CN101548553B - Material for speaker device and speaker device using it - Google Patents

Abstract

The material of the present invention for increasing the sound pressure level at the bass reproduction limit comprises a radius of 50 The following cumulative pore volume is 0.4ml/g or more activated carbon. Preferably the activated carbon has a radius of 7 The following cumulative pore volume is 0.1 ml/g or less. In particular, when the activated carbon has a radius of 18 When the following cumulative pore volume is 0.5ml/g or more sound pressure level raising material is placed in the cabinet of the speaker device, the pressure fluctuation of the gas in the cabinet generated by the vibration of the speaker can be alleviated, and a very good performance can be obtained. Bass reproduction effect. In addition, in the radius of 18 to 50 where activated carbon is loaded In the case of a material that increases the sound pressure level with a cumulative pore volume of 0.4 ml/g or more, a speaker device having a good bass reproduction effect can be obtained even in a high-humidity atmosphere.

Description

Material for speaker device and speaker device using same

technical field

The present invention relates to a material capable of effectively realizing bass reproduction in a small speaker device and improving the sound pressure level of the base reproduction limit for the speaker device, and a speaker device using the same.

Background technique

In general, in a small speaker device, it is difficult to reproduce bass due to the influence of acoustic stiffness due to the small volume of the speaker cabinet. That is, when an electric signal is applied to the speaker, the vibration of the speaker compresses the air in the cabinet, which acts as an air spring and hinders the operation of the speaker. In particular, the sound pressure level decreases in the bass range, and sufficient bass reproduction cannot be achieved. In order to realize low-voice reproduction in a small speaker device, a speaker device in which a gas-adsorbing material such as activated carbon is disposed inside a cabinet has been proposed (for example, International Publication No. 84/03600 pamphlet).

The speaker device of this International Publication No. 84/03600 pamphlet has: a speaker cabinet; a speaker mounted on one surface of the cabinet in such a manner that the rear part communicates with the inside of the cabinet; gas contained in the cabinet; and a configuration Gas-absorptive materials such as activated carbon are used in the box. When an electric signal is applied to the speaker, the vibration of the speaker causes compression and expansion of the gas inside the box at high speed. Along with this, since the molecules of the gas are adsorbed/desorbed on the activated carbon, the pressure fluctuation inside the box is suppressed. As a result, the sound pressure level at the bass region is not suppressed, and an effect equivalent to the case of using a large-capacity cabinet seems to be obtained.

The aforementioned gas-adsorbing material, such as activated carbon, preferably has a low water content. This is because when the activated carbon absorbs moisture and is placed in the box, even if the gas in the box is compressed by the vibration of the speaker, the ability to adsorb the gas molecules becomes insufficient. For this reason, in the above-mentioned International Publication No. 84/03600 pamphlet, a complicated structure such as a partition (diaphragm) that does not allow moisture to permeate is provided between the speaker in the box and the gas-adsorbing material such as activated carbon is adopted. structure.

In International Publication No. 03/013183 pamphlet, it is disclosed that in order to make it difficult to absorb moisture even in a high-humidity atmosphere, as a gas-adsorbing material placed in the box, at least partially used Hydrophobized adsorbent material. For example, activated carbons that have been hydrophobized by reaction with silicon compounds are disclosed. British Patent Application Publication No. 2391224 describes hydrophobized activated carbon that can be used as such a gas-adsorbing material. Such a material can be used even in a high-humidity atmosphere, but requires complicated steps such as hydrophobization.

In the pamphlet of International Publication No. 03/101147, a speaker device is disclosed, which is loaded with activated carbon in the box, and the box is replaced by high-concentration dry carbon dioxide gas. A detection unit for the concentration of carbon dioxide, a supply unit for carbon dioxide, and a unit for controlling the supply. However, this speaker device also requires a complicated unit for keeping the humidity low.

Therefore, a method for improving bass reproduction of the above-mentioned speaker device is desired, and in particular, further improvement of gas-adsorbing materials such as activated carbon is desired.

Contents of the invention

The present invention has been made to solve the above-mentioned conventional problems, and its object is to provide a material for raising the sound pressure level at the bass reproduction limit for a speaker device that can further effectively realize bass reproduction in a small speaker device and a speaker unit using it.

The inventors have found that when activated carbon having a cumulative volume of 0.4 ml/g or more of pores having a pore diameter of a predetermined size or less is placed in the housing of the above-mentioned speaker device, a sufficient gas adsorption effect is obtained when the speaker vibrates. , as a result, bass reproduction can be realized more effectively, thereby completing the present invention.

