JP2006239966A - Liquid jetting head and liquid jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting head which can stabilize a liquid ejection characteristic in a good state and can also prevent breakage of a diaphragm, and to provide a liquid jetting apparatus. <P>SOLUTION: The liquid jetting head is equipped with a channel forming substrate 10 where pressure generating chambers communicating with nozzle openings are formed; and piezoelectric elements each comprised of a lower electrode, a piezoelectric layer and an upper electrode set via the diaphragm at one face side of the channel forming substrate 10. At the same time, the liquid jetting head has a laminated electrode 140 which consists of a layer different from the lower electrode and upper electrode. The laminated electrode 140 is set on the diaphragm outside of a region corresponding to the pressure generating chambers and is electrically connected with the lower electrode 60. A stress relaxing layer 150 formed of a material whose coefficient of linear expansion is larger than that of the diaphragm and smaller than that of the laminated electrode 140 is set at a region corresponding to at least an end of the laminated electrode 140 between the laminated electrode 140 and the diaphragm. <P>COPYRIGHT: (C)2006,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 diaphragm, 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 thereof 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.

  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.)

  In view of such circumstances, it is an object of the present invention to provide a liquid ejecting head and a liquid ejecting apparatus that can stabilize the liquid ejection characteristics in a good state and prevent the vibration plate from being destroyed.

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 is formed, and a lower surface provided on one surface side of the flow path forming substrate via a diaphragm. A piezoelectric element composed of an electrode, a piezoelectric layer, and an upper electrode, and is provided on the diaphragm outside the region corresponding to the pressure generating chamber, which is formed of a layer different from the lower electrode and the upper electrode. A laminated electrode electrically connected to the lower electrode, and a coefficient of linear expansion between the laminated electrode and the diaphragm is at least in a region corresponding to an end of the laminated electrode. In the liquid jet head, a stress relaxation layer made of a material larger than the plate and smaller than the laminated electrode is provided.
In the first aspect, by providing the stress relaxation layer, the stress concentration on the diaphragm at least at the portion corresponding to the end of the laminated electrode is suppressed, and the diaphragm is prevented from being destroyed due to the stress concentration. The

According to a second aspect of the present invention, in the liquid jet head according to the first aspect, the stress relaxation layer is provided only in a region corresponding to an end portion of the laminated electrode.
In the second aspect, the stress concentration on the diaphragm at the end of the laminated electrode is more effectively suppressed.

According to a third aspect of the present invention, in the liquid jet head according to the first or second aspect, the stress relaxation layer is provided so as to extend to an outside of an edge portion of the laminated electrode.
In the third aspect, the stress concentration on the diaphragm at the end of the laminated electrode is more effectively 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 more reliably suppressed.

According to a fifth aspect of the present invention, in the fourth aspect, the stress relaxation layer is formed of the same layer as the piezoelectric layer that constitutes the piezoelectric element, and the piezoelectric layer that constitutes the piezoelectric element; Are separated from each other in the liquid ejecting head.
In the fifth aspect, the stress relaxation layer can be formed relatively easily in the same process as the piezoelectric element, and the stress propagation of the piezoelectric element 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 any one of the first to sixth aspects, the flow path forming substrate is made 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 seventh aspect, cracks due to stress concentration are particularly likely to occur in the elastic film made of silicon dioxide, but by providing a stress relaxation layer, it is also possible to prevent cracks occurring in the elastic film.

An eighth aspect of the present invention is a liquid ejecting apparatus including the liquid ejecting head according to any one of the first to seventh aspects.
In the eighth 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)
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 of 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 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 15 keeps the flow path resistance of the ink flowing from the ink communication path 14 into the pressure generation chamber 12 constant. In addition, a plurality of adhesion relief grooves 16 parallel to the longitudinal direction of the pressure generation chambers 12 are provided in a region outside the row of the pressure generation chambers 12 so as to penetrate the flow path forming substrate 10. The adhesion escape groove 16 serves to prevent excess adhesive from flowing into the pressure generating chamber 12 when a protective substrate, which will be described later, is bonded to the flow path forming substrate 10 with an adhesive.

