JP4931510B2 - Ribbon microphone - Google Patents

Description

  The present invention relates to a ribbon type microphone, and particularly has a feature in a fixing structure of an end portion of a ribbon-like diaphragm.

  Ribbon-type microphones use a ribbon-like diaphragm as the diaphragm. The ribbon-shaped diaphragm is fixed by, for example, sandwiching both end portions in the length direction between fixed electrodes. A pair of permanent magnets are arranged opposite to each other in the width direction of the ribbon-shaped diaphragm so that the ribbon-shaped diaphragm is sandwiched in the width direction, and a ribbon-shaped electrode is disposed in a magnetic field formed by the permanent magnets. ing. Since the ribbon-shaped diaphragm vibrates in the magnetic field by receiving the sound wave, an electric signal corresponding to the sound wave is generated in the ribbon-shaped diaphragm, and the electric signal can be taken out from both ends of the ribbon-shaped diaphragm. As a material for the ribbon-shaped diaphragm, a material having good conductivity and low specific gravity is desirable, and an aluminum foil is generally used.

  Patent Document 1 is a patent publication relating to the applicant's patent application, and FIG. 4 shows an example of a ribbon microphone described in Patent Document 1. In FIG. 4, the code | symbol 10 shows a ribbon-shaped diaphragm. The ribbon-shaped diaphragm 10 is formed by forming a strip-like member made of, for example, aluminum foil into a corrugated shape, leaving both end portions 10a and 10b in the longitudinal direction. As a method for forming the ribbon-shaped diaphragm 10 in a wavy shape, for example, there is a method in which a pair of gears are meshed with a pair of gears interposed between a pair of gears and the pair of gears are rotated. As the pair of gears rotate, the band-shaped member is formed into a wave shape while being fed. The band-shaped member is formed in a shape in which the longitudinal section is wavy except for both end portions 10a and 10b in the longitudinal direction. As described above, the aluminum foil is characterized by good electrical conductivity and low specific gravity, and is suitable for performing the bending process described above, and is suitable as a material for a ribbon-shaped diaphragm of a ribbon microphone. In particular, it is desirable to use a pure aluminum material that does not contain other metal components.

  Flat end portions 10a and 10b of the ribbon-shaped diaphragm 10 which are not subjected to bending are fixed to the fixed electrodes 20 and 20, respectively. The fixed electrodes 20 and 20 include a pair of electrode members 20a and 20b, respectively. If one electrode member 20b is a member fixed to the microphone body side, both end portions 10a, 10b of the ribbon-shaped diaphragm 10 are placed on the electrode members 20b on both sides, and both end portions 10a of the ribbon-shaped diaphragm 10 are placed. , 10b, the other electrode member 20a is placed on the electrode member 20b. One electrode member 20a avoids a position corresponding to the ribbon-shaped diaphragm 10, and has round holes near the ends on both sides, and the other electrode member 20b has a screw hole at a position corresponding to the round hole of the electrode member 20a. have. A screw 22 as a fastening means is inserted into each round hole of each electrode member 20a, each screw 22 is screwed into each screw hole of the electrode member 20b, and both end portions of the ribbon-like diaphragm 10 are a pair of electrode members 20a, It is sandwiched and fixed by 20b.

  A pair of permanent magnets 30 and 30 formed in a quadrangular prism shape are disposed so as to sandwich the ribbon-shaped diaphragm 10 from the width direction and parallel to the longitudinal direction of the ribbon-shaped diaphragm 10. A magnetic field from one permanent magnet to the other permanent magnet is formed between the pair of permanent magnets 30, and the ribbon-like diaphragm 10 exists in this magnetic field. An appropriate gap is formed between the ribbon-shaped diaphragm 10 and the pair of permanent magnets 30 and 30. The ribbon-shaped diaphragm 10 vibrates according to the sound wave by receiving the sound wave. The ribbon-shaped diaphragm 10 generates an electrical signal corresponding to a sound wave by vibrating in a magnetic field. That is, the apparatus described above constitutes a ribbon microphone as an electroacoustic transducer. The electrical signal generated by the ribbon-shaped diaphragm 10 is taken out from the fixed electrodes 20 and 20 to the outside. Therefore, the pair of electrode members 20a and 20b constituting the fixed electrodes 20 and 20 are made of a conductive material and are generally made of a copper alloy in consideration of workability.

