JPS6029279B2 - dynamic microphone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic microphone in which a diaphragm is coupled to a voice coil disposed in a gap in a magnetic circuit, and in particular, the frequency characteristics and sound quality of the microphone itself can be adjusted by using a capacitor. It is something that can be done.

Dynamic microphones, also known as moving coil microphones, are used for a wide variety of purposes.

Therefore, microphones with various frequency characteristics and sound quality are required, but these frequency characteristics and sound quality are largely determined by the internal structure of the microphone.
It is necessary to individually manufacture microphones with internal structures that correspond to desired frequency characteristics and sound quality. Therefore, separate manufacturing molds and the like are required for each, which not only increases cost but also increases the number of types of parts, making manufacturing cumbersome. On the other hand, it is desired to be able to adjust the frequency characteristics and sound quality of one type of microphone during assembly and use.

The present invention has been made in view of the above-mentioned conventional circumstances, and it is possible to obtain the desired frequency characteristics and sound quality with simple operations during assembly and when using a microphone, and it is also easy to adjust. The purpose is to provide a dynamic microphone that can be mass-produced with high efficiency.

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view showing a dynamic microphone according to a first embodiment of the present invention.

In FIG. 1, a magnetic circuit 2 is composed of a magnet 3, a yoke 4, and a center ball 5. The yoke 4 has a cylindrical shape with a bottom, and an inertance ring 6 is disposed inside the yoke 4. A voice coil 8 is disposed in the air gap 7 between the yoke 4 and the center ball 5 of the magnetic circuit 2, and this voice coil 8 is connected to a diaphragm (
diaphragm) 9. This diaphragm 9 has a central dome part and a peripheral edge part, and the outermost peripheral end of the edge part is supported by the diaphragm ring 1. In front of this diaphragm 9 (upper part in the figure), an equalizer cap 11 for Takagi compensation is provided. 12 is installed. Furthermore, a wind screen 13 may be provided outside these to wrap around the neck of the microphone. Next, behind the diaphragm 9 (lower in the figure), a first volume chamber 21 and a second volume chamber 22 are formed.

Here, the main part of the first volume chamber 21 is a cylinder 23 connected to the bottom side of the yoke 4 of the magnetic circuit 2;
is connected to the inside of the magnetic circuit 2 via a through hole 14 provided on the bottom surface of the yoke 4 and a resistor 15, and the diaphragm 9
The first volume chamber 21 extends from the back surface of the cylinder to the cylindrical body 23 . The second volume chamber 22 is further rearward of this first volume chamber 21 (
It may be formed in the lower part of the figure. Although the cylindrical body serving as the second volume chamber 22 uses the grip 24 of the microphone, a cylindrical body for the second volume chamber may be separately provided inside the grip 24. These first and second volume chambers 21, 2
2 is passed through an inertance tube 25 having a predetermined vibrating thread equivalent mass, that is, an equivalent mass mP for obtaining a desired low-frequency resonance frequency fo.

That is, one end of the inertance tube 25 is connected to the hole 27 provided in the rear baffle plate 26 of the first volume chamber 21, and the hole 28 provided at the other end of the inertance tube 25 is connected to the hole 27 provided in the rear baffle plate 26 of the first volume chamber 21. It opens into the volume chamber 22. The inertance tube 25 includes a plurality of inertance tubes, for example, two in this embodiment.
holes 31 and 32 are respectively formed at predetermined positions,
The second volume chamber 22 is closed.

Resistors 41 and 42 are attached to the sides of these holes 31 and 32 facing the second volume chamber 22, respectively, as necessary. These resistors 41 and 42 are made of a breathable material such as Babylon paper, silk, felt, glass wool, or the like. The equivalent circuit in the bass castle of such an acoustic vibration string is shown in FIG.

In FIG. 2, a vibration source 16 equivalently represents the vibration of the diaphragm 9 caused by sound waves, and an equivalent mass mo, compliance Co, and equivalent resistance connected to this vibration source 16. R equivalently represents the vibration string (for example, the equivalent mass of the diaphragm 9, the equivalent mass of the air passage of the inertance ring 6, etc.) in the vicinity of the magnetic circuit 2 in FIG. Compliance C, indicates the compliance of the first volume chamber 21. The inertance tube 25 and the second volume chamber 22 have an equivalent mass mP,,mP
2, mP3, equivalent resistance rP, , rP2, rP3, and conformance C2, etc., and these values are expressed by the inertance tube 25.
It is determined by the positions and diameters of the holes 31 and 32, the air permeability of the resistors 41 and 42, the volume of the second volume chamber 22, and the like. Therefore, during assembly, the frequency characteristics can be changed by replacing the inertance tube 25, but the holes 31 and 32 can be selectively opened and closed using separate sections, and the materials of the resistors 41 and 42 can be changed as appropriate. This can be done by extremely simple operations such as selection.

