speaker equipment

Abstract

This speaker system provides high-quality sound reproduction through a novel configuration that suppresses the air spring effect. [Solution] The speaker device of the present invention comprises a housing 1 having a baffle plate 2 on which a speaker unit 3 that vibrates in response to an input electrical signal and outputs sound waves is mounted, and an opening 4 is provided on the bottom surface. A predetermined amount of granular material 6, placed parallel to the opening end 5, closes the opening 4 of the housing 1. Granular material 6 is interposed in the path from the internal space to the external space of the enclosure 1, creating a structure in which the air inside the enclosure 1 is acoustically connected to the outside atmosphere via the granular material 6. This configuration suppresses the air spring effect, making it possible to provide a speaker device that achieves high-quality sound reproduction with low distortion.

Description

Technical Field

[0001] The present invention relates to a speaker device.

Background Art

[0002] In conventional acoustic reproduction technology, a speaker device in which a dynamic speaker such as a cone speaker is mounted on a housing has been widely spread.

[0003] When the cone speaker vibrates according to an input electrical signal, if the vibration on the front side of the diaphragm is defined as positive phase, the vibration on the back side of the diaphragm becomes negative phase. That is, the sound waves generated from the front and back sides of the diaphragm are in a relationship of opposite phases to each other. These sound waves in the relationship of opposite phases interfere with each other based on the principle of superposition, and as a result, a phenomenon of mutual cancellation occurs.

[0004] When sound is reproduced in a cone speaker unit not mounted on a housing, the negative-phase sound generated on the back side of the diaphragm, particularly the low-frequency sound with a long wavelength, enters the front side of the diaphragm due to the diffraction phenomenon. This incoming negative-phase sound interferes with the positive-phase sound on the front side of the diaphragm and cancels each other out. As a result, from the cone speaker unit, a sound having acoustic characteristics with the low-frequency range attenuated and biased toward the high-frequency range is reproduced.

[0005] As described above, the negative-phase sound generated from the back side of the diaphragm is a factor that degrades the reproduced sound quality. To solve this problem, a sealed structure has been devised to block the negative-phase sound from the back side of the diaphragm and confine it inside the housing, leading to the current sealed-type speakers.

[0006] Currently commercially available sealed-type speakers generally adopt a method of confining the negative-phase sound on the back side of the diaphragm inside a sealed housing and absorbing / attenuating the confined negative-phase acoustic energy by a porous sound-absorbing material. However, as shown in Non-Patent Document 1, glass wool, a typical porous sound-absorbing material, cannot adequately absorb the high-energy acoustic energy in the low-frequency range below 100 Hz. The fluctuations in air pressure caused by residual acoustic energy create an air spring effect within the enclosure, hindering the movement of the diaphragm, which is trying to vibrate faithfully to the input electrical signal. For this reason, sealed speakers are widely recognized as having a muffled sound quality and low sound pressure in the low-frequency range.

[0007] For the reasons mentioned above, bass reflex speakers, which have high sound pressure levels in the low-frequency range, are currently the mainstream type of speaker equipment on the market for audio reproduction. On the other hand, while sealed enclosures have a structural drawback due to the air spring effect, they have the advantage that the out-of-phase sound from the back of the diaphragm is contained within the enclosure and does not propagate into the atmosphere. Therefore, unlike bass reflex speakers, they have the advantage that the positive-phase sound is not interfered with by the out-of-phase sound.

[0008] It is a well-known fact that high-quality sound reproduction can be achieved in sealed speakers by suppressing the air spring effect, which is a structural drawback of sealed speakers. Based on this understanding, various methods have been devised to improve the sound quality of sealed speakers.

[0009] Patent Document 1 discloses a method in which more than 70% of the enclosure volume of a sealed speaker is filled with a viscoelastic solid-gas composite. In this technology, acoustic energy from the back of the diaphragm is consumed by both airflow friction resistance and viscous flow resistance, and dissipated as thermal energy. Furthermore, Patent Document 2 discloses a method of attaching a sound-dampening device in the shape of an inverted horn that gradually decreases in diameter to the back of a speaker unit inside a sealed enclosure. This technology suppresses the effect of sound waves from the back of the speaker unit on the diaphragm using the inverted horn-shaped sound-dampening device, thereby preventing sound quality degradation and simultaneously achieving miniaturization of the enclosure. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2006-352647 [Patent Document 2] Utility Model Registration No. 3228534 Gazette [Non-patent literature]

