JP2011131387A - Liquid droplet ejection head, liquid droplet ejection device, and method for manufacturing nozzle substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet ejection head that easily detects dot omission in a liquid droplet ejection head and a temperature change, in real time, and to provide a liquid droplet ejection device, and a method for manufacturing a nozzle substrate. <P>SOLUTION: The liquid droplet ejection head includes: a nozzle substrate 12 having a plurality of nozzle holes 10 for ejecting liquid droplets and having at least a temperature sensor 28 formed on the edge of each nozzle hole 10 around the nozzle hole 10; a cavity substrate 14 the bottom wall of which serves as a vibrating plate 22, and which has a plurality of pressure chambers 26 communicating with the nozzle holes 10 of the nozzle substrate 12 and accommodating an ejection liquid, and is laminated on the nozzle substrate 12; an electrode substrate 16 which has an individual electrode 18 for driving the vibrating plate 22 and is laminated on the cavity substrate 14; and an ejection detection circuit 34 for determining whether the jetting of a liquid droplet is satisfactory or not based on a temperature changed by a quantity of the ejection liquid which is present in each nozzle hole 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a droplet discharge head, a droplet discharge device, and a method for manufacturing a nozzle substrate.

  As a typical example of the droplet discharge device, there is an ink jet recording device provided with an ink jet head for image recording. Inkjet recording apparatuses are used for many printing including color printing in recent years because noise during printing is relatively small and small dots can be formed with high density. Such an ink jet recording apparatus includes an ink jet head that receives supply of ink (ejection liquid) from an ink cartridge, and a paper feed mechanism that moves a recording medium perpendicularly to the scanning direction of the ink jet head. Recording is performed by ejecting ink droplets (droplets) to the recording medium by generating mechanical pressure and thermal energy to the inkjet head while moving in the width direction (main scanning direction) of the recording medium. Is called.

  An ink jet head used in such an ink jet recording apparatus generally has a nozzle substrate on which a plurality of nozzles for ejecting ink droplets are formed, and is connected to the nozzle substrate between the nozzle substrate and the nozzle substrate. Pressure chamber (cavity) and a cavity substrate on which an ink flow path such as a reservoir is formed, and pressure is applied to the pressure chamber by the drive unit to displace the vibration plate constituting a part of the pressure chamber, thereby A droplet is ejected from a selected nozzle. As a driving means, there are a method using an electrostatic force, a piezoelectric method using a piezoelectric element, a bubble jet (registered trademark) method using a heating element, and the like.

  In this type of inkjet head, when bubbles are generated in the pressure chamber of the inkjet head, floating paper powder or dust adheres to the vicinity of the nozzle, or the nozzle (inner ink) dries, ink droplets from the nozzle. May not be ejected, and dots may not be formed on the recording medium. Ink droplet ejection failure is generally called “dot missing”. When a dot missing phenomenon occurs, recovery is performed by a cleaning device. For example, when the dot drop phenomenon occurs due to the generation of bubbles, the ink in the nozzle is sucked with a pump to discharge the bubbles in the pressure chamber, and then the ink adhered to the discharge surface with a wiping member called a wiper The ink is then discharged, and then ink droplets called no flushing are ejected without printing to discharge the mixed ink. This series of cleaning steps recovers the dot drop phenomenon due to bubbles.

  As a method for detecting the missing dot as described above, for example, the operation failure is detected without reducing the recording speed by detecting the recording element that does not operate in real time during the reciprocating scan of the recording head by the photo sensor. Has been proposed (see, for example, Patent Document 1).

  Also, “Data related to the temperature of the print head is obtained by the temperature sensor and the temperature sensor control circuit provided in the print head, and the rise temperature data before and after printing is compared with the normal rise temperature data when there is no ejection failure. In other words, a method for detecting an ink ejection defect is proposed (for example, see Patent Document 2).

  Furthermore, “when an ink droplet adheres to the vicinity of the nozzle, an inkjet head that discharges ink from a plurality of nozzles, a first electrode and a second electrode provided in the vicinity of the nozzle, the first electrode There has been proposed an “ink-jet recording apparatus including an electrode and a capacitance detection unit that detects a change in capacitance between the second electrode” (for example, see Patent Document 3). In this technique, a counter electrode is provided in the vicinity of the nozzle on the head surface, and a residual ink droplet around the nozzle is detected by detecting a change in capacitance between the electrodes. In this technique, missing dots are detected for cleaning defects and ink droplet adhesion during ejection.

Japanese Patent Laid-Open No. 11-17984 JP 2000-289218 A Japanese Patent Laid-Open No. 2007-230008

  The technique described in Patent Document 1 has to be adjusted each time because the detection sensitivity differs depending on the surface condition of the recording medium and the recording elements.

  Moreover, the technique described in Patent Document 2 is only a description relating to a detection principle, a circuit, and a control method, and does not mention a specific structure in which a temperature detecting element is provided in each nozzle.

  Further, the technique described in Patent Document 3 prevents an ink droplet ejection failure in advance or enables an occurrence of an ink droplet ejection failure to be detected at an early stage. However, if ink droplets do not adhere in the vicinity of the nozzles on the head surface, that is, if ink cannot be accumulated by ink droplets, it is not possible to detect ink droplet ejection defects. Therefore, the technique described in Patent Document 1 cannot be used for detection of non-ejection nozzles, that is, detection of missing dots. Further, the technique described in Patent Document 1 cannot be used for detecting the ejection amount of ink droplets.

  The present invention has been made in view of these points, and a droplet discharge head, a droplet discharge device, and a nozzle substrate that can easily detect dot dropout and temperature change in the droplet discharge head in real time. It aims at providing the manufacturing method of.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] A nozzle substrate having at least a plurality of nozzle holes for discharging droplets and a temperature sensor formed at the edge of each nozzle hole around each nozzle hole, and a bottom wall constituting a diaphragm. A plurality of pressure chambers communicating with the plurality of nozzle holes of the nozzle substrate and containing a discharge liquid, a cavity substrate stacked on the nozzle substrate, and an individual electrode for driving the diaphragm, A droplet discharge comprising: an electrode substrate stacked on the cavity substrate; and a discharge detection circuit that determines whether the droplet discharge state is good or not based on a temperature that changes depending on an amount of the discharge liquid existing in the nozzle hole. head.

  According to this, it is possible to detect the droplet discharge state based on the temperature change of the temperature sensor. Therefore, the droplet discharge operation can be directly confirmed without being interrupted, and a defective discharge nozzle can be easily identified. When an ejection failure nozzle is specified, the quality of the object can be complemented by ejection droplets from another nozzle hole.

