Dust cap, diaphragm, and electroacoustic transducer

Abstract

To provide a dust cap capable of extending the high-frequency reproduction range by dispersing the resonant frequency.SOLUTION: A dust cap 160 is a dust cap 160 that is placed at the center of a diaphragm 100 of an electroacoustic transducer. The first cross-sectional shape of the dust cap 160 by a first plane including a predetermined reference axis 300 along the vibration direction and the second cross-sectional shape of the dust cap 160 including reference axis 300 by a second plane crossing the first plane are different from each other.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a dust cap, a diaphragm on which the dust cap is disposed, and an electro-acoustic transducer including a diaphragm on which the dust cap is disposed. [Background technology]

[0002] Conventionally, for example, a dome-shaped dust cap may be placed in the center of a cone-shaped diaphragm. In such a rotating body, a dust cap whose cross-sectional shape on a plane including a reference axis that passes through the center of the diaphragm and extends along the vibration direction of the diaphragm is uniform in the circumferential direction will cause single resonance, narrowing the reproduction band. Therefore, Patent Documents 1-3 describe dust caps whose cross-sectional shape on a plane including the reference axis is not uniform in the circumferential direction. By adopting such a dust cap, single resonance is suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 188370 [Patent Document 2] Japanese Patent Application Publication No. 3-038998 [Patent Document 3] JP 2001-224095 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the shape of the dust cap needs improvement.

[0005] The present disclosure provides a dust cap with an improved shape, a diaphragm on which the dust cap with an improved shape is disposed, and an electro-acoustic transducer including the diaphragm. [Means for solving the problem]

[0006] One dust cap disclosed herein is a dust cap that is placed in the center of a diaphragm of an electro-acoustic transducer, and has a first cross-sectional shape defined by a first surface that includes a predetermined reference axis along the vibration direction, and a second cross-sectional shape defined by a second surface that includes the reference axis and intersects the first surface, which is different from a first cross-sectional shape defined by a second surface that includes the reference axis and intersects the first surface.

[0007] A diaphragm according to one aspect of the present disclosure is a diaphragm provided in an electro-acoustic transducer, the diaphragm having at least a neck portion surrounding a predetermined reference axis along a vibration direction, and a first portion, a second portion, and a third portion arranged around the reference axis outside the neck portion and having mutually different cross-sectional shapes taken along a plane including the reference axis, the cross-sectional shape of the first portion being an arc with a first radius of curvature, the cross-sectional shape of the second portion being an arc with a second radius of curvature different from the first radius of curvature, and the cross-sectional shape of the third portion being a part of an ellipse, the cross-sectional shapes of the neck portion taken along all planes including the reference axis being the same curve, and a dust cap is disposed in a central portion, the first cross-sectional shape of the dust cap taken along a first plane including the reference axis being different from the second cross-sectional shape of the dust cap taken along a second plane including the reference axis and intersecting the first plane.

[0008] An electro-acoustic transducer according to the present disclosure comprises a dust cap having a first cross-sectional shape defined by a first surface including a predetermined reference axis along a vibration direction and a second cross-sectional shape defined by a second surface including the reference axis and intersecting the first surface, the dust cap having a different first cross-sectional shape, a diaphragm, a magnetic circuit, a frame that holds the magnetic circuit and the diaphragm, and a voice coil connected to the diaphragm and positioned in a magnetic gap provided by the magnetic circuit. Effect of the Invention

