Sound wave generation device

Abstract

A sound wave generation device according to one aspect of the present disclosure is capable of generating a first sound wave by vibrating a plurality of first MEMS vibration units using a second voltage signal having a frequency in the ultrasonic range and a fourth voltage signal obtained by amplitude modulation of the second voltage signal by a first voltage signal having a frequency in the audible range. Furthermore, the sound wave generation device can generate a second sound wave capable of interfering with the first sound wave in a space by vibrating a plurality of second MEMS vibration units using a third voltage signal having an opposite phase to the second voltage signal and a fifth voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal.

Description

Sound wave generator

[0001] This disclosure relates to a sound wave generating device.

[0002] A speaker that utilizes vibrations generated by a MEMS (Micro Electro Mechanical Systems) circuit (hereinafter referred to as "MEMS speaker") has been proposed (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2024-96072

[0004] Incidentally, a common problem with MEMS speakers is their low sound pressure, especially in the low-frequency range. As a solution, a technique has been proposed in which ultrasonic waves are modulated using audible sound waves, the resulting modulated ultrasonic waves are propagated through the air, and the audible sound waves with waveforms corresponding to the envelope of the modulated ultrasonic waves are demodulated using the air. According to this technique, audible sound waves with high sound pressure can be obtained by demodulating audible sound waves from modulated ultrasonic waves using the air. However, since this technique outputs not only audible sound waves but also ultrasonic waves, there are concerns about the effects of ultrasonic waves on the human body. It is desirable to reduce the effects of ultrasonic waves on the human body and to provide a sound wave generator that can reduce noise.

[0005] A sound wave generator according to the first aspect of this disclosure comprises an electrical signal circuit and a sound wave output circuit. The electrical signal circuit includes a first signal source, a second signal source, a third signal source, a first modulator, and a second modulator. The first signal source is capable of generating a first voltage signal with a frequency in the audible range. The second signal source is capable of generating a second voltage signal with a frequency in the ultrasonic range. The third signal source is capable of generating a third voltage signal with the opposite phase to the second voltage signal. The first modulator is capable of generating a fourth voltage signal by amplitude modulating the second voltage signal with the first voltage signal. The second modulator is capable of generating a fifth voltage signal by amplitude modulating the third voltage signal with the first voltage signal. The sound wave output circuit includes a first MEMS circuit and a second MEMS circuit. The first MEMS circuit is capable of generating a first sound wave by vibrating a plurality of first MEMS vibrating parts with the second voltage signal and the fourth voltage signal. The second MEMS circuit generates a second sound wave that can interfere with the first sound wave in space by vibrating multiple second MEMS vibrating parts using a third voltage signal and a fifth voltage signal.

[0006] In the sound wave generator according to the first aspect of this disclosure, a first sound wave is generated by vibrating a plurality of first MEMS vibrators with a second voltage signal having a frequency in the ultrasonic range and a fourth voltage signal obtained by amplitude modulation of the second voltage signal by the first voltage signal having a frequency in the audible range. Furthermore, a second sound wave capable of interfering with the first sound wave in space is generated by vibrating a plurality of second MEMS vibrators with a third voltage signal having the opposite phase to the second voltage signal and a fifth voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal. Due to the mutual interference between the first and second sound waves in space, the ultrasonic waves contained in the first sound wave and the ultrasonic waves contained in the second sound wave cancel each other out, and a composite sound wave of the audible sound waves contained in the first sound wave and the audible sound waves contained in the second sound wave is output.

[0007] A sound wave generator according to a second aspect of this disclosure comprises an electrical signal circuit and a sound wave output circuit. The electrical signal circuit includes a first signal source, a second signal source, a third signal source, a first modulator, and a second modulator. The first signal source is capable of generating a first voltage signal with a frequency in the audible range. The second signal source is capable of generating a second voltage signal with a frequency in the ultrasonic range. The third signal source is capable of generating a third voltage signal with a phase shifted by 90 degrees with respect to the phase of the second voltage signal. The first modulator is capable of generating a fourth voltage signal by amplitude modulating the second voltage signal with the first voltage signal. The second modulator is capable of generating a fifth voltage signal by amplitude modulating the third voltage signal with the first voltage signal.

[0008] In the sound wave generator according to the second aspect of this disclosure, a first sound wave is generated by vibrating a plurality of first MEMS vibrators with a second voltage signal having a frequency in the ultrasonic range and a fourth voltage signal obtained by amplitude modulation of the second voltage signal by a first voltage signal having a frequency in the audible range. Furthermore, a second sound wave capable of interfering with the first sound wave in space is generated by vibrating a plurality of second MEMS vibrators with a third voltage signal having a phase shifted by 90 degrees with respect to the phase of the second voltage signal and a fifth voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal. Due to the mutual interference between the first and second sound waves in space, the ultrasonic waves contained in the first sound wave and the ultrasonic waves contained in the second sound wave cancel each other out, and a composite sound wave of the audible sound waves contained in the first sound wave and the audible sound waves contained in the second sound wave is output.

[0009] A sound wave generator according to a third aspect of this disclosure comprises an electrical signal circuit and a sound wave output circuit. The electrical signal circuit includes a first signal source, a second signal source, a third signal source, a fourth signal source, a fifth signal source, a first modulator, a second modulator, a third modulator, and a fourth modulator. The first signal source is capable of generating a first voltage signal with a frequency in the audible range. The second signal source is capable of generating a second voltage signal with a frequency in the ultrasonic range. The third signal source is capable of generating a third voltage signal with a phase shifted by 90 degrees with respect to the phase of the second voltage signal. The fourth signal source is capable of generating a fourth voltage signal with the opposite phase to the second voltage signal. The fifth signal source is capable of generating a fifth voltage signal with the opposite phase to the third voltage signal. The first modulator is capable of generating a sixth voltage signal by amplitude modulating the second voltage signal with the first voltage signal. The second modulator is capable of generating a seventh voltage signal by amplitude modulating the third voltage signal with the first voltage signal. The third modulator is capable of generating an eighth voltage signal by amplitude modulating the fourth voltage signal with the first voltage signal. The fourth modulator is capable of generating a ninth voltage signal by amplitude modulating the fifth voltage signal with the first voltage signal. The sound wave output circuit has a first MEMS circuit, a second MEMS circuit, a third MEMS circuit, and a fourth MEMS circuit. The first MEMS circuit is capable of generating a first sound wave by vibrating multiple first MEMS vibrators with the second voltage signal and the sixth voltage signal. The second MEMS circuit is capable of generating a second sound wave that can interfere with the first sound wave in space by vibrating multiple second MEMS vibrators with the third voltage signal and the seventh voltage signal. The third MEMS circuit is capable of generating a third sound wave that can interfere with the first and second sound waves in space by vibrating multiple third MEMS vibrators with the fourth voltage signal and the eighth voltage signal. The fourth MEMS circuit generates a fourth sound wave that can interfere with the first, second, and third sound waves in space by vibrating multiple fourth MEMS vibrating parts using the fifth and ninth voltage signals.

[0010] In the sound wave generator relating to the third aspect of this disclosure, a first sound wave is generated by vibrating a plurality of first MEMS vibrators with a second voltage signal having a frequency in the ultrasonic range and a sixth voltage signal obtained by amplitude modulation of the second voltage signal by a first voltage signal having a frequency in the audible range. Furthermore, a second sound wave capable of interfering with the first sound wave in space is generated by vibrating a plurality of second MEMS vibrators with a third voltage signal having a phase shifted by 90 degrees with respect to the phase of the second voltage signal and a seventh voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal. Furthermore, a third sound wave capable of interfering with the first and second sound waves in space is generated by vibrating a plurality of third MEMS vibrators with a fourth voltage signal having the opposite phase to the second voltage signal and an eighth voltage signal obtained by amplitude modulation of the fourth voltage signal by the first voltage signal. Furthermore, by vibrating multiple fourth MEMS vibrators with a fifth voltage signal that is in the opposite phase to the third voltage signal and a ninth voltage signal obtained by amplitude modulation of the fifth voltage signal by the first voltage signal, a fourth sound wave is generated that can interfere with the first, second, and third sound waves in space. Due to the mutual interference of the first, second, third, and fourth sound waves in space, the ultrasonic waves contained in the first, second, third, and fourth sound waves are attenuated from each other, and a composite sound wave of the audible sound waves contained in the first, second, third, and fourth sound waves is output.

[0011] Figure 1 is a diagram showing an example configuration of a sound wave generator according to the first embodiment of this disclosure. Figure 2 is a diagram showing an example configuration of a sound wave generator according to a comparative example. Figure 3 is a diagram showing an example configuration of a sound wave generator according to the second embodiment of this disclosure. Figure 4 is a diagram showing an example configuration of a sound wave generator according to the third embodiment of this disclosure.

[0012] The forms for implementing this disclosure will be described in detail below with reference to the drawings. The explanation will be given in the following order.

[0013] <1. First Embodiment> [Configuration] Figure 1 shows an example of the configuration of a sound wave generator 100 according to the first embodiment of the present disclosure. The sound wave generator 100 is a MEMS speaker capable of generating audible sound waves by propagating modulated ultrasonic waves in the air by ultrasonic vibration of a large number of MEMS circuits arranged in a plane, and demodulating the modulated ultrasonic waves using the air. Figure 1 illustrates a part of the large number of MEMS circuits arranged in a plane and an electrical signal circuit capable of driving a part of the MEMS circuits. The sound wave generator 100 includes, for example, a sound wave output circuit 120 and an electrical signal circuit 110 capable of driving the sound wave output circuit 120, as shown in Figure 1. The electrical signal circuit 110 corresponds to a specific example of the "electrical signal circuit" according to one embodiment of the present disclosure. The sound wave output circuit 120 corresponds to a specific example of the "sound wave output circuit" according to one embodiment of the present disclosure.