[0011] [Non-Patent Document 1] Paramount Glass Industries, Ltd., "Technical Data," page 136 https: / / www.pgm.co.jp / data / pdf / S001_2020_2021_5syo_web.pdf #:▲~▼:text=127%20www.pg [Accessed September 19, 2024] [Overview of the project] [Problems that the invention aims to solve]

[0012] In a sealed speaker enclosure, if the sound-absorbing material can completely absorb the out-of-phase acoustic energy generated on the back of the diaphragm, then no air pressure fluctuations or air spring effects occur within the enclosure. Without air spring effects, the diaphragm can respond faithfully to the input electrical signal. However, to the best of our knowledge, there are no sound-absorbing materials that effectively attenuate low-frequency acoustic energy.

[0013] The air spring effect in sealed speakers is inherent to the sealed structure itself, and given the current lack of sound-absorbing materials that effectively absorb low-frequency acoustic energy, solving this problem is difficult. Addressing the air spring effect in sealed speakers requires new ideas and solutions that differ from conventional technological approaches.

[0014] This invention has been made in view of the problems of the prior art regarding the air spring effect described above, and aims to provide a small speaker device with a novel configuration that suppresses the occurrence of the air spring effect while maintaining the advantages of a sealed speaker, thereby achieving high-quality reproduced sound. [Means for solving the problem]

[0015] In order to solve the above problems, the speaker device of the present invention includes a speaker unit that vibrates according to an input electrical signal, and a small-volume housing having an opening provided on the bottom surface, the opening is blocked by granular material, a gap acoustically communicating with the outside atmosphere is formed by an insulator between the opening end and the installation surface, the granular material is interposed in the path from the internal space of the housing to the outside through the opening, and the air in the internal space of the housing acoustically communicates with the outside atmosphere through the granular material.

[0016] In the present invention, the opening and the granular material that acoustically communicates while blocking the opening constitute a housing with a semi-hermetic structure.

[0017] Due to this characteristic semi-hermetic structure, the acoustic energy generated by the diaphragm acts intensively on the granular material that blocks the opening. The granular material is an aggregate of fine solid particles with a large specific gravity, has innumerable fine gaps and a large surface area, and the particles have the property of moving freely according to the amount of energy load.

[0018] The acoustic energy acting on the granular material vibrates the fine particles, causes them to rub against each other, generates frictional heat between the surfaces of the fine particles, and dissipates and attenuates the energy while passing through the granular material, but does not completely attenuate. The low-level acoustic energy that has passed through the granular material is dissipated into the atmosphere from the opening end and propagates in the atmosphere as a sound wave with a low sound pressure.

[0019] Since the acoustic energy is dissipated into the atmosphere after passing through and attenuating the granular material, the generation of the air spring effect in the housing is suppressed. As a result, the diaphragm can vibrate faithfully according to the input electrical signal. On the one hand, the acoustic energy dissipated into the atmosphere is greatly attenuated while passing through the granular material, and the sound pressure propagating in the atmosphere as a sound wave is low. Therefore, the influence of the interference of the reverse-phase sound on the back surface of the diaphragm on the forward-phase sound on the front surface is negligibly small.

[0020] Due to the interaction between the granular material and the housing with a quasi-hermetic structure in which the granular material closes the opening, the air spring effect and the interference of the reverse-phase sound are suppressed. As a result, high-quality reproduced sound that is faithful to the original sound and has little distortion can be obtained.

Advantages of the Invention

[0021] According to the present invention, by suppressing the generation of the air spring effect inside the housing, it is possible to provide a small speaker device having high reproducibility of the original sound and acoustic performance with little distortion over the entire frequency band.

Brief Description of the Drawings

[0022] [Figure 1] It is a perspective view of the speaker devices according to Embodiment 1, Embodiment 2, and Embodiment 3 of the present invention. [Figure 2] It is a cross-sectional view taken along line XX of FIG. 1 of the speaker device according to Embodiment 1 of the present invention. [Figure 3] It is a cross-sectional view taken along line XX of FIG. 1 of the speaker device according to Embodiment 2 of the present invention. [Figure 4] It is a cross-sectional view taken along line XX of FIG. 1 of the speaker device according to Embodiment 3 of the present invention. [Figure 5] It is a perspective view of the speaker device according to Embodiment 4 of the present invention. [Figure 6] It is a cross-sectional view taken along line YY of FIG. 5 of the speaker device according to Embodiment 4 of the present invention.

