JP3479464B2 - Unidirectional electret condenser microphone - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unidirectional electret condenser microphone (hereinafter abbreviated as unidirectional ECM), and particularly, it is suitable for unidirectional ECM by finely adjusting acoustic resistance. It relates to a unidirectional ECM suitable for imparting sensitivity.

[0002]

2. Description of the Related Art A conventional example will be described with reference to FIG. Figure 3
In, the capsule 4 is made of a cylindrical body made of a metal material such as aluminum. One end surface of the capsule 4 is closed by a front plate 41 thereof. At the center of the front plate 41, the front sound hole 4
2 is formed. A cloth 5 is provided on the outer surface of the front plate 41.
Is attached. The capsule 4 accommodates the vibrating membrane 1 attached to the vibrating membrane ring 2 made of a metal material, and the vibrating membrane ring 2 is in electromechanical contact with the front plate 41. 3 indicates a back plate. A plurality of back electrode holes 31 are formed through the central portion of the back electrode plate 3. An electret dielectric film 32 is formed on the upper surface of the back electrode plate 3 by adhesion. Reference numeral 7 denotes a ring-shaped spacer made of an insulating material. The vibrating film 1 is attached so as to face the electret dielectric film 32 on the upper surface of the back electrode 3 via the spacer 7. Reference numeral 8 is a back pole holder made of an insulating material. A step portion 81 is formed on the upper end of the back electrode holder 8 over the entire circumference, and the back electrode plate 3 is fitted and fixed thereto. A back electrode chamber 82 is formed in the center of the back electrode holder 8. 9 is IC
It is a chip and is attached and fixed in the back electrode chamber 82. A lead wire 91 is connected to the lower surface of the back electrode holder 8 and I
It is connected to the C chip 9. An output lead wire 92 is further led out from the IC chip 9. Reference numeral 83 is a back electrode plate sound hole formed on the bottom wall of the back electrode holder 8. 10 is a cross, 6
Indicates a printed circuit board. The output lead wire 92 of the previous IC chip 9 is circuit-connected to the printed circuit board 6. The printed circuit board 6 also has a rear surface sound hole 61 communicating with a back electrode plate sound hole 83 formed in the bottom wall of the back electrode holder 8. Although detailed description is omitted, in the above unidirectional ECM, the vibration film 1 is eventually connected to the printed circuit board 6 through the vibration film ring 2 made of a metal material and the capsule 4 made of a metal material. The back electrode plate 3 is circuit-connected to the printed circuit board 6 via the IC chip 9.

[0003]

The directivity characteristic of the unidirectional ECM is set by adjusting the magnitude of the acoustic resistance formed. Then, depending on the shape and size of the case of the mobile phone or other electronic device in which the unidirectional ECM is housed and attached, the mouth, which is the sound source of the speaker, corresponds to the directional axis of the attached unidirectional ECM. There are also cases in which proper positioning cannot be performed. In this case, it is necessary to improve the sensitivity of the ECM by assigning and setting the directional characteristic showing the optimum input characteristic to the sound source of the speaker not located on the directional axis to the unidirectional ECM itself. This directional characteristic is set by adjusting the magnitude of the acoustic resistance of the ECM.

By the way, as the unidirectional ECM, in addition to the above-mentioned conventional examples, Japanese Utility Model Laid-Open No. 57-155890,
Although many are known as described in Japanese Utility Model Laid-Open No. 64-52397, it is hard to say that all of them are easy to adjust the acoustic resistance. That is, regarding the components directly involved in forming the acoustic resistance in the above-described conventional example, these are at least the back electrode holder 8, the cloth 10, and the printed circuit board 6. Therefore, unidirectional ECM
To adjust and set the directivity of
Focusing on components, the shape and dimensions of the sound holes of the back electrode holder 8 and the printed circuit board 6 and the number of sound holes formed can be adjusted and set, and the material, the coarseness and the thickness of the cloth 10 can be adjusted. It is necessary, and the number of parts to be adjusted and changed is too large, and it is not easy to precisely adjust the acoustic resistance.

The present invention provides a printed circuit board which is crimped to the open end of a capsule forming a unidirectional ECM.
The present invention provides a unidirectional ECM that solves the above-mentioned problems by forming and imparting CM acoustic resistance.

