JP2003094663A - Ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable ink-jet head capable of keeping electrical resistance values of a resistance layer and an electrode layer nearly constant over a long period. SOLUTION: The ink-jet head is provided with a head substrate 1 formed of a base plate 2 having the resistance layer 3 and a pair of the electrode layers sequentially fixed on its undersurface and of a protective film 5 covering these layers, and a top plate 6 facing top surface of the base plate 2 so as to form a predetermined clearance in between. Heat energy generated by supplying power to the resistance layer 3 is transmitted to ink 8 filled in the clearance via the base plate 2. A print is formed by making the ink 8 discharged from a discharging hole 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet head for recording an image by depositing ink droplets on a recording paper in a predetermined pattern.

[0002]

2. Description of the Related Art Conventionally, an ink jet head has been used as a recording device for forming an image on recording paper.

The ink jet head recording method uses a thermal energy generated by a heat generating resistor to eject and fly an ink droplet toward a recording sheet, a method using a deformation of a piezoelectric element, and an electromagnetic wave. There are those that utilize the heat generated by irradiation, and among these, the thermal jet type that utilizes the thermal energy of the heating resistor is easy to pattern the heating resistor,
Since even a heating resistor having a small area can generate a relatively large amount of heat energy, it is attracting attention as being suitable for high density recording.

As such a thermal jet type ink jet head, for example, as shown in FIG. 4, a resistance layer 13, a pair of electrode layers 14, and a protective film 15 are sequentially formed on the upper surface of a base plate 12 made of single crystal silicon or the like. A top plate 16 having a plurality of ink ejection holes 17 is arranged on the head substrate 11 formed as described above so as to form a predetermined gap therebetween, and the head substrate 11-top plate 16
It is known to have a structure in which a gap is filled with the ink 18, and the heat generating portion of the resistance layer 13 (a region located between a pair of electrode layers) while conveying the recording paper along the outer surface of the top plate 16. Power is applied to 13a through the electrode layer 14 to selectively cause the heat generating portion 13a of the resistance layer 13 to generate Joule heat.
Bubbles A are generated in the ink 18 on the heat generating portion 13a by these thermal energies, and the ink 18 on the heat generating portion 13a is pushed upward by the pressure of the generated bubbles A, and a part of the ink 18 is ejected. A predetermined image is recorded by ejecting the ink from the hole 17 toward the recording paper.

The protective film 15 on the head substrate 11 is
Alkali ions, water, etc. contained in the ink 18 come into contact with the resistance layer 13, the electrode layer 14 etc. to corrode them, or a cluster of dye contained in the ink 18 causes resistance layer 13 etc. This is to prevent sticking to the heat-generating part of the device, adopts thin film processes such as the well-known CVD (chemical vapor deposition) method and sputtering method, and uses inorganic materials such as silicon nitride and silicon oxide. It was formed by depositing a predetermined thickness on the upper surface of the base plate 12.

[0006]

When the protective layer 15 of the ink jet head is formed by a thin film process such as sputtering, many fine film defects such as pinholes are formed in the protective layer 15.

Therefore, when the water contained in the ink 18 or the ions of K ⁺ , OH ^−, etc. come into contact with the resistance layer 13 or the electrode layer 14 through the film defect of the protective layer 15, the resistance layer 13 or the electrode is formed. The layer 14 is corroded, and the electric resistance of these layers fluctuates significantly.

The present invention has been devised in view of the above drawbacks, and an object thereof is to provide a highly reliable ink jet head capable of keeping the electric resistance values of a resistance layer and an electrode layer substantially constant for a long period of time. Especially.

[0009]

In an ink jet head of the present invention, a resistance layer and a pair of electrode layers are sequentially deposited on the lower surface of a base plate, and these are covered with a protective film. An ink which is provided facing the upper surface so as to form a predetermined gap therebetween, and the thermal energy generated by energization of the resistance layer is filled in the gap through the base plate. It is characterized in that a print image is formed by transmitting the ink to the ink and discharging the ink from the ink discharge hole.

Further, the ink jet head of the present invention is characterized in that the thickness of the base plate is set to 1 μm to 5 μm.

Further, the ink jet head of the present invention is characterized in that the head substrate is placed and fixed on the upper surface of the support plate.

Furthermore, the ink jet head of the present invention is characterized in that the base plate is formed of silicon oxide obtained by thermally oxidizing single crystal silicon.

