Bone conduction earphones and instructions on how to use them

Abstract

We provide bone conduction earphones that can improve sound quality. [Solution] In the bone conduction earphone 1, the sound collection unit 10 collects external sound and converts it into an input audio signal corresponding to the external sound. The ear insertion unit 11 is sized to fit into the recess of the user's concha. The signal receiving unit 12 is provided inside the ear insertion unit and receives the converted input audio signal. The first vibration source 13 is provided inside the ear insertion unit and has vibration characteristics in which the amplitude of the input audio signal in a predetermined frequency band shows a peak at a predetermined first frequency. The second vibration source 14 is provided inside the ear insertion unit and has vibration characteristics in which the amplitude of the input audio signal in a predetermined frequency band shows a peak at a predetermined second frequency that is higher than the first frequency, and can vibrate independently of the first vibration source. The vibration control unit 15 simultaneously inputs the received input audio signal to the first vibration source and the second vibration source.

Description

Technical Field

[0001] The present invention relates to a bone conduction earphone and a method of using the bone conduction earphone.

Background Art

[0002] Conventionally, there are various technologies related to earphones (also referred to as ear inserts, piezoelectric vibration devices, etc.) for improving sound quality. For example, Japanese Patent Application Laid-Open No. 2012-222682 (Patent Document 1) discloses a bone conduction earphone including a bone conduction vibration part, a front convex part, and a rear convex part. The bone conduction vibration part is formed on an ellipsoid and generates voice vibrations. The front convex part projects on one end side in the length direction of the bone conduction vibration part and on the front side in the thickness direction. The rear convex part projects on one end side in the length direction of the bone conduction vibration part and on the rear side in the thickness direction. When one end side in the length direction of the bone conduction vibration part is inserted into the depression of the concha cavity and rotated so that the lower part in the width direction of the bone conduction vibration part adheres to the bottom of the depression of the concha cavity and worn, the bone conduction earphone presses against the tragus, the concha cavity, the antitragus, and the periphery of the entrance of the external auditory canal. Here, the bone conduction vibration part is composed of a piezoelectric ceramic vibrator. Thereby, it is said that the reproducibility of voice information is excellent, it is easy to insert into the depression of the concha cavity, and the support stability after wearing is excellent.

[0003] Furthermore, Japanese Patent Publication No. 2018-191140 (Patent Document 2) discloses a piezoelectric vibration device comprising a plurality of piezoelectric vibrators, a support part, and a vibration transmission part. The plurality of piezoelectric vibrators each have a plate-shaped vibrating body and a plate-shaped piezoelectric body provided on the surface of the vibrating body. The support part supports each of the plurality of piezoelectric vibrators. The vibration transmission part is flexible and transmits the vibrations of each of the plurality of piezoelectric vibrators. Next, each of the plurality of piezoelectric vibrators has a through hole that penetrates the vibrating body and the piezoelectric body in the thickness direction, and is provided parallel to each other with spacing in the thickness direction. The support part has a rod-shaped support column that is inserted through the through hole of each of the plurality of piezoelectric vibrators. The vibration transmission part is positioned between each of the plurality of piezoelectric vibrators that are adjacent to each other. This makes it possible to synchronize the vibrations of each of the plurality of piezoelectric vibrators.

[0004] Furthermore, Japanese Patent Publication No. 2017-076919 (Patent Document 3) discloses an earphone configured to support two parts of the same electromagnetic transducer that move relative to each other with an elastic body interposed between them. This earphone is configured to extract vibrations for cartilage conduction from at least one of the two parts. This allows the pressure on the vibrating surface that contacts the tragus to be adjusted manually as a method of using the bone conduction speaker. It also allows the transmission ratio of sound information via cartilage conduction to sound information via air conduction to be changed according to the level of external noise.

[0005] On the other hand, although not in the field of earphone technology, Japanese Patent Publication No. 2020-141354 (Patent Document 4) discloses an underwater ultrasonic transducer used in a transducer, as an apparatus using multiple transducers. This underwater ultrasonic transducer is a laminated transducer including a low-frequency piezoelectric transducer, a front mass and a rear mass, an acoustic matching layer, a composite transducer, and a backing material. Here, the low-frequency piezoelectric transducer is for transmitting and receiving low-frequency acoustic signals, and the front mass and rear mass form a resonant system for the low-frequency piezoelectric transducer and sandwich the low-frequency piezoelectric transducer between them. The acoustic matching layer is disposed on the acoustic radiating surface side of the front mass, and the composite transducer is disposed between the acoustic matching layer and the front mass and transmits and receives high-frequency acoustic signals. The backing material is disposed between the composite transducer and the front mass to fix the composite transducer. This makes it possible to secure the desired operating range for the transmission voltage sensitivity. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2012-222682 [Patent Document 2] Japanese Patent Publication No. 2018-191140 [Patent Document 3] Special Publication No. 2017-076919 [Patent Document 4] Japanese Patent Publication No. 2020-141354 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Bone conduction earphones use a vibration source that vibrates with an amplitude corresponding to the audio signal. This vibration source refers to the element that generates vibration, and can be a diaphragm, vibrator, or vibration element. Specifically, examples include piezoelectric ceramic vibrators, electromagnetic vibrators, and supermagnetostrictive vibrators.

