JPH09247784A - Speaker device - Google Patents

Abstract

(57) Abstract: To provide a speaker device in which desired directivity can be easily realized. SOLUTION: A pair of speaker units 13 and 23 are
Arranged so that their back surfaces face each other in independent spaces formed inside the enclosure 30, each speaker unit has a predetermined transfer function Hf (jω), Hb (jω).
A signal is supplied from a common signal source through the filters 11 and 21. The transfer function of the filter is electrically controlled according to the desired directivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker device having variable directivity.

[0002]

2. Description of the Related Art Conventionally, there is a speaker device having directivity in one enclosure. In this type of speaker device, basically, the back surface of the enclosure is opened to form an acoustic circuit such as a port (conducting path), and an appropriate amount of sound absorbing material is filled in, so that the required resistance and inertance can be obtained. The desired directivity is realized by adjusting the minutes and.

[0003]

However, in adjusting the resistance component and the inertance component as described above, the dimensions of the port and the amount of the sound absorbing material are set by a complicated acoustic design, and the experiment is repeated. Therefore, there is a problem in that it is necessary to determine the optimum value and the design man-hour becomes large.

Further, there is a problem in that the acoustic circuit such as a relatively long port (conducting path) makes the enclosure large and the internal mechanical structure becomes complicated, resulting in a high manufacturing cost.

Further, there is a problem that the versatility is lacking because the directivity can hardly be changed due to the restriction of the mechanical structure of the enclosure.

In view of the above point, an object of the present invention is to provide a speaker device which can easily change the directional characteristics by electrical processing.

[0007]

In order to solve the above-mentioned problems, a speaker device according to the present invention has a plurality of partitioned spaces inside an enclosure, and a speaker unit is arranged in each of the plurality of spaces. A common audio signal is supplied to each of the speaker units, and the audio signal is supplied to at least one of the speaker units via a filter having a predetermined characteristic.

According to the present invention having the above-described structure, by adjusting the characteristics of the filter, it is possible to easily realize a speaker device having a desired directional characteristic.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a speaker device according to the present invention will be described below with reference to FIGS.

[First Embodiment] FIG. 1 shows the overall construction of a first embodiment of the present invention, and FIGS. 2 and 3 show the construction of the essential parts thereof.

In FIG. 1, an audio signal from an input terminal Tin is commonly supplied to a pair of variable characteristic filters 11 and 21, and an output of one filter 11 is supplied to a speaker unit 13 through an amplifier circuit 12. At the same time, the output of the other filter 21 is supplied to the speaker unit 23 through the amplifier circuit 22.

As shown in FIG. 2, in this embodiment,
The pair of speaker units 13 and 23 are aligned so that their rear surfaces face each other, and the enclosure 3
It is attached to the opposite side surfaces 31 and 32 of 0,
A partition 33 is arranged in the center of the enclosure 30,
Inside the enclosure 30, acoustically independent space 3
4, 35 are formed. As a result, the speaker units 13 and 23 are acoustically independent of each other without their radiation impedances interfering with each other.

Variable characteristic filter 1 of the embodiment of FIG.
1, 21 have a digital configuration as shown in FIG. 3, for example.

That is, in FIG. 3, the digital filter 1
The analog audio signal from the input terminal 101 of 00 is A-
It is converted into a digital audio signal by the D converter 102 and supplied to a digital signal processor (DSP) 103. The DSP 103 filters the digital audio signal from the A / D converter 102 according to a predetermined parameter supplied from a parameter generation circuit 104 including, for example, a ROM, and imparts a required filter characteristic as described below. To do. The output of the DSP 103 is DA
It is converted back into an analog audio signal by the converter 105 and is led to the output terminal 106.

Next, the operating principle of the first embodiment of the present invention will be described with reference to FIGS.

In FIG. 4, the center of the enclosure 30 is the origin, and the center axes of the speaker units 13 and 23 are X.
Set the coordinate axis to be the axis. In this embodiment, the speaker unit 13 on the positive side of the X axis is the front side, and the speaker unit 23 on the negative side of the X axis is the rear side. In addition, the origin of the coordinate axes and the speaker units 13 and 23
It is assumed that the distance from each of the reference planes is L.

