Patent ID: 12212932

DETAILED DESCRIPTION

FIG.1illustrates schematically the basic electronics of a hearing aid5according to one embodiment of the invention. The hearing aid5has at least one input transducer or microphone6picking up an audio signal. The audio signal is digitized and fed to digital signal processor7adapted for amplifying and conditioning of the audio signal intended to become presented for the hearing aid user. The amplification and conditioning are carried out according to a predetermined setting stored in the hearing aid5to alleviate a hearing loss by amplifying sound at frequencies in those parts of the audible frequency range where the user suffers a hearing deficit. The amplified and conditioned audio signal is reproduced for the user via a receiver or speaker8. The microphone6, digital signal processor7, and speaker8provides an audio signal path with hearing loss alleviation.

The hearing aid5includes an RF switch11adapted for connecting an antenna10to either a transceiver13, or a wireless charging unit provided by a rectifying and filtering circuit14and a battery controller15. A processor12controls the RF switch11. In one embodiment, the transceiver13is adapted for communication with other devices via a wireless technology standard, e.g. Bluetooth, over short distances. These other devices may include another hearing aid for providing a binaural set of hearing aids, smartphones of streaming, phone conversation or remote control, or dedicated devices like remote microphones, streamers or remote controls.

The hearing aid5is adapted for being recharged by inductive charging (wireless charging) when placed in a charging stand or on a charging pad providing an electromagnetic field to transfer energy to the hearing aid using electromagnetic radiation. In one embodiment, the hearing aid5just have to be adjacent to the charging pad for charging. A sensor21detects when the hearing aid5is placed in the charging stand. The sensor21may be a magnetic sensor, e.g. a Reed switch operated by an applied magnetic field. The processor12receives input from the sensor21.

The rectifying and filtering circuit14converts an alternating current (AC) picked up by the antenna10, which periodically reverses direction, to direct current (DC) with ripples substantially smoothened. The rectifying and filtering circuit14delivers the direct current to the battery controller15.

The battery controller15adapted for controlling the charging and discharging of a rechargeable battery16. The battery controller15is integrated in a hearing assistive device, e.g. a hearing aid5shown inFIG.2. During charging, the charging voltage is delivered via the rectifying and filtering circuit14to a set of conductive paths or wires18and therefrom to the input terminals IN+ and IN− of the battery controller15. When the input terminals IN+ and IN− are powered, the hearing assistive device will be in charging state. The output voltage from the rectifying and filtering circuit14is connected to IN+ and the IN− terminal is connected to the ground of the rectifying and filtering circuit14.

The rechargeable battery16is in one embodiment a lithium-ion. The rechargeable battery16is via a set of conductive paths or wires19connected with the positive terminal to a B+ pin of the battery controller15, while the negative terminal is connected to a B− pin of the battery controller15. The battery controller15acts as a module for controlling the charging and discharging of the rechargeable battery16, and therefor also for controlling the power supply to the electronic circuits in the hearing aid5.

In charging state60(inFIG.6) with the hearing aid5placed in a charging stand or charging pad, the voltage present on the input pins IN+ and IN− will be passed to the battery pins B+ and B−. The charging process is controlled by the battery controller15. The charging current of the battery controller15depends on size of the rechargeable battery16. In one embodiment the charging current will be significantly below 1 mA, it can be controlled by adjusting a resistor internally in the battery controller15. When the battery controller15has charged the rechargeable battery16completely, it will in one embodiment automatically stop charging. A charging stand will then communicate, e.g. by turning a LED on to the user, that the charging has been completed. The battery controller15will then leave charging state and may enter a connected state61or a stand-alone state62(inFIG.6). By leaving the charging state, the battery controller15will disconnect the input terminals IN+ and IN− from the battery pins B+ and B−.

The battery controller15manages the rechargeable battery16, such as ensuring that the battery16operates inside its recommended operating state, and e.g. is calculating secondary data, reporting that data, controlling and authenticating the relevant environment including the charging stand.

In the connected state61or the stand-alone state62, the rechargeable battery16will power the electronics of the hearing assistive device. Two output pins OUT+ and OUT− are connected to the circuit to be powered by the rechargeable battery16via a pair of conducting paths or wires17. The OUT+ pin the outputs the positive voltage from the rechargeable battery16, and the OUT− pin outputs the negative voltage and should be connected to the ground of circuit which has to be powered by the rechargeable battery16.

The battery controller15will monitor the voltage of the rechargeable battery16as it powers the electronics of the hearing aid5via the wires17. The battery controller15has a status output delivered via a wire20to the processor12.

FIG.2illustrates a hearing aid5according to one embodiment of the invention. The hearing aid5is an In-The-Ear (ITE) hearing aid having a custom molded shelf23manufactured to fit into the ear canal of the hearing aid user. The invention is in the illustrated embodiment applicable for hearing aids placed in the ear canal, both partly and completely. However, the invention may also be useful for e.g. Receiver-In-Canal (RIC) hearing aids or Behind-The-Ear (BTE) hearing aids. The hearing aid5has a face plate22with not shown microphone opening for the microphone6and not shown control buttons for controlling the operation of the hearing aids5. The face plate22and the custom molded shelf23form a cavity in which the electronics of the hearing aid is hosted.

Opposite to the face plate22, the custom molded shelf23has a sound outlet for the speaker8.

The custom molded shelf23may be manufactured in a 3D printing process building a three-dimensional object from a computer-aided design (CAD) model. The 3D printing process relies on successively adding material layer by layer, which is why it is also called additive manufacturing. An example may be Stereolithography in which a light-emitting device selectively illuminate the transparent bottom of a tank filled with a liquid photo-polymerizing resin. The solidified resin is then progressively dragged up by a lifting platform.

