Abstract:
A microphone assembly comprises a housing having a top housing and a bottom housing fixed attached together, defining a volume. The microphone assembly further comprises a motor assembly and a circuit assembly disposed within the housing. The motor assembly includes a backplate and a diaphragm. The motor assembly further comprises a first end and a second end spaced apart by a central portion wherein a portion of the first and second ends fixedly attached to the inner surface of the top housing or the bottom housing. The circuit assembly includes a connecting lead for making contact with the diaphragm or a backplate. The circuit assembly is arranged in series with the motor assembly, but not stacked over or under the motor assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent claims benefit under 35 U.S.C. § 119 (e) to United States Provisional Application No. 60/744,229, filed Apr. 4, 2006 and entitled Monitor Transducer System and Manufacturing Method Thereof, the disclosure of which is hereby incorporated herein for all purposes. 
     
    
     BACKGROUND 
       [0002]    Transducers such as microphones, receivers and speakers are useful in many listening devices such as hearing aids, earphones, in-ear monitors, headphones, Bluetooth wireless headsets, or the like. For instance, a listening device, such as an in-ear monitor that completely fills the outer portion of the ear canal, includes a bulky input converter, i.e. a microphone, an amplification portion, and a receiver. An input signal is received by the input converter and converted to an electrical input signal. Such signals are fed to the amplification portion for further processing and amplification before transmission to the receiver. The receiver being configured to receive the processed signals converts the signals into acoustic signals for transmission to the wearer. 
         [0003]    One typical microphone uses an electret portion (a diaphragm and a backplate) and an electronic processing system that are contained within a housing. The overall height of the microphone, i.e., the height of the housing is defined by the configuration of the electret portion and the electronic processing system. Based on the usual manner of assembly of the microphone, the electret portion is placed either over or under the electronic processing system. Conventionally, the casing for the working components is rectangular in shape. When the microphone engages the inner wall of the ear canal, it causes considerable discomfort when worn by the user, due to the shape of the case. 
         [0004]    For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a significant need in the art for an improved transducer monitor system to overcome these problems. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings wherein: 
           [0006]      FIG. 1  is a block diagram of a listening device according to various embodiments of the present invention; 
           [0007]      FIG. 2  is a perspective view of a transducer monitor system, in accordance with various embodiments of the present invention; 
           [0008]      FIG. 3  is a perspective view of the transducer monitor system and a tubing assembly, in accordance with various embodiments of the present invention; 
           [0009]      FIG. 4  is an exploded view of a thin microphone unit in accordance with various embodiments of the present invention; 
           [0010]      FIG. 5  is a cross-sectional view of the thin microphone unit of  FIG. 4 ; and 
           [0011]      FIG. 6  is a cross-sectional view of another embodiment of a thin microphone unit, in accordance with various embodiments of the present invention. 
       
    
    
       [0012]    Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. 
       DETAILED DESCRIPTION 
       [0013]    While the present disclosure is susceptible to various modifications and alternative forms, certain embodiments are shown by way of example in the drawings and these embodiments will be described in detail herein. It will be understood, however, that this disclosure is not intended to limit the invention to the particular forms described, but to the contrary, the invention is intended to cover all modifications, alternatives, and equivalents failing within the spirit and scope of the invention defined by the appended claims. 
         [0014]      FIG. 1  is a block diagram of a listening device  4 , such as hearing aids, in-ear monitors, electronic hearing protection devices, Bluetooth wireless headsets, earphones, and the like. The listening device  4  may also be virtually any type of audio and listening device. The listening device  4  includes an outside microphone  6 , a processing circuit system  8 , and a transducer monitor system  10 . The outside microphone  6  receives acoustic energy from an acoustic environment external to the wearer of the listening device and converts the sound into corresponding electrical signals that are, in turn, provided to the processing circuit system  8 . While  FIG. 1  shows one microphone, microphone  6  may include one or more microphone transducers without departing the scope of the invention. 
         [0015]    The transducer monitor system  10  includes an inside microphone  12  and a receiver  14 . A sound pressure level (SPL), i.e. occlusion effect, within the ear canal entering the inside microphone  12  is converted to an electrical signal that is, in turn, transmitted to the processing circuit system  8 . The processing circuit system  8 , such as a digital processing system, a sound measurement system, a filter system, a control signal system, a converter, a sound pressure level adjusting system, or combination thereof, receives the signals from the outside and inside microphones  6 ,  12  and then processes the signals before transmission to the receiver  14 . The receiver  14  converts the processed signals provided b the processing circuit system  8  to a sound signal for transmission to the user. While  FIG. 1  shows one receiver, the receiver  14  may include one or more receiver transducers each of which are coupled to the microphone  12  without departing the scope of the invention. The receiver  14  may be a silicon (micro-electromechanical machined, MEMS) receiver, a balanced armature receiver, or a moving coil receiver, depending on the desired applications. Other types of receiver are possible. The microphone  6 ,  12  may be a silicon (micro-electromechanical machined, MEMS) condenser microphone, an electret microphone, an omni-directional microphone, a directional microphone, or a dynamic microphone, depending on the desired applications. The microphones  6 ,  12  may be virtually any type of microphone. 