The present invention provides a radius of 50 The following are activated carbons with a cumulative pore volume of 0.4ml/g or more, which increase the sound pressure level at the bass reproduction limit.

In addition, the present invention provides a speaker device having: a cabinet; a speaker unit mounted on the cabinet; and a material for improving a sound pressure level at a bass reproduction limit arranged in a cavity inside the cabinet, The sound pressure level enhancing material consists of a radius of 50 The following cumulative pore volume is 0.4ml/g or more activated carbon.

In one embodiment, the radius of above-mentioned activated carbon is 7 The following cumulative pore volume is 0.1 ml/g or less.

In one embodiment, the above-mentioned activated carbon has a radius of 18 The cumulative pore volume below is 0.5 ml/g or more.

In another embodiment, the above-mentioned activated carbon has a radius of 18 to 50 The cumulative pore volume is above 0.4ml/g.

In yet another embodiment, the above-mentioned activated carbon has a radius of 18 to 50 The cumulative pore volume is above 0.5ml/g.

When the material of the present invention that improves the sound pressure level at the bass reproduction limit is placed in the cabinet of the above-mentioned speaker device, the pressure fluctuation of the gas in the cabinet due to the vibration of the speaker can be alleviated, and a good bass reproduction effect can be obtained. .

In particular, when the activated carbon has a radius of 18 When a material with a cumulative pore volume of 0.5ml/g or more that increases the sound pressure level at the bass reproduction limit is placed in the cabinet of the speaker device, a very good bass reproduction effect can be obtained, even in a small speaker device. It is also possible to obtain the same acoustic effect as when using a large-capacity cabinet.

On the other hand, activated carbon has a radius of 18 to 50 A material with a cumulative pore volume of 0.4ml/g or more that increases the sound pressure level at the bass reproduction limit is difficult to absorb moisture even in an atmosphere with relatively high humidity. Therefore, when the material that improves the sound pressure level at the bass reproduction limit is placed in the cabinet of the speaker device, the gas in the cabinet can be easily adsorbed/desorbed even in a relatively high humidity atmosphere. As a result, Sufficient bass reproduction can be obtained even in high-humidity atmospheres.

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an embodiment of a speaker device using a material for increasing the sound pressure level at the bass reproduction limit of the present invention.

Fig. 2 is a schematic cross-sectional view showing another embodiment of a speaker device using a material for increasing the sound pressure level at the bass reproduction limit of the present invention.

3 is a graph showing the pore radius distribution of the activated carbon obtained in Example 1, and the cumulative pore volume with respect to the pore radius.

FIG. 4 is a graph showing the water adsorption amount with respect to the relative humidity of the activated carbon obtained in Examples 1, 2, 9 and 10. FIG.

5 is a graph showing the pore radius distribution of the activated carbon obtained in Example 4, and the cumulative pore volume with respect to the pore radius.

6 is a graph showing graphs showing sound pressure characteristics of the speaker device manufactured in Example 5 and a comparative speaker device, and electrical impedance characteristics of these devices.

7 is a graph showing graphs showing the sound pressure characteristics of the speaker device manufactured in Example 8 and a comparative speaker device, and the electrical impedance characteristics of these devices.

Fig. 8 is a graph showing the pore radius distribution of the activated carbon obtained in Example 9, and the cumulative pore volume with respect to the pore radius.

9 is a graph showing curves showing sound pressure characteristics of the speaker device manufactured in Example 11 and when it was placed under high humidity.

10 is a graph showing a speaker device manufactured in Example 12 and a curve showing sound pressure characteristics when it is placed under high humidity.

Detailed ways

(A)Material which raised sound pressure level in bass reproduction limit

The material for increasing the sound pressure level at the bass reproduction limit of the present invention (hereinafter, in this specification, simply referred to as "the material for increasing the sound pressure level") includes a material with a radius of 50 The following cumulative pore volume is 0.4ml/g or more activated carbon. The activated carbon has a radius of 7 The following cumulative pore volume is preferably 0.1 ml/g or less.

When the above radius is 50 When the following cumulative pore volume is less than 0.4 ml/g, the gas molecules in the speaker cabinet cannot be sufficiently adsorbed, and therefore, the drop in the sound pressure level in the low range cannot be sufficiently recovered in the obtained speaker device. 7 in activated carbon When the following cumulative pore volume is 0.1 ml/g or more, in the speaker device obtained, it may not be possible to sufficiently recover the drop in the sound pressure level in the low range.

