JP2003165223A - Ink jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable ink jet head in which electric resistance of a heating resistor or the like, can be kept almost constant over a long term. <P>SOLUTION: In the ink jet head comprising a head substrate 1 where a plurality of heating resistors 3 composed of a CrSiO based resistive material are fixed onto the upper surface of a base plate 2 while being coated with a protective layer 5, and a top plate 6 arranged to form a specified gap between the head substrate 1 and the top plate 6, and ejecting ink 10 filling the gap between the head substrate 1 and the top plate 8 from an ink ejection hole 9 by generating heat from the heating resistor 3, the protective layer 5 of the head substrate 1 comprises a first layer 6 of an inorganic material containing an oxide and/or nitride of Si and a second layer 7 of sintered perhydropolysilazane formed sequentially. <P>COPYRIGHT: (C)2003,JPO

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, as shown in FIG. 3, for example, a plurality of heating resistors are provided on the upper surface of a base plate 12 formed of a plate body made of single crystal silicon whose surface is subjected to thermal oxidation treatment. A top plate 16 having a plurality of ink ejection holes 17 corresponding to the heating resistors 13 in a one-to-one relationship on a head substrate 11 formed by sequentially forming a body 13, electrodes 14 for energization, and a protective layer 15. Is known so that a predetermined gap is formed therebetween, and the gap between the head substrate 11 and the top plate 16 is filled with the ink 18. While conveying along the outer surface 16 of the heat generating resistor 13, the heat generating resistor 13 of the head substrate 11 is selectively and selectively heated by Joule heat based on the image data from the outside. With to generate a bubble A in the middle,
A predetermined image is recorded on the recording paper by pushing up the ink 18 on the heating resistor 13 by the pressure of the generated bubbles A and ejecting a part of the ink 18 toward the recording paper from the ink ejection hole 17. To be done.

The protective layer 15 of the head substrate 11 is
Moisture and ions such as K ⁺ and OH ⁻ contained in the ink 18 come into contact with the heating resistor 13 and the electrode 14 to corrode them, or the dye contained in the ink 18 is solidified. And the like to prevent the same from sticking to the surface of the heating resistor 13, and the material of the protective layer 15 is heat resistance, chemical resistance, sealing property, good thermal conductivity. An inorganic material such as silicon nitride or silicon oxide having excellent cavitation resistance is used.

The protective layer 15 is formed, for example, by
Conventionally known thin film processes such as a CVD (Chemical Vapor Deposition) method and a sputtering method are adopted, and the protective layer 15 is formed by depositing the above-mentioned inorganic material on the base plate 12 to a predetermined thickness.

[0007]

When the protective layer 15 of the head substrate 11 is formed by a thin film process such as a sputtering method or a CVD method, many fine film defects such as pinholes are formed in the protective layer 15. Will be done.

Therefore, water contained in the ink 18 or ions such as K ⁺ and OH ⁻ may come into contact with the heating resistor 13 and the electrode 14 via the film defect of the protective layer 15. In that case, The heating resistor 13 and the like are corroded relatively early by contact with water and ions contained in the ink 18, and the electrical resistance value of the heating resistor 13 and the like fluctuates from the initial value. Was.

The present invention has been devised in view of the above-mentioned drawbacks, and an object thereof is to provide a highly reliable ink jet head capable of keeping an electric resistance value of a heating resistor or the like substantially constant for a long period of time. Especially.

[0010]

In the ink jet head of the present invention, a plurality of heating resistors made of CrSiO-based resistance material are attached to the upper surface of a base plate, and the heating resistors are covered with a protective layer. The heating substrate includes a head substrate and a top plate arranged so as to form a predetermined gap between the head substrate and the head substrate, and the ink filled in the gap between the head substrate and the top plate is used as the heating resistor. An ink jet head which is ejected from an ink ejection hole by heat generation of, wherein the protective layer of the head substrate is made of Si oxide and / or
Alternatively, it is characterized by being formed by sequentially laminating a first layer made of an inorganic material containing a nitride and a second layer made of a sintered body of perhydropolysilazane.

