JP6975910B2 - Alarm sound acoustic device and acoustic system - Google Patents

Description

The present invention generally relates to an alarm sound acoustic device and an acoustic system, and more particularly to an alarm sound acoustic device that resonates a vibrating body and an acoustic system using the same.

Conventionally, an alarm device provided with a resonance chamber that resonates with a sound wave having a predetermined resonance frequency, an output means capable of outputting a sound wave of an arbitrary frequency, and a frequency changing means for changing the frequency of the sound wave output by the output chamber. It is known (see, for example, Patent Document 1). The frequency changing means obtains the maximum sound pressure by changing the frequency of the sound wave output to the output means within the resonance frequency. The resonance chamber forms a resonance space for resonating the sound wave generated by the piezoelectric diaphragm.

Japanese Unexamined Patent Publication No. 2009-157447

For example, when there are a plurality of alarm sounds and the fundamental frequencies of the alarm sounds are different from each other, the alarm device described in Patent Document 1 improves the sound pressure of the alarm sound having a fundamental frequency different from the predetermined resonance frequency of the resonance means. It is difficult to make it.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an alarm sound acoustic device and an acoustic system capable of improving the sound pressure of a plurality of alarm sounds having different fundamental frequencies.

The alarm sound acoustic device according to one aspect of the present invention includes a plate-shaped vibrating body and a housing. The vibrating body resonates at the resonance frequency Fp. The housing houses the vibrating body and resonates at the resonance frequency Fc due to the vibration of the vibrating body to emit a plurality of alarm sounds. Each of the plurality of alarm sounds is an alarm sound having different fundamental frequencies from each other. The relationship between the highest fundamental frequency f among the fundamental frequencies of the plurality of alarm sounds, the resonance frequency Fp, and the resonance frequency Fc is f ≦ | Fp-Fc |. For each of the plurality of alarm sounds, at least one of the plurality of harmonics of the fundamental frequency is included in the frequency band between the resonance frequency Fp and the resonance frequency Fc.

The acoustic system according to one aspect of the present invention includes the above-mentioned acoustic device for alarm sounds and a generation unit that generates a plurality of electric signals corresponding to the plurality of alarm sounds on a one-to-one basis. The vibrating body is configured to resonate at each frequency of the plurality of electric signals.

The present invention has an advantage that the sound pressure can be improved for a plurality of alarm sounds having different fundamental frequencies.

FIG. 1 is a block diagram of an alarm sound acoustic device according to an embodiment of the present invention. FIG. 2A is an exploded perspective view of a main part of the same alarm sound acoustic device. FIG. 2B is a cross-sectional view of the same alarm sound acoustic device. FIG. 3 is a frequency characteristic graph for explaining changes in the frequency characteristics of the above-mentioned alarm sound acoustic device. FIG. 4A is a frequency characteristic graph showing the relationship between the frequency characteristics of the above-mentioned alarm sound acoustic device, the vibrating body and the resonance frequency, and the resonance frequency of the housing. FIG. 4B is a frequency characteristic graph of the first alarm sound and the second alarm sound emitted by the sound device of the alarm sound of the same as above. FIG. 5A is a frequency characteristic graph showing the frequency characteristics of the alarm sound acoustic device according to the comparative example of one embodiment of the present invention, the relationship between the vibrating body and the resonance frequency, and the resonance frequency of the housing. FIG. 5B is a frequency characteristic graph of the first alarm sound and the second alarm sound emitted by the sound device of the alarm sound of the same as above.

Hereinafter, the alarm sound sound device 1 (hereinafter, also simply referred to as sound device 1) and the sound system 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4B. However, the embodiments described below are merely one of the various embodiments of the present invention. The following embodiments can be variously modified depending on the design and the like as long as the object of the present invention can be achieved. Further, each figure described in the following embodiments is a schematic view, and the ratio of the size and the thickness of each component in FIGS. 2A and 2B does not necessarily reflect the actual dimensional ratio. Not necessarily.

