Speaker

Abstract

The present invention provides a speaker that is capable of reducing a distortion component in generated sound. A speaker (1) is characterized by comprising: a vibration plate (11); a frame (13) that holds the outer edge of a vibration plate (11) from the back surface side which is opposite to the sound radiation side; a cover (14) that is disposed on the sound radiation side of the vibration plate (11) and that is fixed to the frame (13); and a protrusion (15) that protrudes from the cover (14) toward an outer region of a non-holding part (11b) excluding a holding portion (11a) which is held by the frame (13) in the vibration plate (11) and that interferes with the outer region of the non-holding portion (11b) from the sound radiation side.

Description

speaker

[0001] The present invention relates to a speaker.

[0002] Conventionally, speakers that generate sound by supplying an audio signal to a voice coil disposed in a magnetic field and vibrating a diaphragm via a bobbin around which the voice coil is wound have been widely used (see, for example, Patent Document 1). In the speaker described in Patent Document 1, the diaphragm includes a central circular dome portion, a ring-shaped cone portion that extends radially from the outer periphery of the dome portion while protruding toward the sound emitting side, and a ring-shaped edge that extends further radially from the outer periphery and is held by a frame. The bobbin is formed in a cylindrical shape with an opening edge adhesively fixed from the back side at the boundary between the circular dome portion and the cone portion, and the voice coil is wound around the bobbin.

[0003] Japanese Patent Application Laid-Open No. 2020-156031

[0004] In the above-mentioned speakers, a resonance phenomenon called split resonance occurs, in which the center and outer periphery of the diaphragm do not move in the same way but move in a wave-like manner, and this resonance can cause distortion components to be mixed into the sound from the diaphragm. Such distortion components are different from the original sound represented by the audio signal, and they lead to a deterioration in the quality of the sound generated by the speaker, so it is desirable to reduce them.

[0005] Therefore, an object of the present invention is to provide a speaker that can reduce distortion components in generated sound, for example.

[0006] In order to solve the above-mentioned problems and achieve the object, the speaker of the present invention is characterized by comprising a diaphragm, a frame that holds the outer edge of the diaphragm from the back side opposite the sound emission side, a cover that is positioned on the sound emission side of the diaphragm and fixed to the frame, and a protrusion that protrudes from the cover toward the outer periphery of the non-held portion of the diaphragm excluding the portion held by the frame, and interferes with the outer periphery of the non-held portion from the sound emission side.

[0007] 1 is a perspective view of a speaker according to an embodiment, as seen from the sound-emitting side; FIG. 1 is a plan view of the speaker shown in FIG. 1, as seen from the sound-emitting side; FIG. 2 is a cross-sectional view of the speaker shown in FIGS. 1 and 2, taken along line V11-V11 in FIG. 2; FIG. 3 is an enlarged view of area A11 in FIG. 3; FIG. 1 is a cutaway perspective view of the speaker shown in FIGS. 1 and 2, cut so that the cross-section shown in FIG. 3 is visible; FIG. 5 is an enlarged perspective view of area A12 in FIG. 5; FIG. 6 is an enlarged view of a comparative example to the speakers shown in FIGS. 1 to 6, showing a local cross-section equivalent to FIG. 4; FIG. 7 is an enlarged perspective view of the comparative example shown in the local cross-section in FIG. 7, showing a local cut cross-section equivalent to FIG. 6; FIG. 8 is a graph showing the frequency characteristics of sound emitted by the speakers of the comparative examples shown in FIGS. 7 and 8; FIG. 9 is a graph showing the frequency characteristics of sound emitted by the speakers of the embodiments shown in FIGS. 1 to 6.

[0008] A speaker according to one embodiment of the present invention will be described below. The speaker according to one embodiment of the present invention includes a diaphragm, a frame, a cover, and a protrusion. The frame is a portion that holds the outer edge of the diaphragm from the rear side opposite the sound emission side. The cover is a portion that is disposed on the sound emission side of the diaphragm and is fixed to the frame. The protrusion protrudes from the cover toward the outer periphery of the non-held portion of the diaphragm excluding the portion held by the frame, and is a portion that interferes with the outer periphery of the non-held portion from the sound emission side.

[0009] With this speaker, the protrusions interfere with the outer periphery of the vibrating non-retained portion of the diaphragm from the sound emitting side, thereby dispersing resonances such as split resonances in the diaphragm. Dispersing the resonances in the diaphragm reduces distortion components mixed into the sound from the diaphragm, improving sound quality.

