JPH0514633Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a microphone, particularly a microphone that is held in the hand and used.

BACKGROUND TECHNOLOGY AND PROBLEMS A stick-shaped microphone, which is often held in the hand, often produces noise (touch noise) when it is gripped again or handed over. This is based on the fact that the diaphragm of the microphone unit vibrates during the above-mentioned operation, and what easily causes this touch noise is
It is not suitable for microphones used in the above-mentioned applications.

Conventionally, various microphones designed to reduce this touch noise have been proposed.

FIG. 1 is an example of this, and to briefly explain it, reference numeral 1 is a microphone unit, which is composed of a yoke 2, an annular magnet 3, a plate 4, a diaphragm 5, a unit case 6, and an equalizer 7. 8 is a unit screen, 9 is a directional resistance, 10 is a directional inertance, 11 is a damper resistance, and 12 is a damper inertance.

Reference numeral 13 denotes a substantially cylindrical cavity case, which is made of metal or resin material and is attached to the back (lower surface) of the microphone unit 1. And the upper end, that is, the microphone unit 1
The side end has a flange 14, and the lower end surface, that is, the back surface 1
5 is occluded. Thus, a back cavity 16 is formed on the back side of the microphone unit 1.

Reference numeral 17 denotes a vibration isolating member (rubber), which has an annular shape and is fitted onto the outer peripheral surface of the cavity case 13. Further, a grip 18 formed of a metal material or a resin material is fitted onto this outer peripheral surface. 19 is a wind screen. Note that according to this configuration, a microphone having unidirectional characteristics can be obtained.

While the vibration applied to the grip 18 is attenuated by the vibration isolation member 17 in the process of being transmitted to the diaphragm 5 of the microphone unit 1,
It has been found that this is still insufficient, and that vibrations applied to the grip 18 in the extension direction of its axis, that is, in the longitudinal direction of the grip 18, appear as relatively large touch noises.

Purpose of the invention The present invention eliminates the above-mentioned drawbacks and
This is to prevent the vibrations applied to the microphone unit 1, that is, the diaphragm 5, from being transmitted to the microphone unit 1, that is, the diaphragm 5.

Summary of the invention The present invention is a microphone in which a cavity case constituting a cavity is attached to the back of a microphone unit, and a grip is fitted to the outer peripheral surface of the cavity case via a vibration isolator. The vibration isolator is formed into a cylindrical shape with a closed back surface so as to form an annular cavity between the vibration isolator and the cavity case, and the end on the microphone unit side is bent. The grip is fitted onto the outer peripheral surface of the member excluding the bent end.

Embodiment Hereinafter, an example of the microphone according to the present invention will be described with reference to FIG. 2. Parts corresponding to those in FIG.

In the present invention, the vibration isolating member 17 described above is formed as shown in the cross-sectional shape of FIG. That is, it has a relatively elongated cylindrical shape, and has a bent portion 20 projecting outward at its upper end, that is, the end on the microphone unit 1 side.
0 to the flange 14 of the cavity case 13.
The lower end of the vibration isolating member 17, that is, the end opposite to the microphone unit 1, is closed by a closing surface 21, and this closing surface 21 is connected to the back surface 15 of the cavity 13 with a screw 22.

When the vibration isolating member 17 is attached to the cavity 13, the size of the cavity case 13 or the vibration isolating member 17, or both, is selected so that an annular cavity 23 is formed between the two 13 and 17. Further, this vibration isolating member 17 can be made of, for example, butyl rubber, and its hardness can be selected to be 30 degrees.

Furthermore, a cavity inertance through hole 24 is formed in the back surface 15 of the cavity 13 to communicate the cavities 16 and 23, and a cavity resistor 25 is provided between them. Therefore, 16 is the first back cavity, and 23 is the second back cavity.

Further, the grip 18 is fitted onto the outer circumferential surface of the vibration isolating member 17 except for the above-mentioned bent portion 20, and is connected with an adhesive 26.

FIG. 3 shows the acoustic circuit of the microphone according to the present invention. Briefly, SP ₀ and SP ₁ are the front sound source and back sound source for this microphone, respectively. L ₁ is the mass of the vibration system, C ₁ is the edge stiffness of the diaphragm 5, L ₂ is the damper resistance, R ₁ is the damper resistance,
C ₂ is the first back cavity, L ₃ is the directional inertance, R ₂ is the directional resistance, L ₄ is the cavity inertance, R ₃ is the cavity resistance, and C ₃ is the second back cavity. In this circuit, the dotted line 27
The conventional acoustic circuit of the microphone shown in FIG. 1 is obtained by excluding the series circuit surrounded by the cavity inertance L ₄ , the cavity resistance R ₃ and the second back cavity C ₃ .

