JP5028199B2 - Omnidirectional dynamic microphone - Google Patents

Description

  The present invention relates to an omnidirectional dynamic microphone, and more particularly to a technique for reducing vibration noise.

  For example, a hand-held microphone used for vocal use is usually an omnidirectional dynamic microphone. In the omnidirectional dynamic microphone, all the surrounding sounds gathered there reach the diaphragm and convert it into an electrical signal. In other words, it has a feature that reacts only to the loudness of the sound regardless of the direction and angle of the microphone body.

  The dynamic microphone is a microphone using electromagnetic induction including a diaphragm, a permanent magnet, and a voice coil. The voice coil is fixed to a diaphragm formed in a substantially dome shape, and the diaphragm vibrates in response to sound waves such as voice, and outputs a voice signal when the coil vibrates in a magnetic field generated by a permanent magnet.

  An omnidirectional dynamic microphone (hereinafter referred to as a microphone) is often used by hand, so the microphone body is often shaken. By shaking the microphone, the vibration is transmitted to the microphone unit inside the microphone, and the diaphragm supported so as to be able to vibrate in the microphone unit vibrates with the voice coil in the magnetic gap and outputs an unnecessary voice signal, which is noise and Become. As a basic configuration for suppressing the noise, a buffer member is generally interposed between a microphone case and a microphone unit. In such a conventional example, there is one that uses a non-breathable sponge for the buffer member, and there is no elastic force to suppress the vibration of the microphone unit, and the microphone unit collides with the inner surface of the microphone case. It only serves to prevent the collision noise that occurs. Therefore, the buffering force is insufficient with the conventional buffer member.

  An example of a conventional omnidirectional dynamic microphone will be described with reference to FIGS. In FIG. 3, reference numeral 15 denotes a head case. The head case 15 is formed in a bowl shape, and an inward jetty 15-2 is formed on the narrow side of the bowl case. The head case 15 has a cylindrical shape at the lower part (right side in FIG. 3) with the jetty 15-2 as a boundary, and is screwed onto the outer peripheral surface of the head case 15 with the internal screw of the microphone case 17 (see FIG. 5). The external screw 15-1 is formed. On the other hand, an internal thread 15-3 is formed in the opening of the head case 15 (left side in FIG. 3). The inner screw 15-3 is screwed with the outer screw 12-1 of the head ring indicated by reference numeral 12. The head ring 12 is formed with an inward jetty at the front (left side in FIG. 3), and the inner peripheral edge of the jetty is bent at right angles in the front direction (left side in FIG. 3). The outer peripheral portion of the head ring 12 has a shape in which the thickness is sequentially increased from the front portion to the central portion. The outer periphery of the dome-shaped head mesh 11 is fitted to the inner periphery of the front end of the head ring 12, and the rear end of the head mesh 11 is in contact with the jetty of the head ring 12. An outer screw 12-1 is provided on the outer peripheral surface of the rear portion (right side in FIG. 3) of the head ring 12, and is screwed into the inner screw 15-3 of the head case 15.

  In FIG. 4, reference numeral 10 denotes a microphone unit. The microphone unit 10 includes a shallow bottomed cylindrical frame 20 at the front (left side in FIG. 4). A plurality of communication holes 29 are formed at equal intervals in the circumferential direction at the bottom of the frame 20. An acoustic resistor 28 is affixed so as to close the front portion of 29. In the illustrated example, a jetty 20-1 having a slightly smaller diameter than the outer periphery is formed in a ring shape toward the rear side (right side in FIG. 4) on the back surface of the frame 20. A ring-shaped unit frame 22 is fitted to the back surface of the frame 20. The unit frame 22 supports the outer peripheral edge of the diaphragm 21. The center of the diaphragm 21 is formed in a dome shape, and an arch-shaped edge portion is formed so as to surround the diaphragm 21. One end of a voice coil 25 is bonded to the diaphragm 21 at the boundary between the center portion and the edge portion. On the rear side of the diaphragm 21, a bottomed cylindrical yoke 26, a flat columnar permanent magnet 23 fixed to the inner lower portion of the yoke 26, and a permanent magnet 23 are fixed and slightly smaller than the diameter thereof. A pole piece 27 having a large diameter and a magnetic circuit portion made of a ring member fixed to the circumferential portion of the opening of the yoke 26 are positioned so as to cover the outer periphery of the pole piece 27. A plurality of through holes are formed at the bottom of the yoke 26. A circular magnetic gap is formed between the pole piece 27 and the ring member, and a voice coil is interposed in the magnetic gap with a space. A cylinder 40 having substantially the same diameter as that of the yoke 26 is fixed to the rear side of the yoke 26 (the right side in FIG. 4). It is fixed toward. A through hole 42-1 is formed at the center of the bottom of the bottomed cylindrical member 42, and an acoustic resistor 42-2 is attached to the front of the through hole 42-1.