Furthermore, the ink jet head of the present invention is characterized in that there is no pinhole in the base plate.

According to the ink jet head of the present invention,
Since the ink is configured to come into contact with the surface (upper surface) opposite to the lower surface of the base plate provided with the resistance layer and the electrode layer, moisture contained in the ink and ions such as K ⁺ and OH ⁻ are included. An attempt to contact the resistance layer or the electrode layer can be satisfactorily blocked by the base plate having no pinhole or the like, and the electric resistance value of the resistance layer or the electrode layer can be kept substantially constant for a long period of time. Therefore, the reliability of the inkjet head is improved.

Further, according to the ink jet head of the present invention, by setting the thickness of the base plate as thin as 1 μm to 5 μm, the heat generated by the resistance layer can be quickly transferred to the ink through the base plate. The thermal response characteristics of the inkjet head can be maintained high.

Further, according to the ink jet head of the present invention, by mounting and fixing the head substrate on the upper surface of the support plate, even when the thickness of the head substrate is extremely thin, the ink jet head is used. It is possible to effectively prevent the head substrate from being deformed, damaged, and the like, and it is possible to hold the entire structure in a desired structure.

Further, according to the ink jet head of the present invention, if a plate made of silicon oxide formed by thermally oxidizing single crystal silicon is used as the base plate, there will be no defects such as pinholes. A good base plate can be obtained relatively easily, and there is an advantage that the reliability and productivity of the inkjet head can be further improved.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention, FIG. 2 is a sectional view of the inkjet head of FIG. 1, and 1 is a head substrate, 6 is a top plate, 8 is a head substrate 1-top plate. Ink filled between 6 and 9 is a support plate.

In the head substrate 1, a resistance layer 3 and a pair of electrode layers 4 and 4 are sequentially deposited and formed on the lower surface of a base plate 2 formed in a rectangular shape, and these are covered with a protective film 5. It has a structure.

The base plate 2 is formed of a silicon oxide plate body having no pinholes or the like, and the thickness thereof is set to, for example, 1 μm to 5 μm.

The base plate 2 serves as a support base material for supporting the resistance layer 3 and the electrode layer 4 on its lower surface, and as a sealing member for blocking the resistance layer 3 and the electrode layer 4 from the ink 8 described later. First, the surface of single crystal silicon is oxidized by a conventionally known thermal oxidation method to form silicon oxide, and thereafter, the silicon oxide portion is reduced to 1 μm.
It is manufactured by slicing to a thickness of m to 5 μm or by removing a portion of single crystal silicon by etching.

As described above, when the plate body made of silicon oxide formed by thermally oxidizing single crystal silicon is used as the base plate 2, a high quality base plate free from defects such as pinholes is relatively simple. In addition, it is possible to improve the reliability and productivity of the inkjet head.

The resistance layer 3 provided on the lower surface of the base plate 2 is made of TaN, TaSiO, TaSiN.
An electric resistance material such as O, TiSiO, TiSiCO, and NbSiO is deposited to a thickness of, for example, 0.01 μm to 0.15 μm, and the region located between the pair of electrode layers 4 and 4 functions as the heating element 3a. To do.

The heating element 3a is, for example, 600 dpi (dot per inch) in the longitudinal direction of the base plate 2.
Are arranged in a straight line at a density of
When the power source power is applied through the device, Joule heat is generated, and the temperature rises to a predetermined temperature required for ejecting the ink 8.

The pair of electrode layers 4 and 4 deposited on the resistance layer 3 includes a heating portion of the resistance layer 3 (heating element 3a).
It functions as a power supply wiring for supplying power to the power source, and is formed with a thickness of, for example, 0.5 μm to 1.0 μm from a metal material containing aluminum or the like as a main component.

The resistance layer 3 and the electrode layer 4 as described above are formed by a well-known thin film method, and specifically, the above-described electric resistance material and metal material are formed on the lower surface of the base plate 2 by well-known sputtering or CVD. It is formed by sequentially depositing by a method or the like and processing these into a predetermined pattern by conventionally known photolithography and etching.

The protective film 5 covering the resistance layer 3 and the electrode layer 4 protects the resistance layer 3 and the electrode layer 4 from corrosion due to contact with moisture contained in the atmosphere, and at the same time, these layers 3 , 4 are electrically insulated from a support plate 9 described later, and are formed of an inorganic material such as silicon oxide or silicon nitride to a thickness of 0.2 μm to 1.2 μm, for example.

