CN112492458A

CN112492458A - Diaphragm, speaker unit and earphone or earplug

Info

Publication number: CN112492458A
Application number: CN202010934534.7A
Authority: CN
Inventors: 藤谷武士
Original assignee: Onkyo Corp
Current assignee: Onkyo Corp
Priority date: 2019-09-11
Filing date: 2020-09-08
Publication date: 2021-03-12
Also published as: JP2021044685A

Abstract

The present disclosure relates to a diaphragm, a speaker unit, and an earphone or an earplug, wherein a dome portion whose radial cross section is convex is constituted by molding a sheet-like member or a film-like member, the diaphragm comprising: a plurality of convex ribs or concave ribs formed in a rotationally symmetrical manner at the dome portion, wherein the plurality of convex ribs or concave ribs extend with a center point as a starting point and are spiral in a radial direction, and the shape of the convex ribs or concave ribs is determined by using the following formula 1A function of a recurrence formula is defined, the formula being derived by adding the first term and the second term. Equation 1: a is₁＝a₂＝1，a_n+2＝a_n+1+a_nAnd n is an integer of not less than 1.

Description

Diaphragm, speaker unit and earphone or earplug

Technical Field

The present disclosure relates to a diaphragm of a dynamic speaker unit used in earphones and earplugs that are mounted on ears of a user and reproduce audio.

Background

In small dynamic speaker units used in earphones and earplugs, there are cases where such a diaphragm is used: the dome portion and the edge portion extending in the circumferential direction of the dome portion are integrally formed by forming a film-like member made of a resin such as PET (polyethylene terephthalate) or PEI (polyetherimide). In the dynamic speaker, a voice coil that supplies an audio signal current from the rear surface side is mounted at a coupling portion of a center dome portion and an edge portion of an integrally configured diaphragm. The circumferential end side of the edge portion of the diaphragm is fixed at a frame connected with a small and light magnetic circuit, and the coil of the voice coil is arranged at the magnetic cavity of the magnetic circuit.

The shape of the diaphragm affects the quality and sound pressure frequency characteristics of the audio reproduced by the dynamic speaker unit. In particular, in a film in which a dome portion and an edge portion are integrally formed, there are many film shapes: by providing a plurality of ribs (protrusions or grooves) at the convex (dome-shaped) dome portion and the convex (roll-shaped) edge portion, respectively, and giving strength to the dome portion, it is attempted to adjust the vibration characteristics of the edge portion which vibrates and deforms up and down. In addition, there are many such membrane shapes: by focusing on the shapes of the dome portion and the edge portion and the arrangement of the ribs, it is attempted to improve acoustic characteristics including flattening of sound pressure frequency characteristics and the like.

For example, conventionally, there is a speaker diaphragm in which a plurality of ribs located between an inner peripheral edge and an outer peripheral edge are formed without contact at equal intervals along a curve from the inner peripheral edge (JP S57-200996U). There is a case where the edge portion of the rib having a plurality of oblique directions shown in fig. 1 or fig. 2 of JP S57-200996U is referred to as a tangential edge.

The cross-section of these ribs shown in fig. 2 or fig. 4 of JP S57-200996U is bent so that corners are provided in straight lines on the base material and the edge portions of the film sheet are bent at acute angles in the ribs. When the diaphragm vibrates up and down and the mobility of the edge portion in the upward direction and the downward direction is different (i.e., the displacement symmetry of the edge portion is different and the linearity of the diaphragm is deteriorated), a failure such as rolling of the diaphragm or occurrence of an abnormal sound is liable to occur. When the displacement symmetry of the edge portion is different, even-order distortion of the sound wave propagating from the dynamic speaker unit is increased, and there is a problem that reproduction sound quality is deteriorated.

Further, conventionally, for example, as shown in fig. 13A to 13F of JP 4153934B, a plurality of obliquely-oriented ribs are provided at both the dome portion and the edge portion (JP 4153934B). Alternatively, a rib in an oblique direction is provided at any one of the dome portion and the edge portion. With JP 4153934B, when the diaphragm and the rib are constituted by separate structures, there is a problem that the weight of the vibration system becomes heavy and a reduction in sound pressure is caused.