[0014] The electrical signal circuit 110 includes an audible sound wave signal source 111, two ultrasonic signal sources 112 and 113 whose output signals have different phases, and two modulators 114 and 115. The audible sound wave signal source 111 corresponds to a specific example of the "first signal source" according to one embodiment of the present disclosure. The ultrasonic signal source 112 corresponds to a specific example of the "second signal source" according to one embodiment of the present disclosure. The ultrasonic signal source 113 corresponds to a specific example of the "third signal source" according to one embodiment of the present disclosure. The modulator 114 corresponds to a specific example of the "first modulator" according to one embodiment of the present disclosure. The modulator 115 corresponds to a specific example of the "second modulator" according to one embodiment of the present disclosure.

[0015] The audible sound wave signal source 111 has a frequency ω in the audible range. ｓ Audible sound signal V ｓｏｕｎｄ It is possible to generate the ultrasonic signal source 112, which has an ultrasonic frequency ω ｃ Carrier signal (+V ｃａｒｒｉｅｒ The ultrasonic signal source 113 is capable of generating a carrier signal (+V). ｃａｒｒｉｅｒ The carrier signal (-V) which is in the opposite phase of ) ｃａｒｒｉｅｒ It is possible to generate an audible sound signal V. ｓｏｕｎｄ This corresponds to a specific example of the "first voltage signal" according to one embodiment of the present disclosure. Carrier signal (+Vｃａｒｒｉｅｒ ) corresponds to a specific example of the "second voltage signal" according to an embodiment of the present disclosure. The carrier signal (-V ｃａｒｒｉｅｒ ) corresponds to a specific example of the "third voltage signal" according to an embodiment of the present disclosure.

[0016] The modulator 114 can generate a modulated ultrasonic signal (+V ｓｏｕｎｄ ) by amplitude-modulating the carrier signal (+V ｃａｒｒｉｅｒ ) with the audible sound signal V. The modulator 115 can generate a modulated ultrasonic signal (-V ＤＳＢ ) by amplitude-modulating the carrier signal (-V ｓｏｕｎｄ ) with the audible sound signal V. The modulated ultrasonic signal (+V ｃａｒｒｉｅｒ ) corresponds to a specific example of the "fourth voltage signal" according to an embodiment of the present disclosure. The modulated ultrasonic signal (-V ＤＳＢ ) corresponds to a specific example of the "fifth voltage signal" according to an embodiment of the present disclosure. ＤＳＢ ) corresponds to a specific example of the "fourth voltage signal" according to an embodiment of the present disclosure. The modulated ultrasonic signal (-V ＤＳＢ ) corresponds to a specific example of the "fifth voltage signal" according to an embodiment of the present disclosure.

[0017] The acoustic wave output circuit 120 includes MEMS circuits 121 and 222. The MEMS circuit 121 corresponds to a specific example of the "first MEMS circuit" according to an embodiment of the present disclosure. The MEMS circuit 122 corresponds to a specific example of the "second MEMS circuit" according to an embodiment of the present disclosure.

[0018] The MEMS circuit 121 includes two MEMS vibrating parts 121a and 121b. The MEMS circuit 121 can generate a first acoustic wave by vibrating the two MEMS vibrating parts 121a and 121b with the carrier signal (+V ｃａｒｒｉｅｒ ) and the modulated ultrasonic signal (+V ＤＳＢ ). The carrier signal (+V ｃａｒｒｉｅｒ ) is input to the MEMS vibrating part 121a. The modulated ultrasonic signal (+V ＤＳＢ ) is input to the MEMS vibrating part 121b. The two MEMS vibrating parts 121a and 121b correspond to a specific example of the "plurality of first MEMS vibrating parts" according to an embodiment of the present disclosure. The first acoustic wave corresponds to a specific example of the "first acoustic wave" according to an embodiment of the present disclosure.

[0019] The MEMS circuit 122 is composed of two MEMS vibration units 122a and 122b. The MEMS circuit 122 receives a carrier signal (-V ｃａｒｒｉｅｒ ) and modulated ultrasonic signal (-V ＤＳＢ By vibrating the two MEMS vibrating units 122a and 122b using the carrier signal (-V), it is possible to generate a second sound wave. ｃａｒｒｉｅｒ The modulated ultrasonic signal (-V) is input to the MEMS vibration unit 122a. ＤＳＢ The second sound wave is input to the MEMS vibration unit 122b. The two MEMS vibration units 122a and 122b correspond to one specific example of the "multiple second MEMS vibration units" according to one embodiment of the present disclosure. The second sound wave corresponds to one specific example of the "second sound wave" according to one embodiment of the present disclosure.

[0020] The "first sound wave" is an ultrasonic wave (+mW) that can be generated from the MEMS vibration unit 121a. ｃａｒｒｉｅｒ ) and ultrasonic waves (+nW) that can be generated from the MEMS vibration unit 121b ＤＳＢ ) and ultrasound (+mW ｃａｒｒｉｅｒ ) and ultrasound (+nW ＤＳＢ Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ W ＤＳＢ This includes ultrasound (+mW). ｃａｒｒｉｅｒ ) is the carrier signal (+V ｃａｒｒｉｅｒ ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "first ultrasonic wave" according to one embodiment of the present disclosure. Ultrasonic wave (+nW ＤＳＢ ) is a modulated ultrasonic signal (+V ＤＳＢ ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "second ultrasonic wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ W ＤＳＢ Ultrasound (+mW) ｃａｒｒｉｅｒ ) and ultrasound (+nW ＤＳＢ Audible sound waves lW are generated by the mutual interference in space with ) ｓｏｕｎｄ and two types of ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄThis corresponds to one specific example of the "first audible sound wave" according to one embodiment of the present disclosure. Ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ This corresponds to one specific example of the "third ultrasonic wave" according to one embodiment of the present disclosure.

[0021] The "second sound wave" is an ultrasonic wave (-nW) that can be generated from the MEMS vibration unit 122a. ＤＳＢ ) and ultrasonic waves (-mW) that can be generated from the MEMS vibration unit 122b ｃａｒｒｉｅｒ ) and ultrasound (-nW ＤＳＢ ) and ultrasound (-mW) ｃａｒｒｉｅｒ Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ W ＤＳＢ This includes ultrasound (-nW). ＤＳＢ ) is a modulated ultrasonic signal (-V ＤＳＢ ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "fifth ultrasonic wave" according to one embodiment of the present disclosure. Ultrasonic wave (-mW) ｃａｒｒｉｅｒ ) is the carrier signal (-V ｃａｒｒｉｅｒ ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "fourth ultrasonic wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ W ＤＳＢ Ultrasound (-mW) ｃａｒｒｉｅｒ ) and ultrasound (-nW ＤＳＢ Audible sound waves lW are generated by the mutual interference in space with ) ｓｏｕｎｄ and two types of ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ This corresponds to a specific example of the "second audible sound wave" according to one embodiment of the present disclosure. Ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ This corresponds to one specific example of the "sixth ultrasonic wave" according to one embodiment of the present disclosure.

[0022] Here, W ｓｏｕｎｄ , W ｃａｒｒｉｅｒ , W ＤＳＢ However, let it be expressed by the following equations (1), (2), and (3).

[0023] The acoustic wave output circuit 120 can mainly output the acoustic waves (2×lW ｃａｒｒｉｅｒ ) generated from the MEMS circuits 121 and 122 by canceling out the ultrasonic waves (+mW ｃａｒｒｉｅｒ ) and the ultrasonic waves (-mW ＤＳＢ ) with each other in the external space ES between the first acoustic wave and the second acoustic wave, and canceling out the ultrasonic waves (+nW ＤＳＢ ) and the ultrasonic waves (-nW ｃａｒｒｉｅｒ W ＤＳＢ ). Here, when the ultrasonic waves (+mW ｃａｒｒｉｅｒ ) and the ultrasonic waves (-mW ｃａｒｒｉｅｒ ) cancel each other out, and the ultrasonic waves (+nW ＤＳＢ ) and the ultrasonic waves (-nW ＤＳＢ ) cancel each other out, the acoustic wave output circuit 120 can output only the acoustic waves (2×lW ｃａｒｒｉｅｒ W ＤＳＢ ) (Equation (4)).

[0024] The acoustic waves (2×lW ｃａｒｒｉｅｒ W ＤＳＢ ) include the synthesized audible acoustic waves (2×lW ｓｏｕｎｄ ) of the audible acoustic wave lW ｓｏｕｎｄ generated from the MEMS circuit 121 and the audible acoustic wave lW ｓｏｕｎｄ generated from the MEMS circuit 122. The acoustic waves (2×lW ｃａｒｒｉｅｒ W ＤＳＢ ) further include the ultrasonic waves (+lW ｃａｒｒｉｅｒ１ ) generated from the MEMS circuits 121 and 122 and the ultrasonic waves (+lW ｃａｒｒｉｅｒ２ ) generated from the MEMS circuit 122. The synthesized audible acoustic waves (2×lW ｓｏｕｎｄ ) are represented by (1 / 4)lW ｓ W ｃ {2e ｊωｓｔ + 2e －ｊωｓｔ}. The ultrasonic waves (lW ｃａｒｒｉｅｒ１ ) are represented by (1 / 4)lW ｓ W ｃ {ej(2ωc + ωs)t + e - j(2ωc + ωs)t}. The ultrasonic waves (lW ｃａｒｒｉｅｒ２ ) are represented by (1 / 4)lW ｓ W ｃIt is expressed as {ej(2ωc-ωs)t + e-j(2ωc-ωs)t}. Therefore, the sound wave (2 × lW) ｃａｒｒｉｅｒ W ＤＳＢ ) is expressed by equation (5).

