Ultrasonic generator

Abstract

To provide an ultrasonic generator with which a hypersonic effect can be achieved easily.SOLUTION: An ultrasonic speaker 40 in an ultrasonic generator includes a first vibration part 71 having a first resonant frequency f1 and a second vibration part 72 having a second resonant frequency f2. When signals including the first resonant frequency and the second resonant frequency are input into the first vibration part 71 and the second vibration part 72, the first vibration part 71 and the second vibration part 72 generate an ultrasonic and irradiate a human with the generated ultrasonic. The first vibration part 71 and the second vibration part 72 vibrate to generate a difference sound wave at a difference sound frequency fd=|f1-f2| represented by an absolute value of a difference between first resonant frequency f1 and the second resonant frequency f2. The difference sound frequency fd is an audible sound frequency. A distance Lp from a first central axis O1 of the first vibration part 71 to a second central axis O2 of the second vibration part 72 is greater than a value λp obtained by dividing the speed of sound by the difference sound frequency fd.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic generator.

Background Art

[0002] Conventionally, as described in Patent Document 1, a multi-resonance ultrasonic transducer including a first resonance type unit actuator having a first resonance frequency and a second resonance type unit actuator having a second resonance frequency is known. In this multi-resonance ultrasonic transducer, two ultrasonic waves are generated, and a difference ultrasonic wave having a frequency that is the difference between the first resonance frequency and the second resonance frequency is generated by the parametric effect.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, when a human is irradiated with ultrasonic waves together with audible sound, a hyper-sonic effect that enhances the brain function of the human can be obtained. When using the multi-resonance ultrasonic transducer described in Patent Document 1 for ultrasonic irradiation to obtain the hyper-sonic effect, if the frequency of the difference ultrasonic wave is the frequency of the audible sound, in addition to the irradiated audible sound, the sound due to the difference ultrasonic wave can be heard by the human. At this time, the sound due to the difference ultrasonic wave becomes noise for the human. Therefore, since the human becomes uncomfortable, it is difficult to obtain the hyper-sonic effect.

[0005] An object of the present disclosure is to provide an ultrasonic generator that makes it easy to obtain the hyper-sonic effect.

Means for Solving the Problems

[0006] The invention described in claim 1 is an ultrasonic generator comprising: an audible sound irradiation unit (30) for irradiating a person with audible sound; an ultrasonic irradiation unit (40, 401) including a first vibrating unit (71) having a first resonant frequency (f1) and a second vibrating unit (72) having a second resonant frequency (f2); and a signal unit (38) for outputting a signal including the first resonant frequency and the second resonant frequency to the first vibrating unit and the second vibrating unit, wherein when a signal including the first resonant frequency and the second resonant frequency is input to the first vibrating unit and the second vibrating unit... The ultrasonic generator consists of a first vibrating section and a second vibrating section that vibrate to generate ultrasonic waves, which are then irradiated onto a person. The vibration of the first and second vibrating sections generates a difference sound wave with a difference tone frequency (fd), which is the absolute value of the difference between the first resonant frequency and the second resonant frequency. The difference tone frequency is considered to be the frequency of an audible sound. The distance (Lp) from the center (O1) of the first vibrating section to the center (O2) of the second vibrating section is greater than the value (λp) obtained by dividing the speed of sound (c) by the difference tone frequency.

[0007] Furthermore, the invention described in claim 4 is an ultrasonic generating device comprising: an audible sound irradiation unit (30) for irradiating a person with audible sound; a first ultrasonic irradiation unit (401) including a first vibrating unit having a first resonant frequency; a second vibrating unit having a second resonant frequency; and a first substrate (461) on which the first vibrating unit and the second vibrating unit are arranged; 5 The resonant frequency 5 The vibrating part and the first 6 The resonant frequency 6 The vibrating part and the first 5 Vibration section and 6 The second ultrasonic irradiation unit (402) includes a second substrate (462) on which a vibrating unit is located, and outputs signals including a first resonant frequency and a second resonant frequency to the first vibrating unit and the second vibrating unit, and 5 Resonant frequency and 6 The signal containing the resonant frequency 5 Vibration section and 6The device comprises a signal unit (38) that outputs to the vibrating unit, and when a signal including a first resonant frequency and a second resonant frequency is input to the first vibrating unit and the second vibrating unit, the first vibrating unit and the second vibrating unit vibrate to generate ultrasonic waves, and irradiate a person with the generated ultrasonic waves, and the frequency of the difference sound wave produced by the first vibrating unit and the second vibrating unit is outside the frequency range of audible sound, and the 5 Resonant frequency and 6 The signal containing the resonant frequency is 5 Vibration section and 6 When input is received in the vibration section, 5 Vibration section and 6 The vibrating part generates ultrasound by vibrating, and the generated ultrasound is irradiated onto a person. 5 Vibration section and 6 The frequency of the difference sound wave produced by the vibrating part is considered to be outside the frequency range of audible sound. , the A first vibrating section and a second vibrating section, and 5 Vibration section and 6 The frequency of the difference sound wave generated between the vibrating part includes the frequency of audible sound, the first substrate and the second substrate are aligned in one direction (D1), and the distance (Lsb) from one end of the first substrate to the other end of the second substrate in one direction is the speed of sound, within the frequency range of audible sound, and the first vibrating part and the second vibrating part are located on the first substrate and the second vibrating part is located on the second substrate. 5 Vibration section and 6 This ultrasonic generator has an ultrasonic frequency that is greater than the value obtained by dividing the frequency of the difference sound wave generated between the vibrating part and the minimum value (N) of that frequency.

[0008] Furthermore, the invention described in claim 5 is an ultrasonic generating device comprising: an audible sound irradiation unit (30) for irradiating a person with audible sound; a first ultrasonic irradiation unit (401) including a first vibrating unit having a first resonant frequency; a second vibrating unit having a second resonant frequency; and a first substrate (461) on which the first vibrating unit and the second vibrating unit are arranged; 5 The resonant frequency 5 The vibrating part and the first 6 The resonant frequency 6 The vibrating part and the first 5 Vibration section and 6The second ultrasonic irradiation unit (402) includes a second substrate (462) on which a vibrating unit is located, and outputs signals including a first resonant frequency and a second resonant frequency to the first vibrating unit and the second vibrating unit, and 5 Resonant frequency and 6 The signal containing the resonant frequency 5 Vibration section and 6 The device comprises a signal unit (38) that outputs to the vibrating unit, and when a signal including a first resonant frequency and a second resonant frequency is input to the first vibrating unit and the second vibrating unit, the first vibrating unit and the second vibrating unit vibrate to generate ultrasonic waves, and irradiate a person with the generated ultrasonic waves, and the frequency of the difference sound wave produced by the first vibrating unit and the second vibrating unit is outside the frequency range of audible sound, and the 5 Resonant frequency and 6 The signal containing the resonant frequency is 5 Vibration section and 6 When input is received in the vibration section, 5 Vibration section and 6 The vibrating part generates ultrasound by vibrating, and the generated ultrasound is irradiated onto a person. 5 Vibration section and 6 The frequency of the difference sound wave produced by the vibrating part is considered to be outside the frequency range of audible sound, and the first vibrating part and the second vibrating part 5 Vibration section and 6 The frequency of the difference sound wave generated between the vibrating part includes the frequency of audible sound, the first substrate and the second substrate are aligned in one direction (D1), and the distance (Lsb) from one end of the first substrate to the other end of the second substrate in one direction is the speed of sound, within the frequency range of audible sound, and the first vibrating part and the second vibrating part are located on the first substrate and the second vibrating part is located on the second substrate. 5 Vibration section and 6 This ultrasonic generator has a value greater than the value obtained by dividing the difference sound wave frequency generated between the vibrating part and the maximum value (N) of the difference sound wave frequency.

[0009] As a result, the vibrating parts that generate difference sound waves having the frequency of audible sound are relatively far apart from each other, so that a phase difference of ultrasonic waves that generate difference sound waves having the frequency of audible sound is likely to occur. For this reason, ultrasonic waves that generate difference sound waves having the frequency of audible sound are likely to weaken each other. Therefore, the sound pressure of the difference sound waves having the frequency of audible sound is likely to decrease. Thus, since the sound due to the difference sound waves is suppressed from becoming noise for humans, the discomfort of humans is suppressed. As a result, the hypersonic effect is likely to be obtained.