  Application Example 2 In the above-described droplet discharge head, the discharge detection circuit detects a weak current generated when the temperature of the temperature sensor changes depending on the presence or absence of discharge liquid, and determines whether the droplet discharge state is good or bad. A droplet discharge head characterized by judging.

  According to this, the droplet existing in the nozzle hole acts as a substance that changes the temperature, and it is possible to detect not only the missing dot but also the abnormality of the ejection amount of the droplet.

  Application Example 3 In the droplet discharge head, the droplet discharge head is characterized in that the temperature of the temperature sensor is maintained at a higher temperature than the discharge liquid by passing a constant current through the temperature sensor.

  According to this, the temperature of the temperature sensor is surely lowered by passing the discharge liquid, and a weak current can be surely generated.

  Application Example 4 In the above-described liquid droplet ejection head, the liquid droplet ejection head is characterized in that the holding temperature of the temperature sensor is 5 degrees or more higher than the liquid ejection.

  According to this, the temperature drop amount of the temperature sensor generated by the passage of the discharge liquid sufficiently exceeds the detection sensitivity of the temperature sensor, so that the temperature drop can be reliably detected.

  Application Example 5 In the droplet discharge head, an insulating material having a lower thermal conductivity than the material of the base material is formed between the temperature sensor and the base material forming the nozzle substrate. A droplet discharge head comprising an insulating film.

  According to this, the temperature change of the nozzle hole can be measured while more reliably preventing the heat held by the temperature sensor from being transmitted to the base material.

Application Example 6 In the droplet discharge head, the insulating material is SIO ₂ or the like.

According to this, since SiO ₂ or the like having low thermal conductivity is interposed between the base material and the temperature sensor, it is possible to more reliably prevent the heat held by the temperature sensor from being transmitted to the base material. The temperature change of the nozzle hole can be measured. Further, since there are abundant film forming means, it is possible to select a film forming means having high quality and low cost according to the specifications of the droplet discharge head.

  Application Example 7 In the droplet discharge head, the temperature sensor partially extends to the inner wall of the nozzle hole.

  This makes it possible to reliably detect the passage of the discharge liquid as a temperature change.

  Application Example 8 In the droplet discharge head, the temperature sensor is made of a conductive material having abrasion resistance and chemical resistance.

  According to this, mechanical contact at the time of head cleaning and durability against discharged liquid can be ensured, and reliability can be ensured over a long period of use.

  Application Example 9 In the droplet discharge head, the temperature sensor is a thermocouple or a thermistor.

  According to this, each temperature of a plurality of nozzle holes can be controlled with higher accuracy.

  Application Example 10 In the droplet discharge head, the thermocouple is characterized in that a contact point of the thermocouple is formed at least at an edge of each nozzle hole.

  According to this, since the temperature detection unit of the thermocouple is disposed in the droplet discharge unit, it is possible to reliably detect a temperature drop due to droplet discharge.

  Application Example 11 In the liquid droplet ejection head, the thermocouple is any one of Pt, Au, Mo, Ta, an alloy thereof, or a compound thereof.

  According to this, abrasion resistance and chemical resistance (alkali resistance) are improved.

  [Application Example 12] A droplet discharge apparatus including the droplet discharge head according to any one of the above.

  According to this, the droplet discharge device has the same effect as that of the above-described droplet discharge head.

  Application Example 13 A step of forming a recess to be a nozzle hole in a silicon substrate, a step of forming a thermal oxide film on the silicon substrate by thermal oxidation, and a step of attaching a support substrate to the recess formation surface of the silicon substrate Thinning the side opposite to the recess forming surface of the silicon substrate to open the recess, forming a temperature sensor at the edge of each opened nozzle hole, the thinned surface of the silicon substrate, and A step of forming a droplet protective film inside the concave portion, a step of forming a liquid repellent film on the droplet protective film, and a support tape bonded to the side surface opposite to the concave portion forming surface of the silicon substrate And removing the support substrate from the silicon substrate and hydrophilizing the liquid repellent film formed on the silicon substrate from the side where the support substrate is peeled off, and the silicon substrate. Process and method of manufacturing a nozzle plate, characterized in that and a step of exposing the wiring connection portion of the temperature sensor of removing the support tape from the substrate.

  According to this, it is possible to manufacture a nozzle substrate that detects a droplet discharge state by a change in temperature of the temperature sensor. Therefore, the droplet discharge operation can be directly confirmed without being interrupted, and a defective discharge nozzle can be easily identified. When an ejection failure nozzle is specified, a nozzle substrate that complements the quality of the object can be manufactured by ejection droplets from another nozzle hole.

  Application Example 14 In the nozzle substrate manufacturing method, the step of forming the temperature sensor includes a step of forming a second electrode on the edge of each opened nozzle hole by oblique sputtering or oblique deposition. Forming a first electrode by oblique sputtering or oblique vapor deposition at least on the second electrode and at the edge of each opened nozzle hole. Production method.

  According to this, since the first electrode and the second electrode are formed in separate steps, the first electrode and the second electrode can be reliably bonded. Further, the first electrode and the second electrode can be formed on the inner wall of the nozzle hole by forming the film obliquely.

FIG. 3 is an exploded perspective view illustrating a state in which the droplet discharge head according to the first embodiment is disassembled. FIG. 3 is a longitudinal sectional view showing a longitudinal section of a droplet discharge head. The top view which shows the state which looked at the droplet discharge head from the top. Explanatory drawing for demonstrating the relationship between a nozzle hole and a thermocouple. The conceptual diagram which shows typically the operation principle at the time of discharge detection. The longitudinal cross-sectional view which shows a part of manufacturing process example of a nozzle substrate. The longitudinal cross-sectional view which shows a part of manufacturing process example of a nozzle substrate. The longitudinal cross-sectional view which shows a part of manufacturing process example of a nozzle substrate. FIG. 2 is a perspective view showing an example of a droplet discharge device equipped with the droplet discharge head according to the first embodiment.

The present embodiment will be described below with reference to the drawings. In the drawings to be referred to in the following description, the scales are different for each layer and each member so that each layer and each member have a size that can be recognized on the drawing.
(First embodiment)
FIG. 1 is an exploded perspective view showing a state in which the droplet discharge head 2 according to the present embodiment is disassembled. FIG. 2 is a longitudinal sectional view showing a longitudinal section of the droplet discharge head 2. FIG. 3 is a plan view showing the droplet discharge head 2 as viewed from above. The configuration and operation of the droplet discharge head 2 will be described with reference to FIGS. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one. Further, the upper side of the figure is the upper side, the lower side is the lower side, the direction in which the nozzle holes 10 are arranged is the short direction, and the direction perpendicular to the short side direction is the long side direction. In FIG. 2, the outer liquid repellent film is omitted, and in FIG. 3, the outer liquid repellent film and the droplet protective film are omitted.

