Patent Publication Number: US-9431738-B2

Title: Microphone connector

Description:
TECHNICAL FIELD 
     The present invention relates to a connector of a microphone, the microphone, and a method for manufacturing the connector of the microphone. 
     BACKGROUND ART 
     A traditional connector of a microphone is assembled through the following processes. An internal assembly (pin insert) including connector pins and electronic parts is inserted into a cylindrical connector case. After this step, the connector case is tightened with screws toward the internal assembly from the exterior in the radial direction of the connector case. The internal assembly is fixed in the connector case through these processes. 
     In such a connector of a microphone, the connector case is tightened with screws toward the internal assembly from the exterior in the radial direction of the connector case; hence, the connector pins of the internal assembly are pulled in the axial directions of the screws. 
     As a result, the connector of the microphone may cause the eccentricity or rotation of the pin insert, leading to the displacement of the connector pins from a predetermined position. In this case, the traditional connector of the microphone causes no contact of the connector pins or no engagement in the connection between the male and female connectors. 
     A condenser microphone includes electronic circuits, such as a detecting unit (microphone unit) for detecting vibration of air, an impedance converter, or an output circuit, which include electronic parts. 
     Electric signals detected in the detecting unit have high impedance. In order to avoid the influence of noise, the impedance converter must convert high impedance electric signals into low impedance electric signals and efficiently output the signals. 
     For example, a microphone cord is exposed to strong electromagnetic waves to cause a high frequency current to flow into the microphone through the connector of the microphone. The flow of the high frequency current is detected by circuit elements in the electronic circuits to cause noise in audio signals. 
     Techniques are disclosed for preventing the eccentricity or rotation of a pin insert fit into a connector case in assembly processes of a microphone (for example, see Japanese Unexamined Patent Application Publications Nos. 2008-141575 (Patent Literature 1) and 2008-67341 (Patent Literature 2)). 
     Other techniques are disclosed for providing an electrostatic shield over a connector for prevention of noise in a condenser microphone (for example, see Japanese Unexamined Patent Application Publications Nos. 2005-094575 (Patent Literature 3) and 2011-205179 (Patent Literature 4)). 
     Unfortunately, the techniques disclosed in Patent Literatures 1 and 2 also involve the connector case tightened with the screws toward the pin insert from the exterior in the radial direction of the connector case. As a result, the connector pins are pulled in the axial directions of the screws. In other words, the displacement of the pin insert in the techniques disclosed in Patent Literatures 1 and 2 also causes no contact of the connector pins or no engagement in the connection between the male and female connectors. 
     In addition, the techniques disclosed in Patent Literatures 3 and 4 require an additional shielding component, such as a magnetic sheet for an electrostatic shield over the connector to therefore increase the numbers of the components and the assembly steps. 
     SUMMARY OF INVENTION 
     Technical Problem 
     It is an object of the present invention to provide a connector of a microphone with reduced displacement, such as eccentricity, of pins in the connector. 
     Solution to Problem 
     A connector of a microphone includes according to the present invention a cylindrical connector case having openings at both ends and a projection on an inner face thereof, two substrates having shapes fittable to the inner face of the cylindrical connector case, the substrates facing each other across the projection in the cylindrical connector case; and a connector pin extending through the substrates in the cylindrical connector case, having a contact that is electrically connected to another electronic device, and having a caulked portion fixed to one of the substrates on an opposite side to the contact. 
     Advantageous Effects of Invention 
     The present invention can prevent the displacement, such as eccentricity, of the connector pin. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view illustrating a condenser microphone according to an embodiment of the present invention. 
         FIG. 2  is a longitudinal cross-sectional view illustrating a connector of the microphone according to the embodiment of the present invention. 
         FIG. 3  is a circuit diagram illustrating a filter circuit in the connector of the microphone in  FIG. 2 . 
         FIG. 4  is an exploded longitudinal cross-sectional view of the connector of the microphone in  FIG. 2 . 
         FIG. 5  is a longitudinal cross-sectional view illustrating a connector pin assembled in the connector of the microphone in  FIG. 2 . 
