Microelectromechanical generator

Abstract

A microelectromechanical generator that can improve power generation efficiency is provided. [Solution] The movable electrode section 20 has an electret electrode 23 arranged opposite to periodically arranged fixed electrodes 13. The elastic support section 50 is configured to support the movable electrode section 20 with a flexible section 51, and the facing area between the electret electrode 23 and the fixed electrode 13 is increased or decreased by deforming the flexible section 51 in the X direction. The electret electrode 23 is arranged so as to overlap with the elastic support section 50 in the Z direction intersecting the X direction, and generates electricity by vibrating.

Description

[Technical Field]

[0001] The present invention relates to microelectromechanical generators. [Background technology]

[0002] Micro-electromechanical generators, also known as MEMS, are used in various industrial fields. MEMS is an abbreviation for Micro Electro Mechanical Systems. Generally, a micro-electromechanical system consists of an electret electrode and a counter electrode, configured to generate an electric field on the surface of the electret electrode to attract electric charge to the surface of the counter electrode. As the movable electrode vibrates mechanically, the contact area with the counter electrode changes, and this change generates an electric current, thereby producing electricity (see, for example, Patent Document 1).

[0003] In the configuration described in Patent Document 1, a beam is used to support a counter electrode, which acts as a movable electrode, so that it can vibrate in a predetermined direction, and the counter electrode is positioned opposite the electret electrode so that it can move relative to it. According to the technology described in Patent Document 1, the damping effect of air on the movable electrode can be reduced, and the power generation efficiency can be improved. Furthermore, by constructing the electret electrode from alkali glass, an electret electrode with a high charge density can be formed, thereby increasing the power generation efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-068643 A (Patent No. 05305797 A) [Overview of the Initiative] [Problem to be solved by the invention]

[0005] In the configuration described in Patent Document 1, electrodes cannot be arranged in the areas where the beams are arranged, and therefore the opposing area cannot be made large, resulting in a structure with poor power generation efficiency. An object of the present disclosure is to provide a microelectromechanical generator that can improve power generation efficiency. [Means for solving the problem]

[0006] The invention comprises a movable electrode section in which an electret electrode is positioned opposite periodically arranged electrodes, and an elastic support section configured to support the movable electrode section by a flexible section, and which increases or decreases the opposing area between the electret electrode and the electrode by deforming the flexible section in the direction of the first axis. In the invention described in claim 1, the electret electrode is positioned so as to overlap with the elastic support section in a direction intersecting the direction of the first axis, and generates electricity by vibrating.

[0007] According to the invention described in claim 1, the electret electrode can be positioned so as to overlap with the elastic support portion in an intersecting direction that intersects the direction of the first axis, thereby enabling effective utilization of the region. As a result, the area in which the electret electrode can be positioned can be increased, thereby improving power generation efficiency. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a longitudinal cross-sectional view schematically illustrating a microelectromechanical generator according to a first embodiment. [Figure 2] 1 is a top view schematically showing the structures of a fixed electrode, a spacer, a movable electrode, and an elastic support portion in the first embodiment; [Figure 3] 1 is an explanatory diagram of the manufacturing method of the microelectromechanical generator in the first embodiment. [Figure 4] 2 is an explanatory diagram of the manufacturing method of the microelectromechanical generator in the first embodiment. [Figure 5] 3 is an explanatory diagram of the manufacturing method of the microelectromechanical generator in the first embodiment. [Figure 6] FIG. 10 is a longitudinal cross-sectional view schematically showing a microelectromechanical generator according to a second embodiment. [Figure 7] 1 is an explanatory diagram of a method for manufacturing a microelectromechanical generator according to the second embodiment; [Figure 8] 2 is an explanatory diagram of the manufacturing method of the microelectromechanical generator in the second embodiment. [Figure 9] 10A and 10B are top views each showing a schematic structure of a fixed electrode, a spacer, a movable electrode, and an elastic support member in the third embodiment; [Figure 10] An explanatory diagram of a current path of a microelectromechanical generator in a third embodiment. [Figure 11] Operational diagram of the movable electrode in the third embodiment, part 1 [Figure 12] Operational diagram of the movable electrode in the third embodiment, part 2 [Figure 13] FIG. 10 is a longitudinal cross-sectional view schematically showing a microelectromechanical generator according to a fourth embodiment. [Figure 14] FIG. 10 is a diagram schematically illustrating an arrangement of a microelectromechanical generator according to a fourth embodiment. [Figure 15] FIG. 10 is a longitudinal cross-sectional view schematically illustrating a vertical vibration state of the microelectromechanical generator according to the fourth embodiment. [Figure 16] FIG. 10 is a longitudinal cross-sectional view schematically showing a microelectromechanical generator according to a fifth embodiment. [Figure 17] 13A and 13B are longitudinal cross-sectional views of a first layer and a second layer, and a top view of the first layer, which schematically illustrate a microelectromechanical generator according to a sixth embodiment; [Figure 18] 13A and 13B are a top view of the second layer and a longitudinal cross-sectional view of the first and second layers, each showing a microelectromechanical generator according to a sixth embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0009] Below, several embodiments of the microelectromechanical generator will be described. Parts that perform the same function in each embodiment will be assigned the same reference numerals, and their description may be omitted. In the drawings, the X, Y, and Z directions will be shown as directions that intersect with each other. The X direction corresponds to the first axis direction, the Y direction corresponds to the second axis direction, and the Z direction corresponds to the third axis direction. From a structural standpoint, it is desirable for the X, Y, and Z directions to intersect at right angles, but this is not a limitation.

[0010] (First embodiment) The first embodiment will be described with reference to Figures 1 to 5. The microelectromechanical generator 1 constitutes a MEMS mounted on a vehicle, and as shown in Figure 1, mainly comprises portions that function as a fixed electrode portion 10, a movable electrode portion 20, and an elastic support portion 50.

[0011] As shown in Figure 1, the fixed electrode section 10 comprises a fixed electrode 13 on a substrate 11 via an insulating film 12. The substrate 11 is made of, for example, silicon. The insulating film 12 is made of, for example, silicon oxide. The fixed electrode 13 is made of a conductive material 101 such as gold or aluminum (see S13 and S14 in Figure 3). The fixed electrode 13 is configured by being periodically arranged in the X direction on the surface of the insulating film 12 on the substrate 11.

[0012] The fixed electrode portion 10 is formed in the first layer L1. As shown in the upper figure in Figure 2, the fixed electrode 13 comprises a first comb-tooth structure 13a in which one end of each striped linear portion 13aa formed along the Y direction is joined together, and a second comb-tooth structure 13b in which the other end of each linear portion 13bb that does not constitute the linear portion 13aa of the first comb-tooth structure 13a is joined together. The linear portions 13aa and 13bb of the fixed electrode 13 are configured to be elongated in the Y direction, which intersects with the X direction in which the movable electrode portion 20 can vibrate.

