JP2019042940A - Liquid discharge head and printer - Google Patents

Abstract

To provide a liquid discharge head in which a displacement amount of a diaphragm is large and which has high reliability, and a printer comprising the liquid discharge head.SOLUTION: A liquid discharge head includes: a pressure chamber; a diaphragm forming one wall of the pressure chamber; a piezoelectric element having a first electrode formed on the diaphragm, a thin film piezoelectric layer being formed on the first electrode and containing lead, and a second electrode formed on the thin film piezoelectric layer; and a lead diffusion suppression layer provided between the diaphragm and the thin film piezoelectric layer. A contour of the thin film piezoelectric layer in a thickness direction of the diaphragm is disposed closer to an inside than a contour of the pressure chamber in the thickness direction of the diaphragm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid discharge head and a printer.

  The liquid discharge head discharges the ink and the other liquid in the pressure chamber from the nozzle using a drive element such as a piezoelectric element. The piezoelectric element includes a piezoelectric layer and electrodes sandwiching the piezoelectric layer. It is possible to change the volume of the pressure chamber and discharge the liquid by utilizing the distortion of the piezoelectric body by applying the drive voltage to these electrodes. With the miniaturization of the liquid discharge head, thinning and miniaturization of each part including the piezoelectric material has been required.

  Patent Document 1 discloses a liquid discharge head including a substrate having a pressure chamber formed therein, a diaphragm formed on the substrate, and a piezoelectric thin film element formed on the diaphragm.

Unexamined-Japanese-Patent No. 2004-042329

  In the liquid discharge head described in Patent Document 1, displacement of the diaphragm by the piezoelectric element is achieved by driving the thin film piezoelectric element so that the degree of 100 plane orientation of the PZT crystal constituting the piezoelectric element exceeds 70%. The quantity has been improved.

  However, the amount of displacement of the diaphragm by the piezoelectric element is very large, such as not only the crystal orientation of the piezoelectric, but also the composition of the piezoelectric, the shape of the piezoelectric, the arrangement of the piezoelectric, the shape of the diaphragm, and the material of the diaphragm. Related to the elements of Also, these various elements are known to affect each other, and changing certain elements to improve one property (eg, displacement) will result in other properties if not changing the other elements. It is also possible that it falls.

  For example, when the composition of the piezoelectric body of the piezoelectric element is changed to increase the displacement of the diaphragm, the reliability of the liquid discharge head may be reduced. Therefore, in order to improve the displacement amount of the diaphragm, it is required to comprehensively examine each element of the liquid discharge head related to the displacement amount.

  An object of some aspects of the present invention is to provide a liquid discharge head having a large displacement of a diaphragm and high reliability, and a printer including the same.

  The present invention has been made to solve at least a part of the problems described above, and can be realized as the following aspects or application examples.

One aspect of the liquid discharge head according to the present invention is
With a pressure chamber,
A diaphragm forming a wall of the pressure chamber;
A piezoelectric element having a first electrode formed on the diaphragm, a thin film piezoelectric layer containing lead formed on the first electrode, and a second electrode formed on the thin film piezoelectric layer; ,
A lead diffusion suppression layer provided between the diaphragm and the thin film piezoelectric layer;
Have
The contour of the thin film piezoelectric layer in the thickness direction of the diaphragm is disposed inside the contour of the pressure chamber in the thickness direction of the diaphragm.

  Such a liquid discharge head is formed so that the contour of the thin film piezoelectric layer in the thickness direction of the diaphragm is disposed inward of the contour of the pressure chamber in the thickness direction of the diaphragm. The structural limitation of the deformation of the diaphragm due to the extremely hard thin film piezoelectric layer is suppressed. Thereby, the displacement amount of the diaphragm can be increased. Further, by providing the lead diffusion suppression layer between the diaphragm and the thin film piezoelectric layer, the diffusion of lead to the diaphragm can be suppressed. As a result, since embrittlement of the diaphragm due to lead can be suppressed, the diaphragm can be less likely to be broken, and the reliability of the liquid discharge head can be enhanced. Furthermore, since the diffusion of lead is suppressed by the presence of the lead diffusion suppression layer, the firing temperature of the thin film piezoelectric layer can be increased. Thus, the piezoelectric characteristics of the piezoelectric element can be enhanced, so that the amount of deformation of the piezoelectric element itself can be increased, and the amount of displacement of the diaphragm can be increased.

  In the liquid discharge head according to the present invention, the diaphragm may have a laminated structure.

  According to such a liquid discharge head, warpage and deflection of the diaphragm in an initial state (the state immediately after formation of the diaphragm) can be controlled more easily.

In the liquid discharge head according to the present invention,
The diaphragm includes a first layer, and second and third layers sandwiching the first layer,
The second layer and the third layer may have the same composition.

  According to such a liquid discharge head, it is easy to balance the stress in the thickness direction of the laminated diaphragms. That is, since the first layer is sandwiched by the second layer and the third layer of the same composition and has a symmetrical structure in the thickness direction, the diaphragm in the initial state (the state immediately after the diaphragm is formed) Can be more easily controlled. Furthermore, since the diffusion of lead into the diaphragm is suppressed by the lead diffusion suppression layer, the disturbance of the balanced stress distribution is suppressed. That is, in the case of such a diaphragm, the effect of the lead diffusion suppression layer becomes more remarkable.

