JP2009094706A - Speaker system and box for speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controllable speaker system of sound pressure frequency characteristics without making a box for the speaker into a special shape. <P>SOLUTION: By supporting a sound absorption member 16 for reflecting and absorbing sound waves on a front baffle 17a surface of a box 17, a refraction effect by the box 17 can be controlled. Thus, in a sealed speaker system 10, sound pressure frequency feature and sound quality of the speaker unit 11 are not damaged. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a speaker system and a speaker box used for audio equipment.

As typical speaker systems currently on the market, a sealed speaker system, a bass reflex speaker system in which an acoustic port is mounted on the sealed speaker system, and a drone cone speaker system are mainstream. The shape of a speaker box (hereinafter simply referred to as a box) employed in these speaker systems is generally a rectangular parallelepiped. When the box is a rectangular parallelepiped, the sound pressure of the speaker system is caused by the sound diffraction effect, which is a factor that impairs the sound quality.
Therefore, in order to solve this problem, conventionally, the corners of the box are rounded, or the box is made oval or spherical to flatten the peaks and valleys of the sound pressure.
Patent Publication 2002-247675 Supervised by Tamon Saeki, “New Edition Speaker & Enclosure Encyclopedia”, 7th edition, 112 pages, Seibundo Shinkosha (issued on September 15, 2005)

However, the conventional box uses a material made of a rigid body (reflectance: approximately 1) such as wood or plastic. Therefore, when such a box made of a rigid body is made into a special shape, there are problems such as (a) high manufacturing costs and (b) restrictions on design.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such a problem and provide a speaker system capable of controlling sound pressure frequency characteristics without requiring a special box shape.

In order to solve the above problems and achieve the object, a speaker system of the present invention includes a speaker unit, a box in which the speaker unit is mounted, and a sound absorbing member that reflects and absorbs sound waves, and the sound absorbing member is a speaker. It is carried in the propagation space of the sound wave radiated from the front surface of the unit.

With the configuration as described above, the diffraction effect by the box can be controlled. Therefore, a speaker system that does not impair the sound pressure frequency characteristics and sound quality of the speaker unit can be realized. In addition, the diffraction effect can be controlled so as to suppress the peaks and valleys in the sound pressure frequency characteristics of the speaker unit. Therefore, a speaker system having a flat sound pressure frequency characteristic can be realized.

The mechanism by which the diffraction effect by the box is controlled by the sound-absorbing member has not been sufficiently theoretically analyzed yet, but the inventors have inferred as follows.
That is, when the sound wave emitted from the speaker unit collides with the sound absorbing member, the diffracted sound field formed by the sound wave reflected by the sound absorbing member is superimposed on the sound wave directly emitted from the speaker unit. The sound pressure frequency characteristic of the diffracted sound field varies depending on the reflectance and sound absorption coefficient of the sound absorbing member used. Therefore, it is presumed that the peaks and valleys of the sound pressure of the speaker system are flattened by appropriately selecting the reflectance and sound absorption coefficient of the sound absorbing member.

The speaker system of the present invention is characterized in that the sound absorbing member is carried on the speaker unit mounting surface of the box.
Further, the sound absorbing member is supported on the peripheral edge of the box.
Further, the sound absorbing member is carried on the speaker unit mounting surface and the peripheral portion of the box.

With the configuration as described above, it is possible to reduce the peaks and valleys of the sound pressure due to the diffraction effect.

The speaker system according to the present invention is characterized in that the sound absorbing member protrudes forward from the speaker unit mounting surface of the box.
With such a configuration, it is possible to flatten the peaks and valleys of the sound pressure of the speaker system.

Moreover, the speaker system of the present invention is characterized in that the sound absorbing member is composed of a plurality of materials having different reflectances and sound absorbing coefficients.
With such a configuration, it is possible to increase the degree of freedom in designing the peaks and valleys of the sound field due to the diffraction effect. The reason is that the discontinuity of the reflected wave from the sound absorbing member can be reduced and the reflected wave can be made smooth.

According to the speaker system of the present invention, it is possible to control the sound pressure of the sound field formed by the diffraction effect without using a special box as in the prior art. The effect which can be controlled is acquired. Therefore, the sound pressure frequency characteristic of the speaker system can be flattened. In addition, the degree of freedom in designing the shape and design of the box is increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings of FIGS.

(First embodiment)
1 and 3 to 5 are schematic views showing one configuration example of the speaker system according to the present invention. FIG. 2 is an explanatory diagram for explaining the arrangement of the sound absorbing members carried by the speaker system according to the present invention. In each drawing, the same constituent elements are given the same reference numerals, and duplicate descriptions are omitted.

