JP2002160363A - Ink jet head and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head and a method for manufacturing the same which applies a static electricity, does not generate a sticking, can be easily manufactured by applying a semiconductor process, and further prevents occurrence of electric short circuit. SOLUTION: A small insulating projection having an opposite surface in opposition to the other electrode and a ratio of projecting height to a diameter of a minimum circle of 0.1 or less is provided in at least one of a movable electrode driven by a actuator and a fixed electrode. The small insulating projection is formed by etching a thin isolating film layer for forming the small insulating projection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head using an electrostatic actuator for discharging ink droplets, and a method of manufacturing the ink jet head.

[0002]

2. Description of the Related Art Ink jet printers have become widespread today. In general, a part of an ink liquid is rapidly boiled to generate bubbles, and ink droplets are ejected by utilizing the expansion force of the bubbles. Or a piezo method in which a piezo element is vibrated by an applied voltage to discharge ink droplets from an ink discharge nozzle. On the other hand, various systems using actuators utilizing electrostatic force for discharging ink droplets have been proposed today.

Here, as shown in FIG. 7, an ink jet head using electrostatic force is provided on a diaphragm 102 having a thin film movable electrode 104 outside a surface on which an ink liquid chamber 100 is formed, for example, a bottom surface. The voltage V is applied between the thin-film movable electrode 104 and the thin-film fixed electrode 106 arranged in parallel to the thin-film movable electrode 104, and the diaphragm 102 is displaced as indicated by a broken line in FIG. The ink supplied from the ink supply hole 108 and filled in the ink liquid chamber 100 is
2 is ejected as an ink droplet 110.

Here, the material of the thin-film movable electrode 104 and the thin-film fixed electrode 106 is limited to those having conductivity. For example, a metal material such as platinum (Pt) is used. However, in a manufacturing process or a driving process of the inkjet head, a small amount of fine particles are mixed between the thin film movable electrode 104 and the thin film fixed electrode 106, so that the thin film movable electrode 104 and the thin film fixed electrode 106 are easily electrically short-circuited. In some cases, the ejection of ink droplets is not performed correctly. In addition, even if fine particles do not enter between the thin-film movable electrode 104 and the thin-film fixed electrode 106, the distance between the electrodes becomes extremely small, and discharge occurs. Sometimes it can easily happen.

To solve the problem of the discharge of the ink jet head utilizing such electrostatic force, Japanese Patent Application Laid-Open No. 7-21476 discloses a method.
No. 9 and JP-A-11-286108 disclose means for preventing discharge. JP-A-7-2147
In Japanese Patent Publication No. 69, an electrode of the diaphragm forms an oxide film on the entire surface of the diaphragm facing the other electrode so that no discharge occurs when the electrode provided on the diaphragm comes into contact with the facing electrode. On the other hand, in JP-A-11-286108, an insulating member made of a shock absorbing material is provided, or insulating particles are arranged. Thereby, any means can prevent an electric short circuit.

[0006]

However, Japanese Patent Application Laid-Open No. Hei 7-2
In Japanese Patent No. 14769, since an electrode of the vibration plate has an oxide film formed on one surface facing the other electrode, a voltage is applied when performing anodic bonding for assembling the substrates of the ink jet head, When the device is operated by applying an electric charge, electric charges accumulate on the insulating film, and even if this electric charge is removed, a minute surface force is generated,
Sticking (sticking) with the facing electrode is likely to occur. On the other hand, in JP-A-11-286108, an insulating member made of a shock absorbing material is provided or insulating particles are used. However, a normal semiconductor manufacturing process cannot be used, and a special manufacturing process is required. Therefore, it is not possible to easily and mass-produce an ink jet head in which an electric short circuit is prevented.

[0007] With the demand for higher density ink jet heads today, the width of the vibration plate is reduced in order to narrow the distance between adjacent ink discharge nozzles, and accordingly, the ink discharge amount is kept constant. In order to achieve this, the diaphragm is elongated, and the thin-film movable electrode 104 and the thin-film fixed electrode 10
6 tends to be narrower. Under such circumstances, when the distance between the thin-film movable electrode 104 and the thin-film fixed electrode 106 is reduced and an elongated diaphragm is arranged, an electric short circuit and sticking are more likely to occur.