  This droplet discharge head 2 is a representative of an electrostatic actuator of electrostatic drive driven by electrostatic force, and is a face eject type droplet discharge that discharges droplets from nozzle holes provided on the surface side of the nozzle substrate. Represents the head. The droplet discharge head 2 has a three-layer structure in which three substrates, a nozzle substrate 12, a cavity substrate 14, and an electrode substrate 16, are joined in order. That is, in the droplet discharge head 2, the nozzle substrate 12 is bonded to one surface (upper surface) of the cavity substrate 14, and the electrode substrate 16 is bonded to the other surface (lower surface). The substrate 16 and the nozzle substrate 12 are sandwiched from above and below.

  The droplet discharge head 2 includes an individual electrode 18 formed on the electrode substrate 16 and a vibration plate 22 of the cavity substrate 14 disposed to face the individual electrode 18 with a predetermined drive gap 20 therebetween. Equipped with an electrostatic actuator. In the droplet discharge head 2 according to this embodiment, the electrode substrate 16 and the cavity substrate 14 are bonded by anodic bonding, and the cavity substrate 14 and the nozzle substrate 12 are bonded using an adhesive such as an epoxy resin. Will be described. Further, a drive signal (pulse voltage) is supplied to the individual electrode 18 formed on the electrode substrate 16 of the droplet discharge head 2 by a drive circuit 24 which is a power supply means such as a driver IC shown in FIG. ing.

[Nozzle substrate]
The nozzle substrate 12 is configured using, for example, a silicon single crystal substrate (hereinafter, simply referred to as a silicon substrate) having a (100) plane orientation with a thickness of about 65 μm (micrometer) as a main material. Then, it is bonded to the upper surface of the cavity substrate 14 (the surface opposite to the surface to which the electrode substrate 16 is bonded). A plurality of nozzle holes 10 communicating with each of the cavities (discharge chambers) 26 are formed in the nozzle substrate 12 so as to penetrate at a predetermined pitch. Each nozzle hole 10 discharges droplets such as ink droplets transferred from the cavity 26 to the outside. Note that the surface of the nozzle substrate 12 on which droplets are ejected is referred to as a droplet ejection surface 12a, and the side surface opposite to the droplet ejection surface 12a is referred to as an adhesive surface 12b.

  Each nozzle hole 10 is composed of a cylindrical first nozzle hole 10a on the tip side in the ejection direction and a cylindrical second nozzle hole 10b having a diameter larger than that of the first nozzle hole 10a. And the second nozzle hole 10b are provided coaxially. With this configuration, the droplet discharge direction can be aligned with the central axis direction of the nozzle hole 10, and stable droplet discharge characteristics can be exhibited. That is, by forming the nozzle holes 10 in a plurality of stages, there is no variation in the flying direction of the droplets, there is no scattering of the droplets, and variations in the discharge amount of the droplets can be suppressed.

  On the droplet discharge surface 12a of the nozzle substrate 12, a thermocouple 28 is provided as a temperature sensor used when dot missing detection is performed (dot missing detection will be described in detail in FIG. 4 and subsequent figures). The thermocouple 28 is a phenomenon in which a voltage is generated in a circuit when a metal circuit 28a, 28b made of two different materials is connected to form one circuit (thermocouple) and a temperature difference is given to two contact portions. We are using. The temperature of the contact portion 30a is obtained by measuring the flow of electric charge generated at that time.

  The first contact portion 30a of the two different types of metal electrodes 28a and 28b, that is, the portion for measuring the temperature, is formed at the edge of each nozzle hole 10. The second contact portion 30b is formed at the connection portion between the common electrode 28A and the metal electrode 28b. Thereby, the temperature of the nozzle hole 10, particularly the temperature when the discharge liquid (discharge liquid 32 shown in FIG. 5) exists in the nozzle hole 10, is measured, and the discharge detection circuit 34 discharges the droplet based on this temperature information. The judgment of the quality of the situation is made.

  As described above, the thermocouple 28 includes two types of metal electrodes 28a and 28b made of different materials. Typical combinations of the two types of metal wire materials are chromel (alloys mainly composed of nickel and chromium) and alumel (alloys mainly composed of nickel), but in addition, iron and constantan (copper and nickel). Main alloys), copper and constantan, chromel and constantan, etc. are known. Any combination of these may be used. Further, the thermocouple 28 is made of a conductive material (for example, Pt (platinum), Au (gold), Mo (molybdenum), Ta (tantalum), an alloy thereof, or an alloy excellent in abrasion resistance and chemical resistance (alkali resistance). These compounds etc.) may be comprised.

  Note that the contact portion 30a of the thermocouple 28 is preferably in close contact with the discharged liquid. This is for more accurately measuring the temperature of the discharged liquid. However, in order to ensure electrical insulation and chemical resistance between the contact portion 30a of the thermocouple 28 and the discharged liquid, it is necessary to form an insulating coating on the contact portion 30a.

  A droplet protective film 36 is provided on the thermocouple 28. The droplet protective film 36 is disposed so as to fill the uneven portion of the thermocouple 28 formed in an uneven shape, and its upper surface is formed substantially flat.

  A thermocouple 28 (for convenience, an electrode on the right side of the paper is referred to as a metal electrode 28a and an electrode on the left side of the paper is referred to as a metal electrode 28b) is formed at the edge of each nozzle hole 10 around each nozzle hole 10. The thermocouple 28 is formed so as to extend from the edge of each nozzle hole 10 to the upper part of the inner wall of each nozzle hole 10.

The metal electrode 28 a is connected to the ejection detection circuit 34 via the wiring 38 or the wiring 40. The base material of the nozzle substrate 12 and the thermocouple 28 are insulated by insulating films 68 and 69 made of an insulating material having a lower thermal conductivity than the material of the base material forming the nozzle substrate 12. The insulating films 68 and 69 are made of, for example, SiO ₂ .

