JP2830198B2 - Speaker system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a speaker system having an acoustic tube on one side of a speaker unit.

Conventional technology One of the conventional technologies for expanding the low temperature range of speaker systems
One is an acoustic maze type.

Hereinafter, a conventional acoustic maze type speaker system will be described with reference to the drawings.

FIG. 5 is a structural sectional view of the speaker system.

In FIG. 5, 1 is a cabinet, 2a, 2b, 2c, 2d, 2e.
Is a partition plate provided on the front plate and the rear plate of the cabinet 1, 3 is an opening provided on a lower portion of the front plate of the cabinet 1, and 4 is a speaker unit provided on an upper portion of the front plate.

The operation of the acoustic maze-type speaker system configured as described above will be described below.

Partition plates 2a, 2b, 2c, 2d provided in the cabinet 1
Reference numeral 2e denotes an acoustic tube, and a speaker unit 4
The sound emitted from the back of the sound tube is guided to the sound tube and radiated from the opening. An acoustic tube resonates at a specific frequency determined by its overall length. Assuming that the total length of the acoustic tube is L and the sound velocity in the air is C, the resonance frequency fn = C / 4Lx (2n + 1), where n = 0,1,
2,... N, and when n = 0, a quarter wavelength becomes equal to the length of the acoustic tube, causing a resonance phenomenon, and an acoustically increased sound is radiated from the opening 3 of the acoustic tube, and a large amount near the bass reproduction limit. Efficiency is improved. At a frequency where the half wavelength is equal to the length of the sound tube, the sound radiated from the front of the speaker unit 4 and the sound radiated from the opening 3 of the sound tube, which is originally out of phase with the sound from the front. The sound from the back of the unit 4 is added in the same phase due to a half-wave phase delay, and the sound pressure level increases. Further, when n = 2, the 3/4 wavelength becomes equal to the length of the acoustic tube, a resonance phenomenon occurs in the acoustic tube, and an acoustically increased sound is radiated from the opening 3 of the acoustic tube as in the case of n = 0. You. Therefore, a high-efficiency speaker system can be realized in a low-pitched sound range.

Problems to be Solved by the Invention However, in the above configuration, since the frequency at which 1/4 wavelength is equal to the length of the acoustic tube is the bass reproduction limit frequency of the speaker system, the acoustic tube needs to be longer to reproduce the bass range. And there is a disadvantage that the shape of the cabinet becomes large. When used as a low-frequency sound reproduction speaker system, it is desirable to use a speaker system for medium and high temperatures by using a frequency near the frequency at which 3/4 wavelength is equal to the length of the acoustic tube as a reproduction limit of a high frequency range.
As shown in the figure, in the conventional method, the acoustic radiation efficiency at the time of resonance of the acoustic tube increases as the frequency increases,
The sound pressure reaches a peak near the frequency where the 3/4 wavelength is equal to the length of the acoustic tube, and it is difficult to flatten this band by an electric circuit, which deteriorates the characteristics of the speaker system and lowers the sound quality.

In view of the above problems, the present invention expands the reproduction limit of the low frequency range without lengthening the sound tube, and suppresses the peak of the sound pressure near the frequency where the 3/4 wavelength is equal to the length of the sound tube. An object of the present invention is to provide a speaker system having bass characteristics.

Means for Solving the Problems In order to achieve this object, a speaker system according to the present invention comprises a first sound tube extending from one side of a front surface or a back surface of a speaker unit, one end of which is closed and an opening of which is closed. A second acoustic tube opened to the field space is arranged coaxially with the speaker unit and the first acoustic tube, and the total length of the first and second acoustic tubes is 1/4 of a reproduction limit. A wavelength, and a distance is provided between an open end of the first acoustic tube and a closed end of the second acoustic tube to constitute an acoustic volume.