[0025] For example, ω ｓ ω is 1 kHz, ｃ Let's assume it's 400 kHz. At this time, ultrasound (+nW) ＤＳＢ ) includes 399 kHz ultrasound and 401 kHz ultrasound. Ultrasound (-nW) ＤＳＢ ) includes 399 kHz ultrasound and 401 kHz ultrasound. Sound waves (2 × lW) ｃａｒｒｉｅｒ W ＤＳＢ ) includes audible sound waves at 1 kHz, ultrasound at 799 kHz, and ultrasound at 801 kHz. Ultrasound (+mW) ｃａｒｒｉｅｒ ) and ultrasound (-mW) ｃａｒｒｉｅｒ ) and cancel each other out, and ultrasound (+nW ＤＳＢ ) and ultrasound (-nW ＤＳＢ If these cancel each other out, the sound wave output circuit 120 will not output ultrasonic waves at 400 kHz, 399 kHz, and 401 kHz, and will only output audible sound waves at 1 kHz and ultrasonic waves at 799 kHz and 801 kHz.

[0026] [Effects] Next, the effects of the sound wave generator 100 will be explained in comparison with the sound wave generator 200 of the comparative example.

[0027] Figure 2 shows an example configuration of a sound wave generator 200 according to a comparative example. The sound wave generator 200 is a MEMS speaker capable of generating audible sound waves by propagating modulated ultrasonic waves in the air through ultrasonic vibrations of a number of MEMS circuits arranged in a plane, and demodulating the modulated ultrasonic waves using the air. Figure 2 illustrates some of the number of MEMS circuits arranged in a plane and an electrical signal circuit capable of driving some of the MEMS circuits. The sound wave generator 200 includes, for example, a sound wave output circuit 220 and an electrical signal circuit 210 capable of driving the sound wave output circuit 220, as shown in Figure 2.

[0028] The electrical signal circuit 210 includes an audible sound wave signal source 211, an ultrasonic signal source 212, and a modulator 213. The audible sound wave signal source 211 has a frequency ω in the audible range. ｓ Audible sound signal V ｓｏｕｎｄ It is possible to generate the ultrasonic signal source 212 has an ultrasonic frequency ω ｃ Carrier signal (+V ｃａｒｒｉｅｒ The modulator 213 is capable of generating an audible sound signal V. ｓｏｕｎｄ The carrier signal (+V ｃａｒｒｉｅｒ By amplitude modulation of ), a modulated ultrasonic signal (+V ＤＳＢ It is possible to generate ).

[0029] The sound wave output circuit 220 has a MEMS circuit 221. The MEMS circuit 221 is composed of two MEMS vibration units 221a and 221b. The MEMS circuit 221 receives a carrier signal (+V ｃａｒｒｉｅｒ ) and modulated ultrasonic signal (+V ＤＳＢ By vibrating the two MEMS vibration units 221a and 221b using ), it is possible to generate a "predetermined sound wave." The "predetermined sound wave" is an ultrasonic wave (+mW) that can be generated from the MEMS vibration unit 221a. ｃａｒｒｉｅｒ ) and ultrasonic waves (+nW) that can be generated from the MEMS vibration unit 221b ＤＳＢ ) and ultrasound (+mW ｃａｒｒｉｅｒ ) and ultrasound (+nW ＤＳＢ Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ W ＤＳＢ This includes (Equation (6)).

[0030] Here, W ｓｏｕｎｄ , W ｃａｒｒｉｅｒ , W ＤＳＢ However, let's assume that it is represented by the above equations (1), (2), and (3). In this case, the "predetermined sound wave" is represented by the following equation (7).

[0031] Thus, in the comparative example, the sound wave generator 200 generates ultrasonic waves (+mW) from the MEMS circuit 221. ｃａｒｒｉｅｒ , +nW ＤＳＢ) is output to the external space ES without being reduced or canceled out.

[0032] On the other hand, in this embodiment, the carrier signal (+V ｃａｒｒｉｅｒ ) and modulated ultrasonic signal (+V ＤＳＢ The first sound wave is generated by vibrating two MEMS vibrators 121a and 121b using the carrier signal (+V). ｃａｒｒｉｅｒ The carrier signal (-V) which is in the opposite phase of ) ｃａｒｒｉｅｒ ) and modulated ultrasonic signal (-V ＤＳＢ By vibrating the two MEMS vibrating sections 122a and 122b, a second sound wave capable of interfering with the first sound wave in space is generated. Through the mutual interference of the first and second sound waves in space, the ultrasonic waves contained in the first sound wave (+mW) ｃａｒｒｉｅｒ , +nW ＤＳＢ ) and the ultrasound contained in the second sound wave (-mW ｃａｒｒｉｅｒ , -nW ＤＳＢ ) and cancel each other out or cancel each other out. Furthermore, due to the mutual interference between the first sound wave and the second sound wave in space, the audible sound wave (lW) contained in the first sound wave is reduced. ｓｏｕｎｄ ) and the audible sound waves (lW) contained in the second sound wave ｓｏｕｎｄ ) and the combined sound wave and the ultrasound (+1W) contained in the first sound wave ｃａｒｒｉｅｒ１ ) and the ultrasound (+1W) contained in the second sound wave ｃａｒｒｉｅｒ２ ) Combined ultrasound (2 × lW) ｃａｒｒｉｅｒ１ ) is output. Thus, in this embodiment, the ultrasonic waves (+mW) included in the first sound wave are output. ｃａｒｒｉｅｒ , +nW ＤＳＢ ) and the ultrasound contained in the second sound wave (-mW ｃａｒｒｉｅｒ , -nW ＤＳＢ ) and are mutually reduced or canceled out. As a result, the effects of ultrasound on the human body can be reduced compared to the sound wave generator 200 of the comparative example.

[0033] In this embodiment, instead of the two ultrasonic signal sources 112 and 113, an ultrasonic signal source capable of generating two types of ultrasonic waves with opposite phases to each other may be provided. Even in this case, the same effects as in the above embodiment can be obtained.

[0034] <2. Second Embodiment> [Configuration] Figure 3 shows an example of the configuration of a sound wave generator 300 according to a second embodiment of the present disclosure. The sound wave generator 300 is a MEMS speaker capable of generating audible sound waves by propagating modulated ultrasonic waves in the air by ultrasonic vibration of a large number of MEMS circuits arranged in a plane, and demodulating the modulated ultrasonic waves using the air. Figure 3 illustrates a part of the large number of MEMS circuits arranged in a plane and an electrical signal circuit capable of driving a part of the MEMS circuits. The sound wave generator 300 includes, for example, a sound wave output circuit 320 and an electrical signal circuit 310 capable of driving the sound wave output circuit 320, as shown in Figure 3. The electrical signal circuit 310 corresponds to a specific example of the "electrical signal circuit" according to one embodiment of the present disclosure. The sound wave output circuit 320 corresponds to a specific example of the "sound wave output circuit" according to one embodiment of the present disclosure.

[0035] The electrical signal circuit 310 includes an audible sound wave signal source 311, two ultrasonic signal sources 312 and 313 whose output signals have different phases, and two modulators 314 and 315. The audible sound wave signal source 311 corresponds to a specific example of the "first signal source" according to one embodiment of the present disclosure. The ultrasonic signal source 312 corresponds to a specific example of the "second signal source" according to one embodiment of the present disclosure. The ultrasonic signal source 313 corresponds to a specific example of the "third signal source" according to one embodiment of the present disclosure. The modulator 314 corresponds to a specific example of the "first modulator" according to one embodiment of the present disclosure. The modulator 315 corresponds to a specific example of the "second modulator" according to one embodiment of the present disclosure.

[0036] The audible sound wave signal source 311 has a frequency ω in the audible range. ｓ Audible sound signal V ｓｏｕｎｄ It is possible to generate the ultrasonic signal source 312, which has an ultrasonic frequency ω ｃ Carrier signal (+V ｃａｒｒｉｅｒ_q The ultrasonic signal source 313 is capable of generating a carrier signal (+V). ｃａｒｒｉｅｒ_q A carrier signal (+V) whose phase is shifted by 90 degrees relative to the phase of ) ｃａｒｒｉｅｒ_i It is possible to generate an audible sound signal V. ｓｏｕｎｄThis corresponds to a specific example of the "first voltage signal" according to one embodiment of the present disclosure. Carrier signal (+V ｃａｒｒｉｅｒ_q ) corresponds to one specific example of the "second voltage signal" according to one embodiment of the present disclosure. Carrier signal (+V ｃａｒｒｉｅｒ_i This corresponds to one specific example of the "third voltage signal" according to one embodiment of the present disclosure.

[0037] Modulator 314 receives the audible sound signal V ｓｏｕｎｄ The carrier signal (+V ｃａｒｒｉｅｒ_q By amplitude modulation of ), a modulated ultrasonic signal (+V ＤＳＢ_q The modulator 315 is capable of generating an audible sound signal V ｓｏｕｎｄ The carrier signal (+V ｃａｒｒｉｅｒ_i By amplitude modulation of ), modulated ultrasonic signal V ＤＳＢ_i It is possible to generate a modulated ultrasonic signal (+V). ＤＳＢ_q ) corresponds to a specific example of the "fourth voltage signal" according to one embodiment of the present disclosure. Modulated ultrasonic signal (+V ＤＳＢ_i This corresponds to a specific example of the "fifth voltage signal" according to one embodiment of the present disclosure.