[0008] Generally, vibration sources exhibit vibration characteristics that show a peak in amplitude (output) at a predetermined frequency, and these vibration characteristics vary greatly depending on the material, structure, and type of the vibration source. For example, if the peak of the vibration characteristic is on the low-frequency side, and the input audio signal is also on the low-frequency side, the vibration source will vibrate with a large amplitude, making it easier for the user to hear. On the other hand, if the input audio signal is on the high-frequency side, the vibration source will vibrate with a small amplitude, making it difficult for the user to hear. In other words, bone conduction earphones have the problem that the quality of sound (sound quality) that the user can hear varies depending on the vibration characteristics of the vibration source.

[0009] In particular, the vibration characteristics of a vibration source often peak at low frequencies. Therefore, with high-frequency audio signals, the amplitude of the vibration source becomes small, making it difficult for the user to hear. For example, the characters that make up a language generally consist of vowels and consonants. In Japanese, vowels are the characters "a," "i," "u," "e," and "o," while consonants are all characters other than vowels. In English, vowels are the characters "a," "e," "i," "o," and "u," while consonants are all characters other than vowels. Generally, in other languages, vowels are at low frequencies and consonants are at high frequencies. As a result, conventional bone conduction earphones have difficulty reproducing the vibrations of consonants in the high-frequency range, making it difficult for users to hear them. Therefore, there has been a need for bone conduction earphones that produce large amplitudes of sound at any frequency range, making them easy for users to hear.

[0010] In particular, for users with hearing impairments or hearing loss, it is crucial to accurately transmit both high-frequency and low-frequency sounds. Furthermore, even just being able to clearly hear high-frequency consonants can broaden the range of sounds that people with hearing impairments or hearing loss can understand, improving their comprehension of external sounds.

[0011] Here, in the technology described in Patent Document 1, the bone conduction vibrator is a single piezoelectric ceramic. In the technology described in Patent Document 2, multiple piezoelectric vibrators are connected (in contact) to synchronize the overall vibration and increase the output that becomes sound. In the technology described in Patent Document 3, the same electromagnetic vibrator is used to facilitate the extraction of vibration. In the technology described in Patent Document 4, a desired range of motion can be secured by stacking a low-frequency piezoelectric vibrator and a composite vibrator. However, in the technologies described in Patent Documents 1-3, since a single vibrator or multiple identical vibrators are used, there is a high possibility that a single vibration characteristic will be exhibited overall, and the above-mentioned problems cannot be solved. In the technology described in Patent Document 4, since the vibration intensity is increased as a whole by stacking multiple different vibrators, it is no different from the vibration characteristic of a single vibrator, and therefore the above-mentioned problems cannot be solved.

[0012] Therefore, the present invention has been made to solve the aforementioned problems and aims to provide bone conduction earphones and a method for using bone conduction earphones that can accurately reproduce sound in any frequency band and improve sound quality. [Means for solving the problem]

[0013] The bone conduction earphone according to the present invention comprises a sound collecting unit, an ear insertion unit, a signal receiving unit, a first vibration source, a second vibration source, and a vibration control unit. The sound collecting unit collects external sound and converts it into an input audio signal corresponding to the external sound. The ear insertion unit is sized to fit into the cavity of the user's concha. The signal receiving unit is provided inside the ear insertion unit and receives the converted input audio signal. The first vibration source is provided inside the ear insertion unit and has vibration characteristics in which the amplitude of an input audio signal in a predetermined frequency band peaks at a predetermined first frequency. The second vibration source is provided inside the ear insertion unit and has vibration characteristics in which the amplitude of an input audio signal in the frequency band peaks at a predetermined second frequency higher than the first frequency, and can vibrate independently of the first vibration source. The vibration control unit simultaneously inputs the received input audio signal to the first vibration source and the second vibration source. The bone conduction earphone according to the present invention inserts one end of the ear insertion part into a recess in the user's concha, presses the ear insertion part against the concha between the user's tragus and antitragus, and simultaneously vibrates the first vibration source and the second vibration source in response to external sound.

