JPH11157067A - Recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a vibration plate when an anode- connection is made between a vibration plate substrate of a recording head and an electrode substrate. SOLUTION: In the recording head wherein a vibration plate is deformed by electrostatic forces acting between an electrode and the vibration plate to generate pressures, whereby a recording material is delivered onto a recording medium, when an angle formed between a side surface of a step provided in an electrode substrate to keep the interval between the vibration plate and the electrode and a surface provided on the electrode is very acute, in order to prevent the deformation of the vibration plate due to a large electrostatic force generated at the step when an anode-connection is made, the angle is made equal to 14 degrees or more, or the potential of the electrode made equal to that of the vibration plate substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head, and to high-quality printing such as color printing.
The present invention relates to a recording head that can be used as a structure of a micropump, a pressure sensor, and the like.

[0002]

2. Description of the Related Art In an on-demand type ink jet head, a part of a wall of a liquid chamber is formed as a thin diaphragm, and a piezoelectric element is provided here as an electromechanical conversion element. Deforming the diaphragm by deformation, changing the pressure of the liquid chamber and discharging ink (piezo-on-demand type), providing a heating element inside the liquid chamber, generating bubbles by heating the heating element by energizing, A method of discharging ink by the pressure of bubbles (bubble jet method) is widely and generally known. These methods include:
There are issues such as miniaturization, high density, high speed, high image quality, etc.
As a solution to these problems, an electrostatic inkjet has been proposed. In the electrostatic inkjet, a thin vibration plate provided in a liquid chamber is deformed by static electricity, and the pressure in the liquid chamber is increased by the deformation to discharge ink. For example, in JP-A-5-50601, a nozzle, a discharge chamber, an ink cavity, and a vibration plate are formed on a middle substrate made of silicon by etching, and the upper substrate having an ink supply port and the vibration plate are opposed to each other. There is disclosed an apparatus in which a head is formed by integrating a lower substrate provided with electrodes and an electric field is applied between the diaphragm and the electrodes to eject ink based on the above-described principle. Further, for example, Japanese Patent Laid-Open No. 6-71882
Japanese Patent Application Laid-Open Publication No. H11-163,087 discloses a technique in which the distance between the diaphragm and the electrode is limited to 0.05 μm to 2.0 μm for the purpose of low voltage driving.

[0003]

In an electrostatic head (actuator) having such a configuration, a diaphragm substrate and an electrode substrate are generally bonded to each other by an anodic bonding method. At the time of anodic bonding, + on the diaphragm substrate (Si) side,
A negative electric potential is applied to the electrode substrate (Pyrex glass) side, and an electrostatic force acting between the two substrates is generated due to the bias of the charge caused by the movement of the alkali ions in the glass substrate, and this is one of the driving forces for bonding. And At this time, if the shape of the step portion provided for keeping the distance between the two substrates constant is too acute, the electrostatic force acting on that portion becomes extremely large, and the diaphragm substrate is deformed, A situation of joining occurs. Therefore, a first object of the present invention is to prevent this deformation occurring at the time of joining, and a second object is to positively increase a property that an electrostatic force acting on the step becomes extremely large depending on a stepped shape. It is an object of the present invention to provide a configuration in which the displacement of the diaphragm can be increased at a relatively low voltage. Still another object of the present invention is to provide a configuration for preventing the vibration plate and the insulating film on the electrode from sticking together when they come into contact with each other. Hereinafter, the problem will be specifically described for each claim.

It is an object of the present invention to prevent deformation of the diaphragm substrate during anodic bonding between the diaphragm substrate and the electrode substrate, maintain a predetermined distance between the electrode and the diaphragm, and maintain uniformity of ink ejection. And to improve the reproducibility of the gap.

A second object of the present invention is to prevent the diaphragm substrate from being deformed at the time of anodic bonding between the diaphragm substrate and the electrode substrate even when the angle of the step is extremely acute, and to prevent the electrode and the diaphragm from being deformed. Is maintained at a predetermined interval, and the uniformity of ink ejection and the reproducibility of the gap are improved.

The object of the invention of claims 3 and 4 is that of claim 2
Another object of the present invention is to reduce the complexity of electric wiring for making the diaphragm substrate and the electrode have the same potential during anodic bonding.