Disclosure of Invention

According to an aspect of the present disclosure, there is provided a membrane sheet in which a dome portion whose radial cross section is convex is formed by molding a sheet-like member or a film-like member, the membrane sheet comprising: a plurality of convex ribs or concave ribs formed in a rotationally symmetric manner at the dome portion, wherein the plurality of convex ribs or concave ribs extend with a center point as a starting point and are spiral in a radial direction, and the shape of the convex ribs or concave ribs is defined by a function of a recurrence formula using formula 1 below, the formula 1 being obtained by adding a first term and a second term,

equation 1:

a₁＝a₂＝1

a_n+2＝a_n+1+a_n

n is an integer of not less than 1.

Drawings

Fig. 1 is an external view of a dynamic speaker unit used in earphones and earbuds according to one embodiment of the present disclosure.

Fig. 2 is a plan view for describing a shape of a diaphragm according to an embodiment of the present disclosure.

Fig. 3 is a diagram for describing the shape of a spiral rib of a diaphragm according to one embodiment of the present disclosure.

Fig. 4 is a top view of the shapes of a diaphragm according to two embodiments of the present disclosure and a diaphragm of a comparative example.

Fig. 5 is a graph illustrating displacement symmetry of a diaphragm according to the present disclosure.

Fig. 6 is a graph showing sound pressure frequency characteristics of the diaphragm of the present disclosure and the diaphragm of the comparative example.

Fig. 7 is a graph showing sound pressure frequency characteristics of the diaphragm of the present disclosure and the diaphragm of the comparative example.

Fig. 8 is a plan view illustrating the shape of a diaphragm according to three other embodiments of the present disclosure.

Fig. 9 is a graph illustrating sound pressure frequency characteristics of a diaphragm according to another embodiment of the present disclosure.

Fig. 10 is a graph showing sound pressure frequency characteristics of a diaphragm according to another embodiment of the present disclosure and a diaphragm of a comparative example.

Detailed Description

The present disclosure is made to solve the problems of the conventional techniques described above, and an object of the present invention is to provide a speaker unit in which reproduction sound quality is excellent by focusing on shapes of a dome portion and an edge portion and by improving acoustic characteristics (including flattening sound pressure frequency characteristics with respect to a diaphragm of an electrodynamic speaker unit).

A diaphragm, a speaker unit using the diaphragm, an earphone, and an earbud according to preferred embodiments of the present disclosure are described below. However, the present disclosure is not limited to these embodiments.

(embodiment mode 1)

Fig. 1 is a diagram for describing a dynamic speaker unit 1 used in earphones and earbuds according to a preferred embodiment of the present disclosure. Specifically, fig. 1 is a perspective view showing the appearance of the speaker unit 1 from the front. Fig. 2 is a plan view, in which a part of the diaphragm 10 of the speaker unit 1 is enlarged to describe its shape. The embodiment of the speaker unit 1 is not limited to the case of this embodiment. Further, with respect to the configuration of the speaker unit 1 which is unnecessary for describing the present disclosure, illustration and description are omitted.

The speaker unit 1 of the present embodiment is an electrodynamic speaker in which a nominal diameter used in an earphone placed close to the ear of a user is 40 mm. For example, when the nominal diameter is 35mm to 50mm, the speaker unit 1 is suitable for an earphone. When the nominal diameter is a small diameter (for example, in the case where the nominal diameter is 5mm to 10 mm), the speaker unit 1 is suitable for an earplug. The speaker unit 1 is mounted at a baffle of the earphone or a housing of the ear plug, and constitutes the earphone or the ear plug. The detailed embodiment of the earphone or the ear plug using the speaker unit 1 is not illustrated or described.

The speaker unit 1 includes: a frame 2 formed of a resin material; a magnetic circuit 3 (not shown) fixed at the frame 2; a film 10 formed of a PEEK laminated film; a voice coil (not shown) which is engaged with the diaphragm 10 and in which a coil is arranged in a magnetic cavity (not shown) of the magnetic circuit 3 (not shown); terminals (not shown) connecting both ends of the coil of the voice coil; and a braking member (not shown) which is installed at the frame 2 and through which the acoustic wave propagated from the diaphragm 10 passes. In fig. 1, the magnetic circuit 3, the voice coil, and the stopper member covering the opening, described later, of the frame 2 are hidden by being positioned on the rear surface side of the diaphragm 10, and therefore are not visible from the external appearance of the speaker unit 1.

