Bone conduction earphones and how to use them

Abstract

To provide a bone conduction earphone capable of improving sound quality. [Solution] In the bone conduction earphone 1, the sound collector 10 collects external sounds and converts them into an input sound signal corresponding to the external sounds. The ear insert 11 has a size that allows it to be inserted into the cavity of the user's concha. The signal receiver 12 is provided inside the ear insert and receives the converted input sound signal. The first vibration source 13 is provided inside the ear insert and has vibration characteristics in which the amplitude of an input sound signal of a predetermined frequency band shows a peak at a predetermined first frequency. The second vibration source 14 is provided inside the ear insert and has vibration characteristics in which the amplitude of an input sound signal of a frequency band shows a peak at a predetermined second frequency higher than the first frequency, and can vibrate independently of the first vibration source. The vibration controller 15 inputs the received input sound signal to the first vibration source and the second vibration source simultaneously.

Description

[Technical field]

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

[0002] Conventionally, there are many kinds of technologies related to earphones (also called ear inserts, piezoelectric vibration devices, etc.) that improve sound quality. For example, Japanese Patent Application Laid-Open Publication No. 2012-222682 (Patent Document 1) discloses a bone conduction earphone including a bone conduction vibration unit, a front side convex portion, and a back side convex portion. The bone conduction vibration unit is formed on an ellipsoid and generates sound vibration. The front side convex portion is provided to protrude from one end side of the bone conduction vibration unit in the length direction and on the front side in the thickness direction. The back side convex portion is provided to protrude from one end side of the bone conduction vibration unit in the length direction and on the back side in the thickness direction. When the one end side of the bone conduction vibration unit in the length direction is inserted into the depression of the concha cavity and rotated so that the lower part of the bone conduction vibration unit in the width direction is in close contact with the bottom of the depression of the concha cavity and worn, the bone conduction earphone is in pressure contact with the tragus, the concha cavity, the antitragus, and the periphery of the entrance of the ear canal. Here, the bone conduction vibration unit is composed of a piezoelectric ceramic vibrator. This provides excellent reproducibility of audio information, makes it easy to insert into the cavity of the concha, and provides excellent support stability after attachment.

[0003] In addition, JP 2018-191140 A (Patent Document 2) discloses a piezoelectric vibration device including a plurality of piezoelectric vibrators, a support, and a vibration transmission unit. The plurality of piezoelectric vibrators have a plate-shaped vibrating body and a plate-shaped piezoelectric body provided on the surface of the vibrating body. The support supports each of the plurality of piezoelectric vibrators. The vibration transmission unit is flexible and transmits the vibration of each of the plurality of piezoelectric vibrators. Next, each of the plurality of piezoelectric vibrators has a through hole penetrating the vibrating body and the piezoelectric body in the thickness direction, and is provided in parallel to each other at intervals in the thickness direction. The support has a rod-shaped support that is inserted into each of the through holes of the plurality of piezoelectric vibrators. The vibration transmission unit is in contact with each of the adjacent piezoelectric vibrators among the plurality of piezoelectric vibrators and is arranged between them. It is said that this makes it possible to synchronize the vibration of each of the plurality of piezoelectric vibrators.

[0004] In addition, JP 2017-076919 A ​​(Patent Document 3) discloses an earphone configured to support two parts of the same electromagnetic vibrator that move relative to each other with an elastic body interposed therebetween. This earphone is configured to extract vibration for cartilage conduction from at least one of the two parts. As a result, it is said that as a method of using a bone conduction speaker, the pressure with which the vibration surface that is in contact with the tragus is in contact with the tragus can be adjusted manually. It is also said that the transmission ratio of audio information via cartilage conduction and audio information via air conduction can be changed according to the level of external noise.

[0005] On the other hand, although it is not in the technical field of earphones, as a device using multiple transducers, JP 2020-141354 A (Patent Document 4) discloses an underwater ultrasonic transducer used in a transducer. 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 the rear mass form a resonance system of the low-frequency piezoelectric transducer and are for sandwiching the low-frequency piezoelectric transducer between each other. The acoustic matching layer is disposed on the acoustic radiation 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 ensure a desired range of motion for the transmission voltage sensitivity. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2012-222682 [Patent Document 2] JP 2018-191140 A [Patent Document 3] Special Publication No. 2017-076919 [Patent Document 4] JP 2020-141354 A Summary of the Invention [Problem to be solved by the invention]

[0007] Bone conduction earphones use a vibration source that vibrates at an amplitude corresponding to the audio signal. This vibration source means an element that generates vibration, and corresponds to a diaphragm, a vibrator, a vibration element, etc., and specific examples include a piezoelectric ceramic vibrator, an electromagnetic vibrator, and a giant magnetostrictive vibrator.

