JPH06261385A - Directive speaker - Google Patents

Abstract

PURPOSE:To obtain the accurate directivity over the wide frequency band even if the directional speaker is used in a small room by arranging a unit comprising a high frequency sound speaker array between speaker units comprising a low frequency sound speaker array. CONSTITUTION:The reproduction frequency band is divided into the low frequency sound area and high frequency sound area. The low frequency sound area is reproduced by a low frequency sound speaker array 5 where plural 1st speaker units 7 with the front and back of diaphragms opened are two- dimensionally arranged at the prescribed intervals on the surface and the high frequency sound area is on the same surface with the speaker array 5 and reproduces sounds by a high frequency sound speaker array 6 comprising plural 2nd speaker units 8 arranged between the 1st speaker units 7 comprising the low frequency sound speaker array 5. Thus, the soundwave irradiated from one speaker array is not disturbed by the other speaker array and if it is used in the normal room, the sharp directivity can be obtained over the wide frequency band.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Directional speakers that can obtain strong sound pressure only at a specific place are effective when different explanations are made at adjacent booths at exhibition halls or when different announcements are made at adjacent platforms at stations. Is. As a means for achieving narrow directivity, a method is known in which a plurality of speaker units are arranged linearly or in a plane shape to form a speaker array.
The configuration will be described below with reference to (FIG. 9) to (FIG. 16).

In FIG. 9, 8 is a speaker unit having a diameter of 4 cm, and 6b is this speaker unit 16.
It is a speaker array consisting of books. Speaker unit 8
Are arranged in a straight line at 5.5 cm intervals, and are attached to closed boxes 9 that are independent of each other.

The directivity of this directional speaker device at each frequency is shown in FIG. The input signals are sent to the speaker units located symmetrically with respect to the center of the directional speaker device from the center to the end, respectively.
00, 0.95, 0.86, 0.74, 0.60, 0.
Sine wave signals of 46, 0.32, and 0.29 V are input in phase. The directivity is represented by a relative sound pressure level on the circumference of 6 m away from the directional speaker device with the front as a reference.

The directivity of such a speaker array is determined by the frequency, the total length of the speaker array, the spacing between the speaker units, and the directivity of each speaker unit. For example, in order to attenuate the sound pressure level in the direction of 60 ° from the front by 15 dB or more, it is necessary to establish the relationship of L ≧ 1.4λ, where L is the total length of the speaker array and λ is the wavelength of the sound wave. In the speaker array of FIG. 9, the frequency at which this relationship holds is 530 Hz or higher. When the frequency becomes lower, the directivity becomes correspondingly looser. For example, as can be seen from (FIG. 10), at 250 Hz, this speaker array is nearly omnidirectional.

On the other hand, when the rear surface of the speaker unit is used in an open state, sharper directivity can be obtained without increasing the length of the speaker array. This is due to the cancellation of sound waves emitted from the front and back of each speaker unit.
This is because the directivity of the speaker unit becomes sharper than in the case where the speaker unit is attached to the closed box. This solves the problem that the directivity becomes loose in the low frequency range, but in the low frequency range, the above-mentioned cancellation results in reduced efficiency and a reduced sound pressure level.

In order to construct a directional speaker device having a sharp directivity over a wide band and a uniform sound pressure level, the following method may be adopted. The reproduction frequency band is divided into two, and the low-pitched sound range with a low directivity is reproduced by the speaker array used with the rear surface of the speaker unit open. In the high sound range with sufficiently directivity, it is sufficient to reproduce the sound in a speaker array in which a speaker unit is attached to a closed box so that the input level to the low sound range is higher than that in the high sound range.

