JP6932029B2 - Horn speakers, speaker units, megaphones, adapters, and broadcasting systems - Google Patents

Description

The present invention, horn speaker, the speaker unit, Megaho down, the adapter is attached to the horn speaker, and a broadcasting system.

As a horn speaker, the technique described in Patent Document 1 and the technique described in Patent Document 2 are known.
The horn speaker includes a driver unit and a horn. The horn is formed to propagate sound forward.

Japanese Unexamined Patent Publication No. 2011-193112 Japanese Unexamined Patent Publication No. 11-308690

The horn speaker is installed so that the sound is transmitted to a predetermined area. Specifically, the horn is directed in a predetermined direction. However, part of the sound emitted from the horn speaker also wraps around to the rear. When the output is high, the sound that wraps around to the rear can be noisy. In addition, when a plurality of horn speakers are installed, the sound coming out of one horn speaker and wrapping around backward may interfere with the sound coming out of another horn speaker and propagating forward, and the sound may become unclear. be. As described above, in the horn speaker, it is desirable that the sound wrapping around to the rear is small.
Therefore, to provide a horn speaker that can reduce sound from flowing backward the loudspeaker unit, Megaho down, the adapter, and a broadcast system.

(1) A horn speaker that solves the above problems includes a driver unit that forms sound, a horn that is attached to the driver unit, and a phase adjustment plate that is arranged on the outer periphery of the open end of the horn, and the phase adjustment. The plate is attached to the horn so that a gap through which sound passes is formed between the open end of the horn and the phase adjusting plate.

According to this configuration, the phase adjusting plate diffracts at the open end of the horn and blocks the progress of the sound wrapping around backward. Further, the sound diffracted at the end of the phase adjusting plate and wraps backward and the sound wrapping backward through the gap between the open end of the horn and the phase adjusting plate are interfered with and attenuated. In this way, the sound that wraps around backward can be reduced.

(2) A horn speaker that solves the above problems includes a driver unit that forms sound and a horn that is attached to the driver unit. The horn has a sound hole through which sound passes, and the sound hole is the sound hole. It is provided on the opening end side of the half position from the opening end of the horn to the driver unit.

According to this configuration, the horn attenuates by interfering with the sound diffracted at the open end of the horn and wrapping backward and the sound passing through the sound hole on the driver unit side of the horn opening end and wrapping backward. Let me. In this way, the sound transmitted to the rear can be reduced.

(3) The speaker unit for solving the above problems includes a plurality of horn speakers arranged in a predetermined pattern, and a pair of phase adjusting plates provided on both sides of the unit composed of the plurality of the horn speakers. The phase adjusting plate is attached to the unit so that a gap through which sound passes is formed between the front side end of the unit and the phase adjusting plate.

According to this configuration, the phase adjusting plate diffracts at the side edge of the front of the unit to block the progress of the sound wrapping around to the rear. Further, the sound diffracted at the edge of the phase adjusting plate and wraps backward and the sound wrapping backward through the gap between the front side end of the unit and the phase adjusting plate are interfered with and attenuated. In this way, the sound that wraps around backward can be reduced.

(4) A megaphone that solves the above problems includes a driver unit that forms sound, a horn that is attached to the driver unit, and a microphone that is attached to the rear of the horn, and the horn is a sound hole through which sound passes. The sound hole is provided on the opening end side of the half position from the opening end of the horn to the driver unit.

According to this configuration, the horn attenuates by interfering with the sound diffracted at the open end of the horn and wrapping backward and the sound passing through the sound hole on the driver unit side of the horn opening end and wrapping backward. Let me. In this way, the sound transmitted to the rear can be reduced. In addition, howling can be suppressed by this damping effect.

(5) The adapter that solves the above problems is an adapter that can be attached to a horn, and the adapter has an opening into which the opening end of the horn is inserted, and is between the opening end of the horn and the adapter. It can be attached to the outer periphery of the open end of the horn so that a gap through which sound passes is formed.

According to this configuration, the adapter diffracts at the end of the horn to block the progression of sound wrapping backwards. Further, the adapter interferes with and attenuates the sound diffracted at the outer end of the adapter and wraps around backwards and the sound wraps around backwards through the gap between the open end of the horn and the adapter. In this way, the sound that wraps around backward can be reduced.

(6) The adapter that solves the above problems is an adapter that can be attached to the horn, and the adapter has an opening through which the open end of the horn enters and a sound hole through which sound passes, and the open end of the horn. It can be attached to the outer circumference of.

According to this configuration, the adapter diffracts at the end of the horn to block the progression of sound wrapping backwards. Further, the adapter interferes with and attenuates the sound diffracted at the outer end of the adapter and wraps around backward and the sound wrapping backward through the sound hole of the adapter. In this way, the sound that wraps around backward can be reduced.

(7) The horn that solves the above problems is a horn of a horn speaker including a driver unit that forms sound and a horn that is attached to the driver unit. The horn has a sound hole through which sound passes. The sound hole is provided on the opening end side of the half position from the opening end of the horn to the driver unit.

According to this configuration, the horn attenuates by interfering with the sound diffracted at the open end of the horn and wrapping backward and the sound passing through the sound hole on the driver unit side of the horn opening end and wrapping backward. Let me. In this way, the sound transmitted to the rear can be reduced.

