CN101424719A - Method for shielding capacity test of glasses for preventing electromagnetic radiation and device for implementing the method - Google Patents
Method for shielding capacity test of glasses for preventing electromagnetic radiation and device for implementing the method Download PDFInfo
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- CN101424719A CN101424719A CNA2007100476465A CN200710047646A CN101424719A CN 101424719 A CN101424719 A CN 101424719A CN A2007100476465 A CNA2007100476465 A CN A2007100476465A CN 200710047646 A CN200710047646 A CN 200710047646A CN 101424719 A CN101424719 A CN 101424719A
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Abstract
The invention relates to an electromagnetic shielding effect testing method by coating electromagnetic radiation resisting paint by using a far field method and also relates to a device for realizing the method. The electromagnetic shielding effect testing method of electromagnetic radiation resisting glasses is characterized in that the surface resistance RS of an electromagnetic radiation resisting coating layer of the electromagnetic radiation resisting glasses is firstly measured, a surface resistivity rho S is obtained, then, the surface resistivity rho S is substituted into a formula to obtain the shielding effect SE, and a testing method of the surface resistivity rho S adopts a ring method. The invention uses a non-destructive method to test the surface resistivity of materials, consequently, the shielding effect is obtained, a special testing field is not needed, a testing device is relatively cheaper, an expensive network analyzer is not needed, and the cost of the analyzer device is greatly reduced. Compared with a near field test, the testing uncertainty is greatly reduced, and the testing repeatability is good.
Description
Technical field
The present invention relates to a kind of method of testing of shield effectiveness, particularly the method for testing of glasses for preventing electromagnetic radiation shield effectiveness also relates to the device of realizing this method.
Background technology
Great-power electromagnetic radiation energy injury human body, the easiest position that injured by electromagnetic radiation of human body is eyes, for a long time, under more heavy dose of electromagenetic wave radiation, it is muddy that eye's lens can become, and gives birth to cataract.Preventive measure are exactly to put on the glasses that scribble electromagnetic radiation preventing paint, but scribble the metallic film of anti-electromagnetic radiation when eyeglass after, the light transmission of eyeglass has weakened, coating is thick more, the anti-electromagnetic radiation performance is good more, and luminous flux is few more, in order to seek an optimum between brightness and anti-electromagnetic radiation, we must survey the electromagnet shield effect of accurate eyeglass, but regrettably none suitable method so far.
The national military standard SJ/T20524-1995 of China has stipulated that the non-conducting material surface is coated with or coating, wire netting, electro-conductive glass, conductive film, the measuring method of plate shielding material shield effectivenesss such as conducting medium plate.But it requires sample diameter is Φ 115, and the size of glasses can't be tested, even use less sample clamp less than Φ 115 usually.And this is a kind of destructive testing method, so the glasses for preventing electromagnetic radiation test is an intractable problem all the time.
Commonly used in the past is a kind of near field method for this reason, as shown in Figure 1.
For the electromagnetic wave that prevents to launch is diffracted into receiving antenna one side from the side of eyeglass, emitting antenna and receiving antenna are generally done very for a short time, and antenna factor is just very big like this, and the signal that receiver is received is just very weak, it is very big that noise also just becomes, and brings very big error to test.In addition, during test electromagnetic wave from the eyeglass limit diffraction and from the eyeglass reflection after the indoor leakage that repeatedly reflexes to receiving antenna and caused all makes the test result error very big.And, near field electromagnetic shield effectiveness distance dependent also and between radiation source, antenna and the eyeglass.Even the anechoic chamber, build-in test in the millions of units of cost, this inhomogeneous error in field that causes owing to a reflection still can reach 6 decibels (also not comprising the diffracted error from eyeglass one side to opposite side).Moreover, on the angle of estimating the electromagnetic shielding material performance, consider near field electromagnetic shield effectiveness distance dependent also and between radiation source, antenna and the eyeglass, obviously, the near field method is not a kind of good method.
Summary of the invention
The technical problem to be solved in the present invention first aspect is to propose a kind of glasses for preventing electromagnetic radiation shield effectiveness method of testing, to solve the problems referred to above that existing method of testing exists.
Glasses for preventing electromagnetic radiation shield effectiveness method of testing is characterized in that, may further comprise the steps:
1) measures the surface resistance R of the anti-electromagnetic radiation coating of described glasses for preventing electromagnetic radiation
s, draw the surface resistivity ρ of described anti-electromagnetic radiation coating
s
2) with resulting surface resistivity in the step 1), the following formula of substitution obtains shield effectiveness SE
Z in the formula
oBe the space wave impedance, its value is 377 Ω.
