Loop antenna for CIC hearing aid

Abstract

An antenna (10) for a completely-in-canal hearing aid (1) is provided. The antenna (10) comprises: a radiating pair of Helmholtz loops (12) facing each other; and tuning elements (14) connected in series with each loop (12). The loops (12) are excited such that a magnetic field of each loop (12) is in a same direction at resonance. A hearing aid (1) comprising such an antenna is further provided.

Description

[0001] LOOP ANTENNA FOR CIC HEARING AID

[0002] Technical Field

[0003] The present inventive concept relates to an antenna for a completely-in-canal (CIC) hearing aid. More particularly, the present inventive concept relates to a loop antenna for a CIC hearing aid.

[0004] Background

[0005] Modem hearing aids are getting smaller and smaller, and the smallest type of hearing aids are the CIC hearing aids. A CIC type hearing aid needs to fit within ear canals of different sizes. This size constraint means that there is very little space for an antenna.

[0006] A further issue for antennas for CIC type hearing aids is that CIC hearing aids are inside the body, so impedance of the body may prevent signals from reaching the hearing aid and the radiation should be carefully limited to not interact with body tissue in potentially harmful ways.

[0007] Prior art solutions such as US 919175 B2 place an antenna outside the casing of the hearing aid to act as a pull-out string for helping remove the hearing aid from the ear canal. This has a benefit of having less interference from the body of the user because the antenna reaches out of the ear canal, however these antennas are prone to damage as the hearing aid is adjusted or removed from the ear.

[0008] Summary

[0009] It is therefore an object of the present inventive concept to improve antennas used in CIC hearing aids. This and other objects are achieved by the features set out in the appended independent claims, with embodiments set out in the dependent claims.

[0010] Accordingly, a first aspect of the inventive concept is provided by an antenna for a completely-in-canal (CIC) hearing aid. The antenna comprises: a radiating pair of loops facing each other; and tuning elements connected in series with each loop. The loops are excited such that a magnetic field of each loop is in a same direction at resonance.Helmholtz coils comprise two electromagnets (such as loops or coils) aligned on a same axis and with equal currents in the same direction to generate a region of nearly uniform magnetic field.

[0011] The loops of the present invention are loops arranged in a similar manner as Helmholtz coils, i.e. they face each other and generate a substantially uniform magnetic field. These may therefore be called Helmholtz loops.

[0012] The Helmholtz loops may further be fed with equal currents in the same direction and may be aligned on the same axis.

[0013] The Helmholtz loops may further be symmetric and / or self-symmetric.

[0014] The Helmholtz loops may have a shape similar to a circle, a half-circle, or any other suitable shape.

[0015] The Helmholtz loops may be made by any suitable conductive material, such as copper, gold, or aluminium.

[0016] The tuning elements may be a capacitor, resistor, or inductor. There may be one tuning element per loop. There may also be more than one tuning element per loop. The tuning elements tune the antenna to the correct transmission frequency, such as radio- or Bluetooth® frequencies.

[0017] By using such an antenna design, a space-efficient antenna may be used in CIC hearing aids with good enough radiation characteristics to transmit signals to and from within the ear canal.

[0018] Such an antenna suitable for use in a CIC hearing aid may be further usable in other in-the-ear hearing aids.

[0019] Additionally, such an antenna design is simple and cheap to manufacture and is well protected from wear and corrosion because it may be manufactured as a part of already existing manufacturing steps and be placed within the hearing aid. Also, such an antenna may be manufactured using automation, further improving consistency and efficiency.

[0020] The already existing limitations of antennas in CIC hearing aids may prevent such an antenna to be used for functions requiring high bandwidth and long range, however such an antenna is ideal for simple functions such as control signals from e.g. a dedicated device or smartphone.

[0021] The antenna may be formed as an integrated part of a printed circuit board (PCB) of the hearing aid.By integrating the antenna with a PCB, the antenna may be made even more space efficient. Furthermore, it may be relatively easy and effective to add such an antenna when manufacturing the PCB, limiting the total number of manufacturing steps.

[0022] An amplifier PCB may be especially suitable for integrating with the antenna. A distance between the radiating pair of Helmholtz loops may be between 50% and 150% of the diameter of each of the Helmholtz loops.

