Electroacoustic transducer

Abstract

This electroacoustic transducer (100) comprises a magnetic circuit (110), a coil (120), an oscillation plate (130), a frame (140), and an edge (150). The edge (150) includes: an up-roll portion (151) which curves to protrude toward a front side, which is one side of an oscillation direction of the oscillation plate (130); and a down-roll portion (152) which is connected concentrically to the up-roll portion (151) and which curves so as to protrude toward a rear side, which is the other side of the oscillation direction. The up-roll portion (151) includes a first bulging line (161) which protrudes toward the rear side and the down-roll portion (152) includes a second bulging line (162) which protrudes toward the front side. The inclination of the first bulging line (161) and the inclination of the second bulging line (162) are the same when viewed from the front side.

Description

Technical Field

[0001] The present disclosure relates to a device that converts acoustic vibrations, such as those of a microphone, into changes in an electrical quantity, or a device that converts changes in an electrical quantity into acoustic vibrations, such as a speaker.

Background Art

[0002] Conventionally, in order to suppress secondary distortion by equalizing the air discharge amount due to the amplitude in the front-rear direction of the edge that supports the diaphragm vibrating in a speaker, which is one type of electroacoustic transducer, a configuration in which an up-roll portion protruding toward the front side and a down-roll portion protruding toward the rear side are provided on the edge in a concentric circle shape is described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when an edge having an up-roll portion and a down-roll portion provided concentrically is adopted in a speaker, resonance may occur.

[0005] Therefore, the present disclosure solves this problem, and while adopting an edge having an up-roll portion and a down-roll portion provided concentrically to equalize the air discharge amount during vibration of the edge, it aims to provide an electroacoustic transducer that suppresses resonance and improves frequency characteristics.

Means for Solving the Problems

[0006] To achieve this object, an electroacoustic transducer according to one aspect of the present disclosure includes a magnetic circuit, a coil disposed in a magnetic gap of the magnetic circuit, a diaphragm to which the coil is connected, a frame that holds the magnetic circuit, and an edge that connects the diaphragm and the frame. The edge includes an up-roll portion that curves so as to protrude toward the front side, which is one side in the vibration direction of the diaphragm, and a down-roll portion that is connected concentrically with the up-roll portion and curves so as to protrude toward the rear side, which is the other side in the vibration direction. A plurality of linear first bulging strips that bulge toward one of the front-rear directions are provided on the up-roll portion, and a plurality of linear second bulging strips that bulge toward one of the front-rear directions are provided on the down-roll portion. When the protruding directions of the first bulging strip and the second bulging strip are different, the first bulging strip and the second bulging strip are inclined in the same direction with respect to the radial direction centered on the winding axis of the coil. When the protruding directions of the first bulging strip and the second bulging strip are the same, the first bulging strip and the second bulging strip are inclined in different directions with respect to the radial direction centered on the winding axis.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to suppress the torsional vibration of the diaphragm and improve the frequency characteristics of the electroacoustic transducer.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 8

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of an electroacoustic transducer will be described with reference to the drawings. Note that the following embodiments are examples for explaining the electroacoustic transducer and are not intended to limit the electroacoustic transducer. 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. Also, the X-axis, Y-axis, and Z-axis shown in the figures represent orthogonal coordinates arbitrarily set for the explanation of the figures. That is, the Z-axis does not necessarily follow the vertical direction, and the X-axis and Y-axis do not necessarily exist in the horizontal plane.

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

[0012] FIG. 1 is a cross-sectional view showing an electroacoustic transducer 100. FIG. 2 is a plan view showing the electroacoustic transducer 100 from the front side. Note that FIG. 1 is a cross-sectional view when cut along a plane including the winding axis 122 (central axis of the coil) of the coil 120. In FIG. 2, the hatching is not meant to indicate a cross-section, but is for distinguishing between the up-roll portion 151 (described later) and the down-roll portion 152 (described later), and is applied to the down-roll portion 152. Also, the front side (the Z+ side in the figure) is the side opposite to the magnetic circuit 110 with respect to the diaphragm 130 in the direction of the winding axis 122 of the coil 120, and is the side that emits sound. Note that the side where the magnetic circuit 110 is disposed with respect to the diaphragm 130 is the rear side (the Z− side in the figure).