The diaphragm 10 is a diaphragm integrally formed of a dome portion 11 which is a part of a spherical surface and an edge portion 12 extending on the outer periphery of the dome portion 11. In the diaphragm 10, a voice coil that supplies an audio signal current from the rear surface side is mounted at a coupling portion of the dome portion 11 and an edge portion 12 that is an outer peripheral portion of the dome portion 11. The outer peripheral edge side of the edge portion 12 of the diaphragm 10 is fixed at a diaphragm fixing portion 21 of the frame 2, and the small and light magnetic circuit 3 is fixed at a magnetic circuit fixing portion 22 (not shown) of the frame 2. The magnetic circuit fixing portion 22 is provided inside with an opening communicating with the magnetic cavity of the magnetic circuit 3 and through which the voice coil passes. The coil of the voice coil coupled to the diaphragm 10 is arranged in the magnetic cavity of the magnetic circuit 3.

Therefore, in the speaker unit 1, when an audio signal current is supplied to the voice coil disposed in the magnetic cavity of the magnetic circuit 3 generating a strong direct-current magnetic field, a driving force is generated in the illustrated Z-axis direction, and the speaker vibration system constituted by the voice coil and the diaphragm 10 vibrates in the Z-axis direction. That is, the speaker vibration system is vibratably supported only by the edge portion 12 of the diaphragm 10. As a result, pressure variations are generated in the air existing in front and rear of the diaphragm 10, and the audio signal current is converted into sound waves (audio).

The frame 2 has: a substantially annular membrane fixing portion 21 that fixes an outer peripheral portion of the edge portion 12 of the membrane 10; a substantially annular magnetic path fixing portion 22 for fixing the magnetic path 3; a coupling portion 23 (not shown) that couples the diaphragm fixing portion 21 and the magnetic circuit fixing portion 22 and defines a plurality of openings (not shown); and a terminal fixing portion (not shown) that fixes the terminal. The frame 2 mounts the diaphragm 10 on the front surface side such that the dome portion 11 and the edge portion 12 of the diaphragm 10 are exposed, and is configured such that an acoustic wave propagating from the front surface side of the diaphragm 10 is reproduced.

Further, with respect to the acoustic wave propagating from the rear surface side of the diaphragm 10 being in an inverse relationship with the acoustic wave propagating from the front surface side of the diaphragm 10, the frame 2 is configured such that the acoustic wave from the edge portion 12 is reproduced to the rear surface side via a plurality of openings (not shown) defined by the coupling portions 23. A braking member (not shown) having air permeability may be installed at the coupling portion 23 to cover the opening. In the speaker unit 1, the compliance (acoustic capacity) caused by the internal space of the frame 2 can be adjusted by means of the opening and the stopper member so as to be suitable for the earphone or the earplug, and the frequency characteristics, particularly the frequency characteristics of the low-frequency band, can be adjusted by adjusting the compliance.

The frame 2 is formed of a resin material including a polyphenylene ether-based resin, a polystyrene resin, and at least one polyolefin resin selected from the group consisting of polyethylene, polypropylene, and an ethylene-propylene copolymer. The weight ratio of the polyphenylene ether-based resin and the polystyrene resin is preferably in the range of 90/10 to 70/30, and the polyolefin resin is preferably included in an amount of 5 to 20 parts by weight, relative to 100 parts by weight of the total amount of the polyphenylene ether-based resin and the polystyrene resin. The polyphenylene ether-based resin and the polystyrene resin may be alloyed.

By using the above resin material, the frame 2 of the present embodiment can have a high internal loss and excellent mechanical properties in good balance, and can have light and excellent heat resistance and a signal-to-noise (S/N) ratio. In more detail, by including a polyphenylene ether-based resin, a polystyrene resin, and a polyolefin resin in a specific ratio, it is possible to obtain a frame 2 having a particularly high internal loss and excellent mechanical properties in good balance and having excellent vibration characteristics without losing the excellent heat resistance, moisture resistance, moldability, dimensional stability, and lightweight properties that the resins originally have.

The membrane 10 was molded from a PEEK laminate film (PEEK 9 μm/TPU 15 μm/PEEK 9 μm) member having a thickness of 33 μm. The dome portion 11 of the diaphragm 10 is a dome-shaped diaphragm portion having a convex cross section. The edge portion 12 of the diaphragm 10 is a bead having a convex shape in a radial cross section. As shown in fig. 1 or fig. 2, a plurality of convex spiral ribs 6 are provided at the dome portion 11, and a part of convex surfaces of the convex spiral ribs is convex. The spiral rib 6 of the diaphragm 10 may be a concave rib that recesses a portion of the convex surface.

