JP2003094648A - Droplet discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a flow channel forming member and a diaphragm are eluted into a liquid. SOLUTION: A thin liquid resistant film 10 made of a multi-layer film of organic resin films 10a and 10b is formed on each wall surface of a pressurized liquid chamber 6, an ink supply channel 7, and a common liquid chamber 8, or the wall contacting ink in a channel forming substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet discharge head, an ink cartridge, an ink jet recording apparatus and a method for manufacturing the droplet discharge head.

[0002]

2. Description of the Related Art An ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile machine, a copying machine and a plotter, has a nozzle for ejecting ink droplets and an ink flow path (ejection chamber, which communicates with this nozzle). Also referred to as a pressure chamber, a pressurized liquid chamber, a liquid chamber, etc.) and a drive unit for pressurizing the ink in the ink flow path, and an inkjet head as a droplet discharge head is mounted. As the droplet discharge head, for example, there are a droplet discharge head that discharges a liquid resist as droplets, a droplet discharge head that discharges a DNA sample as droplets, etc., but the following description will focus on the inkjet head.

In the ink jet head, as an energy generating means for generating energy for pressurizing the ink in the ink flow passage, a piezoelectric element is used to deform a vibrating plate forming a wall surface of the ink flow passage, thereby forming a volume in the ink flow passage. Of a so-called piezo type in which ink droplets are discharged by changing the temperature (see Japanese Patent Laid-Open No. 2-51734), or pressure generated by heating ink in an ink flow path using a heating resistor to generate bubbles. A so-called bubble type (refer to Japanese Patent Laid-Open No. 61-59911) in which ink droplets are ejected by means of a vibrating plate that forms the wall surface of an ink flow path and an electrode are arranged so as to face each other, and are generated between the vibrating plate and the electrode. An electrostatic type that changes the internal volume of the ink flow path to eject ink droplets by deforming the vibrating plate by the electrostatic force that is applied (Japanese Patent Application Laid-Open No. HEI 6-26187).
No. 71882), for example.

By the way, in the ink jet recording apparatus, in order to achieve high quality recording of a color image at a high speed, in order to achieve high image quality, high density processing using a micromachine technique is used, and a material for a head constituent member is also used. ,metal,
From plastics and the like to silicon, glass, ceramics and the like, silicon has come to be used as a material particularly suitable for fine processing.

Further, in terms of color, development of ink and recording medium (medium) is mainly carried out, and optimization in terms of penetrability, color developability and color mixing prevention property when ink adheres to the recording medium. In addition, in order to improve the long-term storage stability of the printed media and the storage stability of the ink itself, the ink components,
The composition is also being developed.

In this case, the head constituent member may be dissolved in the ink by the ink depending on the combination of the ink and the material of the head constituent member. In particular, when the flow path forming member is formed of silicon, silicon is eluted into the ink and is deposited on the nozzle portion, which causes clogging of the nozzle and lowers the color developability of the ink to deteriorate the image quality. Further, in a head using a diaphragm, similarly, when a silicon thin film diaphragm is used, if the silicon forming the diaphragm is eluted, the vibration characteristics fluctuate or the vibration becomes impossible.

In this case, if it is dealt with by changing the material of the head constituent member, it becomes difficult to realize high-density processing,
In many cases, deterioration of processing accuracy also occurs. Further, the change of the material causes a drastic change in the working process and a need to devise an assembling process, resulting in a decrease in the nozzle density and a decrease in the print quality.

On the other hand, in order to adjust the ink composition, the components and composition of the ink are originally designed to have optimum penetrability and color developability for recording media in order to improve printing quality, or to improve storage stability. Since it is adjusted to, the change adjustment of the components may impair the high image quality.

Therefore, in the conventional ink jet head, an ink resistant thin film is formed on the surface of the flow path forming member which contacts the ink. For example, WO9
8/42513 discloses forming titanium, a titanium compound or aluminum oxide on the surface in contact with the ink, and JP-A-5-229118 discloses forming an oxide film on the surface in contact with the ink. JP 10-2
Japanese Patent No. 91322 discloses forming a thin film of an oxide-resistant oxide, nitride, metal or the like on the surface of a silicon oxide film.

[0010]

However, in the above-mentioned conventional ink jet head, the inorganic ink resistant film has a region where it is likely to be electrochemically dissolved depending on the pH of the ink, and the demand for the ink is severe. Prone. Specifically, for a silicon oxide film, for example, pH>
Although it dissolves in the ink of No. 9, generally, the pH of the ink having good color development is often alkaline of about 10 to 11. Therefore, in order to secure the ink resistance, the film thickness is The thickness of the inorganic film must be considerably increased, and it is often difficult to apply a thick inorganic film in terms of the process. In addition, internal stress is generated and the flow path forming member is deformed.

Further, when forming an ink resistant film, a sputtering method or a vapor deposition method is used. At this time, since the particles for forming the thin film have directionality, the structure of the flow path is changed. There is a problem that it is difficult to completely cover all the surfaces with a thin film because a shadow portion is generated and the thin film is partially thinned or is not formed at all.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a highly reliable droplet discharge head which prevents corrosion due to liquid at low cost.

[0013]

In order to solve the above-mentioned problems, a droplet discharge head according to the present invention includes a multi-layer organic resin film on a surface of a silicon member forming a liquid flow path, which is in contact with a liquid. It is configured to have a liquid resistant thin film.

Further, the droplet discharge head according to the present invention is liquid resistant including a multi-layered organic resin film on the surface of the bonding area of at least the nozzle plate forming the nozzle of the silicon member forming the liquid flow path. The structure has a thin film.

Here, in the droplet discharge head according to the present invention, the organic resin film is preferably polyimide or polypentazoxazole. Further, it is preferable that the liquid-resistant thin film on the surface of the joining region of the silicon member forming the liquid flow path and the nozzle plate forming the nozzle contains a thermoplastic polyimide film. In this case, the thermoplastic polyimide film is preferably the bottom layer or the top layer.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. An inkjet head according to a first embodiment of a droplet discharge head of the present invention will be described with reference to FIGS. 1 to 5. 1 is an exploded perspective view of the same head, FIG. 2 is a sectional view of the same head taken along the longitudinal direction of the liquid chamber, FIG. 3 is an enlarged view of the main parts of FIG. 2, and FIG. FIG. 5 is a cross-sectional explanatory view taken along the hand direction, FIG. 5 is a main-portion enlarged cross-sectional explanatory view of FIG. 4, and FIG.

