Inductive charging device for hearing device and method for operating same

Abstract

The invention relates to a method (60) for operating an inductive charging device (22) of a hearing device (4), comprising a voltage source (26) and a resonant circuit (28) connected to the voltage source, said resonant circuit comprising a charging coil (30) and a capacitor (32) having a main capacitor (34) and a regulating branch (38) connected in parallel to the main capacitor. For different states (66) of the control branch (38), values (70) characterizing the current generated by the electric coil (30) are detected, which differ as a function of the capacitance of the control branch (38). According to the invention, a state (66) is determined in which the current corresponding to the value (70) is maximum, and the control branch (38) is controlled as a function of the state (66). The invention further relates to an inductive charging device (22) and a system (2).

Description

Technical Field

[0001] The invention relates to a method for operating an inductive charging device for a hearing instrument and an inductive charging device for a hearing instrument. The inductive charging device comprises a voltage source and a resonant circuit connected to the voltage source. In addition, the invention also relates to a system with an inductive charging device and a hearing instrument. Background Art

[0002] People who suffer from hearing loss usually use hearing aids, which are hearing devices. Here, the ambient sound is usually converted into an electrical (audio / sound) signal by means of a microphone, that is, an electromechanical sound converter, so that the electrical signal is detected. The detected electrical signal is processed by means of an amplifier circuit and input into the ear canal of the person by means of other electromechanical converters in the form of earpieces. In addition, the detected sound signal is usually processed, for which a signal processor of the amplifier circuit is usually used. Here, the amplification is matched to the possible hearing loss of the wearer of the hearing device. The (sound) converter and the amplifier circuit are arranged in a housing and are at least partially protected from environmental influences in this way.

[0003] In order to power the various components of the hearing aid, such as the amplifier circuit and the sound converter, batteries are mostly used. This is designed, for example, as a replaceable secondary battery that can be removed from the housing and charged outside the housing. It is therefore necessary that the housing has a minimum size, thereby enabling the battery to be manually removed. In the case of further reducing the structural size of the housing, such removal is no longer possible. In this case, the battery is fixedly installed and charged inside the housing. In order to have as few openings as possible in the housing, so as to prevent, for example, foreign objects from entering the housing through the openings, a charging unit is increasingly arranged in the housing, which has a receiving coil. In addition, in order to charge the battery, the receiving coil is inductively excited by means of an external charging device, so that the battery and thus the hearing aid are wirelessly charged.

[0004] The charging device usually has a resonant circuit connected to a voltage source. During operation, the resonant circuit is excited by means of the voltage source so that an alternating current is conducted by means of the resonant circuit. This results in a time-varying magnetic field which induces an alternating current in the receiving coil for charging the battery. In order to ensure that the energy transferred between the charging device and the hearing instrument is as large as possible, with the charging process being relatively short and with as few losses as possible, the frequency of the magnetic field that is created must be identical to the natural frequency of the resonant circuit of the charging device and to the natural frequency of another resonant circuit that is formed by parts of the charging unit by means of the receiving coil.

[0005] The natural frequency of the resonant circuit of the charging device is set here as a function of the inductance of the charging coil of the resonant circuit and the capacitance of the capacitor of the resonant circuit. However, due to manufacturing tolerances in the components, the natural frequency of the resonant circuit may shift. If this shift is relatively large, the energy captured by the hearing device is relatively low, so that the charging device is essentially unable to charge the hearing device.

[0006] To remedy this problem, for example, components with relatively low manufacturing tolerances can be selected, which, however, increases manufacturing costs. As an alternative, the natural frequencies of the individual resonant circuits can also be determined after each charging device has been produced and compared with the expected natural frequencies. If the deviation is too large, for example, the charging device is discarded and no longer used. As an alternative, for example, the capacitor is removed and replaced by another one. In the alternative, another capacitor is installed that is electrically connected in series or in parallel with the capacitor, so that the natural frequency is offset. In both alternatives, an additional assembly step is required, that is, a mechanical modification of the already installed charging device, which also increases manufacturing costs. It is also possible that in the case of a reassembled capacitor, the capacitor has an unfavorable capacitance due to manufacturing tolerances, which requires new reprocessing. Summary of the invention

[0007] The technical problem to be solved by the present invention is therefore to provide a method which is particularly suitable for operating an inductive charging device for a hearing instrument, as well as a particularly suitable inductive charging device for a hearing instrument and a particularly suitable system comprising an inductive charging device and a hearing instrument, wherein in particular the electrical losses occurring are reduced and wherein the manufacturing costs are suitably reduced and the efficiency is preferably increased.

[0008] According to the invention, this object is achieved with respect to the method by the features of claim 1, with respect to the inductive charging device by the features of claim 3 and with respect to the system by the features of claim 9. Advantageous further developments and embodiments are the subject matter of the respective dependent claims.

