JP4553130B2 - Liquid ejecting head and liquid ejecting apparatus - Google Patents

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.

  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 corresponds to the pressure generating chamber by lithography. There is one in which piezoelectric elements are formed so as to be separated into shapes and independent for each pressure generating chamber. This eliminates the need to affix the piezoelectric element to the diaphragm, and not only enables the piezoelectric element to be densely formed by a precise and simple technique called lithography, but also reduces the thickness of the piezoelectric element. There is an advantage that it can be made thin and can be driven at high speed.

  However, in such an ink jet recording head in which piezoelectric elements are arranged at high density, one electrode (common electrode) of each piezoelectric element is provided in common to a plurality of piezoelectric elements. If the ink droplets are simultaneously driven to discharge a large number of ink droplets at once, there is a problem that a voltage drop occurs, the displacement amount of the piezoelectric element becomes unstable, and the ink discharge characteristics deteriorate. Note that the electrode of the piezoelectric element formed of a thin film has a relatively high resistance value because of its thin film thickness, and this problem is particularly likely to occur.

  In order to solve such a problem, for example, a connection wiring layer electrically connected to the common electrode of the piezoelectric element is provided in a region facing the vicinity of the longitudinal end portion of the piezoelectric element, and the resistance value of the common electrode is set. There is one that is substantially reduced (for example, see Patent Document 1).

Here, the connection wiring layer is formed of a material having relatively high conductivity, for example, a metal material such as gold (Au) or aluminum (Al) in order to reduce the resistance of the common electrode. Further, the thickness is approximately the same as the thickness of the diaphragm, for example, about 1 to 3 μm. On the other hand, the diaphragm is often formed of a material having relatively low conductivity. For example, Patent Document 1 discloses a diaphragm including an elastic film made of silicon dioxide (SIO ₂ ) formed by thermally oxidizing a flow path forming substrate that is a single crystal silicon substrate.

  Further, as a method for manufacturing the connection wiring layer, a method of patterning by etching after forming a film by sputtering or vapor deposition is common. In order to obtain a film having good adhesion to the substrate by sputtering or vapor deposition, it is necessary to form the film while heating the flow path forming substrate (vibrating plate) on which the connection wiring layer is formed to about 100 to 300 ° C. There is. Furthermore, in the sputtering method, the film formation proceeds while atoms collide with the flow path forming substrate (vibrating plate). Therefore, even if the flow path forming substrate is not heated, the temperature of the flow path forming substrate (vibrating plate) is 150- It reaches 300 ° C.

  For this reason, when the connection wiring layer is formed by a sputtering method or the like, there is a problem that residual film stress acts on the vibration plate due to a difference in contraction amount when the vibration plate and the connection wiring layer are cooled. That is, the residual film stress acts on the diaphragm, so that, for example, when an external force such as pressurization during head assembly or capping when using the head is applied, the diaphragm around the connection wiring layer is relatively easily cracked. There is a problem that it ends up.

  Further, in such an ink jet recording head, for example, a reservoir is formed by a communication portion provided on the flow path forming substrate and a reservoir portion provided on the reservoir forming substrate joined to the flow path forming substrate. There is one in which ink is supplied from a reservoir to each pressure generating chamber (see, for example, Patent Document 2). In the ink jet recording head having such a configuration, the ink (moisture) in the reservoir permeates from the joint portion between the flow path forming substrate and the reservoir forming substrate, and when the ink reaches the connection wiring layer, a voltage is applied to the ink. May cause electrolysis, generating gas and foreign matter, resulting in ink droplet ejection failure. Furthermore, when the ink penetrates to the piezoelectric element, the piezoelectric element may be destroyed by the ink. Further, in the structure in which the connection wiring layer or the like is provided as described above, such a problem is particularly likely to occur because the thickness of the adhesive for joining the reservoir forming substrate becomes relatively large.

  Such a problem exists not only in an ink jet recording head that ejects ink, but also in other liquid ejecting heads that eject droplets other than ink.

JP 2004-1431 A (Claims etc.) JP 2004-216581 A (FIG. 3, page 7, etc.)

