Patent Application
20240223957
The present invention relates to a vibrator and a hearing device.
Conventionally, various devices that transmit vibration to a target object to enable sound perception, such as bone conduction devices, bone conduction speakers, and bone conduction vibrators, have been developed (Patent Documents 1 to 5).
Inconveniently, these devices still leave much room for further studies.
In view of the above situation, an object of the present invention is to provide more useful vibrators and hearing devices.
To achieve the above object, according to one aspect of the present invention, a vibrator includes a yoke that is open at its top end and that has a bottom portion and a circumferential wall portion, a coil bobbin of which at least part is arranged inside the yoke, a coil that is wound around the coil bobbin, a magnet of which at least part is arranged inside the coil bobbin, a damper that supports the yoke, a frame that fixes the damper to the yoke, and a case for housing the yoke, the coil bobbin, the coil, the magnet, the damper, and the frame. An outer edge portion of the damper is fixed to the case. The bottom face of an inner edge portion of the damper makes contact with the top end of the circumferential wall portion of the yoke, and the frame is swaged to be fixed to the damper and the yoke so as to make contact with the top face of the inner edge portion of the damper and with the inner surface of the circumferential wall portion of the yoke.
According to another aspect of the present invention, the top end of the coil bobbin may make contact with the inner surface of the case.
According to another aspect of the present invention, there may be further provided a top plate arranged inside the coil bobbin. The magnet may include a first magnet and a second magnet. The first magnet may be arranged over the top plate, and the second magnet may be arranged under the top plate.
According to another aspect of the present invention, the shape of the inner bottom of the yoke may correspond to the shape of the bottom end of the second magnet so that the bottom end of the second magnet can be fixed inside the yoke.
According to another aspect of the present invention, the frame and the yoke may be formed of a soft magnetic material or soft magnetic materials.
According to another aspect of the present invention, at least parts of the frame and the circumferential wall portion of the yoke may face the coil.
According to another aspect of the present invention, the damper may have a through hole formed in it so as to penetrate the damper in an up-down direction.
According to another aspect of the present invention, the case may include an upper case and a lower case, and the outer edge portion of the damper is held between the upper case and the lower case.
According to the present invention, the upper case may have a wiring hole through which a cable is passed.
According to another aspect of the present invention, there may be further provided a closing member for covering the wiring hole so that the case can be sealed.
According to a further aspect of the present invention, a hearing device includes the vibrator of any of the configurations described above as a cartilage conduction vibrator for transmitting a sound signal to an ear cartilage.
As described above, with the present invention, it is possible to provide more useful vibrators and hearing devices.
A case 2 of the vibrator 1 is composed of an upper case 2a and a lower case 2b. The upper case 2a and the lower case 2b are fixed to each other with adhesive or the like. On the upper case 2a, a projection 2c is formed. The case 2 is formed of resin (for example, ABS resin) or the like.
The projection 2c on the upper case 2a has a wiring hole 2d through which a cable 12 is passed.
The surface of the case 2 in the part excluding the projection 2c is curved. In terms of what is shown in the diagrams, the part of the case 2 excluding the projection 2c is in a spherical or nearly spherical shape. A “spherical shape” may be not only a perfect spherical shape but also a substantially spherical shape with errors within a predetermined tolerance range. When the vibrator 1 is fitted to an ear of a user, a part of the case 2 corresponding to the dimension W1 from its bottom end to the projection 2c is hooked on the ear. To stably fit the vibrator 1 to the ear, it is preferable that the dimension W1 be large. For example, the dimension W2 of the projection 2c in the up-down direction can be equal to or smaller than one-half of the dimension W3 between the bottom end and the top end of the upper case 2a. It is preferable that the projection 2c extend in a direction tangential to the upper case 2.
Housed in the case 2 are a coil bobbin 4, a coil 5, a magnet (a first magnet 6, a second magnet 8), a top plate 7, a frame 9, a damper 10, a yoke 11, and a circuit board 3.