[0008] Here, a vibration source generally has vibration characteristics that show a peak where the amplitude (output) becomes large at a certain 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 characteristics exists on the low frequency side, when the input audio signal is on the low frequency side, the vibration source vibrates with a large amplitude, making it easier for the user to hear. On the other hand, when the input audio signal is on the high frequency side, the vibration source vibrates with a small amplitude, making it difficult for the user to hear. In other words, bone conduction earphones have a problem in that the quality of the sound (sound quality) that the user can hear varies depending on the vibration characteristics of the vibration source.

[0009] In particular, since the vibration characteristics of the vibration source usually have a peak on the low frequency side, the amplitude of the vibration source is small in the input high frequency side audio signal, and the user often has difficulty in hearing. For example, characters that make up a language generally include vowels and consonants, and Japanese vowels are the characters "a", "i", "u", "e", and "o", and Japanese consonants are characters other than Japanese vowels. Also, English vowels are the characters "a", "e", "i", "o", and "u", and English consonants are characters other than English vowels. Here, generally, in other languages, vowels are on the low frequency side and consonants are on the high frequency side, so that normal bone conduction earphones have difficulty reproducing the vibration of consonants in the high frequency band, and there is a problem that users have difficulty in hearing consonants. Therefore, there has been a demand for bone conduction earphones that have a large amplitude and are easy for users to hear regardless of the frequency band of the audio.

[0010] In particular, for users who are hearing impaired or hard of hearing, it is important to convey both high-frequency and low-frequency sounds accurately. In addition, even if only high-frequency consonants can be clearly heard, the range of sounds that hearing impaired or hard of hearing people can understand will be expanded, and their understanding of sounds from the outside world will be improved.

[0011] Here, in the technology described in Patent Document 1, the bone conduction vibration part is a single piezoelectric ceramic. In the technology described in Patent Document 2, a plurality of piezoelectric vibrators are connected (contacted) to synchronize the overall vibration and increase the output as sound. In the technology described in Patent Document 3, the same electromagnetic vibrator is used to facilitate vibration extraction. 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, a single vibrator or a plurality of identical vibrators are used, so there is a high possibility that one vibration characteristic appears as a whole, and the above-mentioned problem cannot be solved. In the technology described in Patent Document 4, a plurality of different vibrators are stacked to increase the strength of the vibration as a whole, so the vibration characteristic is the same as that of a single vibrator, and the above-mentioned problem cannot be solved.

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

[0013] The bone conduction earphone according to the present invention includes a sound collection unit, an ear insertion unit, a signal receiving unit, a first vibration source, a second vibration source, and a vibration control unit. The sound collection unit collects external sound and converts it into an input sound signal corresponding to the external sound. The ear insertion unit has a size that allows it to be inserted into a cavity of the user's concha. The signal receiving unit is provided inside the ear insertion unit and receives the converted input sound signal. The first vibration source is provided inside the ear insertion unit and has vibration characteristics in which the amplitude of an input sound signal of a predetermined frequency band shows a peak 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 sound signal of the frequency band shows a peak at a predetermined second frequency higher than the first frequency, and can vibrate independently of the first vibration source. The vibration control unit inputs the received input sound signal to the first vibration source and the second vibration source simultaneously. The bone conduction earphone of the present invention has one end of the ear insertion portion inserted into a recess in the user's concha cavity, and the ear insertion portion is pressed against the concha cavity between the user's tragus and antitragus, and the first vibration generating source and the second vibration generating source are vibrated simultaneously based on the external sound.

[0014] A method of using a bone conduction earphone according to the present invention includes a pressure contact step and a vibration step. The pressure contact step is to insert one end of the ear insertion part into a recess of the user's concha cavity and press the ear insertion part against the concha cavity between the user's tragus and antitragus. The vibration step is to simultaneously vibrate the first vibration generating source and the second vibration generating source based on the external sound. Effect of the Invention

[0015] According to the present invention, it is possible to accurately reproduce sounds in any frequency band, thereby improving sound quality. [Brief description of the drawings]