         FIG. 6  is a longitudinal cross-sectional view illustrating steps for caulking the connector pin in the connector of the microphone in  FIG. 2 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A microphone, a connector of the microphone, and a method for manufacturing the connector of the microphone will now be described according to embodiments of the present invention. 
     [Microphone] 
     A microphone according to an embodiment of the present invention will now be described with reference to the accompanying drawings. 
       FIG. 1  is a side view illustrating a microphone according to the embodiment of the present invention. As illustrated in  FIG. 1 , the microphone  20  includes a connector  22  at the back end. 
     The connector  22  is attachable and detachable to a microphone cable connector  28  connected to one end of a microphone cable  24 . The connector  22  in this embodiment is male while the microphone cable connector  28  is female. 
     The top end of the microphone cable connector  28  is inserted into a connector case  1  of the connector  22 . The microphone cable connector  28  has a socket at the top end. 
     The connector  22  has a connector pin  2  engaged into the socket of the microphone cable connector  28  inserted into the connector case  1 . The connector pin  2  is engaged into the socket to electrically connect the connector  22  to the microphone cable connector  28 . 
     [Connector of Microphone] 
     The connector of the microphone according to an embodiment of the present invention will now be described with reference to the accompanying drawings. 
       FIG. 2  is a longitudinal cross-sectional view illustrating the connector of the microphone according to the embodiment of the present invention. As illustrated in  FIG. 2 , the connector  22  includes the cylindrical connector case  1 . The connector case  1  is a hollow cylindrical connector  22  having two openings. 
     A first opening  14  has a shape fittable to the microphone cable connector  28 . A second opening  15  is disposed on the opposite side to the first opening  14  of the connector case  1 . 
     The connector case  1  has a projection  10  on the inner circumference. A first substrate  11  and a second substrate  12  are engaged to the projection  10 . The projection  10  may be provided on the entire inner circumference of the connector case  1 . Alternatively, projection fragments  10  may be provided so as to support at least several positions of each of the first and second substrates  11  and  12 . 
     The connector case  1  has a screw hole  17  for fixing the connector  22  to the microphone  20  with a screw. 
     The first and second substrates  11  and  12  have shapes fittable to the inner face of the connector case  1 . The shapes fittable to the inner face of the connector case  1  refer to shapes that are similar to or receivable in the interior of the connector case  1 . The first and second substrates  11  and  12  are discs fittable to the inner face of the connector case  1 . The first and second substrates  11  and  12  are discs having conductive patterns on both faces for implementing electronic circuits, for example, printed circuit boards (PCBs). 
     The first and second substrates  11  and  12  mounted in the connector case  1  have respective conductive patterns on their inner faces facing each other. The conductive patterns constitute a filter circuit for the microphone  20  in collaboration with electronic parts  16 . The electronic parts  16  mounted on the inner faces of the first and second substrates  11  and  12  are, for example, zener diodes or capacitors. 
     Conductive patterns on the outer faces opposite to the respective inner faces of the first and second substrates  11  and  12  function as ground patterns. The ground patterns on the outer faces of the first and second substrates  11  and  12  mounted in the connector case  1  are grounded via the connector case  1 . The electronic parts  16  mounted on the inner faces of the first and second substrates  11  and  12  are surrounded by the grounded conductive patterns and electrically shielded from the exterior. 
     The first and second substrates  11  and  12  mounted in the connector case  1  have through-holes  111  and  121  respectively for inserting the connector pin  2 , on a common straight line in parallel to the central axis of the connector case  1 . The numbers of the through-holes  111  and  121  correspond to the number (generally three) of the connector pins  2  in the connector  22 . 
     An approximate half along the length of the connector pin  2  functions as a contact  21  electrically connected to the microphone cable connector  28 . The residual half along the length of the connector pin  2  is a slim portion  27 . The connector pin  2  has a step  29  between the contact  21  and the slim portion  27 . 
