EP2034770B1 - Transfer device for a hearing aid with shielded film conductor - Google Patents

Abstract

The device has a resonant circuit including a primary capacitor with an antenna coil (10), and an electrical conductor provided in the resonant circuit. The electrical conductor includes a shielding and a film conductor (13) that is provided with a signal line (14) and a shielding wire (15). A shielding capacitance of the shielding wire is connected parallel to the capacitor. The shielding capacitance together with capacitance of the capacitor is selectively utilized as resonant circuit capacitance. The signal line and the shielding wire are short-circuited at an end of the conductor.

Description

The present invention relates to a transmission device for a hearing device with a resonant circuit including a capacitor and a coil and an electrical line in or to the resonant circuit, wherein the electrical line has a shield. Moreover, the present invention relates to an electrical coil with a wire winding to be screened. In particular, the present invention relates to a hearing device with such a coil for wirelessly receiving and / or transmitting signals. The term "hearing device" is understood here to mean, in particular, a hearing device, but also any other device for sound output that can be worn on or in the ear, such as, for example, a headset, headphones and the like.

Hearing aids are portable hearing aids that are used to care for the hearing impaired. In order to meet the numerous individual needs, different types of hearing aids such as behind-the-ear hearing aids (BTE), hearing aid with external receiver (RIC: receiver in the canal) and in-the-ear hearing aids (IDO), e.g. Concha hearing aids or canal hearing aids (ITE, CIC). The hearing aids listed by way of example are worn on the outer ear or in the ear canal. In addition, bone conduction hearing aids, implantable or vibrotactile hearing aids are also available on the market. The stimulation of the damaged hearing takes place either mechanically or electrically.

Hearing aids have in principle as essential components an input transducer, an amplifier and an output transducer. The input transducer is usually a sound receiver, z. As a microphone, and / or an electromagnetic receiver, for. B. an induction coil. The output transducer is usually as an electroacoustic transducer, z. As miniature speaker, or as an electromechanical transducer, z. B. bone conduction, realized. The amplifier is usually integrated in a signal processing unit. This basic structure is in FIG. 1 shown using the example of a behind-the-ear hearing aid. In a hearing aid housing 1 for carrying behind the ear, one or more microphones 2 for receiving the sound from the environment are installed. A signal processing unit 3, which is also integrated in the hearing aid housing 1, processes the microphone signals and amplifies them. The output signal of the signal processing unit 3 is transmitted to a loudspeaker or earpiece 4, which outputs an acoustic signal. The sound is optionally transmitted via a sound tube, which is fixed with an earmold in the ear canal, to the eardrum of the device carrier. The power supply of the hearing device and in particular of the signal processing unit 3 is carried out by a likewise integrated into the hearing aid housing 1 battery. 5

In the magnetic transmission of data (control data, programming data, audio data) E-field influences are undesirable because they can be destructively superimposed with the useful signal from the magnetic field. Affected by E-field couplings are the magnetic antennas (coil arrangements with and without ferrite core) and in particular their supply lines. Conventional shields are for application in miniaturized hearing aids for space and effort reasons usually not applicable.

It is known to effectively shield electric fields with electrically conductive sheaths. The best known example is coaxial cables.

From the patent US 6,940,466 B2 In addition, the shielding of ferrite core coils with screen films is known. This type of shielding an antenna is specifically associated with hearing aids with serious disadvantages. The film surface has a high capacitive coupling to the underlying ones Turns. The higher the operating frequency, the lower the impedance between the windings and the screen foil. This leads to strong losses for the transmission case and in the case of reception to a deterioration of the sensitivity. If you want to keep the capacitive coupling low, the insulation must be very thick. As a result, the device is much larger and is no longer applicable for miniaturized hearing aids.

The publication US 2006/0269088 A1 describes a multi-coil coupling system for hearing aids. In particular, a transmission device with a resonant circuit including a capacitor and a coil and an electrical line is set forth in the resonant circuit. In addition, stray capacitances occur in the resonant circuit, which together with an inductance lead to resonance.

Furthermore, the Patent US 4,926,007 A a shielded flexible foil conductor. This conductor can be used in particular for supply lines of antennas.

The publication US 2006/0049995 A1 describes an antenna circuit integrated in a semiconductor chip. Multiple capacitances and inductors form a tuning circuit with which it is possible to adjust an impedance.

