JP2002347246A - Inkjet recording head - Google Patents

Abstract

[PROBLEMS] To provide an ink jet recording head which is inexpensive and has excellent printing characteristics. A nozzle plate constituting an ink jet recording head is formed of a metal plate having streaks extending in one direction on the surface thereof, and the direction of the streaks of the nozzle plate and the direction in which the plurality of ink ejection holes are arranged in parallel. Angle of 80 ° ~
It was configured to have a positional relationship of 100 °.

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 recording media has been rapidly expanding.

[0003] Such an ink jet recording apparatus includes an ink jet recording head (hereinafter referred to as a head).
The head is a Kaiser type that pressurizes ink in the flow path by vibrating the flow path wall filled with ink with a piezoelectric actuator and discharges the ink as ink droplets from the ink discharge holes. A so-called piezoelectric head is known.

FIG. 4 is a schematic diagram of a piezoelectric type head called a Kaiser type. As shown in FIG. 4, a head 30 has a plurality of side walls 32 arranged side by side on a diaphragm 31 and an ink flow path 36 between each side wall 32. A flow path member 35 having one end side closed and an ink supply hole 37 provided on the other end side is joined to the flow path member 35 via a thermosetting adhesive. Plate 33 having ink discharge holes 38 communicating with the nozzle
A piezoelectric actuator 34 is attached to the surface of the vibration plate 31 on the side opposite to the flow paths 36 with a thermosetting adhesive, and the piezoelectric actuator 34 is polarized in the thickness direction. What used the electrode 40 laid on the upper and lower main surfaces of the piezoelectric ceramic plate 39 was used.

In order to eject ink droplets from the head 30, an electrode 4 forming a piezoelectric actuator 34 is used.
By applying a voltage between 0 and 0, the piezoelectric actuator 34 is vertically vibrated in the thickness direction, and the vibrating plate 31 is vibrated in the direction of the arrow, so that the ink in the flow path 36 is pressurized and formed as ink droplets from the ink discharge holes 38. It was designed to be ejected (Japanese Patent Laid-Open No. 7-156385).

In order to stably eject ink droplets from the head 30, the nozzle plate 33 is not deformed by the pressure applied to the ink in the flow path 36, and the head 30 is assembled. It is desirable to form the nozzle plate 33 from a material having good handling properties at the time. Conventionally, a material formed from a metal is used. In manufacturing the nozzle plate 33 from this metal, it has been proposed to manufacture the nozzle plate 33 by an electroforming method.

More specifically, after an insulating mask having a thickness of several μm is provided on a conductive flat plate at a position where the flow path 36 is formed, a metal (for example, Ni) is plated by electroforming. It has been proposed to manufacture a metal nozzle plate 33 having ink discharge holes 38 by forming a layer and then removing the flat plate and the insulating mask (Japanese Patent Application Laid-Open No. 2000-2000).
-289209).

[0008]

However, forming the nozzle plate 33 by the electroforming method requires processes such as formation of an insulating mask, formation of a plating layer, and separation of the flat plate and the insulating mask. 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 33, the hole diameter of the ink ejection holes 38, the intervals, and the like with high accuracy. A great deal of labor is required to stably manufacture the nozzle plate 33 in which the thickness of the nozzle plate 33 is controlled to ± 2 μm, the diameter of the ink discharge holes 38 is controlled to ± 2 μm, and the interval between the ink discharge holes 38 is controlled to ± 1 μm. And it was costly.

Therefore, a nozzle plate 33 is manufactured by using a metal plate manufactured by a rolling method which can be obtained at a low cost, and forming an ink discharge hole 38 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 in the manufacturing process of the nozzle plate 33 or heat in the bonding process to the flow path member 35 using a thermosetting adhesive, the extended metal crystal is restored to its original state. The shape and spacing of the ink ejection holes 38, which had been set to predetermined dimensions before the application of heat, are changed. When such a nozzle plate 33 is attached to the flow path member 35, the ink ejection holes 3 There is a problem causing the displacement of the.

[0010] In particular, such a problem is caused by a long nozzle plate 33 like a line type ink jet recording head 30.
When using the ink discharge holes 38 at one end and the ink discharge holes 38 at the other end, there is a considerable dimensional change, and the ink discharge holes 38 at one end are attached to the flow path member 35 based on the ink discharge holes 38 at one end. At the same time, on the other end side, a part or the whole of the ink discharge hole 38 is closed by the side wall 32, and there is a problem that the discharge amount of the ink droplet is significantly reduced or the ink droplet cannot be discharged.