(8) A broadcasting system that solves the above problems includes the above horn speaker. According to this configuration, it is possible to reduce the wraparound sound behind.

According to the above-mentioned horn speaker, speaker unit, megaphone, horn, adapter, and broadcasting system, it is possible to reduce the sound wrapping around behind.

Sectional drawing of the horn speaker which concerns on 1st Embodiment. The partial front view of the horn speaker which concerns on 1st Embodiment. The schematic diagram which shows the operation of the horn speaker which concerns on 1st Embodiment. Schematic diagram of a broadcasting system installed in a tunnel. The graph which shows the front frequency characteristic about the horn speaker which concerns on 1st Embodiment and the horn speaker of the conventional structure. The graph which shows the frequency characteristic of the back surface about the horn speaker which concerns on 1st Embodiment and the horn speaker of the conventional structure. FIG. 5 is a polar coordinate graph showing directivity characteristics of a horn speaker according to the first embodiment and a horn speaker having a conventional structure in a sound of 2 kHz. The side view of the speaker unit which concerns on 2nd Embodiment. Side view of a horn having other forms of sound holes. Side view of a horn having other forms of sound holes. The front view of the speaker unit which concerns on 3rd Embodiment. The graph which shows the front frequency characteristic about the speaker unit which concerns on 3rd Embodiment and the speaker unit of a conventional structure. The graph which shows the frequency characteristic of the back surface about the speaker unit which concerns on 3rd Embodiment and the speaker unit of a conventional structure. FIG. 5 is a polar coordinate graph showing directivity characteristics of a speaker unit according to a third embodiment and a speaker unit having a conventional structure in a sound of 2 kHz. A side view of the megaphone according to the fourth embodiment. The graph which shows the frequency characteristic of the front of the megaphone which concerns on 4th Embodiment and the megaphone of a conventional structure. The graph which shows the frequency characteristic of the back surface about the megaphone which concerns on 4th Embodiment and the megaphone of the conventional structure. The front view of the adapter which concerns on 5th Embodiment. The front view of the adapter which concerns on 6th Embodiment.

<First Embodiment>
The horn speaker according to the first embodiment will be described with reference to FIGS. 1 to 7.
As shown in FIGS. 1 and 2, the horn speaker 1 includes a driver unit 2 that forms sound, a horn 3 that is attached to the driver unit 2, and a phase adjusting plate 6. The driver unit 2 is composed of a diaphragm having a coil, a magnet, a yoke, and a plate. When a signal is input to the coil, the diaphragm vibrates due to electromagnetic action, and sound is formed. The horn 3 has a folding structure. For example, the horn 3 includes a tubular first reflector 3a, a second reflector 3b through which the first reflector 3a is inserted, and a third reflector 3c through which the second reflector 3b is inserted. The sound path through which sound passes is configured as a passage through which sound passes through the first reflector 3a, the second reflector 3b, and the third reflector 3c in this order. The cross-sectional area of the sound path (the area of the surface perpendicular to the propagation direction) gradually expands toward the open end 4 of the horn 3. The outer shape of the open end 4 of the horn 3 is configured to be, for example, a circle, an ellipse, an oval, or a rectangle.

The phase adjusting plate 6 is attached to the horn 3 so as to surround the open end 4 of the horn 3. The phase adjusting plate 6 is attached to the horn 3 via the support portion 5. The support portion 5 may be a member separate from the horn 3 and the phase adjusting plate 6, or may be provided integrally with any of the horn 3 and the phase adjusting plate 6. Further, the horn 3, the support portion 5, and the phase adjusting plate 6 may be integrally molded.

The phase adjusting plate 6 is attached to the horn 3 at the following angles. That is, in the cross-sectional view of the horn speaker 1, the angle AG between the front surface of the phase adjusting plate 6 and the line Cp parallel to the central axis C of the horn speaker 1 is an extension line of the horn 3 (at the opening end 4 of the horn 3). It is desirable that the angle AH between the tangent line) and the line Cp parallel to the central axis C of the horn speaker 1 is greater than or equal to the angle AH.

A gap S through which sound passes is provided between the open end 4 of the horn 3 and the phase adjusting plate 6. The width length LS1 of the gap S is set to a length at which the sound pressure reducing effect (see later) of the sound propagating backward is exhibited. For example, in the case of the horn speaker 1 of the present embodiment, the width length LS1 of the gap S is preferably 1 mm or more and 10 mm or less. As a result of the experiment, when the width length LS1 of the gap S was less than 1 mm, the sound pressure reducing effect of the sound propagating backward was not sufficiently obtained. It is conceivable that the reason for this is that the sound pressure propagating backward through the gap S is too small to be balanced with the sound pressure propagating backward through the phase adjusting plate 6 and does not cancel the sound. Further, when the width length LS1 of the gap S is 10 mm or more, conversely, the sound pressure propagating backward through the gap S is too large to be balanced with the sound pressure propagating backward around the phase adjusting plate 6. , It is conceivable not to cancel the sound. The "width length LS1 of the gap S" is defined as a length in a direction perpendicular to the central axis C of the horn speaker 1 (hereinafter, "diameter direction").