(1) Outline of Acoustic System The acoustic system 100 is, for example, a system that outputs an alarm sound for notifying the occurrence of a fire. The sound system 100 can individually output a plurality of alarm sounds having different fundamental frequencies. The plurality of alarm sounds having different fundamental frequencies are, for example, a first alarm sound generated from the first signal A1 (see FIG. 4B) and a second signal B2 (see FIG. 4B) having a higher fundamental frequency than the first alarm sound. There are two alarm sounds, the second alarm sound generated from. The sound system 100 alternately outputs, for example, a first alarm sound and a second alarm sound for a predetermined time (for example, 1 second).

(2) Configuration of Acoustic System As shown in FIG. 1, the acoustic system 100 includes an acoustic device 1 and a generation unit 2. The acoustic system 100 further includes a drive unit 3.

The generation unit 2 has, for example, a signal generation circuit that outputs an AC voltage of a square wave by a PWM (Pulse Width Modulation) control method. The generation unit 2 can individually generate the first signal A1 and the second signal B2 as electric signals. The first signal A1 is, for example, a signal composed of a rectangular wave AC voltage. The first signal A1 includes a fundamental wave whose frequency is the fundamental frequency fA and a plurality of harmonics whose frequency is an integral multiple of fA. As shown in FIG. 4B, the plurality of harmonics are the second harmonic having a frequency of 2fA, the third harmonic having a frequency of 3fA, the fourth harmonic having a frequency of 4fA, and the fifth harmonic having a frequency of 5fA. It includes harmonics, a sixth harmonic having a frequency of 6 fA, and a seventh harmonic having a frequency of 7 fA.

The second signal B2 is, for example, a signal composed of a rectangular wave AC voltage. The second signal B2 includes a fundamental wave having a fundamental frequency fB having a frequency higher than that of fA, and a plurality of harmonics having a frequency that is an integral multiple of fB. As shown in FIG. 4B, the plurality of harmonics are a second harmonic having a frequency of 2 fB and a third harmonic having a frequency of 3 fB. For example, the generation unit 2 alternately outputs the first signal A1 and the second signal B2 to the drive unit 3 for a predetermined time (for example, 3 seconds).

The drive unit 3 has, for example, a resonance circuit including a coil, a capacitor, and the like. The drive unit 3 amplifies the AC voltage in a specific frequency band by electrically resonating the electric signal in a specific frequency band among the electric signals input from the generation unit 2 with a resonance circuit. The specific frequency band is, for example, a frequency band in which the vibrating body 11 is relatively less likely to vibrate than other frequency bands, and is a frequency band determined by factors such as the shape and material of the vibrating body 11. The drive unit 3 outputs the amplified AC voltage to the vibrating body 11 to vibrate the vibrating body 11.

(3) Configuration of Sound Device for Alarm Sound The sound device 1 has a vibrating body 11 and a housing 12 as shown in FIGS. 1, 2A and 2B.

The vibrating body 11 has, for example, two plate-shaped piezoelectric elements having a bimorph structure and a diaphragm arranged between the piezoelectric elements. The vibrating body 11 is formed in a disk shape, and the two piezoelectric elements expand and contract due to the AC voltage input from the drive unit 3 to vibrate in the thickness direction of the vibrating body 11. The vibrating body 11 mechanically vibrates at the frequency of the AC voltage from the drive unit 3.

The housing 12 has a base portion 13, a lid portion 14, and a mounting frame 16.

The mounting frame 16 is formed in an annular shape and is mounted on the edge portion of the vibrating body 11. The mounting frame 16 attaches the vibrating body 11 to the base portion 13 and the lid portion 14 by being sandwiched between the base portion 13 and the lid portion 14.

As shown in FIG. 2A, the base portion 13 is formed in a bottomed cylindrical shape having substantially the same outer diameter as the mounting frame 16. The base 13 is formed of, for example, a synthetic resin material. As shown in FIG. 2B, an opening is formed in the surface of the base 13 on the side in contact with the mounting frame 16. By attaching the vibrating body 11 to the base 13 via the mounting frame 16 so as to close the opening of the base 13 with the vibrating body 11, the first air chamber 131 is formed between the base 13 and the vibrating body 11. ..

