Patent Publication Number: US-9900684-B2

Title: Microphone device

Description:
RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Japanese Application No. JP2015-160636 filed Aug. 17, 2015, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a microphone device in which a microphone unit is attached inside microphone case with a cushioning member, and especially relates to a microphone device in which an arrangement of a microphone cable that leads out an electrical signal from the microphone unit is improved. 
     Description of the Related Art 
     In a case of a handheld microphone, a user directly holds the body of a microphone case. Therefore, applied vibration and acceleration are easily transmitted to the microphone unit in the microphone case. This generates a vibration noise called touch noise or handling noise. 
     Therefore, in this sort of microphone device, to prevent generation of the vibration noise, a configuration is employed in which the microphone unit is attached inside the microphone case with a cushioning member formed with a rubber material, and this microphone device is disclosed in patent publications, such as JP 2015-5942 A and JP 2008-177633 A. 
     The cushioning member that supports the microphone unit functions as a vibration isolator of the microphone unit and has a natural frequency of vibration, i.e. a resonant frequency. Therefore, when the cushioning member holding the microphone unit receives external vibration resonates, this causes to generate and output a large vibration noise output. Therefore, the resonant frequency needs to be set to a lower frequency band outside a sound collecting band of the microphone unit, or to a lower frequency band the noise at which seems to be inconspicuous even within the sound collecting band. 
     To achieve this, a high compliant material needs to be selected as the material of the cushioning member that functions as a vibration isolator, and accordingly the microphone unit can move in a large movable range in the microphone case. 
     Meanwhile, a microphone cable that leads an electrical signal from a microphone unit is connected between the microphone unit supported by the cushioning member and the microphone case that accommodates the microphone unit. 
       FIGS. 7 to 10  exemplarily illustrate the above-described arrangement of the microphone cable in the conventional microphone device including a cushioning member. 
     Note that the conventional microphone device illustrated in  FIGS. 7 to 10  includes members that serve the same functions as an embodiment according to the present invention illustrated in  FIGS. 1 to 6 , described below, and the members are illustrated with the same reference signs. Therefore, detailed configurations of respective portions will be described below based on  FIGS. 1 to 6 . 
     A microphone cable  45  in the conventional microphone device is arranged in a space along a nearly central portion of a microphone case  30 , without forming slack as possible in a substantially linear manner, and connects between a microphone unit  10  and a connector  47 , as exemplarily illustrated in  FIG. 7 . 
     According to the configuration illustrated in  FIG. 7 , the microphone cable  45  is arranged in a state of floating in the air in a space portion between a microphone unit  10  and a connector  47 . Therefore, vibration received by a microphone case  30  is transmitted to the microphone unit  10  from the connector  47  through the microphone cable  45 , as schematically illustrated by the broken line. Accordingly, the vibration noise is generated. 
     To prevent the generation of the vibration noise through the microphone cable  45 , use of a thinner wire can be suggested as the microphone cable  45 . 
     However, when the microphone device is dropped and a large shock is applied to the microphone device, the microphone unit  10  instantly swings largely with being held by cushioning members  41  and  42 . Accordingly, a problem occurs that an unreasonable tension is applied to the microphone cable  45  and the microphone cable  45  may be disconnected, as illustrated in  FIG. 8 . 
     Therefore, when sufficient looseness is provided to the microphone cable  45  connected to between the microphone unit  10  and the connector  47 , as illustrated in  FIG. 10 , disconnection of the microphone cable  45  can be prevented if a large shock is applied to the microphone device, as described above. In this case, however, the microphone cable  45  freely vibrates, and the free vibration of the microphone cable  45  is transmitted to the microphone unit  10 , as illustrated in  FIG. 9 , and this may cause to generate the vibration noise. 
     That is, the bi-directional arrow illustrated in  FIG. 9  illustrates a state that the microphone cable  45  freely vibrates, and the broken line schematically illustrates a situation where the vibration of the microphone cable  45  is transmitted to the microphone unit  10 . 
     SUMMARY OF THE INVENTION 
     In the microphone device in which the microphone unit is supported in the microphone case with the cushioning member, the microphone cable connecting the microphone unit and the connector has problems of generating vibration noise due to respective causes, as described based on  FIGS. 7 to 10 . Further, the microphone device has a problem of disconnection of the microphone cable when receiving a shock. 
