JPS58215899A - Diaphragm for electrostatic type electroacoustic transducer and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a diaphragm with good sensitivity easily at low cost by removing part of metallic plates by etching work after sticking the metallic plates to both surfaces of the synthetic resin film, and thus forming a frame. CONSTITUTION:The synthetic resin film 11 as a diaphragm is heated about up to its melting point and metallic plates 12a and 12b are stuck to both surfaces of the film 11. Then surfaces of the metallic plates 12a and 12b which are left as the frame are covered with resist layers 13a and 13b. In this state, parts of the metallic plates 12a and 12b which are not masked with the layers 13a and 13b are etched to form frames 12a' and 12b' while the film 11 as the diaphragm 11' is exposed. Then, the layers 13a and 13b are removed and the body is cut in an adequate outward appearance shape. This manufacturing method facilitates the manufacture and reduces the stiffness of the diaphragm, improving the sensitivity and performance of the diaphragm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a bell-shaped electroacoustic transducer diaphragm used in microphones, head-on speaker units, etc., and a method for manufacturing the same.

[Technical Background of the Invention and Problems] An electrostatic air-to-air acoustic transducer in which an imaging plate is provided between two fixed electrodes has been put to practical use, for example, as a headphone speaker unit.

FIG. 1 shows a case where this is constructed focusing only on the converting section. As shown in the figure, the imaging membrane 1 is attached to a frame 2 on one side thereof, and two fixed electrodes 4a and 4b are arranged facing each other on both sides of the vibrating membrane 1 with the frame 2 and a spacer 3 in between. ing. Fixed electrodes 4a, 4b
are metal plate 4aI, electret 114at, and metal plate 4b8., respectively. It is constituted by an electret layer 4b2. Note that 5 in the figure indicates a case.

Figure 2 shows an extracted portion of the camera board.

As shown in the figure, the IC imaging membrane 1 is stretched over a frame 2, but the frame 2 is provided only on one side of the vibrating membrane 1.

It is being

In such a speaker unit, the distance between the diaphragm 1 and the fixed electrodes 4a and 4b is the same as that between the frame 2 and the spacer 3.
Since it is determined by , it has the advantage of maintaining one interval with high accuracy. What kind of structure is used to reduce the gap between the imaging film 1 and the fixed electrodes 4a and 4b to obtain a highly sensitive transducer?

New problems arise.

That is, in order to reduce the gap between the imaging film 1 and the fixed electrodes 4a and 4b, it is necessary to reduce the thickness of the frame 2 and the spacer 3 accordingly.

When the frame 2 is made thinner, the mechanical strength becomes low T, and the frame 2 is warped during assembly, resulting in the following drawbacks.

(1) Not only does the imaging film 1 easily peel off, resulting in defects, but also the tension tends to change, resulting in unstable performance and many variations.

(2) Difficult to assemble, especially difficult to assemble automatically.

(3) Frame 2 is warped, so store the camera board.

Vibrator 1 is easily damaged during transportation.

Therefore, it has been difficult to reduce the distance between the diaphragm and the fixed electrode using such a diaphragm. For example, if you try to apply the outer diameter force to a 14mm micro-on, the frame thickness will have to be about 0.5mm.
For this reason, the gap between the imaging film and the fixed electrode is 9.5 mm or more, which reduces sensitivity and has hindered its practical use.

[Purpose of the invention]

This invention was made based on the above circumstances.

An object of the present invention is to provide a static center type diaphragm for an air-acoustic transducer, which can reduce the gap between the diaphragm and the fixed electrode, and which can easily obtain good sensitivity and performance at a low cost, and a method for manufacturing the same. It is something to do.

[Summary of the invention]

The actual method of this invention is not to construct a ring-shaped frame by stretching a photographic film, but to sandwich a synthetic resin film and attach metal plates to both sides of the film, and then etching the seven parts of the frame. It is characterized by removing a portion of these metal plates from both sides and using the exposed synthetic resin parts as a vibrating part.