This ink jet head has a flow path forming substrate (flow path forming member) 1 formed of a single crystal silicon substrate.
And a diaphragm 2 bonded to the lower surface of the flow path forming substrate 1,
A nozzle plate 3 bonded to the upper surface of the flow path forming substrate 1,
By these, a pressurized liquid chamber 6 that is a flow path (ink liquid chamber) that communicates with the nozzle 5 that ejects an ink droplet, and a common ink that supplies ink to the pressurized liquid chamber 6 through an ink supply passage 7 that serves as a fluid resistance portion. A liquid resistant thin film made of an organic resin film is formed on each wall surface of the pressurizing liquid chamber 6, the ink supply passage 7, and the common liquid chamber 8 which form the liquid chamber 8 and are the surfaces of the flow path forming substrate 1 in contact with the ink. 10
Is deposited.

Then, a laminated piezoelectric element 12 is bonded to the outer surface side (the surface opposite to the liquid chamber) of the vibration plate 2 so as to correspond to each pressurized liquid chamber 6, and the laminated piezoelectric element 12 is attached to the base substrate 13. Bonded and fixed, a spacer member 14 is bonded to the base substrate 13 around the row of the piezoelectric elements 12.

As shown in FIG. 3, the piezoelectric element 12 is composed of piezoelectric materials 15 and internal electrodes 16 alternately laminated. Here, as shown in FIG. 3, the ink in the pressurized liquid chamber 6 is pressurized by using displacement in the d33 direction as the piezoelectric direction of the piezoelectric element 12. As shown in FIG. 6, the ink in the pressurized liquid chamber 6 may be pressurized by using displacement in the d31 direction as the piezoelectric direction of the piezoelectric element 12. Through holes are formed in the base substrate 13 and the spacer member 14 to form ink supply ports 9 for supplying ink to the common liquid chamber 8 from the outside.

Further, the outer peripheral portion of the flow path forming substrate 1 and the outer peripheral portion on the lower surface side of the diaphragm 2 are adhesively bonded to a head frame 17 formed by injection molding with epoxy resin or polyphenylene sulphite. The substrate 13 is fixed to each other with an adhesive or the like at a portion not shown. Further, the FPC cable 18 is connected to the piezoelectric element 12 by solder bonding, ACF (anisotropic conductive film) bonding, or wire bonding to give a drive signal,
A drive circuit (driver IC) 1 for selectively applying a drive waveform to each piezoelectric element 12 is connected to the FPC cable 18.
9 is implemented.

Here, the flow path forming substrate 1 is processed by anisotropically etching a single crystal silicon substrate having a crystal plane orientation (110) using an alkaline etching solution such as an aqueous potassium hydroxide solution (KOH). A through hole to be the pressure liquid chamber 6, a groove to be the ink supply path 7, and a through hole to be the common liquid chamber 8 are formed. In this case, each pressurizing liquid chamber 6 is partitioned by a partition wall portion (liquid chamber spacing wall) 20.

The diaphragm 2 is formed of a nickel metal plate and is manufactured by the electroforming method. The vibrating plate 2 has a thin portion 21 for facilitating deformation and a thick portion 22 for joining with the piezoelectric element 12 at a portion corresponding to the pressurized liquid chamber 6, and the liquid chamber spacing wall 2
The thick portion 23 is also formed in the portion corresponding to 0, the flat surface side is adhesively joined to the flow path forming substrate 1, and the thick portion 23 is adhesively joined to the frame 17. A column 24 is provided between the thick portion 23 of the diaphragm 2 corresponding to the liquid chamber spacing wall 20 and the base substrate 13. The pillar portion 24 has the same structure as the piezoelectric element 12.

The nozzle plate 3 is provided with nozzles 5 having a diameter of 10 to 30 μm corresponding to the pressurized liquid chambers 6 and bonded to the flow path forming substrate 1 with an adhesive. As the nozzle plate 3, a metal such as stainless steel or nickel, a combination of metal and a resin such as a polyimide resin film, silicon, or a combination thereof can be used. Further, on the nozzle surface (surface in the ejection direction: ejection surface), a water repellent film is formed by a known method such as a plating film or a water repellent agent coating in order to ensure water repellency with respect to the ink.

In this ink jet head, all surfaces of the common liquid chamber 8, the fluid resistance portion 7, and the pressurized liquid chamber 6 that form the liquid flow path formed by the flow path forming member 1 made of silicon are in contact with the ink. , And a liquid resistance (here, ink resistance and corrosion resistance) thin film 10 formed of a multi-layered film (laminated film) of an organic resin film is formed on the surface to which the nozzle plate 3 is joined (the upper surface of the partition wall 20). is doing.

The liquid-resistant thin film 10 is composed of multiple layers (multilayers) of organic resin films 10a and 10b.
0a and 10b are preferably formed by spraying polyimide or polypentazoxazole to a thickness of 1000Å
To 50 μm, and preferably 1 μm to 10 μm in thickness, to form a film over the entire surface to form a laminate. On the other hand, when the thickness is extremely thin, pinholes are generated due to dust or the like existing on the diaphragm 2, and when it is extremely thick, the rigidity of the diaphragm 2 becomes high and the injection characteristic is improved. It is determined from the perspective of changing.

The method of forming the organic resin film is not limited to the spray method, but by applying and forming a liquid of an organic resin material by the spray method, the controllability of the film thickness is good and the flow path forming member is formed. It is possible to form a film having a substantially uniform film thickness on a member having a complicated surface shape with undulations (concavities and convexities), and the process margin is improved.

In the laminated liquid-resistant thin film 10, the lower organic resin film 10a is formed very thin in the upper part of the liquid chamber 6 made of the silicon substrate which is the portion A in FIG. By overcoating with 10b, the coverage in this area is greatly improved and becomes fully coated.

