JPH01276997A - Loudspeaker system - Google Patents

Abstract

PURPOSE:To suppress the peak of reproduced sound pressure frequency characteristics by standing waves so as to obtain flat sound pressure characteristics by providing at least one or more each of loudspeaker units for low- and high-pitched sounds in an acoustic pipe, slit-partition plates inside the acoustic pipe and horn, and a sound absorbing material between the partition plates and acoustic pipe. CONSTITUTION:Slit-partition plates 5 are provided at the opened section of an acoustic pipe 4 and at sections which are equal to the 1/3 of the length of the pipe 4 along the inner surface of the pipe 4 from the front face of a diaphragm of this loudspeaker unit and the sound absorbing material 6 is packed in the spaces between the acoustic pipe 4 and partition plates 5. Part of sound waves led to the opening becomes reflected waves and tends to return to the front face of the diaphragm due to an abrupt change in acoustic impedance produced at the opening section. Such reflected waves can be absorbed by the sound absorbing material 6 provided inside the acoustic pipe and occurrence of standing waves inside the acoustic pipe can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speaker system in which an acoustic tube for guiding sound waves is arranged on the front surface of a speaker diaphragm.

Conventional technology A method of installing a horn or acoustic tube on the front of a speaker diaphragm and guiding the sound waves generated from the diaphragm to the opening can obtain a larger output sound pressure than when no horn or acoustic tube is used. It has been widely used since it has advantages such as being able to transmit sound in a specific direction.

Hereinafter, a conventional speaker system equipped with a horn or acoustic tube will be explained with reference to the drawings.

FIG. 3 shows a structural sectional view of the above speaker system.

In FIG. 3, 9 is a speaker unit, 3 is a back cavity, and 8.7 is a sound guide section.

The operation of the speaker system with the horn and acoustic tube configured as described above will be explained below.

A horn 8 is placed on the front part of the speaker diaphragm, the area of which is small near the diaphragm and gradually increases in size as it approaches the opening, and the rear part of the speaker diaphragm does not radiate to the outside. The back cavity 3 is arranged like this. If the length of the horn 8 is sufficiently longer than the wavelength of the reproduction band to be reproduced, a flat reproduction sound pressure frequency characteristic can be obtained.

Problems to be Solved by the Invention However, with the above configuration, if the horn length cannot be made long enough for integration into equipment,
The reproduced sound pressure frequency characteristic is a characteristic with many peaks and dips and valleys.For example, Figure 2 shows the reproduced sound pressure frequency characteristic diagram of a speaker system equipped with a horn or acoustic tube.Characteristic B in Figure 2 is a characteristic of a conventional speaker system equipped with a horn or acoustic tube as shown in FIG. 3, for example.

As shown in Fig. 4, in a long acoustic tube, when the speed of sound is C, the frequency f-(2n-1)C/4L (n-
A resonance phenomenon occurs at 1, 2, 3, . . . i, and a peak/dip appears in the reproduced sound pressure frequency characteristic. Furthermore, the fourth
The figure shows the sound pressure distribution and particle velocity distribution when n=2.

In view of the above-mentioned problems, the present invention provides a speaker system that can obtain flat frequency characteristics without peaks and dips due to resonance even in a speaker system having a short horn or acoustic tube. The speaker system of the present invention guides sound waves in front of a speaker diaphragm (an acoustic tube is arranged), and inside the acoustic tube, at least one speaker unit for bass and at least one speaker unit for treble are arranged. In addition, the area of the sound tube is small at the front of the diaphragm, and increases as it approaches the opening, and one-third of the length of the sound tube is set between the opening of the sound tube and the speaker diaphragm. A wall is provided with a partition plate having slits in both sides.Furthermore, a sound absorbing material is arranged between the partition plate and the side wall of the acoustic tube.

Effect The present invention provides a slit in the partition at a portion L/3 from the diaphragm side and at the open end of the acoustic tube, and arranges a sound absorbing material between the side wall of the acoustic tube and the partition plate, thereby reducing the particle velocity. , the second peak can be taken, and also,
The first peak having the maximum particle velocity at the aperture can also be taken at the same time. Further, the third and subsequent peaks can also be taken by the slit in the opening.

Furthermore, the sound waves generated on the front surface of the diaphragm can be passed through to the opening by the partition plate that guides the sound waves from the front surface of the diaphragm to the opening, making it possible to reproduce up to high frequencies.

As a result of the above effects, it is possible to realize flat sound pressure frequency characteristics up to high frequencies without peaks and dips.