A non-breathable ring-shaped rear damper 33 is fitted to the rear outer periphery of the cylinder 40 at the rear of the microphone unit 10. Further, a ring-shaped peripheral damper 32 having no air permeability is fitted to the outer periphery of the frame 20 on the outer periphery of the front portion of the microphone unit 10. Further, a flat ring-shaped damper 31 having no air permeability is fitted to the front surface of the frame 20 on the front surface of the microphone unit 10. A microphone unit is supported in the head case 15 with the rear damper 33, the peripheral damper 32, and the front damper 31 interposed.

  When an external force is applied to the microphone and vibrates, the three types of dampers, the front damper 31, the peripheral damper 32, and the rear damper 33, suppress the collision of the microphone unit 20 with the head case 15. Moreover, the sealing effect of acoustic space is also acquired by using the material which does not have air permeability as a material of each said damper. However, the main effect of providing the above three types of dampers is to suppress the collision of the microphone unit 10 against the head case 15 and to mitigate the collision sound generated when the microphone unit 10 collides with the head ring 12. The effect of suppressing vibration cannot be obtained. Further, as shown in FIG. 3, the rear damper 33 dominates the supporting force of the microphone unit 10. On the other hand, the center of gravity of the microphone unit 10 is a substantially front portion of the microphone unit 10 where the heavy permanent magnet 23, the yoke 26, the pole piece 27, and the like are located.

  In FIG. 5A, a line denoted by reference numeral 51 indicates a surface extending in the radial direction through the center of gravity of the microphone unit 10, and a reference numeral 57 indicates a line in the central axis direction of the microphone unit 10 passing through the center of gravity. Indicates. When the external force is applied to the microphone when the external force is applied to the microphone, the line 51 and the line 55 indicating the radial surface passing through the support center of the microphone unit 10 by the rear damper 33 have a distance in the direction of the central axis 57. The amplitude of the relative movement of the unit increases. This is because the microphone unit 10 moves relative to the microphone case with the support center of the microphone unit 10 on the line 55 as a fulcrum. In addition, when the microphone is used by hand, there is a support position at the central portion in the longitudinal direction of the cylindrical microphone case 17 (see the line indicated by reference numeral 61), and the microphone unit rotates because of the rotational position. The relative movement with respect to the 10 microphone cases becomes larger.

  As a prior art related to the present invention, there is an invention described in Patent Document 1. The invention described in Patent Document 1 relates to a dynamic microphone having a structure for reducing vibration noise. When the microphone is used by hand, the microphone itself vibrates strongly, causing the diaphragm to vibrate, and the voice coil attached to the diaphragm moves relative to the magnetic gap of the magnetic circuit to generate power, which is unnecessary along with the voice. Moreover, a considerable amount of noise is generated. Therefore, the invention described in Patent Document 1 solves this by providing an acoustic resonance circuit for suppressing vibration.

  In the invention described in Patent Document 1, there are two air chambers of different sizes made of an elastic body on the back side of the diaphragm for inputting sound, and the two air chambers communicate with each other through a duct. When an impact sound is generated by an impact from the outside of the microphone case, a resonance circuit inside the air chamber installed on the back side of the diaphragm acts, canceling the impact sound at a specific frequency, and reducing the acoustic impedance. The sound pressure is lowered to increase the return sound pressure to the diaphragm, and the braking force against the diaphragm is increased. According to this known example, vibration noise can be suppressed. However, this is an acoustic solution using the resonance circuit, which is different from the method for solving the problem of vibration noise according to the present invention.

