JP2019110706A - Vibration power generation device - Google Patents

Abstract

To provide a vibration power generation device that can suppress a decline in the power generation capacity.SOLUTION: A vibration power generation device 50 includes a pair of piezoelectric element laminates 10 (10A, 10B), a weight body 51 disposed between the pair of piezoelectric element laminates, and a fixing member 52 disposed between the pair of piezoelectric element laminates. The piezoelectric element laminate includes a piezoelectric element 1 (1A, 1B) having a substrate 11 and a plurality of piezoelectric members 12 disposed on the substrate, and a printed wiring board 2 (2A, 2B) having an opening 21 disposed on the surface opposite to the weight body side of the piezoelectric element. The piezoelectric element has a piezoelectric body in a first area A which is an area where the substrate and the opening overlap in a plan view, and each of the piezoelectric element laminate is fixed to a weight body in the first area of the substrate.SELECTED DRAWING: Figure 3

Description

  Embodiments of the present disclosure relate to a vibration power generation device that converts vibrational energy into electrical energy.

  As one of power generation devices using energy harvesting (environmental power generation) technology that generates power from environmental energy such as heat, light and vibration, development of vibration power generation devices is in progress.

  In a vibration power generation device, a piezoelectric element is generally used as a power generation element, and bending vibration occurs in the piezoelectric element by the action of an external force, and pressure generated on the vibration surface is converted to electric power by the change amount of deflection at that time. (Refer patent document 1, 2). As the structure of the piezoelectric element, for example, a cantilever structure having one fixed end and a movable end supporting a weight body and acting on vibration, two fixed ends and an action point of vibration located therebetween A double-ended beam (both-ends support beam) structure is known.

JP, 2007-202293, A JP, 2008-192944, A

  The present inventors, as a new vibration power generation device, have a structure in which a weight body is disposed between the action points of vibration of a pair of opposing piezoelectric elements, and more specifically, the above-mentioned opening on a printed wiring board having an opening. We have developed a structure in which the piezoelectric elements of two piezoelectric element stacks are connected by a weight body using the piezoelectric element stack in which the piezoelectric elements are mounted so as to overlap in plan view. Here, since the piezoelectric element can generate a large amount of current as the amount of change in deflection caused by the bending vibration caused by the external force increases, the inventors of the present invention have found useless vibration of the piezoelectric element in the vibration power generation device having the above structure. The two piezoelectric element laminates are fixed by a fixing member in order to increase the amount of vibrational energy generated by receiving an external force and bending and vibrating while controlling. However, it has been found that even with such a structure, a desired power generation capacity may not be obtained.

  The inventors of the present invention conducted intensive studies to solve the above problems, and even if the two piezoelectric element laminates are fixed by the fixing member, the initial deflection of the piezoelectric elements becomes large depending on the arrangement order of the piezoelectric element laminates. It was found that the power generation capacity of the vibration power generation device is reduced as a result of the decrease in the amount of change in deflection of the piezoelectric element due to the action of the external force.

  The present disclosure has been made in view of the above problems, and provides a vibration power generation device capable of reducing initial deflection of piezoelectric elements in a pair of piezoelectric element stacks and suppressing a decrease in power generation capacity. As the main purpose.

  With respect to the above-mentioned problems, as a result of further intensive investigations by the present inventors et al., Initial deflection of the piezoelectric element is caused by the influence of dimensional tolerances of other members such as a printed wiring board and a fixing member located between a pair of piezoelectric elements. Was identified to be larger. Therefore, the present inventors have solved the above problems by reducing the number of other members positioned between the piezoelectric elements of the pair of piezoelectric element stacks and reducing the dimensional tolerance between the pair of piezoelectric elements. .

  That is, the present disclosure is a vibration having a pair of piezoelectric element stacks, a weight body disposed between the pair of piezoelectric element stacks, and a fixing member disposed between the pair of piezoelectric element stacks. A power generation device, wherein the piezoelectric element laminate is disposed on a surface of the piezoelectric element having a substrate and a plurality of piezoelectric bodies disposed on the substrate, and a surface of the piezoelectric element opposite to the weight body side. And a printed wiring board having an opening, wherein the piezoelectric element has the piezoelectric body in a first area which is an area where the substrate and the opening overlap in plan view, and each of the piezoelectric elements is stacked. The body provides a vibrational power generation device secured to the weight in the first region of the substrate.

  Further, the present disclosure is a vibration having a pair of piezoelectric element stacks, a weight body disposed between the pair of piezoelectric element stacks, and a fixing member disposed between the pair of piezoelectric element stacks. A power generation device, wherein the piezoelectric element laminate includes a piezoelectric element having a substrate and a plurality of piezoelectric bodies disposed on the substrate, and a printed wiring board having an opening, and the substrate of the piezoelectric element And the weight body are joined by welding.

  The present disclosure provides a vibration power generation device in which the weight body and the substrate of the piezoelectric element are formed of the same metal.

  In the present disclosure, a vibration power generation device is provided in which the metal is SUS304.

  Further, the present disclosure is a method of manufacturing a vibration power generation device described above, including a bonding step of welding the substrate of the piezoelectric element of the piezoelectric element laminate and the weight body by welding. Provide a method of manufacturing a device.

  According to the present disclosure, variation in initial deflection of the pair of piezoelectric elements is reduced, and it is possible to prevent an increase in bending stiffness of the piezoelectric element due to the initial deflection and to suppress a decrease in power generation capacity for individual devices. It is possible to provide a vibration power generation device.

1 is a schematic perspective view showing an example of a vibration power generation device of the present disclosure. It is a schematic plan view showing an example of a vibration power generation device of the present disclosure. It is the ZZ sectional view taken on the line of FIG. It is a schematic sectional drawing which shows the other structure of a vibration electric power generation device. It is an enlarged plan view of the area | region P of FIG. It is a schematic diagram explaining the aspect of the several piezoelectric material on the board | substrate in a piezoelectric element. It is a schematic plan view which shows an example of a piezoelectric element. It is a schematic plan view which shows an example of a printed wiring board. It is a schematic perspective view which shows an example of a weight body. It is a schematic diagram explaining the arrangement position of a fixing member. It is a schematic sectional drawing which shows the other example of the vibration electric power generation device of this indication. It is a schematic sectional drawing which shows the structure of the simulation model of the vibration electric power generation device of a reference example and a reference comparative example. It is a schematic plan view and a sectional view of each member in a simulation model of a vibration power generation device. It is a graph which shows the simulation result of _Tad dependence of the output electric power of a vibration power generation element.

  In the present specification, when there is a certain configuration such as a certain member or a certain region “above (or below)” another configuration such as another member or another region, unless otherwise specified, This includes not only directly above (or just below) other configurations, but also above (or below) other configurations, ie, other configurations between (or below) other configurations. Also includes the case where the element is included.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings and the like. However, the present disclosure can be implemented in many different aspects, and is not construed as being limited to the description of the embodiment exemplified below. In addition, the drawings may be schematically represented with respect to the width, thickness, shape, etc. of each portion in comparison with the embodiment in order to clarify the description, but this is merely an example, and the interpretation of the present disclosure is limited. It is not something to do. In the specification and the drawings, the same elements as those described above with reference to the drawings already described may be denoted by the same reference numerals, and the detailed description may be appropriately omitted. Moreover, although it may be demonstrated using the words "upper" or "lower" for convenience of explanation, the vertical direction may be reversed.

I. Vibration Power Generation Device First, the vibration power generation device of the present disclosure will be described. The piezoelectric element laminate of the present disclosure is roughly divided into two modes.