A fifth object of the present invention is to positively utilize the property that the electrostatic force acting on the side surface of the step and the surface on which the electrode is provided is extremely acute when the angle between the side surface and the electrode is also extremely sharp. However, by providing a configuration capable of increasing the displacement of the diaphragm at a relatively low voltage, and by preventing the deformation of the diaphragm substrate during anodic bonding, it is possible to maintain a predetermined distance between the electrodes,
The purpose is to improve the uniformity of ink ejection and the reproducibility of the gap.

An object of the present invention is to prevent the vibration plate and the insulating film on the electrode from sticking to each other when they come into contact with each other and to prevent deformation of the vibration plate substrate at the time of anodic bonding. An object of the present invention is to maintain a predetermined interval and improve uniformity of ink ejection and reproducibility of a gap.

Another object of the present invention is to prevent the vibration plate and the insulating film on the electrode from sticking to each other when they come into contact with each other.

[0010]

According to a first aspect of the present invention, there is provided a discharge port for discharging a recording medium and a pressurized liquid chamber for applying a discharge pressure to the recording medium, and a part of the pressurized liquid chamber is constituted. A diaphragm substrate on which a vibrating plate is formed, and an electrode substrate having a first electrode formed at a position facing the diaphragm, deforming the diaphragm by electrostatic force acting between the electrodes and the diaphragm, In a recording head that discharges a recording medium to a recording medium by the generated pressure, a side surface of a step provided on the electrode substrate and a surface on which the electrode is provided are formed in order to keep a constant distance between the diaphragm and the electrode. The recording head has an angle of 14 ° or more.

According to a second aspect of the present invention, in the recording head according to the first aspect, a second electrode is provided on a side surface of the step.

According to a third aspect of the present invention, in the recording head according to the second aspect, the second electrode is in electrical contact with the diaphragm substrate.

According to a third aspect of the present invention, in the recording head according to the second aspect, before the diaphragm substrate and the electrode substrate are anodically bonded to each other, the first electrode and the second electrode are connected by a lead electrode portion. The recording head is connected, and becomes electrically disconnected after anodic bonding.

According to a fifth aspect of the present invention, there is provided a diaphragm having a discharge port for discharging a recording medium and a pressurized liquid chamber for applying a discharge pressure to the recording medium, the diaphragm constituting a part of the pressurized liquid chamber. A diaphragm substrate, and an electrode substrate having a first electrode formed at a position facing the diaphragm, deforming the diaphragm by electrostatic force acting between the electrodes and the diaphragm, and generating a recording medium by the generated pressure. In a recording head that discharges the first electrode to the recording medium, the angle between the side surface of the step and the surface on which the electrode is formed is 15 ° or less, and the first electrode extends from the upper surface of the electrode substrate to the side surface of the step. The recording head is provided with an insulating film on the electrode or on the surface facing the diaphragm.

A sixth aspect of the present invention is the recording head according to the fifth aspect, wherein the total surface energy of the insulating film is 50 mJ / m ² or less.

According to a seventh aspect of the present invention, in the recording head according to the fifth or sixth aspect, the insulating film is a hard carbon film.

[0017]

FIG. 1 is a sectional view showing an embodiment of a recording head according to the present invention. In FIG. 1, a first electrode 2 is arranged on a lower substrate (electrode substrate) 1 of the recording head so as to face a diaphragm 5 of a diaphragm substrate 4, and the lower plate (electrode substrate) is provided with a diaphragm 5 on the lower substrate. A diaphragm substrate 4 provided with a concave portion serving as a pressurized liquid chamber 6 is joined, and an upper substrate 7 on which a discharge port 8 and a flow path 9 are formed is further joined. In this configuration, the recording head applies an electric field between the vibration plate 5 and the electrode 2 to deform the vibration plate by electrostatic force, and increases the pressure of the liquid chamber by a restoring force when the deformation or the deformation is restored. To discharge ink.

The lower substrate 1 and the diaphragm substrate 4 are joined by an anodic bonding method. Diaphragm substrate (Si) during anodic bonding
A positive potential is applied to the side and a negative potential is applied to the electrode substrate (Pyrex glass) side. An electrostatic force acting between the two substrates is generated due to the bias of the charge caused by the movement of the alkali ions in the glass substrate. This is one of the driving forces for joining the two substrates. At the time of this anodic bonding, if the shape of the step portion provided to keep both substrates constant is too acute, the electrostatic force acting on that portion becomes extremely large, and the diaphragm substrate is deformed (electrode (In the state of being pulled to the side). The present invention has been made in order to solve the above-described problems, and relates to the relationship between the deformation of the diaphragm 5 and the shape of the step portion, particularly the angle of the side surface, which occur during the above-described process during anodic bonding. It was made based on the results of a detailed investigation. Table 1 shows the relationship between the angle a and the amount of deformation of the diaphragm.