  In view of such circumstances, the present invention can stabilize the liquid ejection characteristics in a good state, and can prevent the vibration plate from being broken due to stress concentration and the piezoelectric element from being broken due to moisture. It is an object to provide an injection device.

A first aspect of the present invention that solves the above problems includes a flow path forming substrate that includes a pressure generation chamber that communicates with a nozzle opening and a communication portion that communicates with the pressure generation chamber via a supply path. A piezoelectric element comprising 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, and the communicating portion joined to the surface of the flow path forming substrate on the piezoelectric element side A reservoir forming substrate having a reservoir portion that communicates with the lower electrode and the upper electrode in an area corresponding to the supply path at least on the diaphragm in an area to which the reservoir forming substrate is joined. Is a laminated electrode that is composed of different layers and is electrically connected to the lower electrode, the linear expansion coefficient of which is larger than that of the diaphragm and smaller than that of the laminated electrode. Along the parallel direction A discontinuous stack that is discontinuous with the stacked electrode is provided in the region on the side of the communication portion of the stacked electrode that extends from the region corresponding to the stacked electrode via the stress relaxation layer. An electrode is provided in parallel with the laminated electrode.
In the first aspect, by providing the laminated electrode, the resistance value of the lower electrode film, which is the common electrode of the piezoelectric element, is substantially reduced, so that the occurrence of crosstalk or the like is suppressed and stable ejection characteristics are obtained. It is done. Further, by providing the stress relaxation layer, the stress concentration on the diaphragm due to the stress of the laminated electrode or the like is suppressed, and the diaphragm is prevented from being destroyed due to the stress concentration. Furthermore, since the reservoir forming substrate and the flow path forming substrate can be satisfactorily bonded by providing the discontinuous laminated electrode, the piezoelectric element is destroyed by the liquid that has permeated between these substrates from the reservoir portion. Can be prevented.

According to a second aspect of the invention, in the liquid jet head according to the first aspect, the supply path is provided through the flow path forming substrate.
In the second aspect, the diaphragm in the region corresponding to the supply path is likely to be cracked, but by providing the stress relaxation layer, the diaphragm in such a region can be prevented from being broken.

According to a third aspect of the present invention, in the first or second aspect, the laminated electrode and the discontinuous laminated electrode are insulated from each other.
In the third aspect, voltage application to the ink can be more reliably suppressed.

According to a fourth aspect of the present invention, in the liquid jet head according to any one of the first to third aspects, the stress relaxation layer is made of a ceramic material.
In the fourth aspect, the stress concentration on the diaphragm can be suppressed more reliably.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the stress relaxation layer includes the same layer as the piezoelectric layer constituting the piezoelectric element, and constitutes the piezoelectric element. The liquid ejecting head is separated from the piezoelectric layer.
In the fifth aspect, the stress relaxation layer can be formed relatively easily by the same process as that of the piezoelectric element, and the stress propagation when the piezoelectric element is deformed can be effectively suppressed.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the thickness of the stress relaxation layer is equal to or greater than the thickness of the multilayer electrode. It is in.
In the sixth aspect, the stress generated in the diaphragm and the laminated electrode is more reliably relaxed by the stress relaxation layer.

According to a seventh aspect of the present invention, in the liquid ejecting head according to any one of the first to sixth aspects, the reservoir forming substrate includes a piezoelectric element holding portion that protects the piezoelectric element.
In the seventh aspect, it is possible to more reliably prevent the destruction of the piezoelectric element due to moisture.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the flow path forming substrate is formed of a silicon single crystal substrate, and the diaphragm is formed on a surface of the flow path forming substrate. The liquid ejecting head includes at least an elastic film made of silicon.
In the eighth aspect, cracks due to stress concentration are particularly likely to occur in the elastic film made of silicon dioxide. However, by providing a stress relaxation layer, it is possible to prevent cracks occurring in the elastic film.