[0010] In this embodiment, the protrusion is a portion of the cover that protrudes toward the outer periphery of the non-holding portion, which reduces manufacturing costs compared to when the protrusion is a separate part.

[0011] In this embodiment, the protrusions are configured to bite into the outer periphery of the non-holding portion, which further enhances the effect of dispersing resonance compared to when the protrusions are simply in contact with the outer periphery of the non-holding portion.

[0012] In this embodiment, the protrusions interfere with the outer periphery of the non-retaining portion over a predetermined width in the circumferential direction. This configuration makes it possible to disperse resonance while suppressing changes in the vibration characteristics of the diaphragm, compared to when the protrusions interfere with the outer periphery of the diaphragm over the entire periphery.

[0013] In this embodiment, a plurality of protrusions having a predetermined width are disposed in a dispersed manner with their positions shifted in at least one of the circumferential direction and the radial direction of the non-holding portion. With this configuration, the displacement of the plurality of protrusions can further enhance the effect of dispersing resonance.

[0014] Furthermore, in this embodiment, in addition to the above-described configuration in which multiple protrusions of a predetermined width are dispersed, the following configuration is further provided: First, the cover has an outer periphery frame fixed to the frame, a vibration adjustment unit disposed opposite the center of the diaphragm to adjust the frequency of the sound emitted by the diaphragm, and multiple spokes extending radially from the vibration adjustment unit to the outer periphery frame. The protrusions have a shape in which the base portion of each of the multiple spokes on the outer periphery frame side protrudes by the spoke width. With this configuration, using multiple spokes makes it easier to form the protrusion shape of the protrusions on the cover, thereby reducing manufacturing costs.

[0015] An embodiment of a speaker will be described. Fig. 1 is a perspective view of a speaker according to the embodiment, as seen from the sound-emitting side, and Fig. 2 is a plan view of the speaker shown in Fig. 1, as seen from the sound-emitting side. Fig. 3 is a cross-sectional view of the speaker shown in Figs. 1 and 2, taken along line V11-V11 in Fig. 2, and Fig. 4 is an enlarged view of area A11 in Fig. 3. Fig. 5 is a cutaway perspective view of the speaker shown in Figs. 1 and 2, cut so that the cross-section shown in Fig. 3 is visible, and Fig. 6 is an enlarged perspective view of area A12 in Fig. 5.

[0016] The speaker 1 of this embodiment is a tweeter speaker used to reproduce high-pitched sounds, and includes a diaphragm 11 , a drive unit 12 , a frame 13 , a cover 14 , and a protrusion 15 .

[0017] The diaphragm 11 includes a central circular dome portion 111, a ring-shaped cone portion 112 extending from the outer periphery of the dome portion 111 in the radial direction D12 while protruding toward the sound radiation side, and an edge portion 113. The edge portion 113 is a ring-shaped portion extending from the outer periphery of the cone portion 112 to the side opposite the sound radiation side, directly downward in the axial direction D11 along the axis X11, and then bending in the radial direction D12 for a predetermined width. In this embodiment, the diaphragm 11 is a single sheet member in which the circular dome portion 111, the cone portion 112, and the edge portion 113 are seamlessly connected. The edge portion 113 (outer edge) of the diaphragm 11 is adhesively fixed to a holding shelf 132 provided inside an opening 131 on the sound radiation side of a cylindrical frame 13 coaxial with the diaphragm 11, from the rear side of the diaphragm 11 opposite the sound radiation side. In this diaphragm 11, the edge portion 113 is the portion 11a supported by the frame 13, and the circular dome portion 111 and the cone portion 112 excluding this supported portion 11a are the non-supported portion 11b that can vibrate.

[0018] The driver 12 is a component that vibrates the diaphragm 11 when an audio signal is supplied, thereby generating sound represented by the audio signal in the diaphragm 11. The driver 12 includes a bobbin 121, a voice coil 122, and a drive magnetic field generator 123. The bobbin 121 is a cylindrical member with an opening edge 121a adhesively fixed from the rear side to the boundary between the circular dome portion 111 and the cone portion 112 of the diaphragm 11. The voice coil 122 is a coiled electric wire wound around the bobbin 121 and supplied with an audio signal. The drive magnetic field generator 123 is a magnetic circuit component that houses the voice coil 122 within a cylindrical magnetic gap Ga1 and generates a magnetic field in the magnetic gap Ga1 to vibrate the diaphragm 11 via the bobbin 121 when an audio signal is supplied to the voice coil 122. In this embodiment, the voice coil 122 is wound around the bobbin 121. However, voice coil 122 is not limited to this, and may be provided in a pocket portion provided in diaphragm 11. Specifically, a structure may be provided in which a bottomed, circumferential pocket portion having an opening on the sound emitting side is provided at the boundary between circular dome portion 111 and cone portion 112, and an air-core coil located inside the pocket portion is fixed with an adhesive as voice coil 122.