[0010] Note that the reference signs with parentheses attached to each component etc. show an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0011] [Figure 1] Configuration diagram of the ultrasonic wave generator of the first embodiment. [Figure 2] Top view of the ultrasonic speaker of the ultrasonic wave generator. [Figure 3] Cross-sectional view taken along line III-III of FIG. 2. [Figure 4] Relationship diagram between frequency and sound pressure in the ultrasonic wave generator. [Figure 5] Relationship diagram between the average value of the first peak value and the second peak value and the sound pressure of the difference sound wave. [Figure 6] Top view of the ultrasonic speaker of the ultrasonic wave generator of the second embodiment. [Figure 7] Relationship diagram between frequency and sound pressure in the ultrasonic wave generator. [Figure 8] Configuration diagram of the ultrasonic wave generator of the third embodiment. [Figure 9] Top view of the first ultrasonic speaker and the second ultrasonic speaker of the ultrasonic wave generator. [Figure 10] Cross-sectional view taken along line X-X of FIG. 9. [Figure 11] Relationship diagram between frequency and sound pressure in the ultrasonic wave generator. [Figure 12] Relationship diagram between frequency and sound pressure in the ultrasonic wave generator. [Figure 13] Configuration diagram of the ultrasonic generator according to the fourth embodiment. [Figure 14] Top view of the first and second ultrasonic speakers of the ultrasonic generator. [Figure 15] A diagram illustrating the relationship between frequency and sound pressure in an ultrasonic generator. [Modes for carrying out the invention]

[0012] The embodiments will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numeral, and their descriptions will be omitted.

[0013] (First Embodiment) The ultrasonic generator of this embodiment facilitates the acquisition of the hypersonic effect by irradiating a person with audible sound and ultrasound. Specifically, as shown in Figure 1, the ultrasonic generator 20 includes an audible recording medium 22, an audible signal generator 24, an audible playback circuit 26, an audible amplification circuit 28, and an audible speaker 30. The ultrasonic generator 20 also includes an ultrasonic recording medium 32, an ultrasonic signal generator 34, an ultrasonic playback circuit 36, an ultrasonic amplification circuit 38, and an ultrasonic speaker 40.

[0014] The audible recording medium 22 is, for example, ROM or flash memory, and stores digital information related to audible sound. The audible signal generator 24 is, for example, an optical drive or card reader, and reads the digital information related to audible sound stored in the audible recording medium 22. The audible playback circuit 26 is a DAC, and converts the digital information of audible sound read by the audible signal generator 24 into analog information. The audible amplification circuit 28 is an amplifier, and amplifies the signal corresponding to the analog information related to audible sound converted by the audible playback circuit 26. DAC stands for Digital-to-Analog Converter. Audible sound is defined as sound with a frequency between 20 Hz and 20 kHz.

[0015] The audible speaker 30 corresponds to the audible sound irradiation unit and generates audible sound amplified by the audible amplification circuit 28. In this way, the audible speaker 30 irradiates the human auditory system with audible sound.

[0016] The ultrasonic recording medium 32 is, for example, a ROM or flash memory, and stores digital information related to ultrasound. The ultrasonic signal generator 34 is, for example, an optical drive or card reader, and reads the digital information related to ultrasound stored in the ultrasonic recording medium 32. The ultrasonic playback circuit 36 ​​is a DAC, and converts the digital information related to ultrasound read by the ultrasonic signal generator 34 into analog information. The ultrasonic amplification circuit 38 corresponds to the signal section, and is an amplifier that amplifies the signal corresponding to the analog information related to ultrasound converted by the ultrasonic playback circuit 36. Note that ultrasound is a sound with a frequency higher than 20 kHz.

[0017] The ultrasonic speaker 40 corresponds to the ultrasonic irradiation unit and, for example, by being equipped with a PMUT, generates ultrasonic waves amplified by the ultrasonic amplification circuit 38. This allows the ultrasonic speaker 40 to irradiate humans with ultrasonic waves. PMUT stands for Piezoelectric Micromachined Ultrasonic Transducer.

[0018] Specifically, as shown in Figures 2 and 3, the ultrasonic speaker 40 comprises a case 42, a bonding member 44, a semiconductor substrate 46, an insulating film 48, a semiconductor film 50, a first piezoelectric film 51, a first electrode 61, a second piezoelectric film 52, a second electrode 62, a first vibrating section 71, and a second vibrating section 72.

[0019] The case 42 is formed in a box shape from resin, ceramics, or the like. The case 42 also houses the joining member 44, semiconductor substrate 46, insulating film 48, semiconductor film 50, first piezoelectric film 51, first electrode 61, second piezoelectric film 52, second electrode 62, first vibrating part 71, and second vibrating part 72, which will be described later. Furthermore, a housing (not shown) that houses the case 42 is attached, for example, to a desk or wall (not shown).

[0020] The bonding member 44 is, for example, a silicone-based adhesive. Multiple bonding members 44 are arranged at predetermined intervals at the bottom of the case 42 in one direction D1 perpendicular to the thickness direction DT of the semiconductor substrate 46, which will be described later. Furthermore, multiple bonding members 44 are arranged at predetermined intervals at the bottom of the case 42 in a direction perpendicular to both the one direction D1 and the thickness direction DT.

[0021] The semiconductor substrate 46 is formed, for example, in a rectangular shape from silicon or the like. The length of the semiconductor substrate 46 in the direction perpendicular to the thickness direction DT is, for example, 5.0 to 15.0 mm. Furthermore, the semiconductor substrate 46 has a substrate surface 465, a substrate back surface 467, a first space 471, a second space 472, and a support portion 475.

[0022] The substrate surface 465 is the side of the semiconductor substrate 46 opposite to the bonding member 44. The substrate back surface 467 is the side of the semiconductor substrate 46 facing the bonding member 44. The substrate back surface 467 is also bonded to the bonding member 44. This forms an air inflow / outflow space 477, which is partitioned by the substrate back surface 467, the bonding member 44, and the bottom of the case 42. Air flows in and out of the case 42 through the air inflow / outflow space 477.

[0023] The first space 471 is a hole space that penetrates the substrate surface 465 and the substrate back surface 467. The first space 471 is also in communication with the air inlet / outlet space 477. Furthermore, the first space 471 is formed in a cylindrical shape having an axis extending in the thickness direction DT, for example, by etching. The radius of the first space 471 is, for example, 0.1 to 2.0 mm. Furthermore, the length of the first space 471 in the thickness direction DT is, for example, 0.1 to 1.0 mm.

[0024] The second space 472 is positioned at a predetermined distance from the first space 471 in one direction D1, and is a space of holes that penetrate the substrate surface 465 and the substrate back surface 467. The second space 472 is also in communication with the air inlet / outlet space 477. Furthermore, the second space 472 is formed in a cylindrical shape having an axis extending in the thickness direction DT, for example, by etching. The radius of the second space 472 is, for example, 0.1 to 2.0 mm. Furthermore, the length of the second space 472 in the thickness direction DT is, for example, 0.1 to 1.0 mm.

[0025] The support portion 475 is the part of the semiconductor substrate 46 adjacent to the first space 471. Furthermore, the support portion 475 is the part of the semiconductor substrate 46 adjacent to the second space 472. In addition, the length of the support portion 475 in the thickness direction DT is, for example, 0.1 to 1.0 mm.

[0026] The insulating film 48 is formed of an oxide film, a nitride film, or the like, and therefore has electrical insulating properties. For example, the insulating film 48 is formed of silicon oxide. The length of the insulating film 48 in the thickness direction DT is, for example, 1.0 to 10.0 μm. Furthermore, since the insulating film 48 is formed on the substrate surface 465, it closes the first space 471 and the second space 472 and is supported by the support portion 475.

[0027] The semiconductor film 50 is conductive, for example, due to the doping of a silicon film with p-type impurities. The semiconductor film 50 is formed on an insulating film 48. Furthermore, the length of the semiconductor film 50 in the thickness direction DT is set to 10.0 to 30.0 μm. The semiconductor film 50 is connected to the ultrasonic amplification circuit 38 via bonding wires, pads, connection terminals, etc. (not shown). Here, the semiconductor film 50 is given as an example of a conductive film formed on the insulating film 48, but it is not limited to this. The conductive film formed on the insulating film 48 may be, for example, a film formed from an electrode material such as a titanium-aluminum alloy.

