WO2002045461A2

WO2002045461A2 - Surface mountable telecoil as for use in a hearing aid

Info

Publication number: WO2002045461A2
Application number: PCT/US2001/044260
Authority: WO
Inventors: Paris N. Tsangaris; Thomas D. Schulz
Original assignee: Knowles Electronics, Llc
Priority date: 2000-11-28
Filing date: 2001-11-27
Publication date: 2002-06-06
Also published as: WO2002045461A3; WO2002045461A9; AU2002219871A1

Abstract

A method of assembling a plurality of finished telecoil packages for use in a plurality of hearing aids is claimed. The method comprises the steps of first providing a plurality of telecoils having first and second leads. A substrate is also provided. The telecoils are arranged on the upper surface of the substrate in an array and affixed to the substrate with an epoxy. The epoxy is cured, and the first and second leads are soldered to a plurality of corresponding terminal pads located on the upper surface of the substrate. The entire substrate is secured to a fixture, and the upper surface of the substrate and the plurality of telecoils is coated with an encapsulating substance. The substrate is removed from the fixture and severed along a plurality of predetermined paths to separate the telecoil array into a plurality of single telecoil packages.

Description

SURFACE MOUNTABLE TELECOIL AS FOR USE IN A HEARING AID

DESCRIPTION

Technical Field

The present invention relates generally to hearing aids, and, more particularly, to a telecoil package mountable on a substrate surface as for use in a hearing aid. Background of the Invention

Hearing aids normally pick up sound through a microphone, convert the sound to a signal, amplify the signal via a low power audio amplifier, and transmit the signal to a user's ear via a receiver.

Ambient acoustic noise can adversely affect the hearing aid's performance. Ambient acoustic noise can reduce the signal-to-noise ratio; and when the desired sound signal is weak (as in the case of a telephone speaker), the ambient noise may actually override and mask the signal which renders the desired signal non-detectable.

To combat this effect, modern hearing aids, worn in the ear or behind the ear, can be equipped with "telecoils." A telecoil is generally a coil of wire wound around a soft magnet core and encased within the hearing aid. The telecoils are generally inserted into a telecoil package, and the entire telecoil package is connected to the hearing aid audio amplifier and to the output acoustic transducer.

Hearing aids comprising telecoils are useful for listening to the telephone since the telephone's receiver produces a very weak sound. The telecoil does not pick up acoustic ambient noise and thus allows a much better signal-to- noise ratio than a conventional microphone. The telecoil picks up sounds via magnetic induction, typically from a telephone's receiver or from a dynamic speaker having a magnetic core. Telecoils may also be used to pick up magnetic induction transmitted by an induction loop, typically installed around walls in conference rooms, theaters, classrooms, churches, and the like. Generally, a hearing aid equipped with a telecoil can be switched from "M" (microphone) to "T" (telecoil). ^"When on M, the standard microphone signal is amplified and heard by the wearer. When on T₃ the signal induced into the telecoil is amplified and heard by the wearer. The sensitivity of these telecoils is typically not more than 3-4 mV/A/m. The typical telecoil output electrical signal induced by telephone receivers is about 50-100 μV. This signal is best detected when the axis of the telecoil's magnetic core is parallel to the magnetic field's direction, and the telecoil is positioned as close as possible to the telephone receiver. In use, the signal from the telecoil is amplified by the hearing aid amplifier and routed to the hearing aid receiver for conversion into sound. In the case of a telephone, a coil in the telephone receiver acts like the primary of a transformer and the telecoil acts like the secondary and thereby obtains the telephone signal.