[0023] Helmholtz coils are traditionally separated by half the diameter of each of the coils to maximize a uniformity of the magnetic field. By separating the Helmholtz loops by at least half the diameter and at most 1.5 of the diameter, the difference in magnetic field between the centers and the edges of the loops is lowered as the distance increases, at the expense of worsening the field's uniformity in the region near the center. Further, this distance is optimized between a low enough distance offering high interaction between the two loops and far enough such that a substantial part of the magnetic field lines created by one loop passes through the other one. This will provide the antenna with a high effective area.

[0024] The distance between the loops may further be influenced by size constraints of the hearing aid, however the range of between 50% and 150% of the diameter of each of the loops has been found to be most effective.

[0025] The antenna may be configured to receive control signals in a Bluetooth® frequency range.

[0026] The Bluetooth® frequency range is 2.4-2.5 GHz, such as 2.44 GHz. This frequency range is compatible with many types of devices and is energy efficient and has beneficial radiation characteristics.

[0027] Control signals may be defined as signals changing parameters and states of the hearing aid, in contrast to signals such as binaural streaming data. Such signals are usually data-efficient and are usually sent from close proximity to the hearing aid.

[0028] The antenna may analogously be configured to transmit signals in the Bluetooth® frequency range, such as acknowledgement signals.

[0029] The radiating pair of Helmholtz loops may be separated by a battery of the hearing aid.

[0030] Such a battery has been found to fit the distance requirements of the Helmholtz loops well and as batteries usually have a circular shape similar to theloops, the combined structure is space-efficient and fits already existing CIC hearing aids without much added design work.

[0031] The antenna may be configured to be a magnetic type of antenna.

[0032] A magnetic type antenna may be considered as an antenna where the near field electromagnetic energy is dominated by magnetic energy, e.g. at least half or at least 70% of the near field energy is magnetic.

[0033] Such an antenna type is more suitable for use near or within a human body, since the magnetic field is not absorbed by body issue in the same way electrical fields are.

[0034] The antenna may be configured to radiate while the hearing aid is being adjusted or removed.

[0035] This may be accomplished by the antenna being completely encased in a casing of the hearing aid, such that it is not shorted or interfered with through human touch.

[0036] This enables signals to be received and transmitted while a user is touching the hearing aid, e.g. using a pull-out member to pull or push the hearing aid into position in the ear canal. This provides a reliable customer experience and further ensures that signals are received when a user may be most prone to send multiple control signals, i.e. when something is wrong and they’re trying to adjust both the fit and parameters to fix the issue.

[0037] A second aspect of the inventive concept is provided by an in-the-ear hearing aid. The hearing aid comprises: a loop antenna according to the first aspect; and an electrically isolated pull-out member.

[0038] Such a pull-out member may be a pull-out string, a pull-out rod, or a pull-out loop, or any suitable member for assisting a user with adjusting or pulling out the hearing aid from their ear.

[0039] By electrically isolating the pull-out member, the user will not risk an electric shock or interfering with the hearing aid as the pull-out member is used.

[0040] The pull-out member may be made using plastics, rubber, or any other suitable material, such as an organic material.

[0041] Any alternatives and benefits of the first aspect also apply to the second aspect mutatis mutandis.

[0042] The in-the-ear hearing aid may be a completely-in-canal (CIC) hearing aid The loop antenna used is especially beneficial for use in CIC hearing aids.The pull-out member may be flexible.

[0043] Such a pull-out member is especially resilient to damage and wear, which may be important to ensure the hearing aid does not get stuck in the ear.

[0044] The hearing aid may further comprise an amplifier PCB integrated with the loop antenna.

[0045] By integrating the antenna with a PCB, the manufacturing process is simplified, and the resulting product is more robust.

[0046] The amplifier PCB is especially suitable for this integration.

[0047] Description of drawings

[0048] The invention will be described in further detail with reference to preferred aspects and the accompanying drawing, in which:

[0049] Fig. 1 shows a schematic of an antenna according to an embodiment;

[0050] Fig. 2 shows a schematic view of an antenna according to an embodiment; and

[0051] Fig. 3 shows a schematic view of a hearing aid according to an embodiment.

