Power generator

Abstract

To provide a power generator that can reduce a clearance between an electret film and an electrode and has excellent power generation efficiency.SOLUTION: A power generator has: a shaft member; a rotor plate that includes a silicon substrate where an insertion hole into which the shaft member is inserted is formed; a first pedestal that is arranged opposite to the rotor plate; an electret film that is arranged on one of the rotor plate and the first pedestal so as to be opposite to the other; and a first electrode that is arranged on the other of the rotor plate and the first pedestal so as to be opposite to the electret film. The shaft member has a groove formed extending in an axial direction. The rotor plate has a plurality of first beam parts that each extend from an outer edge of the insertion hole into the insertion hole and are each arranged in the groove at a leading end, and second beam parts that are each arranged between the plurality of first beam parts and press the shaft member at a leading end.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power generation device. [Background technology]

[0002] The power generating device described in Patent Document 1 includes a first substrate, a plurality of electret electrodes arranged on the first substrate, a second substrate arranged opposite the first substrate, a plurality of electrodes arranged on the second substrate, and a rotating shaft coaxially connecting the first substrate and the second substrate. In such a power generating device, power is generated by the relative rotation of the first substrate and the second substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-192577 A Summary of the Invention [Problem to be solved by the invention]

[0004] In such a power generating device, as long as the electret electrode and the electrode do not come into contact with each other, it is possible to generate power more efficiently by reducing the distance between the electret electrode and the electrode. However, it is difficult to reduce the distance between the electret electrode and the electrode due to factors such as the low flatness of the first substrate, the tendency of the first substrate to warp or bend, and the inclination of the first substrate and the second substrate with respect to the rotation axis. [Means for solving the problem]

[0005] The power generating device of the present invention comprises a shaft member and a rotating plate including a silicon substrate having an insertion hole into which the shaft member is inserted; A first base disposed opposite the rotating plate; an electret film disposed on one of the rotating plate and the first base so as to face the other; a first electrode disposed on the other of the rotating plate and the first base so as to face the electret film; The shaft member has a groove formed extending in the axial direction, The rotating plate has a plurality of first beam portions extending into the insertion hole from the outer edge thereof and having their tips positioned within the groove, and a second beam portion positioned between the plurality of first beam portions and pressing the shaft member at its tip. [Brief description of the drawings]

[0006] [Figure 1] 1 is a cross-sectional view showing a power generating device according to a first embodiment. [Diagram 2] 2 is a perspective view of a shaft member of the power generating device shown in FIG. 1. [Diagram 3] 2 is a plan view of a rotating plate of the power generating device shown in FIG. 1. [Figure 4] 4 is an enlarged plan view showing a holding portion of the rotating plate. FIG. [Diagram 5] 4 is an enlarged plan view showing a holding portion of the rotating plate. FIG. [Figure 6] 2 is an enlarged cross-sectional view showing a first spacer and a second spacer of the power generating device shown in FIG. 1. [Figure 7] FIG. 4 is a cross-sectional view showing a power generating device according to a second embodiment. [Figure 8] 8 is a perspective view of a shaft member of the power generating device shown in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a power generating device of the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

[0008] First Embodiment FIG. 1 is a cross-sectional view showing a power generating device according to a first embodiment. FIG. 2 is a perspective view of a shaft member of the power generating device shown in FIG. 1. FIG. 3 is a plan view of a rotating plate of the power generating device shown in FIG. 1. FIGS. 4 and 5 are enlarged plan views showing a holding portion of the rotating plate. FIG. 6 is an enlarged cross-sectional view showing a first spacer and a second spacer of the power generating device shown in FIG. 1. In the following, for convenience of explanation, the upper side in FIG. 1 is also referred to as the upper side, and the lower side is also referred to as the lower side.

[0009] The power generation device 1 shown in Figure 1 has a rotating plate 2, a first pedestal 31 arranged opposite the upper surface 2a of the rotating plate 2 with a gap G1 between them, a second pedestal 32 arranged opposite the lower surface 2b of the rotating plate 2 with a gap G2 between them, a side wall portion 33 connecting the first pedestal 31 and the second pedestal 32, an axial member 5 connected to the rotating plate 2, a plurality of electret films 6 arranged on the upper surface 2a and lower surface 2b of the rotating plate 2, a plurality of first electrodes 71 arranged on the lower surface 31b of the first pedestal 31, a plurality of second electrodes 72 arranged on the upper surface 32a of the second pedestal 32, a first spacer 91 arranged between the rotating plate 2 and the first pedestal 31, and a second spacer 92 arranged between the rotating plate 2 and the second pedestal 32.

