JP2005144804A - Liquid injection head and liquid injection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid injection head which can securely prevent a piezoelectric element from breaking down for a long time and also prevent the displacement of a vibrating plate from diminishing and a liquid injection device. <P>SOLUTION: In the liquid injection head comprising a flow path formation substrate 10 where a pressure generating chamber 12 communicating with a nozzle opening 21 for discharging liquid droplets is formed and the piezoelectric element 300 consisting of a lower electrode 60, a piezoelectric material layer 70 and an upper electrode 80 mounted on one direction side of the flow path formation substrate 10 through the vibrating plate, the piezoelectric element 300 is covered with an insulating film 100 having at least a first layer 101 formed of an inorganic insulating material on the piezoelectric element 300 side and a second layer 102 which is formed of a different material from the first layer 101 and on this layer 101. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, and in particular, a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is configured by a vibration plate, and a piezoelectric element is formed on the surface of the vibration plate. The present invention relates to an ink jet recording head and an ink jet recording apparatus that eject ink droplets by displacement of a piezoelectric element.

  A part of the pressure generation chamber communicating with the nozzle opening for discharging ink droplets is constituted by a vibration plate, and the vibration plate is deformed by a piezoelectric element to pressurize the ink in the pressure generation chamber to discharge ink droplets from the nozzle opening. Two types of ink jet recording heads have been put into practical use: those using a longitudinal vibration mode piezoelectric actuator that extends and contracts in the axial direction of the piezoelectric element, and those using a flexural vibration mode piezoelectric actuator.

  The former can change the volume of the pressure generation chamber by bringing the end face of the piezoelectric element into contact with the vibration plate, and it is possible to manufacture a head suitable for high-density printing, while the piezoelectric element is arranged in an array of nozzle openings. There is a problem that the manufacturing process is complicated because a difficult process of matching the pitch into a comb-like shape and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are necessary.

  On the other hand, the latter can flexibly vibrate, although a piezoelectric element can be built on the diaphragm by a relatively simple process of sticking a green sheet of piezoelectric material according to the shape of the pressure generation chamber and firing it. There is a problem that a certain amount of area is required for the use of, and high-density arrangement is difficult.

  On the other hand, in order to eliminate the disadvantages of the latter recording head, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is shaped to correspond to the pressure generating chamber by lithography. In some cases, the piezoelectric element is formed so as to be independent for each pressure generating chamber. And such a piezoelectric element has a problem that it is easily destroyed due to an external environment such as moisture. Therefore, in order to solve such a problem, the outer peripheral surface of the piezoelectric element is covered with a protective film made of an insulator, and the protective film is thinner in the area facing the upper surface of the piezoelectric element than the other areas. The thing which provided the thin film part is proposed (for example, refer patent document 1).

  However, when the protective film is formed, there is a problem that pinholes and the like are formed in the film, which reduces moisture resistance and destroys the piezoelectric element. In particular, when a pinhole or the like is formed in the thin film portion, the piezoelectric element is easily broken.

  Further, in a head provided with a protective film having a thin film portion, the piezoelectric element is covered with a protective film in order to prevent the piezoelectric element from being broken, and the displacement of the diaphragm by covering the piezoelectric element with the protective film In order to prevent the deterioration of the film, the protective film is provided with a thin film portion. The film thickness of the thin film portion is smaller than the film thickness of the other portions, so that the moisture resistance is reduced, and the piezoelectric element (piezoelectric layer) There is a problem that it may be destroyed.

  Thus, in a head in which a piezoelectric element is covered with a protective film, the amount of displacement of the diaphragm is reduced when the piezoelectric element is covered with the protective film, while the piezoelectric element is destroyed when the protective film is formed thin. Therefore, it is very difficult to solve these two problems at the same time. Such a problem exists not only in an ink jet recording head that ejects ink droplets, but also in other liquid ejecting heads that eject droplets other than ink.