Although the liquid resistant thin film 10 is formed on the entire surface of the flow path forming substrate 1 here, at least the surface where silicon is exposed may be covered. That is,
Like the ink jet head, when the thin film diaphragm 2 is formed of a metal plate such as nickel, the liquid chamber side surface of the diaphragm 2 and the surface (upper end surface) of the partition wall 20 that is joined to the nozzle plate 3 are not necessarily liquid resistant. It is not necessary to form the conductive thin film 10.

In the ink jet head thus constructed, 20 to 50 is selectively applied to the piezoelectric element 12.
By applying the drive pulse voltage of V, the piezoelectric element 12 to which the pulse voltage is applied is laminated in the stacking direction (in the case of FIG. 3).
Is displaced to deform the vibrating plate 2 toward the nozzle 5, the ink in the pressurized liquid chamber 6 is pressurized by the volume / volume change of the pressurized liquid chamber 6, and an ink droplet is ejected (ejected) from the nozzle 5. It

Then, the liquid pressure in the pressurized liquid chamber 6 decreases as the ink droplets are discharged, and a slight negative pressure is generated in the pressurized liquid chamber 6 due to the inertia of the ink flow at this time. In this state, by turning off the voltage application to the piezoelectric element 12, the diaphragm 2 returns to its original position and the pressurized liquid chamber 6 returns to its original shape, so that a negative pressure is further generated. To do. At this time, ink is filled in the pressurized liquid chamber 6 from the ink supply port 9 through the common liquid chamber 8 and the ink supply path 7 which is a fluid resistance portion. Therefore, after the vibration of the ink meniscus surface of the nozzle 5 is attenuated and stabilized, a pulse voltage is applied to the piezoelectric element 12 to eject the ink droplet for the next ink droplet ejection.

In this ink jet head, the surface of the flow path forming substrate 1 in contact with the ink is the organic resin film 10a,
Since it is covered with the liquid resistant thin film 10 made of 10b, the elution of silicon, which is a flow path forming member, into the ink is prevented, the nozzle is not clogged, and long-term operation stability and reliability are ensured. It was confirmed that it was obtained.

Next, an ink jet head according to a second embodiment of the present invention will be described with reference to FIGS. 7 and 8. 7 is an exploded perspective view of the head, and FIG. 8 is a cross-sectional view of the head in the lateral direction of the liquid chamber. This inkjet head has a vibrating plate 42 on a flow path forming member 41 corresponding to the flow path forming substrate 1 and the nozzle plate 3 of the first embodiment.
The piezoelectric member 44 held by the holding member 43 is bonded to the vibration plate 42.

The flow path forming member 41 is made of a silicon substrate, and a groove serving as a nozzle 45 for ejecting an ink droplet by anisotropic etching, and a pressurized liquid chamber 46 communicating with the nozzle 45.
To form the ink supply path 47, which is a fluid resistance portion, and the common liquid chamber 48, which form the common liquid chamber 48.
To form an ink supply port 49 communicating with. And
The nozzle 45, the pressurizing liquid chamber 46, the fluid resistance portion 46, and the common liquid chamber 48, which are the surfaces of the flow path forming member 41 that come into contact with the ink, have a liquid-resistant thin film made of a laminated film of organic resin films 10a and 10b. 10 (not shown in FIG. 7) is deposited. The method for forming the organic resin films 10a and 10b and the film thickness are the first.
It is similar to the embodiment.

The piezoelectric member 44 has a driving portion 52 formed by alternately laminating green sheets and internal electrodes on a non-driving portion 51 formed by laminating only a plurality of green sheets made of a piezoelectric material. By grooving the drive portion 52 while reaching the drive portion 51 and leaving the non-drive portion 51, a plurality of piezoelectric elements 53 including the drive portions 52 corresponding to the respective pressurized liquid chambers 46 are formed. . This piezoelectric element 5
The tip of 3 is joined to the diaphragm 42.

In the ink jet head thus constructed, 20 to 50 is selectively applied to the piezoelectric element 53.
By applying the driving pulse voltage of V, the piezoelectric element 53 to which the pulse voltage is applied is displaced in the stacking direction to deform the vibrating plate 42, and the pressurized liquid chamber 46 is changed by the volume / volume change of the pressurized liquid chamber 46. The ink inside is pressurized, and ink droplets are ejected (ejected) from the nozzle 45 in a direction orthogonal to the displacement direction of the piezoelectric element 53. The subsequent operation is the same as that of the inkjet head of the first embodiment.

Also in this ink jet head, the surface of the flow path forming member 41 that contacts the ink and the surface that joins with the vibration plate 42 (the surface of the partition wall 50 on the vibration plate 42 side) are laminated films of the organic resin films 10a and 10b. Liquid resistant thin film 1
Since it was covered with 0, it was confirmed that the elution of silicon into the ink was prevented, the nozzle was not clogged, and long-term operation stability and reliability were obtained.

Next, a different example of the ink jet head according to the third embodiment of the present invention will be described with reference to FIGS. 9 and 10. 9 is a cross-sectional explanatory view taken along the lateral direction of the diaphragm showing one example of the head, and FIG. 10 is a cross-sectional explanatory view taken along the lateral direction of the diaphragm showing another example of the head.

In the ink jet head of each of these examples, the vibrating plate 62 is integrally formed on the flow path forming member 61, and the nozzle plate 6 is formed.
3 are joined to form a liquid flow path such as a pressurized liquid chamber 66 with which the nozzle 65 communicates. Here, the example of FIG.
A nozzle 65 penetrating 3 is formed into a side shooter type (the same type as the first embodiment), FIG.
In this example, a groove-shaped nozzle 65 communicating with the pressurized liquid chamber 66 is formed on the nozzle plate 63 to form an edge shooter type (similar type to the second embodiment).

