JP2019004306A - Horn speaker, loudspeaker unit, megaphone, horn, adapter, and broadcasting system - Google Patents

Abstract

To provide a horn speaker, loudspeaker unit, megaphone, horn, adapter, and broadcasting system, capable of reducing generation of a backward turn-around sound.SOLUTION: A horn speaker 1 includes: a driver unit 2 forming a sound; a horn 3 installed on the driver unit 2 and a phase adjustment board 6 arranged at an outer periphery of an opening end 4 of the horn 3. The phase adjustment board 6 is installed on the horn 3 so that a sound runs between the opening end 4 of the horn 3 and the phase adjustment board 6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a horn speaker, a speaker unit, a megaphone, a horn, an adapter 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.

JP 2011-193112 A Japanese Patent Laid-Open No. 11-308690

The horn speaker is installed so that sound is transmitted to a predetermined area. Specifically, the horn is directed in a predetermined direction. However, some of the sound coming out of the horn speaker also goes back. When the output is large, the sound that circulates backward can become noise. Also, when multiple horn speakers are installed, there is a risk that the sound coming out from one horn speaker and going back will interfere with the sound coming out from the other horn speaker and propagating forward, making the sound unclear. is there. Thus, in the horn speaker, it is desirable that there is little sound that circulates backward.
Therefore, a horn speaker, a speaker unit, a megaphone, a horn, an adapter, and a broadcasting system that can reduce the sound that wraps around the back are provided.

  (1) A horn speaker that solves the above problem includes a driver unit that forms sound, a horn that is attached to the driver unit, and a phase adjustment plate that is disposed on an outer periphery of an opening 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 opening end of the horn and the phase adjusting plate.

  According to this configuration, the phase adjusting plate blocks the progress of the sound that diffracts at the opening end of the horn and circulates backward. Further, the sound that is diffracted at the end of the phase adjustment plate and circulates backward is interfered with and attenuated by the sound that circulates backward through the gap between the opening end of the horn and the phase adjustment plate. In this way, it is possible to reduce the sound that circulates backward.

  (2) A horn speaker that solves the above problem includes a driver unit that forms sound and a horn that is attached to the driver unit, and the horn has a sound hole that allows sound to pass therethrough, It is provided on the opening end side of a half position from the opening end of the horn to the driver unit.

  According to this configuration, the horn is attenuated by interfering with the sound that diffracts around the opening end of the horn and circulates backward, and the sound that passes through the sound hole on the driver unit side of the opening end of the horn and circulates backward. Let In this way, the sound transmitted backward can be reduced.

  (3) A speaker unit that solves the above problem includes a plurality of horn speakers arranged in a predetermined pattern, and a pair of phase adjustment plates provided on both sides of the unit constituted by the plurality of horn speakers. The phase adjustment plate is attached to the unit such that a gap through which sound passes is formed between a front end of the unit and the phase adjustment plate.

  According to this configuration, the phase adjusting plate blocks the progress of the sound that diffracts at the front end of the unit and wraps around the rear. Furthermore, the sound that diffracts at the end of the phase adjustment plate and circulates backward is interfered with and attenuates the sound that circulates backward through the gap between the front side edge of the unit and the phase adjustment plate. In this way, it is possible to reduce the sound that circulates backward.

  (4) A megaphone that solves the above problem 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 has a sound hole through which sound passes. The sound hole is provided closer to the opening end than a half position from the opening end of the horn to the driver unit.

  According to this configuration, the horn is attenuated by interfering with the sound that diffracts around the opening end of the horn and circulates backward, and the sound that passes through the sound hole on the driver unit side of the opening end of the horn and circulates backward. Let In this way, the sound transmitted backward can be reduced. Moreover, howling can be suppressed by this attenuation effect.

  (5) The adapter that solves the above-mentioned problem 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 opening end of the horn so that a gap through which sound passes is formed.

  According to this configuration, the adapter blocks the progress of the sound that is diffracted at the opening end of the horn and circulates backward. Further, the adapter causes the sound diffracted at the outer end of the adapter to circulate backward and the sound circulated backward through the gap between the opening end of the horn and the adapter to interfere and attenuate. In this way, it is possible to reduce the sound that circulates backward.