  As the above-described protective film, a plurality of ink liquid chambers are provided on one side of the substrate, and a protective film for protecting electrodes provided on the inner surface of each ink liquid chamber is known (for example, patents). Reference 2). However, this protective film protects the electrodes, and is clearly different from the protective film that prevents the piezoelectric element provided in the portion not in contact with ink from being damaged by moisture.

JP 2001-260357 A (FIG. 8) Japanese Patent Laid-Open No. 07-101057 (FIG. 4)

  In view of such circumstances, the present invention provides a liquid ejecting head and a liquid ejecting apparatus that can reliably prevent destruction of a piezoelectric element over a long period of time and prevent a decrease in the displacement of a diaphragm. The issue is to provide.

According to a first aspect of the present invention for solving the above-described problem, a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for discharging droplets is formed, and a diaphragm is provided on one side of the flow path forming substrate. A liquid ejecting head comprising a lower electrode, a piezoelectric layer, and an upper electrode provided via the first electrode, wherein the piezoelectric element is made of an inorganic insulating material and is formed on the piezoelectric element side; In the liquid ejecting head, the liquid jet head is covered with an insulating film made of a material different from that of the first layer and having at least a second layer formed on the first layer.
In the first aspect, since the first layer that directly protects the piezoelectric element is made of an inorganic insulating material, destruction of the piezoelectric element due to moisture is surely prevented. In addition, since the piezoelectric element is covered with an insulating film having at least a first layer made of an inorganic insulating material and a second layer made of a material different from the first layer, pinholes are formed in each of the first layer and the second layer. Even if formed, the pinholes of the respective layers do not coincide with each other in the surface direction of the insulating film, and the deterioration (destruction) of the piezoelectric element (piezoelectric layer) due to moisture (humidity) is ensured over a long period of time. Is prevented.

According to a second aspect of the present invention, in the first aspect, at least a part of the part of the insulating film facing the upper electrode has a thickness of the first layer of the other part facing the piezoelectric element. The liquid ejecting head has a thin film portion thinner than the thickness.
In the second aspect, since at least the outer peripheral surfaces of the upper electrode and the piezoelectric layer can be reliably covered with the two insulating films, destruction of the piezoelectric element due to moisture is reliably prevented. In addition, since the thickness of at least a part of the portion facing the upper electrode of the insulating film is thinner than the thickness of the other portion facing the piezoelectric element, obstruction of driving of the piezoelectric element by the insulating film is reduced and vibration A reduction in the displacement of the plate is prevented.

According to a third aspect of the present invention, in the second aspect, a portion corresponding to the thin film portion of the first layer is removed.
In the third aspect, since the outer peripheral surfaces of the upper electrode and the piezoelectric layer can be reliably covered with the two insulating films, destruction of the piezoelectric element due to moisture is reliably prevented. In addition, since a material having a low Young's modulus (hardness) (for example, a resin) can be selected as a material for covering the upper surface of the piezoelectric element, a decrease in the displacement of the diaphragm is prevented.

A fourth aspect of the present invention is the liquid ejecting head according to any one of the first to third aspects, wherein a Young's modulus of the first layer is larger than a Young's modulus of the second layer.
In the fourth aspect, since the Young's modulus (hardness) on the surface side is smaller than the Young's modulus (hardness) on the piezoelectric element side of the insulating film, a decrease in the displacement amount of the diaphragm is prevented.

According to a fifth aspect of the present invention, in the liquid jet head according to any one of the first to fourth aspects, at least the first layer is made of an oxide.
In the fifth aspect, since the piezoelectric element is covered with the first layer made of an oxide having a low moisture permeability, destruction of the piezoelectric element due to moisture is surely prevented.

According to a sixth aspect of the present invention, in the liquid jet head according to the fifth aspect, the second layer is made of an oxide different from the first layer.
In the sixth aspect, since the piezoelectric element is covered with the insulating film having the first layer and the second layer made of the oxide having low moisture permeability, the destruction of the piezoelectric element due to moisture is surely prevented.