[0014] Furthermore, the method of using the bone conduction earphone according to the present invention is a method of using a bone conduction earphone, comprising a pressing step and a vibration step. The pressing step involves inserting one end of the ear insertion part into the recess of the user's concha, and pressing the ear insertion part against the concha between the user's tragus and antitragus. The vibration step involves simultaneously vibrating the first vibration source and the second vibration source based on the external sound. [Effects of the Invention]

[0015] According to the present invention, it is possible to accurately reproduce sound in any frequency band and improve sound quality. [Brief explanation of the drawing]

[0016] [Figure 1] These are a plan view and a front view cross-sectional view showing an example of a bone conduction earphone according to an embodiment of the present invention. [Figure 2] It is a graph showing an example of the output voice amplitude of the prior art and the output voice amplitude of the present invention with respect to the input voice signal. [Figure 3] It is a front view showing an example before and after inserting the bone conduction earphone according to an embodiment of the present invention into the depression of the user's concha cavity. [Figure 4] It is a schematic diagram showing an example of the output voice amplitude of the prior art with respect to an input voice signal including low-frequency and high-frequency voices. [Figure 5] It is a schematic diagram showing an example of the output voice amplitude of the present invention with respect to an input voice signal including low-frequency and high-frequency voices. [Figure 6] It is a plan view cross-sectional view and a front view cross-sectional view showing an example of a configuration in which the first vibration generation source and the second vibration generation source are rearranged. [Figure 7] It is a front view cross-sectional view (Fig. 7A) showing an example when the arrangement of the first vibration generation source and the second vibration generation source is changed, and a front view cross-sectional view (Fig. 7B) showing an example when the sizes of the first vibration generation source and the second vibration generation source are changed. [Figure 8] It is a plan view cross-sectional view and a front view cross-sectional view showing an example of a rearranged configuration when the sizes of the first vibration generation source and the second vibration generation source are changed. [Figure 9] It is a plan view cross-sectional view, a front view cross-sectional view, and a graph of output voice amplitude showing an example when a third vibration generation source is further provided, and a plan view cross-sectional view, a front view cross-sectional view, and a graph of output voice amplitude showing an example when a third vibration generation source and a fourth vibration generation source are further provided. [Figure 10] It is a schematic diagram showing Example 1 of a virtual bone conduction earphone and the experimental situation. [Figure 11] It is a graph showing an example of the vibration characteristics of the first vibration generation source, the vibration characteristics of the second vibration generation source, the theoretically synthesized theoretical vibration characteristics, and the experimentally obtained experimental vibration characteristics.

Embodiments for Carrying Out the Invention

[0017] The following describes embodiments of the present invention with reference to the attached drawings to facilitate understanding of the invention. Note that the following embodiments are merely examples of the present invention and do not limit the technical scope of the invention.

[0018] As shown in Figure 1, the bone conduction earphone 1 according to an embodiment of the present invention comprises a sound collection unit 10, an ear insertion unit 11, a signal receiving unit 12, a first vibration source 13, a second vibration source 14, and a vibration control unit 15.

[0019] Here, the sound collection unit 10 collects external sound and converts it into an input audio signal corresponding to that external sound. The sound collection unit 10 can be, for example, a microphone.

[0020] Furthermore, the ear insertion portion 11 is sized to be inserted into the recess of the user's concha. Here, the ear insertion portion 11 is configured in an elliptical disc shape, for example, as shown in Figure 1. Elliptical disc shape means an elliptical shape with a certain thickness, which allows it to be inserted into the recess of the user's concha.

[0021] Furthermore, the signal receiving unit 12 is located inside the ear insertion unit 11 and receives the converted input audio signal. Here, if the signal receiving unit 12 is connected to the sound collection unit 10 by wireless communication, as shown in Figure 1, for example, the signal receiving unit 12 can receive the input audio signal from the sound collection unit 10 via wireless communication. Here, wireless communication can be, for example, Bluetooth®. Alternatively, if the signal receiving unit 12 is connected to the sound collection unit 10 by wired communication, the signal receiving unit 12 can receive the input audio signal from the sound collection unit 10 via electrical wires.

[0022] Furthermore, the first vibration source 13 is provided inside the ear insertion part 11 and has a vibration characteristic V1 in which the amplitude (output) Amplitude (mm) shows a peak at a predetermined first frequency f1 (Hz) for an input audio signal in a predetermined frequency band f. Here, the vibration source refers to an element that generates vibration, and corresponds to a diaphragm, vibrator, vibrating element, etc. Also, if the input audio signal has a constant amplitude Amplitude (mm) in the range of a predetermined frequency f (for example, 10Hz to 6000Hz), as shown in Figure 2, the first vibration source 13 will receive the input audio signal and output a vibration with an amplitude Amplitude (mm) that shows a peak at the first frequency f1 (Hz).

[0023] In Figure 2, the vibrating surface of the first vibration source 13 is positioned upwards towards the ear insertion portion 11. Here, the vibrating surface is the surface that outputs vibration, and typically, a vibration source has a vibrating surface that generates vibration in one direction.

