Abstract:
An acoustic motor assembly includes a substrate with a diaphragm ring that is integrally formed with the substrate. The diaphragm ring forms an opening extending through the substrate. The assembly also includes an electrically charged plate extending over the opening; a diaphragm extending over the opening and vertically displaced from the electrically charged plate; and a stitch coupling the electrically charged plate to the diaphragm. Sound energy creates a movement of the diaphragm, and the movement is effective to create an electrical signal representative of the sound energy.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This patent claims benefit under 35 U.S.C. §119 (e) to United States Provisional Application No. 61918002 entitled “Microphone and Circuit and Motor Assembly” filed Dec. 19, 2013, the content of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This application relates to Electret Condenser Microphone (ECM) devices and, more specifically, to the construction and configuration of the substrates in these devices. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the case of an Electret Condenser Microphone (ECM), sound energy enters through a sound port and vibrates a diaphragm and this action creates a corresponding change in electrical potential (voltage) between the diaphragm and a charged back plate disposed near the diaphragm. This voltage represents the sound energy that has been received. Typically, the voltage is then transmitted to an electric circuit (e.g., an integrated circuit such as an application specific integrated circuit (ASIC)). Further processing of the signal may be performed on the electrical circuit. For instance, amplification or filtering functions may be performed on the voltage signal at the integrated circuit. 
         [0004]    The ECM includes an electret based motor. The electret based motor typically includes the diaphragm and charged back plate. A ceramic substrate is typically used for the integrated circuit. In these assemblies, a diaphragm ring and other extra components are used. The use of a separate diaphragm ring adds additional complexity to the system. For example, the diaphragm ring is an extra part that requires an extra step in the manufacturing process to install. In today&#39;s manufacturing environment it is extremely desirable to minimize the costs of the devices produced. Additional parts necessarily increase the cost of the ECM device and this has become undesirable under many circumstances. 
     
    
     
       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  comprises a top exploded view of an ECM assembly according to various embodiments of the present invention; 
           [0007]      FIG. 2  comprises a bottom exploded view of the ECM assembly of  FIG. 1  according to various embodiments of the present invention; 
           [0008]      FIG. 3  comprises a top perspective view of a circuit and motor combination of  FIG. 1  and  FIG. 2  incorporating a diaphragm ring into a ceramic substrate according to various embodiments of the present invention; 
           [0009]      FIG. 4  comprises a bottom perspective view of the circuit and motor combination of  FIG. 1 , FIG.  2 ., and  FIG. 3  incorporating a diaphragm ring into a ceramic substrate according to various embodiments of the present invention; 
           [0010]      FIG. 5  comprises a top perspective view of another circuit motor combination incorporating a diaphragm ring into a ceramic substrate according to various embodiments of the present invention; 
           [0011]      FIG. 6  comprises a bottom perspective view of the circuit motor combination of  FIG. 5  incorporating a diaphragm ring into a ceramic substrate according to various embodiments of the present invention; 
           [0012]      FIG. 7  comprises a cutaway perspective view of another ECM assembly according to various embodiments of the present invention; 
           [0013]      FIG. 8  comprises a top exploded view of another ECM assembly according to various embodiments of the present invention; 
           [0014]      FIG. 9  a perspective cutaway view of a hearing aid module including an ECM assembly according to various embodiments of the present invention; 
           [0015]      FIG. 10  comprises a perspective view of the hearing aid module of  FIG. 9  according to various embodiments of the present invention; 
           [0016]      FIG. 11  comprises a exploded perspective view of a double sided ceramic diaphragm according to various embodiments of the present invention; 
           [0017]      FIG. 12  comprises a side view of a double sided ceramic diaphragm of  FIG. 11  according to various embodiments of the present invention; 
           [0018]      FIG. 13  comprises a side cutaway view of the diaphragm assembly of  FIGS. 11 and 12  in a housing according to various embodiments of the present invention; 
           [0019]      FIG. 14  comprises a front perspective view of a side-by-side ceramic diaphragm assembly according to various embodiments of the present invention. 
