Circularly polarized antenna and hearing instrument

Abstract

A circularly polarized antenna (20) for a hearing instrument (1) is described. This antenna (20) has a ground plane (24) and an excitation layer (28) separated from the ground plane (24) by a first dielectric layer (26), which is coupled to a signal connection (40) passing through the first dielectric layer (26) and the ground plane (24). Furthermore, the antenna (20) has a cover layer (36) arranged on the side of the excitation layer (28) facing away from the ground plane (24) and separated from it by a second dielectric layer (34), wherein the cover layer (36) is connected to the ground plane (24) at four points via a capacitor and / or an inductor in each connection.

Description

[0001] The invention relates to a circularly polarized antenna. Furthermore, the invention relates to a hearing instrument with such an antenna.

[0002] Hearing instruments (or hearing devices) are typically used to output an audio signal to the wearer's ear. The output is achieved via an output transducer, usually acoustically through sound waves transmitted via a loudspeaker (also called a "receiver"). Such hearing instruments are frequently used as hearing aids. They typically include an acoustic input transducer (especially a microphone) and a signal processor. This processor is designed to process the input signal (also called the microphone signal) generated from the ambient sound by the input transducer, using at least one user-specific signal processing algorithm, in such a way as to at least partially compensate for the wearer's hearing loss.Particularly in the case of a hearing aid, the output transducer can be a loudspeaker, a bone conduction receiver, or a cochlear implant, all of which are designed to mechanically or electrically couple the sound signal into the wearer's ear. There are also hearing instruments that protect or improve the hearing of users with normal hearing, for example, by enabling improved speech understanding in complex listening situations. Such devices are also known as "Personal Sound Amplification Products" (PSAPs). The term "hearing instruments" also includes devices such as tinnitus maskers, headsets, headphones, and similar devices.

[0003] Typical designs of hearing instruments, especially hearing aids, are behind-the-ear (BTE) and in-the-ear (ITE) hearing instruments. These terms refer to the intended wearing position. Behind-the-ear hearing instruments have a (main) housing that is worn behind the ear. A distinction can be made between models whose speaker is located within this housing—sound is typically delivered to the ear via a sound tube placed in the ear canal—and models that have an external speaker positioned in the ear canal. In-the-ear hearing instruments, on the other hand, have a housing that is worn in the ear or even entirely within the ear canal.

[0004] Hearing aids also offer the option of selecting or changing settings, at most a volume level or so-called hearing programs. Besides operation via switches or buttons on the hearing aid itself, which can be challenging due to their often very small size, operation via a remote control is significantly more convenient. Since a wired remote control can be conspicuous or even annoying due to a tangled cable, a wireless connection between the remote control and the hearing aid is considerably more user-friendly. The use of a smartphone with a suitable app installed as a remote control is particularly interesting in this regard. For this purpose, but also for integrating external audio signals (e.g., TV audio), wireless technology based on the Bluetooth standard ("Bluetooth" is a registered trademark) is a viable option.Due to minimal antenna dimensions, the challenge here is to combine the miniaturization of hearing instruments, especially in-ear hearing instruments, with the required antenna dimensions.

[0005] The invention is therefore based on the objective of providing a particularly small antenna for use in a hearing instrument.

[0006] This problem is solved according to the invention by an antenna having the features of claim 1. Furthermore, this problem is solved according to the invention by a hearing instrument having the features of claim 13. Advantageous and partly inventive embodiments and further developments of the invention are set out in the dependent claims and the following description.

[0007] The antenna according to the invention is designed as a circularly polarized antenna and is intended for use in a hearing aid. The circularly polarized antenna (hereinafter referred to simply as "antenna") has a ground plane and an excitation layer separated from the ground plane by a first dielectric layer. The excitation layer is coupled to a signal terminal that passes through the first dielectric layer and the ground plane. The antenna also has a cover layer, which is arranged on the side of the excitation layer facing away from the ground plane and is separated from it by a second dielectric layer. The cover layer is connected to the ground plane at four points via an interposed capacitor (also called "terminal capacitance") and / or an inductor (also called "terminal inductance").

