JP2017092923A - Acoustic guide of speaker system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single speaker unit capable of combining a sound image type and a sound field type, reproducing the bass band, having a wide directivity, and capable of reproducing auditory localization clearly with a small sound source.SOLUTION: In the front of a speaker unit 3 of a stereo device, acoustic guide plates 1, 2 for dividing the sound source of left and right speakers into a direct sound 7 and indirect sounds 8, 9 are provided. Auditory localization is clarified by dividing the sound source of the left and right speakers into a direct sound and an indirect sound, and imparting a wide directivity in the horizontal direction, and a narrow directivity in the horizontal direction to the direct sound. Furthermore, a sound field feeling is increased by the indirect sound.SELECTED DRAWING: Figure 1

Description

The present invention relates to an acoustic guide device for increasing sound image localization and sound field feeling.

Conventionally, in speaker reproduction, an acoustic horn is provided on the front surface of the speaker unit to increase the sound field feeling, or a diffuser, an acoustic lens, or the like is used.

Published by Sakamoto Kobo, “Electroacoustic Vibration”, Corona, July 20, 1960 p. 48-55

A speaker unit having a large caliber, such as a woofer, reproduces the low frequency range, but sharpens the directivity in the high frequency range, and the sound pressure attenuates when the speaker unit moves away from the center of the shaft. On the other hand, a small-diameter speaker unit has a wide directivity and a small sound image, but it is difficult to produce a low sound range. It is difficult to solve both of these problems with a single speaker unit. Also, it is difficult to arbitrarily set the ratio of direct sound and indirect sound generated from the speaker unit in order to increase the sound field feeling in stereo reproduction. The present invention is intended to solve the above-described points.

Means to solve

The present invention has devised the following means for solving the above problems.
An acoustic guide unit that is installed in front of the speaker and controls the sound path of the speaker unit. Vertical sound path reflectors are provided on the left and right sides from the center of the speaker unit, and the sound is transmitted directly from the center. And the indirect sound from the left side part and the right side part, the direct sound is expanded in the horizontal direction by the width of the central portion, and the vertical directionality is narrowed by the length in the vertical direction. A speaker sound guide device comprising:

Effect of the invention

  1 and FIG. 2, the direct sound from the acoustic guide device is the same as the guide plate (1) having a width a (5) provided in the diameter of the speaker unit (3) ( 2), the directivity is determined by the value of ka expressed by the ratio ka = 2πa / λ of the diameter and wavelength of the vibration surface of the speaker unit (3). (Where λ is the wavelength.) From the data shown in the directivity (22) of FIG. 4, the ratio ka = 2πa / λ, which is the ratio of the width (interval) a (5) to the wavelength λ, is 2 Or less, a sound source (20) having a wide directivity (21) can be obtained. By narrowing the lateral width, the speaker unit having a caliber of 4a (6) is equivalent to a (5). It becomes a small sound source. By inserting the guide device according to the present invention as compared with the width of 4a (6), the horizontal width of a (5) can maintain a wide directivity in the horizontal direction up to a short wavelength and a high frequency band.

On the other hand, with reference to FIG. 5, in the case of a vertically long diaphragm in which the length of a short side is a (27) and the long side is 4a (26), ka = 2π × (4a) / λ = 4 The directivity characteristic in the longitudinal direction, which is four times the wavelength λ in this ratio, here in the vertical direction shows a sharp directivity, and the directivity characteristic (24) of ka = 4 shown in FIG. 4 is ± 45 ° above the central axis. / The sound pressure response is attenuated by -10db just by changing to the bottom. Further, the sound source converges in a beam shape at a point f (25) shown in FIG. 4 to become a virtual sound source, and there is an effect that sound can be heard as if sound is emitted from the point f (25). Despite being a vertically long sound source, it converges to this f point and one point. As described above, the acoustic guide device according to the present invention has an effect of providing a wide directivity characteristic in the horizontal direction and a narrow directivity in the vertical direction regardless of the diameter of the speaker unit. Therefore, with a single speaker unit, there is a wide directivity characteristic over the entire band, the sound source becomes smaller, the effect of preventing interference from the ceiling and floor can be seen in the vertical direction, and the full range operation becomes effective. In addition, the indirect sound increases the sense of sound field due to the sound reflected from the left and right wall surfaces, and also reduces the feeling of hollowing between the left and right speakers.

