Electroacoustic transducer and assembly kit for electroacoustic transducer

Abstract

[Problem] To provide an electroacoustic transducer having sufficient characteristics with a simple structure. [Solution] An electroacoustic transducer 1 comprising: a fixed part 10 having at least a coil 12; a vibration part 20 which is disposed inside the coil and vibrates along the axial direction of the coil in response to an input signal; and a support member 30 which is connected to the vibration part and the fixed part and supports the vibration part so as to allow the vibration part to vibrate under tension.

Description

Electroacoustic transducers, electroacoustic transducer assembly kits

[0001] The present invention relates to an electro-acoustic transducer and an assembly kit for the electro-acoustic transducer.

[0002] 2. Description of the Related Art So-called electroacoustic transducers are known that generate sound by vibrating a vibrating part in response to an input signal.

[0003] Previously, for example, a speaker has been disclosed that has a first diaphragm and a second diaphragm that is joined at the outer periphery of the first diaphragm and arranged opposite the first diaphragm, and that extends rearward from the center toward the outer periphery, with a reinforcing member disposed between the first and second diaphragms (see, for example, Patent Document 1).

[0004] Patent No. 7332230

[0005] An object of the present invention is to provide an electroacoustic transducer having a simple structure and sufficient characteristics, and an assembly kit for the electroacoustic transducer.

[0006] The electroacoustic transducer of the present invention comprises a fixed part having at least a coil, a vibrating part arranged inside the coil and vibrating along the axial direction of the coil in response to an input signal, and a support member connected to the vibrating part and the fixed part and supporting the vibrating part so that it can vibrate under tension.

[0007] In addition, the electroacoustic transducer assembly kit of the present invention includes a vibrating part that is inserted inside the coil and vibrates along the axial direction of the coil in response to an input signal, and a support member that is adhered to the vibrating part and the fixed part and supports the vibrating part so that it can vibrate under tension.

[0008] According to the present invention, it is possible to provide an electroacoustic transducer having a simple structure and sufficient characteristics, and an assembly kit for the electroacoustic transducer.

[0009] FIG. 1 is a schematic cross-sectional view showing a first embodiment of an electro-acoustic transducer according to the present invention. FIG. 2 is a graph showing frequency characteristics of the electro-acoustic transducer and electro-acoustic transducers of related art. FIG. 3 is a three-dimensional frequency characteristic graph showing frequency analysis of sound generated when the top surface of the electro-acoustic transducer and electro-acoustic transducers of related art is hammered with a finger. FIG. 1 is a schematic cross-sectional view showing a second embodiment of an electro-acoustic transducer according to the present invention. FIG. 2 is a plan view of a third embodiment and a plan view of a fourth embodiment of an electro-acoustic transducer unit according to the present invention. FIG. 3 is a schematic cross-sectional view showing a fifth embodiment of an electro-acoustic transducer according to the present invention. FIG. 4 is a schematic view showing an electro-acoustic transducer according to the present invention attached to the outer wall of a box and configured as a speaker. FIG. 4 is a schematic cross-sectional view showing an example of an electro-acoustic transducer of related art.

[0010] Hereinafter, embodiments of an electroacoustic transducer according to the present invention will be described with reference to the drawings. In the following description, the axial direction of the electroacoustic transducer 1 will be referred to as the Y direction, and the directions perpendicular to the Y direction will be referred to as the X direction and the Z direction. The surface facing the -Y direction will be referred to as the front, and the surface facing the +Y direction will be referred to as the back.

[0011] Electroacoustic Transducer (1) First, a first embodiment of the electroacoustic transducer of the present invention will be described. Fig. 1 is a cross-sectional view showing a cross section of a portion of an electroacoustic transducer 1 according to the present invention cut out at a predetermined angle, and the electroacoustic transducer 1 is actually a substantially cylindrical member. As shown in Fig. 1, the electroacoustic transducer 1 mainly includes a fixed portion 10, a vibrating portion 20, and a support member 30.

[0012] The fixed portion 10 includes a unit base 11 and a coil 12. The unit base 11 is a substantially annular member that forms the front surface of the electro-acoustic transducer 1. The unit base 11 is made of a non-magnetic material, such as resin, and is formed by resin molding. In this embodiment, the unit base 11 is substantially annular, but any other appropriate structure, such as an elliptical cylindrical or rectangular cylindrical shape, can be used.

[0013] The coil 12 is an annular member and is held on the rear side of the unit base 11. The coil 12 has a hole 12a formed in the center thereof into which the vibrating part 20 is inserted.