As shown in FIG. 2A, the lid portion 14 is formed in a bottomed cylindrical shape having substantially the same outer diameter as the mounting frame 16. The lid portion 14 is formed of, for example, a synthetic resin material. As shown in FIG. 2B, an opening is formed in the surface of the lid portion 14 on the side in contact with the mounting frame 16. By attaching the vibrating body 11 to the lid portion 14 via the mounting frame 16 so as to close the opening of the lid portion 14 with the vibrating body 11, the second air chamber 141 is provided between the lid portion 14 and the vibrating body 11. It is formed.

The bottom plate 15 of the lid portion 14 is formed with a plurality of through holes 151 that penetrate the bottom plate 15 in the thickness direction. The through hole 151 is provided to radiate the sound generated in the second air chamber 141 to the outside of the housing 12. In other words, the sound radiated to the outside of the housing 12 through the through hole 151 becomes an alarm sound. Note that FIG. 2B shows an example in which the bottom plate 15 is integrally formed with the lid portion 14, but the present invention is not limited to this example, and the bottom plate 15 may be formed separately from the lid portion 14. For example, the lid portion 14 may be formed in a cylindrical shape, and the opening of the lid portion 14 on the side opposite to the side in contact with the mounting frame 16 may be closed by the bottom plate 15.

Here, it is assumed that the distance from the bottom plate 15 to the vibrating body 11 can be changed in the housing 12. The larger the distance from the bottom plate 15 to the vibrating body 11 and the larger the volume of the second air chamber 141, the higher the sound pressure of the frequency on the high frequency side of the predetermined frequency band of the sound radiated from the bottom plate 15 of the housing 12. The level becomes large, and the frequency on the low frequency side of the predetermined frequency band becomes relatively small. On the other hand, as the volume of the second air chamber 141 is made smaller, the sound pressure level of the frequency on the high frequency side in the predetermined frequency band of the sound radiated from the bottom plate 15 of the housing 12 becomes smaller, and the sound pressure level is smaller in the predetermined frequency band. The frequency on the low frequency side becomes relatively large. The sound pressure level represents the magnitude of the sound pressure with respect to the reference sound pressure (for example, 20 × ^{10-6 [Pa]).}

Hereinafter, the frequency band between the frequency Fg and the frequency Fh in FIG. 3 will be described as a predetermined frequency band. In FIG. 3, the frequency characteristic of the housing 12 is shown by a broken line, and the frequency characteristic when the volume of the second air chamber 141 is smaller than that of the housing 12 is shown by a solid line. The smaller the volume of the second air chamber 141 of the housing 12, the higher the sound pressure level of the frequency on the low frequency side in the frequency band between the frequency Fg and the frequency Fh. Therefore, the average sound pressure level of the entire frequency band between the frequency Fg and the frequency Fh is increased. Therefore, by adjusting the volume of the second air chamber 141, the sound pressure in a predetermined frequency band of the sound radiated from the bottom plate 15 of the housing 12 can be increased.

(4) Frequency Characteristics of Alarm Sound Acoustic Device The relationship (frequency characteristics) between the frequency of the alarm sound of the acoustic device 1 and the sound pressure level will be described with reference to FIGS. 4A and 4B.

The frequency characteristic of the acoustic device 1 is represented by the radiation characteristic 50 as shown in FIG. 4A. The radiation characteristic 50 is a frequency characteristic determined by the resonance characteristic 51 of the vibrating body 11 and the resonance characteristic 52 of the housing 12.

The resonance characteristic 51 is a frequency characteristic in which the frequency at which the vibrating body 11 resonates is represented by the horizontal axis and the sound pressure level for each frequency is represented by the vertical axis. The resonance frequency Fp at which the sound pressure level of the resonance characteristic 51 peaks is determined by, for example, the shape and material of the piezoelectric element and the diaphragm of the vibrating body 11. The graph of the resonance characteristic 51 has a shape in which the sound pressure level at the resonance frequency Fp is the peak, and the sound pressure level drops sharply as the distance from the resonance frequency Fp increases.

