JP3664043B2 - Speaker system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a speaker system for a high sound pressure, low frequency range, such as a so-called subwoofer, which is used in a sound reproducing device or the like.
[0002]
[Prior art]
A double bass reflex method has been widely known as a method for increasing the sound pressure in a low frequency range of a speaker system. For example, an example is shown in pages 26 to 29 of “CRAFT HAND BOOK SPEAKER-CRAFT-MANUAL VOL.3” which is a design example collection of speaker systems issued by Fostex Corporation.
[0003]
The speaker system described in the design case collection has two cavities that are divided into a speaker unit side and a bass reflex port side by a partition plate inside the enclosure of the bass reflex speaker system. Has a port. By utilizing the resonance caused by these two cavities and ports, the sound pressure in the low band can be made higher than that of the bass reflex system.
[0004]
[Problems to be solved by the invention]
However, according to the conventional configuration, the following problems occur.
[0005]
1. The double bass reflex system requires a partition plate and a port compared to the bass reflex system, which greatly increases the cost.
[0006]
2. The effect of increasing sound pressure is small due to the mechanical resistance of the port of the partition plate.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional problems, suppress a significant cost increase, and reduce the mechanical resistance of the partition plate port to improve the sound pressure in a low range.
[0008]
[Means for Solving the Problems]
First speaker system according to the invention of the present invention, the interior of the enclosure of the bass reflex type speaker system, the first cavity and the two cavities of the second cavity which is divided into the side of the side and the bass reflex port of a speaker unit by the inner partition plate comprising a, and an opening for connecting the two cavities, a speaker system configured only with the inner wall surface of the cross section of the partition plate enclosure, lower the peak frequency of the impedance curve of the loudspeaker system When f1, f2, and f3 are set in order from the side, the enclosure is configured so that resonance of f2 occurs by the total execution cavity of the enclosure, the speaker unit, and the bass reflex port, the first cavity, the speaker unit, The opening causes resonance of f3. Configured urchin, a speaker system that is configured to being a f3 / f2 ≦ 5.
[0009]
With this configuration, only the opening hole can function as a port due to the effect of the opening end correction. Therefore, it is possible to obtain the same performance as in the case of providing a conventional port only by providing an opening with an inner wall surface of the enclosure and a cross section of the middle partition plate in a part of the middle partition plate.
[0010]
On the other hand, mechanical resistance is generated by the flow of air in the port. The mechanical resistance of this port is a factor that lowers the sound pressure in the low frequency range. Generally, in order to reduce the mechanical resistance of the port, it is necessary to increase the opening area of the port. Furthermore, in order to increase the opening area of the port and make the resonance frequency the same, the port must be lengthened.
[0011]
In the conventional speaker system, there is a limitation in the configuration in order to increase and lengthen the opening area of the partition plate port. Further, when a large partition plate port is used, the effective internal volume of the enclosure is reduced by the volume occupied by the port, so that the low-band resonance frequency is increased.
[0012]
In the speaker system according to the first aspect of the present invention, since the wall surface of the enclosure which is generally long enough as a port attached to the partition plate can function as a port, the same resonance frequency as that of the conventional partition plate port. When obtaining the above, the opening area can be increased as compared with the conventional case. As a result, the mechanical resistance of the port can be reduced, and low-frequency reproduction with a high sound pressure can be realized.
[0013]
The speaker system according to the second aspect of the present invention includes a first cavity and a second cavity divided into a speaker unit side and a bass reflex port side by a partition plate inside an enclosure of the bass reflex speaker system. A speaker system comprising two cavities, and an opening connecting the two cavities is configured only by a cross-section of the partition plate and an inner wall surface of the enclosure, the speaker of the enclosure constituting the opening The speaker system is characterized in that all of the inner wall surface is joined to the partition plate. In the configuration of the first invention, there is a possibility that the speaker system is joined in a state of moving to the inner wall surface side of the enclosure where the partition plate is not joined at the time of mass production assembly of the speaker system. In this case, an irregular small gap is formed between the inner partition plate and the inner wall of the enclosure, and the flow of air to the small gap causes a decrease in low-frequency sound pressure due to an increase in mechanical resistance, and wind noise is generated. To do. However, by adopting the configuration shown in the present invention, it is possible to prevent the low-frequency sound pressure from decreasing and to prevent the generation of abnormal sounds such as wind noise.
