JP2004247892A - Speaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker system which can concurrently realize both ultra-small size and thin thickness and is low-cost and excellent in design versatility by enabling reproducing a low frequency sound which can be practically available even by a small-dimension speaker unit. <P>SOLUTION: In the speaker system, the diaphragm of a speaker unit SP is made to border a main chamber 2 provided with an acoustic duct 3 and the back surface of the speaker unit SP borders a closed chamber 4. In this system, a sub-chamber 5 provided alongside the main chamber 2 and having an area ratio extremely smaller than that of the main chamber 2 is formed, and the diaphragm of the speaker unit SP is made to border the sub-chamber 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a loudspeaker system for low-frequency sound reproduction that uses a small-diameter loudspeaker unit, realizes a small and thin loudspeaker cabinet, and obtains a practical sound pressure level.
[0002]
[Prior art]
2. Description of the Related Art Generally, in audio-visual devices such as a television receiver and an audio device, a loudspeaker system using Helmholtz resonance is often used in order to enhance a low-pitched sound range and reproduce the sound with a sense of realism. Particularly, in a speaker system dedicated to bass, a Kelton system is often used because it can be configured relatively compact without using a long horn or the like, and is practically used.
[0003]
FIG. 10 is a cross-sectional view showing an example of a conventional speaker system configured by the Kelton system. In a cabinet 100 configuring the speaker system, a speaker unit 101 is fixed to a baffle plate 102 in the cabinet 100. The inside of the cabinet 100 is partitioned by a baffle plate 102 into a first air chamber 103 and a second air chamber 104. The first air chamber 103 is provided with an acoustic duct 105, and a low sound is generated from the acoustic duct 105 by utilizing the Helmholtz resonance caused by the stiffness of the air in the first air chamber 103 and the air equivalent mass of the acoustic duct 105. (For example, Patent Document 1).
[0004]
Unlike the bass reflex type speaker system, the reproduced sound is radiated only from the acoustic duct in the Kelton type speaker system configured as described above, and its sound pressure characteristic has a frequency range whose practical lower limit frequency is as shown in FIG. The characteristic is obtained through a filter from fl to the upper limit frequency fh. As a characteristic tendency of the bass range, the bass reflex system is 18 db / oct. , While the Kelton system uses 12 db / oct. As in the closed system. Therefore, the Kelton system is advantageous when considering only the reproduction of the low frequency range, and it is specified and used as a low frequency speaker system from such characteristics, and is widely used as a subwoofer such as a home theater.
[0005]
[Patent Document 1]
JP 2000-278778 A
[Problems to be solved by the invention]
In such a structure of the conventional Kelton type speaker system, the lower limit frequency fl that can be reproduced is limited to about 70% of the lowest resonance frequency f0 of the speaker unit to be used, and the lower limit frequency is forcibly set by means of cabinet design. When fl is reduced, as shown in FIG. 12, a practical reproduction frequency band has a very narrow steep characteristic, and the connection with a speaker for reproducing the middle and high frequencies becomes extremely poor. For this reason, in order to lower the lower limit frequency fl, a speaker unit having a lower minimum resonance frequency f0 is employed. However, since the speaker unit naturally has a large diaphragm diameter, the overall size of the speaker system is increased. Become.
[0007]
By the way, in recent years, especially in audiovisual equipment, miniaturization of speaker systems is an important issue, and while miniaturization of speaker systems for medium and treble can be easily achieved, miniaturization of speaker systems for bass sounds is difficult. Also, the outer shape was a box shape, and the design flexibility was poor.
[0008]
This is because, as described above, in the Kelton type speaker system, the diaphragm of the speaker unit directly faces the main room of the cabinet as shown in FIG. It had to be secured, and the box shape was naturally the basic form. In addition, the Kelton type speaker system has a low sound reproduction efficiency because the back of the speaker unit faces a closed room, and in many cases, a dedicated amplifier is built-in. It was difficult and did not improve the design.
[0009]
The present invention has been made in view of such a conventional problem, and is intended to enable low-frequency sound reproduction that can be provided for practical use even when a small-diameter speaker unit is employed. It is an object of the present invention to provide a loudspeaker system which can be made thinner and which is excellent in appearance design.