Providing a sound path through which the direct sound passes in the width direction narrower than the diameter inside the front surface of the speaker unit where the low sound range comes out has an effect of expanding the directivity in the horizontal direction up to the mid-high sound range. FIG. 4 shows the relationship between the wavelength λ of the speaker unit having a diameter of 4a with respect to the widths of ka = 1 (21), ka = 2 (22), ka = 3 (23), and ka = 4 (24). The directivity characteristics of Here, in relation to the wavelength, as shown in the wavelength 2πa / λ = ka = 1 (21) and the same wavelength 2πa / λ = ka = 2 (22) of the data, it has a wide directivity characteristic. This has the effect of providing a wide directional characteristic equivalent to a small-aperture speaker unit having a quarter of the diameter 4a.

This will be described with reference to FIG. From a vibration source that is elongated in the longitudinal direction with a width a and length 4a according to the guide plate (1) and (2), sound seems to be generated from the center position of the speaker unit (28) as an equivalent sound source. A virtual sound source (29) is obtained, which is smaller than the actual diameter of the speaker unit (28) and has a diameter of a. The width a is a wavelength = 2πa and is shown in a (27) shown in FIG. 5 and ka = 1, which indicates a wide directivity and a linear sound source having a length of 4a. As a sound source in the lateral width direction, a spherical wave shape with moderate directivity and a sharp directivity characteristic in the vertical direction indicated by the sound source in the longitudinal direction 4a are synthesized as the virtual sound source (29), and the sound source is represented by point f in FIG. 25), the bass sound is reproduced by the 4a caliber speaker, the caliber is wide directional in the horizontal direction, the sound image and the localization close to the virtual point sound source by the small caliber are reproduced, and the function of the full range speaker is achieved. effective.

With the acoustic guide device according to the present invention, the direct sound wave from the vertical direction has sharp directivity in the vertical direction without losing the wide directional characteristics in the left-right direction, reducing the interference distortion of reflection due to the direct sound wave from the ceiling or the ceiling Increase the clarity of the sound. The directional characteristic data (24) shown in FIG. 4 is for a diaphragm having a length four times the wavelength of 2πa, and the directional characteristic shows a sharp directional characteristic with an attenuation of −30 db or less at ± 75 °. ing.

Referring to FIG. 3, the sound path is divided and reflected by the guide plates (1) and (2), and the indirect sound emitted from both inner sides of the left and right speakers is directed to the center, so the right and left Even if the distance between the speakers is increased and the distance between them is increased, the sound pressure density in the center portion does not become thin, so that the so-called hollow sound field is not produced.

Indirect sound coming from the outside of the right and left is reflected on the left and right outer walls and reflectors of the room and reflected directly from the sound by the reflecting guide plates placed in front of the right and left speakers, so that it can be heard as a diffused sound source. Increased feeling.

Referring to FIG. 3, both the right and left speakers radiate direct sound in the front direction and indirect sound in the left and right direction, so a wide directional characteristic is obtained on the 180 ° plane from the front, and the audible frequency band. The sound inside is heard flat.

By setting the width of the direct sound path guide plate arbitrarily, wide directivity can be obtained regardless of the diameter of the speaker unit used, and the acoustic guide device according to the present invention is easy to install. As described above, it is possible to achieve both sound image type and sound field type, reproduce the bass band, have wide directivity, clearly reproduce the sound image localization with a small sound source, and can be used with a single unit, so There is no need.