[0014]
A speaker system according to a third invention of the present invention is characterized in that, in addition to the second invention, the field part of the speaker unit and the partition plate are joined.
[0015]
When the diaphragm vibrates, a vibration reaction of the vibration system is generated in the field part of the speaker unit. Due to the vibration reaction generated in the field part, the field part is unnecessarily vibrated, and this vibration is transmitted to the front baffle of the enclosure, which is a fixed part of the speaker unit, via the frame. As a result, the front baffle vibrates greatly, and unnecessary noise is greatly generated from other than the speaker unit. However, since the field unit of the speaker unit can be fixed to the partition plate by the configuration shown in the present invention, vibration from the field unit, which is a source of vibration due to reaction, is transmitted to the partition plate inside the enclosure. Can be transmitted, and unnecessary vibration of the front baffle can be reduced.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
(Embodiment 1)
1 and 2 are cross-sectional views of the low-frequency reproduction speaker system according to the first embodiment. In this speaker system, two speaker units 1 connected in series with a diameter of 17 cm are attached to a wooden enclosure 2 having internal dimensions of a width of 175 mm, a height of 418 mm, and a depth of 278 mm. The two speaker units have the same specifications, each having an effective vibration mass of 14 g and an effective vibration radius of 5.5 cm. The speaker unit 1 is attached to the lower front side of the enclosure.
[0018]
A second port 3 having an inner diameter φ40 and a length of 50 mm is attached to the lower rear side of the enclosure. Furthermore, a wooden partition plate 4 having a thickness of 12 mm is arranged inside the enclosure. The total inner volume of 19.5 liters is divided into a cavity on the speaker unit side, that is, the first cavity 5 and a cavity on the second port side, that is, the second cavity 6 by the partition plate 4. The distance from the inner wall surface of the baffle to which the speaker unit 1 is attached to the front surface of the middle partition plate 4 is 82 mm, and the distance from the rear surface of the middle partition plate 4 to the inner wall surface of the rear surface of the enclosure is 184 mm. The respective internal volumes are 6 liters for the first cavity 5 and 13.5 liters for the second cavity 6. An opening 7 having an opening area of 113 cm ² is constituted by the inner wall of the upper part of the enclosure and the upper end cross-section of the partition plate 4. Due to the effect of opening end correction, the effective port length of the opening is about 130 mm. The side and bottom surfaces of the middle partition plate 4 are in close contact with the inner wall of the enclosure, and there is no air circulation. In addition, the enclosure cross-sectional area by the enclosure inner wall surface to which the partition plate 4 is attached is 732 cm ² .
[0019]
The operation of the speaker system configured as described above according to the present embodiment will be described. FIG. 3 shows an equivalent circuit of the speaker system of the first embodiment.
[0020]
4 and 5 show a conventional speaker system. That is, a first port 8 having an inner diameter φ80 and a length of 30 mm is attached to the upper part of the partition plate 14. The speaker unit 1, the enclosure 2, and the second port 3 are the same as those of the speaker system according to the first embodiment.
[0021]
FIG. 6 shows a comparison between measured sound pressure frequency characteristics and impedance characteristics of the speaker system according to the first embodiment and the conventional speaker system. A and C indicate respective sound pressure frequency characteristics, and B and D indicate respective impedance characteristics.
[0022]
Regarding the sound pressure frequency characteristic, the characteristic A of the first embodiment is that the sound pressure of the flat portion of the low frequency characteristic is 89.5 dB, and a frequency of 86.5 dB, which is −3 dB from this sound pressure, that is, general This frequency is called the cut-off frequency, but it is 55 Hz. On the other hand, the characteristic C of the conventional speaker system is that the sound pressure of the flat portion is 88.5 dB, and the sound pressure frequency of -3 dB, that is, the cutoff frequency is 55 Hz. The same.
[0023]
Next, the impedance characteristics B and D will be described. From FIG. 6, the frequency of the peak of the impedance characteristic is 27 Hz, 75 Hz, and 240 Hz from the low frequency side. These will be referred to as f1, f2, and f3. f3 / f2 = 3.2. The resonance of f1 is due to the resonance of the first cavity and the opening or the first port, the speaker unit, and the second cavity and the second port. The resonance of f2 is resonance by the total effective cavity of the enclosure, the speaker unit, and the second port. Further, the resonance of f3 is a resonance caused by the first cavity, the speaker unit, and the opening or the first port. From the figure, it can be confirmed that the respective resonance frequencies are the same, but the magnitude of the impedance is larger in the speaker system according to the present embodiment. This is because, in the speaker system shown in the first embodiment, the wall surface of the enclosure can function as a port, and due to the effect of opening end correction, the effective radius of the opening portion × 2 + the partition wall thickness is substantially an effective port. This is because the port opening area can be increased without increasing the resonance frequency because the length is increased, and as a result, the mechanical resistance of the port is decreased.