[0009] The method is used for operating an inductive charging device for a hearing instrument. The inductive charging device is also referred to below only as a "charging device" and is not a component of the hearing instrument, but is used to charge the hearing instrument. In this case, the charging device is not only suitable for this purpose, but is also arranged and designed for this purpose. For example, the charging device has a holder for the hearing instrument, by means of which the hearing instrument is temporarily held or can be held during the charging process. Preferably, the holder is formed by means of a groove or a hole, into which the hearing instrument can be inserted. After the charging process is completed, the hearing instrument can be spaced apart from the charging device and in particular separated from the charging device.

[0010] For example, the hearing device is a headset or comprises a headset, and for example the hearing device is a headset. However, it is particularly preferred that the hearing device is a hearing aid. The hearing aid is used to support people who suffer from hearing loss. In other words, the hearing aid is a medical device with the help of which, for example, partial hearing loss is compensated. The hearing aid can be, for example, a receiver-in-the-canal hearing aid (RIC), an in-the-ear hearing device, such as an in-ear hearing aid, an in-the-canal hearing aid (ITC) or a completely in-the-canal hearing aid (CIC), hearing glasses, a pocket hearing aid, a bone conduction hearing aid or an implantable hearing aid. Alternatively, the hearing aid is a behind-the-ear hearing aid (Behind-the-Ear hearing aid) that is worn behind the auricle.

[0011] The hearing aid is arranged and designed to be worn on a human body. In other words, the hearing aid preferably comprises a holding device, by means of which it can be fixed on the human body. If the hearing device is a hearing aid, the hearing device is designed and arranged, for example, to be arranged behind the ear or in the ear canal. The hearing device is in particular wireless and is arranged and designed to be at least partially introduced into the ear canal.

[0012] The hearing device comprises, for example, a microphone for detecting sound. In particular, the ambient sound or at least a part of the ambient sound is detected by means of the microphone during operation. The microphone is, in particular, an electromechanical sound converter. The microphone has, for example, only a single microphone unit or a plurality of interacting microphone units. Each microphone unit should have a diaphragm, which is vibrated according to the sound waves, wherein the vibration is converted into an electrical signal by means of a corresponding pickup device, for example a magnet moving in a coil. As a result, an audio signal can be detected by means of each microphone unit, which is based on the sound that strikes the microphone unit. The microphone unit is particularly designed to be omnidirectional. The microphone should be at least partially arranged inside the housing of the hearing device and thus at least partially protected.

[0013] The hearing device should have an earpiece for emitting an output signal. The output signal is in particular an electrical signal. The earpiece is an electromechanical sound converter, preferably a loudspeaker. Depending on the design of the hearing device, the earpiece is at least partially arranged in the ear canal of the hearing device wearer, that is, the person, or is at least acoustically connected to the ear canal in a prescribed state. The hearing device is in particular mainly used to output the output signal by means of the earpiece, wherein the corresponding sound is generated. In other words, the main function of the hearing device is preferably to emit the output signal. The output signal is in particular generated at least partially based on the sound detected by means of the microphone.

[0014] The hearing device should include a signal processor, which forms a signal processing unit or at least a component of a signal processing unit in a suitable manner. However, the hearing device should at least include a corresponding signal processing unit. The signal processor is, for example, a digital signal processor (DSP) or is implemented by means of analog components. With the help of the signal processor, the (audio) signal established by, for example, a microphone is preferably adjusted according to the hearing loss of the wearer of the hearing device. It is in line with the purpose that if the signal processor is designed as a digital signal processor, an A / D converter is arranged between the microphone and the signal processing unit, for example, with the signal processor. The signal processor is adjusted in particular according to a parameter set. Here, the amplification in different frequency ranges is set by means of the parameter set, so that the signal established by the microphone is processed according to a certain set value, in particular according to the hearing loss of the wearer of the hearing device. Particularly preferably, the hearing device also includes an amplifier or the amplifier is at least partially formed by means of the signal processor. The amplifier is connected upstream or downstream of the signal processor, for example, in terms of signal technology.

[0015] The hearing device preferably comprises a charging unit, which is particularly designed for wireless charging of the hearing device, preferably of a battery of the hearing device. For this purpose, the charging unit should be in electrical contact with the battery in the assembled state. Preferably, the battery is a secondary battery and / or the battery is used, for example, to supply power to an earpiece, a microphone and / or a signal processing unit. The battery is particularly used essentially to supply power to all other components of the hearing device. The charging unit is particularly used for wireless reception of electrical energy, so that wireless charging of the hearing device, in particular so-called "wireless charging", can be achieved with the help of the charging unit. In this case, the charging unit preferably interacts with the charging device.

