JP2001191541A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head which is not deformed with respect to bending displacement of a partition wall even when a thickness of a nozzle plate is reduced and has the superior ink ejection performance by preventing position shift of an ink ejection nozzle when the nozzle plate is bonded to a fluid passage member. SOLUTION: A plurality of partition walls 2 each made of a piezoelectric ceramic having a driving electrode 3 are juxtaposed. The nozzle plate 4 having the ink ejection nozzles 5 each made from an Ni-Co alloy or an Ni-Fe alloy is bonded to the top faces of the partitions 2 of fluid passage members 1 forming fluid passages 7 for the ink each provided between the respective two partitions 2, thereby forming the ink jet recording head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various printers and recorders for printing characters and images by ejecting ink droplets from fine ink ejection holes, and printing machines used for pattern formation in the printing and ceramic fields. The present invention relates to an ink jet recording head mounted on a recording apparatus.

[0002]

2. Description of the Related Art In recent years, with the spread of multimedia, a non-impact type recording apparatus utilizing ink jet or thermal transfer has been developed in place of the impact type recording apparatus. It is spreading in the field. Among such non-impact type printing apparatuses, a printing apparatus using the ink-jet method has attracted attention for its future potential because it is easy to increase the number of gradations and colors and its running cost is low.

FIG. 3 shows an example of a conventional ink jet recording head mounted on a recording apparatus, in which a plurality of partition walls 22 are arranged in parallel, and a space between the partition walls 22 is formed as an ink flow path 27. A flow path member 21 made of piezoelectric ceramics having an ink supply hole 26 at the bottom of the flow path 27; a driving electrode 23 formed on each of both side surfaces of the partition wall 22;
A nozzle plate 24 having an ink discharge hole 25 connected to the top surface of the partition wall 22 with a thermosetting adhesive or glass, and communicating with the name flow path 27;
By bending and displacing the partition wall 22 in a “く” shape, the ink introduced into the flow path 27 from the ink tank (not shown) via the ink supply hole 26 is pressurized, and the ink droplet is discharged from the ink discharge hole 25. It was intended to discharge. In addition,
In the figure, reference numeral 28 denotes a lead line of the driving electrode 23.

Conventionally, as the piezoelectric ceramics forming the flow path member 21, a piezoelectric ceramic mainly containing lead zirconate titanate or the like has been used.
The nozzle plate 24 joined to the top surface of the second 2 is made of the same size as the piezoelectric ceramics forming the partition walls 22 so as not to be separated or deformed by the heat applied when joining with a thermosetting adhesive or glass. It is necessary to be formed of a material having a thermal expansion coefficient, and it has been proposed to be formed of the same piezoelectric ceramic as the partition wall 22 or an insulating ceramic such as magnesia, zirconia, and alumina.
(See JP-A-6-234215).

[0005]

However, since the piezoelectric ceramics have a small Young's modulus of about 50 GPa, when the nozzle plate 24 is formed, the partition wall 22 is secured while maintaining the strength.
In order to prevent the deformation caused by the bending displacement of the nozzle plate 24, the thickness of the nozzle plate 24 had to be increased. As a result, the length of the ink discharge holes 25 provided in the nozzle plate 24 increases, and the resistance in the flow path increases. Therefore, there is a problem that the discharge speed and the discharge amount of the ink droplets decrease. Moreover, it is very difficult to accurately form the ink ejection holes 25 in the thick nozzle plate 24.

On the other hand, green ceramics such as magnesia, zirconia, and alumina have a Young's modulus of 100G.
Since it has a sufficient rigidity of Pa or more, the nozzle plate 24
Although it is possible to reduce the thickness of the ceramics, it is necessary to apply grinding to reduce the thickness of the ceramics, and to apply lapping to finish the surface smoothly, so that the grinding or lapping is applied. Even if the nozzle plate 24 is distorted and the top surface of the partition wall 22 cannot be air-tightly joined, or if the nozzle plate 24 can be air-tightly joined to the partition wall 22,
There is a problem in that the deformation of No. 2 is hindered and the ejection performance (ejection speed and ejection amount) of ink droplets ejected from each ink ejection hole 25 is adversely affected.