[0009] According to the present disclosure, a wide reproduction band can be achieved by avoiding single resonance caused by the dust cap. Also, by making the shape relatively simple, disturbance of the directional characteristics can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a plan view showing the diaphragm from the front with the edge attached. [Diagram 2] 2 is a cross-sectional view showing the diaphragm and an edge taken along line AA in FIG. 1. [Diagram 3] 2 is a cross-sectional view showing the diaphragm and an edge taken along line BB in FIG. [Figure 4] FIG. 2 is a plan view showing the dust cap from the front. [Diagram 5] 5 is a cross-sectional view showing the dust cap taken along line CC in FIG. 4. [Figure 6] 5 is a cross-sectional view showing the dust cap taken along line DD in FIG. 4. [Figure 7] 1 is a cross-sectional view of a speaker device, which is one type of electro-acoustic transducer equipped with a diaphragm. [Figure 8] 11 is a diagram showing a difference in sound pressure frequency characteristics between a speaker device having a diaphragm of a conventional shape and a speaker device having a diaphragm on which a dust cap of the present embodiment is arranged. FIG. [Figure 9] 1 is a cross-sectional view of an automobile, which is one example of a moving object to which a speaker device having a diaphragm is attached. [Figure 10] FIG. 1 is a diagram showing a mini component system, which is one type of electronic device to which a speaker device having a diaphragm is attached. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of a dust cap, a diaphragm, and an electroacoustic transducer according to the present disclosure will be described with reference to the drawings. Note that the following embodiment is an example for explaining the present disclosure, and is not intended to limit the present disclosure. For example, the shapes, structures, materials, components, relative positional relationships, connection states, numerical values, mathematical expressions, contents of each step in the method, and the order of each step shown in the following embodiment are examples, and may include contents not described below. In addition, geometric expressions such as parallel and orthogonal may be used, but these expressions do not indicate mathematical strictness, and include substantially acceptable errors, deviations, etc. In addition, expressions such as simultaneous and identical also include substantially acceptable ranges.

[0012] In addition, the drawings are schematic diagrams in which emphasis, omission, or ratio adjustment is appropriately performed to explain the present disclosure, and are different from the actual shapes, positional relationships, and ratios. In addition, the X-axis, Y-axis, and Z-axis that may be shown in the drawings indicate orthogonal coordinates that are arbitrarily set for the explanation of the drawings. In other words, the Z-axis is not necessarily an axis along the vertical direction, and the X-axis and Y-axis are not necessarily present in a horizontal plane.

[0013] In addition, in the following, a plurality of inventions may be collectively described as one embodiment. In addition, some of the contents described below are described as optional components related to the present disclosure.

[0014] Fig. 1 is a plan view showing the front of diaphragm 100 with edge 110 attached. Fig. 2 is a cross-sectional view showing diaphragm 100 and edge 110 taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view showing diaphragm 100 and edge 110 taken along line BB in Fig. 1.

[0015] The diaphragm 100 is a component included in an electroacoustic transducer such as a speaker device or a microphone, and is a component that vibrates itself to vibrate the air and generate sound, or vibrates itself based on the vibration of the air. The diaphragm 100 includes at least a first portion 111, a second portion 112, a third portion 113, and a neck portion 117, and in this embodiment, also includes a fourth portion 114.

[0016] The first portion 111, the second portion 112, the third portion 113, and the fourth portion 114 are arranged around a predetermined reference axis 300 (see FIGS. 2 and 3) along the vibration direction (the Z-axis direction in the drawings). The first portion 111, the second portion 112, and the third portion 113 are portions having mutually different cross-sectional shapes along a plane including the reference axis 300 (for example, a cross section along line AA and a cross section along line BB in FIG. 1). The third portion 113 and the fourth portion 114 have the same cross-sectional shape along a plane including the reference axis 300.

[0017] In the present embodiment, the shape of the diaphragm 100 in plan view, that is, when viewed from the direction of the reference axis 300, is a circle, and the shapes of the first portion 111, the second portion 112, the third portion 113, and the fourth portion 114 in plan view are the same as each other in a sector shape. The diameter of the diaphragm 100 in plan view is about 100 mm. The areas of the first portion 111, the second portion 112, the third portion 113, and the fourth portion 114 in plan view are also the same. Note that, since a connection portion 115 (described in detail later) is provided at each boundary between the first portion 111, the second portion 112, the third portion 113, and the fourth portion 114, the shapes of the first portion 111, the second portion 112, the third portion 113, and the fourth portion 114 in plan view are not perfect sector shapes.

[0018] The third portion 113 and the fourth portion 114 are disposed between the first portion 111 and the second portion 112. The first portion 111 and the second portion 112 are not adjacent to each other. The third portion 113 and the fourth portion 114 are not adjacent to each other.