Further, the document discloses DE 31 43 210 A1 an electrical component consisting of inductive and capacitive elements. In this case, a wound into a plane, punched out of a metal foil trace structure is folded so that the superimposed conductor track parts form a continuous winding of the inductive element, while between selected, superimposed conductor track parts, a dielectric is arranged to form the capacitive element. In the electrical component, capacitive elements can be realized which together with the inductive element form a resonant circuit.

The object of the present invention is therefore to propose a transmission device for a hearing device with a shielded antenna feed, wherein the space is to be reduced. In one embodiment, a shielded antenna coil with reduced space requirement is to be provided.

According to the invention this object is achieved by a transmission device according to claim 1.

In this case, an electrical coil can be used with a wire winding including a first and a second wire end, wherein the wire winding is formed single-layered in an axial direction starting at the first end of the wire and a wire section is guided at the second end of the wire against the axial direction as a shield directly over the wire winding ,

Advantageously, by exploiting the shielding capacitance, which is actually a parasitic capacitance, it is possible to increase the capacitance of the necessary resonant circuit capacitor to reduce and thus save space. In addition, the use of the film conductor has the advantage that its capacity can be determined very accurately, whereby the necessary tolerances can be reduced. This in turn reduces the necessary tuning range and makes possible a so-called "on-chip tuning" in which on-chip tuning capacitors are switched on as required. The tuning capacitor necessary for the resonant circuit of the transmission device can then be completely integrated into a semiconductor chip.

Preferably, the coil of the resonant circuit has an own shield formed by its winding wire itself. In particular, the intrinsic shielding is formed, as in the above-described electrical coil, by passing a wire end directly opposite the wire winding, in the direction opposite to the axial direction of the winding as shielding. In this way, voluminous shielding components can be avoided.

According to one embodiment, one of the signal lines and the shield line may be short-circuited at one end of the electrical line of the resonant circuit. Thus, the shield is set to the potential of one end of the line and there is no special shielding potential to the electrical line to be performed.

Furthermore, the foil conductor can have a conductor layer, which can be interrupted laterally or laterally and thus used both for the signal line and for the shielding line. Alternatively or additionally, the foil conductor may have a plurality of conductor layers for the signal line and the shield line. As a result, the desired shielding effects can be achieved parallel or transversely to the carrier foil of the foil conductor.

FIG 1

den prinzipiellen Aufbau eines Hörgeräts gemäß dem Stand der Technik;

FIG 2

die Zuleitung einer Spule mit einem Folienleiter gemäß der vorliegenden Erfindung;

FIG 3

einen Querschnitt der Zuleitung von FIG 2;

FIG 4

eine erste Alternative einer Zuleitung;

FIG 5

eine zweite Alternative einer Zuleitung;

FIG 6

eine dritte Alternative einer Zuleitung;

FIG 7

einen Längsschnitt durch eine mehrlagige Antennenspule;

FIG 8

einen Längsschnitt durch eine einlagige Antennenspule;

FIG 9

ein Schaltungsdiagramm einer erfindungsgemäßen Übertragungseinrichtung; und

FIG 10

ein Schaltungsdiagramm einer alternativen Übertragungseinrichtung.

The present invention will be further explained with reference to the accompanying drawings, in which:

FIG. 1

the basic structure of a hearing aid according to the prior art;

FIG. 2

the supply of a coil with a foil conductor according to the present invention;

FIG. 3

a cross section of the supply of FIG. 2 ;

FIG. 4

a first alternative of a supply line;

FIG. 5

a second alternative of a supply line;

FIG. 6

a third alternative of a supply line;

FIG. 7

a longitudinal section through a multi-layer antenna coil;

FIG. 8

a longitudinal section through a single-layer antenna coil;

FIG. 9

a circuit diagram of a transmission device according to the invention; and

FIG. 10

a circuit diagram of an alternative transmission device.

The embodiments described in more detail below represent preferred embodiments of the present invention.

FIG. 2 symbolically shows a part of a single-layer wound antenna coil 10. The first coil end 11 represents the signal line input sig. The second coil end 12, which is also used for shielding (see. FIG. 8 ) is applied to a screen or reference potential ref. The two winding ends 11 and 12 are connected to a foil conductor 13. Specifically, the first winding end 11 with a signal line 14 of the film conductor 13 and the second Winding end 12 connected to a shield line 15. It is therefore shown here the case that the antenna is connected with a connection to a reference potential (ground or supply voltage) and for this connection, a shield layer or the shield line 15 of the film conductor 13 is used.

