Abstract:
To obtain a ribbon microphone unit, which makes the tension of a diaphragm adjustable by configuring a ribbon diaphragm assembly that is detachable to a magnetic-circuit assembly including a magnet, and which further allows a user side to carry out the maintenance by replacing the ribbon diaphragm assembly; a ribbon microphone unit comprises: a magnetic-circuit assembly including a magnet; and a ribbon diaphragm, wherein the ribbon diaphragm, together with a substrate having a circuit pattern formed on both ends thereof, a metal fitting for crimping an end portion of the ribbon diaphragm to the circuit pattern, and a screw for crimping the metal fitting toward the substrate, constitute a diaphragm assembly, and wherein the diaphragm assembly is secured to the magnetic-circuit assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to ribbon microphones and ribbon microphone units. 
     2. Related Background of the Invention 
     A ribbon microphone includes a magnet for forming a magnetic field and a ribbon diaphragm, as main component members. The magnet is disposed on both sides of the ribbon diaphragm to sandwich the same, whereby a magnetic field is formed between the magnets on the both sides. The ribbon diaphragm is given an appropriate tension and disposed within the magnetic field while the both longitudinal ends are held down. In response to a sound wave, the ribbon diaphragm vibrates within the magnetic field and thereby a current corresponding to the sound wave flows through the ribbon diaphragm and thus the sound wave is converted into an electric signal. Generally, an aluminum foil is used as the material of the ribbon diaphragm. Since aluminum has an excellent electrical conductivity as compared with other metallic materials and also has a low specific gravity, aluminum is suitable as the ribbon diaphragm of the ribbon microphone. 
     The ribbon microphone is a mass control type microphone, and in the reproduction limit of the low frequency side, the lower the resonance frequency of the ribbon diaphragm, to the lower frequency the sound signal can be electroacoustically transduced. However, if the resonance frequency of the ribbon diaphragm is too low, such a problem will occur that the ribbon diaphragm easily moves to contact a pole for forming the magnetic field when a wind blows against the ribbon diaphragm or when a vibration is applied thereto. For this reason, in order to attach the ribbon diaphragm, it is necessary to pull the both longitudinal ends with an appropriate force, fix the both ends under an appropriate tension, and increase the resonance frequency to an appropriate frequency. 
     Then, in the manufacture process of the conventional ribbon microphone or in the adjustment process thereof, an operator lightly blows on the ribbon diaphragm, and visually observes and checks the bending level of the ribbon diaphragm at that time, and then adjusts the tension to an appropriate one. As described above, an aluminum foil is suitable for the ribbon diaphragm of the ribbon microphone. However, since the aluminum foil is extremely thin and light weighted, it may break when provided in a tensioned state while the tension is adjusted. Accordingly, good or poor results of the product largely depend on the skills of an operator, so a lot of skills are required in order to manufacture an excellent ribbon microphone. 
     Although the present invention relates to the ribbon microphone, the structure is similar to the structure of a ribbon speaker. In the ribbon speaker, a signal current is passed through a ribbon diaphragm, and then cooperating with a magnetic field which a magnet generates, the ribbon diaphragm is vibrated to generate sounds. Hereinafter, the inventions described in Patent Documents related to the present invention, including the ribbon speaker, will be described. 
     The invention described in Patent Document 1 relates to a tension adjustment method of a ribbon diaphragm of a ribbon microphone. This conventional ribbon microphone unit comprises a yoke formed into a square frame, and a ribbon diaphragm disposed along the longitudinal direction of the yoke and in the center portion in the width direction of this yoke. The yoke integrally includes a support plate near the both longitudinal ends, and a presser plate is disposed on the lower surface side of these support plates, respectively. The presser plate is secured to the support plates by fastening a screw, respectively. This screw is adjusted so as to lightly press the ribbon diaphragm in advance, and then the ribbon diaphragm is vibrated by a vibrator, and while observing its amplitude, the tension of the ribbon diaphragm is adjusted, and then by fastening the screw the ribbon diaphragm is secured. Since the screw is used as a securing unit of the ribbon diaphragm, the tension adjustment of the ribbon diaphragm can be carried out repeatedly. 
