JP4276108B2 - Microphone unit mounting structure, electronic device including the same, and microphone unit mounting method - Google Patents

Description

  The present invention relates to a mounting structure for a microphone unit, an electronic device including the mounting structure, and a mounting method for the microphone unit.

An electret condenser type microphone unit is mounted on an electronic device such as a mobile phone or a headset. In general, a condenser unit is formed of a diaphragm (vibrating membrane) and a back electrode plate facing each other through a spacer in a cylindrical case. And a substrate on which a conversion element such as an FET (electrolytic effect transistor) is mounted (see, for example, Patent Document 1). With the recent trend toward miniaturization of electronic devices such as mobile phones, such microphone units have been miniaturized so that they can be mounted in electronic devices even in smaller spaces.
JP 2002-142295 A

  However, when the microphone unit is miniaturized, the diameter of the diaphragm, the gain of the FET, the capacitance of the capacitor unit, and the like are reduced accordingly, leading to a decrease in sensitivity.

  The present invention has been made in view of the above-described problems of the prior art, and a microphone unit mounting structure capable of improving the sensitivity of a miniaturized microphone unit, an electronic apparatus including the same, and a microphone unit mounting It aims to provide a method.

  The mounting structure of the microphone unit according to the present invention is connected to an internal substrate with a first through hole having a cylindrical member that houses an electret condenser type microphone unit and an element for operating the microphone unit in the cylindrical member. And when the microphone unit is mounted on the mounting board so that the opening of the cylindrical member is closed, the inside of the microphone unit is provided. A first acoustic space and a second acoustic space communicating with each other through the first through hole are formed with the substrate interposed therebetween.

  According to the present invention, since the second acoustic space communicated with the first acoustic space is formed by the first through-hole formed in the internal substrate, the air is more than that in the case of only the first acoustic space. The volume of the chamber (cavity) increases. Therefore, the amplitude of the vibration film is increased and the sensitivity is improved.

  The mounting board may have a second through hole, and the second acoustic space may be communicated with the external space through the second through hole. Thereby, since the microphone unit can collect sound from the mounting board side, for example, when applied to a mobile phone or the like, the microphone unit can be arranged on the same side as the side where the battery is arranged with respect to the mounting board. It becomes possible. For this reason, it is possible to save the space on the back surface side (the side on which the microphone unit is not mounted) of the mounting substrate where thinning is desired.

  In this case, the microphone unit is provided in a case with a hole having a hole at the bottom in the cylindrical member, and a sealed space is formed to communicate the hole of the case with the hole and the other opening of the cylindrical member. It is preferable. Thereby, the capacity | capacitance of an air chamber becomes large and a sensitivity is improved more.

  It is preferable that the connection terminal is constituted by a coil spring and is in pressure contact with the mounting substrate. As a result, for example, the microphone unit can be mounted on a mounting substrate in which a plurality of connection conductors connected to the connection terminal are concentrically arranged (bull's-eye arrangement), and there is no need to consider the directionality of the connection terminal. Therefore, the microphone unit can be easily mounted. Further, for example, the microphone unit can be mounted without using an adhesive by holding the electronic device casing in a state of being pressed against the mounting substrate.

  An electronic apparatus according to the present invention includes the above microphone unit mounting structure.

  According to the present invention, it is possible to realize an electronic device with good sensitivity of the microphone unit even when it is downsized.

  The microphone unit mounting method of the present invention is connected to a cylindrical member that houses an electret condenser type microphone unit and an internal substrate with a through hole that has an element for operating the microphone unit in the cylindrical member. It has a connection terminal and a mounting board that can be electrically connected to the connection terminal. The microphone unit is mounted on the mounting board so that the opening of the cylindrical member is closed, and the microphone board is sandwiched between The first and second acoustic spaces communicating with each other through the through hole are formed.

