JP4606175B2 - Dynamic microphone - Google Patents

Description

  The present invention relates to a dynamic microphone capable of ensuring a frequency response up to a low frequency and enhancing sensitivity.

  The dynamic microphone includes a magnetic circuit formed of a magnet, a yoke, and the like, a diaphragm, and a voice coil that is integrally attached to the diaphragm and disposed in a gap in the magnetic circuit. When the diaphragm vibrates according to the sound that reaches the microphone, the voice coil vibrates with this, and the voice coil vibrates while traversing the magnetic field formed in the gap, so that the voice coil converts the sound into an electrical signal and outputs it. Is done.

  An example of a conventional dynamic microphone unit having a general configuration is shown in FIG. In FIG. 2, a disc-shaped magnet (permanent magnet) 1 is fixed to the center of the inner bottom surface of a flat circular dish-shaped yoke 2 by an adhering means such as adhesion. The magnet 1 is magnetized in the thickness direction (vertical direction in FIG. 2). The thickness (height) dimension of the magnet 1 is the same as the height of the inner peripheral surface of the peripheral wall 21 of the yoke 2, and the upper end surface of the magnet 1 and the upper end surface of the peripheral wall 21 of the yoke 2 are on the same plane. The ring yoke 3 is fixed to the upper end surface of the peripheral wall 21 of the yoke 2 by a fixing means such as adhesion. A disc-shaped pole piece 4 is fixed to the upper end surface of the magnet 1 by a fixing means such as adhesion. The upper end surface of the pole piece 4 and the upper end surface of the ring yoke 3 are on the same plane. Between the inner peripheral surface of the ring yoke 3 and the outer peripheral surface of the pole piece 4, a gap 5 concentric with the ring yoke 3 and the pole piece 4 is formed with a constant width. The pole piece 4, the ring yoke 3, and the yoke 2 constitute a magnetic circuit through which the magnetic flux emitted from the magnet 1 passes. That is, the magnetic flux emitted from the magnet 1 passes through the pole piece 4, reaches the ring yoke 3 through the gap 5, and returns to the magnet 1 through the yoke 2. Therefore, a magnetic field is formed in the gap 5.

The aforementioned gap 5, across the magnetic field formed in the gap 5, the voice coil 7 thin conductive wire is wound in a cylindrical shape is disposed. The voice coil 7 is attached to a diaphragm 6 made of a film-like material. The configuration of the diaphragm 6 and the voice coil 7 will be described in more detail. The diaphragm 6 includes a center dome portion 61 and a sub dome portion 62 that elastically supports the center dome portion 61, and the boundary between the center dome portion 61 and the sub dome portion 62. In the vicinity, one end side of the voice coil 7 is fixed by means such as adhesion. The diaphragm 6 also has an adhesive part 63 having a constant width d on the entire outer periphery of the sub dome part 62, and the adhesive part 63 is adhered to the adhesive surface 32 formed on the ring yoke 3. The bonding surface 32 formed on the ring yoke 3 is formed in a step shape on the inner peripheral side of the peripheral wall 31 formed in the ring yoke 3 and at a position one step higher than the main body portion of the ring yoke 3. Therefore, the diaphragm 6 is supported in a state where the other portions except the bonding surface 63 are lifted from the ring yoke 3. Further, the voice coil 7 mechanically tightly coupled to the diaphragm 6 is located in the gap 5 as described above, and the inner peripheral surface of the ring yoke 3 constituting the gap 5 and the pole constituting the gap 5 The piece 4 is supported so as not to contact the outer peripheral surface of the piece 4.

  When the sound wave reaches the microphone, the vibration plate 6 vibrates according to the sound wave, and the voice coil 7 vibrates integrally with the vibration plate 6. The voice coil 7 cuts the magnetic flux in the gap 5 by the vibration of the voice coil 7, and an electrical signal according to the sound wave is generated in the voice coil 7. In this way, the sound wave is converted into an electric signal and output from the microphone.

  The reason why the diaphragm 6 has the center dome portion 61 is to give the voice coil 7 together with the diaphragm 6 with a predetermined rigidity. The reason why the diaphragm 6 has the sub dome portion 62 is that the entire diaphragm 6 is elastically supported and the diaphragm 6 is vibrated faithfully according to the sound wave.