[0010] As in the power generating device 1, by arranging the first and second electrodes 71, 72 on both the top and bottom of the rotating plate 2, the amount of power generated by the power generating device 1 can be increased. However, the configuration of the power generating device 1 is not particularly limited, and for example, the second seat 32 and the second electrode 72 may be omitted, and the first seat 31 and the first electrode 71 may be arranged only on the upper side of the rotating plate 2. In this case, the amount of power generated is lower than in this embodiment, but the power generating device 1 can be made thinner.

[0011] ≪Shaft member 5≫ As shown in Fig. 1, the shaft member 5 is a columnar member that extends vertically in a straight line. The shaft member 5 has a first tenon portion 51, a guide portion 52, a first shaft portion 53, a second shaft portion 54, and a second tenon portion 55. The first tenon portion 51, the guide portion 52, the first shaft portion 53, the second shaft portion 54, and the second tenon portion 55 are arranged in the axial direction in this order from the bottom. These portions are integrally formed.

[0012] The material of the shaft member 5 is carbon steel, which has excellent rigidity and heat resistance and is also easy to process, such as by cutting or grinding. However, the material of the shaft member 5 is not particularly limited, and other than carbon steel, for example, tantalum (Ta), tungsten (W), etc. may be used.

[0013] 1, the first tenon portion 51 is located at the lower end of the shaft member 5, and the second tenon portion 55 is located at the upper end of the shaft member 5. The first tenon portion 51 and the second tenon portion 55 are each rod-shaped and function as an axis when the shaft member 5 rotates. The shaft member 5 is supported by the main plate W at the first tenon portion 51 and the second tenon portion 55 so as to be rotatable around the central axis J.

[0014] As shown in Figs. 1 and 2, the second shaft portion 54 has a larger diameter than the first shaft portion 53. In other words, the diameter of the second shaft portion 54 is larger than the diameter of the first shaft portion 53. Therefore, a seat surface 59 is formed at the connection portion between the first shaft portion 53 and the second shaft portion 54. The seat surface 59 is a surface perpendicular to the central axis J of the shaft member 5. Note that the "large diameter" is not limited to a circular shape, but also includes a case where at least a part of the outer diameter shape of the second shaft portion 54 is larger than the outer diameter shape of the first shaft portion 53.

[0015] 1, a first spacer 91, a rotary plate 2, and a second spacer 92 are held on the first shaft portion 53. The configuration of this portion will be described in detail later.

[0016] As shown in Figs. 1 and 2, the guide portion 52 is located between the first shaft portion 53 and the first tenon portion 51. The guide portion 52 has a function of guiding the first spacer 91, the rotating plate 2, and the second spacer 92 to the first shaft portion 53. Such a guide portion 52 has a tapered shape that reduces in diameter from the first shaft portion 53 toward the first tenon portion 51. The outer diameter of the end of the guide portion 52 on the first shaft portion 53 side is equal to the outer diameter of the first shaft portion 53, and the outer diameter of the end of the guide portion 52 on the first tenon portion 51 side is larger than the outer diameter of the first tenon portion 51.

[0017] As shown in Figs. 1 and 2, the shaft member 5 has a plurality of grooves 58 formed in communication with the first shaft portion 53 and the guide portion 52. Each groove 58 is formed straight along the central axis J of the shaft member 5. The bottom of each groove 58 is rounded in an arc shape. In this embodiment, seven grooves 58 are formed at equal angular intervals in the circumferential direction of the shaft member 5. However, the number of grooves 58 is not particularly limited.

[0018] Such a shaft member 5 is made of a conductive material, particularly a metal material such as copper or aluminum. Since the shaft member 5 is conductive in this way, it can be used as a part of a conductor for electrically drawing out the electret film 6 to a terminal T, which will be described later, disposed on the first seat 31. Therefore, the electret film 6 can be easily electrically drawn out. Furthermore, by making the shaft member 5 out of a metal material, it is possible to form a shaft member 5 having higher strength. However, the material of the shaft member 5 is not particularly limited, and may be a conductive material other than a metal material, or may be an insulating material.

[0019] 1, a weight M for rotating the rotating plate 2 around the central axis J is connected to the shaft member 5 as described above. The weight M is disposed eccentrically with respect to the central axis J. Therefore, when the central axis J is inclined with respect to the vertical direction, the weight M moves vertically downward due to its own weight, and the shaft member 5 rotates around the central axis J accordingly.

[0020] <Rotating plate 2> As shown in FIG. 3, the rotating plate 2 is disk-shaped and has a uniform thickness over the entire surface. Such a rotating plate 2 is formed from a silicon substrate, particularly a single crystal silicon substrate. By forming the rotating plate 2 from a silicon substrate in this way, a rotating plate 2 having high flatness with little warping or bending can be obtained. Therefore, it is possible to reduce the gaps G1 and G2 between the first and second pedestals 31 and 32 and the rotating plate 2 while suppressing contact between the first and second pedestals 31 and 32 and the rotating plate 2. Therefore, it is possible to improve the power generation efficiency of the power generation device 1.

