JP6282009B2 - Ribbon microphone - Google Patents

Description

  The present invention relates to a ribbon microphone capable of avoiding the influence of foreign matters (iron powder, wire-like small pieces, etc.) entering from the outside.

The microphone unit in the ribbon type microphone has the ribbon type diaphragm arranged in a strong parallel magnetic field, vibrates in response to a sound wave, and obtains an audio signal proportional to the vibration speed of the ribbon type diaphragm. Configured as follows.
In this ribbon type microphone unit, in order to increase the sensitivity as a microphone, it is impossible in practice to make the length of the ribbon type diaphragm unlimited. Further, if the distance between the front and rear acoustic terminals is set large in order to increase the vibration speed of the ribbon diaphragm, the driving force of the ribbon diaphragm is lowered at high frequencies depending on the wavelength.
For this reason, it is necessary to improve the sensitivity as a microphone by a method of increasing the magnetic flux density applied to the ribbon diaphragm.

At present, since a neodymium magnet having a large energy product is relatively easily available, a ribbon microphone having high sensitivity can be obtained even with a relatively simple magnetic circuit.
However, since the magnetic flux density in the vicinity of the magnetic pole is high, ferromagnetic foreign matters such as iron powder and wire-like pieces are easily attracted to the magnetic gap portion. When such a foreign matter is adsorbed to the magnetic gap portion, the foreign matter extends along the direction of the magnetic flux, thereby hindering the vibration operation of the ribbon diaphragm.

In order to avoid the occurrence of such problems, a magnet for adsorbing magnetic foreign matter is arranged near the magnetic gap, and the magnetic foreign matter is prevented from entering near the ribbon diaphragm. The present applicant has already proposed a ribbon microphone (see Patent Document 1).
However, it is not preferable to specially arrange a magnet for attracting foreign matters from the viewpoint of manufacturing cost, and it also has problems such as an increase in size and weight of the microphone. Therefore, it is desirable to employ a means for preventing ferromagnetic foreign matter from entering the magnetic gap without incurring costs.

Therefore, the present applicant has a configuration in which an auxiliary yoke formed of a magnetic member is disposed so as to straddle the window frame of the yoke with respect to the yoke formed in a window frame shape supporting the magnet and the ribbon diaphragm. The ribbon type microphone is proposed (see Patent Document 2).
According to this, the auxiliary yoke functions as an acoustic terminal component that adjusts the frequency response characteristics of the microphone, a function as a magnetic path that bypasses the magnetic flux from the magnet, and a function that prevents the entry of ferromagnetic foreign matter into the magnetic gap. A ribbon microphone can be provided.

Japanese Patent No. 4753831 Japanese Patent No. 5103216

  5 and 6 show a microphone unit constituting the ribbon microphone disclosed in Patent Document 2 described above. That is, FIGS. 5A and 5B are a front view and a side view of the microphone unit, and FIG. 6 is an enlarged cross-sectional view of the microphone unit cut at the center in the longitudinal direction.

  5 and 6, reference numeral 2 denotes a yoke formed in a window frame shape, and reference numeral 3 denotes a pair of magnets arranged to face each other along the inner side surface of the window hole of the yoke. Reference numeral 8 denotes a pair of ribbon diaphragms arranged in a magnetic gap between opposing magnets. Reference numeral 7 is located on both sides of the yoke and the magnet, and supports the ribbon 8 at both ends in the longitudinal direction. The substrate to be shown is shown. Further, reference numeral 9 denotes a pair of acoustic terminal components (auxiliary yokes) made of a magnetic material arranged so as to straddle the window frame of the yoke.

  The numerical values described in FIGS. 5 and 6 indicate the leakage magnetic flux density (unit: Tesla) in each part of the microphone unit. It can be understood that the leakage magnetic flux density is relatively low between the ribbon diaphragm 8 and the acoustic terminal component 9 and the leakage magnetic flux density is high at both ends of the acoustic terminal component 9 in the width direction. This is because the substrate 7 is made of a non-magnetic material, so that the path of the magnetic circuit from both ends of the acoustic terminal component 9 toward the window frame-shaped yoke 2 supports the ribbon diaphragm 8. It is thought that it occurs because it is divided by.

  According to the microphone unit shown in FIG. 5 and FIG. 6, since the leakage magnetic flux is large in the vicinity of both end portions in the width direction of the acoustic terminal component, the foreign substance of the magnetic material is easily attracted to this vicinity. It moves into the magnetic gap in which the diaphragm is disposed, causing a problem of preventing the vibration of the ribbon diaphragm.

  The present invention has been made paying attention to the above-mentioned problems, and it is an object of the present invention to provide a ribbon microphone that can minimize the influence of foreign matter on a magnetic substance adsorbed by the action of leakage magnetic flux. To do.