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, the insulator film 55 is made of platinum (Pt) and iridium (Ir) and has a thickness of, for example, a lower electrode film 60 of about 0.2 μm and lead zirconate titanate (PZT). 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. The elastic film 50 and the insulator film 55 are collectively referred to as a diaphragm.

As a material of the piezoelectric layer 70, for example, a relaxor ferroelectric material obtained by adding a metal such as niobium, nickel, magnesium, bismuth or yttrium 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.

  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 extends to the vicinity of the end portion 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 protective 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, It consists of a metal layer 93 formed 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 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 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. 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.

  Further, on the lower electrode film 60 outside the region corresponding to the pressure generation chambers 12 arranged side by side, the first laminated electrode made of the same layer (adhesion layer 92 and metal layer 93) as the first lead electrode 91 is formed. 140 is provided and is electrically connected to the lower electrode film 60. Further, in the region between the piezoelectric elements 300 arranged in parallel, for example, the lower electrode lead-out wiring 97 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 wiring 97 is composed of the adhesion layer 92 and the metal layer 93 that constitute the first lead electrode 91. The lower electrode lead-out wiring 97 extends from the first laminated electrode 140 along the lead-out direction of the upper electrode lead-out 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 wiring 97 and the like is provided in order 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 wirings 97 are continuously formed from the first laminated electrode 140, the occurrence of a voltage drop can be prevented more reliably, and the ink discharge characteristics can always be good and stable. Obtainable.

  In the present invention, the 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 interposed between the first multilayer electrode 140 and the diaphragm. Is provided. The stress relaxation layer 150 may be provided at least in a region corresponding to the end portion of the first stacked electrode 140. That is, the stress relaxation layer 150 may be formed so that the end portion of the first multilayer electrode 140 is positioned on the stress relaxation layer 150. For example, in this embodiment, as shown in FIG. 3, the stress relaxation layer 150 is provided only in a region corresponding to the end portion of the first stacked electrode 140. Of course, this stress relaxation layer 150 is not only in the region corresponding to the end portion of the first multilayer electrode 140, but also, for example, on the lower side of the first multilayer electrode 140 over the entire surface thereof as shown in FIG. It may be provided continuously.

  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 material forming the diaphragm and smaller than the material of the first stacked 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 the laminated electrode 140 may be used, and a ceramic material or the like is preferably used. In the present embodiment, the stress relaxation layer 150 is formed of the same layer as the piezoelectric layer 70 constituting the piezoelectric element 300, that is, lead zirconate titanate (PZT).

By providing such a stress relaxation layer 150 between the first laminated electrode 140 and the diaphragm, the stress of the diaphragm and the first laminated electrode 140 causes the stress of the first laminated electrode 140. The diaphragm which generate | occur | produces around, especially the crack of the elastic film 50 can be prevented. In addition, in the region corresponding to the end portion of the first laminated electrode 140, the diaphragm is easily cracked due to stress concentration. However, by providing the stress relaxation layer 150, it is possible to reliably crack the diaphragm due to such stress concentration. Can be prevented. Furthermore, if the stress relaxation layer 150 is provided only in the region corresponding to the end portion of the first laminated electrode 140 as in the present embodiment, it is possible to more reliably prevent the diaphragm from cracking.
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 described above, the stress relaxation layer 150 may be provided in a region facing the end portion of the first stacked electrode 140, but the stress relaxation layer 150 is provided at the end portion of the first stacked electrode 140. It is desirable to be provided continuously so as to straddle. That is, the position of the end portion of the stress relaxation layer 150 may coincide with the position of the end portion of the first stacked electrode 140, but is positioned outside the end portion of the first stacked electrode 140. It is preferable. Specifically, when each of the first stacked electrode 140 and the stress relaxation layer 150 has a thickness of about 1 μm as in the present embodiment, the end of the stress relaxation layer 150 is connected to the first stacked electrode 140. It is desirable to be located at least 16 μm outside from the end. Furthermore, the stress relaxation layer 150 is preferably formed to be equal to or thicker than the thickness of the first stacked electrode 140. By providing such a stress relaxation layer 150 between the lower electrode film 60 and the first laminated electrode 140 in the extending direction of the lower electrode film 60 and the first laminated electrode 140, the stress is reduced. The cracking of the diaphragm due to concentration can be prevented more reliably.

