Electroacoustic transducer

Abstract

To provide an electroacoustic converter capable of routing a signal line of the inner voice coil without affecting the vibration of an outer voice coil.SOLUTION: An electroacoustic converter 100 includes: a diaphragm 110; an inner voice coil 121 attached to the diaphragm 110; an outer voice coil 122 attached to the diaphragm 110 to enclose the inner voice coil outside the inner voice coil; a magnet 130; a yoke 140; a diaphragm 110; and a frame 150 holding the yoke 140. The magnet 130 has a through-shaped or notched wiring portion 133 in which the inner signal line of the inner voice coil 121 is wired.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to electroacoustic transducers such as speakers and microphones.

Background Art

[0002] Conventionally, in order to widen the frequency band of an electroacoustic transducer such as a speaker to the high frequency range, techniques related to reducing the diameter of the vibrating part have been proposed. On the other hand, reducing the diameter of the vibrating part is contrary to the conversion efficiency between electricity and sound. Therefore, Patent Document 1 describes a technique in which two voice coils arranged coaxially are attached to one diaphragm, and it is possible to widen the frequency band to the high frequency range while ensuring high efficiency.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it is desirable that the signal line connected to the inner voice coil be wired without affecting the vibration of the outer voice coil.

[0005] An object of the present disclosure is to provide an electroacoustic transducer in which two voice coils are attached to a diaphragm, and the signal line connected to the inner voice coil can be wired without affecting the vibration of the outer voice coil.

Means for Solving the Problems

[0006] One of the electroacoustic transducers according to the present disclosure includes a diaphragm, an inner voice coil attached to the diaphragm, an outer voice coil attached to the diaphragm so as to surround the inner voice coil outside the inner voice coil, a magnet, a yoke, and a frame that holds the diaphragm and the yoke. The magnet includes a through-shaped or notch-shaped wiring portion through which a pair of inner signal lines, which are signal lines of the inner voice coil, are wired.

Effects of the Invention

[0007] In the electroacoustic transducer according to the present disclosure, the signal line connected to the inner voice coil is wired in the wiring portion provided in the magnet, so that it can be wired without affecting the vibration of the outer voice coil.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 4

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Figure 10

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the electroacoustic conversion device according to the present disclosure will be described with reference to the drawings. Note that the following embodiments are examples for explaining the present disclosure and are not intended to limit the present disclosure. For example, the shapes, structures, materials, components, relative positional relationships, connection states, numerical values, mathematical formulas, the content of each step in the method, the order of each step, etc. shown in the following embodiments are examples, and may include content not described below. Also, geometric expressions such as parallel and orthogonal may be used, but these expressions do not indicate mathematical strictness and include substantially allowable errors, deviations, etc. Also, expressions such as simultaneous and identical also include a substantially allowable range.

[0010] Also, the drawings are schematic diagrams that have been appropriately emphasized, omitted, or adjusted in ratio for explaining the present disclosure, and are different from the actual shapes, positional relationships, and ratios.

[0011] Also, in the following, a plurality of inventions may be comprehensively described as one embodiment. Also, a part of the content described below is explained as an arbitrary component related to the present disclosure.

[0012] (Embodiment 1) FIG. 1 is a perspective view showing the appearance of the electroacoustic conversion device 100 according to Embodiment 1 from the diaphragm 110 side. FIG. 2 is a perspective view showing the electroacoustic conversion device 100 according to Embodiment 1 with the diaphragm 110 omitted. FIG. 3 is a perspective view showing the appearance of the electroacoustic conversion device 100 according to Embodiment 1 from the side opposite to the diaphragm 110. FIG. 4 is a cross-sectional view showing the electroacoustic conversion device 100 according to Embodiment 1 cut along the position of line I-I shown in FIG. 1.

[0013] As shown in these figures, the electroacoustic transducer 100 includes a diaphragm 110, an inner voice coil 121, an outer voice coil 122, a magnet 130, a yoke 140, and a frame 150.