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

  According to this configuration, the adapter blocks the progress of the sound that is diffracted at the opening end of the horn and circulates backward. Further, the adapter attenuates the sound that diffracts at the outer end of the adapter and circulates backward and the sound that circulates backward through the sound hole of the adapter interfere with each other. In this way, it is possible to reduce the sound that circulates backward.

  (7) A horn that solves the above-described problem is a horn speaker horn that 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, The sound hole is provided closer to the opening end than a half position from the opening end of the horn to the driver unit.

  According to this configuration, the horn attenuates the sound that diffracts around the opening end of the horn and circulates backward from the sound that passes through the sound hole on the driver unit side of the opening end of the horn and circulates backward. Let In this way, the sound transmitted backward can be reduced.

  (8) A broadcasting system that solves the above problem includes the horn speaker. According to this configuration, it is possible to reduce the sound that wraps around in the rear.

  According to the horn speaker, the speaker unit, the megaphone, the horn, the adapter, and the broadcasting system, it is possible to reduce the sound that wraps around the rear.

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 effect | action of the horn speaker which concerns on 1st Embodiment. The schematic diagram of the broadcasting system installed in a tunnel. The graph which shows the frequency characteristic of a front about the horn speaker which concerns on 1st Embodiment, and the horn speaker of a conventional structure. The graph which shows the frequency characteristic of a back surface about the horn speaker which concerns on 1st Embodiment, and the horn speaker of a conventional structure. The polar coordinate graph which shows the directional characteristic in the sound of 2 kHz about the horn speaker which concerns on 1st Embodiment, and the horn speaker of a conventional structure. The side view of the speaker unit which concerns on 2nd Embodiment. The side view of a horn which has a sound hole of other forms. The side view of a horn which has a sound hole of other forms. The front view of the speaker unit which concerns on 3rd Embodiment. The graph which shows the frequency characteristic of a front about the speaker unit which concerns on 3rd Embodiment, and the speaker unit of conventional structure. The graph which shows the frequency characteristic of a back surface about the speaker unit which concerns on 3rd Embodiment, and the speaker unit of conventional structure. The polar coordinate graph which shows the directional characteristic in the sound of 2 kHz about the speaker unit which concerns on 3rd Embodiment, and the speaker unit of conventional structure. The side view of the megaphone concerning 4th Embodiment. The graph which shows the frequency characteristic of a front about the megaphone which concerns on 4th Embodiment, and the megaphone of a conventional structure. The graph which shows the frequency characteristic of a back surface about the megaphone which concerns on 4th Embodiment, and the megaphone of a 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>
With reference to FIGS. 1-7, the horn speaker which concerns on 1st Embodiment is demonstrated.
As shown in FIGS. 1 and 2, the horn speaker 1 includes a driver unit 2 that forms sound, a horn 3 attached to the driver unit 2, and a phase adjustment plate 6. The driver unit 2 includes 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 a sound is formed. The horn 3 has a folded structure. For example, the horn 3 includes a cylindrical 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 the sound passes is configured as a passage through which the sound passes in this order through the first reflector 3a, the second reflector 3b, and the third reflector 3c. The cross-sectional area of the sound path (the area of the surface perpendicular to the propagation direction) gradually increases toward the opening 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 ellipse, or a rectangle.

  The phase adjustment plate 6 is attached to the horn 3 so as to surround the opening end 4 of the horn 3. The phase adjustment plate 6 is attached to the horn 3 via the support portion 5. The support 5 may be a separate member from the horn 3 and the phase adjustment plate 6, or may be provided integrally with either the horn 3 or the phase adjustment plate 6. Moreover, the horn 3, the support part 5, and the phase adjustment plate 6 may be integrally molded.

  The phase adjusting plate 6 is attached to the horn 3 at the following angle. That is, in a cross-sectional view of the horn speaker 1, the angle AG between the front surface of the phase adjusting plate 6 and a 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). The angle AH between the tangent line) and the line Cp parallel to the central axis C of the horn speaker 1 is preferably greater than or equal to.

