JP2004015588A - Speaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a speaker system having an acoustic radiation duct capable of reducing the generation of wind noise and/or harmonic distortion components at the opening of the acoustic radiation duct. <P>SOLUTION: This speaker system having the acoustic radiation duct comprises an enclosure, a speaker unit, and the acoustic radiation duct. The acoustic radiation duct has a main duct extending from one external wall, among external walls constituting the enclosure, into the inside of the enclosure, and a sub-duct provided in the peripheral part of the main duct. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a speaker system having an acoustic radiation duct used for reproducing an audio signal, and more particularly to a speaker system having an acoustic radiation duct represented by a bass reflex type enclosure.
[0002]
[Prior art]
2. Description of the Related Art In a speaker system or the like used for audio signal reproduction, speakers are attached to various enclosures in order to improve reproduction characteristics in a low frequency range. Above all, in the well-known bass reflex type enclosure, it is possible to improve the bass reproduction characteristics by utilizing the acoustic resonance of the air stiffness in the enclosure and the air mass in the acoustic radiation duct. it can. The first opening of the acoustic radiation duct is provided on a baffle surface outside the enclosure, and the second opening is provided inside the enclosure.
[0003]
In the vicinity of the resonance frequency at which the above-mentioned resonance occurs, radiation sound of high sound pressure is obtained from the sound radiation duct opening provided on the baffle surface outside the enclosure. At this time, the air vibrates at a very high speed inside the acoustic radiation duct and at the opening. As a result, undesirable wind noise and harmonic distortion components occur in the acoustic radiation duct.
[0004]
This phenomenon tends to occur in the case of an acoustic radiation duct having a uniform cross section in the length direction. In addition, when the opening of the sound radiation duct is small, it becomes more remarkable. With the recent miniaturization of speakers and speaker systems, the opening of the acoustic radiation duct has become smaller, and the wind noise and harmonic distortion components tend to be larger.
[0005]
For this purpose, conventionally, a method has been adopted in which the cross-sectional shape of the sound radiation duct is changed in accordance with the length direction, or in particular, a tapered or curved surface is provided at the opening of the sound radiation duct to smoothly change the opening area. ing.
[0006]
[Problems to be solved by the invention]
However, in the above-described conventional method, there is a limit in reducing the generation of wind noise and harmonic distortion components. If a tapered or curved surface is provided in the opening of the sound radiation duct, it is necessary to make a considerable change to obtain the effect sufficiently, and the area of the opening is smaller than the required cross-sectional area of the sound radiation duct. growing. Therefore, in reality, it is not possible to provide a sufficiently large taper or curved surface at the opening of the sound radiation duct, so that wind noise and harmonic distortion components increase.
[0007]
As described above, there is a need for a speaker system having an acoustic radiation duct that can reduce the generation of wind noise and harmonic distortion components at the opening of the acoustic radiation duct.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention takes the following technical measures.
[0009]
A speaker system according to the present invention is a speaker system including an enclosure, a speaker unit, and an acoustic radiation duct, wherein the acoustic radiation duct extends from one of outer walls constituting the enclosure to the inside of the enclosure. It has a duct and a sub duct provided at a peripheral portion of the main duct.
[0010]
In the present invention, preferably, the sub duct has a first opening provided in proximity to an opening on the enclosure outer wall side of the main duct, a second opening provided outside the enclosure, A speaker system is provided that is defined by a space that communicates the opening and the second opening.
[0011]
In the present invention, preferably, the sub duct has a flow velocity control means.
[0012]
In the present invention, preferably, the flow velocity control means of the sub duct is a taper provided at the first and / or second opening of the sub duct.
[0013]
In the present invention, preferably, the flow control means of the sub duct is a sound absorbing material disposed in a space communicating the first opening and the second opening of the sub duct.
[0014]
Hereinafter, the operation of the present invention will be described.
[0015]
The bass bass reflex speaker system's low-frequency reproduction characteristics are based on the mass of the vibration system such as the diaphragm of the speaker, the stiffness of the support system such as the damper, the mass of the air in the acoustic radiation duct, and the stiffness of the air inside the enclosure. Is determined. In the vicinity of the resonance frequency of the bass reflex type enclosure, the volume velocity of the air in the sound radiation duct becomes maximum, and the sound reproduction from the opening of the sound radiation duct can improve the reproduction characteristics in the low frequency range. In this case, the air vibration is disturbed by the resistance due to the friction generated on the wall surface in the acoustic duct and the acoustic load greatly changing at the acoustic radiation duct opening, and the wind noise and harmonic distortion components are generated. Occurs. A large change in the acoustic load is that the vibration velocity of the air at the opening of the sound radiation duct is high, while the air around the sound radiation duct opening on the baffle surface provided with the opening is almost stationary. This is due to the fact that the vibration speed of the air is greatly different.