[0019]

[Table 1]

Next, the first embodiment of the present invention will be described with reference to FIG. 2 which shows a sectional view taken along the line XX 'in FIG.
The above table shows the case where the predetermined gap is 0.5 μm. In this case, the allowable vertical deformation is 6% or less of the gap. As is clear from the table, the angle a
Becomes larger, the amount of deformation in the vertical direction can be remarkably reduced. Further, in consideration of a margin in manufacturing, it is preferably 18 ° or more. In view of this, the invention of claim 1 provides a step 10 provided to keep the distance between the diaphragm 5 and the first electrode 2 constant.
Angle a between the side surface 11 and the surface on which the first electrode is provided
Is set to 14 ° or more, more preferably 18 ° or more, whereby the deformation of the diaphragm is reduced to a level that does not cause a practical problem.

Here, the materials of the substrates 1, 4, 7 are as follows:
Glass (especially Pyrex # 7740, # 707
0, # 7059, etc.) or crystalline silicon is desirable in terms of microfabrication, but is not particularly limited thereto. However, as for the diaphragm substrate 4, a material having a low resistance is desirable in order to apply a voltage, and in this sense, low-resistance crystalline silicon is preferable.

The step 10 provided to keep the gap between the diaphragm 5 and the first electrode 2 constant and the method of forming the electrodes will be described. First, the step 10 is formed on the surface of the lower substrate 1.
A resist pattern or an etching mask pattern having an opening only in a portion corresponding to the above is formed and etched. At this time, when the adhesion between the resist or the mask material and the substrate is weak, or when the resist or the mask material is eroded by the substrate etchant, the side surface of the step 10 is not vertical.

Next, a method for forming an electrode and a protective layer will be described. As an electrode material, a thin film of a metal material was mainly deposited on the lower substrate 1 by a vapor phase synthesis method such as a sputtering method, an evaporation method, an EB evaporation method, and the like, and an electrode was formed by photolithography and etching. More specifically, Ti /
Film thicknesses of 0.05 to 0.5 microns were formed using Pt, Ni, Cu, W, Ta, NiCr, Crt and the like. In addition to metals, transparent conductive materials (ITO, ZnO, SnO) and the like can be used, but these materials are not particularly limited. Further, as the protective layer, SiO ₂ , SiNx, SiON
x, etc. are used, and sputtering, vapor deposition,
It was deposited by a vapor phase synthesis method such as an EB evaporation method and the like, and a protective layer was formed by photolithography and etching.

Further, a method of manufacturing a diaphragm substrate will be described. Using a substrate made of Si (100) or (110) with about 2 μm of SiO ₂ on the surface, etching the SiO ₂ at the position corresponding to the diaphragm on top of this, opening an opening, and leaving only Si in that part With KOH aqueous solution (several% to about 4
(5%) as an etchant, anisotropic etching was performed at 80 ° C. to the thickness of the diaphragm. In addition, hydrazine, TMHA, or the like can be used as a wet anisotropic etchant. Further, the controllability of the diaphragm thickness can be improved by using selective etching using a highly doped layer of Si or using an etch stop of the PN junction substrate by an electrochemical method.

The invention of claim 2 is based on FIG.
And only the diaphragm substrate 4 are shown. In practice, the upper substrate 7 is sequentially bonded thereon to form a recording head.) As shown in FIG. 7, the upper substrate 7 is provided on the lower substrate 1 in order to keep the distance between the diaphragm substrate 4 and the first electrode 2 constant. The second electrode 12 is provided on the side surface 11 of the step 10. At the time of anodic bonding, the second
The electrode 12, the first electrode 2, and the diaphragm substrate 4 are set to the same potential by external wiring (each is independently connected to a probe terminal to a lead pad portion, and the wiring of the terminal is connected to make the same potential). By doing so, the electrostatic force acting on the side surface 11 of the step 10 and the diaphragm substrate 4 at the time of joining can be completely eliminated, so that the reproducibility and uniformity of the gap can be significantly improved. Another advantage of this configuration is that the effect hardly depends on the shape of the step (the angle a between the side surface 11 of the step 10 and the surface on which the first electrode 2 is provided). In FIG. 3, there is no insulating film 3 on the second electrode 12, but the presence or absence of the insulating film has no bearing on the effect of the present invention.