[0024] Furthermore, the second vibration source 14 is provided inside the ear insertion part 11 and has a vibration characteristic V2 in which the amplitude Amplitude (mm) of the input audio signal in the frequency band peaks at a predetermined second frequency f2 (Hz) that is higher than the first frequency f1 (Hz), and can vibrate independently of the first vibration source 13. Here, if the input audio signal has a constant amplitude Amplitude (mm) in the range of a predetermined frequency f (10Hz to 6000Hz), as described above, the second vibration source 14 receives the input audio signal and outputs a vibration with an amplitude Amplitude (mm) that peaks at the second frequency f2 (Hz). Also, in Figure 2, the vibration surface of the second vibration source 14 is positioned facing the same direction as the vibration surface of the first vibration source 13.

[0025] Here, the statement that the second vibration source 14 vibrates independently of the first vibration source 13 means that the first vibration source 13 and the second vibration source 14 vibrate separately without contact with each other. If the first vibration source 13 and the second vibration source 14 are located close together, the vibrations of the first vibration source 13 and the vibrations of the first vibration source 14 may partially interfere with and cancel each other out. However, since the first vibration source 13 and the second vibration source 14 vibrate in different and unique frequency bands, the overall output vibration will have a broader frequency band.

[0026] Then, as shown in Figure 2, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, the vibration characteristics V1 of the first vibration source 13 and the vibration characteristics V2 of the second vibration source 14 overlap with each other to form a composite wave, and as a whole, a vibration characteristic V12 with a wider frequency band is formed.

[0027] This is called stagger tuning in the field of electronic circuits. Stagger tuning means expanding the frequency range to obtain the required frequency band by linking multiple tuning circuits with different frequency bands. In this invention, we have applied this phenomenon, which is in the field of acoustics rather than electronic circuits, to bone conduction earphones.

[0028] As a result, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, the frequency range in which amplitude (Amplitude (mm)) exists is broadened compared to when the first vibration source 13 and the second vibration source 14 vibrate individually. This makes it possible to increase the amplitude (Amplitude (mm)) and vibrate any sound in any frequency range.

[0029] Furthermore, the vibration control unit 15 simultaneously inputs the received audio signal to the first vibration source 13 and the second vibration source 14. This makes it possible to vibrate the first vibration source 13 and the second vibration source 14 simultaneously.

[0030] Furthermore, as shown in Figure 3, the bone conduction earphone 1 according to an embodiment of the present invention has one end 11a of the ear insertion part 11 inserted into the recess of the user's concha cavity CC, and the ear insertion part 11 is pressed against the concha cavity CC between the user's tragus T and antitragus A, causing the first vibration source 13 and the second vibration source 14 to vibrate simultaneously in response to external sound. Deep within the recess of the concha cavity CC is the ear canal EC. The ear canal EC is connected to the cochlea, a sensory organ that controls hearing, and cartilage Ca, such as tragus cartilage and auricular cartilage, is present around the ear canal EC, and vibrations are transmitted from the ear canal EC to the cartilage Ca and then to the cochlea.

[0031] This makes it possible to accurately reproduce sound in any frequency band and improve sound quality. Specifically, as explained in Figure 2, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, a vibration characteristic V12 with a wide frequency band is formed. This vibration characteristic V12 is important.

[0032] For example, as shown in Figure 4, in the conventional technology, if an input audio signal having various frequency bands is vibrated only by the first vibration source 13, the peak of the first frequency f1 (Hz) in the vibration characteristic V1 of the first vibration source 13 is biased towards the low frequency side. As a result, the output audio amplitude of the first vibration source 13 becomes larger only on the low frequency side. In other words, the output audio amplitude decreases sharply on the high frequency side compared to the input audio signal. For example, when the first vibration source 13 of the ear insertion part 11 vibrates while pressed against the concha cavity CC, the vibration is transmitted to the external auditory canal EC and surrounding cartilage Ca, but the amplitude of vibration on the high frequency side decreases sharply, leaving only the amplitude of vibration on the low frequency side. Therefore, when a user hears this, for example, only the low-frequency sounds will be loud, specifically, only the vowel sounds will be loud. As a result, the user will perceive only the vowels as loud, and sounds containing consonants will be difficult to understand.

[0033] Furthermore, in conventional technology, if an input audio signal having various frequency bands is vibrated only by the second vibration source 14, the peak of the second frequency f2 (Hz) in the vibration characteristic V2 of the second vibration source 14 is biased towards the high-frequency side. As a result, the output audio amplitude of the second vibration source 14 becomes larger only on the high-frequency side. In other words, the output audio amplitude decreases sharply on the low-frequency side compared to the input audio signal. For example, when the second vibration source 14 of the ear insertion part 11 vibrates while pressed against the concha cavity CC, the vibration is transmitted to the external auditory canal EC and surrounding cartilage Ca, but the amplitude of vibration on the low-frequency side decreases sharply, leaving only the amplitude of vibration on the high-frequency side. Therefore, when a user listens to this, for example, only the high-frequency sounds become louder, and then only the consonant sounds become louder. In this case, the user perceives only the consonants as louder, and it becomes difficult to understand sounds that include vowels.