Presently, surface mount telecoil packages are individually manufactured for use in hearing aids. The small telecoil is inserted into a cylindrical sleeve of insulating material. Terminal pads are affixed to ends of the telecoil, and tin plated copper lugs or terminal brackets enclose the telecoil within the sleeve. Epoxy or some other substance seals the telecoil within the sleeve. The finished telecoil package is then inserted into a conventional hearing aid. This method of manufacturing has several drawbacks. First, the seals provided by the lugs are unreliable, and the telecoils are susceptible to corrosion. Additionally, the terminal connections can be unreliable because the telecoils are soldered to the pads and again at the lugs. Also, when the telecoil package is inserted into the hearing aid, there is a chance that an electrical short can occur between the telecoil package and another hearing aid component because the lugs are exposed.

Summary of the Invention

The present invention is directed to an improved telecoil package for insertion into a conventional hearing aid and a method for producing the same. The telecoil package of the present invention comprises a conventional telecoil affixed to a substrate with an epoxy, and covered with a potting material.

The telecoil includes a pair of lead wires which are electrically connected to the substrate.

Multiple telecoil packages may be produced simultaneously by populating the substrate with telecoils in an array format. The telecoils can be electrically connected to the substrate. The potting material is then provided to encapsulate the substrate and the telecoils. Once the potting material is cured, the substrate can be sawed along predetermined paths to create a plurality of individual telecoil packages which are ready for insertion into electrical devices.

Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.

Brief Description of the Drawings

Figure 1 is a perspective view of a telecoil package of the present invention;

Figure 2 is a top view of the substrate used to manufacture the telecoil package of Figure 1 ;

Figure 2a is a bottom view of the substrate of Figure 2; Figure 3 is a cross-sectional view of the telecoil package of Figure 1; Figure 4 is a top view of a substrate populated with multiple telecoils used to produce multiple telecoil packages; Figure 4a is a bottom view of the substrate of Figure 4;

Figure 5 is a flowchart of a method of the present invention. Detailed Description of the Preferred Embodiment

While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

The present invention is directed to an improved telecoil package as for use in a hearing aid. Accordingly, Figure 1 is an illustration of an individual finished telecoil package 10 of the present invention. The finished telecoil package 10 includes a substrate 14 covered with a potting material 16.

Now referring to Figures 2 and 2a, the substrate 14 is generally planar and includes an upper surface 20 and a lower surface 24. The substrate 14 has a pair of parallel aligned through-holes 28 which are coated or plated with a conducting material 32. The through-holes 28 make an electrical connection between the upper surface 20 and the lower surface 24 of the substrate 14..

On the upper surface 20 of the substrate 14, the conducting material 32 is connected to a first pair of terminal pads 36. The conducting material 32 extends from the terminal pads 36 to the though-holes 28. The conducting material 32 then extends downwardly through the though-holes 28 to the lower surface 24 of the substrate 14. On the lower surface 24, the conducting material 32 extends to a second pair of terminal pads 40. The second pair of terminal connectors 40 are provided for electrical connection to a hearing aid. Referring to Figure 3, the first pair of terminal pads 36 located on the upper surface 20 of the substrate 14 are provided for electrical connection to a conventional telecoil 44. The telecoil 44 generally includes a wire coil 48 wound about a soft magnet core 52. A pair of leads 56a, 56b extend from the telecoil 44 and are electrically connected to the first pair of terminal pads 36 located on the upper surface 20 of the substrate 14.

The first pair of terminal pads 36 are generally positioned near one end of the telecoil 44. This arrangement allows for efficient soldering of the leads 56a, 56b to the first pair of terminal pads 36, typically with a 95% tin and 5% silver solder. The telecoil 44 is fixedly connected to the upper surface 20 of the substrate 14 with an adhesive 60 such as an epoxy. The adhesive 60 is applied to the upper surface 20 of the substrate 14. The telecoil 44 is then placed on the substrate 14, and the adhesive 60 is cured so that telecoil 44 is reliably secured to the substrate 14.

