JP4989342B2 - Speaker device material and speaker device using the same - Google Patents

Description

  The present invention relates to an adsorption material for a speaker device that can effectively realize low-frequency reproduction in a small speaker device, and a speaker device using the same.

  In general, in a small speaker device, since the volume of the speaker cabinet is small, it is difficult to reproduce low sound due to the effect of acoustic stiffness. That is, when an electrical signal is applied to the speaker, the air in the cabinet is compressed by the vibration of the speaker, and this acts as an air spring that prevents the speaker from moving. Regeneration cannot be achieved. In order to realize low-pitched sound reproduction in a small speaker device, a speaker device in which a gas adsorbing material such as activated carbon is arranged inside a cabinet has been proposed (for example, Patent Document 1).

  The speaker device of Patent Document 1 includes a speaker cabinet, a speaker attached to one surface of the cabinet such that a rear portion communicates with the interior of the cabinet, a gas contained in the cabinet, and an arrangement in the cabinet. Gas adsorbing material such as activated carbon. When an electric signal is applied to the speaker, the vibration in the speaker causes the gas in the cabinet to be compressed and expanded at a high speed. Along with this, the gas molecules are adsorbed and desorbed on the activated carbon, so that the pressure fluctuation in the cabinet is suppressed. As a result, it is disclosed that the sound pressure level in the bass portion is not suppressed and the same effect as that obtained when a large-capacity cabinet is used can be obtained.

There is a demand for further improvement of means for improving low-frequency reproduction in the above-described speaker device, particularly a gas adsorbing material such as activated carbon.
JP-T-60-500635

  The present invention solves the above-described conventional problems, and an object of the present invention is to use an adsorption material for a speaker device such as activated carbon that can more effectively realize low-frequency reproduction in a small speaker device, and the same. The object is to provide a speaker device.

  The inventors can obtain a sufficient gas adsorbing effect when the speaker vibrates when the activated carbon having a cumulative volume of pores having a pore size equal to or smaller than a predetermined size is 0.5 ml / g or more is placed in the cabinet of the speaker device. As a result, it has been found that bass reproduction is more effectively realized, and the present invention has been completed.

  The adsorbing material for a speaker device of the present invention is made of activated carbon having a radius of 18 mm or less and a cumulative pore volume of 0.5 ml / g or more.

  The speaker device of the present invention is a speaker device having a cabinet, a speaker unit attached to the cabinet, and a speaker device adsorption material disposed in an empty space inside the cabinet, the speaker device adsorption material Is made of activated carbon having a cumulative pore volume of 0.5 ml / g or more with a radius of 18 mm or less.

  According to one embodiment, the cumulative pore volume of the activated carbon having a radius of 7 mm or less is 0.1 ml / g or less.

  When the adsorbing material for a speaker device of the present invention is placed in the cabinet of the speaker device, the pressure fluctuation of the gas in the cabinet caused by the vibration of the speaker is alleviated, a sufficient bass reproduction effect can be obtained, and a large-capacity cabinet The acoustic effect equivalent to the case of using is obtained.

(A) Adsorbing material for speaker device The adsorbing material for speaker device of the present invention is made of activated carbon having a cumulative pore volume of 0.5 ml / g or more having a radius of 18 mm or less. The cumulative pore volume at a radius of 18 mm or less is preferably 0.6 ml / g or more. The accumulated pore volume of 7% or less of this activated carbon is preferably 0.1 ml / g or less. The cumulative pore volume of the activated carbon at a radius of 18 mm or more is preferably 0.2 ml / g or less, more preferably 0.1 ml / g or less.

  If the cumulative pore volume at the radius of 18 mm or less is less than 0.5 ml / g, the adsorption of gas molecules in the speaker cabinet is not sufficient, and therefore the sound pressure level in the low sound range is reduced in the obtained speaker device. Cannot recover sufficiently. When the cumulative pore volume of activated carbon of 7 mm or less is 0.1 ml / g or more, or when the cumulative pore volume of radius 18 mm or more exceeds 0.2 ml / g, in the obtained speaker device, In some cases, the decrease in sound pressure level cannot be fully recovered.