       
    
    
       [0020]    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 
       [0021]    The approaches presented herein provide a circuit and motor combination with a diaphragm ring that is physically integrated with the substrate. By “integrated,” it is meant that the substrate and ring are formed together, made of the same material, and/or are contiguous. A simplified circuit and motor assembly are provided. Separate diaphragm rings needed and present in previous systems are eliminated. In some aspects, the diaphragm ring is incorporated into a ceramic substrate. 
         [0022]    In many of these embodiments, an extended ceramic substrate is used with an opening for the motor. As used herein, “motor” refers to the diaphragm and charged back plate. An opening may be created in a ceramic substrate, for example, by punching the ceramic substrate to form the diaphragm ring of the motor. A ground plane can be created on both the top and bottom portions connecting the diaphragm ring directly to the circuit ground. Consequently, no wire or cement (for example) is needed to couple the ring to the ground plane. 
         [0023]    In some advantages of the present approaches, a drop through assembly is provided. A reduced-sized part is provided since a separate diaphragm is not used. A standalone circuit and motor assembly could be provided to a customer, for example, in customer&#39;s face plate. Different size options are provided depending upon the desired mechanical outline and electroacoustic performance. A wire bond is provided from the circuit to the charged back plate and this is advantageous because two assembly operations are combined into one operation. Parasitic capacitance in the motor assembly is reduced because beyond the diaphragm and statically charged back plate, there are no other conductive surfaces that form capacitive constructions. Reduced parasitic capacitance is beneficial because it increases the gain of motor. The need to insulate the edge of the back plate from the diaphragm ring is also eliminated since surface is non-conductive. 
         [0024]    Referring now to  FIGS. 1-7 , one example of an ECM assembly is described. The assembly  100  includes a housing comprised of a top cover  102  and a bottom cover  104 , and a motor-circuit assembly  106  which includes epoxy  118 . 
         [0025]    The substrate  108  of the motor-circuit assembly  106  includes terminals  113  for signal, ground and power supply connections that protrude through an opening  112  in cover  104 . The terminals  113  may be constructed of metal pads in one example. 
         [0026]    Disposed over the opening  110  on substrate  108  are a back plate  114 , a diaphragm  116 , and epoxy  118 . The epoxy between the charge plate and diaphragm provides mechanical support and is sometimes referred to as a “stitch” due to its shape. A small bead of epoxy may be dispensed from a hypodermic needle to form the stitch at the four corners of the charge plate  114  (not shown). The epoxy “stitch”  118  may also be constructed of a conjoined B-stage adhesive and a polyimide (e.g., Kapton) as shown in figures which is configured to secure the charged back plate  114  to the assembly  106 . The construction of the charged back plate  114  and the diaphragm  116  are well known to those skilled in the art. The substrate  108  may in one example be a ceramic substrate and includes a diaphragm ring  111  (which is part of and incorporated with the substrate). In one aspect, the diaphragm ring  111  may be approximately 0.10 inches thick. Other dimensions may also be used. A wire  122  forms an electrical connection between the charged back plate  114  and an integrated circuit  124  (e.g., an application specific integrated circuit (ASIC)). The integrated circuit  124  may perform various processing functions such as amplifying the voltage produced. Capacitors  125  may be attached to the integrated circuit. A glass coating  127  may be applied to insulate and protect areas of circuit. A ground layer  129  may be exposed to provide an area that can be used to form a ground connection between the circuit  124  and cover  104 . A conduction pad  131  couples the wire  122  to the charged back plate  114  and the integrated circuit  124 . A sound port  120  is formed in the bottom cover  104  and allows sound into the assembly  100 . 
         [0027]    In one example of the operation of the system of  FIGS. 1-7 , sound energy enters through the sound port  120  and vibrates the diaphragm  116  and this action creates a corresponding change in electrical potential (voltage) between the diaphragm  116  and the charged back plate  114 . This voltage represents the sound energy that has been received. The voltage is transmitted via the wire  122  to the integrated circuit  124  where further processing of the signal may be performed. For instance, amplification or filtering functions may be performed on the voltage signal at the integrated circuit. 
