Patent Abstract:
A flexible support for a hearing instrument receiver suspended on a receiver tube in a hearing instrument housing will lessen the feedback that could be generated if the housing is jostled. A tether affixed to the receiver and anchored to the housing functions in this manner, and also improves the stability of the receiver inside the housing. Alternatively, a floating arrangement, where the receiver rotatably resides in a cradle may also offer feedback reduction and isolation for the receiver.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application is related to U.S. patent application Ser. No. 09/887,939 filed Jun. 22, 2001, incorporated by reference herein. 
     
    
     
       BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    The receiver of a hearing instrument, the component that generates the sound heard by the instrument&#39;s user, contains an electromechanical transducer similar to a loudspeaker held within an enclosure. If the receiver comes into physical contact with the inside of the hearing instrument or perhaps another component, vibration generated by the action of the receiver may be transferred to the housing and then to the microphone which would be amplified and provided to the input of the receiver, thus resulting in feedback. A resilient and compliant mount for the receiver can help prevent the creation of such a feedback path.  
           [0003]    In one arrangement, the receiver is supported on one side by a semi-rigid receiver tube. A flexible tether having resilient qualities, made from a material such as rubber or an elastomer, supports and anchors the other side of the receiver. Alternatively, studs fashioned from a material such as rubber or an elastomer and projecting outwardly from opposite faces of the receiver and positioned in a cradle on the inside wall of the housing may also be employed. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    [0004]FIG. 1 is a partial cross-sectional view of a hearing instrument housing;  
         [0005]    [0005]FIGS. 2 and 3 are exterior and cross-sectional views, respectively, of a receiver tube;  
         [0006]    [0006]FIGS. 4 and 5 are two orthogonal views of a receiver with a tether;  
         [0007]    [0007]FIGS. 6-8 are orthogonal views of the tether of FIGS. 4 and 5;  
         [0008]    [0008]FIGS. 9 and 10 are drawings of alternative tether sections for the tether of FIGS. 6-8;  
         [0009]    [0009]FIGS. 11-13 are orthogonal views of a tether having two anchor points;  
         [0010]    [0010]FIG. 14 is a cross-sectional view of a receptacle in a hearing instrument housing for a receiver tube;  
         [0011]    [0011]FIG. 15 is a partial cross-sectional view of another arrangement of a hearing instrument housing;  
         [0012]    [0012]FIG. 16 is a flow chart of a procedure for designing a tether and assembling the hearing instrument; and  
         [0013]    [0013]FIGS. 17 and 18 are two orthogonal views of a combined receiver boot with a tether; FIG. 19 illustrates the receiver boot positioned in a hearing instrument shell. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0014]    [0014]FIG. 1 is a partial cross-sectional view of a hearing instrument housing  10  and a receiver assembly  100  (enclosing the receiver mechanism) positioned therein. A flexible receiver tube  200  having some degree of resilience and compliance, also shown in FIGS. 2 and 3, is attached to the receiver assembly  100  to convey sound to the outside of the instrument housing  10 .  
         [0015]    The tube  200  may be fabricated from a synthetic material such as an elastomer or any other suitable material. One such elastomer is marketed by DuPont Dow Elastomers, L.L.C. under the trademark Viton. A receptacle  20  within the instrument housing  10  accepts the receiver tube  200  and, in conjunction with the tube  200 , provides support for the receiver assembly  100 . The flexible receiver tube  200  reduces the vibration that would otherwise be induced in the housing  10  when the transducer mechanism within the receiver assembly  100  operates. Further, should the hearing instrument be dropped, the tube  200  would absorb some of the stress induced by the impact and prevent the receiver assembly  100  from shifting its position within the hearing instrument housing  10 .  
         [0016]    If supported solely by the receiver tube  200 , given sufficient force, the receiver assembly  100  could shift within the housing  10 , making contact with the wall  12  of the housing or perhaps another component within the housing  10 , and providing a path for feedback. To prevent this from happening, the receiver assembly  100  may be secured within the instrument housing  10 .  
