonding surface 2a to apply an electric field of 1.0 to 3.0 kV / mm between both electrode layers, polarization is performed, and then both electrode layers are removed. . Similarly, an electrode layer made of silver or the like is formed on each of the bonding surface 3a of the thick piezoelectric ceramic plate 3 and the surface 3b opposite to the bonding surface 3a, and the surface 3b opposite to the bonding surface 3a.
A positive voltage is applied to the electrode layers formed in step 1 and a negative voltage is applied to the adhesive surface 3a to perform polarization treatment, and then both electrode layers are removed.
Then, a paste of thermosetting adhesive is applied to the bonding surface 3a of the thick piezoelectric ceramic plate 3, and then the bonding surface 2a of the thin piezoelectric ceramic plate 2 is bonded to the bonding surface 3a of the substrate 3.
It can be obtained by heating and curing the adhesive while pressurizing it, after stacking it.

According to the pasting structure 1 of the present invention,
As described above, the piezoelectric ceramic plate 3 having a large thickness is subjected to the polarization treatment from the surface 3b opposite to the bonding surface 3a toward the bonding surface 3a, and the piezoelectric ceramic plate 2 having a small thickness is also treated with the bonding surface 2a. It is characterized in that it is subjected to polarization treatment from the surface 2b on the opposite side to the adhesive surface 2a.

That is, the bonding surfaces 2a, 3 of the thin piezoelectric ceramic plate 2 (without polarization treatment) and the thick piezoelectric ceramic plate 3 (without polarization treatment) that form the pasting structure 1 are formed.
When a paste of a thermosetting adhesive is interposed between a and heat-cured while applying pressure, the adhesive contracts, and contraction stress is generated especially on the bonding surface 3a side of the piezoelectric ceramic plate 3 to bond the piezoelectric ceramic plate 3. Tensile stress acts on the surface 3b opposite to the surface 3a, and the outer peripheral portion of the sticking structure 1 warps toward the thin piezoelectric ceramic plate 2 side as shown in FIG.

On the other hand, the piezoelectric ceramic plate 2 having a small thickness and the piezoelectric ceramic plate 3 having a large thickness are subjected to a polarization treatment in order to exert the piezoelectric effect. After polarization, as shown in FIG. 3, the outer peripheral portions of the piezoelectric ceramic plates 2 and 3 tend to warp in the direction opposite to the polarization direction from the positive pole side to the negative pole side of the voltage.

Therefore, the inventor of the present invention pays attention to both of these phenomena and attaches the bonding surfaces 2a and 3 to the piezoelectric ceramic plates 2 and 3, respectively.
By performing a polarization process from the surfaces 2b and 3b on the side opposite to a toward the bonding surfaces 2a and 3a, the force to bend the outer peripheral portion of each piezoelectric ceramic plate 2 and 3 toward the bonding surface side by the polarization process and the bonding process. It was found that the force to warp the patch structure 1 with the contraction of the agent was offset and the patch structure 1 with less warpage was obtained as shown in FIG.

Further, in the polarization treatment of the piezoelectric ceramic plates 2 and 3, the degree of polarization is increased by increasing the strength of the electric field, and as a result, the degree of warpage is also increased. Therefore, it is possible to further reduce the warp of the pasting structure 1 by controlling the electric field strength applied during the polarization treatment within a range that does not impair the piezoelectric characteristics of the piezoelectric ceramics.

However, in order to fully exert the piezoelectric effect of the piezoelectric ceramics in the pasting structure 1, not only the polarization direction applied to each piezoelectric ceramic plate 2 and 3 is set, but also the thin piezoelectric ceramic plate 2 It is important that at least the surface roughness of the surface 2b opposite to the adhesive surface 2a is 1 μm or less in terms of arithmetic average roughness (Ra).

That is, if the surface roughness of the surface 2b of the piezoelectric ceramic plate 2 having a small thickness opposite to the bonding surface 2a is rough, the tensile stress generated by the polarization treatment does not occur uniformly over the entire surface, and is locally generated. This is because the load causes a warp with undulations.