In the liquid discharge head according to the present invention,
The lead diffusion suppression layer may have conductivity and be provided between the first electrode and the thin film piezoelectric layer.

  According to such a liquid discharge head, the lead diffusion suppression layer can function as an auxiliary electrode of the first electrode. In addition, the lead diffusion suppression layer can also be used as the first electrode.

In the liquid discharge head according to the present invention,
The lead diffusion suppression layer may be provided between the diaphragm and the first electrode.

  According to such a liquid discharge head, since the lead diffusion suppressing layer is not contained in the piezoelectric element, it is difficult to inhibit the piezoelectric performance of the piezoelectric element, and lead contained in the thin film piezoelectric layer is diffused to the diaphragm. It can be difficult to do. In addition, when the lead diffusion suppression layer has conductivity, the lead diffusion suppression layer can function as an auxiliary electrode of the first electrode.

In the liquid discharge head according to the present invention,
The thickness of the thin film piezoelectric layer may be 3 μm or less.

  According to such a liquid discharge head, the displacement amount of the diaphragm can be further increased.

One aspect of the liquid discharge head according to the present invention is
With a pressure chamber,
A diaphragm forming a wall of the pressure chamber;
A piezoelectric element having a first electrode formed on the diaphragm, a thin film piezoelectric layer containing lead formed on the first electrode, and a second electrode formed on the thin film piezoelectric layer; ,
Have
The contour of the thin film piezoelectric layer in the thickness direction of the diaphragm is disposed inside the contour of the pressure chamber in the thickness direction of the diaphragm.
The first electrode functions as a lead diffusion suppression layer.

  Such a liquid discharge head is formed so that the contour of the thin film piezoelectric layer in the thickness direction of the diaphragm is disposed inward of the contour of the pressure chamber in the thickness direction of the diaphragm. The structural limitation of the deformation of the diaphragm due to the extremely hard thin film piezoelectric layer is suppressed. Thereby, the displacement amount of the diaphragm can be increased. Further, by providing the first electrode functioning as the lead diffusion suppression layer between the diaphragm and the thin film piezoelectric layer, it is possible to suppress the diffusion of lead to the diaphragm. As a result, since embrittlement of the diaphragm due to lead can be suppressed, the diaphragm can be less likely to be broken, and the reliability of the liquid discharge head can be enhanced. Furthermore, since the diffusion of lead is suppressed by the presence of the first electrode functioning as a lead diffusion suppression layer, the firing temperature of the thin film piezoelectric layer can be increased. Thus, the piezoelectric characteristics of the piezoelectric element can be enhanced, so that the amount of deformation of the piezoelectric element itself can be increased, and the amount of displacement of the diaphragm can be increased.

  One aspect of a printer according to the present invention includes the liquid discharge head described above.

  Since such a printer includes the above-described liquid discharge head, the displacement amount of the diaphragm is large, the efficiency of the discharge of the liquid (for example, ink) is high, and the liquid discharge head is unlikely to be damaged.

  In the present invention, when referring to a specific B member (hereinafter referred to as "B") provided "above" or "below" a specific A member (hereinafter referred to as "A"), the upper side of A is referred to. Or it is a meaning including the case where B is provided directly under, and the case where B is provided above or below A via another member. Also, the case of A top is the same as the case of A above. In addition, when B is present above or below A, it means that it can be understood as such by changing the viewing direction or angle or rotating the field of view, and it is irrelevant to the action direction of gravity.

FIG. 2 is a schematic view of a cross section of the liquid discharge head according to the embodiment. FIG. 2 is a schematic view of a cross section of the liquid discharge head according to the embodiment. FIG. 2 is a schematic view of the liquid discharge head according to the embodiment as viewed in plan. FIG. 1 is a perspective view schematically showing a printer according to an embodiment.

  Hereinafter, some embodiments of the present invention will be described. The embodiment described below is an example of the present invention. The present invention is not limited to the following embodiments at all, and includes various modifications implemented without departing from the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

1. Liquid Ejection Head A liquid ejection head according to the present embodiment will be described with reference to the drawings. 1 and 2 are schematic views of a cross section of the liquid discharge head 200 according to the present embodiment. FIG. 3 is a schematic plan view of the liquid discharge head 200 according to the present embodiment. 1 and 2 correspond to the cross sections taken along the line I-I and the line II-II of FIG. 3, respectively. Note that the sizes and thicknesses of the respective members in FIGS. 1 to 3 are drawn in a partially exaggerated manner for the convenience of the description, and the relative sizes and thicknesses of the respective members are not limited to those illustrated either.

  A liquid discharge head 200 will be described as an embodiment of a liquid discharge head according to the present invention. The liquid discharge head 200 of the present embodiment includes a nozzle plate 10, a pressure chamber substrate 20, a diaphragm 30, a piezoelectric element 40, and a lead diffusion suppression layer 50. The pressure chamber 21 is defined by the diaphragm 30, the pressure chamber substrate 20, and the nozzle plate 10, and the diaphragm 30 forms one wall of the pressure chamber 21.