  A gap S through which sound passes is provided between the opening end 4 of the horn 3 and the phase adjustment plate 6. The width LS1 of the gap S is set to a length at which an effect of reducing the sound pressure of the sound propagating backward (see below) appears. 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, if the width LS1 of the gap S is less than 1 mm, the effect of reducing the sound pressure of the sound propagating backward cannot be obtained sufficiently. A possible reason for this is that the sound pressure propagating backward through the gap S is too small and does not balance with the sound pressure propagating backward around the phase adjusting plate 6 and does not cancel the sound. On the other hand, when the width length LS1 of the gap S is 10 mm or more, the sound pressure propagating backward through the gap S is too large and does not balance with the sound pressure propagating backward around the phase adjustment plate 6. It is possible 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 “radial direction”).

The width LA of the phase adjusting plate 6 defines the frequency of the sound to be reduced with respect to the sound of each frequency propagating backward. “Width LA of phase adjusting plate 6” is defined as a length in the radial direction.
As will be described later, when the half wavelength of the sound coincides with the width length LA of the phase adjusting plate 6, the sound pressure of the sound having a frequency corresponding to the wavelength is reduced behind the horn speaker 1. Based on this effect, by adjusting the width LA of the phase adjusting plate 6, the sound pressure of the sound having a desired frequency can be reduced in the rear. Specifically, the sound pressure of low frequency sound can be reduced as the width length LA of the phase adjusting plate 6 is increased.

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

  The secondary sound waves having a wave source near the gap S have the same phase. A part of the secondary sound wave having a wave source 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 having a wave source near the gap S travels 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 later than the direct sound wave. That is, the phase adjustment plate 6 forms a delay of the detour secondary sound wave directly with respect to the secondary sound wave. If the phase difference between the direct secondary sound wave and the detour secondary sound wave is equivalent to a half wavelength, the two secondary sound waves interfere with each other and cancel each other. In this way, the sound pressure of the sound propagating behind the horn speaker 1 is reduced.

  In order to effectively cause the canceling action between the direct secondary sound and the bypass secondary sound, the width LA of the phase adjusting plate 6 is not less than ¼ times and less than 1.0 times the half wavelength of the sound wave to be reduced. It is preferable that it is 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 adjusting plate 6 is not less than 1/4 times and less than 1.0 times of 85 mm which is a half wavelength of 2 kHz, that is, 21 mm. It is preferable that it is less than 85 mm.

  The sound of 2 kHz is a sound that is easy for humans to hear in the audible range. Therefore, in order to reduce the ambiguity due to the overlap of sound from the horn speaker 1, it is preferable to reduce the sound of the horn speaker 1 around 2 kHz, and a great effect can be expected. For this reason, the width length LA of the phase adjustment plate 6 of the horn speaker 1 is set to 21 mm or more and less than 85 mm as described above so that the reduction of the sound of 2 kHz is increased behind the horn speaker 1.

With reference to FIG. 4, the effect of the horn speaker 1 of this embodiment is demonstrated by making the broadcast system 10 into an example.
A broadcast system 10 for disaster prevention is installed in the tunnel 9.
The broadcast system 10 of this embodiment includes a plurality of horn speakers 1. In the tunnel 9, the horn speakers 1 are arranged at predetermined intervals so as to face the same direction. When the broadcasting system 10 generates sound, the sound (sound) propagates in the same direction in the tunnel 9. Most of the sound of the horn speaker 1 propagates forward, but part of the sound also circulates backward. For this reason, the sound (sound) is transmitted to the person between the two horn speakers 1 from the two front and rear horn speakers 1. Since a person hardly stands at an equal distance from the two horn speakers 1, two sounds (sounds) having the same contents are transmitted to the person with a time shift. Since the two sounds overlap with time shift, the sound (sound) becomes unclear and the broadcast content becomes difficult to hear.

  In this respect, as described above, the horn speaker 1 of the present embodiment has a sound pressure of the rotating sound behind the horn speaker having a conventional structure (the one having no phase adjusting plate 6; the same shall apply hereinafter). Is small. In the case where two voices overlap with each other with a time shift, the influence of the sound that wraps around from the rear is small, so that the ambiguity caused by the overlap of the two voices 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 it may spread around the venue, which may be a noise. According to the horn speaker 1 of the embodiment, since the sound pressure of the wraparound sound behind the horn speaker having the conventional structure is small, it is possible to suppress the sound leaking outside the broadcast area (for example, around the venue).

  In addition, in order to suppress the sound from flowing around 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 installation is expensive. In this respect, the phase adjusting plate 6 is for reducing the sound having a frequency effective for humans and is not much larger than the soundproof wall, so that the installation cost can be suppressed.