A. First Aspect A first aspect of the vibration power generation device of the present disclosure (hereinafter, this vibration may be referred to as the vibration power generation device in this section) includes a pair of piezoelectric element laminates and the pair of piezoelectric element laminates. A vibration generating device having a weight body disposed on the upper surface and a fixing member disposed between the pair of piezoelectric element stacks, wherein the piezoelectric element stack is disposed on a substrate and the substrate A piezoelectric element having a plurality of piezoelectric bodies; and a printed wiring board having an opening disposed on the surface of the piezoelectric element opposite to the weight body side, the piezoelectric element comprising the substrate and the piezoelectric element. The piezoelectric body is provided in a first area which is an area overlapping the opening in plan view, and each of the piezoelectric element stacks is fixed to the weight body in the first area of the substrate.

  The vibration power generation device of this aspect will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing an example of the vibration power generation device of the present embodiment, and FIG. 2 is a schematic plan view of FIG. FIG. 3 is a cross-sectional view taken along the line Z-Z of FIG. The vibration power generation device vibration power generation device 50 of this embodiment includes a pair of piezoelectric element stacks 10A and 10B, a weight body 51 disposed between the pair of piezoelectric element stacks 10A and 10B, and a pair of piezoelectric element stacks 10A. , 10B, and a fixing member 52. The piezoelectric element laminates 10A and 10B are respectively the substrate 1 and the piezoelectric elements 1A and 1B having the plurality of piezoelectric bodies 12 disposed on the substrate 1, and the surfaces of the piezoelectric elements 1A and 1B opposite to the weight body 51 side. It has printed wiring boards 2A and 2B which have opening 21 arranged on the top. The piezoelectric elements 1A and 1B have a piezoelectric body 12 in a first area A where the substrate 11 and the opening 21 of the printed wiring board 2 overlap in a plan view. A region located on the outer side from the outer periphery 21 a of the opening 21 and overlapping the substrate 11 and the printed wiring boards 2A and 2B in plan view is a second region B. The respective piezoelectric element stacks 10A and 10B are fixed to the weight body 51 in the first region A of the substrate 11 of the piezoelectric elements 1A and 1B. Further, in the example shown in FIGS. 1 to 3, the respective piezoelectric element laminates 10A and 10B are connected and fixed to the fixing member 52 on the surface of the printed wiring boards 2A and 2B on the side of the piezoelectric elements 1A and 1B. .

  The present inventors use a piezoelectric element laminate in which a piezoelectric element is mounted on a printed wiring board having an opening so as to overlap the opening in a plan view, and overlaps the piezoelectric elements of two piezoelectric element laminates. We have developed a new vibration power generation device that has a structure in which it is connected by a weight and the two piezoelectric element laminates are fixed by a fixing member. Since the piezoelectric element can generate a large amount of current as the amount of change in deflection caused by the bending vibration caused by the external force increases, according to the above-described structure, the two piezoelectric element laminates are fixed by the fixing member. While controlling unnecessary vibration of the piezoelectric element, it is possible to increase the amount of vibration energy generated by bending vibration due to an external force. However, it has been found that even with such a structure, a desired power generation capacity may not be obtained.

  With respect to the above-mentioned problems, as a result of intensive investigations by the present inventors etc., the initial deflection of the piezoelectric element becomes large and the bending rigidity of the piezoelectric element is increased by the arrangement order of the piezoelectric element laminate in the structure of the vibration power generation device. It was found that the amount of change in deflection of the piezoelectric element is smaller than in the case where there is no initial deflection for the action of an external force of equal magnitude. Then, when the amount of change in bending of the piezoelectric element decreases, the amount of change in stress applied to the piezoelectric layer of the piezoelectric element decreases, that is, the amount of generated charge decreases, and as a result, the power generation capacity of the vibration power generation device decreases. I learned that I would do it. The inventors of the present invention conducted further studies on the cause of the increase in initial deflection of the piezoelectric element, and as a result, the influence of dimensional tolerances of other members such as a printed wiring board and a fixing member located between a pair of piezoelectric elements. It was identified that.

  According to the vibration power generation device of this aspect, the initial deflection of the piezoelectric element is achieved by reducing the number of other members between the piezoelectric elements of the pair of piezoelectric element laminates and reducing the dimensional tolerance between the pair of piezoelectric elements. Can be reduced, and an increase in bending stiffness due to initial deflection can be suppressed. Specifically, since hardening of the spring which is a non-linear phenomenon of the beam portion of the substrate of the piezoelectric element is suppressed, it is possible to prevent an increase in bending rigidity of the piezoelectric element. Then, by bringing the flexural rigidity of the actual piezoelectric element close to the design value, the desired vibration of the weight body can be generated by the action of the external force. Therefore, the vibration power generation device of this aspect can suppress the fall of power generation capacity.

  In the vibration power generation device of this aspect, when an external force acts, the force applied in the axial direction of the weight body by the reaction thereof is convex with respect to the direction in which the external force acts, the substrate of the piezoelectric element in the piezoelectric element laminate Make a bend. Since the substrate of the piezoelectric element is thin and has a low bending rigidity to the extent that the weight body can vibrate by an external force, the piezoelectric element contracts and displaces, and the displacement increases and the repulsive force increases and is displaced due to reversal. Vibrations of the mechanical mechanical spring-mass system occur. By repetition of such displacement, the piezoelectric element can be bent and vibrated to generate an alternating current.

The effect by the structure of the vibration power generation device of this aspect is demonstrated in more detail. As a structure of a vibration power generation device having a pair of piezoelectric element laminates, a weight body, and a fixing member, for example, as shown in FIG. 4, printed wiring boards 2A and 2B of the pair of piezoelectric element laminates 10A and 10B are The structure arrange | positioned in the surface by the side of weight body 51 of piezoelectric element 1A, 1B, respectively is also assumed. In the case of the structure illustrated in FIG. 4, a total of three members, two types of printed wiring boards 2A and 2B and a fixing member 52, are provided between the pair of piezoelectric elements 1A and 1B. Assuming that the dimensional tolerance of the fixing member 52 is δl _A, and the dimensional tolerances of _the printed wiring boards 2A and 2B are δl _B1 and δl _B2 , respectively, the dimensional tolerance δ shown by the following formula (1) is between the pair of piezoelectric elements 1A and 1B. It will occur.

Here, the dimensions of and the printed wiring board of the fixed member, means the length in the axial direction in which the weight body is oscillated in the primary vibration mode, the direction of X ₃ if 1 length Say. Specifically, the dimension of the fixing member refers to the thickness of the component inserted between the printed wiring boards 2A and 2B in the axial direction of the weight body. In addition, in the case of the dimensions of a printed wiring board, it refers to the thickness of the insulating substrate including the resist and the wiring located in the portion in contact with the fixing member.

Moreover, the dimensional tolerance of each member is specifically a statistical error of the dimension generated at the time of machining, and as an actual measurement value, the dimension of the machined part is measured and the standard deviation is calculated from them. It can be calculated by For example, with a common tolerance specified in JIS B 0 405: 1991, δl _A is equal to ± l mm in fine grade (f) when the part thickness is more than 6 mm and 30 mm or less, δl _B1 is equal to δl _B2 and is standard The manufacturing specification is approximately ± 0.2 mm, and in this case, δ is ± 0.3 mm. The piezoelectric element is fixed to the printed wiring board via, for example, a solder bump, but the tolerance of the height of the solder bump is usually about ± 0.01 mm, which is sufficiently smaller than the dimensional tolerance of members. It can be ignored.