Since the center dome portion 61 of the diaphragm 6 vibrates together with the voice coil 7, increasing the area of the center dome portion 61 can increase the sensitivity of the microphone. Since the control method of the unidirectional dynamic microphone is mainly mass control, it is possible to collect sound at a low frequency by lowering the resonance frequency in the low band of the diaphragm 6. To lower the resonance frequency in the low range,
(1) Make the voice coil 6 heavy.
(2) The elastic force of the sub dome part 62 is weakened by means of weakening the stiffness, for example.
There is a way. However, the method of increasing the weight of the voice coil 6 increases vibration noise when the microphone is held by hand, that is, handling noise, and is not suitable as a handheld microphone. On the other hand, as a method of weakening the elastic force of the sub dome portion 62, there are methods of reducing the thickness of this portion or increasing the radius of curvature of this portion. Further, when the area of the sub dome part 62 is reduced, it becomes difficult to support the center dome part 61 softly. Therefore, increasing the area of the sub dome part 62 is also one method.

  Usually, the outer peripheral edge portion of the diaphragm 6, that is, the bonding portion 63 is fixed by being planarly bonded to the yoke 2 or the like constituting the housing of the microphone unit as in the example shown in FIG. 2 (for example, Patent Document 1). , See Patent Document 2). The adhesive margin of the bonding portion 63 is a radial width d of the bonding portion 63 and is about 1 mm. Therefore, about 2 mm is secured in diameter. Incidentally, in the case of a microphone unit in which the diameter a at the thickness direction center of the voice coil 7 is 13 mm, the inner diameter b of the peripheral wall 21 of the yoke 2 is 24 mm, and the diameter c including the bonding portion 63 of the voice coil 6 is 27 mm. d is about 1 mm.

  From the above, in the case of a microphone unit having a large outer shape, it is not a problem to secure the radial width d of the bonding portion 63 of about 1 mm. However, in a relatively small-diameter microphone unit having an outer diameter of 20 mm or less, by securing a radial width d of the bonding portion 63 of about 1 mm, a dimension of 10% or more in diameter is used for bonding the outer peripheral edge of the diaphragm 6. Will be used. Along with this, there is a problem that the area of the center dome 61 of the diaphragm 6 is reduced, thereby reducing the sensitivity of the microphone. Also, if the area of the sub dome 62 is reduced in an attempt to increase the area of the center dome 61 as much as possible, the elastic force of the sub dome 62 that supports the center dome 61 increases (the spring becomes stiff: stiffness increases), and the bass This causes a problem that sound collection becomes difficult.

  Further, in the conventional configuration in which the outer peripheral edge portion of the diaphragm 6 is fixed by bonding, as shown in FIG. 2, the adhesive 65 protruding from the bonding surface 32 causes the outer periphery of the sub dome portion 62 of the diaphragm 6 and the ring yoke 3. This spreads and hardens on the inner peripheral surface following the adhesive surface 32, and the range in which the movement of the sub dome portion 62 is allowed is limited, making it difficult to move. From this point also, it becomes difficult to collect sound in the low frequency range. .

  As described above, in order to enable low-frequency sound collection in a small-diameter dynamic microphone unit, a device that can secure the effective area of the center dome part and sub-dome part of the diaphragm as much as possible is required. It is done.

Japanese Patent Laid-Open No. 10-336791 JP-A-5-207583

  The present invention has been made in order to solve the problems of the conventional dynamic microphone as described above. By devising the support structure of the diaphragm, the diaphragm can be used even with a small-diameter microphone. The objective is to provide a dynamic microphone that is easy to move when received, secures frequency response up to low frequencies, and can secure sufficient sensitivity by allowing sufficient area of the center dome. To do.

The present invention is a dynamic microphone having a diaphragm that vibrates in response to a sound wave, and a conversion unit that electrically acts on the diaphragm and converts the vibration into an electrical signal. It has a dome part and a sub dome part on the outer peripheral side thereof, and the outer peripheral edge part of the diaphragm is in line contact with the bonding surface of the support which forms a flat surface by extending the shape of the sub dome part in the cross section. Then, by applying an elastic adhesive along the line contact portion even after curing, the outer peripheral edge of the diaphragm is adhered to the adhesive surface forming the flat surface of the support , and the vibration The most important feature is that the outer peripheral edge of the plate is separated from the adhesive surface except for the portion in line contact with the adhesive surface .

The outer peripheral edge of the diaphragm is brought into line contact with the support, and the line contact part is fixed to the support with an adhesive, whereby the adhesive area of the diaphragm can be reduced. The area can be increased, and even a small-diameter microphone can ensure frequency response up to a low frequency range. In addition, since the adhesive area of the diaphragm can be reduced, the area of the center dome portion of the diaphragm can be increased, thereby increasing the sensitivity of the microphone.
If an adhesive that is elastic even after curing is used as the above-mentioned adhesive, movement of the diaphragm is allowed to some extent even in the bonded portion, and it becomes easy to ensure frequency response to a low frequency range.