1.1. Nozzle Plate The nozzle plate 10 has a flat plate shape as shown in FIGS. 1 and 2. The nozzle plate 10 is provided below the pressure chamber substrate 20. The nozzle plate 10 may be integral with or separate from the pressure chamber substrate 20. In the case of a separate body, the nozzle plate 10 is bonded to the pressure chamber substrate 20 by, for example, an adhesive or a heat welding film. The nozzle plate 10 constitutes one wall (lower wall) of the pressure chamber 21 and has a plurality of nozzle holes 11 corresponding to the pressure chamber 21.

  The nozzle hole 11 communicates with the pressure chamber 21, and the liquid (for example, ink) filled in the pressure chamber 21 is discharged from the nozzle hole 11 according to the change in volume of the pressure chamber 21. A plurality of nozzle holes 11 are provided, for example, according to the number of pressure chambers 21, and are provided, for example, in a line along the direction in which the pressure chambers 21 are arranged.

  As a material of the nozzle plate 10, silicon, stainless steel (SUS etc.), titanium, titanium alloy etc. can be mentioned.

1.2. Pressure Chamber Substrate The pressure chamber substrate 20 is processed into a shape that can form the side wall of the pressure chamber 21. The pressure chamber substrate 20 is formed, for example, by etching a silicon substrate. In the present embodiment, as shown in FIG. 3, a communication passage 22 is formed at the end of the pressure chamber 21. The communication passage 22 is formed so as to reduce the flow cross-sectional area by narrowing the end of the pressure chamber 21. The length and shape of the communication passage 22 are not particularly limited.

  Although not shown, the pressure chamber 21 is connected to the manifold via the communication passage 22. The manifold is a common liquid supply path of each pressure chamber 21. The manifold is connected to a liquid reservoir (liquid tank, cartridge, etc.), and liquid is supplied from the liquid tank to the pressure chamber 21 through the manifold. The pressure chamber substrate 20 may be formed with another flow path in addition to the pressure chamber 21 and the communication path 22.

1.3. Diaphragm The diaphragm 30 has a flat plate shape, and constitutes one wall (upper wall) of the pressure chamber 21. The diaphragm 30 is provided above the pressure chamber substrate 20. Another layer may be provided between the diaphragm 30 and the pressure chamber substrate 20. Alternatively, the diaphragm 30 may be provided directly on the upper end surface of the pressure chamber substrate 20. The diaphragm 30 can be bent or vibrated by the operation of the piezoelectric element 40.

In the present specification, the diaphragm 30 is a member present between the end (upper end) of the pressure chamber substrate 20 and the lead diffusion suppression layer 50, and a member that bends or vibrates due to the operation of the piezoelectric element 40. Defined as the whole of However, in the case where the lead diffusion suppression layer 50 has conductivity, and is disposed between the thin film piezoelectric layer 44 and the first electrode 42, lead diffusion from the end (upper end) of the pressure chamber substrate 20 A member other than the first electrode 42 existing up to the suppression layer 50 is defined as the entire member that bends or vibrates due to the operation of the piezoelectric element 40.

The material of the diaphragm 30 desirably includes a material having high rigidity and mechanical strength. The thickness of the diaphragm 30 is appropriately designed, for example, in accordance with the mechanical properties of the material used. Examples of the material of the diaphragm 30 include inorganic oxides such as zirconium oxide (ZrO _x ), silicon nitride (SiN), silicon oxide (SiO _x ), tungsten (W), tantalum (Ta), stainless steel (SUS), etc. Inorganic nitrides, oxynitrides, metals, alloys and the like can be exemplified. The suffix “ _x ” is a value determined by the stoichiometry ratio or a value in the vicinity thereof.

  The diaphragm 30 may have a laminated structure of two or more layers. The number of layers to be laminated is not particularly limited. In the case of a laminated structure, the material and thickness of each layer can be set independently. By forming the diaphragm 30 into a laminated structure, for example, the diaphragm 30 in an initial state (for example, a state in which the diaphragm 30 is formed after the silicon of the pressure chamber substrate 20 is etched) when the liquid discharge head 200 is manufactured. It is easy to control the warpage and deflection of the lens to a predetermined degree. Moreover, by setting it as a laminated structure, the efficiency in the case of the bending of the diaphragm 30, or a vibration may be able to be improved, for example.

  In the example of FIG. 1 and FIG. 2, the diaphragm 30 has a three-layer structure. Furthermore, in the illustrated example, the material of the stacked three layers is independently optional, but can be, for example, silicon oxide, silicon nitride, or silicon oxide in order from the pressure chamber substrate 20 side. Although not shown, it may be a five-layer structure, and the material of each layer to be stacked in that case is not particularly limited, but, for example, silicon oxide, tungsten, silicon oxide, tungsten, oxide in order from the pressure chamber substrate 20 side It may be silicon or the like.

  When the diaphragm 30 has a laminated structure of three or more layers, as in the illustrated laminated structure, when viewed from a specific layer (first layer) among the laminated layers, the layer In the diaphragm 30, there is a layer configuration in which the second layer and the third layer are laminated so as to sandwich the (first layer), and the second layer and the third layer have the same composition (the same material). You may do so. This makes it easier to balance the stress in the thickness direction of the laminated diaphragms 30. That is, in the thickness direction of the diaphragm 30, if it has a symmetrical structure centering on a specific layer, it is possible to further balance the stress in the thickness direction. Thereby, the warpage and deflection of the diaphragm 30 in the initial state can be controlled more easily. In addition, the entire layer configuration of the diaphragm 30 may have a symmetrical structure, and in this case, warpage and deflection of the diaphragm 30 can be easily controlled.

