Abstract:
A water-repellent microphone and an improved method for constructing such a water-repellent microphone provides easy assembly and good acoustic performance. In one embodiment, a water-repellent membrane and a washer are pre-assembled. The surface of the washer opposite the membrane is covered by an adhesive, and the adhesive is covered by a removable liner. The method of assembly comprises removing the liner, and pressing the membrane and washer over the sound port of the microphone. The washer provides spacing between the microphone and the membrane and increases the membrane area through which sound passes, thus providing good acoustic performance. In a second embodiment, the washer is provided as a separate element with adhesives and liners on both sides. A first liner is removed and the washer is attached to the membrane or the microphone, and then the second liner is removed and the assembly is completed.

Description:
[0001]     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/338,990, filed Dic. 10, 2001, which application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to the construction of small water-repellent microphones, and more particularly an improved method for the construction of a small water-resistant microphone, which method reduces the difficulty associated with handling small parts, and provides improved acoustic performance. Such small water-repellent microphone is well suited for use as the microphone of an Implantable Cochlear Stimulation (ICS) system, wherein the microphone is generally worn on the user&#39;s head, and is subject to moisture generally encountered in such use (e.g., perspiration, rain, fog, etc.)  
         [0003]     Cochlear stimulation systems are known in the art. Such systems are used to help the profoundly deaf (those whose middle and/or outer ear is dysfunctional, but whose auditory nerve remains intact) to hear. The sensation of hearing is achieved by directly exciting the auditory nerve with controlled impulses of electrical current, which impulses are generated as a function of transduced acoustic energy. The acoustic energy is picked up by a microphone carried externally (not implanted) by the person using the device and converted to electrical signals. The electrical signals, in turn, are processed and conditioned by a signal receiver and processor, also referred to as a Wearable Processor (WP), in an appropriate manner, e.g., converted to a sequence of pulses of varying width and/or amplitude. The sequence of pulses, or command words that define such sequence of pulses, is carried by an external cable running from the WP to an external headpiece positioned on the side of the user&#39;s head. Generally, a magnet in the headpiece holds the headpiece in place. Such magnet also aligns the headpiece with a corresponding magnet in the implantable parts of the ICS system. Such implantable part receives the command words or pulse sequence, and converts them to appropriate stimulation current pulses that are applied to the auditory nerve through an electrode array implanted in the cochlea, as is known in the art.  
         [0004]     While known ICS systems have succeeded in providing the sensation of hearing to the profoundly deaf, they unfortunately also have the disadvantage of appearing unsightly due to the external cable running from the WP to the headpiece positioned on the side of the user&#39;s head. The WP is typically worn or carried by the user on a belt or in a pocket. While the WP is not too large, it is likewise not extremely small, and hence also represents an inconvenience for the user. The cable which connects the WP with the headpiece is often a source of irritation and self-consciousness for the user.  
         [0005]     The above-described aesthetic considerations, and inconvenience of an external wire, are addressed by U.S. Pat. No. 5,824,022, issued Oct. 20, 1998, for “Cochlear stimulation system employing Behind-The-Ear (BTE) Speech Processor With Remote Control.” The &#39;022 patent teaches a small single external device that performs the functions of both the WP and the headpiece. The external device is positioned behind the ear to minimize its visibility, and requires no cabling to additional components. The &#39;022 patent is incorporated herein by reference.  
         [0006]     While the BTE device taught by the &#39;022 patent resolves the issues of aesthetics and inconvenience, the resulting device, and known BTE hearing aids, disadvantageously include a microphone which is exposed to perspiration and rain, resulting in frequent failures. Therefore, there is a need for a microphone assembly that provides resistance to moisture, while maintaining a good frequency response. Further, due to the small size of known microphones used with BTE devices, the assembly of water-repellent microphone assemblies may be awkward and time consuming. Thus there is a further need for a construction method for small water-repellent microphones.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention addresses the above and other needs by an improved method for constructing a water-repellent microphone providing easy assembly and good acoustic performance. In one embodiment, a water-repellent membrane and a washer are pre-assembled. The surface of the washer opposite the membrane is covered by an adhesive, and the adhesive is covered by a removable liner. The method of assembly comprises removing the liner, and pressing the membrane and washer over the sound port of the microphone. The washer provides spacing between the microphone and the membrane and increases the membrane area through which sound passes. In a second embodiment, the washer is provided as a separate element with adhesives and liners on both sides. A first liner is removed and the washer is attached to the membrane or the microphone, and then the second liner is removed and the assembly is completed.  
