JPH02288596A - Speaker system - Google Patents

Abstract

PURPOSE:To suppress the resonance frequency component due to a sound guide path selectively by providing a resonator sound absorbing material absorbing the resonance frequency component of the sound guide path so as to act on the sound guide path. CONSTITUTION:Resonator sound absorbing bodies 51, 52 are provided respectively to upper and lower outer sides of an expanded tube part 41 of a sound guide path 4 to absorb the resonance. The resonator sound absorbing bodies 51, 52 have ports 61, 62 opened toward the middle of the sound guide. 4, especially toward the border between the expanded tube part 41 and the parallel tube part 42 to form a Helmhortz resonator. The resonance frequency of the upper resonator 51 is slightly higher than the 0-th order resonance frequency of the sound guide path 4, while the resonance frequency of the lower resonator 52 is slightly lower than the resonance frequency. Thus, the component of the resonance frequency from the sound guide path is absorbed selectively. Then the accurate reproducing sound is obtained with high efficiency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention removes peaks in frequency characteristics caused by the resonance frequency of the sound guide in a speaker system that includes a sound guide in front of the speaker. Regarding the speaker system.

[Conventional technology]

Conventionally, the sound guide path of a speaker has been designed so that the cross-sectional area of the sound guide gradually expands, as in the case of a so-called horn speaker, to adjust the acoustic impedance, improve electroacoustic conversion efficiency, and reproduce accurate sound. The purpose was to obtain.

However, with the recent development of audiovisual devices, various types of speaker systems are required, and sound guide paths that are not necessarily acoustically rational have come to be used.

For example, in an example of a speaker system developed for a large television set, the speaker is installed using the space behind the side of the cathode ray tube, and a sound pipe installed on the side is used to guide sound waves to the front. Efforts have been made to prevent noise and ensure sound quality regardless of the installation location.

However, with this method, due to storage space constraints, it is not possible to design the sound pipe so that the cross-sectional area increases monotonically, and the sound pipe is formed in the shape of a long slit, which is acoustically similar to a straight sound pipe.

In such a sound guide, an acoustic tube with one end open is formed, so the specific frequency fn determined by the effective pipe length I fn= (C/(4 net)] (2n+1) (
n=o, t, 2. ---), it is well known that the resonance phenomenon occurs in the reproduced sound, which causes the sound quality to deteriorate (C is the speed of sound). In order to suppress the resonance and improve the sound quality in such a case, it is known that a sound absorbing material is used on the inner surface of the sound guide, and the sound absorbing material is attached to form a horn, for example. This known method makes it possible to suppress the peak on the harshness frequency characteristic to some extent.

[Problem to be solved by the invention]

However, in the case of the above known method, the resonance generated in the sound guide has a sharp peak determined by the effective sound guide length, while the sound absorber exhibits sound absorption characteristics with weak frequency selectivity. However, the suppression of resonance sounds is not sufficient to fully satisfy listeners who are sensitive to sound quality, and the reproduced sound is generally absorbed, reducing the output sound pressure level. In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a speaker system that selectively suppresses resonance frequency components caused by a sound guide path.

[Means to solve the problem]

The present invention provides a speaker system in which sound waves are guided to an opening by a sound guide path provided on the front surface of the speaker unit.
The present invention is characterized in that a resonator sound absorber that absorbs the resonant frequency component of the sound guide is provided in a state that acts on the sound guide. The resonant frequency of the resonator sound absorber is sufficiently close to the resonant frequency of the sound guide, or includes a portion where the resonant frequency is a frequency close to each of a low frequency side and a high frequency side across the resonant frequency. Preferably, the configuration is configured.

Further, in the speaker system of the present application, it is preferable that the resonator sound absorber is configured by a portion that absorbs the fundamental resonance frequency component of the sound guide and a portion that absorbs the higher-order resonance frequency component.

In the speaker system of the present invention, the opening of the resonator sound absorber is provided so as to act on the sound guide, but it may be provided at an intermediate portion of the sound guide. It is preferable to provide the speaker side end portion of the speaker.

Furthermore, when the resonator sound absorber of the speaker system of the present invention is integrally provided on the outside across the wall of the sound guide,
Alternatively, there is a great advantage in manufacturing when it is integrally provided in a rear cabinet disposed at the rear of the speaker. Further, it is possible to form an expansion tube portion in the sound guide path and arrange a resonator sound absorber outside of the expansion tube portion.

The present invention is a speaker system that further includes a sound absorbing material in the sound guide path.

[For production]

Since the resonator sound absorber is configured to cause resonance at approximately the same frequency as the resonant frequency of the sound guide, when the sound guide is excited to resonate by the sound wave emitted by the speaker, the resonator sound absorber will cause resonance. Sound waves cause resonance. At this time, air actively enters and exits at the opening of the resonator sound absorber, and the sound wave energy of the resonant frequency is consumed, thereby exhibiting a sound absorption effect for the resonant frequency sound wave.