[0006]

According to a first aspect of the present invention, there is provided a capsule 4 made of a cylindrical body made of a metal material, and a front sound hole 42 is formed at the center of a front plate 41 of the capsule. In a unidirectional electret condenser microphone in which an electret dielectric film 32 constituting a capacitor is housed inside the capsule 4 and the open end of the capsule 4 is closed by the printed board 6, the printed board 6 is printed on the upper surface. Top metal foil 65 for forming wiring
An upper substrate 602 made of an insulating material deposited on the lower surface and a lower metal foil 63 deposited on the lower surface and an intermediate metal foil 64 deposited on the upper surface made of an insulating material on the lower side The substrate 601 and the lower surface of the upper substrate 602 and the surface of the intermediate metal foil 64 are bonded to each other,
A part of the center portion of the intermediate metal foil 64 is removed and the space 64 is removed.
1 is formed, the bottom surface of the space 641 and the lower substrate 601.
A unidirectional electret condenser microphone having a lower sound hole 611 communicating with the lower surface of the upper substrate 602 formed in the lower substrate 601, and an upper sound hole 612 communicating the upper surface of the upper substrate 602 with the space 641 formed in the upper substrate 602. did.

According to a second aspect of the present invention, in the unidirectional electret condenser microphone according to the first aspect, the back electrode holder 8 made of an insulating material is fitted and fixed to the back electrode plate 3 constituting one electrode. The back electrode holder 8 is provided with a conductive ring 33 which is inscribed in the back electrode holder 8 and electrically connects the back electrode holder 8 and the printed circuit board 6 to each other. A unidirectional electret condenser microphone housed in a back electrode chamber 82 formed inside 8 and attached and fixed to the printed circuit board 6 was constructed.

Further, claim 3: claim 1 and claim 2
In the unidirectional electret condenser microphone described in any of the above, a unidirectional electret condenser microphone is formed in which the lower surface metal foil of the lower substrate forming the printed wiring is formed on almost the entire surface of the lower substrate. . Further, claim 4 is the unidirectional electret condenser microphone according to any one of claims 1 to 3, wherein the metal foil is a copper foil.

Claim 5: Claims 1 to 4
In the unidirectional electret condenser microphone described in any of the above, a single copper foil formed on the lower surface of the upper substrate 602 symmetrically with the intermediate copper foil 64 formed on the upper surface of the lower substrate 601. A directional electret condenser microphone was constructed.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the examples of FIGS. FIG. 1 is a view showing a cross section of the embodiment, and FIG. 2 is an exploded perspective view of a printed circuit board. The capsule 4 is composed of a cylindrical body made of a metal material such as aluminum. One end surface of the capsule 4 is closed by a front plate 41 thereof. However, a front sound hole 42 is formed at the center of the front plate 41. The capsule 4 accommodates the vibrating membrane 1 attached to the vibrating membrane ring 2 made of a metal material, and the vibrating membrane ring 2 is in electromechanical contact with the front plate 41. A plurality of back electrode holes 31 are formed through the back electrode plate 3. An electret dielectric film 32 is formed on the upper surface of the back electrode plate 3 by adhesion. The vibrating film 1 is attached so as to face the electret dielectric film 32 on the upper surface of the back electrode plate 3 via a ring-shaped spacer 7 made of an insulating material. A step portion 81 is formed on the upper end portion of the back electrode holder 8 made of an insulating material over the entire circumference, and the back electrode plate 3 is fitted and fixed thereto. Inside the back electrode holder 8 is a back electrode chamber 82.
Are formed. The IC chip 9 is located in the back electrode chamber 82 and is attached and fixed to the printed circuit board 6 described later. Here, it is assumed that the IC chip 9 includes a capacitor for removing high frequency noise, an inductor, and other circuit elements. The lower surface of the back electrode holder 8 is attached and fixed to the printed circuit board 6 via the conductive ring 33.

To assemble a unidirectional ECM, a back electrode plate in which a vibrating membrane ring 2, a vibrating membrane 1 and a spacer 7 are housed in a capsule 4 and an electret dielectric film 32 is adhered and formed on an upper surface thereof. 3 is fitted into the stepped portion 81 of the back electrode holder 8 and integrated into the capsule 4, and the printed circuit board 6 is further brought into contact with the lower end surface of the back electrode holder 8 to form the rear end portion of the capsule 4. The assembly is completed by bending and crimping the bottom surface of the printed circuit board 6. In this case, the IC chip 9 is electromechanically preliminarily connected and fixed to the upper surface of the printed board 6.