In particular, in order to further effectively realize bass reproduction in small speaker devices, the sound pressure level raising material of the present invention preferably includes a radius of 18 Activated carbon with a cumulative pore volume of 0.5 ml/g or more. Radius is 18 The following cumulative pore volume is more preferably 0.6 ml/g or more. 7 of the activated carbon The cumulative pore volume below is more preferably 0.1 ml/g or below. The activated carbon has a radius of 18 The above cumulative pore volume is preferably 0.2 ml/g or less, more preferably 0.1 ml/g or less.

In this case, when the above radius is 18 When the following cumulative pore volume is less than 0.5 ml/g, the adsorption of gas molecules in the speaker box is insufficient, and for this reason, in the obtained speaker device, there is a case where the sound pressure level drop in the low range cannot be fully recovered. . 7 in activated carbon When the following cumulative pore volume is 0.1ml/g or more, or the radius is 18 When the above cumulative pore volume exceeds 0.2 ml/g, in the obtained speaker device, the drop in the sound pressure level in the low range may not be sufficiently recovered.

On the other hand, in order to more effectively realize bass regeneration under a relatively high humidity atmosphere, the activated carbon used in the material for improving the sound pressure level of the present invention preferably has a pore radius of 18 to 50 The cumulative pore volume in the range of 0.4 ml/g or more. The cumulative pore volume in this range is more preferably 0.5 ml/g or more. Activated carbon having such a pore size characteristic has moisture resistance. Here, activated carbon "has moisture resistance" means that when the activated carbon is left in an atmosphere at a temperature of 30°C and a relative humidity of 70% for 48 hours, the amount of water absorbed per 1 g of the activated carbon is 200 mg or less. The water adsorption amount is preferably 100 mg or less.

Therefore, when such activated carbon is placed in the casing of the above-mentioned speaker device, the amount of water adsorbed by the activated carbon is low even in a relatively high-humidity atmosphere. Therefore, the adsorption and desorption of the gas molecules in the cabinet can be sufficiently performed, and as a result, a sufficient bass reproduction effect can be obtained. When the radius of the pores in activated carbon is 18 to 50 When the cumulative pore volume in the range of 0.4 ml/g is less than 0.4 ml/g, the drop in the sound pressure level in the low range cannot be sufficiently recovered in a high-humidity atmosphere.

In this case, the aforementioned activated carbon has a radius of 18 The following cumulative pore volume is more preferably 0.2 ml/g or less, still more preferably 0.1 ml/g or less. When the radius is 18 When the cumulative pore volume exceeds 0.2ml/g, the moisture adsorption tends to be relatively high in a region with a humidity of about 50 to 70%, and the speaker may not be able to obtain a sufficient bass reproduction effect.

The pore radius and cumulative pore volume of the activated carbon specified above were measured by the steam method shown below. In this method, the situation that the equilibrium water vapor pressure of the sulfuric acid aqueous solution utilizing a certain concentration is a fixed value, that is, the situation that there is a fixed relationship between the sulfuric acid concentration of the sulfuric acid aqueous solution and the equilibrium water vapor pressure, causes the specified water vapor pressure Space, which is used for determination. Specifically, the cumulative pore volume corresponding to a predetermined pore radius was obtained from a curve showing the relationship between the pore diameter and the cumulative pore volume prepared by the following method.

Activated carbon of a specified mass is placed in the gas phase of the adsorption chamber containing a sulfuric acid aqueous solution of a specified concentration, and is brought into contact with water vapor for 48 hours under the conditions of 1 atmosphere (absolute pressure) and 30°C to form an equilibrium state. Next, the mass of the activated carbon was measured, and the amount of mass increase was defined as the saturated adsorption amount of water of the activated carbon at 30°C.

The sulfuric acid aqueous solution used above has a value (P) of the equilibrium water vapor pressure (1 atmosphere (absolute pressure), value at 30°C) inherent to its concentration, at which water vapor is adsorbed at a specified In pores with a radius below the pore radius (r). The predetermined pore radius is obtained by a calculation formula expressing Kelvin in the following formula (I). In addition, the cumulative pore volume of pores below the pore radius corresponds to the volume of water at 30° C. corresponding to the saturated adsorption amount of water obtained by the above measurement.

r=-[2VmγcosΦ]/[RTln(P/P ₀ )] (I)

Here, r, Vm, γ, Φ, R, T, P, and _P0 have the following meanings:

r: pore radius (cm)

Vm: Molecular volume of water (cm ³ /mol) = 18.079 (30°C)

γ: Surface tension of water (dyne/cm) = 71.15 (30°C)

Φ: contact angle between capillary wall and water (°) = 55°

R: gas constant (erg/deg·mol) = 8.3143×10 ⁷

T: absolute temperature (K) = 303.15

P: Saturation vapor pressure (mmHg) shown by water in pores

P ₀ : 1 barometric pressure (absolute pressure) of water, saturated vapor pressure (mmHg) at 30°C = 31.824