[0014] The diaphragm 110 is a member to which the inner voice coil 121 and the outer voice coil 122 are coupled, and is a member that converts the vibration of air caused by displacement in the front-rear direction (the Z-axis direction in the figure) with respect to the neutral position and the acoustic signals generated in the inner voice coil 121 and the outer voice coil 122. The shape of the diaphragm 110 is not particularly limited, but in the case of the first embodiment, the shape of the diaphragm 110 is circular as a whole. The diaphragm 110 includes a circular annular inner coupling portion 111 to which the inner voice coil 121 is coupled, a circular annular outer coupling portion 112 to which the outer voice coil 122 is coupled, and a circular annular peripheral portion 113 attached to the frame.

[0015] The inner coupling portion 111 and the outer coupling portion 112 have a trapezoidal cross section and bulge outward (the Z+ side in the figure). The inner voice coil 121 and the outer voice coil 122 are respectively attached to flat top surface portions corresponding to the upper bases of the trapezoids. The inside of the inner coupling portion 111 is sealed by a dome-shaped inner film portion 114 that bulges outward. The space between the inner coupling portion 111 and the outer coupling portion 112 is connected by an annular film portion 115 having an arc-shaped cross section and bulging outward. The space between the outer coupling portion 112 and the peripheral portion 113 is connected by an edge 116 having an arc-shaped cross section and bulging outward.

[0016] Note that the shape of the diaphragm 110 may also be conical, elliptical conical, pyramidal, elliptical plate, rectangular flat plate, etc. The material constituting the diaphragm 110 is not particularly limited, and examples thereof include paper and resin.

[0017] The inner voice coil 121 is a component whose one end is disposed within the inner magnetic gap 141 (see FIGS. 2 and 4), and the other end is attached to the inner coupling portion 111 of the diaphragm 110. By vibrating together with the diaphragm 110, it interacts with the magnetic flux constantly present within the inner magnetic gap 141, and is a component that converts the vibration of air and the acoustic signal.

[0018] The axis (central axis) of the inner voice coil 121 is disposed in the direction of vibration (amplitude) of the diaphragm 110 (Z-axis direction in the figure), and is orthogonal to the direction of the magnetic flux within the inner magnetic gap 141.

[0019] In the case of the first embodiment, the inner voice coil 121 is a coil having an overall cylindrical shape formed by winding a single metallic wire a plurality of times in the axial direction (Z-axis direction in the figure). Also, the inner voice coil 121 has a plurality of layers (two layers in the case of the first embodiment) of coils electrically connected in series in the radial direction, and both the start and end of the winding are located on the side of the diaphragm 110. Further, extending from the inner voice coil 121 are a first inner signal line 161 and a second inner signal line 162 connected to both ends of the wire forming the coil. Details of the signal lines including the first inner signal line 161 and the second inner signal line 162 will be described later.

[0020] The outer voice coil 122 is a component attached to the diaphragm 110 so as to surround the inner voice coil 121 on the outside of the inner voice coil 121. Similar to the inner voice coil 121, the outer voice coil 122 converts the vibration in the axial direction (Z-axis direction in the figure) and the acoustic signal by interaction with the magnetic flux constantly present within the outer magnetic gap 142.

[0021] In the case of Embodiment 1, the winding axis (central axis) of the outer voice coil 122 is arranged coaxially with the winding axis of the inner voice coil 121. Similar to the outer voice coil 122 and the inner voice coil 121, it is a cylindrical coil in an overall view formed by winding a single metallic wire a plurality of times in the winding axis direction (Z-axis direction in the figure). Further, the outer voice coil 122 has a plurality of layers (two layers in the case of Embodiment 1) of coils arranged with electrical series connection in the radial direction, and both the start and the end of winding are located on the diaphragm 110 side. Further, from the outer voice coil 122, a first outer signal line 163 and a second outer signal line 164 connected to both ends of the wire forming the coil extend.

[0022] Note that the voice coil including the inner voice coil 121 and the outer voice coil 122 may be provided with a bobbin. The bobbin is a cylindrical member that serves as a base around which the wire is wound, and is made of a material such as aluminum or resin. Also, the winding directions of the wires of the inner voice coil 121 and the outer voice coil 122 may be the same or different. The winding direction is determined by the phase of the acoustic signal generated in each.