[0014] The vibrating section 20 is a member disposed inside the coil 12. The vibrating section 20 vibrates inside the coil 12 along the axial direction of the coil 12 in response to a signal.

[0015] The vibrating section 20 mainly includes a cap yoke 21 , a magnet 22 , a center yoke 23 , and a spacer 24 .

[0016] The cap yoke 21 is a cylindrical member with a bottom that forms the top and side surfaces of the vibrating part 20. The bottom of the cap yoke 21 is exposed on the rear side (+Y side) of the electro-acoustic transducer 1. The opening of the cap yoke 21 faces the unit base 11 with a gap therebetween. The inner diameter of the cap yoke 21 is larger than the outer diameter of the coil 12. As a result, the cap yoke 21 covers part of the outer periphery of the coil 12.

[0017] The magnet 22 is a substantially cylindrical magnet and is disposed inside the cap yoke 21 and the coil 12. The magnet 22 may be connected to the inner bottom surface of the cap yoke 21. The center yoke 23 is a disk-shaped member connected to the lower part of the magnet 22 in the figure. The outer diameter of the magnet 22 is smaller than the inner diameter of the hole 12a of the coil 12. Therefore, the magnet 22, the center yoke 23, and the spacer 24 can move axially (in the Y direction) inside the hole 12a. A Lorentz force is generated between the magnet 22 and the coil 12. As a result, the vibrating part 20 vibrates along the axial direction of the coil 12.

[0018] The support member 30 is a member that supports the vibrating section 20 so that it can vibrate. The support member 30 is, for example, a sheet-like member. The support member 30 may also have a thickness that is so-called a film. The support member 30 is formed of a material with small elastic deformation, such as an organic material. The support member is formed of, for example, a synthetic polymer material. More specifically, the support member 30 is formed of, for example, PET, cellophane, a low-resilience acrylic foam sheet, or silicone rubber. For example, by using silicone rubber for the support member 30, an electro-acoustic transducer 1 that is highly durable and has little change in response to heat generated by the coil 12 can be realized. Furthermore, by using a material that already has adhesive strength on one side, assembly is easy.

[0019] The support member 30 has a shape corresponding to the unit base 11, and is substantially circular in this embodiment. The support member 30 is disposed so as to cover the hole 12a of the coil 12. The support member 30 is also adhered to the coil 12. With this configuration, the front surface of the electro-acoustic transducer 1 is sealed by the support member 30, so that the electro-acoustic transducer 1 can be configured with high dustproof and waterproof properties without using a separate member for sealing.

[0020] The shape of the support member 30 is not limited to the above, and it may be a shape in which part of the hole 11a of the unit base 11 is open. More specifically, for example, the support member 30 may be substantially rectangular. The support member 30 may also be substantially cross-shaped. There may be multiple support members 30, and for example, a cross-shaped support member 30 may be formed by bonding two substantially rectangular support members 30 together and intersecting them at substantially right angles. A configuration in which part of the hole 11a is open can reduce noise when the vibrating unit 20 vibrates.

[0021] The support member 30 is connected to the fixed part 10 and the vibrating part 20. More specifically, the support member 30 is bonded to the coil 12 on its upper surface in the figure. A spacer 24 is connected to the back surface (+Y side surface) of the support member 30. Furthermore, the unit base 11 is connected to the front surface (-Y side surface) of the support member 30. As a result, the support member 30 supports the vibrating part 20 by tension so that it can vibrate.

[0022] Here, an electro-acoustic transducer 1001 according to the related art will be described with reference to FIG. 8 . This electro-acoustic transducer 1001 has a suspension 1030 on its front side. The suspension 1030 is, for example, a disk-shaped metal member having elasticity, and is connected to a vibrating unit 1020 via a spacer 1024. The suspension 1030 in the figure exerts elasticity through a plurality of holes. The vibrating unit 1020 mainly includes a cap yoke 1021, a magnet 1022, and a center yoke 1023, and vibrates in the axial direction of a coil 1012 in response to an input signal. The suspension 1030 also abuts against a flange 1011 a on the front side of a unit base 1011. As a result, the suspension 1030 holds the vibrating unit 1020 in a vibrable manner by its elasticity.

