JP2008177633A - Microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microphone capable of reducing a vibration noise by reducing variance in pressure in a microphone case caused by vibrations of the microphone. <P>SOLUTION: The microphone is constituted so that a case, a head cover mounted on a front end portion of the case, a vibration-proof member mounted between the case and head cover, and a microphone unit are fixed to the case through the vibration-proof member, wherein a sound hole, communicating with the outside from the inside of the case, is included in a side portion of the head cover. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microphone that can reduce vibration noise by reducing a pressure change in a microphone case caused by vibration of the microphone.

  Vibration generated when gripping or holding the microphone propagates through the microphone case and is transmitted to the built-in microphone unit, generating vibration noise. In order to prevent this vibration noise, a microphone is known in which a vibration isolating mechanism is applied to a microphone unit incorporated in a microphone case (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 7-245795

  According to the microphone described in Patent Document 1, the microphone unit is installed on the bottom surface of the microphone unit with a thick anti-vibration rubber, and the microphone unit is attached to the microphone case via the anti-vibration rubber. The low vibration component of the vibration generated in the case can be effectively absorbed, and vibration noise can be prevented.

  In the microphone, a head cover for windshield is mounted on the uppermost part of the microphone case, and an air chamber is formed between the head cover and the microphone unit mounted in the microphone case. A microphone with good acoustic characteristics can be obtained when the volume of the air chamber is as small as possible. For this reason, the above-described vibration isolation mechanism (hereinafter referred to as “shock mount”) is disposed at the front end of the microphone case to reduce the volume of the air chamber formed by the microphone unit mounted via the shock mount and the head cover. Is more desirable.

  An example of a conventional microphone mounted with a microphone unit in this way is shown in FIGS. 3 and 4 are longitudinal sectional views of examples of conventional microphones. In FIG. 3, the microphone 1 has a shock mount 11 attached to a front end portion of a case 12, and a microphone unit 10 is attached via the shock mount 11. The microphone unit 10 has a function of converting vibration such as sound into an electric signal. The shock mount 11 is made of an elastic material necessary for fixing the microphone unit 10 to the case 12 and preventing vibration transmitted from the case 12 to the microphone unit 10. A head cover 14 is mounted so that the shock mount 11 is sandwiched between the case 12 and the shock mount 11. The head cover 14 is mounted so as to cover the front end portion of the microphone case 12 and has a role of preventing wind noise from being generated by preventing the outside air from directly hitting the acoustic terminal 13 of the microphone unit 10. The member constituting the acoustic terminal 13 has an outer peripheral portion fixed to the shock mount 11 and forms an air chamber 15 between the acoustic terminal 13 and the head cover 14.

  When the microphone 1 receives an impact due to dropping or the like and vibrates in the vertical direction in FIG. 3, the shock mount 11 is displaced so as to cancel the vibration. For example, the operation of the shock mount 11 and its effect when the microphone 1 is displaced downward will be described with reference to FIG. In FIG. 4, the microphone unit 1 is displaced downward from the state shown in FIG. 3 by vibration. When the microphone unit 1 is displaced downward in this manner, the shock mount 11 is displaced so as to extend upward.

  In this way, the shock mount 11 is displaced relative to the case 12 to cancel the vibration propagating to the microphone unit 10 and prevent the generation of vibration noise due to the vibration of the case 12. Since the acoustic terminal 13 and the head cover 14 are relatively close to each other, the air in the air chamber 15 is compressed and the pressure in the air chamber 15 is increased. Conversely, when the microphone 1 is displaced upward, the air in the air chamber 15 is expanded and the pressure is reduced. When vertical vibration is applied to the microphone 1, as described above, a continuous pressure change occurs in the air chamber 15, and this pressure change increases the vibration of the acoustic terminal 13 and causes vibration noise. .

  Accordingly, when the vibration in the vertical direction is absorbed by the elasticity of the shock mount 11, the air around the acoustic terminal 13 is vibrated by the displacement of the shock mount 11, and vibration noise is generated by the vibration of the air. Cause. Therefore, even if the microphone unit 10 is attached to the case 12 via the shock mount 11, vibration noise cannot be effectively prevented.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a microphone that can reduce a pressure change inside the case caused by vibration of the case and prevent vibration noise.

  The present invention comprises a case, a head cover attached to the front end of the case, a vibration isolating member attached between the case and the head cover, and a microphone unit fixed to the case via the vibration isolating member. The microphone is characterized in that an acoustic hole is provided in a side portion of the head cover so as to communicate from the inside of the case to the outside.

  Further, the present invention is characterized in that the acoustic hole is located in the vicinity of the vibration isolating member. Further, the present invention is characterized in that an acoustic resistor is installed to cover the acoustic terminal of the microphone unit.

  According to the present invention, the change in the air pressure in the vicinity of the vibration isolation member due to the vibration of the microphone can be avoided by the outflow and inflow of air through the acoustic hole, so that vibration noise propagating to the acoustic terminal can be prevented. . Further, since the acoustic resistance is provided so as to cover the acoustic terminal of the microphone unit, vibration noise can be suppressed without the acoustic terminal being affected by the pressure change caused by the vibration of the microphone.