An embodiment of a dynamic microphone according to the present invention will be described below with reference to FIG. In addition, the same code | symbol was attached | subjected to the same part as the structure of the prior art example shown in FIG.
In FIG. 1, a disc-shaped or low columnar magnet (permanent magnet) 1 is fixed to the center of the inner bottom surface of a flat circular dish-shaped yoke 2 by an adhering means such as adhesion. The magnet 1 is magnetized in the thickness direction (vertical direction in FIG. 1). The thickness (height) dimension of the magnet 1 is the same as the height of the inner peripheral surface of the peripheral wall 21 of the yoke 2, and the upper end surface of the magnet 1 and the upper end surface of the peripheral wall 21 of the yoke 2 are on the same plane. The ring yoke 3 is fixed to the upper end surface of the peripheral wall 21 of the yoke 2 by a fixing means such as adhesion. A disc-shaped pole piece 4 is fixed to the upper end surface of the magnet 1 by a fixing means such as adhesion. The upper end surface of the pole piece 4 and the upper end surface of the ring yoke 3 are on the same plane. A gap 5 concentric with the ring yoke 3 and the pole piece 4 is formed between the inner peripheral surface of the ring yoke 3 and the outer peripheral surface of the pole piece 4 with a constant width. The pole piece 4, the ring yoke 3, and the yoke 2 constitute a magnetic circuit through which the magnetic flux emitted from the magnet 1 passes. That is, the magnetic flux emitted from the magnet 1 passes through the pole piece 4, reaches the ring yoke 3 through the gap 5, and returns to the magnet 1 through the yoke 2. Therefore, a magnetic field is formed in the gap 5.

  The gap 5 is provided with a voice coil 7 in which a thin conductive wire is wound around a cylindrical shape across a magnetic field formed in the gap 5. The voice coil 7 is attached to a diaphragm 6 made of a film-like material. The configuration of the diaphragm 6 and the voice coil 7 will be described in more detail. The diaphragm 6 is formed in a ring shape along the outer periphery integrally with the center dome portion 61 and the center dome portion 61 in order to elastically support the same. The sub dome portion 62 is provided. The sub dome portion 62 has a dome shape in cross section. One end of the voice coil 7 is fixed to the vicinity of the boundary between the center dome portion 61 and the sub dome portion 62 by means such as adhesion.

The ring yoke 3 also functions as a support for the diaphragm 6. The ring yoke 3 is stepped on the inner peripheral side of the peripheral wall 31 formed on the ring yoke 3 and is positioned one step higher than the main body portion of the ring yoke 3. The outer peripheral edge of the diaphragm 6 is bonded to the entire surface of the bonding surface 33 formed. However, unlike the conventional example shown in FIG. 2, the bonding portion 64 at the outer peripheral edge of the diaphragm 6 has a shape in which the dome shape in the cross section of the sub dome portion 62 is extended, and thus the bonding surface forming a flat surface. 33 is in line contact with a circular arc in the circumferential direction (it looks like point contact in the cross section shown in FIG. 1). An adhesive 66 is applied along the line contact portion , and the diaphragm 6 is fixed to the ring yoke 3 as a support in the range of the width f of the adhesive surface 33. The outer peripheral edge portion of the diaphragm 6 is separated from the adhesive surface 33 and the inner peripheral surface of the peripheral wall 31 of the ring yoke 3 except for the portion in line contact with the adhesive surface 33, and this separated portion is separated from the adhesive surface 33. The adhesive 66 is cured within the range of the width f, and the diaphragm 6 is fixed. Therefore, the adhesive 66 covers the diaphragm 6 from the upper and lower surfaces of the outer peripheral edge portion and is fixed to the ring yoke 3. In this way, the diaphragm 6 is supported in a state where the other portions except the bonding surface 33 are floated from the ring yoke 3 and the pole piece 4. Further, the voice coil 7 mechanically tightly coupled to the diaphragm 6 is located in the gap 5 as described above, and the inner peripheral surface of the ring yoke 3 constituting the gap 5 and the pole constituting the gap 5 The piece 4 is supported so as not to contact the outer peripheral surface of the piece 4.

  As the adhesive 66, an adhesive that is elastic even after curing is selected and used. As an example of an adhesive that remains elastic after curing, there is a one-component RTV rubber KE347 manufactured by Shin-Etsu Chemical Co., Ltd., which was used in the examples of the present invention.