[0008] The ground plane, the excitation layer, and the cover layer each represent a body, particularly a foil-like body, i.e., one with a significantly larger planar extent (e.g., diameter, length, or width) compared to its thickness (e.g., at least ten times larger). These layers can therefore alternatively be referred to as the (particularly foil-like) ground plane, excitation body, and cover layer. The respective dielectric layer is also formed by a body, particularly one made of a dielectric material or composite material. Its thickness is preferably greater than that of the ground plane, the excitation layer, and the cover layer. In particular, the thicknesses of all layers are dimensioned such that the total thickness of the antenna is less than one-quarter of the effective wavelength of the antenna. D g < λ eff 4

[0009] The effective wavelength is λ eff = λ 0 ϵ r where ε ris the dielectric constant of the dielectric layers. λ 0 This is the free-space wavelength, which is approximately 12 cm at a typical frequency of 2.45 GHz (wavelength of the Bluetooth radio standard).

[0010] The ground plane is expediently connected (coupled) to a ground potential, in particular that of the listening instrument, in the intended operating state of the antenna.

[0011] The arrangement of the ground plane, the excitation layer, and the cover layer according to the invention enables a compact antenna design, particularly with regard to its external dimensions. This is especially advantageous for its use in mobile devices, particularly in hearing aids. The interposition of the respective capacitance (preferably in the form of a capacitor, also known as a "terminal capacitor") or inductance (preferably in the form of a coil, also known as a "terminal coil") between the four contacts of the cover layer to the ground plane results in the circular polarization of the antenna. This is also advantageous for mobile applications when the orientation (in terms of polarization) of a transmitting antenna relative to a receiving antenna is not fixed or cannot be determined.A circularly polarized antenna is insensitive to interference from another circularly polarized antenna and, compared to a linearly polarized antenna, is at least relatively insensitive to the polarization direction of the latter. Linearly polarized antennas, on the other hand, exhibit particularly high attenuation against linearly polarized signals whose polarization direction does not match their own, especially if it is perpendicular to their own.

[0012] According to a preferred embodiment, a ground via (i.e., a through-hole connection to the ground layer) is provided through the first and second dielectric layers at each point where the cover layer contacts the ground layer (also referred to as the cover layer contact point). This allows the antenna to be implemented as an integrated component, eliminating the need for external contacts in the form of (wire) conductors (e.g., cables or the like).

[0013] According to another advantageous embodiment, the four contact points of the cover layer (and thus also, in particular, the four mass vias) are arranged offset by 90 degrees from each adjacent contact point with respect to a center (especially the geometric center of gravity) of the cover layer. In other words, the mass vias each lie on radial rays emanating from the center of the cover layer, which are rotated 90 degrees relative to each other, e.g., relative to an analog clock, at 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock.

[0014] In particular, the contact points are also arranged at the edges of the cover layer. "At the edges" is preferably understood to mean that the respective contact point is located at least within a peripheral strip surrounding the cover layer, with a width of at most one-third of the local distance (i.e., at the location of the contact point) between the outer edge of the cover layer and the center of the cover layer. Advantageously, the contact points are also designed identically, so that the antenna structure is rotationally symmetrical. In particular, at least a 180-degree rotational symmetry, and optionally also a 90-degree rotational symmetry, is formed.

[0015] In a manufacturing-efficient design, the cover layer has a recess at the edge of each contact point, e.g., in the form of a notch, within which the grounding via is contacted with the cover layer in the plane of the cover layer, e.g., soldered. Preferably, the respective grounding via terminates at the contact point.

[0016] Preferably, the excitation layer and the cover layer are shaped like round discs. A round shape allows the antenna to be integrated particularly well into the hearing instrument. However, the excitation layer and the cover layer can also be polygonal, for example, hexagonal, octagonal, or multiple-sided.

[0017] In a preferred embodiment, the excitation layer is smaller in diameter—or, in the case of a non-circular shape, in its outer surface dimensions—than the cover layer. Furthermore, preferably, the diameters or outer surface dimensions of the cover layer (excluding any recesses at the contact points) and the two dielectric layers correspond to each other.