[0010]
[Means for Solving the Problems]
Therefore, the present invention has been made to solve the above-mentioned problem by each means described below. That is, according to the first aspect of the present invention, in the speaker system in which the diaphragm of the speaker unit faces the main room provided with the acoustic duct, and the rear surface of the speaker unit faces the closed room, the speaker system is connected to the main room, and A sub-chamber having an extremely small volume ratio with respect to the main chamber is formed, and the diaphragm of the speaker unit faces the sub-chamber.
[0011]
According to the invention of claim 2, in a speaker system in which a diaphragm of a speaker unit faces a main room provided with an acoustic duct, and a back surface of the speaker unit faces a closed room, the speaker system is connected to the main room, and A sub-chamber having an extremely small volume ratio with respect to the main chamber is formed so that the diaphragm of the first speaker unit faces the sub-chamber and the diaphragm of the second speaker unit faces the main chamber. To do.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a cross-sectional view of a speaker system according to a first embodiment of the present invention. A speaker cabinet 1 mainly includes a main room 2 and includes an acoustic duct 3. Therefore, Helmholtz resonance occurs due to the stiffness of the air in the main chamber 2 and the air equivalent mass (air mass) of the acoustic duct 3, and low sound is radiated from the acoustic duct 3.
[0014]
Next, a closed chamber 4 is formed at the end of the main chamber 2 facing the acoustic duct 3, and the speaker unit SP is arranged on the baffle plate 4 a of the closed chamber 4 in a horizontal state with respect to the longitudinal direction of the cabinet 1. Attached. The area defined by the baffle plate 4a and the inner wall of the cabinet becomes the sub-chamber 5, and the diaphragm of the speaker unit SP faces the sub-chamber 5. The volume ratio of the sub-chamber 5 to the main chamber 2 is extremely small, and the diaphragm of the speaker unit SP reliably captures the air in the sub-chamber 5 by reducing the air equivalent mass so that the vibration is effectively propagated. To do.
[0015]
With this configuration, the diaphragm of the speaker unit SP first excites the air in the sub-chamber 5, and the air in the sub-chamber 5 communicates as an air diaphragm as shown in the equivalent configuration diagram of FIG. Effectively propagates to the air in the main chamber 2. That is, when the diaphragm of the speaker directly faces the main chamber 2 having a large air capacity, the smaller the diaphragm of the speaker unit SP and the lower the frequency, the more difficult it is to catch air in the main chamber 5. Thus, the degree of excitation of the air in the main chamber 2 is reduced. However, in the present invention, the air in the small space of the sub-chamber 5 having a small capacity is primarily excited, so that the diaphragm of the speaker unit SP Since the loss of vibration energy can be prevented and the air in the sub chamber 5 is equivalently replaced with the speaker unit SP, the air in the main chamber 2 is strongly excited.
[0016]
FIG. 3 is a mechanical diagram of the speaker system of the first embodiment, where m0 indicates an equivalent mass of a diaphragm, a voice coil, and the like of the speaker unit SP, and S1 is an equivalent stiffness due to the hardness of the edge of the diaphragm and the damper. , S2 is the equivalent stiffness of the air spring applied to the back of the diaphragm of the speaker SP in the closed chamber 4, m1 is the equivalent air mass of the sub chamber 5, m2 is the equivalent air mass of the acoustic duct 3, and Sc1 is the equivalent stiffness of the main chamber 2. Is shown. As is apparent from the figure, when the driving force F of the diaphragm is input to the speaker unit SP and the diaphragm is excited, the force directly acts on the air in the sub-chamber 5 and the equivalent stiffness Sc1 of the main chamber 2 Helmholtz resonance occurs in the air equivalent mass m2 of the acoustic duct 3, and bass is reproduced. FIG. 4 shows an equivalent circuit of the speaker system of the first embodiment showing such an operation mode.
[0017]
In an experimental configuration of the speaker system 1 according to the first embodiment based on such an operation principle, a small speaker unit having a diaphragm of 46 mm in diameter is used, the main chamber 2 is set to about 1000 cc, the acoustic duct is set to about 22 cc, and the closed chamber is set. When 4 was about 500 cc and the sub-chamber 5 was about 100 cc to 120 cc, the sound output characteristics were as shown in FIG. 5, and the practical lower limit frequency was about 50 Hz and the upper limit frequency was about 300 Hz. Further, according to the speaker system of the present invention, it was confirmed that the lower limit of the lower limit frequency can be reduced to 30% to 35% of the lowest resonance frequency f0 of the speaker unit.