         [0016]    Depending on the type of microphone, the microphones  6 ,  12  may include a motor assembly (not shown) and a circuit assembly (not shown) arranged in series with the motor assembly, but not stacked over or under the motor assembly. The formation of the motor assembly and the circuit assembly will follow. 
         [0017]      FIGS. 2-3  illustrate an embodiment of the transducer monitor system  10 . The system  10  processes audio signals from an external environment for communication to the wearer and further provides for monitoring the SPL inside the ear canal. To do so, the system  10  may include the inside microphone  12  and the receiver  14 . The microphone  12  may be mounted to the receiver  14  and such mounting may be achieved by any conventional method of attachment. In this regard, the microphone  12  and the receiver  14  may form a conjoined microphone-receiver assembly as depicted in  FIG. 2 . However, such mounting is not required or essential to the invention, and the microphone  12  may exist within the system  10  separately from the receiver  14 . The microphone  12  may include a tapered housing  16 , an external terminal  20  and a sound port  18 . The housing  16  as shown includes a cover  16   a  and a base  16   b  attached to the cover  16   a  by any conventional method of attachments to retain the working components (e.g., a circuit assembly and a motor assembly as is well known). As shown in  FIG. 2 , the housing  16  is tapered near the sound port  18  to provide better fitting into the ear canal and/or the listening device incorporating the system  10  and further to accommodate the working components which will be discussed later. The external terminal  20  couples to the processing circuit system (See  FIG. 1 ) and may be mounted to a rear portion  16   d  of the housing  16 . The sound port  18  may be provided at a front portion  16   c  of the housing  16 , or at any convenient and operable location on the housing  16 . The microphone  12  senses acoustic signals within the ear canal representing a SPL in the ear canal. The microphone  12  converts these acoustic signals to electrical signals that may be processed by the processing circuit system (See  FIG. 1 ) along with other signals before the signal is transmitted to the receiver  14 . 
         [0018]    The receiver  14  may include a housing  22 , an external terminal  26 , and a sound port  24 . The housing  22  includes a cover  22   a  and a base  22   b  attached to the cover  22   a  by any conventional method of attachments to retain the working components (e.g., an acoustic assembly, a motor assembly, and a coupling assembly as is well known). The external terminal  26  coupled to the processing circuit system (See  FIG. 1 ) may be mounted to a rear portion  22   d  of the housing  22  and the sound port  24  may be provided at a front portion  22   c  of the housing  22 . Of course the terminal  26  and the sound port  24  may be provided at any convenient and operable location on the housing  22 . The receiver  14  is operable upon the processed signals received from the processing circuit system (See  FIG. 1 ) to generate acoustic signals that are then transmitted to the ear canal through the sound port  24  of the receiver  14 . In alternative arrangements, the external terminals  20 ,  26  of the microphone  12  and the receiver  14  may be combined into one terminal to minimize the number of electrical connections. As shown in  FIG. 3 , an optional tubing member  27  is coupled to the transducer monitor system  10 . A first tube portion  28  may mount to the microphone  12  and a second tube portion  29  may mount to the receiver  14 . As depicted in  FIG. 3 , the first and second tubing members may be a single, duel lumen structure or tubing member  27  having separate passageways  28 ′ and  29 ′. Alternatively, individual tube structures may be used. Each passageway  28 ′,  29 ′ is suitably aligned with the respective sound ports  18 ,  24  of the microphone  12  and the receiver  14 . It will be understood that the length of the tube(s) may vary without departing the scope of the invention. 
         [0019]      FIG. 4  illustrates an exploded view of a microphone  50 . The microphone  50  includes a motor assembly  30 , also known as electret portion and a circuit assembly  32 . The motor assembly  30  includes a diaphragm (not shown), a backplate  30   b , and a frame  30   c  sandwiched between the diaphragm (not shown) and the backplate  30   b . It will be understood that the operation of the microphone  50  is generally based on the change in capacitance and resulting electric signal that may be generated as a result of movement of the diaphragm (not shown) responsive to exposure to sound pressure relative to the fixed electrode of the backplate  30   b . The sound pressure may be the result of acoustic energy presented in front of the ear canal, or from other sources. The circuit assembly  32  is electrically coupled to the motor assembly  30  via a connecting lead  38 . The circuit assembly  32  may include a preamplifier such as, for example, a source-follower field effect transistor (FET) integrated circuit, or any suitable signal processing and amplification circuit. The microphone  50  may be an inside microphone  12  (See  FIG. 1 ), an outside microphone  4  (See  FIG. 2 ), or combination thereof. 