[0018] According to a preferred embodiment of this excitation layer with reduced diameter (area dimensions), four ground tabs, each formed by a ring segment, are located on the excitation layer and are in contact with the ground layer. In particular, these ring segments have a width of up to half, preferably about one-third or even just one-quarter, of the local edge distance of the cover layer to its center as described above. These ring segments are galvanically isolated from the excitation layer, for example, by means of the first and / or the second dielectric layer. Each of these ground tabs advantageously forms an auxiliary capacitor (with a corresponding capacitance) connected in parallel to the capacitance (especially the capacitor) on the cover layer. This is advantageous for the circular polarization of the antenna.It has been found that different terminal capacitances are advantageous for the formation of circular polarization. To avoid having to use different terminal capacitors (i.e., with different terminal capacitances), the ground tabs expediently have different circumferential lengths, at least in pairs. Preferably, the ground tabs opposite each other across the center (center of gravity) of the excitation layer are of the same length, while the other two have a different length, e.g., by up to 1 mm, preferably by about 0.5 mm. However, to avoid elliptical or even linear polarization, the difference in length between the ground tabs should not exceed these dimensions. This allows standard components to be used as terminal capacitors.Any necessary differences can be achieved relatively easily using mass flags.

[0019] Each of the ground tabs is conveniently connected to one of the four ground vias (and thus to the ground plane). This eliminates the need for additional contact between the ground tabs and the ground plane, which contributes to the antenna's compact design.

[0020] According to a preferred embodiment, the signal connection for the excitation layer is formed by a through-hole (hereinafter referred to as the "signal via"). This signal via penetrates the first dielectric layer and the ground layer, as described above. Preferably, the signal via is galvanically decoupled from the ground layer, i.e., electrically isolated. Furthermore, the signal via is arranged in an angular region between two (adjacent) ground vias, in particular on an angle bisector between two ground vias (i.e., preferably angled by ±45 degrees relative to these two ground vias).

[0021] The signal connection, in particular the signal via, is preferably also arranged at the edge (see above definition) of the excitation layer and connected to it at the edge.

[0022] According to a preferred embodiment, the first and second dielectric layers are connected – particularly in the area of ​​a spacer between the ground flags and the excitation layer.

[0023] Preferably, the first and second dielectric layers are formed from a material with a relative permittivity between 5 and 15, in particular between 8 and 12, preferably exactly or approximately (i.e., + / - 1) 10. For example, an epoxy resin or a comparable plastic or ceramic is used as such a material.

[0024] Advantageously, the ground layer, the excitation layer, the ground tabs and / or the cover layer are formed from electrically conductive material, in particular a metal, preferably copper.

[0025] Preferably, the outer edge (in the case of a round cover layer) or the outer edge (in the case of a polygonal cover layer) also forms an outer boundary of the entire antenna. In particular, the first and second dielectric layers are also designed with the same outer diameter or the same outer dimensions as the dielectric layer.

[0026] As explained above, the invention enables a particularly compact circularly polarized antenna. Specifically, in the case of a circular cover layer, the largest (outer) diameter (or in the case of a non-circular, especially polygonal, cover layer, the largest outer dimension) of the cover layer, and thus preferably also of the antenna, is less than or equal to 0.1 times, more particularly less than or equal to 0.08 times, and preferably 0.06 times, the wavelength of a frequency selected for transmitting and receiving the antenna. In the case of the Bluetooth standard frequency of approximately 2.4–2.5 GHz, 0.06 times corresponds to approximately 0.75 cm. That is, the invention enables an antenna with a diameter of less than 0.8 cm for the widely used Bluetooth standard.

[0027] The hearing instrument according to the invention comprises, in particular, at least one microphone, a signal processor, and a loudspeaker, the antenna described above. Preferably, the hearing instrument is designed as a hearing aid worn in the ear. In particular, the hearing instrument constitutes a hearing aid device.

[0028] The conjunction "and / or" is to be understood here and in the following in particular as meaning that the features linked by means of this conjunction can be formed both jointly and as alternatives to each other.

[0029] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 schematically shows a hearing instrument in a perspective view, Fig. 2 schematically shows a circularly polarized antenna of the hearing instrument in another perspective view from a top, Fig. 3 schematically shows the antenna in yet another partially transparent perspective view from a bottom, Figs. 4, 5 in view according to Fig. 2 schematically the antenna with focus on an excitation layer and a ground layer, and Fig. 6 in a schematic representation of electronic components of the hearing instrument in a pre-assembly assembly.

[0030] Corresponding parts in all figures are always marked with the same reference symbols.

