Magnetic shielding for communication device applications

Description

CLAIM OF PRIORITY

The present application claims the benefit under 35 U.S.C. 119(e) of U.S. Provisional Patent Application Ser. No. 61/142,083, filed Dec. 31, 2008, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This application relates to communication devices and more particularly to magnetic shielding for communication device applications

BACKGROUND

Communication devices often involve compact designs having densely populated components. These components can suffer in performance due to electromagnetic interference during operation. One example of such a communication device is a hearing aid. Hearing aids typically include a device called a “receiver” which plays sound processed by electronics in the hearing aid. The receiver is often close to other components so that magnetic shielding is required. One existing method for shielding a receiver is to draw and anneal mu-metal in the form of a “can” in which the receiver is placed to minimize magnetic interference. However, this approach requires metal working to draw the mu-metal and a separate annealing process to provide alignment of magnetic grain boundaries of the mu-metal. There is a need in the art for an improved magnetic shielding that is easy to use with communication devices and provides a high quality magnetic shielding.

SUMMARY

A communication device comprising a coated surface having a fine grained coating, the coating including a high nickel content to provide magnetic shielding.

This Summary is an overview of some of the teachings of the present application and is not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details about the present subject matter are found in the detailed description and the appended claims. The scope of the present invention is defined by the appended claims and their equivalents.

DETAILED DESCRIPTION

The following detailed description of the present invention refers to subject matter in the accompanying drawings which show, by way of illustration, specific aspects and embodiments in which the present subject matter may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present subject matter. References to “an”, “one”, or “various” embodiments in this disclosure are not necessarily to the same embodiment, and such references contemplate more than one embodiment. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope is defined only by the appended claims, along with the full scope of legal equivalents to which such claims are entitled.

The present subject matter relates to a fine grained coating, including, but not limited to, the nanometer scale grain structures obtained using the processes set forth in U.S. Pat. Nos. 7,320,832 and 7,354,354, which are incorporated by reference herein in their entirety. The inventors proposed using a high nickel content mu-metal formulation for production of the fine grained coatings to provide low-frequency shielding. Mu-metal is a nickel-iron alloy that has very high magnetic permeability. The high permeability makes mu-metal very effective at screening static or low-frequency magnetic fields. Typically, mu-metal objects require heat treatment after they are in final form. One type of heat treatment is annealing. Annealing increases the magnetic permeability about 40 times. However, one advantage of the present process of using a mu-metal formulation with the fine grained coatings is that the resulting object does not require annealing. Another advantage of the present process is that the coatings can be made on plastic or other surfaces. Yet another advantage is that the hardness of the coatings adds to the rigidity of the resulting coated object. Another advantage is that the fine grain structure of the present subject matter can provide grain structures that are substantially smaller than annealed mu-metal. In one embodiment, the grain structure was about 1000 times smaller and tighter than a mu-metal counterpart. Another advantage is that the coated components provided by the present process can be about 6/10ths of the thickness of their mu-metal counterparts and still achieve the same amount of magnetic shielding, so overall coating thicknesses are less.

In one embodiment, an alloy with a high nickel content is formed using the processes described in the references incorporated by reference herein. In one embodiment, an alloy comprising about 75% nickel, about 15% iron, copper and molybdenum alloy is provided. Other concentrations are possible without departing from the scope of the present subject matter.

The present coating process can be applied to a variety of components and surfaces to provide magnetic shielding in a communications device. Such devices, include, but are not limited to cell phones, hearing aids, and other hearing assistance devices.

In hearing aid applications, the plastic of the hearing aid can be coated with the present shielding. It can supplement or entirely replace the current magnetic shielding used with the receiver or speaker of the hearing aid. In various applications the plastic components generated using stereolithography can be coated.

The present subject matter includes hearing assistance devices, including but not limited to, cochlear implant type hearing devices, hearing aids, such as in-the-ear (ITE), in-the-canal (ITC), completely-in-the-canal (CIC), behind-the-ear (BTE), and receiver-in-the-canal (RIC) type hearing aids. It is understood that behind-the-ear type hearing aids may include devices that reside substantially behind the ear or over the ear. Such devices may include hearing aids with receivers associated with the electronics portion of the behind-the-ear device, or hearing aids of the type having receivers in the ear canal of the user. It is understood that other hearing assistance devices not expressly stated herein may fall within the scope of the present subject matter.

This application is intended to cover adaptations or variations of the present subject matter. It is to be understood that the above description is intended to be illustrative, and not restrictive. The scope of the present subject matter should be determined with reference to the appended claims, along with the full scope of legal equivalents to which such claims are entitled.