The flow path forming member 61 is made of a silicon substrate. For example, a high-concentration P-type impurity diffusion layer such as a boron diffusion layer is formed on a single crystal silicon substrate having a crystal plane orientation (110), and an etching solution such as a KOH aqueous solution is used. By performing anisotropic etching using the boron diffusion layer, the boron diffusion layer functions as an etching stop layer to stop the etching. Therefore, the diaphragm 62 having a high precision thickness of the boron diffusion layer is integrally formed on the bottom surface of the recessed portion serving as the pressurized liquid chamber 66. It was formed in.

The surface of the flow path forming member 61 in contact with the ink (the wall surface of the pressurized liquid chamber 66 and the liquid chamber spacing wall 69).
Side wall surface and the surface of the diaphragm 62) of the organic resin film 10
The liquid resistant thin film 10 made of a laminated film of a and 10b is formed. The film forming method and film thickness of the organic resin films 10a and 10b are the same as those in the first embodiment. In this ink jet head, the diaphragm 62 is formed of a silicon thin film. Therefore, by forming the liquid resistant thin film 10 on the surface of the diaphragm 62 on the liquid chamber side, the diaphragm 62 can be prevented from being eluted and the vibration characteristics can be improved. The reliability and stability are improved by eliminating the fluctuations and vibration defects.

An intermediate layer (insulating layer) 70 is formed on the outer surface side of the diaphragm 62, and a lower electrode layer 71, a piezoelectric layer 72 and an upper electrode layer 73 corresponding to each pressurized liquid chamber 66 are formed. ing. Here, the lower electrode layer 71 is formed of platinum or a white metal element (Pb,
Rh, Ih, Ru) and other refractory metals and their alloys as the main component of the electrode material are formed by screen printing,
On the lower electrode layer 71, a piezoelectric material such as a material containing PZT as a main component is paste-processed by calcination powder and screen-printed,
Further, a silver-palladium alloy or the like to be the upper electrode layer 73 is formed by screen printing.

In the thus constructed ink jet head, by selectively applying the driving pulse voltage to the electrodes 71, 72 of the piezoelectric layer 72, the piezoelectric layer 72 to which the pulse voltage is applied is deformed and vibrates. The plate 62 is deformed, and the ink in the pressurized liquid chamber 66 is pressurized by the volume / volume change of the pressurized liquid chamber 66, and ink droplets are ejected (jetted) from the nozzle 65. The subsequent operation is the same as that of the inkjet head of the first embodiment.

Also in this ink jet head, the surface of the flow path forming member 61 including the vibrating plate 62 which contacts the ink is covered with the liquid resistant thin film 10 which is a laminated film of the organic resin films 10a and 10b. It was confirmed that elution of silicon into the ink was prevented, and there was no clogging of nozzles, fluctuations in vibration characteristics, and vibration defects, and long-term operational stability and reliability were obtained.

Next, an ink jet head according to a fourth embodiment of the present invention will be described with reference to FIGS. 11 to 14. FIG. 11 is a plan view of the head, and FIG.
11 is a cross-sectional explanatory view taken along the line BB of FIG. 11, and FIG.
14 is a cross-sectional explanatory view taken along the line CC of FIG.
It is sectional explanatory drawing which follows the line.

This ink jet head is provided on the first substrate 81 which is a flow path forming member, the second substrate 82 which is an electrode substrate provided on the lower side of the first substrate 81, and the upper side of the first substrate 81. A nozzle plate 83 which is also a third substrate, and a pressurizing liquid chamber 86, which is a liquid flow path through which a plurality of nozzles 85 for ejecting ink droplets communicate with each other, and a fluid resistance portion 87 to the pressurizing liquid chamber 86. A common liquid chamber 88 for supplying ink is formed, and the ink is supplied from an ink supply port 89 formed in the nozzle plate 83, and the common liquid chamber 88, the fluid resistance portion 87,
The liquid is ejected as droplets from the nozzle 85 through the pressurized liquid chamber 86.

On the first substrate 81, there are formed a pressurizing liquid chamber 86, a concave portion forming a vibrating plate 90 forming a bottom surface which is a wall surface of the pressurizing liquid chamber 86, a groove portion serving as a fluid resistance portion 87, and a common liquid chamber 88. To form the pressurizing liquid chamber 86, the vibration plate 90, the fluid resistance portion 87, and the common liquid chamber 88, the organic resin film 10a is formed on the entire surface of the first substrate 81 in contact with the ink.
A liquid resistant thin film 10 composed of a laminated film of 10b is formed. The film forming method and film thickness of the organic resin films 10a and 10b are the same as those in the first embodiment. Further, each pressurized liquid chamber 86 is partitioned by a partition wall 91.

As the first substrate 81, for example, a high-concentration P-type impurity diffusion layer, for example, a boron diffusion layer is formed on a single crystal silicon substrate having a crystal plane orientation (110), and is anisotropically formed by using an etching solution such as a KOH aqueous solution. By etching
Since the boron diffusion layer functions as an etching stop layer to stop the etching, the diaphragm 90 having a highly accurate thickness is formed by the boron diffusion layer.

Further, for example, it can be formed using an SOI substrate in which a silicon substrate is bonded via an oxide film. In this case as well, the diaphragm that serves as the pressurizing liquid chamber 86 is anisotropically etched using an etching solution such as a KOH aqueous solution so that the diaphragm 9 serves as an etch stop layer.
0 can be formed.

As the second substrate 82, a single crystal silicon substrate containing n-type or p-type impurity atoms of 1E14 / cm ^{3 to} 5E17 / cm ³ is used. Normally, plane orientation (100)
Although a single crystal silicon substrate of (110) or (111) can be used depending on the process, a glass substrate such as Pyrex (registered trademark) glass other than the single crystal silicon substrate, A ceramic substrate or the like can also be used.

On the second substrate 82, HTO, LT
An insulating film (silicon oxide film) 92 having a required thickness is formed by O, a thermal oxidation method, a CVD method, a sputtering method, etc., a drive electrode 95 is formed on the insulating film 92, and an insulating film 92 is further laminated. As a result, the drive electrode 95 is embedded, and the insulating film 92 is further formed.
Is processed by photolithography and etching to form a recess 94 for forming a gap 96. The diaphragm 9 and the drive electrode 95 facing the diaphragm 90
A microactuator that deforms 0 with an electrostatic force is configured. The insulating film 92 becomes the spacer portion 93 except the concave portion 94, and becomes the electrode protective film 97 of the drive electrode 95 at the bottom portion of the concave portion 94.