According to a seventh aspect of the present invention, in the liquid jet head according to the fifth or sixth aspect, the first layer is made of aluminum oxide.
In the seventh aspect, since the first layer is made of aluminum oxide having an extremely low moisture permeability among oxides, destruction of the piezoelectric element is reliably prevented.

According to an eighth aspect of the present invention, in the fifth aspect, the liquid ejecting head is characterized in that the second layer is made of a resin.
In the eighth aspect, the first layer is made of an oxide having a low moisture permeability, the destruction of the piezoelectric element is reliably prevented, and the second layer is made of a resin having a Young's modulus (hardness) smaller than that of the oxide. A decrease in the displacement of the diaphragm is prevented.

According to a ninth aspect of the present invention, in the eighth aspect, the semiconductor device further includes a protective substrate provided with a piezoelectric element holding portion that is bonded to the surface of the flow path forming substrate on the piezoelectric element side and protects the piezoelectric element. The second layer is continuously provided from a region facing the piezoelectric element to an inner surface in the piezoelectric element holding portion by injecting uncured resin from a communication hole provided on the protective substrate and communicating with the piezoelectric element holding portion. The liquid ejecting head is characterized in that the liquid ejecting head is formed.
In the ninth aspect, the second layer is relatively easily formed on the first layer by injecting a predetermined amount of uncured resin into the piezoelectric element holding portion in a state where the flow path forming substrate and the protective substrate are joined. Can be formed.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the pressure generating chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed by film formation and lithography. In the liquid ejecting head, the liquid ejecting head is formed.
In the tenth aspect, a large number of liquid jet heads having high-density nozzle openings can be manufactured relatively easily.

An eleventh aspect of the present invention is a liquid ejecting apparatus including the liquid ejecting head according to any one of the first to tenth aspects.
In the eleventh aspect, it is possible to realize a liquid ejecting apparatus that has significantly improved durability and reliability.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a cross-sectional view taken along line AA ′ of FIG. As shown in the figure, the flow path forming substrate 10 is made of a silicon single crystal substrate having a plane orientation (110) in the present embodiment, and one surface thereof is made of silicon dioxide previously formed by thermal oxidation. A 2 μm elastic film 50 is formed. A plurality of pressure generating chambers 12 are arranged in parallel in the width direction of the flow path forming substrate 10. In addition, a communication portion 13 is formed in a region outside the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10, and the communication portion 13 and each pressure generation chamber 12 are provided for each pressure generation chamber 12. Communication is made via a supply path 14. The communication part 13 constitutes a part of a reservoir that communicates with a reservoir part of a protective substrate, which will be described later, and serves as a common ink chamber for the pressure generating chambers 12. The ink supply path 14 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 13.

Further, on the opening surface side of the flow path forming substrate 10, an insulating film 51 used as a mask when forming the pressure generating chambers 12 is interposed on the side opposite to the ink supply path 14 of each pressure generating chamber 12. A nozzle plate 20 having a nozzle opening 21 communicating in the vicinity of the end is fixed through an adhesive, a heat-welded film, or the like. The nozzle plate 20 has a thickness of, for example, 0.01 to 1 mm, a linear expansion coefficient of 300 ° C. or less, for example, 2.5 to 4.5 [× 10 ⁻⁶ / ° C.], glass ceramics, silicon It consists of a single crystal substrate or non-rust steel.

  On the other hand, as described above, the elastic film 50 having a thickness of, for example, about 1.0 μm is formed on the side opposite to the opening surface of the flow path forming substrate 10. For example, an insulator film 55 having a thickness of about 0.4 μm is formed. Further, on the insulator film 55, a lower electrode film 60 having a thickness of, for example, about 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1.0 μm, and a thickness of, for example, about 0 The upper electrode film 80 of .05 μm is laminated to form the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In addition, here, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In this embodiment, the lower electrode film 60 is a common electrode of the piezoelectric element 300, and the upper electrode film 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. In either case, a piezoelectric active part is formed for each pressure generating chamber. Further, here, the piezoelectric element 300 and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In addition, since such a piezoelectric element 300 is provided in the area | region facing the pressure generation chamber 12 via a diaphragm, it does not contact the ink with which the pressure generation chamber 12 is filled directly.