[0052] Description of embodiments

[0053] In the following, terms such as a / an / the and comprising are intended to be interpreted as non-limiting. Any processor or computing unit may be implemented as an electronic circuit and electronic connections may be wired or wireless unless otherwise explicitly stated. Unless explicitly specified, a wireless connection may be implemented in any number of standards known to a person skilled in the art, such as Wi-Fi, Bluetooth®, Zigbee, Matter, 4G / LTE, 5G and so one.

[0054] Fig. 1 shows an embodiment of an antenna 10. The antenna 10 comprises two sets of Helmholtz coils 12 in series with a tuning capacitor 14 each. Radio frequency (RF) power is supplied to the middle and split to each of the Helmholtz coils 12.

[0055] The Helmholtz coils 12 are aligned on the same axis and with equal currents in the same direction to generate a region of nearly uniform magnetic field.

[0056] The two Helmholtz coils 12 are arranged to be mutually (inductively) coupled to each other. This increases the total inductance seen from RF power in.

[0057] A benefit of using such a two-coiled antenna is that the antenna has a second radiating structure compared to only using one coil leading to optimal usage of agiven volume, and the mutual inductance between the two Helmholtz coils 12 increases the total effective area compared to using only one coil, thereby also increasing the antenna efficiency.

[0058] The effective area of an antenna is a parameter representing the strength of the antenna interaction with an incoming wave. A larger effective area indicates a better reception.

[0059] Fig. 2 shows an embodiment of an antenna 10. The antenna 10 of Fig. 2 is a version of the antenna 10 of Fig. 1 that uses loops 12 instead of Helmholtz coils 12, which may be called Helmholtz loops 12.

[0060] The loops 12 are self-symmetric and face each other. The loops 12 are excited such that a magnetic field of each loop 12 is in a same direction at resonance.

[0061] The loops 12 of Fig. 2 are fed with equal currents in the same direction. These currents are represented by large arrows in Fig. 2.

[0062] The loops 12 of Fig. 2 have a shape similar to a half-circle and are aligned on a same axis.

[0063] The loops 12 are made from copper.

[0064] The loops 12 are separated by about half a diameter of each of the loops. The antenna 10 further comprises four tuning elements 14, two connected to each loop 12. These tuning elements 14 may be capacitors, resistors and / or inductors.

[0065] The tuning elements 14 tune the antenna 10 to a desired working frequency. The antenna 10 of Fig. 2 is configured to send and receive signals around 2.44 GHz. Any number of tuning elements 14 may be used.

[0066] The loops 12 are connected to a PCB 3 that acts as ground. The loops 12 are also connected to RF power in.

[0067] Fig. 3 shows an embodiment of a hearing aid 1. The schematic of Fig. 3 only shows a breakout of relevant components and not the full hearing aid 1 , e.g. a casing or housing is missing so the figure may not look much like a hearing aid.

[0068] Depending on the housing used, the hearing aid 1 may be a CIC hearing aid or another in-the-ear hearing aid.

[0069] The hearing aid 1 comprises an antenna 10 similar to the antenna 10 in Fig. 2.The hearing aid 1 further comprises an amplifier PCB 3, which enables an amplifier of the hearing aid 1 to function and also acts as ground for the antenna 10 similar to the PCB 3 in Fig. 2.

[0070] The hearing aid 1 further comprises a pull-out member 7. This pull-out member 7 helps a user to adjust the hearing aid 1 or remove the hearing aid 1 from their ear.

[0071] The pull-out member 7 is electrically isolated and flexible. The pull-out member 7 is resilient and long-lasting and convenient and safe to use.

[0072] The hearing aid 1 further comprises a battery 5. The battery 5 is situated between the two loops 12 of the antenna 10. This is very space-efficient.

[0073] The hearing aid 1 further comprises a receiver 8. This produces sound for a user to aid their hearing.

[0074] Other components of the hearing aid 1 may interfere and / or absorb some of the power output by the antenna 10. For example, 80-95%, such as 90%, of the power output by the antenna 10 may be absorbed by the other components of the hearing aid 1 , such as the battery 5. The antenna 10 may output around 1 mW of power.

[0075] This loss may be unavoidable and may mean that the antenna 10 is more suitable for control signals than e.g. high-bandwidth streaming. However, such streaming may be unsuitable for a CIC-type hearing aid anyway since they are very size limited and therefore have limited battery life, and streaming is very energy demanding.