[0034] As shown in Figure 5, in the present invention, when an input audio signal having various frequency bands is simultaneously vibrated by the first vibration source 13 and the second vibration source 14, the overall vibration characteristic V12 has a large amplitude over a wide frequency range, resulting in a large overall output audio amplitude at both low and high frequencies. In other words, the output audio amplitude is reproduced with a waveform equivalent to the input audio signal, without any decrease in amplitude at either the low or high frequency side compared to the input audio signal. For example, when the first vibration source 13 and the second vibration source 14 of the ear insertion part 11 vibrate while pressed against the concha (CC), the vibration is transmitted to the external auditory canal (EC) and surrounding cartilage (Ca). However, since the first vibration source 13 excels at low-frequency vibrations and the second vibration source 14 excels at high-frequency vibrations, neither the low-frequency nor the high-frequency vibrations decrease. Therefore, when a user listens to this, for example, it is heard as a loud sound at both low and high frequencies, allowing both vowels and consonants to be clearly heard. This makes it possible to accurately reproduce audio across any frequency band, thereby improving sound quality.

[0035] In this invention, as long as the second vibration source 14 vibrates independently of the first vibration source 13, there is no particular limitation, and a wide variety of configurations and arrangements can be realized.

[0036] For example, in Figure 1, the first vibration source 13 and the second vibration source 14 are arranged side by side perpendicular to the vibration surface. However, the configuration is not limited to this. For example, as shown in Figure 6, the first vibration source 13 and the second vibration source 14 may be arranged inside the ear insertion part 11 with their respective vibration surfaces aligned horizontally without contact with each other, or the first vibration source 13 and the second vibration source 14 may be arranged with some overlap in the vertical space.

[0037] Furthermore, as shown in Figure 6, the first vibration source 13 and the second vibration source 14 may be arranged inside the ear insertion portion 11 with their respective vibration surfaces facing outward at a predetermined inclination angle α (degrees). There are no particular limitations on the inclination angle α formed between the vibration surface of the first vibration source 13 and the vibration surface of the second vibration source 14; for example, it can be set within the range of 0 to 180 degrees.

[0038] Here, if the inclination angle α is 180 degrees, the vibration planes of the first vibration source 13 and the second vibration source 14 are aligned horizontally and facing the same direction. If the inclination angle α is 90 degrees, the vibration plane of the first vibration source 13 is aligned perpendicular to the vibration plane of the second vibration source 14. If the inclination angle α is 0 degrees, the vibration plane of the first vibration source 13 is aligned horizontally with respect to the vibration plane of the second vibration source 14, but facing different directions.

[0039] Furthermore, as shown in Figure 6, the first vibration source 13 and the second vibration source 14 may be configured to be arranged parallel to each other with their respective vibration surfaces facing outward inside the ear insertion portion 11. Alternatively, as shown in Figure 6, the first vibration source 13 and the second vibration source 14 may be configured to be arranged perpendicular to each other with their respective vibration surfaces facing outward inside the ear insertion portion 11. Here, in Figure 6, the vibration surface of the first vibration source 13 is positioned perpendicular to the vibration surface of the second vibration source 14 near the lower part of the center of the vibration surface of the second vibration source 14, but the configuration is not limited to this.

[0040] Furthermore, there are no particular limitations on the sound collection unit 10; for example, in addition to a microphone, it may be a sound collection device that collects music or sound, such as a music player or radio.

[0041] Furthermore, the shape of the ear insertion portion 11 is appropriately designed and modified according to the configuration and arrangement of the first vibration source 13 and the second vibration source 14. As shown in Figure 1, it may be elliptical, or as shown in Figure 5, it may be cylindrical or hemispherical.

[0042] Furthermore, there are no particular limitations on the size of the ear insertion portion 11, but it is preferable that, for example, the length be in the range of 1.0 cm to 3.0 cm, the width be in the range of 0.5 cm to 2.0 cm, and the thickness be in the range of 0.5 cm to 2.0 cm.

[0043] Furthermore, there are no particular limitations on the configuration of the signal receiving unit 12. For example, it may be an electrical circuit that receives the input audio signal, or it may also include an adjustment circuit to adjust the magnitude of the input audio signal, a switch circuit to control the power on and off, a filter circuit to block noise signals contained in the input audio signal, or a combination thereof.

[0044] Furthermore, there are no particular limitations on the types of the first vibration source 13 and the second vibration source 14, but examples include piezoelectric ceramic resonators, electromagnetic resonators, and supermagnetostrictive resonators. Also, the first vibration source 13 and the second vibration source 14 may be of the same type or different types.