  As the dimensional tolerance of each member positioned between the pair of piezoelectric elements is larger, the overall dimensional tolerance between the pair of piezoelectric elements is larger, and as a result, the variation in initial deflection of each piezoelectric element is larger. Among them, since the printed wiring board generally has a large allowable range of dimensional tolerance, in the structure in which the printed wiring board is positioned between the pair of piezoelectric elements, the dimensional tolerance calculated from the equation (1) is further increased. It is assumed that the variation of the initial deflection of is further increased.

On the other hand, in the vibration power generation device of this embodiment, as shown in FIG. 3, the printed wiring boards 2A and 2B of the pair of piezoelectric element laminates 10A and 10B are the weight 2 side of the piezoelectric elements 1A and 1B, respectively. And a structure disposed on the opposite side of For this reason, one type of fixing member 52, a total of one member, is provided between the pair of piezoelectric elements 1A and 1B. Then, assuming that the dimensional tolerance of the fixing member 51 is δl _A , the dimensional tolerance δ shown by the following equation (2) occurs between the pair of piezoelectric elements 1A and 1B, and the dimension between the pair of piezoelectric elements is obtained according to equation (1) The number of factors that determine the tolerance δ can be reduced.

For example, δ is equal to δl _A with a common tolerance defined in JIS B 0 405: 1991, and it becomes ± 0.1 mm in fine grade (f) when the thickness of the part is more than 6 mm and 30 mm or less. This is significantly smaller than ± 0.3 mm which is δ in the case where the thickness of the insulating substrate of the printed wiring board is included in the above-mentioned formula (1).

  Thus, in the vibration power generation device of this aspect, the dimensional tolerance occurring between the pair of piezoelectric elements is sufficient in consideration of the dimensional tolerance of the fixing member, so the dimensional tolerance between the pair of piezoelectric elements can be reduced. Initial deflection of the piezoelectric element caused by the influence of dimensional tolerance can also be reduced. Therefore, the vibration power generation device of this aspect can suppress the decrease in the power generation capacity.

  Hereinafter, each structure in the vibration power generation device of this aspect is demonstrated.

1. Piezoelectric Element Laminate The piezoelectric element laminate in the vibration power generation device of the present aspect is a piezoelectric element having a substrate and a plurality of piezoelectric bodies disposed on the substrate, and a surface of the piezoelectric element on the opposite side to the weight body side. The piezoelectric element has the piezoelectric body in a first area, which is an area where the substrate and the opening overlap in a plan view. In the vibration power generation device of this aspect, two piezoelectric element laminates are arranged in pairs via weight bodies.

  In the piezoelectric element laminate, the opening side of the printed wiring board is "inside", and the outer peripheral side of the printed wiring board is "outside". The outer periphery of the opening refers to the outer edge that forms the contour of the opening, and the shape in plan view of the opening refers to a shape (an outer peripheral shape) surrounded by the outer periphery in plan view. Moreover, the outer periphery of a printed wiring board means the outer edge which makes the outline of a printed wiring board except an opening part.

  The piezoelectric element laminate in this aspect has a first area which is an area where the substrate of the piezoelectric element and the opening of the printed wiring board overlap in plan view. The first area is an area indicated by reference numeral A in FIGS. 1 to 3, and the size of the first area corresponds to the size of the opening of the printed wiring board.

Further, the piezoelectric element laminate in this aspect is a second area which is an area where the substrate and the printed wiring board are stacked in an overlapping manner in a plan view at a position corresponding to the outer side from the outer periphery of the opening. Have. The second region is a region indicated by reference numeral B in FIGS. Width of the second region (the length indicated by W ₂ in FIG. 5) is preferably smaller than the width of the outer periphery of the opening to the outer periphery of the printed circuit board (the length indicated by W ₁ in FIG. 5). This is because the fixing member can be disposed outside the second region. 5 is an enlarged plan view of the region P of FIG. The width of the second region refers to the distance between the outer periphery and the inner periphery of the second region, specifically, the linear distance between the outer periphery of the opening and the outer periphery of the substrate of the piezoelectric element.

(1) Piezoelectric Element The piezoelectric element of the piezoelectric element laminate in this aspect has a substrate and a plurality of piezoelectric bodies disposed on the substrate. The piezoelectric element has the piezoelectric body in the first region.

(A) Piezoelectric Body The piezoelectric body has a piezoelectric layer and a current collecting layer disposed on the piezoelectric layer. The piezoelectric element can be electrically connected to the printed wiring board in the current collecting layer. Here, having a plurality of piezoelectric bodies on the substrate means that a single piezoelectric layer 22 is disposed on the substrate 11 as shown in FIG. 6A, and a current collecting layer 23 is formed on the single piezoelectric layer 22. The plurality of piezoelectric bodies 12 may be provided on the substrate 11 by forming individual pieces of the current collecting layer 23 and the piezoelectric layer 22 overlapping with each other in plan view by arranging the pieces in a piece shape. As shown in (b), a plurality of piece-like piezoelectric members 12 having the piezoelectric layer 22 and the current collecting layer 23 on the piezoelectric layer 22 may be provided on the substrate 11. Above all, the structure shown in FIG. 6A is preferable in that when the piezoelectric layer is formed of, for example, aluminum nitride, the wiring from the electrode can be routed on the piezoelectric body which is also an insulator. 6 (a) and 6 (b) are schematic views for explaining the aspect of the plurality of piezoelectric bodies on the substrate in the piezoelectric element, where the right side is a plan view and the left side is a cross-sectional view.

  The material of the piezoelectric layer can be selected from materials conventionally used for piezoelectrics and ferroelectrics. As such a material, a lead-free ferroelectric material can be preferably used. Examples of the lead-free ferroelectrics include aluminum nitride (AlN); scandium-containing aluminum nitride (Sc-AlN), magnesium and niobium-containing aluminum nitride (Mg / Nb-AlN), etc .; Lead zirconate titanate containing different elements such as zinc (ZnO), lead zirconate titanate (PZT), lead zirconate titanate containing niobium (Nb-PZT) and the like; potassium sodium niobate (KNN) etc. may be mentioned. Above all, aluminum nitride (AlN) or aluminum nitride (AlN) or an environmentally friendly product that does not contain lead, a performance index determined by the value of the square of the piezoelectric constant divided by the dielectric constant, and a production technology have been established. The different element-containing aluminum nitride is preferable, and aluminum nitride (AlN) is more preferable.

  The proportion of aluminum nitride (AlN) or aluminum containing another element contained in the piezoelectric layer is preferably as large as possible, and may be, for example, 42% by mass or more, and more preferably 99% by mass or more, particularly 99. It is preferable to set it as 5 mass% or more. This is because the piezoelectric layer can be made a high density layer by not including other substances that cause a decrease in piezoelectricity.

  The thickness of the piezoelectric layer is not particularly limited, but may be, for example, 1 μm or more, and in particular, 2 μm or more is preferable. The thickness of the piezoelectric layer may be, for example, 20 μm or less, and preferably 10 μm or less.

  The current collecting layer collects charges appearing on the surface of the piezoelectric layer. As a constituent material of the above-mentioned current collection layer, the material used for the electrode in a general piezoelectric element can be applied, for example, copper, silver, gold, platinum, molybdenum, tungsten, nickel, titanium, zinc, aluminum etc. Compounds, silver compounds containing glass etc. mainly containing silica in silver, silver-lead alloys, silver-palladium alloys, silver-platinum alloys, etc., gold-lead alloys, gold-palladium alloys, gold-platinum alloys And the like. The material constituting the current collection layer may be one type or two or more types. The thickness of the current collection layer can be the same as the thickness of the electrode in a general piezoelectric element, and can be, for example, in the range of 0.05 μm to 5 μm.