[0019] The driving magnetic field generator 123 also includes a permanent magnet 123a, a yoke 123b, and a plate 123c. The permanent magnet 123a is a ring-shaped magnet extending around the axis X11. The yoke 123b is a magnetic member having a shape in which a cylindrical portion 123b-2 protrudes in the axial direction D11 from the center of a circular bottom plate 123b-1 centered on the axis X11. The permanent magnet 123a is placed on the surface of the circular bottom plate 123b-1 so that the cylindrical portion 123b-2 passes inside. The plate 123c is a ring-shaped plate made of magnetic material whose inner periphery forms a magnetic gap Ga1 between itself and the cylindrical portion 123b-2, and is disposed so that the permanent magnet 123a is sandwiched between itself and the circular bottom plate 123b-1. The magnetic field from the permanent magnet 123a circulates through the magnetic gap Ga1 and inside the yoke 123b and the plate 123c, which are magnetic materials. The voice coil 122 is exposed to the magnetism in the magnetic gap Ga1, and when an audio signal is supplied, it vibrates the diaphragm 11 via the bobbin 121 due to the Lorentz force.

[0020] In this embodiment, the driving magnetic field generating unit 123 is an external magnetic type magnetic circuit in which the permanent magnet 123a is arranged on the outer periphery of the yoke 123b. However, the driving magnetic field generating unit in the speaker is not limited to this, and may be an internal magnetic type magnetic circuit in which the permanent magnet is arranged inside a ring-shaped yoke.

[0021] The frame 13 is formed in a cylindrical shape from resin and surrounds the diaphragm 11, and as described above, the holding portion 11a (edge ​​portion 113) of the diaphragm 11 is adhesively fixed to the holding shelf 132 provided inside the opening 131 on the sound emission side. The cylindrical frame 13 is also fixed to the plate 123c located on the sound emission side of the driving magnetic field generating unit 123 in the driving unit 12. In this embodiment, the frame 13 is made of resin, but is not limited to this and may be made of a metal compound containing aluminum, zinc, or the like.

[0022] The cover 14 is made of resin, disposed on the sound-emitting side of the diaphragm 11, and fixed to the frame 13. The cover 14 includes an outer peripheral frame 141, a vibration adjustment portion 142, and multiple (three in this embodiment) spokes 143. The outer peripheral frame 141 is a ring-shaped portion fixed to the frame 13. The vibration adjustment portion 142 is disposed facing the circular dome portion 111, which is the center of the diaphragm 11, and adjusts the frequency of the sound emitted by the diaphragm 11. The spokes 143 are three portions extending radially from the vibration adjustment portion 142 to the outer peripheral frame 141. These three spokes 143 extend at equal intervals of 120° in the circumferential direction D13 around the axis X11. Note that, although the cover 14 is made of resin in this embodiment, the material is not limited thereto and the cover 14 may be made of a metal compound containing aluminum, zinc, or the like.

[0023] The protrusion 15 is a portion that protrudes from the cover 14 toward the outer periphery of the non-held portion 11b of the diaphragm 11, excluding the held portion 11a by the frame 13, and interferes with the outer periphery of the non-held portion 11b from the sound radiation side. As described above, the non-held portion 11b is the circular dome portion 111 and the cone portion 112 excluding the edge portion 113, and the protrusion 15 interferes with the outer periphery of this non-held portion 11b, specifically the outer periphery apex 112a of the cone portion 112, from the sound radiation side. The protrusion 15 is a portion that is integrally formed with the cover 14 from resin, and is a portion that protrudes from the cover 14 toward the outer periphery apex 112a of the cone portion 112. The protrusion 15 interferes with the outer periphery apex 112a of the cone portion 112 so as to bite into it. Furthermore, the protrusions 15 interfere with the outer circumferential apex 112a by a predetermined width in the circumferential direction D13, and are dispersedly arranged in a plurality of locations (three in this embodiment) by being shifted in position in at least one of the circumferential direction D13 and the radial direction D12 (only the circumferential direction D13 in this embodiment). The dispersed arrangement here is achieved by having the base portion of each of the three spokes 143 on the outer circumferential frame 141 side protrude by a spoke width W11 (FIG. 2) to form the protrusions 15, resulting in three locations equally spaced at 120° intervals in the circumferential direction D13.