[0024]
As described above, in the speaker system according to the present embodiment, even when the cutoff frequency is the same, it is possible to increase the sound pressure as compared with the related art.
[0025]
Next, a speaker system in which the mechanical resistance equivalent to that of the first embodiment, that is, the opening area of the first port is the same as that of the first embodiment will be described.
[0026]
7 and 8 are speaker systems having a first port having the same opening area as that of the speaker system according to the first embodiment. That is, the first port 18, which is a resin molded product having an inner diameter φ120, a length of 132 mm, and a thickness of 3 mm, is attached to the middle partition plate 24. Other configurations are the same as those of the speaker system according to the first embodiment. FIG. 9 shows a characteristic comparison with the first embodiment. That is, since the opening area of the first port is large, the mechanical resistance can be reduced, and the resonance between the first cavity and the first port, that is, the level near 240 Hz of the impedance characteristic is equivalent to that of the speaker system according to the first embodiment. Can be. Therefore, on the contrary, it can be seen that the opening of the configuration of the speaker system according to the first embodiment is equivalent to a port having an inner diameter of 120 and a length of 132 mm. This port length corresponds to the equivalent radius of the opening × 2 + thickness of the partition plate. In other examples, it has been confirmed that this relationship is almost the same.
[0027]
In the speaker system shown in FIGS. 7 and 8, since the large port is provided in the second cavity, the effective cavity of the second cavity becomes small. As a result, the resonance frequency related to the second cavity is increased, the sound pressure of 70 Hz or less is decreased by about 1 dB, and the cutoff frequency is increased to 58 Hz. As described above, in the conventional configuration, even if an attempt is made to reduce the mechanical resistance of the first port to prevent a decrease in sound pressure due to the mechanical resistance, the effective volume of the second cavity or the first cavity is reduced, so that the cutoff is achieved. The frequency increases.
[0028]
Next, in the speaker system according to the first embodiment, the optimum range of the resonance frequency by the first cavity and the opening will be described.
[0029]
FIG. 10 shows a comparison of measured characteristics when the resonance frequency f3 is high with the first cavity and the first port of the speaker system according to the present invention and the conventional speaker system under the same conditions with a cutoff frequency of 55 Hz. It is. As for the specifications of the speaker system, the distance from the inner wall surface of the mounting baffle of the speaker unit 1 to the front surface of the middle partition plate is 41 mm, and the distance from the rear surface of the middle partition plate to the inner wall surface of the rear surface of the enclosure is 225 mm. The respective internal volumes are 3 liters for the first cavity and 16.5 liters for the second cavity. Other specifications are the same as those of the speaker system according to the first embodiment.
[0030]
Since the volume of the first cavity is smaller than that of the speaker system according to the first embodiment, the resonance frequency f3 due to the first cavity and the opening is increased. The peak frequency of the impedance characteristic, that is, the resonance frequency is 27 Hz, 75 Hz, and 390 Hz from the low frequency side, and f3 = 390 Hz. Further, f3 / f2 = 5.2.
[0031]
Regarding the sound pressure frequency characteristics G and J at this time, there is almost no difference between the speaker system according to the present invention and the conventional speaker system. Also, there is almost no difference between the impedance characteristics H and K.
[0032]
The reason for this will be described. As described above, the resonance frequency of f3 is determined by the size of the first cavity and the opening. The resonance frequency of f2 is resonance by the total effective cavity of the enclosure, the speaker unit, and the second port, and is not affected by the position of the partition plate and the shape of the opening. Here, the conditions for increasing f3 are when the volume of the first cavity is small and when the size of the opening is large. FIG. 3 shows an equivalent circuit diagram of the double bass reflex speaker system. The former state described above is a case where C1 in the figure is small and Rc1 is large, and the latter state is (Sd / This is a case where Sp1) ² · Mp1 is large and (Sd / Sp1) ² · Rp1 is small. In any case, the portion of C1, Rc1, and the portion of (Sd / Sp1) ² · Mp1, (Sd / Sp1) ² · Rp1 can be ignored, that is, the resonance effect by the first cavity and the opening. Is so small that the advantage of the speaker system according to the present invention over the conventional speaker system is lost.