[0016]
According to the present invention, the speaker system of the present invention is a speaker system including an enclosure, a speaker unit, and an acoustic radiation duct, wherein the acoustic radiation duct is connected to one of the outer walls constituting the enclosure from the inside of the enclosure. The main duct, and the auxiliary duct provided at the periphery of the main duct, so that the air at the opening of the auxiliary duct is guided by the vibration of the air at the opening of the main duct, and the air of the main duct Vibrates in synchronization. As a result, the air at the opening of the sub duct oscillates at a vibration speed between the vibration speed of the air at the opening of the main duct and the vibration speed of the air at rest around the opening. Therefore, the discontinuity of the vibration speed of the air is reduced, so that the generation of wind noise and harmonic distortion components can be reduced.
[0017]
Further, according to the present invention, the sub duct has a first opening provided in proximity to an opening of the main duct on the enclosure outer wall side, a second opening provided outside the enclosure, The air in the first opening of the sub duct is defined by the space communicating the first opening and the second opening, so that the air in the opening of the main duct is not affected by the air inside the enclosure. Is induced by the vibration of the main duct, and vibrates in synchronization with the air in the main duct. As a result, the air at the opening of the sub duct oscillates at a vibration speed between the vibration speed of the air at the opening of the main duct and the vibration speed of the air at rest around the opening. Therefore, the discontinuity of the vibration speed of the air is reduced, so that the generation of wind noise and harmonic distortion components can be reduced.
[0018]
Further, according to the present invention, by providing the sub-duct with the flow velocity control means, the vibration velocity of the air in the sub-duct can be adjusted, so that the generation of wind noise and harmonic distortion components can be further reduced. .
[0019]
Further, according to the present invention, since the vibration velocity of the air in the sub duct can be adjusted by providing the first and / or the second opening of the sub duct with a taper, the wind noise can be effectively produced at low cost. And the generation of harmonic distortion components can be reduced.
[0020]
Further, according to the present invention, by providing the sound absorbing material in the space communicating the first opening and the second opening of the sub duct, the vibration speed of the air in the sub duct can be easily adjusted. The generation of wind noise and harmonic distortion components can be effectively reduced at a low cost.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a speaker system according to preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
[0022]
FIG. 1 is a schematic sectional view of a speaker system 1 according to a preferred embodiment of the present invention. The speaker system 1 includes a speaker 2 and a sound radiation duct 3 of the present invention mounted on an enclosure 4, and is configured as a bass reflex type speaker system. The speaker 2 may be an electrodynamic speaker and may have any appropriate configuration. In FIG. 1, the sound radiation duct 3 is attached to the same baffle surface as the speaker attached baffle surface, but may be attached to any baffle surface of the enclosure.
[0023]
The sound radiation duct 3 includes a main duct 31 and a sub duct 32. The first opening 31a of the main duct 31 is provided in the baffle 4a outside the enclosure 4, and the second opening 31b is provided inside the enclosure 4. In the illustrated example, the sub duct 32 is configured as a folded duct. Specifically, the first opening 32 a of the sub duct 32 is provided around the opening 31 a of the main duct 31, and the second opening 32 b of the sub duct 32 is connected to the first opening 32 of the sub duct 32. It is provided around the portion 32a. Therefore, the first opening 31a of the main duct 31 and the first opening 32a of the sub duct 32 are arranged close to each other, and the second opening 31b of the main duct 31 and the second opening of the sub duct 32 are arranged. Portions 32b are spaced apart inside and outside of enclosure 4.
[0024]
FIG. 2 is a sectional view of a speaker system 1 according to another preferred embodiment of the present invention. In the sub duct 32 of the present embodiment, the first opening 32 a is provided around the first opening 31 a of the main duct 31, and the second opening 32 b is arranged outside the enclosure 4.
[0025]
FIG. 3 is a partial cross-sectional view near the acoustic radiation duct 3 of the speaker system 1 according to another preferred embodiment of the present invention. FIG. 4A is a front view of the opening defining member 33 and the cylindrical duct 34 constituting the sound radiation duct of FIG. 3, and FIG. 4B is a cross-sectional view. The main duct 31 includes a cylindrical duct 34 and an opening defining member 33 attached to the cylindrical duct 34. An outer cylindrical portion 33a surrounding the main duct 31 is provided around the main duct 31. The main duct 31 is attached to the enclosure by attaching the cylindrical duct 34 to the through hole 4b of the baffle 4a via the sub baffle 4c. The auxiliary duct 32 is defined by the outer cylindrical portion 33a, the inner cylindrical portion 33c, and the cylindrical duct 34 of the opening defining member 33. More specifically, the first opening 32a of the sub duct 32 has a plurality of opening defining portions 33b formed concentrically connecting the inner tubular portion 33c and the outer tubular portion 33a of the opening defining member 33. It is defined as an arc-shaped opening. The second opening 32b of the sub duct 32 is defined by a wall defining the through hole 4b of the baffle 4a and the outer cylindrical portion 33a. Therefore, the second opening 32b of the sub duct 32 is provided as an annular opening located concentrically with the main duct 31 and the first opening 32a around the first opening 32a. As described above, the sub duct 32 includes the first opening portion 32a formed in the opening defining portion 33b of the opening defining member 33, and the second opening portion 32b defined by the outer cylindrical portion 33a and the through hole 4b. And a space connecting the first opening 32a and the second opening 32b (this space is defined by the inner cylindrical portion 33c, the outer cylindrical portion 33a, the cylindrical duct 34, the wall of the sub baffle 4c, and the through hole 4b). (Defined by a wall).