  The pore radius and cumulative pore volume of the activated carbon defined above are measured by the water vapor method shown below. In this method, the equilibrium water vapor pressure of a sulfuric acid aqueous solution having a constant concentration becomes a constant value, that is, a predetermined relationship is established between the sulfuric acid concentration of the sulfuric acid aqueous solution and the equilibrium water vapor pressure. This space is created and measured using this. Specifically, the cumulative pore volume corresponding to a predetermined pore radius is obtained based on a curve indicating the relationship between the pore diameter and the cumulative pore volume created by the following method.

  A predetermined mass of activated carbon is placed in the gas phase portion of the adsorption chamber containing a sulfuric acid aqueous solution having a predetermined concentration, and brought into contact with water vapor at 48 ° C. for 48 hours under the conditions of 1 atm (absolute pressure) and 30 ° C. Next, the mass of the activated carbon is measured, and the mass increase is defined as the saturated adsorption amount of water of the activated carbon at 30 ° C.

  The sulfuric acid aqueous solution adopted above has an equilibrium water vapor pressure value (P) (1 atm (absolute pressure), a value at 30 ° C.) inherent to the concentration, and the water vapor pressure has a predetermined pore radius ( r) Water vapor is adsorbed in the pores having the following radii. The predetermined pore radius is obtained based on the Kelvin equation represented by the following equation (I). And 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)
Where r, Vm, γ, Φ, R, T, P, and P ₀ 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 the capillary wall and water (°) = 55 °
R: Gas constant (erg / deg · mol) = 8.3143 × 10 ⁷
T: Absolute temperature (K) = 303.15
P: saturated vapor pressure (mmHg) indicated by water in the pores
P ₀ : 1 atm (absolute pressure) of water, saturated vapor pressure (mmHg) at 30 ° C. = 31.824

  As the predetermined sulfuric acid aqueous solution, eleven types of sulfuric acid aqueous solutions having a specific gravity of 0.025 intervals from a specific gravity of 1.05 to 1.30, a sulfuric acid aqueous solution having a specific gravity of 1.35, and sulfuric acid having a specific gravity of 1.40. An aqueous solution (a total of 13 types of sulfuric acid aqueous solutions) is prepared, and the above measurement is performed. Thereby, in each measurement, the cumulative pore volume of pores not more than the calculated pore radius is obtained. By plotting the cumulative pore volume thus determined against the pore radius, a cumulative pore volume curve of activated carbon can be obtained. By differentiating this, a pore distribution curve is obtained. For example, FIG. 2 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 thus obtained, a cumulative pore volume of 18 cm or less in the activated carbon is determined.

  The production method of the activated carbon used as the adsorbing material of the present invention is not particularly limited, and activated carbon having the predetermined cumulative pore volume may be selected from the activated carbons obtained by the usual activated carbon production method. Usually, the activated carbon used in the present invention is produced by sufficiently carbonizing a carbonaceous material and then activating it by a method such as gas activation or drug activation.

  As the carbonaceous material, mineral materials, plant materials, synthetic materials and the like are used. Examples of the mineral materials include coal / petroleum materials (coal pitch, coke, etc.). Examples of plant materials include wood, charcoal, fruit shells (coconut shells, etc.), and various fibers. Among these, various fibers include natural fibers such as cotton and hemp, regenerated fibers such as rayon and viscose rayon, and semi-synthetic fibers such as acetate and triacetate. Examples of the synthetic material include various synthetic resins. Examples thereof include polyamide resins such as nylon, polyvinyl alcohol resins such as vinylon, acrylic resins, polyacrylonitrile resins, polyolefin resins such as polyethylene and polypropylene. , Polyurethane resins, phenol resins, vinyl chloride resins, and the like.

  Of the carbonaceous materials, plant materials and synthetic materials are particularly suitable. For example, coconut shells and phenolic resins are preferably used. Two or more kinds of carbonaceous materials may be mixed and used.