     In the connector case  1 , the slim portion  27  is inserted into the through-hole  111  of the first substrate  11  and the through-hole  121  of the second substrate  12  in this order from the first opening  14  along the length of the connector pin  2 , i.e., along the central axis of the connector case  1 . The connector pin  2  is fixed in the longitudinal direction by the contact of the step  29  in the connector pin  2  to the outer face of the first substrate  11 . 
     Although only one connector pin  2  is illustrated in  FIG. 2 , any number of connector pins may be provided to the present invention. 
     A portion of the connector pin  2  adjacent to the first opening  14  functions as the contact  21  for electrical connection with the microphone cable connector  28 . Another portion (on the other side) of the connector pin  2  adjacent to the second opening  15  functions as a caulked portion  23  fixed on the second substrate  12 . The caulked portion  23  has a slit  25  along the length of the connector pin  2 . The slit  25  facilitates expansion of the caulked portion  23  for the caulking. 
     As illustrated in  FIG. 2 , the caulked portion  23  projects from the outer face (at the right in  FIG. 2 ) of the second substrate  12  through the through-hole  121  of the second substrate  12 . 
     An engaged member  3  covering the caulked portion  23  of the connector pin  2  is engaged on the other side of the connector pin  2  extending through the first and second substrates  11  and  12 . The engaged member  3  is engaged along the outer circumference of the caulked portion  23 . 
     The engaged member  3  is a cylinder having a slim portion  32  and a thick portion  33 , which are separated at a step  31  on the inner face. In the engaged member  3 , the caulked portion  23  is caulked and engaged with the step  31 . 
     The caulked portion  23  is caulked to fix the first and second substrates  11  and  12  to the connector case  1  between the steps  29  and  31  such that the projection  10  and a spacer  4  are held between the first and second substrates  11  and  12 . 
     The engaged member  3  is fixed around the outer circumference of the connector pin  2 , and one end of the engaged member  3  is in contact with the outer face of the second substrate  12 . 
     The spacer  4  is disposed between the first and second substrates  11  and  12  through which the connector pin  2  extends. 
     The spacer  4  defines the distance between the first and second substrates  11  and  12  in the longitudinal direction in the connector case  1 . The spacer  4  is a cylinder having a length corresponding to the defined distance. The spacer  4  fixes the connector pin  2  along its central axis in the connector case  1  in collaboration with the projection  10  of the connector case  1 . 
     The spacer  4  also prevents the inclination of the first and second substrates  11  and  12  in the connector case  1 . 
     The spacer  4  is a cylinder (ferrite bead) composed of, for example, ferrite. The spacer or ferrite bead  4  functions as a self-inductance component (inductor) of a filter circuit due to a current flowing through the connector pin  2  extending through the spacer  4 . 
       FIG. 3  is a circuit diagram illustrating a filter circuit in the connector  22  of the microphone in  FIG. 2 .  FIG. 3  exemplifies three connector pins  2  (PIN 1 , PIN 2 , and PIN 3 ) in the connector  22 . 
     As illustrated in  FIG. 3 , the connector  22  is a three-pin microphone connector including pins PIN 1 , PIN 2 , and PIN 3 . The connector  22  can have a ground pin PIN 1 , and a hot pin PIN 2  and a cold pin PIN 3  of a balanced output. 
     In the filter circuit, a zener diode ZD 1  is connected to a capacitor Cl in parallel between the pins PIN 1  and PIN 2 . In the filter circuit, a zener diode ZD 2  is connected to a capacitor C 2  in parallel between the pins PIN 1  and PIN 3 . 
     In the filter circuit, a capacitor C 3  is connected between the pins PIN 1  and PIN 2 . In the filter circuit, a capacitor C 4  is connected between pins PIN 1  and PIN 3 . In the filter circuit, a coil L 1  is connected to the pin PIN 1 . 
     The filter circuit has an inductor L 2  since the connector pin  2  (PIN 2 ) is inserted into the spacer or ferrite bead  4 . The filter circuit similarly has an inductor L 3  since the connector pin  2  (PIN 3 ) is inserted into the spacer or ferrite bead  4 . 