         [0008]     In accordance with one aspect of the invention, there is provided a water repellent membrane and washer assembly. The membrane and washer are provided attached to one another. An adhesive and liner reside on the side of the washer opposite the membrane. The water-repellent microphone may then be assembled by removing the liner, and pressing the membrane and washer against the surface of the microphone which includes the sound port. The requirement to apply an adhesive, or to assemble the water-repellent microphone in a fixture is thus eliminated. Further, the requirement to manually manipulate small parts is minimized.  
         [0009]     It is an additional feature of the present invention to provide a separate membrane and washer. The washer includes adhesives and liners on both side. The washer may either be attached to the microphone first, or to the membrane first. As in the first embodiment, there is not need to handle a separate adhesive, or to assemble the water-repellent microphone in a fixture.  
         [0010]     It is a further feature of the invention to provide a water repellent membrane and a washer, wherein the washer resides between the membrane and the soundport of the microphone. The acoustic performance of the water-repellent microphone is limited by the area of the membrane through which sound passes. If the membrane is attached directly to the microphone, the membrane area is limited by the size of the microphone sound port. The addition of a washer between the membrane and the microphone increases the area sound may pass through to the size of the passage through the washer, thus providing good acoustic performance,  
         [0011]     It is an additional feature of the invention to provide a water-repellent seal between the membrane, washer, and microphone. The water-repellent microphone is assembled using an adhesive between the membrane and the washer, and between the washer and the microphone. Such adhesive provides a 360 degree seal to effectively repel the water from entering the microphone.  
         [0012]     It is a another feature of the present invention to provide a method of pre-assembly of a membrane and microphone. In known applications, a microphone sub-assembly is constructed by inserting a membrane, washer, and microphone into a boot (or housing). Great care must be taken during assembly to properly position the members. By pre-assembling the membrane, washer, and microphone, a single member may be inserted into the boot, thus eliminating the need to position the individual members.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:  
         [0014]      FIG. 1  shows a Behind-The-Ear (BTE) device residing upon the ear of a user;  
         [0015]      FIG. 2  shows a partial cross-section of the BTE device;  
         [0016]      FIG. 3  depicts a cross-section of a microphone subassembly suitable for use with the BTE device;  
         [0017]      FIG. 4  shows a water-repellent microphone suitable for use within the microphone subassembly;  
         [0018]      FIG. 5  depicts a cross-sectional view of a second microphone subassembly suitable for use with the BTE device;  
         [0019]      FIG. 6  shows a second water-repellent microphone suitable for use within the second microphone subassembly;  
         [0020]      FIG. 7  depicts a BTE device including an In-The-Ear (ITE) microphone, residing upon the ear of a user;  
         [0021]      FIG. 8  shows additional details of an earhook attachable ITE microphone;  
         [0022]      FIG. 9  shows a plan view of a water-repellent membrane and washer;  
         [0023]      FIG. 9A  shows a cross-sectional view of a first membrane and washer assembly taken along line  9 A- 9 A of  FIG. 9 , wherein a first adhesive resides upon a first side of the washer, and a second adhesive resides upon a second side of the washer, and wherein the washer is water-repellent attached to the membrane by the second adhesive;  
         [0024]      FIG. 9B  depicts the membrane and washer of  FIG. 9A , wherein the membrane and washer are not attached;  
         [0025]      FIG. 9C  shows the membrane and washer assembly of  FIG. 9A  with a first release liner residing upon the first adhesive;  
         [0026]      FIG. 9D  shows the membrane and washer assembly of  FIG. 9B  with the first release liner residing upon the first adhesive and a second release liner resides upon the second adhesive;  
         [0027]      FIG. 10A  shows a cross-sectional view of a second membrane and washer assembly taken along line  9 A- 9 A of  FIG. 9 , wherein the first adhesive resides upon the first side of the first washer, and the second adhesive resides upon the second side of the first washer, and wherein a third adhesive resides upon a third side of the second washer and a fourth adhesive resides upon a fourth side of the second washer, and wherein the first washer is water-repellent attached to the membrane by the second adhesive, and the second washer is water-repellent attached to the membrane by the third adhesive.  