Further, the ink jet head of the present invention is characterized in that the first layer of the protective layer is a thin film formed by a sputtering method or a CVD method.

Further, in the ink jet head of the present invention, the composition ratio of the CrSiO-based resistance material forming the heating resistor is Cr _x SiO _y (0.7≤x≤5.1, 1.8≤y≤).
2.4), and the content ratio of Si contained in each of the heating resistor and the protective layer is set to 10 atom% to 44 atom%.

Furthermore, in the ink jet head of the present invention, the ink has a viscosity (25 ° C.) of 0.3 mPa · s or more.
It is characterized by being adjusted to 3.0 mPa · s.

According to the ink jet head of the present invention,
Since the film defect of the lower first layer of the two layers constituting the protective layer is sealed by the second layer of the sintered body of perhydropolysilazane, the heating resistor is contained in the ink. It is possible to satisfactorily protect against corrosion due to contact with moisture and K ⁺ , OH ^−, etc., and to keep the heat-generating resistor, etc., reliably shut off from the ink by the second layer, so that the electric resistance of the heat-generating resistor, etc. It becomes possible to keep the value substantially constant over a long period of time.

Further, according to the ink jet head of the present invention, the composition ratio of the CrSiO-based resistance material forming the heating resistor of the head substrate is Cr _x SiO _y (0.7 ≦ x ≦ 5.
1, 1.8 ≦ y ≦ 2.4), and the content ratio of Si contained in each of the heating resistor and the protective layer is 10 atomic% to
By setting it to 44 atomic%, it is possible to adjust the linear expansion coefficients of the heating resistor and the protective layer to relatively close values by making the familiarity good between the heating resistor-protective layer and each layer of the protective layer. Therefore, even if the temperature of the inkjet head rises due to the heat generated by the heating resistor during the recording operation, it is possible to effectively prevent a large thermal stress from being generated between the respective layers, and each layer of the protective layer can be prevented. It becomes possible to firmly adhere to the base. This improves the reliability of the inkjet head.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. 1 is a perspective view of an inkjet head according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the inkjet head of FIG. 1. The inkjet head shown in FIG. 1 generally includes a head substrate 1 and a top plate. 8 and ink 10.

The head substrate 1 has a plurality of heat generating resistors 3 attached and arranged on the upper surface of a base plate 2 which has been processed to have a rectangular shape along the longitudinal direction thereof. The electrodes 4 for energization are connected to both ends of each of them, and they are commonly covered with a single protective layer 5.

The base plate 2 is made of single crystal silicon or the like whose surface is insulated, and has a support for supporting a plurality of heating resistors 3, electrodes 4 for energization, a protective layer 5, etc. on its upper surface. It functions as a base material.

When the base plate 2 is made of single crystal silicon, a single crystal silicon ingot (lump) formed by a conventionally known Czochralski method (pulling method) or the like is sliced into a predetermined thickness to form a rectangular outer shape. A conventionally known thermal oxidation method is applied to the surface of the plate obtained by processing, and an oxide film (silicon oxide) is formed, for example, at 0.5 μm to 7.0 μm.
It is manufactured by forming it to a thickness of m.

The heating resistor 3 of the head substrate 1 is
For example, they are arranged linearly in the longitudinal direction (main scanning direction) of the base plate 2 at a density of 600 dpi (dots per inch), and each of them is formed of a CrSiO-based resistance material, so that power is supplied via the electrodes 4 and the like. When electric power is supplied, Joule heat is generated, and the temperature reaches a predetermined temperature required to generate bubbles A in the ink 10.

CrS forming such a heating resistor 3
As the io-based resistance material, the composition ratio is Cr _x SiO 2.
Those represented by _y (0.7 ≦ x ≦ 5.1, 1.8 ≦ y ≦ 2.4) are preferably used, and the content ratio of Si contained in the heating resistor 3 is 10 atoms. % To 44 atomic%.

