JPH0256000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an electrostatic electroacoustic transducer such as a capacitor microphone, and in particular to a thin film such as a dielectric film on which a conductive layer constituting a diaphragm is attached. This makes it possible to streamline the work of joining the thin film to the frame that supports it, and to freely control and accurately set the free resonance frequency of the diaphragm that is joined to the frame as desired.

Conventionally, electrostatic electroacoustic transducers, such as capacitor microphones, are made by bonding a conductive metal foil onto one surface of a thin film base material such as a dielectric polyester film, or by bonding a conductive metal foil onto one surface of a thin film-like base material such as a dielectric polyester film. It has an electroacoustic transducer element in which a diaphragm formed by depositing a conductive layer by vapor deposition is joined to a diaphragm ring serving as a support frame. The diaphragm is stretched around the diaphragm ring under a predetermined tension so as to have a desired constant resonance frequency. Therefore, when joining the diaphragm to the diaphragm ring, the diaphragm is pulled in all directions with a constant tension during the joining process.

By the way, conventionally, when bonding a diaphragm ring to a diaphragm ring, an adhesive is used which is made by mixing silver powder or the like into a thermosetting resin such as an epoxy synthetic resin to make it conductive. When using such a thermosetting adhesive, in order to harden the adhesive,
It is necessary to heat-treat the joint between the diaphragm and the diaphragm ring at a temperature sufficient to cure the adhesive for a predetermined period of time. Therefore, it is not possible to perform work efficiently in a short time. Furthermore, the heat treatment causes elongation of the diaphragm, which is held under constant tension during the bonding process, making it impossible to bond the diaphragm ring to the diaphragm ring while maintaining the tension applied during the bonding process. In particular, polyester film, etc., which is the base material of the diaphragm,
Not only does the elongation rate vary depending on the heating temperature, but the elongation rate due to heating does not match the shrinkage rate after cooling. Therefore, not only does the tension applied during the bonding process not match the tension after bonding, but it is extremely difficult to delicately control the tension after bonding during the bonding process. Therefore, it has become extremely difficult to bond and tension the diaphragm to the diaphragm ring while maintaining a desired controlled and constant free resonance frequency.

Therefore, the present invention was proposed with the aim of solving the above-mentioned problems of the conventional film. The thin film diaphragm to be formed and the support frame that supports this diaphragm can be joined without going through a heat treatment process, and the diaphragm is supported so as to have a desired stable and constant free resonance frequency. It is designed so that it can be attached to a frame and stretched.

An example in which the present invention is applied to a condenser microphone will be described below.

To give an overview of the capacitor type microphone to which the present invention is applied, as shown in Fig. 1, this microphone is a thin film with a thickness of about 4μ to 8μ made of a dielectric material such as polyester film. A conductive layer 2 is formed by vapor depositing a conductive metal such as copper to a thickness of angstroms on one surface of the base material 1, and the diaphragm 3 is formed into a thin film. A diaphragm ring 4, which is a supporting frame formed of a conductive metal, is bonded and stretched over one end surface of the diaphragm ring 4, and an insulating spacer 5 having a thickness of about 30 μm to 200 μm is interposed between the diaphragm ring 4 and the diaphragm ring 4. It has an electroacoustic transducer element 7 disposed on a back plate 6 serving as a back electrode. This electroacoustic transducer element 7 is housed and held in a capsule 8, which is a storage container, and constitutes a microphone body 9. That is, the electroacoustic transducer 7 has the diaphragm 3 positioned so as to correspond to the upper opening 10 provided in the capsule 8 so that the diaphragm 3 faces outward, and the insulating material constituting the bottom cover of the capsule 8. The back plate 6 is supported by the support base 11.
A lead electrode 15 for extracting an output signal from a through hole 13 formed in the insulating support base 11.
It is housed and held in the capsule 8 in such a way that it extends. Then, the microphone main body 9
is housed and held in an outer casing in which an electric circuit such as an amplifier circuit is built-in, thereby forming a condenser type microphone.

The diaphragm 3 constituting the electroacoustic transducer element 7 of the capacitor microphone according to the present invention is
In order to be able to bond to the diaphragm ring 4 without going through a heat treatment process like conventional ones, an ultraviolet curable resin composition that is cured by irradiation with ultraviolet light, which is a short wavelength light of about 200 to 400 mμ, is used. Therefore, the diaphragm ring 4 is bonded and stretched.