A ninth aspect of the present invention is a liquid ejecting apparatus including the liquid ejecting head according to any one of the first to eighth aspects.
In the ninth aspect, a liquid ejecting apparatus with improved durability and reliability can be realized.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, FIG. 2 is a plan view of FIG. 1 and a cross-sectional view taken along line AA ′, and FIG. FIG. In this embodiment, the flow path forming substrate 10 is composed of a silicon single crystal substrate having a plane orientation (110), and as shown in the drawing, one surface thereof is composed of silicon dioxide and has an elastic film thickness of 0.5 to 2 μm. 50 is formed. A plurality of pressure generating chambers 12 are arranged in parallel along 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 generating chamber 12 of the flow path forming substrate 10. The communication portion 13 and each pressure generation chamber 12 communicate with each other via an ink communication passage 14 formed with substantially the same width as the pressure generation chamber 12 and an ink supply passage 15 formed with a width narrower than the pressure generation chamber 12. Has been. The communication portion 13 communicates with a reservoir portion of a reservoir forming substrate, which will be described later, and constitutes a part of a reservoir that serves as a common ink chamber for the pressure generation chambers 12. The ink supply path 15 keeps the flow path resistance of the ink flowing from the ink communication path 14 into the pressure generation chamber 12 constant.

On the opening surface side of the flow path forming substrate 10, an end opposite to the ink supply path 15 of each pressure generation chamber 12 is provided via a mask film 51 used as an etching mask when forming the pressure generation chamber 12. A nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the portion is fixed through an adhesive, a heat welding 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, and a glass ceramic or silicon single crystal of, for example, 2.5 to 20 [× 10 ⁻⁶ / ° C.]. It consists of a substrate or stainless 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. An insulator film 55 made of zirconium (ZrO ₂ ) and having a thickness of, for example, about 0.4 μm is formed. Further, on the insulator film 55, the lower electrode film 60 made of platinum (Pt) and iridium (Ir) and having a thickness of about 0.2 μm, for example, and lead zirconate titanate (PZT) are used. For example, a piezoelectric layer 70 having a thickness of about 1.0 μm and an upper electrode film 80 made of iridium (Ir) and having a thickness of about 0.05 μm, for example, are laminated by a process described later to form the piezoelectric element 300. It is composed.

As a material of the piezoelectric layer 70, for example, a relaxor ferroelectric material in which a metal such as niobium, nickel, magnesium, bismuth or yttrium is added to a ferroelectric piezoelectric material such as lead zirconate titanate (PZT). Etc. may be used. The composition may be appropriately selected in consideration of the characteristics and application of the piezoelectric element. For example, PbTiO ₃ (PT), PbZrO ₃ (PZ), Pb (Zr _x Ti _1-x ) O ₃ (PZT) , Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT), Pb (Zn _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PZN-PT), Pb (Ni _{1 / 3 Nb 2/3) O 3 -PbTiO 3} (PNN-PT), Pb (In 1/2 Nb 1/2) O 3 -PbTiO 3 (PIN-PT), Pb (Sc 1/3 Ta 2/3) O ₃ -PbTiO ₃ (PST-PT), Pb (Sc _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PSN-PT), BiScO ₃ -PbTiO ₃ (BS-PT), BiYbO ₃ -PbTiO ₃ ( BY-PT Etc. The.

  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. A portion that is composed of 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. As will be described in detail later, an upper electrode lead electrode 90 is connected to each upper electrode film 80 which is an individual electrode of the piezoelectric element 300, and each piezoelectric element is connected via the upper electrode lead electrode 90. A voltage is applied to 300. The diaphragm is composed of an elastic film 50 and an insulator film 55.