The spiral rib 6 of the dome portion 11 of the diaphragm 10 extends radially with a set center point O as a starting point and is spiral-shaped. In the

diaphragm

10, 13 ribs are arranged at equal intervals in the circumferential direction. The shape (curved state) of each helical rib 6 is defined by a function using the recurrence formula of formula 1: a fibonacci number series that may be derived by adding the first and second terms.

(formula 1)

a₁＝a₂＝1

a_n+2＝a_n+1+a_n(n: an integer of not less than 1)

For example, a fibonacci number series is a number series that persists {1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, …, … }, which is reported to occur in many natural world phenomena. Specifically, it has been reported that fibonacci series appear in a spiral shape such as an arrangement of seeds of sunflower, a cross-sectional shape of a shell of nautilus, an arrangement of thorns of cactus, and the like. The ratio of adjacent Fibonacci numbers converges to the golden ratio

Fig. 3 is a diagram for describing the shape of the spiral rib. For example, needlesFor the value a of each term of the Fibonacci sequence_nThe set of squares in which squares as one side are arranged in order to be adjacent to each other defines the shape of the spiral rib by connecting arcs connecting two vertexes of the squares with the length of the one side of the square as a radius. Fig. 3 shows a case where each term of the fibonacci sequence has a value of {1, 1, 2, 3, 5, 8, 13 }.

A spiral shape based on a fibonacci sequence may be defined by continuously connecting x-y coordinates discretely defined by the functions of equation 2.

(formula 2)

(b: optional constant, m: parameter (natural number),

golden ratio ═ 1+ sqrt (5)]/2(＝1.618…))

The shape of the spiral shape of each of the plurality of convex ribs 6 of the diaphragm 10 is determined by formula 1 and formula 2. That is, the shape of the spiral of the bionic (biomimetic) is determined based on the fibonacci number series. The spiral rib 6 of the diaphragm 10 is a rib in the case where the shape is defined by setting the value "b" of the formula 2 to "0.03".

A plurality of spiral-shaped convex ribs or concave ribs may be provided not only at the dome portion 11 but also at the edge portion 12. In the diaphragm 10 of the present embodiment, not only the convex spiral rib 6 but also the concave spiral rib 14(16) are provided at the dome portion 11 and the edge portion 12. In the present embodiment, although the annular edge portion 12 having a convex cross section is integrally constituted with the dome portion 11 on the outer diameter side of the dome portion 11 by molding a sheet-like member or a film-like member, the edge portion 12 constituted by a different member may be connected to the outer diameter side of the dome portion 11.

Further, a plurality of concave ribs 13 formed by recessing the convex surface are provided at the edge portion 12. The plurality of reentrant ribs 13 include: a first rib 14(16) which is a spiral rib arranged like a tangential rib; and a second rib 15 which is an inclined rib and is arranged at the edge portion 12 in a rotationally symmetrical manner. Thirty second ribs 15 and five first ribs 14(16) as the concave ribs 13 are provided at the edge portion 12 of the diaphragm 10 of the present embodiment. Although the first ribs 14(16) of the present embodiment are spiral ribs, the first ribs 14 may be straight ribs.

Each of the concave first ribs 14 is formed by recessing the convex surface of the edge portion 12 such that the first rib 14 is along a first prescribed line T1 which intersects a first radial line R1 passing through the center point O at an angle θ of 45 degrees. The first radial line R1 is an imaginary line passing through the vicinity of the substantial center of the first rib 14. For example, as shown in fig. 2, the first rib 14 is formed as a groove in which a convex surface of the edge portion 12, which is separated from the center point O by a predetermined distance along the first radial line R1, is recessed along a first prescribed line T1 that intersects at an angle θ of 45 degrees.

The first predetermined line T1 defining the first rib 14 is also a tangent to a concentric circle having the center point O as its center. That is, the first predetermined line T1 is a tangent to a concentric circle intersecting the illustrated radial line R0 having an angle θ of 45 degrees at an angle θ of 90 degrees. Thus, the first ribs 14 along the first prescribed line T1 form tangential ribs of the rim portion 12.

Further, as shown in fig. 2, the other first rib 14 is formed as a groove in which a convex surface of the edge portion 12 separated from the center point O by a predetermined distance along a first radial line shown is recessed along a first prescribed line intersecting at an angle θ of 45 degrees. These first ribs 14 are concave ribs which are replicated by rotating the first ribs 14 intersecting the X axis by 72 degrees about the center point O. Similarly, in the diaphragm 10, two first ribs 14 intersecting with the X axis or the Y axis are also arranged so that the two first ribs 14 are duplicated in a rotationally symmetrical manner. As a result, a total of five first ribs 14 are arranged at an angle of 72 degrees from the center point O in a rotationally symmetrical manner.