Further, such a problem is not limited to the head having the ink discharge holes 38 in a direction perpendicular to the longitudinal direction of the flow path 36 as in the head 30 shown in FIG. The same applies to a head having ink ejection holes in the longitudinal direction.

[0012]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a flow path member having a plurality of side walls arranged in parallel on a diaphragm, and a flow path for ink between each side wall. A piezoelectric actuator provided on a surface opposite to each flow path; and a nozzle plate joined to the flow path member and provided with an ink ejection hole communicating with each flow path. In an ink jet recording head that pressurizes ink in the flow path to discharge ink droplets from ink discharge holes by vibrating a plate, the nozzle plate has a linear uneven portion extending in one direction on a surface thereof. It is formed of a metal plate, and the angle between the direction of the linear uneven portion on the surface of the nozzle plate and the direction in which the plurality of ink ejection holes are arranged is set to 80 ° to 100 °.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 is a view showing an embodiment of an ink jet recording head according to the present invention. FIG. 1 (a) is a perspective view with a part thereof cut away, and FIG. 1 (b) is an enlarged view of a portion A in FIG. It is sectional drawing.

In the ink jet recording head 20 (hereinafter referred to as a head), a plurality of side walls 2 are juxtaposed on a vibration plate 1, an ink flow path 6 is formed between the side walls 2, and one end is closed. A nozzle provided with an ink supply hole 7 on the other end side, and an ink discharge hole 8 joined to the flow channel member 5 with a thermosetting adhesive and communicating with each flow path 6 A piezoelectric actuator 4 is adhered to the surface of the vibration plate 1 on the side opposite to the flow path 6 by bonding or the like.

The piezoelectric actuator 4 includes a lead zirconate titanate (PZT), a lead magnesium niobate (PMN), and a lead nickel niobate (P
NN) or the like by baking or thin film forming means on the upper and lower main surfaces of a piezoelectric ceramic plate 9 made of a sintered body mainly composed of a sintered body.
An electrode 10 made of a metal such as u, Pt, Pd, Ag, Cr, Ni, or an alloy thereof is laid, and a voltage is applied between the electrodes 10 to generate longitudinal vibration in the piezoelectric ceramic plate 9. The piezoelectric actuator 4 is made to expand and contract in the thickness direction. The piezoelectric actuator 4 is attached to the surface of the diaphragm 1 on the side opposite to the flow path 6 to vibrate the diaphragm 1 and pressurize ink in the flow path 6. As a result, ink is ejected from the ink ejection holes 8 as ink droplets.

FIG. 1 shows a single-layer piezoelectric ceramic plate 9.
The example using the piezoelectric actuator 4 provided with
As shown in FIGS. 2A and 2B, a laminated piezoelectric actuator formed by sequentially laminating a plurality of piezoelectric ceramic plates 9 and electrodes 10 may be used. In the head shown in FIG. As the piezoelectric actuator 4 of the type, a piezoelectric actuator that vibrates longitudinally in the laminating direction by energization between the electrodes 10 is used. In the head shown in FIG. The piezoelectric actuator 4 is used to vertically vibrate in a direction perpendicular to the laminating direction by applying an electric current between the electrodes 10, and the vibrating plate 1 is vibrated up and down in any of the heads. Ink 6 is pressurized, and ink droplets are ejected from an ink ejection hole 8.

According to the head 20 of the present invention, the nozzle plate 3 is formed of a metal plate manufactured by a rolling method, and the rolling direction (the direction of arrow Y) formed on the surface of the metal plate is changed. The plurality of linear uneven portions shown in FIG.
It is characterized by having an angle θ of ゜ to 100 °.

That is, according to the head 20 of the present invention, since the nozzle plate 3 is formed of a metal plate manufactured by a rolling method, it is possible to form an insulating mask by electroforming.
Since the steps of forming a plating layer, peeling off a flat plate and an insulating mask, and the like are not necessary, it is not necessary to control plating time, current, metal concentration in a plating solution, and the like, so that the nozzle plate 3 can be manufactured at low cost. As a result, the inexpensive head 20
Can be provided.