[0023] The magnet 130 is a permanent magnet that generates a steady magnetic flux acting on the magnetic flux that changes based on the acoustic signals input to the inner voice coil 121 and the outer voice coil 122 in the inner magnetic gap 141 and the outer magnetic gap 142, respectively. The magnet 130 includes a through or notch-shaped wiring portion 133 in which a pair of first inner signal lines 161 and a second inner signal line, which are a pair of signal lines of the inner voice coil 121, are wired.

[0024] In the case of Embodiment 1, the magnet 130 has an annular shape with a rectangular cross-section, and a central hole penetrating in the thickness direction (Z-axis direction in the figure) serves as the wiring portion 133. A cylindrical inner cylinder portion 143, which is a part of the yoke 140, is inserted and arranged in the wiring portion 133, forming an annular inner magnetic gap 141 between the magnet 130 and the inner cylinder portion 143. A cylindrical insulating member 153 is inserted and arranged inside the wiring portion 133 and inside the inner cylinder portion 143. The first inner signal line 161 and the second inner signal line 162, which are inner signal lines, protrude from the inner voice coil 121 toward the inside to the inside of the insulating member 153 and are wired in an inserted state inside the insulating member 153. This prevents a short circuit between the inner signal lines and the yoke 140. Note that the insulating member 153 is integrally formed with the frame 150.

[0025] It is preferable to use, for example, a neodymium-based magnet or the like for the magnet 130 that has high magnetic energy. Thereby, the thickness of the magnet 130 can be reduced, and the thickness of the entire electroacoustic conversion device 100 can be reduced. Furthermore, weight reduction can also be achieved.

[0026] The yoke 140 guides the magnetic flux generated from the side opposite to the diaphragm 110 of the magnet 130 to the diaphragm 110 side in the winding axis direction of the inner voice coil 121, and is a member that generates a steady magnetic flux in the inner magnetic gap 141 and the outer magnetic gap 142 provided between the magnet 130 and the yoke 140. The yoke 140 is made of a magnetic material.

[0027] The yoke 140 of Embodiment 1 includes an annular base portion 145 with a rectangular cross-section to which the annular magnet 130 is attached. A cylindrical inner cylinder portion 143 protruding from the inner peripheral portion of the base portion 145 toward the diaphragm 110 side is arranged, and a cylindrical outer cylinder portion 144 protruding from the outer peripheral portion of the base portion 145 toward the diaphragm 110 side is arranged.

[0028] Note that the yoke 140 may be provided with an annular top plate on the side opposite to the base portion 145 with respect to the magnet 130. Also, in the case of the first embodiment, the magnet 130 and the base portion 145 of the yoke 140 are fixed by an adhesive, but the magnet 130 and the yoke 140 may be fixed using fastening members such as screws and rivets.

[0029] A magnetic circuit is formed by the magnet 130 and the yoke 140. The magnetic circuit is attached to the frame 150 so as to be located behind the diaphragm 110, and includes an annular inner magnetic gap 141 and an outer magnetic gap 142 that face the diaphragm 110. The inner magnetic gap 141 is a gap that generates a steady magnetic flux in a direction intersecting the magnetic flux generated in the inner voice coil 121, and the outer magnetic gap 142 is a gap that generates a steady magnetic flux in a direction intersecting the magnetic flux generated in the outer voice coil 122.

[0030] The frame 150 is a member that holds the diaphragm 110 and the yoke 140. In the case of the first embodiment, the frame 150 includes a cylindrical first frame 151 attached to the outer cylindrical portion 144 of the yoke 140, and an annular second frame 152 that covers the surface of the base portion 145 of the yoke 140 opposite to the diaphragm 110. A cylindrical insulating member 153 that protrudes from the inner peripheral portion of the second frame 152 toward the diaphragm 110 side is integrally formed with the second frame 152.

[0031] The frame 150 is a member that houses the magnetic circuit, the inner voice coil 121, and the outer voice coil 122. The outer peripheral portion of the diaphragm 110 is attached to the open end portion of the first frame 151 by an adhesive or the like. The material constituting the frame 150 is not particularly limited, but in the case of the first embodiment, the frame 150 is a resin molded product having insulating properties.