  The ribbon microphone according to the present invention, which has been made to solve the above-mentioned problems, includes a yoke having a yoke window hole, a magnetic circuit assembly including a magnet disposed along an inner surface of the yoke window hole, A substrate having a substrate window hole communicating with the yoke window hole, and a diaphragm assembly including a ribbon diaphragm mounted in a magnetic gap formed by the magnet and mounted across the substrate window hole; An acoustic terminal component made of a magnetic material and straddling the yoke window hole to form a magnetic circuit and to cover the ribbon diaphragm at a distance from the ribbon diaphragm, and a width direction of the acoustic terminal component And an adhesive layer applied to the substrate side so as to be along the edge of the substrate.

In this case, it is possible to suitably employ a configuration in which magnets are disposed on both inner surfaces facing each other in the longitudinal direction of the yoke window hole, and the magnetic gap is formed between the pair of magnets.
In addition, a configuration in which a pair of ribbon diaphragms are arranged in parallel with each other in the magnetic gap can be suitably employed.

  Further, in a preferred embodiment, a pair of acoustic terminal components covering the front side and the back side of the ribbon diaphragm are respectively arranged on the front side and the back side of the yoke window hole. In this case, it is desirable that the acoustic terminal component has a flat plate-like main body portion in which a plurality of holes functioning as acoustic terminals are formed, and a plurality of leg portions bent with respect to the main body portion. The plurality of leg portions straddle the yoke window hole to form a magnetic circuit.

According to the ribbon type microphone having the above-described configuration, an acoustic terminal component that forms a magnetic circuit across the yoke window hole formed in the yoke is provided. And the adhesion layer is formed along the edge part of the width direction of an acoustic terminal component on the board | substrate side which opposes the edge part of the width direction of this acoustic terminal component.
Therefore, the foreign substance of the magnetic substance that is easily attracted to the end portion in the width direction of the acoustic terminal component having a particularly high leakage magnetic flux density is captured by the adhesive layer applied to the substrate side and fixed to the adhesive layer.
As a result, it is possible to solve the problem that the foreign substance of the magnetic material enters the magnetic gap and hinders the vibration operation of the ribbon diaphragm.

It is the front view which shows the magnetic circuit assembly of the ribbon type microphone which concerns on this invention, and the vertical sectional view in a center part. It is the front view and side view of an acoustic terminal component. It is the front view and side view of a microphone unit. It is an expanded sectional view in the center part of the longitudinal direction of a microphone unit. It is the front view and side view which showed the leakage magnetic flux density in the conventional ribbon type microphone unit. FIG. 6 is an enlarged cross-sectional view at the center in the longitudinal direction showing the leakage magnetic flux density of the microphone unit shown in FIG. 5.

Hereinafter, a ribbon microphone according to the present invention will be described based on an embodiment shown in the drawings. FIG. 1 shows a magnetic circuit structure 1, which is composed of a yoke 2 made of a metal material and a pair of long magnets 3.
The yoke 2 has a rectangular outer shape as viewed from the front and the back, and has an appropriate thickness, and a rectangular window hole (yoke window hole) 4 is formed in the length direction at the center thereof, Configured.

A pair of magnets 3 are fixed to the opposing inner side surfaces in the length direction of the yoke 2 configured in this window frame shape. Each of the magnets 3 is formed of, for example, a neodymium alloy and has an elongated prismatic shape, and the opposing surfaces of the magnets 3 are magnetized so as to have different magnetic poles. Therefore, the yoke 2 and the pair of magnets 3 constitute a magnetic circuit, and a magnetic gap is formed between the magnets 3 and 3 by a parallel magnetic flux.
Screw holes 5 are formed at the four corners of the yoke 2, respectively. The screw holes 5 at the four corners are used for attaching a rectangular substrate (described later) constituting a part of the diaphragm assembly along the longitudinal direction of the yoke 2.

The substrate constituting part of the diaphragm assembly attached to the front and back surfaces of the yoke 2 is denoted by reference numeral 7 in FIGS.
FIG. 3A shows the microphone unit as viewed from the front. However, when the microphone unit is viewed from the back, the configuration is the same as that in FIG. Is omitted.

A pair of substrates 7 made of a non-magnetic material are respectively attached to the front and back surfaces of the yoke 2. And the both ends of the ribbon type diaphragm 8 shown in FIG. 4 are attached to the both ends of each substrate 7 in the longitudinal direction through spacers (not shown).
The pair of ribbon diaphragms 8 is made of an aluminum material. And this ribbon type diaphragm 8 is mutually attached at a position slightly inserted into the magnetic gap from both outer sides of the magnet 3 as shown in FIG. It arrange | positions so that it may become a parallel state.
Therefore, according to this embodiment, the sensitivity as a microphone can be improved by adding the audio signals generated in the respective ribbon diaphragms 8.

  In addition, a window hole (substrate window hole) 7a having a length substantially equal to the magnetic gap by the magnet 3 is formed at the center of the substrate 7, and the substrate window hole 7a is formed with the magnetic gap at the center. It communicates with the yoke window hole 4.

FIG. 2 shows a single structure of the acoustic terminal component 9 attached to the outside of each of the yokes 2 via the respective substrates 7 on the front and back surfaces.
The acoustic terminal component 9 is made of a magnetic material, and has a rectangular main body portion 9a formed in a rectangular shape, a plurality of leg portions 9b bent at right angles to the main body portion 9a, A planar attachment portion 9c that is further bent toward the outer side at the distal end portion of the leg portion 9b is provided.

