JP4003870B2 - Electret condenser microphone - Google Patents

Description

[0001]
[Field of the Invention]
The present invention relates to an electret condenser microphone in which an electret material film on which an electrode film is formed is configured as a vibrating membrane unit, and more particularly to an electret condenser microphone that can increase detection sensitivity by reducing the stray capacitance of the microphone section.
[0002]
[Prior art]
A conventional electret condenser microphone in which an electret film on which an electrode film is formed as a vibrating membrane unit is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-247200, and will be described below with reference to FIGS. 3 is a cross-sectional view of an electret condenser microphone showing a conventional example, FIG. 4 is an exploded perspective view of the diaphragm unit in FIG. 3, 100 is an electret condenser microphone, 110 is a metal case, and an acoustic hole 110a on the front side. A fixed electrode 110b is provided on the inner surface side.
[0003]
Reference numeral 120 denotes a vibrating membrane unit, which is configured by fixing a vibrating membrane 140 made of an electret material film having an electrode film 130 to a metal support frame 150. The metal case 110 and the vibrating membrane unit 120 are stacked and disposed via a spacer 160, whereby the electret condenser microphone 100 is configured by the electrode film 130 and the fixed electrode 110b. Reference numeral 170 denotes a circuit board on which electronic elements 180 a and 180 b for processing the detection signal of the electret condenser microphone 100 are mounted. Reference numeral 190 denotes an output electrode for taking out the output signal of the microphone.
[0004]
The operation of the electret condenser microphone 100 having the above configuration is such that the electrode film 130 is provided on the surface, the vibration film 140 made of an electret material film, and the inner surface side of the metal case 110 having the function of the fixed electrode 110b form the spacer 160. A capacitor is formed by sandwiching. When the vibrating membrane 140 is displaced by the vibration of air applied from the acoustic hole 110a of the metal case 110, the capacitor converts the displacement into an electric signal, which is guided to the circuit board 170, and the electronic element 180a. , 180 b and output from the output electrode 190 led to the back surface of the circuit board 170.
[0005]
In the operation of the electret condenser microphone 100, the diaphragm unit 120 is electrically connected to the circuit board 170 via the metallic support frame 150, and the fixed electrode 110b is electrically connected to the circuit board 170 via the metal case 110. Connected. FIG. 4 is an exploded perspective view of the diaphragm unit 120 in FIG. 3, and the vibration film 140 having the electrode film 130 formed on the entire surface is fixed to the support frame 150 with the electrode film 130 facing down. A membrane unit 120 is configured.
[0006]
[Problems to be solved by the invention]
In the conventional electret condenser microphone 100 shown in FIG. 3, the area of the electrode film 130 and the vibration film 140 constituting the vibration film unit 120 is substantially the same size, so the fixed electrode 110 b and the vibration film unit 120 are the same. The capacitance (capacitor) formed by the electrode film 130 constituting the electrode is formed by the effective capacity formed by the operable region 140a of the vibration film 140 and the non-operation region 140b in which the vibration film 140 is constrained by the support frame 150. It becomes a combined capacity with the stray capacity.
[0007]
That is, the sensitivity of the electret condenser microphone 100 corresponds to the total capacity formed by the fixed electrode 110b and the vibrating membrane 140 and the operable region 140a of the vibrating membrane 140 (the cavity 150b of the support frame 150 shown in FIG. 4). The floating capacitance formed by the non-operating region 140b of the vibrating membrane 140 (the portion corresponding to the frame portion 150a of the support frame 150 shown in FIG. 4) There is a problem that the sensitivity of the electret condenser microphone 100 decreases as the amount increases.
[0008]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an electret condenser microphone that does not reduce sensitivity.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a vibrating membrane unit having a vibrating membrane made of an electret material film fixed to a support frame, and an electrode membrane formed on the vibrating membrane, and a fixed electrode facing the electrode membrane When, in the electret condenser microphone having a circuit board that an electronic element is mounted for processing a detection signal of the vibration film unit, as well as constituting the support frame in the vibrating membrane unit with the insulating member, the area of the electrode film the It is characterized by being approximately equal to the area inside the support frame .
[0010]
By laminating and arranging a vibration case unit having a metal case, a vibration film made of an electret material film fixed to an insulating support frame, and an electrode film formed on the vibration film via a spacer, An electret condenser microphone is configured with a part of the metal case facing the electrode film as a fixed electrode, and the area of the electrode film in the diaphragm unit is approximately equal to the area inside the support frame. And
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 is a cross-sectional view of an electret condenser microphone according to the present invention, FIG. 2 is an exploded perspective view of the diaphragm unit in FIG. 1, 10 is an electret condenser microphone, 11 is a metal case, an acoustic hole 11a on the front side, an inner surface A fixed electrode 11b is provided on the side.