     The invention described in Patent Document 2 relates to a method of assembling a diaphragm assembly including a ribbon diaphragm used for a ribbon speaker. This conventional example comprises: a ribbon diaphragm that is wound in a roll form; a magazine component in which a slit is formed in the longitudinal direction and an adhesive layer is formed in the surface thereof; and a pressure roller wider than the slit. The above-described magazine component is made up of a nonmagnetic aluminum material, and the ribbon diaphragm is disposed parallel to the longitudinal direction of the slit. In the method of assembling the diaphragm assembly, while moving the magazine component in the longitudinal direction, the ribbon diaphragm is continuously pressure-welded to the magazine component via the adhesive layer by the pressure welding of a pressure roller, and thereby the both longitudinal ends of the ribbon diaphragm are bonded to the magazine component. According to the method of assembling the diaphragm assembly, which is a conventional example, the failure rate of the ribbon diaphragms caused by a manual assembly can be reduced, and the diaphragm assembly can be manufactured automatically and continuously. 
     The invention described in Patent Document 3 relates to a ribbon speaker. This conventional example comprises: a yoke, wherein a magnetic gap-forming portion of the yoke that constitutes a magnetic circuit together with a magnet is divided; and a vibration-system assembly provided with a ribbon diaphragm. The vibration-system assembly functions as a spacer, which prevents the divided yokes from contacting to each other by interposing a nonmagnetic material, e.g., an aluminum material, between the divided yokes. Moreover, by interposing the vibration-system assembly within the parallel magnetic field generated between the divided yokes, excellent frequency characteristics can be obtained. A signal current is passed through the diaphragm provided in the vibration-system assembly to vibrate the diaphragm, thereby outputting a sound. The vibration-system assembly can be detached by disassembling each of the divided yokes. Accordingly, when the diaphragm is damaged, the repair of the damage or the component replacement can be easily carried out by detaching the vibration-system assembly. 
     The invention described in Patent Document 4 relates to a ribbon speaker. Both ends in the axial length direction of a ribbon diaphragm are supported with a stationary terminal, and at the same time an ultraviolet curing resin is applied to the edge in the axial length direction and to the wall surface of a plate disposed within a magnetic gap, in which the ribbon diaphragm is disposed. Then, the ultraviolet curing resin is irradiated with an ultraviolet ray and is reacted, and thereby the diaphragm is attached to the inside of the magnetic gap of the magnetic circuit. The air-setting adhesive has a drawback that a long curing time and also an unstable cured state due to the variation in the curing conditions affect the performance of the ribbon diaphragm. In contrast, in the ultraviolet curing resin, a portion coated with the ultraviolet curing resin is irradiated with an ultraviolet ray, thereby eliminating a non-uniformity or variation in the cured state or curing time and thus obtaining a stable cured state. 
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2006-319595 
     [Patent Document 2] Japanese Unexamined Patent Application Publication No. S57-171900 
     [Patent Document 3] Japanese Unexamined Utility Model Application Publication No. S57-163892 
     [Patent Document 4] Japanese Unexamined Utility Model Application Publication No. S57-119989 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     The ribbon diaphragm of the ribbon microphone is likely to be loosened by being blown by a strong wind or by an application of an impact, and if the loosened amount becomes above a certain level, it is necessary to readjust the tension and furthermore replace the ribbon diaphragm. According to the invention described in Patent Document 1, the use of a screw as the securing unit of the ribbon diaphragm allows for the readjustment of the tension of the ribbon diaphragm. However, according to the conventional ribbon microphones including that of the invention described in Patent Document 1, the ribbon diaphragm is secured directly to the magnetic-circuit assembly to constitute the microphone unit, and therefore there is a drawback that only those of skill in the ribbon microphone can maintain the ribbon microphone. Accordingly, when the adjustment or replacement of the ribbon diaphragm is required, the whole microphone needs to be sent to the manufacturer. 
     In the inventions described in Patent Documents 2 to 4, as the method of adhering the ribbon diaphragm to the magazine component or the plate, an adhesive, thermocompression bonding, or bonding by an ultraviolet curing resin is used. These inventions relate to the diaphragm of the ribbon speaker, and even if these inventions are applied to a diaphragm made up of a very thin material, such as aluminum foil, as in the present invention in this application, it is impossible to cause the resultant diaphragm to function as a diaphragm that vibrates in response to a sound wave. Even if referring to the configuration of the conventional ribbon speaker and this configuration is applied to the diaphragm of a ribbon microphone, the ribbon diaphragm is difficult to be detached once bonded to a plate or the like. For example, in a diaphragm bonded using an air-setting adhesive or the like, the diaphragm needs to be detached by heat treating the adhesion portion again and the diaphragm itself may be damaged depending on the circumstances. Furthermore, in the ribbon speaker, once the diaphragm is incorporated, the tension needs not be readjusted, and therefore there is not even a concept of replacing the ribbon diaphragm. 