  The plurality of piezoelectric bodies are disposed on at least one surface of the substrate in the first region. The piezoelectric body may be provided on the surface on the printed wiring board side, may be provided on the surface opposite to the printed wiring board side, or may be provided on both sides. Among them, in the first region, it is preferable to have the plurality of piezoelectric bodies on both surfaces of the substrate. It is because the power generation by vibration can be performed efficiently. At this time, it is preferable that the piezoelectric body disposed on one surface of the substrate and the piezoelectric body disposed on the other surface overlap in plan view. This is because the influence of the warp of the base material due to the residual stress of the piezoelectric layer can be reduced.

  The number of piezoelectric members in the piezoelectric element is not particularly limited as long as the desired power generation capability can be obtained.

(B) Substrate The substrate is a thin plate-like member that supports the piezoelectric body, and can be referred to as a diaphragm. The substrate vibrates from a position overlapping with the outer periphery of the opening in plan view due to the action of an external force. Moreover, the said board | substrate has the area | region (area | region R in FIG. 2) used as a fixed position with the weight body mentioned later.

  The substrate is required to have physical properties that allow the piezoelectric element to be bent in the direction in which the external force acts. Therefore, it is preferable that the substrate has high toughness and elasticity and low bending rigidity. Examples of such a substrate include a resin substrate and a metal substrate. Examples of the resin of the resin substrate include silicone resin, polyimide, polyethylene terephthalate, and polycarbonate. Examples of the metal of the metal substrate include stainless steel (SUS), titanium, a titanium alloy, nickel, a nickel alloy and the like. Among them, a metal substrate is preferable, and a SUS substrate is more preferable. This is because SUS substrates have high toughness, are relatively inexpensive, and are industrially easy to obtain. As stainless steel, SUS303, SUS304 etc. are mentioned, for example. Among them, SUS304 is preferable. The reason for this will be described in detail in the section “2. Weight body” described later, so the description here is omitted.

  The plan view shape of the substrate corresponds to the plan view shape of the piezoelectric element. The substrate can have a plan view shape that can be bent and oscillated by the action of an external force. The plan view shape of the substrate in the first region is not particularly limited, but is preferably a cross shape having four beam portions. By making the plan view shape of the substrate in the first region into a cross shape, the substrate is easily bent and vibrated by the action of an external force, larger vibration energy can be obtained, and it has high output and high impact reliability. Because you can do it.

  FIGS. 7A to 7C are schematic plan views showing an example of the piezoelectric element, and the plan view shape of the substrate 11 in the first region A is a cross shape having four beam portions 11 a. In the first region A, portions other than the beam portion 11a of the substrate 11 are through holes (symbol 11b in FIGS. 7A to 7C).

  The beam portion of the substrate intersects the outer periphery of the opening in the insulating substrate, and in particular, the shape of the opening in a plan view is preferably a square having a chamfered portion with four corners chamfered. At this time, it is preferable that the chamfered portion has a chamfering width equal to or larger than the width of the beam portion, and the four beam portions are orthogonal to the chamfered portion. The beam part extends in a direction intersecting with the direction in which the impact force is applied to the piezoelectric element, so the stress concentration occurring at the end of the beam part fixed to the printed wiring board is dispersed. It is because it can be made to have higher output power and high impact reliability. In FIG. 7B, the four beam portions 11a of the substrate 11 are orthogonal to the chamfered portion 21b of the square opening 21a in the insulating substrate.

  The range in which the above-described effects can be exhibited in addition to the case where the plane angle at which the beam portion and the chamfered portion intersect (hereinafter referred to as the intersection angle) is 90 ° that the four beam portions are orthogonal to the chamfered portion, respectively. In this case, the crossing angle may be larger or smaller than 90 °. Specifically, the crossing angle may be defined as a range of 90 ° ± 30 °.

  When the plan view shape of the substrate in the first region is a cross shape, the beam portion can be a double-supported beam in which both ends are fixed. The four beams 11a of the substrate 11 illustrated in FIGS. 7 (a) and 7 (b) are fixed at one end to the printed wiring board and at the other end to the beam intersection 11c. It is a beam. In the case of a cross shape having four beam portions, the beam intersection portion 11c corresponding to the intersection position of the four beam portions can have an action point of vibration, and the piezoelectric element and the weight body described later are fixed at the beam intersection portion 11c. Be done.

  In a first aspect, in the case where the plan view shape of the substrate is a cross shape, as an aspect in which one end of the beam is fixed to the printed wiring board, one end of the beam is a printed wiring board The substrate may have a peripheral frame, the end of the beam may be connected and fixed to the peripheral frame, and the peripheral frame and the printed wiring board may be formed of the opening. It may be laminated and fixed outside the outer periphery. In the substrate illustrated in FIGS. 7A and 7B, one end of each of the four beam portions is connected and fixed to the outer peripheral frame, and the substrate illustrated in FIG. Each of the two beam portions is fixed to the printed wiring board at one end. The end portion of the beam portion of the substrate or the outer peripheral frame of the substrate can be fixed to the printed wiring board via, for example, an adhesive layer described later.

  When the substrate has an outer peripheral frame, the shape of the outer peripheral frame in plan view is not particularly limited as long as it does not overlap the opening of the printed wiring board in plan view and can be laminated outside the outer periphery of the opening. For example, it may be designed appropriately according to the plan view shape of the opening of the printed wiring board, such as a square, a polygon other than a square, or a circle. The quadrilaterals and polygons include regular squares and regular polygons. In addition, the corners of the quadrangle or polygon may be chamfered.

  The width and effective length of the beam portion of the substrate are not particularly limited, and the size and the number of the piezoelectric members to be mounted, the sizes of the substrate and the opening, and the vibration tendency of the weight body to the externally applied vibration. It can design suitably according to resonance frequency, a power generation range, etc. which are required supposing. In addition, the effective length of a beam part means the length of the area | region which can be vibrated in the beam part to which both ends were fixed. The plurality of beam portions in the substrate preferably have equal effective lengths and preferably equal widths.

  The size of the substrate is not particularly limited, and can be appropriately designed according to the size of the piezoelectric element and the size of the vibration power generation device using the piezoelectric element laminate.

  The substrate preferably has a thickness capable of exhibiting the above-mentioned physical properties, and can be, for example, 10 μm or more, and in particular, 20 μm or more, particularly 25 μm or more. The thickness of the substrate can be 1000 μm or less, preferably 500 μm or less, and particularly preferably 100 μm or less. By setting the thickness of the substrate within the above range, the piezoelectric body can be supported, and vibration can be performed by the action of an external force.

(C) Others The method of forming the piezoelectric element is not particularly limited. For example, chemical deposition such as chemical vapor deposition (CVD), metal organic decomposition (MOD), sol-gel method, sputtering, or the like for the substrate It is obtained by direct film formation by physical deposition such as molecular beam epitaxy and pulsed laser deposition (PLD), and processing into a desired shape to form a piezoelectric body. Further, the piezoelectric element can be obtained by preparing a substrate processed into a desired shape in advance, and bonding and fixing a piezoelectric body to a region located in the first region of the substrate using an adhesive or the like. At this time, the piezoelectric body can be formed using a known method such as a sintering method.

(2) Printed Wiring Board The printed wiring board of the piezoelectric element laminate in this aspect is disposed on the surface of the piezoelectric element opposite to the weight body side, and has an opening.