As the above specified sulfuric acid aqueous solution, prepare 11 kinds of sulfuric acid aqueous solutions with a specific gravity of 0.025 intervals from 1.05 to 1.30, a sulfuric acid aqueous solution with a specific gravity of 1.35, and a sulfuric acid aqueous solution with a specific gravity of 1.40 (a total of 13 kinds of sulfuric acid aqueous solutions) , to carry out the above determination. Thus, in each measurement, the cumulative pore volume of pores smaller than the calculated pore radius is obtained. The cumulative pore volume obtained in this way is plotted against the pore radius to obtain a cumulative pore volume curve of the activated carbon. By differentiating this, a pore distribution curve can be obtained. For example, FIG. 3 shows a graph showing the pore radius distribution of the activated carbon obtained in Example 1, and the cumulative pore volume with respect to the pore radius.

Based on the cumulative pore volume curve of the activated carbon obtained in this way, the cumulative pore volume of the activated carbon within the range of the desired pore radius can be obtained.

The method of producing activated carbon used as the material for increasing the sound pressure level of the present invention is not particularly limited, and activated carbon having the above-mentioned predetermined cumulative pore volume may be selected from activated carbon obtained by a usual method of producing activated carbon. Generally, activated carbon used in the present invention is produced by sufficiently carbonizing a carbonaceous material and then activating it by gas activation, chemical activation, or the like.

As the above-mentioned carbonaceous material, mineral-based materials, plant-based materials, synthetic-based materials, and the like can be used. Examples of mineral materials include coal and petroleum materials (coal pitch, coke, etc.). Examples of plant-based materials include wood, charcoal, fruit shells (coconut shells, etc.), and various fibers. Among these, various fibers include natural fibers such as kapok and hemp, regenerated fibers such as rayon and viscose rayon, and semi-synthetic fibers such as cellulose acetate and cellulose triacetate. As above-mentioned synthetic materials, can enumerate various synthetic resins, for example polyamide resins such as nylon, polyvinyl alcohol resins such as vinylon, acrylic resins, polyacrylonitrile (Polyacrylonitrile) resins, polyamide resins such as polyethylene and polypropylene, etc. Olefin resins, polyurethane resins, phenolic resins, vinyl chloride resins, etc.

Among carbonaceous materials, plant-based materials and synthetic-based materials are particularly preferable, and for example, coconut shells, phenolic resins, and the like can be preferably used. The carbonaceous material may be used alone or in combination of two or more materials.

The shape of the carbonaceous material is not particularly limited. Materials in various shapes such as granular, powdery, fibrous, and sheet forms can be used. For the purpose of usability and effective performance, granular carbonaceous materials are preferably used for relatively large speaker devices, and fibrous or sheet-shaped carbonaceous materials are preferably used for small and thin speaker devices. The granular material can also be crushed or granulated. Examples of fibrous and sheet-like carbonaceous materials include sheet-processed products such as woven fabrics, non-woven fabrics, films, felts, papers, and formed plates.

The conditions for carbonizing the carbonaceous material are not particularly limited. For example, in the case of granular carbonaceous material, it can be used at a temperature of 300° C. or higher while flowing a small amount of inert gas into the batch type rotary kiln. conditions for processing.

The activation method after the carbonization of the carbonaceous material, as described above, can also use any method such as gas activation, chemical activation, etc., but from the point of obtaining activated carbon with high mechanical strength and the above-mentioned predetermined pore diameter, it is preferable to use gas. activation. Examples of the gas used in the gas activation method include water vapor, carbon dioxide gas, oxygen, LPG combustion exhaust gas, or a mixed gas thereof. In consideration of safety and reactivity, a gas containing water vapor (a gas containing water vapor at 10 to 50% by volume) is preferable.

The activation temperature is usually 700°C to 1100°C, preferably 800°C to 1000°C. However, the activation temperature, time, and heating rate are not particularly limited, and vary depending on the type, shape, size, desired pore size distribution, and the like of the selected carbonaceous material. Activated carbon obtained by activation can be used as it is, but practically, it is preferable to remove adhering components by acid washing, water washing, or the like.

The activated carbon thus obtained can be in a shape such as a particle shape or a sheet shape depending on the shape of the above-mentioned carbonaceous material. Alternatively, it may be pulverized further. If necessary, granular activated carbon having a desired particle size ranging from granular particles having a certain size to fine powder can be used. The sheet-shaped activated carbon can be in the form of cloth, felt, paper, plate, or the like. In addition, such activated carbon may be used individually or in mixture of 2 or more types.