     In view of the prior arts described above, the present invention has employed a concept of configuring a ribbon diaphragm assembly that is detachable to a magnetic-circuit assembly, and an object of the present invention is to provide a ribbon microphone and a ribbon microphone unit which make it possible to detach the ribbon diaphragm assembly from the magnetic-circuit assembly and then adjust the tension of the diaphragm, and which further allows a user side to carry out the maintenance of the ribbon diaphragm by replacing the ribbon diaphragm assembly. 
     Means for Solving the Problems 
     According to a main feature of the present invention, a ribbon microphone unit comprises: a magnetic-circuit assembly including a magnet and having a magnetic gap; and a ribbon diaphragm that is disposed inside the magnetic gap and vibrates in response to a sound wave, wherein the magnetic-circuit assembly comprises: a yoke having a window hole; and a magnet secured to a wall surface of the window hole, wherein the ribbon diaphragm, together with a substrate having a window hole and having a circuit pattern formed on both ends of the window hole, a metal fitting for crimping an end portion of the ribbon diaphragm to the circuit pattern, and a screw for crimping the metal fitting toward the substrate, constitute the ribbon diaphragm assembly, and wherein the ribbon diaphragm assembly is secured to the magnetic-circuit assembly. 
     Advantages of the Invention 
     The ribbon microphone unit according to the present invention comprises the magnetic-circuit assembly and the ribbon diaphragm assembly (hereinafter, referred to as the “diaphragm assembly”), and each of them is detachable. This structure allows a user side to detach the diaphragm assembly from the magnetic-circuit assembly and carry out the maintenance, such as the tension adjustment, replacement, and the like of the ribbon diaphragm. In particular, the replacement of the diaphragm assembly can be easily carried out by detaching the diaphragm assembly from the magnetic-circuit constituting portion and then by attaching a new diaphragm assembly, and therefore the magnetic-circuit assembly needs not be replaced. Moreover, the replacement of the magnetic-circuit assembly can be easily carried out by detaching the diaphragm assembly from the magnetic-circuit assembly. Furthermore, the maintenance of only the ribbon diaphragm is also possible, and by loosening a screw securing the ribbon diaphragm via the metal fitting, the tension adjustment or the detachment of the ribbon diaphragm is possible. 
     Moreover, in the ribbon microphone unit according to the present invention, a dustproof cloth or a magnet may be attached to the window hole of the diaphragm assembly. This structure can prevent the occurrence of a problem by preventing the penetration of a minute iron powder or foreign substance, which is to enter the inside of the microphone unit from the outside of the ribbon microphone, by means of the dustproof cloth, or by adhering the minute iron powder or foreign substance to the magnet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an embodiment of a ribbon microphone according to the present invention, wherein  FIG. 1(   a ) is a schematic plane view, and  FIG. 1(   b ) is a schematic front view. 
         FIG. 2  shows the ribbon microphone according to the embodiment, wherein  FIG. 2(   a ) is a plane cross sectional view,  FIG. 2(   b ) is a front cross sectional view, and  FIG. 2(   c ) is a side cross sectional view. 
         FIG. 3  shows a microphone unit in the embodiment, wherein  FIG. 3(   a ) is a cross sectional view when viewed from the front,  FIG. 3(   b ) is a plane view, and  FIG. 3(   c ) is a cross sectional view when viewed from the side. 
         FIG. 4  shows a magnetic-circuit assembly in the embodiment, wherein  FIG. 4(   a ) is a front view,  FIG. 4(   b ) is a plane view, and  FIG. 4(   c ) is a cross sectional view when viewed from the side. 
         FIG. 5  shows a diaphragm assembly in the embodiment, wherein  FIG. 5(   a ) is a plane view,  FIG. 5(   b ) is a cross sectional view when viewed from the side, and  FIG. 5(   c ) is a bottom view. 