[0024] Next, a comparative example will be described in comparison with the speaker 1 of the embodiment described above.

[0025] Fig. 7 is an enlarged view of a comparative example to the speakers shown in Figs. 1 to 6, showing a local cross section equivalent to that of Fig. 4. Fig. 8 is an enlarged perspective view of the comparative example shown in the local cross section of Fig. 7, showing a local cut section equivalent to that of Fig. 6. Note that in Figs. 7 and 8, components equivalent to those shown in Figs. 4 and 6 are designated by the same reference numerals as in Figs. 4 and 6, and only those components necessary for explanation are shown. Further, below, redundant explanations of these equivalent components will be omitted.

[0026] 7 and 8 , the speaker 5 of the comparative example does not have components corresponding to the protrusions 15 in the above-described embodiment at the base of each of the three spokes 143 on the cover 54. Therefore, a gap B51 is formed between the outer periphery of the non-supported portion 11b of the diaphragm 11, whose edge portion 113 is supported by the frame 13, i.e., between the outer periphery apex 112a of the cone portion 112 and the base of the spokes 143. In the speaker 5 of the comparative example, this gap B51 allows the non-supported portion 11b of the diaphragm 11 to vibrate without interference. As a result, a resonance phenomenon such as split resonance occurs, in which the center and outer periphery of the diaphragm 11 do not move in the same way but instead move in a wavy manner. This resonance may result in distortion of the sound from the diaphragm 11.

[0027] In contrast to the above comparative example, in the speaker 1 of the embodiment described with reference to Figures 1 to 6, the protrusions 15 interfere from the sound emission side with the outer periphery of the vibrating non-retained portion 11b of the diaphragm 11, i.e., the outer periphery apex 112a of the cone portion 112. This interference can disperse the resonance in the diaphragm 11, which may distort the sound in the above comparative example, as follows.

[0028] Fig. 9 is a graph showing the frequency characteristics of the sound emitted by the speakers of the comparative examples shown in Fig. 7 and Fig. 8. And Fig. 10 is a graph showing the frequency characteristics of the sound emitted by the speakers of the embodiment shown in Fig. 1 to Fig. 6.

[0029] In both graph G51 of the frequency characteristics of the comparative example shown in Fig. 9 and graph G11 of the frequency characteristics of the example shown in Fig. 10, the horizontal axis represents frequency [Hz] and the vertical axis represents sound pressure level [dB]. Graphs G11 and G51 also depict frequency characteristics L11 and L51 of the sound itself emitted by speakers 1 and 5, frequency characteristics L12 and L52 of second-order distortion components contained in the sound, and frequency characteristics L13 and L53 of third-order distortion components.

[0030] In most cases, the sound emitted by the speakers 1 and 5 is caused by a resonant sound near 15 kHz in the second-order distortion component, which causes a deterioration in sound quality. In the frequency characteristics of the comparative example shown in graph G51 of Fig. 9, a large resonant peak P51 is observed near 15 kHz in the frequency characteristic L52 of the second-order distortion component. In contrast, in the frequency characteristics of the example shown in graph G11 of Fig. 10, the resonant peak P11 near 15 kHz in the frequency characteristic L12 of the second-order distortion component is dispersed and reduced by approximately 10 dB.

[0031] In this way, according to the speaker 1 of the above-described embodiment, the resonance in the diaphragm 11 can be dispersed by interfering with the protrusion 15, thereby reducing the distortion components mixed into the sound from the diaphragm 11 and improving the sound quality.

[0032] In this embodiment, the protrusion 15 is a portion of the cover 14 that protrudes toward the outer periphery of the non-holding portion 11b, i.e., toward the outer periphery apex 112a of the cone portion 112. This configuration reduces manufacturing costs compared to when the protrusion 15 is a separate part.

[0033] In this embodiment, the protrusion 15 bites into and interferes with the outer circumferential apex 112a of the cone portion 112. This configuration can further enhance the effect of dispersing resonance compared to when the protrusion 15 is simply in contact with the outer circumferential apex 112a.