[0016] The charging device has a voltage source, by means of which a voltage, for example a direct voltage or particularly preferably an alternating voltage, is provided. The voltage is in particular less than 60 V and is, for example, 12 V or 5 V. In addition, the charging device also includes a resonant circuit connected to the voltage source. As a result, the resonant circuit can be operated by means of the voltage source, for which purpose in particular a current is conducted from the voltage source to the resonant circuit. The resonant circuit has a charging coil, which is in particular an electrical winding. A specific inductance is thus provided by means of the charging coil. In addition, the resonant circuit has a capacitor. Preferably, the resonant circuit is formed by means of the charging coil and the capacitor.

[0017] The capacitor has a main capacitor. In addition, the capacitor also has a regulating branch connected in parallel with the main capacitor. The regulating branch is adjustable, and the capacitance (size) of the regulating branch can be changed by adjusting the regulating branch. A plurality of states are defined, wherein the capacitance of the regulating branch is different in each state. In particular, there are at least two different settings, so that the regulating branch has two corresponding states. Since the regulating branch is connected in parallel with the main capacitor of the resonant circuit, the capacitance of the resonant circuit is also different from each other in different states. Therefore, it can also be achieved that the natural frequency of the resonant circuit is changed by adjusting the regulating branch. In other words, each state corresponds to a different natural frequency of the resonant circuit.

[0018] For example, the capacitance is formed only by means of a main capacitor and a regulating branch. However, it is particularly preferred that the capacitance also includes one or more, preferably two, further capacitors, which are also referred to below as secondary capacitors and are electrically connected in series with the main capacitor, in particular. The capacitance provided can be increased in particular by means of secondary capacitors. Preferably, the capacitance of the main capacitor is between 5 nF and 10 nF, and the secondary capacitor has, for example, a capacitance of 1 nF to 5 nF. Preferably, the main capacitor and the secondary capacitor are designed differently from each other, so that the capacitance of the resonant circuit can be selected relatively freely.

[0019] According to the method, a value characterizing the current generated by the charging coil due to the change in capacitance is detected for different states of the control branch, in particular for all states of the control branch. In other words, the voltage source is operated and the value is detected. In this case, the value characterizes the current flowing through the charging coil, which current is different due to the change in capacitance. Preferably, a one-to-one assignment of current to the individual values ​​is formed in this case. Expediently, the voltage source is always operated in the same way when detecting the value, so that different currents and thus different values ​​are only formed due to the correspondingly different capacitances.

[0020] In a subsequent working step, the state is determined in which the current corresponding to the value is at a maximum. Thus, if, for example, the characteristic value is substantially consistent with or proportional to the current, the maximum value of the value and the state in which the value is detected are determined. In this case, the smaller the deviation of the natural frequency of the resonant circuit from the frequency used to operate the resonant circuit (in particular the frequency of the alternating voltage provided by the voltage source) when the voltage source is operated in the same manner, the greater the current.

[0021] The regulating branch is then regulated according to the state, i.e. the state in which the current corresponding to the value is maximum. The resonant circuit is thereby regulated such that the current flowing through the charging coil is maximum when operating with a voltage source. This results in a relatively efficient operation of the resonant circuit and thus a relatively efficient energy transfer to the hearing device. In other words, due to the regulation of the capacitance, the natural frequency of the resonant circuit is matched to the voltage source used, so that the energy efficiency in the energy transfer to the hearing device, i.e. the energy efficiency in the charging of the hearing device, is maximum and the losses are relatively small. This increases the efficiency.

[0022] Due to the controllability of the control branch, relatively high currents can be achieved with each charging device, wherein components with high manufacturing tolerances can be used for the charging coil and the capacitor of the resonant circuit, thereby reducing material costs and thus also manufacturing costs. It is also possible to continue to use essentially every charging device, thus reducing the scrap rate. In this case, no mechanical reworking of the charging device is necessary, which also keeps the manufacturing costs relatively low.

[0023] For example, a current can be used as a characterizing value. However, it is particularly preferred to use a voltage as a characterizing value, which voltage is particularly dropped across the measuring resistor. In this way, relatively inexpensive sensors can be used, thus further reducing production costs. The measuring resistor is here connected in particular relative to the resonant circuit and, for example, in parallel with the main capacitor or with other components of the resonant circuit, for example, with the secondary capacitor or one of the possible secondary capacitors.

[0024] For example, the method is implemented each time the charging device is used, for example when it is switched on or powered on, that is, in particular, at each restart. In this way, the aging effects of the main capacitor and other components of the charging device are particularly taken into account, so that the charging device has relatively good functionality over a longer period of time. As an alternative, the method is implemented at certain time intervals or under certain conditions. As an alternative, the method is implemented only once, for example, after the charging device has been manufactured or when it has been produced. As a result, manufacturing tolerances of the components are compensated after mechanical manufacturing, and the charging device can be put into use basically immediately each time the user uses it. In addition, there is no need for the user to perform corresponding operations, which improves comfort.