  Gold vapor deposition films may be formed on both the front and back surfaces of the ribbon-shaped diaphragm 10 made of aluminum foil, including both end portions 10a and 10b. It is desirable that the gold vapor deposition film has a film thickness of 500 angstroms (50 nm) or more and the mass added to the ribbon-like diaphragm 10 is within 10%. Ribbon-shaped diaphragm 10 can prevent oxidation of the aluminum foil and reduce sensitivity change by forming a gold vapor deposition film.

JP 2005-252440 A

The present invention is a further improvement of the ribbon microphone described above.
Ribbon-shaped diaphragms are generally made of a material having a very small conductive resistance, such as aluminum foil. Further, since the ribbon microphone has a low signal level, the signal level taken out via the electrode member is increased by a step-up transformer to obtain a microphone output. The direct current resistance of the ribbon diaphragm is about 0.1 to 0.2Ω, and the step-up transformer has, for example, a primary resistance of 0.2Ω and a secondary resistance of about 600Ω. As described above, since the conductive resistance of the ribbon-shaped diaphragm is small, even if there is an electrical resistance of several tenths of Ω in the electrical path from the ribbon-shaped diaphragm to the step-up transformer, the sensitivity is decreased, the output impedance is increased, etc. A problem occurs. For example, if the resistance of the ribbon-shaped diaphragm is 0.1Ω, but the connection resistance is 0.1Ω, the sensitivity of the microphone decreases, and the output impedance increases according to the transformation ratio of the step-up transformer. There is a problem that. Therefore, it is necessary to make the DC resistance of the portion connecting the ribbon-shaped diaphragm and the step-up transformer as small as possible.

  In order to reduce the DC resistance of the portion connecting the ribbon-shaped diaphragm and the step-up transformer, in the conventional example shown in FIG. 4, it is only necessary to increase the pressure-bonding force between the pair of electrode members 20a and 20b. The tightening force should be increased.

  However, a gap corresponding to the thickness of the ribbon-shaped diaphragm 10 is generated between both ends in the length direction of the pair of electrode members 20a and 20b. When this portion is strongly tightened by the screw 22, the pair of electrodes Both or one of the members 20a and 20b bend like a bow, the stress on the central portion in the width direction of the ribbon-shaped diaphragm 10 is reduced, and the connection resistance is increased.

  In order to solve this problem, a device has been devised in which one of the pair of electrode members 20a and 20b is deformed in advance in a direction opposite to the direction in which it is bent by tightening the screw 22. However, the degree to which the electrode member is deformed depends on the experience and intuition of the person involved in manufacturing, and there is a difficulty in inferior in productivity.

  In any case, the contact portion between the ribbon-shaped diaphragm and the electrode member in the conventional ribbon microphone is a point contact at several points, and skill is required to stabilize the connection resistance without variation.

  In addition, since the pair of electrode members 20a and 20b that fix both ends of the ribbon-shaped diaphragm 10 are fastened with the screws 22, a slight gap is required between the round hole of the one electrode member 20a and the screw 22. . The other electrode member 20b is fixed to the circuit board fixed in the microphone case by an appropriate means such as adhesion, and the electrode member 20a is fastened to the electrode member 20b with a screw 22. However, at the moment when the screw 22 hits the electrode member 20 a and is fixed to the other electrode member 20 b, a rotational force is applied to the electrode member 20 a, and the electrode member corresponds to the gap between the round hole of the electrode member 20 a and the screw 22. 20a is displaced. Although the amount of displacement is very small, the ribbon-shaped diaphragm 10 is deformed so as to be twisted because the ribbon-shaped diaphragm 10 is displaced so that the end of the ribbon-shaped diaphragm 10 extending in a strip shape is twisted. If the ribbon-like diaphragm 10 is deformed in this manner, the response of the ribbon-like diaphragm 10 with respect to sound waves is reduced, which causes a reduction in performance as a microphone.

  Thus, it is necessary to carefully tighten the electrode member 20a with the screw 22. When fixing the electrode member 20a to the other electrode member 20b, while holding the electrode member 20a with tweezers or the like, and tightening the two screws 22 little by little alternately, the ribbon-like diaphragm 10 is not twisted. We are working carefully.