The resulting diaphragm is characterized by a synthetic resin diaphragm being held between a pair of metal frames with relatively low tension and approximately uniform thickness. There is.

〔Effect of the invention〕

According to the method of this invention, a frame is formed by etching after attaching a metal plate to both sides of a synthetic resin film. There is a method that can reduce the gap and increase the sensitivity.

Furthermore, by having such a small gap, it is possible to improve the frequency characteristics, especially in the high range, by utilizing the viscous resistance of the air when the imaging film vibrates.

In the imaging plate obtained by this invention, the diaphragm is supported between a pair of frames in a state of low tension and approximately uniform thickness, so that the stiffness of the diaphragm can be reduced. It can be made smaller, and from this point it is possible to improve the low frequency characteristics. Furthermore, the method of the present invention employs means that are easy and suitable for automation in each step, and therefore has the advantage of being able to provide a diaphragm with excellent berthability and good performance at a low cost.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

・In Fig. 3 (a), 11 is a synthetic resin film that becomes a vibrating body, and on both sides there are gold [plates 12a,
12b is arranged. By heating these to near the melting point of the synthetic resin film 11 and applying pressure from both sides, metal plates 12a and 12b are attached to both sides of the synthetic resin film 11, as shown in tb+ in the figure.

If the surface of the part to be left as a frame is covered with resist Iff 13a *13b as shown in FIG. 3 (C1) and etching is performed in this state, it will be masked with resist I#13a and 13b as shown in FIG. 3(d). Gold layer plate 12a that was not used.

12b is corroded and the frames 12a' and 1
2b' (formed), and the synthetic resin film 11 that will become the vibrating part 11' is exposed.Therefore, as shown in FIG. By cutting it into a shape, a diaphragm as shown in ff) in the same figure can be obtained. If necessary, see Figure 1(e)
Conductive treatment is applied to one or both sides of the synthetic resin 1 or 1 at the stage of sintering.

Fig. 1 fgl shows a plan view of the diaphragm thus obtained, and Fig. 4 shows its oblique one-dimensional view.

If you make a photographic board in this way, the synthetic resin +11411
When the metal plates 12a and 12b are attached to both sides of the synthetic resin steel plate 1, the tension of the synthetic resin steel plate 1 is determined, and as a result, the stiffness of the sliding plate 1 is determined. The bonding between the plastic film 11 and the metal plates 12a and 12b can be achieved by simply placing the metal plates 12a and 12b on both sides of one synthetic resin film and applying heat and pressure. It can be attached without applying any tension. Therefore, according to this method, it is possible to easily obtain an imaging plate with extremely low stiffness.

In addition, this method uses a synthetic resin 1 11 and a metal plate 12a.

Using 12b, frame 12a is etched; 1
2b' and the vibrating part 11' of synthetic 4# fat model 11 are formed C
Since the etching is performed only on the metal plates 12a and 12b, the imaging section 11 has a uniform thickness.
'It has the advantage of being easy to obtain.

Therefore, in combination with the fact that a product with low stiffness can be easily obtained as mentioned above, it is easy to manufacture and has a high sensitivity.
(Also, a diaphragm with excellent performance can be obtained.

Furthermore, this method includes 1 synthetic resin 1 replica 11 and a metal plate 12a.
, 12b, removing part of the metal plates 12a and 12b by etching, and cutting by pressing are all suitable for mass production.
It is excellent in reducing production and can reduce manufacturing costs.

Fig. 5 shows the vibration plate obtained by this invention.
1 shows a case in which an air-acoustic transducer of the type Pussyple '1 is constructed. In the figure, 14a is a fixed electrode consisting of a metal plate 14a++ electret Ia 14a.

Reference numeral 14b indicates a metal plate 14b, a fixed electrode made of an electret layer 14b2, and 15 a case. Note that the other parts are the same as in FIGS. 3 and 4.

Corresponding parts are denoted by the same reference numerals and explanations are omitted.