[0034] In this embodiment, the protrusions 15 interfere with the outer periphery apex 112a of the cone portion 112 by a predetermined width in the circumferential direction D13. This configuration makes it possible to disperse resonance while suppressing changes in the vibration characteristics of the diaphragm 11, compared to when the protrusions 15 interfere with the outer periphery of the diaphragm 11 over the entire circumference.

[0035] In this embodiment, three protrusions 15 having a predetermined width are disposed in a dispersed manner with their positions shifted in the circumferential direction D13. With this configuration, the displacement of the three protrusions 15 can further enhance the effect of dispersing resonance.

[0036] Furthermore, in this embodiment, the above-described configuration in which three protrusions 15 are dispersedly arranged is adopted as follows. First, the cover 14 has an outer peripheral frame 141, a central vibration adjustment portion 142, and three spokes 143. The protrusions 15 have a shape in which the base portion of each of the three spokes 143 on the outer peripheral frame 141 side protrudes by a spoke width W11. With this configuration, using the three spokes 143 makes it easy to form the protrusion shape of the protrusions 15 on the cover 14, thereby reducing manufacturing costs.

[0037] The present invention is not limited to the above-described embodiment, but includes other configurations that can achieve the object of the present invention, and the following modifications are also included in the present invention.

[0038] For example, in the above-described embodiment, the speaker 1 is exemplified as a tweeter speaker used to reproduce high-frequency sounds. However, the speaker is not limited to this, and may be a woofer speaker used to reproduce low-frequency sounds, and any specific speaker type is not required.

[0039] Furthermore, in the above-described embodiment, the speaker 1 is exemplified as an example of a speaker in which the diaphragm 11 has a circular dome portion 111 and a cone portion 112, and the voice coil 122 drives both the circular dome portion 111 and the cone portion 112 together via the bobbin 121. However, the speaker is not limited to this, and may be a dome-type speaker in which a voice coil drives a dome-shaped diaphragm, or a cone-type speaker in which a voice coil drives a cone-shaped diaphragm. The speaker may be of any specific type as long as it has a diaphragm that emits sound.

[0040] Furthermore, in the above-described embodiment, an example of a diaphragm is diaphragm 11 that is a single sheet member in which circular dome portion 111, cone portion 112, and edge portion 113 are seamlessly connected. However, the diaphragm is not limited to this, and even if it has a circular dome portion, cone portion, and edge portion, each may be formed separately and the edges may be bonded together, and the specific form of the diaphragm is not limited.

[0041] Furthermore, in the above-described embodiment, speaker 1 is exemplified as an example of a speaker in which edge portion 113, which is the outer edge of diaphragm 11, is adhesively fixed to frame 13. However, the speaker is not limited to this, and as long as the outer edge of the diaphragm is held by the frame, a damping material or cushion may be interposed between the outer edge of the diaphragm and the frame, and the specific manner in which the outer edge of the diaphragm is held is not important.

[0042] In the above-described embodiment, the protrusion 15 formed by protruding a portion of the cover 14 is exemplified as an example of the protrusion. However, the protrusion is not limited to this, and may be formed as a separate component from the cover and adhesively fixed to the cover. Furthermore, the protrusion formed as a separate component may be formed from any material, such as a resin or felt material, different from that of the cover. However, as described above, the protrusion 15 formed by protruding a portion of the cover 14 can reduce manufacturing costs.

[0043] Furthermore, in the above-described embodiment, as an example of a protrusion, protrusion 15 is shown as being inserted into the outer periphery of non-retained portion 11b of diaphragm 11, i.e., protrusion 15 is shown as being inserted into the outer periphery of cone portion 112, i.e., the outer periphery apex 112a of cone portion 112. However, the protrusion is not limited to this, and may be inserted into the outer periphery of non-retained portion 11b of diaphragm 11, i.e., the outer periphery apex 112a of cone portion 112, by simply contacting the outer periphery of non-retained portion 11b of diaphragm 11. However, as described above, by inserting protrusion 15 into the outer periphery of non-retained portion 11b of diaphragm 11, the effect of dispersing resonance can be further enhanced. Note that the amount of insertion of the protrusion can be appropriately set depending on the frequency characteristics of the sound generated by the diaphragm, etc.