  Hereinafter, embodiments of a microphone according to the present invention will be described with reference to the longitudinal sectional views of FIGS. 1 and 2. In FIG. 1, the microphone 1 includes a case 12, a shock mount 11 attached to the front end of the case 12, and a microphone unit 10 attached via the shock mount 11. The microphone unit 10 has a function of converting vibration such as sound into an electric signal, and an electroacoustic conversion method is not limited. The shock mount 11 is made of an elastic material necessary for fixing the microphone unit 10 to the case 12 and preventing vibration transmitted from the case 12 to the microphone unit 10. A head cover 14 is attached to the front end of the case 12 so that the shock mount 11 is sandwiched between the case 12 and the case 12. The head cover 14 is mounted so as to cover the front end portion of the microphone case 12 and has a role of preventing wind noise from being generated by preventing external air from directly hitting the acoustic terminal 13 of the microphone unit 10. The member constituting the acoustic terminal 13 has an outer peripheral portion fixed to the shock mount 11 and forms an air chamber 15 between the acoustic terminal 13 and the head cover 14.

  The shock mount 11 is made of an elastic material necessary for fixing the microphone unit 10 to the case 12 and preventing vibration transmitted from the case 12 to the microphone unit 10.

  The head cover 14 has a bottomed cylindrical shape, and an acoustic hole 17 that communicates from the air chamber 15 to the outside of the microphone 1 is formed in a portion corresponding to a side surface. The acoustic hole 17 is located in the vicinity of the shock mount 11.

  In addition, an acoustic resistor 16 is installed on the front surface (upper side in FIG. 1) of the acoustic terminal 13 in FIG. The acoustic resistor 16 is mechanically fixed to the microphone unit 10. The acoustic resistor 16 has a resistance value that does not degrade the high frequency response of the microphone 1, and forms an air chamber 15 between the head cover 14 and the acoustic resistor 16.

  In the microphone 1 having the above structure, when the microphone 1 is dropped or shaken rapidly to apply vertical vibration in FIG. 1, the shock mount 11 is displaced relative to the case 12 to cancel this vibration. The vibration can be prevented from propagating to the microphone unit 10. FIG. 2 shows a state when the case 12 is displaced downward in comparison with FIG. 1 when the microphone 1 vibrates up and down.

  As shown in FIG. 2, when the microphone 1 is displaced downward, the shock mount 11 is displaced relatively upward and extends. Due to this displacement, the shock mount 11 is deformed so as to rise upward, so that air in the vicinity of the shock mount 11 is pushed upward.

  The air pressure inside the air chamber 15 rises due to the air pushed up by the shock mount 11, but the air whose pressure inside the air chamber 15 rises by the acoustic hole 17 provided on the side surface of the head cover 14 is outside the microphone 1. To be discharged.

  As described above, the pressure fluctuation inside the air chamber 15 caused by the vibration of the microphone can be eliminated by discharging the air from the acoustic hole 17, and the continuous fluctuation of the air pressure on the front surface of the acoustic terminal 13 can be prevented. Therefore, vibration noise can be prevented.

  An acoustic resistor 16 is mounted on the front surface of the acoustic terminal 13 of the microphone 1. The acoustic resistance 16 serves to alleviate the collision of air against the acoustic terminal 13 due to the pressure fluctuation in the air chamber 15 generated by the vertical vibration of the microphone 1 as described above. By mounting the acoustic resistor 16, it is possible to prevent the air in the air chamber 15 and the acoustic terminal 13 from directly colliding even if the microphone 1 is displaced downward as shown in FIG. It is possible to prevent the acoustic terminal 13 from taking in vibration noise due to the vibration of the microphone 1.

  The acoustic resistor 16 is generally composed of a net-like member or a cloth-like member, but suppresses an increase in vibration noise due to a pressure change in the air chamber 15 and degrades a high-frequency response. It is necessary to design the resistance value so as not to occur.

  Further, it is desirable that a filter be provided in the acoustic hole 17 to prevent wind noise from flowing directly into the air chamber 15 in order to prevent wind noise.

  As described above, the electroacoustic conversion system of the microphone according to the present invention is not limited to a specific system, but is particularly effective when the present invention is applied to a non-directional dynamic microphone.

It is a longitudinal cross-sectional view which shows the Example of the microphone which concerns on this invention. It is a longitudinal cross-sectional view which shows the state which the said microphone displaced to the downward direction. It is a longitudinal cross-sectional view which shows the Example of the conventional microphone. It is a longitudinal cross-sectional view which shows the state which said microphone displaced downward.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microphone 10 Microphone unit 11 Shock mount 12 Case 13 Acoustic terminal 14 Head cover 15 Air chamber 16 Acoustic resistance 17 Acoustic hole

Claims (3)

A microphone comprising a case, a head cover attached to the front end of the case, a vibration isolation member mounted between the case and the head cover, and a microphone unit fixed to the case via the vibration isolation member. ,
A microphone having an acoustic hole communicating from the inside of the case to the outside at a side portion of the head cover.   2. The microphone according to claim 1, wherein the acoustic hole is located in the vicinity of the vibration isolation member.   The microphone according to claim 1, wherein an acoustic resistor is installed so as to cover an acoustic terminal of the microphone unit.