[0013] The linear portion 13bb of the second comb tooth structure 13b is arranged opposite the linear portion 13aa of the first comb tooth structure 13a, and the first comb tooth structure 13a and the second comb tooth structure 13b are configured separately on the substrate 11 with an insulating film 12 interposed between them.

[0014] In other words, the fixed electrode 13 is configured such that the electrodes of adjacent first comb structures 13a and second comb structures 13b are connected by different wiring. These first comb structures 13a and second comb structures 13b are electrically connected to the outside using at least two sets of wiring, and are connected to both ends of an external load, although not shown in the diagram. The external load, although not shown here, consists of a rectifier circuit such as a diode bridge, a capacitor, and the load to which power is supplied in the subsequent stage.

[0015] As shown in the upper part of Figure 2, the spacers 30 are positioned at the four corners of the rectangular base material 11 in the XY plane. As shown in Figure 1, the spacers 30 are interposed between the outer peripheral support portion 40 and the fixed electrode portion 10, and as a result, the outer peripheral support portion 40 is supported from below in the Z direction.

[0016] The movable electrode portion 20 is formed in the second layer L2. The second layer L2 is located above the first layer L1 (see Figure 1). As shown in the middle diagram of Figure 2, the electret electrodes 23 are spaced apart from each other in the X direction and arranged in a stripe pattern along the Y direction. As shown in Figure 1, the movable electrode portion 20 is supported by a movable electrode support portion 52 located directly below the inner end portion 51a of the flexible portion 51. As a result, the movable electrode portion 20 is integrally coupled with the outer peripheral support portion 40. The electret electrodes 23 are configured to be elongated in the Y direction, which is intersecting with the X direction in which the movable electrode portion 20 can vibrate.

[0017] The outer peripheral support portion 40 and the elastic support portion 50 are formed in the third layer L3. The third layer L3 is located on top of the second layer L2 (see Figure 1). As shown in the lower part of Figure 2, the outer peripheral support portion 40 is formed in the shape of a rectangular frame and is configured to support a pair of elastic support portions 50 at the center in the Y direction inside the rectangular frame.

[0018] The pair of elastic support parts 50 are arranged symmetrically in the X direction with respect to the X-direction center of the outer peripheral support part 40. The base ends 50a of the pair of elastic support parts 50 are connected to the outer peripheral support part 40 at their respective Y-direction centers. The elastic support parts 50 are not connected to the outer peripheral support part 40 at any positions other than the base ends 50a.

[0019] Each pair of elastic support parts 50 comprises a flexible part 51 and a movable electrode support part 52. As shown in the lower diagram of Figure 2, each flexible part 51 has linear sections that are arranged parallel to the Y direction, connected at both ends in the Y direction via short connecting parts, and a space with a long axis in the Y direction is provided inside the connecting linear sections.

[0020] The movable electrode support part 52 is connected to the inner end part 51a of the flexible part 51, and supports the movable electrode part 20 from above in the Z direction, as shown in Fig. 1. By employing such a structure, the flexible part 51 is flexible in the X direction, and the elastic support part 50 can deform the flexible part 51 in the X direction while supporting the movable electrode part 20. As described above, since the movable electrode support part 52 of the elastic support part 50 supports the movable electrode part 20, when an external force is applied, the flexible part 51 deforms and bends in the X direction, causing the movable electrode part 20 to vibrate in the X direction.

[0021] As will be explained in the embodiment below, when it is expected that the magnitude of vibration in the X direction is greater than that in the Z direction, it is desirable that the Z direction thickness of flexible portion 51 constituting elastic support member 50 is greater than or equal to the X direction width, as shown in Fig. 1. In this case, the linear portion of flexible portion 51 can easily deform when it flexes and vibrates in the X direction. In the XZ cross section shown in Fig. 1, flexible portion 51 is shown as having a structure in which one linear portion and inner end portion 51a are connected, but a thin line is drawn between these portions in the cross section to make it easier to understand.

[0022] It is desirable that the XZ cross-sectional dimensions of the flexible portion 51 be such that the width dimension in the X direction is less than or equal to the thickness dimension in the Z direction. However, this can be considered as the X direction dimension less than or equal to the thickness dimension in the Z direction including one linear portion of the flexible portion 51 and the inner end portion 51a, or as the X direction dimension less than or equal to the thickness dimension in the Z direction of the one linear portion of the flexible portion 51.

[0023] Referring to the longitudinal cross-sectional view shown in Figure 1, the structure and operation will be explained from a different perspective. As shown in Figure 1, the fixed electrode section 10 has fixed electrodes 13 arranged periodically, and the movable electrode section 20 has electret electrodes 23 arranged periodically in the X direction on the surface opposite to the surface where the fixed electrodes 13 are arranged.

[0024] The number of electret electrodes 23 arranged is approximately half the number of the line portions 13aa, 13bb of the fixed electrode 13. In the default structure shown in Fig. 1, the electret electrodes 23 are arranged so as to be located at the middle position in the X direction between the line portions 13aa, 13bb of the fixed electrode 13. The outer peripheral support portion 40 and the fixed electrode portion 10 are fixed via spacers 30, and the distance between the electret electrodes 23 and the fixed electrode 13 is adjusted depending on the height of the spacers 30.

[0025] The electret electrodes 23 are periodically arranged along the X direction on the surface of the movable electrode section 20. The electret electrodes 23 are arranged so as to overlap the elastic support sections 50 in an intersecting direction (Z direction in this embodiment) that intersects with the deformation direction (X direction in this embodiment) of the flexible sections 51 of the elastic support sections 50. In other words, the electret electrodes 23 are arranged so as to overlap the flexible sections 51 of the elastic support sections 50 in the Z direction. This allows the electret electrodes 23 to be arranged while effectively utilizing the arrangement area of ​​the elastic support sections 50, as shown in the configuration area X0 in FIG. 1 .

[0026] The elastic support member 50 supports the movable electrode member 20 while deforming in the X direction, thereby supporting the movable electrode member 20 so that it can move in the X direction. The microelectromechanical generator 1 is intended to be mounted on a vehicle, and if an external force such as vehicle vibration is applied in the X direction, the spatial distance between the linear portions of one flexible member 51 of the elastic support member 50 will shorten / extend, and in response to this, the spatial distance between the linear portions of the other flexible member 51 will shorten / extend. The flexible member 51 repeats elastic deformation, causing the movable electrode member 20 to vibrate in the X direction relative to the fixed electrode member 10.

[0027] As the movable electrode unit 20 vibrates in the X direction, the electret electrode 23 vibrates / reciprocates in the X direction above the first comb-tooth structure 13a and the second comb-tooth structure 13b of the fixed electrode 13. As a result, the overlapping area of ​​the electret electrode 23 and the fixed electrode 13 in the X direction increases or decreases, and the overlapping area between the electret electrode 23 and the fixed electrode 13 increases or decreases. This changes the amount of charge induced in the fixed electrode 13.