The width LA of the phase adjusting plate 6 defines the frequency of the sound to be reduced for the sound of each frequency propagating backward. The "width length LA of the phase adjusting plate 6" is defined as the length in the radial direction.
As will be described later, when the half wavelength of the sound matches the width LA of the phase adjusting plate 6, the sound pressure of the sound having a frequency corresponding to that wavelength is reduced behind the horn speaker 1. Based on this effect, the sound pressure of a sound having a desired frequency can be reduced in the rear by adjusting the width LA of the phase adjusting plate 6. Specifically, the longer the width LA of the phase adjusting plate 6, the lower the sound pressure of low-frequency sound can be reduced.

The operation of the horn speaker 1 will be described with reference to FIG.
The sound wave emitted from the driver unit 2 of the horn speaker 1 is propagated forward by the horn 3. On the other hand, according to the Huygens principle, a secondary wave (hereinafter referred to as "secondary sound wave") whose wave source is a point near the gap S spreads around the point near the gap S.

The secondary sound waves whose wave source is a point near the gap S have the same phase. A part of the secondary sound wave whose wave source is a point near the gap S propagates backward through the gap S. Here, this secondary sound wave is referred to as "direct secondary sound wave". The other part of the secondary sound wave whose wave source is a point near the gap S goes around the phase adjusting plate 6 and propagates backward. Here, this secondary sound wave is referred to as a "detour secondary sound wave". The detour secondary sound wave propagates backward behind the direct secondary sound wave. That is, the phase adjusting plate 6 forms a delay of the bypass secondary sound wave with respect to the direct secondary sound wave. If the phase difference between the two at the point where the direct secondary sound wave and the bypass secondary sound wave interfere with each other is equivalent to half a wavelength, the two secondary sound waves interfere with each other and cancel each other out. In this way, the sound pressure of the sound propagating behind the horn speaker 1 is reduced.

In order to effectively cancel the direct secondary sound wave and the bypass secondary sound wave, the width LA of the phase adjusting plate 6 is 1/4 times or more and less than 1.0 times the half wavelength of the sound wave for reduction purpose. It is preferably the length of. For example, in order to reduce the sound of 2 kHz behind the horn speaker 1, the width LA of the phase adjustment plate 6 is 1/4 times or more and less than 1.0 times of 85 mm, which is a half wavelength of 2 kHz, that is, 21 mm. It is preferably more than 85 mm.

The sound of 2 kHz is a sound that is easy for humans to hear even in the audible range. Therefore, in order to reduce the indistinctness caused by the overlap of the sounds from the horn speaker 1, it is preferable to reduce the sound of the horn speaker 1 at around 2 kHz, and a great effect can be expected. Therefore, as described above, the width LA of the phase adjusting plate 6 of the horn speaker 1 is set to 21 mm or more and less than 85 mm so that the reduction of the sound of 2 kHz becomes large behind the horn speaker 1.

The effect of the horn speaker 1 of the present embodiment will be described with reference to FIG. 4 by taking the broadcasting system 10 as an example.
A broadcasting system 10 for disaster prevention is installed in the tunnel 9.
The broadcasting system 10 of the present embodiment includes a plurality of horn speakers 1. In the tunnel 9, the horn speakers 1 are arranged so as to face in the same direction at predetermined intervals. When the broadcasting system 10 generates sound, the sound (sound) propagates in the tunnel 9 in the same direction. Most of the sound of the horn speaker 1 propagates forward, but some sound also wraps around backward. Therefore, the sound (sound) is transmitted from the two horn speakers 1 in the front and rear to the person between the two horn speakers 1. Since a person rarely stands at an equidistant position from the two horn speakers 1, two voices (sounds) having the same content are transmitted to the person with a time lag. Since the two sounds overlap with each other in time, the sound (sound) becomes unclear and it becomes difficult to hear the broadcast contents.

In this respect, as described above, the horn speaker 1 of the present embodiment has a sound pressure of a rotating sound rearward as compared with a horn speaker having a conventional structure (one having no phase adjusting plate 6; the same applies hereinafter). Is small. When two sounds overlap with each other in time, the influence of the sound wrapping around from behind is small, so that the ambiguity caused by the overlap of the two sounds is reduced.

The effect of the horn speaker 1 of the embodiment is exhibited not only in the broadcasting system 10 but also in various usage modes of the horn speaker 1. For example, when a loud speaker is installed in a venue such as a banquet hall or an exhibition hall, the sound behind the hall spreads around the hall, which may become noise. According to the horn speaker 1 of the embodiment, since the sound pressure of the rear wraparound sound is smaller than that of the horn speaker of the conventional structure, it is possible to suppress the sound leaking to the outside of the broadcasting area (for example, around the venue).

Further, in order to prevent the sound from wrapping around behind the horn speaker 1, a soundproof wall may be provided around the horn speaker 1. However, the soundproof wall has a structure that blocks the sound emitted from the horn speaker 1, is large-scale, and has a problem that the installation is expensive. In this respect, the phase adjusting plate 6 reduces the sound of a frequency that is effective for humans, and is not larger than the soundproof wall, so that the installation cost can be suppressed.