[0016] [Figure 1] 1A and 1B are a plan view and a front view showing an example of a bone conduction earphone according to an embodiment of the present invention; [Diagram 2] 1 is a graph showing an example of an output audio amplitude of the conventional technology and an output audio amplitude of the present invention relative to an input audio signal. [Diagram 3] 1A to 1C are front views showing an example of a bone conduction earphone according to an embodiment of the present invention before and after insertion into a cavity of the user's concha. [Figure 4] FIG. 1 is a schematic diagram showing an example of a prior art output audio amplitude for an input audio signal containing low and high frequency audio. [Diagram 5] FIG. 2 is a schematic diagram showing an example of the output audio amplitude of the present invention for an input audio signal including low-frequency and high-frequency audio. [Figure 6] 1A and 1B are a plan view and a front view showing an example of a configuration in which the arrangement of a first vibration generating source and a second vibration generating source is changed. [Figure 7] FIG. 7A is a front cross-sectional view showing an example in which the arrangement of the first vibration generating source and the second vibration generating source is changed, and FIG. 7B is a front cross-sectional view showing an example in which the size of the first vibration generating source and the second vibration generating source is changed. [Figure 8] 11A and 11B are a plan view and a front view, respectively, showing an example of a configuration in which the arrangement is changed when the sizes of a first vibration generating source and a second vibration generating source are changed. [Figure 9] FIG. 11 shows a plan view sectional view and a front view sectional view showing an example of a case where a third vibration generating source is further provided, and a graph of output audio amplitude; and FIG. 11 shows a plan view sectional view and a front view sectional view showing an example of a case where a third vibration generating source and a fourth vibration generating source are further provided, and a graph of output audio amplitude. [Figure 10] FIG. 1 is a schematic diagram showing a virtual bone conduction earphone embodiment 1 and an experimental situation. [Figure 11] 11 is a graph showing an example of vibration characteristics of a first vibration source, vibration characteristics of a second vibration source, theoretically synthesized theoretical vibration characteristics, and experimental vibration characteristics obtained by analysis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings to help the understanding of the present invention. Note that the following embodiment is an example of the present invention and is not intended to limit the technical scope of the present invention.

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

[0019] Here, the sound collection unit 10 collects external sounds and converts them into input sound signals corresponding to the external sounds. The sound collection unit 10 can be, for example, a microphone.

[0020] Moreover, ear insertion section 11 has a size that allows it to be inserted into the cavity of the user's concha. Here, ear insertion section 11 is configured in an elliptical disk shape, for example, as shown in Fig. 1. Moreover, an elliptical disk shape means an elliptical shape with a certain thickness, and can be inserted into the cavity of the user's concha.

[0021] Moreover, the signal receiving unit 12 is provided inside the ear insert unit 11 and receives the converted input audio signal. Here, for example, as shown in FIG. 1, when the signal receiving unit 12 is connected to the sound collecting unit 10 by wireless communication, the signal receiving unit 12 can receive the input audio signal from the sound collecting unit 10 via wireless communication. Here, examples of wireless communication include Bluetooth (registered trademark). Also, when the signal receiving unit 12 is connected to the sound collecting unit 10 by wired communication, the signal receiving unit 12 can receive the input audio signal from the sound collecting unit 10 via an electric wire.

[0022] The first vibration source 13 is provided inside the ear insertion unit 11, and has a vibration characteristic V1 in which the amplitude (output) Amplitude (mm) peaks at a predetermined first frequency f1 (Hz) for an input audio signal of a predetermined frequency band f. Here, the vibration source means an element that generates vibration, and corresponds to a diaphragm, a vibrator, a vibration element, etc. In addition, when the input audio signal has a constant amplitude Amplitude (mm) in a region of a predetermined frequency f (for example, 10 Hz to 6000 Hz) as shown in FIG. 2, the first vibration source 13 receives the input audio signal and outputs vibration of an amplitude Amplitude (mm) that peaks at the first frequency f1 (Hz).

[0023] 2, the vibration surface of the first vibration generating source 13 is disposed facing upward of the ear insertion portion 11. Here, the vibration surface is a surface that outputs vibration, and a vibration generating source usually has a vibration surface that generates vibration in one direction.

[0024] The second vibration source 14 is provided inside the ear insertion portion 11, has a vibration characteristic V2 in which the amplitude (mm) shows a peak at a predetermined second frequency f2 (Hz) higher than the first frequency f1 (Hz) for an input audio signal of a frequency band, and can vibrate independently of the first vibration source 13. Here, when the input audio signal has a constant amplitude (mm) in the range of the predetermined frequency f (10 Hz to 6000 Hz) as described above, the second vibration source 14 receives the input audio signal and outputs vibration of an amplitude (mm) showing a peak at the second frequency f2 (Hz). In FIG. 2, the vibration surface of the second vibration source 14 is arranged to face the same direction as the vibration surface of the first vibration source 13.