[0023] In contrast, the electroacoustic transducer 1 according to the present invention includes a support member 30 that supports the vibrating section so that it can vibrate under tension, instead of a metal member such as the suspension 1030 that exerts elastic force due to its structure. Metal members are expensive, and require processing to exert elastic force, which increases processing costs. Furthermore, metal members are prone to deformation. In contrast, the electroacoustic transducer 1 according to the present invention can be constructed inexpensively using easy-to-handle components. Furthermore, while metal members are prone to breakage due to corrosion, fatigue, or aging, the support member 30 of the electroacoustic transducer 1 is not made of metal, thereby eliminating failure factors specific to metals. In particular, using silicon for the support member 30 can ensure even greater durability.

[0024] Furthermore, the use of a so-called sheet-like or film-like support member 30 allows the electro-acoustic transducer 1 to be thinner and more compact than a metal member. Furthermore, while a metal member requires connecting members such as screws between the support member 30 and the spacer 1024, the support member 30 can be easily attached to the unit base 11 and the spacer 24 with double-sided tape or adhesive, eliminating the need for special connecting members and allowing the electro-acoustic transducer 1 to be made even thinner. With the thin electro-acoustic transducer 1, the contact point between the support member 30 and the unit base 11 serves as the fulcrum of vibration, and the center of vibration of the vibrating section 20 is relatively close to the fulcrum of vibration, thereby preventing the vibrating section 20 from vibrating in an unintended direction, for example, a direction rotating on the X-Z plane.

[0025] A plurality of electroacoustic transducers 1 may be arranged in a so-called array to form an array speaker. The arrangement may be, for example, arranged vertically and horizontally at predetermined intervals, or arranged in a substantially circular shape. The electroacoustic transducer 1 according to the present invention can be constructed inexpensively, so that a relatively inexpensive array speaker can be realized. By configuring it as an array speaker, it is possible to emit sound at a higher volume.

[0026] Frequency Response Characteristics FIG. 2 shows the frequency characteristics of the electroacoustic transducer 1 according to the present invention. That is, the horizontal axis represents frequency, and the vertical axis represents output level (dBV). The dashed line represents the frequency characteristics of the electroacoustic transducer 1001 according to the related art, and the solid line represents the frequency characteristics of the electroacoustic transducer 1 according to the present invention. Although the electroacoustic transducer 1 according to the present invention has a slightly lower low-frequency output level than the electroacoustic transducer 1001 according to the related art, it can be seen that it has sufficient sensitivity in higher frequency bands, for example, in the mid-frequency range around 1 kHz and higher, and can achieve sufficient sound pressure. Furthermore, because the low-frequency output level is low, sharp mechanical resonance peaks are unlikely to occur, enabling natural sound output. The output level can be adjusted appropriately by changing the material of the support member 30, etc. For example, by using a support member 30 made of a material that exerts greater tension, i.e., that is relatively stretchable, it is possible to increase the low-frequency output. Conversely, when the electroacoustic transducer 1 is used in an environment where low-frequency sound pressure may cause discomfort, such as when it is in direct contact with the human body, it is possible to further suppress the low frequencies by using a support member 30 made of a material with less tension, i.e., one that is relatively inelastic.

[0027] Sound Generated When Hammering FIG. 3 is a three-dimensional frequency characteristic graph showing the frequency analysis of the sound generated when the top surface of the electroacoustic transducer 1 according to the present invention and the electroacoustic transducer 1001 according to the related art is hammered with a finger. FIG. 3(a) shows the three-dimensional frequency characteristic graph of the electroacoustic transducer 1 according to the present invention, and FIG. 3(b) shows the three-dimensional frequency characteristic graph of the electroacoustic transducer 1001 according to the related art. In both cases, hammering is performed at the timing indicated by the triangle. The sound across a wide frequency band generated immediately after hammering is the sound of the hammering itself. In the electroacoustic transducer 1001 according to the related art, a sound (a frequency band of just under 10 kHz) is generated in the dashed line region after the sound of the hammering itself. This sound is noise generated by the resonance of the suspension 1030, which is composed of a metal spring. On the other hand, in FIG. 3(a), the impact sound is generally small, and no peak in the high-frequency region corresponding to the above-mentioned noise generated in the electroacoustic transducer 1001 according to the related art is observed. In other words, it is clear that the electroacoustic transducer 1 according to the present invention can exhibit stable performance without generating noise due to external impact.