The characteristics of the horn speaker 1 according to the present embodiment will be described with reference to FIGS. 5 to 7.
The frequency characteristic graphs of FIGS. 5 and 6 are obtained as follows. In an anechoic chamber, a microphone is installed 4 m away from the opening end 4 of the horn speaker 1 on the front side (or back side), a 1 W test signal is input to the horn speaker 1, and the microphone is used for each frequency. Detect the output. The frequency characteristic graphs shown in the other embodiments are also graphs obtained by the same method (however, the measurement conditions may be different. See each figure).
The frequency characteristics of the horn speaker 1 according to the first embodiment are shown by solid lines. The frequency characteristics of the conventional structure horn speaker are shown by the broken line. The meanings of the solid line and the broken line are the same in the frequency characteristic graphs shown in other embodiments.

The measurement method of the polar coordinate graph of FIG. 7 will be described. The polar graph is obtained as follows. In an anechoic chamber, install a microphone 4 m away from the horn speaker 1, input a 1 W test signal to the horn speaker 1, rotate the horn speaker 1 360 degrees, and detect the output of the microphone at each angle. do. In the polar graph, the outermost line on the radial axis is 100 dB and the innermost line is 50 dB (this point is the same in FIG. 14). Further, in the polar coordinate graph, 0 degree indicates the position directly in front of the horn speaker 1, and 180 degrees indicates the position directly behind the horn speaker 1.
The directivity of the horn speaker 1 according to the first embodiment is shown by a solid line. The directivity of the conventional structure horn speaker is shown by the broken line. The meanings of the solid line and the broken line are the same in the polar coordinate graphs shown in other embodiments.

As shown in FIG. 5, in the front, the frequency characteristics of the horn speaker 1 according to the first embodiment and the frequency characteristics of the horn speaker having the conventional structure are substantially the same.
As shown in FIG. 6, on the back surface, the horn speaker 1 according to the first embodiment has a lower sound pressure at a frequency of 1 kHz or more and 3 kHz as compared with the horn speaker having a conventional structure.
As shown in FIG. 7, in the sound of 2 kHz, the horn speaker 1 according to the first embodiment has a lower sound pressure in the range of 165 degrees or more and 195 degrees as compared with the horn speaker of the conventional structure, and in particular, 180 degrees. 10 dB lower in degree.
As described above, the horn speaker 1 of the present embodiment does not change the frequency characteristic of the front surface, and can reduce the sound pressure of the sound of about 2 kHz behind the horn speaker 1.

Hereinafter, the effect of the horn speaker 1 according to the present embodiment will be described.
(1) The horn speaker 1 includes a phase adjusting plate 6 arranged on the outer periphery of the open end 4 of the horn 3. The phase adjusting plate 6 is attached to the horn 3 so that a gap S through which sound passes is formed between the open end 4 of the horn 3 and the phase adjusting plate 6.
According to this configuration, the phase adjusting plate 6 diffracts at the opening end 4 of the horn 3 and blocks the progress of the sound wrapping around backward. Further, the sound diffracted at the end of the phase adjusting plate 6 and wrapping backward and the sound wrapping backward through the gap S between the opening end 4 of the horn 3 and the phase adjusting plate 6 are interfered with and attenuated. In this way, the sound that wraps around backward can be reduced.

(2) The broadcasting system 10 includes a horn speaker 1. The plurality of horn speakers 1 are arranged in one row or a plurality of rows. The directions of the plurality of horn speakers 1 are aligned in one direction of the arrangement of the horn speakers 1.
The sound pressure of the sound that wraps around behind each horn speaker 1 is smaller than that of the horn speaker having the conventional structure. Where the sound is transmitted directly from the horn speaker 1 and the sound that wraps around to the rear is transmitted from the other horn speaker 1, these sounds overlap and the sound becomes unclear. In this respect, the sound pressure of the sound that wraps around the rear of the horn speaker 1 is smaller than that of the horn speaker of the conventional structure, and the influence of the sound that wraps around behind the horn speaker 1 is small, so that the indistinctness of the sound is reduced. In this way, according to the broadcasting system 10, the clarity of the voice can be improved.

<Second Embodiment>
The horn speaker 11 according to the second embodiment will be described with reference to FIGS. 8 to 10.
The horn speaker 11 of the present embodiment includes a driver unit 12 that forms sound and a horn 13 that is attached to the driver unit 12. Similar to the horn 3 of the first embodiment, it is composed of a plurality of reflectors.

The horn 13 has a sound hole 15 through which sound passes. Specifically, a sound hole 15 through which sound passes is provided in the outermost reflector among the plurality of reflectors.
The number of sound holes 15 is one or more. The sound hole 15 is provided on the opening end 14 side of the half position from the opening end 14 of the horn 13 to the driver unit 12. For example, the plurality of sound holes 15 are provided along a circle centered on the central axis C of the horn 13 (same as the central axis C of the horn speaker 11). Preferably, the width length LS2 of the plurality of sound holes 15 (the length along the outer shape of the horn 13 in the cross section including the central axis C of the horn 13) is equal. The width length LS2 of the sound hole 15 is 1 mm or more and 10 mm or less. This point is the same as the width length LS1 of the gap S of the horn speaker 1 according to the first embodiment.

