JPS6036956Y2 - directional microphone - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a directional microphone.

Conventionally, as shown in FIG. 1A, magnets 3a are placed on both sides of a diaphragm 2 made of a thin film of insulating material and on which a spiral coil 1 is printed.

In a so-called full-plane drive type directional microphone having a structure in which microphones 3b are respectively arranged, a sound hole 5 is provided on the side surface of the microphone unit 4 to introduce sound waves to the back surface of the diaphragm 2 to obtain the desired directivity. In addition, a hole 6a communicating with the air chamber 8 of the microphone case 7 was provided in the back side yoke 6 of the microphone unit E, and a damping material 9 for acoustic resistance was attached to this hole 6a for damping.
It was necessary to provide radial grooves 3b' on the upper surface of the magnet 3b arranged on the back side of the diaphragm 2, as shown in Figure 0, for guiding sound waves to the back side of the diaphragm 2.

For this reason, in the conventional directional microphone of this type, the magnet 3b must be molded and processed to provide the groove 3b', which has the drawback of increasing costs.

Further, since the magnet 3a placed on the front side of the diaphragm 2 and the magnet 3b placed on the back side of the diaphragm 2 cannot be used as common parts, there is a problem that the number of parts increases.

Furthermore, since the magnet 3b on the back side is provided with R3b', the strength of the magnet 3b deteriorates - there is a risk that it may easily crack or chip, and care must be taken during manufacturing and assembly work, making manufacturing complicated. and the groove 3b'
This also has the disadvantage that the magnetic flux density of the magnet 3b is reduced.

The present invention improves the above-mentioned drawbacks and provides a directional microphone that facilitates manufacturing and reduces costs by making it possible to introduce sound waves to the back of the diaphragm without providing grooves in the magnet. The purpose is to

The present invention will be described below with reference to the drawings.

Figure 2 A and 2 show an embodiment of the present invention, and 11
is a bottomed, substantially cylindrical microphone case which also functions as a gripping part and has a back air chamber 12 formed therein, and a net-like protective case 13 is attached to the top of this microphone case 11. .

14 is a short cylindrical microphone unit, and a fixing hole 15 is provided along the axial direction on its outer circumference.A screw 16 is inserted from above, and the tip of the screw 16 is inserted into the upper part of the microphone case 11. The microphone unit 14 is housed and fixed within the protective case 13 by screwing into the protective case 11a.

Therefore, the microphone unit 14 is mainly connected to a diaphragm 18 which is vibably supported by the support frame "7" via the edges.
, annular magnets 19a and 19b, and a yoke 20.

The diaphragm 18 is formed of a thin film of an insulating material, and on both sides of the diaphragm 18, at least two or more magnets 19a, 19b are arranged facing each other with a slight interval between them.

These magnets 19a and 19b are arranged concentrically on the inner surface of a yoke 20 disposed above and below the diaphragm 18, and the magnetic poles facing each other with the diaphragm 18 in between have the same polarity. In addition, adjacent magnetic pole faces are arranged to have different polarities.

A spiral coil 21 is printed on the diaphragm 18 so as to be located between the adjacent magnetic poles of the magnets 19a and 19b, so that the magnetic flux generated between the adjacent magnetic poles crosses the coil 21 at right angles, and the external When the diaphragm 18 vibrates due to sound waves introduced into the interior through the sound hole 13a of the protective case 13 and the sound hole 20a formed in the yoke 20, an electromotive force is generated in the coil 21 according to Fleming's law, and a sound current is obtained. It is now possible to

22 is arranged at the bottom of the microphone unit 1 and is made of a material such as synthetic resin for introducing sound waves into the microphone unit 14 through the sound hole 20a of the lower yoke 20 to obtain desired directivity characteristics. This acoustic attachment 14 has a circular hole 22a in the center to which a damping material 23 for damping the diaphragm 18 is pasted.
It consists of a main body 22a having a substantially disc-like shape and a plurality of upright pieces 22b integrally formed with the main body 22a so as to extend perpendicularly to the main body 22a on the outer periphery of the upper surface of the main body 22a. 22b is curved approximately concentrically with respect to the disc-shaped main body 22a and is spaced apart from each other, and between the adjacent upright pieces 22b, 22b is a component that exerts a speed effect on the diaphragm 18 in the microphone unit 14. A slit 22c is formed for introducing the sound wave.

By the way, the directivity characteristics of a sound pressure gradient microphone are determined by the mass of air determined by the volume of the slit 22c formed in the acoustic attachment 22, and the acoustic impedance of the acoustic attachment 22, which is made up of the resistance component of the air that occurs when a sound wave passes through it. , a capacitance component due to the internal volume of the back air chamber 12 of the microphone case 11 located on the rear side of the diaphragm 18, and the hole 22 of the main body 22a of the acoustic attachment 22.
It is determined by the ratio of the acoustic impedance made up of the resistance component of the damping material 23 attached to a'.