[0032] The signal line is an electric wire such as a gold wire that inputs an acoustic signal to the voice coil or outputs an acoustic signal from the voice coil. In the case of Embodiment 1, the first inner signal line 161 and the second inner signal line 162, which are inner signal lines connected to the inner voice coil 121, are wired in a plane including the reel of the inner voice coil 121 inside the frame 150. The first outer signal line 163 and the second outer signal line 164, which are outer signal lines connected to the outer voice coil 122, are wired in a plane perpendicular to the reel of the inner voice coil 121 inside the frame 150.

[0033] The first inner signal line 161 and the second inner signal line 162 are pierced inside the cylindrical insulating member 153 and wired to the outside of the second frame 152. The first outer signal line 163 and the second outer signal line 164 pass between the outer cylindrical portion 144 of the yoke 140 and the diaphragm 110, and are respectively pierced inside a pair of groove portions 154 provided in the first frame 151 and wired to the outside of the first frame 151.

[0034] The inner voice coil 121 includes inner and outer two-layer coils in the radial direction. The first inner signal line 161 connected to the end of the outer coil is wired so as to protrude from the outside of the inner voice coil 121 beyond the edge portion in contact with the diaphragm 110 of the inner voice coil 121 to the inside of the inner voice coil 121. Further, the inner coupling portion 111 of the diaphragm 110 is provided with an annular inner protrusion 117 and an outer protrusion 118 protruding toward the magnet 130 on the inside and outside of the inner voice coil 121 to be attached, respectively. The first inner signal line 161 is bent or curved so as to avoid the inner protrusion 117.

[0035] According to the electroacoustic transducer 100 according to Embodiment 1, since the area of the inner film portion 114 corresponding to the inner voice coil 121 is small and the weight is light, it is advantageous for high-frequency vibration, and the frequency band of the electroacoustic transducer 100 can be expanded to the high-frequency range. Further, since the area of the annular film portion 115 corresponding to the outer voice coil 122 is large, it is advantageous for improving the sound pressure level. Therefore, even when the entire diaphragm 110 is reduced in diameter, the conversion efficiency between the acoustic signal and the air vibration can be increased by the inner voice coil 121 and the outer voice coil 122.

[0036] In addition, the first inner signal line 161 and the second inner signal line 162 connected to the inner voice coil 121 are wired to the outside of the frame 150 through the wiring portion 133 that penetrates in the thickness direction at the center of the magnet 130, so that they do not interfere with the outer voice coil 122 or the outer signal line.

[0037] (Embodiment 2) Embodiment 2 of the electroacoustic transducer 100 will be described. Note that components (parts) having the same operations, functions, shapes, mechanisms, and structures as those in Embodiment 1 may be denoted by the same reference numerals and the description thereof may be omitted. Further, in the following, the description will focus on the differences from Embodiment 1, and the description of the same content may be omitted.

[0038] FIG. 5 is a perspective view showing the appearance of the electroacoustic transducer 100 according to Embodiment 2 from the diaphragm 110 side. FIG. 6 is a perspective view showing the electroacoustic transducer 100 according to Embodiment 2 with the diaphragm 110 omitted. FIG. 7 is a cross-sectional view showing the electroacoustic transducer 100 according to Embodiment 2 cut along the line II-II shown in FIG. 5. FIG. 8 is a perspective view showing the electroacoustic transducer 100 according to Embodiment 2 disassembled.

[0039] As shown in these figures, the electroacoustic transducer 100 according to Embodiment 2 includes a diaphragm 110, an inner voice coil 121, an outer voice coil 122, a magnet 130, a yoke 140, and a frame 150.

[0040] In the case of Embodiment 2, the shape of the diaphragm 110 is rectangular (square) when viewed as a whole. The diaphragm 110 includes a rectangular annular inner coupling portion 111 to which the inner voice coil 121 is coupled, a rectangular annular outer coupling portion 112 to which the outer voice coil 122 is coupled, and a rectangular annular peripheral portion 113 attached to the frame.