  Hereinafter, the structure of the piezoelectric element 300 will be described in detail. In this embodiment, the lower electrode film 60 that is a common electrode of the piezoelectric element 300 is formed in a region facing the pressure generation chamber 12 in the longitudinal direction of the pressure generation chamber 12, and a plurality of lower electrode films 60 are arranged in the parallel direction of the pressure generation chambers 12. Are continuously provided over a region corresponding to the pressure generation chamber 12. Further, the lower electrode film 60 is extended to the vicinity of the end of the flow path forming substrate 10 in the direction in which the pressure generating chambers 12 are arranged. In the present embodiment, the plurality of arranged piezoelectric elements 300 and the upper electrode lead are provided. The electrode 90 is continuously provided around the periphery. On the other hand, the piezoelectric layer 70 and the upper electrode film 80 constituting the piezoelectric element 300 are basically provided in a region facing the pressure generating chamber 12, but in the longitudinal direction of the pressure generating chamber 12, the lower electrode The film 60 extends outward from the end of the film 60, and the end surface of the lower electrode film 60 is covered with the piezoelectric layer 70.

  Further, each layer constituting such a piezoelectric element 300 is covered with a first insulating film 100 made of an inorganic insulating material, and the upper electrode lead electrode 90 is connected to each of the first insulating film 100 via the first insulating film 100. The upper electrode film 80 of the piezoelectric element 300 is connected. Specifically, the upper electrode lead electrode 90 includes a first lead electrode 91 connected to the upper electrode film 80 and a second lead electrode 94 connected to the first lead electrode 91 in the present embodiment. It consists of Then, the first lead electrode 91 is extended on the first insulating film 100, and the vicinity of one end thereof is connected to the upper electrode film 80 through the contact hole 101 formed in the first insulating film 100. Has been. Each layer constituting the first lead electrode 91 and the piezoelectric element 300 is further covered with a second insulating film 110 formed of an inorganic insulating material similar to that of the first insulating film 100. The second lead electrode 94 constituting the upper electrode lead electrode 90 extends on the second insulating film 110, and one end of the second lead electrode 94 passes through a contact hole 111 formed in the second insulating film 110. The other end of the first lead electrode 91 is connected. The vicinity of the other end of the second lead electrode 94 is electrically connected to a drive IC mounted on a reservoir forming substrate 30 described later.

Here, the first lead electrode 91 includes, for example, an adhesion layer 92 formed of nickel (Ni), chromium (Cr), titanium (Ti), copper (Cu), titanium tungsten (TiW), and the like, The metal layer 93 is made of gold (Au), aluminum (Al), or the like. In the present embodiment, the adhesion layer 92 constituting the first lead electrode 91 is made of titanium tungsten (TiW), the metal layer 93 is made of aluminum (Al), and the thickness thereof is about 1 μm. Similar to the first lead electrode 91, the second lead electrode 94 includes an adhesion layer 95 and a metal layer 96. For example, in this embodiment, the adhesion layer 95 constituting the second lead electrode 94 is made of nickel chrome (NiCr), the metal layer 96 is made of gold (Au), and the thickness thereof is about 1 μm. The material of the first and second insulating films 100 and 110 is not particularly limited as long as it is an inorganic insulating material, and examples thereof include aluminum oxide (AlO _x ) and tantalum oxide (TaO _x ). An inorganic amorphous material such as aluminum oxide (Al ₂ O ₃ ) is preferably used.

  In the present embodiment, the elastic film 50 and the insulator film 55 in the region corresponding to the opening peripheral edge of the communication portion 13 are also formed of the adhesion layer 95 and the metal layer 96 that constitute the second lead electrode 94. However, the discontinuous metal layer 97 discontinuous with the second lead electrode 94 remains. The discontinuous metal layer 97 is formed so as to cover the penetrating portion 52 formed in the elastic film 50 and the insulator film 55, and is etched when the flow path forming substrate 10 is anisotropically etched to form the communicating portion 13. Functions as a stop layer. And after forming the communication part 13, the discontinuous metal layer 97 of the area | region facing the penetration part 52 is removed, As a result, the discontinuous metal layer 97 remains in the area | region corresponding to the opening peripheral part of the communication part 13. .