Further, a nozzle plate 24 made of ceramics is used.
When the ink discharge holes 25 are formed in the ceramic plate, the ink discharge holes 25 are formed at predetermined positions on the ceramic plate in advance, and then finished to a predetermined thickness by grinding and lapping.
As described above, since the nozzle plate 24 is distorted, the ink discharge holes 25 cannot be arranged at predetermined positions of the flow path 27 when the nozzle plate 24 is joined to the flow path member 21. There was a problem that a part of the hole 25 was closed by the partition wall 22.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has a plurality of partition walls made of piezoelectric ceramics arranged in parallel, a flow path member serving as an ink flow path between the partition walls, and a side surface of the partition walls. And a nozzle plate that is joined to the top surface of the partition wall and has an ink discharge hole that communicates with each flow path. The drive electrode is energized to bend and displace the partition wall. In the ink jet recording head that pressurizes the ink in the flow path and discharges the ink droplet from the ink discharge hole, the nozzle plate is made of Ni-Co.
It is characterized by being formed of a Ni-Fe-based alloy or a Ni-Fe-based alloy.

In particular, when a Ni—Fe alloy is used for the nozzle plate, the Ni content is 35 to 45% by weight, and the balance of the Ni—Fe alloy or the Ni content is substantially Fe. It is preferable to use a Ni-Fe alloy containing 35 to 45% by weight, a Ti content of 1 to 3% by weight, and the balance substantially consisting of Fe.

[0010]

Embodiments of the present invention will be described below. FIG. 1 is a perspective view of an example of an ink jet recording head according to the present invention in which an upper portion is cut away, and FIGS. 2A and 2B are partial cross-sectional views for explaining a driving principle of the ink jet recording head of the present invention. It is.

In this ink jet recording head, a plurality of partition walls 2 are arranged in parallel, a space between each partition wall 2 is formed as an ink flow path 7, and a piezoelectric ceramic having an ink supply hole 6 at the bottom of each flow path 7. And a nozzle plate 4 having an ink discharge hole 5 connected to each flow path 7 and joined to a top surface of the partition 2 with a thermosetting adhesive or glass,
Driving electrodes 3 are formed on the upper half of both sides of the partition wall 2 along its longitudinal direction.
Are supplied with electricity through a lead wire 8 laid on one end side of the flow path member 1.

In order to print on a recording medium (not shown) using the ink jet recording head, an ink such as a pigment type oil-based ink, a water-based dye ink, a water-based pigment ink, or an ultraviolet curable ink is supplied. As shown in FIG. 2A, positive voltages are applied to the driving electrodes 3b, 3c and the driving electrodes 3h, 3i, respectively, and the driving electrodes 3a, 3d, When a negative voltage is applied to 3g and 3j, the partition walls 2a and 2b are bent and displaced toward the flow path 7a, and the partition walls 2d and 2e are bent and displaced toward the flow path 7d, thereby filling the flow paths 7a and 7d. The discharged ink is pressurized to discharge ink droplets from the ink discharge holes 5.

Next, each of the driving electrodes 3a to 3d, 3g to 3
When the current to j is cut off, the partition walls 2a,
2b, 2d, and 2e return to their original shapes by the elastic action, and the pressure in the flow paths 7a and 7d is reduced. As a result, the introduction of ink from the ink supply holes 6 is started, and the above-described driving lightning pole When a voltage is applied to 3a to 3d and 3g to 3j with the polarity reversed, as shown in FIG.
Since b is displaced outwardly with respect to the flow path 7a and the partition walls 2d and 2e are displaced outwardly with respect to the ink flow path 7d, the pressure inside the flow paths 7a and 7d is further reduced and the ink is filled. Will be. Each of the driving electrodes 3a to
When the energization to 3d, 3g to 3j is cut off, the partition walls 2a, 2b, 2d, 2e that have been bent and displaced return to their original shapes due to the elastic action, and enter the next ink ejection stage. By sequentially repeating the above operations, ink droplets are continuously ejected from the ink ejection holes 5.

The piezoelectric ceramics forming the flow path member 1 include piezoelectric ceramics mainly composed of lead zirconate titanate (PZT type) and lead magnesium niobate.
Piezoelectric ceramics mainly composed of (PMN-based), piezoelectric ceramics mainly composed of lead nickel niobate (PNN-based), and furthermore, piezoelectric ceramics in which these main components are combined, are used. Nozzle plate 4 joined to the top surface of partition 2 made of these piezoelectric ceramics
Is formed of a Ni—Co alloy or a Ni—Fe alloy.

