JPH0458698A - Speaker system - Google Patents

Abstract

PURPOSE:To prevent the rapid reduction in the sound pressure level at a low frequency by mounting speaker units of a same characteristic to both buffle plates opposite to each other, covering a rear side of the one with a sound absorbing member and connecting the units electrically so as to be in operation in opposite phase. CONSTITUTION:Speakers 1, 2 of a same characteristic are mounted to a buffle plate 4 of a cabinet 3, a rear part of the speaker 2 is covered by a sound absorption material 6 and the speakers are interconnected to an input terminal 7 by internal wiring members 8a, 8b so that they are operated in opposite phase. Since the sound radiating from the speaker units 1, 2 at middle and high frequencies is of the same amplitude but in opposite phase, a dipole directivity is provided and since the rear side of the speaker 2 is covered by the sound absorption material, the amplitude of the diaphragm of the speaker unit 2 is more limited than that of the speaker unit 1, the cancellation of the sound pressure is relaxed and a rapid decrease in the sound pressure level at a low frequency is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a speaker system having dipole directivity characteristics.

2. Description of the Related Art In recent years, improvements in video technology have made it possible to show movies on a large screen even at home. Along with this, sound equipment has also come to be required to have the power and sound quality befitting a large screen.

Against this background, as shown in FIG.
On the other hand, it is often a so-called surround sound field reproduction device that uses two or three speaker systems 9 in the front and two or more speaker systems 12 on the sides or rear.

The front channel of this surround sound field playback device receives signals such as the audio of the software being played and background music, while the rear channel receives signals such as indirect sound and reverberation that are synthesized from the front signal using a special processing device. It reproduces the signal.

If the tones of the direct sound component coming from the front and the indirect sound or resonance components coming from the rear are different, it will give a sense of discomfort to the viewer, so it is desirable that the front and rear speaker systems have the same sound quality as possible. Therefore, even if the speaker system is for the rear, it is desired that it be able to reproduce low frequencies to some extent. In addition, since the rear channels reproduce indirect sound and reverberant sound, it is important to install the speaker system so that the sound from a specific speaker system does not reach the viewer directly and localize the sound image to achieve a good surround effect. For example, as shown in FIG. 4, there is a method of increasing the above effect by using a large number of general rear speaker systems 12 to surround the viewer 11 to disperse the sound sources. However, due to installation location issues and costs, it is required to obtain the maximum effect with as few rear speaker systems as possible.

On the other hand, dipole speaker systems have disadvantages in terms of bass reproduction, as the sound pressure at the front and back of the speaker cancel each other out at frequencies lower than the frequency range where the baffle size corresponds to half a wavelength. ,
It has a dipole directional characteristic in which the sound pressure is maximum at the front and back sides of the speaker, and the sound pressure is minimum at the sides of the speaker, and is known to be useful for certain purposes.

This is for example the document DIPOLE RADIATORS
YSTEMS: Dipole radiator system (R,
J, NE! Written by fMAN, JOURNAL OF TIT
E AUDIO ENGINEERING 5OCIET
Y, +980, JANUARY/FEBRUARY, V
OLt1ME28. NUMBER1/2) As stated above, the speaker unit is generally attached to two baffle plates rather than a cabinet.

In view of the above points, the following speaker system has been proposed as a rear speaker system, which operates in the same way as the dipole speaker system described above and has a speaker unit housed in a cabinet for practical use.

This is a speaker system in which speaker units having the same characteristics are attached to both one baffle plate and the opposing baffle plate of a cabinet, and both speaker units are electrically connected to each other so that they operate in opposite phases. In other words, when the diaphragm of the speaker unit attached to one baffle plate moves in the direction of protruding from the baffle plate, the diaphragm of the speaker unit attached to the opposite baffle plate moves in the direction of sinking below the baffle plate. That's why. Like the dipole type speaker system described above, this speaker system exhibits a dipole directivity characteristic in which the sound pressure is maximum at the front of each speaker unit and the sound pressure is minimum at a position equidistant from each speaker unit, that is, on the side of the cabinet. On the other hand, in a frequency band below frequency fc, the sound pressures from both speakers cancel each other out, causing a rapid drop in the sound pressure level. To explain fC here, Ll is the straight line distance for the sound emitted from the speaker unit facing the measuring sound receiving point to reach the measuring sound receiving point, and the sound emitted from the other speaker unit on the back side is Ll. When the distance from the outside of the cabinet to the measurement sound receiving point is L2, the difference between these two distances L2 - Ll (hereinafter referred to as the effective distance between both speaker units) is the frequency. It corresponds to a half wavelength of fc.