According to an experiment conducted by the present inventor, the surface roughness on the surface 2b of the piezoelectric ceramic plate 2 having a small thickness opposite to the bonding surface 2a is 1.0 in terms of arithmetic mean roughness (Ra).
When it exceeds μm, it is found that the warpage accompanied by undulation cannot be sufficiently eliminated, and the surface roughness on the surface 2b of the piezoelectric ceramic plate 2 opposite to the bonding surface 2a is calculated as the arithmetic mean roughness (R
By setting the thickness to 1.0 μm or less in a), the tensile stress can be uniformly generated on the entire surface 2b of the piezoelectric ceramic plate 2 opposite to the adhesive surface 2a, and the degree of waviness can be reduced. The present invention has been completed based on the finding that the sticking structure 1 having a uniform thickness can be obtained by sticking it to the thick piezoelectric ceramic plate 3 and the sticking structure 1 with less warpage can be obtained.

Piezoelectric ceramic plate 2 which is preferably thin
The surface roughness of the surface 2b opposite to the adhesive surface 2a is preferably 0.5 μm or less in terms of arithmetic average roughness (Ra). By doing so, the warp of the pasting structure 1 is further reduced. be able to.

The surface roughness of the bonding surfaces 2a and 3a of the piezoelectric ceramic plates 2 and 3 is preferably 0.1 to 1.0 μm in terms of arithmetic average roughness (Ra) in order to obtain adhesive strength. . Further, the surface roughness of the surface 3b of the thick piezoelectric ceramic plate 3 on the side opposite to the bonding surface 3a is not particularly limited, but in order to obtain a stable displacement of the pasting structure 1, an arithmetic operation is performed. Average roughness (R
It may be 5 μm or less in a).

The material of the piezoelectric ceramic plates 2 and 3 forming the pasting structure 1 is not particularly limited, and zirconate titanate, which is generally used as a vibration source for actuators, buzzers and the like. Lead (PZT
System), lead titanate (PT system), or these as the main components, and Mg, Nb, Ni, Z for increasing the piezoelectric constant and the like.
It is possible to use piezoelectric ceramics in which at least one or more of n, Sb, Te, Sr, Ba and the like are substituted.

The size of the piezoelectric ceramic plates 2 and 3 varies depending on the application. For example, in the case of a square plate, it is 10 m.
m-250 mm x 20 mm-300 mm x thickness 0.1 m
A substrate having a size of m to 3 mm may be used.

Further, as the thermosetting adhesive for forming the adhesive layer 4, an epoxy adhesive, a polyimide adhesive,
A general thermosetting adhesive such as a phenol-based adhesive can be used, and among them, an epoxy-based adhesive that can obtain high adhesive strength is preferable.

Next, as an application example, an ink jet recording head formed by using the sticking structure 1 of the present invention will be described with reference to FIGS. 5 and 6A and 6B.

FIG. 5 is a partially cutaway perspective view showing an example of an ink jet recording head using the laminated structure of piezoelectric ceramics of the present invention, and FIGS. 6 (a) and 6 (b) are the ink jet recording shown in FIG. FIG. 6 is a partial cross-sectional view for explaining the driving principle of the head.

In this ink jet recording head 10, a plurality of grooves whose one end is opened from the thin piezoelectric ceramic plate 2 side to the middle of the thick piezoelectric ceramic plate 3 are formed in the sticking structure 1 shown in FIG. By engraving with a wheel, each groove serves as an ink flow path 13, and a wall partitioning each groove serves as a partition wall 12
1 is manufactured, and then vapor deposition method, sputtering method, CV
The flow path 1 including the side surface of the partition wall 12 by a thin film forming means such as D method.
The driving electrode 14 is formed on the surface of No. 3, and the lead wire 19 of the driving electrode 14 is formed on the top surface of the flow path member 11.

The material for forming the driving electrode 14 and the lead wire 19 thereof is platinum, gold, palladium, rhodium,
Metals such as nickel and aluminum, or platinum-gold,
An alloy mainly composed of palladium-silver, platinum-palladium or the like may be used.