The present invention is configured by the first and second acoustic tubes and the acoustic volume, and the frequency of the resonance phenomenon generated by the combination of the first and second acoustic tubes decreases according to the acoustic capacity of the acoustic volume. . The acoustic capacity also acts as a high-cut filter that blocks the mid-high range radiated from the speaker unit, and suppresses the sound pressure peak generated at the upper limit of the reproduction band.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural sectional view of a speaker system according to a first embodiment of the present invention. In FIG.
5 is a speaker unit, 6 is a first acoustic tube connected to the back of the speaker unit 5, 7 is its open end, 8 is a second acoustic tube whose one end 9 is closed, and 10 is open to the sound field space. The open end 11 of the second acoustic tube 8 is an acoustic volume formed between the open end 7 of the first acoustic tube 6 and the closed end 9 of the second acoustic tube 8.

Regarding the speaker system configured as described above,
The operation will be described below. The sound radiated from the back of the speaker unit 5 passes through the first acoustic tube 6 and is radiated from its open end 7 to an acoustic volume 11 formed between the first acoustic tube 6 and the closed end 9 of the second acoustic tube 8. . The sound in the acoustic volume 11 passes through the outer wall of the first acoustic tube 6 and the inner wall of the second acoustic tube 8,
The light is radiated from the open end 10 of the second acoustic tube 8 into the sound field space.
Therefore, the first acoustic tube 6 and the second acoustic tube 8 are arranged in an acoustic space.
11 and the speaker unit 5
, The equivalent acoustic capacity of the acoustic tube extending from the back surface to the opening end of the second acoustic tube 8 increases, and the frequency at which a resonance phenomenon occurs in the acoustic tube decreases. FIG. 2 shows a comparison between the sound pressure frequency characteristics and the amplitude characteristics of the diaphragm when a conventional sound tube having a uniform cross-sectional area and the sound tube of the present invention are used. At the time of resonance of the acoustic tube, the acoustic impedance of the acoustic tube viewed from the back of the speaker unit 5 becomes very large, and suppresses the amplitude of the diaphragm. From the amplitude characteristics in FIG. 2, it can be seen that the acoustic tube of the present invention lowers the frequency at which the resonance phenomenon of the acoustic tube occurs. Along with this, the sound tube of the present invention increases the sound pressure level near the low-frequency sound reproduction limit, thereby expanding the reproduction band. Furthermore, since the acoustic capacity of the acoustic volume 11 operates as a high cut filter, the
The sound pressure peak near the frequency where the 3/4 wavelength is equal to the length of the sound tube is suppressed in the sound tube of the present invention.

FIG. 3 is a structural sectional view of a speaker system according to a second embodiment of the present invention. 3 in FIG.
Is a speaker unit, 12 is a first acoustic tube coupled to the back of the speaker unit 5, 13 is its open end, and 14 is an input end 15
Is a second acoustic tube arranged at a distance from the open end of the first acoustic tube 12, and 16 is a second acoustic tube that emits sound into a sound field space.
14 is an open end, 17 is a third acoustic tube having its ends 18, 19 closed coaxially outside the first acoustic tube 12 and the second acoustic tube 14, 2
Reference numeral 0 denotes an acoustic volume defined by the outer walls of the first and second acoustic tubes 12 and 14 and the inner wall of the third acoustic tube 17.

Regarding the speaker system configured as described above,
The operation will be described below. In FIG. 3, sound emitted from the back of the speaker unit 5 passes through the first acoustic tube 12 and is radiated from its open end 13 to a space between the first acoustic tube 12 and the input end 15 of the second acoustic tube 14. . This space is composed of the first acoustic tube 12 and the second acoustic tube.
Is acoustically coupled to an acoustic space 20 defined by the outer wall of the acoustic tube 14 and the inner wall of the third acoustic tube 17 having the closed ends 18 and 19. Further, a second acoustic tube 14 having an input end 15 is coupled to the acoustic space 20, and an open end 16 thereof is coupled to the sound field space. Therefore, the basic operation of the speaker system in the present embodiment is the same as that of the first embodiment of the present invention shown in FIG. What is greatly different from the first embodiment is that the acoustic volume 20 is formed on the outer walls of the first and second acoustic tubes 12 and 14 and the positions of the closed ends 18 and 19 are extended to both ends, so that the third volume is obtained. Since the acoustic tube 17 can obtain a large acoustic volume with a small outer diameter, the outer diameter of the speaker system can be made smaller than that of the first embodiment.