[0025] Here, the second vibration source 14 vibrating independently of the first vibration source 13 means that the first vibration source 13 and the second vibration source 14 vibrate separately without contacting each other. When the first vibration source 13 and the second vibration source 14 are close to each other, the vibrations of the first vibration source 13 and the first vibration source 14 may partially interfere with each other and cancel each other out, but since the first vibration source 13 and the second vibration source 14 vibrate in different specific frequency bands, the vibration output as a whole will have a wider frequency band.

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

[0027] In the field of electronic circuits, this is called staggered tuning. Staggered tuning means that multiple tuning circuits with different frequency bands are connected to widen the frequency band to obtain the required frequency band. In the present invention, this phenomenon is applied to bone conduction earphones in the acoustic field, which is different from the field of electronic circuits.

[0028] As a result, when the first vibration source 13 and the second vibration source 14 vibrate simultaneously, the frequency band in which the amplitude (mm) exists is wider than when the first vibration source 13 and the second vibration source 14 each vibrate individually, and it is possible to increase the amplitude (mm) and vibrate any frequency band of sound.

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

[0030] As shown in Fig. 3, the bone conduction earphone 1 according to the embodiment of the present invention inserts one end 11a of the ear insertion part 11 into a cavity of the user's concha cavity CC, presses the ear insertion part 11 against the concha cavity CC between the user's tragus T and antitragus A, and vibrates the first vibration generating source 13 and the second vibration generating source 14 simultaneously based on an external sound. An ear canal EC is present deep inside the cavity of the concha cavity CC. 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 vibration is transmitted from the ear canal EC to the cartilage Ca and then to the cochlea.

[0031] This makes it possible to accurately reproduce sounds in any frequency band, and improves sound quality. That is, as explained in Fig. 2, when the first vibration generating source 13 and the second vibration generating source 14 vibrate simultaneously, a vibration characteristic V12 with a wider frequency band is formed. This vibration characteristic V12 is important.

[0032] For example, as shown in FIG. 4, in the conventional technology, if an input sound signal having various frequency bands is vibrated only by the first vibration generating source 13, the peak of the first frequency f1 (Hz) in the vibration characteristic V1 of the first vibration generating source 13 is biased toward the low frequency side, so that the output sound amplitude of the first vibration generating source 13 is large only on the low frequency side. In other words, the output sound amplitude is rapidly reduced on the high frequency side compared to the input sound signal. For example, when the first vibration generating source 13 of the ear inserting portion 11 vibrates while being pressed against the cavity of the concha CC, the vibration is transmitted to the external auditory canal EC and the surrounding cartilage Ca, but the vibration amplitude on the high frequency side is rapidly reduced, and only the vibration amplitude on the low frequency side remains. Therefore, when a user hears this, for example, only the sound on the low frequency side becomes louder, specifically, only the sound of the vowel becomes louder. In this case, the user will recognize only the vowels as loud, and it will be difficult to understand sounds including consonants.

[0033] In addition, in the 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 toward the high frequency side, so that the output audio amplitude of the second vibration source 14 is large only on the high frequency side. In other words, the output audio amplitude is rapidly reduced 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 being pressed against the cavity of the concha CC, the vibration is transmitted to the external auditory canal EC and the surrounding cartilage Ca, but the amplitude of the vibration on the low frequency side is rapidly reduced, and only the amplitude of the vibration on the high frequency side remains. Therefore, when a user hears this, for example, only the voice on the high frequency side becomes loud, and then only the voice of the consonant becomes loud. In this case, the user recognizes only the consonant as being loud, and it becomes difficult to understand the voice including the vowel.

[0034] Therefore, as shown in FIG. 5, in the present invention, when an input sound signal having various frequency bands is vibrated simultaneously by the first vibration generating source 13 and the second vibration generating source 14, the overall vibration characteristic V12 has a large amplitude in a wide frequency range, so that the overall output sound amplitude is large at both low and high frequencies. In other words, the output sound amplitude is reproduced to a waveform equivalent to that of the input sound signal without decreasing in amplitude at both low and high frequencies compared to the input sound signal. For example, when the first vibration generating source 13 and the second vibration generating source 14 of the ear inserting portion 11 vibrate while being pressed against the cavity of the concha CC, the vibration is transmitted to the external auditory canal EC and the surrounding cartilage Ca, but since the first vibration generating source 13 excels at vibration on the low frequency side and the second vibration generating source 14 excels at vibration on the high frequency side, the vibration on the low frequency side and the vibration on the high frequency side do not decrease. Therefore, when the user hears this, for example, it sounds loud at both low and high frequencies, so that vowels and consonants can be clearly heard. This makes it possible to accurately reproduce sounds of any frequency band, improving sound quality.