The coil 5 is wound around the coil bobbin 4. The coil bobbin 4 is elongate in the up-down direction, and the top end of the coil bobbin 4 makes contact with the inner surface of the case 2 (upper case 2a). The coil 5 is fed with an electrical signal (a sound signal or the like). The coil bobbin 4 is formed of craft paper or the like, and the coil 5 is formed of copper or the like.
The circuit board 3 is fitted to the inner surface of the case 2 (upper case 2a). To the circuit board 3, the cable 12 (
The circuit board 3 is close to the wiring hole 2d, and thus the cable 12 can be easily connected to the circuit board 3. The coil bobbin 4 is formed to be vertically elongate so that its top end makes contact with the circuit board 3 and the inner surface of the case 2 (upper case 2a), and thus an end (not shown) of the coil 5 or a conductor (not shown) connected to the coil 5 can be easily connected to the circuit board 3.
At least part of the magnet (first and second magnets 6 and 8) is arranged inside the coil bobbin 4. The magnet include the first magnet 6 and the second magnet 8. For the first and second magnets 6 and 8, for example, neodymium magnets are used.
The top plate 7 is arranged inside the coil bobbin 4. The first magnet 6 is arranged over the top plate 7. The second magnet 8 is arranged under the top plate 7. For the top plate 7, for example, iron (such as SPCC) is used.
The yoke 11 is open at its top end and has a bottom portion and a circumferential wall portion. The shape of the inner bottom of the yoke 11 corresponds to the shape of the bottom end of the second magnet 8 so that the bottom end of the second magnet 8 is fixed inside the yoke 11. This allows easy positioning of the second magnet 8. The yoke 11 is formed of a soft magnetic material (such as SPCC).
At least part of the coil bobbin 4 is arranged inside the yoke 11.
An outer edge portion of the damper 10 is fixed to the case 2 and lies between the upper case 2a and the lower case 2b. That is, the outer edge portion of the damper 10 is held between the upper case 2a and the lower case 2b. The bottom face of an inner edge portion of the damper 10 makes contact with the top end of the circumferential wall portion of the yoke 11. The damper 10 is formed of, for example, stainless steel. As shown in
The frame 9 fixes the damper 10 to the yoke 11. Specifically, the frame 9 is swaged to be fixed to the damper 10 and the yoke 11 so as to make contact with the top face of the inner edge portion of the damper 10 and the inner surface of the circumferential wall portion of the yoke 11 respectively. The frame 9 is formed of a soft magnetic material (such as SPCC [steel plate cold commercial]).
If the damper 10 is fixed to the yoke 11 with adhesive or the like (without using the frame 9), they will be fixed together unstably. Here, however, the damper 10 is fixed to the yoke 11 using the frame 9, and this makes it easy to fix them together. That is, fixing the damper 10 to the yoke 11 using the frame 9 in this way is suitable for mass production.
In addition, with the damper 10 fixed to the yoke 11 by the frame 9, the damper 10 supports the yoke 11. The yoke 11 is suspended inside the case 2 by the damper 10 and the frame 9. That is, the yoke 11 stays apart from the inner surface of the case 2.
If the yoke is fixed to the inner surface of the case with adhesive or the like, inconveniently, vibration may be perceived not in the entire sound range but only in a high-frequency band (for example, 5 kHz or higher). In this embodiment, the yoke 11 stays apart from the inner surface of the case 2, and this helps avoid such a problem.
At least parts of the frame 9 and the circumferential wall portion of and the yoke 11 face the coil 5. With this structure, a magnetic flux can be easily concentrated in the coil 5. In particular, the frame 9 and the yoke 11 being formed of a soft magnetic material or soft magnetic materials (such as SPCC) make it easier to concentrate a magnetic flux to the coil 5. Concentrating a magnetic flux (increasing the magnetic flux density) results in a higher driving force for vibration and makes it easy to produce vibration.
If a hole is formed in the case, noise leaks through the hole in the case when the vibrator vibrates. In a case where suppressed noise is preferable, the case can be sealed. Thus, the case 2 may be sealed. When the case 2 is sealed, a closing member (not shown) to cover the wiring hole 2d may be used.