         [0020]      FIG. 5  illustrates a cross-sectional view of an exemplary embodiment of the microphone  12 . The motor assembly  30  is disposed within the housing  6  such that one side of the motor assembly  30  is fixedly attached to the inner surface of the front portion  16   c  and the opposed side of the motor assembly  30  is fixedly attached to the inner surface of the cover  16   a . The enclosed area  40   a , formed by the motor assembly  30  wherein the diaphragm  30   a  is faced downward to the inner surface of the cover  16   a  and the inner surface of the front portion  16   c , constitutes a front volume  40   a . The sound port  18  formed on the front portion  16   c  communicates with the front volume  40   a  to allow signals to enter the microphone  12 . The circuit assembly  32  is positioned adjacent the opposed side of the motor assembly  30  near where it attaches to the inner surface of the base  16   a  and itself is adjacent to the inner surface of the base  16   a . The circuit assembly  32  is attached within the housing to the inner surface of the rear portion  16   d . A ribbon wire  34  for grounding radio frequency interference (RFI) and a plurality of connecting wires (not shown) for providing input/output/power extend through a hole  18 ′ formed on the rear portion  16   d  of the housing  16 . The wires, in turn, couple to the external terminal(s)  20 . As depicted in  FIG. 5 , instead of stacking the motor assembly  30  either over or under the circuit assembly  32  as is typically done, the motor assembly  30  is arranged in what can be described as series or side-by-side relationship with the circuit assembly  32 . This arrangement advantageously reduces the overall height of the microphone  12 , for example, by about 5% to about 90% of a conventional microphone. More particularly, the microphone  12  may have a height of from about 0.5 to 1 mm. The cover  16   a  of the microphone  12  may further be formed with a tapered portion to allow deep fitting of the microphone and/or a corresponding exterior housing therefore into the ear canal and also to allow fitting into smaller listening devices. The outside microphone  6  as depicted in  FIG. 1  may be assembled the same way as the microphone  12  used for the transducer monitor system  10  or any other listening devices. 
         [0021]    The size, thickness and length, for example, of a microphone  12  may be further reduced. The housing  16  may be formed to include an aperture. The aperture may be formed in a single wall of the housing such as  16   a ,  16   b  or  16   d , or may be formed at the intersection of two walls. For example, an aperture may be formed where wall  16   a  intersects wall  16   d . The circuit board portion of the circuit assembly  32  may be positioned and secured within the opening, and thus the interior size of the housing  16  and correspondingly the exterior size of the housing may be reduced. Alternatively, the opening may be formed at the intersection of the wall  16   b  and the wall  16   d , and the circuit board portion of the circuit assembly  32  positioned and secured within that opening. In this later arrangement, it will be appreciated, that the circuit assembly  32  is positioned under motor assembly  30 , but not in the stacked arrangement of a typical electret microphone. Forming the housing to include a portion of the circuit assembly  32  advantageously allows for the connecting wires to be reduced or eliminated, as the external terminal(s) may be formed directly on the circuit assembly  32  and any connecting wires formed as traces on or within the circuit board portion of the circuit assembly  32 . Providing the connecting wires as traces on or within the circuit board portion of the circuit assembly  32  furthermore significantly reduces manufacturing/assembly complexity. Still further reductions in housing size may be achieved by forming all or a portion of the frame member of the motor assembly  30  into the one or more of the housing walls. The resulting microphone is highly compact with simplified manufacturing. 
         [0022]      FIG. 6  illustrates a cross-sectional view of another embodiment of the microphone  12 . A vent  46  may be formed on the cover  16   a  of the housing. The vent  46  may have a dimension of about 0.008 inches and may be formed by any suitable technique. The ultimate size and location of the vent  46  may depend upon the application. A member  48  with a vent  49  of a size different than the vent  46 , e.g., smaller, of the cover  16   a  may overlap the vent  46  and can be formed by any suitable technique. The vent  49  may have a dimension of about 0.001 inches when the vent  46  has the about 0.008 inches dimension. Alternatively the vent  46  of the cover  16   a  may include a plurality of smaller holes. Preferably the plurality of small holes has an acoustic resistance, with the acoustic resistance being chosen to be substantially equivalent to the acoustic resistance of a single hole acoustic vent. The member  48  is made of stainless steel. The use of other types of material for the housing is possible. The vents  46 ,  49  facilitate the pressure equalization between the front volume  40   a  and the surrounding outside the microphone housing  16 . An optional damping member may be provided to cover the first vent  46  or the second  49  and preventing debris from clogging the vents  46 ,  49 . The damping member may further modify the acoustic characteristics of the microphone  12 . 
         [0023]    All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extend as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0024]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.