[0012]
Reference numeral 12 denotes a vibrating membrane unit, which is configured by adhering a vibrating membrane 14 made of an electret material film having an electrode film 13 to an insulating support frame 15. The metal case 11 and the diaphragm unit 12 are stacked and disposed via a spacer 16, whereby the electret condenser microphone 10 is configured by the electrode film 13 and the fixed electrode 11 b. Reference numeral 17 denotes a circuit board on which electronic elements 18a and 18b for processing the detection signal of the electret condenser microphone 10 are mounted. Reference numeral 19 denotes an output electrode for taking out the output signal of the microphone.
[0013]
FIG. 2 is an exploded perspective view of the diaphragm unit 12 in FIG. 1. The support frame 15 is formed of an insulating material such as resin, and a conductive electrode 15c is provided through a part of the frame portion 15a. The vibrating membrane 14 is formed with an electrode film 13 having an area substantially equal to or slightly smaller than the hollow portion 15b of the support frame 15, and a connection electrode 13a electrically connected to the electrode film 13 is provided with the support film 13a. It is formed at a position corresponding to the conductive electrode 15 c of the frame 15.
[0014]
Then, the vibrating membrane 14 is fixed to the support frame 15 with the electrode film 13 facing down to constitute the vibrating membrane unit 12, and the electrode film 13 is connected to the circuit via the connection electrode 13a and the conductive electrode 15c. The fixed electrode 11 b is electrically connected to the circuit board 17 through the metal case 11.
[0015]
Since the basic operation of the electret condenser microphone 10 is the same as that of the electret condenser microphone 100, a duplicate description is omitted. The electrode film 13 is formed only in the operable region 14a of the vibrating membrane 14 constituting the portion 12 (the portion corresponding to the cavity 15b of the support frame 15 shown in FIG. 2), and the non-operating region 14b of the vibrating membrane 14 (in FIG. The electrode film 13 is not formed on a portion corresponding to the frame portion 15a of the support frame 15 to be shown, and the support frame 15 is formed of an insulating member.
[0016]
The electret condenser microphone 10 of the present invention has no metal member (the electrode film 13 is not formed) in the non-operating region 14b of the diaphragm 14 constituting the diaphragm unit 12 due to the difference in configuration from the conventional example. Further, since the support frame 15 is an insulating member) and the stray capacitance does not exist in the non-operating region 14b, it is possible to improve sensitivity reduction as a microphone.
[0017]
The electrode film 13 and the connection electrode 13a can be simultaneously formed on the vibration film 14 using a mask, and the conductive electrode 15c in the support frame 15 is formed on the frame 15a through the inner wall of the cavity 15b. It can be performed by a method such as printing a conductive paint on the lower surface.
[0018]
【The invention's effect】
As described above, according to the present invention, the support frame constituting the diaphragm unit is formed of an insulating material, and the area of the electrode film formed on the diaphragm made of the electret material film is defined as the operable area of the diaphragm. By making the size substantially equal, it was possible to improve the sensitivity reduction of the condenser microphone and provide an electret condenser microphone having excellent acoustic characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of an electret condenser microphone of the present invention.
2 is an exploded perspective view of a diaphragm unit constituting the electret condenser microphone of FIG. 1. FIG.
FIG. 3 is a cross-sectional view of a conventional electret condenser microphone.
4 is an exploded perspective view of a diaphragm unit constituting the electret condenser microphone of FIG. 3. FIG.
[Explanation of symbols]
10, 100 Electret condenser microphone 11, 110 Metal case 12, 120 Vibrating membrane unit 13, 130 Electrode membrane 14, 140 Vibrating membrane 14a, 140a Vibrable region 14b, 140b Non-vibrating region 15, 150 Support frame 16, 160 Spacer 17, 170 Circuit board

Claims (3)

A vibration membrane unit having a vibration film made of an electret material film fixed to the support frame, an electrode film formed on the vibration film, a fixed electrode facing the electrode film, and the vibration film unit In an electret condenser microphone having a circuit board on which an electronic element for processing the detection signal is mounted, the support frame in the vibration membrane unit is formed of an insulating member, and the area of the electrode film is the area inside the support frame electret condenser microphone, characterized in that substantially equal when.   The electret condenser microphone according to claim 1, wherein the support frame is provided with a conductive electrode for electrically connecting the electrode film to the circuit board.   By laminating and arranging a vibration case unit having a metal case, a vibration film made of an electret material film fixed to an insulating support frame, and an electrode film formed on the vibration film via a spacer, An electret condenser microphone is configured with a part of the metal case facing the electrode film as a fixed electrode, and the area of the electrode film in the diaphragm unit is approximately equal to the area inside the support frame. Electret condenser microphone.

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