In FIG. 11, the signal output from the signal source 1 is branched into two, and passes through a low pass filter 2 and a high pass filter 3, respectively. The signal that has passed through the low-pass filter 2 is amplified by the amplifier 4 and then input to the bass array speaker array 5b. The signal that has passed through the high-pass filter 3 is amplified by the amplifier 4 and then input to the high-frequency speaker array 6b. The bass speaker array 5b includes eight speaker units 7 each having a diameter of 9.4 cm.
The speaker units 7 are arranged in a straight line at intervals of 11 cm, and the rear surface is open. The treble range speaker array 6b is composed of 16 speaker units 8 having a diameter of 4 cm, and is the same as the treble range speaker array (FIG. 9). The speaker unit 8 is attached to the punching metal 10b, but this does not prevent the emission of sound from the speaker unit.

FIG. 12 shows the directivity of the bass speaker array 5b of this directional speaker device in the same manner as in FIG. Input signals of 1.00, 0.81, 0.52, and 0.26 V are input in the same phase from the center to the ends of the speaker units that are symmetrical with respect to the center. It can be seen from FIG. 12 that the attenuation amount of the sound pressure level in the 60 ° direction is improved by about 6 dB compared with the speaker array of FIG. 9.

In a directional speaker device in which speaker arrays are linearly arranged as shown in FIG. 11, narrow directivity is obtained in a direction parallel to the speaker array, but not in a direction perpendicular to the speaker array. It becomes directional. (Fig. 1
(FIG. 13) shows a diagram of iso-sound pressure lines at 500 Hz and 1 kHz (the intervals of the iso-sound pressure lines are every 3 dB) on a plane at a distance of 1.5 m from the directional speaker device of 1).
The iso-sound pressure line draws a shape close to an elongated ellipse, and in the direction perpendicular to the speaker array, a sound wave having a high sound pressure level reaches a place away from the directional speaker device.

When this directional speaker device is used in a normal room, a sound wave having a high sound pressure level is reflected on a wall surface or a floor surface over a wide range, so that the directional sound field is remarkably deteriorated particularly in a low sound range. Further, even if the room is made to be sound absorbing so as to suppress the disturbance of the sound field, it is necessary to perform sound absorbing processing over a wide range. Therefore, when the directional speaker device is used indoors, the directional speaker device needs to have directivity in all directions in the bass range. Therefore, the speaker array must be arranged two-dimensionally on a plane. This is the directional speaker device (Fig. 14).

In FIG. 14, 8 is a speaker unit having a diameter of 4 cm, and 6c is this speaker unit 25.
It is a speaker array consisting of six speakers. The speaker units 8 are arranged in a grid pattern at intervals of 5.5 cm, and are attached to independent sealed boxes 9. In this directional loudspeaker device, an isosonic line diagram at 500 Hz and 1 kHz when an in-phase sine wave signal having a value shown in (Table 1) is input to a loudspeaker unit located symmetrically with respect to the center ( (FIG. 15) is shown similarly to FIG. 13).
From this, it can be seen that a sharp directivity can be obtained in all directions.

[0013]

[Table 1]

[0014]

However, the above-described conventional directional speaker device has the following problems. As shown in FIG. 14, a directional speaker device in which small-diameter speaker units are arranged on a plane at narrow intervals so as to reproduce the entire band requires not only a very large number of speaker units but also ( Similar to the directional speaker device of FIG. 9), there is a problem that the directivity is loose at low frequencies. for that reason,
As in the directional speaker device of FIG. 11, it is desirable to adopt a method in which the reproduction frequency band is divided into two, and a low directivity range is reproduced with the speaker array used with the rear surface of the speaker unit open. However, when the speaker arrays are two-dimensionally arranged in a plane, there is a spatial limitation in arranging two sets of speaker arrays on the same plane. Also,
As shown in (FIG. 16), when the bass speaker array is provided in front of the treble speaker array, the sound waves emitted from the treble speaker array are scattered by the bass speaker array. However, the problem that the directivity deteriorates occurs.

An object of the present invention is to solve the above problems and to obtain sharp directivity over a wide frequency band even when the directional speaker device is used in a small room.