The CrSiO-based resistance material having such a composition ratio is easy to adjust the calorific value per unit time to a size suitable for ejecting the ink droplet i, and is excellent in pulse resistance. It is possible to obtain the heating resistor 3 suitable for applications such as photographic printing that requires gradation expression.

The pair of electrodes 4, 4 connected to both ends of the heating resistor 3 are made of a metal material such as Al (aluminum), and one of them is at one end side of the heating resistor 3 for all heating resistors. 3 are commonly connected, and the other end is individually connected to each heating resistor 3 at the other end side of the heating resistor 3.

The pair of electrodes 4 function as a power supply line for applying power source power to the heating resistor 3, and the heating resistor 3 is energized by turning on / off a driver IC (not shown). Controlled.

The heating resistor 3 and the pair of electrodes 4 are
A conventionally known thin film method, specifically, the above-described CrSiO-based resistance material and a metal material such as Al are sequentially deposited on the entire upper surface of the base plate 2 by a sputtering method or the like, which is then subjected to conventionally known photolithography and It is formed by adopting an etching technique and processing it into a predetermined pattern. The heating resistor 3 thus obtained has a thickness of, for example, 0.01 μm to 0.2 μm, and the electrode 4 has a thickness of, for example, 0.1 μm to 0.7 μm.

The heating resistor 3 and the pair of electrodes 4 described above are also provided.
The protective layer 5 covering the protective layer 5 is for protecting the heating resistor 3 and the electrode 4 from corrosion due to contact of water and ions (K ⁺ , OH ^−, etc.) contained in the ink 10, and The first layer 6 and the second layer 7 are sequentially laminated from the body 3 side 2
It has a layered structure and the thickness of the entire protective layer is, for example, 0.13.
It is set to μm to 2.15 μm.

Both the first layer 6 and the second layer 7 constituting the protective layer 5 are made of an inorganic material containing Si, and the Si content in each of the layers 6 and 7 is As with the heating resistor 3 described above, 10 atomic% to 4
It is set to 4 atom%.

The Si contained in the first layer 6 and the second layer 7
The same as that of the heating resistor 3 in the content of 10 at% to 44 at%.
Is set so that the familiarity between the heating resistor 3 and the protective layer 5 and between the layers of the protective layer 5 is good, and the linear expansion coefficients of these layers 3, 6 and 7 are made relatively close to each other. This is for setting, so that even if the temperature of the inkjet head rises due to the heat generation of the heat generating resistor 3 accompanying the recording operation, a large thermal stress is effectively prevented from being generated between the layers, and the protective layer 5 Each layer of can be firmly adhered to the base.

The first layer 6 and the second layer 7 constituting the protective layer 5 will be individually described below. Of the two layers forming the protective layer 5, the lower first layer 6 is made of an inorganic material containing Si oxide (silicon oxide) and / or nitride (silicon nitride), for example, 0.1 μm to It is formed to have a thickness of 2.0 μm and is in contact with the heating resistor 3 and the electrode 4.

When the second layer 7 disposed on the first layer 6 is formed through a heat treatment process, the organic solvent in the perhydropolysilazane solution, which will be described later, is changed to the heating resistor 3.
This is to effectively prevent the contact with the electrodes 4 and the like to try to oxidize them, so that the variation of the resistance value of the heating resistor 3 in the manufacturing process of the inkjet head can be suppressed very effectively.

The first layer 6 employs a conventionally known thin film method, specifically, a sputtering method, a CVD method, or the like, and is made of silicon oxide, silicon nitride, or a mixed material thereof (Si—O—N). ) Is deposited to a predetermined thickness, and many fine film defects such as pinholes are formed in the first layer 6 thus obtained.

On the other hand, the second layer 7, which is the upper layer of the protective layer 5, is formed of an inorganic material such as silicon oxide, silicon nitride, or Si—O—N to a thickness of 0.03 μm to 0.15 μm. It is formed of a sintered body obtained by sintering the perhydropolysilazane shown in 1.