[0028] Electroacoustic Transducer (2) Here, a different embodiment of the electroacoustic transducer of this embodiment will be described, focusing on differences from the previously described embodiment. Note that the same reference numerals are used for components similar to those of the first embodiment. The electroacoustic transducer 101 of the second embodiment shown in FIG. 4 differs from the previously described electroacoustic transducer 1 in that the unit base 111 is a substantially cylindrical member that holds the coil 12 and covers the side surface of the vibrating unit 20. In other words, the unit base 111 has an annular portion, and the coil 12 and vibrating unit 20 are disposed inside the through-hole 111a. A support member 30 is bonded to the front (-Y side) of the unit base 111 (an example of the "first surface" in the claims), and the support member 30 covers the through-hole 111a. This configuration results in a more robust structure because the coil 12 is circumferentially covered by the unit base 111. The support member 30 may be configured to completely cover the through-hole 111a, or may be configured to cover at least a portion of the through-hole 111a.

[0029] Furthermore, with the above-described configuration, a cap yoke is not required, so the electro-acoustic transducer 101 can be realized with a small number of parts and a simple configuration. Assembly is also easy. Furthermore, the unit base 111 has a simple, approximately cylindrical shape, so it is easy to manufacture. Specifically, an existing cylindrical component, such as a washer, can be repurposed as the unit base 111. The washer is preferably made of a material that can adhere the support member 30, and an appropriate resin, bake material, or the like can be used. In particular, the washer is preferably made of a material that can adhere so-called double-sided tape.

[0030] The support member 230 may be substantially rectangular, as in an electro-acoustic transducer 201 according to a third embodiment shown in Fig. 5(a). Furthermore, the support member 330 may be substantially cross-shaped, as in an electro-acoustic transducer 301 according to a fourth embodiment shown in Fig. 5(b). A plurality of support members 230 may be provided. For example, the cross-shaped support member 330 may be formed by bonding two substantially rectangular support members 230 together, with each member being substantially orthogonal to the other.

[0031] 4 are bonded to the unit base 111 and the support member 30 by, for example, double-sided tape or an appropriate adhesive. With this configuration, even if the unit base 111 and the support member 30 become separated, they can simply be reattached with the double-sided tape or adhesive, making repairs easier than, for example, a configuration that uses a special connecting member.

[0032] In addition to the configuration shown in the figure, a cover member may be provided to cover the entire electro-acoustic transducer 101 shown in Figure 4. The cover member is made of rubber, for example. With this configuration, a more robust electro-acoustic transducer can be constructed. Furthermore, since the magnet 22 is covered by the cover member, it can be prevented from being attracted to external iron members or magnetic bodies, such as a desk.

[0033] In addition to the configuration shown in the figure, the center yoke 23 may have a second magnet having a polarity opposite to that of the magnet 22. With this configuration, the second magnet acts as a so-called counter magnet (a counteracting magnet or a bucking magnet) that cancels out the magnetic field of the magnet 22, and it is possible to prevent the electro-acoustic transducer 101 from being attracted by the magnet 22 to external iron members or magnetic bodies such as a desk.

[0034] Electro-acoustic Transducer (3) The electro-acoustic transducer 401 of the fifth embodiment shown in FIG. 6 differs from the electro-acoustic transducer 101 of the second embodiment in that it further includes a second support member 430 bonded to the vibration unit 20 on the rear side (+Y side) of the unit base 111 (an example of the "second surface" in the claims). The second support member 430 can be of the same shape and material as the support member 30. The support member 30 and the second support member 430 included in the electro-acoustic transducer 401 may have the same shape and material, or one or both of the shape and material may be different. In the example shown in the figure, the second support member 430 is a substantially circular member that is sized to fit the unit base 111 and covers the rear side of the unit base 111. This configuration allows the vibration unit 20 to be sealed within the through-hole 111a of the unit base 111, resulting in a more robust electro-acoustic transducer 401. Furthermore, it is easy to house the electro-acoustic transducer 401 inside another device. Moreover, since the through-hole 111a is sealed, waterproofing and dustproofing are also ensured. Furthermore, since the vibrating section 20 is also supported by the second support member 430, vibration of the vibrating section 20 in an unintended direction can be suppressed. Furthermore, since the second support member 430 is spaced further from the coil 12 than the first support member 30, it is less susceptible to changes in response to heat generated by the coil 12. Therefore, the configuration of the electro-acoustic transducer 401 allows for more stable sound emission.

[0035] Configuration Example Fig. 7 is a schematic diagram showing an electro-acoustic transducer 401 according to the present invention attached to the outer wall of a box and configured as a speaker. The electro-acoustic transducer 401 is connected to a sound generating device 40, such as a smartphone. The bottom surface of the electro-acoustic transducer 1 abuts against a box 50 having a hole 50a. With this configuration, vibrations of the support member 30 are transmitted to the box 50, and sounds reverberating within the interior space of the box 50 are emitted from the hole 50a. In other words, with a simple configuration, the box 50 can function as an amplifier or speaker, enabling louder sound to be emitted.