[0016]

In order to achieve the above-mentioned object, the directional speaker device of the present invention is for a low-pitched sound region composed of a plurality of speaker units which are two-dimensionally arranged at a predetermined interval on the surface. A speaker array and a treble range speaker array including speaker units arranged on the same surface as the bass range speaker array and arranged between the speaker units forming the bass range speaker array.

[0017]

For the directional speaker device used indoors, the reproduction frequency band is divided into two for the reason described above, and the low-frequency range with a loose directivity is reproduced by the speaker array used with the rear surface of the speaker unit open. I want to adopt the method of doing. For the bass range, the speaker array has two speaker units.
Those arranged in a dimension are desirable.

Generally, a speaker array is suitable as a directional sound source because strong radiation appears in directions other than the front at a frequency at which the wavelength λ of the sound wave is shorter than the distance d between the speaker units forming the array. Not. Therefore, the distance d between the speaker units needs to be shorter than the wavelength λ of the upper limit frequency of the band used.

It is necessary that the distance d between the speaker units constituting the low-range speaker array is shorter than λc, where λc is the wavelength of the cutoff frequency fc of the low-pass filter connected to the speaker array. Since the sound wave radiated from the bass speaker array does not affect the directivity of the treble speaker array, it is desirable that the cutoff characteristic of the low-pass filter be as steep as possible. However, in practice, it is not possible to make a filter that does not pass signals at frequencies above the cutoff frequency, so the spacing d between the speaker units must be somewhat shorter than the wavelength λc of the cutoff frequency. For example, when a low-pass filter that attenuates at a rate of 48 dB per octave is used, d ≦ 0.7λc may be satisfied.

From heretofore, when fc = 800 Hz, the distance between the speaker units can be expanded to about 30 cm. Therefore, the high frequency speaker array can be disposed between the low frequency array speaker units. on the other hand,
In the high frequency range, the effect of reflected waves can be easily removed by laying a carpet as a sound absorbing material on the floor surface, so it is not necessary to arrange the speaker units in a perfect two-dimensional array, and the desired service area can be obtained. You can arrange them so that For example, a sufficiently effective directional sound field is formed even with an array in which speaker units are linearly arranged.

Therefore, by arranging the units constituting the high frequency range speaker array between the speaker units constituting the low frequency range speaker array, two sets of speaker arrays can be provided on the same plane. With this configuration, the sound waves emitted from one speaker array are not scattered by the other speaker array, and even when the directional speaker device is used in a normal room, a sharp directivity is obtained over a wide frequency band. Obtainable.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below (FIG. 1) and (FIG. 2). The signal output from the signal source 1 is branched into two, and passes through the low pass filter 2 and the high pass filter 3, respectively. Low pass filter 2
The passed signal is amplified by the amplifier 4 and then input to the bass speaker array 5. The signal passed through the high-pass filter 3 is amplified by the amplifier 4 and then input to the high-frequency speaker array 6. Filter crossover frequency f
c is set to 800 Hz. The bass speaker array 5 includes 16 speaker units 7 each having a diameter of 9.4 cm.
Consists of. The speaker units 7 are arranged in a grid pattern at intervals of 25 cm, and are attached to the punching metal 10 so that the rear surface is open. Punching metal 1
The emission of sound from the speaker unit 7 is not blocked by 0. The high-frequency speaker array 6 is composed of 32 speaker units 8 having a diameter of 4 cm, arranged on a pair of parallel lines at intervals of 8 cm at intervals of 5.5 cm, and attached to independent sealed boxes 9.

In this directional speaker device, the speaker units at positions symmetrical with respect to the center are directed to the speaker array 6 for the high frequency range and to the speaker array 6 for the high frequency range with the values shown in (Table 2). To the speaker units located symmetrically with respect to the center of the sex speaker device, from the center toward the end, respectively, 1.00, 0.95, 0.86, 0.74,
500Hz and 1kHz when in-phase sine wave signals of 0.60, 0.46, 0.32 and 0.29V are input
(FIG. 2) shows the isosonic pressure diagram in FIG.