Hereinafter, a sealed speaker system will be described as an example of the speaker system.
[Configuration of sealed speaker system]
FIG. 1 is a configuration example of a sealed speaker system using a dynamic speaker unit. FIG. 1A is a schematic cross-sectional view of a side surface of a sealed speaker system 10. FIG. 1B is a schematic front view of the sealed speaker system 10 as viewed from the arrow X shown in FIG. 1A.

In FIG. 1, 17 is a box made of a rigid body such as wood or plastic, 17a is a front baffle of the box 17, 11 is a speaker unit, 12 is a magnet of the speaker unit, 13 is a diaphragm of the speaker unit 11, and 14 is a speaker unit 11. , 15 is an edge of the speaker unit 11, and 16 is a sound absorbing member made of a material that reflects and absorbs sound waves radiated from the front surface of the diaphragm 13. The sealed speaker system 10 of the present embodiment has a configuration in which a sound absorbing member 16 is carried on the entire surface of a front baffle 17a of a speaker system (hereinafter referred to as a reference speaker system) in which a speaker unit 11 is mounted on a box 17. .

The thickness (t) of the sound absorbing member 16 may be set to a desired thickness according to the reflectance and sound absorption rate of the sound absorbing member 16 to be used, the sound pressure frequency characteristics of the speaker unit 11, the required sound quality, and the like. In general, the sound pressure peaks and valleys become small at a thickness of 40 mm or less. When the thickness (t) is greater than 40 mm, since the sound absorbing member 16 has a horn effect, the horn needs to have an appropriate shape. An optimum horn shape is effective in flattening the sound pressure because the peaks and valleys of the sound pressure are further reduced.

3 to 5 are configuration examples of other sealed speaker systems in which the sound absorbing member 16 is supported on the front baffle 17a. Only the configuration different from the sealed speaker system 10 described in FIG. 1 will be described here, and the description of the same configuration will be omitted.

The sealed speaker system 30 shown in FIG. 3 has a configuration in which the sound absorbing member 16 is supported in an annular shape along the outer edge of the speaker unit 11 and a part of the front baffle 17a is exposed.

4 has a configuration in which a part of the front baffle 17a is exposed in an annular shape along the outer edge of the speaker unit 11, and the sound absorbing member 16 is supported on the front baffle 17a of the other part. It has become.

As shown in FIGS. 3 and 4, when a part of the front baffle 17a is exposed, it can be made of materials having different reflectivities and sound absorption coefficients. With such a configuration, a sound quality in which the diffraction effect by the front baffle 17a and the diffraction effect by the sound absorbing member 16 are superimposed can be obtained, so that the degree of freedom in designing the sound quality is increased.

The sealed speaker system shown in FIG. 5 has a configuration in which the sound absorbing member 16 described in FIG. 1 is larger than the front baffle 17a. The shape of the sound absorbing member 16 may be such that the length of each side of the sound absorbing member 16 is longer than that of each side of the front baffle 17a, as shown in FIG. 5A. This form is particularly suitable for an embedded speaker system embedded in a wall or the like.

When the closed speaker system is used for installation on the floor, as shown in FIG. 5B, the lower side of the sound absorbing member 16 and the lower side of the front baffle 17a may be flush with each other.

By making the configuration of the sound absorbing member 16 as shown in FIG. 5, the diffraction effect by the sound absorbing member 16 is increased, so that the peak and valley of the sound pressure can be further reduced. Therefore, even if the speaker unit 11 having a large valley of sound pressure frequency characteristics is used, a speaker system having a small valley of sound pressure can be constructed.

As described above, the sound absorbing member 16 may be formed in a desired form according to the reflectance and sound absorbing rate of the sound absorbing member 16 to be used, the sound pressure frequency characteristics of the speaker unit 11, the required sound quality, and the like. Therefore, the form of the sound absorbing member 16 is not limited to the form described above. Next, the arrangement of the sound absorbing member 16 will be described.

[Arrangement of sound absorbing member]
FIG. 2 is an explanatory diagram for explaining the arrangement of the sound absorbing members 16 taking the reference speaker system described in FIG. 1 as an example. FIG. 2A is a cross-sectional space diagram showing a space near the cross section of the reference speaker system. FIG. 2B is a front space diagram showing a space near the front of the reference speaker system.

The sound absorbing member 16 may be provided at an arbitrary position in the space shown by hatching in FIG. That is, it is a space where sound waves radiated from the front surface of the diaphragm 13 of the speaker unit 11 are propagated, and excludes a space formed by translating the opening 21 of the box 17 forward (a front space of the diaphragm 13). What is necessary is just to provide in a position.
Next, an embodiment in which the arrangement of the sound absorbing member 16 is changed will be described.