[0033]
Thus, it can be seen that the resonance frequency by the first cavity and the opening has an appropriate frequency range. Here, an appropriate range of the resonance frequency was found by simulating low-frequency sound pressure frequency characteristics and impedance characteristics using the equivalent circuit shown in FIG. As a result, assuming that the peak frequency of the impedance curve of the speaker system according to the configuration of the present application is f1, f2, and f3 from the lower side, f3 / f2 ≦ 5 is an appropriate range, and if this condition is not met, the conventional double bass reflex system It was confirmed that the performance was equivalent to that of the speaker system.
[0034]
In the first embodiment, two speaker units having the same specification are used, but it goes without saying that even if the specifications are different, even if one speaker unit is used, equivalent performance can be obtained. . Furthermore, although wood with a thickness of 12 mm is used as the inner partition, it goes without saying that even if the thickness is changed, equivalent performance can be obtained by changing the inner partition opening area.
[0035]
(Embodiment 2)
FIG. 11 is a cross-sectional view of the speaker system according to the second embodiment. That is, the middle partition plate 34 is made of wood having a thickness of 12 mm, and has an opening 17 by a corner cut of 150 mm at the upper corner. Other specifications are the same as those of the speaker system according to the first embodiment. With this configuration, the middle partition plate 34 has joints on the inner wall surfaces of all the enclosures forming the opening. In the loudspeaker system according to the first embodiment, the upper inner wall surface of the enclosure inner wall surface does not have a joint, so that there is a risk of being displaced and fixed upward during mass production assembly. As a result, a slight gap is formed in the lower part of the inner partition, and when air flows through the small gap, the mechanical resistance increases, the sound pressure decreases, and abnormal noise such as wind noise may occur. In order to prevent displacement of the partition plate, a method using another member for positioning is also conceivable. However, the cost increases due to the addition of members and the increase in man-hours.
[0036]
However, in the speaker system according to the second embodiment, since the partition plate has joints on all the inner wall surfaces of the enclosure constituting the opening, the partition plate is not fixed at an irregular position during assembly. Quality can be improved with almost no cost increase.
[0037]
In the speaker system according to the second embodiment, the partition opening is provided in the partition corner . However, the configuration having the opening 27 by the notch at the upper end of the partition plate 44 as shown in FIG. It goes without saying that an effect can be obtained.
[0038]
(Embodiment 3)
FIG. 13 is a cross-sectional view of the speaker system according to the third embodiment. That is, the field part 10 and the partition plate 4 of the speaker unit 1 are joined by the wooden spacer 9 having an outer diameter of 70 and a thickness of 20 mm. Other specifications are the same as those of the speaker system according to the first embodiment. With this configuration, the speaker unit 1 is fixed not only to the front baffle of the enclosure but also to the partition plate in the enclosure.
[0039]
Generally, when the diaphragm vibrates, the vibration reaction of the vibration system is generated in the field part 10. Also, this reaction generates unwanted vibrations in the field part. In the speaker system according to the first embodiment, unnecessary vibration of the field unit 10 due to the reaction of the vibration system is transmitted to the front baffle of the enclosure, which is a fixed part of the speaker unit, via the frame. As a result, the front baffle vibrates greatly, and unnecessary noise is greatly generated from other than the speaker unit. However, in the speaker unit according to the third embodiment, since the field portion can be fixed to the partition plate, vibration from the field portion can be transmitted to the partition plate inside the enclosure, and the front baffle can be transmitted. It becomes possible to reduce unnecessary vibration.
[0040]
Although the wooden spacer is used in the third embodiment, it goes without saying that the same effect can be obtained even when a metal spacer such as aluminum is used. Furthermore, it goes without saying that the same or a larger effect can be obtained even if a spacer made of a viscoelastic material is used. It goes without saying that the same effect can be obtained even if the rear surface of the speaker unit and the partition plate are directly fixed without using a spacer.
[0041]
In addition, it goes without saying that the present invention is not limited to the above example.