For simplicity, both speaker units 13,
If 23 is regarded as an omnidirectional point sound source and spherical waves are radiated from the speaker units 13 and 23, the sound pressure P (jω) at an arbitrary observation point Q (x, y) is It can be obtained as the sum of the sound pressures of the spherical waves from 13, 23.

When the characteristics of the filters 11 and 21 in FIG. 1 are Hf (jω) and Hb (jω), respectively, and the gains of the amplifier circuits 12 and 22 are Gf and Gb, respectively, an arbitrary observation point Q (x , y) of the sound pressure P (jω) is expressed by the following equation 1.

[0019]

[Equation 1] Here, c is the speed of sound.

As shown in FIG. 4, Df and Db are arbitrary observation points Q (x, y) and the speaker units 1
It is the distance from 3, 23 and is expressed as the following Expression 2.

[0021]

[Equation 2] Therefore, in this embodiment, the sound pressures Pf (jω) and Pb (jω) at the front and rear observation points Qf and Qb, which are symmetric with respect to the origin on the X-axis, are expressed by the following formula 3. To be done.

[0022]

(Equation 3) Now, in this embodiment, it is considered to realize an ideal unidirectionality in which the frequency characteristic is flat on the front side and no sound is emitted on the back side. Under this condition, the sound pressures at the front and rear observation points Qf and Qb are expressed as Pf (jω) = 1 (3c) Pb (jω) = 0 (3d), respectively.

For simplicity, the amplifier circuits 12 and 22 of FIG.
Gf = Gb = 1 is obtained by normalizing the gains of the above. In addition, the distance between the origin and each observation point Qf, Qb,
For example, a = 1 is set, and the distance between the origin and the reference planes of the speaker units 13 and 23 is set to L = 0.05, for example. As a result, the sound pressures Pf (jω) and Pb (at the front and rear observation points Qf and Qb, as shown in the above number 3, are obtained.
jω) is given by the following equation 4.

[0024]

(Equation 4) The filter characteristic (transfer function) Hf (jω), H of this equation 4
The coefficient of b (jω) is rewritten as the following Expression 5.

[0025]

(Equation 5) This rewriting and the above-mentioned desired directivity conditional expression (3c),
By (3d), the above number 4 is simplified as follows: 1 = D2 · Hf + D1 · Hb (4c) 0 = D1 · Hf + D2 · Hb (4d)

Therefore, the transfer function Hf (
jω) and Hb (jω) are obtained by solving these two equations, and are expressed by the following equation 6. Note that Hf (j
ω) and Hb (jω) have opposite phases to each other so that it can be easily understood by comparing the first rows.

[0027]

(Equation 6) The filters 11 and 21 of this embodiment have a digital configuration as shown in FIG.
In 4, the calculation result of the calculation routine of the above equation 6 is stored as a parameter of the filter characteristic.

Then, the predetermined parameters read from the ROM 104 are supplied to the DSP 103, and, for example,
At frequencies of 100 Hz and 200 Hz, FIG.
A unidirectional pattern as shown in B is obtained and 500H
Even at frequencies of z and 1 kHz, unidirectionality as shown in FIGS. 6A and 6B can be obtained, and unidirectionality can be realized at each frequency from the low band to the middle and high bands.

This unidirectionality is obtained by the equation (3c),
By appropriately setting the desired directivity condition such as (3d), it is possible to switch between wide and narrow, for example.

Further, when it is desired to realize a "8" -shaped directivity in the Y-axis direction, which is different from the directivity shown in FIGS. 5 and 6, this directivity corresponds to the "8" -shaped directivity. Based on the conditional expressions of the sound pressures at the four observation points on the X and Y axes, the desired filter characteristics Hf (jω) and Hb (j
ω) is calculated, and the calculation result is stored in the ROM as a parameter.
By storing predetermined parameters in the ROM, predetermined parameters can be read from the ROM and supplied to the DSP to realize the desired "8" -shaped directivity.

Other directivities can be dealt with by the same processing. In this embodiment, the frequency characteristic of the filter can be switched by selecting a predetermined parameter, and a desired directivity can be obtained. Can be easily realized.

[Second Embodiment] Next, FIGS. 6 to 10 will be described.
The second embodiment of the present invention will be described with reference to FIG.

In the above-described first embodiment, the filter 1
Although the reference numerals 1 and 21 have a digital configuration, they may be configured as a known parametric equalizer type analog filter 200 as shown in FIG. 7, for example.