  The shape of the carbonaceous material is not particularly limited. Various shapes of materials such as granular, powder, fiber, and sheet can be used. For the purpose of handling and effective performance, granular carbonaceous materials are used for relatively large speaker devices, and fibrous or sheet-like carbonaceous materials are used for small and thin speaker devices. It is preferably used. The granular material may be crushed or granulated. Examples of the fibrous and sheet-like carbonaceous materials include sheet processed products such as woven fabric, non-woven fabric, film, felt, paper, and molded plate.

  The conditions for carbonizing the carbonaceous material are not particularly limited. For example, in the case of a granular carbonaceous material, conditions such as processing at a temperature of 300 ° C. or higher while flowing a small amount of inert gas through a batch rotary kiln are adopted. be able to.

  As described above, the activation method after carbonizing the carbonaceous material may employ any method such as gas activation and drug activation, but it has high mechanical strength and obtains activated carbon having the predetermined pore diameter. In terms of gas activation, gas activation is preferably employed. 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 water vapor-containing gas (a gas containing 10 to 50% by volume of water vapor) is preferable.

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

  The activated carbon thus obtained can be in the form of particles, sheets, etc., depending on the shape of the carbonaceous material. Or you may grind | pulverize this further. As the particulate activated carbon, particles having a desired particle size can be used as needed from granular particles having a certain size to fine powders. The sheet-like activated carbon may be in the form of a fabric, felt, paper, plate or the like.

  The particle size of the activated carbon is usually 0.05 to 1.0 mm, preferably 0.1 to 0.3 mm. When the activated carbon is in the form of a fabric, the thickness is usually 0.1 to 2.0 mm, preferably 0.3 to 1.0 mm. An activated carbon fabric having a thickness of less than 0.1 mm is difficult to handle due to its low strength, and an activated carbon fabric having 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 is usually 0.1 to 10.0 mm, preferably 0.3 to 5.0 mm. In any of the above sizes, a particularly suitable bass reproduction effect can be obtained when used in a speaker device.

(B) Speaker Device The speaker device of the present invention will be described with reference to FIG. The speaker device 1 of the present invention includes a cabinet 10, a speaker unit 11 attached to the cabinet, and a speaker device adsorption material 12 disposed in a vacant space R inside the cabinet. The speaker material adsorbing material 12 is made of activated carbon having the predetermined cumulative pore volume. When the activated carbon is in the form of a fiber or a sheet, it can be placed in an appropriate place in the empty room R in the cabinet as it is. In the case of granular or powdered activated carbon, it is preferable that the activated carbon is packaged with a wrapping material having air permeability such as a woven fabric or a non-woven fabric and disposed in the cabinet. The amount of the speaker device adsorption material 12 varies depending on the capacity of the cabinet, the shape of the activated carbon, and the like, and is not particularly limited.

  The vacancies R are usually filled with atmospheric pressure air, 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 in the voice coil, and the cone-type diaphragm is vibrated to generate sound. The sound pressure generated by the cone-shaped diaphragm increases the internal pressure of the empty room R. However, because the speaker device adsorbing material 12 made of activated carbon is disposed in the vacant chamber R, the pressure fluctuation in the vacant chamber R is suppressed by the adsorption and desorption action of the gas of the activated carbon, and the vacant chamber R is equivalent to Large volume. That is, the speaker device 1 operates as if the speaker unit is attached to a cabinet with a large volume.

  Since the activated carbon has the predetermined cumulative pore volume, the equivalent volume of the cabinet is larger than when ordinary activated carbon is used. The theoretical expansion rate of the equivalent volume of the cabinet can be expressed by the following formula as “volume expansion rate”.

When the resonance frequency of the speaker unit to be used to f _o, f _o is expressed by the following equation (1):

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

If the resonance frequency when this speaker is attached to the cabinet is f _OB , f _OB is expressed by the following equation (2):

Here, C _mA indicates the air compliance of the cabinet capacity.