FIG. 4 is a view for explaining the third aspect of the present invention. In FIG. 4, only the lower substrate 1 and the diaphragm substrate 4 are shown. Are sequentially joined to form a recording head. In order to keep the distance between the diaphragm substrate 4 and the first electrode 2 constant, a second electrode 12 is provided on a side surface 11 of a step 10 provided on the lower substrate 1, and as shown, the second electrode 12 is It is patterned so as to be in electrical contact with diaphragm substrate 4. As a material of the lower substrate 1, glass (particularly, Pyrex # 7740, # 7
070, # 7059, etc.), but the invention is not limited thereto. With such a configuration of the recording head, the second electrode 12 and the diaphragm substrate 4 can be set to the same potential without using an external connection at the time of anodic bonding. That is, normally, as in the embodiment of the invention of claim 2 described with reference to FIG. 3, the probe terminal is connected to the extraction pad portion and the wiring of the terminal is connected to have the same potential, but the probe terminal However, according to the present invention, the second electrode 12 and the diaphragm substrate are automatically electrically connected and have the same potential. Become. Moreover, the same effects and advantages as those of the second aspect can be obtained.

Next, the patterning of the second electrode will be described. First, a thin film mainly made of a metal material as an electrode material was deposited on the lower substrate 1 by a vapor phase synthesis method such as a sputtering method, an evaporation method, an EB evaporation method, or the like. More specifically, Ti / Pt, Ni, Cu, W, Ta, NiCr, C
A film thickness of 0.05 to 0.5 μm was formed using rt or the like. In addition to metals, transparent conductive materials (ITO, ZnO, SnO) and the like can be used, but these materials are not particularly limited. Next, a resist is applied to the first electrode 2 and the second electrode 2.
Electrode 12 patterns were simultaneously exposed and etched to form electrodes. By designing the second electrode 12 pattern to be in contact with the diaphragm substrate 4, the second electrode can be manufactured without increasing the number of photolithography. Further, as the protective layer, an inorganic insulating film such as SiO ₂ , SiNx, SiONx, etc. is used. Layers.

FIG. 5 is a diagram showing the structure of the invention according to claim 4 (FIG. 5 shows only the lower substrate 1 and the diaphragm substrate 4).
Actually, the upper substrate 7 is sequentially bonded thereon to form a recording head.) According to a third aspect of the present invention, in the recording head, the first electrode and the second electrode are connected to the leading electrode portion before the diaphragm substrate and the lower substrate are anodically bonded.
3, after the anodic bonding, as shown as a cut portion in FIG. 5, it is cut off by, for example, a laser trimmer, etching or the like to be in an electrically disconnected state. As shown in FIG. 5, the second electrode 12 is patterned so as to be in electrode contact with the diaphragm substrate 4, and furthermore, the first electrode 2 and the second electrode 12 are connected by the extraction electrode portion 13. Therefore, the diaphragm substrate 4, the first electrode 2, and the second electrode 12 automatically have the same potential. According to this configuration, the bonding can be performed without using an external connection as in the second and third aspects of the invention. Therefore, there is no connection failure accompanying the probe terminal, and the connection jig is simplified. In addition, the reproducibility and uniformity of the gap can be remarkably improved, and this effect is obtained by the shape of the step (the same as that shown in FIG.
Hardly depends on the angle a) between the first electrode 2 and the surface on which the first electrode 2 is provided.