The characteristics of the horn speaker 1 according to this embodiment will be described with reference to FIGS.
The frequency characteristic graphs of FIGS. 5 and 6 are obtained as follows. In the anechoic chamber, a microphone is installed at a position 4 m away from the opening end 4 of the horn speaker 1 on the front side (or on the back side), and a 1 W test signal is input to the horn speaker 1. Detect output. Note that 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 characteristic of the horn speaker 1 according to the first embodiment is indicated by a solid line. The frequency characteristics of a conventional horn speaker are indicated by a broken line. In addition, the meaning of a solid line and a broken line is the same also in the frequency characteristic graph shown by other embodiment.

A measurement method of the polar coordinate graph of FIG. 7 will be described. The polar graph is obtained as follows. In the anechoic chamber, a microphone is installed at a distance of 4 m from the horn speaker 1, a 1 W test signal is input to the horn speaker 1, the horn speaker 1 is rotated 360 degrees, and the output of the microphone is detected at each angle. To do. In the polar graph, the outermost line on the radial axis is 100 dB, and the innermost line indicates 50 dB (this is the same in FIG. 14). In the polar coordinate graph, 0 degree indicates a position directly in front of the horn speaker 1, and 180 degrees indicates a position immediately behind the horn speaker 1.
Moreover, the directivity of the horn speaker 1 according to the first embodiment is indicated by a solid line. The directivity characteristics of a conventional horn speaker are indicated by a broken line. In addition, the meaning of a solid line and a broken line is the same also in the polar coordinate graph shown by other embodiment.

As shown in FIG. 5, at 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 not substantially changed.
As shown in FIG. 6, on the back side, the horn speaker 1 according to the first embodiment has a low sound pressure at a frequency of 1 kHz or more and 3 kHz as compared with a 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 low sound pressure in the range of 165 degrees or more and 195 degrees compared to the horn speaker having the conventional structure, and in particular, 180 degrees. 10 dB lower in degrees.
Thus, the horn speaker 1 of this embodiment can reduce the sound pressure of the sound around 2 kHz in the rear without changing the front frequency characteristics.

Hereinafter, effects of the horn speaker 1 according to the present embodiment will be described.
(1) The horn speaker 1 includes a phase adjustment plate 6 disposed on the outer periphery of the opening end 4 of the horn 3. The phase adjustment plate 6 is attached to the horn 3 such that a gap S through which sound passes is formed between the opening end 4 of the horn 3 and the phase adjustment plate 6.
According to this configuration, the phase adjusting plate 6 blocks the progress of the sound that diffracts around the opening end 4 of the horn 3 and circulates backward. Furthermore, the sound that is diffracted at the end of the phase adjustment plate 6 and circulates backward is interfered with and attenuated by the sound that circulates backward through the gap S between the opening end 4 of the horn 3 and the phase adjustment plate 6. In this way, it is possible to reduce the sound that circulates backward.

(2) The broadcast system 10 includes the horn speaker 1. The plurality of horn speakers 1 are arranged in one or a plurality of rows. The directions of the plurality of horn speakers 1 are aligned in one direction of the horn speakers 1.
The sound pressure of the sound that circulates behind each horn speaker 1 is smaller than that of a conventional horn speaker. Where the sound is transmitted directly from the horn speaker 1 and the sound that travels backward from the other horn speaker 1 is transmitted, these sounds overlap and the sound becomes unclear. In this respect, the sound pressure of the sound that circulates behind the horn speaker 1 is smaller than that of the horn speaker having the conventional structure, and the influence of the sound that circulates backward in the sound overlap is small, so that the ambiguity of the sound is reduced. Thus, according to the broadcast 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.
The horn speaker 11 of this embodiment includes a driver unit 12 that forms sound and a horn 13 that is attached to the driver unit 12. Like the horn 3 of the first embodiment, the horn 3 includes 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 closer to the opening end 14 than a 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 (the same as the central axis C of the horn speaker 11). Preferably, the widths 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) are equal. The width LS2 of the sound hole 15 is 1 mm or more and 10 mm or less. This 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 adjustment plate 6 of the first embodiment. In order to reduce the sound of 2 kHz behind the horn speaker 11, the set length LB should be not less than 1/4 times and less than 1.0 times 85 mm which is a half wavelength of 2 kHz, that is, not less than 21 mm 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. Indicates the length of the shortest path among the paths. 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 outline of the horn 13 in a side view. Equal (see FIG. 8).