[0031] In Fig. 1Figure 1 shows a hearing instrument 1, which forms a hearing aid worn in the ear. The hearing instrument 1 has a faceplate 2 and an earpiece 4 adapted to the ear canal, which together enclose an interior housing in which electronic components of the hearing instrument 1 are arranged. The electronic components consist of at least a microphone 6, a signal processor 8, and a loudspeaker 10 (see Figure 1). Fig. 6Furthermore, the electronic components include a rechargeable battery 12 and a battery controller 14 associated with the battery 12, which is configured to control the supply of energy to the other electronic components as well as charging processes. The electronic components also include an antenna 20, which is configured and intended for communication with a mobile device. The antenna 20, the battery controller 14, the microphone 6, and the signal processor are arranged on a folded printed circuit board 22. The battery 12 and the loudspeaker 10 are connected via cables. This forms a pre-assembled module that is Fig. 6 is shown.

[0032] In the Figures 2 to 5 Antenna 20 is explained in more detail below. Antenna 20 is radially polarized and has a particularly compact design. In the illustrated embodiment, antenna 20 is circularly cylindrical.

[0033] Antenna 20 has a (in Fig. 3 visible) underside mass layer 24, which in the intended operating condition (see Fig. 6) is connected to ground potential. A first dielectric layer 26 is arranged on the ground layer 24. The ground layer 24 and the dielectric layer 26 are designed as round disks with the diameter of the circular cylinder of the antenna 20. In the present embodiment, the diameter of the antenna 20 is 6 mm, but can, for example, be in the range of 4 to 8 mm. On this dielectric layer 26, opposite the ground layer 24, an excitation layer 28 in the form of a round disk is arranged. The excitation layer 28 is aligned coaxially with the circular cylindrical shape of the antenna 20. However, the excitation layer 28 has a smaller diameter than the circular cylinder of the antenna 20. Radially outside the excitation layer 28, a ring consisting of four ring segments 30, each covering approximately a quarter circle, is arranged. The radial width of the ring segments 30 is approximately one quarter to one third of the radius of the circular cylinder.Each of the ring segments 30 forms a mass flag 32. In particular, any two mass flags 32 opposite each other via a center of the excitation layer 28 (i.e. its axis) are of the same length and the other two are 0.5 mm shorter.

[0034] A second dielectric layer 34, which again has the same diameter as the circular cylinder, is arranged on the excitation layer 28 and the ground flags 32, which are arranged in the same plane as the excitation layer 28. A cover layer 36, which also forms a circular disk, is arranged on the end face of the second dielectric layer 34 (and thus separated from the excitation layer 28).

[0035] The excitation layer 28 is coupled to a signal connection 40, which, in its intended operating state, is coupled to a signal line and thus indirectly to a signal input and output of the hearing instrument 1. The signal connection 40 is formed by a through-hole, here referred to as signal via 42. The signal via 42 penetrates the ground layer 24 (but is galvanically isolated from it) and the first dielectric layer 26 and is located at the edge of the excitation layer 28. In the present embodiment, one diameter of the signal via 42 lies within, but at an outer edge of, the excitation layer 28.

[0036] The top layer 36 is connected to the mass layer 24 at four contact points 44 (see. Fig. 2At each contact point 44, the cover layer 36 has a recess at its edge, specifically a rectangular incision 46, within which a via ("ground via 48") penetrates the first and second dielectric layers 26 and 34 radially outside the excitation layer 28. The incision 46 extends inwards by a maximum of one-third of the radius of the cover layer 36. The ground vias 48 are contacted with the ground layer 24 at their base. The ground vias 48 are offset from each other by 90 degrees relative to the center of the antenna 20 and thus of the cover layer 36. The signal via 42 lies on an angle bisector between two ground vias 48.

[0037] The grounding vanes 32 are spaced apart and arranged circumferentially such that the grounding vias 48 pass between two grounding vanes 32. However, each grounding vane 32 is in contact with one of the grounding vias 48 and thus with the grounding layer 24 (see Figure 1). Fig. 5 ).

