JP3467987B2 - Sound reproduction device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound reproducing device having a structure in which sound emitted from a speaker is transmitted to a listener by being reflected by an acoustic reflector.

[0002]

2. Description of the Related Art Recently, in a sound reproducing apparatus, a wide range of reproduced sound is ensured by spreading a sound over a wide range by using a reflector so as to expand a listening area and improve a sense of presence. An example of the above-described conventional sound reproducing device will be described below with reference to the drawings.

FIG. 10 shows the structure of a conventional sound reproducing device. In FIG. 10, a conical acoustic reflector 22 that is also integrally formed with the upper cabinet 25 is arranged on the front surface of the diaphragm of the speaker 21 that is fixed upward in the upper cabinet 25.
The space surrounded by is the antechamber 23. The upper cabinet 25 is fixed to the bottom cabinet 26, and the ceiling decoration cabinet 27 is fixed to the upper cabinets and 25 at the upper part of the acoustic reflector 22.

FIG. 11 is a schematic cross-sectional view showing the structure of the front chamber of the conventional sound reproducing device, FIG. 12 is an electroacoustic equivalent circuit of the conventional sound reproducing device, and FIG. 13 is the acoustic characteristic of the conventional sound reproducing device. . The sound radiated upward from the speaker 21 at the sound pressure P is reflected by the acoustic reflection plate 22, passes through the front chamber 23, and is radiated over a wide range to the space. At this time, under the influence of the characteristic acoustic impedance Zr of the anterior chamber portion 23 shown in FIG. 12, as shown by the solid line in FIG. 13, the acoustic characteristic has a mountain in the middle region as shown by the solid line and the high region is attenuated.

FIG. 14 shows an electrical correction circuit of a conventional sound reproducing device. In FIG. 14, the output of the power amplifier 20 is connected to a speaker 21 via a correction circuit 28. The correction circuit 28 includes an inductor Lt and a capacitor C.
It is a trap circuit configured by connecting t in parallel, and the resonance frequency of the trap circuit is set near the center frequency of the peak in the middle range shown by the solid line in FIG. 13 to cancel the peak in the middle range and correct it to a substantially flat characteristic. To do. The attenuation in the high frequency range is corrected by improving the high frequency characteristic of the speaker 1. By the above correction, the corrected acoustic characteristics shown by the broken line in FIG. 13 are obtained.

[0006]

However, in the conventional sound reproducing device as described above, when the distance between the acoustic reflection plate 22 and the speaker 21 is reduced to make the device thinner, the front chamber portion 23 becomes narrower and the acoustic characteristics are improved. Since the peak in the middle range becomes sharper and higher, it is necessary to increase the Q of the correction circuit 28, and therefore it is necessary to reduce the DC resistance of the inductor Lt to increase the L value or increase the order of the filter. However, there is a problem that it is difficult to reduce the thickness because the cost is increased and the component mounting space is lost.

The present invention is intended to solve the above-mentioned problems of the prior art, and the effect of the characteristic acoustic impedance Zr of the antechamber 23 in the case of thinning can be corrected by a simple and inexpensive electric circuit configuration. The purpose of the present invention is to provide a reproducing apparatus.

[0008]

In order to solve the above-mentioned problems, the sound reproducing apparatus of the present invention is constructed between an acoustic reflector and a speaker installed in front of a speaker for converting an electric signal into acoustic energy. An acoustic equalizer is constructed by providing an opening at the neck of the Helmholtz resonator facing the anterior chamber, and by matching the resonance frequency characteristics of the acoustic equalizer caused by the acoustic characteristic impedance of the anterior chamber with the resonant frequency characteristics of the acoustic equalizer. It is designed to lower the top mountain.

According to the present invention, the acoustic equalizer reduces the influence of the characteristic acoustic impedance Zr of the anterior chamber portion on the acoustic characteristic when the thickness is reduced, and the acoustic characteristic can be corrected even with a simple and inexpensive electric circuit configuration. If necessary, a plurality of acoustic equalizers can be provided, and the resonance frequency can be shifted little by little to enhance the effect.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention of the sound reproducing device according to claim 1 of the present invention is a speaker for converting an electric signal into acoustic energy, and a sound which is installed in front of the speaker and is reflected from the speaker before being transmitted. An acoustic equalizer composed of a Helmholtz resonator having an opening in the neck facing the anterior chamber and an anterior chamber configured between the speaker and the acoustic reflector. It is configured to reduce the peaks on the acoustic characteristics by matching the resonance frequency characteristics of the acoustic equalizer with the peaks on the acoustic characteristics caused by the acoustic characteristic impedance of the front portion, and the influence of the characteristic acoustic impedance Zr of the front chamber on the acoustic characteristics. Acts as reduced by the acoustic equalizer.