The operation of the horn speaker 11 will be described.
The sound hole 15 of the horn speaker 11 has the same action as the gap S of the horn speaker 1 according to the first embodiment.
Specifically, a part of the secondary sound wave (direct secondary sound wave) having a point near the sound hole 15 as a wave source propagates backward through the sound hole 15. Further, another part of the secondary sound wave having a point near the sound hole 15 (a detoured secondary sound wave) propagates backward around the opening end 14 of the horn 13. The detour secondary sound wave propagates backward later than the direct sound wave. If the phase difference between the direct secondary sound wave and the detour secondary sound wave is equivalent to a half wavelength, the two secondary sound waves interfere with each other and cancel each other. In this way, the sound pressure of the sound propagating behind the horn speaker 11 is reduced. Specifically, when the set length LB is not less than 21 mm and less than 85 mm (that is, when the set length LB is not less than 1/4 times and less than 1.0 times 85 mm which is a half wavelength of 2 kHz), the 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 embodiment, the sound hole 15x can be configured as a long hole that is long in the direction along the central axis C of the horn speaker 11 (sound propagation direction). The intervals between the plurality of sound holes 15x are equal.

FIG. 10 is a side view of a horn 13y having a sound hole 15y of another form.
In this embodiment, the horn 13y has sound holes 15y arranged in a plurality of rows. For example, the sound holes 15 y are arranged in two rows 16 and 17. The two rows 16 and 17 are arranged forward and backward in the direction along the central axis C of the horn speaker 11. The sound holes 15y in each row are constituted by 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 a predetermined interval. 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 rear 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 and the bypass secondary sound wave passing through the sound hole 15y in the rear row 17 interfere with each other, and the frequency in which the direct secondary sound wave and the bypass secondary sound wave passing through the sound hole 15y in the front row 16 interfere with each other. Out of range. As a result, as a whole, the frequency range in which the sound is canceled by the interference is widened.

Hereinafter, effects 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 closer to the opening end 14 than a 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 hole 15 (15x, 15y) located on the driver unit 12 side of the opening end 14 of the horn 13 and the sound that diffracts around the opening end 14 of the horn 13 and moves backward. Then, it is attenuated by interfering with the sound that circulates backward. Thus, according to the horn speaker 11, the sound transmitted to the back 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, it is possible to widen the frequency range in which sound is canceled by interference.

<Third Embodiment>
A speaker unit according to a third embodiment will be described with reference to FIGS. 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 adjustment 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 or a plurality of columns (for example, 2 columns × 8 rows) at a predetermined interval. All the horn speakers 21 are aligned in the same direction. Preferably, the plurality of horn speakers 21 are housed in a box-shaped housing that houses them.

  The phase adjustment plates 24 are respectively disposed on both sides of a unit constituted by a plurality of horn speakers 21. The phase adjustment plate 24 and the opening 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 adjustment plate 24 is disposed 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 LC of the phase adjusting plate 24 is set in the same manner as the width 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 not less than 1/4 times and less than 1.0 times of 85 mm which is a half wavelength of 2 kHz, that is, 21 mm. It is preferable that it is less than 85 mm.

  A gap S is provided between the phase adjustment plate 24 and a unit constituted by a 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 adjustment 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 S LS3 of the gap S is 1 mm or more and 10 mm or less. Preferably, the width S LS3 of the gap S is 3 mm or more and 7 mm or less.

The characteristics of the speaker unit 20 according to this embodiment will be described with reference to FIGS.
The frequency characteristic graphs of FIGS. 12 and 13 are 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 the front, the frequency characteristics of the speaker unit 20 according to the present embodiment and the frequency characteristics of a speaker unit having a conventional structure (without the phase adjustment plate 24; the same applies hereinafter) are substantially the same. It will not change.
As shown in FIG. 13, on the back side, the speaker unit 20 of the present embodiment has a low 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 low sound pressure in the range of 120 degrees or more and 240 degrees compared to the speaker unit of the conventional structure, and particularly at 180 degrees. , About 8 dB lower.
Thus, the speaker unit 20 of the present embodiment can reduce the sound pressure of the sound around 2 kHz in the rear without changing the front frequency characteristics.