  The present invention eliminates the problems of the prior art as described above, that is, can reduce the connection resistance of the fixing portion between the ribbon-shaped diaphragm and the electrode, and stably maintain the conductivity of the fixing portion. Another object of the present invention is to provide a ribbon microphone that can prevent torsional stress from being transmitted to the ribbon-shaped diaphragm by tightening the fixing member with a screw, and can avoid deformation of the ribbon-shaped diaphragm.

The ribbon microphone according to the present invention includes a ribbon-shaped diaphragm disposed in a magnetic field, a fixing means for fixing both ends of the ribbon-shaped diaphragm, and a permanent magnet for forming the magnetic field, and the fixing The means includes a pair of fixing members that sandwich the end portions of the ribbon-shaped diaphragm at both ends of the ribbon-shaped diaphragm, and a fastening member that fastens the pair of fixing members to each other. The first fixing member is fixed, and the second fixing member is fastened to the first fixing member by a fastening member, and a conductive cloth is interposed between the second fixing member and the ribbon-shaped diaphragm. the conductive cloth obtained by forming a non-woven cloth by entangled fine wire conductivity, and most important, characterized in that it comprises an elastic force covers the ends of the ribbon-shaped diaphragm.

Nonwoven conductive cloth is pressurized in contact with the fixing member and the ribbon-shaped diaphragm at multiple points of the surface, it is possible to obtain a stable conductivity, the fixing member and the conductive cloth ribbon-shaped vibrating It acts to reduce the contact resistance with the plate, and the resistance of the connecting portion can be lowered.
In addition, when a pair of fixing members are fastened with a fastening member such as a screw to pinch and fix the end of the ribbon-like diaphragm, the twisting stress such as a screw is not directly applied to the ribbon-like diaphragm, and the screw or the like even torsional stress occurs, since only shift between the fixed member and the conductive cloth, it is possible to prevent deformation of the ribbon-shaped diaphragm. Therefore, the fixing operation of the ribbon-shaped diaphragm can be performed without requiring skill.

  Embodiments of a ribbon microphone according to the present invention will be described below with reference to FIGS. 1 to 3 show a fixing structure on one end side of the ribbon-shaped diaphragm, and the fixing structure on the other end side of the ribbon-shaped diaphragm is similarly configured.

  1-3, the code | symbol 1 shows a ribbon-shaped diaphragm. The ribbon-shaped diaphragm 1 is obtained by bending a strip-like aluminum foil made of, for example, a pure aluminum material into a corrugated shape leaving both ends in the longitudinal direction, similarly to the ribbon-shaped diaphragm in the conventional example shown in FIG. It is. As a method for forming the ribbon-shaped diaphragm 1 in a corrugated shape, an arbitrary method may be selected and adopted from known methods. Aluminum foil is characterized by good electrical conductivity and low specific gravity, and is suitable for bending.

  Both flat ends of the ribbon-shaped diaphragm 1 that are not subjected to bending are fixed by a fixing means. 1 to 3 show only one end side forming the flat surface of the ribbon-like diaphragm 1 and only one fixing means 8 for fixing the one end side 1a. The fixing means 8 includes a pair of fixing members 3 and 5. When one fixing member 3 is a first fixing member, the first fixing member 3 is bonded to the back surface side (the lower surface side in FIGS. 2 and 3) of the circuit board 2 fixed to the microphone body side. These are fixed by appropriate fixing means. The first fixing member 3 is a quadrangular prism-like member, and is arranged in the longitudinal direction near one side edge of the circuit board 2 and in parallel with this one side edge. The material of the first fixing member 3 is made of a conductive material such as a copper alloy.