FIG. 6 is a view for explaining the invention of claim 5, showing a cross section of a recording head. The most significant feature of the present invention is that, even if the driving voltage is the same, a relatively large vibration is generated even when the driving voltage is the same, by positively utilizing the fact that the angle a formed between the side surface of the step and the surface on which the electrode is provided is extremely acute. That is, the displacement of the plate can be obtained. Describing the configuration, the angle a between the side surface 11 of the step 10 and the surface on which the electrodes are formed is 15 ° or less, and the first electrode 2 is provided across the side surface 11 of the step. Since the electrostatic force increases in inverse proportion to the square of the distance between the opposing electrodes, a relatively low voltage and large electrostatic force sequentially acts on the center from the end of the side surface 11 where the distance between the diaphragm and the electrode is shortest. To go. That is, when the diaphragm 5 comes into close contact with the electrode surface, the gap at the next position is substantially reduced, so that the deformation gradually progresses to the central portion. Further, since the diaphragm 5 is in close contact with the electrode surface, the insulating film 3 is provided on the electrode or on the surface facing the diaphragm to prevent short circuit. In the other configuration, a displacement of 0.1 μm is generated at a gap of 0.5 μm and a normal voltage of 70 V. In contrast, in the present invention, a displacement of 0.1 μm is generated at a gap of 0.5 μm and a voltage of 40 V. Further, another advantage of the present invention is that the side surface of the step 10 when the diaphragm substrate 4 and the electrode substrate (lower substrate) 1 are joined by the same method as described in relation to the second to fourth aspects of the present invention. Electrostatic force between the diaphragm 11 and the diaphragm substrate 4 can be eliminated,
Therefore, the reproducibility and uniformity of the gap can be significantly improved.

As a problem peculiar to the electrostatic ink jet described in connection with the invention of claim 5, there is a problem such as adhesion between the electrode and the diaphragm due to moisture or OH groups adsorbed on the surface of the insulating film. Accordingly, as a result of intensive research on the problem of the adhesion between the diaphragm and the insulating film, it was found that the surface energy of the film was the main factor that governed the adhesion. Table 2 below shows the relationship between the attachment of the diaphragm and the total surface energy of the insulating film.

[0031]

[Table 2]

As is clear from the table, when the total surface energy of the insulating film is about 50 mJ / m ² or less, the probability of the diaphragm sticking is remarkably reduced, and no practical problem is caused. Further, it is preferably 45 mJ / m ² or less. As a material for the insulating film, an organic material such as a fluororesin, polystyrene, an epoxy-based resin, or parylene is actually suitable, but is not particularly limited thereto.

As the insulating film of the recording head, in addition to the problem of sticking to the vibration plate, it is required that the dielectric breakdown voltage is high, the chemical stability is high in view of the process resistance, and the hardness is high. Required. Therefore, as a result of earnest studies on an insulating film satisfying all of the above requirements, it has been found that a hard carbon film formed by a gas phase method is suitable.

Here, the manufacturing method and characteristics of the hard carbon film of the recording head of the present invention will be described. In order to form a hard carbon film, an organic compound gas, particularly, a hydrocarbon gas is used. The phase state in these source gases does not necessarily need to be a gas at normal temperature and normal pressure,
Any liquid or solid can be used as long as it can be vaporized through melting, evaporation, sublimation, etc. by heating or decompression. Examples of the carbon source include paraffinic hydrocarbons such as C ₂ H ₆ , C ₃ H ₈ , and C ₄ H ₁₀ , acetylene-based hydrocarbons such as C ₂ H ₄ , and diolefin-based hydrocarbons. Gases containing all hydrocarbons such as aromatic hydrocarbons can be used. Further, other than hydrocarbons, for example, alcohols, ketones, ethers, esters, CO, CO
Any compound containing at least a carbon atom such as ₂ can be used. In addition, a gas containing hydrogen is used to selectively remove the carbon of the SP ₂ bond generated simultaneously with the carbon of the SP ₃ bond in the film. Specifically, it is H ₂ , H ₂ O or the like.

As a method for forming a hard carbon film from a raw material gas, the active species for film formation are DC, low frequency, high frequency, or
A method formed through a plasma state generated by a plasma method using a microwave or the like is preferable. However, a method using a magnetic field effect in combination for the purpose of increasing the area, improving the uniformity, and lowering the film forming temperature ( ECR plasma CVD is more preferred. In addition, it may be formed through an ion state generated by ion plating, cluster ion beam, or the like, or may be formed from neutral particles generated by ECR sputtering, sputtering, or the like. It may be formed by a combination method. An example of the film forming conditions of the hard carbon film manufactured in this manner is generally as follows in the case of plasma CVD. The mechanical properties of the obtained film are as described above.

RF power: 0.1 to 50 W / cm ² Pressure: 10 ^{-3 to} 10 Pa Deposition temperature: room temperature to 900 ° C.