[0042]
【The invention's effect】
As described above, according to the speaker system of the present invention, the inside of the enclosure of the bass reflex speaker system includes the two cavities divided into the speaker unit side and the bass reflex port side by the partition plate, and the two By configuring the opening connecting the cavities only with the section of the partition plate and the inner wall surface of the enclosure, the same operation as when another port is arranged on the partition plate as in the prior art can be performed. Another port can be omitted. As a result, the port material cost and assembly man-hours can be reduced.
[0043]
Furthermore, with the above-described configuration, the equivalent radius of the opening × 2 + thickness of the partition plate substantially serves as the effective port length of the opening, that is, even if the opening area of the opening is increased, the port length can be increased. it can. As a result, the mechanical resistance of the opening of the partition plate can be reduced without increasing the resonance frequency due to the opening of the partition plate, the loss due to the mechanical resistance can be minimized, and the sound pressure level can be increased. .
[0044]
Further, according to the speaker system of the present invention, since the partition plate has joints on a part of all the inner wall surfaces of the enclosure constituting the opening, the partition plate is fixed at an irregular position at the time of mass production assembly of the speaker system. It will not be done. As a result, there is no decrease in sound pressure due to an increase in mechanical resistance, and there is no occurrence of abnormal sounds such as wind noises, thereby improving quality.
[0045]
Further, according to the speaker system of the present invention, the field part of the speaker unit that is the source of the vibration reaction can be directly fixed to the partition plate, so that the vibration of the front baffle can be suppressed. It is possible to reduce unnecessary noise.
[0046]
Thus, the speaker system of the present invention has great industrial value.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a speaker system according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view of AA showing the speaker system according to Embodiment 1 of the present invention. Fig. 4 is a cross-sectional view showing a conventional speaker system. Fig. 5 is a cross-sectional view of BB showing a conventional speaker system. Fig. 6 is a speaker system according to Embodiment 1 of the present invention and a conventional speaker system. Fig. 7 is a cross-sectional view of a conventional speaker system having a port having the same opening area as that of the partition plate opening of the speaker system according to the first embodiment. FIG. 8 is a cross-sectional view taken along the line CC of the conventional speaker system having a port having the same opening area as the opening of the partition plate of the speaker system according to the first embodiment. 9 is a frequency characteristic diagram showing measured sound pressure frequency characteristics and impedance characteristics of the speaker system according to the first embodiment and the conventional speaker system shown in FIGS. 7 and 8. FIG. 10 shows the case where the cavity on the speaker unit side is small. FIG. 11 is a frequency characteristic diagram showing sound pressure frequency characteristics and impedance characteristics of a speaker system according to the present invention and a conventional speaker system. FIG. 11 is a cross-sectional view showing a speaker system according to a second embodiment of the present invention. FIG. 13 is a cross-sectional view showing a speaker system according to a second embodiment. FIG. 13 is a cross-sectional view showing a speaker system according to a third embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Speaker unit 2 Enclosure 3 2nd port 4, 14, 24, 34, 44 Partition plate 5 1st cavity 6 2nd cavity 7, 17, 27 Opening part 8 and 18 1st port 9 Spacer 10 Field part

Claims (4)

Inside the enclosure of the bass reflex speaker system, there are two cavities, a first cavity and a second cavity, which are divided into a speaker unit side and a bass reflex port side by a partition plate, and the two cavities are connected A speaker system comprising an opening to be formed only by a cross section of the partition plate and an inner wall surface of the enclosure,
When the peak frequency of the impedance curve of the speaker system is set to f1, f2, f3 in order from the lowest,
And total execution cavity of the enclosure, and the loudspeaker unit, the resonance of f2 is configured to produce by the bass reflex port,
Wherein the first cavity, and said loudspeaker unit is configured so that the resonance of f3 by the opening occurs,
f3 / f2 ≦ 5 wherein the to Luz speaker system to be produced.   Inside the enclosure of the bass reflex speaker system, there are two cavities, a first cavity and a second cavity, which are divided into a speaker unit side and a bass reflex port side by a partition plate, and the two cavities are connected A speaker system that includes only the cross section of the partition plate and the inner wall surface of the enclosure, and the inner wall surface of the enclosure that forms the opening portion is all joined to the partition plate. The speaker system characterized by this. Loudspeaker system of claim 1, wherein the inner wall surface of the enclosure which constitutes the opening are joined with all the intermediate partition plate.   4. The speaker system according to claim 1, wherein the field unit of the speaker unit and the partition plate are joined.

Images