         [0028]      FIG. 10B  depicts the membrane and washers of  FIG. 10A , wherein the membrane and washers are not attached;  
         [0029]      FIG. 10C  shows the membrane and washer assembly of  FIG. 10A , with the addition of the first release liner over the first adhesive, and a fourth release liner over the fourth adhesive; and  
         [0030]      FIG. 10D  shows the membrane and washer on  FIG. 10B , with the first release liner residing upon the first adhesive, the second release liner resides upon the second adhesive, a third release liner resides upon the third adhesive, and the fourth release liner residing upon the fourth adhesive.  
         [0031]     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0032]     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be determined with reference to the claims.  
         [0033]     The water-repellent microphone of the present invention provides a simple and effective method for sealing the a sound port of a microphone against water, thus providing improved performance and reliability. It will be apparent to those skilled in the art that the present invention has application to microphones used for various purposes. While the exercise of the method to Implantable Cochlear Stimulation (ICS) systems will be described in detail in the following description, the exercise of the present invention to other applications is intended to come within the scope of the present invention.  
         [0034]     A Behind-The-Ear (BTE) hearing device  10  is shown carried and resting on an ear  12  of a user in  FIG. 1 . The BTE device  10  may either be a standard hearing aid, or the external electronics for an Implantable Cochlear Stimulation (ICS) system. In either case, a microphone is required to receive acoustic energy (i.e., sound waves) and convert the acoustic energy into an electrical signal for further processing. In order to receive the acoustic energy, the microphone must be open to at least some extent to the environment.  
         [0035]     As can be seen in  FIG. 1 , the BTE device  10  forms an arch that starts behind the ear  12  and reaches over the ear  12 . The BTE device  10  ends near the top of the arch, and an earhook  14  continues the arch a short distance. In typical BTE hearing devices, the microphone resides in the BTE device  10  near the highest point of the arch, behind a microphone port  16 . While the microphone port  16  is advantageously positioned to receive sound in a natural manner (i.e., from the direction the patient is looking), the position also exposes the microphone to various moisture sources. Such moisture sources include rain, splashed water, perspiration, etc. Such moisture may not only degrade a microphone&#39;s performance, but in some instances it may render the hearing device inoperable.  
         [0036]     A cross-section of a portion of a BTE device  10  is shown in  FIG. 2 . A microphone subassembly  20  is positioned directly behind the microphone port  16  (see  FIG. 2 ). A BTE device case  18  includes a water deflector  24  residing above the microphone port  16 . The water deflector  24  advantageously deflects large volumes of water attempting to enter the microphone port  16 . The microphone subassembly has an assembly front  26  which resides against the microphone port  16 , and an assembly rear  28  opposite the assembly front  26 .  
         [0037]     A cross-section of a first microphone subassembly  20   a  is shown in  FIG. 3 . The microphone subassembly  20   a , is comprised of components assembled inside a first boot (or housing)  22   a . The exterior of the boot  22   a  is shaped to cooperate with the BTE device case  18  to retain the microphone subassembly  20   a  in the BTE device case  18 . The interior of the boot  22   a defines a microphone cavity, wherein a water-repellent microphone  30   a  resides. A boot port  32  provides an opening to the water-repellent microphone  3   a . The boot port  32  extends from the assembly front  26  (see  FIG. 2 ) to the microphone cavity. The microphone cavity extends from the cavity front end abutting the boot port  32  to the cavity rear end coinciding with the assembly rear  28 . When the microphone subassembly  20   a  is mounted in the BTE case  18 , the boot port  32  is aligned with the microphone port  16  to provide an acoustic path for acoustic energy outside the BTE device  10  to enter the boot port  32 . A step  31  is defined at a front end of the microphone cavity. The step  31  provides a surface for the water-repellent microphone  30   a  to seat against.  
         [0038]     The water-repellent microphone  30   a  comprises a microphone  34 , first washer  36   a , and water-repellent membrane  38 , as shown in  FIG. 4 . The membrane  38  is water-repellent attached to the washer  36   a , and the washer  36   a  is water-repellent attached to the microphone  34 , wherein the microphone port  40  is surrounded by the washer  36   a . When inserted into the boot  22   a  (see  FIG. 3 ), the membrane  38  resides against the step  31 , thus providing a large membrane  38  surface for effective transmission of sound.  