The length from the opening end 14 of the horn 13 to the sound hole 15 (hereinafter, “set length LB”) can be set in the same manner as the width length LA of the phase adjusting plate 6 of the first embodiment. In order to reduce the sound of 2 kHz behind the horn speaker 11, the set length LB must be 1/4 times or more and less than 1.0 times of 85 mm, which is a half wavelength of 2 kHz, that is, 21 mm or more and less than 85 mm. preferable.

The "length from the opening end 14 of the horn 13 to the sound hole 15 (set length LB)" is a length along the curved surface of the horn 13, and is innumerable from any point of the opening end 14 to the sound hole 15. The length of the shortest route among the routes is shown. Specifically, the "length from the opening end 14 of the horn 13 to the sound hole 15 (set length LB)" is the length from the opening end 14 to the sound hole 15 on the outer line of the horn 13 in the side view. Equal (see Figure 8).

The operation of the horn speaker 11 will be described.
The sound hole 15 of the horn speaker 11 has the same function as the gap S of the horn speaker 1 according to the first embodiment.
Specifically, a part of the secondary sound wave (directly secondary sound wave) whose wave source is a point near the sound hole 15 propagates backward through the sound hole 15. Further, another part of the secondary sound wave (detour secondary sound wave) whose wave source is a point near the sound hole 15 propagates backward around the open end 14 of the horn 13. The detour secondary sound wave propagates backward behind the direct secondary sound wave. If the phase difference between the two at the point where the direct secondary sound wave and the bypass secondary sound wave interfere with each other is equivalent to a half wavelength, the two secondary sound waves interfere with each other and cancel each other out. In this way, the sound pressure of the sound propagating behind the horn speaker 11 is reduced. Specifically, when the set length LB is 21 mm or more and less than 85 mm (that is, when the set length LB is 1/4 times or more and less than 1.0 times of 85 mm, which is a half wavelength of 2 kHz), a sound of 2 kHz. Is effectively reduced behind the horn 13.

FIG. 9 is a side view of a horn 13x having another form of sound hole 15x.
In this form, the sound hole 15x can be configured as a long hole long in the direction along the central axis C of the horn speaker 11 (sound propagation direction). The intervals of the plurality of sound holes 15x are equal.

FIG. 10 is a side view of a horn 13y having another form of sound hole 15y.
In this embodiment, the horn 13y has sound holes 15y arranged in a plurality of rows. For example, the sound holes 15y are arranged in two rows 16 and 17. The two rows 16 and 17 are arranged in the front-rear direction along the central axis C of the horn speaker 11. The sound holes 15y in each row are composed of a plurality of sound holes 15y. The sound holes 15y in each row are provided along a circle centered on the central axis C of the horn 13 (same as the central axis C of the horn speaker 11) at predetermined intervals. Further, the sound holes 15y in each row are provided on the opening end 14 side of the half position from the opening end 14 of the horn 13 to the driver unit 12.

The distance from the sound hole 15y in the back row 17 to the opening end 14 is different from the distance from the sound hole 15y in the front row 16 to the opening end 14. Therefore, the frequency range in which the direct secondary sound wave passing through the sound hole 15y in the back row 17 and the bypass secondary sound wave interfere with each other, and the frequency in which the direct secondary sound wave passing through the sound hole 15y in the front row 16 and the bypass secondary sound wave interfere with each other. It is out of range. As a result, the frequency range in which the sound is canceled by the interference is widened as a whole.

Hereinafter, the effect of the horn speaker 11 according to the present embodiment will be described.
(1) The horn speaker 11 includes a horn 13. The horn 13 has a sound hole 15 through which sound passes. The sound hole 15 is provided on the opening end 14 side of the half position from the opening end 14 of the horn 13 to the driver unit 12.

According to this configuration, the horn 13 passes through the sound diffracted at the opening end 14 of the horn 13 and wraps around backward and the sound hole 15 (15x, 15y) on the driver unit 12 side of the opening end 14 of the horn 13. Then, it interferes with the sound that wraps around to the rear and attenuates it. In this way, according to the horn speaker 11, the sound transmitted to the rear can be reduced.

(2) As shown in FIG. 10, the sound holes 15y provided in the horn 13 can be arranged in a plurality of rows. The plurality of rows 16 and 17 are provided along a circle centered on the central axis C of the horn 13. According to this configuration, the frequency range in which the sound is canceled by interference can be widened.

<Third Embodiment>
The speaker unit according to the third embodiment will be described with reference to FIGS. 11 to 14. The speaker unit 20 is a so-called "horn array speaker", "line array speaker", or the like.

The speaker unit 20 includes a plurality of horn speakers 21 and a pair of phase adjusting plates 24. The plurality of horn speakers 21 are arranged in a predetermined pattern. For example, the plurality of horn speakers 21 are arranged in one column or a plurality of columns (for example, 2 columns × 8 rows) at predetermined intervals. The directions of the horn speakers 21 are all aligned in the same direction. Preferably, the plurality of horn speakers 21 are housed in a box-shaped housing that houses them.