  Here, the head of Example 1 in which the stress relaxation layer is provided only in the region corresponding to the end portion of the lower electrode film, and the head of Example 2 in which the stress relaxation layer is continuously provided in the region corresponding to the lower electrode film. The results of calculating the stress state of the diaphragm by the stress calculation by the finite element method in each of the head of the comparative example not provided with the stress relaxation layer will be described. Specifically, when manufacturing the heads of Examples 1 and 2 and the comparative example, the first laminated metal was formed on the lower electrode film at a predetermined temperature, and then cooled to lower the temperature by 300 ° C. Then, the stress generated in the elastic film (vibration plate) after cooling is applied to the portion where the flow path forming substrate exists (with Si) below the vibration plate and the flow path forming substrate exists below the vibration plate. The calculation was made for the portion not having Si (without Si). The results are shown in Table 1 below.

  As shown in Table 1, in the head of the comparative example, the same relatively large stress was generated in the elastic film regardless of “with Si” and “without Si”. In contrast, in the heads of Examples 1 and 2 provided with the stress relaxation layer, it can be seen that the stress generated in the elastic film is clearly reduced. In particular, in the head of Example 2 in which the stress relaxation layer is provided only in the region corresponding to the end portion of the first multilayer electrode, the stress generated in the elastic film is approximately the same as that of the head of the comparative example in the case of “Si present”. It was suppressed to about half, and when “no Si” was reached, it was significantly reduced to about 30% of the head of the comparative example.

  As is clear from these results, according to the configuration of the present invention in which the stress relaxation layer is provided between the diaphragm and the first laminated electrode, the stress is caused by the stress of the diaphragm and the first laminated electrode 140. It is possible to reliably prevent cracking of the vibrating plate.

  In the present embodiment, only the first laminated electrode 140 is provided on the lower electrode film 60 outside the region corresponding to the pressure generation chamber 12 via the stress relaxation layer 150. For example, FIG. As shown in FIG. 6, a second laminated electrode 160 made of the same layer (adhesion layer 95 and metal layer 96) as the second lead electrode 94 may be further provided on the first laminated electrode 140. Further, the second stacked electrode 160 provided on the first stacked electrode 140 may be provided with a narrower width than the first stacked electrode 140 as shown in FIG. As shown in FIG. 5 (b), it may be formed with a width wider than that of the first laminated electrode 140.

  When the stress relaxation layer 150 is provided only in the region corresponding to the end portion of the lower electrode film 60 as in the present embodiment, the stress relaxation layer 150 is formed as shown in FIG. It is preferable to provide the second stacked electrode 160 only in a region that is not present. As a result, the surface heights of the first and second laminated electrodes 140 and 160 laminated on the lower electrode film 60 substantially coincide with each other, so that the protective substrate 30 described later is attached to the flow path forming substrate 10 with an adhesive or the like. Good bonding can be achieved.

  On the surface of the flow path forming substrate 10 on the piezoelectric element 300 side, for example, a protective substrate 30 having a piezoelectric element holding portion 31 capable of ensuring a space that does not hinder its movement in a region facing the piezoelectric element 300 is bonded. It is joined via the agent 35. 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. The piezoelectric element holding portion 31 may be sealed, but of course may not be sealed.

  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. The reservoir 120 is connected to the pressure generation chamber 12 and serves as a common ink chamber for the pressure generation chambers 12. Furthermore, an exposed hole 33 through which the second lead electrode 94 is exposed through the protective substrate 30 in the thickness direction is formed in a region of the piezoelectric element holding portion 31 opposite to the reservoir portion 32. Although not shown, the driving IC mounted on the protective 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. ing.