Embodiment Hereinafter, a speaker system according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional view of the structure of a speaker system according to an embodiment of the present invention. In Fig. 1, 1 is a treble speaker unit, 2 is a bass speaker unit, 3 is a back cavity, and 4 is a channel for guiding sound waves generated in front of the diaphragms of the treble speaker unit l and bass speaker unit 2 (acoustic A partition plate 5 is arranged so that a sound guiding part is provided inside the acoustic tube 4, and has a slit at the opening of the acoustic tube 4 and at one-third of the acoustic tube length from the front of the speaker diaphragm. Reference numeral 6 designates a sound absorbing material arranged in a portion surrounded by the acoustic tube 3 and the partition plate 4, and 7 designates a sound guiding portion.

The operation of the speaker system configured as described above will be described below. The sound from the back of the diaphragm of the high-pitched speaker unit l and the bass speaker unit 2 is closed in the cavity 3, but the sound waves radiated to the front of the diaphragm are guided to the opening through the acoustic tube 4 and radiated. ing. However, due to the sudden change in acoustic impedance that occurs at the aperture, a portion of the sound waves guided to the aperture become reflected waves and attempt to return to the front surface of the diaphragm. This reflected wave is absorbed by the sound absorbing material 6 placed inside the acoustic tube,
This prevents standing waves from being generated inside the acoustic tube. The slits in the partition plate 5 are provided at the opening of the acoustic tube 4, where the particle velocity increases, and at one-third of the acoustic tube length from the front of the speaker diaphragm. It is possible to dampen only the sound waves, and high-frequency sounds that are easily absorbed by the sound absorbing material 6 are guided to the opening without being obstructed by the sound absorbing material 6.

FIG. 2 shows the reproduced sound pressure frequency characteristics of a speaker system equipped with a horn or acoustic tube, comparing the present embodiment and a conventional example. Characteristic B in the conventional example is a characteristic with large peaks and valleys due to the generation of standing waves in the acoustic tube, but as shown in A, the characteristics of the speaker system of this example show that a reproduced sound pressure frequency characteristic that is flat up to the high range can be obtained. I know that it will happen. In addition,
The partition plate 5 inside the acoustic tube has a small cross-sectional area at the front of the speaker (it forms a horn whose cross-sectional area increases as it approaches the opening), or if the cross-sectional area does not change, it may change the shape of the acoustic tube. Regardless, the same effects as in this embodiment can be obtained.

Effects of the Invention As described above, the present invention has at least one speaker unit for bass and treble within the acoustic tube, making it possible to expand the reproduction band. By using a structure in which a partition plate is provided and a sound-absorbing material is placed between the partition plate and the side wall of the acoustic tube, the peak of the reproduced sound pressure frequency characteristics due to the standing waves found in conventional acoustic tubes and horns can be suppressed. A speaker system having suppressed and flat sound pressure characteristics can be realized.

[Brief explanation of the drawing]

FIG. 1 is a structural sectional view of an embodiment of the speaker system of the present invention, FIG. 2 is a sound pressure frequency characteristic diagram of the speaker system, and FIG. 3 is a structural sectional view of a conventional speaker system.
FIG. 4 is a characteristic diagram showing particle velocity distribution and sound pressure distribution in the cross section of the acoustic tube. 1...Treble speaker unit, 2...
...Bass speaker unit, 3...Pack cavity, 4...Acoustic tube, 5...Partition plate, 6.Old sound absorbing material, 7... ...Sound guide section, 8
...Horn, 9...Speaker unit. Agent's name: Patent attorney Toshio Nakao 1 person f-0-Kan 11-use and 0-Kani; ㅅ1 4-On τao 5-Ichishi Kohan 6--Suku R 7-・- In the past, the 2nd diagram of the Shuka comparison (Hzl 9・-su 6-kako, ζ・sito 4th diagram)

Claims (4)

[Claims] (1) A speaker system characterized in that an acoustic tube that guides sound waves is arranged in front of a speaker diaphragm, and at least one speaker unit for bass and at least one speaker unit for treble is arranged inside the acoustic tube. . (2) Claim (2) characterized in that the wall of the acoustic tube is constituted by a partition plate having a slit at its opening and at one-third of the length of the acoustic tube on the side of the speaker diaphragm.
1) The speaker system described. (3) The cross-sectional area surrounded by the partition plate with a slit inside the acoustic tube and the acoustic tube wall is fixed, or the cross-sectional area is small in front of the speaker diaphragm and increases as it approaches the opening. A claim characterized in that (
2) The speaker system described. (4) The speaker system according to claim 2 or 3, wherein a sound absorbing material is disposed between the partition plate having the slit inside the acoustic tube and the side wall of the acoustic tube.