If the resonance frequency of the resonator sound absorber is configured to be sufficiently similar to the resonance frequency of the sound guide, the sound absorption effect will be significant. In addition, if the configuration includes parts whose resonant frequencies are near frequencies on the low frequency side and high frequency side, sandwiching the resonant frequency, an appropriate width will be created in the resonant frequency range, so it may be difficult to design and manufacture it. A sufficient sound absorption effect can be obtained even if the accuracy is not good.

Furthermore, in a speaker system in which the resonator sound absorber is composed of a part that absorbs the fundamental resonance frequency component of the sound guide and a part that absorbs the higher-order resonance frequency components, even the higher-order frequency components are absorbed by the resonance noise. Therefore, extremely good reproduced sound can be obtained.

Since the sound guide forms an acoustic tube with one end open, a corresponding resonance, or standing wave, is generated inside the sound guide, but when the opening of the resonator sound absorber is placed in the middle of the sound guide, , it acts well on the energy of the standing waves, making it easy to obtain a sound absorption effect. Furthermore, since the maximum sound pressure of the standing wave exists at the end on the speaker side, which is the end on the closed pipe side, when the opening of the resonator sound absorber is provided at the end on the speaker side of the sound guide, the sound absorption effect is particularly remarkable.

Furthermore, when the resonator sound absorber of the speaker system of the present invention is integrally provided on the outside across the wall of the sound guide, the shape and corresponding opening shape for the resonator sound absorber to fully function. The position can be designed relatively freely, and the overall shape can be made compact.
It is also extremely easy to mold it with synthetic resin or the like.

In particular, when forming an expansion tube part in the sound guide path, a dead space is created on the outside thereof, so if this space is used as a storage space for the resonator sound absorber, the entire speaker system can be made particularly compact. Further, even when the speaker is integrally provided in a rear cabinet disposed on the rear side of the speaker, the degree of freedom in design and manufacturing is large and manufacturing is easy.

In a speaker system that includes a resonator sound absorber acting on a sound guide and a sound absorbing material inside the sound guide, specific components of the resonant frequency components generated in the sound guide are selectively absorbed. At the same time, resonance frequency components not selected in design and other noise components can be smoothed.

〔Effect of the invention〕

According to the present invention, since the resonance frequency component emitted by the sound guide is selectively absorbed, it is possible to provide a speaker system that can reproduce accurately reproduced sound with high efficiency. In addition, design and manufacturing errors can be easily absorbed, and when it is formed from a resin molded product, there is no need to combine other materials, so manufacturing man-hours can be saved, and a speaker system with high industrial value can be provided.

[Example 1] Hereinafter, the present invention will be described in detail with reference to the drawings. The figure shows an example in which the present invention is implemented in a television speaker system.

As shown in FIG. 6, in a television, a speaker (3) is housed in a space behind the side of the cathode ray tube (2), and the sound wave is guided to the front of the side of the cathode ray tube by a sound guide (4). The installation width of the television set (1) is reduced, the sound field is not disturbed by the installation location, and the sound image is localized at a good position close to the screen. The speaker system used for this purpose consists of a speaker (3) and a bass reflex speaker, as shown in Figure 1.
The speaker system (10) is composed of a rear cabinet (11) having a rear cabinet (12) and a sound guide path (4) provided in the front of the speaker. It has no choice but to have a special shape as shown in the figure. The sound guide path (4) that guides the sound from the front of the speaker to the slit-shaped opening on the side surface of the cathode ray tube is manufactured by joining an inner member and an outer member molded from synthetic resin into one piece. Due to the above-mentioned constraints, the sound guide path (4) has an enlarged tube section (41) that expands into a horn shape from the front of the speaker to the middle of the side of the cathode ray tube, and a cross-sectional area along the side of the cathode ray tube until it reaches the front. Parallel tube part that does not change (4
2). Therefore, the cross-sectional area change of the sound guide path from the sound source to the opening cannot be monotonically increased.
From an acoustical standpoint, the sound guide must be similar to a straight acoustic tube. Therefore, resonance of frequency fn=c(2n+1)/(4 lines l) occurs in the sound guide path. Here, C is the speed of sound, l is the effective length of the sound guide, and n is an integer. From the dimensions of the speaker system actually applied, when n in the above formula is O, the frequency is around 350-400Hz, nfJ(1
At this time, resonance occurs around 1050-1200Hz, which has a large effect on the hearing of the listener. Furthermore, higher-order resonances are also unavoidable when listening to music.