A droplet protective film 36 is formed on the droplet discharge surface 12a of the nozzle substrate 12 and the inner wall of the nozzle hole 10 to protect these surfaces from the discharge liquid. Therefore, the droplet protective film 36 is formed on the thermocouple 28. The droplet protective film 36 is made of an insulating material (for example, SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O _5, etc.) having excellent chemical resistance (particularly alkali resistance) and abrasion resistance. ing. Therefore, it is possible to prevent inconveniences such as the surface of the thermocouple 28 coming into contact with the medium and being worn during the droplet discharge operation, for example, when the medium such as paper is fed during the printing operation.

  Further, a liquid repellent film (the liquid repellent film 42 shown in FIG. 8) may be formed on the droplet protective film 36 on the droplet discharge surface 12a. When the liquid repellent film is formed on the droplet discharge surface 12a, the liquid repellent film is not formed on the inner wall of the nozzle hole 10 and the adhesive surface 12b with the discharge port edge of the nozzle hole 10 as a boundary. As a result, it is possible to improve durability against the discharged liquid and prevent droplets remaining on the droplet discharge surface 12a.

  A diaphragm for buffering the pressure applied to the discharge liquid on the reservoir 44 side by an orifice or diaphragm 22 described later may be formed on the bonding surface 12 b of the nozzle substrate 12. Here, the nozzle substrate 12 is described as the upper surface, and the electrode substrate 16 is described as the lower surface. However, when actually used, the nozzle substrate 12 is often lower than the electrode substrate 16.

  The heater 62 is for heating the nozzle substrate 12. In particular, it is for heating the thermocouple 28.

  Note that the temperature sensor according to the present embodiment is not limited to a thermocouple, and may be another temperature sensor. For example, a thermistor may be used.

[Cavity substrate]
The cavity substrate 14 is composed of, for example, a silicon substrate having a thickness of about 50 μm as a main material. Either or both of dry etching and anisotropic wet etching are performed on the silicon substrate to form each member (cavity 26, orifice 46, reservoir 44, etc.) serving as a flow path for the discharge liquid. The cavity 26, which is one of the members of the cavity substrate 14, has a diaphragm 22 having a flexible bottom wall, acts as a discharge chamber (pressure chamber), and is independent at a position corresponding to the nozzle hole 10. A plurality are formed. Therefore, when the nozzle substrate 12 and the cavity substrate 14 are joined, the cavity 26 communicates with the reservoir 44 through the nozzle hole 10 and the orifice 46.

  The cavities 26 are formed corresponding to the electrode rows of the individual electrodes 18 so that the discharge liquid is held and discharge pressure is applied. The cavities 26 are formed in parallel from the front side to the back side of the drawing. The reservoir 44 functions as a common ink chamber for storing the discharge liquid supplied through the droplet supply port 48 and supplying the discharge liquid to each cavity 26. That is, the reservoir 44 communicates with all the cavities 26 through the respective orifices 46.

  A droplet supply port 48 penetrating the bottom surface of the reservoir 44 is formed on the bottom surface of the reservoir 44. The droplet supply port 48 communicates with the droplet supply port 50 of the electrode substrate 16. The discharge liquid is supplied from the outside to the reservoir 44 through the droplet supply port 48 and the droplet supply port 50. The orifice 46 is formed in a narrow groove shape, and functions as a droplet supply port that allows the reservoir 44 and the cavity 26 to communicate with each other. The orifice 46 may be formed on the bonding surface 12 b of the nozzle substrate 12.

The diaphragm 22 is composed of a high-concentration boron-doped layer. In order to form the diaphragm 22 having a desired thickness, a boron doped layer having the same thickness is formed. The etching rate in etching single crystal silicon with an alkaline solution such as an aqueous potassium hydroxide solution is very small in a high concentration region of about 5 × 10 ¹⁹ atoms / cm ³ or more when the dopant is boron. Therefore, a so-called etching stop technique in which the portion of the diaphragm 22 is a high-concentration boron-doped layer and the boron-doped layer is exposed and the etching rate becomes extremely small when the cavity 26 is formed by anisotropic etching with an alkaline solution. By using this, the thickness of the diaphragm 22 and the volume of the discharge chamber can be formed with high accuracy.

A TEOS film (here, Tetraethyl orthosilicate Tetraethoxysilane) for electrically insulating the diaphragm 22 and the individual electrode 18 is formed on the lower surface of the cavity substrate 14 (the surface facing the electrode substrate 16 and the lower surface of the diaphragm 22). : An insulating film 52 which is a SiO ₂ film made of tetraethoxysilane (ethyl silicate)) is formed by using a plasma CVD (Chemical Vapor Deposition: TEOS-pCVD) method, for example, a film thickness of about 0.1 μm. The film is formed. This insulating film 52 is for preventing dielectric breakdown and short-circuiting when the diaphragm 22 is driven and for preventing etching of the cavity substrate 14 by the discharge liquid.

Here, the case where the insulating film 52 is a TEOS film will be described as an example. However, the present invention is not limited to this, and any material that improves the insulating performance may be used. For example, a dielectric material having a higher relative dielectric constant than silicon oxide such as Al ₂ O ₃ (aluminum oxide (alumina)) or silicon oxynitride may be used. In addition, the insulating film may be formed by ALD (Atomic Layer Deposition) method, ECR (Electron Cyclotron Resonance) sputtering, or the like, without being limited to the case where the film is formed by plasma CVD.

Furthermore, an SiO ₂ film (including a TEOS film) that serves as a liquid protective film (not shown) may be formed on the upper surface of the cavity substrate 14 by plasma CVD or sputtering. This is because the formation of such a liquid protective film can prevent the flow path from being corroded by the discharged liquid. There is also an effect that the stress of the liquid protective film and the stress of the insulating film 52 are offset to reduce the warpage of the diaphragm 22. Further, a highly lubricated hard film made of DLC or the like may be formed on the surface of the insulating film 52 (the surface of the insulating film 52 on the electrode substrate 16 side) and in contact with the individual electrode 18.

  In addition, a common electrode 54 as an external electrode terminal is formed on the cavity substrate 14. The common electrode 54 serves as a terminal when electric charges having a polarity opposite to that of the individual electrode 18 are supplied from the drive circuit 24 to the diaphragm 22 via an FPC (Flexible Printed Circuit) (not shown).

[Electrode substrate]
The electrode substrate 16 is preferably formed using, for example, glass such as borosilicate heat-resistant hard glass having a thickness of 1 mm as a main material. This is because when the electrode substrate 16 and the cavity substrate 14 are anodically bonded, the thermal expansion coefficients of the two substrates are close to each other, so that the stress generated between the electrode substrate 16 and the cavity substrate 14 can be reduced. This is because the electrode substrate 16 and the cavity substrate 14 can be firmly bonded without causing such problems. On the surface of the electrode substrate 16 facing the cavity substrate 14, a recess (glass groove) 20 a that matches the shape of the cavity 26 of the cavity substrate 14 has a depth of about 0.3 μm, for example, by etching. Is formed.