According to a second aspect of the invention of the sound reproducing apparatus of the present invention, in the first aspect of the invention, a plurality of acoustic equalizers each including a Helmholtz resonator are provided. By setting the resonance frequencies of the respective acoustic equalizers in a distributed manner in the frequency band of the peaks on the generated acoustic characteristics, the peaks on the acoustic characteristics are lowered over a wide frequency range.

An embodiment of a sound reproducing apparatus of the present invention will be described in detail below with reference to FIGS. 1 to 9.

(Embodiment 1) FIG. 1 shows the structure of an audio reproducing apparatus according to Embodiment 1 of the present invention. In the figure, a conical acoustic reflector 2 having a tip end facing the diaphragm 1a is provided on the front surface, that is, the upper surface of the diaphragm 1a of the speaker 1 mounted on the upper surface of the upper cabinet 5 for converting an electric signal into acoustic energy. The front chamber 3 is a space that is integrally formed with the speaker 1 and is surrounded by the speaker 1 and the acoustic reflector 2. The upper cabinet 5 is integrally fixed to the bottom cabinet 6 to form an acoustic box. The top decoration cabinet 7 has an opening 7a such as a net or a grill and is fixed to the upper portion of the acoustic reflection plate 2 to protect these parts and enhance the design. Unlike the conventional example, the acoustic equalizer 4 is formed integrally with the upper cabinet 5, and the opening 4a of the acoustic equalizer 4 is installed so as to face the front chamber portion 3. It is preferable that the upper cabinet 5, the acoustic reflector 2, the acoustic equalizer 4, and the like are integrally formed of synthetic resin.

In FIG. 1, the sound radiated from the speaker 1 at the sound pressure P is reflected by the acoustic reflection plate 2, passes through the front chamber portion 3 and is widely radiated into the space. FIG. 2 is a schematic cross-sectional view showing the structure of the front chamber portion of the sound reproducing device of the present embodiment, and FIG. 3 is an electroacoustic equivalent circuit of the sound reproducing device. In FIG. 2, sound pressure P is generated from the speaker 1, and the front chamber portion 3 has a characteristic acoustic impedance Zr. Sound equalizer 4
Is composed of a neck portion 8 and a cavity portion 9, and the neck portion 4 and the cavity portion 9 constitute a Helmholtz resonator.

The acoustic resistance of the neck 8 of the acoustic equalizer 4 is Rh, the acoustic mass of the neck 8 of the acoustic equalizer 4 is Mh,
The acoustic capacity of the cavity portion 9 of the acoustic equalizer 4 is C
If h, the resonance frequency is Fh, and Q is Qh, the resonance frequency Fh in this case is

[0016]

[Equation 1]

And Qh is

[0018]

[Equation 2]

It is represented by FIG. 3 shows an electro-acoustic equivalent circuit of the sound reproducing device of the present embodiment, and FIG. 4 shows acoustic characteristics of the sound reproducing device. In FIG. 2, the sound pressure P emitted from the speaker 1 is reflected by the acoustic reflection plate 2, passes through the front chamber portion 3, and is emitted into the space. At this time, due to the influence of the characteristic acoustic impedance Zr of the anterior chamber part 3, the acoustic characteristic is such that a high mountain is formed in the middle region and the high region is attenuated as shown by the solid line in FIG. Here, the resonance frequency Fh of the acoustic equalizer 4 composed of the Helmholtz resonator is adjusted to the center frequency of the high mountain in the midrange, and Qh is brought close to the Q of the mountain, so that the acoustic equalizer 4 absorbs the high midrange. Figure 4
The acoustic characteristics are as shown by the broken line in (a). Here, the resonance frequency Fh of the acoustic equalizer 4 and the Qh of its Q
Is set by adjusting the shapes of the neck portion 8 and the cavity portion 9.

