JP4972473B2 - Condenser microphone - Google Patents

Description

  The present invention relates to a gooseneck condenser microphone in which a microphone unit is supported by a flexible metal support pipe. More specifically, the microphone cord inserted into the support pipe has good shielding performance. The present invention relates to a technique for effectively preventing the generation of noise due to strong electromagnetic waves radiated from mobile phones and the like.

  Microphones can be used for various purposes such as music, studio, conference, and TV camera. Of these, for conferences, the direction of the microphone can be changed freely, and the gooseneck type does not make the microphone stand out. Many condenser microphones are used.

  A typical conventional example will be described with reference to FIG. 4. In a gooseneck condenser microphone, the microphone unit 10 is used by being attached to the upper end of a support pipe 20 made of a flexible pipe 21.

  A base 22 is integrally provided at the lower end of the support pipe 20, and the base 22 is fixed to a base such as a desk via a ring coupler 23. Connected. The ring coupler 23 is a screw type having a female screw, and the support pipe 20 is firmly connected to the base portion 24 via the base 22 by being screwed with a male screw (not shown) formed on the base portion 24 side.

  The microphone unit 10 is a small unit such as a tie pin type that is attached to the chest and used. In this example, the entire support pipe 20 is made of the flexible pipe 21, but a part of the support pipe 20 may include a telescopic pipe made of a metal nested pipe.

  Although not shown, the microphone unit 10 includes an acoustoelectric converter that forms a kind of capacitor in which a diaphragm and a fixed pole are opposed to each other, and converts a change in capacitance thereof into an electrical audio signal. An FET (field effect transistor) or the like as an impedance converter is provided.

  In addition to the microphone unit 10, the condenser microphone includes an audio output unit (power module unit) 40 including a low cut filter, a power feeding transformer, and an output connector (a connector defined in EIAJ RC5236).

  For example, in a handheld condenser microphone (hand microphone), the microphone unit 10 and the audio output unit 40 are housed in the same cylindrical microphone casing, but in the case of a gooseneck type, the microphone unit 10 and the audio output unit 40 are separated. And connected by a microphone cord 30 inserted into the support pipe 20.

  The audio output unit 40 itself includes a shield case 41. At the time of installation, the audio output unit 40 is accommodated in the base unit 24 using the base unit 24 as a shield case.

  Referring to FIG. 6, the microphone cord 30 includes a power line 31 that supplies power to the microphone unit 10, a signal line 32 that transmits an audio signal output from the impedance converter to the audio output unit 40, and A two-core shielded cable is used that includes a shielded wire 33 that electrostatically cuts off the power line 31 and the signal line 32 and is connected to ground. Although not shown, the shield covered wire 33 is connected to the unit housing (shield case) and the support pipe on the microphone unit 10 side.

  By the way, in a two-core shielded cable, since an audio signal is transmitted in an unbalanced manner, it is weak against external noise (external radio wave) and easily affected by the noise. Therefore, when a strong electromagnetic wave is applied to the microphone cord 30, a high-frequency current due to the electromagnetic wave may enter the microphone unit 10 or the audio output circuit 40 and generate noise.

  In particular, in the case of a gooseneck condenser microphone, the unit housing of the microphone unit 10 and the support pipe 20 are commonly grounded to the shield covered wire 33 on the upper end side of the microphone cord 30 as described above. May act as an antenna when receiving strong electromagnetic waves.

  As a result, high-frequency current due to electromagnetic waves received by the support pipe 20 enters the microphone unit 10 and is detected by the impedance converter, thereby generating noise.

  In recent years, mobile phones have been rapidly spread. However, when a mobile phone is used near a microphone, a considerably strong electromagnetic wave (for example, an electric field generated in the city by commercial radio waves within a range of several centimeters to several tens of centimeters). Therefore, countermeasures are urgently needed in the field of microphones.

  In order to solve this point, the present applicant has proposed the invention described in Patent Document 1, which will be described with reference to FIGS. FIG. 5 is an enlarged cross-sectional view showing a base portion attached to the lower end of the support pipe, and FIG. 6 is a perspective view showing a part of the microphone cord. Refer to FIG. 4 for the overall configuration.

  In the invention described in Patent Document 1, an outer sheath (sheath) 34 is cut off at least in a portion of the microphone cord 30 inserted into the support pipe 20 through the base 22 as shown in FIG. A shield covered wire exposed portion 33a is provided with the shield covered wire 33 exposed, and the shield covered wire exposed portion 33a is covered with a metal tube 35 such as a copper alloy.

  Then, as shown in FIG. 5, the metal tube 35 is positioned in the base 22, and the metal tube 35 is pressed against the inner surface of the base 22 with a press screw 22 a provided on the body portion of the base 22.