[0019] 2, the shape of a cross section of the first portion 111 including the reference axis 300 is a single circular arc with a first radius of curvature R1. The cross-sectional shapes of the first portion 111 cut at any cross section including the reference axis 300 are mutually identical. In other words, the first portion 111 is a part of a body of revolution around the reference axis 300.

[0020] The shape of a cross section of the second portion 112 including the reference axis 300 is a single circular arc with a second radius of curvature R2. When the second portion 112 is cut at any cross section including the reference axis 300, the cross-sectional shape is the same. In other words, the second portion 112 is a part of a body of revolution about the reference axis 300. In the present embodiment, the first radius of curvature R1>the second radius of curvature R2. In the present embodiment, the first radius of curvature R1>=the second radius of curvature R2×1.5, and specifically, the first radius of curvature R1=300 mm, and the second radius of curvature R2=200 mm.

[0021] As shown in Fig. 3, the cross-sectional shapes of the third portion 113 and the fourth portion 114 are parts of an ellipse. In the case of this embodiment, the cross-sectional shapes of the third portion 113 and the fourth portion 114 are a quarter portion of an ellipse cut by the major axis and the minor axis, or a part of the quarter portion. When the third portion 113 and the fourth portion 114 are cut by any cross section including the reference axis 300, the cross-sectional shapes are the same. In other words, the third portion 113 and the fourth portion 114 are parts of a body of revolution about the reference axis 300.

[0022] Neck portion 117 is a portion of diaphragm 100 that is connected to the edges of first portion 111, second portion 112, and third portion 113 on the reference axis 300 side. In the present embodiment, neck portion 117 is connected to the edges of fourth portion 114 and connecting portion 115 on the reference axis 300 side. Neck portion 117 is a portion to which dust cap 160 (see FIG. 7) is attached. Neck portion 117 has the same curved cross-sectional shape in all planes including reference axis 300. Neck portion 117 is a rotating body with reference axis 300 as its central axis.

[0023] In this embodiment, the cross-sectional shape of the plane including the reference axis 300 of the neck portion 117 is a circular arc, and is smoothly connected to the first portion 111, the second portion 112, the third portion 113, the fourth portion 114, and the connecting portion 115. The radius of curvature of the neck portion 117 is 1 / 10 or less of the larger of the first radius of curvature R1 and the second radius of curvature R2. In this embodiment, the radius of curvature of the neck portion 117 is 1 / 10 or less of the smaller of the first radius of curvature R1 and the second radius of curvature R2. Specifically, the radius of curvature of the neck portion 117 is 20 mm or less.

[0024] Connection portion 115 is a portion that connects adjacent portions of diaphragm 100 having different cross-sectional shapes, and constitutes a part of diaphragm 100. In the case of the present embodiment, connection portion 115 smoothly connects between first portion 111 and third portion 113, between third portion 113 and second portion 112, between second portion 112 and fourth portion 114, and between fourth portion 114 and first portion 111.

[0025] In this embodiment, the boundary line between the first portion 111 and the third portion 113 of the connection portion 115, the boundary line between the third portion 113 and the second portion 112 of the connection portion 115, the boundary line between the second portion 112 and the fourth portion 114 of the connection portion 115, and the boundary line between the fourth portion 114 and the first portion 111 of the connection portion 115 are arranged parallel to each other when viewed in a plane.

[0026] Diaphragm 100 is formed by integrally forming first portion 111, second portion 112, third portion 113, fourth portion 114, connection portion 115, and neck portion 117. In a plan view, neck portion 117 of diaphragm 100 has a through hole 116 at the center thereof, which is connected to voice coil 131 (see FIG. 7). Through hole 116 is covered by dust cap 160 attached to neck portion 117.