[0045] Furthermore, there are no particular limitations on the configuration of the first vibration source 13 and the second vibration source 14. For example, if the first vibration source 13 is a first diaphragm and the second vibration source 14 is a second diaphragm, the first vibration source 13 and the second vibration source 14 may be configured by combining a first device capable of vibrating with the first diaphragm and a second device capable of vibrating with the second diaphragm. Alternatively, the first vibration source 13 and the second vibration source 14 may be configured by incorporating the first diaphragm and the second diaphragm into a single device and configuring it so that the first diaphragm and the second diaphragm vibrate independently.

[0046] Furthermore, there are no particular limitations on the positional relationship between the first vibration source 13 and the second vibration source 14, which are located inside the ear insertion part 11. However, for example, as shown in Figure 7A, it is preferable that the second vibration source 14 is located inside the ear insertion part 11 so as to be closer to the cartilage Ca surrounding the concha CC than the first vibration source 13 when the ear insertion part 11 is pressed against the concha CC. This makes it possible to suppress the attenuation of high-frequency vibrations and improve the reproducibility of sound.

[0047] In other words, high-frequency vibrations are generally attenuated more easily than low-frequency vibrations, as the amount of transmissive material increases. Therefore, inside the ear insertion part 11, when the device is worn in the user's concha (CC), the second vibration source 14, which is responsible for high-frequency vibrations, is positioned closer to the cartilage Ca than the first vibration source 13, which is responsible for low-frequency vibrations. By doing so, the vibrations of the second vibration source 14 are transmitted to the cartilage Ca before the vibrations of the first vibration source 13, thereby minimizing the attenuation of the vibrations of the second vibration source 14 and delivering a highly reproducible sound to the user. Furthermore, by positioning the second vibration source 14 closer to the cartilage Ca, it becomes possible to transmit high-frequency vibrations to the cochlea as much as possible.

[0048] Furthermore, there are no particular limitations on the vibration capabilities of the first vibration source 13 and the second vibration source 14, and they can be appropriately selected depending on the type of vibration source. Here, for example, as shown in Figure 7B, it is preferable that the maximum amplitude of the second vibration source 14 is designed to be greater than or equal to the maximum amplitude of the first vibration source 13. Here, the maximum amplitude of the vibration source refers to the maximum value of the displacement amount among the amplitude of vibration of the vibration source. This makes it possible to suppress the attenuation of vibrations on the high-frequency side and improve the reproducibility of sound.

[0049] In other words, as described above, since high-frequency vibrations are more easily attenuated than low-frequency vibrations, the maximum amplitude of the second vibration source 14, which is responsible for high-frequency vibrations, is set to be greater than or equal to the maximum amplitude of the first vibration source 13, which is responsible for low-frequency vibrations, thereby reinforcing the high-frequency vibrations in advance. As a result, when the vibrations of the second vibration source 14 and the first vibration source 13 are transmitted to the ear canal EC (external auditory canal) of the concha CC, even if the vibration of the second vibration source 14 is attenuated, it can be made to be about the same as the vibration of the first vibration source 13, thereby delivering a highly reproducible sound to the user.

[0050] In this invention, if the maximum amplitude of the second vibration source 14 is designed to be greater than or equal to the maximum amplitude of the first vibration source 13, the arrangement of the second vibration source 14 and the first vibration source 13 is not particularly limited, and a wide variety of configurations and arrangements can be realized.

[0051] For example, as shown in Figure 8, within the ear insertion portion 11, the second vibration source 14 may be positioned above the first vibration source 13, and the vibration plane of the second vibration source 14 may be positioned parallel to the vibration plane of the first vibration source 13.

[0052] Here, the first vibration source 13 may be positioned overlapping with the second vibration source 14 in the vertical space, or it may be positioned partially overlapping with the second vibration source 14 in the vertical space, or it may be positioned adjacent to the second vibration source 14 without overlapping in the vertical space.

[0053] Furthermore, as shown in Figure 8, within the ear insertion portion 11, the second vibration source 14 may be positioned above the first vibration source 13, and the first vibration source 13 and the second vibration source 14 may be positioned with their respective vibration planes perpendicular to each other.

[0054] Furthermore, as shown in Figure 8, within the ear insertion portion 11, the second vibration source 14 may be positioned above the first vibration source 13 at a predetermined inclination angle α, and the vibration surfaces of the first vibration source 13 and the second vibration source 14 may be positioned side by side in the same direction such that the inclination angle α between the vibration surface of the first vibration source 13 and the vibration surface of the second vibration source 14 is an acute angle.

[0055] Furthermore, there are no particular limitations on the configuration of the vibration control unit 15, but for example, it may be further equipped with adjustment circuits, switch circuits, filter circuits, etc., which do not have a signal receiving unit 12. Also, the vibration control unit 15 may be further equipped with an equalizer to adjust the vibration of the second vibration source 14 and the vibration of the first vibration source 13. For example, the vibration control unit 15 can adjust the vibrations on the high-frequency side and the low-frequency side by using an equalizer to strengthen the input audio signal to the second vibration source 14 on the high-frequency side and weaken the input audio signal to the first vibration source 13 on the low-frequency side.