         [0017]    In FIG. 1, a tether  300  attached to the receiver assembly  100  functions as an anchor and may also provide support to the receiver assembly  100 . The tether  300  exhibits the properties of resilience and compliance, and may be fabricated from a flexible material such as the previously-mentioned Viton elastomer or another similar material, and may be affixed to the receiver assembly  100  with a glue such as a cyanoacrylate or by some other means. The tether  300  has a ball  310  held in a socket  410  fabricated in the wall  12  of the housing  10  (assuming the necessary degree of thickness) or in an optional platform  420  extending out from the wall  12 , or in some other suitable fixture. To further secure the tether  300 , glue may be applied to the ball  310  to insure that it remains in the socket  410 .  
         [0018]    Alternatively, another shape and securing mechanism could be substituted for the ball  310  and the socket  410 , such as a wedge, a hook, or a ring that mates with a post. Alternatively, a slot provided in the housing  10  could receive the tether  300  and then secured with glue.  
         [0019]    The tether  300  is shown attached to the receiver assembly  100  in the orthogonal view of FIGS. 4 and 5 and then by itself in the orthogonal views of FIGS. 6-8. As can more easily be seen in FIGS. 6 and 7, the ball  310  is at the end of a tether section or member  302  (the region to the left of the dashed line in FIG. 7). The tether section  302  is roughly triangular in shape, narrowing down where it meets the ball  310 . If greater flexibility is desired, the tether section  302  could assume a more rectangular shape by decreasing the width of the tether section  302 , i.e., the length of the dashed line  304 , as illustrated in FIG. 9. Alternatively, the tether section  302  could have a parabolic taper, as shown in FIG. 10.  
         [0020]    Optionally, a strain relief tab  320  may be provided for anchoring the wiring  110  connected to the receiver assembly  100  (see FIG. 4). The wiring  110  is soldered to terminals  120  on the receiver assembly  100  and affixed to the strain relief tab  320  with glue  330  or any other suitable means.  
         [0021]    As can be seen in FIG. 8, the tether  300  may have a lengthwise right-angle cross-section, although other structures such as a U-shaped channel or a flat rectangular shape may be utilized. The angle cross-section aids in the attachment of the tether  300  to the receiver assembly  100  and also provides a surface for the strain relief  320 .  
         [0022]    If the receiver  100  is sufficiently large, a tether having two attachment points may be desired. FIGS. 11-13 illustrate such a configuration.  
         [0023]    To assist with the assembly and registration of the receiver assembly  100  and the receiver tube  200 , a spline  210 , visible in FIGS. 2 and 3, is provided along a portion of the tube  200  and mates with a keyway  22  in the receptacle  20  in the housing  10  (see FIG. 14). The spline  210  assures that the receiver assembly  100  is oriented (radially about the receiver tube  200 ) in the desired position. A flange  220  limits the travel of the tube  200  within the receptacle  20  where it butts up against the inside wall  24  at the entrance to the receptacle  20 .  
         [0024]    In the orientation of the receiver assembly  100  shown in FIG. 1, the primary component of vibration generated by the action of the receiver mechanism would be perpendicular to the page, emanating from the face  130  of the receiver assembly  100 . The receiver tube  200  and the tether  300  minimize the amount of vibration coupled to the housing given such an orientation.  
         [0025]    An alternative support arrangement for the receiver assembly  100  is shown in FIG. 15. There, a cradle  500  has two slots  510  in side plates  520  that accepts an axle-assembly  150  comprising rubber studs  160  projecting outwardly from opposite faces of the receiver assembly  100 . The receiver assembly  100  is held in place in part by tips  530  of the side plates  520  and allowed to rotate about the studs  150 .  
         [0026]    A procedure for positioning the components within an instrument housing  10  and creating the tether  300  is shown in the flow chart of FIG. 16. Initially, a three-dimensional description of the largest volume that the hearing instrument housing  10  could occupy is required, based on the geometry of the user&#39;s ear canal and adjoining ear structure if the hearing instrument extends to the outer ear.  
         [0027]    The components of the instrument are then determined and three-dimensional models or representations of those components are pre-positioned within the housing volume determined above. The representations are positioned in a manner that minimizes the internal volume of the housing  10  required to house the items. A test for collision detection is then performed to insure that the placement of any given component does not interfere with another component, and any necessary adjustments are performed. This is an iterative process, performed until a satisfactory configuration is achieved. In turn, the outer dimensions of the housing  10  are determined, i.e., the minimum size required to house the pre-positioned components. Since the cross-section at any given point in the ear canal is fixed, the size of the housing  10  can be adjusted by varying its length.  