[0027] The outer peripheral edge 118 of the diaphragm 100 in plan view is integrally connected to the second portion 112, the third portion 113, the fourth portion 114, and the connection portion 115. The outer peripheral edge 118 is a portion connected to the edge 110. The surface of the outer peripheral edge 118 connected to the edge 110 is in a truncated cone shape. The thickness of the outer peripheral edge 118 corresponding to the third portion 113 (similar to the fourth portion 114) is thicker than the thickness of the outer peripheral edge 118 corresponding to the first portion 111. The difference in thickness of the outer peripheral edge 118 corresponding to each portion is based on the difference in thickness protruding in the direction away from the edge 110. By making the surface of the outer peripheral edge 118 connected to the edge 110 in a truncated cone shape, a strong connection with the edge 110 is ensured, and the uneven shape of the outer peripheral edge 118 absorbs the difference in cross-sectional shape of each portion.

[0028] The material constituting the diaphragm 100 is not limited. For example, the diaphragm 100 may be formed by papermaking at least one of chemical fibers such as polyester fibers and pulp, or by injection molding of a resin kneaded with a reinforcing material. The diaphragm 100 may also be formed by press molding a sheet or film-like material.

[0029] Fig. 4 is a plan view showing the dust cap 160 from the front. Fig. 5 is a cross-sectional view showing the dust cap 160 taken along line CC in Fig. 4. Fig. 6 is a cross-sectional view showing the dust cap 160 taken along line DD in Fig. 4.

[0030] Dust cap 160 is disposed in front of the center of diaphragm 100 (Z+ side in the drawing), and is a film-like member that covers through-hole 116 provided in diaphragm 100. In the case of this embodiment, dust cap 160 has a circular shape in a plan view, that is, when viewed from the direction of reference axis 300, and bulges forward. The apex of dust cap 160 is on reference axis 300, and has a plane-symmetric shape with respect to a plane including reference axis 300. By making dust cap 160 a plane-symmetric shape, it is possible to avoid non-uniformity in the directional frequency characteristics.

[0031] Dust cap 160 is directly or indirectly connected to diaphragm 100. In the present embodiment, dust cap 160 is directly connected to the front side surface of neck portion 117 using an adhesive or the like. Note that dust cap 160 may be indirectly connected to diaphragm 100 by being connected to bobbin 132 (described in detail later) or the like that is connected to diaphragm 100.

[0032] The dust cap 160 has a first cross-sectional shape of the dust cap 160 by a first surface including a predetermined reference axis 300 along the vibration direction (Z-axis direction in the figure), and a second cross-sectional shape of the dust cap 160 by a second surface including the reference axis 300 and intersecting the first surface, which is different. In the case of this embodiment, the first cross section is the YZ plane in the figure, and the first cross-sectional shape is any two sides of a triangle. In addition, the first cross-sectional shape is two hypotenuses of an isosceles triangle. The second cross section is the XZ plane in the figure that is perpendicular to the first cross section, and the second cross-sectional shape is a curve. The curve is not limited to, but examples include an arc, a part of an ellipse, a hyperbola, a parabola, and the like. The shape of the dust cap 160 changes continuously in the circumferential direction centered on the reference axis 300 from the first cross-sectional shape to the second cross-sectional shape. The orthogonal cross-sectional shape of the dust cap 160 by an orthogonal plane (XY plane in the figure) perpendicular to the reference axis 300 is a curve, and the part that connects to the diaphragm 100 is a circle.

[0033] The material constituting the dust cap 160 is not limited. In addition, the material may be the same as or different from that of the diaphragm 100. For example, the dust cap 160 may be formed by papermaking at least one of chemical fibers such as polyester fibers and pulp, or may be formed by injection molding of a resin kneaded with a reinforcing material. In addition, the diaphragm 100 may be formed by press molding a sheet or film-like material.

[0034] Fig. 7 is a cross-sectional view of a speaker device 120, which is one of electroacoustic transducers including a diaphragm 100. As shown in Fig. 7, the speaker device 120 includes the diaphragm 100, a magnetic circuit 124, a frame that holds the magnetic circuit 124 and the diaphragm 100, and a voice coil 131 that is connected to the diaphragm 100 and disposed in a magnetic gap of the magnetic circuit 124.

[0035] In the case of the present embodiment, the magnetic circuit 124 included in the speaker device 120 is an internal magnet type magnetic circuit 124 formed by sandwiching a magnetized magnet 121 between an upper plate 122 and a yoke 123 .