Further, the concave second ribs 15 are formed by recessing the convex surface of the edge portion 12 such that the second ribs 15 follow a second prescribed line intersecting a second radial line passing through the center point O. The second radial line is an imaginary line passing through the vicinity of the substantial center of the second rib 15. For example, as shown in fig. 2, the second rib 15a arranged in the vicinity of the first rib 14 intersecting the X-axis and at a position not intersecting the first rib 14 is formed as a groove in which a convex surface of the edge portion 12 separated from the center point O by a predetermined distance along a second radial line Ra passing through the center point O is angled

A second prescribed line Ta intersecting the line is recessed.

Therefore, the second predetermined line Ta defining the second rib 15a is not a tangent to a concentric circle centered on the center point O, but has a relationship: the second prescribed line Ta is inclined with respect to the first prescribed line T1 defining the first rib 14 adjacent thereto, and intersects the first prescribed line T1. Therefore, the second ribs 15a along the second prescribed line Ta do not form tangential ribs of the edge portion 12, and form inclined ribs that do not intersect the first ribs 14.

Next, as shown in fig. 2, another second rib 15b is arranged at a position where the second rib 15b is adjacent to the second rib 15a as an inclined rib. Specifically, the second ribs 15b are arranged such that the second ribs 15a are respectively duplicated in a rotationally symmetric manner from the center point O at intervals of a constant angle λ. Similarly, the other second ribs 15c to 15f are respectively arranged such that the second ribs 15a are respectively duplicated in a rotationally symmetric manner from the center point O at intervals of a constant angle λ. As a result, the second ribs 15a to 15f form a rib group composed of six second ribs. The rib group (second ribs 15a to 15f) is arranged between the first rib 14 and the other first rib 14 at a position intersecting the above-described X axis.

In the diaphragm 10 of the present embodiment, five pairs of rib groups constituted by the six second ribs 15 are arranged such that the rib groups are duplicated in a rotationally symmetrical manner at an angle of 72 degrees from the center point O. Therefore, in one circumference of the rim portion 12, the rib groups of the first ribs 14(16) which are spiral ribs like one tangential rib and the second ribs 15 which are constituted by six oblique ribs are arranged so that five pairs constituted by the first ribs 14(16) and the rib groups appear in order.

As a result, as described above, in the edge portion 12 of the film 10 of the present embodiment, the five first ribs 14(16) and the thirty second ribs 15 as the concave ribs 13 are arranged so as to include portions where the existing density of the concave ribs 13 per unit area is high and portions where it is low. Therefore, the rigidity and strength of the edge portion 12 become uneven and the resonance frequency is dispersed. The concave ribs 13 of the edge portion 12 improve the displacement symmetry of the diaphragm 10, prevent failures such as rolling of the diaphragm 10 or occurrence of abnormal sounds, and improve the reproduction sound quality. In the case of the present embodiment, without being limited thereto, a decrease in the peak value of the sound pressure frequency characteristic is suppressed, and the reproduction sound quality may be excellent.

The length and depth of each of the first and

second ribs

14 and 15 may be appropriately defined based on the shape of the edge portion 12. That is, the depth from the convex surface of the edge portion 12 of the concave rib 13 is changed so that the depth at the center position of the edge portion 12 is different from the depth at a position close to the inner peripheral side edge portion or the outer peripheral side edge portion of the edge portion 12. The concave ribs 13 are provided as elongated groove portions at portions other than both edge portions of the convex edge portion 12. The inner edge of the concave rib 13 does not reach the connection portion with the edge portion 12 (the outer peripheral portion of the crown portion 11), and the outer edge of the concave rib 13 does not reach the flat surface portion of the film fixing portion 21 fixed to the frame 2.

Fig. 4 is a graph showing the displacement symmetry in the Z-axis direction of the diaphragm 10 of the present embodiment. The horizontal axis shows a value (%) normalizing the driving force applied to the position of the voice coil to which the diaphragm 10 is mounted, the vertical axis shows an absolute value of a displacement amount (displacement [ mm ]) of the Z-axis direction of the diaphragm with respect to the driving force, and fig. 4 is a graph of an upward direction (upper: solid line, front surface direction) and a downward direction (lower: dotted line, rear surface direction) of rewriting. In the case of an ideal diaphragm in which the displacement symmetry in the Z-axis direction of the edge portion 12 is excellent, the characteristic curve in the upward direction and the characteristic curve in the downward direction do not separate and are close to and substantially matched.