[0038] The sound wave output circuit 320 includes MEMS circuits 321 and 322. MEMS circuit 321 corresponds to a specific example of the "first MEMS circuit" according to one embodiment of the present disclosure. MEMS circuit 322 corresponds to a specific example of the "second MEMS circuit" according to one embodiment of the present disclosure.

[0039] The MEMS circuit 321 is composed of two MEMS vibration units 321a and 321b. The MEMS circuit 321 uses a carrier signal (+V ｃａｒｒｉｅｒ_q ) and modulated ultrasonic signal (+V ＤＳＢ_q By vibrating two MEMS vibration units 321a and 321b using the carrier signal (+V), it is possible to generate a first sound wave. ｃａｒｒｉｅｒ_q The modulated ultrasonic signal (+V) is input to the MEMS vibration unit 321a. ＤＳＢ_qThe sound is input to the MEMS vibration unit 321b. The two MEMS vibration units 321a and 321b correspond to one specific example of the "multiple first MEMS vibration units" according to one embodiment of the present disclosure. The first sound wave corresponds to one specific example of the "first sound wave" according to one embodiment of the present disclosure.

[0040] The MEMS circuit 322 is composed of two MEMS vibration units 322a and 322b. The MEMS circuit 322 uses a carrier signal (+V ｃａｒｒｉｅｒ_i ) and modulated ultrasonic signal (+V ＤＳＢ_i By vibrating two MEMS vibration units 322a and 322b using the carrier signal (+V), it is possible to generate a second sound wave. ｃａｒｒｉｅｒ_i The modulated ultrasonic signal (+V) is input to the MEMS vibration unit 322a. ＤＳＢ_i The second sound wave is input to the MEMS vibration unit 322b. The two MEMS vibration units 322a and 322b correspond to one specific example of the "multiple second MEMS vibration units" according to one embodiment of the present disclosure. The second sound wave corresponds to one specific example of the "second sound wave" according to one embodiment of the present disclosure.

[0041] The "first sound wave" is an ultrasonic wave (+mW) that can be generated from the MEMS vibration unit 321a. ｃａｒｒｉｅｒ_q ) and ultrasonic waves (+nW) that can be generated from the MEMS vibration unit 321b ＤＳＢ_q ) and ultrasound (+mW ｃａｒｒｉｅｒ_q ) and ultrasound (+nW ＤＳＢ_q Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ_q W ＤＳＢ_q This includes ultrasound (+mW). ｃａｒｒｉｅｒ_q ) is the carrier signal (+V ｃａｒｒｉｅｒ_q ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "first ultrasonic wave" according to one embodiment of the present disclosure. Ultrasonic wave (+nW ＤＳＢ_q ) is a modulated ultrasonic signal (+V ＤＳＢ_q ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "second ultrasonic wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ_q W ＤＳＢ_q Ultrasound (+mW)ｃａｒｒｉｅｒ_q ) and ultrasound (+nW ＤＳＢ_q Audible sound waves lW are generated by the mutual interference in space with ) ｓｏｕｎｄ and two types of ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ This corresponds to a specific example of the "first audible sound wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ１ ,lW ｃａｒｒｉｅｒ２ This corresponds to a specific example of the "third ultrasonic wave" according to one embodiment of the present disclosure.

[0042] The "second sound wave" is an ultrasonic wave (+nW) that can be generated from the MEMS vibration unit 322a. ＤＳＢ_i ) and ultrasonic waves (+mW) that can be generated from the MEMS vibration unit 322b ｃａｒｒｉｅｒ_i ) and ultrasound (+nW ＤＳＢ_i ) and ultrasound (+mW ｃａｒｒｉｅｒ_i Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ_i W ＤＳＢ_i This includes ultrasound (+nW). ＤＳＢ_i ) is a modulated ultrasonic signal (+V ＤＳＢ_i ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "fifth ultrasonic wave" according to one embodiment of the present disclosure. Ultrasonic wave (+mW) ｃａｒｒｉｅｒ_i ) is the carrier signal (+V ｃａｒｒｉｅｒ_i ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "fourth ultrasonic wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ_i W ＤＳＢ_i Ultrasound (+mW) ｃａｒｒｉｅｒ_i ) and ultrasound (+nW ＤＳＢ_i Audible sound waves lW are generated by the mutual interference in space with ) ｓｏｕｎｄ and two types of ultrasound (-1W) ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ This corresponds to a specific example of the "second audible sound wave" according to one embodiment of the present disclosure. Ultrasound (-lW) ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２This corresponds to one specific example of the "sixth ultrasonic wave" according to one embodiment of the present disclosure.

[0043] Here, W ｓｏｕｎｄ , W ｃａｒｒｉｅｒ_q , W ｃａｒｒｉｅｒ_i , W ＤＳＢ_q , W ＤＳＢ_i However, let it be expressed by the following equations (8), (9), (10), (11), and (12).

[0044] The sound wave output circuit 320 reacts to the mutual interference of the first sound wave and the second sound wave in the external space ES, thereby detecting the ultrasonic waves (+1W) generated from the MEMS circuit 321. ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) and ultrasonic waves (-1W) generated from the MEMS circuit 322 ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ ) and mutually cancel each other out, and the audible sound waves (2 × lW) generated from the MEMS circuits 321 and 322 ｓｏｕｎｄ ) and ultrasound (mW ｃａｒｒｉｅｒ_q nW ＤＳＢ_q , mW ｃａｒｒｉｅｒ_i nW ＤＳＢ_i It is possible to output mainly ultrasonic waves (+1W) generated from the MEMS circuit 321. ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) and ultrasonic waves (-1W) generated from the MEMS circuit 322 ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ If the two cancel each other out, the sound wave output circuit 320 outputs an audible sound wave (2 × lW). ｓｏｕｎｄ ) and ultrasound (mW ｃａｒｒｉｅｒ_q nW ＤＳＢ_q , mW ｃａｒｒｉｅｒ_i nW ＤＳＢ_i It is possible to output only ).

[0045] Sound waves (lW) ｃａｒｒｉｅｒ_q W ＤＳＢ_q ) is an audible sound wave lW generated from the MEMS circuit 321. ｓｏｕｎｄ and ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ is (1 / 8) lWｓ W ｃ {2e ｊωｓｔ +2e －ｊωｓｔ It is represented as}. Ultrasound (+lW ｃａｒｒｉｅｒ１ ) is (1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc+ωs)t+e-j(2ωc+ωs)t}. Ultrasound (+lW) ｃａｒｒｉｅｒ２ ) is (1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc-ωs)t + e-j(2ωc-ωs)t}. Therefore, the sound wave (lW) ｃａｒｒｉｅｒ_q W ＤＳＢ_q ) is expressed by equation (13).

[0046] Sound waves (lW) ｃａｒｒｉｅｒ_i W ＤＳＢ_i ) is an audible sound wave lW generated from the MEMS circuit 322. ｓｏｕｎｄ and ultrasound (-1W) ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ is (1 / 8) lW ｓ W ｃ {2e ｊωｓｔ +2e －ｊωｓｔ It is represented as}. Ultrasound (-lW ｃａｒｒｉｅｒ１ ) is -(1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc+ωs)t+e-j(2ωc+ωs)t}. Ultrasound (-lW) ｃａｒｒｉｅｒ２ ) is -(1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc-ωs)t + e-j(2ωc-ωs)t}. Therefore, the sound wave (lW) ｃａｒｒｉｅｒ_i W ＤＳＢ_i ) is expressed by equation (14).

[0047] From equations (13) and (14), lW ｃａｒｒｉｅｒ_q W ＤＳＢ_q +lW ｃａｒｒｉｅｒ_i W ＤＳＢ_i This is expressed by equation (15). Therefore, 2ω ｃ Nearby ultrasound is reduced or canceled out.

[0048] For example, ω ｓWhen 801 kHz noise is superimposed on it, ω ｃ When it is 400 kHz, ultrasonic nW ＤＳＢ_q This includes ultrasound at 401 kHz. ＤＳＢ_i nW ＤＳＢ_q It includes an out-of-phase 401 kHz ultrasonic wave. 2ω is a wideband noise contained in the audible sound wave signal source 311. ｃ Noise near 800 kHz is canceled out, and the noise is not converted into the audible range.

[0049] [Effects] Next, the effects of the sound wave generator 300 will be explained.

[0050] In this embodiment, the carrier signal (+V ｃａｒｒｉｅｒ_q ) and modulated ultrasonic signal (+V ＤＳＢ_q The first sound wave is generated by vibrating two MEMS vibrators 321a and 321b using the carrier signal (+V). ｃａｒｒｉｅｒ_q A carrier signal (+V) whose phase is shifted by 90 degrees relative to the phase of ) ｃａｒｒｉｅｒ_i ) and modulated ultrasonic signal (+V ＤＳＢ_i By vibrating the two MEMS vibrating sections 322a and 322b, a second sound wave capable of interfering with the first sound wave in space is generated. The mutual interference between the first and second sound waves in space generates 2ω, which is a wide-band noise contained in the audible sound wave signal source 311. ｃ Noise near 800 kHz is canceled out, and the noise is not converted into the audible range.