Illustrate with the derivation of formula (5) below and of the present inventionly can solve this technical matters really:
Usually the shield effectiveness of electromagnetic shielding material can be represented with following formula:
Here SE is a shield effectiveness, unit: dB
P
oBe incident electromagnetic wave power
P
iIt is the transmission electromagnetic wave power
SE also can be written as:
Here E
oIt is the field intensity of incident wave
E
iIt is the field intensity of transmission ripple
General when the electromagnet shield effect of material is estimated and tested, far field commonly used method.This moment, electromagnetic wave was a plane wave, adopted the two-wire line model, and the incident wave electric field strength E is:
E＝E
ie
i(kz-ωt)………………………………………(3)
Here k=2 π/λ, ω=2 π f, ω is an angular frequency
Use the boundary condition of electromagnetic wave, in the time of the far field can being solved in conjunction with equation (2) in each surface reflection of thin slice and transmission.Thickness is the electromagnet shield effect SE and the conductivity of the sheeting of d, and the funtcional relationship of angular frequency is
…………………………(4)
(list of references: L.W.Shacklette, and N.f.Colaneri, " EMI Shielding with ConductivePolymer Blends " Conductive Polymers Conference 1992 Paper 3)
Here, ε
oBe the vacuum medium dielectric constant microwave medium, ε
o=10
7/ 4 π c
2F/m
σ is a conductivity of electrolyte materials, μ
0Be magnetic permeability μ in the vacuum
0=4 π * 10
-7H/m
δ is the skin depth of material,
The best metal of electric conductivity is a silver, and its skin depth when 1GHz is 2.03 μ m
Glasses for preventing electromagnetic radiation is different from general sunglasses, can both use when it should be worked on outdoor and indoor computer, can not be too big to the decay of light, and coating just can not be too thick, so the mirror film thickness d on the glasses＜＜δ
(4) formula can be reduced at this moment
……………………………(5)
In the formula,
, be the space wave impedance.
From (5) formula as can be known, if known the surface resistivity ρ of material
s, just can try to achieve the electromagnet shield effect of material.
The second aspect of technical matters to be solved by this invention is to propose a kind of method of testing of surface resistivity of anti-electromagnetic radiation coating:
The present invention draws the surface resistivity ρ of the anti-electromagnetic radiation coating of described glasses for preventing electromagnetic radiation by following steps
s:
1) preparing a bottom surface is the external electrode of annular, and the annular internal diameter of bottom surface is r
1One bottom surface is circular interior electrode, and the diameter of the circle of bottom surface is r
2r
2＜r
1
2) described external electrode and described interior electrode are pressed on the anti-electromagnetic radiation coating surface of described glasses for preventing electromagnetic radiation, and make described external electrode concentric with described interior electrode; Utilize direct current bridge or dc digital voltmeter to measure the surface resistance R of the anti-electromagnetic radiation coating between described external electrode and the described interior electrode
S
3) with step 2) in the surface resistance R measured
SFollowing formula is tried to achieve the surface resistivity ρ of described anti-electromagnetic radiation coating
s
Really can test out the surface resistivity ρ of the anti-electromagnetic radiation coating of described glasses for preventing electromagnetic radiation below by the derivation explanation technique scheme of formula (8)
s:
Resistance sample shown in Figure 2 (center section) is very thin, on a rectangle is rectangular, and surface resistivity ρ
sIn the time of can being defined as w=L (L represents length, and w represents width), measured resistance value Rs on the low resistance electrode of the both sides of film:
As press the test of Fig. 2 method, and need sample is cut into rectangle, respectively do a low resistance electrode again at two ends, then will destroy sample.
For this reason, to adopt a bottom surface be annular external electrode and a bottom surface are circular interior electrode.As shown in Figure 3, employing is the external electrode of loop column type and round interior electrode.
Among Fig. 3, beat oblique line and partly be electrode, two electrodes are pressed on the sample surfaces to be measured, can obtain surface resistivity ρ by the method for surveying resistance between the internal and external electrode
s
Abbreviate this method of testing as ring method.
After adopting Fig. 3 method, former formula (6) can't use, and must derive again:
Now get polar coordinates:
Cut a very little central angle Δ θ at Fig. 3, figure shown in Figure 4 is promptly arranged
r
2Be circular ring type electrode inside radius, r
1Be round electrode external radius
＜r
2With r
1Between measure, obtain surface resistance R s:
The third aspect of technical matters to be solved by this invention is to propose to realize the device of above-mentioned glasses for preventing electromagnetic radiation shield effectiveness method of testing.
A kind of proving installation of realizing the glasses for preventing electromagnetic radiation electromagnet shield effect of said method is characterized in that, comprising:
One bottom surface is the external electrode of annular;
The bottom surface that one diameter is littler than the internal radius of the bottom surface of described external electrode is circular interior electrode; Described external electrode is concentric with described interior electrode;
One direct current electric bridge or dc digital voltmeter.
(" interior " of external electrode, interior electrode, " outward " just represent the position relation of two electrodes, do not have other implication.)
Described external electrode is preferably the external electrode of loop column type, and described interior electrode is preferably the interior electrode that is column type.
Further, also comprise the dielectric ring that an insulating material is made, described interior electrode is assemblied in the ring of described dielectric ring, and described dielectric ring is assemblied in the ring of described external electrode.The concrete effect of described dielectric ring is the relative position of fixing between two electrodes.