[0028] For example, if the electret electrode 23 is negatively charged and the fixed electrode 13 is positively charged, when the opposing area between the electret electrode 23 and the fixed electrode 13 increases or decreases, the positive charges on the linear portions 13aa and 13bb of the fixed electrode 13 move.

[0029] For example, when the opposing area between the electret electrode 23 and the line portion 13aa increases, the opposing area between the electret electrode 23 and the line portion 13bb decreases. In this case, the positive charge on the fixed electrode 13 is attracted to the negative charge on the electret electrode 23 and moves to the line portion 13aa.

[0030] Conversely, when the opposing area between the electret electrode 23 and the line portion 13bb increases, the opposing area between the electret electrode 23 and the line portion 13aa decreases, but in this case, the positive charge on the fixed electrode 13 is attracted to the negative charge on the electret electrode 23 and moves to the line portion 13bb. This causes a generated current to flow through the fixed electrode 13, and the generated current can be supplied to an external load (not shown).

[0031] <Example of manufacturing method> An example of a method for manufacturing the micro-electro-mechanical generator 1 will now be described. When forming the fixed electrode portion 10 of the first layer L1, silicon 100 is prepared in S11 of Fig. 3, and an insulating film 12 made of, for example, silicon oxide is formed on the silicon 100 in S12. The insulating film 12 may be formed on the entire surface of the silicon 100 as shown in Fig. 3, or may be formed only on the upper surface of the silicon 100. In this way, the insulating film 12 can be formed on the substrate 11.

[0032] Next, in S13, a conductive material 101 such as gold or aluminum is formed on the upper surface of the insulating film 12, and in S14, the conductive material 101 is processed into a comb-like shape (see the upper diagram of Figure 2) using a semiconductor manufacturing process to form a fixed electrode 13.

[0033] Furthermore, the spacers 30 may be formed by applying a resin adhesive or by applying and exposing a photosensitive resin. The spacers 30 may be formed from silicon oxide. In this case, the spacers 30 may be fixed onto the fixed electrode unit 10 by bonding the silicon that forms the substrate 11 to the silicon oxide that forms the spacers 30. As a result, as shown in the upper diagram of Figure 2, the spacers 30 can be formed at multiple locations on the upper surface of the substrate 11 of the fixed electrode unit 10, and a support material for supporting the peripheral support unit 40 from below can be formed.

[0034] When forming the movable electrode portion 20 of the second layer L2, silicon 200 that will become the base material 21 is also prepared in S21 of Fig. 4. In S22 of Fig. 4, an insulating film 22 such as silicon oxide is formed on the silicon 200. The insulating film 22 may be formed on the entire surface of the silicon 200 as shown in S22 of Fig. 4, or may be formed only on the upper surface of the silicon 200.

[0035] Next, in S23, an electret material 210 is formed on the upper surface of the insulating film 22 using a semiconductor manufacturing process. Next, in S24, the electret material 210 is divided into stripes to form electret electrodes 23. At this time, as shown in the middle diagram of Fig. 2, stripes are formed long in the Y direction. Then, in S25 of Fig. 4, the movable electrode section 20 can be formed by turning it upside down.

[0036] A modified example that achieves the function of the electret electrode 23 will be described. The silicon 200 that forms the substrate 21 may be processed to have unevenness in a striped pattern, and the electret material 210 may be formed on the stepped surface along the unevenness. When formed in this manner, the portion of the electret material 210 formed along the convex portions is close to the fixed electrode 13, and the portion formed along the concave portions is farther from the fixed electrode 13. In other words, the distance between the electret material 210 and the opposing fixed electrode 13 varies depending on the region in which it is formed. This allows for the formation of regions in which the electric field generated by the electret material 210 effectively reaches the opposing fixed electrode 13 and regions in which it does not effectively reach the fixed electrode 13. As a result, the region of the electret material 210 in which the electric field effectively reaches the opposing fixed electrode 13 can function in the same way as the electret electrode 23 described above.

[0037] 5, silicon 202 is also prepared in S31 when forming the outer peripheral support portion 40, flexible portion 51, and movable electrode support portion 52 of the third layer L3. Subsequently, an insulating film (not shown) is formed on the silicon 202, and the silicon 202 and insulating film are processed using semiconductor manufacturing processes such as photolithography and anisotropic etching to form members that will become the flexible portion 51 and its inner end portion 51a, the outer peripheral support portion 40, and the movable electrode support portion 52.

[0038] The flexible section 51 bends along the X direction, and it is desirable to configure the XZ cross-sectional dimensions so that the X-direction width dimension is less than or equal to the Z-direction thickness dimension so that it can easily deform when bending in the X direction. The peripheral support section 40 is disposed on the upper surface of the spacer 30. The X-direction width dimension and Z-direction thickness dimension of the peripheral support section 40 may have any relationship, but it is advisable to set the dimensional ratio taking into account the bonding state depending on the materials of the peripheral support section 40 and the spacer 30. This allows the structure of the third layer L3 to be configured.

[0039] Next, in step S33 of Figure 5, the structure of the third layer L3 and the structure of the movable electrode portion 20 of the second layer L2 are joined and combined. In this case, a part of the upper surface of the movable electrode portion 20 is joined to the lower surface of the movable electrode support portion 52.

[0040] Next, in step S34 of Figure 5, the fixed electrode portion 10 and the spacer 30 are combined with the structure formed in step S33. Specifically, the four corners of the outer peripheral support portion 40 in the XY direction are placed on the upper surface of the spacer 30 and joined together, thereby combining all the structures of the first layer L1 to the third layer L3. This completes the structure of the micro-electromechanical generator 1.

[0041] <Summary of this embodiment> According to this embodiment, since the electret electrode 23 is positioned to overlap with the elastic support portion 50 in the Z direction which intersects the X direction which is the deformation direction of the elastic support portion 50, the overlapping constituent region X0 can be effectively utilized to provide a movable electrode portion 20 with a large volume that protrudes downward from the elastic support portion 50.

[0042] As a result, the number of electret electrodes 23 can be placed in the configuration area X0 can be increased by the amount of the increased area of ​​the movable electrode portion 20 compared to the conventional design, and electret electrodes 23 can be placed in this configuration area X0. As a result, the number of electret electrodes 23 can be increased, which increases the opposing area between the electret electrodes 23 that generate electrostatic induction and the fixed electrode 13, thereby improving power generation efficiency.

[0043] Even when it is necessary to make the device size of the micro-electromechanical generator 1 as small as possible without changing the resonant frequency, which is the vibration frequency of the movable electrode portion 20, the structure of this embodiment can be applied to make it possible to configure the device without changing the size of the elastic support portion 50.