The protective film 5 is formed by adopting conventionally known sputtering or the like and depositing the above-mentioned inorganic material on the surface of the resistance layer 3 or the like. At this time, although film defects such as pinholes are formed on the protective film 5,
Since the protective film 5 is held in non-contact with the ink 8, the moisture contained in the ink 8 or ions such as K ⁺ and OH ⁻ are contained in the resistive layer 3 via the film defect of the protective film 5. And never touches the electrode layer 4.

On the other hand, the above-mentioned head substrate 1 is placed on the support plate 9, and a ceiling plate 6 is formed above the head substrate 1 so that a predetermined gap (for example, a gap of 25 μm to 200 μm) is formed therebetween. Is provided.

The support plate 9 is made of, for example, aluminum or S.
For example, 400 μm to 6 depending on a good heat conductive material such as US
It is formed to a thickness of 00 μm, and the head substrate 1 is mounted on the upper surface of the head substrate 1 via an adhesive (not shown),
The head substrate 1 is bonded and fixed on the support plate 9.

Such a support plate 9 is for mechanically reinforcing the head substrate 1, and even when the thickness of the head substrate 1 is extremely thin, 1 μm to 5 μm, when the ink jet head is used, etc. The head substrate 1 is effectively prevented from being deformed or damaged, and the entire structure of the head substrate 1 is held in a desired structure.

The top plate 6 is arranged so as to face the upper surface of the base plate 2 and has a plurality of ink discharge holes 7 corresponding to the heating elements 3a of the head substrate 1 in a one-to-one relationship. .

The ink discharge holes 7 of the top plate 6 are for discharging ink drops i toward the recording paper during the recording operation of the ink jet head, and the diameter of each ink discharge hole 7 is 10 μm to 100 μm. It is set to the size of
It is fixed to the head substrate 1 so as to be located right above the corresponding heating element 3a.

The top plate 6 is formed by processing a photosensitive epoxy resin, a polyimide resin, molybdenum, alumina ceramics or the like into a predetermined shape, or by combining the above materials, and is made of, for example, molybdenum. , A molybdenum ingot (lump) is formed into a plate shape by a conventionally known metal processing method, and a hole is formed at a predetermined portion of the plate body by a conventionally known laser processing to form an ink discharge hole 7. Then, the obtained top plate 6 is placed on the head substrate 1 via a partition member (not shown), a spacer, or the like, so that the top plate 6 is moved to the head substrate 1.
It is fixed in place on top.

As the ink 8 filled between the head substrate 1 and the top plate 6, for example, an aqueous dye ink or the like is preferably used, and the viscosity thereof is, for example, 0.3 mPa · s or more.
It is adjusted to 3.0 mPa · s (25 ° C).

In the ink 8, the heating element 3 described above is contained.
Bubbles A are generated by the thermal energy of a, and a part of the ink 8 is discharged as an ink droplet i from the ink discharge hole 7 by the pressure when the bubble is generated.

At this time, since the base plate 2 having no pinhole or the like is interposed between the ink 8 and the resistance layer 3 and the electrode layer 4, the ink 8 is against the resistance layer 3 and the electrode layer 4. It will be kept in non-contact.

Since the ink jet head is constructed so that the ink 8 comes into contact with the surface (upper surface) opposite to the lower surface of the base plate 2 provided with the resistance layer 3 and the electrode layer 4 as described above, It contains moisture and K ^+, OH ^-
The base plate 2 can satisfactorily block ions such as ions from coming into contact with the resistance layer 3 or the electrode layer 4, and the electric resistance values of the resistance layer 3 and the electrode layer 4 can be kept substantially constant for a long period of time. It will be possible. Therefore, the reliability of the inkjet head is improved.

Further, in this embodiment, the thickness of the base plate 2 described above is set to a thin thickness of 1 μm to 5 μm, and the heat generated by the resistance layer 3 is transferred to the ink 8 via the base plate 2.
It is possible to maintain high thermal response characteristics of the inkjet head because
It is possible to sufficiently cope with high-speed recording operation.

The ink 8 is supplied to the gap between the head substrate 1 and the top plate 6 from an ink tank (not shown).