Modes for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described. Note that the embodiments shown below are examples of the present invention, and the present invention is not limited to these embodiments.

[0024] In one embodiment of the present invention, the opening is closed by granular material. This granular material is in contact with the outside atmosphere through a gap between the opening end formed by the insulator and the installation surface.

[0025] This configuration maintains an acoustically connected state between the air inside the enclosure and the surrounding air.

[0026] In one embodiment of the present invention, the volume of the enclosure is approximately 50% or less compared to a conventional standard small sealed speaker device.

[0027] This configuration reduces the elastic effect of the air inside the enclosure, allowing acoustic energy to be efficiently transmitted to the granular material in phase with the vibration of the diaphragm. In conventional sealed speakers, there was a proportional relationship between the size of the enclosure and the improvement in sound quality. However, in the semi-sealed structure of the present invention, it is important to transmit acoustic energy to the granular material in phase with the diaphragm, and a large enclosure is unsuitable for a semi-sealed structure because it causes a phase delay.

[0028] In one embodiment of the present invention, the inner diameter cross-sectional area of ​​the opening is in the range of 90% to 110% of the effective vibration area of ​​the diaphragm.

[0029] In this configuration, acoustic energy is transmitted to the particles in phase with the diaphragm and with an intensity approximately equal to that of the diaphragm's vibration.

[0030] In one embodiment of the present invention, the granules are an aggregate having a particle structure formed by non-magnetic solid particles.

[0031] This configuration creates granular material that is not attracted to the speaker unit's magnet. This prevents the particles from entering the speaker unit's magnetic circuit.

[0032] In one embodiment of the present invention, the material forming the granules is an aggregate of solid particles or solid fragments having a specific gravity in the range of 2.5 to 10.0 and a minor axis in the range of 100 μm to 300 μm.

[0033] This configuration creates a granular structure, which works in cooperation with the semi-sealed structure that closes the openings, effectively suppressing the occurrence of the air spring effect.

[0034] In one embodiment of the present invention, a support wire mesh and a permeable membrane that selectively allows air to pass through while trapping particles are fixed to the inner circumferential surface of the opening, and granular material is placed on the upper surface of this permeable membrane.

[0035] This configuration makes it possible to hold the granular material that closes the opening in a hollow state.

[0036] In one embodiment of the present invention, the granular material is enclosed inside a bag made of a breathable membrane and placed on the upper surface of a support wire mesh fixed to the opening.

[0037] This configuration makes it possible to easily prevent the scattering of granules while holding the granules that block the opening in a hollow state.

[0038] In one embodiment of the present invention, the granular material is enclosed in a porous solid container that is permeable and captures particles, and this container is tightly fixed to the inner surface of the opening.

[0039] This makes it possible to easily prevent the scattering of granules while holding the granules that block the opening in a hollow state.

[0040] <Embodiment 1> A speaker device according to Embodiment 1 of the present invention will be described with reference to Figures 1 and 2. In these figures, reference numeral S1 denotes the speaker device according to this embodiment.

[0041] As shown in Figures 1 and 2, the speaker device S1 comprises a housing 1, a baffle plate 2 provided on the front of the housing 1, a speaker unit 3 mounted on the baffle plate 2, and an opening 4 provided on the bottom surface of the housing 1.

[0042] The opening 4 is equipped with a lower support wire mesh 10a at a predetermined height from the opening end 5, and the outer edge of the lower support wire mesh 10a is fixed to the inner circumferential surface of the opening 4 parallel to the opening end 5.

[0043] The opening 4 further includes a lower breathable membrane 9a that is in contact with the upper surface of the lower support wire mesh 10a, and the outer edge of the lower breathable membrane 9a is tightly fixed to the inner circumferential surface of the opening 4.

[0044] The opening 4 further comprises granular material 6 placed on the upper surface of the lower permeable membrane 9a, the granular material 6 being placed parallel to the opening end with a predetermined thickness, and closing the opening 4.

[0045] The opening 4 further comprises an upper permeable membrane 9 positioned at a predetermined height from the upper surface of the granular material 6, and the outer edge of the upper permeable membrane 9 is tightly fixed to the inner circumferential surface of the opening 4.