When the speaker system described above is placed on both sides of the listener as a rear speaker system of an audio reproduction device combined with a home video reproduction device, this speaker system has a dipole directional characteristic, so it can be used near the viewing position. In this case, the sound pressure of the direct sound from the rear speaker system is minimized, and only the indirect sound reflected from the walls of the viewing room reaches the viewer, giving the viewer a good surround effect while using a small number of speakers. I can do it.

Problems to be Solved by the Invention However, in the above speaker system, the sound pressure of both speaker units cancels each other out in the band below fc, causing a sudden drop in sound pressure level. For example, it is possible to increase the effective distance between both speaker units by increasing the size of the cabinet to lower the frequency at which cancellation occurs, that is, fc, or to significantly increase the level of the bass range in the amplifier that drives the speaker system. This caused a big problem in practice.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a speaker system that can provide a good surround effect to the audience while using a small number of speakers, and that does not cause a sudden drop in sound pressure level in the bass range. It is said that

Means for Solving the Problems In order to achieve the above object, the present invention attaches speaker units having the same characteristics to both one baffle plate and the opposing baffle plate of the cabinet, and attaches speaker units to the rear of one speaker unit ( ). is covered with a sound absorbing material, and both speaker units are electrically connected so that they operate in opposite phases.

Effect of the present invention With the above-described configuration, the diaphragm amplitude of both speaker units is the same in the mid-to-high frequency range, and the sound emitted from both speaker units has the same amplitude and opposite phase. It exhibits a dipole directivity characteristic with maximum sound pressure and minimum sound pressure on the sides of the cabinet.

In addition, in the low frequency range, the rear of one speaker unit is covered with sound-absorbing material, which increases air flow resistance and limits the diaphragm amplitude compared to the other speaker unit, reducing sound pressure cancellation. , it is possible to prevent a sudden drop in sound pressure level in the bass range.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1, 2, and 3. As shown in Figure 1,
Speaker units 1 and 2 having the same characteristics are each attached to a baffle plate 5 facing one baffle plate 4 of a cabinet 3. In addition, speaker unit 2
Its rear part is covered with a sound absorbing material 6 such as felt, glass wool, sponge, or foamed rubber. Further, the speaker units 1 and 2 are electrically connected to the input terminal 7 by internal wiring members 8a and 8b so as to operate in opposite phases to each other.

To explain the operation in the above configuration, the diaphragm amplitude of speaker units 1 and 2 is not affected by the difference in the condition at the rear of the speaker unit in the mid-to-high range, so the diaphragm amplitude of the speaker units 1 and 2 in the mid-to-high range is Since the sound emitted from speaker units 1 and 2 has the same amplitude and opposite phase, the sound pressure is maximum in front of speaker units 1 and 2, and the sound pressure is maximum at a position equidistant from speaker units 1 and 2, that is, on the side of the cabinet. It shows a dipole directivity characteristic with the minimum sound pressure at . On the other hand, in the bass range, when only the speaker unit 1 is driven, the sound pressure frequency characteristic shown in FIG. 2a is shown in front of the speaker unit 1. On the other hand, when only the speaker unit 2 is driven, only the mid-high range is attenuated as it goes around the cabinet 3, and since the rear part of the speaker unit 2 is covered with sound absorbing material, there is a large air flow resistance. The diaphragm amplitude is more limited than that of the speaker unit 1, and the front side of the speaker unit 1 exhibits a sound pressure frequency characteristic as shown in FIG. In this way, in the low frequency range, speaker units 1 and 2 are in opposite phases but have different sound pressure levels, that is, different amplitude levels, so the cancellation of sound pressure is alleviated, and when both speaker units 1 and 2 are driven, The sound pressure frequency characteristic in front of the speaker unit 1 extends to the bass range below fc, as shown in FIG. 2C.