When activated carbon is arranged inside the cabinet and the equivalent capacity of the cabinet is expanded A times, and the resonance frequency at this time is f _oc , f _oc is expressed by the following equation (3):

  From the above equations (1), (2), and (3), the volume expansion rate A is expressed by the following equation (4):

In the present invention, the volume expansion rate of the speaker device varies depending on the type and amount of activated carbon used, the capacity of the cabinet, etc., but all have a higher effect than when using activated carbon in a conventional speaker device. Is obtained.

Example 1
The coconut shell was carbonized to obtain a carbide, which was activated with a steam-containing combustion gas at 850 ° C. to obtain granular activated carbon having an average particle size of 0.35 mm. The cumulative pore volume curve of this activated carbon is shown in FIG. 2 together with the pore distribution curve. In FIG. 2, 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 indicates the cumulative pore volume (ml / g) per gram of activated carbon. The vertical axis of the pore distribution curve b1 represents a relative value. The same applies to a2 and b2 in FIG. The cumulative pore volume of this activated carbon having a radius of 18 mm or less was 0.52 ml / g.

(Example 2)
The phenol resin fiber was carbonized to obtain a carbide, which was activated with a steam-containing combustion gas at 850 ° C. to obtain cloth-like activated carbon having an average thickness of 0.50 mm. The cumulative pore volume of this activated carbon having a radius of 18 mm or less was 0.72 ml / g.

(Example 3)
The coconut shell was carbonized to obtain a carbide, which was activated with a steam-containing combustion gas at 860 ° C. to obtain granular activated carbon having an average particle size of 0.30 mm. The cumulative pore volume of this activated carbon having a radius of 18 mm or less was 0.53 ml / g.

(Comparative Example 1)
Coal was granulated to obtain carbides, activated with a steam-containing combustion gas at 900 ° C., and then pulverized to obtain granular activated carbon having an average particle size of 0.28 mm. The cumulative pore volume of this activated carbon having a radius of 18 mm or less was 0.20 ml / g.

(Comparative Example 2)
Coal was granulated to obtain carbides, activated with steam-containing combustion gas at 880 ° C., and then pulverized to obtain granular activated carbon having an average particle size of 0.27 mm. The cumulative pore volume curve a2 of this activated carbon is shown in FIG. 3 together with the pore distribution curve b2. The cumulative pore volume of this activated carbon having a radius of 18 mm or less was 0.33 ml / g.

Example 4
The speaker device shown in FIG. 1 was prepared. This speaker device is a sealed speaker device in which a speaker unit 11 having a diameter of 8 cm is attached to a cabinet 10 having an internal volume of 0.5 L. The resonance frequency of this speaker unit is 76 Hz. In the vacant space R of the speaker device, 40 g of activated carbon obtained in Example 1 was packaged and placed on a breathable woven fabric as the speaker device adsorption material 12.

  A 1 W sine wave electric input was applied to the speaker unit, a measurement microphone was placed at a position 1 m away from the speaker device, and the sound pressure was measured. The impedance of the speaker device was also measured. As a control, the same measurement was performed on a speaker device on which no activated carbon was placed.

  A curve 21 in FIG. 4 is a curve (frequency response curve) showing the sound pressure characteristics of the speaker device of the present embodiment, and a curve 22 is a frequency response curve of the control speaker device. The vertical axis indicates the sound pressure (dB), and the value is displayed at the left end of the graph. The curve 21 shows a high sound pressure level in the low frequency region of 20 to 100 Hz as compared with the curve 22, and it can be seen that the low sound is reproduced well.

A curve 23 in FIG. 4 is an electrical impedance curve of the speaker device of the present embodiment, and shows a change in electrical impedance accompanying a change in frequency. Similarly, the curve 24 is an electric impedance curve of the control speaker device. The vertical axis shows electrical impedance (Ω), and the value is displayed on the right end of the graph. The peak in the vicinity of 100 Hz to 200 Hz represents the resonance frequency (f ₀ ) of the speaker. The lower the frequency, the better the bass is reproduced.
The resonance frequency (f ₀ ) of the speaker unit used is 76 Hz, and as shown in FIG. 4, the resonance frequency f _OB is 146 Hz when this speaker unit is attached to the cabinet (when there is no activated carbon). _{f oc} resonance frequency when placing the activated carbon is 122 Hz. Therefore, it can be seen from the above formula (4) that the volume expansion rate of this speaker device is 1.71.

