JP2017112479A - Contact microphone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a sensitivity fluctuation caused by an attachment pressure to a living body, in a contact microphone which uses a capacitor microphone unit as a vibration-electric conversion element.SOLUTION: A contact microphone 1A includes a capacitor microphone unit 10A, and a living body contact part 22 composed of an elastic resin material which contacts to a living body to transfer the living body vibration thereof to a diaphragm of the capacitor microphone unit. The living body vibration is transferred to the diaphragm through the living body contact part 22, so as to be detected as an electric signal. Also, on the back face of the living body contact part 22 which is attached to the opening of a bottomed cylindrical unit case 21, an electric conductive layer 11a which acts as a diaphragm is provided. A spacer ring 13 and a stationary pole 14 are successively adhered and fixed to the top of the conductive layer 11a. The capacitor microphone unit 10A including the stationary pole 14 is supported by the back face of the living body contact part 22.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a contact microphone that contacts a living body and converts the vibration of the living body into an electric signal. More specifically, the present invention relates to a contact microphone that uses a capacitor microphone unit as a vibration-electric conversion element.

  In addition to the contact microphone that detects acceleration and pressure using a piezoelectric element such as a bone conduction microphone, for example, as described in Non-Patent Document 1, “Non-Auditable Murmur” There is a so-called “microphone (NAM microphone)” or “microphone for body conduction sound collection”.

  In this type of contact microphone, a condenser microphone unit is used as a vibration-electricity conversion element, and vibrations of a living body are transmitted to a diaphragm in contact or non-contact to be converted into an electric signal.

  That is, as shown in FIG. 3, as a basic configuration, the fixed pole 14 and the diaphragm 11 stretched in a state where a predetermined tension is applied to the diaphragm ring 12 are opposed to each other through the spacer ring 13. A condenser microphone unit 10 is provided. In the following description, the condenser microphone unit may be simply referred to as “microphone unit”.

  For the fixed pole 14, a metal plate made of an aluminum material or the like having a plurality of through holes 14a is used. In an NAM microphone, usually, an electret type having an electret dielectric film 15 on the surface facing the diaphragm 11 is used. Is adopted. The fixed pole 14 is incorporated in the unit case while being supported by a pedestal (also referred to as a cylinder) 16 having a shallow bottom made of an electrical insulating material.

  FIG. 4A shows a contact microphone 2 </ b> A as a first conventional example using the microphone unit 10.

  The contact microphone 2 </ b> A has a bottomed cylindrical unit case 21 having an air chamber of a predetermined volume inside and having one surface opened as an opening, and the microphone unit 10 is fixed in the unit case 21. Although housed together with the pedestal 16 that supports the pole 14, a living body contact portion 22 for transmitting the vibration of the living body to the diaphragm 11 is provided in the opening of the unit case 21.

  As described in Patent Document 1, an elastic resin material such as silicone rubber or urethane elastomer having an acoustic impedance close to that of a human soft tissue is used for the living body contact portion 22. In the contact microphone 2A as a conventional example, the living body contact portion 22 is brought into contact with the diaphragm 11 in a natural state (no load state).

  When the contact microphone is used, the living body contact portion 22 is brought into contact with the living body by applying pressure. In the contact microphone 2A of the first conventional example, the living body contact portion 22 is in direct contact with the diaphragm 11. Therefore, as shown in FIG. 4B, the diaphragm 11 is displaced toward the fixed pole 14 by the pressing pressure against the living body.

  This displacement narrows the distance between the diaphragm 11 and the fixed pole 14 and increases the sensitivity. However, it is not preferable that the sensitivity of the contact microphone fluctuates due to the pressure applied to the living body.

  As another example, in the contact microphone 2B as the second conventional example shown in FIG. 5A, an air layer A is interposed between the living body contact portion 22 and the diaphragm 11, and the stiffness of the air layer A is set. The living body contact portion 22 and the diaphragm 11 are mechanically coupled to each other.