[0033]

[Chemical 1]

This perhydropolysilazane is, for example, 1
A ceramic precursor polymer that polymerizes at a temperature of 50 ° C to 220 ° C, and is a perhydropolysilazane solution (viscosity: 0.5 cps to 1.0 cps) prepared by dissolving perhydropolysilazane in an organic solvent such as xylene or cyclohexene.
cps) is thinly applied to the upper surface of the first layer 6 by a conventionally known thick film method such as a dipping method, a spin coating method, or a bar coater method, and this is first applied in a temperature range of 150 ° C. to 220 ° C. for about 1 hour, then About 1 to 400 ℃ ~ 500 ℃
The second layer 7 is formed by heat-treating for a time and ceramming the perhydropolysilazane.

At this time, if the heat treatment of perhydropolysilazane is carried out in a nitrogen atmosphere, the ceramic sintered body containing silicon nitride as a main component is produced. If it is carried out in a high humidity atmosphere (humidity of 50% or more), silicon oxide is mainly contained. A ceramic sintered body as a component will be formed.

Since the second layer 7 formed by the thick film process as described above has almost no film defects such as pinholes, the film defects of the first layer 6 are well covered by the second layer 7. be able to. Therefore, the heating resistor 3 and the electrode 4 are well sealed with the protective layer 5, and the heating resistor 3 and the electrode 4 are sealed with the ink 1.
It is possible to satisfactorily protect from corrosion due to contact with water, ions, etc., contained in zero.

The top plate 8 is arranged on the above-mentioned head substrate 1 so as to form a predetermined gap therebetween.

The top plate 8 has a plurality of ink ejection holes 9 corresponding to the heating resistors 3 in a one-to-one correspondence, and these ink ejection holes 9 are directly above the corresponding heating resistors 3. It is positioned so that it is positioned between the inner surface thereof and the upper surface of the head substrate (surface of the protective layer 5), for example, 5 μm to 50 μm.
Gaps are formed.

The ink ejection holes 9 of the top plate 8 are for ejecting the ink droplet i toward the recording paper due to the generation of the bubbles A during the recording operation of the ink jet head. Has a diameter of, for example, 10 μm to 100 μm
And are arranged in the main scanning direction at the same density as the heating resistors 3.

As the material of the top plate 8, a metal material such as molybdenum, a ceramic material such as alumina ceramics, or a synthetic resin material such as epoxy resin is used. For example, in the case of molybdenum, an ingot of molybdenum (lump) is used. ) Is formed into a plate shape by a conventionally known metal working method, and a plurality of ink discharge holes 9 are formed at predetermined positions of the plate body by a conventionally known etching technique or the like. The top plate 8 is fixed to a predetermined position on the head substrate 1 by placing the top plate 8 on the head substrate 1 via a spacer (not shown) or the like.

Ink 10 is filled in the gap between the head substrate 1 and the top plate 8 to form a predetermined ink flow path between the head substrate 1 and the top plate 8. Such an ink 10
A water-based dye ink or the like is preferably used as the ink having a viscosity of, for example, 0.3 mPa · s to 3.0 mPa · s (25
℃) is adjusted.

The ink 10 is supplied from an ink tank (not shown) to the ink flow path between the head substrate 1 and the top plate 8, and the heat energy from the heating resistor 3 causes the ink 10 to flow into the ink 10. When bubble A is generated,
A part of the ink 10 is pushed up to the ink ejection hole 9 side by the pressure caused by the generation of the bubble A, and a part of the ink 10 is ejected from the ink ejection hole 9 to the outside as an ink droplet i.

Then, the ink droplet i ejected from the ink ejection hole 9 is attached to the surface of the recording paper conveyed along the outer surface of the top plate 8, whereby a predetermined image is formed on the recording paper. Becomes

According to the ink jet head of this embodiment as described above, the heating resistor 3 and the electrode 4 of the head substrate 1 are provided.
Is well sealed by the protective layer 5, so that the heat generating resistor 3 and the electrode 4 contain water and K contained in the ink 10.
^+, OH ^- contact by can be better protected from corrosion, such as, the heat generating resistor 3 and the electrode 4 by continuing to reliably cut off from the ink 10, to maintain these electrical resistance values substantially constant for a long time Is possible.