[0036] Yoke 123 of magnetic circuit 124 is coupled to frame 126. An annular edge 110 that connects outer peripheral edge 118 of diaphragm 100 to frame 126 is adhered to peripheral edge 127 of frame 126. The center of diaphragm 100 is coupled to one end of voice coil body 129. The other end of voice coil body 129 is disposed so as to fit into magnetic gap 125 of magnetic circuit 124. Note that in the present embodiment, voice coil body 129 is exemplified as voice coil body 129 including voice coil 131 and bobbin 132 around which voice coil 131 is wound, but voice coil body 129 without bobbin 132 may be used.

[0037] Although the speaker device 120 having the internal magnet type magnetic circuit 124 has been described, the present invention is not limited to this, and the diaphragm 100 may be applied to the speaker device 120 having the external magnet type magnetic circuit 124 .

[0038] Fig. 8 is a diagram showing the difference in sound pressure frequency characteristics between a speaker device equipped with a diaphragm 100 of a conventional shape and a speaker device 120 equipped with a diaphragm 100 on which the dust cap 160 of the present embodiment is arranged. As shown in Fig. 8, the sound pressure frequency characteristics of the speaker device equipped with the conventional diaphragm 100 have a significant peak dip, for example, near 3 kHz and 4 kHz. On the other hand, the speaker device 120 equipped with the diaphragm 100 according to the embodiment can effectively realize resonance dispersion to suppress the peak dip, and can obtain flat acoustic characteristics especially near 3 kHz and 4 kHz.

[0039] According to the speaker device 120 of this embodiment, it is possible to obtain a speaker with flat sound pressure frequency characteristics in the mid-high range by effectively dispersing the resonance of the diaphragm 100. In addition, it is possible to extend the high-range limit frequency of the speaker, and it is possible to realize high-fidelity reproduction and high-clarity sound quality.

[0040] The present disclosure is not limited to the above-mentioned embodiment. For example, the present disclosure may be realized by combining the components described in this specification in any way, or by excluding some of the components. In addition, the present disclosure also includes modifications obtained by applying various modifications that a person skilled in the art can think of to the above-mentioned embodiment without departing from the gist of the present disclosure, that is, the meaning of the words described in the claims.

[0041] For example, the first cross-sectional shape is formed by two straight lines and the second surface shape is formed by a curved line in the above description of dust cap 160, but the first cross-sectional shape and the second surface shape may be formed by straight lines with different inclinations. Also, the first cross-sectional shape and the second surface shape may be formed by curves with different shapes.

[0042] In addition, although the embodiment has been described in which the cross-sectional shape of third portion 113 and the cross-sectional shape of fourth portion 114 of diaphragm 100 are the same, the cross-sectional shape of third portion 113 and the cross-sectional shape of fourth portion 114 may be different. In other words, fourth portion 114 does not have to be a part of an ellipse, and any shape can be adopted.

[0043] In addition, the annular edge 110 interposed between the diaphragm 100 and the frame may have a diaphragm 100 connection portion that conforms to the shape of the outer peripheral edge of the diaphragm 100, that is, a shape that conforms to the differences in the cross-sectional shapes of each part of the diaphragm 100.

[0044] Furthermore, the cross-sectional shape of neck portion 117 has been described as a circular arc, but the cross-sectional shape of neck portion 117 may be any curve, such as a part of an ellipse or a part of a hyperbola.

[0045] In addition, although the diaphragm 100 is divided into four equal parts at 90° intervals in a plan view, each part does not have to be equal. The diaphragm 100 may be divided into three parts with different cross-sectional shapes, or may be divided into five or more parts.

[0046] Moreover, the electroacoustic transducer including the diaphragm 100 on which the dust cap 160 is arranged may be provided in a moving object. FIG. 9 is a cross-sectional view of an automobile 140, which is one of the moving objects to which a speaker device 120 including the diaphragm 100 is attached. The automobile 140 includes the speaker device 120 including the diaphragm 100 on a rear tray, a front panel, a pillar, a door, etc. The speaker device 120 is used as a part of a car navigation system or a car audio system. The automobile 140 includes a driving means 141, and moves the speaker device 120 together with a vehicle body 142 that functions as a housing for accommodating the speaker device 120.