  For example, in the present embodiment, as shown in FIG. 2, the lower electrode film 60 is formed in a region facing the pressure generation chamber 12 in the longitudinal direction of the pressure generation chamber 12, and corresponds to the plurality of pressure generation chambers 12. It is provided continuously in the area. Further, the lower electrode film 60 extends from the outside of the row of the pressure generating chambers 12 and between the arranged piezoelectric elements 300 to the vicinity of the communication portion 13, and the tip portion thereof extends from a drive IC 120 described later. The connection portion 60a is connected to the connection wiring 130. The piezoelectric layer 70 and the upper electrode film 80 are basically provided in a region facing the pressure generation chamber 12, but in the longitudinal direction of the pressure generation chamber 12, the piezoelectric layer 70 and the upper electrode film 80 are outside the end portion of the lower electrode film 60. The end surface of the lower electrode film 60 is covered with the piezoelectric layer 70. In the vicinity of the longitudinal end of the pressure generating chamber 12, a piezoelectric inactive portion that has the piezoelectric layer 70 but is not substantially driven is formed. A lead electrode 90 is connected to the vicinity of one end of the upper electrode film 80. In this embodiment, the lead electrode 90 extends from the piezoelectric inactive portion outside the pressure generation chamber 12 to a region facing the communication portion 13, and the tip thereof is the same as the lower electrode film 60. In addition, a connection portion 90a to which the connection wiring 130 is connected is provided. In the present embodiment, each layer constituting the piezoelectric element 300 and the lead electrode 90 are covered with the insulating film 100 except for the region facing the connection portion 60a of the lower electrode film 60 and the connection portion 90a of the lead electrode 90. This prevents the piezoelectric element 300 from being damaged by moisture (humidity) or the like.

The insulating film 100 of the present invention is composed of a plurality of layers. In this embodiment, the first layer 101 made of an inorganic insulating material and provided on the piezoelectric element 300 side is made of a material different from that of the first layer 101. And a second layer 102 provided over the first layer 101.
Here, the inorganic insulating material forming the first layer 101 is not particularly limited, and examples thereof include aluminum oxide (Al ₂ O ₃ ), tantalum pentoxide (Ta ₂ O ₅ ), and silicon dioxide (SiO ₂ ). An oxide etc. are mentioned. On the other hand, examples of the material of the second layer 102 include an oxide different from that of the first layer 101 and, for example, a urethane or acrylic resin.

  However, the first layer 101 provided on the piezoelectric element 300 side is preferably formed of an oxide having a relatively low moisture permeability, and is formed of a material having a moisture permeability that is at least lower than that of the second layer 102. It is desirable. Thereby, destruction of the piezoelectric element 300 due to moisture or the like can be more effectively prevented. The material of the first layer 101 is preferably formed of aluminum oxide having an extremely low moisture permeability among oxides. In this manner, by using aluminum oxide as the material of the first layer 101, it is possible to prevent the piezoelectric element 200 from being destroyed without increasing the thickness of the first layer 101 as compared with other oxides.

  As described above, in the present embodiment, since the first layer 101 that directly protects the piezoelectric element 200 is made of an inorganic insulating material, the destruction of the piezoelectric element 300 due to moisture can be reliably prevented. Specifically, if the material forming the first layer 101 is an organic insulating material such as a resin, moisture transmission cannot be prevented as compared with an inorganic insulating material, and the piezoelectric element 300 may be destroyed by moisture. Very expensive. However, when the first layer 101 is formed of an inorganic insulating material, the moisture permeability is extremely lower than that of the organic insulating material. Therefore, by directly protecting the piezoelectric element 300 with such a first layer 101, the piezoelectric element due to moisture is used. The destruction of 300 can be reliably prevented.