  On the front surface side of the circuit board 2 (upper surface side in FIGS. 2 and 3), a circuit pattern for drawing out at least the audio signal generated by the ribbon-shaped diaphragm 1 is formed. On the surface side of the circuit board 2, one end portion 1 a of the ribbon-like diaphragm 1 is placed on the circuit pattern so as to cross the longitudinal direction of the first fixing member 3 at a right angle. . A conductive cloth 4 is placed on the ribbon-shaped diaphragm 1. The conductive cloth 4 is woven into a cloth shape by entwining thin conductive wires, or is formed into a non-woven cloth shape, and has an elastic force by having a certain thickness. The conductive cloth 4 has substantially the same shape as the planar shape of the first fixing member 3, and is opposed to the upper surface of the first fixing member 3 with the circuit board 2 and one end 1 a of the ribbon-like diaphragm 1 interposed therebetween. Has been placed. Therefore, the conductive cloth 4 has a length sufficient to cross the one end 1a of the ribbon-shaped diaphragm 1 in the width direction, and covers the one end 1a of the ribbon-shaped diaphragm 1 in the width direction.

  A second fixing member 5 constituting the fixing means 8 is placed on the conductive cloth 4. The second fixing member 5 is formed in substantially the same rectangular column shape as the first fixing member 3, and is placed on the conductive cloth 4 in the same direction as the first fixing member 3 in parallel with the first fixing member 3. Yes. The second fixing member 5 has round holes near the ends on both sides in the longitudinal direction, avoiding the position corresponding to the ribbon-shaped diaphragm 1, and the conductive cloth 4 and the circuit board 2 also have holes at positions corresponding to the round holes. The first fixing member 3 has a screw hole at a position corresponding to the round hole of the second fixing member 5. Screws 6 as fastening means are inserted into the respective round holes of the second fixing member 5, and the screws 6 penetrating through the holes of the conductive cloth 4 and the circuit board 2 are screwed into the screw holes of the first fixing member 3. The first fixing member 3 and the second fixing member 5 are fastened with screws 6 with the conductive cloth 4, the circuit board 2, and one end 1 a of the ribbon-shaped diaphragm 1 sandwiched therebetween. By doing so, the flat end portion 1a of the ribbon-shaped diaphragm 1 has the conductive cloth 4 interposed between the one end portion 1a and the second fixing member 5, and the one end portion 1a and the first end portion 1a. In a state where the circuit board 2 is interposed between the fixing members, the pair of fixing members 3 and 5 are sandwiched and fixed. In the illustrated example, the pair of screws 6, 6 penetrates near both ends of the conductive cloth 4, but the length of the conductive cloth 4 may be shorter than the dimension between the pair of screws 6, 6. However, it is desirable that the length is sufficient to span the one end 1a of the ribbon-shaped diaphragm 1 in the width direction. The second fixing member 5 is also made of a conductive material such as a copper alloy.

  According to the embodiment configured as described above, when the second fixing member 5 is fastened to the first fixing member 3 with the screw 6, one end of the ribbon-shaped diaphragm 1 with the conductive cloth 4 interposed therebetween. 1 a is sandwiched between the first fixing member 3. In the case of the illustrated embodiment, more precisely, the circuit board 2, the one end 1 a of the ribbon-like diaphragm 1 and the conductive cloth 4 are arranged in this order between the first fixing member 3 and the second fixing member 5. It overlaps and is inserted. Since the conductive cloth 4 is composed of many conductive thin wires, the one end 1a of the ribbon-like diaphragm 1 and the conductive cloth 4, and the conductive cloth 4 and the second fixing member 5 contact each other at many points. The conductivity between these elements is stabilized, and the conductive cloth 4 functions to reduce the contact resistance with the member in contact therewith. In this way, stable conductivity can be easily realized. Further, when the screw 6 is tightened, the second fixing member 5 is rotated relative to the conductive cloth 4 so that the rotational force acting on the second fixing member 5 is applied to the one end 1 a of the ribbon-like diaphragm 1. There is no direct application, and no torsional stress is applied to the ribbon-shaped diaphragm 1. Therefore, the ribbon diaphragm 1 can be easily fixed to the fixing means 8 without requiring skill.