[0046] The opening 4 further comprises an upper support wire mesh 10 positioned at a predetermined height from the upper surface of the upper breathable membrane 9, with the outer edge of the upper support wire mesh 10 fixed to the inner circumferential surface of the opening 4 parallel to the opening end 5.

[0047] The housing 1 is equipped with an insulator 11 that maintains a predetermined spatial distance between the open end 5 and the mounting surface, and the insulator 11 is either pre-attached to the housing 1 or configured as a separate component.

[0048] In the speaker device S1, the path from the internal space of the housing 1 through the open end 5 to the external space is blocked by the granular material 6, but the internal space of the housing 1 and the atmosphere are acoustically in communication via the granular material 6.

[0049] The granular material 6 that closes the opening 4 is composed of zircon sand (zirconium silicate) particles. This zircon sand has a specific gravity of 4.7, a particle size of approximately 150 μm, and is 1 cm². 3 The total surface area is 39.7 cm². 2 Therefore, the granular body 6 has countless minute gaps and a large surface area. The granular material 6 can also be replaced with particles or solid pieces having similar properties to zircon sand, a mixture of particles with different specific gravities and particle sizes, layers of different types of particles, or sound-absorbing material of other materials placed on top of the granular material 6.

[0050] The operating mode of the speaker device S1 will be described below. Due to the characteristic semi-sealed structure of the present invention, acoustic energy within the housing is concentrated at the opening and passes through the granular material 6. The acoustic energy passes through the granular material 6 while attenuating its energy, but it is not completely attenuated. The low level of acoustic energy that has passed through the granular material 6 is dissipated into the atmosphere from the opening end 5 and propagates into the atmosphere as sound waves with low sound pressure.

[0051] Since the acoustic energy is dissipated into the atmosphere after passing through the particles 6, the occurrence of the air spring effect within the enclosure is suppressed. As a result, the diaphragm vibrates faithfully to the input electrical signal. On the other hand, since the acoustic energy dissipated into the atmosphere after passing through the particles 6 is significantly attenuated, the sound pressure of the sound from the back of the diaphragm that propagates into the atmosphere as a sound wave is low. As a result, the effect of interference between out-of-phase sound and in-phase sound is practically negligible.

[0052] The speaker device S1 is capable of reproducing high-quality sound that is faithful to the original sound and has minimal distortion, through the cooperation of its constituent elements: the granular body 6 formed by particles with distinctive properties, and the small-volume, semi-sealed housing 1.

[0053] <Embodiment 2> Referring to Figures 1 and 3, a speaker device S2 according to Embodiment 2 of the present invention will be described. This embodiment has the same configuration as Embodiment 1, except for the method of placing the granular material 6, and the same reference numerals are used for components that are basically the same as in the previous embodiment. Descriptions that overlap with Embodiment 1 will be omitted, and the differences will be described in detail.

[0054] In this second embodiment, the granular material 6 is placed directly on the upper surface of the lower support wire mesh 10a of the opening 4, without using the permeable membranes 9 and 9a used in the first embodiment.

[0055] The opening 4 is equipped with granules 6 enclosed in a breathable bag 7. The bag 7 containing the granules 6 is placed parallel to the opening end 5 between a lower support wire mesh 10a and an upper support wire mesh 10 fixed to the inner circumferential surface of the opening 4, thereby closing the opening 4 with the granules 6.

[0056] Speaker device S2 operates on the same principle as in Embodiment 1. Specifically, the out-of-phase acoustic energy within the enclosure is attenuated as it passes through the gaps between the particles of the granular material 6, thereby suppressing the air spring effect and reducing interference with the in-phase sound. As a result, the original sound is reproduced more faithfully with low distortion, and high-quality sound reproduction is achieved over a wide bandwidth.

[0057] <Embodiment 3> Referring to Figures 1 and 4, a speaker device S3 according to Embodiment 3 of the present invention will be described. This embodiment has the same configuration as Embodiment 1, except for the method of placing the granular material 6, and the same reference numerals are used for components that are basically the same as in the previous embodiment. Descriptions that overlap with Embodiment 1 will be omitted, and the differences will be described in detail.

[0058] In Embodiment 3, the granular material 6 is contained in the container 8 and placed directly on the opening 4 without using a permeable membrane or support wire mesh.

[0059] The opening 4 contains granules 6 enclosed in a container 8 made of a breathable porous solid. The container 8 containing the granules 6 is tightly fixed to the inner surface of the opening 4, and the granules 6 close the opening 4.