FIG. 5 shows a block diagram of the electrical correction circuit according to the present embodiment. The output of the operational amplifier A1 which is a buffer amplifier of the input is applied to the speaker 1 through the resistor R1, the trap circuit Ls, the high frequency correction circuit 11 and the power amplifier 10. The pseudo inductor Ls has resistors R2 and R
3, the operational amplifier A2, and the capacitor C2. The pseudo inductor Ls constitutes a resonance circuit composed of the capacitor C1 and the resistor R7, and the resistor R1 in combination forms a trap circuit. The high frequency correction circuit 11 includes resistors R4 and R
5, R6 and capacitor C2.

The resonance frequency of this trap circuit Ls is shown in FIG.
Match the frequency of the high mountain in the middle range shown by the solid line in (a),
The Q of the trap circuit is set so that the acoustic characteristic of the resistor R7 becomes flatter. The high frequency correction circuit 11 is set so as to correct the attenuation characteristic in the high frequency shown by the solid line in FIG. FIG. 4B shows the frequency characteristic of the electrical correction circuit of the sound reproducing device in this embodiment configured as described above. The solid line in FIG. 4C shows the acoustic characteristics of the sound reproducing device before correction, and the broken line shows the acoustic characteristics when the acoustic equalizer 4 and the electrical correction circuit in FIG. 5 are combined.

As described above, according to the present embodiment, the acoustic equalizer 4 suppresses the height of the mid-range peak on the acoustic characteristics caused by the characteristic acoustic impedance Zr of the anterior chamber portion 3, so that a simple and inexpensive electricity can be obtained. The correction of the acoustic characteristics can be realized by the circuit.

(Embodiment 2) FIG. 6 shows the structure of an audio reproducing apparatus according to Embodiment 2 of the present invention. 6 is different from that of the first embodiment in that a first acoustic equalizer 12, a second acoustic equalizer 13, and two acoustic equalizers are provided, and the other parts are the same as those of the first embodiment in FIG. The structure is the same as that of the reproducing apparatus, and the parts having the same functions are denoted by the same reference numerals and the description thereof will be omitted. The first and second acoustic equalizers 12, 13 are integrally formed with the upper cabinet 5a, and the openings 12a, 13a are installed facing the front chamber portion 3. In FIG. 7, which is a schematic cross-sectional view showing the structure of the anterior chamber of the sound reproducing device of the second embodiment, the first acoustic equalizer 12 comprises a neck 14 and a cavity 15 to form a Helmholtz resonator. The second acoustic equalizer 13 constitutes a Helmholtz resonator with the neck portion 16 and the cavity portion 17.

FIG. 8 shows an electroacoustic equivalent circuit of the sound reproducing device of the present embodiment. The sound pressure P of the speaker 1, the characteristic acoustic impedance Zr of the antechamber 3, the acoustic resistance and acoustic mass of the neck 14 of the first acoustic equalizer 12 are Rh1 and Mh1, and the acoustic of the cavity 15 of the first acoustic equalizer 12 is Let the capacity be Ch1. The acoustic resistance and acoustic mass of the neck 16 of the second acoustic equalizer 13 are set to Rh2.
And Mh2, and the acoustic capacity of the cavity portion 17 of the second acoustic equalizer 13 is Ch2.

Resonant frequencies Fh1 and Fh of the first acoustic equalizer 12 and the second acoustic equalizer 13, respectively.
2, Qh1 and Qh2 of each Q are

[0026]

[Equation 3]

[0027]

[Equation 4]

[0028]

[Equation 5]

[0029]

[Equation 6]

It is represented by The solid line in FIG. 9A shows the acoustic characteristics of this acoustic reproduction device. The resonance frequencies Fh1 and Fh2 of the first and second acoustic equalizers 12 and 13 formed of Helmholtz resonators are dispersed and set in the frequency band of the middle range of the acoustic characteristics, and the middle range of the mountains approaches flatness. By setting Qh1 and Qh2 in this way, the peaks in the middle range of the acoustic characteristics are absorbed, and the acoustic characteristics shown by the broken line in FIG. 9A are obtained. Here, the resonance frequency and Q of each acoustic equalizer are set by adjusting the shape of each neck and cavity. Further, similar to the first embodiment, the electrical correction circuit shown in FIG. 5 is used to perform the correction as shown in FIG. 9B, and thus a nearly flat acoustic characteristic as shown by the broken line in FIG. 9C can be obtained. .