Next, a thermosetting adhesive paste is applied to the top surface of the flow path member 11 by a method such as a squeegee method, a screen printing method, an offset printing method, etc., and the ink supply holes 16 are formed.
The top plate 15 provided with is bonded and heated to cure the adhesive, and the open end surface of the flow path member 11 is coated with a thermosetting adhesive by a method such as a squeegee method, a screen printing method, an offset printing method, or the like. Apply paste to the ink ejection holes 17
The nozzle plate 18 provided with is bonded and heated to cure the adhesive.

Although not shown, the driving electrode 14
Since the ink is easily corroded by the ink, it is preferable that the flow path 13 is covered with a protective film made of a resin film such as polyparaxylylene or a silicon nitride film so as to cover the driving electrode 14.

To print on a recording medium (not shown) using this head 10, first, ink is introduced from an ink tank (not shown) into each flow path 13 through the ink supply hole 15, and As shown in FIG.
a negative voltage is applied to the driving electrode 14b formed in the channel b.
Driving electrodes 14 respectively formed in 3a and 13c
When a positive voltage is applied to each of a and 14c, each wall member 21 and 2 that forms the partition walls 12a and 12b that partition the flow path 13b.
The piezoelectric ceramics No. 2 undergoes shear mode deformation, and the partition walls 12a and 12b are bent and displaced toward the flow path 13b in a substantially V shape, so that the ink in the flow path 13b is pressurized and ink droplets are ejected from the ink ejection holes 17. Can be discharged,
As shown in FIG. 6B, when the polarities of the voltages applied to the driving electrodes 14b and the driving electrodes 14a and 14c are reversed, the partition walls 12a and 12b are bent and displaced toward the flow paths 13a and 13c, respectively. The inside of the flow path 13b is decompressed, ink can be supplied from the ink supply hole 15, and ink droplets can be appropriately ejected by repeating these operations.

According to the ink jet recording head 10 of the present invention, when the flow path member 11 is manufactured, it is formed from the pasting structure 1 which is free from warpage and undulation and has a very small variation in the thickness of the adhesive layer. , Each partition 12
Since the heights of the wall members 21 and 22 forming the ink and the thickness of the adhesive layer 4 can be made uniform in the longitudinal direction thereof, the ejection characteristics of the ink droplets ejected from the ink ejection holes 17 (ejection speed, ejection amount). In addition, it is possible to significantly improve the dispersion of the ejection characteristics (ejection speed, ejection amount) of the ink droplets ejected from the respective ink ejection holes 17.

Although the embodiment of the present invention has been described above, the present invention is not limited to the sticking structure 1 shown in FIG. 1 and the ink jet recording head 10 shown in FIG. 5, and deviates from the gist of the present invention. It goes without saying that improvements and changes may be made as long as they are within the range not covered.

[0041]

(Example 1) Here, in a bonding structure in which two piezoelectric ceramic plates having different thicknesses are bonded to each other via an adhesive layer made of a thermosetting adhesive, Experiments were conducted to examine the magnitude of warpage and the presence of undulations when the surface roughness of the thin piezoelectric ceramic plate on the side opposite to the adhesive surface was varied.

Specifically, lead zirconate titanate (PZ
Two piezoelectric ceramic plates with a thickness of 1.5 mm, which consist of piezoelectric ceramics whose main component is T), are coated with silver electrode layers on the upper and lower surfaces of these substrates, respectively, and electricity is applied between the electrode layers. By applying an electric field of 2.0 kV / mm in the substrate thickness direction to perform polarization treatment, the upper and lower electrode films are removed, and further lapping is performed using silicon carbide abrasive grains having a grain size of 5 μm. External dimensions are 50 mm x 50 mm
Then, a piezoelectric ceramic plate having a plate thickness of 0.2 mm and a piezoelectric ceramic plate having a plate thickness of 0.7 mm in which the surface roughness on the surface opposite to the adhesive surface was varied as shown in Table 1 were produced.

Next, an epoxy adhesive (trade name: EPOTEK) is attached to the bonding surface of the piezoelectric ceramic plate having a plate thickness of 0.7 mm.
353-ND) is applied by a transfer method, and then the plate thickness is 0.2.
mm piezoelectric ceramic plates are pasted together and the pressure is reduced under a pressure of 8 KPa in a vacuum chamber.
By heat treating at a temperature of 00 to 150 ° C. to cure the epoxy adhesive, a sticking structure as a sample was manufactured, and the obtained sticking structure was measured for warpage and undulation.