[0051] In this embodiment, in addition to the two ultrasonic signal sources 312 and 313, an ultrasonic signal source capable of generating two types of ultrasonic waves with phases shifted by 90 degrees from each other may be added. Even in this case, the same effects as in the above embodiment can be obtained.

[0052] <3. Third Embodiment> [Configuration] Figure 4 shows an example of the configuration of a sound wave generator 400 according to the third embodiment of the present disclosure. The sound wave generator 400 is a MEMS speaker capable of generating audible sound waves by propagating modulated ultrasonic waves in the air by ultrasonic vibration of a number of MEMS circuits arranged in a plane, and demodulating the modulated ultrasonic waves using the air. Figure 4 illustrates a part of the number of MEMS circuits arranged in a plane and an electrical signal circuit capable of driving a part of the MEMS circuits. The sound wave generator 400 further includes, for example, a sound wave output circuit 320 and an electrical signal circuit 310 capable of driving the sound wave output circuit 320, as shown in Figure 4. The electrical signal circuits 310 and 410 correspond to a specific example of the "electrical signal circuit" according to one embodiment of the present disclosure. The sound wave output circuits 320 and 420 correspond to a specific example of the "sound wave output circuit" according to one embodiment of the present disclosure.

[0053] The electrical signal circuit 410 includes an audible sound wave signal source 411, two ultrasonic signal sources 412 and 413 whose output signals have different phases, and two modulators 414 and 415. The audible sound wave signal source 411 corresponds to a specific example of the "first signal source" according to one embodiment of the present disclosure. The ultrasonic signal source 412 corresponds to a specific example of the "fourth signal source" according to one embodiment of the present disclosure. The ultrasonic signal source 413 corresponds to a specific example of the "fifth signal source" according to one embodiment of the present disclosure. The modulator 414 corresponds to a specific example of the "third modulator" according to one embodiment of the present disclosure. The modulator 415 corresponds to a specific example of the "fourth modulator" according to one embodiment of the present disclosure.

[0054] The audible sound wave signal source 411 has a frequency ω in the audible range. ｓ Audible sound signal V ｓｏｕｎｄ It is possible to generate the ultrasonic signal source 412, which generates the carrier signal (+V ｃａｒｒｉｅｒ_q The carrier signal (-V) which is in the opposite phase of ) ｃａｒｒｉｅｒ_q The ultrasonic signal source 413 is capable of generating a carrier signal (+V). ｃａｒｒｉｅｒ_i The carrier signal (-V) which is in the opposite phase of )ｃａｒｒｉｅｒ_i It is possible to generate an audible sound signal V. ｓｏｕｎｄ This corresponds to a specific example of the "first voltage signal" according to one embodiment of the present disclosure. Carrier signal (-V ｃａｒｒｉｅｒ_q ) corresponds to one specific example of the "fourth voltage signal" according to one embodiment of the present disclosure. Carrier signal (-V ｃａｒｒｉｅｒ_i This corresponds to a specific example of the "fifth voltage signal" according to one embodiment of the present disclosure.

[0055] Modulator 414 receives the audible sound signal V ｓｏｕｎｄ The carrier signal (-V ｃａｒｒｉｅｒ_q By amplitude modulation of ), a modulated ultrasonic signal (-V ＤＳＢ_q The modulator 415 is capable of generating an audible sound signal V. ｓｏｕｎｄ The carrier signal (-V ｃａｒｒｉｅｒ_i By amplitude modulation of ), a modulated ultrasonic signal (-V ＤＳＢ_i It is possible to generate a modulated ultrasonic signal (-V). ＤＳＢ_q ) corresponds to one specific example of the "eighth voltage signal" according to one embodiment of the present disclosure. Modulated ultrasonic signal (-V ＤＳＢ_i This corresponds to one specific example of the "ninth voltage signal" according to one embodiment of the present disclosure.

[0056] In this embodiment, the modulated ultrasonic signal (+V) output from the modulator 314 is ＤＳＢ_q ) corresponds to one specific example of the "sixth voltage signal" according to one embodiment of the present disclosure. Modulated ultrasonic signal (+V) output from modulator 315 ＤＳＢ_i This corresponds to one specific example of the "seventh voltage signal" according to one embodiment of the present disclosure.

[0057] The sound wave output circuit 420 includes MEMS circuits 421 and 422. MEMS circuit 421 corresponds to a specific example of the "third MEMS circuit" according to one embodiment of the present disclosure. MEMS circuit 422 corresponds to a specific example of the "fourth MEMS circuit" according to one embodiment of the present disclosure.

[0058] The MEMS circuit 421 is composed of two MEMS vibration units 421a and 421b. The MEMS circuit 421 receives a carrier signal (-V ｃａｒｒｉｅｒ_q ) and modulated ultrasonic signal (-V ＤＳＢ_qBy vibrating the two MEMS vibrating units 421a and 421b using the carrier signal (-V), it is possible to generate a third sound wave. ｃａｒｒｉｅｒ_q The modulated ultrasonic signal (-V) is input to the MEMS vibration unit 421a. ＤＳＢ_q The sound is input to the MEMS vibration unit 421b. The two MEMS vibration units 421a and 421b correspond to one specific example of the "multiple third MEMS vibration units" according to one embodiment of the present disclosure. The third sound wave corresponds to one specific example of the "third sound wave" according to one embodiment of the present disclosure.

[0059] The MEMS circuit 422 is composed of two MEMS vibration units 422a and 422b. The MEMS circuit 422 receives a carrier signal (-V ｃａｒｒｉｅｒ_i ) and modulated ultrasonic signal (-V ＤＳＢ_i By vibrating two MEMS vibration units 422a and 422b using the carrier signal (-V), it is possible to generate a fourth sound wave. ｃａｒｒｉｅｒ_i The modulated ultrasonic signal (-V) is input to the MEMS vibration unit 422a. ＤＳＢ_i The sound is input to the MEMS vibration unit 422b. The two MEMS vibration units 422a and 422b correspond to one specific example of the "multiple fourth MEMS vibration units" according to one embodiment of the present disclosure. The fourth sound wave corresponds to one specific example of the "fourth sound wave" according to one embodiment of the present disclosure.

[0060] The "third sound wave" is an ultrasonic wave (-mW) that can be generated from the MEMS vibration unit 421a. ｃａｒｒｉｅｒ_q ) and ultrasonic waves (-nW) that can be generated from the MEMS vibration unit 421b ＤＳＢ_q ) and ultrasound (-mW) ｃａｒｒｉｅｒ_q ) and ultrasound (-nW ＤＳＢ_q Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ_q W ＤＳＢ_q This includes ultrasound (-mW). ｃａｒｒｉｅｒ_q ) is the carrier signal (-V ｃａｒｒｉｅｒ_q ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "seventh ultrasonic wave" according to one embodiment of the present disclosure. Ultrasonic wave (-nW ＤＳＢ_q ) is a modulated ultrasonic signal (-V ＤＳＢ_q ) frequency ωｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "eighth ultrasonic wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ_q W ＤＳＢ_q Ultrasound (-mW) ｃａｒｒｉｅｒ_q ) and ultrasound (-nW ＤＳＢ_q Audible sound waves lW are generated by the mutual interference in space with ) ｓｏｕｎｄ and two types of ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ This corresponds to a specific example of the "third audible sound wave" according to one embodiment of the present disclosure. Ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ This corresponds to one specific example of the "ninth ultrasonic wave" according to one embodiment of the present disclosure.

[0061] The "fourth sound wave" is an ultrasonic wave (-nW) that can be generated from the MEMS vibration unit 422a. ＤＳＢ_i ) and ultrasonic waves (-mW) that can be generated from the MEMS vibration unit 422b ｃａｒｒｉｅｒ_i ) and ultrasound (-nW ＤＳＢ_i ) and ultrasound (-mW) ｃａｒｒｉｅｒ_i Sound waves lW generated by mutual interference in space with ) ｃａｒｒｉｅｒ_i W ＤＳＢ_i This includes ultrasound (-nW). ＤＳＢ_i ) is a modulated ultrasonic signal (-V ＤＳＢ_i ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "eleventh ultrasonic wave" according to one embodiment of the present disclosure. Ultrasonic wave (-mW) ｃａｒｒｉｅｒ_i ) is the carrier signal (-V ｃａｒｒｉｅｒ_i ) frequency ω ｃ The corresponding frequency ω ｃ This is an ultrasonic wave, and corresponds to a specific example of the "10th ultrasonic wave" according to one embodiment of the present disclosure. ｃａｒｒｉｅｒ_i W ＤＳＢ_i Ultrasound (-mW) ｃａｒｒｉｅｒ_i ) and ultrasound (-nW ＤＳＢ_i Audible sound waves lW are generated by the mutual interference in space with ) ｓｏｕｎｄ and two types of ultrasound (-1W) ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２) includes audible sound waves lW ｓｏｕｎｄ This corresponds to one specific example of the "fourth audible sound wave" according to one embodiment of the present disclosure. Ultrasound (-1W) ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ This corresponds to a specific example of the "12th ultrasonic wave" according to one embodiment of the present disclosure.

[0062] Here, W ｓｏｕｎｄ , W ｃａｒｒｉｅｒ_q , W ｃａｒｒｉｅｒ_i , W ＤＳＢ_q , W ＤＳＢ_i However, let it be expressed by the above equations (8), (9), (10), (11), and (12).