[0021] However, the rotating plate 2 may be any substrate as long as it includes a silicon substrate, and may be, for example, a composite substrate in which other substrates or layers are laminated on the silicon substrate, etc. A representative example of such a substrate is a silicon on insulator (SOI) substrate.

[0022] As shown in Fig. 3, the rotating plate 2 has an insertion hole 20 in the center into which the shaft member 5 is inserted, and a rim portion 21 is formed around the insertion hole 20. The rim portion 21 has four through holes 211 arranged in the circumferential direction. However, the number of through holes 211 is not particularly limited. Although Fig. 3 is a plan view, the rotating plate 2 and the electret film 6 are colored using hatching for ease of explanation.

[0023] The rotating plate 2 also has a holding portion 22 located at its center and protruding into the insertion hole 20. The holding portion 22 engages with the shaft member 5, thereby fixing the rotating plate 2 to the shaft member 5. The rim portion 21 and the holding portion 22 are integrally formed from a silicon substrate by patterning using etching.

[0024] As shown in FIG. 4, the holding portion 22 has a plurality of first beam portions 23 arranged radially and a plurality of second beam portions 24 arranged radially. The plurality of first beam portions 23 protrude from the rim portion 21 into the insertion hole 20. Then, one second beam portion 24 is arranged between each pair of adjacent first beam portions 23. Specifically, each second beam portion 24 protrudes from the middle of the first beam portion 23 so as to branch in an L-shape. In this embodiment, seven first beam portions 23 are arranged at equal angular intervals in the circumferential direction of the rim portion 21 in accordance with the number of grooves 58, and a total of seven second beam portions 24 protrude from each first beam portion 23, one by one.

[0025] However, the number of the first beam portions 23 and the second beam portions 24 is not particularly limited, and may be 6 or less, or 8 or more. The number of the first beam portions 23 and the number of the second beam portions 24 may be different. That is, there may be a first beam portion 23 from which the second beam portions 24 are not branched, and conversely, there may be a first beam portion 23 from which multiple second beam portions 24 are branched.

[0026] Each of the first beam portions 23 extends straight toward the shaft member 5 along the radial direction of the rotating plate 2. Each of the first beam portions 23 is tapered so that the width gradually decreases toward the tip, and the tip portion is rounded while slightly expanding in width. The diameter of a circle inscribed at the tips of the seven first beam portions 23 is designed to be smaller than the outer diameter of the first shaft portion 53.

[0027] On the other hand, each second beam portion 24 has a pressing portion 241 and a plurality of spring portions 242 that connect the pressing portion 241 and the first beam portion 23. The pressing portion 241 extends straight toward the shaft member 5 along the radial direction of the rotating plate 2, and the tip portion is rounded in a circular shape. The diameter of a circle inscribed at the tip of each of the seven pressing portions 241 is designed to be slightly smaller than the outer diameter of the first shaft portion 53. The base end portion of the pressing portion 241 is connected to the first beam portion 23 via the plurality of spring portions 242. The plurality of spring portions 242 are arranged in a line in the radial direction of the rotating plate 2, and extend straight generally along the circumferential direction of the rotating plate 2. Each spring portion 242 is a leaf spring, and urges the pressing portion 241 toward the shaft member 5 by elastically deforming in the radial direction of the rotating plate 2.

[0028] As shown in FIG. 5, when the shaft member 5 is inserted, the tip of each first beam portion 23 is disposed in a groove 58 formed in the first shaft portion 53. The groove 58 is recessed further than the first beam portion 23, so that the tip of the first beam portion 23 is unlikely to come into contact with the groove 58, and excessive stress is unlikely to be applied to the first beam portion 23. In contrast, the tip of each pressing portion 241 abuts against the outer circumferential surface of the first shaft portion 53. As described above, the diameter of the circle inscribed at the tips of the seven pressing portions 241 is slightly smaller than the outer diameter of the first shaft portion 53, so that when the first shaft portion 53 is inserted into the insertion hole 20, the spring portion 242 of each second beam portion 24 is elastically deformed, and the pressing portion 241 is urged toward the tip side by the restoring force. Then, the urged pressing portion 241 presses the first shaft portion 53. As a result, the rotating plate 2 is connected to the shaft member 5.

[0029] Since the seven second beams 24 uniformly press the first shaft portion 53 from its periphery, the rotating plate 2 is held concentrically with the shaft member 5 and in a stable position. Furthermore, although the rotating plate 2 formed from a silicon substrate is brittle and easily broken, the seven second beams 24 bear the pressing force in a distributed manner, so that the breaking of the holding portion 22 can be effectively prevented.

[0030] <Electret film 6> 3, a plurality of electret films 6 are symmetrically arranged on each of the upper and lower surfaces of the rim portion 21 of the rotating plate 2. Specifically, the electret films 6 are arranged between a pair of adjacent through holes 211, and the through holes 211 and the electret films 6 are arranged alternately.