  In addition, inside the recess 20a (particularly at the bottom), an individual electrode 18 serving as a fixed electrode is formed with a thickness of 0.1 μm, for example, by sputtering. And this recessed part 20a is the individual electrode 18, the terminal part 18b connected to FPC inside, and the individual electrode lead part 18a which connects the terminal part 18b and the individual electrode 18 (unless it is necessary to distinguish in particular, it is individual The electrode 18 may be patterned in a slightly larger shape similar to these shapes so that an electrode 18 (described as including the individual electrode lead portion 18a and the terminal portion 18b) can be mounted. Moreover, although the case where the depth of the recessed part 20a is about 0.2 micrometer is shown as an example, it can change according to the thickness of the individual electrode 18 produced in the recessed part 20a.

  The individual electrode 18 may be produced by sputtering transparent ITO (Indium Tin Oxide) doped with tin oxide as an impurity with a thickness of 0.1 μm, for example. As described above, when the individual electrode 18 is made of ITO, there is an advantage that it is easy to confirm whether or not the discharge has occurred because it is transparent. The material of the individual electrode 18 is not limited to ITO, and a metal material such as chromium may be used. In addition, the electrode substrate 16 is formed with a droplet supply port 50 that penetrates the droplet supply port 48 of the reservoir 44 and serves as a flow path for taking in the discharge liquid supplied from an external ink tank.

  Further, the FPC mounting portion 56 is formed on the electrode substrate 16 together with the recess 20a. A terminal portion 18 b is formed on the FPC mounting portion 56. That is, the terminal portion 18b is exposed in the electrode extraction portion 58 in which the end portion of the cavity substrate 14 is opened for wiring. An FPC (not shown) is mounted on the FPC mounting portion 56 so that one end (terminal portion 18 b) of the individual electrode 18 and the drive circuit 24 are connected. Therefore, a drive signal is supplied to the individual electrode 18 from the drive circuit 24 via the FPC.

  When the electrode substrate 16 and the cavity substrate 14 are anodically bonded to form a laminated body, a certain drive gap (between the diaphragm 22 and the individual electrode 18 can be deflected (displaced) the diaphragm 22. An air gap) 20 is formed by the recess 20a of the electrode substrate 16. The drive gap 20 is determined by the depth of the recess 20 a and the thickness of the individual electrode 18. Since the drive gap 20 greatly affects the ejection characteristics of the droplet ejection head 2, strict accuracy management is required. The drive gap 20 is formed to be elongated and have a predetermined depth at a position facing each diaphragm 22. The open end portion of the drive gap 20 is hermetically sealed with a sealing portion 60 made of a resin such as epoxy so that moisture and dust do not enter the inside.

  In addition, although the case where the depth of FPC mounting part 56 is about 0.3 micrometer is shown as an example, it is not limited to this, It is good to change according to the depth of recessed part 20a. The drive gap 20 may be hermetically sealed with the sealing portion 60 after performing a vapor phase process. The gas phase treatment is performed so as to perform the hydrophobic treatment after the moisture in the drive gap 20 is removed. The drive gap 20 can also be formed by forming a recess in the silicon substrate that will be the cavity substrate 14 or sandwiching a spacer.

  In the droplet discharge head 2, a plurality of individual electrodes 18 are formed in a rectangular shape having long sides and short sides, and the individual electrodes 18 are arranged so that their long sides are parallel to each other. FIG. 1 shows one electrode row extending in the short side direction of the individual electrode 18. In addition, when the short side of the individual electrode 18 is formed obliquely with respect to the long side and the individual electrode 18 has an elongated parallelogram shape, an electrode array extending in a direction perpendicular to the long side direction is formed. What should I do? The electrode substrate 16 and the cavity substrate 14 can be bonded by anodic bonding, and the cavity substrate 14 and the nozzle substrate 12 can be bonded by bonding using an adhesive or direct bonding.

The operation of the droplet discharge head 2 will be briefly described.
A discharge liquid such as ink is supplied to the reservoir 44 of the cavity substrate 14 from the outside through the droplet supply port 50 and the droplet supply port 48. Further, the discharge liquid is supplied from the reservoir 44 to the cavity 26 of the cavity substrate 14 through the orifice 46. The drive circuit 24 is connected to the individual electrode 18 via the FPC, and controls supply and stop of charge to the individual electrode 18. The drive circuit 24 oscillates at, for example, 24 kHz, applies a pulse potential of about 0 V to 30 V to the selected individual electrode 18 to supply charges, and charges the individual electrode 18 positively.

  At this time, charge having a negative polarity is supplied to the cavity substrate 14 through the common electrode 54, and the diaphragm 22 corresponding to the positively charged individual electrode 18 is relatively negatively charged. Therefore, an electrostatic force (Coulomb force) is generated between the selected individual electrode 18 and the diaphragm 22. If it does so, the diaphragm 22 will be drawn near to the individual electrode 18 side by electrostatic force, and will bend (displace). That is, the diaphragm 22 is attracted to and abuts on the individual electrode 18. This increases the volume of the cavity 26.

  Thereafter, when the supply of electric charges to the individual electrode 18 is stopped, the electrostatic force between the diaphragm 22 and the individual electrode 18 disappears, and the diaphragm 22 is restored to its original state by its elastic force. At this time, since the volume of the cavity 26 decreases rapidly, the pressure inside the cavity 26 increases rapidly. Thereby, a part of the discharge liquid in the cavity 26 is discharged from the nozzle hole 10 as a droplet. For example, printing is performed by the droplets landing on a recording sheet, for example. Thereafter, the discharge liquid is replenished from the reservoir 44 into the cavity 26 through the orifice 46 and returns to the initial state. Such a method is called pulling, but there is also a method called pushing that discharges droplets using a spring or the like.

From here, the dot missing detection which is the characteristic matter of this embodiment will be described in detail.
FIG. 4 is an explanatory diagram for explaining the relationship between the nozzle hole 10 and the thermocouple 28. FIG. 5 is a conceptual diagram schematically showing the operation principle at the time of ejection detection. 4A is an enlarged plan view showing a part of the droplet discharge surface 12a, and FIG. 4B is an enlarged cross-sectional view showing an AA ′ cross section of FIG. 4A. FIG. 5A is a schematic diagram illustrating a state before droplet ejection, and FIG. 5B is a schematic diagram illustrating a state during droplet ejection. FIG. 5 also shows a circuit diagram including the thermocouple 28 and the discharge detection circuit 34.