The resonance characteristic 52 is a frequency characteristic in which the frequency at which the housing 12 resonates with the vibrating body 11 when the vibrating body 11 vibrates is represented by the horizontal axis, and the sound pressure level for each frequency is represented by the vertical axis. The resonance frequency Fc at which the sound pressure of the resonance characteristic 52 peaks is, for example, a frequency characteristic determined by the volume of the second air chamber 141. The graph of the resonance characteristic 52 has a shape in which the sound pressure level at the resonance frequency Fc has a peak, and the sound pressure level sharply decreases as the distance from the resonance frequency Fc increases. In the acoustic device 1 of the present embodiment, the case where the resonance frequency Fc is lower than the resonance frequency Fp (that is, Fc <Fp) will be described, but not limited to this case, the resonance frequency Fc may be higher than the resonance frequency Fp. ..

The radiation characteristic 50 is a frequency characteristic in which the frequency is represented by the horizontal axis and the sound pressure level obtained by adding the sound pressure level of the resonance characteristic 51 and the sound pressure level of the resonance characteristic 52 is represented by the vertical axis for each frequency. Therefore, in the graph of the radiation characteristic 50, the closer the resonance frequency Fp and the resonance frequency Fc are, the larger the peak value of the sound pressure level becomes. Therefore, the sound pressure level in the frequency band between the resonance frequency Fp and the resonance frequency Fc tends to exceed a predetermined sound pressure level fN (for example, about 60 [dB]). On the other hand, the closer the resonance frequency Fp and the resonance frequency Fc are, the narrower the width of the frequency band exceeding the predetermined sound pressure level fN.

On the other hand, as the resonance frequency Fp and the resonance frequency Fc are separated from each other, the frequency band between the resonance frequency Fp and the resonance frequency Fc becomes wider, but in that frequency band, a frequency band in which the sound pressure level decreases occurs. The width of the frequency band in which the sound pressure level decreases becomes wider as the resonance frequency Fp and the resonance frequency Fc are separated, and the lowest sound pressure level in the frequency band between the resonance frequency Fp and the resonance frequency Fp is the resonance frequency Fp. And the resonance frequency Fc become smaller as they are separated from each other. Therefore, in the frequency band between the resonance frequency Fp and the resonance frequency Fc, a frequency band having a predetermined sound pressure level less than fN is likely to occur.

Here, the relationship between the resonance frequency Fp and the resonance frequency Fc of the acoustic device 1, the sound pressure level of the first alarm sound, and the sound pressure level of the second alarm sound will be described with reference to FIGS. 4A and 4B.

The resonance frequency Fp and the resonance frequency Fc in the acoustic device 1 are set so that the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc is set to be equal to or higher than the frequency fB of the fundamental wave of the second alarm sound. That is, the relationship between the highest fundamental frequency f (here, frequency fB) among the fundamental frequencies f of the plurality of alarm sounds, the resonance frequency Fp, and the resonance frequency Fc is f ≦ | Fp-Fc |. As a result, the frequency band between the resonance frequency Fp and the resonance frequency Fc includes at least one harmonic of the fundamental wave of the second warning sound or a plurality of harmonics of the second signal warning sound. Become.

In FIG. 4B, the third harmonic having a frequency of 3 fB in the second alarm sound is included in the frequency band between the resonance frequency Fp and the resonance frequency Fc. As a result, when the acoustic device 1 outputs the second alarm sound generated from the second signal B2, the sound pressure levels of the fundamental wave and the second harmonic of the second alarm sound are about fN (about 60 [dB]). If, the sound pressure level of the third harmonic becomes larger than fN (for example, about 90 [dB]). Therefore, the sound device 1 can increase the sound pressure of the second alarm sound.