  In the liquid discharge head 200 of the present embodiment, the diffusion of lead to the diaphragm 30 is suppressed by the lead diffusion suppression layer 50 described later. However, with the diaphragm 30 as the above-described laminated structure, the distribution of initial stress is predetermined. In the state, the effect of the lead diffusion suppression layer 50 can be said to be more remarkable in that the distribution of stress is less likely to be disturbed by the diffusion of lead.

  In the above-described symmetrical structure, the second layer and the third layer may have the same composition and the same thickness. As described above, the thickness of each layer can be set as appropriate, but in this case, it may be easier to balance the initial stress.

1.4. Piezoelectric Element The piezoelectric element 40 is provided above the diaphragm 30. The piezoelectric element 40 includes a first electrode 42, a thin film piezoelectric layer 44 and a second electrode 46. The piezoelectric element 40 is electrically connected to a piezoelectric element drive circuit (not shown), and can operate (vibrate, deform) based on a signal of the piezoelectric element drive circuit. The diaphragm 30 is flexed or vibrated (displaced) by the operation of the piezoelectric element 40, whereby the volume of the pressure chamber 21 and the pressure inside can be changed.

1.4.1. First Electrode The first electrode 42 is formed above the diaphragm 30. The planar shape of the first electrode 42 may or may not coincide with the planar shape of the thin film piezoelectric layer 44. The first electrode 42 is electrically connected to the first electrode 42 common to the piezoelectric element 40 when the same piezoelectric element 40 is present next to the piezoelectric element 40, as shown in FIG. It may be connected, and in this case, the first electrode 42 is a common electrode of the plurality of piezoelectric elements 40. In addition, the first electrode 42 may be an individual electrode provided for each piezoelectric element 40. In this case, the second electrode 46 may be a common electrode. The first electrode 42 is electrically connected to an external circuit (not shown).

  The thickness of the first electrode 42 is arbitrary as long as the deformation of the thin film piezoelectric layer 44 can be transmitted to the diaphragm 30. The thickness of the first electrode 42 can be, for example, 50 nm or more and 350 nm or less. The first electrode 42 is paired with the second electrode 46, sandwiches the thin film piezoelectric layer 44, and functions as one electrode of the piezoelectric element 40. The first electrode 42 may have a function of making the crystal orientation and grain size of the thin film piezoelectric layer 44 suitable for piezoelectric operation.

  The material of the first electrode 42 is not particularly limited as long as the material has conductivity. For example, as the material of the first electrode 42, a metal such as nickel (Ni), palladium (Pd), platinum (Pt), titanium (Ti), or a conductive oxide such as a composite oxide of lanthanum and nickel may be used. Can. In addition, the first electrode 42 may be a single layer of the materials exemplified above, or may have a structure in which a plurality of materials are stacked.

1.4.2. Thin Film Piezoelectric Layer The thin film piezoelectric layer 44 is formed above the first electrode 42. The thin film piezoelectric layer 44 is deformed by the application of an electric field by the first electrode 42 and the second electrode 46, thereby causing the diaphragm 30 to bend or vibrate.

The thin film piezoelectric layer 44 is formed of a piezoelectric material containing lead. As a material of the thin film piezoelectric layer 44, a perovskite type oxide (A includes Pb and B includes Zr and Ti) represented by a general formula ABO ₃ can be mentioned. More specifically, the thin film piezoelectric layer 44 is formed of lead zirconate titanate (PZT), lead zirconate titanate niobate (PZTN), or the like.

  The thin film piezoelectric layer 44 is formed by, for example, a sol-gel method. The calcination temperature in the sol-gel method is 500 ° C. to 900 ° C., preferably 600 ° C. to 850 ° C., more preferably 650 ° C. to 830 ° C., and still more preferably 700 ° C. to 800 ° C. The sintering temperature of the thin film piezoelectric layer 44 containing lead is found to be better at a high temperature of, for example, 650 ° C. or higher, preferably 700 ° C. or higher.

  However, since the thin film piezoelectric layer 44 contains lead, diffusion of lead may occur during firing. It is known from the inventors' investigation that if the diffusion of lead occurs to the diaphragm 30, the diaphragm 30 becomes brittle. However, when the liquid discharge head 200 of the present embodiment is manufactured, the diffusion of lead from the thin film piezoelectric layer 44 to the diaphragm 30 is suppressed because the lead diffusion suppression layer 50 described later is present. Thereby, when manufacturing the liquid discharge head 200 of the present embodiment, the thin film piezoelectric layer 44 can be fired, for example, at 650 ° C. or higher, preferably 700 ° C. or higher. Thus, the piezoelectric characteristics of the piezoelectric element 40 can be enhanced, and the embrittlement of the diaphragm 30 can be suppressed.