Further, according to the head 20 of the present invention, the direction of the linear uneven portion formed on the surface of the nozzle plate 3 made of a metal plate manufactured by a rolling method (the direction of arrow Y).
Is configured so as to have an angle θ of 80 ° to 100 ° with respect to the direction in which the ink ejection holes 8 are arranged (the direction of arrow X), so that each ink ejection hole 8 provided in the nozzle plate 3 Since it can be arranged so as to be located substantially at the center of the flow path 6 and a part or all of the ink ejection holes 8 are not blocked, a predetermined amount of Ink droplets can be ejected.

That is, on the surface of the metal plate manufactured by the rolling method, a plurality of linear irregularities are formed along the rolling direction, and the metal crystals of the metal plate are extended in the rolling direction. Although the strain is generated inside, the present inventor repeated research on the mechanism, and the heat and the like acted, the strain in the metal plate was relaxed, and the extension of the metal crystal returned to the original state. When returning, it is found that a large dimensional change occurs in the rolling direction of the metal plate, and the dimensional change in a direction perpendicular to the rolling direction is small. By setting the juxtaposition direction to a direction substantially perpendicular to the rolling direction of the metal plate, the nozzle plate 3
Even when the metal plate is distorted due to the heat acting during the manufacture of the nozzle plate and when the nozzle plate 3 is bonded to the flow path member 5 and the dimensional change occurs, the dimensional change in the direction in which the ink ejection holes 8 are arranged is almost the same. Since the nozzle plate 3 is bonded to the flow path member 5 based on the ink discharge holes 8 on one end side, the ink discharge holes 8 on the other end side also
Have been found to be located almost at the center in the width direction, and it has been found that the side wall 2 does not block a part or the whole.

The direction of the linear concave and convex portions (the direction of arrow Y) existing on the surface of the nozzle plate 3 made of a metal plate is set to 80 with respect to the direction in which the ink ejection holes 8 are arranged (the direction of arrow X).
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 3 is changed to the direction of the ink ejection hole 8. , The dimensional change accompanying the relaxation of the distortion becomes large, the shape change of the ink discharge holes 8 and the degree of the dimensional change between the ink discharge holes 8 become too large, and the positional deviation of the ink discharge holes 8 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 metal crystal as it approaches 90 ° with respect to the direction of the linear irregularities formed on the surface of the metal plate. Therefore, it is preferable that the angle θ between the direction of the linear uneven portion (the direction of arrow Y) and the direction in which the ink ejection holes 8 are arranged (the direction of arrow X) is 90 °, and the nozzle plate 3 Can be arranged at the center of the flow path 6 in the width direction.

The metal forming the nozzle plate 3 may be, for example, a metal such as Fe, Mo, Ni, Co, or the like.
-Fe, an alloy mainly composed of Ni-Co or the like can be used. In selecting a material for forming the nozzle plate 3,
In order to reduce the stress at the time of joining, a material having a similar thermal expansion coefficient to the flow path member 5 may be appropriately selected.

Next, a method of manufacturing the ink jet recording head 20 shown in FIG. 1 will be described.

First, the flow path member 5, which constitutes the head 20,
A piezoelectric actuator 4 and a nozzle plate 3 are prepared.

To manufacture the flow path member 5, stainless steel,
Metal plates such as titanium, nickel, copper, and aluminum alloys, alumina, forsterite, steatite, mullite,
A plurality of long holes with both ends closed are provided side by side by etching etc. on a substrate such as a ceramic plate mainly composed of aluminum nitride, a resin composite plate obtained by hardening hard aggregate with resin, a silicon plate, a glass plate, etc. After drilling an ink supply hole 7 on one end side of each slot by laser processing such as a YAG laser or an excimer laser, one surface of the substrate is made of stainless steel so as to cover the opening of each slot. Metal plates such as titanium, nickel, copper, and aluminum alloys, ceramic plates containing alumina, forsterite, steatite, mullite, aluminum nitride, etc. as main components, resin composite plates obtained by hardening hard aggregates with resin, silicon plates, A vibration plate 1 made of a glass plate or the like is attached with a thermosetting adhesive, and a space in which one of the long holes is closed by the vibration plate 1 is used as an ink flow path 6 and each flow path 6 is partitioned. Fabricating the channel member 5 and the side wall 2 to wall.