In FIG. 4B, the fifth harmonic to the seventh harmonic of the first alarm sound are included in the frequency band between the resonance frequency Fp and the resonance frequency Fc. As a result, when the sound device 1 outputs the first alarm sound generated from the first signal A1, the sound pressure levels of the fundamental wave and the first to fourth harmonics of the first alarm sound are fN. The sound pressure level of the 5th to 7th harmonics is larger than that of fN (for example, about 90 to 95 [dB]). Therefore, the acoustic device 1 can increase the sound pressure of the first alarm sound.

The sound pressure levels of the fundamental wave and harmonics of the first alarm sound other than the frequency band between the resonance frequency Fp and the resonance frequency Fc in FIG. 4B have been described as fN for convenience, but each of the fundamental wave and the harmonic has been described. The sound pressure level may be fN or less. Similarly, the sound pressure levels of the fundamental wave and harmonics of the second alarm sound other than the frequency band between the resonance frequency Fp and the resonance frequency Fc in FIG. 4B may be fN or less.

The resonance frequency Fp and the resonance frequency Fc of the acoustic device 1 are set so that the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc of the acoustic device 1 is less than the frequency of the second harmonic of the second alarm sound. ing. In other words, the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc is less than twice the frequency fB of the fundamental wave of the second alarm sound. That is, the relationship between the frequency 2f (here, the frequency 2fB) which is twice the fundamental frequency f, the resonance frequency Fp, and the resonance frequency Fc is | Fp-Fc | <2f. As a result, the frequency band between the resonance frequency Fp and the resonance frequency Fc includes only one harmonic of the fundamental wave of the second alarm sound or the plurality of harmonics of the second alarm sound. .. As described above, in the graph of the radiation characteristic 50, as the frequency band between the resonance frequency Fp and the resonance frequency Fc becomes wider, the frequency band in which the sound pressure level becomes less than the predetermined sound pressure level fN is defined. Since it becomes wider, it is difficult to improve the sound pressure of the alarm sound. However, when the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc is less than the value of the frequency 2fB of the second harmonic of the second alarm sound, the acoustic device 1 is the fundamental wave of the second alarm sound or the second alarm sound. It is possible to improve the sound pressure of one of the plurality of harmonics of the alarm sound. In this case, the acoustic device 1 can further improve the sound pressure of at least one of the fundamental wave of the first alarm sound and the plurality of harmonics of the first alarm sound. As a result, the acoustic device 1 can improve the sound pressures of both the first alarm sound and the second alarm sound having different frequencies.

Here, in order to explain the effect of the acoustic device 1, the acoustic device of the comparative example in which the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc is set to be less than the value of the frequency fB of the fundamental wave of the second alarm sound. Will be described with reference to FIGS. 5A and 5B. The types and reference numerals of the graphs of FIGS. 5A and 5B are the same as those of FIGS. 4A and 4B, respectively.

In the acoustic device of the comparative example, the smaller the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc, the larger the peak of the radiation characteristic 50. Therefore, in FIG. 5B, the sound pressure level of the fifth harmonic of the first alarm sound included in the frequency band between the resonance frequency Fp and the resonance frequency Fc is the fundamental wave of the first alarm sound and other harmonics. It becomes larger than the sound pressure level fN (for example, about 60 [dB]) (for example, about 100 [dB]). However, since neither the fundamental wave of the second alarm sound nor the plurality of harmonics of the second alarm sound is included in the frequency band between the resonance frequency Fp and the resonance frequency Fc, the acoustic device of the comparative example is the second. It is difficult to improve the sound pressure of the alarm sound.

Next, another comparative example acoustic device will be described. The case where the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc of the acoustic device of another comparative example is set to be equal to or higher than the value of the frequency 2fB of the second harmonic of the second alarm sound will be described. In this case, the harmonics of the first alarm sound and the second alarm sound are included in the frequency band between the resonance frequency Fp and the resonance frequency Fc of the acoustic device of another comparative example, respectively. However, as the resonance frequency Fp and the resonance frequency Fc are separated from each other, the minimum sound pressure level of the radiation characteristic 50 in the frequency band between the resonance frequency Fp and the resonance frequency Fc becomes smaller, and the peak of the sound pressure level in the frequency band becomes smaller. Also becomes smaller. That is, even if the frequency band between the resonance frequency Fp and the resonance frequency Fc includes the first alarm sound and the second alarm sound, the acoustic device of another comparative example has the first alarm sound and the second alarm sound. It is difficult to improve both sound pressures.