     Therefore, an objective of the present invention is to provide a microphone device that can effectively prevent transmission of external vibration to a microphone unit through a microphone cable and transmission of vibration due to own vibration of the microphone cable to the microphone unit, and can prevent disconnection of the microphone cable even when a large shock is applied to a microphone case. 
     A microphone device according to the present invention includes: a microphone unit configured to output an electrical signal upon receipt of a sound wave; a microphone case that supports the microphone unit in an inside through a cushioning member formed of an elastic material; and a microphone cable configured to supply the electrical signal from a side of the microphone unit to an output connector attached to the microphone case, wherein a part of the microphone cable is attached along the cushioning member. 
     In this case, in one preferable embodiment, the part of the microphone cable is attached in a state of meandering back and forth once or more between one surface and the other surface of the cushioning member formed in a flat manner. 
     More preferably, a configuration is employed in which the microphone unit is attached to a front end portion of a unit support portion, the microphone unit is swingably supported in the microphone case together with the unit support portion in an axial direction by a front cushioning member and a rear cushioning member in at least two places front and rear of the unit support portion in the axial direction, and a part of the microphone cable is attached to the rear cushioning member close to the output connector. 
     Meanwhile, the rear cushioning member is formed preferably in a ring-shaped manner, has a peripheral edge portion attached to the microphone case, and swingably in the axial direction supports the unit support portion in a central portion. And a part of the microphone cable is attached in a state of meandering back and force once or more between one surface and the other surface of the cushioning member formed in a flat manner, using a plurality of through holes formed along the ring-shaped surface of the rear cushioning member. 
     Then, preferably, a condenser microphone unit is used as the microphone unit, a circuit board including an audio output circuit of the condenser microphone unit is mounted immediately after the condenser microphone unit in the unit support portion, and the circuit board and the output connector are connected with the microphone canle. 
     In addition, a configuration is employed in which the microphone cable is attached in a bundle of a plurality of signal lines, in a state of meandering back and forth once or more between one surface and the other surface of the cushioning member. 
     According to the microphone device of the present invention, the configuration is employed in which a part of the microphone cable that supplies an electrical signal from the microphone unit to the output connector is attached along the cushioning member formed of an elastic material. 
     Therefore, the part of the microphone cable is always in contact with the cushioning member formed of a rubber material, for example, and thus direct transmission of vibration received at the microphone case to the microphone unit side through the microphone cable can be prevented. Accordingly, generation of vibration noise can be effectively suppressed. 
     Further, since apart of the microphone cable is in contact with the cushioning member, free vibration caused in the microphone cable itself is suppressed, and generation of vibration noise due to the free vibration of the microphone cable can be suppressed. 
     Further, the microphone cable along the cushioning member can be arranged with some looseness. Therefore, when a shock is applied to the microphone case, the microphone cable is similarly deformed following deformation of the cushioning member. Thus, application of a force such as providing excessive tension to the microphone cable can be effectively prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is a sectional view illustrating an overall configuration of a microphone device according to the present invention; 
         FIG. 2  is an enlarged view illustrating a microphone unit of the microphone device according to the present invention; 
         FIG. 3  is a cross-sectional view of the microphone device according to the present invention in a state where the microphone receives a mechanical shock in an axial direction; 
         FIG. 4  is an enlarged vertical cross-sectional view illustrating an attached state of a microphone cable to a cushioning member; 
         FIG. 5  is a transverse cross-sectional view taken along the A-A line as viewed in the arrow direction in  FIG. 4 ; 
         FIG. 6  is an enlarged cross-sectional view of a state where the microphone receives a mechanical shock in the axial direction as illustrated in  FIG. 4 ; 
         FIG. 7  is a cross-sectional view illustrating an example of a conventional microphone device; 
         FIG. 8  is a cross-sectional view of the conventional microphone device in a state where the microphone receives a mechanical shock in an axial direction; 
         FIG. 9  is a cross-sectional view illustrating another example of the conventional microphone device; and 
         FIG. 10  is a cross-sectional view of the conventional microphone device in a state where the microphone receives a mechanical shock in an axial direction. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A microphone device according to the present invention will be described based on an embodiment illustrated in the drawings. 
       FIGS. 1 and 3  illustrate an example in which the present invention is applied to a condenser microphone by cross-sectional views. This condenser microphone includes, as a basic configuration, a microphone unit  10 , a unit support portion  20 , and a microphone case  30 . 
     In this embodiment, the microphone unit  10  is provided with a first element  11  and a second element  12  back to back. 