         [0039]     A cross-section of a second microphone subassembly  20   b  is shown in  FIG. 5 . The second microphone subassembly  20   b  is nearly identical to the first microphone subassembly  20   a , except for the absence of a step, and an additional washer added to water-repellent microphone  30   b . As shown in  FIG. 6 , the second water-repellent microphone  30   b  comprises the microphone  34 , the first washer  36   a , membrane  38 , and additionally, a second washer  36   b . The second washer  36   b  is water-repellent attached to the membrane  38 , the membrane  38  is water-repellent attached to the washer  36   a , and the washer  36   a  is water-repellent attached to the microphone  34 , wherein the microphone port  40  is surrounded by the washer  36   a . As is apparent by comparing  FIGS. 4 and 6 , the additional of the second washer  36   b  to the second water-repellent microphone  30   b  is the only difference between the first water-repellent microphone  30   a , and the second water-repellent microphone  30   b . When the second water-repellent microphone  30   a  is inserted in to the boot  22   b , the second washer  36   b  resides against the front end of the microphone cavity, thus providing a large membrane  38  surface for effective transmission of sound.  
         [0040]     Those skilled in the art will recognize that boots, microphone cavities, and sound ports may be made in a variety of shapes. Such other shapes, or combinations of shapes, are intended to come within the scope of the present invention.  
         [0041]     An example of another type of microphone assembly that may be used with a BTE ICS system is disclosed in applicants&#39; co-pending and co-owned U.S. patent application, Ser. No. 09/733,736, filed Dec. 8, 2000, entitled “Water-Resistant Microphone Subassembly”, which application is incorporated herein by reference.  
         [0042]     As an alternative to a BTE ICS system with a microphone residing in the BTE device, an In-The-Ear (ITE) microphone may be utilized with the BTE device. An ITE microphone earhook  40  and BTE device  10  are shown residing on the ear  12  of a user in  FIG. 7 . The ITE microphone earhook  40  comprises a second earhook  14   b , a third microphone subassembly  20   c , and a stalk  44 . The microphone subassembly  20   c  is attached by the stalk  44  to the earhook  14   b . The microphone subassembly  20   c  preferably resides behind the tragus and directed towards the concha of the ear, with a second boot port  32   a  facing downward and somewhat rearward. Some users may vary location of the microphone subassembly  20   c , and these variations are intended to come within the scope of the present invention.  
         [0043]     A more detailed view of the ITE microphone earhook  40  is shown in  FIG. 8 . The microphone subassembly  20   c  comprises the water-repellent microphone  30   a , a third boot (or housing)  22   c , and defines a sound boot port  32   a . The microphone  30   a  (see  FIG. 4 ) resides inside the boot  22   c . Alternatively, the ITE microphone earhook  40  may also utilize a water-repellent microphone  30   b  as described in  FIG. 6  above. Those skilled in the art will recognize that various other embodiments of an ITE microphone may be exercised. In each variation, similar environmental conditions motivate the use of a water-repellent microphone, and all of these variations utilizing a water-repellent microphone constructed as described herein are intended to come within the scope of the present invention.  
         [0044]     A plan view of a membrane and washer assembly  46  is shown in  FIG. 9 . A cross-sectional view of a first embodiment of the membrane and washer assembly  46  taken along line  9 A- 9 A of  FIG. 9  is shown in  FIG. 9A . A first membrane and washer assembly  46   a  comprises the following elements: the membrane  38 , the first washer  36   a , a first adhesive  50   a  on a first side of the washer  36   a  opposite the membrane  38 , and a second adhesive  50   b  on a second side of the washer  36   a  adjacent to the membrane  38 . The membrane is preferably made from Versapor 10000R . The washer is preferably made from polyester. The adhesive  50   a  is preferably acrylic (3M VHB), whereas the adhesive  50   b  is preferably silicone-based or acrylic (3M VHB). The membrane and washer have about the same outside diameter, preferably between about 0.090 and 0.125 inches. The inside diameter of the washer is preferably between about 0.068 and 0.072 inches, wherein the washer defines a substantially cylindrical passage that passes through the center of the washer. The membrane  38  is preferably between about 0.005 and 0.010 inches thick, and the combined width of the combination of the washer  36   a  and the adhesives  50   a ,  50   b  is preferably between 0.008 and 0.010 inches thick. The water-repellent microphone  30   a  (see  FIG. 4 ) in constructed by pressing the adhesive  50   a  against the end of the microphone  32  which includes the sound port  40  (see  FIG. 6 ), wherein the washer  36   a  is substantially centered on the sound port  40  and encloses the soundport  40 .  
         [0045]     In another embodiment, the membrane and washer  46   b  as shown in  FIG. 9B , are provided as a separate membrane  38  and washer  36   a , wherein the adhesives  50   a  and  50   b  reside on the washer  36   a . The construction of a water-repellent microphone using the membrane and washer  46   b  comprises pressing the adhesive  50   a  against the microphone, and pressing the adhesive  50   b  against the membrane, in any order, thereby constructing the water-repellent microphone  30   a.    