[0025] For example, the regulation branch is regulated manually, for example by mechanical actuation of a mechanical switch or the like, which is arranged, for example, in the housing of the charging device. However, it is particularly preferred that the regulation is carried out by means of the electronics of the charging device, which reduces the effort and can also be carried out when the housing of the charging device is closed.

[0026] Expediently, the charging process of the hearing instrument is started after the adjustment. Thus, for charging the hearing instrument, the adjustment of the resonant circuit is used, in which the efficiency is at a maximum, so that the charging process of the hearing instrument is completed relatively quickly.

[0027] The inductive charging device is suitable for, in particular designed and arranged for charging hearing devices. The inductive charging device has a voltage source and a resonant circuit connected to the voltage source, the resonant circuit having a charging coil and a capacitor. The voltage source has a transformer and an inverter, in particular, the inverter can be connected to the power supply network by a connection. The capacitor has a main capacitor and a regulating branch connected in parallel with it. Here, the regulating branch has a plurality of states, wherein each state is achieved by means of a corresponding adjustment of the regulating branch. In this case, the capacitance of the regulating branch generated in different states is different, and thus the capacitance of the resonant circuit is different. In other words, in each state, the capacitance connected in parallel with the main capacitor is different, and thus the capacitance generated by the resonant circuit is different. Thus, the capacitance of the resonant circuit can be changed according to the adjustment of the regulating branch. In other words, in each different state of the regulating branch, the resonant circuit has different capacitances and therefore also has different natural frequencies. Preferably, the capacitor further includes one or more auxiliary capacitors, which are electrically connected in series with the main capacitor and are not bridged by the regulating branch in particular.

[0028] The inductive charging device is operated according to the method, wherein values ​​characterizing the current generated by the charging coil are detected for different states of a control branch, the different states differing according to the capacitance of the control branch. The state is determined in which the current corresponding to the value is maximum. Furthermore, the control branch is regulated according to the state.

[0029] The charging device has in particular a control device, by means of which the method is at least partially implemented. In other words, the control device is suitable for, in particular designed and provided for implementing the method. The control device is hereby formed, for example, by means of discrete components, or the control device has, for example, a microcontroller, which should be designed to be programmable.

[0030] For example, the regulating branch has an adjustable capacitor, which is in particular electrically operable. However, it is particularly preferred that the regulating branch has a regulating path with an auxiliary capacitor and a switching element electrically connected in series with the auxiliary capacitor. The switching element is in particular an electrical switch, such as a transistor or a MOSFET. As an alternative, the switching element is, for example, a thyristor, thereby reducing the energy demand. By means of the regulation of the switching element, at least two of a plurality of states are defined here. In other words, in at least two of a plurality of states, the switching state of the switching element is different. If the switching element is electrically conductive, the auxiliary capacitor is electrically connected in parallel with the main capacitor, thereby increasing the capacitance of the resonant circuit. On the contrary, if the switching element is disconnected, that is, in a state of not being electrically conductive, the capacitance of the resonant circuit is not increased, and is, for example, only given by means of the main capacitor and a possible auxiliary capacitor. Thus, at least two of a plurality of states of the regulating branch can be switched by means of the control of the switching element, and the regulating branch is set accordingly, and manual operation should not be required for this. Thus, the comfort is improved, and the method can also be implemented substantially automatically.

[0031] For example, the regulating branch is formed by means of a regulating path. However, it is particularly preferred that the regulating branch has a plurality of regulating paths of this type which are electrically connected in parallel with each other. The plurality of states are here particularly defined by means of the switching state of the switching element. For example, all auxiliary capacitors are constructed identically to each other here. However, it is particularly preferred that the auxiliary capacitors can also be different from each other, thereby increasing the number of different states. In particular, the one regulating path or each regulating path is connected in parallel with the main capacitor. For example, the regulating branch comprises 3, 4, 5 or more regulating paths of this type. Suitably, the number of regulating paths is less than 10. Preferably, the number of regulating paths is 2. As a result, the number of required components and the necessary space are relatively low, thereby reducing manufacturing costs.

[0032] Therefore, if there are two control paths, whose auxiliary capacitors differ from one another, there are four states in total. Based on the four different states, it is possible to change the capacitance of the resonant circuit relatively comprehensively so that its natural frequency can be adjusted to the desired value, that is, in particular to the frequency of the alternating voltage provided by the voltage source.