When the thin film piezoelectric layer 44 is formed by the sol-gel method, the thin film piezoelectric layer 44 may be formed by performing arbitrary steps such as application of a raw material, degreasing, and baking a plurality of times. For example, the material application and degreasing cycles may be repeated and then fired. When the thin film piezoelectric layer 44 is formed in this manner, periodic fluctuation of the composition may be formed in the thickness direction of the thin film piezoelectric layer 44. Such composition fluctuation can be confirmed, for example, by a method such as SIMS (secondary ion mass spectrum) or (S) TEM-EDX ((scanning) transmission electron microscope-energy dispersive X-ray spectroscopy).

  The thickness of the thin film piezoelectric layer 44 is 3 μm or less, preferably 2.5 μm or less, more preferably 2 μm or less. The lower limit of the thickness of the thin film piezoelectric layer 44 is 500 nm, preferably about 1 μm. If the thickness of the thin film piezoelectric layer 44 is about this level, the diaphragm 30 can be efficiently bent or vibrated.

1.4.3. Second Electrode The second electrode 46 is formed above the thin film piezoelectric layer 44. The second electrode 46 is paired with the first electrode 42 and functions as one of the electrodes of the piezoelectric element 40. The thickness of the second electrode 46 is not particularly limited, and can be, for example, 10 nm or more and 300 nm or less. The material of the second electrode 46 is not particularly limited as long as it is a conductive material. The material of the second electrode 46 is the same as that of the first electrode 42, and thus the description thereof is omitted. In addition, the second electrode 46 may be a single layer of the exemplified material, or may be a structure in which a plurality of materials are stacked.

1.5. Lead Diffusion Suppression Layer The lead diffusion suppression layer 50 is provided between the vibration plate 30 and the thin film piezoelectric layer 44. The lead diffusion suppression layer 50 has a function of suppressing the diffusion of lead contained in the thin film piezoelectric layer 44 to the diaphragm 30 when the piezoelectric element 40 is fired.

The thickness of the lead diffusion suppression layer 50 is arbitrary as long as it does not adversely affect the deformation of the diaphragm 30, but for example, 20 nm or more and 400 nm or less, preferably 30 nm or more and 350 nm or less, more preferably 40 nm or more and 300 nm or less It can be done. The material of the lead diffusion suppression layer 50 is ZnO _x , AlO _x , ZrO _x , HfO _x , TaO _x , Ir, IrO _x , RuO _x , VO _x , SrRuO _x , SrTaO _x , LaTaO _x and (LaSr) CoO _x It is selected. Here, the subscript " _x " is a value determined by the stoichiometry ratio or a value in the vicinity thereof. The lead diffusion suppression layer 50 may be a single layer of the exemplified material, or may be a structure in which a plurality of material layers are laminated.

1.6. Positional relationship of each configuration etc. 1.6.1. Thin Film Piezoelectric Layer and Pressure Chamber In the liquid discharge head 200 of the present embodiment, as shown in FIGS. 1 to 3, the contour of the thin film piezoelectric layer 44 in the thickness direction of the diaphragm 30 described above corresponds to that of the diaphragm 30. It is disposed inside the contour of the pressure chamber 21 in the thickness direction. In other words, when the liquid discharge head 200 is projected parallel to the thickness direction of the diaphragm 30, the thin film piezoelectric layer 44 exists inside the pressure chamber 21.

  In the present specification, when describing the outline of a member in the thickness direction of the diaphragm 30, or when describing a state of projecting in parallel with the thickness direction of the diaphragm 30, it is simply viewed "in plan view" or "planarly And so on.

The material of the thin film piezoelectric layer 44 has a large elastic modulus as compared with the diaphragm 30 and electrodes and the like. Therefore, when the thin film piezoelectric layer 44 is in structural contact with the pressure chamber substrate 20, even if the thin film piezoelectric layer 44 is deformed, the deformation may be suppressed by the pressure chamber substrate 20. As a result, the diaphragm 30 is obtained. Displacement may be suppressed (inhibited). However, the outer periphery of the thin film piezoelectric layer 44 does not overlap the pressure chamber substrate 20 by arranging the thin film piezoelectric layer 44 to be present inside the pressure chamber 21 in a plan view (structurally the thin film piezoelectric Since the layer 44 and the pressure chamber substrate 20 do not contact each other, the deformation of the thin film piezoelectric layer 44 can sufficiently contribute to the displacement of the diaphragm 30. In other words, in the arrangement of the present embodiment, the deformation of the diaphragm 30 is unlikely to be inhibited by the thin film piezoelectric layer 44. Thereby, the displacement amount of the diaphragm 30 can be further increased.

1.6.2. Thin Film Piezoelectric Layer and Lead Diffusion Suppression Layer In the liquid discharge head 200 of the present embodiment, the outline of the thin film piezoelectric layer 44 in plan view is disposed the same as or inside the outline of the lead diffusion suppression layer 50 in plan view. In other words, when the liquid discharge head 200 is projected in parallel to the thickness direction of the diaphragm 30, the thin film piezoelectric layer 44 exists inside the lead diffusion suppression layer 50. In the liquid discharge head 200 of the present embodiment, the lead diffusion suppression layer 50 suppresses the diffusion of the lead of the thin film piezoelectric layer 44 to the diaphragm 30. Therefore, the outline of the lead diffusion suppression layer 50 in plan view may coincide with the outline of the thin film piezoelectric layer 44.