  Further, outside the region corresponding to the pressure generation chambers 12 arranged side by side, a layer different from the lower electrode film 60 and the upper electrode film 80, in the present embodiment, the same layer (adhesion layer) as the first lead electrode 91. 92 and a metal layer 93) are provided, and are electrically connected to the lower electrode film 60. In the present embodiment, the first laminated electrode 140 is formed on the lower electrode film 60, but the present invention is not limited to this, and the first laminated electrode 140 and the lower electrode film 60 are electrically connected. If so, the lower electrode film 60 does not need to be provided below the first stacked electrode 140. Further, in the region between the piezoelectric elements 300 arranged in parallel, for example, the lower electrode lead electrode 98 continuous from the first laminated electrode 140 at a ratio of about one for ten piezoelectric elements 300. Is provided. That is, the lower electrode lead-out electrode 98 is composed of the adhesion layer 92 and the metal layer 93 that constitute the first lead electrode 91. The lower electrode lead electrode 98 extends from the first laminated electrode 140 along the lead direction of the upper electrode lead electrode 90, and is connected via a contact hole 103 provided in the first insulating film 100. The lower electrode film 60 is connected to the region corresponding to the pressure generation chamber 12. The adhesion layer 92 constituting the lower electrode lead-out electrode 98 and the like is provided to prevent the metal layer 93 made of aluminum (Al) and the lower electrode film 60 from reacting and interdiffusion.

  In such a configuration, the resistance value of the lower electrode film 60, which is a common electrode of the piezoelectric element 300, is substantially reduced by the first laminated electrode 140. Therefore, even if a large number of piezoelectric elements 300 are driven simultaneously, the voltage drop does not occur. Occurrence can be prevented. In particular, since the plurality of lower electrode lead-out electrodes 98 are continuously formed from the first laminated electrode 140, the occurrence of a voltage drop is more reliably prevented, and the ink ejection characteristics are always good and stable. Obtainable.

  In addition, a stress relaxation layer 150 made of a material having a linear expansion coefficient larger than that of the diaphragm and smaller than that of the first multilayer electrode 140 is provided between the first laminated electrode 140 and the diaphragm. Yes. The stress relaxation layer 150 only needs to be provided in a region corresponding to at least the end portion of the first multilayer electrode 140. For example, in the present embodiment, the stress relaxation layer 150 includes the stress relaxation layer 150 of the first multilayer electrode 140. On the lower side, it is provided continuously over a region corresponding to the entire surface.

  The material of the stress relaxation layer 150 is not particularly limited as long as the material has a linear expansion coefficient larger than that of the diaphragm and smaller than that of the first laminated electrode 140. For example, when the diaphragm is configured by a plurality of layers as in the present embodiment, the material of the stress relaxation layer 150 is larger than the one having the smallest linear expansion coefficient among these layers and the first A material smaller than that of the laminated electrode 140 may be used, but it is preferable that the material has a linear expansion coefficient larger than that of the entire diaphragm. Specifically, a ceramic material or the like is suitably used as the material of the stress relaxation layer 150. For example, in this embodiment, the same layer as the piezoelectric layer 70 constituting the piezoelectric element 300, that is, lead zirconate titanate. The stress relaxation layer 150 is formed of (PZT).

  Then, by providing the stress relaxation layer 150 between the first laminated electrode 140 and the diaphragm in this way, the surroundings of the first laminated electrode 140 due to the stress of the diaphragm and the first laminated electrode 140 are provided. Can be prevented, in particular, the elastic film 50 can be prevented from cracking. As in the present embodiment, the ink communication path 14, the ink supply path 15, and the like are provided through the flow path forming substrate 10. Although cracks are particularly likely to occur in the plate, by providing the stress relaxation layer 150, the occurrence of cracks in the diaphragm in such a region can be reliably prevented.

  When the stress relaxation layer 150 is formed of the same layer as the piezoelectric layer 70 as in the present embodiment, the stress relaxation layer 150 is separated from the piezoelectric layer 70 constituting the piezoelectric element 300. Is desirable. This is because stress propagation when the piezoelectric element 300 is deformed can be effectively suppressed.