[0063] The sound wave output circuit 420 reacts to the mutual interference of the third sound wave and the fourth sound wave in the external space ES, causing ultrasonic waves (+1W) generated from the MEMS circuit 421 to be emitted. ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) and ultrasonic waves (-1W) generated from the MEMS circuit 422 ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ ) and mutually cancel each other out, and the audible sound waves (2 × lW) generated from the MEMS circuits 421 and 422 ｓｏｕｎｄ ) and ultrasound (-mW) ｃａｒｒｉｅｒ_q , -nW ＤＳＢ_q -mW ｃａｒｒｉｅｒ_i , -nW ＤＳＢ_i It is possible to output mainly ultrasonic waves (+1W) generated from the MEMS circuit 421. ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) and ultrasonic waves (-1W) generated from the MEMS circuit 422 ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ If the two cancel each other out, the sound wave output circuit 420 outputs an audible sound wave (2 × lW). ｓｏｕｎｄ ) and ultrasound (-mW) ｃａｒｒｉｅｒ_q , -nW ＤＳＢ_q -mW ｃａｒｒｉｅｒ_i , -nW ＤＳＢ_i It is possible to output only ).

[0064] Sound waves (lW) ｃａｒｒｉｅｒ_q W ＤＳＢ_q ) is an audible sound wave lW generated from the MEMS circuit 421. ｓｏｕｎｄ and ultrasound (+1W) ｃａｒｒｉｅｒ１ , + lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lWｓｏｕｎｄ is (1 / 8) lW ｓ W ｃ {2e ｊωｓｔ +2e －ｊωｓｔ It is represented as}. Ultrasound (+lW ｃａｒｒｉｅｒ１ ) is (1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc+ωs)t+e-j(2ωc+ωs)t}. Ultrasound (+lW) ｃａｒｒｉｅｒ２ ) is (1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc-ωs)t + e-j(2ωc-ωs)t}. Therefore, the sound wave (lW) ｃａｒｒｉｅｒ_q W ＤＳＢ_q ) is expressed by equation (13).

[0065] Sound waves (lW) ｃａｒｒｉｅｒ_i W ＤＳＢ_i ) is an audible sound wave lW generated from the MEMS circuit 422. ｓｏｕｎｄ and ultrasound (-1W) ｃａｒｒｉｅｒ１ , -lW ｃａｒｒｉｅｒ２ ) includes audible sound waves lW ｓｏｕｎｄ is (1 / 8) lW ｓ W ｃ {2e ｊωｓｔ +2e －ｊωｓｔ It is represented as}. Ultrasound (-lW ｃａｒｒｉｅｒ１ ) is -(1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc+ωs)t+e-j(2ωc+ωs)t}. Ultrasound (-lW) ｃａｒｒｉｅｒ２ ) is -(1 / 8)lW ｓ W ｃ It is expressed as {ej(2ωc-ωs)t + e-j(2ωc-ωs)t}. Therefore, the sound wave (lW) ｃａｒｒｉｅｒ_i W ＤＳＢ_i ) is expressed by equation (14).

[0066] From equations (13) and (14), lW ｃａｒｒｉｅｒ_q W ＤＳＢ_q +lW ｃａｒｒｉｅｒ_i W ＤＳＢ_i This is expressed by equation (15). Therefore, ultrasonic waves near 2ωc are attenuated or canceled out. Consequently, the sound wave output circuits 320 and 420 are equal to the sound wave (2 × lW). ｃａｒｒｉｅｒ_q W ＤＳＢ_q +2 × lW ｃａｒｒｉｅｒ_i WＤＳＢ_i ) only, that is, audible sound waves (lWsWc(e ｊωｓｔ +e －ｊωｓｔ It is possible to output only (Equations (16), (17)).

[0067] [Effects] Next, the effects of the sound wave generator 400 will be explained.

[0068] In this embodiment, the carrier signal (+V ｃａｒｒｉｅｒ_q ) and modulated ultrasonic signal (+V ＤＳＢ_q The first sound wave is generated by vibrating two MEMS vibrators 321a and 321b using the carrier signal (+V). ｃａｒｒｉｅｒ_q A carrier signal (+V) whose phase is shifted by 90 degrees relative to the phase of ) ｃａｒｒｉｅｒ_i ) and modulated ultrasonic signal (+V ＤＳＢ_i By vibrating multiple second MEMS vibrators using ), a second sound wave capable of interfering with the first sound wave in space is generated. Furthermore, the carrier signal (+V ｃａｒｒｉｅｒ_q The carrier signal (-V) which is in the opposite phase of ) ｃａｒｒｉｅｒ_q ) and modulated ultrasonic signal (-V ＤＳＢ_q By vibrating the two MEMS vibrators 421a and 421b using the above, a third sound wave is generated that can interfere with the first and second sound waves in space. Furthermore, the carrier signal (+V ｃａｒｒｉｅｒ_i ) modulated ultrasonic signal with inverse phase (-V ｃａｒｒｉｅｒ_i ) and modulated ultrasonic signal (-V ＤＳＢ_i By vibrating the two MEMS vibrating sections 422a and 422b, a fourth sound wave is generated that can interfere with the first, second, and third sound waves in space. The mutual interference of the first, second, third, and fourth sound waves in space generates ultrasonic waves (+mW) from the MEMS circuit 321. ｃａｒｒｉｅｒ_q , +nW ＤＳＢ_q ) and ultrasonic waves (+mW) generated from the MEMS circuit 322 ｃａｒｒｉｅｒ_i , +nW ＤＳＢ_i ) and ultrasonic waves (-mW) generated from the MEMS vibration unit 421 ｃａｒｒｉｅｒ_q , -nW ＤＳＢ_q ) and ultrasonic waves (-mW) generated from the MEMS vibration unit 422 ｃａｒｒｉｅｒ_i, -nW ＤＳＢ_i ) are mutually canceling each other out, and the audible sound wave lW generated from the MEMS circuit 321 ｓｏｕｎｄ , audible sound wave lW generated from MEMS circuit 322 ｓｏｕｎｄ , audible sound waves lW generated from the MEMS vibration unit 421 ｓｏｕｎｄ , and the audible sound wave lW generated from the MEMS vibration unit 422 ｓｏｕｎｄ A synthesized sound wave is output. Thus, in this disclosure, the ultrasonic waves (+mW) generated from the MEMS circuit 321 are output. ｃａｒｒｉｅｒ_q , +nW ＤＳＢ_q ) and ultrasonic waves (+mW) generated from the MEMS circuit 322 ｃａｒｒｉｅｒ_i , +nW ＤＳＢ_i ) and ultrasonic waves (-mW) generated from the MEMS vibration unit 421 ｃａｒｒｉｅｒ_q , -nW ＤＳＢ_q ) and ultrasonic waves (-mW) generated from the MEMS vibration unit 422 ｃａｒｒｉｅｒ_i , -nW ＤＳＢ_i The effects of ultrasound are mutually neutralized. As a result, the impact of ultrasound on the human body can be reduced.

[0069] In this embodiment, an eight-phase configuration with 45-degree intervals may be created by adding four more phases to the configuration of four ultrasonic signal sources 312, 313, 412, 413 (0 degrees, 90 degrees, 180 degrees, 270 degrees), or a multi-phase configuration based on a similar concept may be created. Even in this case, the same effects as in the above embodiment can be obtained.

[0070] In this embodiment, the audible sound wave signal source 411 may also be used as the audible sound wave signal source 311. Even in this case, the same effects as in the above embodiment can be obtained.

[0071] Although this disclosure has been described with reference to several embodiments, this disclosure is not limited to the embodiments described above, and various modifications are possible. Furthermore, the effects described herein are merely illustrative. The effects of this disclosure are not limited to those described herein. This disclosure may have effects other than those described herein.