(5) Summary As described above, the alarm sound acoustic device 1 in the present embodiment includes a plate-shaped vibrating body 11 and a housing 12. The vibrating body 11 resonates at the resonance frequency Fp. The housing 12 houses the vibrating body 11 and resonates at the resonance frequency Fc due to the vibration of the vibrating body 11 to emit a plurality of warning sounds (here, the first warning sound and the second warning sound), respectively. Each of the plurality of alarm sounds is an alarm sound having different fundamental frequencies (frequency fA and frequency fB). The relationship between the highest fundamental frequency f (here, frequency fB) among the fundamental frequencies of the plurality of alarm sounds, the resonance frequency Fp, and the resonance frequency Fc is f ≦ | Fp-Fc |.

According to the above configuration, the resonance frequency Fp and the resonance frequency Fc are the fundamental frequencies f (frequency fB) in which the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc is the highest among the fundamental frequencies f of the plurality of alarm sounds. It is set above the value. As a result, the frequency band between the resonance frequency Fp and the resonance frequency Fc includes at least one harmonic among the plurality of harmonics of the alarm sound (harmonics of the second signal B2). The harmonics included in the frequency band described above are harmonics of the alarm sound including the highest fundamental frequency f among the fundamental frequencies f of the plurality of alarm sounds. Further, since the frequency of the fundamental wave of the other alarm sounds (frequency fA in this case) is lower than the fundamental frequency f (frequency fB) among the plurality of alarm sounds, the harmonics of the other alarm sounds (first alarm sound). The frequency spacing between each other is smaller than the frequency spacing between the resonance frequency Fp and the resonance frequency Fc. Therefore, the frequency band between the resonance frequency Fp and the resonance frequency Fc includes at least one harmonic among the plurality of harmonics in the other alarm sound (first alarm sound). Therefore, the alarm sound sound device 1 can improve the sound pressure of a plurality of alarm sounds having different frequencies.

In the alarm sound acoustic device 1 of the present embodiment, the relationship between the frequency 2f (here, the frequency 2fB) which is twice the fundamental frequency f, the resonance frequency Fp, and the resonance frequency Fc is | Fp-Fc | <2f. Is preferable. As a result, the resonance frequency Fp and the resonance frequency Fc have an absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc less than twice the frequency of the highest fundamental frequency f (frequency fB) among the plurality of alarm sounds. Is set to. The frequency band between the resonance frequency Fp and the resonance frequency Fc is an alarm sound (second alarm sound) including the highest fundamental frequency f (frequency fB) among the fundamental frequencies f of the plurality of alarm sounds. One of the harmonics of the alarm sound (for example, the third harmonic) will be included. Therefore, the alarm sound sound device 1 can increase the sound pressure of a plurality of alarm sounds having different frequencies. Here, as the absolute value of the difference between the resonance frequency Fp and the resonance frequency Fc becomes larger, the minimum sound pressure in the frequency band between the resonance frequency Fp and the resonance frequency Fc becomes smaller, and the sound pressure peak in the frequency band becomes smaller. The amount of decrease becomes large. However, by satisfying | Fp-Fc | <2f, a plurality of harmonics (or fundamental waves) of alarm sounds can be included in the frequency band between the resonance frequency Fp and the resonance frequency Fc, and the frequency band thereof. The amount of decrease with respect to the peak of sound pressure can be minimized.

In the alarm sound acoustic device 1 of the present embodiment, each of the plurality of alarm sounds (first alarm sound and second alarm sound) includes a fundamental wave and at least one harmonic. The frequency of at least one harmonic (here, the fifth harmonic to the seventh harmonic of the first alarm sound and the third harmonic of the second alarm sound) is between the resonance frequency Fp and the resonance frequency Fc. Is preferable. As a result, even if there are a plurality of alarm sounds such that the fundamental frequency f does not exist between the resonance frequency Fp and the resonance frequency Fc, the sound pressure of each alarm sound is increased by increasing the sound pressure of the harmonic of each alarm sound. be able to.