[0018]
As is clear from the above figures, the speaker unit having a diaphragm of about 46 mm in diameter is quite small, and the main chamber 2 has a very small capacity of about 1000 cc. The system can be completed. Further, according to the first embodiment, the speaker unit SP can be arranged horizontally with respect to the longitudinal direction of the speaker cabinet 1, so that the thickness can be greatly reduced, and a speaker cabinet of an unconventional form can be configured. can do.
[0019]
Next, a second embodiment shown in FIG. 6 to which the basic principle of the present invention is applied will be described. The loudspeaker system shown in FIG. 1 is intended to raise the upper limit frequency, and is capable of reproducing a wide range of bass sound. The feature of the speaker system of the second embodiment is that the diaphragm includes a speaker unit SP1 facing the sub-chamber 5, and the diaphragm has a speaker unit SP2 facing the main chamber 2, and the two speaker units SP1 and SP2 are in phase. It is to be driven by.
[0020]
With this configuration, the speaker unit SP2 directly excites the air in the main chamber 2 as shown in the mechanical diagram of FIG. 7, so that the upper limit frequency can be raised. FIG. 8 shows an equivalent circuit of the speaker system of the second embodiment showing such an operation mode. According to the speaker system of the second embodiment completed as described above, the sound output characteristics include the sound output P1 obtained by the speaker unit SP1 and the sound output P2 obtained by the speaker unit SP2 as shown in FIG. Thus, an acoustic output P3 is obtained, in which low-frequency sound reproduction over a wide band is possible.
[0021]
【The invention's effect】
As described in detail above, according to the invention of claim 1 of the present invention, it is possible to reproduce bass sound that can be practically used even with a small-diameter speaker unit. At the same time, the speaker system can be realized at low cost and excellent in design flexibility. Therefore, a versatile loudspeaker system that can be used for many applications such as audio-visual equipment or housing equipment, which has been difficult to incorporate in the related art, can be provided.
[0022]
According to the second aspect of the present invention, low-frequency sound reproduction over a wide band is possible, and it is easy to reduce and combine the speaker units for medium and high sounds. A sound system can be constructed.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first embodiment of the present invention.
FIG. 2 is an equivalent diagram for explaining the first embodiment of the present invention.
FIG. 3 is a mechanical diagram of the first embodiment of the present invention.
FIG. 4 is an equivalent circuit of the first embodiment of the present invention.
FIG. 5 is a diagram showing sound output characteristics of the first embodiment of the present invention.
FIG. 6 is a sectional view showing a second embodiment of the present invention.
FIG. 7 is a mechanical diagram of a second embodiment of the present invention.
FIG. 8 is an equivalent circuit of a second embodiment of the present invention.
FIG. 9 is a diagram showing acoustic output characteristics of a second embodiment of the present invention.
FIG. 10 is a sectional view of a conventional Kelton speaker system.
11 is a diagram showing acoustic characteristics of the speaker system of FIG.
12 is a diagram showing a state of occurrence of a failure of the speaker system of FIG.
[Explanation of symbols]
1 Speaker cabinet 2 Main room 3 Acoustic duct 4 Sealed room 4a Baffle plate 5・ Secondary room SP ・ ・ ・ ・ ・ ・ Speaker unit

Claims (2)

In a speaker system in which a diaphragm of a speaker unit faces a main room provided with an acoustic duct, and a back surface of the speaker unit faces a closed room,
A speaker system comprising a sub-chamber connected to the main chamber and having an extremely small volume ratio with respect to the main chamber, wherein a diaphragm of a speaker unit faces the sub-chamber. In a speaker system in which a diaphragm of a speaker unit faces a main room provided with an acoustic duct, and a back surface of the speaker unit faces a closed room,
A sub-chamber connected to the main chamber and having an extremely small volume ratio with respect to the main chamber is formed. The diaphragm of the first speaker unit faces the sub-chamber, and the second speaker is disposed in the main chamber. A speaker system wherein a diaphragm of a unit is exposed.

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