However, if the case is sealed and the vibrating plate (the damper and the like) in the case is formed in a shape without a hole, it is difficult to produce vibration. In particular, when the case is small, it is difficult for the vibration plate to move due to air pressure in the case. The space in the case is divided by the vibration plate into an upper space and a lower space. For example, when the vibration plate tends to move downward, the air in the lower space cannot move to the upper space. Thus, the vibration plate cannot vibrate, or only vibrates with a small amplitude.
In the embodiment, the damper 10 has the through holes 10a formed in it. The air above the damper 10 can move to below the damper 10 through the through holes 10a. Likewise, the air below the damper 10 can move to above the damper 10 through the through holes 10a. The movement of the air in the case 2 is not restricted. Not only when the case 2 is not sealed, but also when the space inside the case 2 is sealed, the damper 10 can vibrate with a large amplitude. Thus, even if the case 2 is small and sealed, the damper 10 can vibrate fully.
Since the damper 10 can vibrate fully not only when the case 2 is not sealed but also when the case 2 is sealed, the case 2 can vibrate sufficiently. Thus, it is possible to transmit sufficient vibration to a user of the vibrator 1.
Incidentally, the vibration of the damper or the yoke vibrates the case. When the vibrating case makes contact with a user, the vibration is transmitted to the user, and the user recognizes sound. Meanwhile, the vibration of the case vibrates the air around the case, and this produces air-conducted sound. The case 2 with a small surface area helps suppress air-conducted sound. Thus, while vibration is transmitted to the user, air-conducted sound can be prevented from leaking to around the user.
When the case 2 is sealed, no water nor sweat enters the case 2. Using a sealed case can be applied to a waterproof vibrator.
The damper 10 can be formed of liquid metal. The damper 10 may break through repeated vibration. Liquid metal, while being a metal, is elastic and is less prone to fatigue damage. The damper 10 formed of liquid metal can be used for an extended period.
The damper 10 is arranged at the middle in the case 2 in the up-down direction. The case 2 can be formed in a spherical or nearly spherical shape with no increase in its size. Here, “middle” may be not exactly middle but substantially middle within a predetermined tolerance range. The case may be in any other shape; it does not need to be in a spherical or nearly spherical shape like the case 2.
Next, the hearing mechanism in a hearing device including the vibrator 1 will be described with reference to
The present inventor, otorhinolaryngologist, discovered, for the first time in the world, a novel hearing mechanism (a third hearing mechanism that is neither air conduction nor bone conduction; see the bold solid-line arrows in
Unlike conventional bone conduction, which requires vibration of the heavy frontal and temporal bones, cartilage conduction requires vibration of the lighter tragus X2a or auricular cartilage X2b to make sound perceived. It thus requires very low energy to drive the vibrator.
Moreover, cartilage conduction is different from conventional air conduction (a phenomenon in which air-conducted sound coming from outside the external acoustic meatus entrance X1a vibrates the tympanic membrane X3 to make sound heard) in that it involves a phenomenon in which, when the external acoustic meatus entrance X1a is closed with a finger or the like, the acoustic energy inside the external acoustic meatus X1 increases to make sound perceived louder (an external acoustic meatus closure effect). Thus, closing the external acoustic meatus entrance X1a helps make sound perceived clearly even in a noisy environment.
The vertical axis of the graph represents acoustic pressure (dBSPL), and the horizontal axis represents frequency (Hz) on a logarithmic scale. Also to show the influence, on the acoustic pressure in the external acoustic meatus, of the contact pressure between the outer wall surface of the vibrating body and the ear cartilage around the external acoustic meatus entrance, in the graph, the acoustic pressure observed in a non-contact state (a state where only air-conducted sound produced at the outer wall surface of the vibrating body is heard) is represented by a solid line, the acoustic pressure observed with a contact pressure of 10 grams by a dotted line, the acoustic pressure observed with a contact pressure of 250 grams by a dash-dot line, and the acoustic pressure observed with the external acoustic meatus closed due to a further increase in contact pressure (a contact pressure of 500 grams) by a dash-dot-dot line.