[0041] The inner coupling portion 111 and the outer coupling portion 112 have a flat cross-section. The inside of the inner coupling portion 111 is sealed with an inner film portion 114 that bulges outward. The space between the inner coupling portion 111 and the outer coupling portion 112 is connected by an annular film portion 115 with an arcuate cross-section that bulges outward. The space between the outer coupling portion 112 and the peripheral portion 113 is connected by an edge 116 with an arcuate cross-section that bulges outward.

[0042] The inner voice coil 121 is a component whose one end is disposed within the inner magnetic gap 141 (see FIGS. 6 and 7) and the other end is attached to the inner coupling portion 111 of the diaphragm 110. It generates magnetic flux based on the input acoustic signal and vibrates in the winding axis direction (Z-axis direction in the figure) due to the interaction with the magnetic flux constantly present within the inner magnetic gap 141.

[0043] The winding axis of the inner voice coil 121 (an axis that passes through the center of the diaphragm and extends virtually in the vibration direction of the diaphragm) is orthogonal to the direction of the magnetic flux within the inner magnetic gap 141.

[0044] In the case of the second embodiment, the outer voice coil 122 is attached to the diaphragm 110 so as to surround the inner voice coil 121 on the outside of the inner voice coil 121, and the winding axis (central axis) of the outer voice coil 122 is arranged coaxially with the winding axis of the inner voice coil 121. Similar to the outer voice coil 122 and the inner voice coil 121, it is a coil formed by winding a single metallic wire a plurality of times in the winding axis direction (Z-axis direction in the figure). Also, the outer voice coil 122 has a plurality of layers (two layers in the case of the second embodiment) of coils electrically connected in series in the radial direction, and both the start and end of the winding are located on the side of the diaphragm 110. Further, from the outer voice coil 122, a first outer signal line 163 and a second outer signal line 164 connected to both ends of the wire forming the coil extend.

[0045] In the case of the second embodiment, the magnet 130 includes a rectangular parallelepiped first magnet 131 and a second magnet 132 having the same shape and the same size as the first magnet 131. Both edge portions in the depth direction (Y-axis direction in the figure) of the first magnet 131 and the second magnet 132 are chamfered. Thereby, interference between the curved four corners of the outer voice coil 122 and the magnet 130 can be avoided. Also, loss of the magnet 130 made of a brittle material can be suppressed. In the second embodiment, C chamfering is performed, but R chamfering may also be used.

[0046] The first magnet 131 and the second magnet 132 are arranged side by side with a predetermined gap in the width direction (X-axis direction in the figure) so that the opposing surfaces are parallel. The gap between the first magnet 131 and the second magnet 132 serves as a wiring portion 133 that penetrates in both the thickness direction (Z-axis direction in the figure) and the depth direction (Y-axis direction in the figure).

[0047] In the depth direction, wall-shaped inner wall portions 146, which are parts of the yoke 140, are respectively inserted and arranged in the middle portion of the wiring portion 133, and form linear inner magnetic gaps 141 with the first magnet 131 and the second magnet 132 respectively. The first inner signal line 161 and the second inner signal line 162, which are inner signal lines, are wired in the wiring portion 133 so as to gradually move away from the diaphragm 110 as they go from the inner voice coil 121 toward the outer side in the depth direction, and are wired to the outside of the frame 150 after passing through the outer voice coil 122. Note that the inner signal lines are all wired so as to gradually approach the diaphragm 110 as they go from the outer voice coil 122 toward the outer side in the depth direction.

[0048] The yoke 140 of the second embodiment includes a first yoke 147 and a second yoke 148, which are separate bodies corresponding to the first magnet 131 and the second magnet 132. The first yoke 147 and the second yoke 148 are arranged side by side with a predetermined gap in the width direction (the X-axis direction in the figure). The first yoke 147 and the second yoke 148 each include a rectangular plate-shaped base portion 145 to which the rectangular parallelepiped first magnet 131 and the second magnet 132 are respectively attached. Inside each base portion 145, plate-shaped inner wall portions 146 protruding toward the diaphragm 110 side are arranged, and plate-shaped outer peripheral wall portions 149 protruding toward the diaphragm 110 side are arranged from the outer peripheral portion of the entire base portion 145 arranged side by side. A plurality of through-shaped notches 104 into which the protruding portions 155 provided on the frame 150 are inserted are provided in the outer peripheral wall portion 149.