[0028] The first piezoelectric film 51 is formed from an aluminum nitride-based material such as scandium aluminum nitride, or a piezoelectric material such as lead titanium zirconate or zinc oxide. Furthermore, the first piezoelectric film 51 is formed on the portion of the semiconductor film 50 that overlaps with the first space 471 in the thickness direction DT by sputtering or the like. In addition, the first piezoelectric film 51 is formed in a cylindrical shape, for example, having an axis extending in the thickness direction DT. The length of the first piezoelectric film 51 in the thickness direction DT is, for example, 0.5 to 2.0 μm. Furthermore, the axis of the first piezoelectric film 51 coincides with the axis of the first space 471. Here, "coincidence" includes the manufacturing tolerance range.

[0029] The first electrode 61 is made of an electrode material such as a titanium-aluminum alloy and is therefore conductive. The first electrode 61 is formed on the first piezoelectric film 51 by sputtering or vapor deposition. Furthermore, the length of the first electrode 61 in the thickness direction DT is, for example, 100 to 500 nm. The first electrode 61 is connected to the ultrasonic amplification circuit 38 via bonding wires, pads, connection terminals, etc. (not shown).

[0030] The second piezoelectric film 52, like the first piezoelectric film 51, is formed from an aluminum nitride-based material such as scandium aluminum nitride, or a piezoelectric material such as lead titanium zirconate or zinc oxide. Furthermore, the second piezoelectric film 52 is formed by sputtering or the like on the portion of the semiconductor film 50 that overlaps with the second space 472 in the thickness direction DT. The second piezoelectric film 52 is also formed in a cylindrical shape with an axis extending in the thickness direction DT. The length of the second piezoelectric film 52 in the thickness direction DT is, for example, 0.5 to 2.0 μm. Moreover, the axis of the second piezoelectric film 52 coincides with the axis of the second space 472.

[0031] The second electrode 62, like the first electrode 61, is formed from an electrode material such as a titanium-aluminum alloy. The second electrode 62 is formed on the second piezoelectric film 52 by sputtering or vapor deposition. Furthermore, the length of the second electrode 62 in the thickness direction DT is, for example, 100 to 500 nm. The second electrode 62 is connected to the ultrasonic amplification circuit 38 via bonding wires, pads, connection terminals, etc. (not shown).

[0032] The first vibrating section 71 is composed of a first space 471, a portion of the insulating film 48 that overlaps with the first space 471 in the thickness direction DT, a portion of the semiconductor film 50 that overlaps with the first space 471 in the thickness direction DT, the first piezoelectric film 51, and the first electrode 61. When a signal from the ultrasonic amplification circuit 38 is input to the first piezoelectric film 51 via the semiconductor film 50 or the first electrode 61, the first piezoelectric film 51 vibrates in the thickness direction DT. As a result, the portion of the semiconductor film 50 connected to the first piezoelectric film 51 that overlaps with the first space 471 in the thickness direction DT vibrates. In addition, the portion of the insulating film 48 connected to the semiconductor film 50 that overlaps with the first space 471 in the thickness direction DT vibrates. Furthermore, due to the first space 471, the portion of the semiconductor film 50 that overlaps with the first space 471 in the thickness direction DT and the portion of the insulating film 48 that overlaps with the first space 471 in the thickness direction DT vibrates in the thickness direction DT. This generates ultrasound, which is then directed at a person.

[0033] Furthermore, the first vibrating section 71 has a first central axis O1 and a first resonant frequency f1. The first central axis O1 passes through the center of the first vibrating section 71 and extends in the thickness direction DT. Moreover, the first central axis O1 coincides with the axis of the first space 471 and the axis of the first piezoelectric film 51.

[0034] The size of the first space 471, the material and thickness of the insulating film 48, the material and thickness of the semiconductor film 50, the material and size of the first piezoelectric film 51, and the material and size of the first electrode 61 are adjusted so that the first resonant frequency f1 is higher than the ultrasonic frequency of 20 kHz. For example, in this case, the above size, material and thickness are adjusted so that the first resonant frequency f1 is between 40 kHz and 140 kHz.

[0035] The second vibrating section 72 is composed of a second space 472, a portion of the insulating film 48 that overlaps with the second space 472 in the thickness direction DT, a portion of the semiconductor film 50 that overlaps with the second space 472 in the thickness direction DT, the second piezoelectric film 52, and the second electrode 62. Furthermore, since the second space 472 is arranged with a predetermined distance from the first space 471 in one direction D1, the second vibrating section 72 is aligned with the first vibrating section 71 with a predetermined distance from it in one direction D1. When a signal from the ultrasonic amplification circuit 38 is input to the second piezoelectric film 52 via the semiconductor film 50 or the second electrode 62, the second piezoelectric film 52 vibrates in the thickness direction DT. As a result, the portion of the semiconductor film 50 connected to the second piezoelectric film 52 that overlaps with the second space 472 in the thickness direction DT vibrates. Also, the portion of the insulating film 48 connected to the semiconductor film 50 that overlaps with the second space 472 in the thickness direction DT vibrates. Furthermore, the second space 472 causes the portion of the semiconductor film 50 that overlaps with the second space 472 in the thickness direction DT, and the portion of the insulating film 48 that overlaps with the second space 472 in the thickness direction DT, to vibrate in the thickness direction DT. This generates ultrasound, which is then irradiated onto a person.

[0036] Furthermore, the second vibrating section 72 has a second central axis O2 and a second resonant frequency f2. The second central axis O2 passes through the center of the second vibrating section 72 and extends in the thickness direction DT. Moreover, the second central axis O2 coincides with the axis of the second space 472 and the axis of the second piezoelectric film 52.

[0037] The size of the second space 472, the material and thickness of the insulating film 48, the material and thickness of the semiconductor film 50, the material and size of the second piezoelectric film 52, and the material and size of the second electrode 62 are adjusted so that the second resonant frequency f2 is higher than the ultrasonic frequency of 20 kHz. For example, in this case, the above size, material and thickness are adjusted so that the second resonant frequency f2 is between 40 kHz and 140 kHz.

[0038] Here, the digital information related to ultrasound stored in the ultrasonic recording medium 32 includes information such as a sine wave or cosine wave having a first resonant frequency f1 and a second resonant frequency f2. Therefore, signals such as a sine wave or cosine wave having a first resonant frequency f1 and a second resonant frequency f2 are input from the ultrasonic amplification circuit 38 to the first piezoelectric film 51 and the second piezoelectric film 52. As a result, as shown in Figure 4, the first vibrating part 71 vibrates with a peak sound pressure value of the first resonant frequency f1, and the second vibrating part 72 vibrates with a peak sound pressure value of the second resonant frequency f2. Therefore, ultrasound with a relatively high sound pressure is generated. Consequently, ultrasound is more likely to irradiate humans. Also, at this time, a difference sound wave with a difference frequency fd is generated due to the parametric effect. Furthermore, the difference frequency fd is expressed as the absolute value |f1-f2| of the difference between the first resonant frequency f1 and the second resonant frequency f2. Furthermore, the first resonant frequency f1 and the second resonant frequency f2 are adjusted so that the difference tone frequency fd is between 20 Hz and 20 kHz, which are the frequencies of audible sound. In addition, the difference between the first resonant frequency f1 and the second resonant frequency f2 is adjusted to be relatively small. As a result, the sound pressure of the ultrasound generated by the first vibrating part 71 and the second vibrating part 72 becomes more uniform. Therefore, the reproducibility of the sound source is improved, and the hypersonic effect is more easily obtained.

[0039] Furthermore, the sound pressure at the first resonant frequency f1 is defined as the first peak value Pv1. The sound pressure at the second resonant frequency f2 is defined as the second peak value Pv2. The average value of the first peak value Pv1 and the second peak value Pv2, i.e., (Pv1 + Pv2) / 2, is set to be between 105 dBSPL and 115 dBSPL. To achieve this, the sizes of the first and second spaces 471 and 472, the material and thickness of the insulating film 48, the material and thickness of the semiconductor film 50, the material and size of the first and second piezoelectric films 51 and 52, and the material and size of the first and second electrodes 61 and 62 are adjusted. Additionally, the amplitude of the signal from the ultrasonic amplification circuit 38 is adjusted. Note that in Figure 4, the first peak value Pv1 and the second peak value Pv2 are set to the same value, but they may be different.

