JPS6144048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing microphone packing used as a soundproof packing material for built-in microphones used in tape recorders and the like.

As built-in microphones used in tape recorders and the like, there are condenser microphones shown in FIGS. 1 to 4. In the figure, 1 is a metal case with four ventilation holes (sound guide holes) 2 bored in its upper surface, 3 is a case made of an insulating material such as resin and has a hollow part 4, 5 is an electret diaphragm,
Reference numeral 6 denotes an electret fixing plate (back electrode), which is fixed to the upper surface of the resin case 3. Further, 7 is a metal diaphragm ring having electrical conductivity, and the electret diaphragm 5 is fixed to this. The electret diaphragm 5 and the electret fixing plate 6 constitute an electret type acoustic-electric conversion section.

8 is a FET for impedance conversion housed in the hollow part 4 of the resin case 3, and a spring 10 made of a conductive material connected to its gate electrode is attached to the back of the electret fixing plate 6 by its elasticity. The electret fixing plate 6 is connected to the FET 8.
The gate electrode is connected to the gate electrode of the gate electrode.
Reference numeral 11 denotes a soundproof packing (see FIGS. 5 and 6) made of butyl rubber or the like, and is arranged together with a metal spacer 12 between the lower surface of the case 3 and the lower bent portion of the metal case 1. This soundproof packing 11 is provided with recesses 13 and 14 for inserting the lead wires of the FET 8, and the lead wires 15 and 16 of the drain and source electrodes are inserted into the recesses 13 and 14.
is inserted into the As a result, soundproof packing 1
1 are closely attached to the sides of the lead wires 15 and 16, and these structures provide a soundproofing effect. Further, a part of the metal spacer 12 is cut and raised to form a ground electrode 17, and the above-mentioned electret diaphragm 5 has a conductive diaphragm ring 7,
It is electrically connected to a ground electrode 17 via the metal case 1 .

By the way, the packing 11 used as the above-mentioned soundproofing material is generally formed into a sheet of butyl rubber and then used by molding this. Therefore, usually 1
There are many packings 11 on one butyl rubber sheet.
is formed, and each time the packing 11 is used, the packing is peeled off one by one from this rubber sheet.

Therefore, packing 11 itself has a diameter of 4 to 5 mm.
Since the condenser microphone is a very small molded part, it is extremely difficult to assemble the condenser microphone.
Further, in order to automate the mounting of the packing 11 into the metal case 1, when the above-mentioned sheet formed with a plurality of packings 11 is fed to the automatic mounting device by a vibrating circular feeder, the sheet should be flexible and Because of its high elasticity, it is not possible to line up and supply the sheet to the assembly line, and furthermore, the packing 11 formed on the sheet and the packing 11
The positional relationship between the multiple FETs 8 (the multiple FETs are aligned with a predetermined pitch in advance) cannot be accurately controlled on the assembly line, that is, the positioning accuracy is very poor. . This is because the sheet undergoes significant changes due to heat shrinkage, etc., and has large variations.
Therefore, it has become a bottleneck for automation. Therefore, the present invention provides a method for manufacturing a microphone packing that uses special equipment and uses a special method to automate the assembly.

An embodiment of the method according to the present invention and a device (mold) related thereto will be described below with reference to FIGS. 7 to 14, and portions corresponding to those in FIGS. 1 to 6 described above will be described. are denoted by the same reference numerals and redundant explanation thereof will be omitted.

That is, the packing mold according to the present invention has a plurality of through holes 21 having a predetermined shape as shown in FIG.
It consists of an intermediate mold 22 arranged in parallel, and a pair of upper and lower molds 25 and 26 sandwiching the intermediate mold 22 from above and below. In this case, the intermediate mold 22 is formed into a plate shape,
The plurality of through-holes 21 described above are arranged vertically and horizontally with pitches P ₁ and P ₂ , respectively. The intermediate mold 22 also has a plurality of pilot holes 23 and 24 on both sides of the intermediate mold 22 along its longitudinal direction.
is formed, but this pitch is combined with P ₂ mentioned above.

On the other hand, the lower mold 26 of the pair of molds 25 and 26 has a pilot pin 2 as shown in FIG.
8 and 29 are planted and fixed, thereby positioning the intermediate mold 22, that is, inserting it, for example, into the pilot holes 23 and 24 mentioned above. Furthermore, in a state where the intermediate mold 22 is positioned, a so-called counterbore hole 36 is formed in a portion thereof facing each through hole 21 .

Further, the above-mentioned pilot pins 28 and 29 are installed in the upper mold 25 of the pair of molds 25 and 26.
Engagement holes 30 and 31 are formed to face and engage with this, and a plurality of protrusions 37 are further formed to face the plurality of counterbore holes 36 described above. The 7th
As is clear from the figure, a plurality of intermediate molds 22 can be arranged between a pair of upper and lower molds 25 and 26.

Next, a method of forming the packing 11 using this method will be explained with reference to FIG. 9 and subsequent figures.