Referring particularly to FIG. 2, FIG. 2A is a view showing a cross section of the printed circuit board 6 of the present invention.
(B) is an exploded perspective view of the printed circuit board of FIG. 1. Figure 2
In, the printed circuit board 6 of the present invention comprises a lower substrate 601 and an upper substrate 602 made of an insulating material. On the lower surface of the lower substrate 601, a lower surface copper foil 63 as an example of a lower surface metal foil made of a metal material is adhered and formed. The lower surface copper foil 63 is actually subjected to an etching treatment to form an ECM output terminal, a ground terminal and a printed wiring. An intermediate copper foil 64 is adhered and formed on the upper surface of the lower substrate 601. The intermediate copper foil 64, which is actually subjected to etching treatment, is partially formed into a printed wiring. Then, the central portion is partially removed to form a space 641. In this embodiment, the space 641 is removed in a ring shape. The bottom surface of this space 641 and the lower substrate 601
The lower surface of the is communicated with the lower sound hole 611. The lower surface copper foil 63 and the intermediate copper foil 64 are electrically connected via the through hole 613. On the upper surface of the upper substrate 602, the upper surface copper foil 6
5 is adhered and formed. The upper surface copper foil 65 is divided into an output terminal and a ground terminal. The upper substrate 602 is further formed with an upper sound hole 612, and through holes 623 are separately formed in the central portion and the outer peripheral portion.
The intermediate copper foil 64 and the upper copper foil 65 constitute a printed wiring, and a part of the lower copper foil 63 constitutes an output terminal and a ground terminal. The output terminal and the ground terminal formed of the lower surface copper foil 63 are formed in a ring shape in the embodiment, but the shape is not limited to the ring shape.

The above lower substrate 601 and upper substrate 602 are mutually joined and integrated with one printed circuit board 6 via the intermediate copper foil 64 and the lower surface of the upper substrate 602. The space 641 formed by this joining and integration communicates with the lower surface of the lower substrate 601 through the lower sound hole 611, and the upper sound hole 6 is formed.
12 communicates with the upper surface of the upper substrate 602. Therefore, the lower surface of the lower substrate 601 and the upper surface of the upper substrate 602 have a lower sound hole 611, a space 641, and an upper sound hole 612.
Through the. That is, when the printed circuit board 6 shown in FIG. 2A is incorporated in the ECM as shown in FIG. 1, the back electrode chamber 82, the lower surface of the printed circuit board 6, the lower sound hole 611, the space 641, and the upper sound hole. Through 612, an air flow passage is formed to communicate with each other and allow air to flow.
The air flow passage operates as an acoustic resistance that changes the resistance to the circulating air by adjusting its shape and structure.

In the above embodiment, the intermediate copper foil 64 is formed only on the upper surface of the lower substrate 601, but an intermediate copper foil similar to this intermediate copper foil 64 is symmetrically formed on the lower surface of the upper substrate 602. Can be formed to implement the invention. As a result, the lower substrate 601 and the upper substrate 602 are electrically coupled by adhesion and contact between the two intermediate copper foils with the conductive paint.

The magnitude of the acoustic resistance of this air flow passage, which operates as the acoustic resistance, is determined by the lower sound hole 611 and the upper sound hole 61.
It depends on the diameter of 2 and the number formed. Then, the acoustic resistance changes by changing the space shape, the foil thickness, and the space width of the intermediate copper foil 64 forming the space 641. The intermediate copper foil 64 and the upper surface copper foil 65 form a printed wiring, and the acoustic resistance changes even by this wiring. That is, the present invention is directed to the lower sound hole 61.
1, the space 641, the upper sound hole 612, and the above acoustic resistance setting conditions are adjusted to set an appropriate acoustic resistance. In order to adjust and set the acoustic resistance, first, the conditions of the foil thickness and the space width of the intermediate copper foil 64 are specified. Under this condition, the lower sound hole 611 and the upper sound hole 6
Adjust the diameter and number of 12 to change the acoustic resistance. The condition of the foil thickness and the space width of the intermediate copper foil 64 is set to a condition different from the above conditions, and the diameter and the number of the lower sound hole 611 and the upper sound hole 612 are adjusted and changed under this condition. Can be set. The number and diameter of the lower sound holes 611 can be formed even after the unidirectional ECM is assembled.

To explain the operation of the unidirectional ECM, the back electrode plate 3 made of a metal material on which the electret dielectric film 32 is formed constitutes one electrode, and the vibrating film 16 made of a metal material is used. It constitutes the other electrode. The back electrode plate 3, which is one of the electrodes, is connected to the IC chip 9 via the conductive ring 33 and the printed circuit board 6. This IC chip 9 is finally circuit-connected to the lower surface of the printed board 6 via a copper foil. The vibrating membrane 1, which is the other electrode, is finally connected to the lower surface of the printed circuit board 6 via the vibrating membrane ring 2 made of a metal material and the capsule 4. When acoustic vibration enters the ECM through the front sound hole 42 formed in the front plate 41, the vibrating film 1 vibrates due to this, and the vibrating film 16 and the back electrode plate 3 corresponding to this vibration. The electrical capacity between changes,
This change is output as an electric signal.