[0033] For example, the charging device includes a current sensor for detecting the value, such as a Hall sensor arranged in the area of ​​the charging coil. However, it is particularly preferred that the inductive charging device includes a voltage sensor for detecting the value. In other words, the value is a voltage, that is, preferably a voltage on a measuring resistor. In particular, the measuring resistor is electrically connected in parallel with, for example, a secondary capacitor. Here, the measuring resistor is electrically connected in series with a diode (German: geführt) connected to the relative resonant circuit. As a result, only a half-wave of the corresponding voltage source / current is conducted through the diode. As a result, rectification is achieved with the aid of a diode, so that only one polarity of the voltage needs to be further processed, thereby simplifying the design of the voltage sensor. Manufacturing costs are further reduced thereby. In summary, the voltage sensor is designed to detect the value, that is, to measure the voltage on the measuring resistor, and the measuring resistor is electrically connected in series with a diode connected to the relative resonant circuit. Here, the measuring resistor is in particular an ohmic resistor or a component such as a shunt.

[0034] For example, only a voltage sensor, a measuring resistor and a diode are present. However, it is particularly preferred that a measuring capacitor is connected in parallel with the measuring resistor. The measuring capacitor is used to smooth the voltage across the measuring resistor. As a result, the value does not fluctuate or fluctuates only slightly, which simplifies further processing, in particular the determination of the maximum value.

[0035] For example, the diode is connected directly to the resonant circuit. However, it is particularly preferred that the diode is connected to the resonant circuit via a voltage divider. As a result, only a relatively small voltage appears at the measuring resistor, thus reducing the load on the components. Inexpensive components can be used. Moreover, fluctuations at components that are only slightly loaded are reduced, which increases accuracy. In particular, the voltage divider is electrically connected in parallel with one of a possible plurality of secondary capacitors.

[0036] The system has a hearing device and an inductive charging device. The hearing device is, for example, a headset or a headphone. Particularly preferably, the hearing device is a hearing aid and is used to support people with at least partial hearing loss. As an alternative, the hearing device is particularly configured as a so-called tinnitus masker, that is, in particular for the treatment of tinnitus. For example, the hearing aid can be, for example, a receiver-in-the-canal hearing aid (RIC), an in-ear hearing device, such as an in-ear hearing aid, an in-the-canal hearing aid (ITC) or a completely in-the-canal hearing aid (CIC), hearing glasses, a pocket hearing aid, a bone conduction hearing aid or an implantable hearing aid. Alternatively, the hearing aid is a behind-the-ear hearing aid (Behind-the-Ear hearing aid) worn behind the auricle.

[0037] The hearing device preferably has a battery, by means of which, in particular, other components of the hearing device are energized during operation. Preferably, the battery is a secondary battery and is mounted in a housing of the hearing device in a suitable manner, that is, in particular, non-detachably. In addition, the hearing device should have a charging unit, which is used to charge the hearing device, in particular the battery. The charging unit is suitable for this, is provided and arranged in particular for this purpose. The charging unit is particularly suitable, designed and arranged in a suitable manner for wireless charging. The charging unit is arranged in a suitable manner in the housing of the hearing device. Preferably, the charging unit has a receiving coil and is in electrical contact, preferably direct electrical contact, for example with the battery.

[0038] The charging device comprises a voltage source and a resonant circuit connected thereto, the resonant circuit having a charging coil and a (electric) capacitance, the capacitance having a main capacitor and a regulating branch connected in parallel with the main capacitor. The charging device is operated according to the method, wherein a value characterizing a current generated by the charging coil is detected for different states of the regulating branch, the different states differing according to the capacitance of the regulating branch. The state is determined in which the current corresponding to the value is at a maximum, and the regulating branch is regulated according to the state.

[0039] In particular, it is possible for the hearing instrument and the inductive charging device to be inductively coupled. The charging device has, for example, a holder for at least temporarily fixing the hearing instrument, preferably during a charging process.

[0040] The advantages and developments described with regard to the method may also be transferred to the method / hearing device and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The embodiments of the present invention are described in more detail below with the aid of the accompanying drawings. In the accompanying drawings:

[0042] Figure 1 A simplified circuit diagram of a system with a hearing device and an inductive charging device is schematically shown, and

[0043] Figure 2 A method for operating an inductive charging device is shown.