[0035] Here, in the present invention, as long as the second vibration source 14 is configured to vibrate independently of the first vibration source 13, there is no need to be particularly limited, and a wide variety of configurations and arrangements can be realized.

[0036] For example, in FIG. 1, the first vibration generating source 13 and the second vibration generating source 14 are configured to be arranged side by side in a direction perpendicular to the vibration plane, but this is not limited thereto. For example, as shown in FIG. 6, inside the ear insertion portion 11, the first vibration generating source 13 and the second vibration generating source 14 may be arranged side by side with their vibration planes in the horizontal direction without contacting each other, or the first vibration generating source 13 and the second vibration generating source 14 may be arranged so as to partially overlap in the vertical space.

[0037] 6, the first vibration generating source 13 and the second vibration generating source 14 may be arranged inside the ear insertion portion 11 with their vibration surfaces inclined toward the outside at a predetermined inclination angle α (degrees). There is no particular limitation on the inclination angle α formed between the vibration surfaces of the first vibration generating source 13 and the second vibration generating source 14, and it may be set within the range of 0 degrees to 180 degrees, for example.

[0038] Here, when the inclination angle α is 180 degrees, the vibration plane of the first vibration source 13 and the vibration plane of the second vibration source 14 are arranged side by side in the horizontal direction and facing the same direction. When the inclination angle α is 90 degrees, the vibration plane of the first vibration source 13 is arranged side by side in the perpendicular direction to the vibration plane of the second vibration source 14. When the inclination angle α is 0 degree, the vibration plane of the first vibration source 13 is arranged side by side in the horizontal direction to the vibration plane of the second vibration source 14 and facing a different direction.

[0039] 6, the first vibration generating source 13 and the second vibration generating source 14 may be arranged in parallel with their vibration surfaces facing outward inside the ear insertion portion 11. As shown in Fig. 6, the first vibration generating source 13 and the second vibration generating source 14 may be arranged in a perpendicular direction inside the ear insertion portion 11. Here, in Fig. 6, the vibration surface of the first vibration generating source 13 is arranged in a perpendicular direction to the vibration surface of the second vibration generating source 14 near the lower center of the vibration surface of the second vibration generating source 14, but the arrangement is not limited thereto.

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

[0041] Furthermore, the shape of ear insertion portion 11 is appropriately designed and modified depending on the configuration and arrangement of first vibration generating source 13 and second vibration generating source 14, but it may be an elliptical disk as shown in FIG. 1, or it may be cylindrical or hemispherical as shown in FIG. 5.

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

[0043] Furthermore, there is no particular limitation on the configuration of the signal receiving unit 12, but for example, it may be an electrical circuit that receives an input audio signal, or it may further include an adjustment circuit that adjusts the magnitude of the input audio signal, a switch circuit that controls the power supply on and off, or a filter circuit that blocks noise signals contained in the input audio signal, or a combination of these.

[0044] Furthermore, the types of the first vibration generating source 13 and the second vibration generating source 14 are not particularly limited, and examples thereof include a piezoelectric ceramic vibrator, an electromagnetic vibrator, a giant magnetostrictive vibrator, etc. Furthermore, the first vibration generating source 13 and the second vibration generating source 14 may be of the same type or different types.

[0045] Furthermore, there is no particular limitation on the configuration of the first vibration generating source 13 and the second vibration generating source 14. For example, when the first vibration generating source 13 is a first diaphragm and the second vibration generating source 14 is a second diaphragm, the first vibration generating source 13 and the second vibration generating 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. Furthermore, the first vibration generating source 13 and the second vibration generating source 14 may be configured by incorporating the first diaphragm and the second diaphragm as a single device and configuring the first diaphragm and the second diaphragm to vibrate independently.

[0046] Furthermore, there is no particular limitation on the positional relationship between the first vibration generating source 13 and the second vibration generating source 14 disposed inside the ear insertion portion 11, but for example, as shown in Fig. 7A, the second vibration generating source 14 is preferably provided inside the ear insertion portion 11 so that when the ear insertion portion 11 is pressed against the cavity of the concha CC, it is closer to the cartilage Ca present around the cavity of the concha CC than the first vibration generating source 13. This makes it possible to suppress the attenuation of vibrations on the high frequency side and improve the reproducibility of sound.