[0017]

As described above, the acoustic resistance of the unidirectional ECM of the present invention can be finely adjusted. In this case, the components related to the setting condition of the acoustic resistance are limited only to the printed circuit board, and it is sufficient to adjust and change only this, so the setting of the acoustic resistance is simplified.
Especially, the number and diameter of the lower sound holes are unidirectional.
It can also be done after assembling the M, which is advantageous for further fine tuning of the ECM end product. Further, since the number and diameter of the lower sound holes can be changed even after the unidirectional ECM is incorporated in the electronic device, the acoustic resistance can be finely adjusted to optimize the unidirectional ECM. It is suitable for imparting sensitivity.

In the unidirectional ECM of the present invention, a conductive ring is inscribed in the back electrode holder that constitutes one of the electrodes to electrically connect the back electrode holder to the printed circuit board, and the acoustic resistance is reduced. The back pole chamber in the back pole holder can be made relatively large by not using the cloth forming the back pole holder. As a result, it is possible to configure the acoustic resistance in the rear of the back electrode chamber, that is, in the printed circuit board to form a small ECM exhibiting high sensitivity and unidirectionality.

Further, since the back electrode chamber can be used largely, an IC chip including a capacitor and an inductor for removing high frequency noise can be built in, and E
It is possible to configure a solderless type small ECM that does not require soldering outside the CM capsule. Further, the lower surface copper foil of the lower substrate forming the printed wiring is formed on almost the entire surface of the lower substrate separately from the output terminal and the ground terminal, which is suitable for removing induced noise.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of an example.

FIG. 2 is a diagram illustrating details of a part of FIG.

FIG. 3 is a diagram illustrating a conventional example.

[Explanation of symbols]

1 vibrating membrane 32 electret dielectric film 4 capsules 41 Front plate 42 front sound hole 6 printed circuit boards 601 Lower substrate 602 upper substrate 61 Rear sound hole 611 lower sound hole 612 Upper sound hole 613 through hole 623 through hole 63 Bottom copper foil 631 opening 64 Intermediate copper foil 641 space 65 Top copper foil

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryuji Awamura 38 2430 Nakayama, Kurate-cho, Kurate-gun, Fukuoka Prefecture Hosiden Kyushu Co., Ltd. −35035 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04R 19/04 H04R 1/32 320

Claims (5)

(57) [Claims] 1. An electret dielectric body comprising a capsule made of a cylindrical body of a metal material, a front sound hole being formed at the center of a front plate of the capsule, and a vibrating membrane and a condenser facing the vibrating membrane to constitute a capacitor. In a unidirectional electret condenser microphone in which the film is housed in a capsule and the open end of the capsule is closed by a printed circuit board, the printed circuit board is made of an insulating material on which the upper surface metal foil that forms the printed wiring is deposited. The upper substrate and the lower substrate made of an insulating material on which the lower surface metal foil is adhered and formed on the lower surface and the intermediate metal foil which forms the printed wiring on the upper surface are adhered and formed. The middle part of the intermediate metal foil is partially removed to form a space, and the bottom side of the space communicates with the bottom surface of the lower substrate. Forming a hole on the lower substrate, unidirectional electret condenser microphone, characterized in that the upper sound hole for communicating the upper surface and spaces of the upper substrate formed on the upper substrate. 2. The unidirectional electret condenser microphone according to claim 1, further comprising a back pole holder made of an insulating material to which a back pole plate constituting one electrode is fitted and fixed. It is equipped with a conductive ring which is inscribed and electrically connects the back electrode holder and the printed circuit board, and accommodates an IC chip including a high frequency noise removing capacitor, an inductor and other circuit elements in a back electrode chamber formed inside the back electrode holder. A unidirectional electret condenser microphone, which is mounted and fixed on a printed circuit board. 3. The unidirectional electret condenser microphone according to any one of claims 1 and 2, wherein the lower surface metal foil of the lower substrate forming the printed wiring is provided on substantially the entire surface of the lower substrate. A unidirectional electret condenser microphone characterized by being formed. 4. The unidirectional electret condenser microphone according to any one of claims 1 to 3, wherein the metal foil is a copper foil. 5. The unidirectional electret condenser microphone according to any one of claims 1 to 4, wherein the lower surface of the upper substrate is symmetrical with the intermediate copper foil formed on the upper surface of the lower substrate. A unidirectional electret condenser microphone characterized in that an intermediate copper foil is formed on the.