[0044] Parts that correspond to one another are provided with the same reference symbols in all the figures. DETAILED DESCRIPTION

[0045] exist Figure 1Schematically shown is a simplified circuit diagram of a system 2, which includes a hearing device 4. The hearing device 4 is a hearing aid and is used to provide support to a user, not specifically shown, when the user's hearing is at least partially impaired. For this purpose, the hearing device 4 has a microphone 6, which is acoustically coupled to an opening, not specifically shown, of a hearing device housing 8. A signal processing unit 10 is connected to the microphone 6 in terms of signal technology, and the signal processing unit has a digital signal processor (DSP) not specifically shown. The electrical signal provided by the microphone 6 is appropriately processed during operation by means of the signal processing unit 10 in order to compensate for the hearing impairment of the user and to eliminate possible interfering noise. An earpiece 12 is connected to the signal processing unit 10 in terms of signal technology, and the earpiece is acoustically connected to another opening of the hearing device housing 8. The sound waves generated by means of the earpiece 12 are conducted out of the hearing device housing 8 through the other opening. In the proper state of the hearing device 4 , the hearing device housing 8 is inserted into the ear canal of the user, wherein the opening of the hearing device housing 8 for the acoustic connection to the microphone 6 is on the side facing away from the eardrum, while the opening associated with the earpiece 12 is on the side of the hearing device housing 8 facing the eardrum.

[0046] The microphone 6 and the earpiece 12 are also operated with the aid of a signal processing unit, and for supplying power to the signal processing unit 10, the hearing device 4 has a battery 14 which is fixedly mounted in the hearing device housing 8. The hearing device 4 comprises a charging unit 16 which is also arranged in the hearing device housing 8 and comprises a receiving coil 18 which is electrically in contact with a further unit 20 of the charging unit 16. A rectifier and a charge regulator are provided with the aid of the further unit 20, and the further unit is in electrical contact with the battery 14. This makes it possible to charge the battery 14 inductively, so that no further openings are required in the housing 8, apart from the openings provided for the microphone 6 and the earpiece 12. This results in a relatively high degree of sealing of the hearing device 4.

[0047] For charging the hearing instrument 4, the system 2 comprises an inductive charging device 22, which is also referred to as "charging device". The charging device 22 has a housing 24, in which a voltage source 26 is arranged. During operation, an AC voltage of, for example, 12 V is provided by means of the voltage source 26. For this purpose, the voltage source 26 has a transformer (not shown in detail) which can be connected to an AC power grid as a power supply grid via a plug (not shown in detail). In this case, the housing 24 is arranged as a whole, except for the plug, so that it is also relatively sealed.

[0048] A resonant circuit 28 is connected to a voltage source 26, which is electrically connected in parallel with the voltage source 26. The resonant circuit 28 has a charging coil 30, which is an electrical winding. The inductance of the charging coil 30 is 96.4 nH in the example described. In addition, the resonant circuit 28 includes a capacitor 32, which is electrically connected in series with the charging coil 30. The natural frequency of the resonant circuit 28 is determined by means of the capacitor. When the voltage source 26 is in operation, the resonant circuit 28 is excited to oscillate, wherein the frequency of the current conducted is given by the applied alternating voltage. The more closely the two frequencies coincide, the greater the current conducted by the resonant circuit 28, and the stronger the time-varying magnetic field generated by means of the charging coil 30.

[0049] The capacitor 32 has a main capacitor 34, which has a capacitance of 6.6 nF. Two secondary capacitors 36 are electrically connected in series with the main capacitor 34, one of which has a capacitance of 4.8 nF and the other of which has a capacitance of 2.8 nF. If the charging coil 30 and the capacitors 34, 36 had no manufacturing tolerances, the resonant frequency of the resonant circuit 28 would in particular be 13.556 MHz. However, due to manufacturing tolerances in the components, the natural frequency of the resonant circuit 28 may shift. Therefore, a control branch 38 is electrically connected in parallel with the main capacitor 28, which has two control paths 40 electrically connected in parallel with each other. In this case, each control path 40 is connected in parallel with the main capacitor 34.

[0050] Each control path 40 has an auxiliary capacitor 42, which is electrically connected in series with a switching element 44. The capacitances of the two auxiliary capacitors 42 are different here, and one is 0.47 nF and the other is 1.5 nF. In contrast, the two switching elements 44 are designed identically to one another and are each formed by a MOSFET operated by a suitable control circuit.

[0051] Furthermore, the charging device 22 has a measuring circuit 46, which is connected in parallel with one of the auxiliary capacitors 36, namely with a capacitance of 2.8 nF. The measuring circuit 46 has a voltage divider 48 with two resistors 65 electrically connected in series. The voltage divider 48 is connected in parallel with the respective auxiliary capacitor 46, and one of the resistors 50 is bridged by a series circuit consisting of a diode 52 and a measuring resistor 54. The measuring resistor 54 is thus electrically connected in series with the diode 52 connected to the resonant circuit 28, wherein the diode 52 is connected to the resonant circuit 28 via the voltage divider 48. A measuring capacitor 56 is connected in parallel with the measuring resistor 54.