[0060] The speaker device S3 operates on the same principle as in Embodiment 1. Specifically, the out-of-phase acoustic energy within the enclosure is attenuated as it passes through the gaps between the particles of the granular material 6, thereby suppressing the air spring effect and reducing interference with the in-phase sound. As a result, the original sound is reproduced more faithfully with low distortion, and high-quality sound reproduction is achieved over a wide bandwidth.

[0061] <Embodiment 4> Referring to Figures 5 and 6, a speaker device S4 according to Embodiment 4 of the present invention will be described. The speaker device S4 of Embodiment 4 differs from Embodiment 3 in that it has a cylindrical housing 1 and a baffle plate 2 is arranged on the upper surface of the housing 1, but the other structures are the same as those of Embodiment 3. Components common to the previous embodiments are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0062] As shown in Figures 5 and 6, the speaker device S4 comprises a cylindrical housing 1, a baffle plate 2 provided on the upper surface of the housing 1, a speaker unit 3 mounted on the baffle plate 2, and an opening 4 provided on the bottom surface of the housing 1.

[0063] The opening 4 is closed by granular material 6 enclosed in a container 8 made of a permeable porous solid, similar to Embodiment 3, and the outer edge of the container 8 is tightly fixed to the inner circumferential surface of the opening 4 parallel to the opening end 5. The method for placing the granular material 6 that closes the opening 4 may be either the method using the support wire mesh 10, 10a and permeable membrane 9, 9a in Embodiment 1, or the method using the bag 7 in Embodiment 2.

[0064] As shown in Figure 6, the outer diameter of the cylindrical housing 1 is approximately the same as the outer diameter of the speaker unit 3, which makes it possible to effectively reduce the volume of the housing 1.

[0065] The granular material 6 that closes the opening 4 and the diaphragm are positioned opposite each other, with similar areas ranging from 90% to 110% of each other's area. This configuration, in cooperation with the smaller-volume housing described above, allows acoustic energy from the back of the diaphragm to be transmitted to the granular material 6 more effectively and in phase with the diaphragm.

[0066] The speaker device S4 operates on the same principle as in Embodiment 1. Specifically, the out-of-phase acoustic energy within the enclosure is attenuated as it passes through the gaps between the particles of the granular material 6, thereby suppressing the air spring effect and reducing interference with the in-phase sound. As a result, the original sound is reproduced more faithfully with low distortion, and high-quality sound reproduction is achieved over a wide bandwidth. [Explanation of Symbols]

[0067] 1 cabinet 2 Baffle board 3 speaker units 4 openings 5 Open end 6 grains 7 Bag body 8 containers 9. Upper breathable membrane 9a Lower breathable membrane 10 Upper support wire mesh 10a Lower support wire mesh 11 Insulators

Claims

1. It is a speaker device, A housing comprising a speaker unit mounted on a baffle plate located on the front or top surface, which vibrates in response to an input electrical signal and outputs sound waves, An opening provided on the bottom surface of the housing, The system comprises a granular body having predetermined acoustic properties, which is placed so as to close the opening, The granular material is interposed in the path from the internal space to the external space of the enclosure. A speaker device characterized by the following features.

2. The granular material is an aggregate of non-magnetic fine solid particles or solid fragments. The minor diameter of the solid particle or solid fragment is 100 μm or more, and the specific gravity is 2.5 or more. The speaker device according to feature 1.

3. The outer edge of the breathable membrane is tightly fixed to the inner circumferential surface of the opening. The breathable membrane is arranged parallel to the surface of the opening, The granular material placed on the upper surface of the breathable membrane is blocking the opening. The speaker device according to feature 1.

4. The outer edge of the support wire mesh is fixed to the inner circumferential surface of the opening. The support wire mesh is arranged parallel to the surface of the opening. The speaker device according to feature 1.

5. The granular material is enclosed in a bag made of a breathable membrane. The granular material enclosed in the bag is blocking the opening. The speaker device according to feature 1.

6. The granular material is sealed in a container made of a permeable porous solid. The granular material sealed in the container is blocking the opening. The speaker device according to feature 1.

7. The housing is provided with a vent that connects the opening to the outside atmosphere. The speaker device according to feature 1.

8. The opening is formed The ventilation opening and the opening are separated, It has a partition plate that forms a gap connecting the opening and the vent. The speaker device according to feature 1.

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