[0044] (Second embodiment) The second embodiment will be described with reference to Figures 6 to 8. Parts with the same structural components as the micro-electromechanical generator 1 of the first embodiment are denoted by the same reference numerals, and their descriptions will be omitted as needed. The description will focus on the differences.

[0045] As shown in FIG. 6, the microelectromechanical generator 201 includes a fixed electrode portion 10, a movable electrode portion 220, spacers 230, 225, a movable electrode support portion 252, a peripheral support portion 240, an elastic support portion 250, and an insulating film 272.

[0046] The microelectromechanical generator 201 includes a movable electrode part 220 instead of the movable electrode part 20. The movable electrode part 220 configures an electret electrode 23 on the lower surface of a substrate 21 via an insulating film 22. The insulating film 22 is configured on the upper and lower surfaces of the substrate 21. The structure of the electret electrode 23 is the same as that in the first embodiment, and therefore description thereof will be omitted.

[0047] The microelectromechanical generator 201 has spacers 230 formed on the upper surface of the fixed electrode part 10 in place of the spacers 30. Like the spacers 30 in the first embodiment, the spacers 230 are formed at the four corners of the substrate 11 and insulating film 12 in the XY plane. See the configuration area of ​​the spacer 30 in the upper diagram of Figure 2.

[0048] The height of the spacer 230 is configured to match the interface between the substrate 21 of the movable electrode section 220 and the electret electrode 23. A spacer 225 is configured on the spacer 230. Although not shown, this spacer 225 is configured in a rectangular frame shape in the XY plane, and is configured to have the same structure as the outer periphery support section 240 in the XY plane. In addition, the height of the spacer 225 in the Z direction matches the height of the substrate 21 of the movable electrode section 220 in the Z direction.

[0049] On the upper surface of spacer 225, outer periphery support part 240 is formed in place of outer periphery support part 40, with insulating film 272 interposed therebetween. Outer periphery support part 240 is formed in a rectangular frame shape in the XY plane, similar to outer periphery support part 40 of the first embodiment, and is configured in the same structure as spacer 225 in the XY plane. The height of outer periphery support part 240 in the Z direction matches the height of flexible part 251 in the Z direction.

[0050] The insulating film 272 is formed interposed between the outer peripheral support portion 240 and the spacer 225. The side edges of the insulating film 272 are configured to be located outside the inner surface in the X direction of the outer peripheral support portion 240 and the spacer 225. In other words, the side surface of the insulating film 272 is not flush with the side surface of the outer peripheral support portion 240 or the spacer 225.

[0051] On the inner side of the outer peripheral support portion 240 in the XY plane, an elastic support portion 250 is configured, replacing the elastic support portion 50. The elastic support portion 250 includes a flexible portion 251. The function of the flexible portion 251 is the same as that of the flexible portion 51 in the first embodiment, so its description is omitted. In the longitudinal cross-sectional view shown in Figure 6, the X-direction width of the innermost inner end portion 251a of the flexible portion 251 is wider than the X-direction width of the structure of the flexible portion 251 other than the inner end portion 251a.

[0052] Furthermore, in the structure of the inner end portion 251a of the flexible portion 251, the movable electrode support portion 252 is joined to a part of the center in the X direction of the inner end portion 251a, and the movable electrode support portion 252 is not joined to the other flexible portions 251 of the inner end portion 251a.

[0053] Here, a configuration has been described in which the movable electrode portion 220 is joined to the inner end portion 251a of the flexible portion 251 via the movable electrode support portion 252, and the movable electrode support portion 252 is not joined to any other flexible portion 251 of the inner end portion 251a, but the configuration is not limited to this. The area of ​​contact with the movable electrode portion 220 at the inner end portion 251a of the flexible portion 251 may be less than the area of ​​contact with the movable electrode portion 220 at the inner end portion 251a of the flexible portion 251. Thus, in this embodiment, the elastic support portion 250, the movable electrode portion 220, and the outer peripheral support portion 240 are integrally configured.

[0054] <Manufacturing method> In this embodiment, the peripheral support member 240, the elastic support member 250, and the movable electrode member 220 are integrally formed by processing the SOI substrate 270 using a semiconductor manufacturing process, and a manufacturing method of the microelectromechanical generator 201 using the SOI substrate 270 will be described with reference to FIGS. 7 and 8. SOI stands for Silicon On Insulator. As shown in S41 of FIG. 7, the SOI substrate 270 is formed by bonding a silicon substrate 271 to a silicon substrate 273 via an insulating film 272. When forming the SOI substrate 270, both surfaces of the silicon substrate 273 are thermally oxidized to form an oxide film (not referenced) for the insulating film 22 underlying the electret material 274. Next, in S42 of FIG. 7, the electret material 274 is formed on the upper surface of the SOI substrate 270.

[0055] 7, the electret material 274 is anisotropically etched to form the electret electrode 23. Next, in S44 of Fig. 8, the silicon substrate 273 is anisotropically etched into a rectangular frame shape up to the top surface of the insulating film 272, separating the portion that will become the base material 21 of the movable electrode portion 220 from the portion that will become the spacer 225, thereby forming the portion that will become the movable electrode portion 220. In the subsequent steps, in S45 to S47, the SOI substrate 270 is turned upside down, and the silicon substrate 271 and insulating film 272 are etched. To prevent the effects of this etching process, it is preferable to apply a resist or the like to the movable electrode portion 220 in advance to protect the electret electrode 23 and insulating film 22 of the movable electrode portion 220. The resist is not shown in S44 to S46.

[0056] Next, the SOI substrate 270 is turned upside down in the Z direction, and in S45 of FIG. 8, the silicon substrate 271 is anisotropically etched down to the upper surface of the insulating film 272 by a semiconductor process, thereby forming the flexible portion 251 and the outer periphery support portion 240.

[0057] After processing the flexible portion 251, a portion of the insulating film 272 is isotropically etched. At this time, by removing the insulating film 272 by wet etching using hydrofluoric acid, it is possible to remove the insulating film 272 that exists between the flexible portion 251 and the base material 21 of the movable electrode portion 220. Here, the width in the X direction of the inner end 251a of the flexible portion 251 is configured to be wider than the width in the X direction of the remaining flexible portion 251.

[0058] Therefore, by adjusting the execution time of wet etching the insulating film 272, it is possible to remove all of the insulating film 272 below the structure of the flexible portion 251 other than the inner end 251a, while leaving a portion of the insulating film 272 below the center of the structure of the inner end 251a of the flexible portion 251 to form the movable electrode support portion 252. While the inner end 251a of the flexible portion 251 is partially joined to the movable electrode portion 220, it is possible to release the flexible portion 251 into a state in which it can deform in the X direction. Note that, because the insulating film 272 directly below the outer periphery support portion 240 also remains, it is possible to support the outer periphery support portion 240 from below. After this, the resist or the like (not shown) covering the movable electrode portion 220 is removed.