First, as shown in FIG. 9, the intermediate mold 22 is positioned and placed on the lower mold 26 using the pilot pins 28 and 29, and a molding material such as unvulcanized butyl rubber 27 is placed thereon. The intermediate mold 22 is clamped between a pair of molds 25 and 26 with a necessary pressure (for example, about 200 kg) (see FIG. 10). Of course, at this time, the upper and lower molds 2
5 and 26 are attached to the bottom surface of the upper mold 25, for example.
It is heated to a necessary temperature, that is, a temperature suitable for vulcanization of the butyl rubber 27, using a heater at about 180°C. This clamping time is about 10 minutes. In this case, the butyl rubber 27 is pushed into the through holes 21 of the intermediate mold 22, and the through holes 21 and the upper and lower molds 25, 2
Counterbore hole 36 and protrusion 3 formed on the opposing surface of 6
It is configured in a shape consistent with 7. At this time, a sheet-like portion 38 may be formed on the upper surface of the intermediate mold 22 as shown in the figure, but this is not necessarily necessary.

Thus, the clamping of the upper and lower molds 25 and 26 to the intermediate mold 22 is released, and the intermediate mold 22 is removed from the lower mold 26 (see FIG. 12). In this way, the mold member according to the invention, ie the packing 11 in this example, is manufactured.

The packing 11, which remains attached to the intermediate mold 22 in this manner, is installed in the case 1 shown in FIG. 1 as described below.

That is, as shown in a partially enlarged view in FIG.
A pair of upper and lower molds 39 and 40 are provided facing each other so as to sandwich the intermediate mold 22 between them. And upper mold 39
There is a chuck 32 on the die, and a punch 3 on the lower die 40.
3 is provided. The chuck 32 and punch 33 are movable relative to the respective molds 39 and 40 as shown by arrows. Moreover, these pair of chucks 32 and punches 33 are connected to a large number of through holes 2 formed in the intermediate mold 22 shown in FIG.
1, a plurality (5 in the illustrated example) of the molds 39 and 40 are arranged in a straight line facing the vertical rows of through holes 21. Therefore, in this case, the pitch of each chuck 32 is selected to be the same as the pitch _P1 shown in FIG. Incidentally, the punch 33 is also selected as pitch _P1 .

Furthermore, as shown in FIG. 14, the packing 11 punched by the punch 33 is left in close contact with the recess of the chuck 32, and in this state, the FET 8
The lead wires 15 and 16 are inserted into the lead wire insertion recess 1.
3, 14 and guide holes 41, 42 of chuck 32
The packing 11 is attached to the FET 8. After that, the FET 8 is housed in the case 3, the side of the FET 8 is positioned against the inner wall of the case 3, and the electret diaphragm 5,
Electret fixing plate 6, diaphragm ring 7
After the capacitor microphone is attached, they are housed in the metal case 1 to complete the manufacture of the condenser microphone.
In addition, FET8 is attached to intermediate mold 2 like chuck 32.
Five intermediate molds 22 can be arranged in parallel along the width direction of the intermediate molds 22, and the intermediate molds 22 can be sequentially fed at a feeding pitch _P2 .

Thus, according to the packing manufacturing method according to the present invention, it is impossible to automatically align and supply the packing to the assembly line due to the nature of the material, which has flexibility, stickiness, directionality, and shrinkage. Since the rigidity of the soundproof packing is supplemented by the plate material of the intermediate mold, the soundproof packing can be positioned with high precision and supplied to the assembly line, and automatic assembly in the condenser microphone manufacturing process is facilitated. It becomes easier.

Furthermore, automatic assembly of the condenser microphone becomes possible, and the frequency of cleaning the mold and tearing out parts is eliminated, resulting in lower prices.

Further, the intermediate mold can be made of waste material from the production of the diaphragm ring, and even if a member corresponding to the intermediate mold is manufactured separately, this member can be used repeatedly, so that the cost can be reduced.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a condenser microphone.
Figure 2 is its top view, Figure 3 is its bottom view, and Figure 4 is its top view.
Figure 5 is a front view of the FET, Figure 5 is a perspective view of the soundproof packing, Figure 6 is a sectional view taken along the - line, Figure 7 is a perspective view showing the state of press molding of the packing according to the present invention, Figure 8 The figure is a plan view of the intermediate mold, Figure 9 is a cross-sectional view of the packing immediately before molding, Figure 10 is a cross-sectional view of the packing during molding, and Figure 11 is a cross-sectional view of the packing immediately after molding. , FIG. 12 is a plan view of the intermediate mold, FIG. 13 is a sectional view showing the state of punching the packing, and FIG. 14 is a sectional view showing the state of mounting the FET. 21 is a through hole, 22 is an intermediate mold, 25 and 26 are a pair of upper and lower molds, and 27 is a molding material.

Claims (1)

[Claims] 1. A recess for inserting a lead wire is provided on the back side of a microphone case in which a sound guide hole is formed on the top surface,
In the method for manufacturing a soundproof microphone packing for soundproofing the back side of the case, a plurality of through holes having a predetermined shape are formed in a predetermined arrangement, and positioning holes are provided along the arrangement. An intermediate mold, and a pair of upper and lower molds in which one mold is provided with a convex portion at a position corresponding to the position of the through hole, and the other mold is provided with a concave portion at a position corresponding to the convex portion. and a pair of upper and lower second molding molds in which one mold is provided with a chuck and the other mold is provided with a punch. By arranging a first molding die at a position defined by the positioning hole between the pair of molds, and applying pressure and heat to the intermediate mold by the first mold in this state. A sheet member having a packing portion formed at a position corresponding to the through hole is molded, and then the intermediate mold is placed between the pair of molds of the second mold, and the sheet member is molded into the through hole. A method for manufacturing a microphone packing, characterized in that the packing is obtained by separating the packing by feeding the sheet member at a pitch defined by the positioning holes and punching the packing by the punch.