This filter 200 is realized by incorporating band-pass filters 202a and 202b to 202n whose center frequency and Q are variable in the negative feedback loops of a plurality of operational amplifier circuits 201a and 201b to 201n connected in parallel. To be done.

Each band filter 202a, 202b-20
2n is configured, for example, as shown in FIG. 8, the center frequency changes in inverse proportion to the resistance value by the interlocking variable resistors R3, R4, and in proportion to the resistance value by the variable resistor R2. Q changes. A bandpass filter output appears at the terminal ToB, and a low-pass filter output appears at the terminal ToL.

By the way, the center frequencies ω and Q of the bandpass filter are as follows: ω = 1 / C1C2R3R4 Q = 1 / 2a = {(R1R2) + R1} / (R1R
2) However, it is represented as C1 = C2 and R3 = R4. In addition, (R1 || R2) shows a parallel resistance.

The characteristic of the parametric equalizer in the vicinity of an arbitrary center frequency is that the gain is increased from the gain to the attenuation as shown in FIG. 9 by the variable resistor in each negative feedback loop of FIG. The phase is controlled to a large extent from the leading edge to the trailing edge.

When the filters 13 and 23 have an analog configuration using the parametric equalizer 200 as described above, one of the filter characteristics Hf (j
ω) has, for example, a characteristic obtained by combining a low-pass filter and a plurality of band-pass filters, as shown in FIG. Further, the other filter characteristic Hb (jω) has the same characteristic.

[Third Embodiment] Next, FIGS. 11 to 1 will be described.
A third embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows the configuration of the third embodiment of the present invention.
It is shown in FIG. In FIG. 11, parts corresponding to those in FIG.

In FIG. 11, the audio signal from the input terminal Tin is commonly supplied to the pair of low-pass filters 11L and 21L, and the output of one low-pass filter 11L is passed through the amplifier circuit 12 to the speaker unit 13. While being supplied, the output of the other low-pass filter 21L is supplied to the amplifier circuit 22.
Through the speaker unit 23.

In the third embodiment, the pair of speaker units 13 and 23 is a pair of enclosures 30.
The enclosures 30F and 30B are attached to F and 30B, respectively, and the rear surfaces of the enclosures 30F and 30B are arranged so as to face each other. They don't match, and they are acoustically independent.

In the above-mentioned embodiment, the filters 13 and 2 are used.
3 has a parametric equalizer type analog configuration, a characteristic obtained by combining a low-pass filter and a plurality of band-pass filters is obtained as shown in FIG. 10 above. In the above form, the transfer functions Hf (jω) and Hb (jω) of the above equation 6 are Hfa (jω) = + 5.2 / [1 + exp] by approximating using the first-order low-pass filters 11L and 21L. {0.00279 jω}] (7f) Hba (jω) = − 4.8 / [1 + exp {0.00309 jω}] (7b).

The transfer function Hfa of one low-pass filter 11L
The gain characteristic of (jω) is as shown in FIG. 12, and the transfer function Hba (jω) of the other low-pass filter 11B also has the same gain characteristic.

In the third embodiment, the phase of the low-pass filter is approximated to the phase without phase advance, so the illustration of the phase characteristic is omitted. A CR filter may be used as the above-mentioned analog low pass filter.

In the third embodiment, by the above-mentioned approximation, as shown in FIGS. 13A and 13B, in a low frequency band where it is difficult to realize unidirectionality, for example, at frequencies of 100 Hz and 200 Hz. In addition, unidirectionality can be realized.

In addition, in the mid-range frequencies to which the above approximation does not apply, for example, at frequencies of 500 Hz and 1 kHz, bidirectionality is obtained as shown in FIGS. 14A and 14B. Due to the wavelength, side lobes are generated due to interference in a high frequency range, resulting in complicated directivity.

On the other hand, in the middle / high range, directivity can be imparted to the speaker unit itself. Therefore, the speaker unit for such middle / high range and the low-range single unit as in this embodiment. By combining with a speaker device having unidirectionality, it is possible to realize a speaker system having directivity over a wide frequency band from a low range to a high range.

In the middle and high frequencies, the present invention can be applied in consideration of the size of the speaker units and the distance between the speaker units.