As the material of the drive electrode 95, a refractory metal such as titanium, tungsten, tantalum and the like, a nitride thereof, a compound thereof, a laminated structure thereof, Al,
Polysilicon or the like can be used. Although not shown, a conductive impurity layer having a conductivity type different from that of the single crystal silicon substrate may be formed to serve as a diffusion electrode. Further, the drive electrode 95 is integrally provided with an electrode pad portion 98 for mounting FPC for applying a voltage from an external drive circuit (drive IC) and wire bonding to the drive electrode 95.

On the nozzle plate 83, a plurality of nozzles 85 for ejecting ink droplets are arranged and formed in a line. The nozzle plate 83 may be made of a metal such as stainless steel or nickel, a resin such as a polyimide resin film, a silicon wafer, or a combination thereof.
Further, on the nozzle surface (surface in the ejection direction: ejection surface), a water repellent film is formed by a known method such as a plating film or a water repellent agent coating in order to ensure water repellency with respect to the ink.

In the thus constructed ink jet head, the diaphragm 90 is used as a common electrode, the electrode 95 is used as an individual electrode, and a driving voltage is applied between the diaphragm 90 and the electrode 95 to thereby form the diaphragm 90. The vibration plate 90 is deformed and displaced toward the electrode 95 side by the electrostatic force generated between the vibration plate 90 and the electrode 95, and the electric charge between the vibration plate 90 and the electrode 95 is discharged from this state (the driving voltage is set to 0) to cause the vibration plate. 90 is deformed by returning, the inner volume (volume) / pressure of the liquid chamber 86 is changed, and ink droplets are ejected from the nozzle 85.

At this time, since the surface of the first substrate 81 in contact with the ink is covered with the liquid resistant thin film 10 composed of the laminated film of the organic resin films 10a and 10b, the elution of silicon into the ink is prevented, No long-term operation stability and reliability can be obtained without nozzle clogging or vibration characteristic fluctuation.

A specific example of this electrostatic ink jet head will be described. A plane orientation (100) and a resistivity of 10 to 10 are obtained.
A 30 Ω-cm p single crystal silicon substrate is used as the second substrate 82, a silicon oxide film (insulating film) 92 is formed on the second substrate 82, and a polycrystal containing phosphorus atoms is formed on the insulating film 92. Drive electrode 9 having WSi formed on silicon
5, a silicon oxide film 92 serving as an electrode protection film 97 is formed on the drive electrode 95 to a thickness of 0.25 μm, and the same silicon oxide film 92 is used as a gap spacer part 93 to form a recess 94 having a depth of 0.2 μm. Gap 9 by forming
6 was formed. The silicon oxide film 92 (insulating protection film 97) formed on the drive electrode 95 is formed on the vibration plate 90 and the drive electrode 9.
It is for ensuring the insulation of No. 5.

Further, a part of the silicon oxide film 92 is removed by etching to form a pad portion 98 for applying a drive voltage to the drive electrode 95.

Then, the plane orientation (11
0) 1st substrate 81 made of a single crystal silicon substrate is joined, and boron impurity atoms formed by anisotropically etching the first substrate 81 with a KOH aqueous solution are added to 1E20 / cm3.
The vibrating plate 90 including the high-concentration boron diffusion layer having a film thickness of 2 μm including the above is formed, and the pressurized liquid chamber 86 and the common liquid chamber 8
8, the fluid resistance portion 97 was formed. Thereby, the diaphragm 9
0 is arranged to face the drive electrode 95 with the silicon oxide film 92 forming the gap spacer portion 93 interposed therebetween.

At this time, the partition wall 9 between the individual pressurized liquid chambers 86
1 The upper end has a chamfered shape with two corners in cross section. The surface of the first substrate 81 and the diaphragm 9 made of silicon
A polyimide film and a polypentazoxazole film as the organic resin films 10a and 10b are formed on the surface 0, the side wall surface and the upper surface of the partition wall 91 of the individual pressurizing liquid chamber, the common liquid chamber 86 and the surface of the fluid resistance portion 87 by a spray method. Filmed At this time, the film thickness of each film was 5 μm on the surface of the vibration plate 90. The polyimide film and the polypentoxoxazole film sufficiently covered the silicon, which is the structure of the partition wall 91, even at the upper end portion of the partition wall 91, and there was no exposed portion of the silicon.

Then, on the first substrate 81, a nozzle plate 83 made of a glass plate on which a liquid supply flow channel 89 and a nozzle 85 were formed was bonded by sandblasting.

In this electrostatic ink jet head, the vibrating plate 90 was electrically grounded, and a driving voltage was applied to the driving electrode 95 via the electrode 98 to drive at a constant frequency. When a voltage was applied, an electrostatic attractive force worked between the vibration plate 90 and the drive electrode 95, and the vibration plate 90 was sufficiently drawn to the drive electrode 95 side by the electrostatic attraction force. As a result, the individual liquid chamber 86 was sufficiently pulled, and the liquid was supplied from the common liquid chamber 88 to the individual liquid chamber 86 through the flow path 89 for supplying the liquid. The diaphragm 90 returns to its original position due to the rigidity of Si corresponding to the frequency of the drive voltage, and at this time, the individual liquid chamber 86 is pressurized and the nozzle 8
After 5, the droplet was stably discharged.

As a result of a reliability test with a liquid in this state, it was confirmed that the partition wall 91 was not damaged as a result of the polyimide film being sufficiently covered on the upper part of the partition wall 91 of the individual liquid chamber.

Next, an ink jet head according to a fifth embodiment of the present invention will be described with reference to FIGS. 15 is an external perspective view of the same head, FIG. 16 is an exploded perspective view of the same head, FIG. 17 is a perspective view of a flow path forming substrate of the same head, and FIG. 18 is along the nozzle arrangement direction of the same head. FIG.