  It is explanatory drawing which showed the principle of operation of the acoustic guide device.   It is explanatory drawing of the perspective view of an acoustic guide device.   It is explanatory drawing which showed the implementation method of an acoustic guide device.   It is explanatory drawing which showed the directivity.   It is explanatory drawing which showed the vibration surface of the speaker.

Hereinafter, embodiments for carrying out the present invention will be described with reference to FIGS. 1 and 2.
The sound path guide plate (1) and (2) for dividing the direct sound (7), the indirect sound (8), and the (9) shown in FIG. (2) are provided on the front surface of the speaker unit (3). . The position where the direct sound is output and the interval between the sound path guide plates (1) and (2) are set within the vibration part of the speaker unit (3). The sound generated here radiates forward as a direct sound (7). The sound guide plate (1) and (2) are warped outward, and the sound from the speaker unit (3) is reflected from the sound guide plate (1) and indirect sounds (8) and (9) shown in FIG. Dissipates left and right.

The direct sound (7) emitted from the vibration surface of the central portion sandwiched between the sound path guide plates (1) and (2) of the present invention is horizontally long by the long side 4a (26) shown in FIG. It becomes a rectangular surface of side a (27). The longer the longitudinal side 4a (26) is, the sharper the directivity is in the vertical direction as indicated by the directivity (24) in FIG. Further, as the lateral width length a (27) is shorter, the directional characteristic in the horizontal direction is wider and gentler as indicated by the directional characteristic (21). This direct sound comes out as a sound having a combined directivity in the vertical and horizontal directions.
This directivity is determined by the ratio between the length of the vibration part and the wavelength λ of the sound.
In general, the relationship ka = 2πa / λ is known mathematically. The data table in FIG. 4 shows the practical directivity of each physical quantity in the mathematical formula. The directivity varies depending on the value of ka, and if the wavelength λ is ka = 2πa / λ, the directivity is determined by the ratio of the diameter of the vibration surface to the wavelength. With respect to the relationship between the wavelength λ and the length a of the sound source, the directivity data is shown in FIG. 4 with 2πa / λ = ka. When ka is 1 and ka = 1 (21) and ka is 2, ka = 2 (22), when ka is 3, ka = 3 (23), when ka is 4, ka = 4 ( 24), it can be seen from this data that a sufficiently wide directional characteristic can be obtained in practice if ka is 1 to 2 or less. Accordingly, since the wavelength λ is ka = 2πa / λ ≦ 2, a wide directivity characteristic in the horizontal direction can be obtained if the relationship of λ ≧ πa is satisfied. In the case of the directivity ka = 4 (24) shown in FIG. 4, ka = 4 ≦ 2πa / λ, and the directivity is sharp and narrow. As a result, it appears to be a virtual sound source that shows sharp directivity at a frequency that is shorter than the diameter of the vibration surface of the speaker, and that sounds like sound coming out from one point, point f (25). The effect of reflection from the ceiling and floor can be reduced with a sharp directivity. In addition, since the sound source is a virtual sound source from the point f, a clearer sound image localization can be obtained as a sound source from a small speaker. The directivity characteristic synthesized by the acoustic guide device according to the present invention is a mixed directivity having a wide directivity in the horizontal direction and a narrow directivity in the vertical direction.

1 Sound path guide plate 2 Sound path guide plate 3 Speaker unit 5 Width 6 Speaker diameter 7 Direct sound 8 Indirect sound 9 Indirect sound 21 ka = 1 directional characteristic 22 ka = 2 directional characteristic 23 ka = 3 directional characteristic 24 ka = 4 directivity 25 f point 29 virtual sound source

Claims (1)

A longitudinal sound path reflector is provided on the front side of the speaker unit from the center of the speaker unit to the left side and right side, and the sound is transmitted directly from the center and indirectly from the left side and right side. It is divided into sounds, and it has a structure in which the direct sound is expanded in the horizontal direction by the width of the central portion, and the directivity in the vertical direction is narrowed by the length in the longitudinal direction. Speaker acoustic guide device.

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