  In this embodiment, since the insulating film 100 has a two-layer structure, even when a pinhole or the like is formed in each of the first layer 101 and the second layer 102, each layer in the surface direction of the insulating film 100 is formed. The positions of the pinholes do not coincide with each other, and moisture and the like can be more reliably suppressed from passing through the insulating film 100. Furthermore, the piezoelectric element 300 can be reliably prevented from being destroyed by covering the portions where the piezoelectric element 300 is easily broken, that is, the outer peripheral surfaces of the piezoelectric layer 70 and the upper electrode film 80 with the two insulating films 100. .

  Further, when materials having different Young's moduli are used as the material of the first layer 101 and the second layer 102, it is preferable to use a material having a higher Young's modulus as the material of the first layer 101. That is, by making the layer on the diaphragm side of the insulating film 100 a layer having a relatively high hardness, a decrease in the displacement amount of the diaphragm when the piezoelectric element 300 is driven can be suppressed. In addition, since a material having a lower Young's modulus tends to have a lower moisture permeability, a material having a higher Young's modulus is used as the material for the first layer 101 from the viewpoint of preventing the piezoelectric element 300 from being damaged by moisture or the like. It is preferable to use it. For these reasons, it is particularly preferable to use aluminum oxide as the material of the first layer 101.

In this way, the first layer 101 of the insulating film 100 is formed of a material having a relatively high Young's modulus, and the second layer 102 is formed of a material having a lower Young's modulus. Can be reliably prevented, and a decrease in the displacement of the diaphragm caused by driving the piezoelectric element 300 can be suppressed.
Here, the piezoelectric element is covered with a film made of aluminum oxide, and the result of conducting an energization test on the piezoelectric element in this state is shown in Table 1 below.

  As shown in Table 1, in the case of Test Example 1 in which the piezoelectric element was covered with an aluminum oxide film having a thickness of 100 nm, the piezoelectric element was not broken even in a high humidity atmosphere. On the other hand, in Test Example 2 in which the piezoelectric element was covered with an aluminum oxide film having a thickness of 50 nm, the piezoelectric element was not destroyed in the normal humidity atmosphere, but in the high humidity atmosphere (27 ° C. and 85% Rh), the piezoelectric element was not damaged. Has been destroyed. However, when a resin film made of a urethane resin (trade name: Taffey / manufactured by Hitachi Chemical Co., Ltd.) with a thickness of about 50 μm was formed on an aluminum oxide film having a thickness of 50 nm, an energization test was performed. Even in a high humidity atmosphere, the piezoelectric element was not destroyed. Further, the Young's modulus of the resin film is smaller than the Young's modulus of the aluminum oxide film, and the influence on the displacement of the diaphragm is extremely small. Therefore, in the configuration in which the resin film is provided on the aluminum oxide film in Test Example 2, the decrease in the displacement amount of the diaphragm due to the driving of the piezoelectric element can be suppressed while securing the moisture resistance equivalent to that in Test Example 1. .

As is clear from this result, the piezoelectric element 300 is directly protected by the first layer 101 made of an inorganic insulating material, and the second layer 102 is formed on the first layer 101, whereby moisture (humidity) is formed. It is possible to reliably prevent the piezoelectric element 300 from being damaged due to the above. Further, by forming the first layer 101 with a material having a relatively high Young's modulus, such as aluminum oxide, and forming the second layer 102 with a material having a lower Young's modulus, such as a urethane-based resin, The piezoelectric element 300 can be reliably prevented from being damaged by moisture, and a decrease in the displacement of the diaphragm due to the driving of the piezoelectric element 300 can be suppressed.
In particular, if a resin is used for the material of the second layer 102, for example, when a foreign substance adheres to the stepped portion or the surface of the first layer 101, compared to the case where an oxide is used for the material of the second layer 102. Thus, even if the film thickness is small, the first layer 101 can be reliably covered, and thus there is an effect that the formation failure of the insulating film 100 can be prevented.