  As shown in FIG. 4A, a thermocouple 28 is formed around the nozzle hole 10 at the edge of each nozzle hole 10. In such a state, the temperature at the contact portion 30a varies depending on the position of the discharge liquid existing in the nozzle hole 10, that is, the amount of the discharge liquid.

  In the circuit composed of the thermocouple 28 and the discharge detection circuit 34, a weak current is generated due to a temperature difference between the contact portion 30a and the contact portion 30b due to a change in the temperature of the contact portion 30a. For example, a constant current is supplied to the thermocouple 28 before the droplet is discharged to heat the thermocouple 28 itself, and the temperature of the thermocouple 28 is set to be higher than the liquid temperature of the discharge liquid 32. Alternatively, the thermocouple 28 may be heated using a heater 62 (see FIG. 2), and the temperature of the thermocouple 28 may be set to be higher than the liquid temperature of the discharge liquid 32. Moreover, the temperature of the contact part 30a and the contact part 30b becomes the same by this heating. That is, the thermocouple 28 is in a state where no voltage is generated (no weak current is generated). Alternatively, the temperature difference between the contact part 30a and the contact part 30b may be kept constant so that a constant electromotive force is generated in the thermocouple 28 (a constant current is flowing). Thereby, the temperature of the contact portion 30a of the thermocouple 28 before the droplet discharge (t0 shown in FIG. 5A) becomes the temperature of the contact portion 30a of the thermocouple 28 at the time of droplet discharge (FIG. 5B). By changing to t1), a weak current is generated. Alternatively, the temperature difference between the contact part 30a and the contact part 30b changes, and the constant current changes. That is, the discharge liquid 32 acts as a substance that changes the temperature at the contact portion 30a. Since the temperature of the thermocouple 28 may be different from the temperature of the discharge liquid 32, the temperature of the thermocouple 28 may be lower than the temperature of the discharge liquid 32.

  By utilizing this principle, in this embodiment, dot missing detection and ejection amount abnormality detection can be executed in real time. Therefore, the droplet discharge head 2 can monitor the droplet discharge status (dot missing detection and discharge amount abnormality detection) in real time by detecting the presence or absence of the weak current generated. In other words, if there is no change in the circuit state (when no weak current is generated), it can be determined that dot missing has occurred, and if there is a change in the circuit state (weak current is generated). The discharge amount of the discharge liquid 32 can be determined from the current value. The weak current may be detected by connecting a current detector to the circuit.

  The missing dot detection operation of the droplet discharge head 2 is an operation for inspecting missing dots in all the nozzle holes 10 formed in the nozzle substrate 12. Therefore, the droplet discharge head 2 can detect whether or not the discharge liquid 32 is discharged from the nozzle hole 10, that is, whether or not there is a defective discharge nozzle in which dot missing has occurred, based on a change in the temperature of the contact portion 30 a. it can. Therefore, it is possible to directly check the print quality of a target object such as a droplet discharge operation, for example, a recording paper without interrupting the print operation, and it is possible to easily identify a defective discharge nozzle. Furthermore, when the defective ejection nozzle is specified, the quality of the object can be complemented by the ejection liquid 32 from another nozzle hole 10.

  When a defective nozzle is found by the missing dot detection operation, the recovery process is automatically executed depending on the number and status of the defective nozzles, the operator is notified without executing the recovery process, or the recovery process is performed. It is preferable to select a measure for resuming the printing process as it is without performing notification. That is, when the number of defective nozzles and the distribution state are unacceptable, a recovery operation is automatically performed by a recovery unit that recovers the discharge characteristics of the defective nozzles, and the number of defective nozzles and the distribution state are within a predetermined allowable range. If it is within the range, the operator is notified without executing the recovery operation, and if the number or state of defective nozzles is within the allowable range that has little impact on the discharge quality, that is, the print quality, the next printing operation is continued. To start.

  As a determination criterion at this time, for example, when the number of defective ejection nozzles is a small number that hardly affects print quality with respect to the number of nozzles constituting the nozzle group, A printing operation can be started. Also, if the number of detected defective nozzles is within the range that is not negligible in print quality with respect to the number of nozzles constituting the nozzle group, but is likely to be acceptable to some extent, the operator is notified to determine If it can be ignored, printing is started, and if it cannot be ignored, a recovery operation is performed. Further, when the number of detected defective nozzles is large enough to affect the print quality with respect to the number of nozzles constituting the nozzle group, the recovery operation is automatically executed.

  In addition, as a distribution state of defective nozzles, for example, when it is detected that adjacent nozzle holes 10 have a plurality of defective discharges, there is a high possibility that the print quality will be affected, so regardless of the number of defective nozzles. It is recommended to perform recovery operation automatically. Note that the number of defective ejection nozzles and the like, which are the determination criteria, may be set in advance and stored in a storage unit such as a RAM. If it does so, it will control to judge using the memorize | stored setting value. For example, if the design has a large area of one color, printing failure due to defective ejection nozzles tends to be noticeable, and if it is a fine pattern, it is difficult to notice even if there are some ejection failure nozzles, so depending on the design to be printed and the type of recording medium, etc. It can be set by the operator.

  As described above, the droplet discharge head 2 detects the weak current generated at the time when the temperature at the contact portion 30a changes depending on the amount of the discharge liquid 32 present in the nozzle hole 10, and thereby the dot of each nozzle hole 10 is detected. Missing and discharge amount can be detected. Accordingly, the droplet discharge head 2 can monitor the discharge state of the discharge liquid 32 in real time. Therefore, it is possible to quickly find a defective ejection nozzle and to prevent the quality of the object from deteriorating.

  Further, since the droplet protective film 36 is formed on the thermocouple 28, the thermocouple 28 can be protected by the droplet protective film 36. In addition, since the conductive material used for the thermocouple 28 is a material having abrasion resistance and ink resistance (chemical resistance) against the discharged liquid, it is practically easy to control the voltage, and the durability of the thermocouple 28. The reliability can be ensured over a long period of use.

  Next, the manufacturing process of the nozzle substrate 12 of the droplet discharge head 2 will be described. 6 to 8 are longitudinal sectional views showing a part of manufacturing steps of the nozzle substrate 12. Based on FIGS. 6-8, the manufacturing process of the nozzle board | substrate 12 is demonstrated centering on the characteristic matter.