In FIG. 3 is a section III / III through the film conductor 13 of FIG. 2 shown. Accordingly, located on a carrier film 16, a conductor layer which is interrupted laterally or laterally twice. This results in three lines: In the middle of the signal line 14 and left and right of the shield lines 15, which are connected to each other at the end of the film conductor 13.

In FIG. 4 an alternative foil conductor 13 is shown. He has on the one flat side as the film conductor of FIG. 3 a longitudinally extending signal line 14. On the other flat side of the carrier film 16 (in FIG. 4 the underside) is also a metal coating which is used as the shielding line 17. Between the signal line 14 and the shield line 17 so here is the carrier film 16th

Another embodiment of a foil conductor with shielding is in FIG. 5 played. This construction represents a combination of the ladder constructions of the FIGS. 3 and 4 On the top of the carrier sheet 16 are, as in the example of FIG. 3 , the signal line 14 and the shield line 15 are arranged, while on the bottom of the additional shielding line 17 is arranged.

In FIG. 6 is a development of the film conductor 13 of FIG. 5 shown. In addition to the structure of FIG. 5 is on the signal line 14 and the shield lines 15, a further carrier film 16 'and in turn another additional shielding 17' arranged. While FIG. 3 So a two - layered structure (carrier and conductor layer) of Foil conductor 13 shows, put the FIGS. 4 and 5 a three-layer construction and FIG. 6 a five-layer structure of the film conductor 13. By such a multilayer film conductor 13 with integrated shielding, so can be a space-saving lead for an inductive antenna realize.

The shielding of the supply line is of crucial importance for the construction of critical hearing aids with magnetic data transmission. The choice of the supply line length and the way of laying the supply line must be set much less strict. This is particularly important for in-the-ear hearing aids with individually manufactured housing shells. In the hearing aids, for the most part, parallel resonant circuits with high quality are used, which have a high receiving sensitivity and a high frequency selectivity because of the voltage overshoot in the vicinity of the resonance. Due to the shielding one gains an increased signal-to-noise ratio and a suppression of interfering signals that are not directly in the vicinity of the operating frequency.

The nature of the lead shielding affects particularly antennas that are part of a parallel resonant circuit. The construction-related and usually not negligible supply capacity can be part of the resonant circuit capacity. When using foil conductors (cf. FIGS. 3 to 6 ) the capacitance is very well defined and the dielectric losses very low. The capacity of the shield can therefore be used as a full part of the useful capacity. Due to the clear definition of the shield capacitance, parallel resonant circuits of high quality can be developed. This is very difficult with twisted lines, which are commonly used in hearing aids, since their capacity and shielding capacity vary greatly. Consequently, in the known hearing aids a relatively high tuning range in terms of capacity is necessary. This is usually not possible on a chip ("on-chip tuning"). Since the inventive use of a film conductor with defined Umbrella capacity brings less capacity fluctuations, no separate capacitors must be provided for the tuning of the resonant circuit, but it can be used on a chip in a known manner for tuning the small capacitances.

A film shield, as known from the prior art ( US 6,940,466 B2 ) is not used for the antenna due to the above-mentioned disadvantages in the present case. Instead, the antenna coil is self-shielded, as in the FIGS. 7 and 8 is shown. FIG. 7 shows a multi-layer wound coil 10 'with the coil ends 11 and 12 on one side of the coil 10'. An inner winding layer 18 is wound around a cylindrical ferrite core 20 in a first axial direction 19. An outer winding layer 21, however, is wound in a first axial direction 19 opposite second axial direction 22 to the underlying windings. In this multi-layer wound coil 10 ', the wire end 12 of the outer winding layer 21 is connected to the reference potential ref. As a result, the outer turns have only a small potential difference with respect to the reference ref and are accordingly insensitive to acting E-fields. However, multi-layer wound coils are only suitable for low operating frequencies below about 2 MHz because of their low intrinsic resonance. FIG. 8 on the other hand, symbolically shows a longitudinal section through a single-coil antenna coil 10. The wire winding with its two winding ends 11 and 12 is wound in the first axial direction 19 via the ferrite core 20. A part of the winding wire in front of the second end 12 serves as a return wire 23. To better recognize it, it is in FIG. 8 , which represents a sectional drawing, nevertheless shown in solid lines. This return wire is guided or wound in the opposite second axial direction 22 over the winding layer and subsequently connected to the reference potential ref. The degree of feedback 23 is therefore at reference potential and makes the underlying winding position insensitive to acting E-fields.