[0013] In the case of the present embodiment, as the electroacoustic transducer 100, an example is given of a so-called speaker that converts an acoustic signal, which is a change in an electrical quantity, into an acoustic vibration, which is a vibration of air. The electroacoustic transducer 100 includes a magnetic circuit 110, a coil 120, a diaphragm 130, a frame 140, an edge 150, and a damper 170.

[0014] The magnetic circuit 110 includes a columnar magnet 111 that is a magnetized permanent magnet, a disk-shaped top plate 112 attached to the front side of the magnet 111, and a bottomed cylindrical yoke 113 that houses the magnet 111 and the top plate 112. The yoke 113 is attached to the rear side of the magnet 111. The gap between the top plate 112 and the yoke 113 forms an annular magnetic gap 114 in the magnetic circuit 110. A steady magnetic flux generated by the magnet 111 is generated in the magnetic gap 114. Note that, in the present embodiment, an inner-magnet type magnetic circuit 110 is exemplified, but the magnetic circuit 110 included in the electroacoustic transducer 100 may be an outer-magnet type.

[0015] Coil 120 is a coil to which an acoustic signal is input. The coil 120 is disposed within the magnetic gap 114 such that the winding axis 122 of the coil 120 coincides with the tube axis of the magnetic gap 114 formed by the magnetic circuit 110. In the case of the present embodiment, the coil 120 is wound around the outer circumference of a cylindrical bobbin 121 and is connected to the diaphragm 130 via the bobbin 121. The coil 120 reciprocates in the direction of the winding axis 122 (the Z-axis direction in the figure) due to the magnetic flux that changes corresponding to the audio signal generated in the coil 120.

[0016] The diaphragm 130 is a member that vibrates based on the vibration of the coil 120 and generates acoustic vibrations, that is, vibrations of air. The shape of the diaphragm 130 is not limited and may be a disc shape or the like. In the case of the present embodiment, the diaphragm 130 has a frustum shape, a so-called cone type, and a through-shaped diaphragm hole 131 into which the bobbin 121 is inserted is provided at the center. Further, a dome-shaped cap 132 that covers the diaphragm hole 131 is attached to the diaphragm 130.

[0017] The frame 140 is a structural member that fixedly holds the magnetic circuit 110 and holds the diaphragm 130 in a vibratable manner. The frame 140 includes an annular edge portion 141 that surrounds the outer peripheral edge of the diaphragm 130, a holding portion 142 that holds the magnetic circuit 110, and a connecting portion 143 that connects the edge portion 141 and the holding portion 142.

[0018] The damper 170 is a member having elasticity that supports the diaphragm 130 together with the edge 150 so that the diaphragm 130 vibrates linearly in the direction of the winding axis 122 of the coil 120. In the case of the present embodiment, the damper 170 is attached in a bridging manner between the connecting portion 143 of the bobbin 121 and the frame 140, and supports the diaphragm 130 via the bobbin 121 with respect to the frame 140. Note that the electroacoustic transducer 100 may not include the damper 170.

[0019] FIG. 3 is a perspective view showing the edge 150. The edge 150 is a member having elasticity for connecting the diaphragm 130 to the frame 140 in a vibratable manner. The material of the edge 150 is not limited, and examples thereof include rubber and elastomer. The edge 150 includes an up-roll portion 151 and a down-roll portion 152. In the case of this embodiment, the edge 150 includes a first attachment portion 153 attached to the edge 141 of the frame 140 by an adhesive or the like, and a second attachment portion 154 attached to the diaphragm 130 by an adhesive or the like.

[0020] The up-roll portion 151 is a portion that protrudes toward the front side, which is one side (Z+ side in the figure) in the vibration direction (Z-axis direction in the figure) of the diaphragm 130, and is a portion that curves in an arc shape. The cross-sectional shape of the up-roll portion 151 on the plane including the winding axis 122 of the coil 120 is the same arc shape over the entire circumference except for the bulging strip (details will be described later). A first bulging strip 161 is provided on the up-roll portion 151. In the case of this embodiment, the up-roll portion 151 is arranged concentrically inside the down-roll portion 152 and is integrally connected to the down-roll portion 152.