  The invention described in Patent Document 2 solves this problem by adding an acoustic space and a vibration detection unit for reducing vibration noise of the microphone. This microphone includes a microphone unit for collecting sound and a vibration detection unit for detecting vibration noise. The microphone unit includes a magnetic circuit unit and a diaphragm to which a voice coil arranged in the magnetic gap is bonded, and the vibration detection unit supports the microphone unit and communicates with the back side of the diaphragm. Has an air chamber. On the back surface of the air chamber, a vibration detection unit including a magnetic circuit unit and a diaphragm provided with a voice coil disposed in the magnetic gap is attached. There is an effect of suppressing noise by synthesizing the output signal from the vibration detection unit in the opposite phase to the output signal of the microphone unit. Further, the diaphragm of the vibration detection unit has an effect of suppressing the diaphragm that vibrates by an external force from the back side by utilizing the pressure change of the air chamber. However, since the acoustic space and the vibration detection unit are attached, there is a problem that the weight increases, and it is necessary to supply power to the vibration detection unit.

  The invention described in Patent Document 3 is intended to prevent the diaphragm from vibrating greatly by suppressing standing waves of noise generated by vibration noise of a microphone. A microphone unit equipped with a diaphragm, voice coil, and permanent magnet is provided with a space made of vibration-proof members at the rear, and a plurality of inner walls are concentrically formed in the space to enhance the vibration-proof effect. ing. A lid is provided at the rear end of the space. By making the lid and the diaphragm non-parallel, the incident wave of sound and the reflected wave reflected from the inner wall or the lid are combined, The standing wave in the space is suppressed. The invention described in Patent Document 3 has the most important feature of suppressing the standing wave generated inside the microphone unit, and does not focus on the support structure for the case of the microphone unit itself. The specific configuration for solving is different from the present invention.

  In addition to the inventions described in the above patent documents, inventions aimed at suppressing vibration noise have been proposed (see Patent Documents 4 and 5). However, both inventions relate to vibration noise reduction by an acoustic space. This is different from the present invention.

JP-A-11-2755681 Japanese Patent Laid-Open No. 11-196489 JP 10-336777 A JP-A-53-147525 Japanese Utility Model Publication No. 51-131224

  In any of the above-described conventional examples, this is solved by an acoustic structure as a method for suppressing vibration noise which is a problem in a handheld microphone. However, in order to solve the problem with an acoustic structure, it is necessary to install a vibration detection unit or the like separately from the original function as a microphone, leading to an increase in the weight of the main body. In addition, when the vibration detection unit or the like is provided, power supply is required.

  Therefore, in order to solve the above problems, the present invention aims to suppress vibration noise by a physical design and a support structure of a microphone unit provided with an elastic member.

  The present invention relates to a microphone unit including a diaphragm that vibrates by sound, a voice coil fixed to the diaphragm, and a permanent magnet that generates a magnetic gap for outputting an electric signal when the voice coil vibrates. An omnidirectional dynamic microphone including a case for supporting the microphone unit internally, the microphone unit being supported by the case via an elastic member, the elastic member passing through the center of gravity of the microphone unit. The main feature is that the microphone unit is supported in the case by being interposed between the outer periphery of the microphone unit and the inner peripheral surface of the case at a position where a virtual plane in a direction perpendicular to the central axis crosses. .

  According to the configuration of the microphone of the present invention, the elastic member supports the microphone unit at a position where the virtual plane in the direction orthogonal to the central axis passes through the center of gravity in the radial direction of the microphone unit to which the vibration force due to the external force is greater. Thus, vibration can be effectively suppressed and vibration noise can be reduced.

  Further, the elastic member is made of RTV rubber material, and the elastic member made of the RTV rubber is interposed between the head ring and the microphone unit so that the acoustic space at the rear of the microphone unit can be sealed. Thereby, an omnidirectional microphone can be configured.

  Furthermore, the elastic member is made of a sticky material, and the microphone unit is bonded to the head ring via the elastic member, so that there is an effect of reducing the failure rate during assembly.