The obtained hard carbon film was a film material containing carbon atoms as a main constituent element and containing at least one of amorphous and microcrystalline (diamond-like carbon film, i-C
Film, also called amorphous diamond film).
One feature of the hard carbon film is as follows. It is excellent in that it can be synthesized at relatively low temperature by vapor phase growth, has low surface energy of the film, has water repellency, and has high dielectric strength (5 ×
10 ⁶ v / cm or more) and excellent chemical stability.
Since the hardness is high and the friction coefficient is small (0.3 to 0.1), the wear resistance is excellent. Young's modulus is 3-7 (10 ⁴
Kg / mm ² ). Therefore, it is a suitable material for achieving the purpose of the insulating film.

The thickness of the hard carbon film suitable for the above purpose was 50 to 500 nm. If it is 50 nm or less, although depending on the surface properties of the substrate, the withstand voltage of the film is reduced, and the stability during long-term use is significantly reduced. In addition, 500n
At m or more, peeling of the film frequently occurred. For these reasons, the range of the film thickness is more preferably 100 to 350 nm.

Furthermore, as a result of intensive studies to reduce the surface energy of the film, it is particularly effective to replace hydrogen atoms in the film with F atoms or to introduce N atoms into the film as constituent elements of the skeleton. Was found to be relevant. In order to introduce F atoms, CH ₃ F, C
A hydrocarbon gas containing an F element such as H ₂ F ₂ or CHF ₃ may be used. In order to introduce N atoms, a gas containing an N element, such as N ₂ , NH ₃ , N ₂ H ₂ , may be used as a source gas. The following table shows the change in total surface energy with respect to pure water when each atom is introduced into the film.

[0040]

[Table 3]

FIG. 7 is a view for explaining the invention of claim 7, and FIG. 7 (A) shows a case where a hard carbon film 14 is provided over the entire surface of the first electrode 2. FIG. In a conventional device, an inorganic oxide such as SiO ₂ or Si ₃ N ₄ has been used as a protective film for an electrode. Moisture in the air and -OH are adsorbed on the surface of the electrode and the protective film, and when the electrode and the protective film come into contact, a hydrogen bond-like chemical bond occurs,
Even if the voltage is reduced to zero, the two remain joined. This phenomenon is particularly remarkable when the electrode is a transparent electrode. On the other hand, the hard carbon film had a very small amount of adsorption of water and -OH groups, and did not have the above-mentioned problems. Furthermore, it goes without saying that the hard carbon film has a high specific resistance and a high withstand voltage, and functions as an electrical insulating layer. FIG. 7B shows a configuration in which the hard carbon film 14 is provided only on a part of the electrode 2.

[0042]

According to the first aspect of the present invention, there is provided a diaphragm having a discharge port for discharging a recording medium and a pressurized liquid chamber for applying discharge pressure to the recording medium, and constituting a part of the pressurized liquid chamber. And an electrode substrate having a first electrode formed at a position facing the diaphragm. The diaphragm is deformed by electrostatic force acting between the electrode and the diaphragm, and the In a recording head that discharges a recording medium onto a recording medium by pressure, an angle formed between a side surface of a step provided to maintain a constant distance between the diaphragm and the electrode and a surface on which the electrode is formed is 14 ° or more. With this configuration, the reproducibility and uniformity of the gap can be significantly improved.

According to the second aspect of the present invention, the second electrode is provided on the side surface of the step provided to keep the distance between the diaphragm and the electrode constant, so that the gap reproducibility and uniformity can be improved. It can be significantly improved. This effect hardly depends on the shape of the step (the angle a between the side surface 11 of the step 10 and the surface provided on the first electrode 2).

According to a third aspect of the present invention, since the second electrode is configured to be in electrical contact with the diaphragm, there is no connection failure associated with the probe terminal, and the connection jig is also used. It's easy. Also, gap reproducibility,
The uniformity can be significantly improved, and this effect hardly depends on the shape of the step (the angle a between the side surface 11 of the step 10 and the surface on which the first electrode 2 is formed).

According to a fourth aspect of the present invention, in the third aspect, before the diaphragm substrate and the electrode substrate are anodically bonded, the first electrode and the second electrode are connected by a lead electrode portion, By making the state electrically disconnected after the anodic bonding, there is no connection failure accompanying the probe terminal, and the connection jig is simplified. In addition, the reproducibility and uniformity of the gap can be significantly improved, and this effect hardly depends on the shape of the step (the angle a between the side surface 11 of the step 10 and the surface on which the first electrode 2 is formed).