[0049] In the case of the second embodiment, the frame 150 holds the first yoke 147 and the second yoke 148 while surrounding the outer peripheral wall portion 149 of the yoke 140. The frame 150 is in the shape of a rectangular cylinder and includes a protruding portion 155 that protrudes inward from the inner peripheral surface. The first yoke 147 and the second yoke 148 are inserted into the frame 150 from the side opposite to the portion where the diaphragm 110 is attached, and the plurality of protruding portions 155 and the plurality of notches 104 are engaged with each other to align the frame 150 with the first yoke 147 and the second yoke 148. Thereby, a predetermined gap between the first yoke 147 and the second yoke 148 is determined.

[0050] In the case of the second embodiment, the first inner signal line 161 and the second inner signal line 162, which are inner signal lines connected to the inner voice coil 121, and the first outer signal line 163 and the second outer signal line 164, which are outer signal lines connected to the outer voice coil 122, are wired in the same direction in the depth direction.

[0051] The first inner signal line 161, the second inner signal line 162, the first outer signal line 163, and the second outer signal line 164 pass through a notch 104 provided on one surface of the outer peripheral wall portion 149 of the yoke 140 and through four groove portions 154 provided on one surface of the frame 150 and are wired to the outside of the frame 150.

[0052] In the case of the second embodiment, the electroacoustic transducer 100 includes a pair of inner input terminals 171 to which the first inner signal line 161 and the second inner signal line 162 are electrically connected, respectively, and a pair of outer input terminals 172 to which the first outer signal line 163 and the second outer signal line 164 are electrically connected, respectively. The inner input terminals 171 and the outer input terminals 172 are attached to a terminal block 156 in the shape of a rectangular plate that protrudes outward from the surface of the frame 150 where the groove portion 154 is provided.

[0053] The internal input terminal 171 may receive an acoustic signal in a higher frequency range than the external input terminal 172 from the amplification device. Also, depending on the winding directions of the wires of the internal voice coil 121 and the external voice coil 122, acoustic signals of opposite phases may be input to the internal input terminal 171 and the external input terminal 172 respectively from the amplification device.

[0054] According to the electroacoustic conversion device 100 according to Embodiment 2, since the area of the inner film portion 114 corresponding to the internal voice coil 121 is small and the weight is light, it acts advantageously on vibrations of high frequencies, and the frequency band of the electroacoustic conversion device 100 can be widened to a higher frequency range. Also, since the area of the annular film portion 115 corresponding to the external voice coil 122 is large, it acts advantageously on the improvement of the sound pressure level. Therefore, even when the diameter of the diaphragm 110 is reduced, the conversion efficiency between electricity and acoustics can be increased by the internal voice coil 121 and the external voice coil 122.

[0055] Also, since the first internal signal line 161 and the second internal signal line 162 connected to the internal voice coil 121 are wired to the outside of the frame 150 through the wiring portion 133 which is the gap between the first magnet 131 and the second magnet 132, they do not interfere with the external voice coil 122 or the external signal lines.

[0056] Also, since the first internal signal line 161, the second internal signal line 162, the first external signal line 163, and the second external signal line 164 are wired in the same direction, it becomes possible to easily route the wiring between the amplification device.

[0057] Note that the present disclosure is not limited to the above embodiments. For example, another embodiment realized by arbitrarily combining the components described in this specification and excluding some of the components may be used as an embodiment of the present disclosure. Also, modification examples obtained by applying various modifications that a person skilled in the art can come up with without departing from the gist of the present disclosure, that is, the meaning indicated by the language described in the claims, with respect to the above embodiments are also included in the present disclosure.

[0058] For example, in Embodiment 1, a circular ring-shaped magnet 130 was exemplified, but the magnet may be rectangular ring-shaped.

[0059] Also, in Embodiment 2, the magnet 130 divided into two and the yoke 140 divided into two were exemplified, but at least one of them may be integral.