[Fourth Embodiment] In each of the above-described embodiments, a signal is supplied to a pair of speaker units through a filter and an amplifier circuit, respectively. However, as shown in FIG. The amplifier circuit 12 of No. 1 is directly connected to one speaker unit 13, and the filter 21 is provided between the other speaker unit 23 and the amplifier circuit 12.
It is also possible to interpose c.

Further, as shown in FIG. 16, the pair of speaker units 13 and 23 are driven by the amplifier circuits 12 and 22, respectively, and the filter 21s is provided only on one side of the amplifier circuits, for example, the front stage of the amplifier circuit 22. You may make it interpose.

In any of these cases, by adjusting the characteristics of the filter, it is possible to easily realize the desired directivity as in the above-described embodiments.

In each of the above-mentioned embodiments, when the input signal is a digital signal in the bit stream format, as a low-pass filter for decoding this signal, as described above, the speaker system has directivity. It is also possible to share various filters.

Further, in the embodiment shown in FIG. 1 and the like, the common enclosure is divided into a pair of spaces independent of each other by the partition wall, but a sound absorbing material or a plate with appropriate holes is used as the partition wall. Thus, it is possible to reduce the load on the filter by connecting the pair of speakers with an appropriate acoustic impedance.

The load on the filter can also be reduced by devising the shape of the enclosure so as to block the low-frequency sound coming from the rear speaker unit.

In each of the above-described embodiments, a pair of speaker units is used, but three or more speaker units are used, and each unit is supplied with a signal through an appropriate filter. It is possible to obtain stronger or more complicated directivity.

Alternatively, the voice signal band is divided into a plurality of bands,
By providing a filter and a plurality of speaker units for each divided band, and applying the present invention in a so-called multi-channel drive format, and by spatially combining,
It is also possible to realize a speaker system capable of controlling directivity over a wide frequency band.

[0058]

As described above, according to the present invention, it is possible to easily realize various desired directivities by electrically controlling the transfer characteristics of the filter. In addition, miniaturization is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of a speaker device according to the present invention.

FIG. 2 is a perspective view showing a configuration of a main part of the embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of another main part of the embodiment of the present invention.

FIG. 4 is a plan view for explaining the operation of the present invention.

5 is a plan view showing directional characteristics of the embodiment of FIG. 1. FIG.

FIG. 6 is a plan view showing the directional characteristics of the embodiment of FIG.

FIG. 7 is a connection diagram showing a configuration of a main part of another embodiment of the present invention.

8 is a connection diagram showing a configuration of a main part of the embodiment of FIG.

FIG. 9 is a diagram showing frequency characteristics for explaining the operation of the present invention.

10 is a diagram showing frequency characteristics of a main part of the embodiment of FIG.

FIG. 11 is a block diagram showing a configuration of another embodiment of the present invention.

FIG. 12 is a diagram showing frequency characteristics of main parts of the embodiment of FIG.

13 is a plan view showing the directional characteristics of the embodiment of FIG.

FIG. 14 is a plan view showing the directional characteristics of the embodiment of FIG.

FIG. 15 is a block diagram showing a configuration of another embodiment of the present invention.

FIG. 16 is a block diagram showing the configuration of another embodiment of the present invention.

[Explanation of symbols]

11, 11L ... Filter, 13 ... Speaker unit, 2
1, 21L, 21c, 21s ... Filter, 23 ... Speaker unit, 30, 30B, 30F ... Enclosure,
33 ... Partition wall, 100 ... Digital filter, 103 ... Digital signal processor (DSP), 104 ... Parameter generation circuit (ROM), 200 ... Analog filter (parametric equalizer), 202 ... Bandpass filter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeshi Hara, 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Takayuki Mizuuchi 6-7-35, Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Corporation (72) Inventor Kaoru Gyotoku 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Ikue Akiba 6-735 Kitagawa-Shinagawa, Shinagawa-ku, Tokyo -Inside the corporation

Claims (3)

[Claims] 1. A plurality of spaces partitioned inside the enclosure are formed, a speaker unit is provided in each of the plurality of spaces, and a common audio signal is supplied to each of the speaker units. A speaker device in which the audio signal is supplied to at least one of the speaker units via a filter having a predetermined characteristic. 2. The speaker device according to claim 1, wherein the characteristics of the filter are electrically controllable. 3. The speaker units are arranged in the plurality of spaces so that their rear surfaces face each other.
The speaker device according to claim 1.