  Further, as shown in FIG. 3, a first laminated layer formed in a region corresponding to the supply path that connects the pressure generating chamber 12 and the communication portion 13, in this embodiment, the ink communication path 14 and the ink supply path 15. A discontinuous laminated electrode 160 that is electrically discontinuous with the first laminated electrode 140 is juxtaposed on the communication part 13 side of the electrode 140. In the present embodiment, the discontinuous laminated electrode 160 is composed of an adhesion layer 92 and a metal layer 93, similarly to the first laminated electrode 140. Furthermore, a stress relaxation layer 150 is provided between the discontinuous laminated electrode 160 and the diaphragm so as to be provided continuously from a region corresponding to the first laminated electrode 140. In this embodiment, the stress relaxation layer 150 is formed in a region corresponding to the first stacked electrode 140 and the discontinuous stacked electrode 160, but the discontinuous metal layer provided on the opening periphery of the communication portion 13. You may form continuously to the lower side of 97. Note that the lower electrode film 60 in the region below the discontinuous laminated electrode 160 is preferably electrically separated from the lower electrode film 60 constituting the piezoelectric element 300.

  A reservoir forming substrate 30 having a reservoir portion 31 in a region corresponding to the communication portion 13 of the flow path forming substrate 10 is bonded to the surface of the flow path forming substrate 10 on the piezoelectric element 300 side. In the present embodiment, the reservoir portion 31 is provided along the direction in which the pressure generating chambers 12 are arranged so as to penetrate the reservoir forming substrate 30 in the thickness direction. The reservoir 120 is configured to communicate with the portion 13 and the penetrating portion 52 and serve as a common ink chamber for the pressure generating chambers 12. In addition, the reservoir forming substrate 30 is provided with a piezoelectric element holding portion 32 that can secure a space that does not hinder its movement in a region facing the piezoelectric element 300. Since the piezoelectric element 300 is formed in the piezoelectric element holding portion 32, the piezoelectric element 300 is protected in a state hardly affected by the external environment. Note that the piezoelectric element holding portion 32 may be sealed, but may not be sealed.

  An exposure hole 33 that penetrates in the thickness direction and exposes the second lead electrode 94 is formed in a region opposite to the reservoir portion 31 of the piezoelectric element holding portion 32 of the reservoir forming substrate 30. Yes. Although not shown, the drive IC mounted on the reservoir forming substrate 30 is electrically connected to the second lead electrode 94 and the lower electrode film 60 by connection wiring extending in the exposure hole 33. Has been.

  Examples of the material of the reservoir forming substrate 30 include glass, ceramic material, metal, resin, and the like. However, the reservoir forming substrate 30 is preferably formed of substantially the same material as the thermal expansion coefficient of the flow path forming substrate 10. Preferably, in the present embodiment, the silicon single crystal substrate made of the same material as the flow path forming substrate 10 is used.

  Here, such a reservoir forming substrate 30 is bonded to the flow path forming substrate 10 by the adhesive 35 as described above. For example, the flow path in a region facing the ink supply path 15 and the ink communication path 14 is used. A discontinuous metal layer, a first laminated electrode 140, and the like are formed on the formation substrate 10, and the reservoir formation substrate 30 is actually bonded to the formation substrate 10 with an adhesive 35.

  In the present invention, the discontinuous laminated electrode 160 that is electrically separated from the first laminated electrode 140 is provided on the communication portion 13 side of the first laminated electrode 140, and the discontinuous metal layer 97, the first The reservoir forming substrate 30 is bonded to the discontinuous laminated electrode 160 by the adhesive 35 together with the laminated electrode 140.

  Thereby, the reservoir forming substrate 30 and the flow path forming substrate 10 can be bonded very well, and the ink in the reservoir 120 penetrates from between the flow path forming substrate 10 and the reservoir forming substrate 30 to hold the piezoelectric element. Intrusion into the part 32 can be prevented. Therefore, destruction of the piezoelectric element 300 due to ink can be reliably prevented. Furthermore, since the discontinuous laminated electrode 160 and the first laminated electrode 140 are electrically separated, that is, insulated from each other, a voltage is applied to the ink even if the ink penetrates to the discontinuous laminated electrode 160. As a result, the ink does not electrolyze, and no gas or foreign matter is generated, resulting in ink droplet ejection failure. Further, for example, as in the present embodiment, a discontinuous metal layer 97 including a metal layer made of gold (Au) is provided on the periphery of the communication portion 13, and the reservoir forming substrate 30 is formed on the discontinuous metal layer 97. This is particularly effective when bonded. That is, the discontinuous metal layer 97 (metal layer 96) has low adhesion to the adhesive 35, and the ink easily penetrates between the discontinuous metal layer 97 and the adhesive 35. By providing the ink, it is possible to reliably prevent ink from entering the piezoelectric element holding portion 32.