[0047] That is, in general, the higher the frequency of vibration, the more the transmitter is present, and the more easily the vibration is attenuated compared to the vibration of the lower frequency. Therefore, inside the ear insertion part 11, when the device is attached to the cavity of the concha CC of the user, the second vibration generating source 14 that generates the vibration of the higher frequency is arranged closer to the cartilage Ca than the first vibration generating source 13 that generates the vibration of the lower frequency. This allows the vibration of the second vibration generating source 14 to be transmitted to the cartilage Ca before the vibration of the first vibration generating source 13, thereby minimizing the attenuation of the vibration of the second vibration generating source 14 and delivering a sound with good reproducibility to the user. In addition, by placing the second vibration generating source 14 closer to the cartilage Ca, it is possible to transmit the vibration of the higher frequency to the cochlea as much as possible.

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

[0049] That is, since high-frequency vibrations are more easily attenuated than low-frequency vibrations as described above, the maximum amplitude of the second vibration generating source 14 which is responsible for the high-frequency vibrations is set to be equal to or greater than the maximum amplitude of the first vibration generating source 13 which is responsible for the low-frequency vibrations, thereby strengthening the high-frequency vibrations in advance. As a result, when the vibrations of the second vibration generating source 14 and the first vibration generating source 13 are transmitted to the external auditory canal EC of the cavity of the concha CC, even if the vibration of the second vibration generating source 14 is attenuated, it is possible to deliver sound with good reproducibility to the user by making it approximately the same as the vibration of the first vibration generating source 13.

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

[0051] For example, as shown in FIG. 8, inside the ear insertion portion 11, the second vibration generating source 14 may be disposed above the first vibration generating source 13, and the vibration surface of the second vibration generating source 14 may be disposed parallel to the vibration surface of the first vibration generating source 13.

[0052] Here, the first vibration source 13 may be arranged so as to overlap with the second vibration source 14 in the space above and below, the first vibration source 13 may be arranged so as to overlap only partially with the second vibration source 14 in the space above and below, or the first vibration source 13 may be arranged adjacent to the second vibration source 14 without overlapping with the second vibration source 14 in the space above and below.

[0053] Also, as shown in FIG. 8, inside the ear insertion portion 11, the second vibration generating source 14 may be disposed above the first vibration generating source 13, and the first vibration generating source 13 and the second vibration generating source 14 may be disposed with their vibration planes aligned at right angles to each other.

[0054] Furthermore, as shown in FIG. 8, inside the ear insertion portion 11, the second vibration source 14 may be arranged tilted upward with respect to the first vibration source 13 at a predetermined tilt angle α, and the vibration plane of the first vibration source 13 and the vibration plane of the second vibration source 14 may be arranged side by side in the same direction so that the tilt angle α between the vibration plane of the first vibration source 13 and the vibration plane of the second vibration source 14 is an acute angle.

[0055] Furthermore, there is no particular limitation on the configuration of the vibration control unit 15, and for example, the vibration control unit 15 may further include an adjustment circuit, a switch circuit, a filter circuit, etc. that are not provided in the signal receiving unit 12. The vibration control unit 15 may further include an equalizer to adjust the vibration of the second vibration generating source 14 and the vibration of the first vibration generating source 13. For example, the vibration control unit 15 can adjust the vibration on the high frequency side and the vibration on the low frequency side by using the equalizer to strengthen the input audio signal to the second vibration generating source 14 on the high frequency side and weaken the input audio signal to the first vibration generating source 13 on the low frequency side.

[0056] In addition, in the present invention, the device is configured to have two vibration generating sources, the first vibration generating source 13 and the second vibration generating source 14, which have different frequency bands, but this is not limited to the above, and the device may be configured to have three or more different vibration generating sources.

[0057] For example, as shown in FIG. 9, the third vibration source 16 is provided inside the ear insertion portion 11, has a vibration characteristic V3 in which the amplitude (mm) shows a peak at a predetermined third frequency f3 (Hz) higher than the second frequency f2 (Hz) for an input audio signal of a frequency band, and is capable of vibrating 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 characteristic V1 of the first vibration source 13, the vibration characteristic V2 of the second vibration source 14, and the vibration characteristic 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 a wider frequency band is formed. This makes it possible to widen the reproducible frequency band and improve the sound quality.