  The printed wiring board includes an insulating substrate having an opening, a plurality of wires, connection terminals connected to the wires, and the wires outside the outer periphery of the opening on one surface of the insulating substrate. It has an insulating layer which covers and is arranged so that the field which has the above-mentioned insulating layer of the above-mentioned printed wired board may turn to the above-mentioned piezoelectric element side. In addition, in FIGS. 1-4, illustration is abbreviate | omitted about members other than the insulated substrate of printed wiring board 2A, 2B.

(A) Insulating Substrate The insulating substrate in the printed wiring board is a member supporting the wiring, the connection terminal, and the insulating layer. The insulating substrate is not particularly limited as long as it has a desired insulating property, and, for example, an insulating substrate used for a conventionally known printed wiring board such as a glass epoxy plate can be applied.

  The insulating substrate has an opening. The opening of the insulating substrate is the opening of the printed wiring board. The plan view shape of the opening (peripheral shape of the opening) is not particularly limited as long as the weight body can be inserted and removed when assembling the vibration power generation device, for example, a quadrilateral, a polygon other than a quadrilateral, It can be of any shape such as circular. The quadrilaterals and polygons include regular squares and regular polygons. The quadrangle or polygon may have a chamfered portion whose corner is chamfered. The corners may be chamfered in a planar manner, or may be chamfered in a curved manner.

  FIG. 8 is a schematic plan view showing an example of the printed wiring board 2, showing an example in which the plan view shape of the opening 21 (the shape of the outer periphery 21a) is a square having chamfers 21b with four corners chamfered. There is. In FIG. 8, the members other than the insulating substrate 31 of the printed wiring board 2 are not shown. In FIG. 8, the square opening is chamfered flatly at the corners of the four corners. The chamfering width is not particularly limited and can be set as appropriate, and can be, for example, equal to or greater than the width of the beam portion. The upper limit of the chamfering width is not particularly limited, but is preferably twice or less the length of the beam portion. In addition, chamfering width means the length in the surface direction of the surface formed by chamfering of a corner, and says the length shown by T in FIG.

  Among them, it is preferable that the plan view shape of the opening portion is a square having a chamfered portion in which four corners are chamfered, and the chamfered portion has a chamfered width larger than the width of the beam portion in the substrate of the piezoelectric element. The four beams of the substrate of the piezoelectric element having cross-shaped beams are disposed orthogonal to the chamfers of the opening, thereby intersecting the direction in which an impact force is applied to the piezoelectric element The structure in which the beam extends in the direction can disperse the stress concentration generated at the end of the beam fixed to the printed wiring board, and can have higher output power and high impact reliability. It is from.

  The size of the opening can be appropriately set so that the weight can be inserted and removed.

  The outer peripheral shape in plan view of the insulating substrate is not particularly limited, and may be an arbitrary shape such as, for example, a square, a polygon other than a square, or a circle. The above-mentioned quadrilateral and polygon include square (square) and regular polygon. The corners of the square or polygon may be chamfered. Above all, the outer peripheral shape in plan view of the insulating substrate is preferably a quadrangle, and can be, for example, a square or a rectangle.

  The thickness of the insulating substrate is not particularly limited as long as the wiring, the connection terminal, the insulating layer, and the partition can be supported.

(B) A plurality of wires and connection terminals A plurality of wires in the printed wiring board includes a plurality of printed wires and a plurality of dummy wires. The wiring is provided outside the outer periphery of the opening of the insulating substrate, and for example, is provided outside the second region (the outer peripheral side of the printed wiring board).

  The printed wiring and the dummy wiring are not particularly limited as long as they have a desired conductivity, and can be formed of a wiring material used for a conventionally known printed wiring board.

  The wiring has an output electrode (output terminal) to the outside at one end, and an input electrode (input terminal) from the piezoelectric element at the other end. These connection terminals are not particularly limited as long as they have desired conductivity, and can be similar to the connection terminals used for the conventionally known printed wiring board. The connection terminal may be provided outside the periphery of the opening of the insulating substrate, and at least one of the connection terminals provided at both ends of the wiring may be located in the second region.

  The printed wiring board can be formed by a conventionally known forming method.

(C) Insulating layer The insulating layer is a member provided on the outer surface of the opening on the surface of the printed wiring board on the piezoelectric element side, which protects the wiring, and between the printed wiring board and the piezoelectric element. Has a function to prevent the occurrence of short circuit.

  As a material of the insulating layer, the same material as the insulating layer in a general wiring substrate can be used, and examples thereof include an ionizing radiation curable resin exhibiting an insulating property. Among them, photosensitive resins used for resists are preferable. As a photosensitive resin which shows insulation, a general thing can be used, It may be positive photosensitive resin and may be negative photosensitive resin. As a positive photosensitive resin, a phenol epoxy resin, an acrylic resin, a polyimide, a cycloolefin etc. can be mentioned, for example. Moreover, as a negative photosensitive resin, photosensitive polyimide resin, acrylic resin, photosensitive phenol resin, photosensitive epoxy resin, novolak resin, melamine resin etc. can be mentioned, for example. Moreover, the said insulating layer may contain arbitrary compositions, such as a crosslinking agent, according to the kind of said resin.

  The thickness of the insulating layer is not particularly limited as long as it can exhibit the function of the insulating layer described above, and can be the same as the standard thickness of the insulating layer in a general printed circuit board. May be, for example, 10 μm or more, and in particular, 20 μm or more is preferable. The thickness of the insulating layer can be, for example, 100 μm or less, and can be 60 μm or less.

  The insulating layer is formed at a position overlapping the wiring in plan view. Specifically, the insulating layer can be formed on the insulating substrate outside the second region, and a part of the insulating layer is formed on the insulating substrate in the second region. May be

  The insulating layer can be formed using a general method of forming an insulating layer on a wiring substrate, such as a photolithography method and a printing method.

(3) Adhesive Layer In the piezoelectric element laminate, an adhesive layer is disposed in a space between the piezoelectric element and the printed wiring board in the second region (hereinafter, may be referred to as a space in the second region). It is also good. This is because the printed wiring board and the piezoelectric element can be firmly joined. The adhesive layer in the vibration power generation device is generally referred to as an "underfill", and the adhesive forming the adhesive layer is generally referred to as an "underfill material".

  The adhesive layer is a cured product obtained by curing a liquid adhesive containing a curable resin. As said curable resin, curable resin contained in the general adhesive used for joining a piezoelectric element and a board | substrate is mentioned, For example, a silicone resin, a modified silicon resin, an epoxy resin, a modified epoxy resin, an acryl A resin, a urea resin, a fluorine resin, etc., or a combination of these resins, or a hybrid resin containing one or more of these resins, etc. may be mentioned. Among them, silicone resin and epoxy resin are preferable.

  The adhesive layer is provided to fill the space in the second region. When the space in the second region has an electric connection member described later, the electric connection member is reinforced by the adhesive layer, and connection reliability can be enhanced.

  The thickness of the adhesive layer may be a size that can fill the space in the second region and can firmly bond the printed wiring board and the piezoelectric element, and usually, the insulation of the printed wiring board And the spacing between the piezoelectric substrate and the substrate of the piezoelectric element.

  The method of forming the adhesive layer can be similar to, for example, the method of providing an adhesive layer (underfill) between the component and the substrate in the component mounting board. Specifically, the piezoelectric element is disposed at a desired position on the printed wiring board, and a liquid adhesive (underfill material) is injected into the space in the second region using a needle or the like and filled, and then cured. It can be formed.

(4) Electrical Connection Member The piezoelectric element laminate can have an electrical connection member for electrically connecting the printed wiring board and the piezoelectric element.