The phase adjusting plate 24 is arranged on both sides of a unit composed of a plurality of horn speakers 21. The phase adjusting plate 24 and the open end of the horn 23 of the horn speaker 21 are arranged at the same position in the direction along the central axis of the horn speaker 21. The phase adjusting plate 24 is arranged near the horn speaker 21 via the support portion 25. The phase adjusting plate 24 is directly attached to the horn speaker 21 or attached to the housing.

The width length LC of the phase adjusting plate 24 is set in the same manner as the width length LA of the phase adjusting plate 6 described in the first embodiment. For example, in order to reduce the sound of 2 kHz behind the horn speaker 1, the width LC of the phase adjusting plate 24 is 1/4 times or more and less than 1.0 times of 85 mm, which is a half wavelength of 2 kHz, that is, 21 mm. It is preferably more than 85 mm.

A gap S is provided between the phase adjusting plate 24 and the unit composed of the plurality of horn speakers 21. Specifically, a gap S through which sound passes is provided between the front member 26 that covers the periphery of the open ends of the plurality of horns 23 and the phase adjusting plate 24.

The width length LS3 of the gap S is configured in the same manner as the gap S described in the first embodiment. Specifically, the width length LS3 of the gap S is set to 1 mm or more and 10 mm or less. Preferably, the width length LS3 of the gap S is 3 mm or more and 7 mm or less.

The characteristics of the speaker unit 20 according to the present embodiment will be described with reference to FIGS. 12 to 14.
The frequency characteristic graphs of FIGS. 12 and 13 were obtained by the same measurement method as the frequency characteristic graphs of FIGS. 5 and 6. The polar coordinate graph of FIG. 14 is obtained by the same measurement method as the polar coordinate graph of FIG.

As shown in FIG. 12, in front, the frequency characteristics of the speaker unit 20 according to the present embodiment and the frequency characteristics of the speaker unit having the conventional structure (without the phase adjusting plate 24; the same applies hereinafter) are substantially different. It doesn't change to.
As shown in FIG. 13, on the back surface, the speaker unit 20 of the present embodiment has a lower sound pressure at a frequency of 1 kHz or more and 3 kHz as compared with the speaker unit of the conventional structure.
As shown in FIG. 14, in the sound of 2 kHz, the speaker unit 20 of the present embodiment has a lower sound pressure in the range of 120 degrees or more and 240 degrees as compared with the speaker unit of the conventional structure, and particularly at 180 degrees. , 8 dB low.
As described above, the speaker unit 20 of the present embodiment does not change the frequency characteristic of the front surface, and can reduce the sound pressure of the sound of about 2 kHz behind the speaker unit 20.

Hereinafter, the effect of the speaker unit 20 according to the present embodiment will be described.
The speaker unit 20 includes a plurality of horn speakers 21 arranged in a predetermined pattern and a pair of phase adjusting plates 24. The pair of phase adjusting plates 24 are provided on both sides of a unit composed of a plurality of horn speakers 21. The pair of phase adjusting plates 24 are attached to the unit. A gap S through which sound passes is formed between the side end on the front surface of the unit and the phase adjusting plate 24.

According to this configuration, the phase adjusting plate 24 diffracts at the side end of the front surface of the unit to block the progress of the sound wrapping around to the rear. Further, the sound diffracted at the end of the phase adjusting plate 24 and wrapping backward and the sound wrapping backward through the gap S between the front side end of the unit and the phase adjusting plate 24 are interfered with and attenuated. In this way, the sound that wraps around backward can be reduced.

<Fourth Embodiment>
The megaphone according to the fourth embodiment will be described with reference to FIGS. 15 to 17.
As shown in FIG. 15, the megaphone 31 includes a driver unit 32 that forms sound, a horn 33 that is attached to the driver unit 32, and a microphone 36 that is attached to the rear of the horn 33. The microphone 36 is attached to the horn 33 integrally or detachably from the horn 33. The driver unit 32 is composed of a diaphragm having a coil, a magnet, a yoke, and a plate. The horn 33 has a folding structure. The horn 33 is composed of a plurality of reflectors like the horn 3 of the first embodiment.
The horn 33 has a sound hole 35 through which sound passes. A sound hole 35 through which sound passes is provided in the outermost reflector among the plurality of reflectors. The configuration of the sound hole 35 conforms to the configuration of the sound hole 35 shown in the second embodiment. Further, the length from the opening end 34 of the horn 33 to the sound hole 35 (hereinafter, “set length LD”) also conforms to the example of the second embodiment.

The operation of the megaphone 31 will be described.
The sound hole 35 of the megaphone 31 has the same function as the sound hole 15 of the horn speaker 11 of the second embodiment.
Specifically, a part of the secondary sound wave (directly secondary sound wave) whose wave source is a point near the sound hole 35 propagates backward through the sound hole 35. Further, another part of the secondary sound wave (detour secondary sound wave) whose wave source is a point near the sound hole 35 propagates backward around the open end 34 of the horn 33. The detour secondary sound wave propagates backward behind the direct secondary sound wave. Then, the secondary sound wave directly and the detour secondary sound wave interfere with each other and cancel each other out. In this way, the sound pressure of the sound propagating behind the megaphone 31 is reduced.