[0021] The down-roll portion 152 is a portion that protrudes toward the rear side, which is the other side (Z− side in the figure) in the vibration direction (Z-axis direction in the figure) of the diaphragm 130, and is a portion that curves in an arc shape. The cross-sectional shape of the down-roll portion 152 on the plane including the winding axis 122 of the coil 120 is the same arc shape over the entire circumference except for the bulging strip (details will be described later). A second bulging strip 162 is provided on the down-roll portion 152. In the case of this embodiment, the up-roll portion 151 is arranged concentrically inside the down-roll portion 152 and is integrally connected to the down-roll portion 152.

[0022] In the cross-section including the winding shaft 122 of the coil 120, the cross-sectional shape and size of the up-roll portion 151, and the cross-sectional shape and size of the down-roll portion 152 are set by detailed design. In the case of this embodiment, they are set to be the same. Since the down-roll portion 152 is arranged concentrically outside the up-roll portion 151, the volume of the region surrounded by the down-roll portion 152 is larger than the volume of the region surrounded by the up-roll portion 151. However, the inventor has found that the air discharge amount of the up-roll portion 151 and the air discharge amount of the down-roll portion 152 when the diaphragm 130 vibrates are equal, the power linearity is improved, and an increase in secondary distortion can be suppressed. This is because the amplitude of the down-roll portion 152 close to the first attachment portion 153 attached to the edge portion 141 of the frame 140 is smaller than the amplitude of the up-roll portion 151 far from the first attachment portion 153.

[0023] FIG. 4 is a perspective view showing one of the first bulging strips 161 from the front-oblique side. FIG. 5 is a perspective view showing one of the first bulging strips 161 from the rear-oblique side. In a plan view seen from the front side, the up-roll portion 151 is provided with a plurality of first bulging strips 161 that are inclined in the same direction with respect to the radial direction (the broken line in FIG. 2) centered on the winding shaft 122 of the coil 120 and bulge linearly. Similarly, the down-roll portion 152 is provided with second bulging strips 162. The first bulging strip 161, which is a bulging strip, is a portion that bulges in a streak shape in either the front-rear direction from the surface of the up-roll portion 151 in the direction of the winding shaft 122 (the broken line in FIGS. 4 and 5). Also, as shown in FIG. 4, the first bulging strip 161 is groove-shaped when viewed from one side, and as shown in FIG. 5, it is a protruding rib-shaped when viewed from the other side. Therefore, it can be explained that the first bulging strip 161 is a hollow rib with the side opposite to the protruding side being open. The second bulging strip 162 is the same as the first bulging strip 161.

[0024] In the case of this embodiment, as shown in FIG. 2, the inclination θ1 of the first bulging strip 161 and the inclination θ2 of the second bulging strip 162 are each inclined at 45 degrees or approximately 45 degrees. Also, the direction of inclination is a direction rotated by a predetermined angle (45 degrees in the case of this embodiment) in the clockwise direction when viewed from the front with respect to the radial direction centered on the winding shaft 122. In this way, by arranging the first bulging strip 161 and the second bulging strip 162 to be inclined in the same direction (also in the same direction when viewed from the rear side), the directions of torsional movement around the winding shaft 122 of the up-roll portion 151 and the down-roll portion 152 become opposite due to the forward and backward movement of the diaphragm 130. Here, "inclined in the same direction" means that when the clockwise direction when viewed from the front is taken as the positive direction for both the inclination θ1 of the first bulging strip 161 and the inclination θ2 of the second bulging strip 162, it means the case where 0 degrees < θ1 < 90 degrees, 0 degrees < θ2 < 90 degrees, or 0 degrees > θ1 > -90 degrees, 0 degrees > θ2 > -90 degrees. Note that "inclined in the opposite direction" means that when the clockwise direction when viewed from the front is taken as the positive direction, it means the case where 0 degrees < θ1 < 90 degrees, 0 degrees > θ2 > -90 degrees, or 0 degrees > θ1 > -90 degrees, 0 degrees < θ2 < 90 degrees.