     Then, the microphone unit  10  is attached to a front end portion of the cylinder-shaped unit support portion  20  with a metal-made unit case  13 . 
     A dome-shaped cover  21  is attached to the cylinder-shaped unit support portion  20 , and a circuit board  22  including an audio output circuit of the microphone unit  10  is mounted in the unit support portion  20  right after the cover  21 . 
     The first element  11  in the microphone unit  10  configures a back electret condenser microphone unit in which a diaphragm faces a fixed electrode. 
     Meanwhile, the second element  12  does not configure a condenser microphone although including a fixed electrode and a diaphragm, and substantially functions as a high-pass filter (HPF) by cutting a low frequency range off of a sound wave entering from a rear acoustic terminal, and transmitting only a high frequency range to a back surface of the first element  11 . This HPF function especially improves low-range frequency characteristics of the condenser microphone. 
     Here, the acoustic terminal indicates a position of air that effectively provides a sound pressure to the microphone unit  10 . In other words, the acoustic terminal is a central position of the air moving at the same time with the diaphragm included in the microphone unit  10 . Since the microphone unit  10  is unidirectional, the acoustic terminals exist in front and back of the diaphragm, and the rear acoustic terminal is the acoustic terminal on the rear side of the diaphragm. 
     Then, a signal from the microphone unit  10  is led to the circuit board  22  through a relay rod  23  attached to a central portion of the dome-shaped cover  21 . 
       FIG. 2  is an enlarged view of the microphone unit  10 , and hereinafter, specific description will be given. The first element  11  configures aback electret condenser microphone unit including a diaphragm  11   a  and a fixed electrode  11   b  facing the diaphragm  11   a . Further, the fixed electrode  11   b  is supported by a support member  11   c  having electric conductivity, and the diaphragm  11   a  is supported by a diaphragm frame  11   d.    
     Similarly, the second element  12  also includes a diaphragm  12   a , a fixed electrode  12   b , a support member  12   c , and a diaphragm frame  12   d.    
     The two support members  11   c  and  12   c  are fastened and fixed with a fastening member  112  having conductivity. 
     The fixed electrode  11   b  of the first element  11  is electrically connected with the support member  11   c , the diaphragm  12   a  and the fixed electrode  12   b  of the second element  12  are electrically connected with the support member  12   c , and the support members  11   c  and  12   c  are electrically connected with the fastening member  112  and the diaphragm frame  12   d . Accordingly, the condenser microphone unit by the first element  11  and the high-pass filter by the second element  12  are connected in series. 
     Further, a conductive screw  113  is attached to the diaphragm frame  12   d , and the relay rod  23  is electrically connected to the screw  113 . 
     The cylinder-shaped unit support portion  20 , having the microphone unit  10  mounted in the front end portion, is supported inside of the microphone case  30  in two places front and rear of the unit support portion  20  in an axial direction with a front cushioning member  41  and a rear cushioning member  42 . 
     The front cushioning member  41  and the rear cushioning member  42  are respectively made of rubber materials, and accordingly, the microphone unit  10  is swingably supported in the microphone case  30  in the axial direction together with the unit support portion  20 . 
     In the front cushioning member  41 , an outside of a thin flat ring-shaped portion  41   a  forms a cylinder portion  41   b , and configures an attaching portion to the microphone case  30 . Further, an inside of the thin flat ring-shaped portion forms a short axial cylinder portion  41   c , and the cylinder portion  41   c  encloses the unit support portion  20 . 
     Then, the outside cylinder portion  41   b  of the front cushioning member  41  is sandwiched by an outer peripheral surface of a cylinder body  43  coaxially arranged in the microphone case  30  and an inner wall surface of the microphone case  30 , thereby being attached in the microphone case  30 . 
     Meanwhile, as illustrated in  FIGS. 4 to 6 , the rear cushioning member  42  includes a thin flat ring-shaped portion  42   a . An outer peripheral edge of the thin flat ring-shaped portion  42   a  is folded back inward, and configures an attaching portion  42   b  to the microphone case  30 . Further, a cylinder portion  42   c  is integrally formed with an inside of the thin flat ring-shaped portion  42   a . This cylinder portion  42   c  surrounds a hollow axial body  24  protruding in an axial direction and attached to a lower bottom portion of the unit support portion  20 . Accordingly, the rear cushioning member  42  supports the unit support portion  20  at the lower bottom portion. 