         FIG. 6  shows the diaphragm assembly in the embodiment, wherein  FIG. 6(   a ) is an exploded cross sectional view when viewed from the side, and  FIG. 6(   b ) is an exploded cross sectional view when viewed from the side. 
         FIG. 7  shows the diaphragm assembly in the embodiment, wherein  FIG. 7(   a ) is an exploded plane view, and  FIG. 7(   b ) is a plane view. 
         FIG. 8  shows a substrate in the embodiment, wherein  FIG. 8(   a ) is a plane view, and  FIG. 8(   b ) is a bottom view. 
         FIG. 9  shows a magnet in the embodiment, wherein  FIG. 9(   a ) is a plane view, and  FIG. 9(   b ) is a front view. 
         FIG. 10(   a ) shows a spacer in the embodiment, wherein  FIG. 10(   a ) is a plane view, and  FIG. 10(   b ) is a side view. 
         FIG. 11(   a ) shows a metal fitting in the embodiment, wherein  FIG. 11(   a ) is a plane view, and  FIG. 11(   b ) is a side view. 
         FIG. 12  shows a ribbon diaphragm in the embodiment, wherein  FIG. 12(   a ) is a front view,  FIG. 12(   b ) is a plane view, and  FIG. 12(   c ) is a side view. 
         FIG. 13  shows a yoke in the embodiment, wherein  FIG. 13(   a ) is a front view,  FIG. 13(   b ) is a plane view, and  FIG. 13(   c ) is a cross sectional view when viewed from the side. 
         FIG. 14  is a plane view showing a modification of the diaphragm assembly applicable to the present invention. 
         FIG. 15  is a plane view showing another modification of the diaphragm assembly applicable to the present invention. 
         FIG. 16  shows yet another modification of the diaphragm assembly applicable to the present invention, wherein  FIG. 16(   a ) is a plane view, and  FIG. 16(   b ) is a side view. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the embodiments of a ribbon microphone and a ribbon microphone unit according to the present invention will be described with reference to the accompanying drawings. In  FIG. 1 , reference numeral  1  denotes a microphone case. The microphone case  1  is cylindrical, and in the wall surface thereof, on the positions having a mutually front-rear relation, from the center portion to the tip portion, two rectangular window holes that are long in the longitudinal direction are formed side by side in the longitudinal direction of the microphone case  1 , respectively. A mesh  2  is stuck to these window holes. Sounds from the outside of the microphone case  1  pass through the mesh  2 , and reach a microphone unit disposed inside the microphone case  1 . In  FIG. 2 , reference numeral  10  denotes the microphone unit. The microphone unit  10  is installed in the center position inside the microphone case  1  and corresponding to the attached position of the mesh  2 . 
     As shown in  FIGS. 3(   a ), ( b ), and ( c ), the microphone unit  10  comprises a diaphragm assembly denoted by reference numeral  80 , and a magnetic-circuit assembly denoted by reference numeral  90 . The diaphragm assembly  80  comprises a substrate  20 , a spacer  40 , a ribbon diaphragm  60 , a metal fitting  50 , and a screw  55 , as shown in  FIG. 5  and  FIG. 7 . The substrate  20  is rectangular, and in the center thereof a rectangular window hole  24  that is long in the longitudinal direction is formed. The ribbon diaphragm  60  is disposed vertically across the window hole  24 . The width of the ribbon diaphragm  60  is smaller than the width of the window hole  24 . Near the both longitudinal ends of the substrate  20 , a rectangular circuit pattern  22  that is long in the width direction of the substrate  20  is formed. The both longitudinal ends of the ribbon diaphragm  60  span the circuit pattern  22 , and are secured by a securing unit comprising the spacer  40 , the metal fitting  50 , and the screw  55 . This securing unit will be described later. 