  Even if the stress relaxation layer 150 is separated into a region corresponding to the discontinuous laminated electrode 160 and a region corresponding to the first laminated electrode 140, the ink into the piezoelectric element holding portion 32 as described above is used. Intrusion can be prevented, but the stress relaxation layer 150 is continuously formed in the region corresponding to the first laminated electrode 140 and the discontinuous laminated electrode 160 from the viewpoint of preventing the diaphragm from being broken. I have to. When the stress relaxation layer 150 is separated into a region corresponding to the first multilayer electrode 140 and a region corresponding to the discontinuous multilayer electrode 160, the diaphragm in the region corresponding to the end of the stress relaxation layer 150 is formed. This is because stress concentration occurs and cracks are likely to occur. That is, the stress relaxation layer 150 may be provided continuously in at least a region between the first stacked electrode 140 and the discontinuous stacked electrode 160. For example, as shown in FIG. In the region below the electrode 140 and the discontinuous laminated electrode 160, the stress relaxation layer 150 may be provided only in the region corresponding to the end portions of the first laminated electrode 140 and the discontinuous laminated electrode 160. Of course, even with such a configuration, it is possible to reliably prevent ink from entering the piezoelectric element holding portion 32 while preventing the vibration plate from being destroyed.

  Further, when the discontinuous metal layer 97 including the adhesion layer 95 and the metal layer 96 is provided on the peripheral edge of the opening of the communication portion 13 as in the present embodiment, for example, as shown in FIG. You may make it form the contact | adherence layer 95 which comprises the continuous metal layer 97 continuously on the discontinuous laminated electrode 160. FIG. Since the adhesion layer 95 has high adhesiveness with the adhesive 35, it is possible to more reliably prevent ink from entering the piezoelectric element holding portion 32. Of course, an adhesive layer made of a material having high adhesiveness to the adhesive 35, for example, titanium tungsten (TiW), nickel chrome (NiCr), or the like is provided separately from the discontinuous metal layer 97 on the discontinuous laminated electrode 160. It may be. It goes without saying that the same effect can be obtained even with such a configuration. Further, by providing this adhesion layer also on the discontinuous metal layer 97, the discontinuous metal layer 97 and the discontinuous laminated electrode 160 can be integrated.

  Note that a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the reservoir forming 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). 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 area of the fixing plate 42 facing the reservoir 120 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 120 is sealed only with a flexible sealing film 41. Has been.

  In such an ink jet recording head of this embodiment, ink is taken in from an external ink supply means (not shown), filled with ink from the reservoir 120 to the nozzle opening 21, and then mounted on the reservoir forming substrate 30. In accordance with a recording signal from a driving IC (not shown), a voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12 to thereby form the elastic film 50, the insulator film 55, and the lower electrode film 60. In addition, by bending and deforming the piezoelectric layer 70, the pressure in each pressure generation chamber 12 is increased, and ink droplets are ejected from the nozzle openings 21.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the discontinuous laminated electrode is provided only in the region corresponding to the ink communication portion and the ink supply path. However, the present invention is not limited to this. For example, the discontinuous laminated electrode extends around the periphery of the piezoelectric element holding portion. You may make it provide continuously. Thereby, for example, ink attached to the outer peripheral surface of the head during printing or the like can be prevented from entering the piezoelectric element holding portion, and destruction of the piezoelectric element by ink can be prevented more reliably.

  Further, for example, in the above-described embodiment, the discontinuous laminated electrode is configured by only the same layer as the first laminated electrode. However, the present invention is not limited to this. For example, the discontinuous laminated electrode is formed of a plurality of layers. It may be configured. In any case, the discontinuous laminated electrode may be formed to be equal to or higher than the height of the film formed around the first laminated electrode or the like.