(Examples 5-6)
Using the activated carbon obtained in Examples 2 and 3, the same test as in Example 4 was performed, and the volume expansion ratio was calculated. The volume expansion ratio of the activated carbon obtained in Examples 2 and 3 was 2.16 and 1.33, respectively.

(Comparative Example 3)
In the same apparatus as in Example 4, the test was performed in the same manner as in Example 4 except that the activated carbon obtained in Comparative Example 2 was used instead of the activated carbon obtained in Example 1.

  A curve 31 in FIG. 5 is a frequency response curve of the speaker device of this comparative example, and a curve 32 is a frequency response curve of the control speaker device. The unit of the vertical axis is the same as that in the fourth embodiment. The curve 31 shows a slightly higher sound pressure level in the low frequency region of 20 to 100 Hz compared to the curve 32, but is substantially similar, and the sound pressure level in the low frequency region is hardly improved. I understand that.

A curve 33 in FIG. 5 is an electrical impedance curve of the speaker device of this comparative example, and a curve 34 is an electrical impedance curve of the above-described control speaker device. The unit of the vertical axis is the same as that in the fourth embodiment. The peak in the vicinity of 100 Hz to 200 Hz represents the resonance frequency (f ₀ ) of the speaker. The volume expansion rate of the speaker device was calculated in the same manner as in Example 4, and was 1.13.

(Comparative Example 4)
Using the activated carbon obtained in Comparative Example 1, the same test as in Example 4 was performed, and the volume expansion ratio was calculated. As a result, the volume expansion rate was 0.97.

  When the adsorbing material for a speaker device of the present invention is placed in the cabinet of the speaker device, the pressure fluctuation of the gas in the cabinet caused by the vibration of the speaker is effectively suppressed. As a result, an acoustic effect equivalent to that of a speaker device using a large capacity cabinet can be obtained. The adsorbing material for a speaker device of the present invention can be used well for both a sealed type and a bass reflex type speaker device, and a speaker device having a good bass reproduction effect can be obtained.

It is a schematic cross section which shows one example of the speaker apparatus using the adsorption material for speaker apparatuses of this invention. It is a graph which shows the pore radius distribution of the activated carbon obtained in the Example of this invention, and the cumulative pore volume with respect to a pore radius. It is a graph which shows the pore radius distribution of the activated carbon obtained by the comparative example of this invention, and the cumulative pore volume with respect to a pore radius. It is a graph which shows the curve which shows the sound pressure characteristic of the speaker apparatus manufactured by the Example of this invention, and the control speaker apparatus, and the electrical impedance characteristic of these apparatuses. It is a graph which shows the curve which shows the sound pressure characteristic of the speaker apparatus manufactured by the comparative example of this invention, and the control speaker apparatus, and the electrical impedance characteristic of these apparatuses.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Speaker apparatus 10 Cabinet 11 Speaker unit 12 Adsorption material for speaker apparatuses

Claims (4)

An adsorbing material for a speaker device, comprising activated carbon having a cumulative pore volume of 0.5 ml / g or more with a radius of 18 mm or less and a cumulative pore volume of 0.2 ml / g or less with a radius of 18 mm or more .   The adsorbent material for a speaker device according to claim 1, wherein a cumulative pore volume of the activated carbon having a radius of 7 mm or less is 0.1 ml / g or less. A speaker device having a cabinet, a speaker unit attached to the cabinet, and a speaker device adsorbing material disposed in a vacant space inside the cabinet, wherein the speaker device adsorbing material has a breathable packaging material Packed in
The speaker device adsorbing material is made of activated carbon having a cumulative pore volume of radius 18 mm or less and a cumulative pore volume of 0.5 ml / g or more and a radius of 18 cm or more and a cumulative pore volume of 0.2 ml / g or less .   The speaker device according to claim 3, wherein a cumulative pore volume of the activated carbon having a radius of 7 mm or less is 0.1 ml / g or less.

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