Therefore, the process of joining and tensioning the diaphragm ring 4 to the diaphragm ring 4 will be explained.

First, a film sheet 101 such as polyester film, which is a dielectric material constituting the base material 1 of the diaphragm 3 and is sufficient to transmit ultraviolet rays, is prepared. The conductive layer 2 is formed by vapor-depositing a metal such as copper or silver. This conductive layer 2 is formed on the film sheet 101 with a thickness sufficient to transmit ultraviolet rays.

The film sheet 101 on which the conductive layer 2 has been adhered is stretched in all directions with a desired constant tension, and the conductive layer 2 is placed on the surface of the conductive layer 2 corresponding to the bonding surface 4a of the diaphragm 3 in the diaphragm ring 4. As shown in FIG. 3, the ultraviolet curable resin composition 17 is applied to appropriate locations by screen printing or other transfer methods.

The ultraviolet curable resin composition used here consists mainly of a prepolymer and a monomer.
For example, propylene glycol, 1 mole of maleic anhydride is added to 70% by weight to 1.1 moles, and styrene is added to this at a ratio of 20 to 25% by weight to make an unsaturated polyester resin as a base resin. For example, one containing benzoyl methyl ether as a sensitizer is used. The above resin composition is blended in a ratio of 100 parts of base range and 2 parts of sensitizer.

Furthermore, when the film sheet 101 and the diaphragm ring 4 are bonded together, the ultraviolet curable resin composition contains the conductive layer 2 and the diaphragm ring 4 formed on the film sheet 101.
Silver powder or the like is mixed in to ensure electrical continuity with the material, making it conductive.

Then, as shown in FIG.
Ultraviolet curable resin composition 17 deposited on 01
The diaphragm ring 4 is placed correspondingly.

Next, as shown in FIG. 5, these are placed on a flat glass plate 110 that transmits ultraviolet rays, with the film sheet 101 as a mounting surface, and a flat pressing plate 111 is pressed from the diaphragm ring 4 side. It is supported under pressure by a glass plate 110 and a pressing plate 111. Film sheet 1 like this
01 and the diaphragm ring 4 are supported under pressure, from the bottom surface of the glass plate 110 to
The ultraviolet curable resin composition 17 is cured by irradiating ultraviolet rays with a wavelength of about 400 mμ, and the film sheet 101 and the diaphragm ring 4 are bonded together.

A light source 12 that emits the ultraviolet rays irradiated here
Examples of 0 include high-pressure mercury lamps with an energy distribution in which radiant energy is large at wavelengths of 300 mμ or less, multimetal lamps with energy distribution in which radiant energy is large in wavelengths of 350 mμ to 400 mμ, and 400 mμ or more. A diazo gallium lamp, etc., which has an energy distribution in which the radiant energy is large in the wavelength range from near ultraviolet to visible region, is used, and the absorption wavelength of the sensitizer added to the resin composition and the adhesion of the resin composition are used. It is appropriately selected and used depending on the thickness and the like.

As described above, the ultraviolet curable resin composition 17 is cured by irradiating ultraviolet rays to form the film sheet 101.
After joining the diaphragm ring 4 to the diaphragm ring 4, the film sheet 101 is cut along the outer circumference of the diaphragm ring 4. As shown in FIG. is obtained. This diaphragm ring 4 is housed on a back plate 6 in a capsule 8 with an insulating spacer 5 interposed therebetween, thereby forming a microphone body 9 as shown in FIG.

By the way, the film sheet 101 and the diaphragm ring 4 are constructed such that the ultraviolet curable resin composition 17 applied to the conductive layer 2 formed on one side of the film sheet 101 is applied to the lower surface of the film sheet 101. The bonding is achieved by curing the material using ultraviolet light irradiated from the side. Therefore, the conductive layer 2 formed on the film sheet 101 must also be formed with a thickness sufficient to transmit ultraviolet rays. When the conductive layer 2 is formed of a vapor-deposited layer of copper, it has a thickness of 350 mμ due to the properties of copper.
The transmittance of ultraviolet rays changes depending on the thickness as shown in FIG. Therefore, when the conductive layer 2 is formed as a vapor-deposited layer of copper, the ultraviolet curable resin composition 1 can be formed without losing the electrical properties of the conductive layer 2.
The coating may be formed to have an appropriate thickness within the range shown in FIG. 7, which can ensure the amount of ultraviolet rays transmitted through which is sufficient for the curing in step 7.

