JPS627300A - Electret capacitor microphone - Google Patents

Abstract

PURPOSE:To provide microphone which make it applicable to perform mass production by forming insulating material through a mold package after shaping fixed electrode by using a FET lead frame material. CONSTITUTION:An oscillation film 4 consisting of electret material having metal face formed by a vapour deposition, etc., is stretched on a film ring 3 and is fixed at caulking parts 2b after inserting its film together with respecting components to cylindrical metal cases 2 having sound holes 2a on a top panel. The fixed electrodes 16 of an amplifier block portion play a part of leading inputs of FET and the insulating materials 17 serve the purposes of both as a mold package of FET chips 8c as well as an insulation. In other words, the fixed electrodes 16 shaped at a part of FET lead frame also form the insulating materials 17 by the mold package. Then these devices can be so considered as a component that the number of components decreases in comparison with those of conventional case and assembling is simplified to reduce their material expenses and also to provide the cheap electret capacitor microphone which is applicable to mass productions.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electret condenser microphone.

BACKGROUND OF THE INVENTION FIG. 6 is a sectional view of a conventional electret condenser microphone. In Fig. 6, 1 is a canvas, 2 is a cylindrical metal case with a sound hole 2a on the top surface, and 3 is a vibrating membrane 4 made of electret material with a metal surface formed by metal vapor deposition, etc., which is stretched to a certain extent. Membrane ring, 5 is a gap spacer, 6 is a fixed electrode, 7 is an insulator, 8 is a le T, 8a is an input lead, 8b is an output lead, 9 is a printed circuit board, 10 is a capacitor gap, 11 is a back air chamber . Output lead 8
b is fixed to the printed circuit board 9 with a soldered portion 9a.

The fixed electrode 6, insulator 7, FET 8, and printed circuit board 9 can be considered as one amplifier block, and each of the above-mentioned components is inserted into the metal case 2 and fixed by the caulking portion 2b.

Problems to be Solved by the Invention The electret condenser microphone configured as described above has a large number of parts, and in particular, the amplifier block, which includes the fixed electrode 6, insulator 7, FET 8, and printed circuit board 9, has as many as four parts. However, assembly is difficult and requires a lot of time, which inevitably increases costs. In addition, the large number of parts makes automatic assembly complicated, requiring a large amount of equipment cost, and also having some drawbacks, which inevitably leads to a decrease in the operating rate.

The present invention eliminates the above-mentioned drawbacks, simplifies configuration and assembly by reducing the number of parts, reduces equipment costs for automatic assembly machines, and improves operating efficiency.

The purpose is to provide an electret condenser microphone that is suitable for mass production, and is inexpensive.

Means for Solving the Problems In order to achieve the above object, the present invention relates to an FET, in which a fixed electrode is formed by a part of its lead frame, and an insulator is formed by a molded package. The insulator and FET are integrated into one component.

Therefore, according to the present invention, by integrating the fixed electrode, insulator, and FET into one component, it is possible to reduce the number of components in the amplifier block section, which is the most difficult to automatically assemble.
It has the effect of being easy to assemble.

EXAMPLE Below, the configuration of an example of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention, and the same parts as in FIG. 6 are designated by the same numbers. In FIG. 1, 8c ij FET chip, 8d is a connection wire between FET chip 8C and output lead 8b.

The difference between FIG. 1 and FIG. 6 is that the fixed electrode 16 of the amplifier block part serves as the input lead of the FET, and the insulator 17 also serves as the mold package of the FET chip 8c. . That is, since the fixed electrode 16 is formed on a part of the lead frame of the FET and the insulator 17 is formed by the mold package, these can be considered as one component.

Therefore, in the first case, the number of parts is reduced to 7 parts (2 parts for the amplifier block), compared to 9 parts in the conventional example.

Figures 2 (a), (b), and (C) show details of the FET configured as shown in Figure 1.
The FET is completed by molding the T chip 8C and using it as an insulator 17, cutting 12 parts of the input side lead frame, cutting 13 parts of the output side lead frame, and bending it as shown in the figure. ′ Assembling the block part.

In Fig. 1, an insulator 17 which is a molded package of river π
Since the back air chamber 11 is formed by the printed circuit board 9 and the back air chamber 11, an acoustically stable configuration can be achieved. of course,
Other methods are also possible.

FIG. 4 shows the state before cutting from the PET lead frame in FIG. 1.

FIG. 5 is a sectional view showing another embodiment of the present invention.
In the figure, the capacitor gap 10 is constructed by eliminating the gap spacer 5 in FIG. In the case of FIG. 5, the number of parts can be further reduced to 6, resulting in even greater effects.

Effects of the Invention As described above, according to the present invention, the number of components in the amplifier block can be reduced by forming a fixed electrode by using a part of the lead frame of the FET and forming an insulator by using a molded package. Assembly is simplified and material costs can be reduced, and the automatic assembly machine can also have a simple configuration, reducing equipment costs and improving operating rates. In other words, it is possible to obtain an effect of making the electret condenser microphone suitable for mass production and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electret condenser microphone according to an embodiment of the present invention, FIG. 2(a) is a top view showing details of the PET in FIG. 1, FIG. 2(b) is the same sectional view, Figure (C) is a bottom view of the same, Figure 3 is an exploded view showing how to assemble the amplifier block part in Figure 1, Figure 4 is a top view including the lead frame part of FF1iT in Figure 1, and Figure 5 is FIG. 6 is a sectional view showing another embodiment of the present invention, and FIG. 6 is a sectional view showing a conventional electret condenser microphone. 4... Vibration membrane, 5... Gap spacer, 8b-1
fj force lead, 8C...FET chip, 8d...
Connection wire, 9... Printed circuit board, 16... Fixed electrode, 17... Insulator. Name of agent: Patent attorney Toshio Nakao and 1 other person4.
・Kenkangen S...4-・1'''rA pay 8b・Output lead 8(,-FET menasof 0 8d...I judge it. Figure 3 Figure 4

Claims (2)

[Claims] (1) A fixed electrode is formed by a part of a lead frame, and a vibrating membrane made of an electret material and an FET with an insulator formed by a molded package is provided, and the vibrating membrane is fixed opposite to the fixed electrode. An electret condenser microphone. (2) The electret condenser microphone according to claim 1, wherein one or more convex portions are formed on the fixed electrode.