  In the piezoelectric element laminate, the input electrodes of the pair of electrodes on the printed wiring board are connected to the both ends of the piezoelectric members of the piezoelectric element where the potential difference occurs, through the above-mentioned electrical connection members. Thus, the potential difference generated by the piezoelectric body can be collected as electric energy at each output electrode in the printed wiring board.

  A method of connecting the printed wiring board and the piezoelectric element may be any method as long as conduction between the printed wiring board and the piezoelectric element can be taken, and either a wire bonding method or a flip chip method can be adopted.

  The electrical connection member can be appropriately selected depending on the connection method, and in the case of the flip chip method, for example, a bump can be used, and in the case of the wire bonding method, for example, a conductive wire can be used. When the adhesive layer is provided between the printed wiring board and the piezoelectric element, the printed wiring board and the piezoelectric element can be formed by connecting the printed wiring board and the piezoelectric element by a flip chip method. Connection reliability between elements can be improved. Since the space in the second region is filled with the adhesive layer, concentration of stress on the bump during vibration is suppressed by the surrounding adhesive layer.

  The material of the bumps is not particularly limited as long as the material exhibits conductivity, and, for example, general bump materials such as solder and metal paste can be used. The composition of the solder and the composition of the metal paste are not particularly limited, and may be the same as the composition of the solder and the composition with the metal paste which are generally used for mounting components on a printed wiring board.

  The method for forming the electrical connection member is not particularly limited, and can be formed using a method used for manufacturing a general component mounting wiring board. For example, a mounting method using an anisotropic conductive film (ACF) can be used.

(5) Others Each piezoelectric element laminate is fixed to the weight body in the first region of the substrate of the piezoelectric element. The fixing position can be appropriately set according to the shape of the first region of the substrate.

  Further, each of the piezoelectric element stacks is fixed by the fixing member. The piezoelectric element laminate is preferably fixed by the fixing member at a position that does not inhibit the vibration of the piezoelectric element, and may be fixed by the fixing member in the second region, and is outside the second region The region may be fixed by the fixing member.

  In addition to the above members, the piezoelectric element laminate may be a rectifier circuit, a voltage regulator circuit, an energy management circuit element such as a battery and the circuit itself, a passive element such as a capacitor, a physical quantity sensor such as an acceleration sensor or an ultrasonic transducer It may have a chemical quantity sensor such as an odor sensor, a signal processing circuit, and a communication circuit.

2. Weight body The weight body in the vibration power generation device of this aspect is a member disposed between the pair of piezoelectric element stacks. The weight connects the piezoelectric elements of the pair of piezoelectric element stacks in the first region of the substrate of the piezoelectric element stack, and the mass converts the external force into a force transmitted to the plurality of piezoelectric elements. Have a function to

  The material of the weight is not particularly limited, and, for example, stainless steel (for example, SUS303, SUS304), free-cutting brass (C3604), copper, tungsten, tantalum or the like can be used.

  Moreover, the material of the weight may be the same as or different from the material of the substrate of the piezoelectric element, but among them, the weight and the substrate of the piezoelectric element are formed of the same metal. Is preferred. This is because distortion due to temperature is less likely to occur since the weight body and the piezoelectric element laminate are easily joined and there is almost no difference in thermal expansion coefficient. At this time, the metal is preferably stainless steel, and more preferably SUS304. SUS304 has high strength, and it is possible to firmly bond the weight body and the piezoelectric element laminate. Moreover, when joining a weight body and a piezoelectric element laminated body by spot welding, for example, SUS304 has a high absorptivity of a laser, and welding with a small diameter becomes possible by a laser spot.

  The weight body may have any shape as long as the piezoelectric elements of the pair of piezoelectric element stacks can be connected, and can be, for example, a cylindrical shape, a prismatic shape, or the like. The weight body may have a multistage shape including a body portion and a pair of fixing portions disposed above and below the body portion in the axial direction. The weight body shown in FIG. 9 (a) is a multistage circular casting shape having a cylindrical body portion 51a and a pair of cylindrical fixing portions 51b, and the weight body shown in FIG. 9 (b) is a prismatic body portion It is a multistage prism shape which has 51a and a pair of prismatic fixing | fixed part 51b. 9A and 9B indicate the axis of the body portion, and the axial direction of the body portion is a direction in which an external force is applied to the piezoelectric element, and the piezoelectric of the pair of piezoelectric element laminates is used. It is a direction which connects between elements.

  The shape and size of the weight body are not particularly limited as long as the shape and size can stably convert the external force to the piezoelectric element. When the weight body has a structure having a body portion and a fixing portion, the position of the weight body and the position of the fixing portion are on the axis extension line of the weight body, and stably transmit the external force to the piezoelectric element It can be designed at a position that can be converted into force, and the position is not particularly limited.

  The bonding method of the weight body and the piezoelectric element laminate is not particularly limited, and for example, it can be bonded by welding. Above all, it is preferable that the substrate of the piezoelectric element laminate and the weight body be joined by spot welding. This is because inexpensive and high-strength bonding is possible.

3. Fixing Member The fixing member in the vibration power generation device of this aspect is a member disposed between the pair of piezoelectric element laminates.

  The material of the fixing member is not particularly limited as long as dimensional tolerance is small and durability can be provided. Examples of such materials include metals and resins. As a metal, aluminum (A5052), stainless steel (SUS) etc. are mentioned, for example. Examples of the resin include polycarbonate (PC), polyphenylene ether (PPE), nylon (Ny), one another, or an alloy with polypropylene (PP) or an elastomer, or an aramid fiber composite resin.

  The shape, size, and the like of the fixing member can be appropriately set according to the shape, size, and the like of the vibration power generation device of one embodiment of the present disclosure. The shape of the fixing member is preferably a shape that can be fixed so that initial deflection does not easily occur in the piezoelectric element, and examples thereof include a columnar shape and a plate shape.

  The fixing member is disposed between the pair of piezoelectric element laminates and at a position that does not inhibit the vibration of the piezoelectric element. The fixing member may be fixed, for example, in contact with the surface of the printed wiring board 2 on the piezoelectric element 1 side outside the second region B as shown in FIGS. 1 to 3, as shown in FIG. It may be fixed in contact with the substrate 11 of the piezoelectric element 1 in the second region B, but the former is preferable. Further, the fixing member may be arranged in a columnar shape with an interval along the outer periphery of the printed wiring board, or may be arranged in a plate shape (wall shape) without an interval. Are preferably arranged in the form of This is because the contact area between the printed wiring board and the fixing member can be secured, and unnecessary vibration of the piezoelectric element can be controlled by sufficiently fixing the two piezoelectric element laminates.

  The fixing member is disposed along the axial direction of the weight body between the pair of piezoelectric element laminates, that is, along the action direction of the external force, and hence the fixing member is a side fixing member (member indicated by reference numeral 52A in FIG. 11). Can. Further, in the vibration power generation device according to one embodiment of the present disclosure, an upper surface fixing member and a lower surface fixing member sandwiching the pair of piezoelectric element laminates from above and below in the axial direction of the weight body in addition to the side surface fixing member And the members indicated by reference numeral 52C. The upper surface fixing member and the lower surface fixing member should strike the weight (or the piezoelectric element) with the upper surface fixing member or the lower surface fixing member in order to prevent breakage of the beam portion of the substrate of the piezoelectric element when a large impact is applied from the outside. Can function as a stopper for suppressing the displacement of the beam portion. Further, the upper surface fixing member and the lower surface fixing member can function as a seal (packaging) that prevents adhesion of dust to the piezoelectric element.