[0072] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

[0073] Furthermore, for example, this disclosure can take the following configuration. (1) A sound wave generator comprising an electrical signal circuit and a sound wave output circuit, wherein the electrical signal circuit includes a first signal source capable of generating a first voltage signal with a frequency in the audible range, a second signal source capable of generating a second voltage signal with a frequency in the ultrasonic range, a third signal source capable of generating a third voltage signal with the opposite phase to the second voltage signal, a first modulator capable of generating a fourth voltage signal by amplitude modulating the second voltage signal with the first voltage signal, and a second modulator capable of generating a fifth voltage signal by amplitude modulating the third voltage signal with the first voltage signal, and the sound wave output circuit includes a first MEMS circuit capable of generating a first sound wave by vibrating a plurality of first MEMS vibrating parts with the second voltage signal and the fourth voltage signal, and a second MEMS circuit capable of generating a second sound wave capable of interfering with the first sound wave in space by vibrating a plurality of second MEMS vibrating parts with the third voltage signal and the fifth voltage signal. (2) The first MEMS circuit is capable of outputting, as the first sound wave, a first ultrasonic wave having a frequency corresponding to the frequency of the second voltage signal, a second ultrasonic wave having a frequency corresponding to the frequency of the fourth voltage signal, and a first audible sound wave and a third ultrasonic wave generated by the spatial mutual interference of the first ultrasonic wave and the second ultrasonic wave; the second MEMS circuit is capable of outputting, as the second sound wave, a fourth ultrasonic wave having a frequency corresponding to the frequency of the third voltage signal, a fifth ultrasonic wave having a frequency corresponding to the frequency of the fifth voltage signal, and a second audible sound wave and a sixth ultrasonic wave generated by the spatial mutual interference of the fourth ultrasonic wave and the fifth ultrasonic wave; the sound wave output circuit is capable of canceling out the first ultrasonic wave and the fourth ultrasonic wave, canceling out the second ultrasonic wave and the fifth ultrasonic wave, and outputting a composite sound wave of the first audible sound wave and the second audible sound wave, and the third ultrasonic wave and the sixth ultrasonic wave. The sound wave generator according to (1).(3) A device comprising an electrical signal circuit and a sound wave output circuit, wherein the electrical signal circuit includes a first signal source capable of generating a first voltage signal with a frequency in the audible range, a second signal source capable of generating a second voltage signal with a frequency in the ultrasonic range, a third signal source capable of generating a third voltage signal with a phase shifted by 90 degrees with respect to the phase of the second voltage signal, a first modulator capable of generating a fourth voltage signal by amplitude modulating the second voltage signal with the first voltage signal, and a second modulator capable of generating a fifth voltage signal by amplitude modulating the third voltage signal with the first voltage signal, and the sound wave output circuit includes a first MEMS circuit capable of generating a first sound wave by vibrating a plurality of first MEMS vibrating parts with the second voltage signal and the fourth voltage signal, A sound wave generating device having a second MEMS circuit capable of generating a second sound wave that can interfere with the first sound wave in space by vibrating a plurality of second MEMS vibrating parts with the third voltage signal and the fifth voltage signal. (4) The first MEMS circuit is capable of outputting, as the first sound wave, a first ultrasonic wave having a frequency corresponding to the frequency of the second voltage signal, a second ultrasonic wave having a frequency corresponding to the frequency of the fourth voltage signal, and a first audible sound wave and a third ultrasonic wave generated by the spatial mutual interference of the first ultrasonic wave and the second ultrasonic wave; the second MEMS circuit is capable of outputting, as the second sound wave, a fourth ultrasonic wave having a frequency corresponding to the frequency of the third voltage signal, a fifth ultrasonic wave having a frequency corresponding to the frequency of the fifth voltage signal, and a second audible sound wave and a sixth ultrasonic wave generated by the spatial mutual interference of the fourth ultrasonic wave and the fifth ultrasonic wave; the sound wave output circuit is capable of canceling out the third ultrasonic wave and the sixth ultrasonic wave by the spatial mutual interference of the first sound wave and the second sound wave, and outputting a composite sound wave of the first audible sound wave and the second audible sound wave, and the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave and the fifth ultrasonic wave. The sound wave generator according to (3).(5) A device comprising an electrical signal circuit and a sound wave output circuit, wherein the electrical signal circuit includes: a first signal source capable of generating a first voltage signal with a frequency in the audible range; a second signal source capable of generating a second voltage signal with a frequency in the ultrasonic range; a third signal source capable of generating a third voltage signal with a phase shifted by 90 degrees with respect to the phase of the second voltage signal; a fourth signal source capable of generating a fourth voltage signal with the opposite phase to the second voltage signal; a fifth signal source capable of generating a fifth voltage signal with the opposite phase to the third voltage signal; a first modulator capable of generating a sixth voltage signal by amplitude modulating the second voltage signal with the first voltage signal; a second modulator capable of generating a seventh voltage signal by amplitude modulating the third voltage signal with the first voltage signal; a third modulator capable of generating an eighth voltage signal by amplitude modulating the fourth voltage signal with the first voltage signal; and a fourth modulator capable of generating a ninth voltage signal by amplitude modulating the fifth voltage signal with the first voltage signal. The sound wave output circuit is a sound wave generator comprising: a first MEMS circuit capable of generating a first sound wave by vibrating a plurality of first MEMS vibrating parts with the second voltage signal and the sixth voltage signal; a second MEMS circuit capable of generating a second sound wave capable of interfering with the first sound wave in space by vibrating a plurality of second MEMS vibrating parts with the third voltage signal and the seventh voltage signal; a third MEMS circuit capable of generating a third sound wave capable of interfering with the first sound wave and the second sound wave in space by vibrating a plurality of third MEMS vibrating parts with the fourth voltage signal and the eighth voltage signal; and a fourth MEMS circuit capable of generating a fourth sound wave capable of interfering with the first sound wave, the second sound wave and the third sound wave in space by vibrating a plurality of fourth MEMS vibrating parts with the fifth voltage signal and the ninth voltage signal.(6) The first MEMS circuit is capable of outputting, as the first sound wave, a first ultrasonic wave with a frequency corresponding to the frequency of the second voltage signal, a second ultrasonic wave with a frequency corresponding to the frequency of the sixth voltage signal, and a first audible sound wave and a third ultrasonic wave generated by the spatial mutual interference of the first ultrasonic wave and the second ultrasonic wave; The second MEMS circuit is capable of outputting, as the second sound wave, a fourth ultrasonic wave with a frequency corresponding to the frequency of the third voltage signal, a fifth ultrasonic wave with a frequency corresponding to the frequency of the seventh voltage signal, and a second audible sound wave and a sixth ultrasonic wave generated by the spatial mutual interference of the fourth ultrasonic wave and the fifth ultrasonic wave; The third MEMS circuit is capable of outputting, as the third sound wave, a seventh ultrasonic wave with a frequency corresponding to the frequency of the fourth voltage signal, an eighth ultrasonic wave with a frequency corresponding to the frequency of the eighth voltage signal, and a third audible sound wave and a ninth ultrasonic wave generated by the spatial mutual interference of the seventh ultrasonic wave and the eighth ultrasonic wave; The fourth MEMS circuit is capable of outputting, as the fourth sound wave, a tenth ultrasonic wave having a frequency corresponding to the frequency of the fifth voltage signal, an eleventh ultrasonic wave having a frequency corresponding to the frequency of the ninth voltage signal, and a fourth audible sound wave and a twelfth ultrasonic wave generated by the spatial mutual interference of the tenth ultrasonic wave and the eleventh ultrasonic wave, and the sound wave output circuit is capable of outputting a composite sound wave of the first audible sound wave, the second audible sound wave, the third audible sound wave and the twelfth ultrasonic wave by the spatial mutual interference of the first sound wave, the second sound wave, the third sound wave and the fourth sound wave, canceling out the first ultrasonic wave and the seventh ultrasonic wave, canceling out the second ultrasonic wave and the eighth ultrasonic wave, canceling out the third ultrasonic wave and the ninth ultrasonic wave, canceling out the fourth ultrasonic wave and the tenth ultrasonic wave, canceling out the fifth ultrasonic wave and the eleventh ultrasonic wave and canceling out the sixth ultrasonic wave and the twelfth ultrasonic wave, and a composite sound wave of the first audible sound wave, the second audible sound wave, the third audible sound wave and the fourth audible sound wave as described in (5).

[0074] In the sound wave generator according to the first aspect of this disclosure, a first sound wave is generated by vibrating a plurality of first MEMS vibrators with a second voltage signal having a frequency in the ultrasonic range and a fourth voltage signal obtained by amplitude modulation of the second voltage signal by the first voltage signal having a frequency in the audible range. Furthermore, a second sound wave capable of interfering with the first sound wave in space is generated by vibrating a plurality of second MEMS vibrators with a third voltage signal having the opposite phase to the second voltage signal and a fifth voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal. Due to the mutual interference between the first and second sound waves in space, the ultrasonic waves contained in the first sound wave and the ultrasonic waves contained in the second sound wave are attenuated from each other, and a composite sound wave of the audible sound waves contained in the first sound wave and the audible sound waves contained in the second sound wave is output. In this way, in this disclosure, the ultrasonic waves contained in the first sound wave and the ultrasonic waves contained in the second sound wave are attenuated from each other. As a result, the effects of ultrasound on the human body can be reduced.

[0075] In the sound wave generator according to the second aspect of this disclosure, a first sound wave is generated by vibrating a plurality of first MEMS vibrators with a second voltage signal having a frequency in the ultrasonic range and a fourth voltage signal obtained by amplitude modulation of the second voltage signal by a first voltage signal having a frequency in the audible range. Furthermore, a second sound wave capable of interfering with the first sound wave in space is generated by vibrating a plurality of second MEMS vibrators with a third voltage signal having a phase shifted by 90 degrees with respect to the phase of the second voltage signal and a fifth voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal. Due to the mutual interference between the first and second sound waves in space, the ultrasonic waves contained in the first sound wave and the ultrasonic waves contained in the second sound wave are attenuated from each other, and a composite sound wave of the audible sound waves contained in the first sound wave and the audible sound waves contained in the second sound wave is output. In this way, in this disclosure, the ultrasonic waves contained in the first sound wave and the ultrasonic waves contained in the second sound wave are attenuated from each other. As a result, the effects of ultrasound on the human body can be reduced.

[0076] In the sound wave generator relating to the third aspect of this disclosure, a first sound wave is generated by vibrating a plurality of first MEMS vibrators with a second voltage signal having a frequency in the ultrasonic range and a sixth voltage signal obtained by amplitude modulation of the second voltage signal by a first voltage signal having a frequency in the audible range. Furthermore, a second sound wave capable of interfering with the first sound wave in space is generated by vibrating a plurality of second MEMS vibrators with a third voltage signal having a phase shifted by 90 degrees with respect to the phase of the second voltage signal and a seventh voltage signal obtained by amplitude modulation of the third voltage signal by the first voltage signal. Furthermore, a third sound wave capable of interfering with the first and second sound waves in space is generated by vibrating a plurality of third MEMS vibrators with a fourth voltage signal having the opposite phase to the second voltage signal and an eighth voltage signal obtained by amplitude modulation of the fourth voltage signal by the first voltage signal. Furthermore, by vibrating multiple fourth MEMS vibrators with a fifth voltage signal that is in the opposite phase to the third voltage signal and a ninth voltage signal obtained by amplitude modulation of the fifth voltage signal by the first voltage signal, a fourth sound wave capable of interfering with the first, second, and third sound waves in space is generated. Due to the mutual interference of the first, second, third, and fourth sound waves in space, the ultrasound contained in the first sound wave, the ultrasound contained in the second sound wave, the ultrasound contained in the third sound wave, and the ultrasound contained in the fourth sound wave are attenuated from each other, and a composite sound wave of the audible sound wave contained in the first sound wave, the audible sound wave contained in the second sound wave, the audible sound wave contained in the third sound wave, and the composite sound wave of the audible sound wave contained in the fourth sound wave is output. In this way, in this disclosure, the ultrasound contained in the first sound wave, the ultrasound contained in the second sound wave, the ultrasound contained in the third sound wave, and the ultrasound contained in the fourth sound wave are attenuated from each other. As a result, the effects of ultrasound on the human body can be reduced.