  When the sound wave reaches the microphone, the vibration plate 6 vibrates according to the sound wave, and the voice coil 7 vibrates integrally with the vibration plate 6. The voice coil 7 cuts the magnetic flux in the gap 5 by the vibration of the voice coil 7, and an electrical signal according to the sound wave is generated in the voice coil 7. In this way, the sound wave is converted into an electric signal and output from the microphone. The voice coil 7 and the magnetic circuit constitute a converter that electrically acts on the diaphragm 6 that vibrates in response to sound waves and converts the vibration into an electrical signal.

In the embodiment shown in FIG. 1, a cover 8 that functions as an equalizer is fitted to the tip of the peripheral wall 31 of the ring yoke 3. The cover 8 covers the diaphragm 6 and keeps a gap with the diaphragm 6. An appropriate number of holes 81 for introducing sound waves into the diaphragm 6 are formed in the cover 8.
The portion described above is precisely a microphone unit. This microphone unit is mounted on a microphone case, and other parts are assembled to the microphone case, wiring with a connector, and the like are completed.

  According to the embodiment described above, the diaphragm 6 has the adhesive portion 64 at the outer peripheral edge in line contact with the adhesive surface 33 of the ring yoke 3 as a support, and the line contact portion is Since it is fixed to the ring yoke 3, the width f of the bonding portion 64 can be reduced as compared with the conventional example in surface contact with the support. Accordingly, the dimension g in the radial direction of the sub dome portion 62 of the diaphragm 6 can be increased to widen the area thereof, so that the diaphragm 6 can move easily when receiving a sound wave, and a dynamic microphone having a small diameter is obtained. Even so, there is an advantage that the frequency response to the low range is ensured and the sound can be easily collected to the low range. Further, since the width f of the bonding portion 64 can be reduced, the area of the center dome portion 61 can be sufficiently secured, and even if the dynamic microphone has a small diameter, the sensitivity can be ensured. it can.

  In addition to the above effect, the adhesive 66 is separated from the adhesive surface 33 and the inner peripheral surface of the peripheral wall 31 of the ring yoke 3 except for the outer peripheral edge portion of the diaphragm 6 that is in line contact with the adhesive surface 33. Since the adhesive 66 penetrates and cures in the separated portions to fix the vibration plate 6, the adhesive 66 does not protrude beyond the bonding surface 33, and the vibration plate 6 can be effectively moved by the hardening of the adhesive. The problem that the part is restricted can be solved. As a result, the frequency response and sensitivity up to low frequencies can be improved.

  By making the adhesive 66 an elastic adhesive even after curing, the diaphragm 6 can easily move even after the adhesive 66 is cured. From this point, the frequency response to the low frequency range and Sensitivity can be increased.

It is a longitudinal cross-sectional view which shows the Example of the dynamic microphone concerning this invention. It is a longitudinal cross-sectional view which shows the example of the conventional dynamic microphone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnet 2 Yoke 3 Ring yoke 4 Pole piece 5 Gap 6 Diaphragm 7 Voice coil 33 Adhesive surface 61 Center dome part 62 Sub dome part 64 Adhesive part 66 Adhesive

Claims (4)

A dynamic microphone having a diaphragm that vibrates in response to a sound wave, and a converter that electrically acts on the diaphragm and converts the vibration into an electrical signal;
The diaphragm has a center dome portion and a sub dome portion on the outer peripheral side thereof,
The outer peripheral edge of the diaphragm has a shape in which the shape of the sub dome portion in the cross section is extended, and comes into line contact with the bonding surface of the support that forms a flat surface, and is elastic after curing along the line contact portion. By applying a suitable adhesive, the outer peripheral edge of the diaphragm is adhered to the adhesive surface forming the flat surface of the support, and the outer peripheral edge of the diaphragm is in line contact with the adhesive surface. A dynamic microphone characterized in that a part other than the part is separated from the adhesive surface .   The dynamic microphone according to claim 1, wherein a voice coil constituting the conversion portion is fixed to a boundary portion between the center dome portion and the sub dome portion of the diaphragm.   The dynamic microphone according to claim 2, wherein the voice coil is located in a gap of a magnetic circuit that constitutes the conversion unit together with the voice coil. The support body is composed of a ring-shaped yoke that forms a part of a magnetic circuit constituting the conversion section, and the outer peripheral edge portion of the diaphragm is in line contact with a step portion formed on the inner peripheral side of the yoke. The dynamic microphone according to 1 , 2 or 3 .

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