[0059] A spacer 230 is formed on the upper surface of the fixed electrode portion 10, and the structure formed in S46 is joined so that a spacer 225 is placed on the upper surface of the fixed electrode portion 10 and the spacer 230. This allows the micro-electromechanical generator 201 to be constructed.

[0060] <Summary of this embodiment> In the first embodiment, the flexible portion 51 and the movable electrode portion 20 were fabricated separately, and then the movable electrode portion 20 was bonded and fixed to the end of the flexible portion 51. However, in this embodiment, the SOI substrate 270 is processed using a semiconductor manufacturing process, so that the outer peripheral support portion 240, the flexible portion 251 of the elastic support portion 250, and the movable electrode portion 220 are integrally formed. This eliminates the need for a bonding or joining process for the movable electrode portion 220 and the flexible portion 251, thereby reducing the bonding / joining costs.

[0061] If the opposing positions of the movable electrode section 220 and the flexible section 251 are shifted, for example, in the X direction or Y direction, there is a concern that the overlapping area between the electret electrode 23 and the fixed electrode 13 will decrease. However, in this embodiment, since the SOI substrate 270 is used, it is possible to prevent misalignment between the movable electrode section 220 and the flexible section 251. As a result, it is possible to prevent misalignment between the electret electrode 23 of the movable electrode section 220 and the fixed electrode 13, and to prevent a decrease in the amount of power generation.

[0062] As will be explained in the embodiments described later, if the magnitude of vibration is expected to be greater in the X direction than in the Z direction, it is desirable to set the thickness of the flexible portion 251 in the Z direction to be greater than or equal to the width in the X direction, as shown in Figure 6.

[0063] (Third embodiment) A third embodiment will be described with reference to Figures 9 to 12. In the first and second embodiments, micro-electromechanical generators 1 and 201 that generate electricity in response to vibrations in the X direction were described. In this embodiment, a micro-electromechanical generator 301 that generates electricity in response to vibrations in the Y direction, which is perpendicular to the X direction in a planar manner, will be described.

[0064] In this embodiment, the reference numerals of components corresponding to those of the first embodiment are given a "3" in the hundreds place, and explanations of components with the same structure are omitted, with the focus being on the differences. Note that the cross-sectional structure along the XZ direction is substantially the same as that of the first embodiment, and therefore illustrations of the cross-sectional structure along the XZ direction are omitted in this embodiment.

[0065] As shown in Figure 9, the micro-electromechanical generator 301 includes a fixed electrode section 310 in place of the fixed electrode section 10, a movable electrode section 320 in place of the movable electrode section 20, and a first axial elastic support section 350x and a second axial elastic support section 350y in place of the elastic support section 50.

[0066] In the first layer L1 shown in the upper part of Figure 9, the fixed electrode section 310 includes a substrate 311 instead of a substrate 11 and an insulating film 312 instead of an insulating film 12. Furthermore, as shown in the structure of the first layer L1 in the upper part of Figure 9, the fixed electrode section 310 has fixed electrodes 313 arranged at grid point positions with predetermined intervals in each of the X and Y directions. Each fixed electrode 313 is configured in a rectangular shape in the X and Y directions and is arranged periodically in the X and Y directions.

[0067] In the second layer L2 shown in the middle diagram of Figure 9, the movable electrode portion 320 includes a base material 321 instead of the base material 21, and an insulating film 322 instead of the insulating film 22. Furthermore, as shown in the structure of the second layer L2 in the middle diagram of Figure 9, the movable electrode portion 320 has electret electrodes 323 positioned at grid points with predetermined intervals in the XY direction.

[0068] Figure 10 shows a schematic top view illustrating the arrangement of the fixed electrode 313 and the electret electrode 323. In Figure 10, the fixed electrode 313 is shown by a thick outer border, and the electret electrode 323 is shown by a thin outer border. As shown in Figure 10, it is desirable to arrange the fixed electrode 313 and the electret electrode 323 in a staggered or zigzag pattern. In this embodiment, the electret electrode 323 moves in both the X and Y directions, and this arrangement allows for efficient transfer of the charge on the fixed electrode 313 in accordance with the movement of the electret electrode 323.

[0069] As shown in Figure 10, the fixed electrodes 313 positioned at grid points are electrically connected along the XY diagonal direction through wiring (not shown) configured in the base material 311. In this case, as shown in Figure 10, the fixed electrodes 313 are divided into a first current path A1 and a second current path A2, with adjacent electrodes connected to each other by separate first and second current paths A1 and A2, respectively. Although not shown, the first current path A1 is connected to one end of the load, and the second current path A2 is connected to the other end of the load.

[0070] In the third layer L3 of Figure 9, the pair of first axial elastic support parts 350x are arranged symmetrically in the X direction with respect to the X-direction center of the outer peripheral support part 40. The base ends 350xa of the pair of first axial elastic support parts 350x are connected to the outer peripheral support part 40 at their respective Y-direction centers. The first axial elastic support parts 350x are not connected to the outer peripheral support part 40 at any positions other than the base ends 350xa.

[0071] Each pair of first axial elastic support parts 350x comprises a first flexible part 351x and a movable electrode support part 352x. As shown in the lower diagram of Figure 9, each first flexible part 351x has a linear portion that is configured parallel to the Y direction, connected at both ends in the Y direction via short connecting parts, and a space with a long axis in the Y direction is provided inside the connecting linear portion. By adopting this structure, the first flexible part 351x is flexible in the X direction, and the first axial elastic support part 350x can deform the first flexible part 351x in the X direction while supporting the movable electrode part 320 with the movable electrode support part 352x. As a result, the first flexible part 351x can vibrate in the X direction.

[0072] On the other hand, the pair of second axial elastic support parts 350y are arranged symmetrically in the Y direction with respect to the Y-direction center of the outer peripheral support part 40. The base ends 350ya of the pair of second axial elastic support parts 350y are connected to the outer peripheral support part 40 at their respective X-direction centers. The second axial elastic support parts 350y are not connected to the outer peripheral support part 40 at any positions other than the base ends 350ya.

[0073] Each of the pair of second axial elastic support members 350y includes a second flexible member 351y and a movable electrode support member 352y. As shown in the lower diagram of FIG. 9, each of the second flexible members 351y has linear portions extending parallel to the X direction, which are connected at both ends in the X direction via short connecting portions, and a space with a major axis in the X direction is provided inside the connecting linear portions.

[0074] By adopting this structure, the second flexible portion 351y is flexible in the Y direction, and the second axial elastic support portion 350y can deform the second flexible portion 351y in the Y direction while supporting the movable electrode portion 320 with the movable electrode support portion 352y. As a result, the second flexible portion 351y can vibrate in the Y direction.

