Hearing Aid with Antenna for Reception and Transmission of Electromagnetic Signals

Abstract

The invention regards a communication device which is adapted for placement in a users ear. The communication device comprises a shell part enclosing an input transducer for receiving an input signal, a signal processing device and an output transducer for providing a signal perceivable as sound, a battery located at a surface part of the shell which is facing away from the head of the user, a transmission and reception circuit for transmission and/or reception of electromagnetic energy. According to the invention an antenna for radiating and/or receiving electromagnetic energy is provided such that it has a first surface turned towards the surroundings and a second surface located in close proximity of the battery.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a schematic representation of an ITE hearing aid with an antenna according to the invention,

FIG. 2 is a schematic representation of an antenna according to the invention,

FIG. 3 is a schematic representation of an antenna according to the invention,

FIG. 4 is a schematic representation of an antenna according to the invention,

FIG. 5 is a schematic representation of an antenna in side sectional view,

FIG. 6 is a schematic representation of an antenna in side sectional view.

DESCRIPTION OF A PREFERRED EMBODIMENT

Initially it is worth noting that we are dealing with small antennas, meaning that the wavelength is much larger than the physical size of the antenna and therefore the antenna has a narrow bandwidth (high quality factors) and low efficiency (small radiation resistance compared to the loss resistance). If high currents are dominating, the structure will mainly radiate the magnetic field and vice versa: if high voltages are present, a dominating electric field must be expected.

In FIG. 1 a schematic sectional representation of a CIC hearing aid is shown with an antenna according to the invention. The hearing aid comprises a custom made shell part 2 which is placed deep in the ear canal. Instead of being custom made the shell part can be either flexible or have a flexible outer portion which allows it to be inserted into the ear. 1 is an outline of the external ear of a person. The shell part 2 encloses a receiver 5, a signal processing unit 4 and a microphone 3. The receiver 5 is arranged with an output orifice (not shown) close to the tympanic membrane 6 in order to deliver a useful audio signal to the user. A front plate part 12 is arranged to face the surroundings. In this part a battery drawer 7 with a battery 8 is placed. Also an extractor 9 may be comprised in the front plate. Other components may be placed in the shell or associated with the front plate part 12, such as further microphones or connectors for wired contact with other equipment like telephones. Also the hearing aid will comprise a transmission and/or reception circuit in order to feed/receive electromagnetic energy to/from the antenna. This circuit is connected to the antenna and to the signal processing part 4. The transmission and/or reception circuit is not shown in the figures, and it may be configured as an independent circuit part or it can be configured as part of the signal processing part 4.

An antenna 10 is schematically shown. The antenna 10 is placed in the area between the battery and the external surface of the frontal plate. The antenna i0 is preferably associated the battery drawer 7.

FIG. 2 displays a loop antenna 13. The inductive part of the antenna impedance has to be resonated with an external capacitor (not shown). The magnetic field generated by the loop current is the radiating component and dominating in the near field, especially if it is exited by a balanced signal. If operated in unbalanced mode it will also radiate the electric field. The antenna is less sensitive to detuning from near by objects. The loop has two connections 16 and 11 and can be placed circumferentially with regards to the battery 8.

In FIG. 3 a schematic representation of a loop+helix antenna is shown. This antenna structure is unbalanced and can be made resonant by itself or in combination with an external capacitor. The antenna impedance is adjustable by tapping. Both the H and E fields are radiated from the structure and due to the high end impedance of the helix and compared to the loop antenna, increased sensitivity towards detuning by near by objects must be expected. Two connection points 14 and 15 are shown. A loop of two turns and a helix part of two turns is showed but a higher or lower number of turns may be used.

FIG. 4 discloses a patch antenna 17. Because of the small size of the patch 17 compared to the wavelength the patch 17 can be considered as a capacitor that will require an inductor to be made resonant. The duality between the small loop and the patch is evident. The patch will radiate the electric field from the edges but the tuning inductor will inevitably also add to the radiation pattern with a magnetic contribution. If the patch has a nearby ground plane, only moderate sensitivity to detuning from close by objects will occur.

In FIG. 5 an enlarged side sectional view of an embodiment of the invention is schematically shown. The antenna 10 could be either a loop or a patch antenna and in the shown embodiment it is embedded within the material of the battery lid 2. In this way the antenna 10 will lie close to the battery 8, which thereby may function as ground plane and at the same time shield the antenna 10 from receiving radiation from the possible electromagnetic noise from the speaker or other electronic objects in the hearing aid.

In FIG. 6, an other embodiment of the invention is schematically shown in sectional view. Here the antenna 10 has an extension, which is wider than the projection of the battery 8 on the battery lid 7. The shielding effect of the battery 10 and also the usefulness of the battery as ground plane are not impaired by this, and at the same time an antenna covering a larger area is achieved, whereby further the antenna becomes more effective.

Claims

1. Communication device which is adapted for placement in a users ear and comprises a shell part enclosing an input transducer for receiving an input signal, a signal processing device and an output transducer for providing a signal perceivable as sound, a battery located at a surface part of the shell which is facing away from the head of the user, a transmission and reception circuit for transmission and/or reception of electromagnetic energy, and whereby an antenna for radiating and/or receiving electromagnetic energy is provided such that it has a first surface turned towards the surroundings and a second surface located in close proximity of the battery.

2. Communication device as claimed in claim 1, wherein the antenna is tuned to radiate and/or receive electromagnetic energy in the frequency range of 50 MHz to 50 GHz.

3. Communication device as claimed in claim 1, wherein the antenna is shaped as a part of a flexprint.

4. Communication device as claimed in claim 1, wherein the antenna is embedded in material externally of the battery.

5. Communication device as claimed in claim 4, wherein the antenna is a metal part.

6. Communication device as claimed in claim 1, wherein the antenna is manufactured by deposition of metal material on surface parts of the faceplate and/or battery drawer.

7. Communication device as claimed in claim 1, wherein the antenna covers a surface area of the shell which is wider than the projection of the battery onto the faceplate surface.

8. Communication device as claimed in claim 1, wherein the antenna comprises a loop, which is usable also as a charging loop for a battery.