  In the above-described embodiment, the upper electrode lead-out wiring is composed of the first lead electrode and the second lead electrode. However, the upper electrode lead-out wiring is not limited to this, and the upper electrode lead-out wiring is not limited to the first lead electrode. Only one of the electrode and the second lead electrode may be formed, and the first laminated electrode and the discontinuous laminated electrode may be formed in the same layer as the one lead electrode. Thereby, destruction of the diaphragm due to stress concentration can be prevented while simplifying the manufacturing process.

  The ink jet recording head according to 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. 6 is a schematic view showing an example of the ink jet recording apparatus. As shown in FIG. 6, 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 manufacturing 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. 3 is an enlarged cross-sectional view of the recording head according to the first embodiment. FIG. 6 is an enlarged cross-sectional view illustrating a modification of the recording head according to the first embodiment. FIG. 6 is an enlarged cross-sectional view illustrating a modification of the recording head according to the first embodiment. 1 is a schematic diagram of a recording apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 13 Communication part, 14 Ink communication path, 15 Ink supply path, 20 Nozzle plate, 21 Nozzle opening, 30 Reservoir formation board, 31 Reservoir part, 32 Piezoelectric element holding part, 40 Compliance Substrate, 60 lower electrode film, 70 piezoelectric layer, 80 upper electrode film, 90 upper electrode lead electrode, 91 first lead electrode, 94 second lead electrode, 97 discontinuous metal layer, 98 lower electrode lead electrode , 100 first insulating film, 110 second insulating film, 120 reservoir, 140 first laminated electrode, 150 stress relaxation layer, 160 discontinuous laminated electrode, 300 piezoelectric element

Claims (9)

A flow path forming substrate provided with a pressure generating chamber that communicates with the nozzle opening and a communication portion that communicates with the pressure generating chamber via a supply path, and a diaphragm on one side of the flow path forming substrate A piezoelectric element including a lower electrode, a piezoelectric layer, and an upper electrode, and a reservoir forming substrate having a reservoir portion that is joined to the surface of the flow path forming substrate on the piezoelectric element side and communicates with the communicating portion. ,
The region corresponding to the supply path is composed of a layer different from the lower electrode and the upper electrode and is electrically connected to the lower electrode on at least the diaphragm in the region to which the reservoir forming substrate is bonded. A laminated electrode having a linear expansion coefficient larger than that of the diaphragm and extending along a parallel direction of the pressure generating chambers through a stress relaxation layer made of a material smaller than the laminated electrode,
In addition, a discontinuous multilayer electrode that is discontinuous with the multilayer electrode is disposed in the region on the communication portion side of the multilayer electrode via the stress relaxation layer continuously provided from a region corresponding to the multilayer electrode. A liquid ejecting head, wherein the liquid ejecting head is arranged in parallel with an electrode. The liquid ejecting head according to claim 1, wherein the supply path is provided through the flow path forming substrate. The liquid ejecting head according to claim 1, wherein the multilayer electrode and the discontinuous multilayer electrode are insulated from each other. The liquid ejecting head according to claim 1, wherein the stress relaxation layer is made of a ceramic material. 5. The stress relaxation layer according to claim 1, wherein the stress relaxation layer is made of the same layer as the piezoelectric layer constituting the piezoelectric element, and is separated from the piezoelectric layer constituting the piezoelectric element. A liquid ejecting head characterized by the above. The liquid ejecting head according to claim 1, wherein a thickness of the stress relaxation layer is equal to or greater than a thickness of the stacked electrode. The liquid ejecting head according to claim 1, wherein the reservoir forming substrate includes a piezoelectric element holding portion that protects the piezoelectric element. 8. The flow path forming substrate according to claim 1, wherein the flow path forming substrate is made of a silicon single crystal substrate, and the diaphragm includes at least an elastic film made of silicon dioxide formed on a surface of the flow path forming substrate. A liquid ejecting head. A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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