[0031] The electret film 6 is a film that holds a negative charge. The configuration of the electret film 6 is not particularly limited, but for example, the electret film 6 may be configured to be a silicon oxide film formed by thermally oxidizing the surface of the rotating plate 2 and then electrically charged. In addition, for example, the electret film 6 may be configured to be a silicon oxide film formed on the surface of the rotating plate 2 using a gas phase method such as plasma CVD and then electrically charged. According to such a method, the electret film 6 can be formed by utilizing the characteristics of the silicon substrate, so that the electret film 6 can be easily formed.

[0032] As in this embodiment, by disposing the electret films 6 on both the upper and lower surfaces of the rim portion 21, it is possible to effectively suppress warping and bending of the rotating plate 2 and effectively suppress a decrease in the flatness of the rotating plate 2. Therefore, it is possible to reduce the gaps G1, G2 between the first and second seats 31, 32 and the rotating plate 2 while suppressing contact between the first and second seats 31, 32 and the rotating plate 2, and to improve the power generation efficiency of the power generation device 1.

[0033] <First Spacer 91> As shown in FIG. 6, the first spacer 91 is disposed between the rotating plate 2 and the first seat 31. The first spacer 91 has a function of managing a gap G1 between the rotating plate 2 and the first seat 31. The first spacer 91 is cylindrical, and an insertion hole 910 for inserting the shaft member 5 is formed in the center thereof. The first spacer 91 has a larger diameter than the second shaft portion 54. That is, the outer diameter of the first spacer 91 is larger than the outer diameter of the second shaft portion 54. Note that the "large diameter" does not mean that the first spacer 91 is limited to a circular shape, but includes a case where at least a part of the outer diameter shape of the first spacer 91 is larger than the outer diameter shape of the second shaft portion 54.

[0034] The insertion hole 910 has a larger diameter than the first shaft portion 53 and a smaller diameter than the second shaft portion 54. Therefore, when the shaft member 5 is inserted into the insertion hole 910 from the first tenon portion 51 side, the seat surface 59 abuts against the upper surface 91a of the first spacer 91, and further insertion is restricted. This positions the first spacer 91 with respect to the shaft member 5. Also, a ring-shaped recess 911 surrounding the insertion hole 910 is formed on the lower surface 91b of the first spacer 91. The first spacer 91 contacts the upper surface 2a of the rotating plate 2, more specifically, the upper surface of the holding portion 22, at each of the inner and outer peripheral portions of the recess 911 of the lower surface 91b.

[0035] The material of the first spacer 91 is not particularly limited, but may be, for example, copper, copper alloy, aluminum, aluminum alloy, iron alloy, titanium alloy, etc. Among these, however, it is preferable to use iron alloy, titanium alloy, etc. This allows the first spacer 91 to be formed with high hardness and low deformation.

[0036] <Second Spacer 92> As shown in FIG. 6, the second spacer 92 is disposed between the rotating plate 2 and the second seat 32. The second spacer 92 has a function of managing the gap G2 between the rotating plate 2 and the second seat 32, and a function of fixing the rotating plate 2 to the shaft member 5. The second spacer 92 is cylindrical, and an insertion hole 920 for inserting the shaft member 5 is formed in the center thereof. The second spacer 92 has a larger diameter than the second shaft portion 54, and is approximately equal to the outer diameter of the first spacer 91. Note that the "large diameter" does not mean that the second spacer 92 is limited to a circular shape, but includes a case where at least a part of the outer diameter shape of the second spacer 92 is larger than the outer diameter shape of the second shaft portion 54.

[0037] The insertion hole 920 has a diameter slightly smaller than that of the first shaft portion 53. Therefore, the second spacer 92 is fixed to the first shaft portion 53 by an interference fit. An annular recess 921 surrounding the insertion hole 920 is formed in the upper surface 92a of the second spacer 92. The second spacer 92 contacts the lower surface 2b of the rotating plate 2, more specifically, the lower surface of the holding portion 22, at each of the inner and outer peripheral portions of the recess 921 of the upper surface 92a.

[0038] By pressing the rotating plate 2 toward the first spacer 91 from below using such a second spacer 92, the rotating plate 2 is sandwiched between the first spacer 91 and the second spacer 92. As a result, the rotating plate 2 is firmly fixed to the shaft member 5. As described above, since the outer diameters of the first and second spacers 91 and 92 are larger than the outer diameter of the second shaft portion 54, the rotating plate 2 can be held at a position farther away from the central axis J of the shaft member 5. Therefore, the inclination θ of the rotating plate 2 with respect to the central axis J of the shaft member 5 can be made closer to a right angle. The closer the inclination θ is to a right angle, the smaller the axial wobble of the rotating plate 2 when the shaft member 5 rotates. Therefore, while suppressing contact between the first and second seats 31 and 32 and the rotating plate 2, the gaps G1 and G2 between the first and second seats 31 and 32 and the rotating plate 2 can be made smaller, and the power generation efficiency of the power generation device 1 can be improved.