On the other hand, to manufacture the piezoelectric actuator 4, lead zirconate titanate (P
A piezoelectric ceramic plate 9 made of ZT), lead magnesium niobate (PMN), lead nickel niobate (PNN), or the like is prepared, and Au,
An electrode 10 made of a metal such as Pt, Pd, Ag, Cr, Ni or an alloy thereof is laid and formed by a thin film forming means such as a sputtering method, an ion plating method, a vapor deposition method, or a baking method.

Further, to manufacture the nozzle plate 3, a metal such as Fe, Mo, Ni, Co, or an alloy mainly composed of Ni-Fe, Ni-Co, etc., manufactured by a rolling method is used. After preparing a plate and observing the direction of the linear irregularities formed on the surface of the metal plate (the direction of the streaks) with a metallographic microscope or the like, a plurality of lines are taken with respect to the direction of the linear irregularities (the direction of the streaks). The ink ejection holes 8 are formed by etching or laser processing so that the rows of the ink ejection holes 8 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 streak formed on the surface of the metal plate with a metal microscope or the like.
If the stripes formed on the surface of the metal plate are thin and difficult to determine, the determination 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.

With reference to the ink discharge holes 8 at one end of the nozzle plate 3, the ink discharge holes 8 are positioned so as to be located at the center of the flow path 6 at one end of the flow path member 5.
By bonding the piezoelectric actuator 4 to the surface of the vibration plate 1 on the side opposite to the flow path 6 with a thermosetting adhesive while attaching the piezoelectric actuator 4 to the flow path member 5 with a thermosetting adhesive.
The ink jet recording head 20 of the present invention shown in FIG. 1 can be manufactured. If the ink jet recording head 20 is manufactured by the manufacturing method of the present invention, the ink ejection hole 8 at the other end of the nozzle plate 3 is also located substantially at the center of the flow path 6. The ink jet recording head 20 can be manufactured such that a part or the whole of the ink ejection hole 8 is not blocked by the side wall 2.

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 FIG. 1, the nozzle plate 3 made of only metal has been described. In addition, as shown in FIG.
A polyimide (PI) resin, polyphenylene sulfide (PP) is coated on the surface of the metal plate 21 manufactured by the rolling method.
S) A resin plate 22 made of resin, polyether imide (PEI) resin, polyamide imide (PAI) resin, or the like is attached, and the ink discharge holes 8 are formed in the resin plate 22; A nozzle plate 24 formed by perforating an ink guide hole 23 communicating with the metal plate 21 can also be used. In this case as well, the direction of the linear uneven portion formed on the surface of the metal plate 21 (the direction of the streak) can be used. And the angle θ between the ink ejection holes 8 and the direction in which the ink ejection holes 8 are arranged is 80 ° to 10 °.
What is necessary is just to comprise so that it may become 0 degree.

As described above, it goes without saying that improvements and modifications may be made without departing from the spirit of the present invention.

[0034]

(Example 1) Here, in manufacturing the nozzle plate 3, a metal plate manufactured by a rolling method was used, and the angle between the direction of the streak of the metal plate and the direction in which the ink ejection holes were arranged in parallel was used. An experiment was conducted to examine the amount of deviation in the distance from one end of the ink ejection hole to the other end of the ink ejection hole and the ejection 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 8 having a diameter of 40 μm was formed by 141 μm by an etching method.
1000 nozzle plates 3 were juxtaposed at an m pitch.
At this time, the direction in which the ink ejection holes 8 were arranged was arranged at an angle of 0 ° to 130 ° with respect to the direction of the streaks 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.

[0038]

[Table 1]

As a result, as can be seen from Table 1, the angle between the direction of the stripes of the metal plate and the direction in which the ink ejection holes are arranged is 8 degrees.
Samples e, f, and g in the range of 0 ° to 100 ° have small deviations from the set value of 10 μm or less, and have an angle of 90 ° between the direction of the streaks of the metal plate and the direction in which the ink ejection holes are arranged. The sample f thus obtained was particularly excellent. (Example 2) Next, the ink jet recording head 20 shown in FIG. 1 was manufactured using the nozzle plate shown in Table 1, and ink droplets were ejected, and the ink droplets landed on the recording medium to evaluate the printing characteristics.