As shown in
As will be clear from the graph, when the outer wall surface of the vibrating body is brought into contact with at least a part of the ear cartilage around the external acoustic meatus entrance with no contact with the helix, compared to in a no contact state, the acoustic pressure in the external acoustic meatus at one centimeter from its entrance increases by at least 10 dB in the main audible frequency range (500 Hz to 2300 Hz), (compare the non-contact state indicated by the solid line with the state indicated by the dash-dot line).
As will also be clear from this graph, when the outer wall surface of the vibrator is brought into contact with at least a part of the ear cartilage around the external acoustic meatus entrance with no contact with the helix, as the contact pressure changes, the sound pressure in the external acoustic meatus at one centimeter from its entrance changes by at least 5 dB in the main audible frequency range (500 Hz to 2300 Hz) (compare a loose-contact state indicated by the dotted line with the contact state indicated by the dash-dot line).
From the above, it is clear that, even without an air-conducted sound generation mechanism (for example, a vibrating plate in a typical headphone), the desired sound pressure can be obtained by transmitting vibration from the cartilage conduction vibration source to the ear cartilage through contact. Hearing is achieved with the vibrating body kept in contact with the ear cartilage around the external acoustic meatus entrance without closing the external acoustic meatus. Thus, external sound can be perceived simultaneously with the sound from the vibrator, and this provides comfort wearing of the device with no blocked feeling in the ear.
Furthermore, as will also be clear from this graph, when the outer wall surface of the vibrating body is pressed more firmly against at least a part of the ear cartilage to close the external acoustic meatus (the measurements in
The measurements in this graph were all acquired with no change in the output of the cartilage conduction vibration source. As a state where the outer wall surface of the vibrating body makes contact with at least a part of the ear cartilage around the external acoustic meatus entrance with no contact with the helix, the measurements in this graph were acquired with the outer wall surface of the vibrating body kept in contact with the tragus from outside. The measurements in this graph in the external acoustic meatus-blocked state were acquired, as described above, with the tragus firmly pushed from outside to be folded up to create a state where the external acoustic meatus is closed.
This graph is merely one example, and individual variations will be observed when studied in more detail. To simplify and standardize the phenomenon, the measurements in this graph were acquired with the outer wall surface of the vibrating body kept in contact only with the outer side of the tragus over a small area.
However, an increase in acoustic pressure through contact depends also on the contact area with the ear cartilage. When the outer wall surface of the vibrating body is brought into contact with the ear cartilage around the external acoustic meatus entrance with no contact with the helix, the wider the contact area with the ear cartilage around the external acoustic meatus entrance, the larger the increase in acoustic pressure. With consideration given to the above, the values shown in this graph are general for a configuration utilizing cartilage conduction and are reproducible among a diverse group of subjects.
Although the graph was acquired with the external acoustic meatus closed as a result of the tragus being pushed from outside to increase the contact pressure to fold up the tragus, also in the case where the outer wall surface of the vibrating body is pushed into the external acoustic meatus entrance to close the external acoustic meatus, similar results can be obtained.
The vibrator 1 generates vibration in accordance with a sound signal (an electrical signal carrying sound information) and transmits it to a cartilage tissue around the external acoustic meatus entrance X1a. In terms of what is shown in
Used as described above, the hearing device provides stable and quite natural hearing.
The various technical features disclosed herein may be implemented in any other manners than in the embodiments described above, and allow for any modifications made without departure from their technical ingenuity. That is, the embodiments described above should be considered to be illustrative in all respects and should not be considered to be restrictive. It should be understood that the technical scope of the present invention is defined by the scope of claims and encompasses any modifications made in a scope and sense equivalent to the scope of claims.
The invention disclosed herein finds applications in, for example, headphones for smartphones, portable music players, and the like, hearing aids, and microphones.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-162849 | Oct 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/034333 | 9/14/2022 | WO |