  According to the present invention, since the volume of the air chamber is increased, the amplitude of the diaphragm is increased, and the sensitivity of the microphone unit can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the mounting structure of the microphone unit which can improve the sensitivity of a miniaturized microphone unit, the electronic device provided with the same, and the mounting method of a microphone unit can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted. In the following embodiments, a mobile phone will be described as an example of an electronic device having a microphone unit mounting structure.

  FIG. 1 is a partial cross-sectional view of a mobile phone provided with a microphone unit mounting structure according to a first embodiment of the present invention. In the figure, a mobile phone 1 has a microphone unit 3, a mounting board 4 on which the microphone unit 3 is mounted, and a battery 5 in a casing 2.

  The microphone unit 3 is sandwiched between the mounting substrate 4 and the inner wall surface of the casing 2, and is mounted in a state of being pressed against the mounting substrate 4. In the casing 2, a sound hole 17 is formed (substantially concentrically) in a portion corresponding to a sound hole 8 described later of the microphone unit 3, and the sound S from the external space enters through the sound hole 17, and the sound hole 8. To be guided to.

  The battery 5 is accommodated in a region between the mounting substrate 4 and the casing 2 on the opposite side of the microphone unit 3 with respect to the mounting substrate 4.

  Here, the configuration of the microphone unit 3 will be described.

  The microphone unit 3 includes a microphone unit 20 that performs electroacoustic conversion, a connection terminal 21 for electrically connecting the microphone unit 20 and the mounting substrate 4, and a rubber boot (cylindrical member) 22 that houses the microphone unit 20. And have.

  The microphone unit 20 has a case 6. The case 6 has a wall surface portion (bottom portion) 7 used as a front plate at one end and is formed of a cylindrical metal member (for example, stainless steel) having an opening at the other end. The wall surface portion 7 is formed by pressing. It is formed in a cylindrical shape having a (front plate).

  A sound hole 8 having a predetermined shape (for example, a circular shape) is formed in the wall surface portion 7 of the case 6 to form a sound collecting hole. A vibration film (diaphragm) 9, a spacer 10, a back electrode plate 11, an insulating bush 12, and an internal substrate 13 are mainly accommodated and disposed in the case 6.

  The vibration film 9 is made of a PET (Polyethylene Terephthalate) film having a thickness of about 1.5 μm, and is formed on a vibration film frame (not shown) made of a metal member (for example, phosphor bronze) having a substantially disk shape. It is attached. Au is vapor-deposited on the surface of the vibration film 9 that is bonded to the vibration film frame. A vent hole (through hole) (not shown) for adjusting the atmospheric pressure inside and outside the microphone unit 3 is provided at the center of the vibration membrane 9.

  The back electrode plate 11 is disposed on the rear side of the vibration film 9, that is, on the opening (other end) side of the case 6 than the vibration film 9. The back electrode plate 11 is made of, for example, a metal member (for example, stainless steel) having a substantially square shape and a thickness of about 0.15 mm, and the electret 14 is heat-sealed (laminated) on one surface. Yes. The electret 14 is made of a FEP (Fluorinated Ethylene Propylene) film.

  Further, the back electrode plate 11 is disposed so that the surface on which the electret 14 is heat-sealed faces the vibration film 9. The back electrode plate 11 has an outer diameter set to a value slightly smaller than the inner diameter of the case 6. A cylindrical hole having a diameter of about 0.8 mm is formed at the center of the back electrode plate 11. This hole also functions as a back pressure adjusting hole for communicating the space on both sides of the back electrode plate 11.

  The back electrode plate 11 is formed by punching into a substantially triangular shape in a state where the electret 14 is heat-sealed to a constituent base material. After the punching process is performed and the back electrode plate 11 is formed, the electret 14 is polarized by corona discharge or the like so as to have a predetermined surface charge (for example, about −360 V).

  A spacer 10 is disposed between the back electrode plate 11 and the diaphragm 9. The spacer 10 is made of stainless steel or the like and has a thickness of about 25 μm. As a result, the vibrating membrane 9 and the back electrode plate 11 (electret 14) are arranged with a predetermined interval (about 25 μm) through the spacer 10. A capacitor portion is formed by the vibration film 9 and the back electrode plate 11.

