JPH02149198A - Electlet condenser microphone - Google Patents

Abstract

PURPOSE:To simplify the structure and to facilitate the manufacture through automation by insulating a metallic case and a metallic ring with an expanded part of a diaphragm adhered to one end of a cylindrical metallic ring and forming a capacitor between the diaphragm and the ceiling of the metallic case. CONSTITUTION:The ceiling of the metallic case 11 is used as a fixed electrode in common together with the metallic case 11 and a diaphragm 13 being the result of metal vapor deposition on one side adhered and fixed to one end of a cylindrical doughnut metallic ring 12 is expanded near the outer circumference of the metallic ring 12 to cover the outer side face of the metallic ring 12. Then the metallic case 11 and the metallic ring 12 are insulated surely and the capacitor 19 is formed between the ceiling of the metallic case 11 and the diaphragm. Thus, number of components is decreased, the structure is simplified and the manufacture resulting from the automation is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the structure of an electret condenser microphone (hereinafter abbreviated as EC'M).

Conventional technology FIG. 5 is a sectional view showing the configuration of a conventional ECM.

In Fig. 5, 1 is a cylindrical metal case having a sound hole 1a on the top surface, and 2 is a metal ring to which a vibrating membrane (electret material) 3 having a metal vapor-deposited film 3a applied on one side is attached and fixed with an adhesive or the like. , 4 is a gap spacer, 5 is a brake hole 5
6 is an insulator, 7 is an FET for impedance conversion, and 7a is an input terminal of the FET 7, which is electrically connected to the fixed electrode 5 by contact or spot welding. 8 is a printed circuit board and FET
The output terminal 7b of No. 7 is connected and fixed by soldering 8a. Each of these parts is inserted into the case 1, and its ends are fixed by caulking parts 1b.

Next, the above embodiment will be briefly explained. In FIG. 5, there is an air layer 9 between the vibrating membrane 3 and the fixed electrode 5, forming a capacitor (capacitance) of about several PF to several tens of PF.

This capacity is determined by the arrival of the sound waves entering from the sound hole 1a.
changes slightly due to vibration. This capacitance change can be electrically taken out via the FET 7.

Although this embodiment shows a case in which an electret material is used for the imaging film 3, there is also a method in which this electret material is attached to the fixed electrode 5.

Also, 1; "ET 7 can obtain the same function as this embodiment even when it is configured externally without being configured internally.

Problems to be Solved by the Invention However, the conventional example described above has problems such as difficulty in automated manufacturing due to the large number of parts and complicated structure.

The present invention is intended to solve these conventional problems.
The purpose is to provide an ECM that has a simple structure, is easy to manufacture by automation, and has good quality.

Means for Solving the Problems In order to achieve the above object, the present invention uses a fixed electrode on the top surface of a cylindrical metal case, and a one-sided metal vapor-deposited electrode that is attached and fixed to one end of a donut-shaped metal ring formed in a cylindrical shape. A vibrating membrane is stretched near the outer periphery of the metal ring and is formed to cover the outer surface of the metal ring, and a capacitor is formed between the fixed electrode and the vibrating membrane. The invention has the following effects due to the above configuration. In other words, the top surface of the metal case is used as a fixed electrode along with the metal case, and instead of an insulator, which was one of the conventional components, a vibrating membrane is attached and fixed to the metal ring near the outer periphery of the metal ring. By covering the outer surface of the stretched metal ring, it is possible to reliably insulate the metal case and the metal ring. As a result, the number of parts can be reduced, resulting in a simpler structure and an ECM that can be easily manufactured through automation.

Example FIG. 1 shows a sectional view of an embodiment of the present invention.