According to a fifth aspect of the present invention, the angle between the side surface of the step and the surface on which the electrode is formed is an acute angle of 15 ° or less, and the first electrode is provided across the side surface of the step. And, because the insulating film is provided on the electrode or on the opposing surface of the diaphragm, even if the same driving voltage,
A relatively large displacement of the diaphragm is obtained. Step 1 when joining
The electrostatic force acting on the side surface 11 of the zero and the diaphragm substrate 4 can be completely eliminated, so that the reproducibility and uniformity of the gap can be significantly improved.

Effect corresponding to claim 6: Since the total surface energy of the insulating film in claim 4 is 50 mJ / m ² or less, the problem of sticking to the diaphragm is solved.

According to the seventh aspect, the problem of sticking to the diaphragm is solved by the fact that the insulating film is a hard carbon film. High breakdown voltage and no element breakdown. Due to high chemical stability and high hardness, process resistance is improved and yield is increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a recording head according to the present invention.

FIG. 2 is a view taken along the line XX ′ in FIG. 1;
FIG. 3 is a sectional view of a recording head for describing the invention of FIG.

FIG. 3 is a sectional view of a principal part similar to FIG. 2, for describing the invention of claim 2;

FIG. 4 is a view similar to FIG. 2 for explaining the invention of claim 3;

FIG. 5 is a plan view of an electrode substrate (first substrate) for describing the invention of claim 4;

FIG. 6 is a view similar to FIG. 2 for describing the invention of claim 5;

7 is a view similar to FIG. 2 for explaining the invention of claim 7, wherein FIG. 7 (A) shows an example in which a hard carbon film is coated on the entire surface of the electrode, and FIG. 7 (B) Indicates an example in which a part of the electrode is covered.

[Explanation of symbols]

1 ... electrode substrate (lower substrate), 2 ... first electrode, 3 ... insulating film,
DESCRIPTION OF SYMBOLS 4 ... diaphragm board, 5 ... diaphragm, 6 ... pressurized liquid chamber, 7 ... upper board, 8 ... discharge port, 9 ... flow path, 10 ... step, 11 ... side surface (of step), 12 ... second electrode , 13 ... Extraction electrode part, 1
4: Hard carbon film.

Claims (7)

[Claims] 1. A diaphragm substrate having a discharge port for discharging a recording body, a pressurized liquid chamber for applying discharge pressure to the recording body, and a diaphragm formed as a part of the pressurized liquid chamber, An electrode substrate having a first electrode formed at a position facing the diaphragm, deforming the diaphragm by electrostatic force acting between the electrode and the diaphragm, and causing the recording body to be a recording medium by the generated pressure. In a recording head for discharging, an angle formed between a side surface of a step provided on the electrode substrate and a surface on which the electrode is provided is 14 ° or more in order to keep a constant distance between the diaphragm and the electrode. Recording head. 2. The recording head according to claim 1, wherein a second electrode is provided on a side surface of the step. 3. The recording head according to claim 2, wherein said second electrode is in electrical contact with said diaphragm substrate. 4. The recording head according to claim 3, wherein the first electrode and the second electrode are connected by an extraction electrode portion before the diaphragm substrate and the electrode substrate are anodically bonded; A recording head which is electrically disconnected after anodic bonding. 5. A diaphragm substrate having a discharge port for discharging a recording medium, a pressurized liquid chamber for applying discharge pressure to the recording medium, and a diaphragm formed as a part of the pressurized liquid chamber, An electrode substrate having a first electrode formed at a position facing the diaphragm, deforming the diaphragm by electrostatic force acting between the electrode and the diaphragm, and causing the recording body to be a recording medium by the generated pressure. In a recording head for discharging, an angle between a side surface of the step and a surface provided with an electrode is 15 ° or less, and the first electrode is provided from the upper surface of the electrode substrate to a side surface of the step, and A recording head, wherein an insulating film is provided on an electrode or on a surface facing the diaphragm. 6. The recording head according to claim 5, wherein the total surface energy of the insulating film is 50 mJ / m ² or less. 7. The recording head according to claim 5, wherein the insulating film is a hard carbon film.