In order to solve the above problems, the present invention is directed to an ink jet head utilizing electrostatic force, which does not cause sticking and can be easily manufactured in a semiconductor manufacturing process. It is another object of the present invention to provide an ink jet head for preventing an electric short circuit and to provide a method for manufacturing the ink jet head.

[0009]

In order to achieve the above object, the present invention provides an ink discharge nozzle, an ink liquid chamber communicating with the ink discharge nozzle, and a diaphragm forming one surface of the ink liquid chamber. A movable electrode provided on the vibrating plate, and a fixed electrode disposed outside the ink liquid chamber and spaced apart from the movable electrode by a minute distance in parallel, and applying a voltage between the movable electrode and the fixed electrode. An ink jet head that ejects ink from the ink liquid chamber by vibrating the vibrating plate, wherein at least one of the movable electrode and the fixed electrode has, at its tip, a facing surface facing the other electrode. An ink-jet head comprising an insulating microprojection, wherein a ratio of a height of the projection to a diameter of a minimum circle including the shape of the facing surface is 0.1 or less. It is intended to provide.

Here, it is preferable that a plurality of the insulating microprojections are provided, and it is preferable that the insulating microprojections are regularly arranged. Further, it is preferable that at least two or more insulating microprojections have a common base common to each other. Further, it is preferable that the diaphragm has a rectangular shape, and the opposed surface has a rectangular shape having a short side in a short side direction of the rectangular shape of the diaphragm.

Further, the present invention provides an ink discharge nozzle, an ink liquid chamber communicating with the ink discharge nozzle, a diaphragm forming one surface of the ink liquid chamber, a movable electrode provided on the vibration plate, A fixed electrode disposed outside of the ink liquid chamber and parallel to the movable electrode at a minute distance from the movable electrode, and applying a voltage between the movable electrode and the fixed electrode to vibrate the diaphragm to thereby form the ink. When manufacturing an inkjet head that ejects ink from the liquid chamber,
After forming at least one electrode thin film layer of the movable electrode and the fixed electrode on the substrate, a first mask forming step of forming a first patterning mask for forming an electrode, and the first mask forming step are performed. An insulating thin film layer forming step of forming an insulating thin film layer on a substrate, and a second mask forming step of forming a second patterning mask for forming insulating minute projections at an electrode forming position on the insulating thin film layer A step of etching the insulating thin film layer using the first patterning mask as at least a lowermost etching stop layer; and a mask removing step of removing the first patterning mask and the second patterning mask. By forming an insulating microprojection on at least one of the movable electrode and the fixed electrode. There is provided a method of manufacturing that the ink jet head.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet head of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1A shows a preferred embodiment of an ink jet head according to the present invention, and shows a structure of an ink jet head 10 corresponding to one ink discharge nozzle. FIG. 1B shows a cross-sectional configuration of the inkjet head when cut along the line XX ′ in FIG. 1A. The ink jet head 10 includes a substrate 12,
The substrate 12 has a laminated structure in which three layers 4 and 16 are joined by anodic bonding or the like.
Is provided, and the ink liquid chamber 1 is
8 is formed, and an ink supply path 20 for supplying ink to the ink liquid chamber 18 is formed. Ink supply path 2
0 is connected to a supply path extending in the vertical direction toward the paper surface of FIG. 1A, and this supply path is connected to an ink tank (not shown).

The thickness of the substrate 14 is partially reduced on the bottom surface of the ink liquid chamber 18, and a vibration plate 19 which is easily deformed by electrostatic force is formed as described later. A thin film movable electrode 22 is arranged on the lower surface of the substrate 14, and a common terminal (not shown) of the thin film movable electrode 22 is provided at an end of the substrate 14. Here, the substrate 14,
Reference numeral 16 may be a substrate provided with an insulating layer such as SiO _{2 on} a semiconductor such as Si or a substrate made of Pyrex (registered trademark) glass. On the substrate 16, thin film fixed electrodes 26 are arranged in parallel with the thin film movable electrode 22 at a minute interval, for example, at a distance of 3 μm. (Not shown). As the electrode material of the thin film movable electrode 22 and the thin film fixed electrode 26, for example, Cr
-Pt-Cr three-layer metal or Ti-Pt-Ti
In addition to metal having a layer structure, Al, Si, ITO, or the like is used.