[0076] When the hearing aid 1 is in use it is (at least partially) in an ear of the user. Depending on the type of hearing aid, the hearing aid 1 may be relatively far into the ear of the user, such as for a CIC-type hearing aid.

[0077] Because of this proximity to a human body, the radiation of the antenna 10 is affected. The body is a very large dielectric, which changes the radiation characteristics of the antenna 10 and makes it very difficult to propagate electric fields. There are also health regulations in place limiting the amount and type of radiation used in or near the body.

[0078] Magnetic fields are better suited to being used in or near the human body because magnetic fields are not absorbed by body tissue in the same way electric fields are.The antenna 10 is therefore a magnetic type antenna, which near field electromagnetic energy is comminated by magnetic energy.

[0079] Because the hearing aid 1 in use is in the ear of the user, it may be uncomfortable if not correctly aligned. It may further be difficult to adjust the fit of the hearing aid 1 since it is relatively small and may be partially of fully within the ear canal. As such, a pull-out member 7 such as a string, rod, or loop may be placed on a distal end of the hearing aid 1 to enable the user to better adjust or remove the hearing aid 1.

[0080] This structure is sometimes used as an antenna since it reaches beyond the ear of the user to allow for better conditions for radiation. However, this negatively impacts the pull-out member’s function as a pull-out member since an antenna is more frail than other alternatives.

[0081] Additionally, these pull-out antennas also have issues with occasionally contacting a tragus of the user, thereby grounding the antenna and rendering it nonfunctional, interrupting and / or disrupting any signal being received or transmitted. Also, some users do not like the aesthetics or feel of these pull-out members and cut them off, rendering the hearing aid without an antenna.

[0082] To avoid these issues, the pull-out member 7 of Fig. 3 is flexible, robust, durable, and electrically isolated. The pull-out member 7 of Fig. 3 is made of flexible rubber. The pull-out member 7 is not used as an antenna or a radiating structure of any kind, because the antenna 10 fulfils that purpose for the hearing aid 1.

[0083] The hearing aid 1 may thereby be adjuster or removed, e.g. using the pull-out member 7 or by holding the hearing aid 1 close to the pull-out member 7, without affecting the antenna 10. This is because the antenna 10 is internal and may be completely encased in a casing or housing of the hearing aid.

[0084] Accordingly, the antenna 10 is configured to radiate while the hearing aid 1 is being adjusted or removed. This may be especially beneficial if the user is trying to adjust the hearing aid 1 as a result of signals being received, e.g. while trying to find an optimal volume and fit.

[0085] The preceding description has been a non-exhaustive disclosure of different exemplifying embodiments of the present inventive concept. This is not to be misconstrued as limiting the scope of the protection sought for the inventive concept, which is defined by the appended claims.

Claims

CLAIMS1. An antenna (10) fora completely-in-canal hearing aid (1), the antenna (10) comprising:a radiating pair of loops (12) facing each other; andtuning elements (14) connected in series with each loop (12);wherein the loops (12) are excited such that a magnetic field of each loop (12) is in a same direction at resonance.

2. The antenna according to claim 1 , wherein the antenna (10) is formed as an integrated part of a printed circuit board (3) of the hearing aid (1).

3. The antenna according to claim 1 or 2, wherein a distance between the radiating pair of loops (12) is between 50% and 150% of the diameter of each of the loops (12).

4. The antenna according to any one of the preceding claims, wherein the antenna (10) is configured to receive control signals in a Bluetooth® frequency range.

5. The antenna according to any one of the preceding claims, wherein the radiating pair of loops (12) are separated by a battery (5) of the hearing aid (1).

6. The antenna according to any one of the preceding claims, wherein the antenna (10) is configured to be a magnetic type of antenna.

7. The antenna according to any one of the preceding claims, wherein the antenna (10) is configured to radiate while the hearing aid (1) is being adjusted or removed.

8. An in-the-ear hearing aid (1) comprising:a loop antenna (10) according to any one of the preceding claims; and an electrically isolated pull-out member (7).

9. The hearing aid according to claim 8, wherein the in-the-ear hearing aid (1) is a completely-in-canal hearing aid (1).

10. The hearing aid according to claim 8 or 9, wherein the pull-out member (7) is flexible.

11. The hearing aid according to any one of claims claim 8-10, further comprising an amplifier printed circuit board (3) integrated with the loop antenna (10).

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