  A protective substrate 30 having a piezoelectric element holding portion 31 capable of securing a space that does not hinder its movement in a region facing the piezoelectric element 300 is provided on the surface of the flow path forming substrate 10 on the piezoelectric element 300 side. It is bonded via an adhesive 35 made of the above resin. Since the piezoelectric element 300 is formed in the piezoelectric element holding part 31, it is protected in a state hardly affected by the external environment. Further, the protective substrate 30 is provided with a reservoir portion 32 in a region corresponding to the communication portion 13 of the flow path forming substrate 10. In this embodiment, the reservoir portion 32 is provided along the direction in which the pressure generating chambers 12 are arranged so as to penetrate the protective substrate 30 in the thickness direction, and as described above, the communication portion of the flow path forming substrate 10. 13, a reservoir 110 serving as a common ink chamber for each pressure generating chamber 12 is configured. In addition to using an epoxy resin, the protective substrate 30 and the flow path forming substrate 10 may be bonded by, for example, metal bonding.

  Further, a connection hole 33 that penetrates the protective substrate 30 in the thickness direction is provided in a region between the piezoelectric element holding portion 31 and the reservoir portion 32 of the protective substrate 30. The connection part 60a of the electrode film 60 and the connection part 90a of the lead electrode 90 are exposed. One end of a connection wiring 130 extending from the drive IC 120 mounted on the protective substrate 30 is connected to the connection portion 60 a of the lower electrode film 60 and the connection portion 90 a of the lead electrode 90.

Examples of the material of the protective substrate 30 include glass, ceramic material, metal, resin, and the like, but it is more preferable that the protective substrate 30 be formed of substantially the same material as the thermal expansion coefficient of the flow path forming substrate 10. In the embodiment, a single crystal silicon substrate made of the same material as the flow path forming substrate 10 is used.
A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. The sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and one surface of the reservoir portion 32 is sealed by the sealing film 41. Yes. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 110 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 110 is sealed only by the flexible sealing film 41. Has been.

  In such an ink jet recording head according to this embodiment, ink is taken in from an external ink supply unit (not shown), filled with ink from the reservoir 110 to the nozzle opening 21, and then subjected to pressure according to a recording signal from the driving IC 120. By applying a voltage between each of the lower electrode film 60 and the upper electrode film 80 corresponding to the generation chamber 12, the elastic film 50, the insulator film 55, the lower electrode film 60, and the piezoelectric layer 70 are bent and deformed. The pressure in each pressure generating chamber 12 is increased, and ink droplets are ejected from the nozzle openings 21.

(Embodiment 2)
FIG. 3 is an enlarged cross-sectional view of a main part of an ink jet recording head according to Embodiment 2 of the present invention. FIG. 4 is an enlarged cross-sectional view of a main part for explaining a method for manufacturing an ink jet recording head according to Embodiment 2 of the present invention. As shown in FIGS. 3 and 4, in this embodiment, the uncured resin 102 a is made to pass through the communication hole 31 a that communicates with the piezoelectric element holding portion 31 A provided on the protective substrate 30 A joined to the flow path forming substrate 10. The second layer 102A was continuously formed from the region facing the piezoelectric element 300 to the inner surface of the piezoelectric element holding portion 31A.

