CN2061748U

CN2061748U - Waterproof, damp-proof and long life eletret diaphragm

Info

Publication number: CN2061748U
Application number: CN 89221082
Authority: CN
Inventors: 赵唯
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-12-18
Filing date: 1989-12-18
Publication date: 1990-09-05

Abstract

The utility model discloses an electret diaphragm with negative electric charges stored on a surface, belonging to a sound and electricity converting element. Electric charges can discharge by contacting with water, steam, moisture, etc. Under the circumstance of no reduce of original electric charges, flow afterglow is made into an insulating medium diaphragm on the electret diaphragm, so that the electric charges can be separated from steam, etc., and accordingly, waterproofness and moistureproofness can be obtained, and the service life of the electret diaphragm can be prolonged. In addition, the diaphragm is thin, the utility model has the advantages of cross link, good adhesion, compactness, no pinhole, etc., so that the properties of an original diaphragm can not be influence except the good waterproofness.

Description

Waterproof, damp-proof and long life eletret diaphragm

The utility model relates to sound-electric transition element electret diaphragm, and on it, make one deck dielectric film.

The electret diaphragm is the about 5 millimeters MP metallized paper of a kind of diameter.Promptly be coated with layer of metal film on the macromolecule face, their thickness all is no more than several ten microns.Be pasted with a becket or sheet metal to gain in strength and to make electrode and use in metal covering one side with conducting resinl.

At present the industrial production of electret diaphragm adopts the corona treatment method to finish, injection be the surface electronic negative electrical charge.This store charge discharges owing to contacting with media such as water or steam, makes the electron charge decay, thereby the component life shortening, even can not use in the humid area.

The objective of the invention is under the unattenuated environment of surperficial store charge, to make one deck dielectric film in the above simultaneously,, thereby eliminate discharge, prolonged the electret life-span so that store charge and class conductors such as water or steam are separated.

We know that the surperficial store charge on the electret diaphragm is water funk or class conductor such as steam.Thereby when making the dielectric insulating film barrier layer, the electret diaphragm can not contact with class conductor material, otherwise this moment, store charge will be run away much.In order to accomplish when making dielectric insulating film, and don't contact conductor class material, then " cold plasma flowing afterglow " method is the optimal candidate people, it can satisfy this two requirements simultaneously.

The plasma that low pressure glow discharge produces is called cold plasma, its thermodynamical equilibrium temperature than room temperature height not what.Plasma discharge region is again the aura district, and it conducts electricity.The material component is very complicated in the aura district, atom is arranged, molecule, electronics, negative ions, photon, excited state particle, compositions such as free radical particle.Not far from the aura district, about 10 millimeters, positive and negative charge is just rapidly compound have been fallen.The active particle of this moment is remaining free radical only then, but it is nonconducting, form film yet but can carry out radical polymerization.The non-conductive non-aura district of this moment is called " cold plasma flowing afterglow district ", and its polymerization then is called " plasma induced polymerization ".Therefore pending electret diaphragm should be at least away from 10 millimeters in aura district.

We know nearly all organic substance monomer, as ethene, and styrene, organosilicon, tetrafluoroethene, siloxanes etc. can both carry out plasma induced polymerization and film forming.Some inorganic matters also can plasma polymerization and film forming as carbon disulfide etc., and the latter is can not be getable with other method.This just provides the chance of selecting material monomer to us.

The film that fluorochemical monomer such as tetrafluoroethene etc. aggregate into, not only good insulation preformance, and drainage are also very strong, i.e. not absorption hydrone.

The film that plasma induced polymerization generates also has other advantage, generation be crosslinked shape film, the 50-5000 dust.Film and substrate surface are bonding firmly, the close and free of pinholes of Bao Mo Cause.This is desirable electret diaphragm moisture-impermeable barrier layer.

Because film is thin, therefore can not influence original electret diaphragm mechanics, mechanical and useful electrical property.

We adopt the high-frequency inductor external discharge.Plasma glow zone just is limited in the coil inner glass tube.The benefit of this kind device can not brought the pollution of electrode material, thereby the film good insulation preformance that generates.

Owing to be glow discharge, the temperature in its flowing afterglow district then almost equates with room temperature.Therefore the supporting disk of electret diaphragm can be metal, pottery or plastics.Supporting disk can be driven by motor and make slow rotation, so that film forming is even.The electret diaphragm need not to use water cooling.

The utility model is because only need make one deck dielectric insulating film on former electret diaphragm separates steam etc., thereby can improve greatly its life-span.Be placed in the flowing afterglow district owing to pending electret diaphragm simultaneously, thereby when making dielectric film, its original store charge can not reduce.

If we are willing to sacrifice the surface charge of some storages, to exchange the raising of polymerization film formation speed for, then we can be placed in the electret diaphragm in the glow district and handle, and at this moment the polymerization speed of monomer on face can be accelerated greatly.Because in the glow district, the free radical activity particle is maximum and the closeest, and this is the key factor of polymerization, and other active particle also has certain catalytic action to polymerization, so polymerization speed is accelerated to infer to obtain.Polymerization in the glow district is called plasma polymerization.Therefore store charge is more when closeer on the electret diaphragm, and in order to improve speed of production, do not stint some electric charges of running away, using plasma aggregation processing diaphragm also suits.

Glow discharge institute consuming electric power is few.Because film is thin, the 50-5000 dust, therefore required raw material are few.Raw material belong to general versatile material again in addition, low price, so production cost can height be not to infer.Glow discharge belongs to the method plating, therefore environment is not almost polluted.Because the required vacuum degree of polymerization is not high, only mechanical pump is just much of that, and need not diffusion pump and cold trap so equipment price can be not high.

Respectively detailed description is made in invention below in conjunction with accompanying drawing.Fig. 1 is a foil electret chip architecture enlarged diagram.In fact diameter is only about 5 millimeters.Wherein 1 is the dielectric insulating film that generates with flowing afterglow, and thickness is the 50-5000 dust, does not draw section among the figure.The 2nd, polymeric membrane, upper surface is marked with store charge, and the 3rd, metal film, the 4th, becket.

Fig. 2 is a foil electret piece treating apparatus schematic diagram.Wherein 1 is barometer, the 2nd, and motor, the 3rd, oil-sealed rotary pump, the 4th, supporting disk, the 5th, electret diaphragm, the 6th, bell jar, the 7th, high frequency electric source, 100-1000 watt, the 8th, discharge inductance coil, the 5-15 circle, the 9th, glass tube, diameter 20-50 millimeter, go up around inductance coil, the 10th, gas flowmeter, the 11st, needle-valve, the 12nd, gaseous monomer source.If when monomer is liquid, then need heats it is become gas.Operational factor is as follows: pressure 0.05-50 holder.Gas flow is the 1-150CC/ branch under reference condition; Processing time is 0.5-20 minute.

Claims

A kind of electret diaphragm, it comprises the polymeric membrane that is coated with layer of metal, and gains in strength and the becket used of electrode, stores negative electrical charge on the macromolecule face, feature of the present utility model is to make one deck dielectric insulating film on the electret diaphragm.