[0044] Furthermore, in the above-described embodiment, as an example of a protrusion, protrusion 15 that interferes with the outer periphery of non-retained portion 11b of diaphragm 11 at a predetermined width in circumferential direction D13 is exemplified. However, the protrusion is not limited to this, and may interfere over the entire outer periphery of the non-retained portion of the diaphragm. However, as described above, protrusion 15 that interferes locally at a predetermined width can disperse resonance while suppressing changes in the vibration characteristics of diaphragm 11.

[0045] In the above-described embodiment, three protrusions 15 are illustrated as an example of the protrusions, which are arranged in a dispersed manner at equal intervals of 120° in the circumferential direction D13. However, the number of protrusions is not limited to this, and protrusions may be arranged in only one location and cause interference only at that location. However, as described above, three dispersed protrusions 15 as described above can further enhance the resonance dispersion effect. Note that even if multiple protrusions are arranged in a dispersed manner, as long as the multiple protrusions are arranged in a dispersed manner with their positions shifted in at least one of the circumferential direction and the radial direction, they may be arranged only in the radial direction, or may be arranged in both the circumferential direction and the radial direction. Furthermore, the number of dispersed protrusions is not limited to three, and any number of plural protrusions may be used. Furthermore, the dispersed arrangement is not limited to being equally spaced, and may be arranged at random intervals.

[0046] Furthermore, in the above-described embodiment, the speaker 1 is exemplified as an example of a speaker, in which the cover 14 includes an outer peripheral frame 141, a central vibration adjustment unit 142, and three spokes 143, and the protrusions 15 are provided by protruding the base portions of each spoke 143. However, the speaker is not limited to this, and the cover may not include a vibration adjustment unit or spokes facing the center of the diaphragm. Furthermore, the protrusions may be provided at any position on the outer peripheral frame where no spokes are provided, or at any position on the outer peripheral frame other than the spokes if spokes are provided. However, as described above, by providing the protrusions 15 by protruding the base portions of the spokes 143 extending from the vibration adjustment unit 142 on the outer peripheral frame 141 side, the manufacturing costs of providing the protrusions 15 on the cover 14 can be reduced.

[0047] 1, 5 Speaker 11 Diaphragm 11a Holding portion 11b Non-holding portion 12 Drive portion 13 Frame 14, 54 Cover 15 Protrusion 111 Circular dome portion 112 Cone portion 112a Outer periphery top portion 113 Edge portion 121 Bobbin 121a Opening edge 122 Voice coil 123 Drive magnetic field generating portion 123a Permanent magnet 123b Yoke 123b-1 Circular bottom plate 123b-2 Cylindrical portion 123c Plate 131 Opening 132 Holding shelf 141 Outer periphery frame 142 Vibration adjustment portion 143 Spoke B51 Gap D11 Axial direction D12 Radial direction D13 Circumferential direction G11, G51 Graph L11, L12, L13, L51, L52, L53 Frequency characteristics Ga1 Magnetic gap W11 Spoke width X11 Axis

Claims

1. A speaker comprising: a diaphragm; a frame that holds the outer edge of the diaphragm from the back side opposite the sound emitting side; a cover that is disposed on the sound emitting side of the diaphragm and fixed to the frame; and a protrusion that protrudes from the cover towards the outer periphery of the non-held portion of the diaphragm excluding the portion held by the frame, and interferes with the outer periphery of the non-held portion from the sound emitting side.

2. The speaker according to claim 1, wherein the protrusion is a portion of the cover that protrudes toward the outer periphery of the non-holding portion.

3. The speaker according to claim 1, wherein the protrusions are arranged to bite into and interfere with the outer periphery of the non-retaining portion.

4. The speaker according to claim 1, wherein the protrusion interferes with the outer periphery of the non-retaining portion by a predetermined width in the circumferential direction.

5. The speaker according to claim 4, wherein a plurality of said protrusions of said predetermined width are dispersed and arranged at positions offset in at least one of the circumferential direction and the radial direction of said non-holding portion.

6. A speaker as described in claim 5, characterized in that the cover has an outer peripheral frame fixed to the frame, a vibration adjustment unit arranged facing the center of the diaphragm to adjust the vibration frequency of the sound emitted by the diaphragm, and a plurality of spokes extending radially from the vibration adjustment unit to the outer peripheral frame, and the protrusions have a shape in which the base portion of each of the plurality of spokes on the outer peripheral frame side protrudes by the width of the spoke.

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