     Then, the attaching portion  42   b  folded back to an outer peripheral edge of the rear cushioning member  42  is locked with a lower end portion of the cylinder body  43  coaxially arranged in the microphone case  30 . This locking portion is attached by coming in contact with a step portion  30   a , having a slightly reduced inner diameter of the microphone case  30 , formed inside the microphone case  30 . 
     Note that six through holes  42   d  are formed in the thin flat ring-shaped portion  42   a  of the rear cushioning member  42  at regular intervals in a circumferential direction, as illustrated in  FIG. 5 . The through holes  42   d  are formed to penetrate one surface (front surface) facing the inside of the microphone case  30  and the other surface (back surface) at an opposite side to the front surface. These through holes  42   d  allow the thin flat ring-shaped portion  42   a  of the rear cushioning member  42  to be flexibly configured, and allow a part of a microphone cable  45  to meander up and down (to sew a front surface and a back surface of the through holes  42   d ) and locked. 
     An output connector  47  including a plurality of terminal pins  47   a  is attached to a lower end portion of the microphone case  30 , and the microphone cable  45  is connected between the circuit board  22  arranged immediately after the microphone unit  10  and the output connector  47 . Note that although the microphone cable  45  is illustrated as a single cable in the drawings, the single cable consists of a bundle of a plurality of signal lines. 
     The microphone cable  45  is then hung down in a substantially linear manner in a central portion of the unit support portion  20  from the circuit board  22 , and is led out from the inside of the unit support portion  20  to the inside of the microphone case  30  through an opening  20   a  (see  FIG. 4 ) formed in the lower bottom portion of the unit support portion  20 . Further, the microphone cable  45  pulled out from the unit support portion  20  is, as illustrated in  FIGS. 4 to 6 , attached to the rear cushioning member  42  using the through holes  42   d  formed in the rear cushioning member  42  at regular intervals in the circumferential direction. 
     That is, the microphone cable  45  illustrated in the drawings is attached in a state of meandering back and forth twice and a half from the front surface side (upper surface side) to the back surface side (lower surface side) through the through holes  42   d  of the rear cushioning member  42 . The microphone cable  45  pulled out to a lower surface side of the rear cushioning member  42  is then connected to the output connector  47  through an opening  30   c  formed in an inner partition wall  30   b  of the microphone case  30  in an axial direction. 
     The microphone cable  45  is fixed in the opening  20   a  formed in the lower bottom portion of the unit support portion  20  with an adhesive  20   b , and is also fixed in the opening  30   c  formed in the inner partition wall  30   b  of the microphone case  30  with an adhesive  30   d . That is, the microphone cable  45  is fixed to the unit support portion  20  and the microphone case  30  with the adhesives  20   b  and  30   d  at upper and lower portions of the rear cushioning member  42 . 
     The microphone cable  45  fixed with the adhesives  20   b  and  30   d  then meanders along an up and down direction of the rear cushioning member  42 , and is attached to the rear cushioning member  42  with some slacking. 
     Note that a ring member  51  to which a microphone front mesh  50  is attached is threaded into an upper end opening portion of the microphone case  30 , and accordingly, the microphone unit  10  attached to the front end portion of the unit support portion  20  is covered with the microphone front mesh  50 . 
     According to the microphone device having the above-described configuration, the microphone unit  10  is attached to the microphone case  30  together with the unit support portion  20  through the front cushioning member  41  and the rear cushioning member  42 . 
     Therefore, even if a shock is applied to the microphone case  30 , transmission of the shock to the microphone unit  10  is effectively reduced, as illustrated in  FIGS. 3 to 6 , and generation of vibration noise can be suppressed. 
     In addition, a part of the microphone cable  45  that supplies the electrical signal from the microphone unit  10  side to the output connector  47  side is attached along the rear cushioning member  42 . Therefore, transmission of vibration to the microphone unit  10  side through the microphone cable  45  can be effectively prevented. Further, the rear cushioning member  42  can suppress free vibration of the microphone cable  45  itself. Therefore, suppression effects of the vibration noise can be further exhibited. 
     Note that the above embodiment has been described using the condenser microphone as an example. However, the present invention can be applied to dynamic microphones, for example. Especially, the dynamic microphones are susceptible to inertial force due to an increase in a weight of a voice coil, and as measurements of that, it is desirable to use a more compliant cushioning member. 
     According to the present invention, the microphone cable  45  can be similarly deformed following a relatively large deformation operation of the cushioning member. Therefore, the above-described functions and effects such as avoidance of application of stress to the microphone cable can be obtained.