[0036] Electroacoustic Transducer Assembly Kit The present invention can also be configured as an assembly kit 101a for an electroacoustic transducer 101 having at least a fixed part 10 having a coil 12, for example, as shown in Figure 4, a vibrating part 20 that is inserted inside the coil 12 and vibrates along the axial direction of the coil 12 in response to an input signal, and a support member 30 that is adhered to the fixed part 10 and the vibrating part 20 and supports the vibrating part so that it can vibrate under tension. The assembly kit can be used as a teaching material to help elementary and junior high school students, for example, understand the mechanism of electromagnetic induction through assembly work.

[0037] The coil 12 is connected to the inside of the through-hole 111a of the unit base 111. Both ends of the coil 12 are connected to connectors via appropriate cables. This connector can be connected to a sound generating device such as a smartphone. The support member 30 may also be a member that has adhesive strength on one surface in advance. For example, a release paper that can be easily peeled off by an assembler is attached to the adhesive surface. The magnet 22, center yoke 23, and spacer 24 of the vibration unit 20 are connected in advance.

[0038] The assembler peels off the release paper from the support member 30, places it on a desk with the adhesive side facing up, and places and adheres the unit base 111. Next, the vibrating section 20 is accommodated in the through-hole 111a of the unit base 111, thereby completing the electro-acoustic transducer 101. In this way, the assembly kit 101a for the electro-acoustic transducer 101 according to the present invention allows the electro-acoustic transducer 101 to be easily assembled.

[0039] For example, the support member 30 may be printed with a mark indicating the bonding position for bonding the vibration unit 20. In this case, by placing the vibration unit 20 in accordance with the mark, the assembler can determine the position of the vibration unit 20 relative to the support member 30 and reliably cover the through-hole 111a with the support member 30 when bonding the unit base 111. Furthermore, while it is difficult to print marks on the metal suspension 1030, the support member 30 of the present application allows for printing marks, making assembly easy even for junior assemblers. Note that any suitable shape can be used for the mark. Furthermore, instead of or in addition to the position for bonding the vibration unit 20, a mark indicating the position for bonding the fixed portion 10 may be printed on the support member 30.

[0040] In the case of the suspension 1030 shown in the related art, because it is precisely machined, it is difficult to place it on a desk as a base for assembly, and if it were used as a base, there is a risk of deformation. Furthermore, in the case of the suspension 1030, a connecting process using connecting members is required, making the assembly work complicated. In this regard, the support member 30 has a simple shape and can also function as a base for assembly, making the assembly work easy. Furthermore, because the connecting process is simply by adhesive bonding, even a young person can easily perform it.

[0041] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

[0042] REFERENCE SIGNS LIST 1 electroacoustic transducer 10 fixed portion 20 vibration portion 21 cap yoke 22 magnet 23 center yoke 24 spacer 30 support member

Claims

1. An electro-acoustic transducer comprising: a fixed part having at least a coil; a vibrating part disposed inside the coil and vibrating along the axial direction of the coil in response to an input signal; and a support member connected to the fixed part and the vibrating part and supporting the vibrating part so that it can vibrate under tension.

2. The electro-acoustic transducer according to claim 1, wherein the support member is a sheet-like member.

3. The electro-acoustic transducer according to claim 2, wherein the support member is made of a synthetic polymer material.

4. The electro-acoustic transducer according to claim 3, wherein the support member is made of any one of PET, cellophane, a low-resilience acrylic foam sheet, and silicone rubber.

5. The electro-acoustic transducer according to claim 1, wherein the support member is bonded to the coil.

6. An electro-acoustic transducer as claimed in claim 1, wherein the fixed part further comprises a unit base having a cylindrical part for holding the coil, the vibrating part is disposed inside a through-hole formed in the cylindrical part, and the support member is adhered to the unit base so as to cover at least a portion of the through-hole.

7. The electro-acoustic transducer according to claim 6, wherein the support member is bonded to the first surface of the unit base, and further comprising a second support member bonded to the second surface of the unit base and the vibrating portion.

8. The electro-acoustic transducer according to claim 6, wherein the support member covers the through-hole of the cylindrical portion.

9. An assembly kit for an electroacoustic transducer comprising: a fixed part having at least a coil; a vibrating part that is inserted inside the coil and vibrates along the axial direction of the coil in response to an input signal; and a support member that is adhered to the fixed part and the vibrating part and supports the vibrating part so that it can vibrate under tension.

Images