(Second embodiment)
6 to 8 are schematic views showing a configuration example of a sealed speaker system in which the sound absorbing member 16 is provided on the peripheral edge portion of the box 17 of the reference speaker system described with reference to FIG. The only difference from FIG. 1 is the position where the sound absorbing member 16 is carried. Therefore, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description of the overlapping components is omitted. Only the components different from those in FIG.

The sealed speaker system 60 shown in FIG. 6 has a configuration in which the sound absorbing member 16 is provided in front of the peripheral portion of the front baffle 17a. That is, the sound absorbing member 16 is provided so that the front surface of the front baffle 17a and the front surface of the sound absorbing member 16 are flush with each other.

The sealed speaker system 70 shown in FIG. 7 is provided with the sound absorbing member 16 so that the lower part of the sound absorbing member 16 described in FIG. 6 is cut out so that the lower side of the sound absorbing member 16 and the lower side of the front baffle 17a are flush with each other. ing.

The sealed speaker system 80 shown in FIG. 8 has a configuration in which the sound absorbing member 16 described in FIG. 7 is arranged with a gap 82 and an outer wall of the box 17. The sound absorbing member 16 is carried on a support base 81 provided on the front baffle 17a, and is provided so that the surface of the front baffle 17a and the front surface of the sound absorbing member 16 are flush with each other.

By carrying the sound absorbing member 16 at the position shown in FIGS. 6 and 7, a sound quality in which the diffraction effect by the front baffle 17a and the diffraction effect by the sound absorbing member 16 are superimposed can be obtained. Therefore, since the sound quality can be controlled by changing the surface area of the sound absorbing member 16 and the surface area of the front baffle 17a, the degree of freedom in designing the sound quality is increased. Further, as shown in FIG. 8, when the gap 82 is provided between the sound absorbing member 16 and the box 17, a part of the sound wave from the speaker unit 11 passes through the gap 82, so that the sound quality can be further designed. The degree can be increased.

6 to 8, the front surface of the sound absorbing member 16 and the surface of the front baffle 17a are flush with each other. However, as shown in FIG. 9, the sound absorbing member 16 is configured to protrude forward from the surface of the front baffle 17a. Also good.
With such a configuration, in addition to the diffraction effect by the sound absorbing member 16, the horn effect by the protruded sound absorbing member 16 appears. Therefore, it is effective as a means for flattening the peaks and valleys of the sound pressure of the speaker system.

The horn effect increases in proportion to the protruding amount of the sound absorbing member 16. In general, it is desirable that the peak of the sound pressure is flattened when the protruding amount is 40 mm or more, preferably 60 mm or more.

(Third embodiment)
FIG. 10 is a schematic diagram illustrating a configuration example of the sealed speaker system 100 in which the sound absorbing member 16 described with reference to FIG. 5A is formed of materials having different reflectances and sound absorption rates. The difference from FIG. 5A is only the material configuration of the sound absorbing member 16, and the other configuration is the same as FIG. 5A. Accordingly, the same components as those in FIG. 5A are assigned the same reference numerals and description thereof is omitted, and only configurations different from those in FIG. 5A are described.

In FIG. 10, the sound absorbing member 16a carried on the surface of the front baffle 17a and the sound absorbing member 16b carried on the peripheral portion of the sound absorbing member 16a are made of materials having different reflectivities and sound absorption rates.
By adopting such a configuration, the discontinuity of the reflected wave between the sound absorbing members 16a and 16b and the air layer outside the box 17 can be reduced, and the reflected wave can be made smooth. Therefore, it is possible to further increase the degree of freedom in designing the peaks and valleys of the sound field due to the diffraction effect of the sound absorbing member.
FIG. 10 shows a configuration example using two types of sound absorbing members, that is, the sound absorbing members 16a and 16b, but may be configured by three or more types of sound absorbing members as required. Further, a composite sound absorbing member formed by combining a plurality of different sound absorbing materials may be used.

The speaker systems described above are all sealed speaker systems, but the speaker system according to the present invention can also be applied to bass reflex speaker systems, drone cone speaker systems, and the like. Next, an application example to a bass reflex type speaker system will be described.

[Configuration of bass reflex type speaker system]
FIG. 15 is a schematic diagram showing a configuration example of a bass reflex type speaker system according to the present invention. The bass reflex speaker system 150 shown in FIG. 15 has the same basic configuration as the sealed speaker system 10 shown in FIG. 1 except that the acoustic port 151 is attached to a part of the box 17. Therefore, the same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. Here, only a configuration different from FIG. 1 will be described.