     The capacitors C 1 , C 2 , C 3 , and C 4 , the inductors L 1 , L 2 , and L 3 , and the zener diodes ZD 1 , and ZD 2  constitute a filter circuit (low-pass filter circuit) for an electrostatic shield. The filter circuit is disposed on the respective inner faces of the two circuit substrates (the first and second substrates  11  and  12 ) to be shielded from the exterior. This configuration can enhance the filtering effect. 
     As described above, the first and second substrates  11  and  12  can be aligned in the connector  22  while the electronic parts  16 , such as zener diodes can be protected from an overcurrent flowing from the connector pin  2 . 
     [Method for Manufacturing Connector] 
     A method for manufacturing the connector  22  will now be described. 
       FIG. 4  is an exploded longitudinal cross-sectional view of the connector  22 . As illustrated in  FIG. 4 , the connector  22  is assembled through steps for assembling the spacer  4 , the first substrate  11 , and the connector pin  2  in this order from the first opening  14  of the connector case  1 . In the next step, the second substrate  12  and the engaged member  3  are assembled in this order from the second opening  15 . 
     These assembling steps are performed by aligning the through-hole  111  of the first substrate  11 , the through-hole  121  of the second substrate  12 , the spacer  4 , and the connector pin  2 . 
       FIG. 5  is a longitudinal cross-sectional view illustrating the connector pin  2  assembled in the connector  22 . As illustrated in  FIG. 5 , the first and second substrates  11  and  12  are certainly aligned by the projection  10  and the spacer  4  in assembling the first and second substrates  11  and  12  and the connector pin  2  in the connector case  1 . 
     In other words, since the projection  10  and the spacer  4  prevent the inclination and eccentricity of the connector pin  2  attached to the first and second substrates  11  and  12  in the connector  22 , the connector pin  2  is not misaligned. 
       FIG. 6  is a longitudinal cross-sectional view illustrating steps for caulking the connector pin  2 . As illustrated in  FIG. 6 , the caulked portion  23  is caulked while the contact  21  is covered with a first jig  51  to prevent the connector pin  2  from moving toward the first opening  14  in the longitudinal direction. 
     In this state, a second jig  52  is inserted toward the caulked portion  23  in the longitudinal direction from the second opening  15  to caulk and join the second substrate  12 , the caulked portion  23 , and the engaged member  3 . When the second jig  52  is pressed, the tapered tip of the second jig  52  bites into the inner circumference of the caulked portion  23  to spread the caulked portion  23 . As a result, the caulked portion  23  bites into the step  31  of the engaged member  3 . In this way, the caulked portion  23  is engaged with the step  31  of the engaged member  3  to certainly fix the connector pin  2 . 
     [Advantageous Effects of Embodiment] 
     As described above, the microphone  20  and the connector  22  according to the present embodiment have the following advantageous effects. 
     According to the microphone  20  and the connector  22 , the inner shape of the connector case  1  and the projection  10  can readily fix the first and second substrates  11  and  12  in the longitudinal direction without misalignment of the connector pin  2 . 
     According to the microphone  20  and the connector  22 , the spacer  4  disposed between the first and second substrates  11  and  12  can readily fix the first and second substrates  11  and  12  and the connector pin  2 . 
     According to the microphone  20  and the connector  22 , the connector pin  2  can be fixed to the second substrate  12  by the caulked portion  23  to readily fix the first and second substrates  11  and  12  to the connector case  1 . 
     According to the microphone  20  and the connector  22 , the conductive patterns on the outer faces of the first and second substrates  11  and  12  can function as electrostatic shields to prevent noise caused by a high frequency current through the connector  22 . 
     According to the microphone  20  and the connector  22 , the spacer  4  through which the connector pin  2  extends is a ferrite bead which can function as a filter circuit for an electrostatic shield right near the connector pin  2 . According to this configuration, the microphone  20  and the connector  22  can effectively protect the internal transmission path from exogenous noise. 
     As described above, the method for manufacturing the connector of the microphone according to the present embodiment can produce high-quality connectors with high productive efficiency and a high yield rate.