[0024]

[Table 2]

Comparing this with the sound pressure distribution diagram (FIG. 15) of the conventional directional speaker device (FIG. 14), 500 Hz
Then, the speaker unit 7 of the bass speaker array 5
The open rear surface realizes sharp directivity in all directions.

In the present embodiment, the case has been described where the speaker units constituting the low-range speaker array are arranged on the grid points at intervals of 25 cm, but the intervals of the speaker units and the arrangement method are limited. Not something. For example, even when the speaker units are arranged concentrically, the same effect can be obtained.

Next, a second embodiment of the present invention will be described with reference to (FIG. 3) to (FIG. 5). Source, filter,
The speaker array is the same as in the first embodiment. The low-range speaker array 5 is provided in front of the high-range speaker array 6 so that the two speaker arrays do not overlap when viewed from the front.

Conventionally, the sound wave radiated from the high frequency speaker array is scattered by the low frequency speaker array,
Although there is a problem that the directivity deteriorates, in the case of the present embodiment, the directivity does not deteriorate in the high frequency range. In addition, in the first embodiment, the directivity of the speaker array for low frequency range is (FIG. 4).
, The x-direction and the y-direction are different, and in the y-direction,
There is a problem that the directivity at 400 Hz or higher deteriorates. This is because there is a high-range speaker array in the center in the y direction, and the directivity of the speaker units is different between the inside and the outside. In the present embodiment, the speaker array for the low range is provided in front of the speaker array for the high range, so that the speaker unit inside the speaker array for the low range also has a good sound output as shown in FIG. As a result, since the directivity of the dipole sound source is exhibited, the sharp directivity can be obtained in the y direction as in the x direction.

It is to be noted that, as in the case of the first embodiment, the intervals and the arrangement method of the speaker units forming the low-range speaker array are not limited.

Next, a third embodiment of the present invention will be described with reference to FIG. The signal source, the filter, and the speaker array are the same as those in the first embodiment, and the reflector 11 is attached to the rear of the bass speaker array 5 by 15 cm.

If a reflector is provided at the rear of the speaker unit whose rear surface is open without having a baffle plate, the effect of a mirror image sound source on the reflector causes a 60 ° direction from the front in the low range of 800 Hz or less. The attenuation of the sound pressure level was increased by 3 to 4 dB, and the directivity became sharp.

Even if a reflector is provided behind the bass speaker array of the second embodiment, the same effect as this embodiment can be obtained.

Finally, a fourth embodiment of the present invention will be described together with (FIG. 7) and (FIG. 8). The signal output from the signal source 1 is branched into two, and passes through the low pass filter 2 and the high pass filter 3, respectively. The crossover frequency fc of the filter is set to 800 Hz.
The signal that has passed through the low-pass filter 2 is amplified by the amplifier 4 and then input to the low-frequency range speaker array 5. The signal passed through the high-pass filter 3 is amplified by the amplifier 4,
It is input to the high frequency speaker array 6a. The bass speaker array 5 is composed of 16 speaker units 7 as in the first embodiment, and is attached to the punching metal 10 so that the rear surface thereof is open. The speaker units are arranged in a lattice at intervals of 25 cm, which is shorter than the wavelength of the sound wave having the crossover frequency fc of the filter, that is, 30 cm. The high-frequency speaker array 6 is composed of 46 speaker units 8 having a diameter of 4 cm, arranged in a cross shape along the axis of symmetry of the low-frequency array at 6 cm intervals, and mounted in independent closed boxes 9.

In the speaker unit at the symmetrical position with respect to the center of this directional speaker device, the speaker array 5 for the low frequency range (Table 2) has a speaker array 6a for the high frequency range.
(FIG. 8) shows an iso-sound pressure diagram at 1 kHz when an in-phase sine wave signal having the values shown in (Table 3) is input, as in (FIG. 13).