[0025] The first bulging strip 161 provided on the up-roll portion 151 protrudes in a state where the front side is open and the rear side is closed. The second bulging strip 162 provided on the down-roll portion 152 protrudes toward the front side and the rear side is open. That is, the hollow first bulging strip 161 and the hollow second bulging strip 162 are respectively provided so as to be open to the convex surface which is the bulging side (front side) surface of the up-roll portion 151 and the convex surface which is the bulging side (rear side) surface of the down-roll portion 152. Also, the first bulging strip 161 and the second bulging strip 162 are respectively provided in a protruding shape within the concave surface which is the recessed side (rear side) surface of the up-roll portion 151 and the concave surface which is the recessed side (front side) surface of the down-roll portion 152. The number of the first bulging strips 161 provided on the up-roll portion 151 is the same as the number of the second bulging strips 162 provided on the down-roll portion 152.

[0026] The thicknesses of the first bulging strip 161 and the second bulging strip 162 are equal to the thicknesses of the other parts of the up-roll part 151 and the down-roll part 152. The first bulging strip 161 and the second bulging strip 162 extend linearly, and the cross-sectional shape of the surface perpendicular to the extending direction is U-shaped.

[0027] According to the above electroacoustic transducer 100, since the up-roll part 151 and the down-roll part 152 are each provided with a bulging strip, the structural strength is improved despite the entire edge 150 being wide, and each functions as a so-called tangential edge that suppresses the occurrence of resonance. Further, by combining the up-roll part 151 and the down-roll part 152, it is possible to equalize the amount of air discharged at the edge 150 due to the vibration of the diaphragm 130 and suppress the generation of secondary distortion.

[0028] In addition to the above effects, by making the inclination of the first bulging strip 161 provided on the up-roll part 151 and the inclination of the second bulging strip 162 of the down-roll part 152 in the same direction when viewed from the front side, the twist generated in the up-roll part 151 and the twist generated in the down-roll part 152 are generated in opposite directions to cancel each other out, and it is possible to suppress the occurrence of the phenomenon that the diaphragm 130 twists and vibrates. Therefore, it is possible to prevent the coil 120 from contacting the magnetic circuit 110 and improve the frequency characteristics of the generated sound.

[0029] Note that the present disclosure is not limited to the above-described embodiments. For example, another embodiment realized by arbitrarily combining the components described in this specification and excluding some of the components may also be an embodiment of the present disclosure. Further, modifications obtained by those skilled in the art by making various modifications within the scope not departing from the gist of the present disclosure, that is, the meaning indicated by the language described in the claims, are also included in the present disclosure.

[0030] For example, the case where the first bulging strip 161 is arranged to protrude from the concave surface of the up-roll portion 151 and the second bulging strip 162 is arranged to protrude from the concave surface of the down-roll portion 152 has been described. However, as shown in FIG. 6, the first bulging strip 161 may be arranged to protrude from the convex surface of the up-roll portion 151, and the second bulging strip 162 may be arranged to protrude from the convex surface of the down-roll portion 152.

[0031] Also, as shown in FIG. 7, the first bulging strip 161 may be arranged to protrude from the concave surface of the up-roll portion 151, and the second bulging strip 162 may be arranged to protrude from the convex surface of the down-roll portion 152. Conversely, the first bulging strip 161 may be arranged to protrude from the convex surface of the up-roll portion 151, and the second bulging strip 162 may be arranged to protrude from the concave surface of the down-roll portion 152. In this case, as shown in FIG. 8, in a plan view seen from the front side, the first bulging strip 161 and the second bulging strip 162 are arranged such that their inclinations are different from each other. Thereby, the twist of the up-roll portion 151 and the twist of the down-roll portion 152 can be made in opposite directions. That is, the protruding directions of the first bulging strip 161 and the second bulging strip 162 are different (see FIGS. 1 and 6), and the inclinations of the first bulging strip 161 and the second bulging strip 162 with respect to the radial direction centered on the winding shaft 122 are in the same direction as each other (see FIG. 2) in the first case. In the second case, the protruding directions of the first bulging strip 161 and the second bulging strip 162 are the same (see FIG. 7), and the inclinations of the first bulging strip 161 and the second bulging strip 162 with respect to the radial direction centered on the winding shaft 122 are in different directions from each other (see FIG. 8). Either case may be adopted, and in either case, the twist of the up-roll portion 151 and the twist of the down-roll portion 152 can be made in opposite directions.