  Thereby, the microphone cord 30 is mechanically fixed to the base 22, and the lower end side of the support pipe 20 is electrically connected to the shield covered wire 33 of the microphone cord 30 through the base 22 and the metal pipe 35. It will be.

  According to this, in addition to being electrically connected to the shield covered wire 33 of the microphone cord 30 on the upper end side as described above, the support pipe 20 is also connected to the shield covered wire 33 of the microphone cord 30 on the lower end side. Is electrically connected to the shield-coated wire 33 at two locations on the upper end side and the lower end side, so that the shielding performance of the support pipe 20 is further improved and noise generation due to strong electromagnetic waves is reduced. Is done.

Japanese Patent Laying-Open No. 2005-323226 (FIG. 3)

  However, when assembling, first, the metal tube 35 is crimped on the shield covered wire exposed portion 33a, so that a special tool is necessary for the work, and if it is caulked more than necessary, the wire breaks. Sometimes. In such a case, the microphone cord 30 must be discarded.

  Further, when the metal tube 35 is fixed with the push screw 22a, the metal tube 35 may be deformed if it is tightened strongly. In the worst case, the insulation coating of the power line 31 and the signal line 32 may be crushed and a short circuit may occur. is there.

  On the other hand, when the tightening of the push screw 22a is weak, for example, when the microphone is installed, if the microphone cord 30 is pulled for some reason, the metal tube 35 slips against the push screw 22a, and the microphone cord 30 The tip side of the may come off.

  Furthermore, since the metal tube 35 is pressed against the base 22 from the lateral direction with the push screw 22a, the contact portion is a point contact or a line contact, and contact failure is likely to occur.

  Accordingly, an object of the present invention is to provide a microphone cord inserted into a support pipe in a gooseneck type condenser microphone with respect to a base provided at the lower end of the support pipe, both electrically and mechanically. There is also a sure connection.

  In order to solve the above-described problems, the present invention provides a microphone unit, a flexible metal support pipe that supports the microphone unit on the upper end side, and an upper end side. A cylindrical mouthpiece having a fitting hole into which the lower end of the support pipe is fitted and having a flange on the lower end side, and an audio output portion housed in a cylindrical shield case and fixed on a predetermined base A base part, and a lower end side of the base is connected to the base part via a ring coupler fitted to the flange, and the microphone unit and the audio output part are connected to the support pipe and the base. In a condenser microphone that is electrically connected via a microphone cord having a shield-coated wire that is inserted into the base, the base is located above the bottom of the fitting hole. An enlarged cylindrical portion having a diameter larger than the outer diameter of the microphone cord is formed at the lower end of the base, and the microphone cord is exposed to a shield covered wire formed by cutting off the outer skin at least in a portion inserted through the enlarged cylindrical portion. The diameter-enlarged cylindrical portion includes a conductive cloth disposed around the shield-covered wire exposed portion, and compresses the conductive cloth in the axial direction of the base so that the shield-covered wire exposed portion and the enlarged portion are provided. It is characterized in that a pressing means is provided in close contact with the inner surface of the diameter cylindrical portion.

  According to a preferred aspect of the present invention, as described in claim 2, the upper end of the conductive cloth is smaller in diameter than the enlarged cylindrical portion between the fitting hole and the enlarged cylindrical portion. A stopper wall is formed on which the abuts.

  According to a third aspect of the present invention, a cylindrical recess having a larger diameter and a female thread is formed coaxially on the lower end side of the expanded cylindrical portion, and the cylindrical recessed portion. Inside, a rubber cylinder disposed on the lower end side of the conductive cloth, and a lock ring as the pressing means screwed into the female screw and compressing the rubber cylinder and the conductive cloth in the axial direction of the base Is provided.

  Further, as described in claim 4, it is preferable that a metal washer is disposed between the conductive cloth and the rubber cylindrical body.

  According to the configuration of the first aspect, the conductive cloth is arranged around the shield-covered wire exposed portion in the base, and the conductive cloth is compressed in the axial direction of the base by the pressing means, so that the shield-covered wire exposed portion and the enlarged cylindrical portion are By making close contact with the inner surface, the shield-coated wire of the microphone cord and the base are electrically connected with a wide surface through the conductive cloth, and the shielding performance of the support pipe becomes almost perfect. Further, even in the assembling work, since the caulking work and the fixing work using the push screw are not required, the assembling workability is greatly improved.

  Further, as described in claim 2, by providing a stopper wall between the fitting hole and the diameter-enlarged cylindrical portion with a diameter smaller than that of the diameter-enlarged cylindrical portion and abutting the upper end of the conductive cloth, Can be reliably compressed.