A predetermined control voltage V is applied like a pulse between the common terminal and the unique terminal, and the thin film movable electrode 2
2 and the thin film fixed electrode 26 are configured such that a potential difference is generated according to the input data D. Since the thin-film movable electrode 22 and the thin-film fixed electrode 26 having the potential difference have conductivity, they are charged to different polarities, and as a result, an electrostatic force acts between the electrodes, so that the diaphragm 19 becomes convex downward. On the other hand, when the potential difference is released while deforming, the vibration plate 19 is restored, the pressure in the ink liquid chamber 18 rapidly rises, and the ink droplets are ejected from the ink ejection nozzles 13.

Here, the upper layer of the thin film movable electrode 22 has S
A semiconductor thin film layer made of i or the like is formed, and a plurality of insulating minute protrusions 30 are regularly arranged on the surface of the semiconductor thin film layer. On the upper layer of the thin film movable electrode 22, S
The reason why the semiconductor thin film layer 28 made of i or the like is formed is to prevent an electrical short circuit caused by approaching the thin film movable electrode 22 and the thin film fixed electrode 26 when they come into contact with each other or not. . By providing the semiconductor thin film layer 28, an electrical short circuit can be prevented as compared with the case where the thin film movable electrode 22 and the thin film fixed electrode 26 are made of a conductive metal, and the thin film movable electrode 22 and the thin film fixed electrode 26 are made of a semiconductor. As compared with the case of the configuration, the electric resistance does not increase, the time constant when used as an actuator can be reduced, and the responsiveness of the diaphragm 19 can be improved.

The insulating microprojections 30 are provided on the semiconductor thin film layer 28 by the ink jet head 1.
At the time of anodic bonding at the time of assembling and the driving of the vibration plate 19, the surface layer (semiconductor thin film layer 28) of the thin film movable electrode 22 and the surface layer of the thin film fixed electrode 26, which are polarized and have accumulated surface charges, are mutually connected. This is to prevent sticking. Also, the insulating minute projections 30 are
In addition, since a plurality of thin-film movable electrodes 22 and thin-film fixed electrodes 26 are not fixed, an electric short circuit can be prevented. Here, as a material of the insulating minute projections 30, SiO ₂ , Al ₂ O ₃ , Si ₂ N ₄ , Si
Insulating materials such as C and Ta ₂ O ₅ are mentioned. By providing the insulating minute projections 30, the surface layer of the thin film movable electrode 22 and the surface layer of the thin film fixed electrode 26 are separated from each other by a certain distance without contacting each other. It is not always necessary to form the layer 28 on the thin film movable electrode 22. The semiconductor thin film layer 28 may be provided on the thin film fixed electrode 26. Further, the semiconductor thin film layer 2
8 may not be provided at all.

FIG. 1 (c) shows such an arrangement of the insulating minute projections 30. As shown in FIG. The diaphragm 19 has a narrower width in the arrangement direction of the ink discharge nozzles of the diaphragm 19 with the increase in the density of the ink discharge nozzles of the ink jet head. The length in the direction orthogonal to the nozzle arrangement direction is longer. For example, the shape of the diaphragm 19 is such that the length A is approximately 1 m.
The width B is 40 μm with respect to m. In the present invention, the width B of the diaphragm 19 is 150 μm or less, more preferably 80 μm or less.

According to the shape of the diaphragm 19,
The shape of the opposing surface 33 of the insulating minute projection 30 is also rectangular, and the short side of the rectangular shape at that time matches the short side direction of the diaphragm 19, and the long side direction of the diaphragm 19 is the long side of the rectangular shape. The configuration matches the direction. Thus, the short side of the rectangular shape of the opposing surface 33 of the insulating minute protrusion 30 is
The reason why the diaphragm 19 is arranged so as to coincide with the short side direction is to take into account the magnitude of a change in curvature when the diaphragm 19 is deformed when the diaphragm 19 is deformed by receiving a predetermined control voltage V. . That is, when the diaphragm 19 is deformed by being pulled by the thin film fixed electrode 26, the change in the curvature in the long side direction of the diaphragm 19 is small and the change in the curvature in the short side direction is large. Therefore,
At this time, the insulating minute protrusions 30 are not subjected to a large bending stress in the short side direction due to the change in the curvature in the short side direction, so that separation or cracking is not generated in the short side direction of the diaphragm 19. The short side of the projection 30 is arranged.