[0032] Also, the inclinations of the first bulging strip 161 and the second bulging strip 162 with respect to the radial direction centered on the winding shaft 122 do not have to be the same angle as each other.

[0033] Also, in a plan view, the first bulging strip 161 and the second bulging strip 162 have been described as extending linearly, but the first bulging strip 161 and the second bulging strip 162 may be curved in a plan view, such as a gentle S shape.

[0034] Also, in the case of this embodiment, a speaker that generates sound has been exemplified as the electroacoustic transducer 100, but the electroacoustic transducer 100 may be a microphone or the like that converts acoustic air vibrations into an electric signal that is a change in an electric quantity.

[0035] Also, the edge 150 may include an up-roll portion 151 on the outside and a down-roll portion 152 on the inside. The edge 150 may include a plurality of pairs of the up-roll portion 151 and the down-roll portion 152.

[0036] Note that the number of the first bulging strips 161 provided on the up-roll portion 151 and the number of the second bulging strips 162 provided on the down-roll portion 152 may be different. However, in some cases, the design may be easier if the numbers are the same.

Industrial Applicability

[0037] The electroacoustic transducer according to the present disclosure can be applied to audio-visual devices including televisions and the like, electronic devices such as computers and smartphones, and further to moving bodies such as automobiles.

Description of Reference Numerals

[0038] 100 Electroacoustic transducer 110 Magnetic circuit 111 Magnet 112 Top plate 113 Yoke 114 Magnetic gap 120 Coil 121 Bobbin 122 Spool 130 Diaphragm 131 Diaphragm hole 132 Cap 140 Frame 141 Edge 142 Holding part 143 Connecting part 150 Edge 151 Up-roll part 152 Down-roll part 153 First mounting part 154 Second mounting part 161 First bulging strip 162 Second bulging strip 170 Damper

Claims

1. A magnetic circuit, a coil disposed in a magnetic gap of the magnetic circuit, a diaphragm to which the coil is connected, a frame that holds the magnetic circuit, and an edge that connects the diaphragm and the frame, wherein the edge includes an up-roll portion that curves so as to protrude toward the front side, which is one side in the vibration direction of the diaphragm, and a down-roll portion that is connected concentrically with the up-roll portion and curves so as to protrude toward the rear side, which is the other side in the vibration direction, a plurality of linear first bulging strips that bulge toward either one of the front-rear directions are provided on the up-roll portion, a plurality of linear second bulging strips that bulge toward either one of the front-rear directions are provided on the down-roll portion, and when the protruding directions of the first bulging strip and the second bulging strip are different, the first bulging strip and the second bulging strip incline in the same direction with respect to the radial direction centered on the winding axis of the coil, and when the protruding directions of the first bulging strip and the second bulging strip are the same, the first bulging strip and the second bulging strip incline in different directions with respect to the radial direction centered on the winding axis. An electroacoustic transducer.

2. The first bulging strip provided on the up-roll portion protrudes toward the rear side, the second bulging strip provided on the down-roll portion protrudes toward the front side, and the inclinations of the first bulging strip and the second bulging strip with respect to the radial direction centered on the winding axis are the same as each other. The electroacoustic transducer according to Claim 1.

3. The number of the first bulging strips is the same as the number of the second bulging strips. The electroacoustic transducer according to Claim 1 or 2.

4. The shape of the first bulging strip is equivalent to the shape of the second bulging strip. The electroacoustic transducer according to Claim 1 or 2.

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