[0040] Furthermore, returning to Figures 2 and 3, let Lp be the distance between the vibrating parts, from the first central axis O1 to the second central axis O2 in one direction D1. The distance between the vibrating parts Lp is greater than the wavelength of the difference sound wave produced by the first vibrating part 71 and the second vibrating part 72, as shown in the following relation (1). For example, if the difference sound frequency fd is 20 kHz, the speed of sound is approximately 340 m / s, so the wavelength of the difference sound wave is 17 mm. Therefore, in this case, the distance between the vibrating parts Lp is greater than 17 mm. In the following relation (1), λd is the wavelength of the difference sound wave, and c is the speed of sound.

[0041] Lp>λd λd = c / fd ... (1)

[0042] As described above, the ultrasonic generator 20 of the first embodiment is configured as follows. In this ultrasonic generator 20, for example, when the power of the ultrasonic generator 20 is turned on, audible sound from the audible speaker 30 is irradiated onto the human auditory system, and ultrasonic waves from the ultrasonic speaker 40 are irradiated onto the human body. As a result, a hypersonic effect is obtained for humans. Next, it will be explained that the ultrasonic generator 20 of this embodiment makes it easy to obtain a hypersonic effect.

[0043] Here, if the difference tone frequency fd is the frequency of an audible sound, then in addition to the audible sound emitted from the audible speaker 30, the sound produced by the difference sound wave is also audible to humans. In this case, the sound produced by the difference sound wave becomes noise to humans. Therefore, because it is unpleasant to humans, the hypersonic effect is difficult to obtain.

[0044] Therefore, in the ultrasonic generator 20 of this embodiment, the distance Lp between the vibrating parts is greater than the value obtained by dividing the speed of sound by the difference sound frequency fd, that is, λp, which is the wavelength of the difference sound wave. The distance Lp between the vibrating parts corresponds to the distance from the center of the first vibrating part 71 to the center of the second vibrating part 72.

[0045] As a result, the first vibrating section 71 and the second vibrating section 72 are separated by more than one wavelength of the difference sound wave produced by the first vibrating section 71 and the second vibrating section 72. Therefore, the phase difference between the ultrasound generated by the first vibrating section 71 and the ultrasound generated by the second vibrating section 72 tends to be large. Consequently, the ultrasound generated by the first vibrating section 71 and the ultrasound generated by the second vibrating section 72 tend to weaken each other. Therefore, the sound pressure of the difference sound wave produced by the first vibrating section 71 and the second vibrating section 72 tends to decrease. Consequently, the sound from the difference sound wave is less likely to become noise to humans, thus reducing discomfort to humans. This makes it easier to obtain the hypersonic effect.

[0046] Furthermore, the ultrasonic generator 20 of the first embodiment also provides the following effects.

[0047] [1] The average value of the first peak value Pv1 and the second peak value Pv2, i.e., (Pv1 + Pv2) / 2, is defined as being between 105 dBSPL and 115 dBSPL.

[0048] As a result, as shown in Figure 5, the sound pressure of the difference wave becomes the minimum acceptable level, i.e., 43 dBSPL or higher, which is a sound pressure level that is difficult for humans to hear and does not cause discomfort. Furthermore, the sound pressure of the difference wave becomes the optimal listening level, i.e., 60 dBSPL or lower, which is a sound pressure level that is audible for humans but does not cause discomfort. Therefore, discomfort to humans is suppressed. Consequently, the hypersonic effect is more easily obtained. The relationship between the average values ​​of the first peak value Pv1 and the second peak value Pv2 and the sound pressure of the difference wave shown in Figure 5 plots the values ​​when the first resonant frequency f1 is 58.8 kHz, the second resonant frequency f2 is 67.6 kHz, and the difference sound frequency fd is 8.8 kHz. The sound pressure of the difference wave is measured by collecting the sound generated by the first vibrating part 71 and the second vibrating part 72 on the surface of the first electrode 61 or the surface of the second electrode 62 using a microphone (not shown), and then performing frequency analysis on the collected sound. Furthermore, the first peak value Pv1 and the second peak value Pv2 are also measured by collecting the sound generated by the first vibrating section 71 and the second vibrating section 72 on the surface of the first electrode 61 or the second electrode 62 using a microphone (not shown), and then performing frequency analysis on the collected sound. From these measured first peak value Pv1 and second peak value Pv2, the average value of the first peak value Pv1 and the second peak value Pv2, i.e., (Pv1 + Pv2) / 2, is calculated. Furthermore, the position of the microphone (not shown) for measuring the sound pressure of the difference wave, the first peak value Pv1, and the second peak value Pv2 is, but not limited to, the surface of the first electrode 61 or the surface of the second electrode 62. For example, the position of the microphone (not shown) for measuring the sound pressure of the difference wave, the first peak value Pv1, and the second peak value Pv2 may be the surface of case 42 on the side of the ultrasonic irradiation direction.

[0049] (Second Embodiment) In the ultrasonic generator 20 of the second embodiment, a vibrating unit that generates difference sound waves with frequencies outside the audible frequency range is arranged between vibrating units that generate difference sound waves with frequencies within the audible frequency range. Otherwise, it is the same as the first embodiment.

[0050] Specifically, as shown in Figure 6, the ultrasonic speaker 40 includes a third vibrating section 73, a fourth vibrating section 74, a fifth vibrating section 75, and a sixth vibrating section 76, in addition to the first vibrating section 71 and the second vibrating section 72.

[0051] The third to sixth vibrating sections 73 to 76 each include a corresponding space, a portion of the insulating film 48, a portion of the semiconductor film 50, a piezoelectric film, and an electrode. Furthermore, the third to sixth vibrating sections 73 to 76 are arranged on the semiconductor substrate 46. In addition, the third to sixth vibrating sections 73 to 76 each have third to sixth central axes O3 to O6 and third to sixth resonant frequencies f3 to f6, respectively.

[0052] The third resonant frequency f3 is set to 80 kHz. The fourth resonant frequency f4 is set to 140 kHz. The fifth resonant frequency f5 is set to 120 kHz. The sixth resonant frequency f6 is set to 100 kHz. In addition, the first resonant frequency f1 is set to 40 kHz. The second resonant frequency f2 is set to 60 kHz. Figure 6 shows the values ​​of the first to sixth resonant frequencies f1 to f6 so that each resonant frequency can be seen.

[0053] Here, the digital information related to ultrasound stored in the ultrasonic recording medium 32 includes information such as sine waves or cosine waves having first to sixth resonant frequencies f1 to f6. Therefore, signals such as sine waves or cosine waves having first to sixth resonant frequencies f1 to f6 are input from the ultrasonic amplification circuit 38 to the first to sixth vibrating sections 71 to 76. As a result, as shown in Figure 7, the first to sixth vibrating sections 71 to 76 each vibrate with a peak sound pressure value corresponding to the first to sixth resonant frequencies f1 to f6. This generates ultrasound with a relatively high sound pressure. Consequently, ultrasound is more likely to irradiate humans. In addition, a difference sound wave is generated at this time due to the parametric effect.

[0054] Of the difference sound waves generated, the frequency of the difference sound wave from the first vibrating part 71 and the second vibrating part 72 is 20 kHz, and is therefore considered to be within the range of audible sound. The frequency of the difference sound wave from the first vibrating part 71 and the fourth vibrating part 74 is 100 kHz, and is therefore considered to be outside the range of audible sound. The frequency of the difference sound wave from the first vibrating part 71 and the fifth vibrating part 75 is 80 kHz, and is therefore considered to be outside the range of audible sound. The frequency of the difference sound wave from the first vibrating part 71 and the sixth vibrating part 76 is 60 kHz, and is therefore outside the range of audible sound. The frequency of the difference sound wave from the second vibrating part 72 and the fourth vibrating part 74 is 80 kHz, and is therefore outside the range of audible sound. The frequency of the difference sound wave from the second vibrating part 72 and the fifth vibrating part 75 is 60 kHz, and is therefore outside the range of audible sound. The difference sound wave frequency produced by the second vibrating section 72 and the sixth vibrating section 76 is 40 kHz, which is considered to be outside the frequency range of audible sound.

[0055] Furthermore, a fourth vibrating section 74, a fifth vibrating section 75, and a sixth vibrating section 76 are positioned between the first vibrating section 71 and the second vibrating section 72. Thus, between the first vibrating section 71 and the second vibrating section 72, which generate difference sound waves whose frequencies are within the range of audible sound, the fourth vibrating section 74, the fifth vibrating section 75, and the sixth vibrating section 76, which generate difference sound waves whose frequencies are outside the range of audible sound, are positioned.