[0052] The measuring circuit 46 also has a voltage sensor (not shown in detail) for measuring the voltage across the measuring resistor 54. In this case, due to the diode 52, the voltage across the measuring resistor 54 has only one polarity and the voltage is also smoothed by means of the measuring capacitor 56, so that although an AC voltage is conducted by means of the resonant circuit 28 during operation, the resulting voltage is essentially a DC voltage.

[0053] Furthermore, the charging device 22 has a control device 58, by means of which the voltage source 26, the switching element 44 are controlled and the voltage sensor is read. Figure 2 , to operate inductive charging device 22 . In other words, charging device 22 is operated according to method 60 , and control device 58 is configured and designed to carry out method 60 .

[0054] The method 60 begins with a first working step 62. The first working step 62 is carried out after the preparation of the charging device 22 is completed, that is, after the charging device is mechanically assembled but not yet used. Therefore, this part of the method 60 is carried out in particular in a workshop or, for example, at the manufacturer.

[0055] In the subsequent second working step 64, the control branch 38 is controlled according to one of four predefined states 66. In this state 66, both switching elements 44 are open, so that the control path 40 is electrically isolated. As a result, the size of the capacitance of the auxiliary capacitor 42 does not influence the size of the capacitance 32 of the resonant circuit 28. In addition, the voltage source 26 is operated and thus the resonant circuit 28 is excited. As a result, a current flows through the charging coil 30.

[0056] In a subsequent third working step 68, a value 70 is detected, which characterizes the current generated by charging coil 30. The voltage at measuring circuit 54 is used as the characterizing value 70, which is also smoothed by means of measuring capacitor 56. Due to the rectification by means of diode 52, value 70 is only positive here. In this example, value 70 is therefore greater the greater the current conducted by charging coil 30.

[0057] This value 70 is stored, and then the second working step 64 is carried out again, but in this case a different state 66 of the control branch 38 is selected. In this different state, one of the two switching elements 44 is closed, so that the auxiliary capacitor 42 associated with this control path 40 contributes to the magnitude of the capacitance 32 of the resonant circuit 28. As a result, the natural frequency of the resonant circuit 28 changes compared to the second working step carried out previously, and thus also the magnitude of the current conducted by the charging coil 30. As a result, the value 70 detected in the third working step 68 carried out later also changes. This value is also stored.

[0058] The second working step 64 is then carried out again, in which the changed state 66 of the control path 38 is used again. In this state, the other switching element 44 is electrically conductive, and the previously electrically conductive switching element 44 is set to a non-conductive state. And for this state 66, the value 70 is detected and stored in the third working step 68 that is carried out later.

[0059] Subsequently, the second working step 64 is carried out for the last time, wherein the current state 66 corresponds to a control of the control branch 38 in which both switching elements 44 are closed, ie, electrically conductive. The value 70 is again detected and stored.

[0060] Here, for the different implementations of the second and third working steps 64 and 68, the size of the capacitor 32 is different, and the natural frequency of the resonant circuit 28 is also different. Therefore, the current conducted by the charging coil 30 is also different, even if the voltage source 26 is always operated in the same way. Here, the smaller the deviation between the natural frequency of the resonant circuit 28 and the frequency of the AC voltage provided by the voltage source 26, the greater the current. Therefore, all detected values ​​70 are also different. In summary, in the second and third working steps 64 and 68, for four different states 66 of the control branch 38 (different according to the different capacitances of the control branch 38), the value 70 that characterizes the current generated by the charging coil 30 is detected. Here, in each of the two states 66, the switching state of one of the two switching elements 44 is different. In a solution not specifically shown, the control branch 38 has a plurality of corresponding control paths 40, thereby increasing the number of states 66. Therefore, the second and third working steps 64 and 68 are also implemented more frequently.

[0061] Once the values ​​70 have been detected for all states 66, a fourth working step 72 is carried out. In this working step, the maximum of the detected values ​​70 is determined, i.e., the value 70 at which the corresponding current is the largest. It is then determined which state 66 corresponds to this value 70. In other words, the state 66 is determined in which the value 70 is the largest. Thus, the state 66 is determined in which the natural frequency of the resonant circuit 28 is closest to the frequency of the voltage provided by the voltage source.

[0062] Control branch 38 is regulated as a function of state 66, that is, the switching state of two switching elements 44 is selected accordingly. For this purpose, in particular, the corresponding switching states of two switching elements 44 are stored in a memory of control device 58, so that when charger 22 is restarted, a corresponding control of switching elements 44 can be performed substantially immediately. Control device 58 is designed in this case so that when charger 22 is powered on, switching elements 44 can only be controlled according to this regulation if the corresponding memory is written. The part of method 60 for regulating charger 22 is then terminated.