This ink jet head is provided with a first substrate 121 which is a flow path forming member and a second substrate 122 which is a heating element substrate provided on the lower side of the first substrate 121, and ejects ink droplets by these. A plurality of nozzles 125, and a pressurized liquid chamber flow path 12 that is a liquid flow path communicating with the nozzles 125.
6, a common liquid chamber flow channel 128 for supplying ink to the pressurized liquid chamber flow channel 126, etc. is formed, and the ink is supplied from the ink supply port 129 formed on the first substrate 121, and the common liquid chamber flow channel 128, The liquid is ejected from the nozzle 125 as droplets through the pressurized liquid chamber flow path 126.

The first substrate 121 is made of a silicon substrate,
By etching, the nozzle 125 and the pressurized liquid chamber flow path 12
6 and a recess serving as the common liquid chamber flow channel 128 are formed, and the entire surface including the surface of the first silicon substrate 121, which is in contact with the ink on the second substrate 122 side, is formed of a laminated film of organic resin films 10a and 10b. The liquid thin film 10 is formed (FIG. 17).
(Not shown). The film forming method and film thickness of the organic resin films 10a and 10b are the same as those in the first embodiment.

On the second substrate 122, a heating resistor (electrothermal conversion element) 131, a common electrode 132 for applying a voltage to the heating resistor 131, and an individual electrode 133 are formed.

In the thus constructed ink jet head, the heating resistor 131 generates heat by selectively applying a driving voltage to the individual electrode 133, and a pressure change occurs in the ink in the pressurized liquid chamber flow channel 126. Then, an ink droplet is ejected from the nozzle 125 due to this pressure change in the ink.

At this time, since the surface of the first substrate 121 in contact with the ink is covered with the liquid resistant thin film 10 composed of the laminated film of the organic resin films 10a and 10b, the elution of silicon into the ink is prevented, No long-term operation stability and reliability can be obtained without nozzle clogging.

Next, an ink jet head according to a sixth embodiment of the present invention will be described with reference to FIGS. 19 and 20. 19 is a cross-sectional explanatory view of the same head as the inkjet head of the first embodiment taken along the longitudinal direction of the diaphragm, and FIG. 20 is an enlarged cross-sectional explanatory view of essential parts taken along the single direction of the diaphragm of the same head.

In this embodiment, the nozzle plate 3 and all the surfaces of the flow path forming member 1 made of silicon in contact with the liquid.
On the surface to which is bonded, an organic resin film (liquid-resistant thin film) 151 having a corrosion resistance to a liquid, preferably polyimide or polypentazoxazole is formed by a spray method to a thickness of 1000Å to 50 μm, and particularly preferably. 1 μm to 10
The film is formed to a thickness of μm. On the other hand, when the thickness is extremely thin, pinholes are generated due to dust or the like existing on the diaphragm 2, and when it is extremely thick, the rigidity of the diaphragm 2 becomes high and the injection characteristic is improved. It is determined from the perspective of changing.

Further, an organic resin film 152 having a corrosion resistance to the liquid is laminated on the organic resin film 151 including the upper surface of the partition wall 20 which is a bonding region between the nozzle plate 3 and the first substrate 1. The film is being formed. The organic resin film 152 to be laminated is polyimide, and preferably thermoplastic polyimide.

In the laminated organic resin film, the lower organic resin film 151 is formed very thin on the upper side wall surface of the partition wall 20 of the silicon liquid chamber which is the F portion in FIG. 20, but it is a thermoplastic organic resin film. Since the area 151 is preferably overcoated with a polyimide film, the area F can be sufficiently covered. As a result, it was confirmed that the filling liquid did not damage the partition wall 20 made of silicon.

Next, an ink jet head according to the seventh embodiment of the present invention will be described with reference to FIGS. 21 and 22. 21 is a cross-sectional explanatory view of the same head as the ink jet head of the first embodiment taken along the longitudinal direction of the diaphragm, and FIG. 22 is an enlarged cross-sectional explanatory view of essential parts taken along the direction of the vibrating plate of the same head.

In this embodiment, on the upper surface of the partition wall 20 of the flow path forming member 1 made of silicon, which is joined to the nozzle plate 3, the organic resin film 152 having a corrosion resistance against the liquid,
Preferably, a thermoplastic polyimide film is formed.

On all the surfaces of the flow path forming member 1 in contact with the liquid and the surface of the organic resin film 152, an organic resin film (liquid resistant thin film) 151 having corrosion resistance to the liquid, preferably polyimide. Alternatively, polypentazoxazole is formed by a spray method to a film thickness of 1000Å to 50 μm, particularly preferably 1 μm to 10 μm. On the other hand, when the thickness is extremely thin, pinholes are generated due to dust or the like existing on the diaphragm 2, and when it is extremely thick, the rigidity of the diaphragm 2 becomes high and the injection characteristic is improved. It is determined from the perspective of changing.

In the organic resin film laminated in the area where the flow path forming member 1 and the nozzle plate 3 are laminated in this way, the thermoplastic polyimide 152 of the lower layer is deformed at the end portion during curing, and the individual liquid chamber partition walls are deformed. 20 to cover the upper end. Further, by overcoating with the organic resin film 151, preferably polyimide or polybenzoxazole, the region G in FIG. 22 is sufficiently covered.
As a result, it was confirmed that the filling liquid did not damage the partition wall 20.

Next, the ink cartridge according to the present invention will be described with reference to the perspective explanatory view of FIG. This ink cartridge 210 has an inkjet head 212 according to any one of the above-described embodiments having nozzles 211 and the like.
And an ink tank 213 that supplies ink to the inkjet head 212 are integrated.

As described above, in the case of the head integrated with the ink tank, the defect of the head immediately leads to the defect of the entire ink cartridge. Therefore, the defect in which the head constituent members are corroded by the ink is reduced, and the defect of the head integrated ink cartridge is reduced. Improves reliability.

Next, an example of an ink jet recording apparatus equipped with an ink jet head which is a droplet discharge head according to the present invention will be described with reference to FIGS. 24 and 25. 24 is a perspective explanatory view of the same recording apparatus, and FIG. 25 is a side view of a mechanical portion of the same recording apparatus.