As described above, according to this embodiment, two acoustic equalizers are used to suppress the height of the mid-range peak on the acoustic characteristics caused by the characteristic acoustic impedance Zr of the anterior chamber portion 3, so that it is simple and inexpensive. Correction of acoustic characteristics can be realized even in an electric circuit.

The use of two acoustic equalizers as in the present embodiment is an effective means when the frequency band of the middle mountain in the acoustic characteristics is relatively wide, and the number of acoustic equalizers is It goes without saying that it is possible to make the peaks in the middle range of the acoustic characteristics flatter by increasing the number.

[0033]

As described above, in the sound reproducing device of the present invention, the opening of the neck is provided so as to face the front chamber formed between the speaker and the acoustic reflector installed on the front surface of the speaker. A sound equalizer composed of a Helmholtz resonator is provided, and the acoustic frequency is adjusted by adjusting the resonance frequency and the value of Q of this acoustic equalizer to a high mountain in the middle range on the acoustic characteristic caused by the characteristic acoustic impedance Zr of the anterior chamber. It is possible to easily correct by an electric circuit by absorbing the high peaks in the upper midrange, and by providing multiple acoustic equalizers and shifting their resonance frequencies from each other, correction over a wide frequency band is also possible. It is possible to realize the correction of the acoustic characteristics in the circuit configuration.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a structure of a sound reproducing device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing the structure of the front chamber part of the same.

[Fig. 3] Similarly, an electroacoustic equivalent circuit diagram of the sound reproducing device.

[Figure 4] Similarly, its acoustic characteristic diagram

FIG. 5 is a similar electrical correction circuit diagram in the first embodiment.

FIG. 6 is an exploded perspective view showing a structure of a sound reproducing device according to a second embodiment of the invention.

FIG. 7 is a schematic sectional view showing the structure of the anterior chamber of the same.

FIG. 8 is an electro-acoustic equivalent circuit diagram of the same sound reproducing device.

[Fig. 9] Similarly, its acoustic characteristic diagram

FIG. 10 is an exploded perspective view showing the structure of a conventional sound reproducing device.

FIG. 11 is a schematic sectional view showing the structure of the anterior chamber of the same.

[Fig. 12] Similarly, its electro-acoustic equivalent circuit diagram

[Fig. 13] Similarly, its acoustic characteristic diagram

[Fig. 14] Similarly, the electrical correction circuit diagram

[Explanation of symbols]

1 Speaker 2 Acoustic Reflector 3 Front Chamber 4 Acoustic Equalizer 5 Upper Cabinet 6 Bottom Cabinet 7 Decorative Cabinet 8 Neck of the Acoustic Equalizer 4 9 Cavity of the Acoustic Equalizer 4 Zr Characteristic Acoustic Impedance Rh of the Acoustic Equalizer 4 Acoustic resistance of the neck 8 Mh Acoustic mass of the neck 8 of the acoustic equalizer 4 Ch Acoustic capacity of the cavity 9 of the acoustic equalizer 4

Claims (2)

(57) [Claims] 1. A speaker for converting an electric signal into acoustic energy, an acoustic reflector installed in front of the speaker for reflecting and transmitting sound emitted from the speaker, and between the speaker and the acoustic reflector. An anterior chamber part configured and an acoustic equalizer composed of a Helmholtz resonator provided with an opening of the neck portion facing the anterior chamber part, and a mountain on the acoustic characteristics generated by the acoustic characteristic impedance of the anterior chamber part. And a resonance frequency characteristic of the acoustic equalizer are made to coincide with each other so as to reduce the peaks on the acoustic characteristic. 2. A plurality of acoustic equalizers composed of Helmholtz resonators are provided, and the resonance frequencies of the respective acoustic equalizers are dispersedly set in the frequency band of the mountain on the acoustic characteristics caused by the acoustic characteristic impedance of the front chamber. The sound reproducing device according to claim 1, wherein the sound reproducing device is configured to reduce a peak in acoustic characteristics.