[0075] The first and second axial elastic support members 350x and 350y support the movable electrode unit 320 at four points corresponding to the positions of the movable electrode support members 352x and 352y. When an external force is applied and the movable electrode unit 320 of the second layer L2 moves in the X direction, the electret electrode 323 vibrates in the +X and −X directions, as shown in the upper and lower diagrams of FIG. 11. When an external force is applied and the movable electrode unit 320 of the second layer L2 moves in the Y direction, the electret electrode 323 vibrates in the +Y and −Y directions, as shown in the upper and lower diagrams of FIG. 12. Therefore, whether the movable electrode unit 320 of the second layer L2 moves in the X or Y direction, the positive charges on the fixed electrode 313 are attracted to the negative charges on the electret electrode 323.

[0076] As a result, the positive charge on the fixed electrode 313 moves along the first current path A1 and the second current path A2, supplying the generated current to the load. Consequently, the micro-electromechanical generator 301 can generate electricity in both the X and Y directions of vibration.

[0077] In this embodiment, a second flexible portion 351y is added compared to the previously described embodiment. As a result, the area ratio occupied by the first flexible portion 351x and the second flexible portion 351y relative to the predetermined planar size of the device becomes larger.

[0078] However, as shown in the middle and bottom diagrams of Figure 9, the electret electrode 323 can be mounted overlapping in the Z direction on both the constituent area X0 of the first flexible portion 351x and the constituent area Y0 of the second flexible portion 351y, so that the constituent area X0 of the first flexible portion 351x and the constituent area Y0 of the second flexible portion 351y can be utilized as constituent areas of the electret electrode 323, thereby improving power generation efficiency.

[0079] <Summary of this embodiment> According to the third embodiment, there is provided a first axial elastic support member 350x having a first flexible member 351x that is deformable along the X direction, and a second axial elastic support member 350y having a second flexible member 351y that is deformable along the Y direction that intersects the X direction in a plane. When an external force is applied, the first flexible member 351x deforms in the X direction, causing the electret electrode 323 of the movable electrode member 320 to vibrate in the X direction and generate electricity, and the second flexible member 351y deforms in the Y direction, causing the electret electrode 323 of the movable electrode member 320 to vibrate in the Y direction and generate electricity. As a result, power can be generated by vibrations in both the X and Y directions, and a large amount of power can be generated.

[0080] (Fourth embodiment) The fourth embodiment will be described with reference to Figures 13 to 15. In the first and second embodiments, micro-electromechanical generators 1 and 201 that generate electricity in response to vibrations in the X direction were described, but in this embodiment, a micro-electromechanical generator 401 that generates electricity in response to vibrations in the Z direction perpendicular to the X direction will be described.

[0081] In this embodiment, the hundreds digit of the reference numeral for the components corresponding to the components of the first embodiment is "4," and the explanation of parts with the same structure is omitted, with the explanation focusing on the different parts.

[0082] The microelectromechanical generator 401 includes a fixed electrode portion 10, a movable electrode portion 20, a spacer 30, a peripheral support portion 440, and an elastic support portion 450.

[0083] The outer peripheral support portion 440 and the elastic support portion 450 are provided in place of the outer peripheral support portion 40 and the elastic support portion 50 of the first embodiment, respectively. The outer peripheral support portion 440 has a different height in the Z direction than the outer peripheral support portion 40, but its function is the same as in the first embodiment.

[0084] The elastic support member 450 includes a flexible member 451 and a movable electrode support member 452, and the flexible member 451 is configured to have the same height in the Z direction as the outer peripheral support member 440. The cross-sectional dimension of the flexible member 451 of the elastic support member 450 along the XZ direction is smaller in the direction in which the vibration is more strongly detected, either the X direction or the Z direction. In this embodiment, for example, the Z direction dimension is configured to be smaller than the X direction dimension, or the X direction dimension and the Z direction dimension are configured to be the same dimension.

[0085] The reason for this will be explained below with reference to Fig. 14. The micro-electro-mechanical generator 401 is placed in a space that vibrates in the X and Z directions. As shown in Fig. 14, a sensor S for measuring the running state of an automobile C is placed on the back surface of the inner tread of a tire T. This type of sensor S detects the air pressure, temperature, and acceleration information of the tire T, and transmits the detected information to an electronic control unit (ECU: not shown) of the vehicle via wireless communication. The sensor S requires a power supply device to supply power for its operation, and it is conceivable that the micro-electro-mechanical generator 401 of this embodiment can be applied to this power supply device.

[0086] When car C is traveling, it is accelerated by the repulsive force from the road surface R, so the acceleration that occurs in the normal direction of the road surface R on which tire T rotates is likely to be greater than the acceleration that occurs in the tangential direction of road surface R. For this reason, improved power generation efficiency can be expected by using a structure that generates electricity by vibrating tire T in the normal direction to road surface R rather than in the tangential direction to road surface R.

[0087] When placing the microelectromechanical generator 401 inside the sensor S, if the tangential direction of the road surface R is the X direction and the normal direction of the road surface R is the Z direction, it is likely that (X direction vibration) < (Z direction vibration), so it is desirable to set the cross-sectional dimensions of the flexible part 451 to X direction width ≥ Z direction thickness. This makes it possible to increase the sensitivity to larger vibrations, thereby increasing the power generation efficiency according to vibrations.

[0088] When the micro-electromechanical generator 401 is placed inside the tire T, the movable electrode section 20 vibrates vertically in the Z direction, as shown in Figure 15. At this time, the elastic support section 450 continues to hold the movable electrode section 20 while the flexible section 451 bends vertically. As the movable electrode section 20 repeatedly vibrates vertically in the Z direction, the electret electrode 23 of the movable electrode section 20 repeatedly approaches and moves away from the fixed electrode 13, changing the gap between the electret electrode 23 and the fixed electrode 13. As a result, the amount of induced charge in the fixed electrode 13 changes, causing current to flow and supplying generated current to the load.

[0089] In this embodiment, the XZ cross-sectional dimensions of the flexible portion 451 are smaller in the Z direction than in the X direction, allowing the flexible portion 451 to be easily deformed in the Z direction. Furthermore, even if the dimensions in the X and Z directions are the same, the flexible portion 451 can still be easily deformed. As a result, the movable electrode portion 20 can be vibrated significantly in the Z direction, improving power generation efficiency.

[0090] <Summary of this embodiment> According to this embodiment, the structure is designed to generate electricity even in the Z direction vibration. In this case, the structure of the micro-electromechanical generator 401 of this embodiment is the same as that of the micro-electromechanical generator 1 of the first embodiment, but the cross-sectional dimensions of the flexible part 451 are made smaller in the Z direction than in the X direction or the same in the Z direction so that the flexible part 451 can be easily deformed in the Z direction, which is where the vibration becomes larger, than in the X direction. As a result, the movable electrode part 20 can be vibrated more greatly in the Z direction, and the power generation efficiency can be improved.