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

For example, in the above embodiment, the electrode 4
However, instead of this, the electrode 4 may be formed of a conductive material containing Si such as Al—Si and Al—Si—Cu. In this case, the electrode 4 is protected. There is an advantage that the adhesion between the layers 5 can be improved.

In the above-described embodiment, a partition member may be interposed between the head substrate 1 and the top plate 8 to separate the adjacent heating resistors. In that case, from the bubbles A generated in the ink 10. Since it is possible to effectively prevent the pressure of (1) from being dispersed in the main scanning direction by the partition member, most of the pressure generated due to the formation of the bubble A can be contributed to the ejection of the ink droplet i, and the ink droplet can be prevented. There is also an advantage that discharge can be performed efficiently.

Further, in the above embodiment, the heating resistor 3
Driver board for controlling the heat generation of the head substrate 1
It goes without saying that it may be mounted on top.

[0049]

According to the ink jet head of the present invention, of the two layers constituting the protective layer, the film defect of the first layer which is the lower layer is sealed by the second layer which is the sintered body of perhydropolysilazane. As a result, the heat-generating resistor can be well protected from corrosion due to contact with water contained in the ink, K ⁺ , OH ^−, etc., and the heat-generating resistor can be more reliably formed in the second layer than the ink. By continuing to cut off, it becomes possible to keep the electric resistance value of the heating resistor or the like substantially constant for a long period of time.

Further, according to the ink jet head of the present invention, the composition ratio of the CrSiO-based resistance material forming the heating resistor of the head substrate is Cr _x SiO _y (0.7 ≦ x ≦ 5.
1, 1.8 ≦ y ≦ 2.4), and the content ratio of Si contained in each of the heating resistor and the protective layer is 10 at% to 44 at%.
By setting to atomic%, the heating resistor-protective layer,
Further, since the familiarity between the respective layers of the protective layer can be made good and the linear expansion coefficient of the heating resistor and the respective layers of the protective layer can be adjusted to relatively close values, the inkjet head is generated by the heat generated by the heating resistor during the recording operation. Even if the temperature rises, it is possible to effectively prevent generation of large thermal stress between these layers, and it becomes possible to firmly adhere each layer of the protective layer to the underlayer. . This allows
The reliability of the inkjet head is 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 ... Base plate, 3 ... Heating resistor, 4 ...
・ Electrodes for energization, 5 ... Protective layer, 6 ... First layer, 7
... second layer, 8 ... top plate, 9 ... ink discharge hole,
10 ... Ink

Claims (4)

[Claims] 1. A head substrate comprising a plurality of heating resistors made of a CrSiO-based resistance material deposited on the upper surface of a base plate, and the heating resistors being covered with a protective layer.
A head plate disposed so as to form a predetermined gap between the head substrate and the head substrate, and ink filled in the gap between the head substrate and the top plate is formed by heat generated by the heating resistor. In an inkjet head for discharging from a discharge hole, the protective layer of the head substrate is a second layer made of a first layer made of an inorganic material containing Si oxide and / or a nitride and a sintered body of perhydropolysilazane. An inkjet head, which is formed by sequentially laminating layers. 2. The ink jet head according to claim 1, wherein the first layer of the protective layer is a thin film formed by a sputtering method or a CVD method. 3. A CrSiO-based resistor forming the heating resistor.
The composition ratio of the anti-material is Cr _xSiO_y(0.7 ≦ x ≦ 5.
1, 1.8 ≦ y ≦ 2.4), and the heating resistor
And the content rate of Si contained in each layer of the protective layer is 1
It is characterized by being set to 0 atom% to 44 atom%.
The inkjet printer according to claim 1 or 2,
Dead. 4. The viscosity (25 ° C.) of the ink is 0.3 mP.
The inkjet head according to any one of claims 1 to 3, wherein the inkjet head is adjusted to be from a · s to 3.0 mPa · s.