  The insulating bush 12 is a cylindrical member made of synthetic resin having insulating properties, and its outer diameter is set to be substantially the same as the inner diameter of the case 6, and the inner diameter is the same as the outer diameter of the back electrode plate 11. It is set to almost the same value. The back electrode plate 11 and the contact spring 23 are arranged on the inner peripheral side of the insulating bush 12. At that time, the back electrode plate 11 is elastically pressed toward the spacer 10 by the contact spring 23.

  The contact spring 23 is a cylindrical cap member formed of a bottom portion formed of a donut-shaped planar member and a ring-shaped cylindrical portion, formed of a metal such as SUS, and the connection portion and the back electrode on the internal substrate 13. This is a conductive member for electrically connecting the plate 11.

  In the contact spring 23, three raised springs, which are flat springs with the bottom cut and raised, are equally arranged on the circumference of the bottom. On the outer peripheral side of each of the cut-and-raised plate springs, straight portions that are linearly cut and raised for making contact with the back electrode plate 11 exist. In addition, the straight portion is provided so as to be parallel to the cut-and-raised base portion that is a fold of the root portion cut and raised from the bottom portion and cut and raised the leaf spring.

  The internal substrate 13 has on its surface a JFET (Junction Field-Effect Transistor) chip as an impedance converter that converts the change in capacitance between the vibrating membrane 9 and the back electrode plate 11 (capacitor portion) into electrical impedance. 15. A noise capacitor 16 is mounted and arranged. In addition, a varistor or the like may be mounted. Further, an internal substrate through hole 18 having a predetermined shape and size is formed in a portion of the surface of the internal substrate 13 where the JFET chip 15 and the noise capacitor 16 are not mounted.

  As shown in FIG. 2, the connection terminal 21 is concentrically arranged with a predetermined interval on the outer peripheral side of the first connection terminal 24 disposed on the inner peripheral side and the first connection terminal 24. And a second connection terminal 25 provided. The first connection terminal 24 and the second connection terminal 25 are constituted by coil springs. By using the connection terminal 21 as a coil spring in this way, for example, it is possible to mount on a mounting substrate in which a plurality of connection conductor portions connected to the connection terminal 21 are arranged concentrically. Therefore, it is not necessary to consider the directionality of the connection terminal 21, so that the microphone unit 3 can be easily mounted.

  The rubber boot 22 is made of silicone rubber, elastomer, or the like, and is used to support the microphone unit 20 in a vibration-proof manner. The rubber boot 22 accommodates the microphone unit 20 in a state where the side surface of the case 6 of the microphone unit 20 is covered.

  When mounting the microphone unit 3 as described above, the connection terminal 21 is pressed against the connection conductor (not shown) on the mounting substrate 4 and pressed by the casing 2 (pressed in the direction of arrow P shown in FIG. 1). ), And press the connection terminal against the mounting substrate 4. The microphone unit 3 is held between the casing 2 and the mounting substrate 4 to complete the mounting. Thereby, since the movement to the surface direction of the mounting board | substrate 4 can be suppressed with the urging | biasing force of a spring, a mounting state can be stabilized even if it does not use an adhesive agent. The rubber boot 22 is pressed against the mounting substrate 4 so as to almost completely cover the microphone unit 20 except for the sound hole 8 and its peripheral portion so that there is no gap with the mounting substrate 4.

  When the microphone unit 3 is mounted in this way, the first acoustic space A surrounded by the inner wall of the case 6, the vibration film 9 and the internal substrate 13, the rubber boot 22, the internal substrate 13, and the mounting substrate are installed in the casing 2. A structure in which the second acoustic space B surrounded by 4 is formed is obtained.