The acoustic system 100 of the present embodiment includes the above-mentioned alarm sound acoustic device 1 and a generation unit 2. The generation unit 2 generates a plurality of electric signals (here, the first signal A1 and the second signal B2) corresponding to the plurality of alarm sounds (first alarm sound and second alarm sound) on a one-to-one basis. The vibrating body 11 is configured to resonate at each frequency of a plurality of electric signals.

According to the above configuration, the acoustic system 100 can radiate a plurality of alarm sounds having different fundamental frequencies from the housing 12 of the acoustic device 1 according to the frequencies of the plurality of electric signals generated by the generation unit 2. can. Moreover, the acoustic system 100 can increase the sound pressures of a plurality of alarm sounds (first alarm sound and second alarm sound) having different fundamental frequencies. Therefore, the acoustic system 100 can improve the sound pressure for a plurality of alarm sounds having different frequencies.

By the way, the acoustic device 1 is not limited to the configuration in which the first alarm sound and the second alarm sound are alternately output, and may output only the first alarm sound or only the second alarm sound. Since the sound device 1 can improve the sound pressure in any of the first alarm sound and the second alarm sound, for example, it is not necessary to manufacture the sound device according to the type of the alarm sound. It also improves and the manufacturing cost can be suppressed.

The plurality of alarm sounds are not limited to the alarm sounds having frequency characteristics such that the harmonic is between the resonance frequency Fp and the resonance frequency Fc, but the frequency such that the fundamental wave is between the resonance frequency Fp and the resonance frequency Fc. It may be a characteristic alarm sound.

The number of the plurality of alarm sounds is not limited to two, and may be three or more.

The sound system 100 may be, for example, a system that radiates an alarm sound for the purpose of crime prevention to the outside, in addition to notifying the occurrence of a fire. The sound system 100 may be, for example, a system that sounds an alarm sound according to the presence or absence of a person and the open / closed state of the door.

1 Sound device 11 Vibrating body 12 Housing 2 Generation unit 100 Sound system A1 First signal (electric signal)
B2 2nd signal (electrical signal)

Claims (5)

A plate-shaped vibrating body that resonates at the resonance frequency Fp,
A housing that houses the vibrating body and resonates at the resonance frequency Fc due to the vibration of the vibrating body to emit a plurality of alarm sounds, respectively.
Equipped with
Each of the plurality of alarm sounds is an alarm sound having a different fundamental frequency from each other.
The relationship between the highest fundamental frequency f among the fundamental frequencies of the plurality of alarm sounds, the resonance frequency Fp, and the resonance frequency Fc is as follows.
f ≦ ｜ Fp-Fc ｜
Doo Ri Na,
An alarm sound acoustic device in which at least one harmonic of the plurality of harmonics of the fundamental frequency is included in a frequency band between the resonance frequency Fp and the resonance frequency Fc for each of the plurality of alarm sounds. The relationship between the frequency 2f, which is twice the fundamental frequency f, the resonance frequency Fp, and the resonance frequency Fc, is as follows.
| Fp-Fc | <2f
The alarm sound acoustic device according to claim 1. Each of the plurality of alarm sounds includes a fundamental wave and at least one harmonic.
The alarm sound acoustic device according to claim 1 or 2, wherein the frequency of the at least one harmonic is between the resonance frequency Fp and the resonance frequency Fc. The plurality of alarm sounds are alarm sounds for notifying the occurrence of a fire.
The acoustic device according to any one of claims 1 to 3. The alarm sound acoustic device according to any one of claims 1 to 4,
A generation unit that generates a plurality of electric signals having a one-to-one correspondence with the plurality of alarm sounds,
Equipped with
The vibrating body is an acoustic system configured to resonate at each frequency of the plurality of electric signals.

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