For example, when the set length LD is 21 mm or more and less than 85 mm (that is, when the set length LD is 1/4 times or more and less than 1.0 times of 85 mm, which is a half wavelength of 2 kHz), the sound of 2 kHz is the megaphone 31. Effectively reduces behind. Since the sound around 2 kHz is effectively reduced in the rear, howling is less likely to occur. Since howling is unlikely to occur in this way, the output of the megaphone 31 can be increased as compared with the case where there is no sound hole 35.

The characteristics of the megaphone 31 according to the present embodiment will be described with reference to FIGS. 16 and 17.
The frequency characteristic graphs of FIGS. 16 and 17 were obtained by the same measurement method as the frequency characteristic graphs of FIGS. 5 and 6 (however, the measurement distance on the back surface is different). As shown in FIG. 17, the measurement distance when measuring the frequency characteristic of the back surface of the megaphone 31 is 34 cm.

As shown in FIG. 16, in the front, the frequency characteristics of the megaphone 31 of the present embodiment and the frequency characteristics of the megaphone of the conventional structure (without the sound hole 35; the same applies hereinafter) are substantially the same.
As shown in FIG. 17, on the back surface, the megaphone 31 of the present embodiment has a lower sound pressure at a frequency of 1 kHz or more and 3 kHz as compared with the megaphone of the conventional structure.
As described above, the megaphone 31 of the present embodiment can reduce the sound pressure of the sound of about 2 kHz in the rear without changing the frequency characteristic of the front surface.

Hereinafter, the effect of the megaphone 31 according to the present embodiment will be described.
The megaphone 31 includes a driver unit 32 that forms sound, a horn 33 that is attached to the driver unit 32, and a microphone 36 that is attached to the rear of the horn 33. The horn 33 has a sound hole 35 through which sound passes. The sound hole 35 is provided on the opening end 34 side of the half position from the opening end 34 of the horn 33 to the driver unit 32.

According to this configuration, the horn 33 diffracts at the opening end 34 of the horn 33 and wraps around backward, and passes through the sound hole 35 on the driver unit 32 side of the opening end 34 of the horn 33 and wraps around backward. It interferes with the sound and attenuates it. In this way, the sound transmitted to the rear can be reduced. Moreover, howling can be suppressed by this reduction effect.

<Fifth Embodiment>
The adapter according to the fifth embodiment will be described with reference to FIG.
The adapter 41 according to the fifth embodiment corresponds to the phase adjusting plate 6 of the horn speaker 1 according to the first embodiment. The adapter 41 can be attached to the horn 49. For example, the adapter 41 can be attached to a horn of a conventional structure horn speaker or a horn of a conventional structure megaphone. Preferably, the adapter 41 is configured to be removable from the horn 49.

The width length LE between the inner circumference and the outer circumference of the adapter 41 is set in the same manner as the “width length LA of the phase adjusting plate 6” of the first embodiment. For example, the width LE between the inner circumference and the outer circumference of the adapter 41 is preferably 21 mm or more and less than 85 mm.
The adapter 41 has an opening 42 into which the open end of the horn 49 enters. When the adapter 41 is attached to the outer periphery of the opening end of the horn 49, a gap S through which sound passes is formed between the opening end of the horn 49 and the opening 42 of the adapter 41. In order to form a gap S by attaching the adapter 41 to the horn 49, the adapter 41 is provided with an engaging protrusion 43 that engages with the open end of the horn 49. The engaging projection 43 engages with the opening end of the horn 49 so as to form a gap S between the opening 42 of the adapter 41 and the opening end of the horn 49. The width and length of the gap S are set in the same manner as in the gap S in the first embodiment.

Hereinafter, the effect of the adapter 41 according to the present embodiment will be described.
The adapter 41 can be attached to the horn 49. The adapter 41 has an opening 42 into which the open end of the horn 49 enters. It can be attached to the outer periphery of the open end of the horn 49 so that a gap S through which sound passes is formed between the open end of the horn 49 and the adapter 41.

According to such an adapter 41, the adapter 41 can be attached to a horn speaker having a conventional structure or a megaphone having a conventional structure.
The adapter 41 attached to the horn 49 diffracts at the open end of the horn 49 and blocks the progress of the sound wrapping around backward. Further, the adapter 41 interferes with and attenuates the sound diffracted at the outer end of the adapter 41 and wraps around backward through the gap S between the open end of the horn 49 and the adapter 41. In this way, the sound that wraps around backward can be reduced.

<Sixth Embodiment>
The adapter according to the sixth embodiment will be described with reference to FIG.
The adapter 51 according to the sixth embodiment is a modification of the phase adjusting plate 6 of the horn speaker 1 according to the first embodiment. The adapter 51 can be attached to the horn 59. For example, the adapter 51 is configured to be attachable to a horn of a conventional structure horn speaker or a horn of a conventional structure megaphone.

The adapter 51 has an opening 52 through which the opening end of the horn 59 enters and a sound hole 53 through which sound passes. The inner peripheral portion 54 constituting the opening 52 is configured to be attached in close contact with the horn 59. For example, the inner peripheral portion 54 is made of an elastic body (for example, rubber, elastomer, or resin having elasticity). When the opening 52 of the adapter 51 is fitted into the opening end of the horn 59, the elastic body is elastically deformed and the adapter 51 is fixed to the horn 59.