  In addition, 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 material is substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10. In this embodiment, the silicon single crystal 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). 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 protective substrate 30. In accordance with a recording signal from an 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, and the elastic film 50, the insulator film 55, the lower electrode By bending and deforming the film 60 and the piezoelectric layer 70, the pressure in each pressure generating chamber 12 is increased and ink droplets are ejected from the nozzle openings 21.

(Other embodiments)
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, a configuration in which one or two layers of stacked electrodes (first and second stacked electrodes) are formed on the lower electrode film is illustrated, but the present invention is not limited to this, and of course, the lower electrode Three or more laminated electrodes may be provided on the film. Even in such a configuration, by providing the stress relaxation layer as described above between the diaphragm and the laminated electrode, it is possible to prevent the diaphragm from cracking due to stress concentration.

  In the above-described embodiment, the lower electrode film 60 extends from the region corresponding to the pressure generation chamber 12 to the vicinity of the end of the flow path forming substrate 10 in the direction in which the pressure generation chambers 12 are arranged in parallel. In addition, the configuration in which the plurality of piezoelectric elements 300 and the upper electrode lead-out electrode 90 are continuously provided is exemplified, but the present invention is not limited thereto, and the lower electrode film 60 is a region corresponding to the pressure generation chamber 12. It may be provided only. Even in such a configuration, as long as the first laminated electrode 140 and the second laminated electrode 160 are electrically connected to the lower electrode film 60 in the region corresponding to the pressure generating chamber 12, the piezoelectric element 300 is provided. A voltage drop at the time of driving can be prevented.

  In the above-described embodiment, the example in which the stress relaxation layer is provided between the lower electrode film and the multilayer electrode (first multilayer electrode) has been described. However, the stress relaxation layer is formed between the diaphragm and the multilayer electrode. For example, it may be provided below the lower electrode film.

  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. 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. 3 is an enlarged cross-sectional view illustrating a wiring structure of a recording head according to Embodiment 1. FIG. 3 is an enlarged cross-sectional view illustrating a wiring structure of a recording head according to Embodiment 1. FIG. 3 is an enlarged cross-sectional view illustrating a wiring structure of a recording head according to Embodiment 1. FIG. 3 is an enlarged cross-sectional view illustrating a wiring structure of a recording head according to Embodiment 1. FIG. 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, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board | substrate, 40 Compliance board | substrate, 60 Lower electrode film, 70 Piezoelectric layer, 80 Upper electrode film, 90 Lead electrode for upper electrode, 91 1st lead electrode, 94 2nd lead electrode, 100 1st insulating film, 110 2nd insulating film, 140 1st laminated electrode, 150 Stress relaxation layer, 160 2nd laminated electrode, 300 Piezoelectric element

Claims (8)

A flow path forming substrate in which a pressure generating chamber communicating with the nozzle opening is formed, and a piezoelectric element including a lower electrode, a piezoelectric layer, and an upper electrode provided on one side of the flow path forming substrate via a vibration plate A laminated electrode that is provided on the diaphragm outside the region corresponding to the pressure generation chamber and is electrically connected to the lower electrode, and is configured by a layer different from the lower electrode and the upper electrode. And having a linear expansion coefficient larger than that of the diaphragm and smaller than that of the multilayer electrode, at least in a region corresponding to the end of the multilayer electrode between the multilayer electrode and the diaphragm. A liquid ejecting head, wherein a relaxation layer is provided. The liquid ejecting head according to claim 1, wherein the stress relaxation layer is provided only in a region corresponding to an end portion of the multilayer electrode. 3. The liquid jet head according to claim 1, wherein the stress relaxation layer is provided to extend to an outside of an edge portion of the multilayer electrode. The liquid ejecting head according to claim 1, wherein the stress relaxation layer is made of a ceramic material. 5. The liquid according to claim 4, 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. Jet head. 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. 7. The method 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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