Thus, the above-described ink jet head conveys the recording paper along the outer surface of the top plate 6 in the direction orthogonal to the arrangement direction of the ink ejection holes 7, while generating the heating element 3a.
To generate heat selectively based on image data from the outside, and transfer these heat energies to the ink 8 between the top plate 6 and the head substrate 1 via the base plate 2 to generate bubbles A in the ink 8. A predetermined image is recorded by generating the ink 8 and pushing up the ink 8 toward the ink ejection hole 7 side by the pressure of the generated bubble A to eject the ink droplet i from the ink ejection hole 7 toward the recording paper.

The present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

For example, in the above-described embodiment, a driver IC for controlling the heat generation of the heating element 3a may be mounted on the lower surface of the base plate 2.

Further, in the above-described embodiment, the partition member for forming the ink flow path corresponding to each heating element 3a is provided by separating the adjacent heating elements 3a between the head substrate 1 and the top plate 6. In this case, since the partition wall member effectively prevents the pressure generated from the bubbles generated in the ink 8 from being dispersed in the main scanning direction, the pressure from the bubbles can be efficiently applied to the ink. To be able to communicate. Incidentally, such a partition member may be formed integrally with the top plate or the head substrate, or may be formed separately from the top plate or the head substrate.

Further, in the above-described embodiment, the ink discharge hole 7 is provided in the top plate 6 and is arranged directly above the corresponding heating element 3a. However, instead of this, the ink discharge hole 7 is provided. It may be arranged so as to be offset from directly above the heating element 3a, or when the present invention is applied to an edge shooter type inkjet head that ejects ink droplets from the edge of the head substrate 1, the ink ejection holes 7 are provided on the top plate. It is also possible that the nozzle member 6 is not provided on the nozzle 6, and the nozzle member is disposed on one end side of the head substrate 1 in a direction orthogonal to the top plate 6.

[0046]

According to the ink jet head of the present invention, since the ink is in contact with the surface (upper surface) opposite to the lower surface of the base plate provided with the resistance layer and the electrode layer, it is included in the ink. The base plate having no pinholes or the like satisfactorily blocks the moisture and ions such as K ⁺ and OH ^{− from} coming into contact with the resistance layer or the electrode layer, and the electric resistance value of the resistance layer or the electrode layer is It will be possible to keep it substantially constant for a long period of time. Therefore, the reliability of the inkjet head is improved.

Further, according to the ink jet head of the present invention, by setting the thickness of the base plate thinly to 1 μm to 5 μm, the heat generated by the resistance layer can be quickly transferred to the ink through the base plate. The thermal response characteristics of the inkjet head can be maintained high.

Further, according to the ink jet head of the present invention, by mounting and fixing the head substrate on the upper surface of the support plate, even when the thickness of the head substrate is extremely small, when the ink jet head is used. It is possible to effectively prevent the head substrate from being deformed, damaged, and the like, and it is possible to hold the entire structure in a desired structure.

Further, according to the ink jet head of the present invention, if the plate made of silicon oxide formed by thermally oxidizing single crystal silicon is used as the base plate, there are no defects such as pinholes. A good base plate can be obtained relatively easily, and there is an advantage that the reliability and productivity of the inkjet head can be further improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the inkjet head of FIG.

FIG. 3 is a cross-sectional view of a conventional inkjet head.

[Explanation of symbols]

1 ... Head substrate, 2 ... Base plate, 3 ...
・ Resistive layer, 3a ... Heating element, 4 ... Electrode layer, 5 ...
..Protective film, 6 ... Top plate, 7 ... Ink ejection hole, 8
... Ink, 9 ... Support plate, A ... Bubbles, i ...
・ Ink drop

Claims (5)

[Claims] 1. A predetermined gap is formed between an upper surface of the base plate and a head substrate formed by sequentially depositing a resistance layer and a pair of electrode layers on the lower surface of the base plate and covering them with a protective film. In this way, the top plate is arranged face-to-face in this manner, and heat energy generated by energization of the resistance layer is transferred to the ink filled in the gap via the base plate, and the ink is discharged from the ink discharge hole. An inkjet head that forms a print by discharging. 2. The base plate has a thickness of 1 μm to 5 μm.
The inkjet head according to claim 1, wherein the inkjet head is set to m. 3. The inkjet head according to claim 2, wherein the head substrate is placed and fixed on an upper surface of a support plate. 4. The ink jet head according to claim 1, wherein the base plate is formed of silicon oxide obtained by thermally oxidizing single crystal silicon. 5. The inkjet head according to claim 1, wherein the base plate has no pinholes.