  The diffusion of lead is likely to occur at the time of firing of the thin film piezoelectric layer 44 and diffuses through an object (solid). Therefore, the lead diffusion suppression layer 50 may be present between the thin film piezoelectric layer 44 and the diaphragm 30 at the time of firing. Further, since diffusion of lead is less likely to occur through the gas (space) at the time of firing, the contour of the lead diffusion suppression layer 50 in plan view coincides with the contour of the thin film piezoelectric layer 44 during firing. Even if it is big, it is enough. When the outline of the lead diffusion suppression layer 50 in plan view is larger than the outline of the thin film piezoelectric layer 44 during baking, the lead diffusion suppression layer 50 may be patterned after baking. If the patterning of the lead diffusion suppression layer 50 is performed together with the thin film piezoelectric layer 44 before or after firing, the contour of the lead diffusion suppression layer 50 in plan view corresponds to the contour of the thin film piezoelectric layer 44 It may match.

1.6.3. Lead Diffusion Suppression Layer and First Electrode The lead diffusion suppression layer 50 can exhibit the function of suppressing the diffusion of lead if it is disposed between the diaphragm 30 and the thin film piezoelectric layer 44, but in this section The positional relationship with the electrode 42 and the like will be described.

  The lead diffusion suppression layer 50 is provided between the diaphragm 30 and the first electrode 42 in the embodiment disposed between the diaphragm 30 and the thin film piezoelectric layer 44 in the example of FIGS. 1 to 3. ing. In this way, since the lead diffusion suppression layer 50 is not included in the piezoelectric element 40, the piezoelectric performance of the piezoelectric element 40 is not easily inhibited. The same applies to the case where the first electrode 42 is an individual electrode of each piezoelectric element 40 as described above, but the outline of the first electrode 42 is on the inner side of the outline of the thin film piezoelectric layer 44 in plan view. In some cases, the outline of the lead diffusion suppression layer 50 is disposed outside the outline of the first electrode 42 and is equal to or larger than the outline of the thin film piezoelectric layer 44.

  On the other hand, when the lead diffusion suppression layer 50 has conductivity, the lead diffusion suppression layer 50 may function as an auxiliary electrode that assists the conductivity of the first electrode 42. That is, when the lead diffusion suppression layer 50 has conductivity, the lead diffusion suppression layer 50 is disposed between the diaphragm 30 and the thin film piezoelectric layer 44 as in the example of FIGS. 1 to 3. In the embodiment, it may be provided between the diaphragm 30 and the first electrode 42. In this case, the lead diffusion suppression layer 50 may be appropriately patterned.

Furthermore, in the case where the lead diffusion suppression layer 50 has conductivity, the thin film piezoelectric layer 44 and the thin film piezoelectric layer 44 of the embodiment in which the lead diffusion suppression layer 50 is disposed between the diaphragm 30 and the thin film piezoelectric layer 44. It may be provided between one electrode 42 and the other. In this way, the lead diffusion suppression layer 50 can function as an auxiliary electrode that assists the conductivity of the first electrode 42. Further, in this case, when the lead diffusion suppression layer 50 is formed of Ir, IrO _x , a composite oxide or the like having relatively high conductivity, the lead diffusion suppression layer 50 may be used as the first electrode 42. In this case, the piezoelectric element 40 includes the lead diffusion suppression layer 50 (first electrode 42), the thin film piezoelectric layer 44, and the second electrode 46. In this case, the first electrode 42 may be considered to function as the lead diffusion suppression layer 50.

  In the case where the lead diffusion suppression layer 50 has conductivity, and is provided between the thin film piezoelectric layer 44 and the first electrode 42, the first electrode 42 as described above may be each piezoelectric element. The same applies to the case of 40 individual electrodes. That is, when the outline of the first electrode 42 is inside the outline of the thin film piezoelectric layer 44 in plan view, the outline of the lead diffusion suppression layer 50 is outside the outline of the first electrode 42, and the thin film piezoelectric The lead diffusion suppressing layer 50 may be arranged to be equal to or larger than the contour of the body layer 44, thereby complementing the conductivity of the first electrode 42 or functioning as the first electrode 42. it can. Further, in the case where the lead diffusion suppression layer 50 has conductivity, and the first electrode 42 is integral with the lead diffusion suppression layer 50, or in the case where the first electrode 42 is not provided, the lead diffusion suppression layer 50 can also be considered as the first electrode 42, and in those cases, it may be considered that the first electrode 42 functions as the lead diffusion suppression layer 50.

1.6.4. Lead Diffusion Suppression Layer and Diaphragm The lead diffusion suppression layer 50 is defined as a layer of the above-described material that first appears in the direction from the thin film piezoelectric layer 44 toward the diaphragm 30. That is, when there is a layer of a material that can be the lead diffusion suppression layer 50 in the diaphragm 30, the layer is not regarded as the lead diffusion suppression layer 50, and is regarded as a layer constituting the diaphragm 30. . When the diaphragm 30 is made of a single layer and the single layer is a material that can be the lead diffusion suppression layer 50, the single layer is regarded as the lead diffusion suppression layer 50 even if it is regarded as the diaphragm 30. May be

1.7. Other Configurations The liquid discharge head 200 of the present embodiment shown in FIGS. 1 to 3 includes an insulating layer 60 and a wiring layer 70. The wiring layer 70 is a lead wiring of the second electrode 46. The insulating layer 60 has a function of insulating the wiring layer 70 from the first electrode 42.