Further, the insulating microprojection 30 has at its tip an opposing surface 33 facing the thin-film fixed electrode 26, and the height of the insulating microprojection 30 with respect to the diameter of the smallest circle including the shape of the opposing surface. Is 0.1 or less. For example, the diameter d of the smallest circle including the rectangular shape of the opposing surface 33 of the insulating minute protrusion 30 (see FIG. 1D) is approximately 2 to 4 μm.
m or more, and the upper limit is 30 μm.
On the other hand, the protrusion height h (see FIG. 1 (e)) of the insulating minute protrusion 30 is approximately 0.1 to 0.2 μm or less,
The lower limit is 0.01 μm. With such a configuration of the insulating microprojections 30, sticking can be prevented, and as described later, by using a surface micromachining process using a semiconductor manufacturing process, the insulating microprojections can be efficiently formed. Protrusions can be created.

The opposing surface 33 of the insulating microprojection 30 facing the thin-film fixed electrode 26 has a rectangular shape. However, the present invention is not limited to this, and the height of the insulating microprojection is not limited to this. Any shape such as a triangle or a circle may be used as long as it satisfies the condition that the ratio of the diameter of the smallest circle including the shape of the facing surface 33 to the diameter is 0.1 or less. Also,
The insulating microprojections 30 are provided on the surface of the thin-film movable electrode 22 with the semiconductor thin-film layer 28 interposed therebetween. However, the present invention is not limited to this. The surface of the thin-film fixed electrode 26 or the semiconductor thin-film layer 28 May be provided on the surface layer of the thin-film movable electrode 22 and the surface layer of the thin-film fixed electrode 26 via a thin film. In this embodiment, the semiconductor thin film layer 28 is provided on the thin film movable electrode 22.
6 may be provided.

Such an ink jet head 10 has
In a recording control unit (not shown), a control voltage signal based on a discharge sequence for discharging ink droplets from the ink liquid chamber 18 is created from input data for performing recording, and a desired control is performed on the thin film fixed electrode 26 from a unique terminal. Voltage V
Is applied. On the other hand, since the common terminal is connected to the ground, when a desired control voltage V is applied to the thin-film fixed electrode 26, the thin-film fixed electrode 26 and the thin-film movable electrode 22
In this case, different electric charges are accumulated and charged, and the diaphragm 19 provided with the thin film movable electrode 22 is deformed by electrostatic force. As a result, the pressure of the ink liquid chamber 18 decreases, so that ink flows from the ink supply path 20 to fill the ink liquid chamber 18.
Thereafter, when the control voltage V is released in accordance with the control voltage signal, the diaphragm 19 is restored, and the ink filled in the ink liquid chamber 18 is discharged from the ink discharge nozzle 13 as ink droplets.

When the diaphragm 19 is deformed by an electrostatic force, the insulating micro-projections 30 are provided on the surface of the thin-film movable electrode 22 via the semiconductor thin-film layer 28.
2 and the surface layer of the thin-film fixed electrode 26 do not stick. In addition, the inkjet head 1
At the time of joining the substrate 14 and the substrate 16 at the time of assembling 0,
Bonding is performed by applying one of the substrate 14 and the substrate 16 as an anode and the other as a cathode, for example, by applying a DC voltage of 500 V while heating at 300 ° C. Is a thin film movable electrode 2
2, the surface layer of the thin-film movable electrode 22 and the surface layer of the thin-film fixed electrode 26 do not stick.

The formation of the insulating microprojections 30 on the thin film movable electrode 22 or on the semiconductor thin film 28 can be performed by a micromachining technique using a semiconductor manufacturing process. FIGS. 2A to 2I show a method of forming three insulating microprojections 30. FIG. Note that an ink liquid chamber 18 is formed on the upper surface side of the substrate 14 in the drawing after this step. First, as shown in FIG. 2A, a patterning mask for forming the thin film movable electrode 22 using the photoresist 80 is formed on the surface of the substrate 14 by using a known photolithography technique, as shown in FIG. 2B. A conductive metal layer 5 having a three-layer structure of Cr-Pt-Cr.
2 is laminated on the substrate 19 on which the patterning mask of the photoresist 80 is formed by using known sputtering. For example, the thickness of each of the Cr layers is 0.01 μm, and the thickness of the Pt layer is 0.09 μm.