In this ink jet recording apparatus, a carriage movable in the main scanning direction is provided inside the recording apparatus main body 281, a recording head comprising an ink jet head embodying the present invention mounted on the carriage, and an ink cartridge for supplying ink to the recording head. A printing mechanism unit 282 and the like configured by, for example, are housed, and a paper feed cassette (or a paper feed tray) 284 capable of stacking a large number of papers 283 from the front side can be freely inserted into and removed from the lower portion of the apparatus main body 281. Can be mounted on the paper feed tray 285, and the manual feed tray 285 for manually feeding the paper 283 can be opened, and the paper fed from the paper feed cassette 284 or the manual feed tray 285 (ink drops adhere It means the thing and is not limited to paper.) 283 is taken in, and the printing mechanism unit 282 is used. After recording the image of a main and discharged to the discharge tray 286 mounted on the rear side.

The printing mechanism 282 slides the carriage 293 in the main scanning direction (the direction perpendicular to the paper surface in FIG. 25) by the main guide rod 291 and the sub guide rod 292, which are guide members which are horizontally mounted on the left and right side plates (not shown). The carriage 293 is freely held, and yellow (Y), cyan (C),
A head 294 including an inkjet head according to the present invention that ejects ink droplets of magenta (M) and black (Bk) colors is arranged by arranging a plurality of ink ejection ports (nozzles) in a direction intersecting the main scanning direction. It is installed with the discharge direction facing downward. Also, each ink tank 295 for supplying each color ink to the head 294 is replaceably mounted on the carriage 293.

The ink tank 295 has an atmosphere port communicating with the atmosphere above, a supply port supplying ink to the ink jet head below, and a porous body filled with ink inside. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of. Further, here, as recording heads, heads 29 of respective colors are used.
However, one head having nozzles for ejecting ink droplets of each color may be used. As the inkjet head mounted as the recording head, various inkjet heads as described in the above embodiments can be used.

Here, the carriage 293 is slidably fitted to the main guide rod 291 at the rear side (downstream side in the sheet conveying direction) and slidably fitted to the sub guide rod 292 at the front side (upstream side in the sheet conveying direction). It is placed in. Then, in order to move and scan the carriage 293 in the main scanning direction, the timing belt 300 is stretched between the driving pulley 298 and the driven pulley 299 which are rotationally driven by the main scanning motor 297, and the timing belt 300 is mounted on the carriage 293. The carriage 293 is reciprocally driven by the forward and reverse rotations of the main scanning motor 297.

On the other hand, in order to convey the paper 283 set in the paper feed cassette 284 to the lower side of the head 294, the paper feed roller 301 and the friction pad 302 for separately feeding the paper 283 from the paper feed cassette 284, and the paper 28.
Guide member 303 for guiding the sheet 3 and the fed paper 28
A conveyance roller 304 that reverses and conveys 3 is provided, a conveyance roller 305 that is pressed against the peripheral surface of the conveyance roller 304, and a leading end roller 306 that defines the delivery angle of the paper 283 from the conveyance roller 304. Conveyor roller 3
Reference numeral 04 is rotationally driven by a sub-scanning motor 307 via a gear train.

A print receiving member 309, which is a paper guide member for guiding the paper 283 sent out from the conveying roller 304 below the recording head 294 in correspondence with the movement range of the carriage 293 in the main scanning direction, is provided. There is. A transport roller 311 and a spur 312 that are driven to rotate in order to send out the paper 283 in the paper discharge direction are provided on the downstream side of the print receiving member 309 in the paper transport direction, and further, the paper 283 is sent to the paper discharge tray 286. Roller 313 and spur 3
14 and guide members 315 and 316 that form a paper discharge path.
And are arranged.

At the time of recording, by driving the recording head 294 according to the image signal while moving the carriage 293, ink is ejected onto the stopped paper 283 to record one line, and the paper 283 is moved by a predetermined amount. After transportation, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 283 has reached the recording area, the recording operation is ended and the paper 283 is ejected.

A recovery device 317 for recovering the ejection failure of the head 294 is arranged at a position outside the recording area on the right end side of the carriage 293 in the moving direction. The recovery device 317 has a cap means, a suction means, and a cleaning means. The carriage 293 is moved to the recovery device 317 side during printing standby, and the head 294 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying.
Also, by ejecting ink that is not related to recording during recording, etc., the ink viscosity of all ejection ports is made constant,
Maintains stable discharge performance.

When a discharge failure occurs, the discharge port (nozzle) of the head 294 is sealed with a capping means,
Bubbles and the like are sucked out together with the ink from the discharge port by the suction means through the tube, and the ink and dust adhering to the surface of the discharge port are removed by the cleaning means to recover the discharge failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed in the lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

As described above, since this ink jet recording apparatus is equipped with the ink jet head embodying the present invention, the flow path forming member is prevented from being corroded by ink, and there is no ink droplet ejection failure for a long period of time. Stable ink droplet ejection characteristics are obtained, and the image quality is improved.

In the above embodiment, the droplet discharge head according to the present invention is applied to the ink jet head. However, a droplet discharge head for discharging a droplet of liquid other than ink, for example, a liquid resist for patterning, a gene. It can also be applied to a droplet discharge head that discharges an analysis sample.

[0090]

As described above, according to the droplet discharge head of the present invention, the liquid-resistant thin film including a plurality of organic resin films on the surface of the silicon member forming the liquid flow path, which is in contact with the liquid. Therefore, the corrosion of the silicon member is eliminated and reliability is improved at low cost.

Further, according to the droplet discharge head of the present invention, the silicon member forming the liquid flow path has at least the bonding region with the nozzle plate forming the nozzle, the surface of the bonding region including the multi-layered organic resin film. Since the configuration has the liquid thin film, the corrosion of the silicon member is eliminated at low cost and the reliability is improved.

Here, in the droplet discharge head according to the present invention, since the organic resin film is polyimide or polypentazoxazole, the corrosion resistance is excellent regardless of the type of liquid, and the film thickness is easily adjusted. Can be formed thick, and pinhole defects caused by dust or the like can be prevented from occurring, further improving reliability.