As shown in FIG. 15, the sound absorbing member 16 is carried on the entire surface of the front baffle 17a. Note that the form of the sound absorbing member 16 is not limited to the form shown in FIG. 15, and it is needless to say that the form described in the first to third embodiments may be adopted.

[Configuration of sound absorbing member]
As the sound absorbing member 16 applicable to the present invention, any member that reflects and absorbs sound waves may be used. Specifically, any material may be used as long as it is a soft material in terms of acoustics, that is, a material having a sound wave reflectance (hereinafter simply referred to as reflectance) of less than 1. Examples of such a material include an open-cell foam or a semi-closed-cell foam resin / synthetic rubber in which closed cells and open cells are mixed.
Incidentally, the rigid bodies such as wood and plastic used in the conventional box all belong to a hard material and have a reflectance of about 1.

Open-celled foam or semi-closed-cell foamed foam is made of elastomer such as thermoplastic polyurethane, thermoplastic polyolefin, thermoplastic polystyrene, or synthetic rubber such as NBR, SBR, silicon rubber, ethylene propylene rubber, etc. There is. In order to make the reflectance of these foams smaller than 1, it is easily obtained by foaming so that the air permeability is 10 cc / cm ² / sec or less, preferably about 1 cc / cm ² / sec. An air permeability of 10 cc / cm ² / sec or less is preferable in that the diffraction effect is increased.
Generally, the reflectance of an open-cell foam or semi-closed-cell foam having an air permeability of 10 cc / cm ² / sec or less is 0.8 or less.

(Specific Example 1)
A reference speaker system in which the following speaker unit was mounted in a sealed box having an internal volume of 0.66 liters was prepared.
(Speaker unit standard)
Type of speaker unit: Dynamic type speaker unit “EAS8P170A” (manufactured by Panasonic Corporation)
Diameter: φ70mm
Impedance: 6Ω
Minimum resonance frequency (f ₀ ): 155 Hz
Reproduction frequency band: f _{0 to} 32 kHz
Output sound pressure level: 83.5dB / W (1m)
m ₀ : 2.4 g
Q ₀ : 1.2
(Configuration of sealed box)
Inner dimensions of the box: 110 x 100 x 60 mm depth
Box material: particle board (plate thickness: 15 mm, reflectivity: approximately 1)

Next, the sound absorbing member 16 shown below was adhered to the front baffle 17a of the box 17 to produce a sealed speaker system 10 as shown in FIG.
(Configuration of sound absorbing member 16)
Material of sound absorbing member: urethane foam (“DOX” manufactured by Bridgestone Corporation, air permeability: about 1 cc / cm ² / sec, reflectance: about 0.7)
Dimensions of sound absorbing member: 250 vertical × 220 horizontal × 20 mm thick
In addition, the normal incidence sound absorption coefficient of urethane foam "DOX" is shown in FIG.

The sound pressure frequency characteristics of the above-described sealed speaker system 10 measured in an anechoic room are indicated by a solid line in FIG. The dotted line in FIG. 13 is the sound pressure frequency characteristic of the reference speaker system. As can be seen from FIG. 13, by supporting the sound absorbing member 16 on the front baffle 17a, the sound pressure in the middle sound range from around the lowest resonance frequency to around 1 kHz becomes higher than that of the reference speaker system, and the peaks and valleys of the sound pressure become smaller. It was.

(Specific Example 2)
A reference speaker system similar to that of Example 1 is prepared. As shown in FIG. 6, the sound absorbing member 16 and the peripheral edge of the front baffle 17a are arranged so that the front baffle 17a and the front surface of the sound absorbing member 16 are flush with each other. A sealed speaker system 60 attached in a collar shape to the part was created.
(Configuration of sound absorbing member 16)
Sound absorbing material: Urethane foam (“DOX” manufactured by Bridgestone Corporation)
Dimensions of sound absorbing member; external dimensions: length 300 x width 290 x thickness 20 mm
Inner dimensions: length 140 x width 130mm

The sound pressure frequency characteristic measured in the anechoic chamber of the above-described sealed speaker system 60 is shown by a solid line in FIG. The dotted line in FIG. 11 is the sound pressure frequency characteristic of the reference speaker system. As can be seen from FIG. 11, the sound absorbing member 16 is carried on the peripheral portion of the front baffle 17a, so that the sound pressure in the midrange is higher and flatter than that of the reference speaker system, and the sealed type described in the specific embodiment 1 The sound pressure waveform in the middle range is further flattened than the speaker system 10.