  When the vibration power generation device of this aspect has the upper surface fixing member and the lower surface fixing member, the stopper 53 is further provided on the weight side surface of at least one of the upper surface fixing member and the lower surface fixing member as shown in FIG. You may have. This is because even in the vibration direction that contributes to power generation, it is possible to prevent displacement exceeding the elastic limit of the material.

  The fixing method of the fixing member and the piezoelectric element laminate, and the fixing method of the side fixing member, the upper surface fixing member and the lower surface fixing member are not particularly limited. For example, a fixing method using a fastening means such as screwing And a fixing method using a bonding means such as an adhesive or a pressure-sensitive adhesive.

5. Other members In the vibration power generation device of the present embodiment, a fixed lubricating layer (a member indicated by reference numeral 54 in FIG. 11) is provided on the surface on the weight body side of the fixing member (side fixing member) disposed between the pair of piezoelectric element laminates. ) May be arranged. This is because the vibration direction of the piezoelectric element can be limited to the axial direction of the weight body. The fixed lubricating layer preferably has friction resistance and wear resistance. Examples of the material of the fixed lubricating layer include fluorine resin typified by Teflon (registered trademark), and Teflon-containing nickel plating (Ni-PTFE).

6. The vibration power generation device of this aspect has the above-mentioned structure, thereby suppressing variation in initial deflection of the piezoelectric element and suppressing a decrease in power generation capacity of individual devices. As electrical energy. Such a vibration power generation device can be used, for example, as a power supply source to a sensor network module for IoT (Internet of Things) such as an in-vehicle application system in which wiring power feeding or battery driving is difficult or an infrastructure soundness diagnosis system.

B. Second Aspect A second aspect of the vibration power generation device of the present disclosure (hereinafter, may be referred to as a vibration power generation device of this aspect in this section) includes a pair of piezoelectric element laminates and the pair of piezoelectric element laminates A vibration generating device having a weight body disposed on the upper surface and a fixing member disposed between the pair of piezoelectric element stacks, wherein the piezoelectric element stack is disposed on a substrate and the substrate A piezoelectric element having a plurality of piezoelectric bodies and a printed wiring board having an opening are provided, and the substrate of the piezoelectric element and the weight body are joined by welding.

  The vibration power generation device is required to have high power generation capacity. In order to satisfy such requirements, it is necessary to increase the amount of vibration energy generated by the vibration of the piezoelectric element and to improve the conversion efficiency to electrical energy. For this reason, the joint portion between the piezoelectric element and the weight body needs to be durable to withstand vibration.

  To solve such problems, according to the vibration power generation device of this aspect, the substrate of the piezoelectric element and the weight body are joined by welding, and thus inexpensive and high-strength joining is possible. It is because

  Hereinafter, each structure of the vibration power generation device of this aspect is demonstrated.

1. Piezoelectric Element Laminate The piezoelectric element laminate in the vibration power generation device of this aspect is a piezoelectric element laminate having a substrate and a piezoelectric element having a plurality of piezoelectric bodies disposed on the substrate, and a printed wiring board having an opening. And.

(1) Piezoelectric Element The piezoelectric element includes a substrate and a plurality of piezoelectric bodies disposed on the substrate. The piezoelectric element can include the piezoelectric body in a first area which is an area where the substrate and the opening overlap in plan view.

  The piezoelectric element of the piezoelectric element laminate in this aspect can be the same as the piezoelectric element of the piezoelectric element laminate in the first aspect of the vibration power generation device described above, and thus the description thereof is omitted here. Among them, the base of the piezoelectric element is preferably formed of the same metal as the weight body, more preferably the metal is stainless steel, and particularly preferably the metal is SUS304. The reason for this has been described in the first aspect of the vibration power generation device described above, so the description here is omitted.

(2) Printed wiring board The printed wiring board has an opening. About the said printed wiring board, since it can be made to be the same as that of the printed wiring board of the piezoelectric element laminated body in the 1st aspect of the vibration electric power generation device mentioned above, description here is abbreviate | omitted.

  The printed wiring board may be disposed on the surface of the piezoelectric element on the weight body side, or may be disposed on the surface of the piezoelectric element opposite to the weight body.

2. Weight body The weight body in the vibration power generation device of this aspect is disposed between the pair of piezoelectric element stacks.

  The weight body can be the same as the weight body in the first aspect of the vibration power generation device described above, and thus the description thereof is omitted here. Among them, the weight body is preferably formed of the same metal as the base material of the piezoelectric element, more preferably the metal is stainless steel, and particularly preferably the metal is SUS304. The reason for this has been described in the first aspect of the vibration power generation device described above, so the description here is omitted.

3. Fixing Member The fixing member in the vibration power generation device of this aspect is disposed between the pair of piezoelectric element laminates.

  The fixing member and the arrangement position thereof can be the same as the fixing member and the arrangement position thereof in the first aspect of the vibration power generation device described above, and thus the description thereof is omitted here.

4. Others In the vibration power generation device of this aspect, each of the piezoelectric element stacks is fixed to the weight body in the first region of the substrate. Further, the substrate of the piezoelectric element and the weight body are joined by welding.

  The weight body and the substrate of the piezoelectric element are preferably formed of the same metal, more preferably the metal is stainless steel, and particularly preferably the metal is SUS304. By using the same SUS304, welding with a small diameter can be performed by the laser spot by using the high laser absorptivity of SUS304.

  That the substrate of the piezoelectric element and the weight body are joined by welding means that, for example, a rough surface portion is provided around the bonding portion of the substrate to the weight body, the substrate of the piezoelectric element It can be confirmed from the fact that the weight body and the bonding interface do not contain any metal other than the above-mentioned substrate and the metal forming the weight body. The rough surface portion of the substrate refers to a portion formed around the bonding portion between the substrate and the weight body and having a surface roughness greater than that of the other surface of the substrate, specifically, the surface roughness Ra Means a portion showing Ra> 0.1 μm. The surface roughness Ra is a value measured in accordance with JIS B0601.

5. Application The vibration power generation device of this aspect can be used as a power supply source to, for example, a sensor network module for IoT (Internet of Things) such as an in-vehicle application system in which wiring feeding or battery driving is difficult or an infrastructure soundness diagnosis system.

II. Method of Manufacturing Vibration Power Generation Device The method of manufacturing a vibration power generation device according to the present disclosure is a method of manufacturing a vibration power generation device described in the section “I. Vibration power generation device”, and the piezoelectric element included in the piezoelectric element laminate. It is a manufacturing method which has a joining process which joins the above-mentioned substrate of the above, and the above-mentioned weight body by welding.

  According to the method of manufacturing a vibration power generation device of the present disclosure, the pair of piezoelectric element laminates and the weight body can be joined at low cost and with high strength.

A. Bonding Step The bonding step in the method of manufacturing a vibration power generation device of the present disclosure is a bonding step of welding the substrate of the piezoelectric element of the piezoelectric element laminate and the weight body by welding.

  According to this process, the pair of piezoelectric element laminates can be fixed to the weight body in the first region of the substrate of the piezoelectric element.

  The welding method is not particularly limited as long as the substrate of the piezoelectric element and the weight body can be firmly joined, but a method using laser light is preferable among them. Further, at the joint portion between the substrate of the piezoelectric element and the weight body, the welded portion formed by welding may be at one or more points, and usually in a plurality of point or line or plane It is formed. The distance between the welds can be set as appropriate.

  In this process, the piezoelectric element laminate may be disposed so that the printed wiring board is closer to the weight body than the piezoelectric element, and the piezoelectric element is closer to the weight body than the printed wiring board. You may arrange and carry out. The said piezoelectric element laminated body arrange | positions and performs it so that a piezoelectric element may become a weight body side rather than a printed wiring board, The 1st aspect of the vibration electric power generation device demonstrated by the term of said "I. vibration electric power generation device" Can be manufactured.