Next, as shown in FIG. 2C, the conductor metal layer 82 formed on the photoresist 50 is lifted off using acetone, and the conductor electrode 22 and the conductor electrode 22 are lifted off.
To form a conductive metal layer 82 'extending from the substrate to the common electrode. Next, on the substrate 14 on which the conductive metal layer 82 'is formed, FIG.
As shown in (d), a photoresist 84 is coated,
A patterning mask is formed by using a known photolithography technique. Here, the photoresist 84 at the position 86 where the thin film conductor electrode 22 is formed is removed.

Next, as shown in FIG. 2E, the substrate 14 on which a patterning mask is formed with a photoresist 84 is formed.
A semiconductor thin film layer 88 made of, for example, Si having a thickness of 0.09 μm is formed thereon by sputtering, and the photoresist 84 is removed to form the thin film conductor electrode 22 as shown in FIG. All are lifted off except for the semiconductor thin film layer 88 ′ which is stacked at the position 86 which is to be stacked. Thus, the conductive metal layer 8 is formed on the substrate 14.
2 ′ and a semiconductor thin film layer 88 ′ are formed.

Next, as shown in FIG. 2G, a patterning mask of a photoresist 90 is formed by using a photolithography technique. Here, a patterning mask of a photoresist 90 for forming the insulating minute projections 30 is formed at the position 86 where the thin film conductor electrode 22 is to be formed. Next, as shown in FIG.
In addition to the entire surface of the semiconductor thin film layer 88 ′, SiO
₂ is formed by sputtering. For example, the thickness of the insulating thin film layer 60 is set to 0.1.
2 μm. Next, the photoresist 90 is entirely removed, and the insulating thin film layer 90 is lifted off. Thus,
The thin-film fixed electrode 22, the semiconductor thin-film layer 28, the insulating minute projections 30, and the thin-film conductor layer 82 'from the thin-film movable electrode 22 to the common terminal are formed.

Here, as shown in FIG. 3, the insulating minute protrusion 30 is located at the position 86 where the thin film movable electrode 22 is formed.
The photoresist 90 (shaded portion) under the insulating thin film layer 92 made of iO ₂ is removed, and the insulating thin film layer 92 located above is also removed at the same time. Portions 92a, 92b and 92c of the insulating thin film layer 92 where the projections 30 are to be formed
May also be removed together. Further, when the photoresist 90 (shaded portion) is removed, even if the insulating thin protrusions 30 are not removed to the portion of the insulating thin film layer 92 where the insulating fine protrusions 30 are to be formed, the insulating fine protrusions 30 are easily peeled off and become insulative. There is a problem that the projection 30 is formed. Accordingly, the present invention provides a method for manufacturing an ink jet head described below.

Hereinafter, the production of the ink jet head of the present invention will be described.
The fabrication method will be described. The inkjet head of the present invention
The method for manufacturing the microstructure is to form the insulating microprojections as described above into a thin film.
A method of providing the movable electrode on the surface layer, the method comprising:
For surface micromachining process
This is what is done. 4A to 4J,
As an example of the method of manufacturing the ink jet head of the present invention
The diaphragm 19 shown in FIG. 1 is made of Pyrex glass.
On this diaphragm 19, a three-layer structure of Cr-Pt-Cr is provided.
A conductive metal thin film movable electrode 22 made of
A semiconductor thin film layer made of Si as the semiconductor thin film layer 28;
28, and an upper layer of SiO 2 _TwoInsulating micro protrusion made of
3 shows a series of steps for providing an inset 30. Here,
Shows the formation of two insulating microprojections 30.

First, as shown in FIG.
On the surface of the thin film movable electrode 22 of the photoresist 50
A patterning mask for formation is formed by using a known photolithography technique, and as shown in FIG.
A conductor metal layer 52 having a three-layer structure of -Cr is formed on the substrate 19 on which the patterning mask of the photoresist 50 is formed by using known sputtering. For example, C
The thickness of each of the r layers is 0.01 μm, and the thickness of the Pt layer is 0.9.
μm.

Next, as shown in FIG. 4C, the conductor metal layer 52 formed on the photoresist 50 is lifted off using acetone, and the conductor electrodes 22 and 22 are lifted off.
To form a conductive metal layer 52 'extending from the substrate to the common terminal. Next, on the substrate 14 on which the conductive metal layer 52 'is formed, FIG.
As shown in (d), a photoresist 54 is coated,
Using a known photolithography technique, a patterning mask for forming an electrode is formed (first mask forming step). Here, the photoresist 54 at the position 56 where the thin film conductor electrode 22 is formed is removed.