The particle diameter of the activated carbon of the particles is usually 0.05 to 1.0 mm, preferably 0.1 to 0.3 mm. When the activated carbon is in the form of cloth, its thickness is usually 0.1 to 2.0 mm, preferably 0.3 to 1.0 mm. An activated carbon cloth with a thickness of less than 0.1 mm is difficult to use because of its low strength, and an activated carbon cloth with a thickness exceeding 2.0 mm is difficult to produce. In the case of a felt shape, a paper shape, or a plate shape, the thickness thereof is usually 0.1 to 10.0 mm, preferably 0.3 to 5.0 mm. Under the above-mentioned size conditions, even when used in a speaker device, a particularly suitable bass reproduction effect can be obtained.

(B) Speaker device

One embodiment of the loudspeaker device of the present invention is illustrated in FIG. 1 . The speaker device 1 of the present invention has a cabinet 10 , a speaker unit 11 attached to the cabinet 10 , and a sound pressure level raising material 12 arranged in a cavity R1 inside the cabinet 10 . The sound pressure level raising material 12 includes activated carbon having the aforementioned prescribed cumulative pore volume. In the case where the sound pressure level raising material 12 is in the form of fibers or sheets, it can be directly arranged at an appropriate position of the cavity R1 in the housing 10 . In the case of granular or powdery activated carbon, it is preferably packaged in an air-permeable packaging material such as woven or non-woven fabric, and placed in the box 10 . The amount of the sound pressure level raising material 12 varies depending on the capacity of the case 10, the shape of the sound pressure level raising material 12, etc., and is not particularly limited.

The chamber R1 is usually filled with air at normal pressure, but may be filled with a specific gas such as carbon dioxide.

In FIG. 1, when an electric signal is applied to the speaker unit 11, a force is generated on the voice coil, causing the cone-shaped diaphragm to vibrate and produce sound. The sound pressure generated by the tapered diaphragm increases the internal pressure of the chamber R1. However, since the sound pressure level raising material 12 including activated carbon is arranged in the cavity R1, the pressure fluctuation in the cavity R1 is suppressed by the adsorption and desorption of the gas of the sound pressure level raising material 12, The empty chamber R1 is equivalently large in volume. That is, the above-mentioned speaker device 1 operates in such a manner that a speaker unit is mounted on a large-capacity box.

Since the above-mentioned sound pressure level raising material 12 has the above-mentioned predetermined cumulative pore volume, the equivalent volume of the case 10 becomes larger than that of the case where normal activated carbon is used. The theoretical expansion ratio of the equivalent volume of the housing 10 can be represented by the following formula as "volume expansion ratio".

Assuming that the resonance frequency of the speaker unit 11 used is f ₀ , f ₀ is represented by the following equation (1).

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Here, M _ms is the mass of the loudspeaker vibration system, and C _ms represents the compliance of the loudspeaker support system.

Assuming that the resonance frequency when the speaker unit 11 is mounted on the cabinet 10 is f _0B , f _0B is represented by the following equation (2).

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; B</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; mA</span>}}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; mA</span>}}}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Here, C _mA represents the air compliance of the box capacity.

The material 12 that improves the sound pressure level of the bass reproduction limit is arranged inside the box body 10, and the equivalent capacity of the box body 10 is enlarged to A times. When the resonant frequency at this time is f _0C , then f _0C is by the following Formula (3) expresses.

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; mA</span>}}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; ms</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; mA</span>}}}<span\; class="notranslate">\; )</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Using the above formulas (1), (2), and (3), the volume expansion ratio A is represented by the following formula (4).

$\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; =</span>\frac{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; C</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}\mathrm{<span\; class="notranslate">\; B</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

In the present invention, the above-mentioned volume expansion ratio of the speaker device 1 varies depending on the type and amount of the material 12 used to increase the sound pressure level, the capacity of the box 10, etc., but it is different from the case of using activated carbon in the existing speaker device In comparison, higher effects can be obtained.

Another embodiment of the speaker device of the present invention is illustrated and described in FIG. 2 . The speaker device 2 of the present invention has a cabinet 20 , a speaker unit 21 attached to the cabinet 20 , and a sound pressure level raising material 22 arranged in a cavity R2 inside the cabinet 20 . This speaker device 2 is a bass reflex type speaker device having a bass reflex port 23 in a cabinet 20 . The form of the speaker device 2 of the present invention is not particularly limited, and may be a speaker device of a sealed system.