  Specifically, as shown in FIG. 4, after the protective substrate 30A is bonded to the surface of the flow path forming substrate 10 on the piezoelectric element 300 side, the nozzle tube 200 is inserted into the communication hole 31a of the protective substrate 30A and the nozzle A predetermined amount of liquid urethane resin is injected as uncured resin 102a into the piezoelectric element holding portion 31A through the tube 200. Here, for example, the uncured resin 102a is injected from a region facing the piezoelectric element 300 until it contacts the inner surface of the piezoelectric element holding portion 31A. At this time, since the protective substrate 30A and the flow path forming substrate 10 are bonded by the adhesive 35, the injected uncured resin 102a does not flow out of the piezoelectric element holding portion 31A. After that, the second layer 102A is formed on the surface of the first layer 101A in the piezoelectric element holding portion 31A by performing heat treatment at a predetermined temperature. Thereby, as shown in FIG. 3, the piezoelectric element 300 is reliably covered with the insulating film 100A having the first layer 101A and the second layer 102A.

  In this way, the second layer 102A is formed by injecting a predetermined amount of uncured resin 102a into the piezoelectric element holding portion 31A in a state where the flow path forming substrate 10 and the protective substrate 30A are joined, thereby forming the second layer 102A. Since it is not necessary to pattern 102A into a predetermined shape, the second layer 102A can be formed on the first layer 101A relatively easily. In addition, the second layer 102A made of urethane resin has less influence on the displacement of the diaphragm than when aluminum oxide is used. For this reason, there is an advantage that the thickness of the second layer 102A need not be controlled with high accuracy. In addition, since the piezoelectric element 300 can be reliably covered with the insulating film 100A having the first layer 101A and the second layer 102A, the same effects as those of the first embodiment described above can be obtained.

(Embodiment 3)
FIG. 5 is an enlarged cross-sectional view of a main part of an ink jet recording head according to Embodiment 3 of the present invention. In the present embodiment, as shown in FIG. 5, the thickness of the first layer 101 </ b> B is at least part of the portion facing the upper electrode film 80 of the insulating film 100 </ b> B than the thickness of the other portion facing the piezoelectric element 300. A thin film portion 400 is also provided. Even in such a configuration, at least the outer peripheral surfaces of the piezoelectric layer 70 and the upper electrode film 80 can be reliably covered with the two insulating films 100B having the first layer 101B and the second layer 102B. ) Or the like can be prevented reliably. In addition, by providing the thin film portion 400 in the first layer 101B, the influence of the insulating film 100B on the displacement of the piezoelectric element 300 (vibrating plate) can be reduced, and a decrease in the amount of displacement of the vibrating plate can be prevented.

(Embodiment 4)
FIG. 6 is an enlarged cross-sectional view of a main part of an ink jet recording head according to Embodiment 4 of the present invention. In Embodiment 3 described above, the thin film portion 400 is provided in at least a part of the portion facing the upper electrode film 80 of the insulating film 100B. However, in the present embodiment, as shown in FIG. At least a part of the portion facing the electrode film 80 was removed to provide a removal unit 500, and the removal unit 500 was covered with the second layer 102C. Even in such a configuration, the outer peripheral surfaces of the piezoelectric layer 70 and the upper electrode film 80 can be reliably covered with the two-layer insulating film 100C having the first layer 101C and the second layer 102C, and therefore moisture (humidity). It is possible to reliably prevent the piezoelectric layer 70 from being broken due to the above. Further, by providing the removal portion 500 in the insulating film C, the influence of the insulating film 100C on the displacement of the piezoelectric element 300 (vibrating plate) can be reduced, and a decrease in the displacement amount of the vibrating plate can be prevented. Since the film thickness of the second layer 102C is formed relatively thicker than the other parts in the removal portion 500, the piezoelectric element caused by moisture permeation and pinholes in the second layer 102C corresponding to this removal part. No destruction of 300 occurs.