[0056] Furthermore, while the present invention is configured to include two vibration sources, a first vibration source 13 and a second vibration source 14, which have different frequency bands, the invention is not limited to this configuration, and may be configured to include three or more different vibration sources.

[0057] For example, as shown in Figure 9, the third vibration source 16 is located inside the ear insertion part 11 and has vibration characteristics V3 in which the amplitude (mm) of the input audio signal in the frequency band shows a peak at a predetermined third frequency f3 (Hz) that is higher than the second frequency f2 (Hz), and can vibrate independently of the first vibration source 13 and the second vibration source 14.

[0058] As a result, when the first vibration source 13, the second vibration source 14, and the third vibration source 16 vibrate simultaneously, the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, and the vibration characteristics V3 of the third vibration source 16 overlap with each other to form a composite wave, and as a whole, a vibration characteristic V123 with an even wider frequency band is formed. This makes it possible to broaden the reproducible frequency band and improve sound quality.

[0059] Here, as long as the third vibration source 16 vibrates independently of the first vibration source 13 and the second vibration source 14, there is no particular need to limit it, and a wide variety of configurations and arrangements can be realized. For example, the third vibration source 16 can be arranged in a wide variety of ways with respect to the positional relationship between the first vibration source 13 and the second vibration source 14, as described above. For example, the vibration surface of the third vibration source 16 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the first vibration source 13, and this inclination angle α is set within the range of 0 to 180 degrees, as described above. Similarly, the vibration surface of the third vibration source 16 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the second vibration source 14.

[0060] Furthermore, as shown in Figure 9, a fourth vibration source 17 is provided, which is located inside the ear insertion part 11 and has vibration characteristics V4 in which the amplitude (mm) of the input audio signal in the frequency band shows a peak at a predetermined fourth frequency f4 (Hz) that is higher than the third frequency f3 (Hz), and can vibrate independently of the first vibration source 13, the second vibration source 14, and the third vibration source 16.

[0061] As a result, when the first vibration source 13, the second vibration source 14, the third vibration source 16, and the fourth vibration source 17 vibrate simultaneously, the vibration characteristics V1 of the first vibration source 13, V2 of the second vibration source 14, V3 of the third vibration source 16, and V4 of the fourth vibration source 17 overlap with each other to form a composite wave, resulting in the formation of a vibration characteristic V1234 with an even wider frequency band. This makes it possible to further broaden the reproducible frequency band and improve sound quality.

[0062] Here, as long as the fourth vibration source 17 vibrates independently of the first vibration source 13, the second vibration source 14, and the third vibration source 16, there is no particular need to limit it, and a wide variety of configurations and arrangements can be realized. For example, the fourth vibration source 17 can be arranged in a wide variety of positions relative to the first vibration source 13, the second vibration source 14, and the third vibration source 16, as described above. For example, the vibration surface of the fourth vibration source 17 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the first vibration source 13, and this inclination angle α is set within the range of 0 to 180 degrees, as described above. Similarly, the vibration surface of the fourth vibration source 17 may be configured to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the second vibration source 14. Furthermore, the vibration surface of the fourth vibration source 17 may be configured to be inclined with respect to the vibration surface of the third vibration source 16 at a predetermined inclination angle α (degrees).

[0063] Furthermore, although the above description explained the case where a third vibration source 16 and a fourth vibration source 17 are added, the same applies even when the number of vibration sources is further increased. [Examples]

[0064] Examples and comparative examples of the present invention will be described below in detail, but the application of the present invention is not limited to these examples.

[0065] In the field of acoustics, it was confirmed that staggered synchronization occurs and the frequency band is broadened by simultaneously vibrating two vibration sources with different frequency bands. First, as shown in Figure 10, two vibration sources 13 and 14 were prepared, and vibration control units 15 were connected to each of the two vibration sources 13 and 14, and the respective frequency bands of the two vibration sources 13 and 14 were set. Specifically, for the first vibration source 13, the vibration control unit 15 connected to the first vibration source 13 was adjusted so that the first peak f1 was on the low frequency side, and for the second vibration source 14, the vibration control unit 15 connected to the second vibration source 14 was adjusted so that the second peak f2 was on the high frequency side. Next, an oscilloscope 100 was connected to each of the vibration control units 15 of the two vibration sources 13 and 14, and the amplitudes of the two vibration sources 13 and 14 were adjusted while checking them with the oscilloscope 100. In addition, the two vibration sources 13 and 14 were synchronized while visually checking the oscilloscope 100. In other words, a bone conduction earphone 1, which virtually includes a first vibration source 13, a second vibration source 14, and a vibration control unit 15, was created as Example 1.