[0056] Furthermore, of the difference sound waves generated as described above, the frequency of the difference sound waves produced by the second vibrating section 72 and the third vibrating section 73 is 20 kHz, and is therefore considered to be within the audible frequency range. The frequency of the difference sound waves produced by the third vibrating section 73 and the fourth vibrating section 74 is 60 kHz, and is therefore considered to be outside the audible frequency range.

[0057] Furthermore, a fourth vibrating section 74 is positioned between the second vibrating section 72 and the third vibrating section 73. Thus, a fourth vibrating section 74, which generates a difference sound wave whose frequency is outside the frequency range of audible sound, is positioned between the second vibrating section 72 and the third vibrating section 73, which generate a difference sound wave whose frequency is within the frequency range of audible sound.

[0058] As described above, a vibrating part that generates a difference sound wave whose frequency is outside the range of audible sound is positioned between vibrating parts that generate a difference sound wave whose frequency is within the range of audible sound.

[0059] Furthermore, as shown in Figure 6, the distance from the first central axis O1 to the second central axis O2 in one direction D1 is defined as the distance between the first vibrating parts Lp1. In addition, the distance from the second central axis O2 to the third central axis O3 in one direction D1 is defined as the distance between the second vibrating parts Lp2. Also, the distance from the fifth central axis O5 to the sixth central axis O6 in one direction D1 is defined as the distance between the third vibrating parts Lp3.

[0060] Furthermore, the frequency of the difference sound wave produced by the first vibrating part 71 and the second vibrating part 72 is 20 kHz, which is considered to be an audible sound frequency. Therefore, the distance Lp1 between the first vibrating parts is greater than the wavelength of the difference sound wave produced by the first vibrating part 71 and the second vibrating part 72. Consequently, the distance Lp1 between the first vibrating parts is greater than the value obtained by dividing the speed of sound by the frequency of the difference sound wave produced by the first vibrating part 71 and the second vibrating part 72. Here, the speed of sound is approximately 340 m / s, and the frequency of the difference sound wave produced by the first vibrating part 71 and the second vibrating part 72 is 20 kHz, so the distance Lp1 between the first vibrating parts is greater than 17 mm.

[0061] Furthermore, the frequency of the difference sound wave produced by the second vibrating part 72 and the third vibrating part 73 is 20 kHz, which is considered to be within the range of audible sound. Therefore, the distance Lp2 between the second vibrating parts is greater than the wavelength of the difference sound wave produced by the second vibrating part 72 and the third vibrating part 73. Thus, the distance Lp2 between the second vibrating parts is greater than the value obtained by dividing the speed of sound by the frequency of the difference sound wave produced by the second vibrating part 72 and the third vibrating part 73. Here, the speed of sound is approximately 340 m / s, and the frequency of the difference sound wave produced by the second vibrating part 72 and the third vibrating part 73 is 20 kHz, so the distance Lp2 between the second vibrating parts is greater than 17 mm.

[0062] Furthermore, the frequency of the difference sound wave produced by the fifth vibrating section 75 and the sixth vibrating section 76 is 20 kHz, which is considered to be within the range of audible sound. Therefore, the distance Lp3 between the third vibrating sections is greater than the wavelength of the difference sound wave produced by the fifth vibrating section 75 and the sixth vibrating section 76. Consequently, the distance Lp3 between the third vibrating sections is greater than the value obtained by dividing the speed of sound by the frequency of the difference sound wave produced by the fifth vibrating section 75 and the sixth vibrating section 76. Here, the speed of sound is approximately 340 m / s, and the frequency of the difference sound wave produced by the fifth vibrating section 75 and the sixth vibrating section 76 is 20 kHz, so the distance Lp3 between the third vibrating sections is greater than 17 mm.

[0063] Furthermore, as shown in Figure 7, the sound pressures at the first to sixth resonant frequencies f1 to f6 are denoted as the first to sixth peak values ​​Pv1 to Pv6, respectively. The average value of the first to sixth peak values ​​Pv1 to Pv6 is set to be between 105 dBSPL and 115 dBSPL. For this reason, the materials and sizes of the first to sixth vibrating parts 71 to 76 are adjusted. Also for this reason, the amplitude of the signal from the ultrasonic amplification circuit 38 is adjusted. Note that in Figure 7, the first to sixth peak values ​​Pv1 to Pv6 are set to the same value, but they may be different. In addition, the average value of the peak values ​​of a combination of two vibrating parts among the first to sixth vibrating parts 71 to 76 where the frequency of the difference sound wave is the frequency of an audible sound may be between 105 dBSPL and 115 dBSPL.

[0064] As described above, the ultrasonic generator 20 of the second embodiment is configured as described above. The ultrasonic generator 20 of the second embodiment also provides the same effects as the first embodiment. In addition, the second embodiment also provides the effects described below.

[0065] [2] Here, the distance Lp1 between the first vibrating parts is relatively large, as it is greater than the wavelength of the difference sound wave produced by the first vibrating part 71 and the second vibrating part 72. For this reason, a vibrating part different from the first vibrating part 71 and the second vibrating part 72 is likely to be placed between the first vibrating part 71 and the second vibrating part 72.

[0066] Therefore, between the first vibrating section 71 and the second vibrating section 72, which generate difference sound waves whose frequencies are within the range of audible sounds, are the fourth vibrating section 74, the fifth vibrating section 75, and the sixth vibrating section 76, which generate difference sound waves whose frequencies are outside the range of audible sounds.

[0067] This eliminates the need to position the fourth vibrating section 74, the fifth vibrating section 75, and the sixth vibrating section 76 outside the space between the first vibrating section 71 and the second vibrating section 72, thus suppressing an increase in the size of the ultrasonic speaker 40. Furthermore, since the frequencies of the difference sound waves produced by the first vibrating section 71 and the second vibrating section 72 and the fourth vibrating section 74, the fifth vibrating section 75, and the sixth vibrating section 76 are outside the audible frequency range, the sound produced by these difference sound waves is suppressed from becoming noise to humans. Therefore, discomfort to humans is suppressed. Consequently, the hypersonic effect is more easily obtained.

[0068] (Third embodiment) As shown in Figure 8, the ultrasonic generator 20 of the third embodiment includes a first ultrasonic speaker 401 and a second ultrasonic speaker 402 instead of the ultrasonic speaker 40. This is a difference from the first embodiment.

[0069] The first ultrasonic speaker 401 corresponds to the ultrasonic speaker 40 and is equivalent to the first ultrasonic irradiation unit. As shown in Figures 9 and 10, the first ultrasonic speaker 401 includes a first case 421, a first bonding member 441, and a first semiconductor substrate 461 instead of the case 42, bonding member 44, and semiconductor substrate 46. Furthermore, the first ultrasonic speaker 401 includes a first insulating film 481 and a first semiconductor film 501 instead of the insulating film 48 and semiconductor film 50. The first ultrasonic speaker 401 also includes a first vibrating unit 71, a second vibrating unit 72, and a third vibrating unit 73.

[0070] The first case 421 corresponds to case 42. The first bonding member 441 corresponds to bonding member 44. The first semiconductor substrate 461 corresponds to the first substrate and also to semiconductor substrate 46. The first semiconductor substrate 461 also has a first substrate surface 4651, a first substrate back surface 4671, a first space 471, a second space 472, and a first support portion 4751. The first substrate surface 4651 corresponds to substrate surface 465. The first substrate back surface 4671 corresponds to substrate back surface 467. The first support portion 4751 corresponds to support portion 475. A first air inflow / outflow space 4771 is formed, partitioned by the first substrate back surface 4671, the first bonding member 441, and the first case 421. Air flows in and out of the first air inflow / outflow space 4771 from inside the first case 421. Therefore, the first air inflow / outflow space 4771 corresponds to air inflow / outflow space 477. The first insulating film 481 corresponds to the insulating film 48. The first semiconductor film 501 corresponds to the semiconductor film 50. Therefore, the explanation of the first case 421, the first bonding member 441, the first semiconductor substrate 461, the first insulating film 481, and the first semiconductor film 501 will be omitted.