Hereinafter, effects 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 constituted by 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 front side edge of the unit and the phase adjustment plate 24.

  According to this configuration, the phase adjusting plate 24 blocks the progress of the sound that diffracts around the front side edge of the unit and moves backward. Further, the sound diffracted at the end of the phase adjusting plate 24 and wrapping around backwards and the sound wrapping around through the gap S between the front side end of the unit and the phase adjusting plate 24 are interfered and attenuated. In this way, it is possible to reduce the sound that circulates backward.

<Fourth embodiment>
A megaphone according to the fourth embodiment will be described with reference to FIGS.
As shown in FIG. 15, the megaphone 31 includes a driver unit 32 that forms sound, a horn 33 attached to the driver unit 32, and a microphone 36 attached to the rear of the horn 33. The microphone 36 is attached to the horn 33 so as to be integral with or separated from the horn 33. The driver unit 32 includes a diaphragm having a coil, a magnet, a yoke, and a plate. The horn 33 has a folded structure. The horn 33 is composed of a plurality of reflectors as in 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 of 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 action as the sound hole 15 of the horn speaker 11 of the second embodiment.
Specifically, a part of the secondary sound wave (direct secondary sound wave) having a point near the sound hole 35 as a wave source propagates backward through the sound hole 35. Further, another part of the secondary sound wave having a point near the sound hole 35 (the detour secondary sound wave) propagates backward around the opening end 34 of the horn 33. The detour secondary sound wave propagates backward later than the direct sound wave. Then, the direct secondary sound wave and the detour secondary sound wave interfere with each other and cancel each other. In this way, the sound pressure of the sound propagating behind the megaphone 31 is reduced.

  For example, when the set length LD is not less than 21 mm and less than 85 mm (that is, when the set length LD is not less than 1/4 times and less than 1.0 times 85 mm, which is a half wavelength of 2 kHz), the sound of 2 kHz is the megaphone 31. Effectively reduce behind. Since sound around 2 kHz is effectively reduced behind, howling is less likely to occur. Since howling hardly occurs as described above, the output of the megaphone 31 can be increased as compared with the case where the sound hole 35 is not provided.

The characteristics of the megaphone 31 according to this embodiment will be described with reference to FIGS. 16 and 17.
The frequency characteristic graphs of FIGS. 16 and 17 are 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, on the front side, the frequency characteristics of the megaphone 31 of the present embodiment and the frequency characteristics of the megaphone having the conventional structure (without the sound hole 35; the same applies hereinafter) are not substantially different.
As shown in FIG. 17, on the back side, the megaphone 31 of this embodiment has a low sound pressure at a frequency of 1 kHz or more and 3 kHz as compared with a megaphone having a conventional structure.
Thus, the megaphone 31 of the present embodiment can reduce the sound pressure of the sound around 2 kHz behind without changing the front frequency characteristics.

Hereinafter, effects 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 attached to the driver unit 32, and a microphone 36 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 closer to the opening end 34 than a 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. Attenuate by interfering with sound. In this way, the sound transmitted backward 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 adjustment 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 horn speaker having a conventional structure or a horn of a megaphone having a conventional structure. Preferably, the adapter 41 is configured to be detachable from the horn 49.

The width LE between the inner periphery and the outer periphery of the adapter 41 is set in the same manner as the “width length LA of the phase adjusting plate 6” in the first embodiment. For example, the width LE between the inner periphery and the outer periphery 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 opening 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 the 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 protrusion 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 of the gap S is set similarly to the gap S in the first embodiment.

Hereinafter, effects 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 opening end of the horn 49 enters. It can be attached to the outer periphery of the opening end of the horn 49 so that a gap S through which sound passes is formed between the opening end of the horn 49 and the adapter 41.

According to such an adapter 41, the adapter 41 can be attached to a conventional horn speaker or a conventional megaphone.
The adapter 41 attached to the horn 49 blocks the progress of the sound that diffracts around the opening end of the horn 49 and circulates backward. Furthermore, the adapter 41 attenuates the sound that diffracts around the outer end of the adapter 41 and circulates backward and the sound that circulates backward through the gap S between the opening end of the horn 49 and the adapter 41 by interfering with each other. In this way, it is possible to reduce the sound that circulates backward.