[0039] In particular, as described above, by forming the recess 911 on the lower surface 91b of the first spacer 91, a portion closer to the outer edge of the lower surface 91b of the first spacer 91, i.e., a portion on the outer periphery side of the recess 911, can be more reliably brought into contact with the lower surface 2b of the rotating plate 2 without being affected by the flatness of the lower surface 91b. Similarly, by forming the recess 921 on the upper surface 92a of the second spacer 92, a portion closer to the outer edge of the upper surface 92a of the second spacer 92, i.e., a portion on the outer periphery side of the recess 921, can be more reliably brought into contact with the upper surface 2a of the rotating plate 2 without being affected by the flatness of the upper surface 92a. Therefore, the above-mentioned effect becomes more prominent. Furthermore, by fixing the second spacer 92 to the first shaft portion 53 by interference fit, the second spacer 92 can be fixed to the first shaft portion 53 without using a separate member such as an adhesive. Therefore, foreign matter is less likely to be interposed between the first and second spacers 91 and 92 and the rotating plate 2, and the above-mentioned effect becomes more prominent.

[0040] Furthermore, as described above, since the first spacer 91 and the second spacer 92 sandwich the holding portion 22 of the rotating plate 2, the holding portion 22 is reinforced from both the top and bottom by the first spacer 91 and the second spacer 92. This improves the mechanical strength of the holding portion 22, and effectively prevents damage to the holding portion 22. This effectively increases the mechanical strength of the power generation device 1.

[0041] The material of the second spacer 92 is not particularly limited, and may be, for example, copper, a copper alloy, aluminum, an aluminum alloy, an iron alloy, a titanium alloy, etc. However, among these, it is preferable to use copper, a copper alloy, aluminum, an aluminum alloy, etc. This makes the second spacer 92 easily deformable while having sufficient strength, which makes it easy to fix by a tight fit.

[0042] The configuration of the second spacer 92 is not particularly limited. For example, a C-shaped snap ring may be used instead of an annular shape. Even with such a configuration, the second spacer 92 can be fixed to the first shaft portion 53 without using adhesive.

[0043] <First Pedestal 31> 6, the first pedestal 31 is disposed opposite the upper side of the rotating plate 2 with a gap G1 therebetween.

[0044] The first pedestal 31 is a disk plate with a uniform thickness over the entire surface. The first pedestal 31 is made of an insulating material such as a resin material, a glass material, or a ceramic material. This makes it possible to easily insulate the first electrode 71 supported by the first pedestal 31 from the shaft member 5. This makes it possible to suppress a short circuit between the first electrode 71 and the electret film 6. However, the material of the first pedestal 31 is not particularly limited.

[0045] The first base 31 has an insertion hole 310 in the center into which the shaft member 5 is inserted, and a rim portion 311 is formed around the insertion hole 310. On the lower surface of the rim portion 311, i.e., the surface on the rotating plate 2 side, first electrodes 71 are arranged in a circumferential direction and have the same number and shape as the electret film 6. As shown in FIG. 1, these first electrodes 71 are led out to the outside of the power generating device 1 by wiring L1.

[0046] 6, the lower surface 31b of the first pedestal 31 is in contact with the upper surface 91a of the first spacer 91. This prevents a gap from occurring between the first pedestal 31 and the first spacer 91, and prevents the presence of another member between them, making it possible to easily and accurately manage the gap G1. Furthermore, the posture of the first pedestal 31 is stabilized, and the inclination θ1 of the first pedestal 31 with respect to the central axis J of the shaft member 5 can be brought closer to a right angle. As the inclination θ1 comes closer to a right angle, the gap G1 with the rotating plate 2 can be reduced while suppressing contact with the rotating plate 2, thereby improving the power generation efficiency of the power generation device 1.

[0047] Since the first spacer 91 is fixed to the shaft member 5 by the second spacer 92, it slides against the lower surface 31b of the first pedestal 31 as the shaft member 5 rotates. For this reason, it is preferable to perform a treatment for reducing frictional resistance and increasing slidability, such as a fluororesin coating, on at least one of the upper surface 91a of the first spacer 91 and the lower surface 31b of the first pedestal 31. This allows the rotating plate 2 to rotate with a smaller torque.

[0048] Furthermore, a terminal T is disposed on the upper surface 31a of the first base 31. This terminal T is connected to the shaft member 5 via a contact member 8 such as a brush. This electrically connects the terminal T and the electret film 6. This configuration is possible by forming the shaft member 5 from a conductive material, and this makes it easy to electrically extract the electret film 6.