First, as shown in FIG. 6A, a single crystal silicon substrate 12 ′ having a thickness of 725 μm and conductivity is prepared, set in a thermal oxidation apparatus (not shown), an oxidation temperature of 1075 ° C., an oxidation time of 90 minutes, Thermal oxidation is performed under the condition of a mixed atmosphere of water and water vapor, and a thermal oxide film (SiO ₂ film) 64 having a film thickness of 0.5 μm is uniformly formed on the surface of the silicon substrate 12 ′. Then, a recess 64a to be the second nozzle hole 10b is patterned in the thermal oxide film 64 on the bonding surface 12b of the silicon substrate 12 ′.

  Next, as shown in FIG. 6B, a resist film 66 having a thickness of 1.0 μm is formed on the adhesive surface 12b of the silicon substrate 12 ′, and a recess 66a that becomes the first nozzle hole 10a is formed by photolithography. Pattern.

Next, as shown in FIG. 6C, by using an ICP dry etching apparatus (not shown), the recess 66a that becomes the first nozzle hole 10a of the resist film 66 is anisotropically dry etched vertically at a depth of 40 μm, for example. First nozzle hole 10a is formed. In this case, C ₄ F ₈ and SF ₆ are used as the etching gas, and these etching gases may be used alternately. Here, C ₄ F ₈ is used for protecting the side surface of the groove so that the etching does not proceed to the side surface of the groove to be formed, and SF ₆ is used for promoting the vertical etching of the silicon substrate 12 ′. .

  Next, as shown in FIG. 6D, after removing the resist film 66, the concave portion 64a that becomes the second nozzle hole 10b of the thermal oxide film 64 is anisotropically perpendicular to the depth of 40 μm by an ICP dry etching apparatus. Dry etching is performed to form the second nozzle hole 10b. At this time, the first nozzle hole 10a is also etched to a depth of about 70 to 80 μm, and the nozzle hole 10 is completed.

  Next, as shown in FIG. 7A, after the thermal oxide film 64 remaining on the surface of the silicon substrate 12 ′ is peeled off, the droplet discharge surface 12a, the adhesive surface 12b, and the nozzle hole 10 of the silicon substrate 12 ′ are removed. An insulating film 68 having a thickness of 0.1 μm is formed on the inner wall by dry oxidation.

Next, as shown in FIG. 7B, a support substrate 70 is attached to the adhesive surface 12b of the silicon substrate 12 ′, and the thickness is reduced from the droplet discharge surface 12a side until the plate thickness becomes 65 μm. Subsequently, a 0.2 μm-thick silicone polymer film serving as the insulating film 69 is formed on the exposed surface of the droplet discharge surface 12a of the silicon substrate 12 ′ by plasma CVD using a siloxane material. Then, UV irradiation is performed in the air for dehydration condensation, and the surface of the insulating film 69 is changed to SiO ₂ .

  Next, as shown in FIG. 7C, a metal mask 72 is provided on the droplet discharge surface 12a, and one side (metal electrode 28b) of the thermocouple 28 having a thickness of 0.1 μm is obliquely sputtered or obliquely deposited. Formed by. At this time, the angle of oblique sputtering or oblique deposition is controlled or the substrate is rotated to form the metal electrode 28b up to the upper part of the inner wall of the nozzle hole 10.

  Next, as shown in FIG. 7D, the metal mask 72 is removed, a metal mask 74 is installed, and the other side (metal electrode 28a) of the thermocouple 28 having a thickness of 0.1 μm is obliquely sputtered or obliquely. It is formed by vapor deposition. At this time, the angle of oblique sputtering or oblique vapor deposition is controlled or the substrate is rotated to form the metal electrode 28 a up to the upper part of the inner wall of the nozzle hole 10. Thus, since the metal electrode 28a and the metal electrode 28b are formed in separate steps, they can be reliably bonded.

Next, as shown in FIG. 7E, the metal mask 74 is removed, and a 0.2 μm-thick silicone polymer film serving as the droplet protective film 36 is formed on the surface of the droplet discharge surface 12a of the silicon substrate 12 ′. It is formed by plasma CVD of siloxane raw material. Then, UV irradiation is performed in the air to cause dehydration condensation, and the surface of the droplet protective film 36 is changed to SiO ₂ .

  Next, as shown in FIG. 8A, a liquid repellent treatment is further performed on the droplet discharge surface 12a of the silicon substrate 12 '. In this case, a silane coupling material is dip coated to form a liquid repellent film 42 on the droplet discharge surface 12a. At this time, the liquid repellent film 42 is also formed on the inner walls of the first nozzle hole 10a and the second nozzle hole 10b.

  Next, as shown in FIG. 8B, a support tape 76 is attached to the droplet discharge surface 12a, and the support substrate 70 on the adhesive surface 12b side is peeled off in this state. Then, oxygen or argon plasma treatment is performed from the bonding surface 12b side, and the liquid-repellent film 42 formed on the inner wall of the nozzle hole 10 is broken and hydrophilized.

  Next, as shown in FIG. 8C, the support tape 76 is peeled off.

Next, as shown in FIG. 8D, the droplet protective film 36 and the liquid repellent film 42 in the wiring connection portion of the thermocouple 28 are selectively destroyed by laser irradiation. And the wiring connection part of the thermocouple 28 is exposed.
The nozzle substrate 12 can be easily manufactured by the above manufacturing process.

  When the droplet discharge head 2 is manufactured using the nozzle substrate 12 thus manufactured, the bonding surface of the cavity substrate 14 is bonded to the adhesive surface 12b of the nozzle substrate 12, and the nozzle substrate 12 and the cavity substrate are bonded. 14 joined bodies are formed. Thereafter, in the joined body including the nozzle substrate 12 and the cavity substrate 14, the joining surface of the electrode substrate 16 is attached to the other joining surface of the cavity substrate 14. By passing through the above process, the joined body of the nozzle substrate 12, the cavity substrate 14, and the electrode substrate 16 is formed, and the droplet discharge head 2 is completed.

(Second Embodiment)
FIG. 9 is a perspective view showing an example of a droplet discharge apparatus 100 equipped with the droplet discharge head 2 manufactured in the first embodiment. A droplet discharge device 100 shown in FIG. 9 is a general ink jet printer. The droplet discharge device 100 can be manufactured by a known manufacturing method. In addition to the droplet discharge device 100 shown in FIG. 9, the droplet discharge head 2 can change the discharge liquid 32 in various ways, thereby manufacturing a color filter for a liquid crystal display, forming a light emitting portion of an organic EL display device, It can also be applied to the discharge of biological liquids. Further, the present invention can also be applied as a droplet discharge device of a printed wiring board manufacturing apparatus that creates a wiring board by an inkjet method.