Therefore, in order to obtain constant directivity characteristics, the slit 2 formed between the upright pieces 22b of the acoustic attachment 22 must be
2c volume variation and braking material 23
The acoustic resistance should be kept as constant as possible.

However, in the present invention, the slit 22c of the acoustic attachment 22 can be made uniform by molding plastic or Guicast, and the hole 22a' formed in the center can be made of cloth, felt, etc. with a predetermined amount of ventilation. By applying the damping material 23, the acoustic resistance can be made constant, which is preferable.

The tip of the upright piece 22b of the acoustic attachment 22 is brought into contact with the lower surface of the lower yoke 20 constituting the microphone unit 14, and the outer circumferential portion of the lower surface of the main body 22a is placed on the upper part 11a of the microphone case 11. It is placed inside the microphone body in such a state.

That is, in assembling, first, the attachment 2z, which has been constructed in advance by stretching the damping material 23 whose acoustic resistance component has been measured, is placed on one side of the slit 22c, which has an acoustic impedance for providing directional characteristics, and the hole 22a' formed in the center of the slit 22c. On the other hand, the frequency response of the microphone unit 14 configured in advance is checked in advance, and the acoustic attachment 22 is disposed on the lower surface of the microphone unit H.
and the acoustic attachment 22 are made into a unit.

In this case, the tip of the upright piece 22b is bonded to the lower surface of the lower yoke 20 via adhesive, and the microphone unit 1
The acoustic attachment 22 may be integrally coupled to the lower surface of the microphone unit 14, or the acoustic attachment 22 may be integrally connected to the lower surface of the microphone unit 14, or a supporting rod may be provided protruding from the lower surface of the microphone unit 14.
A hole is formed in the corresponding position of the main body 22a of 22,
By tightly fitting the rod into the hole, both can be integrated into a unit.

Thus, the acoustic body consisting of the microphone unit 14 and the acoustic attachment 22 which have been unitized in this way is connected to the upper part of the microphone case 11 through the screw 16.
1a, and then a protective case 1 for preventing dust etc. from entering the interior and protecting the acoustic body.
3 to the upper outer periphery of the microphone case 11, the microphone main body can be easily assembled.

As described above, according to the present invention, the frequency response of the microphone unit and the damping material of the acoustic attachment are adjusted in advance, and the acoustic attachment having a predetermined acoustic impedance is integrally fixed to the lower part of the microphone unit. Therefore, a desired directivity characteristic can be easily obtained, and the microphone unit and the acoustic attachment that have been integrated in advance can be fixed in the microphone case, which has the advantage of being easy to manufacture and suitable for mass production.

In addition, it is possible to eliminate the process of creating holes in the supporting frame that constitutes the microphone unit and the side of the yoke on the back side of the diaphragm, as well as creating grooves in the magnet due to this, as in the conventional example. Since the magnets placed on the top and bottom of the board can be shared, costs can be reduced accordingly, and since there is no need to provide grooves on the magnets, a decrease in magnetic flux density can be prevented. There are advantages.

[Brief explanation of the drawing]

Figure 1 (A) 9 is a conventional directional microphone, Figure (A) is a partial cross-sectional view, Figure 0 is a perspective view of a magnet used on the conventional side, and Figure 2 (A) 9 is a directional microphone according to the present invention. Figure A is a sectional view thereof, and Figure 0 is a perspective view of the acoustic attachment applied to the present invention. 11...Microphone case, 12...
・Air chamber, 13...Protective case, 14...
... Microphone unit, 15 ... Fixing hole, 16 ... Screw, 17 ... Support frame, 1
8...Vibration plate, 19a, 19b...Magnet, 20...Yoke, 20a...
・Sound hole, 21... Coil, 22... Acoustic attachment, 22a... Body, 22a'
...hole, 22b... standing piece, 22c.
...Slit, 23...braking material.

Claims (1)

[Scope of utility model registration request] A diaphragm 18 having a coil 21, and a plurality of magnets 19a and 19b arranged oppositely above and below this diaphragm 18.
and a yoke 20 in which these magnets are arranged to form a magnetic circuit and a sound hole 20a for introducing sound waves is formed,
An acoustic attachment 22 is provided in which a hole 22a communicating with the air chamber 12 of the microphone case 11 is formed on the back surface of the microphone unit 14 via a damping material 23 for acoustic resistance, and a slit 22c is defined by an upright piece 22b. A directional microphone characterized in that it is configured to introduce sound waves into the back surface of the microphone unit earthwork through the slit 22c.