When referring to the graph of fig. 4, in the diaphragm 10 of the present embodiment, the characteristic curve in the upward direction and the characteristic curve in the downward direction are very close, and the displacement symmetry in the Z-axis direction of the edge portion 12 is excellent. Therefore, the dynamic speaker unit 1 using the diaphragm 10 can suppress the occurrence of abnormal sound by rolling the speaker vibration system including the voice coil, the diaphragm 10, and the like. When the displacement symmetry in the Z-axis direction of the diaphragm 10 is excellent, the displacement symmetry approaches a direction in which the amounts of discharged air are equal when the absolute values of the displacements in the upward direction and the downward direction of the diaphragm 10 are equal. Therefore, occurrence of even-order distortion is suppressed, and reproduction sound quality can be excellent.

Fig. 5 is a graph showing the sound pressure frequency characteristics of the diaphragm 10 of the present embodiment and the diaphragm 100 of the comparative example. The horizontal axis shows the frequency of the input audio signal (10Hz to 100kHz), and the vertical axis shows the reproduced sound pressure level. In the case of the diaphragm 10 of the present embodiment, the peak dip occurring in about 3k to 30kHz when the diaphragm 100 of the comparative example is employed is suppressed. Therefore, according to the dynamic speaker unit 1 using the diaphragm 10 of the present embodiment, the reproduced sound quality of the headphone or the earplug including the diaphragm can be improved.

Fig. 6 is a plan view showing the shape of each of the

other membranes

10a and 10b of the present embodiment and the membrane 100 of the comparative example. In the diaphragm 10a, similarly to the above-described diaphragm 10, thirteen spiral ribs 6a are arranged at the dome portion 11 by setting the value "b" in the formula 2 to "0.03". Further, the diaphragm 10b is different from the above-described diaphragm 10, and by setting the value "b" in the formula 2 to "0.005", four spiral ribs 6b are arranged at the dome portion 11. On the other hand, the spiral rib 6 is not provided at the dome portion 11 of the diaphragm 100 of the comparative example.

Further, rib groups of the first rib 14 as one tangential rib and the second rib 15 composed of nine inclined ribs are arranged at the edge portions 12 of the

diaphragm

10a and 10b and the edge portion 12 of the diaphragm 100 of the comparative example, respectively, so that four pairs of the first rib 14 and the rib groups appear in order. That is, in the case where the above-described diaphragm 10 includes the spiral rib 16 at the edge portion 12, the diaphragm 10 is different from the diaphragm 10a, the diaphragm 10b, and the diaphragm 100 of the comparative example in that the diaphragm 10a, the diaphragm 10b, and the diaphragm 100 of the comparative example do not include the spiral rib at the edge portion 12, and the other settings are the same.

Fig. 7 is a graph showing the sound pressure frequency characteristics of the

diaphragms

10a and 10b of the present embodiment and the diaphragm 100 of the comparative example, similarly to the graph of fig. 5. In the case of the

diaphragms

10a and 10b, the peak dip occurring in about 3k to 30kHz with the diaphragm 100 of the comparative example was suppressed. Therefore, by the dynamic speaker unit 1 using the

diaphragms

10a and 10b of the present embodiment, the reproduced sound quality of the earphone or the earplug including the speaker unit 1 can be excellent.

In the case of an earphone (not shown) including the dynamic speaker unit 1 using the

diaphragms

10, 10a, and 10b of the present embodiment, as a result of comparison with the sense of hearing, it can be confirmed that the reproduction sound quality of the earphone of the present embodiment is more excellent than that of the earphone of the comparative example. In the case of the present embodiment, since the dome portion 11 includes the convex spiral rib imitating natural, the strength of the dome portion 12 of the diaphragm 10 is reinforced, and an effect of dispersing resonance in the bass range can be brought about. Further, it is possible to suppress the occurrence of unnecessary sound waves such as abnormal sounds caused by the rolling of the diaphragm 10 of the dynamic speaker unit 1. The dynamic loudspeaker unit 1 using the membrane 10 may be used in an ear plug (not shown) having a housing supported directly on the ear of the user.