Next, referring to Figure 4, the substrate 14 is placed within a fixture 64 and encapsulated with a potting material 16, such as an epoxy-based or silicon- based material. The potting material 16 coats upper surface 20 of the substrate 14 to completely encapsulate the first pair of terminal pads 36, the telecoils 44, and every other portion of the upper surface 20. The potting material 16 is cured until it hardens to provide an air-tight cover. A reference insignia 68, as shown in Figure 1, may be impregnated or printed on the potting material 16 to provide a guide for the orientation of the telecoil package 10 for use when the telecoil package 10 is placed within and connected to a conventional hearing aid. Figure 4 shows multiple telecoils 44 arranged in an array on the upper surface 20 of the substrate 14. This arrangement allows multiple individual telecoil packages 10 to be manufactured simultaneously. After the encapsulating material 16 is applied and cured "the substrate 14 is removed from the fixture 64, and each individual telecoil package 10 is DC resistance tested for reliability. Each telecoil 44 is compared to a predetermined value. After testing, any failing telecoil package 10 can be identified either electronically or with a physical marking.

Next, the substrate 14 is mounted to a tape and ring. The ring is generally an eight inch metal ring with tape stretched across it. The substrate adheres to the tape. The individual telecoil packages 10 are then formed by sawing the substrate

14 along predetermined paths between the telecoils 44. The individual telecoil packages 10 are removed from the tape, and the units that failed the testing are discarded. The telecoil packages 10 that passed the testing are placed in a shipping package for transportation to the customer. The method of producing the telecoil package 10 disclosed herein, and depicted in the Figure 5 as a flowchart, has many advantages over the prior methods of producing telecoil packages. For instance, the method and telecoil package disclosed herein is advantageous because the present method allows multiple telecoil packages to be produced simultaneously rather than individually.

Also, since the present telecoil package includes an air-tight cover with no so seals or seams, the chance of the telecoil corrosion is reduced.

Moreover, the method of the present invention produces a more reliable telecoil package. The terminal connections of the prior art telecoil packages can be unreliable because the telecoils are soldered to the pads and again at the lugs. The telecoil package of the present invention avoids this by soldering the leads directly to the terminal pads.

Finally, when the telecoil package of the present invention is inserted into the hearing aid, there is reduced chance that an electrical short can occur between the telecoil package and another hearing aid component. This is true because the components of the telecoil package disclosed herein are completely covered with the encapsulating material. This method can also be used to produce coils of various aspect ratios and heights with minimal tooling through changes to the substrate only While the specific embodiment has been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying Claims.

Claims

CLAIMSWhat is claimed is:

1. A method of producing a telecoil package, the method comprising the steps of: providing a telecoil having a pair of leads for electrically interconnecting the telecoil to an electrical device; providing a substrate; and affixing the telecoil to the substrate.

2. The method of claim 1 wherein the substrate includes an upper surface having a first pair of terminal pads for connection to the leads of the telecoil.

3. The method of claim 2 wherein the substrate includes a lower surface having a second pair of terminal pads for electrical connection to the electrical device, the first pair terminal pads being connected to the second pair of terminal pads by a conductive material.

4. The method of claim 3 wherein the substrate includes a pair of through- holes and the conductive material extends from the upper surface to the lower surface via the through-holes.

5. The method of claim 1 further comprising the steps of: providing an epoxy to fixedly secure the telecoil to an upper surface of the substrate; and curing the epoxy.

6. The method of claim 1 further comprising the steps of: providing a potting material to an upper surface of the substrate; curing the potting material.

7. The method of claim 6 wherein the potting material encapsulates the upper surface of the substrate and the telecoil.

8. The method of claim 6 further comprising the step of imparting an

5 orienting indicator onto the cured encapsulating material for providing a reference when the finished telecoil package is inserted into a hearing aid.

9. A method of producing a plurality of telecoil packages, the method comprising the steps of: o providing a plurality of telecoils each having a pair of leads for electrically interconnecting the telecoils to an electrical device; providing a substrate; arranging the plurality of telecoils in an array on an upper surface of the substrate; 5 affixing each telecoil to the substrate; and severing the substrate along predetermined paths.