Therefore, as a first embodiment of the present invention, FIGS.
As shown in the figure, one resonator sound absorber (51), (5
2), which absorbs resonance. Each resonator sound absorber (51), (52) is located in the middle of the sound guide (4), especially in the enlarged tube section (41) and the parallel tube section (42).
An opening or port (61
), (62) to form a so-called Helmholtz resonator. The resonant frequency fr in the Helmholtz resonator is determined by % fr=(C/2π) (S/V(12+0.8d)). However, ■ is the volume of the resonator, S is the opening area, d is the diameter of the port, and l is the length of the port. The resonance frequency frl of the upper resonator (51) is 0 of the sound guide (4).
slightly higher than the next resonant frequency fO, while the lower resonator (
52) is designed so that the resonance frequency fr2 is slightly lower than the resonance frequency fO.

The results of measuring sound pressure frequency characteristics while operating the speaker system of the present invention are shown in FIGS. 9 to 12.

The figures show the results measured with a sound pressure detection microphone set in front of the opening of the sound guide path, converted to a distance of 1 m. In each figure, the lower graph shows the output sound pressure level when driven by a speaker. The above graph, plotted in dB against frequency, is an impedance characteristic diagram. FIG. 9 shows a resonant state of the sound guide without a resonator sound absorber. FIG. 1θ shows the measurement results of the above-mentioned Example 1, regarding a speaker system to which a resonant sound absorber using two resonant frequencies frl and fr2 sandwiching the zero-order resonant frequency fO is added. The resonance that showed a peak of 7 dB near 400 Hz (Figure 9A) was found at 300 Hz and 400 Hz.
It can be seen that due to the addition of the two resonator sound absorbers having resonance nearby, the attenuation was approximately 4 dB (Fig. 10C), proving a very remarkable effect. The reason why two resonance frequencies are prepared with one resonance frequency in between is to absorb the difference in resonance frequency that may occur due to design or manufacturing and obtain a reliable sound absorption effect, but this figure covers this. It has been shown that the objective can be fully achieved even when choosing a resonant frequency that is quite far from the resonant frequency.

[Embodiment 2] FIGS. 3 and 4 are drawings illustrating another embodiment of the speaker system of the present invention. Resonator sound absorber (53), (5
4) openings (63) and (64) are provided at the side portions of the front surface of the speaker. Since the standing waves generated in the acoustic tube with one end open have a maximum sound pressure at the end on the closed tube side, the resonator sound absorbers (53) and (54) of this embodiment have a remarkable sound absorption effect. ``Also, a resonator sound absorber (55) corresponding to the resonant frequency is provided outside the sound guide path and between the television set outer frame wall and an opening (65).

An example in which a suitable number of (66) are provided on the outer wall of the sound guide expansion tube portion (41) is shown by dotted lines. Since the resonant frequency is determined for each aperture by the shape of the aperture and the space equivalently formed by the rear portion thereof, these are designed to match the resonant frequency of the sound guide.

FIG. 11 shows the measurement results of a speaker system in which the opening of the resonator sound absorber was provided in the expansion tube portion of the sound guide. The resonance frequency is set to match the zero-order resonance frequency. The 7 dB peak shown in FIG. 9A was completely absorbed and flattened (FIG. 11D), demonstrating a significant sound absorption effect.

Furthermore, Fig. 12 shows a case in which the opening of the resonator sound absorber is provided at the speaker side end, and a resonator sound absorber having a resonant frequency corresponding to the higher-order resonance frequency (Fig. 9B) is added. The measurement results were shown. As shown in E in the figure, approximately 4 dB
were improved.

[Example 3] As shown in FIG. 4, the resonator sound absorber (53),
If a porous sound-absorbing material (13) made of fibers such as cloth, tongue, glass wool, or foamed resin is further attached to the inner wall of the sound guide path (4) equipped with (54), resonance components can be selectively removed. resonator sound absorber (53), (
54) and a sound absorbing material (13) that generally smooths the acoustic characteristics.
) By taking advantage of each characteristic, the speaker system exhibits extremely desirable reproduction characteristics.

FIG. 13 shows the measurement results when the sound absorbing material (13) was attached to the sound guide path shown in FIG. 1 and FIG. 2. A resonator sound absorber (53) that absorbs resonance frequencies as seen in the high frequency range of FIGS. 1O to 12.

In the speaker system using only (54), the acoustic characteristics have many sharp peaks, whereas the sound absorbing material (13
), it can be seen that these are considerably smoothed out.

[Example 4] Figures 7 and 8 show a television set in which the speaker system (10) of the present invention incorporating a woofer and a tweeter (9) are separately attached to improve sound quality. It is a drawing. Tweeters (9) for reproducing high-frequency sounds are attached to the left and right upper sides of the front cabinet (1) of the television set from the back side with screws so as to radiate sound forward. Furthermore, the main speaker system (10) incorporating a woofer is fixed to the side of the cabinet (1) with screws so that its opening is located at the front of the set, adjacent to the left and right sides of the cathode ray tube (2). . In this way, even if you build an entire acoustic system by applying this application only to the main speaker, where sound guide resonance is a particular problem, and not applying it to the tweeter, which does not have this problem, the acoustic effect will be reduced. Of course it will not disappear.