Fig. 8 is a plan view showing the shapes of the

diaphragms

10c, 10d, and 10e of other embodiments. Further, each of fig. 9 and 10 is a graph showing a sound pressure frequency characteristic. In the

diaphragms

10c, 10d, and 10e of these embodiments, the shape and arrangement of the spiral rib 6 arranged at the dome portion 11 and the spiral rib 16 arranged at the edge portion 12 are different from those of the diaphragm 10 of the present embodiment, and other settings are the same.

Similarly to the above-described diaphragm 10b, by setting the value "b" in the formula 2 to "0.005", four spiral ribs 6c are arranged at the dome portion 11 of the diaphragm 10c shown in (a) of fig. 8. Further, by setting the value "b" in the formula 2 to "0.005", five concavely spiral-shaped ribs 16c are arranged at the edge portion 12 in a rotationally symmetrical manner.

Further, by setting the value "b" in the formula 2 to "0.005", five spiral ribs 6d are arranged at the dome portion 11 of the diaphragm 10d shown in (b) of fig. 8. Further, by setting the value "b" in the formula 2 to "0.005", eight concavely spiral ribs 16d are arranged in a rotationally symmetrical manner at the edge portion 12.

In addition, in the diaphragm 10e shown in fig. 8 (c), the configuration of the spiral rib 6e arranged at the dome portion 11 is different from the above-described diaphragm 10 b. That is, in the spiral rib 6e, similarly to the above-described diaphragm 10b, four spiral ribs 6b are arranged by setting the value "b" in the formula 2 to "0.005", and four spiral ribs 6b are additionally added, which are inverted, so that eight spiral ribs are arranged in total. At the edge portion 12 of the membrane 10e, the same concave ribs 13 as those at the edge portion 12 of the membrane 10b are arranged.

When referring to the graphs of fig. 9 and 10, in the

diaphragms

10c, 10d, and 10e, similarly to the

diaphragms

10 and 10b, the rigidity and strength of the dome portion 11 and the edge portion 12 become uneven and the resonance frequency is dispersed as compared with the diaphragm 100 of the comparative example. As a result, a decrease in the peak value of the sound pressure frequency characteristic is suppressed, and the reproduction sound quality can be excellent. The electrodynamic speaker unit 1 using the

diaphragms

10c, 10d, and 10e can suppress the occurrence of abnormal sounds caused by rolling of the speaker vibration system including the voice coil and the diaphragm 10, as compared with the diaphragm 100 of the comparative example.

As the above-described embodiment, as the recessed rib 13 in the edge portion 12, the first rib 14 (tangential rib) and the second rib 15 may be at least arranged so as not to intersect but to be adjacent. The first ribs 14, which are tangential ribs, may be along a first prescribed line intersecting a first radial line passing through the center point at 45 degrees, and the second ribs 15 may be along a second prescribed line intersecting a second radial line at a predetermined number of degrees less than 45 degrees. Further, the rib groups formed so that the first ribs 14 and the second ribs 15 are adjacent may be arranged so that the rib groups alternately appear in one turn of the edge portion 12.

The resin material constituting the membrane 10 is not limited to a laminated film-like member of PEEK (polyetheretherketone). For example, the material forming the membrane 10 may be a light resin material film (one formed by hot-pressing a sheet or one formed by press-molding an elastomer sheet), such as another film of PET (polyethylene terephthalate), PEI (polyetherimide), PEN (polyethylene naphthalate), PC (polycarbonate), PI (polyimide), PAR (polyarylate), PPS (polyphenylene sulfide), or the like. Further, the material forming the film 10 may be a nonwoven fabric made of natural fibers such as cellulose or the like or synthetic fibers or a paper material. The membrane 10 may be a membrane laminated with multiple materials. For example, when resin films such as PEEK, PEI, PET, PEN are laminated, an elastomer sheet or an adhesive layer may be sandwiched between the resin films as an intermediate layer.

The diaphragm 10 can be operated to constitute an assembly portion of a speaker vibration system of the dynamic speaker unit 1 by connecting the voice coil 3 to a voice coil mounting portion defined at an outer peripheral portion of the dome portion 11. The dimension of the curved surface in which the ridge line portion including the spiral rib 6 or the concave rib 13 is chamfered can be changed in the shape and size of each of the dome portion 11 and the edge portion 12 in accordance with the dimension of the diameter of the voice coil 3 and the dimension of the thickness of the resin material constituting the diaphragm 10.