According to the present invention configured as described above, the diaphragm formed as a thin film and the support such as a diaphragm ring that supports the diaphragm can be bonded without going through a heat treatment process. The production of the acoustic transducer becomes extremely easy. In particular, since the ultraviolet curable resin composition used in the present invention is cured in a short time by irradiation with ultraviolet rays, efficient bonding work can be performed.

Furthermore, since the diaphragm and the supporting body constituting the present invention can be bonded together by only short-term irradiation with ultraviolet rays, the diaphragm does not stretch due to heating unlike conventional systems. Therefore, the tension applied to the film sheet constituting the diaphragm during the bonding process is maintained as it is even after bonding to the support. Therefore, the free resonance frequency, which is varied by the tension of the diaphragm after it is bonded to the support, can be accurately and stably controlled, making it possible to use electroacoustic transducers such as capacitor microphones with extremely good characteristics. Can be configured.

Furthermore, since the conductive layer is thick enough to transmit ultraviolet rays, it is possible to irradiate ultraviolet rays from the diaphragm. is supported in a pressed state by a pressing plate, and in this state UV rays are irradiated from the diaphragm side to cure the ultraviolet curable resin composition adhered between the diaphragm and the frame. With this, the diaphragm and frame can be joined together. Therefore, the adhesion between the diaphragm and the frame is ensured, and since the diaphragm is joined to the frame with a predetermined tension applied, the distance between the diaphragm and the back plate is maintained correctly. This makes it possible to ensure mutual parallelism and ensure good acoustic characteristics.

In addition, in the method of the present invention as described above, since ultraviolet rays are irradiated from the thin film sheet side to achieve bonding with the frame, the ultraviolet rays can be efficiently irradiated to the ultraviolet curable resin composition. Rapid curing and reliable bonding of this ultraviolet curable resin composition can be achieved. Then, the diaphragm is bonded to the frame while a constant tension is applied, but since the ultraviolet curable resin composition achieves rapid curing, the diaphragm is bonded to the frame after the diaphragm is bonded to the frame. The applied tension can be reliably maintained as desired without causing large fluctuations, and the free resonance frequency can also be controlled accurately and reliably. Therefore, it is possible to provide an electroacoustic transducer with good acoustic characteristics.

Although the above-mentioned embodiments have been explained using an example of a capacitor microphone, each of the above-mentioned inventions can also be applied to an electroacoustic transducer such as a capacitor-type speaker having a similar structure, and the above-mentioned embodiments can also be applied to an electroacoustic transducer such as a capacitor-type speaker having a similar structure. effect can be achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention. Figures 2 to 6 are diagrams showing the bonding process of the diaphragm ring that constitutes the present invention and the diaphragm ring that is the support, and Figure 2 shows the state in which the conductive layer is adhered to the film sheet. A cross-sectional view,
FIG. 3 is a cross-sectional view of the film sheet further coated with an ultraviolet curable resin composition;
FIG. 4 is a cross-sectional view of a state in which a diaphragm ring is further placed on the film sheet, and the fifth
The figure is a cross-sectional view showing the bonded state of the film sheet and the diaphragm ring, and FIG. 6 is a perspective view showing the state in which the film sheet is cut into individual diaphragm rings and bonded and stretched as a diaphragm. 7th
The figure is a diagram showing the relationship between the thickness of the conductive layer and the transmittance of ultraviolet rays. 1... Base material constituting the diaphragm, 2... Conductive layer,
3... Vibration plate, 4... Diaphragm ring serving as a support frame, 7... Electroacoustic conversion element, 17... Ultraviolet curable resin composition.

Claims (1)

[Claims] 1. Applying a UV-curable resin composition onto the conductive layer while applying tension to a UV-transparent thin film sheet on which a conductive layer is formed to a thickness that allows UV-ray transmission;
placing a frame on the ultraviolet curable resin composition;
Next, the ultraviolet rays are irradiated from the thin film sheet side to cure the ultraviolet curable resin composition to bond the thin film sheet and the frame, and then the thin film sheet is cut along the outer circumference of the frame. A method for manufacturing an electrostatic electroacoustic transducer, in which a frame is formed by bonding and stretching a diaphragm, and the frame is placed on a back plate in a storage container with an insulating spacer interposed therebetween. .