Next, as shown in FIG. 4E, the substrate 14 on which a patterning mask is formed with a photoresist 54 is formed.
A semiconductor thin film layer 58 made of, for example, 0.09 μm in thickness is formed by sputtering on the top, and an insulating thin film layer 60 made of SiO ₂ is formed by sputtering, as shown in FIG. (Insulating thin film layer forming step). The thickness of the insulating thin film layer 60 is, for example, 0.2 μm. Note that, as described above, the semiconductor thin film layer 28 in FIG.
The formation of the semiconductor thin film layer 58 made of may be omitted.

Next, as shown in FIG. 4G, a patterning mask of a photoresist 62 is formed at a position 56 where the thin-film conductor electrode 22 is to be formed (second mask forming step). This patterning mask is composed of insulating microprojections 3
This is a patterning mask for forming 0. further,
Next, as shown in FIG. 4H, a photoresist 64 is applied to the back surface of the substrate 14. The reason why the photoresist 64 is applied is to prevent the back surface of the substrate 14 from being etched during the wet etching performed in the next step.

Next, as shown in FIG.
H_Four9: 100 SiO composition of F _TwoUse etchant
Etching for a predetermined time
The insulating thin film layer 60 is removed except for the portion protected by
(Etching step). At that time, the photoresist 5
4 is at least the lowermost etching stop layer.
In this embodiment, the semiconductor thin film layer 58 made of Si
The lower layer is not etched, but in the present invention
Is, as described above, the semiconductor thin film layer 58 made of Si.
When the formation is not performed, the photoresist 54 and the thin film are movable.
The conductive metal layer 52 'forming the electrode 22 is etched away.
It becomes a top layer.

Finally, as shown in FIG. 4J, by removing the photoresist 54, the semiconductor thin film layer 58 is lifted off, and the photoresist 62 is removed (mask removing step). Thereby, the thin film movable electrode 2
2, the semiconductor thin film layer 28 and the insulating microprojections 30,
Further, a conductive metal layer 52 'from the thin film movable electrode 22 to the common terminal is formed. Thus, the height of the protrusion is 0.2 μ
m or less, it is possible to easily form an insulating microprojection having a shape in which the diameter of the smallest circle including the shape of the opposing surface of the insulating microprojection is 1 to 4 μm or more.

In the above-described manufacturing method, as shown in FIG. 5, the insulating thin film layer 60 made of SiO ₂ in the hatched portion is removed by etching, so that minute insulating minute projections 30 are formed. By performing lift-off using a photoresist as in the method (1), the insulating minute protrusions 30 are formed in the semiconductor thin film layer 28 and the thin film movable electrode 22 during the process as compared with the case where the insulating minute protrusions 30 are formed. Peeling from the surface is extremely small, and the insulating minute projections 30 are not formed in a state where the peeling is easy. Of course,
Depending on the shape and size of the insulating microprojections 30, the insulating microprojections 30 may be formed using the above-described conventional method.

The ink-jet head 10 is shown in FIG.
As shown in (c), the diaphragm 19 is arranged in two rows near the center of the diaphragm 19 at regular intervals in the long side direction of the diaphragm 19, but the present invention is not limited to this. There may be three or more rows. Further, as shown in FIGS. 6A and 6B, the diaphragms 19 may be arranged in a row near the center of the diaphragm 19. Further, as shown in FIG.
The long side of the opposing surface 33 of the insulating minute projection 30 may be set to the short side direction of the diaphragm 19 as long as the insulating minute projection 30 does not peel or crack due to deformation of the diaphragm 15.

As shown in FIGS. 6 (c) and 6 (c '), the microprojection forming member 32 having a common base 31 having a common base of the plurality of microprojections 30' is connected to the insulating microprojections 30. As shown in FIG.
May be arranged instead. In this case, the projection height of the minute projection 30 'refers to the height from below the common base 31 to the opposing surface of the tip of the minute projection 30'.

Although the ink jet head and the method of manufacturing the ink jet according to the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. Of course you can do it.