[0071] The first to third vibrating sections 71 to 73 are arranged on the first semiconductor substrate 461. The first resonant frequency f1 is set to 40 kHz. The second resonant frequency f2 is set to 80 kHz. The third resonant frequency f3 is set to 120 kHz. Figure 9 shows the values ​​of the first to third resonant frequencies f1 to f3 to indicate their respective resonant frequencies.

[0072] Here, the digital information related to ultrasound stored in the ultrasonic recording medium 32 includes information such as sine waves or cosine waves having first to third resonant frequencies f1 to f3. Therefore, signals such as sine waves or cosine waves having first to third resonant frequencies f1 to f3 are input from the ultrasonic amplification circuit 38 to the first to third vibrating units 71 to 73. As a result, as shown in Figure 11, the first to third vibrating units 71 to 73 vibrate with the sound pressure of the first to third resonant frequencies f1 to f3 as the peak value. Therefore, ultrasound with a relatively high sound pressure is generated. Consequently, ultrasound is more likely to be transmitted to humans.

[0073] At this time, difference sound waves are generated between the first to third vibrating parts 71 and 73. Since the first to third resonant frequencies f1 to f3 are 40, 80, and 120 kHz, the frequencies of the difference sound waves generated between the first to third vibrating parts 71 and 73 are 40 and 80 kHz, which are outside the frequency range of audible sound. Therefore, the sound of the difference sound waves generated between the first to third vibrating parts 71 and 73 is inaudible to humans and does not become noise.

[0074] The second ultrasonic speaker 402 corresponds to the second ultrasonic irradiation section and comprises a second case 422, a second bonding member 442, a second semiconductor substrate 462, a second insulating film 482, and a second semiconductor film 502. The second ultrasonic speaker 402 also comprises a fourth vibrating section 74, a fifth vibrating section 75, and a sixth vibrating section 76.

[0075] The second case 422 is formed in a box shape from resin, ceramics, or the like. The second case 422 also houses the second bonding member 442, the second semiconductor substrate 462, the second insulating film 482, the second semiconductor film 502, the fourth vibrating section 74, the fifth vibrating section 75, and the sixth vibrating section 76, which will be described later. Furthermore, the housing that houses the second case 422 is mounted, for example, on a desk or wall, which will not be shown. The second case 422 is also aligned with the first case 421 in one direction D1.

[0076] The second joining member 442 is, for example, a silicone-based adhesive. Multiple second joining members 442 are arranged at predetermined intervals in one direction D1 at the bottom of the second case 422. Furthermore, multiple second joining members 442 are arranged at predetermined intervals in directions perpendicular to both the one direction D1 and the thickness direction DT at the bottom of the second case 422.

[0077] The second semiconductor substrate 462 corresponds to the second substrate and is formed, for example, in a rectangular shape from silicon or the like. The length of the second semiconductor substrate 462 in the direction perpendicular to the thickness direction DT is, for example, 5.0 to 15.0 mm. Furthermore, since the second case 422 is aligned with the first case 421 in one direction D1, the second semiconductor substrate 462 is aligned with the first semiconductor substrate 461 in one direction D1. The second semiconductor substrate 462 also has a second substrate surface 4652, a second substrate back surface 4672, and a second support portion 4752.

[0078] The second substrate surface 4652 is the side of the second semiconductor substrate 462 opposite to the second bonding member 442. The second substrate back surface 4672 is the side of the second semiconductor substrate 462 facing the second bonding member 442. The second substrate back surface 4672 is also bonded to the second bonding member 442. This forms a second air inflow / outflow space 4772, which is partitioned by the second substrate back surface 4672, the second bonding member 442, and the bottom of the second case 422. Air flows in and out of the second air inflow / outflow space 4772 within the second case 422.

[0079] The second support portion 4752 is a part of the second semiconductor substrate 462 adjacent to the spaces of the fourth vibration portion 74, the fifth vibration portion 75, and the sixth vibration portion 76. The length of the second support portion 4752 in the thickness direction DT is, for example, 0.1 to 1.0 mm.

[0080] The second insulating film 482 is formed of an oxide film, a nitride film, or the like, and therefore has electrical insulating properties. For example, the second insulating film 482 is formed of silicon oxide. The length of the second insulating film 482 in the thickness direction DT is, for example, 1.0 to 10.0 μm. Furthermore, since the second insulating film 482 is formed on the second substrate surface 4652, it fills the spaces of the fourth vibrating part 74, the fifth vibrating part 75, and the sixth vibrating part 76, and is supported by the second support part 4752.

[0081] The second semiconductor film 502 is conductive, for example, by doping a silicon film with p-type impurities. The second semiconductor film 502 is formed on the second insulating film 482. Furthermore, the length of the second semiconductor film 502 in the thickness direction DT is set to 10.0 to 30.0 μm. The second semiconductor film 502 is connected to the ultrasonic amplification circuit 38 via bonding wires, pads, connection terminals, etc. (not shown). Here, the second semiconductor film 502 is given as a conductive film formed on the second insulating film 482, but it is not limited to this. The conductive film formed on the second insulating film 482 may be, for example, a film formed from an electrode material such as a titanium-aluminum alloy.

[0082] The fourth to sixth vibrating sections 74 to 76 are arranged on the second semiconductor substrate 462. The fourth resonant frequency f4 is set to 60 kHz. The fifth resonant frequency f5 is set to 140 kHz. The sixth resonant frequency f6 is set to 100 kHz. Figure 9 shows the values ​​of the fourth to sixth resonant frequencies f4 to f6 so that their respective resonant frequencies can be identified.

[0083] Here, the digital information related to ultrasound stored in the ultrasonic recording medium 32 includes information such as sine waves or cosine waves having the fourth to sixth resonant frequencies f4 to f6. Therefore, signals such as sine waves or cosine waves having the fourth to sixth resonant frequencies f4 to f6 are input from the ultrasonic amplification circuit 38 to the fourth to sixth vibrating sections 74 to 76. As a result, as shown in Figure 12, the fourth to sixth vibrating sections 74 to 76 vibrate with the sound pressure of the fourth to sixth resonant frequencies f4 to f6 as the peak value. Therefore, ultrasound with a relatively high sound pressure is generated. Consequently, ultrasound is more likely to be transmitted to humans.

[0084] At this time, difference sound waves are generated between the 4th to 6th vibrating sections 74 and 76. Since the 4th to 6th resonant frequencies f4 to f6 are 60, 140, and 100 kHz, the frequencies of the difference sound waves generated between the 4th to 6th vibrating sections 74 and 76 are 40 and 80 kHz, which are outside the range of audible sound. Therefore, the sound of the difference sound waves generated between the 4th to 6th vibrating sections 74 and 76 is inaudible to humans and does not constitute noise.

[0085] Furthermore, at this time, difference sound waves are generated between the first to third vibrating sections 71 to 73 and the fourth to sixth vibrating sections 74 to 76. The first to third resonant frequencies f1 to f3 are 40 to 120 kHz, and the fourth to sixth resonant frequencies f4 to f6 are 60 to 140 kHz. Therefore, the frequency of the difference sound waves generated between the first to third vibrating sections 71 to 73 and the fourth to sixth vibrating sections 74 to 76 is 20 to 100 kHz, which includes both audible frequencies and frequencies outside the audible frequency range.

[0086] Furthermore, as shown in Figures 9 and 10, the distance from the edge of the first semiconductor substrate 461 to the edge of the second semiconductor substrate 462 in one direction D1 is defined as the substrate distance Lsb. The substrate distance Lsb is greater than the value obtained by dividing the speed of sound by the divisor N. The divisor N is the minimum frequency of the difference sound wave generated between the first to third vibrating parts 71 to 73 located on the first semiconductor substrate 461 and the fourth to sixth vibrating parts 74 to 76 located on the second semiconductor substrate 462, within the audible frequency range.

[0087] Specifically, as described above, the frequency of the difference sound wave generated between the first to third vibrating parts 71 to 73 located on the first semiconductor substrate 461 and the fourth to sixth vibrating parts 74 to 76 located on the second semiconductor substrate 462 is 20 to 100 kHz. Therefore, within the audible frequency range, the minimum value of the difference sound wave frequency generated between the first to third vibrating parts 71 to 73 and the fourth to sixth vibrating parts 74 to 76 is 20 kHz. The speed of sound is approximately 340 m / s. Consequently, the distance Lsb between the substrates is greater than 17 mm.

[0088] As described above, the ultrasonic generator 20 of the third embodiment is configured as described above. The ultrasonic generator 20 of the third embodiment also provides the same effects as the second embodiment. Furthermore, the third embodiment also provides the effects described below.