That is, since the Ni—Co alloy or the Ni—Fe alloy has a high Young's modulus of about 150 to 200 GPa, even if the thickness of the nozzle plate 4 is reduced to 200 μm or less, and even to 100 μm or less. It has sufficient strength and does not deform even when the partition wall 2 is bent.
In addition, since the thickness of the nozzle plate 4 can be reduced, the length of the ink discharge hole 5 can be shortened. Therefore, an increase in resistance in the flow path can be suppressed, and a drop in the discharge speed and discharge amount of the ink droplet can be prevented. Therefore, the use of the ink jet recording head according to the present invention enables accurate and clear printing of characters and images according to information with good responsiveness.

The nozzle plate 4 is made of a Ni—Co alloy or N
By forming the nozzle plate 4 from an i-Fe alloy, the thickness of the nozzle plate 4 can be reduced, and the nozzle plate 4 has an appropriate strength. Therefore, the ink discharge holes 5 can be easily formed. Can easily be perforated.

Further, a Ni--Co alloy or Ni--Fe
The alloy does not warp even when the thickness of the nozzle plate 4 is reduced, and has a thermal expansion coefficient of 10 to 12 × 10 ⁻⁷ / ° C. for a Ni—Co alloy. In this case, the top surface of the partition wall 2 can be approximated to 2 to 12 × 10 ⁻⁷ / ° C., which is close to the coefficient of thermal expansion (1 to 5 × 10 ⁻⁷ / ° C.) of the piezoelectric ceramic forming the partition wall 2. Even when heat is applied when bonding with a thermosetting adhesive or glass, the bonding can be reliably performed without causing separation due to a difference in thermal expansion, and the flow path 7 can be hermetically sealed. Since the nozzle plate 4 is not distorted, the ink ejection holes 5 can be arranged at predetermined positions without displacement.

In addition, Ni-Co alloys and Ni-Fe alloys have lower material costs than ceramics, so that ink jet recording heads can be manufactured at low cost.

In particular, when the nozzle plate 4 is formed of a Ni—Fe alloy, the Ni content is 35 to 45% by weight.
Ni-F having a composition substantially consisting of Fe
Use an e-based alloy or have a Ni content of 35-4
If a Ni—Fe alloy having a composition of 5% by weight, a Ti content of 1 to 3% by weight, and the balance substantially consisting of Fe is used, the coefficient of thermal expansion is 2 to 5 × 10 ^−7. / ° C., the coefficient of thermal expansion of the piezoelectric ceramics forming the partition 2 can be made very close to that of the partition 2.
This is preferable because it is possible to increase the bonding strength between the ink jet holes 5 and airtightly seal the flow paths 7 here, prevent displacement of the ink discharge holes 5 and arrange them at predetermined positions. It should be noted that “the balance is substantially made of Fe” means that N
It means that components other than Fe except for i and Ti are 3% by weight or less.

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

First, the above-described piezoelectric ceramic plate is prepared, polarized in the thickness direction, and a plurality of grooves are formed on one surface of the piezoelectric ceramic plate at equal intervals by grinding or blasting with a dicing saw or the like. Engrave.

Specifically, when a groove is formed by a dicing saw, a processing speed of 15 mm / s is used by using a rotary blade to which diamond abrasives of # 1000 to # 2000 are fixed.
ec or less, preferably 5 mm / sec or less. Also, when grooving is performed by blasting, since the processing pressure applied to the wall forming the groove is relatively small, sand,
Particles such as glass and ceramics may be sprayed at a pressure of about 40 GPa.

In this manner, the groove is formed in the ink flow path 7.
Then, the flow path member 1 is formed, in which the wall that partitions the name flow path 7 is used as the partition wall 2. The ink supply holes 6 may be formed at the bottom of the groove by laser processing.

Next, after masking the required portion of the flow path member 1, the upper half of each side wall of each partition 2 is formed along the longitudinal direction by a film forming means such as a vapor deposition method, a sputtering method, and a plating method. Lead wires 8 are formed on the drive electrode 3 at one end of the flow path member 1. Metal such as platinum, gold, palladium, copper, nickel, aluminum or platinum-gold, palladium-
An alloy mainly containing silver, platinum-palladium, or the like may be used.

On the other hand, the nozzle plate 4 having the ink discharge holes 5
Can be formed by etching a metal plate made of a Ni—Co-based alloy or a Ni—Fe-based alloy to form the ink discharge holes 5, or a nozzle provided with the ink discharge holes 5 by electroforming. The plate 4 may be formed. In particular, if the electroforming method is used, the flatness of the nozzle plate 4 can be ensured even when the nozzle plate 4 is formed to a thickness of 100 μm or less. It is preferable because it can be formed.

Then, the nozzle plate 4 made of a Ni—Co alloy or a Ni—Fe alloy is thermosettingly bonded to the top surface of each partition 2 so as to close the flow path 7 of the flow path member 1 with the nozzle plate 4. By joining with an agent or glass, the ink jet recording head shown in FIG. 1 can be obtained.

In the ink jet recording head shown in FIG. 1, an example is shown in which the entire flow path member 1 constituting the partition 2 is formed of piezoelectric ceramics. However, only the partition 2 is formed of piezoelectric ceramics. But it doesn't matter. Further, the partition 2 may be formed by bonding two layers of piezoelectric ceramic members having opposing polarization directions by bonding or the like. In particular, an ink jet recording head having such a partition 2 is provided with a driving electrode. When a voltage is applied to the ink-jet recording head 3, the ink-jet recording head can be bent and displaced in a “C” shape larger than the ink-jet recording head shown in FIG. It can be even higher. In order to achieve such an effect, it is necessary to form the driving electrode 3 on all side surfaces of the partition 2.
Further, it is needless to say that the present invention is not limited to the embodiments described above, and may be improved without departing from the gist thereof.

[0028]

EXAMPLE An ink jet recording head of the present invention shown in FIG. 1 and a conventional ink jet recording head shown in FIG.
An experiment was conducted to examine the positional deviation between the ink ejection holes 22 and the ink ejection holes 5 and 25.

In this experiment, each ink jet recording head was prepared by preparing a 0.7 mm thick piezoelectric ceramic plate containing lead zirconate titanate as a main component and having a Young's modulus of 50 GPa, and performing polarization treatment in the thickness direction of the child. After that, grooves are formed with a dicing saw at a groove width of 70 μm, a groove depth of 400 μm, and a pitch of 141 μm, and holes are drilled at the bottom of each groove with an excimer laser to form a plurality of structures with the ink flow paths 7, The partition walls 2 and 22 were used to partition the flow paths 7 and 27, and flow path members 1 and 21 having ink supply holes 6 and 26 at the bottom of the flow paths 7 and 27 were produced.

Next, masking is applied to the flow path members 1 and 21, and A is formed on both side surfaces of the partition walls 2 and 22 along the longitudinal direction thereof.
The drive electrodes 3 and 23 made of u were formed on one end surfaces of the flow path members 1 and 21 by lead lines 8 and 28 made of Au by a sputtering method. The driving electrodes 3 and 23 formed on the side surfaces of the partition walls 2 and 22 were formed in a band shape in which the depths of the flow paths 7 and 27 were 200 μm and the length in the longitudinal direction was 10 mm.

Thereafter, on the top surface of the partition wall 2 of the flow path member 1,
As a product of the present invention, a nozzle plate 4 made of a Ni-Co alloy or a Ni-Fe alloy and having different thicknesses is joined with an epoxy-based adhesive to produce an ink jet recording head shown in FIG. Conventionally, a nozzle plate 24 made of piezoelectric ceramics (PZT) containing molybdenum (Mo) or lead zirconate titanate as a main component and having a different thickness is bonded to the top surface of the partition wall 22 of the road member 21 by epoxy bonding. Then, the ink jet recording heads shown in FIG. 3 were manufactured.

The flow path members 1, 21 pass through the centers of the ink discharge holes 5, 25 and extend along the longitudinal direction of the flow paths 7, 27.
To measure the amount of deviation between the centers of the ink ejection holes 5 and 25 and the centers of the partitions 2 and 22, and then energize the driving electrodes 3 and 23 to bend the partitions 2 and 22 exposed at the cut portions. The displacement was measured by displacement.

The driving frequency to the driving electrodes 3 and 23 is set to a sine wave of 120 kHz, and a voltage of 30 V is applied only to the positive electrode while the input of the negative electrode is cut off. The displacement amount at the center of the side surface of No. 22 was measured with a laser displacement meter.

The results are as shown in Table 1.