[0040]

As described above in detail, sticking does not occur because the insulating minute protrusion is provided on at least one of the thin film movable electrode and the thin film fixed electrode. Also,
Since the ratio of the height of the protrusion to the diameter of the smallest circle including the shape of the facing surface provided at the tip of the insulating minute protrusion is set to 0.1 or less, the ink jet head can be easily manufactured using a semiconductor process. Further, by forming a plurality of such insulating minute protrusions, an electrical short circuit can be prevented even when the distance between the thin film movable electrode and the thin film fixed electrode is not constant. In addition, the insulating microprojections are separated from each other by forming the opposed surfaces of the insulating microprojections in the short side direction of the rectangular shape of the diaphragm so that the short sides are aligned with respect to the rectangular diaphragm. It becomes difficult. Further, since the insulating minute protrusions are formed by using the etching process, the insulating minute protrusions do not peel off during the manufacturing process unlike the conventional case.

[Brief description of the drawings]

FIG. 1A is a configuration diagram illustrating a schematic configuration of an example of an inkjet head according to the present invention, and FIG.
It is sectional drawing seen from the XX 'line in (a), (c)
FIGS. 2A and 2B are front views of the diaphragm shown in FIG. 1A, and FIGS. 1D and 1E are diagrams illustrating an insulating microprojection shown in FIG.

FIGS. 2A to 2I are explanatory views illustrating a process of forming a conventional insulating minute projection.

FIG. 3 is an explanatory diagram illustrating a main part of a step of forming the insulating minute protrusions of FIG. 2;

FIGS. 4A to 4J are explanatory views illustrating an example of steps of a method for manufacturing an ink jet head according to the present invention.

FIG. 5 is an explanatory diagram illustrating a main part of a step of forming the insulating minute projections illustrated in FIG. 4;

FIGS. 6A to 6C and 6C 'are views showing another embodiment of the insulating projection of the ink jet head of the present invention.

FIG. 7 is a configuration diagram illustrating a schematic configuration of a conventional inkjet head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ink jet head 12, 14, 16 Substrate 18 Ink liquid chamber 20 Ink supply path 22 Thin film movable electrode 26 Thin film fixed electrode 28, 58, 88 Semiconductor thin film layer 30 Insulating micro projection 31 Common base 32 Micro projection forming member 50, 54, 62, 64, 80, 90 Photoresist 52, 82 Conductive metal layer 60, 92 Insulating thin film layer

Claims (6)

[Claims] An ink discharge nozzle, an ink liquid chamber communicating with the ink discharge nozzle, a vibrating plate forming one surface of the ink liquid chamber, a movable electrode provided on the vibrating plate,
A fixed electrode disposed outside of the ink liquid chamber and parallel to the movable electrode at a minute distance from the movable electrode, and applying a voltage between the movable electrode and the fixed electrode to vibrate the diaphragm to thereby form the ink. An ink jet head that ejects ink from a liquid chamber, wherein at least one of the movable electrode and the fixed electrode has a projection at a tip end that opposes the other electrode,
An ink-jet head comprising an insulating minute protrusion having a ratio of a height of the protrusion to a diameter of a minimum circle including the shape of the facing surface of 0.1 or less. 2. The ink jet head according to claim 1, wherein a plurality of said insulating minute projections are provided. 3. The ink jet head according to claim 2, wherein said insulating minute projections are regularly arranged. 4. The at least two or more insulating micro projections,
The inkjet head according to claim 2, wherein the inkjet head has a common base common to each other. 5. The diaphragm according to claim 1, wherein the diaphragm has a rectangular shape, and the facing surface has a rectangular shape having a short side in a short side direction of the rectangular shape of the diaphragm. Ink jet head. 6. An ink discharge nozzle, an ink liquid chamber communicating with the ink discharge nozzle, a vibration plate forming one surface of the ink liquid chamber, a movable electrode provided on the vibration plate,
A fixed electrode disposed outside of the ink liquid chamber and parallel to the movable electrode at a minute distance from the movable electrode, and applying a voltage between the movable electrode and the fixed electrode to vibrate the diaphragm to thereby form the ink. In manufacturing an inkjet head for discharging ink from a liquid chamber, after forming at least one electrode thin film layer of the movable electrode and the fixed electrode on a substrate, a first patterning mask for forming an electrode is formed. A mask forming step; an insulating thin film layer forming step of forming an insulating thin film layer on the substrate having undergone the first mask forming step; A second mask forming step of forming a second patterning mask of the above, wherein the first patterning mask is at least a lowermost etching stop layer, By performing an etching step of etching the edge thin film layer and a mask removing step of removing the first patterning mask and the second patterning mask, at least one of the movable electrode and the fixed electrode has an insulating property. A method for manufacturing an ink-jet head, wherein a minute projection is formed.