  However, also in this contact microphone 2B, as shown in FIG. 5 (b), the diaphragm 11 is displaced toward the fixed pole 14 due to the pressure of the living body contact portion 22 against the living body. Similarly, the sensitivity of the contact microphone varies depending on the pressure applied to the living body.

  In both the first conventional example and the second conventional example, when a contact microphone is attached / detached, vibration noise having a low frequency component is generated as in the case of a normal microphone, and the worst diaphragm 11 comes into contact with the fixed pole 14. Has a problem that the function as a microphone is lost.

JP 2011-182000 A

Co-authored by Shota Shimizu et al. “Frequency characteristics of several types of NAM microphones” The Acoustical Society of Japan, September 2007 issue

  Accordingly, an object of the present invention is to prevent the sensitivity from fluctuating due to an attachment pressure to a living body in a contact microphone using a condenser microphone unit as a vibration-electric conversion element.

In order to solve the above-described problems, the present invention provides a condenser microphone unit in which a diaphragm and a fixed pole are arranged to face each other via a spacer, and an elastic resin that contacts the living body and transmits the biological vibration to the diaphragm. A contact microphone comprising a living body contact portion made of a material, and transmitting vibrations of a living body to the diaphragm via the living body contact portion to detect an electrical signal.
Including a unit case having one surface opened as an opening, the living body contact portion is provided in the opening of the unit case, and the condenser microphone unit including the fixed electrode is provided on the back surface of the living body contact portion. It is characterized by being supported.

  In the present invention, it is preferable that the diaphragm is integrally formed on the back surface of the living body contact portion as a metal vapor deposition film or a metal foil.

  Further, the present invention includes an aspect in which the diaphragm is made of a resin film having a metal vapor deposition film on one surface stretched on the diaphragm ring, and the diaphragm ring is attached to the back surface of the biological contact portion. .

  According to a preferred aspect of the present invention, an electret dielectric film is provided on the electrode surface of the fixed pole facing the diaphragm.

  The unit case may be an open type communicating with the outside, but is preferably a closed type and the inside is sealed.

  According to the present invention, the entire condenser microphone unit including the fixed electrode is supported on the back surface of the living body contact portion made of an elastic resin material provided in the opening of the unit case. Even if the diaphragm is displaced, the fixed pole is also displaced while keeping the distance from the diaphragm, so that the sensitivity does not vary due to the pressure applied to the living body. In addition, vibration noise of a low frequency component at the time of attachment / detachment can be suppressed to be small.

(A) Sectional drawing which shows the contact microphone which concerns on 1st Embodiment of this invention, (b) Sectional drawing which shows the state in which the attachment pressure to the biological body was applied in 1st Embodiment. Sectional drawing which shows the contact microphone which concerns on 2nd Embodiment of this invention. Sectional drawing which shows the basic composition of a condenser microphone. (A) Sectional drawing which shows the contact microphone which concerns on a 1st prior art example, (b) Sectional drawing which shows the state in which the attachment pressure to the biological body was applied in the 1st prior art example. (A) Sectional drawing which shows the contact microphone which concerns on a 2nd prior art example, (b) Sectional drawing which shows the state in which the attachment pressure to the biological body was applied in the 2nd prior art example.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this. In the description of this embodiment, the same reference numerals are used for components that can be regarded as substantially the same as or the same as those of the conventional example described with reference to FIGS.

  As shown in FIG. 1A, the contact microphone 1A according to the first embodiment includes a microphone unit 10, a unit case 21, and a living body contact portion 22 as in the conventional example described above. As a definition of the microphone unit 10, the microphone unit 10 does not include a base (cylinder) 16 that supports the fixed pole 14.

  Also in the first embodiment, the unit case 21 is formed of a bottomed cylindrical body having an air chamber having a predetermined volume inside and having one surface opened as an opening. The microphone unit 10 is attached to the unit case 21 so as to close the opening of the case 21, but the surface 22a of the living body contact portion 22 is a contact surface to a living body (not shown) and the surface facing the unit case 21 is a back surface 22b. Is entirely supported by the back surface 22b of the living body contact portion 22.