[0026]
FIG. 5 is a partial cross-sectional view of the vicinity of the sound radiation duct 3 of the speaker system 1 according to another preferred embodiment of the present invention. In the present embodiment, a flow velocity control means is provided at the first and / or second opening of the sub duct to control the vibration speed of the air in the sub duct 32. Specifically, as shown in FIG. 5, the second opening 32b of the sub duct 32 may be configured by providing a taper in the through hole 4b of the baffle 4a. Thus, by providing the flow rate control means in the first and / or second openings 32a and / or 32b of the sub duct 32, it is possible to effectively reduce the generation of wind noise and harmonic distortion components. it can.
[0027]
FIG. 6 is a partial cross-sectional view of the vicinity of the sound radiation duct 3 of the speaker system 1 according to another preferred embodiment of the present invention. As shown in FIG. 6, the sound absorbing material 5 may be arranged in a space communicating the first opening 32a and the second opening 32b of the sub duct 32 to control the vibration speed of the air in the sub duct 32.
[0028]
In the description of the above embodiment, the sub duct 32 is configured by attaching the opening defining member 33 and the cylindrical duct 34 to the baffle 4a via the sub baffle 4c, but any appropriate opening defining member, duct forming member, and mounting You may comprise by a member. The sound radiation duct 3 may be configured by using a folded duct or the like formed in advance.
[0029]
In the above-described embodiment, the first opening of the main duct is circular, and the first and second openings of the sub duct are a plurality of arcs and an annular shape. The shape is not limited to a circular shape, an arc shape, and an annular shape, but may be a polygonal shape such as an elliptical shape or a rectangular shape. Further, the dimensions of the openings of the main duct and the sub duct are not limited to the dimensions described in the embodiment.
【The invention's effect】
[0030]
FIG. 7 is a graph of the sound pressure in front of the duct and the frequency characteristics of the second and third harmonic distortion when measured at a distance of 10 cm in front of the sound emitting duct in the speaker system having the sound emitting duct of the present invention. . At this time, the opening diameter of the opening 31a of the main duct is 34 mm, and the center diameter of the 12 arc-shaped first openings 32a of the sub-duct 32 located concentrically with the opening 31a of the main duct 31 is 42. 5 mm, the opening width is 2.5 mm, and the length is 21 mm. Similarly, the center diameter of the annular second opening 32b of the sub duct 32 is 55 mm, and the opening width is 6 mm. As described above, the implementation of the present invention reduces the distortion at 40 to 60 Hz for the second harmonic distortion and 40 to 100 Hz for the third harmonic distortion.
[0031]
ADVANTAGE OF THE INVENTION According to this invention, the acoustic radiation duct and the speaker system which can reduce generation | occurrence | production of the wind noise and the harmonic distortion component in the opening part of an acoustic radiation duct can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a speaker system using an acoustic radiation duct of the present invention.
FIG. 2 is a cross-sectional view of a speaker system using an acoustic radiation duct according to another preferred embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing the vicinity of an acoustic radiation duct in another preferred embodiment of the speaker system of the present invention.
FIG. 4 is a front view and a cross-sectional view of an opening defining member and a cylindrical duct that constitute the acoustic radiation duct of the present invention.
FIG. 5 is a partial cross-sectional view showing the vicinity of an acoustic radiation duct in another preferred embodiment of the speaker system of the present invention.
FIG. 6 is a partial cross-sectional view showing the vicinity of an acoustic radiation duct in another preferred embodiment of the speaker system of the present invention.
FIG. 7 is a graph of duct front sound pressure and frequency characteristics of second and third harmonic distortion measured in a speaker system having an acoustic radiation duct of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Speaker system 2 Speaker 3 Sound radiation duct 31 Main duct 31a First opening of main duct 31b Second opening of main duct 32 Sub duct 32a First opening of sub duct 32b Second opening of sub duct 33 Opening regulation Member 33a Outer tubular portion 33b Rib 33c Inner tubular portion 34 Cylindrical duct 4 Enclosure 4a Baffle 4b Baffle through hole 4c Secondary baffle 5 Sound absorbing material

Claims (5)

A speaker system including an enclosure, a speaker unit, and an acoustic radiation duct,
The acoustic radiation duct is
A main duct extending from one of the outer walls constituting the enclosure to the interior of the enclosure;
A speaker system including a sub duct provided on a peripheral portion of the main duct. The sub duct has a first opening provided near an opening on the enclosure outer wall side of the main duct, a second opening provided outside the enclosure, the first opening, The speaker system according to claim 1, wherein the speaker system is defined by a space communicating with the second opening. The speaker system according to claim 1, wherein the sub duct has a flow rate control unit. The speaker system according to any one of claims 1 to 3, wherein the flow velocity control means is a taper provided in the first and / or the second opening of the sub duct. The speaker system according to any one of claims 1 to 3, wherein the flow velocity control means is a sound absorbing material disposed in a space communicating the first opening and the second opening of the sub duct. .

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