  FIG. 3 is a schematic diagram showing only the two spaces A and B by hatching so that the first acoustic space A and the second acoustic space B can be easily recognized. As shown in FIG. 3, the first acoustic space A and the second acoustic space B become one space communicated by the inner substrate through hole 18 of the inner substrate 13 in the casing 2, and the second acoustic space B is a rubber boot. 22 is isolated from the external space G by being in contact with the mounting substrate 4 without a gap. Thereby, in addition to the first acoustic space, the second acoustic space B located outside the case 6 can also be used as an air chamber. For this reason, the air damper effect can be reduced, the amplitude of the vibrating membrane 9 can be increased, and the sensitivity can be improved even with the microphone unit 3 of the same size.

  FIG. 4 is a partial cross-sectional view of a mobile phone provided with a microphone unit mounting structure according to a second embodiment of the present invention. The mounting structure according to this embodiment is different in that the mounting position of the microphone unit 3 is opposite to the mounting position in the mounting structure according to the first embodiment, and the sound in the microphone unit 3 is captured. The direction is opposite. The microphone unit in the present embodiment is the same as that in the first embodiment, and thus detailed description including the configuration is omitted.

  In FIG. 4, the mobile phone 1 includes a microphone unit 3, a mounting board 4 on which the microphone unit 3 is mounted, and a battery 5 in a casing 2.

  The microphone unit 3 is sandwiched between the mounting substrate 4 and the inner wall surface of the casing 2, and is mounted in a state of being pressed against the mounting substrate 4. A mounting substrate through hole 19 is formed in the mounting substrate 4 at a position substantially corresponding to the internal substrate through hole 18 of the microphone unit 3 (substantially on a concentric axis).

  In the casing 2 positioned on the opposite side of the microphone unit 3 with respect to the mounting substrate 4, a hole 27 substantially concentric with the mounting substrate through hole 19 is formed. A seal member 28 formed of rubber or the like is interposed in a portion where the mount substrate through hole 19 and the hole 27 are formed between the mount substrate 4 and the casing 2. A hole 30 that is substantially concentric with the through hole 19 and the hole 27 is formed. As a result, the sound S from the external space is taken in through the hole 27 and is guided to the microphone unit 3 through the hole 30 and the mounting substrate through hole 19 in order.

  The battery 5 is accommodated in a region between the mounting substrate 4 and the casing 2 on the same side as the microphone unit 3 with respect to the mounting substrate 4.

  The mounting of such a microphone unit 3 is performed in the same manner as in the first embodiment. In the mounting structure in the present embodiment, as in the first embodiment, the first acoustic space A surrounded by the inner wall of the case 6, the vibration film 9 and the internal substrate 13, the rubber boot 22, the internal substrate 13, and the like. A second acoustic space B surrounded by the mounting substrate 4 is formed. Thereby, since the air chamber has a large capacity that combines the first acoustic space A and the second acoustic space B, the amplitude of the vibrating membrane 9 can be increased, and the sensitivity can be improved.

  In the present embodiment, when the microphone unit 3 is fixed, a concave portion 32 having a U-shaped cross section is provided in the casing 2, and the concave portion 32 covers the opening 31 of the microphone unit 3. 22 and the recess 32 of the casing 2 form a third acoustic space (sealed space) C isolated from the external space G. The opening 31 in the present embodiment corresponds to the sound hole 8 in the first embodiment.

  FIG. 5 is a schematic view showing only the third acoustic space C by hatching. As shown in FIG. 5, the third acoustic space C is isolated from the external space G by the vibration film 9, the case 6, the rubber boot 22, and the concave portion 32 of the casing 2. For this reason, the third acoustic space C also functions as an air chamber, and the capacity of the microphone unit 3 increases accordingly. Thereby, the amplitude of the vibration film 9 is increased, and the sensitivity is further improved. In the first embodiment, the concave portion 32 is formed in the casing 2 to form the third acoustic space C by the mounting substrate 4 and the concave portion 32, and the mounting substrate through hole 19 is formed in the mounting substrate 4. The second acoustic space B and the third acoustic space C may be communicated. Thereby, in the said 1st Embodiment, since the large capacity air chamber which united the 1st acoustic space A, the 2nd acoustic space B, and the 3rd acoustic space C is realizable, a sensitivity can be improved more.