This allows the grip to be removed to expose the inertance tube 25 and the hole 31 not only during assembly but also during use.
, 32 can be selectively opened and closed to obtain desired frequency characteristics and sound quality. Furthermore, a mechanism may be provided that allows the holes 31 and 32 to be opened and closed by an external switch operation or the like. Next, FIG. 3 is a schematic sectional view showing a second embodiment of the present invention, and FIG. 4 is a sectional view taken along the line W--W in FIG. 3.

In this second embodiment, the bottom plate 52 of the first volume chamber 51
A coaxial cylindrical inner cylinder 53 and an outer cylinder 54 are connected toward the rear (downward in the figure), and the inside of the inner cylinder 53 is connected to a second volume chamber 55, and the inner cylinder 53 and outer cylinder An inertance tube 56 is provided between the inertance tube 54 and the inertance tube 54 . The bottom plate 52 of the first volume chamber 51 is provided with holes 57 that are formed radially from the outer periphery of the inner cylindrical body 53 as shown in FIG. The chamber 51 and the inertance tube 56 are communicated. Here, FIG. 3 is a cross section taken along line m--m in FIG. 4. Further, a hole 58 is provided at the lower end of the inner cylinder 53, and an inertance pipe 56 is inserted through the hole 58.
and the second volume chamber 55 are communicated with each other. The inertance tube 56 also has holes 31' and 3 at predetermined positions, respectively.
2' is formed. A resistor 41' is installed inside these holes 31' and 32' (on the second volume chamber side) as necessary.
, 42' are attached. Since the other configurations are the same as those of the first embodiment described above, the same parts as in FIG. 1 are given the same numbers and the explanation will be omitted. Further, the equivalent circuit is the same as that in FIG. 2, and the effects are also the same as in the first embodiment, so the explanation will be omitted. As is clear from the above description, the characteristics of the dynamic microphone according to the present invention are as follows. At least two volume chambers capable of accumulating air are formed behind the diaphragm, these volume chambers are communicated by an inertance tube having a predetermined vibration system equivalent mass, and a plurality of inertance tubes are provided at intermediate positions of the inertance tube. It is formed by forming holes. Therefore, due to the hole in the inertance tube, a bypass is formed in the equivalent circuit from a predetermined intermediate value of the equivalent mass of the inertance tube, and the resonant frequency value etc. change, so the frequency characteristics are changed to improve the sound quality. You can make it whatever you want.

In this case, the frequency characteristics can be adjusted very easily by selectively opening and closing the holes or opening them through resistors. In addition, since different frequency characteristics and sound quality can be obtained with the same internal structure, it is possible to obtain versatility as a microphone, and since there is no need to change manufacturing molds for different frequency characteristics, it is suitable for mass production.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic sectional view showing the first embodiment of the present invention;
1 is an equivalent circuit diagram of FIG. 1, FIG. 3 is a schematic sectional view showing a second embodiment of the present invention, and FIG. 4 is a sectional view taken along the line W-N in FIG. 3. 1...Dynamic microphone, 2...
... Magnetic circuit, 7 ... Air gap, 8 ... Voice coil, 9 ... Vibration plate, 21, 51 ... First volume chamber, 22, 55 ... ...Second volume chamber, 25,
56...inertance tube, 31, 32, 31'
, 32'... hole, 41, 42, 41', 42'...
...Resistor. Figure 2 Figure 3 Figure 4 Figure 1

Claims (1)

[Claims] 1. In a dynamic microphone in which a voice coil is disposed in a gap provided in a magnetic circuit and a diaphragm is coupled to the voice coil, at least two volume chambers capable of accumulating air are formed behind the diaphragm. A dynamic microphone characterized in that these volume chambers are communicated by an inertance tube having a predetermined vibrating thread equivalent mass, and a complementary number of holes are formed in the inertance tube.