FIG. 3 shows a speaker system according to an embodiment of the present invention placed on both sides of a test listener 11 as a rear speaker system 10, and used in combination with a home video playback device 13 and a front speaker system 9. This is an example of a playback device. When the speaker system according to the embodiment of the present invention is installed as shown in this figure, the directivity of the rear speaker system 10 is a dipole directional characteristic. The sound pressure is minimized, and only indirect sound reflected from the walls of the viewing room, etc., reaches the viewer 11, and a good surround effect can be provided to the viewer 11 even though a small number of them are used. In addition, since a sudden drop in sound pressure level does not occur in the bass range, it is possible to match the sound quality of the front and rear speaker systems, and the direct sound component coming from the front speaker system 9 and the rear speaker system 10 This eliminates the possibility that the timbres of the indirect sounds and resonance components caused by the sound are different and give a sense of discomfort to the viewer 11. In addition, in the low frequency range, the dipole directional characteristics of Speaker Unit) 1.2 are slightly reduced due to the difference in amplitude level, but due to the nature of human hearing that the sense of localization is ambiguous for low frequency sounds, The surround effect is not impaired at all.

As described above, according to the speaker system of the embodiment of the present invention, the sounds emitted from the speaker units 1 and 2 have the same amplitude and opposite phase in the middle and high frequency range.
It exhibits a dipole directivity characteristic in which the sound pressure is maximum at the front of the cabinet and the sound pressure is minimum at positions equidistant from the speaker units 1 and 2, that is, on the sides of the cabinet, and a good surround effect can be obtained. On the other hand, in the low frequency range, the rear part of speaker unit 2 is covered with sound-absorbing material, so the air flow resistance is large, so the diaphragm amplitude is more limited than that of speaker unit 1, and the cancellation of sound pressure is alleviated. , it is possible to prevent a sudden drop in sound pressure level in the bass range.

In this embodiment, speaker units 1 and 2 having the same characteristics are used, but the bass speaker unit of a multi-way speaker system composed of a plurality of speaker units each having the same characteristics and a dividing network may be used. Needless to say, it is effective to apply the configuration of the present invention.

Effects of the Invention As is clear from the above embodiments, according to the present invention, in the mid-to-high frequency range, the sounds emitted from both speaker units have the same amplitude and opposite phase, so that the maximum sound pressure occurs in front of each speaker unit. , exhibits a dipole directivity characteristic with the minimum sound pressure on the sides of the cabinet. In addition, in the low frequency range, the rear of one speaker unit is covered with sound-absorbing material, which increases air flow resistance and limits the diaphragm amplitude compared to the other speaker unit, reducing sound pressure cancellation. be done. Therefore, it is possible to provide a speaker system that can provide a good surround effect to the audience while using a small number of speakers, and that does not cause a sudden drop in sound pressure level in the bass range.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a speaker system according to an embodiment of the present invention;
FIG. 2 is a sound pressure frequency characteristic diagram of the speaker system of the same embodiment, and FIG. 3 is a layout diagram showing an example of a sound reproduction device in which the speaker system of the present invention is combined with a home video reproduction device as a rear speaker system. FIG. 4 is a layout diagram showing an example of a sound reproduction device in which a conventional general speaker system is combined with a home video reproduction device as a rear speaker system. 1, 2...Speaker unit, 3...Cabinet), 4.5...Baffle plate, θ...Sound absorbing material,
7...Input terminal, 8a, 8b...Internal wiring material. Name of agent Patent attorney Shigetaka Awano Haka1/2

Claims (1)

[Claims] Speaker units with the same characteristics are attached to both one baffle plate and the opposing baffle plate of the cabinet, the rear of one speaker unit is covered with sound absorbing material, and both speaker units operate in opposite phases to each other. Electrically connected speaker system.