Embodiments according to the present invention will be described below with reference to the drawings. Since many parts of the configuration of the present invention are substantially the same as the configuration of the conventional example described above, the description of the schematic configuration of the microphone will be omitted, and the main part will be described mainly. Figure 1 shows an embodiment of the present invention, when compared with the conventional example shown in FIG. 3, eliminates the rear damper 33, in place of the peripheral portion dampers 32 and the front damper 31, using RTV rubber 50 There is a big difference. In FIG. 1, the RTV rubber 50 has a cylindrical shape, and the front end is bent inward at a right angle. The microphone unit 10 has the same configuration as the microphone unit in the conventional example, and is interposed between the front surface and the outer peripheral surface of the frame 20 of the microphone unit 10 and the inner peripheral surface of the head ring 12, and bonds them together. And elastic support. Since the permanent magnet 23 and the yoke 26 are installed at the front part of the microphone unit 10, the center of gravity of the microphone unit 10 is located at the front part, and a virtual plane passing through this center of gravity and perpendicular to the central axis is present. The microphone unit 10 and the head ring 12 are bonded to each other at the crossing position with the RTV rubber 50 interposed therebetween.

  Reference numeral 51 denotes a virtual plane passing through the center of gravity of the microphone unit 10 and orthogonal to the central axis. Reference numeral 53 denotes a virtual plane passing through the center of support of the microphone unit 10 by the RTV rubber 50 and perpendicular to the central axis. The distance between the line indicating the surface 51 and the line indicating the surface 55 in FIG. 5A and the distance between the line indicating the surface 51 and the line indicating the surface 53 in FIG. It is designed to support it near the center of gravity. With this configuration, when an external force such as an impact force is applied to the microphone, the force with which the microphone unit 10 tries to rotate with respect to the microphone case is reduced, and a stable support structure for the microphone unit 10 with less vibration is obtained. be able to. Further, even if the microphone case is gripped at the center in the length direction and shaken at the gripped position as a fulcrum, the microphone unit 10 is supported by the head case 15 at a position close to the center of gravity as described above. The force with which the microphone unit 10 tries to rotate with respect to the case is small, and the vibration of the microphone unit 10 in the radial direction can be effectively suppressed, and vibration noise can be reduced.

  Further, the RTV rubber 50 interposed between the outer periphery of the microphone unit 10 and the inner peripheral surface of the case has adhesiveness as a property, and the head mesh 11 is fixed as shown in FIG. The head ring 12 and the microphone unit 10 are bonded together with the RTV rubber 50 interposed therebetween. A head case 15 is coupled to the head ring 12 by screws, and thus the head case 15 supports the microphone unit 10 therein.

  Furthermore, as shown in FIG. 1, the RTV rubber 50 is a non-breathable material, and is interposed between the outer periphery of the microphone unit 10 and the inner peripheral surface of the head ring 12, so that the inside of the microphone case is In addition, the acoustic space on the rear side of the microphone unit 10 is effectively sealed. Due to this effect, sound is collected only from the head mesh 11 side, and the rear side of the microphone unit 10 has a sealed acoustic space, thereby forming an omnidirectional microphone.

It is a longitudinal cross-sectional view which shows the principal part of the Example of the microphone concerning this invention. It is a decomposition | disassembly longitudinal cross-sectional view which shows the principal part of the said Example. It is a longitudinal cross-sectional view which shows the principal part of the example of the conventional microphone. It is a decomposition | disassembly longitudinal cross-sectional view which shows the principal part of the said conventional microphone. (A) which shows the said conventional microphone is a longitudinal cross-sectional view, (b) is a front view, (c) is an external appearance side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Microphone unit 12 Head ring 15 Head case 20 Frame 23 Permanent magnet 25 Voice coil 26 Yoke 50 RTV rubber which is an elastic member 51 Center of gravity position of microphone unit 53 Support position of microphone unit

Claims (3)

A microphone unit including a diaphragm that vibrates by sound, a voice coil fixed to the diaphragm, and a permanent magnet that generates a magnetic field for outputting an electric signal when the voice coil vibrates. A omnidirectional dynamic microphone with a case for supporting
The microphone unit is supported by the case via an elastic member,
The elastic member is interposed between the outer periphery of the microphone unit and the inner peripheral surface of the case at a position where a virtual plane in a direction passing through the center of gravity of the microphone unit and perpendicular to the central axis crosses, and the microphone unit is placed in the case. An omnidirectional dynamic microphone characterized by its support.   The omnidirectional dynamic microphone according to claim 1, wherein the elastic member is made of a material capable of sealing an acoustic space.   The omnidirectional dynamic microphone according to claim 1, wherein the elastic member is made of an adhesive material.

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