[0063] In a subsequent fifth working step 74, the proximity of the hearing instrument 4 to the charging device 22 is detected by means of a sensor or the like (not shown in detail). In this case, a charging process 76 is started. For this purpose, the resonant circuit 28 is excited by means of the voltage source 26, so that a time-varying magnetic field is established by means of the charging coil 30. As a result, the nearby receiving coil 28 induces an alternating current, which is further processed by means of the further unit 20, so that the battery 14 is charged.

[0064] When the battery 14 is fully charged or the hearing instrument 4 is removed from the charging device 22, a sixth working step 78 is carried out and the voltage source 26 is switched off. This ends the charging process 76. As soon as the hearing instrument 4 is brought close to the charging device 22 again or the battery 14 is at least partially discharged, the fifth working step 74 is carried out again. Thus, in the method 60, the state at which the value 70 is maximum is determined only once and the control path 38 is adjusted accordingly. In contrast, a plurality of charging processes 76 are carried out in the method 60.

[0065] The present invention is not limited to the above-mentioned embodiments. Instead, those skilled in the art can derive other variations of the present invention therefrom, as long as they do not depart from the technical solution of the present invention. In addition, all individual features described in conjunction with the embodiments can be combined with each other in other ways, as long as they do not depart from the technical solution of the present invention.

[0066] Reference numerals list

[0067] 2 System

[0068] 4. Hearing equipment

[0069] 6 Microphone

[0070] 8Hearing device housing

[0071] 10Signal processing unit

[0072] 12 Earpiece

[0073] 14 Batteries

[0074] 16 Charging Units

[0075] 18 receiving coil

[0076] 20 Additional power supplies

[0077] 22Inductive charging equipment

[0078] 24 Shell

[0079] 26 Voltage Source

[0080] 28 Resonance Circuit

[0081] 30 Charging coil

[0082] 32 Capacitor

[0083] 34 Main capacitor

[0084] 36 capacitors

[0085] 38 regulating branch

[0086] 40 Adjustment Path

[0087] 42 auxiliary capacitor

[0088] 44 Switching elements

[0089] 46 Measurement Circuit

[0090] 48 Voltage Divider

[0091] 50 resistor

[0092] 52 diode

[0093] 54 Measuring resistance

[0094] 56 Measuring capacitor

[0095] 58 Control Equipment

[0096] 60 Methods

[0097] 62 First working step

[0098] 64 Second working step

[0099] 66 Status

[0100] 68 Third working step

[0101] 70 value

[0102] 72Fourth working step

[0103] 74 Fifth working step

[0104] 76 Charging process

[0105] 78Sixth working step.

Claims

1. A method (60) for operating an inductive charging device (22) of a hearing instrument (4), the inductive charging device comprising a voltage source (26) and a resonant circuit (28) connected to the voltage source, the resonant circuit comprising a charging coil (30) and a capacitor (32), the capacitor having a main capacitor (34) and a regulating branch (38) connected in parallel with the main capacitor, wherein: - detecting a value (70) representative of the current generated by the charging coil (30) for different states (66) of the regulating branch (38), the different states being different depending on the capacitance of the regulating branch (38), - determining a state (66) in which the current corresponding to said value (70) is maximum, and - regulating the regulating branch (38) as a function of the state (66).

2. The method (60) according to claim 1, characterized in that: After the adjustment, a charging process (76) of the hearing instrument (4) is started.

3. An inductive charging device (22), comprising a voltage source (26) and a resonant circuit (28) connected to the voltage source, the resonant circuit comprising a charging coil (30) and a capacitor (32), the capacitor having a main capacitor (34) and a regulating branch (38) connected in parallel with the main capacitor, and the charging device is operated according to the method (60) of claim 1 or 2.

4. The inductive charging device (22) according to claim 3, characterized in that: The regulating branch (38) has a regulating path (40) comprising an auxiliary capacitor (42) and a switching element (44) electrically connected in series with the auxiliary capacitor, wherein the switching state of the switching element (44) is different in at least two of a plurality of states (66).

5. The inductive charging device (22) according to claim 4, characterized in that: The control branch (38) has a plurality of such control paths (40) which are electrically connected in parallel with one another.

6. The inductive charging device (22) according to any one of claims 3 to 5, characterized in that: A voltage sensor is provided which is designed to detect the value (7), namely to measure the voltage across a measuring resistor (54) which is electrically connected in series with a diode (52) connected to the resonant circuit (28).

7. The inductive charging device (22) according to claim 6, characterized in that The measuring capacitor (56) is connected in parallel with the measuring resistor (54).

8. The inductive charging device (22) according to claim 6 or 7, characterized in that: The diode (52) is connected to the resonant circuit (28) via a voltage divider (48).

9. A system (2) comprising a hearing device (4) and an inductive charging device (22) according to any one of the preceding claims 3 to 8.

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