(Specific Example 3)
A reference speaker system similar to that of the first embodiment is prepared. As shown in FIG. 9, a sealed speaker system 90 in which a sound absorbing member 16 shown below protrudes 80 mm from the surface of the baffle 17a and is attached to the peripheral portion of the box 17 is provided. Created.
(Configuration of sound absorbing member 16)
Sound absorbing material: Urethane foam (“DOX” manufactured by Bridgestone Corporation)
Dimensions of sound-absorbing member; external dimensions: length 150 x width 140 x depth 90 mm
Inner dimensions: 110 x 100 mm

The sound pressure frequency characteristic measured in the anechoic chamber of the above-described sealed speaker system 90 is shown by a solid line in FIG. Note that the dotted line in FIG. 14 is the sound pressure frequency characteristic of the reference speaker system. As can be seen from FIG. 14, the sound pressure in the middle range is higher and flattened than in the reference speaker system, and the sound pressure level in the lower mid range is higher than that in the sealed speaker system 60 described in the second embodiment, and The sound pressure waveform in the middle range has been further flattened.

(Comparative Example 1)
The sound pressure frequency characteristic of the sealed speaker system in which the sound absorbing member 16 (urethane foam) of the sealed speaker system 60 described in the specific embodiment 2 is replaced with a wooden board shown below is shown by a solid line in FIG. The dotted line in FIG. 12 is the sound pressure frequency characteristic of the reference speaker system.
(Structure of wood board)
Wood board material: cedar board (reflectance: approximately 1)
Dimensions of wood board; external dimensions: length 300 x width 290 x thickness 10 mm
Inner dimensions: length 140 x width 130mm

As can be seen from FIG. 12, when compared with the sealed speaker system 60 described in the specific example 2, the sound pressure from the lowest resonance frequency to 500 Hz is lowered by 2 to 4 dB, and the peaks and valleys of the sound pressure are increased.

The speaker system and the speaker box according to the present invention are useful in the field of acoustic equipment.

Schematic which shows the example of 1 structure of the sealed speaker system which concerns on this invention. Explanatory drawing for demonstrating arrangement | positioning of the sound absorption member which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. Schematic which shows the example of 1 structure of the other sealed speaker system which concerns on this invention. FIG. 3 is a sound pressure frequency characteristic diagram of a sealed speaker system according to the present invention. FIG. 6 is a sound pressure frequency characteristic diagram of a sealed speaker system used in a comparative example. The sound pressure frequency characteristic figure of the other sealed speaker system which concerns on this invention. The sound pressure frequency characteristic figure of the other sealed speaker system which concerns on this invention. The normal incidence sound absorption coefficient characteristic figure which shows an example of the normal incidence sound absorption coefficient of the acoustic resistance member which concerns on this invention. Schematic which shows the example of 1 structure of the bass-reflex type speaker system concerning the present invention. The sound absorption characteristic figure which shows the normal incidence sound absorption coefficient of the sound absorption member which concerns on this invention.

Explanation of symbols

10, 30, 40, 60, 70, 80, 90, 100 Sealed speaker system 11 Speaker unit 16 Sound absorbing member 17 Box 17a Front baffle
150 bass reflex type speaker system

Claims (12)

A speaker unit, a box in which the speaker unit is mounted, and a sound absorbing member that reflects and absorbs sound waves, and the sound absorbing member is carried in a propagation space of sound waves radiated from the front surface of the speaker unit. The speaker system. The speaker system according to claim 1, wherein the sound absorbing member is carried on a speaker unit mounting surface of the box. The speaker system according to claim 1, wherein the sound absorbing member is carried on a peripheral portion of the box. The speaker system according to claim 3, wherein the sound absorbing member protrudes forward from a speaker unit mounting surface of the box. 5. The speaker system according to claim 1, wherein the box and the sound absorbing member are made of materials having different reflectivities and sound absorption factors. 6. The speaker system according to claim 1, wherein the sound absorbing member is made of a plurality of materials having different reflectivities and sound absorption factors. The speaker system according to claim 1, wherein the speaker unit is mounted in a sealed box. The speaker system according to claim 7, wherein an acoustic port is provided in a part of the box. A speaker box, comprising: a box having an opening for mounting a speaker unit; and a sound absorbing member that reflects and absorbs sound waves, and the sound absorbing member is carried outside the box. The speaker box according to claim 9, wherein the sound absorbing member is carried on a box surface having the opening. The speaker box according to claim 9 or 10, wherein the sound absorbing member is carried on a peripheral portion of the box. The speaker box according to claim 9, wherein the sound absorbing member protrudes forward from a box surface having the opening.

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