  The insulating layer 60 is provided to cover at least a part of the side surface of the first electrode 42 and the thin film piezoelectric layer 44. In the illustrated example, the insulating layer 60 is provided only in the region under the wiring layer 70. The top surface of the insulating layer 60 may not be horizontal as shown in FIG. The insulating layer 60 is provided to ensure insulation between the first electrode 42 and the wiring layer 70. As a material of the insulating layer 60, either an inorganic substance or an organic substance can be used. Among them, from the viewpoint of hardly inhibiting the displacement of the diaphragm 30, a material having a small Young's modulus (elastic modulus) is preferable. For example, the material of the insulating layer 60 is preferably silicon oxide or various polymers.

  The wiring layer 70 is provided above the insulating layer 60. The wiring layer 70 may be provided in contact with the thin film piezoelectric layer 44. The wiring layer 70 is electrically connected to the second electrode 46. The wiring layer 70 is electrically insulated from the first electrode 42 by at least the insulating layer 60. The wiring layer 70 electrically connects the second electrode 46 to an external circuit (not shown). As a material of the wiring layer 70, various metals such as nickel, iridium, gold, platinum and the like can be used, and a single layer structure or a multilayer structure of these may be used.

  The liquid discharge head 200 of the present embodiment may further include an appropriate configuration. As such a configuration, for example, a space covering the piezoelectric element 40 is formed, and a protective substrate for suppressing mechanical damage of the piezoelectric element 40 and the diaphragm 30, a semiconductor integrated circuit for driving the piezoelectric element 40 ( Circuit boards including ICs). Also, between the diaphragm 30 and the first electrode 42, between the first electrode 42 and the thin film piezoelectric layer 44, between the thin film piezoelectric layer 44 and the second electrode 46, between the diaphragm 30 and the lead diffusion suppression layer 50 Between the lead diffusion suppression layer 50 and the first electrode 42, and between the lead diffusion suppression layer 50 and the thin film piezoelectric layer 44, to improve adhesion between the layers, or a crystal of the material of the lead diffusion suppression layer 50. For the purpose of controlling the properties, for example, a layer containing titanium (Ti) may be formed.

Although not shown, a liner layer is formed on part or all of the wall surface which divides the pressure chamber 21, that is, the side of the diaphragm 30 on the pressure chamber 21 side or the side surface of the pressure chamber substrate 20 which divides the pressure chamber 21. It may be provided. The liner layer may have a function of suppressing corrosion of the diaphragm 30 and the pressure chamber substrate 20 by a liquid (ink or the like) introduced into the pressure chamber 21. Examples of the material of the liner layer include TaO _x , parylene (polyxylylene) and the like.

1.8. Method of Manufacturing Liquid Ejection Head The liquid ejection head 200 can be manufactured, for example, as follows. The layer to be the diaphragm 30 on a silicon substrate, the layer to be the lead diffusion suppression layer 50, the layer to be the first electrode 42, the layer to be the thin film piezoelectric layer 44, and the layer to be the second electrode 46 , Sputtering method, vacuum evaporation method, sol-gel method or the like. These steps may include masking and patterning steps as appropriate and necessary. The firing of the thin film piezoelectric layer 44 can be performed at an appropriate timing. In addition, in the sol-gel method, a series of operations of raw material solution application, preheating, and crystallization annealing may be repeated several times to obtain a desired film thickness. Thus, a structure in which the diaphragm 30, the lead diffusion suppression layer 50, and the piezoelectric element 40 are formed in a predetermined shape on the silicon substrate can be obtained. The insulating layer 60 can be formed by, for example, a spin-on-glass (SOG) method, an inkjet method, or the like, and can be patterned as necessary. The wiring layer 70 can be formed, for example, by a method such as sputtering, vacuum evaporation, CVD, electroless plating, etc., and then patterned. Then, the pressure chamber substrate 20 is formed by etching the silicon substrate from the side opposite to the surface on which the layer is formed, using a suitable mask. The nozzle plate 10 is manufactured, for example, by cutting a stainless steel plate and perforating the nozzle hole 11 at a predetermined position. The pressure plate 30 including the diaphragm 30, the lead diffusion suppressing layer 50, the piezoelectric element 40, and the nozzle plate 10 manufactured as described above are fixed to predetermined positions using known alignment means etc., if necessary. The liquid discharge head 200 is manufactured by assembling using the same.