[0049] <Second Pedestal 32> 6, the second pedestal 32 is disposed below the rotating plate 2, facing the rotating plate 2 with a gap G2 therebetween. That is, the second pedestal 32 is disposed so as to sandwich the rotating plate 2 between itself and the first pedestal 31. The second pedestal 32 has a function of supporting the second electrode 72. In addition, the power generating device 1 is attached to an object by fixing the second pedestal 32 to a base plate W.

[0050] The second seat 32 has the same structure as the first seat 31. That is, the second seat 32 is a disk plate, and the thickness is uniform over the entire surface. The second seat 32 is made of an insulating material, such as a resin material, a glass material, or a ceramic material. This makes it possible to easily insulate the second electrode 72 supported by the second seat 32 from the shaft member 5. Therefore, it is possible to suppress a short circuit between the second electrode 72 and the electret film 6. However, the material of the second seat 32 is not particularly limited.

[0051] The second seat 32 has an insertion hole 320 in the center into which the shaft member 5 is inserted, and a rim portion 321 is formed around the insertion hole 320. Second electrodes 72 are arranged in the circumferential direction on the upper surface of the rim portion 321, i.e., on the surface on the rotating plate 2 side, and are the same number and shape as the electret films 6. As shown in FIG. 1, these second electrodes 72 are led out to the outside of the power generating device 1 by wiring L2.

[0052] 6, the upper surface 32a of the second seat 32 is in contact with the lower surface 92b of the second spacer 92. This prevents a gap from occurring between the second seat 32 and the second spacer 92 and prevents another member from being interposed between them, making it possible to easily and accurately manage the gap G1. Furthermore, the posture of the second seat 32 is stabilized, and the inclination θ2 of the second seat 32 with respect to the central axis J of the shaft member 5 can be brought closer to a right angle. As the inclination θ2 comes closer to a right angle, the gap G2 with the rotating plate 2 can be reduced while suppressing contact with the rotating plate 2, thereby improving the power generation efficiency of the power generation device 1.

[0053] Since the second spacer 92 is fixed to the shaft member 5, the second spacer 92 slides against the upper surface 32a of the second seat 32 as the shaft member 5 rotates. For this reason, it is preferable to perform a treatment for reducing frictional resistance and increasing slidability, such as a fluororesin coating, on at least one of the lower surface 92b of the second spacer 92 and the upper surface 32a of the second seat 32. This allows the rotating plate 2 to rotate with a smaller torque.

[0054] <Side wall portion 33> As shown in Fig. 1, the side wall portion 33 is cylindrical and disposed so as to surround the periphery of the rotating plate 2. The side wall portion 33 is connected at its upper end to the first seat 31 and at its lower end to the second seat 32. This allows the first seat 31 and the second seat 32 to be fixed via the side wall portion 33, suppressing their relative displacement. The first seat 31, the second seat 32, and the side wall portion 33 are integrated to form the package 3 that houses the rotating plate 2, thereby protecting the rotating plate 2.

[0055] The power generating device 1 has been described above. As described above, the power generating device 1 includes the shaft member 5, the rotating plate 2 including a silicon substrate in which the insertion hole 20 into which the shaft member 5 is inserted is formed, the first seat 31 arranged opposite the rotating plate 2, the electret film 6 arranged on one of the rotating plate 2 and the first seat 31 so as to face the other, and the first electrode 71 arranged on the other of the rotating plate 2 and the first seat 31 so as to face the electret film 6. The shaft member 5 has a groove 58 formed to extend in the axial direction, and the rotating plate 2 has a plurality of first beam portions 23 extending from the outer edge of the insertion hole 20 into the insertion hole 20 and having their tip portions arranged in the groove 58, and a second beam portion 24 arranged between the plurality of first beam portions 23 and pressing the shaft member 5 at its tip portion. The rotating plate 2 including the silicon substrate is brittle and easily broken, but the pressing force is received by the multiple second beam portions 24 in a distributed manner, so that the breakage of the holding portion 22 can be effectively suppressed. This makes it possible to form the rotating plate 2 from a silicon substrate. Furthermore, by forming the rotating plate 2 from a silicon substrate, the rotating plate 2 has high flatness with little warping or bending. Therefore, the gap G1 between the first pedestal 31 and the rotating plate 2 can be made smaller while suppressing contact between the first pedestal 31 and the rotating plate 2, and the power generation efficiency of the power generation device 1 can be improved.

[0056] As described above, the power generating device 1 has the first spacer 91 into which the shaft member 5 is inserted and which is located between the rotating plate 2 and the first seat 31. This makes it easy to manage the gap G1 between the rotating plate 2 and the first seat 31.