According to such a configuration, the grip 18 is connected to the cavity 13 via the vibration isolating member 17 and the general damper member of the second back cavity 23 formed between the vibration isolating member 17 and the cavity case 13.
That is, since it is connected to the microphone unit 1, the transmission of vibrations to the microphone unit 1 in the lateral direction (direction orthogonal to the longitudinal direction of the grip) to the grip 18 is significantly reduced compared to the case shown in FIG. Furthermore, since the bent portion 20 of the vibration isolating member 17 is interposed between the tip of the grip 18 and the flange 14 of the cavity case 13, this bent portion 20 serves as a cushion for the grip 18 in the longitudinal direction. , vibrations in this direction can be prevented from being transmitted to the microphone unit 1.

When changing the microphone or handing it over,
Vibration is transmitted to the microphone unit's diaphragm 5 through the grip 18, which causes touch noise. Then, if the diaphragm 5 is displaced, for example, downward in FIG. Masu. However, since the second back cavity is a closed space, the pressure change generated within the cavity 16 is reflected and transmitted to the cavity 16 again via the cavity inertance, and as a result, the diaphragm 5 is pushed up. , touch noise can be canceled. In other words, in this example, unnecessary vibration of the diaphragm caused by touch noise can be canceled by a pressure change that is 180 degrees out of phase with the pressure change caused by the vibration caused by touch noise.

Note that the cavity resistor 25 is the same as the cavity 16.
and the second cavity resistance 23.
This controls how pressure changes within the cavity 16 are transmitted to the cavity 23. In other words, it is possible to control the amount of unnecessary vibration of the diaphragm cancelled.

FIG. 4 shows the conventional microphone shown in FIG. 1 and the microphone according to the present invention shown in FIG. From 20Hz
It shows the vibration characteristics by measuring the level of the signal obtained from these microphones, that is, the sound pressure level (SPL) under various vibrations up to 500Hz.The horizontal axis is the scale of the vibration frequency applied to the microphone, and the vertical axis is the scale. Shows the sound pressure level on a scale. solid line 30
3 shows the characteristics of the microphone according to the present invention, and the dotted line 31 shows the characteristics of the conventional microphone. As is clear from this characteristic diagram, the microphone according to the present invention has a 2 to 3 dB reduction in sound pressure level in the vibration range of 20 Hz to 400 Hz compared to conventional microphones, and as a result, the microphone's longitudinal It was also confirmed that directional touch noise was reduced.

FIG. 5 is a curve diagram showing frequency characteristics with the directivity direction for the microphone as a parameter;
The horizontal axis is a scale of frequency, and the vertical axis is a scale of output level. Note that the degrees written in the figure mean the directivity direction with the front direction of the microphone as 0°. Furthermore, the curve indicated by the dotted line is the frequency characteristic with respect to the 180° directivity direction of the microphone shown in FIG.

As is clear from this, the microphone according to the present invention can suppress the output even lower than the conventional microphone when it comes to sound pressure from the back of the microphone (180° directivity direction). You can also check.

Effects of the Invention The present invention described above has the feature of being able to sufficiently reduce the so-called touch noise that occurs when transferring microphones, etc., compared to the conventional one.
As for the configuration for this purpose, compared to the conventional example shown in Fig. 1,
Since it is only necessary to change the shape of the vibration isolating member 17, the structure is not complicated, and therefore the purpose can be achieved without increasing the price of the entire microphone.

[Brief explanation of drawings]

Fig. 1 is a partial sectional view showing a conventional microphone, Fig. 2 is a partial sectional view showing an example of the microphone according to the present invention, Fig. 3 is its acoustic circuit diagram, and Fig. 4 shows its vibration characteristics. Curve diagram, FIG. 5 is a frequency characteristic curve diagram. 1 is a microphone unit, 5 is a diaphragm, 13
1 is a cavity case, 16 is a first back cavity, 17 is a vibration isolating member, and 23 is a second back cavity.

Claims (1)

[Scope of Claim for Utility Model Registration] A cavity case that is attached to the back side of the microphone unit to form a cavity, a bent part that is attached to the outer peripheral surface of the cavity case and supports the microphone unit, and this bent part. a vibration isolating member consisting of a cylindrical part that is integrally provided with the cylindrical part to form a closed space; and a grip that is fitted into the cylindrical part of the vibration isolating member; A microphone characterized in that the cavity case and the vibration isolating member are integrally connected to each other while communicating with a closed space of the vibration isolating member.