(Other embodiments)
As mentioned above, although each embodiment of this invention was described, this invention is not limited to embodiment mentioned above. For example, in Embodiment 1 described above, the insulating film 100 including the first layer 101 and the second layer 102 is provided. However, the present invention is not limited to this. For example, an insulating film including three or more layers may be provided. May be.
In Embodiment 1 described above, the piezoelectric element 300 is formed in the piezoelectric element holding portion 31 of the protective substrate 30. However, the present invention is not limited to this, and the piezoelectric element holding portion may not be provided. Even in this case, since the surfaces of the piezoelectric element and the lead electrode are covered with the insulating film having the first layer and the second layer, the destruction of the piezoelectric element (piezoelectric layer) due to moisture (humidity) is ensured. Can be prevented.
Furthermore, in the first embodiment described above, the insulating film is formed except for the layers constituting the piezoelectric element 300 and the pattern region of the lead electrode 90 except for the region facing the connection part 60a of the lower electrode film 60 and the connection part 90a of the lead electrode 90. However, the present invention is not limited to this, and the insulating film only needs to be provided so as to cover at least a region facing the piezoelectric element.

  Further, the ink jet recording head of the above-described embodiment constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 7 is a schematic view showing an example of the ink jet recording apparatus. As shown in FIG. 7, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively. The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head of the present invention. However, the basic configuration of the liquid ejecting head is not limited to the above-described configuration. The present invention covers a wide range of liquid ejecting heads, and can naturally be applied to those ejecting liquids other than ink. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (surface emitting displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

FIG. 3 is an exploded perspective view of the recording head according to the first embodiment. 2A and 2B are a plan view and a cross-sectional view of the recording head according to the first embodiment. FIG. 6 is an enlarged cross-sectional view of a main part of a recording head according to a second embodiment. FIG. 6 is an enlarged cross-sectional view of a main part illustrating a recording head manufacturing method according to Embodiment 2. FIG. 6 is an enlarged cross-sectional view of a main part of a recording head according to a third embodiment. FIG. 6 is an enlarged cross-sectional view of a main part of a recording head according to a fourth embodiment. 1 is a schematic diagram of a recording apparatus according to an embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Piezoelectric element holding | maintenance part, 32 Reservoir part, 40 Compliance board | substrate, 50 Elastic film, 55 Insulator film, 60 Lower electrode film , 70 piezoelectric layer, 80 upper electrode film, 100 insulating film, 101 first layer, 102 second layer, 110 reservoir, 200 nozzle tube, 300 piezoelectric element

Claims (11)

A flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for discharging droplets is formed, and a lower electrode, a piezoelectric layer, and an upper electrode provided on one surface side of the flow path forming substrate via a vibration plate In a liquid ejecting head comprising the piezoelectric element,
The piezoelectric element is an insulation having at least a first layer made of an inorganic insulating material and formed on the piezoelectric element side, and a second layer made of a material different from the first layer and formed on the first layer. A liquid ejecting head, which is covered with a film. 2. The thin film portion according to claim 1, wherein a thickness of the first layer is thinner than a thickness of another portion facing the piezoelectric element in at least a portion of the insulating film facing the upper electrode. Liquid ejecting head. The liquid ejecting head according to claim 2, wherein a portion of the first layer corresponding to the thin film portion is removed. 4. The liquid ejecting head according to claim 1, wherein a Young's modulus of the first layer is larger than a Young's modulus of the second layer. The liquid ejecting head according to claim 1, wherein at least the first layer is made of an oxide. The liquid ejecting head according to claim 5, wherein the second layer is made of an oxide different from that of the first layer. The liquid ejecting head according to claim 5, wherein the first layer is made of aluminum oxide. 6. The liquid jet head according to claim 5, wherein the second layer is made of a resin. 9. The protective substrate according to claim 8, further comprising a protective substrate provided with a piezoelectric element holding portion that is bonded to the surface of the flow path forming substrate on the piezoelectric element side and protects the piezoelectric element, and the second layer includes the protection layer. An uncured resin is injected from a communication hole provided in a substrate and communicating with the piezoelectric element holding portion, and is continuously formed from a region facing the piezoelectric element to an inner surface in the piezoelectric element holding portion. Liquid ejecting head. The pressure generation chamber according to any one of claims 1 to 9, wherein the pressure generation chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed by film formation and lithography. Liquid ejecting head. A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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