[0057] As described above, the first spacer 91 has a larger diameter than the shaft member 5, and the lower surface 91b, which is the surface of the first spacer 91 facing the rotating plate 2, is in contact with the rotating plate 2. With this configuration, the rotating plate 2 can be held at a position farther away from the central axis J of the shaft member 5. Therefore, the inclination θ of the rotating plate 2 with respect to the central axis J of the shaft member 5 can be made closer to a right angle. The closer the inclination θ is to a right angle, the smaller the wobble of the rotating plate 2 when the shaft member 5 rotates. Therefore, the gap G1 between the first seat 31 and the rotating plate 2 can be made smaller while suppressing contact between the first seat 31 and the rotating plate 2, and the power generation efficiency of the power generation device 1 can be improved.

[0058] As described above, the shaft member 5 has the first shaft portion 53, the second shaft portion 54 having a diameter larger than that of the first shaft portion 53, and a seating surface 59 formed between the first shaft portion 53 and the second shaft portion 54, and the first shaft portion 53 is inserted into the first spacer 91. The first spacer 91 abuts against the seating surface 59. The power generating device 1 also has a second spacer 92 fixed to the first shaft portion 53 so as to sandwich the rotating plate 2 between the first spacer 91 and the second spacer 92. With this simple configuration, the rotating plate 2 can be fixed to the shaft member 5 with the lower surface 91b of the first spacer 91 in contact with the rotating plate 2.

[0059] As described above, the electret film 6 is disposed on the rotating plate 2, and the first electrode 71 is disposed on the first pedestal 31. With this configuration, the electret film 6 can be formed by taking advantage of the characteristics of the silicon substrate, making it easy to form the electret film 6.

[0060] As described above, the power generating device 1 has the second seat 32 arranged opposite the rotating plate 2 with the rotating plate 2 sandwiched between the first seat 31 and the second seat 32, and the second electrode 72 arranged on the second seat 32 opposite the rotating plate 2. The electret film 6 is arranged on both sides of the rotating plate 2 opposite the first electrode 71 and the second electrode 72. This can increase the amount of power generated by the power generating device 1.

[0061] As described above, the power generating device 1 has the second spacer 92 into which the shaft member 5 is inserted and which is located between the rotating plate 2 and the second seat 32. This makes it easy to manage the gap G2 between the rotating plate 2 and the second seat 32.

[0062] As described above, the second spacer 92 has a larger diameter than the shaft member 5, and the upper surface 92a of the second spacer 92, which is the surface on the rotating plate 2 side, is in contact with the rotating plate 2. With this configuration, the rotating plate 2 can be held at a position farther away from the central axis J of the shaft member 5. Therefore, the inclination θ of the rotating plate 2 with respect to the central axis J of the shaft member 5 can be made closer to a right angle. The closer the inclination θ is to a right angle, the smaller the wobble of the rotating plate 2 when the shaft member 5 rotates. Therefore, the gap G2 between the second seat 32 and the rotating plate 2 can be made smaller while suppressing contact between the second seat 32 and the rotating plate 2, and the power generation efficiency of the power generation device 1 can be improved.

[0063] As described above, the shaft member 5 has electrical conductivity, which makes it easy to electrically extract the electret film 6.

[0064] <Second embodiment> Fig. 7 is a cross-sectional view showing a power generating device according to a second embodiment of the present invention, Fig. 8 is a perspective view of a shaft member of the power generating device shown in Fig. 7.

[0065] This embodiment is similar to the first embodiment described above, except that the configuration of the shaft member is different. In the following description, the present embodiment will be described focusing on the differences from the first embodiment described above, and the description of the similarities will be omitted. In each drawing of this embodiment, the same reference numerals are used for the same configurations as the above-mentioned embodiment.

[0066] As shown in FIG. 7 and FIG. 8, the shaft member 5 of this embodiment has a recess 531 formed in the first shaft portion 53. The recess 531 is formed in the upper end portion of the first shaft portion 53 and has a ring shape along the circumferential direction. Since the depth of the recess 531 is shallower than the groove 58, the recess 531 and the groove 58 are arranged alternately along the circumferential direction of the first shaft portion 53. The tip end of the second beam portion 24 of the rotating plate 2 is fitted into this recess 531. As in the first embodiment described above, in the fitted state, the spring portion 242 is elastically deformed, and the pressing portion 241 presses the first shaft portion 53 by the restoring force. As a result, the rotating plate 2 is fixed to the shaft member 5.

[0067] The recess 531 has a tapered portion 531a at its lower end, which has a slope that slopes downward. The tip of the pressing portion 241 contacts the tapered portion 531a. Therefore, the biasing force of the spring portion 242 is dispersed into the force of the pressing portion 241 pressing the shaft member 5 and the force of the pressing portion 241 biasing the rotating plate 2 upward, and the rotating plate 2 is pressed against the seating surface 59. As a result, the upper surface 2a of the rotating plate 2 contacts the seating surface 59 strongly, and the inclination θ of the rotating plate 2 with respect to the central axis J of the shaft member 5 can be made close to a right angle.