It should be noted that the size of the warp of the piezoelectric ceramic plate and the presence or absence of undulations, and the size of the warp of the pasting structure are determined by using a surface roughness measuring machine and the diagonal line on the surface of the piezoelectric ceramic plate and the pasting structure. Measured from the shape of the surface roughness curve at the measurement length of 50 mm above, the magnitude of the warp is measured at the top (measurement start point or end point) and the bottom (measurement center or substrate center) of the surface curve. The difference between the heights of (near). Also,
The undulation was judged based on whether or not the shape of the surface curve was observed.

The respective results are shown in Table 1.

[0046]

[Table 1]

As a result, as can be seen from Table 1, sample N
o. 1 to 7 on a thick piezoelectric ceramic plate,
If polarization treatment is applied from the surface (positive voltage) opposite to the bonding surface to the bonding surface (negative voltage), the sample No. 8 to 1
As shown in 0, on the piezoelectric ceramic plate, the bonding surface (positive voltage)
From this, it is understood that the warp of the pasting structure can be significantly reduced as compared with the case where the polarization treatment is performed toward the surface opposite to the adhesive surface (negative voltage).

However, the sample No. When the surface roughness on the surface opposite to the adhesive surface of the thin piezoelectric ceramic plate exceeds 1.0 μm in terms of arithmetic average roughness (Ra) as in Nos. 5 to 7, the piezoelectric ceramic plate is warped with waviness. Occurs, and as a result, the bonded structure in which the piezoelectric ceramic plates are bonded together has a large warp.

On the other hand, sample No. As shown in 1 to 4, each piezoelectric ceramic plate is polarized from the surface (positive voltage) opposite to the bonding surface to the bonding surface (negative voltage), and The surface roughness on the surface opposite to the adhesive surface is calculated as the arithmetic mean roughness (R
When the thickness is 1.0 μm or less in a), the warp and waviness of the pasting structure can be made extremely small, which is excellent.

As a result, on each piezoelectric ceramic plate, from the surface opposite to the bonding surface (positive voltage) to the bonding surface (negative voltage).
If the surface roughness of the surface of the thin piezoelectric ceramic plate on the side opposite to the adhesive surface is 1.0 μm or less in terms of arithmetic average roughness (Ra), it will be attached with less waviness and warpage. It turns out that the structure can be obtained.

(Example 2) Next, the sample No. 2,
An ink jet recording head was manufactured using the sticking structures of 5 and 8, and the speed of ink droplets ejected from 20 ink ejection holes was measured in each head,
The average velocity and variation in velocity of ink drops were measured.

Specifically, a diamond wheel having diamond abrasive grains with a grain size of 5 μm fixed from the surface side of the thin piezoelectric ceramic plate forming each pasting structure is used, and the processing speed is set to 5 mm / sec. On the other hand, by forming 3000 grooves on the other hand, each groove was used as an ink flow path, and a flow path member having a partition wall for partitioning each groove was manufactured. The depth of each channel is 300μ.
m, the width of each flow path was 75 μm, and the pitch was 141 μm.

After that, after masking the necessary portions of each flow path member, a driving electrode made of an aluminum film is formed on the entire inner wall surface of the flow path by the sputtering method, and the flow path is formed from the end of the flow path. Leader lines made of an aluminum film, which communicate with the respective drive electrodes, were formed to the rear end of the member.

Thereafter, a top plate made of alumina ceramics having an ink supply hole for introducing ink is provided on the top surface of each partition wall, and an ink discharge hole for discharging ink is provided on the open end side of the flow path member. An ink jet recording head as a sample was produced by adhering nozzle plates made of a polyimide resin provided with the above with a thermosetting epoxy adhesive.

Then, a voltage of 30 V is applied to the driving electrode of each of the obtained ink jet recording heads to form a partition wall of 8 k.
The velocity of the ink droplets ejected from the 20 ink ejection holes was measured by displacing at a frequency of Hz, and the average velocity of the ink droplets and the velocity variation were calculated. The variation in the velocity of the ink droplet was calculated by the standard deviation of the velocity of the ink droplet ejected from the ink ejection hole.