  The droplet discharge head 2 can also be used for a piezoelectric drive type droplet discharge device and a bubble jet (registered trademark) type droplet discharge device. For example, when the droplet discharge head 2 is used as a dispenser and used for discharging onto a substrate that is a biomolecule microarray, DNA (Deoxyribo Nucleic Acids), other nucleic acids (for example, Ribo Nucleic Acid: ribonucleic acid, (Peptide Nucleic Acids: peptide nucleic acids, etc.) A liquid containing a probe such as a protein may be discharged.

  The case where the droplet discharge head 2 according to the first embodiment has a three-layer structure including the electrode substrate 16, the cavity substrate 14, and the nozzle substrate 12 has been described as an example. However, the glass substrate, the cavity substrate, and the reservoir substrate are described. And a four-layer structure comprising nozzle plates.

  In addition, the droplet discharge device according to the present embodiment includes a droplet discharge device for producing a protein chip or a DNA chip, a droplet discharge device for a color filter manufacturing device for an organic EL manufacturing device or a liquid crystal display device, and a wiring board. It is possible to correspond to a droplet discharge device or the like of a printed wiring board manufacturing apparatus that produces the ink by the inkjet method.

  DESCRIPTION OF SYMBOLS 2 ... Droplet discharge head 10 ... Nozzle hole 10a ... 1st nozzle hole 10b ... 2nd nozzle hole 12 ... Nozzle substrate 12 '... Silicon substrate 12a ... Droplet discharge surface 12b ... Adhesion surface 14 ... Cavity substrate 16 ... Electrode substrate 18 ... individual electrode 18a ... individual electrode lead 18b ... terminal 20 ... drive gap 20a ... concave 22 ... diaphragm 24 ... drive circuit 26 ... cavity (pressure chamber) 28 ... thermocouple (temperature sensor) 28A ... common electrode 28a ... metal Electrode (first electrode) 28b ... Metal electrode (second electrode) 30a ... Contact part 30b ... Contact part 32 ... Discharge liquid 34 ... Discharge detection circuit 36 ... Drop protection film 38 ... Wiring 40 ... Wiring 42 ... Liquid repellent Membrane 44 ... Reservoir 46 ... Orifice 48 ... Droplet supply port 50 ... Droplet supply port 52 ... Insulating film 54 ... Common electrode 56 ... FP Mounting part 58 ... Electrode extracting part 60 ... Sealing part 62 ... Heater 64 ... Thermal oxide film 64a ... Recess 66 ... Resist film 66a ... Recess 68, 69 ... Insulating film 70 ... Support substrate 72 ... Metal mask 74 ... Metal mask 76 ... Support tape 100: droplet discharge device.

Claims (14)

A nozzle substrate having at least a plurality of nozzle holes for discharging liquid droplets and a temperature sensor formed at the edge of each nozzle hole around each nozzle hole;
A cavity substrate having a bottom wall constituting a diaphragm, having a plurality of pressure chambers communicating with the plurality of nozzle holes of the nozzle substrate and containing a discharge liquid, and stacked on the nozzle substrate;
An individual electrode for driving the diaphragm, and an electrode substrate stacked on the cavity substrate;
A discharge detection circuit that determines the quality of a droplet discharge state based on a temperature that varies depending on the amount of discharge liquid present in the nozzle hole;
A droplet discharge head characterized by comprising: The droplet discharge head according to claim 1,
The droplet discharge head, wherein the discharge detection circuit detects a weak current generated by a change in temperature of the temperature sensor depending on the presence or absence of a discharge liquid, and determines whether the droplet discharge state is good or bad. The droplet discharge head according to claim 2,
A droplet discharge head, wherein a constant current is passed through the temperature sensor to maintain the temperature of the temperature sensor at a higher temperature than the discharge liquid. The droplet discharge head according to claim 3,
A droplet discharge head, wherein a holding temperature of the temperature sensor is 5 degrees or more higher than that of the discharge liquid. In the droplet discharge head according to any one of claims 1 to 4,
A liquid droplet ejection head comprising an insulating film formed of an insulating material having a lower thermal conductivity than the material of the base material between the temperature sensor and the base material forming the nozzle substrate. The droplet discharge head according to claim 5,
The droplet discharge head, wherein the insulating material is SIO ₂ or the like. In the liquid droplet ejection head according to any one of claims 1 to 6,
A part of the temperature sensor extends to the inner wall of the nozzle hole. In the liquid droplet ejection head according to any one of claims 1 to 7,
The temperature sensor is made of a conductive material having abrasion resistance and chemical resistance. In the droplet discharge head according to any one of claims 1 to 8,
The temperature sensor is a thermocouple or a thermistor. The droplet discharge head according to claim 9,
The thermocouple has a contact point of the thermocouple formed at least at an edge of each nozzle hole. The droplet discharge head according to claim 9 or 10,
The droplet discharge head, wherein the thermocouple is any one of Pt, Au, Mo, Ta, an alloy thereof, or a compound thereof.   A droplet discharge apparatus comprising the droplet discharge head according to claim 1. Forming a recess to be a nozzle hole in the silicon substrate;
Forming a thermal oxide film on the silicon substrate by thermal oxidation;
Bonding the support substrate to the recess forming surface of the silicon substrate;
Thinning the side surface opposite to the recess forming surface of the silicon substrate and opening the recess,
Forming a temperature sensor at the edge of each opened nozzle hole;
Forming a droplet protective film on the thinned surface of the silicon substrate and inside the recess;
Forming a liquid repellent film on the droplet protective film;
After a support tape is bonded to the side opposite to the recess forming surface of the silicon substrate, the support substrate is peeled off from the silicon substrate, and the liquid repellent film formed on the silicon substrate is peeled off from the support substrate From the step of hydrophilizing,
Peeling the support tape from the silicon substrate;
Exposing the wiring connection of the temperature sensor;
A method for manufacturing a nozzle substrate, comprising: In the manufacturing method of the nozzle substrate according to claim 13,
Forming the temperature sensor comprises:
Forming a second electrode by oblique sputtering or oblique deposition on the edge of each opened nozzle hole;
Forming the first electrode by oblique sputtering or oblique deposition on at least the second electrode and at the edge of each opened nozzle hole;
A method for manufacturing a nozzle substrate, comprising: