JP2002292861A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive ink jet recording head having excellent print characteristics. SOLUTION: A plurality of barrier walls 2 of piezoelectric ceramic, each provided with a drive electrode 3, are formed side by side on a channel member 1 such that the gaps between respective barrier walls 2 serve as ink channels and a rolled metal plate is placed on the top face of the barrier walls 2 such that the angle between the direction of linear protrusions and recesses formed on the surface of the metal plate and the arranging direction of ink ejection holes 5 is in the range of 80 deg.-100 deg., thus manufacturing an ink jet recording head 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head mounted on an ink jet recording apparatus for printing characters and images by discharging ink droplets.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers and the development of multimedia, the use of ink jet recording devices as recording devices for outputting information to a recording medium has been rapidly expanding.

[0003] Such an ink jet type recording apparatus is equipped with an ink jet recording head (hereinafter referred to as a head). The head is provided with a heater in a flow path filled with ink, and heats the ink by the heater. ,
A thermal jet method in which ink is pressurized by bubbles generated in the flow path and ink droplets are discharged from ink discharge holes, and a wall forming a flow path filled with ink is bent and displaced by a piezoelectric element by a mechanical device. There is generally known a piezoelectric method in which ink in a flow path is pressurized to eject ink droplets from ink ejection holes. Among them, the piezoelectric head has excellent durability and responsiveness, and has the advantage that the type of ink is not limited because the ink is not directly heated.

In such a piezoelectric type head, as shown in FIG. 4, a plurality of partition walls 22 are arranged side by side, and an ink flow path 27 is formed between the partition walls 22. A flow path member 21 made of a piezoelectric ceramic having a supply hole 26, a drive electrode 23 formed on both side surfaces of the partition wall 22, and a top surface of the partition wall 22 joined by a thermosetting adhesive, A nozzle plate 24 provided with an ink discharge hole 25 communicating with a passage 27. When the drive electrode 23 is energized to bend and displace the partition 22 in a く shape, the ink from an ink tank (not shown) In some cases, ink introduced into the flow path 27 through the supply hole 26 is pressurized to eject ink droplets from the ink ejection hole 25. In the drawing, reference numeral 28 denotes a lead line of the driving electrode 23.

In order to discharge ink droplets stably with such a head 20, it is necessary to form the nozzle plate 24 from a material having high rigidity which does not bend with respect to the bending displacement of the partition 22. A metal plate is used, and in manufacturing the nozzle plate 24 from the metal, it has been proposed to manufacture the nozzle plate 24 by an electroforming method.

More specifically, after an insulating mask having a thickness of several μm is formed on a conductive flat plate in accordance with the distance between the flow paths 27, a metal (for example, Ni) is formed by electroforming. It has been proposed to manufacture a metal nozzle plate 24 having ink discharge holes 25 by forming a plating layer and then removing the flat plate and the insulating mask (see Japanese Patent Application Laid-Open No. H11-147316). ).

[0007]

However, forming the nozzle plate 24 by the electroforming method requires steps such as formation of an insulating mask, formation of a plating layer, separation of a flat plate from the insulating mask, and the like. Not only is the process complicated, but also the plating time, current, metal concentration in the plating solution, and the like are strictly controlled in order to control the thickness of the nozzle plate 24, the diameter of the ink ejection holes 25, the interval, and the like with high accuracy. A great deal of labor and cost to stably manufacture the nozzle plate 24 in which the thickness of the nozzle plate 24 is controlled to ± 2 μm, the hole diameter of the ink discharge holes 25 is controlled to ± 2 μm, and the interval between the ink discharge holes 25 is controlled to ± 1 μm. It took something.

Therefore, it is necessary to manufacture a nozzle plate 24 by using a metal plate manufactured by a rolling method which can be obtained at a low cost, and forming an ink discharge hole 25 in the metal plate by etching or laser processing. Although it is conceivable, in the metal plate manufactured by the rolling method, since the metal crystal is stretched in the rolling direction, the surface has linear irregularities in the rolling direction, and the inside has distortion, When the distortion inside the metal plate is relaxed by frictional heat during the manufacturing process of the nozzle plate 24 or heat during the process of attaching the nozzle plate 24 to the flow path member 21 using a thermosetting adhesive, the elongated metal crystal becomes Before returning to the original state, the shape and the interval of the ink ejection holes 25 set to a predetermined size before applying heat change. There is a problem causing the displacement of the hole 25.

[0009] In particular, such a problem arises as in the case of the line type ink jet recording head 20, in which the long nozzle plate 24 is used.
When using the ink ejection holes 25 at one end and the ink ejection holes 25 at the other end, there is a considerably large dimensional change. In this case, a part or the whole of the ink discharge hole 25 is closed by the partition wall 22, and there is a problem that the discharge amount of the ink droplet is significantly reduced or the ink droplet cannot be discharged.

[0010]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a flow path member in which a plurality of partition walls at least partially made of piezoelectric ceramics are arranged side by side, and an ink flow path is provided between the partition walls. A driving electrode formed on the side surface of the partition,
A nozzle plate provided with a plurality of ink ejection holes connected to the top surface of each of the partition walls and communicating with each of the flow paths, by applying a current to the driving electrodes to bend and displace the partition walls,
In an ink jet recording head that pressurizes ink in each flow path and discharges ink droplets from the ink discharge holes, the nozzle plate is formed by a metal plate having a linear uneven portion extending in one direction on the surface thereof. In addition, the angle between the direction of the linear uneven portion of the nozzle plate and the direction in which the plurality of ink ejection holes are arranged is 80 ° to 100 °.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a cutaway perspective view showing an example of an ink jet recording head of the present invention, and FIG. 2 is a partial line sectional view for explaining the driving principle of the ink jet recording head of the present invention.

This ink jet recording head 10 is made of piezoelectric ceramics having a plurality of partition walls 2 arranged side by side, an ink flow path 7 between the partition walls 2, and an ink supply hole 6 at the bottom of each flow path 7. A flow path member 1 and a nozzle plate 4 having an ink ejection hole 5 connected to each flow path 7 and joined to a top surface of the partition wall 2 with a thermosetting adhesive. Driving electrodes 3 are formed on the upper half of the surface along the longitudinal direction, and each driving electrode 3 is energized through a lead wire 8 laid on one end side of the flow path member 1. It has become.

Further, in the ink jet recording head 10 of the present invention, the nozzle plate 4 is formed of a metal plate manufactured by a rolling method, and the rolling direction (the direction of arrow A) formed on the surface of the metal plate. Are arranged so as to have an angle θ of 80 ° to 100 ° with respect to the direction in which the ink ejection holes 6 are arranged (the direction of arrow B).

The ink jet recording head 1
In order to print on a recording medium (not shown) using No. 0, an ink such as a pigment-type oil-based ink, a water-based pigment ink, or an ultraviolet curable ink is introduced into each flow path 7 through the ink supply hole 6, and FIG. As shown in a), for example, the driving electrode 3b,
A positive voltage is applied to each of the driving electrodes 3c and the driving electrodes 3h and 3i,
When a negative voltage is applied to the driving electrodes 3a, 3d, 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. Pressurize the ink filled in 7a, 7d,
Ink droplets are ejected from the ink ejection holes 5.

Next, the driving electrodes 3a to 3d, 3g to 3
When the current to j is cut off, the partition walls 2a,
2b, 2d, 2e return to the original shape by the elastic action,
As a result of the pressure reduction in the flow paths 7a and 7d, the introduction of ink from the ink supply hole 6 is started, and the voltage is applied to the driving electrodes 3a to 3d and 3g to 3j by reversing the positive and negative directions. Then, as shown in FIG.
Since the 2b is bent outwardly with respect to the flow path 7d, the pressure inside the flow paths 7a and 7d is further reduced, and the ink is filled. And each of the driving electrodes 3a to 3d, 3g to 3j
When the power supply to the power supply is cut off, the partition walls 2a and 2
b, 2d, and 2e return to their original shapes by the elastic action and enter the next ink discharge stage. These operations are sequentially repeated to continuously discharge ink droplets from the ink discharge holes 5. It has become.

According to the present invention, the nozzle plate 4 is
Since it is formed by a metal plate manufactured by a rolling method, the steps of forming an insulating mask, forming a plating layer, peeling off a flat plate or an insulating mask, such as the electroforming method, are unnecessary, and Since it is not necessary to control the plating time, current, metal concentration in the plating solution, and the like, the nozzle plate 4 can be manufactured at low cost, and as a result, an inexpensive head 10 can be provided.

Further, according to the present invention, the direction of the linear uneven portion (direction of arrow A) existing on the surface of the nozzle plate 4 made of a metal plate manufactured by the rolling method is
Are arranged so as to have an angle θ of 80 ° to 100 ° with respect to the juxtaposed direction (direction of arrow B), so that each ink ejection hole 5 provided in the nozzle plate 4 is substantially at the center of each flow path 7. , And a part or all of the ink discharge holes 5 are not blocked, so that a predetermined amount of ink droplets can be stably discharged from all the ink discharge holes 5. Can be.

That is, a plurality of linear irregularities are formed along the rolling direction on the surface of the metal plate manufactured by the rolling method, the metal crystal is extended in the rolling direction, and the inside thereof has a strain. However, the present inventor repeatedly studied the mechanism, and found that when heat and the like acted to alleviate the strain in the metal plate and the elongation of the metal crystal returned to its original state, It is found that a large dimensional change occurs in the rolling direction of the metal plate, and that a dimensional change in a direction perpendicular to the rolling direction is small. By setting the direction substantially perpendicular to the rolling direction of the metal plate, the distortion of the metal plate is reduced by the heat acting during the production of the nozzle plate 4 and the time of bonding the nozzle plate 4 to the flow path member 1. Even if changes occur, ink Since the dimensional change in the arrangement direction of the holes 5 is hardly affected, whereas it is bonded to the nozzle plate 4 to the channel member 1 to the ink discharge hole 5 of the end side as a reference,
The ink discharge holes 5 on the other end side can also be arranged so as to be located substantially in the center of the flow path 7, and it has been found that the partition walls 2 do not block part or all of them.
The present invention has been reached.

The direction of the linear uneven portion (direction of arrow A) existing on the surface of the nozzle plate 4 made of a metal plate is set to 80 with respect to the direction in which the ink ejection holes 5 are arranged (direction of arrow B).
When the angle θ is less than 80 ° or more than 100 °, the direction of the linear uneven portion existing on the surface of the nozzle plate 4 is changed to the direction of the ink ejection hole 5. , The dimensional change accompanying the relaxation of the distortion becomes large, the shape change of the ink discharge holes 5 and the degree of the dimensional change between the ink discharge holes 5 become too large, and the positional deviation of the ink discharge holes 5 is reduced. This is because it occurs.

It should be noted that the degree of the dimensional change accompanying the relaxation of the strain is less affected by the extension of the crystal as it approaches 90 ° with respect to the direction of the linear irregularities formed on the surface of the metal plate. The angle θ between the direction of the linear uneven portion (the direction of arrow A) and the direction in which the ink ejection holes 5 are arranged (the direction of arrow B) is 9
Preferably, the angle is set to 0 °, and the respective ink ejection holes 5 of the nozzle plate 4 can be arranged at the center of the channel 7 with higher accuracy.

The piezoelectric ceramics forming the flow path member 1 include piezoelectric ceramics mainly containing lead zirconate titanate (PZT type), piezoelectric ceramics mainly containing lead magnesium niobate (PMN type), and the like. A piezoelectric ceramic containing lead nickel niobate (PNN) as a main component, or a piezoelectric ceramic in which these main components are combined can be used.

The metal forming the nozzle plate 4 may be, for example, Fe, Mo, Ni, Co, or an alloy mainly composed of these. Above all, it is preferable to use a metal having a small thermal expansion difference from the piezoelectric ceramic in consideration of residual stress at the time of joining with the partition wall 2 made of the piezoelectric ceramic. For example, Mo steel, Ni—Fe, Ni
-An alloy mainly composed of Ni such as Co can be preferably used.

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

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

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, and when grooving is performed, the processing pressure applied to the wall forming the groove is relatively small.
Particles such as glass and ceramics may be sprayed at a pressure of about 40 GPa.

Then, a channel member 1 is manufactured in which the obtained grooves are used as ink channels 7 and the walls separating the respective channels 7 are used as partition walls 2. The ink supply hole 6 has a Y
It is formed by laser processing such as an AG laser and an excimer laser.

Next, after masking the necessary portions 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, rhodium, nickel and aluminum or platinum-gold, palladium-
An alloy mainly composed of gold, platinum-palladium or the like may be used.

On the other hand, a metal plate manufactured by a rolling method is prepared, and the direction of the linear irregularities formed on the surface of the metal plate is observed with a metal microscope or the like. On the other hand, the ink ejection holes 5 are formed by etching or laser processing so that the rows of the plurality of ink ejection holes 5 have an angle θ of 80 ° to 100 °.

Here, when the rolling direction is specified, it can be determined by observing the direction of the linear irregularities formed on the surface of the metal plate with a metal microscope or the like. If it is difficult to judge the linear irregularities formed on the metal plate, the judgment may be made by observing the metal crystal on the surface of the metal plate with a scanning electron microscope and observing the direction in which the metal crystal extends.

Thereafter, for example, with reference to the ink ejection holes 5 on one end side of the nozzle plate 4, the ink ejection holes 5 are positioned so as to be located at the center of the flow path 7 of the flow path member 1.
The ink jet recording head 10 of the present invention can be manufactured by laminating with a thermosetting adhesive or glass, and the ink discharge hole at the other end side of the nozzle plate 4 can be manufactured by the manufacturing method of the present invention. 5 can also be arranged so as to be located substantially at the center of each flow path 7 of the flow path member 1, and manufacture the ink jet recording head 10 in which a part or the whole of the ink discharge hole 5 is not closed by the partition wall 2. can do.

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, in the ink jet recording head 10 shown in FIG. Although an example in which the partition wall 2 is formed of piezoelectric ceramics has been described, a partition wall 2 formed of piezoelectric ceramics or a partition wall 2 in which two layers of piezoelectric ceramic members having opposite polarization directions are joined by bonding or the like is used. In particular, the partition wall 2 is formed by joining two layers of piezoelectric ceramic members having opposite polarization directions.
When a voltage is applied to the driving electrode 3, the ink droplet can be displaced more flexibly than the ink jet recording head 10 shown in FIG. It can be even higher. In order to achieve such an effect, the partition 2
It is necessary to form the driving electrode 3 on the entire side surface of the device.

Also, in the ink jet recording head 10 shown in FIG. 1, the nozzle plate 4 made of only metal has been described. For example, as shown in FIG. 3, polyimide (PI) is formed on a metal plate manufactured by a rolling method. A nozzle plate 4 in which a resin plate 9 made of a resin, polyphenylene sulfide (PPS) resin, polyetherimide (PEI) resin, polyamideimide (PAI) resin, or the like may be used, may be used. It is sufficient that the angle θ between the direction of the linear uneven portion formed on the surface and the direction in which the ink ejection holes 5 are arranged has a positional relationship in the range of 80 ° to 100 °.

Further, the present invention can be applied not only to the head 10 having the ink ejection holes 5 arranged in a line, but also to a head in which a group of ink ejection holes is arranged in two or more lines.

As described above, it goes without saying that the present invention may be improved or changed without departing from the scope of the invention.

[0036]

(Example 1) Here, in manufacturing a nozzle plate, a metal plate manufactured by a rolling method was used, and the direction of the linear uneven portion of the metal plate and the direction of juxtaposition of the ink discharge holes were used. An experiment was conducted to examine the amount of deviation of the distance from the ink discharge hole at one end to the ink discharge hole at the other end when the angle formed was different, and the discharge performance of an ink jet recording head using these nozzle plates.

More specifically, a 40 μm-thick metal plate made of Mo manufactured by a rolling method was used, and an ink discharge hole having a diameter of 40 μm was formed to 141 μm by an etching method.
1000 nozzle plates arranged side by side at a pitch were produced. At this time, the direction in which the ink ejection holes were arranged was arranged at an angle of 0 ° to 110 ° with respect to the direction of the linear uneven portion formed by the rolling method.

Then, the distance from the ink ejection hole at one end to the ink ejection hole at the other end of the obtained nozzle plate was measured, and the amount of deviation from the set value of 140.859 mm was calculated.

The results are as shown in Table 1.

[0040]

[Table 1]

As a result, as can be seen from Table 1, the samples e, f, and e in which the angle between the direction of the linear uneven portion of the metal plate and the direction in which the ink ejection holes are arranged are in the range of 80 ° to 100 °. g
The sample f in which the deviation from the set value was as small as 10 μm or less and the angle between the direction of the linear uneven portion of the metal plate and the direction in which the ink ejection holes were arranged was 90 ° was particularly excellent.

Next, an ink jet recording head was manufactured using the nozzle plates shown in Table 1, and ink droplets were ejected, and the ink droplets were landed on the recording medium to determine the ejection performance.

First, a piezoelectric ceramic substrate mainly composed of lead zirconate titanate that has been subjected to polarization processing in the thickness direction is prepared, and after polarization processing in the thickness direction, a plurality of substrates whose both ends are closed by grinding using a dicing saw. Were formed side by side, and a flow path member was prepared in which each groove was used as a flow path and a wall partitioning each groove was used as a partition.

At this time, the width of the partition was 70 μm, the height of the partition was 350 μm, and the width of the flow path was 70 μm.

Next, after tilting the flow channel member to form a metal film of aluminum on the top surface and the upper half of the side surface by sputtering, the center of the metal film adhered to the top surface of the partition wall is elongated. The wafer was cut along a direction by a YAG laser, and the metal films formed on the upper halves on both side surfaces of the partition were used as drive electrodes, and the metal film formed on the periphery of the top surface of the partition was used as lead lines for the drive electrodes. In addition, an ink supply hole for supplying ink to the bottom of the flow channel with a YAG laser was formed.

Then, after aligning the ink discharge holes of the nozzle plate and the flow path shown in Table 1, the head was manufactured by joining the top surface of the partition wall with an epoxy-based adhesive.

Then, a voltage was applied to the driving electrode of the head via a lead wire to eject ink droplets, and the ink droplets were landed on the recording medium to evaluate the ejection performance.

The ejection performance was evaluated by measuring and comparing the interval between the landing positions of the ink droplets that landed on the recording medium and the pitch between the ink ejection holes with an image processing device connected to a photographing camera. The variation in the landing position of the ink droplet was calculated as a percentage.

The results are as shown in Table 2.

[0050]

[Table 2]

As can be seen from Table 2, the samples Noa, b,
Since c, d, and h have large displacements of the ink ejection holes,
The variation in the landing position of the ink droplet was as large as 7% to 9%.

On the other hand, in the samples e, f, and g, since the positional accuracy of the ink discharge holes arranged in parallel with the nozzle plate is good and the positional deviation between each flow path of the flow path member and the ink discharge holes is small, the recording is performed. Excellent printing accuracy was obtained in which the position accuracy of ink droplets that landed on the medium was 1 to 3%.

As a result, when the metal plate formed by the rolling method is used as the nozzle plate, the angle between the direction of the linear uneven portion of the metal plate indicating the rolling direction and the direction in which the ink ejection holes are arranged is 80 degrees. It turns out that it is good to set it to {-100}.

[0054]

As described above, according to the present invention, a plurality of partition walls at least partially made of piezoelectric ceramics are juxtaposed, a flow path member having an ink flow path between the partition walls, A driving electrode formed on the side surface, and a nozzle plate joined to the top surface of each of the partition walls and provided with a plurality of ink ejection holes communicating with the respective flow paths. In the ink jet recording head that pressurizes ink in each flow path and discharges ink droplets from the ink discharge holes by bending and displacing the nozzle plate, the nozzle plate has a linear uneven portion extending in one direction on the surface thereof. The angle between the direction of the linear concavo-convex portion of the nozzle plate and the direction in which the plurality of ink ejection holes are arranged is in the range of 80 ° to 100 °. Because of the configuration, the nozzle Although formed by a metal plate manufactured by a rolling method, it is possible to arrange so that each ink ejection hole provided in the nozzle plate is located substantially at the center of the flow path, respectively, and a part or all of the ink ejection holes Is not blocked, so that a predetermined amount of ink droplets can be stably ejected from all the ink ejection holes.

Further, according to the present invention, since the nozzle plate is formed of a metal plate manufactured by a rolling method, complicated steps and management such as the electroforming method are not required, and the nozzle plate is manufactured at low cost. be able to.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of an ink jet recording head according to the present invention.

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

FIG. 3 is a partially cutaway perspective view showing another embodiment of the inkjet recording head according to the present invention.

FIG. 4 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: drive electrode 4, 24: nozzle plate 5, 25: ink discharge hole 6, 26: ink supply hole 7, 27: flow path 8, 28: drawing out Wire 9: Resin plate

Claims (1)

[Claims] A plurality of partition walls at least partially formed of piezoelectric ceramics, wherein a plurality of partition walls are formed in parallel, and a flow path member having an ink flow path between the partition walls; a driving electrode formed on a side surface of the partition walls; A nozzle plate that is joined to the top surface of each partition and has a plurality of ink ejection holes that communicate with each flow path. In an ink jet recording head that pressurizes ink and ejects ink droplets from the ink ejection holes, the nozzle plate is formed of a metal plate having a linear uneven portion extending in one direction on the surface thereof, and the nozzle plate has a linear shape. An angle between the direction of the concave and convex portions and the direction in which the plurality of ink ejection holes are arranged in the range of 80 ° to 100 °.