The respective results are shown in Table 2.

[0057]

[Table 2]

As a result, as can be seen from Table 2, in the ink jet recording head formed by using the sticking structure of the present invention, since the sticking structure has less waviness and warpage, the height of the wall member forming each partition wall is high. Since the thickness variation of the adhesive layer and the thickness of the adhesive layer are small and can be made uniform, the velocity average value of the ink droplets ejected from each ink ejection hole is as large as 7.0 m / s or more, and the velocity variation of the ink droplets is large. 0.1 m
It was suppressed to within / s, and the ink droplet ejection characteristics were very excellent.

[0059]

As described above, according to the present invention, there is provided a bonding structure in which two piezoelectric ceramic plates having different thicknesses are bonded to each other via an adhesive layer, and at least the bonding surface of each piezoelectric ceramic plate described above. The surface roughness of the surface on the opposite side is 1 μm or less in terms of arithmetic mean roughness (Ra), and each piezoelectric ceramic plate is subjected to polarization treatment from the surface opposite to the bonding surface toward the bonding surface. As a result, it is possible to provide a pasting structure with less warpage and undulation.

Further, a plurality of grooves are formed from the thin piezoelectric ceramic plate side of the pasting structure to the middle of the thick piezoelectric ceramic plate, and each groove is used as an ink flow path, and each groove is formed. A nozzle plate having a partition wall as a partition wall, a drive electrode formed on a side surface of each partition wall of the flow path member, and an ink discharge hole communicating with each flow path in the flow path member. Since the ink jet recording head is configured by joining the ink droplets, the ejection characteristics of the ink droplets can be improved, and the speed variation of the ink droplets ejected from each ink ejection hole can be made extremely small. A high inkjet recording head can be provided.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of an attachment structure made of piezoelectric ceramics of the present invention.

FIG. 2 is a cross-sectional view showing a pasting structure made of piezoelectric ceramics of the present invention.

FIG. 3 is a sectional view showing a warped state of a polarized piezoelectric ceramic plate.

FIG. 4 is a cross-sectional view showing a state in which a thick piezoelectric ceramic plate that is not polarized and a thin piezoelectric ceramic plate are bonded together with an adhesive.

FIG. 5 is a partially cutaway perspective view showing an example of an ink jet recording head using a pasting structure made of the piezoelectric ceramics of the present invention.

6A and 6B are partial cross-sectional views for explaining the driving principle of the inkjet recording head shown in FIG.

FIG. 7 is a partially cutaway perspective view showing a conventional inkjet recording head.

[Explanation of symbols]

1,43: Bonding structure 2,43: Thin piezoelectric ceramic plate 2a: Adhesive surface 2b: Surface opposite to adhesive surface 3,45: Thick piezoelectric ceramic plate 3a: Adhesive surface 3b: Opposite adhesive surface Surface on the side 4: Adhesive layers 10, 40: Inkjet recording head 11, 31:
Flow path members 12, 32: Partition wall 13, 33: Pressurizing chamber 14, 34:
Driving electrodes 15, 35: ink supply holes 16, 36: top plate 17,
37: Ink ejection holes 18, 38: Nozzle plate 19, 39: Lead lines 21, 22, 41, 42: Wall member

Claims (2)

[Claims] 1. A laminated structure in which two piezoelectric ceramic plates having different thicknesses are bonded to each other via an adhesive layer, and the surface roughness of at least the surface opposite to the adhesive surface of the thin piezoelectric ceramic plate is The arithmetic mean roughness (Ra) is set to 1 μm or less, and each piezoelectric ceramic plate is subjected to polarization treatment from the surface opposite to the bonding surface toward the bonding surface. Attachment structure. 2. A plurality of grooves are engraved from the thin piezoelectric ceramic plate side of the laminated structure of piezoelectric ceramics according to claim 1 to the middle of the thick piezoelectric ceramic plate. A flow path member having a partition as a flow path and a wall partitioning each groove, a driving electrode provided on a side surface of each partition wall, and an ink discharge joined to the flow path member and communicating with each flow path An ink jet recording head comprising a nozzle plate having holes.