FIG. 7 shows a case where, in addition to the above-mentioned sound system, surround speakers (8) are directly attached to the left and right rear sides of the cabinet (1) from the back side.

[Other Examples]

In the above embodiment, two resonant frequencies are used with the resonant frequency in between, but if a certain level of manufacturing accuracy is achieved or if there is tolerance, it is possible to use two resonant frequencies on each side of the sound guide. It goes without saying that it is sufficient to use one resonator sound absorber for each resonant frequency.

The arrangement of the sound absorbers corresponding to each resonant frequency is not limited to the above-mentioned arrangement, and the object of the present invention can be achieved if an opening is provided in the sound guide path because it acts on the sound guide path.゛For example,
Even if openings are provided in the vicinity of the speaker-side end of the sound guide and in the center, the effect remains the same.

If a resonator sound absorber (7) that opens into the sound guide path (4) is provided in the rear cabinet portion (1) as schematically shown in FIG. 5, the degree of freedom in designing the arrangement of members can be increased.

In the above embodiment, the front surface of the speaker is the radiation surface,
Although the case where the sound guide is placed in front of the speaker is shown,
Even when the rear surface of the speaker is the radiation surface and the sound guide path is located behind the speaker, the sound absorption effect of the resonator sound absorber remains unchanged.

Furthermore, it goes without saying that the speaker may be of any type.

The above describes an example in which the present invention is applied to a speaker system used in a television. However, the technical idea of the present application is for example in a cockpit chinia-type viewing device or a music listening device in a car, etc., which utilizes a sound guide to achieve benefits. It is widely used in certain cases.

Please note that although numbers referring to drawings are added in the description of the claims, these are added for the purpose of aiding understanding and do not limit the technical idea of the claimed invention. Needless to say.

[Brief explanation of drawings]

1 is an elevational sectional view showing one embodiment of the speaker system of the present invention, FIG. 2 is a sectional view of the same, FIG. 3 is an elevational sectional view showing another embodiment of the speaker system of the present invention, and FIG. FIG. 5 is an elevational sectional view showing still another embodiment of the present invention, FIG. 6 is a plan sectional view showing how the speaker system of the present invention is used, and FIG. 7 is a plan sectional view of the present invention. FIG. 8 is a sectional view of the same, and FIG. 9 is a perspective view showing still another embodiment.
13 are sound pressure frequency characteristic diagrams of the sound guide path. (3)...Speaker, (4)...Sound guide, (11)...Rear cabinet, (13)
...Sound absorbing material, (51)...(55)...
- Resonator sound absorber, (61)...(66)...opening.

Claims (10)

[Claims] 1. A speaker system in which sound waves are guided to an opening by a sound guide path (4) provided in the front of a speaker (3), and a resonator sound absorber (
51)--(55) in a state of acting on the sound guide path (4). 2. The speaker system according to claim 1, wherein the resonant frequency of the resonator sound absorbers (51)--(55) is sufficiently close to the resonant frequency of the sound guide path (4). 3. The resonator sound absorbers (51) to (55) have a resonance frequency that is a neighboring frequency on the low frequency side across the resonance frequency of the sound guide (4) and a resonance frequency that is a neighboring frequency on the high frequency side. 2. The speaker system according to claim 1, comprising: 4. 4. The resonator sound absorber (51)--(55) comprises a part that absorbs the fundamental resonance frequency of the sound guide (4) and a part that absorbs the higher-order resonance frequency. The speaker system described in any of the above. 5. A claim in which openings (63) and (64) of the resonator sound absorbers (53) and (54) that act on the sound guide path (4) are provided at an end of the sound guide path on the speaker (3) side. The speaker system according to any one of Items 1 to 4. 6. Any one of claims 1 to 4, wherein openings (61), (62) of the resonator sound absorbers (51), (52) that act on the sound guide path (4) are provided at an intermediate portion of the sound guide path. The speaker system described in Crab. 7. 7. The speaker system according to claim 1, wherein the resonator sound absorbers (51)--(55) are integrally provided on the outside of the sound guide path (4) across a wall. 8. The speaker according to any one of claims 1 to 6, wherein the sound guide path (4) has an expansion tube section (41), and the resonator sound absorbers (51)--(55) are arranged outside of the expansion tube section (41). system. 9. The speaker system according to any one of claims 1 to 6, wherein the resonator sound absorber (7) is integrally provided within a rear cabinet (11) disposed on the rear surface of the speaker (3). 10. The speaker system according to any one of claims 1 to 9, further comprising a sound absorbing material (13) in the sound guide path (4).