[0091] (Fifth embodiment) A fifth embodiment will be described with reference to Figure 16. As shown in Figure 16, the micro electromechanical generator 501 includes a pair of fixed electrode portions 10, a pair of movable electrode portions 20, a pair of spacers 30, an outer peripheral support portion 540, and an elastic support portion 550 in the Z direction.

[0092] In this embodiment, the hundreds digit of the reference numeral for components corresponding to the components of the first embodiment is "5," and the description of parts with the same structure is omitted, with the focus being on the different parts.

[0093] As shown in Figure 16, the structure consists of layers L1a, L2a, L3a, L2b, and L1b stacked from bottom to top, and these layers L1a, L2a, L3a, L2b, and L1b are configured symmetrically from top to bottom with respect to layer L3a.

[0094] Layers L1a and L1b are configured with a pair of fixed electrode portions 10 arranged symmetrically in the Z direction, and layers L2a and L2b are configured with a pair of movable electrode portions 20 arranged symmetrically in the Z direction. Layer L3a is configured with an outer peripheral support portion 540 and an elastic support portion 550.

[0095] The outer peripheral support portion 540 has spacers 30 joined to its upper and lower ends and is sandwiched between these pair of spacers 30. An elastic support portion 550 is formed on the inner side of the outer peripheral support portion 540 in the X direction. The structure of these outer peripheral support portion 540 and elastic support portion 550 is the same as the joining structure of the outer peripheral support portion 40 and elastic support portion 50 in the first embodiment (see, for example, the lower diagram in Figures 1 and 2), so a description is omitted.

[0096] The elastic support portion 550 comprises a flexible portion 551 and a pair of movable electrode support portions 552. The movable electrode support portions 552 are joined to the inner end portion 551a of the flexible portion 551 in the Z direction, both vertically and horizontally, and further join the movable electrode portion 20 to the upper and lower parts, respectively. As a result, the elastic support portion 550 is fixed to a predetermined layer L3a in the Z direction and supports the flexible portion 551 so that it can be deformed in the X direction. The movable electrode support portions 552 joined to the flexible portion 551 support the movable electrode portion 20 vertically in the Z direction.

[0097] Therefore, as the flexible portion 551 of the elastic support portion 550 vibrates in the X direction, the electret electrode 23 vibrates in the X direction relative to the fixed electrode 13, and current can be supplied to a load (not shown), similar to the first embodiment.

[0098] Furthermore, when the movable electrode portion 20 vibrates in the Z direction, the electret electrode 23 repeatedly moves toward and away from the fixed electrode 13, thereby generating power in the same manner as in the fourth embodiment. If it is expected that the vibration in the X direction is greater than the Z direction, it is desirable that the Z direction thickness of the flexible portion 551 be equal to or greater than the X direction width, as shown in Fig. 16. Conversely, if it is expected that the vibration in the Z direction is greater than the X direction, it is desirable that the X direction width of the flexible portion 551 be equal to or greater than the Z direction thickness.

[0099] Because the fixed electrode section 10 and the movable electrode section 20 have a symmetrical structure in the Z direction, a large amount of power can be generated. By stacking the movable electrode sections 20 in the Z direction, the stacking space can be effectively utilized, increasing the opposing area between the electret electrode 23 and the fixed electrode 13, and thus a large amount of power can be generated.

[0100] For the sake of simplicity, the structure of the first embodiment in which the movable electrode portion 20 vibrates in the X direction is shown here as being configured to be vertically symmetrical in the Z direction with the layer L3a at the center, but this is not limiting. For example, the structure of the third embodiment in which the movable electrode portion 320 vibrates in the X and Y directions may be configured to be vertically symmetrical in the Z direction with the layer L3a at the center. By configuring the structure of the third embodiment as a symmetrical structure as in this embodiment, the amount of power generation corresponding to vibration in the X and Y directions can be increased.

[0101] (Sixth embodiment) The sixth embodiment will be described with reference to Figures 17 and 18. For example, in the first embodiment, the electret electrodes 23 of the fixed electrode section 10 and the movable electrode section 20 are respectively formed on separate substrates 11 and 21 and arranged opposite each other in the Z direction, but the present invention is not limited to this structure. For example, a microelectromechanical generator 601 shown in Figures 17 and 18 may be configured.

[0102] The micro-electromechanical generator 601 is constructed by stacking the structures of the first layer L11 and the second layer L12 shown in Figures 17 and 18. Note that the upper part of Figure 17 and the lower part of Figure 18 also show schematic longitudinal cross-sectional views along the line XV-XV.

[0103] As shown in Fig. 17, the microelectromechanical generator 601 has an outer support portion 640 on the first layer L11. The outer support portion 640 has an outer frame portion 640a configured in a rectangular frame shape and a plurality of protruding portions 640b protruding from the outer frame portion 640a. The plurality of protruding portions 640b are each configured to protrude from a part of the Y-direction inner edge of the rectangular frame of the outer frame portion 640a toward the center in the Y direction. The outer frame portion 640a of the outer support portion 640 is configured to support a pair of elastic support portions 650 at the center in the Y direction of its inner wall.

[0104] The pair of elastic support parts 650 are arranged symmetrically in the X direction with respect to the X-direction central part of the outer support part 640. The base ends 650a of the pair of elastic support parts 650 are each connected to the outer support part 640 at the Y-direction central part. The elastic support parts 650 are not connected to the outer support part 640 at any position other than the base ends 650a.

[0105] Each of the pair of elastic support members 650 includes a flexible member 651 and a movable electrode support member 652. As shown in the lower diagram of Fig. 17, each of the flexible members 651 has linear portions formed parallel to the Y direction, which are connected at both ends in the Y direction via short connecting members, and a space with a major axis along the Y direction is provided inside the connecting linear portions.

[0106] 17 is joined to the center in the Y direction of the inner end of the flexible portion 651, and supports the movable electrode supported portion 624 (see FIG. 18) of the second layer L12 from below in the Z direction. By employing such a structure, the flexible portion 651 is flexible in the X direction, and the elastic support portion 650 can deform the flexible portion 651 in the X direction while supporting the movable electrode portion 620 (see FIG. 18).

[0107] 17 and 18, elastic support member 650 is preferably configured so that the XZ cross-sectional dimensions of flexible member 651 are such that the X-direction width is equal to or less than the Z-direction thickness, and in this case, the linear portion of flexible member 651 can easily deform when it flexes and vibrates in the X direction. Elastic support member 650 is joined to a part of the lower surface of movable electrode member 620 from movable electrode support member 652 configured in flexible member 651.

[0108] As shown in the plan view in Figure 18, in this embodiment, the fixed electrode section 610 and the movable electrode section 620 are configured on the same second layer L12. The fixed electrode section 610 comprises a fixed base material 611 and a plurality of fixed electrodes 613. The fixed base material 611 is configured on the second layer L12 above the outer support section 640 of the first layer L11, and comprises an outer frame section 611a configured in the shape of a rectangular frame, and a plurality of protruding sections 611b protruding from the outer frame section 611a.