[0089] [3] Here, difference sound waves are generated between the first to third vibrating sections 71 to 73 and the fourth to sixth vibrating sections 73 to 76. When the frequency of these generated difference sound waves is the frequency of an audible sound, the sound produced by the difference sound waves is heard by humans in addition to the audible sound emitted from the audible speaker 30. At this time, the sound produced by the difference sound waves becomes noise to humans. For this reason, it is unpleasant to humans, and the hypersonic effect is difficult to obtain.

[0090] Therefore, the distance Lsb between the substrates is greater than the value obtained by dividing the speed of sound by the divisor N. As a result, the distance between the first to third vibrating sections 71 to 73 and the fourth to sixth vibrating sections 74 to 76 is greater than one wavelength of the difference sound wave generated between the first to third vibrating sections 71 to 73 and the fourth to sixth vibrating sections 74 to 76. Consequently, the phase difference between the ultrasound generated in the first to third vibrating sections 71 to 73 and the ultrasound generated in the fourth to sixth vibrating sections 74 to 76 tends to be large. Therefore, the ultrasound generated in the first to third vibrating sections 71 to 73 and the ultrasound generated in the fourth to sixth vibrating sections 74 to 76 tend to weaken each other. Consequently, the sound pressure of the difference sound wave generated between the first to third vibrating sections 71 to 73 and the fourth to sixth vibrating sections 74 to 76 tends to decrease. Therefore, the sound from these difference sound waves is suppressed from becoming noise to humans, thus reducing discomfort to humans. This makes it easier to achieve the hypersonic effect.

[0091] (Fourth Embodiment) In the ultrasonic generator 20 of the fourth embodiment, as shown in Figure 13, the number of first ultrasonic speakers 401 is two instead of one. Also, the number of second ultrasonic speakers 402 is two instead of one. Furthermore, the first to fourth vibration sections 71 to 74 are provided in the first ultrasonic speaker 401, and the fifth vibration section 75 and the sixth vibration section 76 are provided in the second ultrasonic speaker 402. The configuration of the first to sixth vibration sections 71 to 76 differs from that of the third embodiment. Furthermore, the second ultrasonic speaker 402 includes a seventh vibration section 77 and an eighth vibration section 78. Other than these, it is the same as the third embodiment.

[0092] The first to fourth vibrating sections 71 to 74 are arranged on the first semiconductor substrate 461, as shown in Figure 14. Here, the first resonant frequency f1 is set to 70 kHz. The second resonant frequency f2 is set to 130 kHz. The third resonant frequency f3 is set to 100 kHz. The fourth resonant frequency f4 is set to 40 kHz. In Figure 14, the values ​​of the first to fourth resonant frequencies f1 to f4 are indicated so that their respective resonant frequencies can be identified.

[0093] The 5th to 8th vibrating sections 75 to 78 are arranged on the second semiconductor substrate 462. Furthermore, the 5th resonant frequency f5 is set to 85 kHz. The 6th resonant frequency f6 is set to 115 kHz. The 7th resonant frequency f7 is set to 145 kHz. The 8th resonant frequency f8 is set to 55 kHz. In Figure 14, the values ​​of the 5th to 8th resonant frequencies f5 to f8 are indicated so that the respective resonant frequencies can be seen.

[0094] Here, the digital information related to ultrasound stored in the ultrasonic recording medium 32 includes information such as sine waves or cosine waves having first to eighth resonant frequencies f1 to f8. Therefore, signals such as sine waves or cosine waves having first to eighth resonant frequencies f1 to f8 are input from the ultrasonic amplification circuit 38 to the first to eighth vibrating units 71 to 78. As a result, as shown in Figure 15, the first to eighth vibrating units 71 to 78 vibrate with the sound pressure of the first to eighth resonant frequencies f1 to f8 as the peak value. Therefore, ultrasound with a relatively high sound pressure is generated. Consequently, ultrasound is more likely to be transmitted to humans.

[0095] At this time, a difference sound wave is generated between the first to fourth vibrating parts 71 to 74. Since the first to fourth resonant frequencies f1 to f4 are 70, 130, 100, and 40 kHz, the frequency of the difference sound wave generated between the first to fourth vibrating parts 71 to 74 is 30 to 90 kHz, which is outside the frequency range of audible sound. Therefore, the sound of the difference sound wave generated between the first to fourth vibrating parts 71 to 74 is inaudible to humans and does not constitute noise.

[0096] Furthermore, at this time, difference sound waves are generated between the 5th to 8th vibrating sections 75 and 78. Since the 5th to 8th resonant frequencies f5 to f8 are 85, 115, 145, and 55 kHz, the frequency of the difference sound waves generated between the 5th to 8th vibrating sections 75 and 78 is 30 to 90 kHz, which is outside the range of audible sound. Therefore, the sound of the difference sound waves generated between the 5th to 8th vibrating sections 75 and 78 is inaudible to humans and does not constitute noise.

[0097] Furthermore, at this time, difference sound waves are generated between the first to fourth vibrating sections 71 to 74 and the fifth to eighth vibrating sections 75 to 78. The first to fourth resonant frequencies f1 to f4 are 40 to 130 kHz, and the fifth to eighth resonant frequencies f5 to f8 are 55 to 145 kHz. Therefore, the frequency of the difference sound waves generated between the first to fourth vibrating sections 71 to 74 and the fifth to eighth vibrating sections 75 to 78 is 15 to 105 kHz, which includes both audible frequencies and frequencies outside the audible frequency range.

[0098] In this case, the minimum frequency of the difference sound wave generated between the first to fourth vibrating parts 71 to 74 located on the first semiconductor substrate 461 and the fifth to eighth vibrating parts 75 to 78 located on the second semiconductor substrate 462, within the audible frequency range, is 15 kHz. The speed of sound is approximately 340 m / s. Therefore, the distance Lsb between the substrates is greater than 22.6 mm.

[0099] As described above, the ultrasonic generator 20 of the fourth embodiment is configured as described above. The ultrasonic generator 20 of the fourth embodiment also provides the same effects as the third embodiment.

[0100] (Other embodiments) This disclosure is not limited to the embodiments described above, and modifications can be made to these embodiments as appropriate. Furthermore, it goes without saying that, in each of the embodiments described above, the elements constituting the embodiment are not necessarily essential, except in cases where they are explicitly stated to be particularly essential or where they are clearly considered essential in principle.

[0101] The signaling units and methods described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the signaling units and methods described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the signaling units and methods described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0102] In each of the above embodiments, the audible recording medium 22, the audible signal generator 24, the audible playback circuit 26, the audible amplification circuit 28, the ultrasonic recording medium 32, the ultrasonic signal generator 34, the ultrasonic playback circuit 36, and the ultrasonic amplification circuit 38 are all separate components. However, they are not limited to being separate components. For example, the audible recording medium 22, the audible signal generator 24, the audible playback circuit 26, the ultrasonic recording medium 32, the ultrasonic signal generator 34, and the ultrasonic playback circuit 36 ​​may be an integrated circuit. Alternatively, the audible recording medium 22, the audible signal generator 24, the audible playback circuit 26, the audible amplification circuit 28, the ultrasonic recording medium 32, the ultrasonic signal generator 34, the ultrasonic playback circuit 36, and the ultrasonic amplification circuit 38 may be an integrated circuit. In these cases, audible sound and ultrasound are separated via a frequency filter or the like.

[0103] In the embodiments described above, the ultrasonic speaker 40, the first ultrasonic speaker 401, and the second ultrasonic speaker 402 are equipped with a PMUT to generate ultrasonic waves amplified by the ultrasonic amplification circuit 38, but are not limited to this. The ultrasonic speaker 40, the first ultrasonic speaker 401, and the second ultrasonic speaker 402 may, for example, be equipped with a CMUT to generate ultrasonic waves amplified by the ultrasonic amplification circuit 38. CMUT stands for Capacitive Micro-machined Ultrasound Transducer.

[0104] In the third and fourth embodiments described above, the distance Lsb between the substrates is greater than the value obtained by dividing the speed of sound by the divisor N. The divisor N is the minimum frequency of the difference sound waves generated between the multiple vibrating parts located on the first semiconductor substrate 461 and the multiple vibrating parts located on the second semiconductor substrate 462, within the frequency range of audible sound. Conversely, the divisor N may be the maximum frequency of the difference sound waves generated between the multiple vibrating parts located on the first semiconductor substrate 461 and the multiple vibrating parts located on the second semiconductor substrate 462, within the frequency range of audible sound.