[0047] Moreover, the speaker device 120 including the diaphragm 100 on which the dust cap 160 is arranged may be provided in an electronic device as shown in Fig. 10. Fig. 10 is a diagram showing another example of use of the speaker device 120 including the diaphragm 100. An audio mini component system 150 will be exemplified and described as one of the electronic devices including the speaker device 120 including the diaphragm 100.

[0048] The mini component system 150 has two speaker devices 120 built in each of two enclosures 151. The mini component system 150 also includes an amplifier 152 including an amplifier circuit for an electric signal input to the speaker device 120, a tuner 153 for outputting a source input to the amplifier 152, and a CD player 154. The mini component system 150, which is an audio mini component system, amplifies a music signal input from the tuner 153 or the CD player 154 by the amplifier 152, and emits sound from the speaker device 120 based on the amplified signal. In addition to the mini component system 150, examples of electronic devices include an audio system for an automobile, a portable audio device, video equipment such as a liquid crystal television or an organic EL display television, information and communication equipment such as a mobile phone, and computer-related equipment.

[0049] The dust cap 160 of the first embodiment of the present disclosure is a dust cap 160 arranged in the center of a diaphragm 100 provided in an electro-acoustic transducer, and a first cross-sectional shape of the dust cap 160 defined by a first surface including a predetermined reference axis 300 along the vibration direction is different from a second cross-sectional shape of the dust cap 160 defined by a second surface including the reference axis 300 and intersecting the first surface.

[0050] According to the dust cap 160 of the first embodiment, it is possible to disperse the resonance frequency and expand the high-frequency reproduction band.

[0051] The second embodiment of the dust cap 160 includes the first embodiment, and the first cross-sectional shape is any two sides of a triangle.

[0052] A dust cap 160 of a third embodiment of the present disclosure includes a second embodiment, where the first cross-sectional shape is the two hypotenuses of an isosceles triangle.

[0053] According to the second and third aspects, the dust cap 160 can be manufactured easily.

[0054] The dust cap 160 of the fourth embodiment includes any of the first to third embodiments, and has a shape that changes continuously from the first cross-sectional shape to the second cross-sectional shape.

[0055] The dust cap 160 of the fifth embodiment includes any of the first to fourth embodiments, and the orthogonal cross-sectional shape taken along a plane orthogonal to the reference axis 300 is a curve.

[0056] According to the fourth and fifth aspects, it is possible to prevent dust cap 160 from having a peculiar shape, thereby improving sound quality.

[0057] The dust cap 160 of the sixth embodiment includes any one of the first to fifth embodiments, and is formed by papermaking a material including at least one of chemical fiber and pulp.

[0058] The dust cap 160 of the seventh embodiment includes any of the dust caps of the first to fifth embodiments, and is formed from injection-molded resin.

[0059] The dust cap 160 of the eighth embodiment includes any of the first to fifth embodiments, and is formed by press molding a sheet or film-like material.

[0060] The ninth embodiment of the diaphragm 100 is a diaphragm 100 provided in an electro-acoustic transducer, the diaphragm 100 having at least a neck portion 117 surrounding a predetermined reference axis 300 along the vibration direction, and a first portion 111, a second portion 112, and a third portion 113 arranged around the reference axis 300 outside the neck portion 117 and having different cross-sectional shapes taken along a plane including the reference axis 300, the cross-sectional shape of the first portion 111 being an arc with a first radius of curvature, the cross-sectional shape of the second portion 112 being an arc with a second radius of curvature different from the first radius of curvature, the cross-sectional shape of the third portion 113 being a part of an ellipse, the cross-sectional shapes of the neck portion 117 taken along any plane including the reference axis 300 being the same curve, and any dust cap 160 of the first embodiment to the eighth embodiment is arranged in the central portion.

[0061] The electro-acoustic transducer of the tenth embodiment comprises a dust cap 160 of any one of the first to eighth embodiments, a diaphragm 100, a magnetic circuit 124, a frame 126 that holds the magnetic circuit 124 and the diaphragm 100, and a voice coil 131 that is connected to the diaphragm 100 and positioned in a magnetic gap 125 provided by the magnetic circuit 124.