The sound hole 53 is provided in a portion between the inner circumference and the outer circumference. The sound hole 53 follows a circle centered on the central axis of the horn speaker or megaphone. The width length LS4 of the sound hole 53 is 1 mm or more and 10 mm or less, preferably 3 mm or more and 7 mm or less. The "width length LS4 of the sound hole 53" is defined as the length in the direction (diameter direction) perpendicular to the central axis of the horn 59.

The width length LF between the sound hole 53 of the adapter 51 and the outer circumference is set in the same manner as the “width length LA of the phase adjusting plate 6” of the first embodiment. For example, the width length LF between the inner circumference and the outer circumference of the adapter 51 is preferably 21 mm or more and less than 85 mm.
When the adapter 51 is attached to the outer periphery of the open end of the horn 59, the open end of the horn 59 and the opening 52 of the adapter 51 are in close contact with each other.

Hereinafter, the effect of the adapter 51 according to the present embodiment will be described.
The adapter 51 has an opening 52 through which the open end of the horn 59 enters and a sound hole 53 through which sound passes. Further, the adapter 51 can be attached to the outer periphery of the open end of the horn 59.

According to such an adapter 51, the adapter 51 can be attached to a horn speaker having a conventional structure or a megaphone having a conventional structure.
The adapter 51 attached to the horn 59 diffracts at the open end of the horn 59 and blocks the progress of the sound wrapping around backward. Further, the adapter 51 interferes with and attenuates the sound diffracted at the outer end of the adapter 51 and wraps around backward and the sound wrapping backward through the sound hole 53 of the adapter 51. In this way, the sound that wraps around backward can be reduced.

<Other Embodiments>
Each embodiment is not limited to the above configuration. Hereinafter, modification examples of each embodiment will be described.
-In the first embodiment, the phase adjusting plate 6 may be foldable. For example, the phase adjusting plate 6 is divided into a plurality of divided bodies in the circumferential direction, and each divided body is attached to the horn via a hinge. Each split body is folded behind the horn 3. When each of the divided bodies is expanded and engaged in the circumferential direction, the phase adjusting plate 6 is formed. According to such a foldable phase adjusting plate 6, the accommodating space of the horn speaker 1 is not increased, and the accommodating property (decrease in accommodating property due to the provision of the phase adjusting plate 6) can be reduced.
-The modified examples of the sound holes 15x and 15y shown in the second embodiment (FIGS. 9 and 10) can also be applied to a megaphone.

AG ... Angle, AH ... Angle, C ... Central axis, Cp ... Line, LS1 ... Width length, LS2 ... Width length, LS3 ... Width length, LS4 ... Width length, LA ... Width length, LB ... Set length, LC ... Width Length, LD ... Set length, LE ... Width length, LF ... Width length, S ... Gap, 1 ... Horn speaker, 2 ... Driver unit, 3 ... Horn, 3a ... 1st reflector, 3b ... 2nd reflector, 3c ... No. 3 reflector, 4 ... open end, 5 ... support, 6 ... phase adjustment plate, 9 ... tunnel, 10 ... broadcasting system, 11 ... horn speaker, 12 ... driver unit, 13 ... horn, 13x ... horn, 13y ... horn, 14 ... Open end, 15 ... Sound hole, 15x ... Sound hole, 15y ... Sound hole, 16 ... Front row, 17 ... Back row, 20 ... Speaker unit, 21 ... Horn speaker, 23 ... Horn, 24 ... Phase adjustment plate, 25 ... Support part, 26 ... front member, 31 ... megaphone, 32 ... driver unit, 33 ... horn, 34 ... opening end, 35 ... sound hole, 36 ... microphone, 41 ... adapter, 42 ... opening, 43 ... engaging protrusion, 49 ... horn, 51 ... adapter, 52 ... opening, 53 ... sound hole, 54 ... inner circumference, 59 ... horn.

Claims (7)

A driver unit that forms sound, a horn that is attached to the driver unit, and a phase adjusting plate that is arranged on the outer periphery of the open end of the horn are provided.
The phase adjusting plate is a horn speaker attached to the horn so that a gap through which sound passes is formed between the open end of the horn and the phase adjusting plate. The horn speaker according to claim 1, wherein the phase adjusting plate and the horn are integrally molded. The angle between the line along the front surface of the phase adjusting plate and the line parallel to the central axis of the horn speaker is the extension of the tangent line at the opening end of the horn and the line parallel to the central axis of the horn speaker. The horn speaker according to claim 1 or 2, which is greater than or equal to the angle between. A plurality of horn speakers arranged in a predetermined pattern and a pair of phase adjusting plates provided on both sides of a unit composed of the plurality of horn speakers are provided.
The pair of the phase adjusting plates are speaker units attached to the unit so that a gap through which sound passes is formed between the front side end of the unit and the phase adjusting plate. A megaphone including the horn speaker according to any one of claims 1 to 3 and a microphone connected to the horn speaker. An adapter that can be attached to the horn
The adapter has an opening into which the open end of the horn enters, and is attached to the outer periphery of the open end of the horn so that a gap through which sound passes is formed between the open end of the horn and the adapter. Adapters that are possible. A broadcasting system including the horn speaker according to any one of claims 1 to 3.

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