First, a plurality of long holes, both ends of which are closed by etching, are arranged side by side on a silicon substrate having a thickness of 300 μm manufactured by a pulling method (CZ method), and ink is supplied to one end side of each long hole by a YAG laser. After the holes 7 are drilled, the diaphragm 1 made of stainless steel having a thickness of 20 μm is attached to one surface of the silicon substrate with an epoxy-based adhesive so as to cover each of the long holes.
The flow path member 5 was manufactured in which the elongated hole closed by the vibration plate 1 was used as the ink flow path 6 and the wall separating the flow paths 6 was the side wall 2. The width of the channel 6 was 100 μm, the depth of the channel 6 was 300 μm, and the pitch of the channel 6 was 141 μm.

Next, a piezoelectric actuator 4 was attached to the surface of the diaphragm 1 on the side opposite to the flow paths 6 with an epoxy-based adhesive. The piezoelectric actuator 4 used was one in which an Au film was formed on the upper and lower main surfaces of a piezoelectric ceramic plate 9 mainly containing lead zirconate titanate (PZT) by a sputtering method.

Then, the nozzle plate 3 shown in Table 1 was aligned with the ink discharge holes 8 and the flow paths 6, and then joined with an epoxy-based adhesive to produce an ink jet recording head 20.

Then, the piezoelectric actuator 4 of the head 20 is driven to vibrate the vibration plate 11 to pressurize the ink in the flow path 6 and eject ink droplets from the ink ejection holes 8 to deposit ink droplets on the recording medium. The print characteristics were evaluated by landing.

The printing characteristics were evaluated by measuring the intervals 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 results were evaluated as variations in the landing positions of ink droplets.

The results are as shown in Table 2.

[0046]

[Table 2]

As a result, as can be seen from Table 2, the sample N
In oa, b, c, d, and h, since the positional deviation of the ink ejection holes is large, the landing positions of the ink droplets vary, and the ejection direction of the ink droplets also varies. Was as large as 7% to 9%.

On the other hand, in the samples e, f, and g, the positional accuracy of the ink discharge holes arranged in parallel to the nozzle plate is good, and the variation in the positions of the respective flow paths of the flow path member and the ink discharge holes is small. Position accuracy of ink droplets landed on recording medium is 1-3%
And excellent printing accuracy could be obtained.

[0049]

As described above, according to the present invention, a plurality of side walls are juxtaposed on a vibration plate, and a flow path member having an ink flow path between each side wall; A piezoelectric actuator provided on the surface on the opposite side to the nozzle, and a nozzle plate joined to the flow path member and provided with an ink ejection hole communicating with each flow path, and the vibration plate is vibrated by driving the piezoelectric actuator. By doing so, in an ink jet recording head that pressurizes ink in the flow path and discharges ink droplets from ink discharge holes, the nozzle plate is formed of a metal plate having a streak extending in one direction on the surface thereof, and Since the angle between the direction of the streak of the nozzle plate and the direction in which the plurality of ink ejection holes are arranged has a positional relationship in the range of 80 ° to 100 °, the nozzle plate is manufactured by a rolling method. Although it is formed of a metal plate, each ink ejection hole provided in the nozzle plate can be arranged so as to be located substantially at the center of the flow path, and a part or all of the ink ejection hole is closed. Therefore, 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. 1A is a partially cutaway perspective view showing an embodiment of an ink jet recording head according to the present invention, and FIG. 1B is an enlarged sectional view of a portion A in FIG. 1A.

FIGS. 2A and 2B are enlarged cross-sectional views showing a part of an ink jet recording head according to the present invention on which various piezoelectric actuators are mounted.

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, 31: diaphragm 2, 32: side wall 3, 33: nozzle plate 4, 34: piezoelectric actuator 5, 35: flow path member 6, 36: flow path 7, 37: ink supply hole 8, 38: ink discharge hole 9, 39: piezoelectric ceramic plate 10, 40: electrode 20, 30: head 21: metal plate 22: resin plate 23: ink guide hole

Claims (1)

[Claims] 1. A flow path member having a plurality of side walls arranged in parallel on a vibration plate and having a flow path of ink between the side walls, and a piezoelectric actuator provided on a surface of the vibration plate opposite to each flow path. And a nozzle plate joined to the flow channel member and having an ink ejection hole communicating with each flow channel. By vibrating the vibration plate by driving the piezoelectric actuator, the ink in the flow channel is discharged. In an ink jet recording head that pressurizes and discharges ink droplets from ink discharge holes, the nozzle plate is formed of a metal plate having linear irregularities extending in one direction on its surface, An angle between the direction of the linear concavo-convex portion and the direction in which the plurality of ink ejection holes are arranged is 80 ° to 100 °.