[0035]

[Table 1]

As a result, as can be seen from Table 1, when the nozzle plate 4 was formed of a Ni—Co alloy or a Ni—Fe alloy, although the thickness was as thin as 200 μm or less, the bending displacement of the partition wall 2 was limited. On the other hand, there was no deformation, and the displacement of the partition 2 was as large as 30 nm or more. In addition, since the thermal expansion coefficient is close to that of the piezoelectric ceramic (PZT) forming the flow path member 1 and the distortion of the nozzle plate 4 is small, the position of the ink ejection hole 5 can be maintained even when the nozzle plate 4 is joined with an epoxy adhesive. The displacement was as small as 15 μm or less, and was superior in terms of manufacturability, displacement characteristics of the partition 2, and displacement of the ink ejection holes 5 as compared with the conventional product.

In particular, when the nozzle plate 4 has a Ni content of 35,
About 50% by weight and the balance substantially consisting of Fe
-Fe-based alloy and Ni content is 35 to 50% by weight, T
i is 1 to 3% by weight, and the balance is substantially Fe
Since the thermal expansion difference between the piezoelectric ceramics (PZT) forming the flow path member 1 and the piezoelectric ceramics (PZT) forming the flow path member 1 is extremely small, the ink formed after joining with the epoxy adhesive can be used. 12 misalignment of hole 5
It could be less than μm, which was particularly excellent.

[0038]

As described above, according to the present invention, a plurality of partition walls made of piezoelectric ceramics are juxtaposed, a flow path member serving as an ink flow path between each partition wall, and a side wall of the partition wall. A driving electrode and a nozzle plate joined to the top surface of the partition wall and having an ink ejection hole communicating with each flow path, by applying a current to the driving electrode to bend and displace the partition, In an ink jet recording head that pressurizes ink in a flow path and discharges the ink as a droplet from the ink discharge hole, the nozzle plate may be formed of a Ni-Co alloy or Ni-
Since the nozzle plate is made of an Fe-based alloy, the thickness of the nozzle plate can be extremely reduced to 200 μm or less, so that the resistance of the flow path (addition: source passage ) in the ink discharge hole can be reduced, and the discharge characteristics of the ink droplet can be reduced. (Discharge speed and discharge amount) can be improved. Further, even if the thickness of the nozzle plate is reduced, the distortion is small and the difference in thermal expansion between the nozzle plate and the piezoelectric ceramic forming the partition is small. In addition, since the material cost is lower than that of ceramics, the inkjet recording head can be manufactured at low cost.

In particular, when the nozzle plate 4 has a Ni content of 35,
About 50% by weight and the balance substantially consisting of Fe
-Fe-based alloy or Ni content of 35 to 50% by weight, T
i is 1 to 3% by weight, and the balance is substantially Fe
Since the thermal expansion difference between the piezoelectric ceramics forming the flow path member and the piezoelectric ceramics can be extremely reduced, it is preferable that the ink discharge holes are formed with little displacement.

[Brief description of the drawings]

FIG. 1 is a perspective view of an inkjet recording head according to the present invention, in which a-portion is cut away.

FIGS. 2A and 2B are partial cross-sectional views for explaining the driving principle of an ink jet recording head according to the present invention.

FIG. 3 is a partially cutaway perspective view of a conventional inkjet recording head.

[Explanation of symbols]

1, 21: flow path member 2, 22: partition wall 3, 23: driving electrode 4, 24: nozzle plate 5, 25: ink ejection hole 6, 2
6: Ink supply hole 7, 27: Channel 8, 28: Lead line

Claims (3)

[Claims] 1. A flow path member comprising a plurality of partition walls made of piezoelectric ceramics arranged side by side, and an ink flow path between the partition walls.
A drive electrode formed on the side surface of the partition wall, and a nozzle plate joined to the top surface of the partition wall and having an ink ejection hole communicating with each flow path, and the partition wall is formed by supplying electricity to the drive electrode. In an ink jet recording head that pressurizes ink in the flow path and discharges ink droplets from the ink discharge holes by bending and displacing, the nozzle plate is made of Ni-C
An ink jet recording head characterized by being formed of an o-based alloy or a Ni-Fe-based alloy. 2. The ink jet recording head according to claim 1, wherein the content of Ni forming the Ni-Fe alloy is 35 to 45% by weight, and the balance substantially consists of Fe. 3. The Ni-Fe alloy has a Ni content of 35 to 45% by weight and a Ti content of 1 to 3% by weight.
2. The ink jet recording head according to claim 1, wherein the balance is substantially made of Fe.