[0109] Multiple protruding portions 611b are each formed by projecting toward the center in the Y direction from a part of the inner edge in the Y direction of the outer frame portion 611a. The outer frame portion 611a and protruding portions 611b of the fixing base material 611 are connected to the outer frame portion 640a and protruding portions 640b of the outer support portion 640, respectively. Multiple fixing electrodes 613 are formed by protruding in a comb-like manner in the X direction from the side walls of the outer frame portion 611a and the side walls of the protruding portions 611b of the fixing base material 611, respectively.

[0110] On the other hand, the movable electrode portion 620 comprises a base material 621, an insulating film 622, an electret electrode 623, and a movable electrode support portion 624 in the second layer L12. The base material 621 includes movable pieces 621b positioned between the outer frame portion 611a and the protruding portion 611b, and between adjacent protruding portions 611b, and is formed in a structure in which the plurality of movable pieces 621b are connected to a base body 621a that is movable in the X direction.

[0111] The movable electrode supporting portion 652 of the first layer L11 is located below the movable electrode supported portion 624 of the second layer L12, and the movable electrode supported portion 624 and the movable electrode supporting portion 652 are joined together.

[0112] The movable electrode portion 620 includes an electret electrode 623 that protrudes in a comb-like manner from the exposed surface of the movable piece portion 621b of the base material 621 via an insulating film 622. The base material 621 is made of silicon, and the electret electrode 623 is formed on the side wall of the base material 621. As shown in Figures 17 and 18, the electret electrode 623 and the fixed electrode 613 are arranged in a facing configuration.

[0113] Although not shown, the fixed electrode 613 is configured such that a fixed electrode 613a extending in the X-direction from the left wall of the outer frame portion 611a and the protruding portion 611b is connected to one end of the load, and a fixed electrode 613b extending in the X-direction from the right wall of the outer frame portion 611a and the protruding portion 611b is connected to the other end of the load.

[0114] By employing such a structure, the elastic support member 650 is configured to support the movable electrode member 620 by the flexible member 651. When an external force is applied and the flexible member 651 is bent and deformed in the X direction, the movable electrode member 620 moves in the X direction, and the opposing area between the electret electrode 623 and the fixed electrode 613 increases or decreases.

[0115] As a result, if electret electrode 623 is negatively charged, the positive charge on fixed electrode 613 moves, allowing current to be supplied to the load. When the positive charge on fixed electrode 613a increases / decreases, the positive charge on fixed electrode 613b decreases / increases, allowing current to be supplied to the load.

[0116] This provides the same effects as the embodiment described above. Specifically, the flexible portion 651 and the electret electrode 623 can be stacked in the Z direction, which is the thickness direction of the first layer L11 and the second layer L12. This allows for effective use of the region, increases the facing area between the fixed electrode 613 and the electret electrode 623, and enables the generation of a large amount of electricity.

[0117] (Other embodiments) The present invention is not limited to the above-described embodiment, and the following modifications or extensions are possible. For example, a configuration has been described in which the flexible portions 51, 251, 451, and 551 are joined to the movable electrode portion 20 via the movable electrode support portions 52, 252, 452, and 552 at their inner ends 51a, 251a, 451a, and 551a, but the configuration is not limited to this. The "flexible portions" may be joined in any configuration as long as they are arranged to overlap with the "electret electrode" in the Z direction.

[0118] For example, in the first embodiment, the fixed electrode 13 is named as the fixed electrode 13 for the sake of convenience of explanation, but is not limited to this, and the electrode does not need to be fixed as long as its relative position with respect to the electret electrode 23 changes so that the facing area changes relative to the electret electrode 23.

[0119] Although the present disclosure has been described based on the above-described embodiment, it is understood that the present disclosure is not limited to the embodiment or the structure described in the embodiment. The present disclosure also encompasses various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure. [Explanation of symbols]

[0120] In the drawings, 1, 201, 301, 401, 501, and 601 indicate microelectromechanical generators, 10 indicates a fixed electrode portion, 13 indicates a fixed electrode (electrode), 20, 220, 320, and 620 indicate movable electrode portions, 23, 323, and 623 indicate electret electrodes, 50, 250, 450, 550, and 650 indicate elastic support portions, 350x indicates a first axis elastic support portion (elastic support portion), 350y indicates a second axis elastic support portion (elastic support portion), 51, 251, 451, and 651 indicate flexible portions, 351x indicates a first flexible portion (flexible portion), 352x indicates a second flexible portion (flexible portion), and 52, 252, 352x, 352y, 452, and 652 indicate movable electrode support portions.

Claims

1. a movable electrode portion (20; 220; 320; 620) in which electret electrodes (23; 323) are arranged opposite to periodically arranged electrodes (13); and an elastic support portion (50; 250; 350x, 350y; 450; 550; 650) configured to support the movable electrode portion by a flexible portion (51; 251; 351x, 351y; 451; 651), and which increases or decreases the opposing area between the electret electrode and the electrode by deforming the flexible portion in the direction of a first axis, The electret electrode is arranged to overlap the elastic support portion in a direction intersecting the direction of the first axis, and generates electricity by vibrating.

2. The elastic support portion and the movable electrode portion are integrally formed in the intersecting direction, and the elastic support portion is configured to support the movable electrode portion at a part of the flexible portion, 2. The micro-electromechanical generator according to claim 1, wherein the area of ​​contact between the flexible portion and the movable electrode portion and ... other portion of the flexible portion is smaller than the area of ​​contact between the flexible portion and the movable electrode portion and the other portion of the flexible portion.

3. The elastic support portions (350x, 350y) include a first axis elastic support portion (350x) having, as the flexible portion, a first flexible portion (351x) deformable along the direction of the first axis, and a second axis elastic support portion (350y) having, as the flexible portion, a second flexible portion (351y) deformable along the direction of a second axis that intersects with the first axis in a plane, 2. The microelectromechanical generator according to claim 1, wherein when an external force is applied, the first flexible portion deforms in the direction of the first axis, causing the electret electrode of the movable electrode portion to vibrate in the direction of the first axis and generate electricity, and the second flexible portion deforms in the direction of the second axis, causing the electret electrode of the movable electrode portion to vibrate in the direction of the second axis and generate electricity.

4. The vibration source is disposed in a space that vibrates in a direction of the first axis and a direction of a third axis that intersects with the first axis, A microelectromechanical generator as described in claim 1, wherein the cross-sectional dimensions of the flexible portion of the elastic support portion along the first axis and the third axis are smaller in the direction of the first axis or the third axis in which greater vibration is detected, or are the same in the direction of the first axis and the direction of the third axis.

5. 2. The micro-electromechanical generator according to claim 1, wherein the movable electrode portion and the electrode are configured as a pair with the elastic support portion sandwiched therebetween.

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