FIG. 4 is a structural sectional view of a speaker system according to a third embodiment of the present invention. In FIG.
5 is a speaker unit, 21 is a first acoustic tube coupled to the back of the speaker unit 5, 22 is its open end, and 23 is the input end
A second acoustic tube having 24, 25 an open end thereof coupled to the sound field space, 26 a third acoustic tube provided coaxially outside the second acoustic tube 23, 27 a second acoustic tube The closed end, which contacts the outer wall of 23, is the other closed end.

Regarding the speaker system configured as described above,
The operation will be described below. The sound emitted from the back of the speaker unit 5 passes through the first acoustic tube 21 and is radiated from the open end 25 of the second acoustic tube 23 to the sound field space. A closed end is provided between the open end 22 of the first acoustic tube 21 and the input end 24 of the second acoustic tube 23.
A sound volume 29 constituted by a third sound tube 26 having 27 and 28 is combined. Therefore, the basic operation of this embodiment is the same as that of the first and second embodiments. A major difference from the first embodiment is that the closed end 27 of the third acoustic tube 26
Of the second acoustic tube 23 and the third acoustic tube 26
Since the size of the acoustic volume 29 formed by the inner wall of the speaker system can be set, the overall height of the speaker system can be reduced.

Effect of the Invention As described above, the present invention provides a second speaker having one end closed and an opening open to the sound field space outside the first acoustic tube extending from one of the front and rear sides of the speaker unit. An acoustic tube disposed coaxially with the speaker unit and the first acoustic tube, wherein a total length of the first and second acoustic tubes is a quarter wavelength of a reproduction limit; By configuring a sound volume with a distance between the open end of the tube and the closed end of the second sound tube, the bass reproduction limit frequency is reduced as compared with the case where a conventional straight sound tube is used. At the same time, the sound pressure level in the vicinity of the frequency can be increased, and the bass reproduction band can be expanded. Furthermore, the sound volume of the sound tube of the present invention suppresses the sound pressure peak caused by the resonance phenomenon near the frequency where the 3/4 wavelength is equal to the sound tube length in the conventional sound tube, and the speaker system has a flat bass range characteristic. Can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the structure of a speaker system according to a first embodiment of the present invention, FIG. 2 is a diagram showing the sound pressure and amplitude frequency characteristics of a diaphragm of the speaker system and a conventional speaker system, and FIG. FIG. 4 is a structural sectional view of a speaker system according to a second embodiment of the present invention, FIG. 4 is a structural sectional view of a speaker system according to a third embodiment of the present invention, and FIG. 5 is a structural sectional view of a conventional speaker system. 5 speaker unit, 6, 12, 21 ... first sound tube,
8,14,23 ... second sound tube, 11, 20, 29 ... sound volume, 26
... Third acoustic tube.

Claims (3)

(57) [Claims] 1. A second acoustic tube, one end of which is closed and whose opening is opened to a sound field space, is provided outside a first acoustic tube extending from one of a front surface and a rear surface of the speaker unit. And the first acoustic tube is arranged coaxially, and the total length of the first and second acoustic tubes is 1 / the reproduction limit.
A speaker system having four wavelengths, wherein a sound volume is configured by providing a distance between an open end of the first sound tube and a closed end of the second sound tube. 2. A sound in which the open ends of a first acoustic tube and a second acoustic tube are arranged to face each other with a distance therebetween, and both ends are coaxially closed outside the first and second acoustic tubes. Arrange the tubes,
The speaker system according to claim 1, wherein the closed acoustic tube is used as an acoustic volume. 3. A third sound tube which is closed at one end and joined to the outer wall of the second sound tube and closed at one end is provided outside the second sound tube. The speaker system according to claim 1, wherein an acoustic volume is formed between an outer wall and an inner wall of the third acoustic tube.