1.9. Operation and Effect According to the liquid discharge head 200 of the present embodiment, the contour of the thin film piezoelectric layer 44 in the thickness direction of the diaphragm 30 is disposed inside the contour of the pressure chamber 21 in the thickness direction of the diaphragm 30. Therefore, the restraint of the displacement of the diaphragm 30 by the relatively hard thin film piezoelectric layer 44 is structurally suppressed. Therefore, the amount of displacement of the diaphragm 30 can be increased. Further, by providing the lead diffusion suppression layer 50 between the diaphragm 30 and the thin film piezoelectric layer 44, even if the firing temperature of the thin film piezoelectric layer 44 is increased, the lead is diffused to the diaphragm 30. It can be suppressed. Thereby, the piezoelectric characteristics of the piezoelectric element 40 can be enhanced, the displacement amount of the diaphragm 30 can be increased, and the embrittlement of the diaphragm 30 due to lead can be suppressed, so the diaphragm 30 is not easily damaged. It is possible to improve the reliability.

  The liquid discharge head 200 of the present embodiment is, for example, a recording head used for an image recording apparatus such as a printer, a color material discharge head used for manufacturing a color filter such as a liquid crystal display, an organic EL display, FED (surface emitting display) It can also be suitably used as a liquid material discharge head used to form an electrode of an electrophoretic display or the like and a color filter, and a bio-organic material discharge head used to manufacture a biochip.

2. Printer Next, a printer according to the present embodiment will be described with reference to the drawings. FIG. 4 is a perspective view schematically showing the printer 300 according to the present embodiment.

  A printer according to the present invention includes the liquid discharge head according to the present invention. Hereinafter, the printer 300 including the liquid discharge head 200 will be described as an example.

  The printer 300 is an inkjet printer. The printer 300 includes a head unit 310, as shown in FIG. The head unit 310 has a liquid discharge head 200. The number of liquid discharge heads 200 constituting the head unit 310 is not particularly limited. In the head unit 310, cartridges 312 and 314 are provided detachably. The carriage 316 has a head unit 310 mounted thereon, and is axially movable on a carriage shaft 322 attached to the apparatus main body 320.

  In the printer 300, the driving force of the drive motor 330 is transmitted to the carriage 316 via a plurality of gear wheels (not shown) and the timing belt 332. Thus, the carriage 316 is moved along the carriage shaft 322. On the other hand, the apparatus main body 320 is provided with a conveyance roller 340 as a conveyance means, and the recording sheet S which is a recording medium such as paper is conveyed by the conveyance roller 340. The conveyance means for conveying the recording sheet S is not limited to the conveyance roller, and may be a belt, a drum or the like.

  The printer 300 includes a printer controller 350. The printer controller 350 is electrically connected to a circuit board (not shown) of the liquid discharge head 200. The printer controller 350 generates, for example, a RAM for temporarily storing various data, a ROM for storing control programs and the like, a control unit including a CPU and the like, and a drive for generating a drive signal to be transmitted to the liquid discharge head 200. A signal generation circuit etc. are provided.

  Since the printer 300 includes the above-described liquid discharge head 200, it has sufficient ink discharge performance and reliability.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the invention includes configurations substantially the same as the configurations described in the embodiments (for example, configurations having the same function, method and result, or configurations having the same purpose and effect). The present invention also includes configurations in which nonessential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that can achieve the same effects or the same objects as the configurations described in the embodiments. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 10 nozzle plate 11 nozzle hole 20 pressure chamber board 21 pressure chamber 22 communication path 30 diaphragm 40 piezoelectric element 42 first electrode 44 thin film piezoelectric layer 46 ... second electrode, 50 ... lead diffusion suppression layer, 60 ... insulating layer, 70 ... wiring layer, 200 ... liquid discharge head, 300 ... printer, 310 ... head unit, 312, 314 ... cartridge, 316 ... carriage, 320 ... device Body, 322: Carriage shaft, 330: Drive motor, 332: Timing belt, 340: Conveying roller, 350: Printer controller

Claims (8)

With a pressure chamber,
A diaphragm forming a wall of the pressure chamber;
A piezoelectric element having a first electrode formed on the diaphragm, a thin film piezoelectric layer containing lead formed on the first electrode, and a second electrode formed on the thin film piezoelectric layer; ,
A lead diffusion suppression layer provided between the diaphragm and the thin film piezoelectric layer;
Have
The contour of the thin film piezoelectric layer in the thickness direction of the diaphragm is disposed inside the contour of the pressure chamber in the thickness direction of the diaphragm. In claim 1,
The liquid discharge head, wherein the diaphragm has a laminated structure. In claim 2,
The diaphragm includes a first layer, and second and third layers sandwiching the first layer,
The liquid discharge head, wherein the second layer and the third layer have the same composition. In any one of claims 1 to 3,
The lead diffusion suppression layer is conductive, and is provided between the first electrode and the thin film piezoelectric layer. In any one of claims 1 to 3,
The liquid discharge head, wherein the lead diffusion suppression layer is provided between the diaphragm and the first electrode. In any one of claims 1 to 5,
The thickness of the thin film piezoelectric layer is 3 μm or less. With a pressure chamber,
A diaphragm forming a wall of the pressure chamber;
A piezoelectric element having a first electrode formed on the diaphragm, a thin film piezoelectric layer containing lead formed on the first electrode, and a second electrode formed on the thin film piezoelectric layer; ,
Have
The contour of the thin film piezoelectric layer in the thickness direction of the diaphragm is disposed inside the contour of the pressure chamber in the thickness direction of the diaphragm.
The first electrode functions as a lead diffusion suppression layer. A printer comprising the liquid discharge head according to any one of claims 1 to 7.

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