<Sixth Embodiment>
The adapter according to the sixth embodiment will be described with reference to FIG.
An adapter 51 according to the sixth embodiment is a modification of the phase adjustment 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 horn speaker having a conventional structure or a horn of a megaphone having a conventional structure.

  The adapter 51 has an opening 52 into 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 to the horn 59 in close contact. For example, the inner peripheral portion 54 is configured by 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 periphery and the outer periphery. The sound hole 53 is along a circle centered on the central axis of the horn speaker or megaphone. The width 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 a length in a direction (radial direction) perpendicular to the central axis of the horn 59.

The width length LF between the sound hole 53 and the outer periphery of the adapter 51 is set in the same manner as the “width length LA of the phase adjusting plate 6” in the first embodiment. For example, the width LF between the inner periphery and the outer periphery 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 opening end of the horn 59, the opening end of the horn 59 and the opening 52 of the adapter 51 are in close contact with each other.

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

According to such an adapter 51, the adapter 51 can be mounted on a conventional horn speaker or a conventional megaphone.
The adapter 51 attached to the horn 59 blocks the progress of the sound that diffracts around the opening end of the horn 59 and circulates backward. Furthermore, the adapter 51 causes the sound diffracted around the outer end of the adapter 51 to circulate backward and the sound circulated backward through the sound hole 53 of the adapter 51 to interfere and attenuate. In this way, it is possible to reduce the sound that circulates backward.

<Other embodiments>
Each embodiment is not limited to the above configuration. Hereinafter, a modified example of each embodiment will be described.
In the first embodiment, the phase adjustment 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 divided body is folded to the rear side of the horn 3. When each divided body is expanded and engaged in the circumferential direction, the phase adjusting plate 6 is formed. According to such a foldable phase adjustment plate 6, there is no increase in the accommodation space of the horn speaker 1, and a reduction in accommodation property (a reduction in accommodation property due to the provision of the phase adjustment plate 6) can be reduced.
-The modification (FIGS. 9 and 10) of the sound holes 15x and 15y shown in the second embodiment can be applied to a megaphone.

  AG ... Angle, AH ... Angle, C ... Center 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 ... first reflector, 3b ... second reflector, 3c ... first 3 reflector, 4 ... open end, 5 ... support, 6 ... phase adjusting plate, 9 ... tunnel, 10 ... broadcast 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 ... Rear 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 ... Open end, 35 ... Sound hole, 36 ... Microphone, 41 ... Adapter, 42 ... Opening, 43 ... Engaging projection, 49 ... Horn, 51 ... Adapter, 52 ... opening, 53 ... sound hole, 54 ... inner periphery, 59 ... horn.

Claims (8)

A driver unit for forming a sound, a horn attached to the driver unit, and a phase adjusting plate disposed on an outer periphery of an opening end of the horn,
The phase adjustment plate is attached to the horn so that a gap through which sound passes is formed between an opening end of the horn and the phase adjustment plate. A driver unit for forming sound, and a horn attached to the driver unit;
The horn has a sound hole through which sound passes, and the sound hole is provided closer to the opening end than a half position from the opening end of the horn to the driver unit. A plurality of horn speakers arranged in a predetermined pattern, and a pair of phase adjusting plates provided on both sides of a unit constituted by the plurality of horn speakers,
The pair of phase adjustment plates are attached to the unit such that a gap through which sound passes is formed between a front side end of the unit and the phase adjustment plate. A driver unit for forming sound, a horn attached to the driver unit, and a microphone attached to the rear of the horn;
The horn has a sound hole through which sound passes, and the sound hole is provided closer to the opening end than a half position from the opening end of the horn to the driver unit. 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. Possible adapter. An adapter that can be attached to the horn,
The adapter has an opening into which the opening end of the horn enters and a sound hole through which sound passes, and can be attached to the outer periphery of the opening end of the horn. In a horn speaker horn comprising a driver unit that forms sound and a horn attached to the driver unit,
The horn has a sound hole through which sound passes, and the sound hole is provided closer to the opening end than a half position from the opening end of the horn to the driver unit.   A broadcasting system comprising the horn speaker according to claim 1.