[0066] Next, a sound recording device 101 was set up at a predetermined distance from the two vibration sources 13 and 14. The amplitudes of the two vibration sources 13 and 14 were adjusted, causing the first vibration source 13 and the second vibration source 14 to vibrate and oscillate simultaneously, and the sound was measured by the measuring device 101. The sound received by the measuring device 101 was then analyzed to calculate the output sound amplitude for the simultaneous vibration of the first vibration source 13 and the second vibration source 14.

[0067] Figure 11 is a graph showing an example of the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, the theoretically combined theoretical vibration characteristics V12t, and the experimental vibration characteristics V12e obtained by analysis. Note that the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, the theoretical vibration characteristics V12t, and the experimental vibration characteristics V12e are shown as graphs of gain against frequency. However, since gain essentially represents vibration, and the units of gain differ between the theoretical vibration characteristics V12t and the experimental vibration characteristics V12e, the gains of the vibration characteristics V1 of the first vibration source 13, the vibration characteristics V2 of the second vibration source 14, and the theoretical vibration characteristics V12t are shown on the left axis of the graph, and the gain of the experimental vibration characteristics V12e is shown on the right axis. The gain of the experimental vibration characteristics V12e was plotted for each frequency, and an approximation curve was drawn. As shown in Figure 11, the curve for the experimental vibration characteristic V12e closely matched the curve for the theoretical vibration characteristic V12t. This confirmed the occurrence of staggered tuning and the expansion of the frequency band.

[0068] Example 1 demonstrates the effects of air vibration, but it is presumed that similar effects would also occur with vibrations in the concha (CC) or external auditory canal (EC). In this way, by simultaneously vibrating two vibration sources with different frequency bands, it should be possible to accurately reproduce any frequency range of sound and improve sound quality. [Industrial applicability]

[0069] As described above, the bone conduction earphones and method of using bone conduction earphones according to the present invention are useful not only for general bone conduction earphones but also in the field of bone conduction earphones for the hearing impaired and hard of hearing, and are effective bone conduction earphones and methods of using bone conduction earphones that enable accurate hearing of sounds in any frequency band and improve sound quality. [Explanation of Symbols]

[0070] 1. Bone conduction earphones 10 Sound collection section 11. Ear insertion part 12 Signal receiving section 13. The first source of vibration 14. Second source of vibration 15. Vibration control unit

Claims

1. A sound collection unit that collects external audio and converts it into an input audio signal corresponding to the external audio, An ear insertion part having a size that can be inserted into the recess of the user's concha cavity, A signal receiving unit is provided inside the ear insertion portion to receive the converted input audio signal, A first vibration source is provided inside the ear insertion portion and has vibration characteristics in which the amplitude of an input audio signal in a predetermined frequency band shows a peak at a predetermined first frequency. A second vibration source is provided inside the ear insertion portion and has vibration characteristics in which the amplitude of the input audio signal in the frequency band shows a peak at a predetermined second frequency higher than the first frequency, and is capable of vibrating independently of the first vibration source. A vibration control unit that simultaneously inputs the received input audio signal to the first vibration source and the second vibration source, Equipped with, One end of the ear insertion part is inserted into the recess of the user's concha, and the ear insertion part is pressed against the concha between the user's tragus and antitragus, causing the first vibration source and the second vibration source to vibrate simultaneously based on the external sound. Bone conduction earphones.

2. The second vibration source is provided inside the ear insertion portion so as to be closer to the cartilage surrounding the concha of the ear than the first vibration source when the ear insertion portion is pressed against the concha of the ear. The bone conduction earphone according to claim 1.

3. The maximum amplitude of the second vibration source is designed to be greater than or equal to the maximum amplitude of the first vibration source. The bone conduction earphone according to claim 1.

4. A sound collection unit that collects external audio and converts it into an input audio signal corresponding to the external audio, An ear insertion part having a size that can be inserted into the recess of the user's concha cavity, A signal receiving unit is provided inside the ear insertion portion to receive the converted input audio signal, A first vibration source is provided inside the ear insertion portion and has vibration characteristics in which the amplitude of an input audio signal in a predetermined frequency band shows a peak at a predetermined first frequency. A second vibration source is provided inside the ear insertion portion and has vibration characteristics in which the amplitude of the input audio signal in the frequency band shows a peak at a predetermined second frequency higher than the first frequency, and is capable of vibrating independently of the first vibration source. A vibration control unit that simultaneously inputs the received input audio signal to the first vibration source and the second vibration source, A method for using bone conduction earphones equipped with, A pressing step involves inserting one end of the ear insertion portion into a cavity in the user's concha and pressing the ear insertion portion against the concha between the user's tragus and antitragus, A vibration process in which the first vibration source and the second vibration source are simultaneously vibrated based on the external sound, How to use bone conduction earphones.

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