A large number of holes 9d functioning as acoustic terminals are formed in the flat body portion 9a. The plurality of leg portions 9b and the planar attachment portions 9c described above are formed at the target positions at both end portions in the width direction of the acoustic terminal component 9 at both end portions and the central portion in the length direction of the acoustic terminal component 9, respectively. Yes.
And the acoustic terminal component 9 is attached to the outer side of each board | substrate 7 arrange | positioned before and behind the yoke 2 using each planar attachment part 9c mentioned above, as shown in FIG.3 and FIG.4. In this case, a common screw hole may be provided in the planar mounting portion 9c and the yoke 2, and the mounting may be performed using a screw (not shown).

In this embodiment, means for applying the adhesive to the planar attachment portion 9c and attaching it to the substrate 7 is employed.
Accordingly, the acoustic terminal component 9 forms a magnetic circuit across the yoke window hole 4 and is disposed so as to cover the ribbon diaphragm 8 with a gap from the ribbon diaphragm 8.
Therefore, the acoustic terminal component 9 functions as an auxiliary yoke by forming one magnetic circuit, which increases the magnetic flux density of the magnetic gap and increases the sensitivity of the microphone unit.

  Further, the numerous holes 9d formed in the acoustic terminal component 9 function as acoustic terminals as described above, and contribute to adjusting the frequency response characteristics of the microphone unit. In this case, if necessary, the frequency response characteristics can be adjusted by covering a large number of holes 9d formed in the acoustic terminal component 9 with an acoustic resistor made of felt, mesh, or the like.

  On the other hand, in this embodiment, as shown in FIG. 3, an adhesive is applied to the substrate 7 side so as to be along the end in the width direction of the acoustic terminal component 9, and the adhesive layer 11 is formed. Yes. That is, as described with reference to FIGS. 5 and 6, the adhesive layer 11 is applied along a position where the leakage magnetic flux density is particularly high in the microphone unit. The adhesive layer 11 is also applied to the back side of the microphone unit. They are arranged at similar positions.

Therefore, the adhesive layer 11 effectively captures the magnetic foreign matter adsorbed by the leakage magnetic flux, and functions to fix the magnetic foreign matter to the adhesive layer 11.
As a result, the degree of intrusion of the magnetic foreign substance into the magnetic gap can be reduced, and the problem that the vibration operation of the ribbon diaphragm is hindered by the magnetic foreign substance can be largely solved.

  As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 11, for example, the trade name “Cemedine BBX strong pressure-sensitive adhesive” provided as a general commercial product from Cemedine Co., Ltd. (Shinagawa-ku, Tokyo) can be suitably used. It is also possible to use other materials that do not solidify over a long period of time and can retain adhesiveness.

The above-described microphone unit is housed in a case that protects the microphone unit, thereby forming a practical ribbon-type microphone. However, the microphone case is not shown.
According to the ribbon type microphone according to the present invention, the function as the ribbon type microphone can be sufficiently exhibited, and the effects described in the column of the effect of the invention described above can be enjoyed.

1 Magnetic Circuit Assembly 2 Yoke 3 Magnet 4 Window Hole (Yoke Window Hole)
5 Screw hole 7 Substrate 7a Window hole (Substrate window hole)
8 Ribbon type diaphragm 9 Acoustic terminal parts (auxiliary yoke)
9a Body part 9b Leg part 9c Planar mounting part 9d Acoustic terminal hole 11 Adhesive layer

Claims (5)

A magnetic circuit assembly including a yoke having a yoke window hole, and a magnet disposed along an inner surface of the yoke window hole;
A diaphragm assembly including a substrate having a substrate window hole communicating with the yoke window hole, and a ribbon diaphragm that is mounted across the substrate window hole and disposed in a magnetic gap formed by the magnet When,
An acoustic terminal component that is made of a magnetic material, forms a magnetic circuit across the yoke window hole, covers the ribbon diaphragm, and is spaced from the ribbon diaphragm;
An adhesive layer applied to the substrate side so as to be along an end in the width direction of the acoustic terminal component; and
A ribbon-type microphone characterized by comprising:   2. The ribbon microphone according to claim 1, wherein magnets are respectively disposed on both inner surfaces facing each other in the longitudinal direction of the yoke window hole, and the magnetic gap is formed between the pair of magnets. .   The ribbon microphone according to claim 1 or 2, wherein a pair of ribbon diaphragms are arranged in parallel with each other in the magnetic gap.   The pair of acoustic terminal components that respectively cover the front side and the back side of the ribbon diaphragm are disposed to face the front side and the back side of the yoke window hole, respectively. Item 4. The ribbon microphone according to any one of items 3 to 4.   The acoustic terminal component has a flat plate-like main body portion in which a plurality of holes functioning as acoustic terminals are formed, and a plurality of leg portions that are bent with respect to the main body portion. The ribbon microphone according to any one of claims 1 to 4, wherein a magnetic circuit is formed across the yoke window hole.

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