[0060] Further, as shown in FIGS. 9 and 10, the electroacoustic transducer 100 may include a first top plate 157 and a second top plate 158 (hereinafter, may be collectively referred to as "top plate 105") corresponding to the first magnet 131 and the second magnet 132. The top plate 105 is a member arranged in contact with the magnet 130 on the opposite side of the yoke 140 with respect to the magnet 130. The top plate 105 is a member made of a magnetic material that forms an inner magnetic gap 141 and an outer magnetic gap 142 with the yoke 140, and concentrates the steady magnetic flux generated by the magnet 130 in the inner magnetic gap 141 and the outer magnetic gap 142. Thereby, the conversion efficiency between electricity and sound in the inner voice coil 121 and the outer voice coil 122 can be improved.

[0061] As shown in FIG. 10, rectangular cutouts may be provided at the four corners of the top plate 105. Also, chamfers such as C-chamfers and R-chamfers may be provided. Thereby, interference between the top plate 105 and the corner portions of the outer voice coil 122 can be avoided.

[0062] When the electroacoustic transducer 100 includes the top plate 105, the magnet 130 is sized to be hidden by the top plate 105 in a top view, and the four corners of the magnet 130 do not have to be intentionally chamfered.

[0063] Also, the wiring portion 133 may be formed in a state where a part of the magnet 130 is cut out.

[0064] Also, the electroacoustic conversion device 100 may be used in an acoustic system including an amplification device that can input an acoustic signal containing a strong component in a higher frequency range than the external voice coil 122.

Industrial Applicability

[0065] The present disclosure is applicable to electroacoustic conversion devices such as microphones and speakers, and particularly to electroacoustic conversion devices that perform conversion between sound and acoustic signals in the high frequency range.

Explanation of Reference Numerals

[0066] 100 Electroacoustic conversion device 104 Notch 105 Top plate 110 Diaphragm 111 Inner coupling part 112 Outer coupling part 113 Peripheral edge part 114 Inner film part 115 Ring film part 116 Edge 117 Inner protruding strip 118 Outer protruding strip 121 Inner voice coil 122 Outer voice coil 130 Magnet 131 First magnet 132 Second magnet 133 Wiring part 140 Yoke 141 Inner magnetic gap 142 Outer magnetic gap 143 Inner cylindrical part 144 Outer cylindrical part 145 Base part 146 Inner wall part 147 First yoke 148 Second yoke 149 Outer peripheral wall part 150 Frame 151 First frame 152 Second frame 153 Insulating member 154 Groove part 155 Protrusion 156 Terminal Block 157 First Top Plate 158 Second Top Plate 161 First Inner Signal Line 162 Second Inner Signal Line 163 First Outer Signal Line 164 Second Outer Signal Line 171 Inner Input Terminal 172 Outer Input Terminal

Claims

1. A diaphragm, an inner voice coil attached to the diaphragm, an outer voice coil attached to the diaphragm so as to surround the inner voice coil outside the inner voice coil, a first magnet and a second magnet, a yoke, a frame for holding the diaphragm and the yoke, a wiring portion, and comprising the wiring portion is formed between the first magnet and the second magnet, a pair of inner signal lines which are signal lines of the inner voice coil project toward the outside of the inner voice coil and extend beyond the outer voice coil an electroacoustic transducer.

2. comprising a rectangular flat plate-shaped first top plate and a second top plate corresponding to the first magnet and the second magnet, the first top plate and the second top plate each having rectangular notches at their four corners The electroacoustic transducer according to claim 1.

3. A pair of the inner signal lines and a pair of outer signal lines which are signal lines of the outer voice coil are connected to an amplifier such that acoustic signals of opposite phases flow through the inner voice coil and the outer voice coil, respectively. The electroacoustic transducer according to claim 1 or 2.

4. a pair of inner input terminals to which the pair of inner signal lines are electrically connected, a pair of outer input terminals to which a pair of outer signal lines which are signal lines of the outer voice coil are electrically connected, an acoustic signal in a higher frequency range than the outer input terminals is input from an amplifier to the inner input terminals The electroacoustic transducer according to any one of claims 1 to 3.

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