Such coils are also very suitable for higher frequency operating frequencies up to 20 MHz.

FIG. 9 shows a circuit diagram of a transmission device according to the invention. A resonant circuit consisting of the antenna coil 10 or L _res with a main resonant capacitor C _res is fed by a chip 24, which in turn is connected to ground GND and is supplied by a supply voltage V +. For the resonant circuit supply, the chip 24 provides the signal potentials Sig + and Sig-. The potential Sig + is fed via the signal line 14 of the film conductor 13 directly to the coil 10. The other potential Sig- is also applied to the coil 10 via the signal line 14 of a foil conductor 13. This wiring diagram of the coil 10 represents an equivalent circuit diagram for the coils of FIGS. 7 and 8 represents.

In this example, the shield lines 15 of the film conductors 13 are connected to a specific reference potential V _ref , which is also provided by the chip 24. This reference potential V _ref is independent of the signal potentials Sig + and Sig-, resulting in a balanced wiring of the inductive antenna.

The shielding of the foil conductor 13 leads to an additional capacitance C _guard . This because of the nature of the film conductor very defined shielding capacitance C _guard is parallel to the capacitance C _res , so that the resonant circuit capacitance is roughly formed from the sum of the capacitances C _res plus C _guard . However, the entire resonant circuit capacity is to be tuned exactly, which is why parallel to the main capacitor C _res on the chip 24 tuning capacitances are provided, which are symbolized in the circuit diagram by the variable capacitance C _chip . Since the manufacturing tolerances of the foil conductor are low, especially with regard to the shielding, only a small tuning range is required with regard to the resonant circuit capacitance. This can be realized by the capacitors or the variable capacitance C _chip on the chip 24.

In FIG. 10 a further embodiment of the transfer device according to the invention is shown. While with the circuit of FIG. 9 a symmetrical wiring of the inductive antenna 10, namely with the signal potentials Sig + and Sig- is possible by the circuit of FIG. 10 realized an asymmetrical wiring of the inductive antenna 10. The one terminal of the coil 10 is placed here via the signal line 14 to reference potential V _ref . The other terminal of the coil 10 is connected to a signal potential Sig which, like the reference potential V _{ref, is provided} by a chip 24 '. The parallel resonant circuit C _res , L _res is therefore at the two potentials V _ref and Sig. At one end of the foil conductor 13, the shield line 15 is short-circuited to the signal line 14. Despite shielding, the antenna then has only two instead of three connections (cf. FIGS. 7 and 8 ). This is particularly important for miniaturization, since then only two of the relatively large connection pads must be maintained. In order to avoid current loops, it is also advantageously provided that the shielding layer or the shielding line 15 is connected to the reference potential terminal V _ref on only one side of the foil conductor 13.

Claims (6)

1. Transmission facility for a hearing apparatus having

   - an oscillating circuit including a capacitor (C_res) and a coil (L_res, 10) as well as

   - an electrical line (13) in or to the oscillating circuit, characterised in that

   - the electrical line has a shield,

   - the electrical line has a film conductor (13) with signal line (14) and shielding line (15), the capacitance distribution of which is defined and the shielding capacitance (C_guard) of which is connected in parallel to the capacitor and the shielding capacitance is used together with the capacitance of the capacitor (C_res) in a targeted fashion as an oscillating circuit capacitance,

   - a variable tuning capacitor (C_Chip) integrated completely into a semiconductor chip is connected to the capacitor (C_res).
2. Transmission facility according to claim 1, with the coil (L_res, 10) having a natural shielding formed itself by its winding wire.
3. Transmission facility according to claim 2, with the coil (L_res, 10) having a wire winding including a first (11) and a second wire end (12), and with the wire winding being formed in one layer in an axial direction (19) starting at the first wire end (11) and
   a wire section (23) on the second wire end (12) being guided as a shield directly over the wire winding opposite to the axial direction (22).
4. Transmission facility according to one of the preceding claims, with the signal line (14) and the shielding line (15) being short-circuited at one end of the electrical line.
5. Transmission facility according to one of the preceding claims, with the film conductor (13) having a conductor layer, which is laterally discontinued and is therefore used both for the signal line (14) as well as for the shielding line (15).
6. Transmission facility according to one of the preceding claims, with the film conductor (13) having several conductor layers for the signal line (14) and the shielding line (15).

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