B. Other Steps The method of manufacturing a vibration power generation device of the present disclosure can have other steps such as a piezoelectric element laminate formation step, a fixing member arrangement step, and the like in addition to the above-described bonding step. About these other processes, since it can be made to be the same as that of the manufacturing method of a publicly known oscillating power generation device, explanation here is omitted.

[Reference Example and Reference Comparative Example]
The effects of the vibration power generation device of the present disclosure were evaluated by finite element analysis. As finite element analysis software, ANSYS 16.0 (ANSYS) was used. The physical property database used the one that comes standard with the software, but the science chronology (Maruzen, 2015) and Z. Cao, J. Zhang and H. Kuwano, Sens. Actuators A 179 (2012), pp. See 178-184.

The simulation model of the vibration power generation device of the structure illustrated to FIG. 12 (a), (b) was created. The vibration power generation device of the structure illustrated in FIG. 12A is a reference example, and the vibration power generation device of the structure illustrated in FIG. 12B is a reference comparative example. 13 (a) is a schematic plan view of the piezoelectric element laminate in the simulation model, FIG. 13 (b) is a schematic cross section of the piezoelectric element and the weight body in the simulation model, and FIG. 13 (c) is a simulation model The schematic plan view of a weight body is shown, respectively. Moreover, FIG. 14 is a graph which shows the simulation result of _Tad dependence of the output electric power of a vibration electric power generation element. In addition, about the code | symbol in FIGS. 12-14, it is the same as having already demonstrated. Further, in FIGS. 12A, 12B, and 13B, the illustration of the specific configuration of the piezoelectric element is omitted.

As illustrated in FIG. 13A, in the simulation model, the piezoelectric element 1 of the piezoelectric element laminate 10 has four beams and is formed on both sides of a stainless steel substrate 11 having a cross shape in plan view. A single aluminum nitride thin film covering the entire surface of the substrate 11 is formed as the piezoelectric layer 22. The thickness T _beam of the beam portion 11a and 0.05 mm, the thickness of the piezoelectric layer T _piezo. Was 0.004 mm.

As illustrated in FIGS. 13A and 13B, the beam portion 11a is a fixed end in which one end is ideally joined to the outer periphery 21a of the opening 21 of the insulating substrate of the printed wiring board 2 The other end portion is a fixed end similarly joined to the beam intersection portion 11 c which is a connection portion with the weight body 51. Further, the length L _beam between the two fixed ends of the beam portion 11a (effective length of the beam portion 11a) was set to 4 mm.

A current collecting layer (hereinafter, referred to as an electrode layer) is formed on the piezoelectric layer 22 to form the piezoelectric body 12, and the dimension of the electrode layer in the beam length direction is the piezoelectric body length ( _Lpiezo. ) _. It was set to 1.8 mm. In addition, the width of the beam portion 11a is the substrate beam width (W _beam ), and the width of the electrode layer in the piezoelectric body 12 is the piezoelectric body width (W _piezo. ), W _beam = W _piezo = 7 mm, and W _beam and W _piezo is FIG. 13 (b), the was equal to the width (diameter) D ₁ of the fixed portion 51b of the weight body 51 shown in (c).

As shown in FIG. 13 (b), the weight body 51, the length d ₁ and 2mm of the fixed portion 51b, and the body portion 51a the length d ₂ and 7 mm. The target length d between the piezoelectric elements 1A and 1B defined from these values is equal to the sum of d ₁ and d ₂ and is 9 mm. Further, as shown in FIG. 13 (c), the dimensions of the planar direction, the width D ₁ of the fixing portion 51b of the weight body 51 and 7 mm, and the outer peripheral diameter D ₂ of the body portion 51a and 13.3 mm. The material of the weight body 51 was tungsten, and the weight was 22.5 g.

  Each dimension is shown in Table 1 and Table 2.

In this model, the difference between the target length d between the piezoelectric elements and the realized length d ^* between the piezoelectric elements caused by the dimensional error of the parts such as the fixing member and the insulating substrate disposed between the pair of piezoelectric elements is T _ad The _Tad dependency of the output power of the vibration power generation element is calculated as shown in FIG. At this time, a parabolic element is used for the mesh, and the mesh size is X ₁ direction = 0.01 mm, X _{2 based on the} coordinate display shown in FIG. 1 and FIGS. 12 (a) and 12 (b) and 13 (a). direction = 0.01mm, was the _{X 3} direction = 0.002mm. The solver used an electromechanical coupled analysis solver capable of calculating piezoelectric elements. For the reference frequency, the output power P normalized by the value when there is no error is P = 1.00, 0.79, 0.29 when T _ad is 0 mm, 0.05 mm, 0.10 mm, respectively. It has been shown that the output power decreases as the dimensional deviation increases.

  In the structure of the reference example, the dimensional tolerance was ± 0.1 mm, and in the structure of the reference comparative example, the dimensional tolerance was ± 0.3 mm. From the results shown in FIG. 14, assuming that the dimensional tolerance allowed when making a vibration power generation device capable of generating about 80% of the design value as a good product is 0.05 mm, and the dimensional tolerance follows a normal distribution. The yield rate of the vibration power generation device having the structure of the reference example is 38%, and the yield rate of the vibration power generation device having the structure of the reference comparative example is 13%. From the above results, in the structure of the vibration power generation device of the reference example, the non-defective rate is improved by nearly three times that of the structure of the vibration power generation device of the reference comparative example. It was suggested that it was big.

DESCRIPTION OF SYMBOLS 1, 1A, 1B ... Piezoelectric element 2, 2A, 2B ... Printed wiring board 10, 10A, 10B ... Piezoelectric element laminated body 11 ... Substrate 12 ... Piezoelectric body 21 ... Opening 21a ... Outer periphery 50 ... Vibration power generation device 51 ... Weight weight Body 52, 52A ... Fixing member (side fixing member)
A ... first area B ... second area

Claims (5)

A vibration power generation device comprising: a pair of piezoelectric element stacks; a weight body disposed between the pair of piezoelectric element stacks; and a fixing member disposed between the pair of piezoelectric element stacks,
The piezoelectric element laminate includes a substrate and a piezoelectric element having a plurality of piezoelectric members disposed on the substrate, and a print having an opening disposed on the surface of the piezoelectric element opposite to the weight body side. A wiring board, and the piezoelectric element includes the piezoelectric body in a first area, which is an area where the substrate and the opening overlap in plan view,
Each said piezoelectric element laminated body is a vibration electric power generation device currently fixed to the said weight body in the said 1st area | region of the said board | substrate. A vibration power generation device comprising: a pair of piezoelectric element stacks; a weight body disposed between the pair of piezoelectric element stacks; and a fixing member disposed between the pair of piezoelectric element stacks,
The piezoelectric element laminate includes a piezoelectric element having a substrate and a plurality of piezoelectric bodies disposed on the substrate, and a printed wiring board having an opening.
A vibration power generation device, wherein the substrate of the piezoelectric element and the weight body are joined by welding.   The vibration power generation device according to claim 1, wherein the weight body and the substrate of the piezoelectric element are formed of the same metal.   The vibration power generation device according to claim 3, wherein the metal is SUS304. A method of manufacturing a vibration power generation device according to any one of claims 1 to 4, wherein
The manufacturing method of the vibration electric power generation device which has a joining process which joins the said board | substrate of the said piezoelectric element which the said piezoelectric element laminated body has, and the said weight body by welding.