[0038] The top layer 36 is coupled to the ground vias 48 terminating at the contact points 44 on the end face of the second top layer 36, with each via a capacitor 50 (which has a capacitance) interposed. This results in the circularly polarized characteristic of the antenna 20. The ground lugs 32 each form an auxiliary capacitor connected in parallel to the respective capacitor 50. Due to the different lengths of the ground lugs 32 in pairs, the auxiliary capacitors have different capacitances, at least in pairs, which reinforce the circularly polarized characteristic of the antenna 20.

[0039] The ground layer 24, the ground tabs 32, the excitation layer 28, and the cover layer 36 are electrically conductive, e.g., made of metal. In the present embodiment, these are specifically formed by a copper foil or copper coating. The first and second dielectric layers 26 and 34 are formed of a material with a relative permittivity of 10 ± 1, e.g., a plastic, such as an epoxy resin.

[0040] In principle, it is also conceivable that the ground layer 24 is formed as part of the circuit board 22 and that the antenna 20 is therefore at least partially integrated into the circuit board 22.

[0041] The subject matter of the invention is not limited to the embodiment described above. Rather, further embodiments of the invention can be derived by a person skilled in the art from the above description. Reference symbol list

[0042] 1 Hearing instrument 2 Faceplate 4 Earpiece 6 Microphone 8 Signal processor 10 Speaker 12 Battery 14 Battery controller 20 Antenna 22 Circuit board 24 Ground layer 26 Dielectric layer 28 Excitation layer 30 Ring segment 32 Ground tab 34 Dielectric layer 36 Top layer 40 Signal connection 42 Signal via 44 Contact point 46 Cutout 48 Ground via 50 Capacitor

Claims

1. Circularly polarized antenna (20) for a hearing instrument (1), comprising - a ground plane (24), - an excitation layer (28) separated from the ground plane (24) by a first dielectric layer (26), which is coupled to a signal connection (40) passing through the first dielectric layer (26) and the ground plane (24), and - a cover layer (36) arranged on the side of the excitation layer (28) facing away from the ground plane (24) and separated from it by a second dielectric layer (34), wherein the cover layer (36) is connected to the ground plane (24) at four points by means of a capacitor and / or an inductor in each place.

2. Circularly polarized antenna (20) according to claim 1, wherein at each point for contacting the cover layer (36) with the ground layer (24) a ground via (48) is guided through the first and the second dielectric layer (26).

3. Circularly polarized antenna (20) according to claim 1 or 2, wherein the four points for contacting the cover layer (36) with the ground layer (24) are arranged offset by 90 degrees from each adjacent point with respect to a center of the cover layer (36).

4. Circularly polarized antenna (20) according to one of claims 1 to 3, wherein the excitation layer (28) and the cover layer (36) are designed as round disks.

5. Circularly polarized antenna (20) according to one of claims 1 to 4, wherein the excitation layer (28) is formed in diameter smaller than the cover layer (36) and wherein four ground flags (32) formed by a ring segment (30) are formed on the plane of the excitation layer (28) and are contacted with the ground layer (24).

6. Circularly polarized antenna (20) according to claim 5, wherein each mass vane (32) is contacted with one of the four mass vias (48).

7. Circularly polarized antenna (20) according to one of claims 2 to 6, wherein the signal connection (40) for the excitation layer (28) is formed by a signal via (42) which is arranged in an angular range between two ground vias (48), in particular on an angle bisector.

8. Circularly polarized antenna (20) according to claim 7, wherein the signal via (42) is arranged at the edge of the excitation layer (28).

9. Circularly polarized antenna (20) according to one of claims 1 to 8, wherein the first and the second dielectric layer (26, 34) are connected.

10. Circularly polarized antenna (20) according to one of claims 1 to 9, wherein the first and the second dielectric layer (26, 34) are formed from a material having a relative permittivity between 5 and 15, in particular between 8 and 12, preferably 10.

11. Circularly polarized antenna (20) according to one of claims 1 to 10, wherein the ground layer (24), the excitation layer (28) and / or the cover layer (36) are formed of electrically conductive material, in particular a metal, preferably copper.

12. Circularly polarized antenna (20) according to one of claims 1 to 11, wherein a largest diameter of the cover layer (36) is less than or equal to 0.1 times, in particular 0.08 times, the wavelength of a frequency selected for transmitting and receiving the antenna (20).

13. Hearing instrument (1), in particular a hearing instrument to be worn in the ear, comprising a circularly polarized antenna (20) according to one of claims 1 to 12.

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