The above-mentioned material 22 for increasing the sound pressure level comprises activated carbon with the above-mentioned prescribed cumulative pore volume, preferably comprising a pore radius of 18 to 50 Activated carbon with a cumulative pore volume in the range of 0.4ml/g or more. When the sound pressure level raising material 22 is in the form of a fiber or a sheet, it can be directly arranged at an appropriate position of the cavity R2 in the housing 20 . In the case of granular or powdery activated carbon, it is preferably packaged in an air-permeable packaging material such as woven fabric or nonwoven fabric, and placed in the box 20 . The amount of the sound pressure level raising material 22 varies depending on the volume of the box 20, the shape of the sound pressure level raising material 22, etc., and is not particularly limited.

The speaker device 2 in FIG. 2 is a speaker device of a bass reflex type having a bass reflex port (acoustic port) 23 inside a cabinet 20 . The purpose of the bass reflex method is to adjust the size and length of the opening of the bass reflex port 23, so that the sound emitted to the back of the speaker unit 21 resonates with the volume of the cavity R2 and is taken out, so that the sound located in the low frequency region pressure increased. Since the bass reflex port 23 can circulate air inside and outside the box body 20, when the humidity of the outside air is high, the humidity inside the box body 20 also becomes high. For example, the material 22 that increases the sound pressure level has a radius of 18-50 In the case of activated carbon having a cumulative pore volume of 0.4 ml/g or more, it has sufficient moisture resistance. Therefore, even if the speaker device 2 is used in a high-humidity atmosphere, it is difficult for the activated carbon to adsorb moisture.

In FIG. 2, when an electric signal is applied to the speaker unit 21, a force is generated on the voice coil, causing the cone diaphragm to vibrate and emit sound. The sound pressure generated by the tapered diaphragm increases the internal pressure of the chamber R2. However, since the sound pressure level raising material 22 including moisture-resistant activated carbon is arranged in the cavity R2, the gas adsorption and desorption functions of the activated carbon can be effectively exhibited even under high humidity. As a result, pressure fluctuations in the chamber R2 are suppressed, and the chamber R2 has an equivalently large volume. Therefore, a sufficient bass reproduction effect can be obtained even under high humidity, and an acoustic effect equivalent to the case of using a large-capacity cabinet can be obtained.

Example

(Example 1)

Coconut shells are carbonized to obtain carbonized products, which are activated with combustion gas containing water vapor at 850°C to obtain granular activated carbon with an average particle size of 0.35 mm. A cumulative pore volume curve and a pore distribution curve of the activated carbon are shown together in FIG. 3 . In FIG. 3, a1 is a cumulative pore volume curve, and b1 is a pore distribution curve. The value on the vertical axis of the cumulative pore volume curve a1 represents the cumulative pore volume (ml/g) per 1 g of activated carbon. The vertical axis of the pore distribution curve b1 represents a relative value. The activated carbon has a radius of 18 The following cumulative pore volume is 0.52ml/g, and the radius is 18-50 The cumulative pore volume is 0.03ml/g.

Fig. 4 is a graph showing the water adsorption amount (g) per 1 g of the activated carbon with respect to the relative humidity. This graph is a graph prepared from the relative humidity calculated from the water vapor pressure corresponding to various sulfuric acid concentrations in the above-mentioned steam method, and the corresponding water adsorption amount. In FIG. 4 , the unit (g/g-AC) on the vertical axis represents the amount of water adsorbed per 1 g of activated carbon.

(Example 2)

A carbonized product was obtained by carbonizing phenolic resin fibers, which were activated with a combustion gas containing water vapor at 850° C. to obtain cloth-like activated carbon with an average thickness of 0.50 mm. The activated carbon has a radius of 18 The following cumulative pore volume is 0.72ml/g, and the radius is 18-50 The cumulative pore volume is 0.00ml/g. FIG. 4 shows a graph of the same water adsorption amount as in Example 1 for this activated carbon.

(Example 3)

Coconut shells were carbonized to obtain carbonized products, which were activated with combustion gas containing water vapor at 860°C to obtain granular activated carbon with an average particle size of 0.30 mm. The activated carbon has a radius of 18 The following cumulative pore volume was 0.53 ml/g.

(comparative example 1)

Coal was granulated to obtain a carbonized product, which was activated at 900° C. with a combustion gas containing water vapor, and then pulverized to obtain granular activated carbon with an average particle diameter of 0.28 mm. The activated carbon has a radius of 50 The following cumulative pore volume is 0.35ml/g, and the radius is 18 The cumulative pore volume below is 0.20 ml/g.