[0062] An eleventh embodiment of an electro-acoustic transducer includes the tenth embodiment, and the diaphragm 100 includes at least a first portion 111, a second portion 112, and a third portion 113, which are arranged around a predetermined reference axis 300 along the vibration direction and have mutually different cross-sectional shapes taken along a plane including the reference axis 300, and the cross-sectional shape of the first portion 111 is an arc with a first radius of curvature, the cross-sectional shape of the second portion 112 is an arc with a second radius of curvature different from the first radius of curvature, and the cross-sectional shape of the third portion 113 is a part of an ellipse. [Industrial Applicability]

[0063] The dust cap, diaphragm, and electroacoustic transducer according to the present disclosure can be applied to electronic devices such as audiovisual devices and information and communication devices, and mobile objects such as automobiles. [Explanation of symbols]

[0064] 100 diaphragm 110 Edge 111 First part 112 Second part 113 Third part 114 Fourth part 115 Connection 116 Through hole 117 Neck 118 Outer periphery 120 Speaker equipment 121 Magnet 122 Upper Plate 123 York 124 Magnetic Circuit 125 Magnetic Gap 126 frames 127 Periphery 129 Voice coil body 131 Voice coil 132 Bobbin 140 Automobiles 141 Driving means 142 Body 150 Mini component system 151 Enclosure 152 Amplifier 153 Tuner 154 players 160 Dust Cap 300 Reference axis

Claims

1. A dust cap disposed at a center of a diaphragm of an electroacoustic transducer, A first cross-sectional shape of the dust cap defined by a first plane including a predetermined reference axis along a vibration direction is different from a second cross-sectional shape of the dust cap defined by a second plane including the reference axis and intersecting the first plane. Dust cap.

2. The first cross-sectional shape is any two sides of a triangle.

2. The dust cap of claim 1.

3. The first cross-sectional shape is two hypotenuses of an isosceles triangle.

3. The dust cap of claim 2.

4. The shape changes continuously from the first cross-sectional shape to the second cross-sectional shape.

3. The dust cap according to claim 1 or 2.

5. The orthogonal cross-sectional shape of the orthogonal plane perpendicular to the reference axis is a curve.

3. The dust cap according to claim 1 or 2.

6. The dust cap is 3. The dust cap according to claim 1, which is formed by papermaking a material containing at least one of chemical fiber and pulp.

7. The dust cap is Made from injection molded resin 3. The dust cap according to claim 1 or 2.

8. The dust cap is Formed by pressing sheet or film-like materials 3. The dust cap according to claim 1 or 2.

9. A diaphragm provided in an electroacoustic transducer, The diaphragm is A neck portion that surrounds a predetermined reference axis along a vibration direction; At least a first portion, a second portion, and a third portion are arranged around the reference axis on the outside of the neck portion, and have cross-sectional shapes taken along a plane including the reference axis that are different from one another, The cross-sectional shape of the first portion is is a circular arc with a first radius of curvature, The cross-sectional shape of the second portion is an arc having a second radius of curvature different from the first radius of curvature; The cross-sectional shape of the third portion is It is part of an ellipse, The neck portion is The cross-sectional shape of any plane including the reference axis is the same curve, The dust cap according to claim 1 or 2 is disposed in the center. diaphragm.

10. A dust cap according to claim 1 or 2; A diaphragm; A magnetic circuit; a frame for holding the magnetic circuit and the diaphragm; a voice coil connected to the diaphragm and disposed in a magnetic gap of the magnetic circuit.

11. The diaphragm is The vibration transducer includes at least a first portion, a second portion, and a third portion that are arranged around a predetermined reference axis along a vibration direction and have mutually different cross-sectional shapes taken along a plane including the reference axis, The cross-sectional shape of the first portion is is a circular arc with a first radius of curvature, The cross-sectional shape of the second portion is an arc having a second radius of curvature different from the first radius of curvature; The cross-sectional shape of the third portion is It is part of an ellipse 11. The electroacoustic transducer according to claim 10.

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