[0068] Further, the second shaft portion 54 of the shaft member 5 is inserted into the first spacer 91. The first spacer 91 has an insertion hole 910 larger than the outer diameter of the second shaft portion 54, and is not fixed to the shaft member 5. Further, the first spacer 91 is merely in contact with both the rotating plate 2 and the first pedestal 31 and is not fixed thereto. Therefore, the first spacer 91 slides with at least one of the rotating plate 2 and the first pedestal 31 as the rotating plate 2 rotates.

[0069] On the other hand, the first shaft portion 53 of the shaft member 5 is inserted into the second spacer 92. The second spacer 92 has an insertion hole 920 larger than the outer diameter of the first shaft portion 53, and is not fixed to the shaft member 5. In addition, the second spacer 92 is merely in contact with both the rotating plate 2 and the second pedestal 32 and is not fixed thereto. Therefore, the second spacer 92 slides with at least one of the rotating plate 2 and the second pedestal 32 as the rotating plate 2 rotates.

[0070] However, without being limited thereto, for example, the first spacer 91 may be fixed to at least one of the shaft member 5 and the rotating plate 2, or may be fixed to the first pedestal 31. Similarly, the second spacer 92 may be fixed to at least one of the shaft member 5 and the rotating plate 2, or may be fixed to the second pedestal 32.

[0071] The second embodiment as described above can also achieve the same effects as the first embodiment.

[0072] Although the power generating device of the present invention has been described above based on the illustrated embodiment, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having a similar function. In addition, any other configuration may be added to the present invention. [Explanation of symbols]

[0073] 1...power generating device, 2...rotating plate, 2a...upper surface, 2b...lower surface, 20...insertion hole, 21...rim portion, 211...through hole, 22...retaining portion, 23...first beam portion, 24...second beam portion, 241...pressure portion, 242...spring portion, 3...package, 31...first base, 31a...upper surface, 31b...lower surface, 310...insertion hole, 311...rim portion, 32...second base, 32a...upper surface, 320...insertion hole, 321...rim portion, 33...side wall portion, 5...shaft member, 51...first tenon portion, 52...guide portion, 53...first shaft portion, 531...recess, 531a ...Tapered portion, 54...Second shaft portion, 55...Second tenon portion, 58...Groove, 59...Seat surface, 71...First electrode, 72...Second electrode, 6...Electret film, 8...Contact member, 91...First spacer, 91a...Upper surface, 91b...Lower surface, 910...Insertion hole, 911...Recess, 92...Second spacer, 92a...Upper surface, 92b...Lower surface, 920...Insertion hole, 921...Recess, G1...Gap, G2...Gap, J...Central axis, L1...Wiring, L2...Wiring, M...Spindle, T...Terminal, W...Base plate, θ...Tilt, θ1...Tilt, θ2...Tilt

Claims

1. A shaft member; a rotating plate including a silicon substrate having an insertion hole into which the shaft member is inserted; A first base is disposed opposite the rotating plate; an electret film disposed on one of the rotating plate and the first base so as to face the other; a first electrode disposed on the other of the rotating plate and the first base so as to face the electret film; The shaft member has a groove formed extending in the axial direction, The rotating plate is characterized in having a plurality of first beam portions extending from the outer edge of the insertion hole into the insertion hole and having their tips positioned within the groove, and a second beam portion positioned between the plurality of first beam portions and pressing the shaft member at its tip.

2. The power generating device according to claim 1 , further comprising a first spacer into which the shaft member is inserted and which is positioned between the rotating plate and the first base.

3. The first spacer has a larger diameter than the shaft member, The power generating device according to claim 2 , wherein a surface of the first spacer facing the rotating plate is in contact with the rotating plate.

4. The shaft member has a first shaft portion, a second shaft portion having a diameter larger than that of the first shaft portion, and a seat surface formed between the first shaft portion and the second shaft portion, and the first shaft portion is inserted into the first spacer, The first spacer abuts against the seat surface, 4. The power generating device according to claim 2, further comprising a second spacer fixed to the first shaft portion so as to sandwich the rotating plate between the first spacer and the second spacer.

5. The electret film is disposed on the rotating plate, The power generating device according to claim 1 , wherein the first electrode is disposed on the first base.

6. a second seat disposed opposite the rotating plate so as to sandwich the rotating plate between the first seat and the second seat; a second electrode disposed on the second base so as to face the rotating plate; The power generating device according to claim 5 , wherein the electret films are disposed on both sides of the rotating plate so as to face the first electrode and the second electrode, respectively.

7. The power generating device according to claim 6 , further comprising a second spacer into which the shaft member is inserted and which is positioned between the rotating plate and the second seat.

8. The second spacer has a larger diameter than the shaft member, The power generating device according to claim 7 , wherein a surface of the second spacer facing the rotating plate is in contact with the rotating plate.

9. The power generating device according to claim 1 , wherein the shaft member is electrically conductive.

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