[0077] This application claims priority based on Japanese Patent Application No. 2024-227675, filed with the Japan Patent Office on 24 December 2024, and all contents of that application are incorporated herein by reference.

[0078] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. The device comprises an electrical signal circuit and a sound wave output circuit, the electrical signal circuit having a first signal source capable of generating a first voltage signal with a frequency in the audible range, a second signal source capable of generating a second voltage signal with a frequency in the ultrasonic range, a third signal source capable of generating a third voltage signal with the opposite phase to the second voltage signal, a first modulator capable of generating a fourth voltage signal by amplitude modulating the second voltage signal with the first voltage signal, and a second modulator capable of generating a fifth voltage signal by amplitude modulating the third voltage signal with the first voltage signal, the sound wave output circuit having a first MEMS circuit capable of generating a first sound wave by vibrating a plurality of first MEMS (Micro Electro Mechanical Systems) vibrating parts with the second voltage signal and the fourth voltage signal, A sound wave generating device having a second MEMS circuit capable of generating a second sound wave that can interfere with the first sound wave in space by vibrating a plurality of second MEMS vibrating parts with the third voltage signal and the fifth voltage signal.

2. The sound wave generator according to claim 1, wherein the first MEMS circuit is capable of outputting, as the first sound wave, a first ultrasonic wave having a frequency corresponding to the frequency of the second voltage signal, a second ultrasonic wave having a frequency corresponding to the frequency of the fourth voltage signal, and a first audible sound wave and a third ultrasonic wave generated by the spatial mutual interference of the first ultrasonic wave and the second ultrasonic wave; the second MEMS circuit is capable of outputting, as the second sound wave, a fourth ultrasonic wave having a frequency corresponding to the frequency of the third voltage signal, a fifth ultrasonic wave having a frequency corresponding to the frequency of the fifth voltage signal, and a second audible sound wave and a sixth ultrasonic wave generated by the spatial mutual interference of the fourth ultrasonic wave and the fifth ultrasonic wave; and the sound wave output circuit is capable of canceling out the first ultrasonic wave and the fourth ultrasonic wave, canceling out the second ultrasonic wave and the fifth ultrasonic wave, and outputting a composite sound wave of the first audible sound wave and the second audible sound wave, and the third ultrasonic wave and the sixth ultrasonic wave.

3. The device comprises an electrical signal circuit and a sound wave output circuit, the electrical signal circuit having a first signal source capable of generating a first voltage signal with a frequency in the audible range, a second signal source capable of generating a second voltage signal with a frequency in the ultrasonic range, a third signal source capable of generating a third voltage signal with a phase shifted by 90 degrees with respect to the phase of the second voltage signal, a first modulator capable of generating a fourth voltage signal by amplitude modulating the second voltage signal with the first voltage signal, and a second modulator capable of generating a fifth voltage signal by amplitude modulating the third voltage signal with the first voltage signal, the sound wave output circuit having a first MEMS circuit capable of generating a first sound wave by vibrating a plurality of first MEMS (Micro Electro Mechanical Systems) vibrating parts with the second voltage signal and the fourth voltage signal, A sound wave generating device having a second MEMS circuit capable of generating a second sound wave that can interfere with the first sound wave in space by vibrating a plurality of second MEMS vibrating parts with the third voltage signal and the fifth voltage signal.

4. The sound wave generator according to claim 3, wherein the first MEMS circuit is capable of outputting, as the first sound wave, a first ultrasonic wave having a frequency corresponding to the frequency of the second voltage signal, a second ultrasonic wave having a frequency corresponding to the frequency of the fourth voltage signal, and a first audible sound wave and a third ultrasonic wave generated by the spatial mutual interference of the first ultrasonic wave and the second ultrasonic wave; the second MEMS circuit is capable of outputting, as the second sound wave, a fourth ultrasonic wave having a frequency corresponding to the frequency of the third voltage signal, a fifth ultrasonic wave having a frequency corresponding to the frequency of the fifth voltage signal, and a second audible sound wave and a sixth ultrasonic wave generated by the spatial mutual interference of the fourth ultrasonic wave and the fifth ultrasonic wave; and the sound wave output circuit is capable of canceling out the third ultrasonic wave and the sixth ultrasonic wave by the spatial mutual interference of the first sound wave and the second sound wave, and outputting a composite sound wave of the first audible sound wave and the second audible sound wave, and the first ultrasonic wave, the second ultrasonic wave, the fourth ultrasonic wave and the fifth ultrasonic wave.

5. The device comprises an electrical signal circuit and a sound wave output circuit, the electrical signal circuit having: a first signal source capable of generating a first voltage signal with a frequency in the audible range; a second signal source capable of generating a second voltage signal with a frequency in the ultrasonic range; a third signal source capable of generating a third voltage signal with a phase shifted by 90 degrees with respect to the phase of the second voltage signal; a fourth signal source capable of generating a fourth voltage signal with the opposite phase to the second voltage signal; a fifth signal source capable of generating a fifth voltage signal with the opposite phase to the third voltage signal; a first modulator capable of generating a sixth voltage signal by amplitude modulating the second voltage signal with the first voltage signal; a second modulator capable of generating a seventh voltage signal by amplitude modulating the third voltage signal with the first voltage signal; a third modulator capable of generating an eighth voltage signal by amplitude modulating the fourth voltage signal with the first voltage signal; and a fourth modulator capable of generating a ninth voltage signal by amplitude modulating the fifth voltage signal with the first voltage signal. The sound wave output circuit is a sound wave generator comprising: a first MEMS circuit capable of generating a first sound wave by vibrating a plurality of first MEMS (Micro Electro Mechanical Systems) vibrating parts with the second voltage signal and the sixth voltage signal; a second MEMS circuit capable of generating a second sound wave capable of interfering with the first sound wave in space by vibrating a plurality of second MEMS vibrating parts with the third voltage signal and the seventh voltage signal; a third MEMS circuit capable of generating a third sound wave capable of interfering with the first sound wave and the second sound wave in space by vibrating a plurality of third MEMS vibrating parts with the fourth voltage signal and the eighth voltage signal; and a fourth MEMS circuit capable of generating a fourth sound wave capable of interfering with the first sound wave, the second sound wave and the third sound wave in space by vibrating a plurality of fourth MEMS vibrating parts with the fifth voltage signal and the ninth voltage signal.

6. The first MEMS circuit is capable of outputting, as the first sound wave, a first ultrasonic wave with a frequency corresponding to the frequency of the second voltage signal, a second ultrasonic wave with a frequency corresponding to the frequency of the sixth voltage signal, and a first audible sound wave and a third ultrasonic wave generated by the spatial mutual interference of the first ultrasonic wave and the second ultrasonic wave; the second MEMS circuit is capable of outputting, as the second sound wave, a fourth ultrasonic wave with a frequency corresponding to the frequency of the third voltage signal, a fifth ultrasonic wave with a frequency corresponding to the frequency of the seventh voltage signal, and a second audible sound wave and a sixth ultrasonic wave generated by the spatial mutual interference of the fourth ultrasonic wave and the fifth ultrasonic wave; the third MEMS circuit is capable of outputting, as the third sound wave, a seventh ultrasonic wave with a frequency corresponding to the frequency of the fourth voltage signal, an eighth ultrasonic wave with a frequency corresponding to the frequency of the eighth voltage signal, and a third audible sound wave and a ninth ultrasonic wave generated by the spatial mutual interference of the seventh ultrasonic wave and the eighth ultrasonic wave; The sound wave generator according to claim 5, wherein the fourth MEMS circuit is capable of outputting, as the fourth sound wave, a tenth ultrasonic wave having a frequency corresponding to the frequency of the fifth voltage signal, an eleventh ultrasonic wave having a frequency corresponding to the frequency of the ninth voltage signal, and a fourth audible sound wave and a twelfth ultrasonic wave generated by the spatial mutual interference of the tenth ultrasonic wave and the eleventh ultrasonic wave, and the sound wave output circuit is capable of outputting a composite sound wave of the first audible sound wave, the second audible sound wave, the third audible sound wave and the fourth audible sound wave by the spatial mutual interference of the first sound wave, the second sound wave, the third sound wave and the fourth sound wave, canceling out the first ultrasonic wave and the seventh ultrasonic wave, canceling out the second ultrasonic wave and the eighth ultrasonic wave, canceling out the third ultrasonic wave and the ninth ultrasonic wave, canceling out the fourth ultrasonic wave and the tenth ultrasonic wave, canceling out the fifth ultrasonic wave and the eleventh ultrasonic wave and canceling out the sixth ultrasonic wave and the twelfth ultrasonic wave.

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