     In  FIG. 8 , at four corners on the plane of the substrate  20 , in order to secure the diaphragm assembly  80  to the magnetic-circuit assembly  90  by using a screw, there is formed a hole  28  for passing the screw therethrough. The diaphragm assembly  80  is installed in the state that the side in which the ribbon diaphragm  60  is provided in a tensioned state faces the yoke  70 . As shown in  FIG. 5(   b ), in the diaphragm assembly  80  when viewed from the side, the metal fitting  50 , the ribbon diaphragm  60 , and the spacer  40  project from the surface of the substrate  20 , and these members are fitted in the window hole  72  of the yoke  70 . The ribbon diaphragm  60  provided in a tensioned state in the diaphragm assembly  80  is positioned within a magnetic gap of the parallel magnetic flux formed by two magnets  30  that are fixedly adhered to the magnetic-circuit assembly  80 . As shown in  FIGS. 8(   a ), ( b ), in the substrate  20 , the circuit pattern  23  is formed also on the opposite side of the surface on which the circuit pattern  22  is formed. The circuit pattern  23  is cruciform, and the hole  26  passing through the circuit pattern  22  passes through the circuit pattern  23 , and a connection portion of an electrode is positioned in the circuit pattern  23 . The connection portion of the electrode is connected to an external circuit. 
       FIG. 10  shows the spacer. The spacer  40  is made up of an electrically conductive material, and is rectangular, and a hole  42  for passing a screw therethrough is formed on the both ends. The metal fitting  50  shown in  FIG. 11  is made up of an electrically conductive material, and is rectangular, and a hole  52  for passing a screw therethrough is formed on the both ends. The thickness of the metal fitting  50  is slightly thicker than the thickness of the spacer  40 . 
     The securing unit of the ribbon diaphragm  60  is described with reference to  FIG. 6  and  FIG. 7 . In the substrate  20 , at the both longitudinal ends of the circuit pattern  22 , the hole  26  is formed passing through the circuit pattern  22 . A screw  55  is inserted into these holes  26  from the under side in  FIG. 6 . The spacer  40  is disposed on the upper surface of the circuit pattern  22 , and the ribbon diaphragm  60  is disposed on the upper surface of the spacer  40 , and furthermore on the upper surface thereof the metal fitting  50  is disposed. The screw  55  is inserted into the hole  42  of the spacer  40  from the under side toward the upper side. The screw  55  is fastened into the screw hole  52  of the metal fitting  50 , whereby the ribbon diaphragm  60  and the spacer  40  are crimped and secured between the screw  55  and the metal fitting  50 . 
     Next, a specific configuration of the magnetic-circuit assembly  90  is described. As shown in  FIG. 4 , the magnetic-circuit assembly  90  comprises the yoke  70  and the magnet  30 . The yoke  70  is rectangular and has an appropriate thickness, wherein a rectangular window hole  72  that is long in the longitudinal direction is formed in the center, and the magnet  30  is fixedly adhered to the inner-wall surfaces, which are parallel to the longitudinal direction of the window hole  72  and face to each other, respectively. As shown in  FIG. 9 , the magnet  30  forms a slender rectangular column shape, and is magnetized in the width direction. A gap is formed between the opposing magnets  30 . The opposed face of each magnet  30  is disposed so as to have a different pole. The yoke  70  and a pair of magnets  30  constitute the magnetic circuit, and the gap between the magnets  30  forms the magnetic gap for the parallel magnetic flux. The magnet  30  is made up of a neodymium material, and generates a relatively strong magnetic force. 
     In  FIG. 4(   b ), a screw hole  74  is formed at four corners of the plane of the yoke  70 , respectively. Moreover, at the both longitudinal ends of the window hole  72  as well as at both width-directional ends of the yoke  70 , a screw hole  76  is formed at four places, respectively. As shown in  FIG. 13(   a ), on the front of the yoke  70 , a screw hole  78  is formed near both longitudinal ends. The screw hole  74  and the screw hole  78  are for securing the yoke  70  to the microphone case, and the screw hole  76  is for securing the later-described diaphragm assembly  80 . 
     In the embodiment of the microphone unit  10  shown in  FIG. 3 , two diaphragm assemblies  80  are used with respect to one magnetic-circuit assembly  90 . Two diaphragm assemblies  80  sandwich the magnetic-circuit assembly  90  from both sides, with the rear surfaces facing to each other. The yoke  70  constituting the magnetic-circuit assembly  90  is rectangular and has an appropriate thickness, as described above. The magnetic-circuit assembly  90  and the diaphragm assembly  80  have approximately the same dimension in the width direction, and the longitudinal dimension of the magnetic-circuit assembly  90  is longer than that of the diaphragm assembly  80 . The magnetic-circuit assembly  90  is secured to the microphone case  1  using the later-described fixing method. 