         [0046]     In yet another embodiment, a membrane and washer assembly  46   c  is provided with a release liner  52   a  residing over the adhesive  50   a , as shown in  FIG. 9C . In all aspects other than the addition of the release liner  52   a , the membrane and washer assembly  46   c  is identical to the membrane and washer assembly  46   a . The construction of the water-repellent microphone  30   a  using the membrane and washer assembly  46   c  includes a further step of removing the release liner before pressing the membrane and washer assembly  46   c  against the microphone  32 .  
         [0047]     In another embodiment of the present invention, a membrane and washer  46   d  includes release liner  52   a  over the adhesive  50   a , and release liner  52   b  over adhesive  50   b , as shown in  FIG. 9D . In all aspects other than the addition of the release liners  52   a  and  52   b , the membrane and washer assembly  46   d  is identical to the membrane and washer assembly  46   b . The construction of the water-repellent microphone  30   a  using the membrane and washer assembly  46   d  includes a further step of removing the release liner  52   a  before pressing the membrane and washer assembly  46   c  against the microphone  32 , and removing the release liner  52   b  before pressing the membrane  38  against the adhesive  50   b.    
         [0048]     A cross-sectional view of a membrane and washer assembly  46   e  is shown in  FIG. 1A . The membrane and washer assembly  46   e  includes the first washer  36   a , the membrane  38 , and a second washer  36   b . The washers  36   a  and  36   b  are water-repellent attached to the membrane  38  by the adhesive  50   b  and an adhesive  50   c , respectively. The adhesive  50   a  resides on a first side of the washer  36   a , which first side faces away from the membrane  38 , and a fourth adhesive  50   d  resides on a fourth side of the second washer  36   b , which fourth side faces away from the membrane  38 . The membrane and washer assembly  46   e  may be attached to a microphone  32  by pressing the membrane and washer assembly  46   e  against the microphone  32 ., thus constructing the water-repellent microphone  30   b  (see  FIG. 6 ).  
         [0049]     A membrane and washer  46   f  is shown in  FIG. 10B  comprising the first washer  36   a , the membrane  38 , and a second washer  36   b , wherein the washer  36   a  includes the adhesive  50   a  on the first side, and the adhesive  50   b  on the second side, and the washer  36   b  includes a third adhesive  50   c  on a third side, and the fourth adhesive  50   d  on the fourth side. The water-repellent microphone  30   b  is constructed by pressing the first adhesive  50   a  against the microphone  32 , pressing the membrane  38  against the second adhesive  50   b , and pressing the third adhesive  50   c  against the membrane  38 .  
         [0050]     A membrane and washer assembly  46   g  shown in  FIG. 10C  comprises the membrane and washer assembly  46   e  with the further addition of the first release liner  52   a  over the adhesive  50   a , and a fourth release liner  52   d  over the adhesive  50   d . The water-repellent microphone  30   b  is constructed by removing the release liner  52   a  and pressing the adhesive  50   a  against the microphone  32 .  
         [0051]     An additional membrane and washer  46   h  is shown in  FIG. 10D . The membrane and washer  46   h  comprises the membrane and washer assembly  46   f  with the further addition of the first release liner  52   a  over the adhesive  50   a , the second release liner  52   b  over the adhesive  50   b , a third release liner  52   c  over the adhesive  50   c , and the fourth release liner  52   d  over the adhesive  50   d . The water-repellent microphone  30   b  is constructed by removing the release liner  52   a  and pressing the adhesive  50   a  against the microphone  32 , removing the second release liner  52   b  and pressing the membrane against the adhesive  50   b , and removing the third release liner  52   c  and pressing adhesive  50   c  against the membrane.  
         [0052]     In an alternative embodiment, the washer is attached to the membrane by methods other than adhesives. For example, the washer may be attached to the membrane by thermobonding or by ultrasonic bonding. Those skilled in the art will recognize these, and other boding techniques, which are intended to come within the scope of the present invention.  
         [0053]     Those skilled in the art will recognize variations to the membrane and washers described above. In particular, the order of construction of the water-repellent microphones  30   a  and  30   b  may freely vary from the order the steps were recited in above. Further, the inclusion of a fourth release liner and a fourth adhesive are optional in the embodiments in which they are included.  
         [0054]     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.