  1 to 3 show the one end 1a of the ribbon-shaped diaphragm 1 and its fixing structure, the other end of the ribbon-shaped diaphragm 1 is also configured in the same manner as the one end 1a, and the fixing means 8 is used. Therefore, the other end portion of the ribbon-shaped diaphragm 1 is fixed under the intervention of the conductive cloth similar to the conductive cloth 4. A pair of permanent magnets are arranged opposite to each other with the ribbon-shaped diaphragm 1 sandwiched in the width direction, and a magnetic field is formed between the opposed surfaces of the pair of permanent magnets, and the ribbon-shaped diaphragm 1 is formed in a wavy shape in the magnetic field. The main part is located. Therefore, when a sound wave hits the ribbon-shaped diaphragm 1, the ribbon-shaped diaphragm 1 vibrates according to the sound wave, and an electric signal is generated in the ribbon-shaped diaphragm 1 by crossing the magnetic flux. This electric signal is an audio signal corresponding to a sound wave, and this audio signal can be taken out through the circuit pattern of the circuit board 2 at both ends of the ribbon-shaped diaphragm 1 or from the second fixing member 5. It is like that.

The circuit board 2 is not essential, and when the circuit board 2 is not used, an electrical signal can be drawn out from the electrode member as in the conventional example shown in FIG.
As described in Patent Document 1, the ribbon-shaped diaphragm 1 is preferably composed mainly of an aluminum foil, and a gold vapor deposition film having a film pressure of 50 nm or more is formed on both surfaces thereof. By doing so, it is possible to prevent galvanic corrosion due to the joining of different metals.

  When fixing the both ends of the ribbon-shaped diaphragm 1 with the fixing means 8, the one end of the ribbon-shaped diaphragm 1 is temporarily fixed with the screw 6 of the fixing means 8 loosely tightened, and the ribbon-shaped diaphragm 1 is fixed. The resonance frequency is measured while pulling from one end, and when the resonance frequency reaches an appropriate value, the screw 6 is firmly tightened and fixed at that position. When performing such work, if there is no conductive cloth 4 having elastic force, the pressing force by the elastic force is not applied to one end portion of the ribbon-shaped diaphragm 1 in the temporarily fixed state, and the ribbon-shaped diaphragm 1 When the hand is released, the ribbon-shaped diaphragm 1 is contracted like a coil spring, and adjustment work is difficult. In that respect, according to the embodiment of the present invention, the ribbon-like diaphragm 1 is pressed by the elastic force of the conductive cloth 4 in the temporarily fixed state, and the ribbon-like diaphragm 1 is contracted even if the hand is released. Therefore, there is an advantage that adjustment work becomes easy.

  The above-described portion is a portion that should be called a microphone unit of a ribbon microphone, and a portion corresponding to the microphone unit is incorporated in a microphone case to become a final product of the microphone.

It is a top view which shows only the principal part of the ribbon type microphone concerning this invention. It is front sectional drawing of the principal part of a ribbon type microphone same as the above. It is principal part side surface sectional drawing of a ribbon type microphone same as the above. It is a disassembled perspective view which shows the example of the conventional ribbon type microphone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ribbon-shaped diaphragm 1a End part of ribbon-shaped diaphragm 2 Circuit board 3 1st fixing member 4 Conductive cloth 5 2nd fixing member 6 Screw 8 Fixing means

Claims (4)

A ribbon-like diaphragm arranged in a magnetic field;
Fixing means for fixing both ends of the ribbon-shaped diaphragm;
A permanent magnet for forming the magnetic field,
The fixing means includes a pair of fixing members that sandwich the end portions of the ribbon-shaped diaphragm at both ends of the ribbon-shaped diaphragm, and a fastening member that fastens the pair of fixing members to each other.
The pair of fixing members includes a first fixing member fixed to the microphone body side and a second fixing member fastened to the first fixing member by the fastening member,
A conductive cloth is interposed between the second fixing member and the ribbon diaphragm,
The conductive cloth obtained by forming a non-woven cloth by entangled fine wire of the conductive ribbon type microphone has an elastic force covers the ends of the ribbon-shaped diaphragm.   The ribbon microphone according to claim 1, wherein the first fixing member is fixed to a circuit board disposed in the microphone body. A ribbon-shaped diaphragm, a nonwoven fabric-like conductive cloth, and a second fixing member are stacked in this order on one surface side of the circuit board, and the first fixing member is fixed to the other surface side of the circuit board. the conductive cloth, ribbon microphone according to claim 2, wherein the screw of the fastening member through the circuit board is screwed to the first fixing member. 2. The ribbon microphone according to claim 1, wherein the fastening member is a screw that passes through one of the pair of fixing members and is screwed into the other fixing member.

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