10. The method of claim 9 further comprising the steps of: providing a potting material to at least a portion of the upper surface of the 0 substrate; curing the potting material.

11. The method of claim 10 wherein the potting material encapsulates the upper surface of the substrate and the telecoil. 5

12. The method of claim 11 further comprising the step of imparting an orienting indicator onto the cured potting material for providing a reference when the finished telecoil package is inserted into the hearing-aid.

30

13. The method of claim 9 wherein the substrate includes a plurality of first pairs of terminal pads on an upper surface for connection to the leads of the plurality of telecoils.

14. The method of claim 13 wherein the substrate includes a plurality of second pairs of terminal pads on a lower surface of the substrate for electrical connection to the electrical device, each first pair of terminal pads being connected to a respective second pair of terminal pads by a conductive material.

15. The method of claim 14 wherein the substrate includes a plurality through- hole pairs wherein the conductive material extends from the upper surface to the lower surface via the through-hole pairs in the substrate.

16. The method of claim 9 further comprising the steps of: providing an epoxy to fixedly secure the plurality of telecoils to an upper surface of the substrate; and curing the epoxy.

17. A method of assembling a plurality of finished telecoil packages, the method comprising the steps of: providing a plurality of telecoils having first and second leads; providing a substrate having an upper surface including a plurality of lead terminal pads for electrical connection to the first and second leads of the plurality of telecoils and a lower surface including a plurality of connecting terminal pads for connecting the finished telecoil package to the electrical device, the substrate further including a plurality of plated through-holes electrically connecting the lead terminal pads of the upper surface to the connecting terminal pads of the bottom surface; arranging the plurality of telecoils on the upper surface of the substrate in an array; affixing the plurality of telecoils to the substrate with an epoxy; curing the epoxy; soldering the first and second leads of each telecoil to a plurality of corresponding terminal pads located on the upper surface of the substrate; securing the substrate to a fixture; encapsulating the upper surface of the substrate and the plurality of telecoils with a potting substance; curing the potting substance; impregnating an exposed upper surface of the cured potting substance with a plurality of directional indicators, each directional indicator being substantially aligned with an individual telecoil; removing the substrate from the fixture; testing each telecoil in the telecoil array and identifying any individual telecoils that do not reach a predetermined value; securing the substrate to a tape and ring unit; and severing the substrate along a plurality of predetermined paths in order to separate the telecoil array into a plurality of single telecoil packages.

18. The method of claim 17 wherein a 95% tin and 5% silver solder is used to solder the leads to the lead terminal pads.

19. A telecoil package for insertion into an electrical device, the telecoil package comprising: a telecoil having a pair of leads, the telecoil fixedly connected to a substrate which has a pair of lead terminal pads on an upper surface, the telecoil leads being electrically connected to the terminal pads.

20. The telecoil package of claim 19 wherein the telecoil is coated with a potting material.

21. The telecoil package of claim 20 wherein an orientation indicator is imprinted on the potting material.

22. The telecoil package of claim 21 further comprising a pair of connector terminal pads on a lower surface of the substrate for electrical connection to the lead terminal pads on the upper surface of the substrate.

23. The telecoil package of claim 22 wherein a conductive material electrically connects the lead terminal pads to the connector terminal pads.

24. The telecoil package of claim 23 wherein the substrate includes a pair of through-holes wherein the conductive material passes from the upper surface of the substrate to the lower surface of the substrate via the through-holes.

25. A telecoil package for insertion into an electrical device, the telecoil package comprising: a telecoil having a pair of leads; a substrate having an upper surface and a lower surface, the upper surface having a pair of lead terminal pads wherein the telecoil leads are electrically connected to the lead terminal pads, the lower surface having a pair of connector terminal pads which are electrically connected to the lead terminal pads; and a potting material encapsulating the upper surface of the substrate.