  By the way, especially in a mobile phone among electronic devices, space is preferentially allocated to an operation button, a liquid crystal, a battery, and the like, so that a space for installing (mounting) a microphone and a speaker becomes narrow. Furthermore, with the recent miniaturization of mobile phones, the installation (mounting) space for microphones and speakers is becoming increasingly narrow.

  The present invention not only improves the sensitivity of the microphone in the case of downsizing, but also begins to solve the problem that the space is too small to be installed in a normal installation location. As a result of intensive research to solve this problem, the present inventors have taken a sound from the back side of the microphone as shown in FIG. It was possible to install a microphone in a place that could not be installed because of the lack of it.

  In general, mobile phones are equipped with a battery on the back side (the side opposite to the liquid crystal screen and operation buttons). According to the mounting structure of the microphone unit according to the second embodiment of the present invention, the bidirectional microphone unit is non-directional that collects sound only from the mounting substrate side, and can be installed on the back side. Become. Such a mounting structure eliminates the need to provide a microphone on the front side (opposite side of the battery with respect to the mounting substrate), so that space can be saved and the mobile phone can be made thinner.

  As mentioned above, although this invention was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment. For example, in the above embodiment, a mobile phone has been described as an example of the electronic device, but the present invention can be applied to various electronic devices such as a headset.

It is a fragmentary sectional view of the mobile telephone provided with the mounting structure of the microphone unit which concerns on 1st Embodiment of this invention. It is the perspective view which looked at the microphone unit shown in FIG. 1 from the terminal electrode side. It is the schematic which showed only the 1st acoustic space and the 2nd acoustic space with the oblique line. It is a fragmentary sectional view of the mobile telephone provided with the mounting structure of the microphone unit which concerns on 2nd Embodiment of this invention. It is the schematic which showed only the 3rd acoustic space by the oblique line.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Mobile phone (electronic device), 2 ... Casing, 3 ... Microphone unit, 4 ... Mounting board, 5 ... Battery, 6 ... Case, 7 ... Wall surface part, 8 ... Sound hole, 9 ... Vibration membrane, 11 ... Back electrode Reference numeral 13: Internal substrate, 18: Internal substrate through hole (first through hole), 19: Mounting substrate through hole (second through hole), 20 ... Microphone unit, 21 ... Connection terminal, 22 ... Rubber boot (tubular member) ), 31 ... opening, A, B, C ... acoustic space, G ... external space.

Claims (6)

A cylindrical member that houses an electret condenser microphone unit;
A connection terminal connected to an internal substrate with a first through hole having an element for operating the microphone unit in the tubular member;
A mounting board capable of electrically connecting the connection terminals;
When the microphone unit is mounted on the mounting board so that the opening of the cylindrical member is closed, the first and second communicating with each other through the first through hole sandwiching the inner board of the microphone unit. 2. A microphone unit mounting structure in which two acoustic spaces are formed. The mounting substrate has a second through hole,
The microphone unit mounting structure according to claim 1, wherein the second acoustic space communicates with an external space through the second through hole. The microphone unit is provided in a case with a hole having a hole in the bottom in the cylindrical member,
3. The microphone unit mounting structure according to claim 2, wherein a sealed space is formed to communicate the hole of the holed case with the other opening of the cylindrical member.   The microphone unit mounting structure according to any one of claims 1 to 3, wherein the connection terminal is configured by a coil spring and is in pressure contact with the mounting substrate.   An electronic apparatus comprising the microphone unit mounting structure according to claim 1. A cylindrical member that houses an electret condenser microphone unit;
A connection terminal connected to an internal substrate with a through hole having an element for operating the microphone unit in the cylindrical member;
A mounting board capable of electrically connecting the connection terminals;
First and second acoustic spaces that are connected to each other through the through-hole, with the microphone unit mounted on the mounting substrate, the inner substrate of the microphone unit being sandwiched so that the opening of the cylindrical member is closed; A microphone unit mounting method comprising: forming a microphone unit.

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