  According to a third aspect of the present invention, a cylindrical recess having a larger diameter and a female thread is formed coaxially on the lower end side of the enlarged diameter cylindrical portion, and the lower end of the conductive cloth is formed in the cylindrical recess. In addition to the effect of claim 1, by providing a rubber cylinder disposed on the side, and a lock ring as a pressing means for screwing into the female screw and compressing the rubber cylinder and the conductive cloth in the axial direction of the base, The microphone cord can be securely fixed.

  Further, as described in claim 4, by disposing a metal washer between the conductive cloth and the rubber cylinder, it is possible to limit the degree of crushing when the conductive cloth and the rubber cylinder are compressed. .

  Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded view showing an insertion portion of a microphone cord with respect to a base, which is a main part of the present invention, FIG. 2 is a cross-sectional view showing a state where the microphone cord is inserted into the base, and FIG. It is sectional drawing which shows a state.

  Although only the main part of the present invention is shown in FIGS. 1 to 3, refer to FIG. 4 for the entire configuration including the microphone unit and the audio output unit. Components that may be the same as those of the conventional example described in FIGS. 4 to 6 are given the same reference numerals.

  As shown in FIG. 1, since the condenser microphone of the present invention is also a gooseneck type, a support pipe 20 including a flexible pipe 21 that supports the microphone unit 10 (see FIG. 4) at its upper end is used. A base 220 is integrally attached to the lower end of the base plate.

  Also in the present invention, a condenser microphone unit is used as the microphone unit 10. Further, the support pipe 20 may be a flexible pipe 21 as a whole, or an expansion / contraction pipe made of a metal nested pipe may be interposed at either the middle, upper end side, or lower end side. .

  The base 220 is a metal cylinder made of, for example, a copper alloy, and has a fitting hole 221 into which the lower end of the support pipe 20 is fitted on the upper end side, and a flange 222 having an enlarged diameter is formed on the lower end side. Has been.

  A ring coupler 23 is fitted to the flange 222, and the base 220 is connected to the base portion 24 by the ring coupler 23. In this example, the ring coupler 23 is a screw type having an internal thread, and the support pipe 20 is firmly connected to the base portion 24 via the base 220 by being screwed to a male screw (not shown) formed on the base portion 24 side. Is done. Another type of coupler may be used for the ring coupler 23.

  The base portion 24 is made of a metal cylindrical body, and is fixed to a base such as a desk (not shown) by a fixing means such as a screw. As described above with reference to FIG. 4, the audio output unit 40 is accommodated in the base unit 24 when the microphone is installed on the base.

  In order to electrically connect the microphone unit 10 supported by the support pipe 20 and the audio output unit 40, the microphone cord 30 is inserted into the support pipe 20 and the base 220.

  The microphone cord 30 is a two-core shielded cable having a power line 31, a signal line 32, a shield covered wire 33 and an outer cover 34, and the shield covered wire 33 on the upper end side of the support pipe 20 is a unit case and a support pipe of the microphone unit 10. 20 is electrically connected to

  In the base 220, an enlarged cylindrical portion 223 having a diameter larger than the outer diameter of the microphone cord 30 is formed from the bottom of the fitting hole 221 to the support pipe 20 to the lower end on the flange 222 side, and the fitting hole A stopper wall 224 that is larger in diameter than the outer diameter of the microphone cord 30 but smaller in diameter than the enlarged cylindrical portion 223 is formed between the 221 and the enlarged cylindrical portion 223.

  Further, according to this embodiment, the cylindrical concave portion 225 having a larger diameter than the enlarged diameter cylindrical portion 223 and having the female screw 226 is coaxially formed on the lower end side of the enlarged diameter cylindrical portion 223. In other words, the enlarged diameter cylindrical portion 223 includes a cylindrical recess 225 formed on the lower end side with a larger diameter.

  When the microphone cord 30 is inserted into the base 220, the microphone cord 30 is provided with a shield covered wire exposed portion 33a formed by cutting out the outer skin 34 at least at a portion inserted through the enlarged diameter cylindrical portion 223.

  In this example, the outer skin 34 is cut not only from the portion inserted through the enlarged diameter cylindrical portion 223 but also from the portion extending to the upper end of the microphone cord 30. This is to improve the electrical connection of. In the present invention, as described above, the shield covered wire exposed portion 33a may be provided at least in a portion inserted through the enlarged diameter cylindrical portion 223.

  Referring also to FIG. 2, when inserting the microphone cord 30 into the base 220, a conductive fabric 51 is accommodated in the enlarged diameter cylindrical portion 223. The conductive cloth 51 is preferably housed in the enlarged diameter cylindrical portion 223 in a cylindrical shape so as to be disposed around the shield covered wire exposed portion 33a.

  In this case, when the axial length of the cylindrical body made of the conductive cloth 51 is made longer than the axial length of the enlarged diameter cylindrical portion 223 and the upper end of the conductive cloth 51 is abutted against the stopper wall 224 as shown in FIG. The lower end protrudes from the enlarged diameter cylindrical portion 223.