[0059] Here, as long as the third vibration source 16 is configured to vibrate independently of the first vibration source 13 and the second vibration source 14, there is no need to be any particular limitation, 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 positions relative to the first vibration source 13 and the second vibration source 14, as described above. For example, the third vibration source 16 may be configured so that the vibration surface of the third vibration source 16 is inclined at a predetermined inclination angle α (degrees) relative to the vibration surface of the first vibration source 13, and this inclination angle α is set within a range of 0 degrees to 180 degrees, as described above. Similarly, the third vibration source 16 may be configured so that the vibration surface of the third vibration source 16 is inclined at a predetermined inclination angle α (degrees) relative to the vibration surface of the second vibration source 14.

[0060] Furthermore, as shown in FIG. 9, a fourth vibration source 17 is provided. The fourth vibration source 17 is provided inside the ear insertion portion 11, and has a vibration characteristic V4 in which the amplitude (mm) for an input audio signal of a frequency band shows a peak at a predetermined fourth frequency f4 (Hz) higher than the third frequency f3 (Hz), and is capable of vibrating 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 characteristic V1 of the first vibration source 13, the vibration characteristic V2 of the second vibration source 14, the vibration characteristic V3 of the third vibration source 16, and the vibration characteristic V4 of the fourth vibration source 17 overlap each other to form a composite wave, and as a whole, a vibration characteristic V1234 with a wider frequency band is formed. This makes it possible to further expand the reproducible frequency band and improve the sound quality.

[0062] Here, as long as the fourth vibration source 17 is configured to vibrate independently of the first vibration source 13, the second vibration source 14, and the third vibration source 16, there is no need to be particularly limited, 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 positional relationships with the first vibration source 13, the second vibration source 14, and the third vibration source 16, as described above. For example, the fourth vibration source 17 may be configured so that the vibration surface of the fourth vibration source 17 is 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 a range of 0 degrees to 180 degrees, as described above. Similarly, the fourth vibration source 17 may be configured so that the vibration surface of the fourth vibration source 17 is inclined at a predetermined inclination angle α (degrees) with respect to the vibration surface of the second vibration source 14. Moreover, the vibration plane of the fourth vibration generating source 17 may be arranged to be inclined at a predetermined inclination angle α (degrees) with respect to the vibration plane of the third vibration generating source 16 .

[0063] In the above, the case where the third vibration generating source 16 and the fourth vibration generating source 17 are added has been described, but this is not limited thereto, and the same applies even if more vibration generating sources are added. 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 has been confirmed that staggered tuning occurs and the frequency band is widened by simultaneously vibrating two vibration sources of different frequency bands. First, as shown in FIG. 10, two vibration sources 13 and 14 are prepared, a vibration control unit 15 is connected to each of the two vibration sources 13 and 14, and the frequency bands of the two vibration sources 13 and 14 are set. That is, in the first vibration source 13, the vibration control unit 15 connected to the first vibration source 13 is adjusted so that the first peak f1 is on the low frequency side, and in the second vibration source 14, the vibration control unit 15 connected to the second vibration source 14 is adjusted so that the second peak f2 is on the high frequency side. Next, an oscilloscope 100 is 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 are adjusted while checking with the oscilloscope 100. Also, the two vibration sources 13 and 14 are synchronized while checking with the oscilloscope 100 visually. That is, a virtual bone conduction earphone 1 equipped with a first vibration generating source 13, a second vibration generating source 14, and a vibration control unit 15 was created as Example 1.

[0066] Next, a measuring device 101 capable of recording sound was placed at a predetermined distance from the two vibration sources 13, 14, the amplitudes of the two vibration sources 13, 14 were adjusted, and the first vibration source 13 and the second vibration source 14 were vibrated and oscillated simultaneously, and the sound was measured by the measuring device 101. The sound received by the measuring device 101 was then analyzed, and the output sound amplitude for the simultaneous vibration of the first vibration source 13 and the second vibration source 14 was calculated.