In such an electroacoustic transducer, 1 synthetic resin film 11
Since the thickness of the frames 12a' and 12b' that sandwich the vibration part 11' and the fixed electrode 14a can be made thinner,
It would be possible to reduce the gap between 14b and 14b. therefore(
Not only can the sensitivity of the air 41 be improved, but also the thinness of the air layer between the vibrating part 11' and the fixed electrodes 14a and 14b allows this part to move as the imaging part 11' moves. The viscous resistance of the air has the effect of suppressing peaks in frequency characteristics that occur particularly at high-frequency resonance points and improving characteristics.

Further, as shown in Fig. 14, this photographing plate is protected by frames 12a' and 12b' on both sides of the vibrating part 11', and the vibrating part is
1' is less likely to be damaged. Furthermore, since the diaphragm does not have a front or back side, it is possible to prevent mistakes such as changing the front and back sides when assembling the +tt air subresonance converter. Further, for the same reason, it is suitable for automatic assembly, and in combination with the above-mentioned points regarding the manufacture of sliding plates, it is possible to further promote unfavorable production.

Furthermore, when downsizing a molded electrophonic transducer, the diameter of the diaphragm inevitably becomes smaller, so unless the tension in the vibrating part is loosened, the low-frequency characteristics of the '13 Kikō acoustic transducer tend to deteriorate. However, as described above, the imaging plate according to the present invention has the advantage that a small tension in the vibrating section can be obtained, and therefore a small-sized acoustic transducer with good low-frequency characteristics can be easily realized.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist.

For example, in the above embodiment, heating and pressure are used to attach the pair of metal plates to the synthetic resin film, but other equivalent methods may also be used. Deposition by can also be used.

Further, in the above embodiment, the case of a circular imaging plate has been mainly described, but it may have the shape of a pond, but it may also have an irregular polygonal shape, for example, to improve performance.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of an example of a conventional push-pull air-acoustic transducer using a diaphragm; Figure 2 is a perspective view of an example of a conventional imaging plate; An explanatory diagram showing one embodiment of the manufacturing method of the invention, FIG. 4 is a perspective view of a diaphragm obtained by this method, and FIG. 5 is an electrostatic push-pull electroacoustic transducer constructed using this imaging plate. It is for the cross section of. 1...m, @III 2...Frame 3...Spacer 4a, 4b...Fixed electrode 4a, 4b,...Metal plate 48! *4b!
...Electret layer 5...Case 11...Synthetic resin 8Mt2a, tzb...Metal plate 11'...4 Disturbance part 12a', 12b'...
・Frame 13a, 13b...Resist layer 14a
, 14b...Fixed electrode "a+p 14b, ,
,, Metal plate 14at g i, ib, ”+ Electret layer 15...One person outside the case i-2 Hayashi 1 Figure 1 (a) (C) Figure 2 Figure 3

Claims (5)

[Claims] (1) A step in which a synthetic resin film is sandwiched and metal plates are attached to both sides of the film, and a part of these metal plates is etched until the synthetic resin film is exposed from both sides, leaving the part that will become the frame. A method for manufacturing a diaphragm for an electrostatically formed air-sound dance transducer, characterized in that the exposed portion of the synthetic resin film is used as a vibrating part. (2) For an electrostatic electroacoustic transducer according to claim 1, wherein metal plates are attached to both sides of the synthetic resin film by heating and pressurizing the synthetic resin film to near its melting point. Method of manufacturing a photographic board. (3) A method for manufacturing a diaphragm for an electrostatic electroacoustic transducer according to claim 1, characterized in that metal plates are attached to both sides of the synthetic resin film by adhesion. (4) A method for manufacturing a diaphragm for an electrostatic electroacoustic transducer according to any one of claims 1 to 3, characterized in that a thermoplastic material is used as the synthetic resin film. (5) It is equipped with a pair of supporting frames made of metal and a vibrating part made of a synthetic resin film sandwiched between these frames, and this vibrating part is supported in a relatively low tension state and has a thickness of A diaphragm for an electrostatic electroacoustic transducer, characterized in that the diaphragm is approximately uniformly formed.