Since the liquid-resistant thin film on the surface of the joining region of the silicon member forming the liquid flow path and the nozzle plate forming the nozzle contains the thermoplastic polyimide film, not only the corrosion resistance is excellent, Excellent coverage of the upper part of the liquid chamber, improved adhesion strength with the nozzle plate, and higher reliability. In this case, since the thermoplastic polyimide film is the lowermost layer or the uppermost layer, not only the corrosion resistance is excellent, but also the coating property of the sequentially formed organic resin film is improved, so that the reliability is increased.

[Brief description of drawings]

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

FIG. 2 is an explanatory cross-sectional view of the same head taken along the longitudinal direction of the liquid chamber.

FIG. 3 is an enlarged explanatory view of a main part of FIG.

FIG. 4 is an explanatory cross-sectional view taken along the lateral direction of the liquid chamber of the head.

FIG. 5 is an enlarged explanatory view of a main part of FIG.

FIG. 6 is an enlarged cross-sectional explanatory view of main parts for explaining a different example of the piezoelectric element of the head.

FIG. 7 is an exploded perspective view illustrating an inkjet head according to a second embodiment of the invention.

FIG. 8 is a cross-sectional explanatory view of the same head taken along the lateral direction of the liquid chamber.

FIG. 9 is an explanatory sectional view taken along the lateral direction of the diaphragm showing an example of the inkjet head according to the third embodiment of the present invention.

FIG. 10 is an explanatory sectional view taken along the lateral direction of the diaphragm showing another example of the inkjet head according to the embodiment.

FIG. 11 is an explanatory plan view of an inkjet head according to a fourth embodiment of the present invention.

12 is a cross-sectional explanatory view taken along the line BB of FIG.

13 is a cross-sectional explanatory view taken along the line CC of FIG.

14 is a cross-sectional explanatory view taken along the line DD of FIG.

FIG. 15 is an external perspective explanatory view of an inkjet head according to a fifth embodiment of the present invention.

FIG. 16 is an exploded perspective view of the head.

FIG. 17 is a perspective explanatory view of a flow path forming substrate of the head.

FIG. 18 is an explanatory cross-sectional view of the same head taken along the nozzle arrangement direction.

FIG. 19 is an explanatory cross-sectional view taken along the longitudinal direction of the diaphragm of the inkjet head according to the sixth embodiment of the present invention.

FIG. 20 is an enlarged cross-sectional explanatory view of a main part of the same head taken along the lateral direction of the diaphragm.

FIG. 21 is a cross-sectional explanatory view taken along the longitudinal direction of the diaphragm of the inkjet head according to the seventh embodiment of the present invention.

FIG. 22 is an enlarged cross-sectional explanatory view of a main part of the same head taken along the lateral direction of the diaphragm.

FIG. 23 is a perspective explanatory view of an ink cartridge integrally formed with a droplet discharge head according to the present invention.

FIG. 24 is an explanatory perspective view showing an example of an inkjet recording apparatus equipped with a droplet discharge head according to the present invention.

FIG. 25 is a side view for explaining a mechanism section of the recording apparatus.

[Explanation of Codes] 1 ... Flow path forming substrate, 2 ... Vibration plate, 3 ... Nozzle plate, 5 ... Nozzle, 6 ... Pressurized liquid chamber, 7 ... Ink supply passage, 8 ... Common liquid chamber, 9 ... Ink supply port 10 ... Liquid resistant thin film, 10a, 1
0b, 151, 152 ... Organic resin film, 12 ... Piezoelectric element,
13 ... Base substrate, 17 ... Head frame, 20 ... Partition wall, 41 ... Flow path forming member, 42 ... Vibration plate, 43 ... Holding member, 44 ... Piezoelectric member, 45 ... Nozzle, 46 ... Pressurized liquid chamber,
47 ... Ink supply passage, 48 ... Common liquid chamber, 49 ... Ink supply port, 50 ... Partition wall, 53 ... Piezoelectric element, 61 ... Flow path forming member, 62 ... Vibrating plate, 63 ... Nozzle plate, 66 ... Pressurized liquid chamber ,
72 ... Piezoelectric layer, 81 ... First substrate (flow path forming member), 82
... Second substrate, 83 ... Nozzle plate, 85 ... Nozzle, 86 ... Pressurized liquid chamber, 87 ... Ink supply passage, 88 ... Common liquid chamber, 89 ...
Ink supply port, 90 ... Vibration plate, 91 ... Partition wall, 95 ... Drive electrode, 96 ... Gap.

Continued front page    (72) Inventor Kaihei Isshiki             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2C057 AF70 AF72 AG29 AG47 AG54                       AP34 AP57 AQ02 AQ03 BA03                       BA14 BA15

Claims (6)

[Claims] 1. In a liquid drop ejection head for pressurizing a liquid in a liquid flow path communicating with a nozzle to eject a liquid drop from the nozzle, a multi-layer is formed on a surface of a silicon member forming the liquid flow path in contact with the liquid. And a liquid-resistant thin film including the organic resin film according to claim 1. 2. In a liquid droplet ejection head for ejecting liquid droplets from the nozzle by pressurizing a liquid in a liquid channel communicating with the nozzle, at least the nozzle is formed in a silicon member forming the liquid channel. A droplet discharge head having a liquid-resistant thin film including a multi-layered organic resin film on a surface of a bonding region with a nozzle plate. 3. The droplet discharge head according to claim 1, wherein the organic resin film is polyimide. 4. The droplet discharge head according to claim 1, wherein the organic resin film is polypentoxoxazole. 5. The liquid-resistant thin film according to any one of claims 1 to 4, wherein a liquid-resistant thin film is formed on a surface of a joining region of a silicon member forming the liquid flow path and a nozzle plate forming the nozzle. A liquid droplet ejection head characterized in that includes a thermoplastic polyimide film. 6. The droplet discharge head according to claim 5, wherein the thermoplastic polyimide film is a lowermost layer or an uppermost layer.