  That is, in the contact microphone 1A according to the first embodiment, the conductive layer 11a made of a metal vapor deposition film or a metal foil is integrally formed on the back surface 22b of the living body contact portion 22, and the conductive layer 11a is formed into the microphone unit 10. The spacer ring 13 and the fixed electrode 14 which are other components of the microphone unit 10 are sequentially attached to the conductive layer 11a with an adhesive or the like.

  In this way, the microphone unit 10a having the diaphragm 11 as the conductive layer 11a formed on the back surface 22b is provided on the back surface 22b of the living body contact portion 22, and the entire microphone unit 10a including the fixed electrode 14 is in contact with the living body. Even if the conductive layer (vibrating plate) 11a is displaced through the living body contact portion 22 by the pressure applied to the living body as shown in FIG. 14 is also displaced while maintaining a distance from the conductive layer 11a, so that the sensitivity does not fluctuate due to the pressure applied to the living body. In addition, vibration noise of a low frequency component at the time of attachment / detachment can be suppressed to be small.

  The living body contact portion 22 is preferably made of an elastic resin material such as silicone rubber or urethane elastomer having an acoustic impedance close to that of a human soft tissue.

  Further, as the back electret type, the electret dielectric film 15 is preferably provided on the surface of the fixed electrode 14 facing the conductive layer 11a. However, as the film electret, the electret dielectric film may be provided on the conductive layer 11a side. Good. The unit case 21 is preferably a closed type and the inside is sealed, but may be an open type communicating with the outside.

  Next, as a second embodiment, like the contact microphone 1B shown in FIG. 2, the microphone unit 10 (however, the pedestal 16 is not included) shown in FIG. You may make it attach integrally through.

  In this case, after the diaphragm ring 12 on which the diaphragm 11 is stretched is bonded and fixed to the back surface 22b of the living body contact portion 22, the spacer ring 13 and the fixed electrode 14 are sequentially attached with an adhesive or the like. 11, the diaphragm ring 12, the spacer ring 13, and the fixed electrode 14 integrated with each other are attached to the back surface 22 b of the living body contact portion 22.

  According to the second embodiment, an air layer is interposed between the living body contact portion 22 and the vibration plate 11, but the vibration plate is pressed via the living body contact portion 22 and the diaphragm ring 12 by the pressure applied to the living body. Even if 11 is displaced, the fixed pole 14 is also displaced while maintaining a distance from the diaphragm 11, so that the sensitivity does not vary due to the pressure applied to the living body. In addition, vibration noise of a low frequency component at the time of attachment / detachment can be suppressed to be small.

1A, 1B Contact microphone 10 Condenser microphone unit (microphone unit)
DESCRIPTION OF SYMBOLS 11 Diaphragm 12 Diaphragm ring 13 Spacer ring 14 Fixed pole 15 Electret dielectric film 16 Base (cylinder)
21 Unit case 22 Living body contact part

Claims (5)

A condenser microphone unit in which a diaphragm and a fixed electrode are arranged to face each other via a spacer; and a living body contact portion made of an elastic resin material that contacts the living body and transmits the living body vibration to the vibrating plate. In the contact microphone for detecting the vibration of the sound through the living body contact portion to the diaphragm and detecting it as an electrical signal,
Including a unit case having one surface opened as an opening, the living body contact portion is provided in the opening of the unit case, and the condenser microphone unit including the fixed electrode is provided on the back surface of the living body contact portion. A contact microphone characterized by being supported.   The contact microphone according to claim 1, wherein the diaphragm is integrally formed on the back surface of the living body contact portion as a metal vapor deposition film or a metal foil.   2. The diaphragm according to claim 1, wherein the diaphragm is made of a resin film having a metal vapor deposition film on one surface stretched on a diaphragm ring, and the diaphragm ring is attached to the back surface of the living body contact portion. Contact microphone.   The contact microphone according to claim 1, wherein an electret dielectric film is provided on an electrode surface of the fixed pole facing the diaphragm.   The contact microphone according to any one of claims 1 to 4, wherein the inside of the unit case is hermetically sealed.

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