In FIG. 1, the same parts as in FIG. 5 are indicated by the same numbers. In the figure, 11 is a cylindrical metal case, which has a sound hole (braking hole 11a) on the top surface and a convex portion 11C on a part of the inner surface, and this top surface is fixed. 12 is a donut-shaped metal ring formed in a cylindrical shape, and a vibrating membrane 13 formed by metal vapor deposition 13a on one side is fixed to one end by pasting with adhesive or the like, and the convex portion By pressing the vibrating membrane 13 with 11C, a gear knob is formed between the inner surface of the metal case 11 and the vibrating membrane 13,
A capacitor 19 is formed between the metal case 11 and the top surface. Note that the convex portion 11C can also be constructed using a gap spacer similar to the conventional one. metal ring 1
2 will not operate if it shorts with the metal case 11. To prevent this, the vibrating membrane 13 is connected to the metal ring 1.
The metal case 11 is stretched near the outer periphery of the metal case 11 and is formed to cover it along the outer surface 111 of the metal case 11.
The configuration ensures reliable insulation between the metal ring 120 and the metal ring 120. In addition, there is a slight taber li on the inner surface of the metal case 11.
d is provided to prevent a short circuit between the metal case 11 and the metal ring 12. Although there is no problem in the present invention even if this taper lid is not provided, in this embodiment, in order to more reliably prevent the short circuit, It shows.

A concave portion 12a is provided on the opposite surface of the metal ring 12 to the surface on which the vibrating membrane 13 is pasted, and an input terminal 7a of the PET 7 is formed in this portion, and is connected to the output terminal 7 in an airtight manner by contact or the like.
Similarly to the conventional example, output can be taken out via the printed circuit board 8.

These parts are inserted into the metal case 11 and fixed by caulking portions 11b and the like.

FIG. 2 is a perspective view of the metal ring 12 to which the photographic film 13 is attached, and FIG. 3 is a partially enlarged sectional view of the vicinity of the enlarged portion 13b. Metal vapor deposition 1 near the stretched portion 13b
3a is in a state 13C where there is almost no vapor deposition because the vibrating membrane 13 is stretched, and is opposite to the insulator. 13d
Generally, a Teflon-based film is used for the vibrating membrane 13, which is the end portion formed by covering the outer surface of the metal ring with the vibrating membrane, and this film is suitable for use in this embodiment because it stretches well due to its properties.

Figures 4(a) and 4(b) are processing diagrams for performing this bow lengthening process. In the figure (a), the center of the metal ring 12 is determined by a lifting pin 23, the dimension 1 from the upper presser 21 and the lower presser 22 of the film is made to have little variation, and the metal ring 12 is pressed up using a spring 24. (b
) The figure shows a configuration in which the center of the metal ring 12 is determined by an upper presser 25 and a lower presser 26, and a large gap is provided between the lifting pin 27 and the metal ring. Upper presser 2
5. The lower presser 26 is provided with tapers 25a and 26a, respectively, and 47 dimensions are determined by these tapers. Conventionally, film was generally cut using male and female dies, but precision maintenance to match the dies was difficult and it was difficult to cut multiple pieces at once.
According to the method described above, this can be easily carried out. Further, it is possible to make the device thinner, and when the dimensions are the same as the conventional structure, the internal air chamber can be made larger than that of the conventional structure, so that excellent sensitivity can be obtained.

Effects of the Invention As is clear from the above embodiments, the present invention makes it possible to insulate the metal case 11 and the metal ring 12 by using the stretched cut portion of the diaphragm attached to one end of the cylindrical metal ring, and to prevent vibrations. Since the capacitor 19 is formed between the membrane 13 and the top surface of the metal case 11, the structure is simple due to the reduction in the number of parts. It has the advantage of being able to provide

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, FIG. 2 is a perspective view of a metal ring to which a vibrating membrane is attached, FIG. Figure 4 is a schematic diagram of the vibrating membrane stretching process, and Figure 5 is the conventional E
It is a sectional view of CM. 11... Metal case, 12... Metal ring, 13
... Vibrating membrane, 13b... Extended portion of vibrating membrane, 7
...FET, 8...Printed circuit board. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1st
Figure 4 Figure 2 Figure 5 Figure 3

Claims (1)

[Claims] A cylindrical metal case and its top surface are used as one fixed electrode, and a vibrating membrane with metal vapor deposited on one side is fixed to one end of a donut-shaped metal ring formed in the cylindrical shape. An electret condenser microphone in which a vibrating membrane is stretched to cover the outer surface of a metal ring, and a capacitor is configured between the fixed electrode and the vibrating membrane.