[0035]

[Table 3]

The directional speaker device shown in FIG. 1 has speaker arrays in the high frequency range arranged in parallel lines.
The directivity in the direction perpendicular to the speaker array is gentle as shown in (FIG. 2). If a certain degree of directivity is required even in the direction perpendicular to the speaker array, the speaker units may be arranged in a cross shape as in this embodiment (FIG. 8).
The desired directivity is realized as follows.

[0037]

As described above, the present invention has two frequency bands.
The bass range is divided and reproduced by a bass range speaker array composed of a plurality of speaker units arranged at predetermined intervals, and the treble range is on the same plane as the bass range speaker array, By reproducing with a speaker array for high frequency range composed of speaker units arranged between the speaker units forming the speaker array for use in a speaker, even if the directional speaker device is used in a normal room, sharp directivity over a wide frequency band is achieved. Is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a sound pressure distribution of the directional speaker shown in FIG. 1;

FIG. 3 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a diagram showing directivity in x and y directions of the directional speaker shown in FIG. 1;

FIG. 5 is a diagram showing the operation of the second embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 8 is a diagram showing sound pressure distribution of the directional speaker shown in FIG. 7;

FIG. 9 is a diagram showing a configuration of a first conventional example.

FIG. 10 is a diagram showing the directivity of the directional speaker shown in FIG. 9;

FIG. 11 is a diagram showing a configuration of a second conventional example.

FIG. 12 is a diagram showing the directivity of the directional speaker shown in FIG. 11;

FIG. 13 is a diagram showing a sound pressure distribution of the directional speaker shown in FIG. 11;

FIG. 14 is a diagram showing a configuration of a third conventional example.

FIG. 15 is a diagram showing a sound pressure distribution of the directional speaker shown in FIG. 14;

FIG. 16 is a diagram showing a configuration of a fourth conventional example.

[Explanation of symbols]

 1 signal source 2 low-pass filter 3 high-pass filter 4 amplifier 5, 5b, 5c (for low frequency range) speaker array 6, 6a, 6b, 6c (for high frequency range) speaker array 7 speaker unit 8 speaker unit 9 closed box 10, 10b, 10c Punching metal 11 Reflector

Claims (5)

[Claims] 1. A reproduction frequency band is divided into a low-pitched sound region and a high-pitched sound region, and in the low-pitched sound region, a plurality of first speaker units whose front and rear portions of a diaphragm are open are arranged on a surface at predetermined intervals. Reproduction is performed by the low-range speaker array arranged in a dimension, and the high-range is on the same plane as the low-range speaker array, and between the first speaker units forming the low-range speaker array. A directional speaker device which reproduces by a speaker array for a high range including a plurality of second speaker units arranged in the above. 2. A reproduction frequency band is divided into a low-pitched sound region and a high-pitched sound region, and the low-pitched sound region has a plurality of first speaker units whose front and rear sides of the diaphragm are open at predetermined intervals on the surface. The low-range speaker array is reproduced in a three-dimensional manner, and the high-range is behind the surface on which the low-range speaker array is arranged, and when viewed from the front, the low-range speaker array is reproduced. A directional speaker device, wherein reproduction is performed by a high-frequency speaker array including a plurality of second speaker units arranged so as not to overlap the first speaker unit that constitutes the speaker unit. 3. The directional speaker device according to claim 1, further comprising a reflector provided behind the speaker array for low sound range. 4. The first speaker unit is arranged on a two-dimensional lattice point, and the distance between the lattice points is 0.7 of the wavelength of the sound wave having the upper limit frequency of the reproduction frequency band of the speaker array for the low range. The directional speaker device according to any one of claims 1 to 3, which is equal to or less than double. 5. The directional speaker device according to claim 4, wherein the second speaker units are arranged in a cross shape along the axis of symmetry of the lattice points where the first speaker units are arranged.