  In addition, a rubber cylindrical body 53 is accommodated in the cylindrical recess 225. The axial length of the rubber cylindrical body 53 is also made longer than the axial length of the cylindrical concave section 225, and the lower end side of the rubber cylindrical body 53 A part of the projection protrudes from the cylindrical recess 225.

  The elasticity of the rubber cylindrical body 53 is harder than the elasticity of the conductive cloth 51. In addition, a metal washer 52 is preferably disposed between the conductive cloth 51 and the rubber cylindrical body 53.

  Finally, a lock ring 54 having a male screw 41 that engages with the female screw 226 of the cylindrical recess 225 is fitted into the cylindrical recess 225, the lock ring 54 is tightened, and the conductive cloth 51 and the rubber cylinder 53 are tightened as shown in FIG. Is compressed in the axial direction of the base 220.

  As a result, the conductive cloth 51 is first crushed and in close contact with the shield covered wire exposed portion 33a and the inner surface of the enlarged diameter cylindrical portion 223, so that the shielding performance of the support pipe 20 is further enhanced. In addition, since the metal washer 52 is disposed between the conductive cloth 51 and the rubber cylindrical body 53, the degree of crushing of the conductive cloth 51 and the rubber cylindrical body 53 is limited.

  Next, the rubber cylindrical body 53 is crushed, the inner diameter side is reduced, and the outer diameter side is expanded in the radial direction. Therefore, the microphone cord 30 is mechanically firmly fixed in the base 220, and the microphone cord 30 is caused to have a base portion for some reason. Even if it is pulled from the 24 side, the microphone cord 30 does not shift.

  Further, since the lock ring 54 can be easily disassembled by loosening the lock ring 54 and removing it from the cylindrical recess 225, it is excellent in terms of maintainability.

The exploded view which shows the insertion part of the microphone cord with respect to the nozzle | cap | die which is the principal part of this invention. Sectional drawing which shows the state which inserted the microphone cord in the nozzle | cap | die in this invention. Sectional drawing which shows the state which fixed the microphone cord in the nozzle | cap | die in this invention. The front view which shows the conventional gooseneck type condenser microphone. The expanded sectional view which shows the fixation structure of the microphone cord in the nozzle | cap | die in a prior art example. The perspective view which shows a part of microphone cord used for the said prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Microphone unit 20 Support pipe 21 Flexible pipe 220 Base 221 Fitting hole 222 Flange 223 Expanded cylindrical part 224 Stopper wall 225 Cylindrical recessed part 226 Female screw 23 Ring coupler 24 Base part 30 Microphone cord 33 Shield covered wire 33a Shield covered wire exposed part 40 Audio output part 51 Conductive cloth 52 Washer 53 Rubber cylinder 54 Lock ring

Claims (4)

A microphone unit, a flexible metal support pipe that supports the microphone unit on the upper end side, a fitting hole in which the lower end of the support pipe is fitted on the upper end side, and a flange on the lower end side A lower end of the base including a cylindrical base and a base part in which an audio output part is housed in a cylindrical shield case and fixed on a predetermined base, and is attached to the flange via a ring coupler In the condenser microphone, the side of which is connected to the base portion, and the microphone unit and the audio output portion are electrically connected via a microphone cord having a shield coated wire inserted into the support pipe and the base. ,
In the base, an enlarged cylindrical portion having a diameter larger than the outer diameter of the microphone cord is formed from the bottom of the fitting hole to the lower end of the base, and the microphone cord is inserted into at least the enlarged cylindrical portion. A shield-covered wire exposed portion formed by cutting off the outer skin at the portion to be formed, and in the enlarged-diameter cylindrical portion, a conductive cloth disposed around the shield-covered wire exposed portion, and the conductive cloth as a shaft of the base A condenser microphone, characterized in that it is provided with pressing means for compressing in a direction to bring it into close contact with the shield coated wire exposed portion and the inner surface of the enlarged diameter cylindrical portion.   The stopper wall with which the upper end of the said electrically conductive cloth contact | abuts between the said fitting hole and the said enlarged diameter cylindrical part with a smaller diameter than the said enlarged diameter cylindrical part is formed. The condenser microphone described in 1.   On the lower end side of the enlarged diameter cylindrical portion, a cylindrical recess having a larger diameter than that of the enlarged diameter cylindrical portion and having an internal thread is formed coaxially, and in the cylindrical recess, on the lower end side of the conductive cloth. 2. A rubber cylinder disposed, and a lock ring as the pressing means that is screwed into the female screw and compresses the rubber cylinder and the conductive cloth in the axial direction of the base. Or the condenser microphone of 2. The condenser microphone according to claim 3 , wherein a metal washer is disposed between the conductive cloth and the rubber cylindrical body.

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