     The maintenance method of the ribbon diaphragm  60  is described. The diaphragm assembly  80  is detached from the microphone unit  10 , and then the screw  55  is loosened to detach the ribbon diaphragm  60 . The ribbon diaphragm to be replaced is prepared so as to be slightly longer than the length to be normally used. In the substrate  20 , the spacer  40  is disposed on the circuit pattern  22 , and the screw  55  is passed through the hole  26  of the circuit pattern and the hole  42  of the spacer  40  from the lower side of the substrate  20 . The ribbon diaphragm  60  is vertically across the window hole  24  along the longitudinal axis line of the substrate  20 , and is disposed on the upper surface of each spacer  40  at both longitudinal ends of the substrate  20 . The metal fitting  50  is loosely fastened from above the ribbon diaphragm  60 , and the tension is adjusted while pulling the remainder portion of the ribbon diaphragm  60  that extends from each spacer  40  to the horizontal direction, and then the metal fitting  50  is fastened and the remainder portion of the ribbon diaphragm  60  is cut off. Again, the diaphragm assembly  80  is attached to the magnetic-circuit assembly  90 . Moreover, if the replacement of the diaphragm assembly  80  itself is required, it is possible to detach the diaphragm assembly  80  from the microphone unit  10  and replace the whole diaphragm assembly  80 . 
       FIG. 14  shows a modification of the substrate constituting the diaphragm assembly. In  FIG. 14 , in a substrate  120 , there are formed a plurality of circular holes  122  along the center line in the longitudinal direction, in place of the window hole  24  of the substrate  20  in the embodiment described above. Such a configuration restricts the area of the holes at the opposing positions of the ribbon diaphragm  60 , and allows for a design to generate an acoustic resonance, and also allows the frequency characteristics to be extended to a high frequency region. Accordingly, a high-frequency sound wave also can be converted into an electric signal. In the illustrated example, a plurality of circular holes are assumed, but not limited to this form. Such shape, number, size, and position of the window holes of the substrate that generate an acoustic resonance may be employed. 
     If a magnet made of a neodymium material or the like having a strong magnetic force is used as the magnet  30 , a minute iron powder, foreign substance, or the like may adhere thereto and a desired acoustic characteristic as the ribbon microphone may be lost to cause a failure.  FIG. 15  and  FIG. 16  show examples of implementing countermeasures for avoiding the cause of the above-described failure. In  FIG. 15 , reference numeral  130  denotes a dustproof cloth. As illustrated, the mesh dustproof cloth  130  may be attached to the position to plug the window hole  24  of the substrate  20 . 
     An example shown in  FIG. 16  shows an example using an iron powder adsorbing magnet as the dust protection. As illustrated, an iron powder adsorbing magnet  140  having a slender rectangular column shape is fixedly adhered to the position to plug the window hole  24 , from the back side of the surface, in which the ribbon diaphragm  60  is provided in a tensioned manner, of the substrate  20 . The iron powder adsorbing magnet  140  is assumed to have a weak magnetic force relative to the magnet  30  of the magnetic-circuit assembly  90 , and includes opposing poles on both sides in the width direction so as not to change the parallel magnetic field within the magnetic gap as much as possible. The installation of the dustproof cloth  130  and the iron powder adsorbing magnet  140  makes it possible to prevent a minute iron powder or foreign substance from entering the inside of the microphone unit  10  from the outside of the ribbon microphone. 
     As described above, according to the ribbon microphone unit of the present invention, because the ribbon microphone unit comprises the diaphragm assembly and the magnetic-circuit assembly and each of them has a detachable configuration, the readjustment of the tension or the replacement of the diaphragm assembly or magnetic-circuit assembly can be easily carried out by a user side in maintaining the ribbon diaphragm. Moreover, when two diaphragm assemblies comprising the ribbon diaphragm are used, the sensibility of the microphone can be improved by connecting the respective diaphragm assemblies in series. Furthermore, according to the embodiments of the present invention, by attaching the dustproof cloth, the iron powder adsorbing magnet, or the like to the window hole of the substrate, it is possible to prevent a minute iron powder or foreign substance from entering the inside of the microphone unit. 
     If the ribbon microphone unit described above is incorporated into the microphone case to configure the ribbon microphone, the ribbon microphone that provides the effects as described above can be obtained.