[0105] This allows the first semiconductor substrate 461 and the second semiconductor substrate 462 to be placed closer together compared to the case where the divisor N is the minimum value mentioned above. As a result, the size of the ultrasonic generator 20 can be reduced. Therefore, an increase in the size of the ultrasonic generator 20 is suppressed. In addition, due to the distance Lsb between the substrates, a difference in phase between the ultrasonic waves generated by the multiple vibrating parts located on the first semiconductor substrate 461 and the ultrasonic waves generated by the multiple vibrating parts located on the second semiconductor substrate 462 is likely to occur. Therefore, the ultrasonic waves generated by the multiple vibrating parts located on the first semiconductor substrate 461 and the ultrasonic waves generated by the multiple vibrating parts located on the second semiconductor substrate 462 tend to weaken each other. As a result, the sound pressure of the difference sound waves generated between the multiple vibrating parts located on the first semiconductor substrate 461 and the multiple vibrating parts located on the second semiconductor substrate 462 tends to decrease. Therefore, the sound from these difference sound waves is less likely to become noise to humans, thus reducing discomfort to humans. This makes it easier to obtain the hypersonic effect.

[0106] The above embodiments may be combined as appropriate. [Explanation of Symbols]

[0107] 30 Audible Speakers 38. Amplifier circuit for ultrasonic applications 40 ultrasonic speakers 71 First Vibration Section 72 Second Vibration Section f1 1st resonance frequency f2 2nd resonant frequency fd Difference frequency

Claims

1. An ultrasonic generator, an audible sound irradiating unit (30) that irradiates a person with audible sound, An ultrasonic irradiation unit (40, 401) including a first vibrating unit (71) having a first resonant frequency (f1) and a second vibrating unit (72) having a second resonant frequency (f2), A signal unit (38) that outputs a signal including the first resonant frequency and the second resonant frequency to the first vibrating unit and the second vibrating unit, Equipped with, When a signal including the first resonant frequency and the second resonant frequency is input to the first vibrating unit and the second vibrating unit, the first vibrating unit and the second vibrating unit vibrate to generate ultrasound, and irradiate the person with the generated ultrasound. The vibration of the first vibrating part and the second vibrating part generates a difference sound wave with a difference frequency (fd) represented by the absolute value of the difference between the first resonant frequency and the second resonant frequency. The aforementioned difference tone frequency is considered to be the frequency of an audible sound. An ultrasonic generator in which the distance (Lp) from the center (O1) of the first vibrating part to the center (O2) of the second vibrating part is greater than the value (λp) obtained by dividing the speed of sound (c) by the difference tone frequency.

2. When a signal including the first resonant frequency and the second resonant frequency is input to the first vibrating unit and the second vibrating unit, The first vibrating part vibrates with a peak value of the sound pressure at the first resonant frequency. The second vibrating part vibrates with a peak value of the sound pressure at the second resonant frequency. The ultrasonic generator according to claim 1, wherein the average value of the sound pressure at the first resonant frequency and the sound pressure at the second resonant frequency is 105 dBSPL or more and 115 dBSPL or less.

3. The ultrasonic irradiation unit includes a fourth vibrating unit (74) having a fourth resonant frequency (f4), The signal unit outputs a signal including the first resonant frequency, the second resonant frequency, and the fourth resonant frequency to the first vibrating unit, the second vibrating unit, and the fourth vibrating unit. When a signal including the first resonant frequency, the second resonant frequency, and the fourth resonant frequency is input to the first vibrating unit, the second vibrating unit, and the fourth vibrating unit vibrate to generate ultrasonic waves, and irradiate the person with the generated ultrasonic waves. The frequencies of the difference sound waves produced by the first vibrating part and the fourth vibrating part are set to be outside the frequency range of audible sound. The frequencies of the difference sound waves produced by the second and fourth vibrating parts are set to be outside the frequency range of audible sounds. The ultrasonic generator according to claim 1 or 2, wherein the fourth vibrating section is arranged between the first vibrating section and the second vibrating section.

4. An ultrasonic generator, an audible sound irradiating unit (30) that irradiates a person with audible sound, A first ultrasonic irradiation unit (401) includes a first vibrating unit having a first resonant frequency, a second vibrating unit having a second resonant frequency, and a first substrate (461) on which the first vibrating unit and the second vibrating unit are arranged. A second ultrasonic irradiation unit (402) includes a fifth vibrating section having a fifth resonant frequency, a sixth vibrating section having a sixth resonant frequency, and a second substrate (462) on which the fifth vibrating section and the sixth vibrating section are arranged. A signal unit (38) outputs a signal including the first resonant frequency and the second resonant frequency to the first vibrating unit and the second vibrating unit, and outputs a signal including the fifth resonant frequency and the sixth resonant frequency to the fifth vibrating unit and the sixth vibrating unit, Equipped with, When a signal including the first resonant frequency and the second resonant frequency is input to the first vibrating unit and the second vibrating unit, the first vibrating unit and the second vibrating unit vibrate to generate ultrasound, and irradiate the person with the generated ultrasound. The frequencies of the difference sound waves produced by the first vibrating part and the second vibrating part are set to be outside the frequency range of audible sound. When a signal including the fifth resonant frequency and the sixth resonant frequency is input to the fifth vibrating unit and the sixth vibrating unit, the fifth vibrating unit and the sixth vibrating unit vibrate to generate ultrasound, and irradiate the person with the generated ultrasound. The frequencies of the difference sound waves produced by the fifth and sixth vibrating parts are set to be outside the frequency range of audible sounds. The frequency of the difference sound wave generated between the first vibrating part and the second vibrating part and the fifth vibrating part and the sixth vibrating part includes the frequency of audible sound. The first substrate and the second substrate are arranged in one direction (D1), An ultrasonic generator wherein the distance (Lsb) from the edge of the first substrate to the edge of the second substrate in one direction is greater than the value obtained by dividing the speed of sound by the minimum value (N) of the difference sound wave frequencies generated between the first vibrating part and the second vibrating part, which are located on the first substrate and the fifth vibrating part and the sixth vibrating part, which are located on the second substrate, within the range of audible sound frequencies.

5. An ultrasonic generator, an audible sound irradiating unit (30) that irradiates a person with audible sound, A first ultrasonic irradiation unit (401) includes a first vibrating unit having a first resonant frequency, a second vibrating unit having a second resonant frequency, and a first substrate (461) on which the first vibrating unit and the second vibrating unit are arranged. A second ultrasonic irradiation unit (402) includes a fifth vibrating section having a fifth resonant frequency, a sixth vibrating section having a sixth resonant frequency, and a second substrate (462) on which the fifth vibrating section and the sixth vibrating section are arranged. A signal unit (38) outputs a signal including the first resonant frequency and the second resonant frequency to the first vibrating unit and the second vibrating unit, and outputs a signal including the fifth resonant frequency and the sixth resonant frequency to the fifth vibrating unit and the sixth vibrating unit, Equipped with, When a signal including the first resonant frequency and the second resonant frequency is input to the first vibrating unit and the second vibrating unit, the first vibrating unit and the second vibrating unit vibrate to generate ultrasound, and irradiate the person with the generated ultrasound. The frequencies of the difference sound waves produced by the first vibrating part and the second vibrating part are set to be outside the frequency range of audible sound. When a signal including the fifth resonant frequency and the sixth resonant frequency is input to the fifth vibrating unit and the sixth vibrating unit, the fifth vibrating unit and the sixth vibrating unit vibrate to generate ultrasound, and irradiate the person with the generated ultrasound. The frequencies of the difference sound waves produced by the fifth and sixth vibrating parts are set to be outside the frequency range of audible sounds. The frequency of the difference sound wave generated between the first vibrating part and the second vibrating part and the fifth vibrating part and the sixth vibrating part includes the frequency of audible sound. The first substrate and the second substrate are arranged in one direction (D1), An ultrasonic generator wherein the distance (Lsb) from the edge of the first substrate to the edge of the second substrate in one direction is greater than the value obtained by dividing the speed of sound by the maximum value (N) of the difference sound wave frequencies generated between the first and second vibrating parts located on the first substrate and the fifth and sixth vibrating parts located on the second substrate, within the range of audible sound frequencies.

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