(Example 4)

Coal was granulated to obtain a carbonized product, which was activated at 880° C. with a combustion gas containing water vapor, and then pulverized to obtain granular activated carbon with an average particle diameter of 0.27 mm. The cumulative pore volume curve a2 and pore distribution curve b2 of this activated carbon are shown together in FIG. 5 . The activated carbon has a radius of 50 The following cumulative pore volume is 0.47ml/g, and the radius is 18 The following cumulative pore volume was 0.33 ml/g.

(Example 5)

Prepare the speaker unit shown in Figure 1. This speaker device is a sealed speaker device in which a speaker unit 11 with a diameter of 8 cm is attached to a box 10 with an internal volume of 0.5 L. The resonance frequency of this speaker unit is 76Hz. 40 g of activated carbon obtained in Example 1 was packed in air-permeable woven cloth and placed in the cavity R1 of the speaker device as the material 12 for increasing the sound pressure level at the bass reproduction limit.

A 1 W sine wave electrical input was applied to the speaker unit, and a measurement microphone was placed at a distance of 1 m from the speaker unit to measure the sound pressure. The measurement of the impedance of the speaker device was also carried out. As a control, the measurement was performed in the same manner on a speaker device in which activated carbon was not loaded.

Curve C1 in FIG. 6 is a curve (frequency response curve) showing the sound pressure characteristics of the speaker device of this embodiment, and curve C2 is a frequency response curve of the speaker device for comparison. The vertical axis represents sound pressure (dB), and the left end of the graph represents its value. Compared with the curve C2, the curve C1 shows a high sound pressure level in the low frequency range of 20 to 100 Hz, and it can be seen that the bass is well reproduced.

A curve C3 in FIG. 6 is an electrical impedance curve of the speaker device of this embodiment, and shows a change in electrical impedance accompanying a change in frequency. Likewise, curve C4 is the electrical impedance curve of the above-mentioned comparative speaker device. The vertical axis represents electrical impedance (Ω), and the value is represented at the right end of the graph. The peak around 100 to 200 Hz indicates the resonant frequency (f ₀ ) of the speaker. The bass is reproduced more favorably as the peak shifts toward the lower frequency side.

The resonant frequency (f ₀ ) of the speaker unit used is 76 _Hz , and as shown in FIG. The resonant frequency f _0C inside the box is 122Hz. Therefore, from the above formula (4), it can be seen that the volume expansion ratio of the speaker device is 1.71.

(Example 6 and 7)

Using the activated carbon obtained in Examples 2 and 3, the same test as in Example 5 was performed, and the volume expansion rate was calculated. The volume expansion ratios of the activated carbons obtained in Examples 2 and 3 were 2.16 and 1.33, respectively.

(Embodiment 8)

In the same apparatus as in Example 5, it was tested similarly to Example 5 except having used the activated carbon obtained in Example 4 instead of the activated carbon obtained in Example 1.

Curve C5 of Fig. 7 is the frequency response curve of the loudspeaker device of the present embodiment, and curve C6 is the frequency response curve of the loudspeaker device of comparison. The units of the vertical axis are the same as those in Example 5 above. Curve C5 shows a slightly higher sound pressure level in the low-frequency region of 20 to 100 Hz than curve C6.

Curve C7 in FIG. 7 is the electrical impedance curve of the speaker device of this embodiment, and curve C8 is the electrical impedance curve of the above-mentioned comparative speaker device. The units of the vertical axis are the same as those in Example 5 above. The peak around 100 Hz to 200 Hz indicates the resonant frequency (f ₀ ) of the speaker. The volume expansion ratio of the speaker device was calculated in the same manner as in Example 5, and found to be 1.13.

(comparative example 2)

Using the activated carbon obtained in Comparative Example 1, the same test as in Example 5 was performed, and the volume expansion rate was calculated. As a result, the volume expansion ratio was 0.97.

(Example 9)

Coal was granulated to obtain a carbonized product, which was activated at 880° C. with a combustion gas containing water vapor, and then pulverized to obtain granular activated carbon with an average particle diameter of 0.35 mm. The cumulative pore volume curve and pore distribution curve of this activated carbon are shown together in FIG. 8 . In FIG. 8, a3 is a cumulative pore volume curve, and b3 is a pore distribution curve. The activated carbon has a radius of 18 to 50 The cumulative pore volume is 0.62ml/g. With regard to this activated carbon, FIG. 4 collectively shows a graph showing the same water adsorption capacity as in Example 1.

(Example 10)

Coal was granulated to obtain a carbonized product, which was activated with a combustion gas containing water vapor at 900° C. to obtain granular activated carbon with an average particle diameter of 0.32 mm. The activated carbon has a radius of 18 to 50 The cumulative pore volume is 0.71ml/g. With regard to this activated carbon, FIG. 4 collectively shows a graph showing the same water adsorption capacity as in Example 1.