The hearing aid5is shown as contained in a charging stand having a cavity provided by a container26and a lid27.

The antenna10, is in the embodiment illustrated with reference toFIG.3andFIG.4provided on or integrated in the face plate22. The face plate22is manufactured by injection molding an appropriate plastic material, why the face plate22will act as a dielectric material.FIG.3shows a cross-section of the face plate22, and on the inner surface, the faceplate22is covered by a metallic pattern or layer serving a ground plane25for the antenna. In one embodiment, the ground plane25covers a significant part (+75%) of the face plate22facing towards the cavity in which the electronics of the hearing aid is hosted. On the outer surface of the faceplate22, there is provided resonating (radiating) antenna elements30. These antenna elements30are connected to the RF switch11via an antenna feed31passing through the faceplate22. Finally, the antenna elements30are covered by a thin layer24of a protective plastic material.

The antenna elements30are in one embodiment applied to the face plate22in a photolithographic process, where light is used to transfer a geometric pattern from a photomask to a photosensitive chemical photoresist on the faceplate22(substrate). In one embodiment, a Laser Direct Structuring (LDS) process employs a thermoplastic material doped with a (non-conductive) metallic inorganic compound, which is activated by means of laser.

In one embodiment the antenna elements30is arranged on a separate printed circuit board (e.g. on a flex print) adjacent to the face plate inside the cavity provided by the faceplate22and the custom molded shelf23.

In yet another embodiment, the first branch32and the second branch33are arranged along a ground plane25. The first branch32and the second branch33are arranged on the inner surface of the faceplate22, and the ground plane25is arranged on a printed circuit board inside the hearing assistive device5.

FIG.4illustrates schematically the outer surface of the faceplate22and it is that resonating (radiating) antenna elements30comprises a first branch32and a second branch33. According to the invention, the first branch32has a first resonance frequency adapted for radio communication, and the second branch33has a second resonance frequency adapted for wireless charging.

The resonating (radiating) antenna elements30provides a single monopole antenna that covers two different frequency bands. These two different frequency bands may include the ISM band at 2.4 GHz used by Bluetooth, and an appropriate frequency for wireless charging. When using a high-frequency resonant tank (e.g. 6.78 MHz) compliant with the Qi technology, it is possible to transmit power over long distances (typically half a meter or more).

The antenna elements30operates in one embodiment as a monopole which is a resonant antenna. The monopole operates as an open resonator for radio waves, oscillating with standing waves of voltage and current along its length. Therefore, the length of the antenna is determined by the wavelength of the radio waves it is used with. In one embodiment the monopole is the quarter-wave monopole, in which the antenna is approximately one quarter of the wavelength of the radio waves.

By applying appropriate matching components, including a capacitor and an inductor, it is possible to shorten the physical length of the two branches and obtain the desired electric length. The matching components may be used for antenna tuning. Furthermore, it is possible to cover almost any two frequency bands by the concept according to the invention by changing lengths of the branches and sizes of the matching components.

The lengths of the two branches32and33may also be changed by using a dielectric material, e.g. the face plate manufactured from a plastic material, for separating branches32and33from the ground plane25.

FIG.5illustrates one embodiment of the antenna elements30, where the antenna feed31feeds a first resonating branch32comprising a common antenna section50and a first stub section51, and a second resonating branch33comprising the common antenna section50and a second stub section52. The two resonating branches do also in this embodiment have resonance frequencies adapted for wireless charging, and radio communication, respectively.

FIG.6illustrates schematically a state diagram for a hearing aid5according to one embodiment of the invention. The hearing aid5has a sensor21detecting whether, the hearing aid5is placed in the not-shown charging stand or not. Then the processor12will instruct the battery controller15to start charging the rechargeable battery16. The processor12instructs the RF switch12to disconnect the antenna10from the transceiver13and to direct currents picked up by the antenna towards the rectifying and filtering circuit14and further towards the battery controller15for charging the rechargeable battery16.

Once the battery controller15informs the processor12that the charging of the rechargeable battery16has been completed, the processor12changes the state of the hearing aid5to be either connected state61or stand-alone state62. In one embodiment the hearing aid5will enter the stand-alone state62and remain there as long as the hearing aid5remains in the not-shown charging stand. In the stand-alone state62the processor12disables the transceiver13and disconnects the antenna10from the electronics of the hearing aid5. In case the hearing aid5stays in the charging stand26,27for long time, the battery controller15will monitor the status of the rechargeable battery16and communicate to the processor12if recharging is necessary and the charging state60must be reentered. Otherwise the hearing aid5will automatically change state from stand-alone state62to connected state61when the sensor21detects and communicates to the processor12that the hearing aid5is no longer placed in the charging stand26,27.

According to the invention, the antenna component30comprises two branches32and33. In one embodiment, the two branches32and33are provided as monopole antennas. Monopole antennas constitutes a class of radio antennas consisting of a straight rod-shaped conductor. The driving signal from the transmitter is applied to a feed in the end. The monopole is a resonant antenna, and the rod functions as an open resonator for radio waves, oscillating with standing waves of voltage and current along its length. Therefore, the length of the antenna is determined by the wavelength of the radio waves it is used with. In one embodiment, the two branches32and33are arranged in parallel with a ground plane25. Hereby the monopoles operate as inverted-L-antennas.

The inverted-L antenna is a monopole antenna bent over to run parallel to the ground plane. This provides the advantage of compactness and a shorter length than the214monopole can be obtained. However, the inverted L antenna has the disadvantage of a very low impedance. An alternative could be to apply an inverted-F antenna which also is very compact and provides impedance matching capability.