         [0028]    Referring now to  FIG. 8 , one example of an ECM assembly is described. In this example, a step in housing is not used. Instead, cover  804  has a slanted portion that is used to connect sound inlet  820  to diaphragm  816  without impeding air flow. The other components are the same as those referred to in the example of  FIGS. 1-7  and like-numbered elements in  FIG. 8  refer to similar elements in  FIGS. 1-7 . 
         [0029]    Referring now to  FIG. 9  and  FIG. 10 , one example of a face plate module (e.g., as used in a hearing aid) including an ECM assembly is described. 
         [0030]    The face plate module  900  includes an ECM motor-circuit assembly  906 , and an outer housing portion  904 . The face plate module  900  may be used and attached to other housings or other components for example to form a hearing aid. The ECM motor-circuit assembly  906  includes a back plate  914 , a diaphragm  916 , and epoxy for mechanical support of plate  918 . It also includes integrated circuit  924  and capacitors  925 . The other components are the same as those referred to in the example of  FIGS. 1-7  and like-numbered elements in  FIG. 9  refer to similar elements in  FIGS. 1-7 . 
         [0031]    Referring now to  FIG. 11-13 , one example of a motor and circuit assembly  1106  that includes a double-sided motor is described. A substrate  1108  has attached to it charge plates or coatings applied to surfaces that is charged and are on opposite sides of substrate. A first diaphragm  1116  and a second diaphragm  1116  and an integrated circuit  1124  are disposed within the assembly  1106 . Terminals  1113  allow a customer to make connections from a hearing aid system to the assembly  1106 . This arrangement creates a dual microphone for vibration cancelation with the microphones being in-phase for picking up sound and 180 degrees out of phase for the picking up of vibration. In this example, the integrated circuit  1124  is coupled to both motors (i.e., the first motor with the first diaphragm  1116  and the second motor with the second diaphragm  1131 ). In this case, the integrated circuit receives two different inputs and produces a single output signal. Alternatively, two separate integrated circuits can be deployed with one integrated circuit for each motor and thus two output signals (not shown). 
         [0032]    Referring now to  FIG. 14 , one example of a side-by-side motor and circuit assembly  1400  is described. The assembly  1400  includes a first motor assembly  1406 , a second motor assembly  1406 , that may share a substrate  1408 . These elements are disposed under a top cover (not shown) and bottom cover (not shown) that forms an overall ECM assembly. Customer terminals  1413  may be arranged as shown in the other example devices described herein. 
         [0033]    Disposed over a first opening  1410  through the substrate is a first charged back plate  1414 , a first diaphragm  1416 , and a first stitch (not shown). Disposed over a second opening  1410  through the substrate is a second charged back plate  1414 , a second diaphragm  1417 , and a second stitch (not shown). As with the other examples described herein, a sound port is formed in the top cover and allows sound into the assembly  1400 . The construction of the charged back plates  1414 , and the diaphragms  1416  are well known to those skilled in the art. The stitches may be constructed of a conjoined B-stage adhesive and a polyimide (i.e. Kapton) and are configured to secure the charged back plates  1414  to the assembly  1400 . The substrate  1408  is a ceramic substrate and includes a first diaphragm ring  1411  and a second diaphragm ring  1411  (which are part of and incorporated into the substrate  1408 ). 
         [0034]    In one aspect, the diaphragm rings  1411  may be approximately 0.10 inches thick. Other dimensions may also be used. Wires  1422  couples the charged back plates  1414  to first and second integrated circuits  1424  via pads  1431 . The integrated circuits  1424  may be application specific integrated circuits (ASICs) in one example. The integrated circuits  1424  may perform various processing functions such as amplifying the voltage produced. 
         [0035]    It will be understood that the elements of the individual microphones shown in  FIG. 14  are the same as the elements described with respect to  FIGS. 1-7 , but that in  FIG. 14  two motors are disposed on the same substrate. It will be further understood that although two microphones are shown in  FIG. 14 , any number of microphones may be used. The functioning of these microphones may be the same or similar to the functioning of the microphone described with respect to  FIGS. 1-7 . 
         [0036]    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.