Further, in the diaphragm 10, the dome portion 11 may be constituted by a member different from the edge portion 12, and connected to the center side of the edge portion 12. That is, the dome portion 11 composed of a member different from the sheet-like member or the film-like member constituting the edge portion 12 having a convex shape in the radial cross section may be connected to the center side of the edge portion 12.

Although the frame 2 of the present embodiment can have well-balanced high internal loss and excellent mechanical characteristics, and is light and has excellent heat resistance and signal-to-noise ratio by using a resin material including the polyphenylene ether-based resin, the polystyrene resin, and the polyolefin resin in a specific ratio as described above, the frame 2 may be made of other resin materials or metal materials in different ratios.

The diaphragm of the present disclosure is not limited to the electrodynamic speaker unit shown, and may be a speaker unit that further includes a damper and constitutes a speaker vibration system. The diaphragm is not limited to the dynamic speaker unit, and may be applied to a piezoelectric speaker unit.

Cross Reference to Related Applications

The present application claims priority from japanese application No. 2019-165002, filed on 11.9.2019, the entire contents of which are incorporated herein by reference.

Claims

1. A membrane sheet in which a dome portion having a convex radial cross section is formed by molding a sheet-like member or a film-like member, comprising:

a plurality of convex ribs or concave ribs formed in a rotationally symmetrical manner at the dome portion,

wherein the plurality of convex ribs or concave ribs extend with a center point as a starting point and are spiral in a radial direction, and the shape of the convex ribs or concave ribs is defined by a function of a recurrence formula using formula 1 below, the formula 1 being obtained by adding a former first term and a former second term,

equation 1:

a₁＝a₂＝1

a_n+2＝a_n+1+a_n

n is an integer of not less than 1.

2. The diaphragm according to claim 1, wherein said diaphragm is a single-layer diaphragm,

the value a for each term of the array defined by said equation 1_nThe shape of the convex rib or the concave rib is defined by a set of squares in which squares having one side are arranged in order to be adjacent to each other, and arcs connecting two vertexes of the squares with the length of the one side of each of the squares as a radius are continuously connected.

3. The diaphragm according to claim 1, wherein said diaphragm is a single-layer diaphragm,

wherein the shape of the convex rib or the concave rib is defined by continuously connecting x-y coordinates discretely defined by a function of the following equation 2,

equation 2:

b is an optional constant, m is a natural number parameter,

is the golden ratio [1+ sqrt (5)]/2(＝1.618…)。

4. The diaphragm according to claim 1, wherein said diaphragm is a single-layer diaphragm,

wherein an annular edge portion which is formed of a member different from the sheet-like member or the membrane-like member and has a convex radial cross section is connected to an outer diameter side of the dome portion.

5. The diaphragm according to claim 1, wherein said diaphragm is a single-layer diaphragm,

wherein, by molding the sheet-like member or the membrane-like member, an annular edge portion having a convex-shaped radial cross section is integrally formed with the dome portion on the outer diameter side of the dome portion.

6. The diaphragm according to claim 4, wherein said diaphragm is a single-layer diaphragm,

wherein the edge portion includes a plurality of convex ribs or concave ribs formed on the convex surface in a rotationally symmetrical manner, and

the plurality of convex or concave ribs extend in a spiral shape with a center point as a starting point in a radial direction, and the shape of the convex or concave ribs is defined by a function of a recursion formula using the formula 1, the formula 1 being obtained by adding a former first term and a former second term.

7. The diaphragm according to claim 4, wherein said diaphragm is a single-layer diaphragm,

wherein the edge portion includes a plurality of concave ribs formed by recessing the convex surface in a rotationally symmetric manner, and

the plurality of reentrant ribs includes at least:

a first rib disposed along a first prescribed line intersecting a first radial line passing through the center point at an angle of 45 degrees; and

a second rib disposed at a position adjacent to but not intersecting the first rib and disposed along a second prescribed line intersecting a second radial line at a predetermined angle less than 45 degrees.

8. The diaphragm of claim 4, further comprising a voice coil connected to a voice coil mounting portion defined in an outer periphery of the dome portion.

9. A speaker unit, comprising:

the diaphragm of claim 8;

a frame at which an outer peripheral edge portion of an edge portion of the membrane sheet is fixed;

a terminal fixed at the frame and connected with a coil of the voice coil;

a magnetic circuit having a magnetic cavity in which the coil of the voice coil is arranged and fixed at the frame; and

a braking member installed to cover an opening of a window portion of the frame.

10. A headset or earplug comprising the speaker unit according to claim 9.