         [0028]    The tip  30  of the hearing instrument housing  10  is then filled creating a filled-in volume or tip fill  32  to provide the surrounding structure for the receiver tube receptacle  20  and a surface  24  for the receiver tube flange  220  (see FIGS. 1 and 14). The depth of the tip fill  30  may be set to allow for the desired length of the receiver tube  200  between the flange  220  and the receiver assembly  100 . This length is selected based in part on the flexibility of the receiver tube  200  and the desired stiffness and resilience.  
         [0029]    Since the position of the receiver assembly  100  within the housing  10  is now known, the dimensions of the tether  300  can be determined. If the configuration of FIG. 1 is used, the optional platform  420  is located on the wall  12  and the socket  410  is positioned therein. Alternatively, the socket  410  may be located in the wall  12  given a sufficiently thick outer wall  12 .  
         [0030]    The information resulting from the foregoing process may be provided to the fabrication process, be it manual or automated. For example, the housing  10  may be fabricated using the rapid prototyping process described in U.S. patent application Ser. No. 09/887,939.  
         [0031]    To assemble the hearing instrument, the receiver assembly  100  is inserted into the housing  10 , and the receiver tube  200  is inserted into the receptacle  20 . The spline  210  on the tube  200  is oriented according to the keyway  22 , until the flange  220  on the tube  200  butts up against the inside wall  24  at the entrance of the receptacle  20 . The tether  300  or the axle assembly  150 , on the receiver assembly  100 , is then anchored on the housing  10 , either at the socket  410  or the cradle  500 , respectively. In either case, the receiver tube  200  is bent slightly, creating a degree of spring tension that helps to stabilize the receiver assembly  100  in the housing  10 . Where the tether  300  is employed, the bending also results in spring tension therein. To achieve the tension in the receiver tube  200 , the length of the tube  200  may be selected such that section from the flange  220  to the receiver assembly  100  forms an arc when the receiver assembly is anchored by either the tether  300  and ball  310  or the axle assembly  150  in the cradle  500 .  
         [0032]    The dimensions of the receiver tube  200 , and the location of the flange  220  thereon, and of the tether  300  and its components depend in part on the dimensions of the particular hearing instrument and the receiver assembly  100  employed. The dimensions can be determined empirically or using finite element analysis. In various prototypes, a receiver tube  200  having an outside diameter of 2.4 mm and an inside diameter of 1.4 mm, where the flange  220  is located a distance approximately 5.0 mm from the receiver assembly  100  has been found to work satisfactorily. That distance may vary from approximately 0.5-6.0 mm. Similarly, a tether  300  having a thickness of 0.4-0.5 mm, a width varying from 1 mm to 6 mm at the widest to 1 mm at the ball  310  (see FIG. 7), and a length of 2.0 mm (in a range of 0.5-5.0 mm, depending on the desired degree of resilience and stiffness), and having a ball  310  having a diameter of 1.0-1.5 mm has also been found to work satisfactorily.  
         [0033]    In certain applications, such as smaller hearing instruments where the entire device resides in the ear canal, the receiver assembly is considerably smaller and may be enclosed in a receiver boot fabricated from a material such as the Viton elastomer. One such an arrangement is shown in FIGS. 17-19. As shown in the figures, an outer receiver boot  600  holds the receiver assembly  100 ; the receiver tube  610  may be an integral part of the boot or it may be a separate component. The receiver assembly  100  is inserted into an opening  602  in the boot  600  and oriented such that its output port (not shown) is positioned adjacent the receiver tube  610 . In the case where the receiver tube  610  is a separate component, a protrusion or spout may be provided on the receiver assembly  100  (not shown) to attach and support the receiver tube  610 . The receiver tube  610  also has a spline  612  to aid in orientation of the receiver assembly  100  during assembly.  
         [0034]    The boot  600  also has a tether  620  and ball  620 . The tether  620  may have a length of 1-3 mm and thickness of 0.5 mm; the ball  630  may have a diameter of 1 mm. The receiver tube portion  610  may have a length of 1-5 mm, a diameter of 2 mm, and wall thickness of 0.4 mm. As shown in FIG. 19, a drawing of a hearing instrument employing a receiver boot  600 , the ball  630  resides in a socket  640  in the wall  650  of the hearing instrument.

Technology Classification (CPC): 7