[0067] 11 is a graph showing an example of the vibration characteristic V1 of the first vibration source 13, the vibration characteristic V2 of the second vibration source 14, the theoretical vibration characteristic V12t theoretically synthesized, and the experimental vibration characteristic V12e obtained by analysis. The vibration characteristic V1 of the first vibration source 13, the vibration characteristic V2 of the second vibration source 14, the theoretical vibration characteristic V12t, and the experimental vibration characteristic V12e are shown in a graph of gain against frequency, but the gain essentially means vibration, and the theoretical vibration characteristic V12t and the experimental vibration characteristic V12e have different units of gain, so the gains of the vibration characteristic V1 of the first vibration source 13, the vibration characteristic V2 of the second vibration source 14, and the theoretical vibration characteristic V12t are shown on the left axis of the graph, and the gain of the experimental vibration characteristic V12e is shown on the right axis of the graph. The gain of the experimental vibration characteristic V12e was plotted for each frequency, and an approximate curve was drawn. As shown in Fig. 11, the curve of the experimental vibration characteristic V12e was almost identical to the curve of the theoretical vibration characteristic V12t. This confirmed the occurrence of staggered tuning and the expansion of the frequency band.

[0068] Although the first embodiment shows the effect of air vibration, it is presumed that the same effect can be obtained by vibration in the cavity of the concha CC or the ear canal EC. In this way, by simultaneously vibrating two vibration sources with different frequency bands, it is possible to accurately reproduce sounds of any frequency band, and improve sound quality. [Industrial Applicability]

[0069] As described above, the bone conduction earphones and methods of using the bone conduction earphones of the present invention are useful not only in the field of general bone conduction earphones, but also in the field of bone conduction earphones for the hearing impaired and hard of hearing, and are effective as bone conduction earphones and methods of using bone conduction earphones that can accurately hear sounds of any frequency band and improve sound quality. [Explanation of symbols]

[0070] 1. Bone conduction earphones 10 Sound collection section 11 Ear Insert 12 Signal receiving section 13 First source of vibration 14 Secondary source of vibration 15 Vibration control section

Claims

1. A bone conduction earphone having at least two vibration generating sources, a sound collection unit that collects external sound and converts it into an input sound signal corresponding to the external sound; an ear insertion portion having a size that allows it to be inserted into a cavity of the user's concha; a signal receiving unit provided inside the ear insert unit and receiving the converted input audio signal; a first vibration generating source provided inside the ear insertion portion and having vibration characteristics in which an amplitude of an input audio signal in a predetermined frequency band exhibits a peak at a predetermined first frequency; a second vibration generating source that is provided inside the ear insert portion so as to be closer to cartilage present around the concha cavity than the first vibration generating source when the ear insert portion is pressed against the concha cavity, the second vibration generating source having vibration characteristics that, for an input audio signal in the frequency band, exhibits a peak in amplitude at a predetermined second frequency higher than the first frequency, and that can vibrate independently of the first vibration generating source; a vibration control unit that simultaneously inputs the received input audio signal to the first vibration generating source and the second vibration generating source; Equipped with One end of the ear insertion portion is inserted into a recess of the user's concha cavity, and the ear insertion portion is pressed against the concha cavity between the user's tragus and antitragus, and the first vibration generating source and the second vibration generating source are vibrated simultaneously based on the external sound, so that the vibrations of the first vibration generating source and the second vibration generating source are independently transmitted to the user's external auditory canal and surrounding cartilage. Bone conduction earphones.

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

3. A bone conduction earphone having at least two vibration generating sources, a sound collection unit that collects external sound and converts it into an input sound signal corresponding to the external sound; an ear insertion portion having a size that allows it to be inserted into a cavity of the user's concha; a signal receiving unit provided inside the ear insert unit and receiving the converted input audio signal; a first vibration generating source provided inside the ear insertion portion and having vibration characteristics in which an amplitude of an input audio signal in a predetermined frequency band exhibits a peak at a predetermined first frequency; a second vibration generating source that is provided inside the ear insert portion so as to be closer to cartilage present around the concha cavity than the first vibration generating source when the ear insert portion is pressed against the concha cavity, the second vibration generating source having vibration characteristics that, for an input audio signal in the frequency band, exhibits a peak in amplitude at a predetermined second frequency higher than the first frequency, and that can vibrate independently of the first vibration generating source; a vibration control unit that simultaneously inputs the received input audio signal to the first vibration generating source and the second vibration generating source; A method for using a bone conduction earphone comprising: a pressing step of inserting one end of the ear insertion portion into a recess of the user's concha cavity and pressing the ear insertion portion against the concha cavity between the user's tragus and antitragus; a vibration step of simultaneously vibrating the first vibration generating source and the second vibration generating source based on the external sound, and independently transmitting the vibration of the first vibration generating source and the vibration of the second vibration generating source to the user's ear canal and surrounding cartilage; A method for using a bone conduction earphone having the same.

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