(Example 11)

Prepare the speaker unit shown in Fig. 2 . This speaker device is a speaker device of a bass reflex type in which a cone-shaped speaker unit 21 with a diameter of 8 cm is mounted in a box 20 having an inner volume of 0.8 L provided with a bass reflex port 23 . The activated carbon 40 obtained in Example 9 was packed in air-permeable woven cloth and placed in the cavity R2 of the speaker device as the material 22 for increasing the sound pressure level at the bass reproduction limit.

A 1 W sine wave electrical input was applied to the speaker unit, and a measurement microphone was placed at a distance of 1 m from the speaker unit to measure the sound pressure. As a control, the same measurement was performed about the speaker device which did not mount activated carbon.

Next, the speaker device with activated carbon was left in an atmosphere with a humidity of 70% for 24 hours. After standing, the sound pressure of the speaker device having activated carbon was measured in the same manner.

Curve C9 of FIG. 9 is a curve (frequency response curve) showing the sound pressure characteristics of the original speaker device produced in this embodiment, and curve C10 is the frequency response of the speaker device after being placed in an atmosphere with a humidity of 70% for 24 hours. curve. Curve C11 is the frequency response curve of the comparative loudspeaker device. Compared with the curve C11, the curve C9 shows a high sound pressure level in the low-frequency range of 30 to 100 Hz, and it can be seen that the bass is well reproduced. The curve C10 showing the sound pressure characteristics after being left in an atmosphere with a humidity of 70% is substantially the same as the curve C9, and it can be seen that a sufficiently high sound pressure level can be obtained in the bass range even under high humidity.

(Example 12)

In the same apparatus as in Example 11, it was tested similarly to Example 11 except having used the activated carbon obtained in Example 1 instead of the activated carbon obtained in Example 9.

Curve C12 in FIG. 10 is the frequency response curve of the speaker device produced in this embodiment, and curve C13 is the frequency response curve after the speaker device was placed in an atmosphere with a humidity of 70% for 24 hours. Curve C14 is the frequency response curve of the control loudspeaker device. Compared with the curve C14, the curve C12 shows a high sound pressure level in the low frequency range of 30 to 100 Hz, and it can be seen that the bass is well reproduced. However, the part of the frequency range of the curve C13 representing the sound pressure characteristic after being left in an atmosphere with a humidity of 70% is similar to the comparative curve C14, and it is obvious that a high sound pressure level cannot be obtained in the bass range under high humidity.

Industrial availability

When the material for increasing the sound pressure level of the present invention is placed in the cabinet of a speaker device, pressure fluctuations in the gas inside the cabinet caused by vibration of the speaker can be alleviated, and a good bass reproduction effect can be obtained. In particular, when the activated carbon has a radius of When the following sound pressure level-increasing material having a cumulative pore volume of 0.5 ml/g or more is placed in the cabinet of the speaker device, the same acoustic effect can be obtained as when a large-capacity cabinet is used. On the other hand, activated carbon has a radius of Materials that increase the sound pressure level with a cumulative pore volume of 0.4 ml/g or more are less likely to absorb moisture even in a relatively high-humidity atmosphere. Therefore, when the material for increasing the sound pressure level is placed in the box of the speaker device, the gas in the box can be easily adsorbed and desorbed even in a relatively high-humidity atmosphere. As a result, even in a high-humidity Even in the atmosphere, sufficient bass reproduction effect can be obtained. The material for increasing the sound pressure level of the present invention can be used favorably in any of the speaker devices of the sealing type and the bass reflex type, and a speaker device having a good bass reproduction effect can be obtained.

Claims (2)

1. A material that increases the sound pressure level at the bass reproduction limit, wherein, by radius The following cumulative pore volume is 0.5ml/g or more and the radius The above-mentioned cumulative pore volume is 0.2ml/g or less activated carbon, and the radius of the activated carbon is The following cumulative pore volume is 0.1 ml/g or less. 2. A speaker device having: a cabinet; a speaker unit mounted on the cabinet; and a material arranged in a cavity inside the cabinet to improve the sound pressure level at the bass reproduction limit, wherein, The material for increasing the sound pressure level is packaged in an air-permeable packaging material, The material that increases the sound pressure level is determined by the radius The following cumulative pore volume is 0.5ml/g or more and the radius The above cumulative pore volume is 02ml/g or less activated carbon, and the radius of the activated carbon is The following cumulative pore volume is 0.1 ml/g or less.