Also comprise the press strip that an insulating material is made, have three mounting holes in alignment on the described press strip, have two corresponding mounting holes on the described external electrode, have a corresponding mounting hole on the electrode in described, pass above-mentioned mounting hole by screw press strip and described external electrode, interior electrode are assembled.During with the hand press strip, under the effect of press strip, keep certain pressure between described external electrode and the described interior electrode pair sample, thereby a fixing little contact resistance is arranged.Press strip make compress described external electrode and described in electrode convenient.
The material of making described dielectric ring is that the material that teflon is made described press strip is phenoplast.
Described external electrode comprises layer of brass and conductive rubber layer, and described interior electrode also is like this.
Compared with prior art, the invention has the beneficial effects as follows: 1. pass through the surface resistivity of non-destructive method test material, and then obtain shield effectiveness, will in coaxial system, carry out destructive testing originally and transfer to be a kind of non-destructive testing (NDT); 2. do not need special test site, testing apparatus is relatively also cheap, need not expensive network analyzer; Change the microwave radio testing tool of the required costliness of former test into relatively inexpensive electric instrument, greatly reduce the instrument and equipment expense; 3. compare with near-field test, the uncertainty of test reduces greatly, the test good reproducibility.
Description of drawings
Further specify the present invention below in conjunction with the drawings and specific embodiments.
Fig. 1 is that the near field method is surveyed eyeglass shield effectiveness synoptic diagram.
Fig. 2 surveys the sample resistance synoptic diagram of surface resistivity
Fig. 3 is the surface resistivity method of testing synoptic diagram after improving.
Fig. 4 is that ring method is surveyed surface resistivity derivation of equation figure.
Fig. 5 is the structural representation of the round electrode described in the embodiment.
Fig. 6 is the structural representation of the circular ring type electrode described in the embodiment.
Fig. 7 is the structural representation of the dielectric ring described in the embodiment.
Fig. 8 is the structural representation of the press strip described in the embodiment.
Fig. 9 is the wiring layout of the round electrode described in the embodiment, circular ring type electrode and press strip.
Embodiment
For technological means, creation characteristic that the present invention is realized, reach purpose and effect is easy to understand, below in conjunction with embodiment, further set forth the present invention.
Glasses for preventing electromagnetic radiation shield effectiveness proving installation comprises as direct current bridge or the dc digital voltmeter (not shown) of surveying surface resistance; As the column type electrode 1 of interior electrode, loop column type electrode 2, dielectric ring 3 and press strip 4 as external electrode.
Referring to Fig. 5.Column type electrode 1 is overlooked rounded, and the side is " T " word shape, comprises column type electrode body of making of brass 11 and the conductive rubber layer 12 that is bonded in column type electrode body 11 bottoms.The effect of conductive rubber layer 12 is the contact resistances that reduce electrode and sample surface.The thickness of conductive rubber is 0.5mm.
Referring to Fig. 6.The inner ring surface of loop column type electrode 2 is step-like, the outer ring surface upper vertical, and the bottom slopes inwardly; Loop column type electrode 2 comprises loop column type electrode body of making of brass 21 and the conductive rubber layer 22 that is bonded in loop column type electrode body bottom.
Loop column type electrode 2, its internal diameter are r
1Column type electrode 1, its diameter are r
2r
2＜r
1
Referring to Fig. 7.The material of making described dielectric ring 3 is teflon or other insulating material that is easy to process.The inner ring surface of dielectric ring 3 is step-like, is fit to column type electrode 1 and is assemblied in wherein.The outer ring surface of dielectric ring 3 is the scalariform of falling from power, and is fit to be assemblied in the loop column type electrode 2.
Referring to Fig. 8.Certain flexible insulating material that has that press strip 4 usefulness phenoplast or other are easy to process is made thick 1mm; Press strip 4 centers have a circular mounting hole 41, and a rectangle mounting hole 42,43 is respectively opened on both sides.Mounting hole 42,43 is designed to rectangle.Different eyeglass curvature differences, the upper surface of internal and external electrode might be uneven during test, and when in this case press strip being installed, press strip can be crooked, in order still press strip to be installed on the internal and external electrode in this case, just mounting hole 42,43 is designed for rectangle with securing member.
Referring to Fig. 9.Column type electrode 1 is assemblied in the dielectric ring 3 as interior electrode 1; Dielectric ring 3 is assemblied in the loop column type electrode 2, and loop column type electrode 2 is as external electrode 2.Offer a mounting hole 13 at the center of column type electrode 1, on loop column type electrode 2, offer two mounting holes 23,24.Press strip 4 is pressed on loop column type electrode 2, dielectric ring 3 and the column type electrode 1, passes above-mentioned mounting hole with screw 51,52,53 compressing tablet 4 is connected with column type electrode 1 with loop column type electrode 2.Column type electrode 1 and dielectric ring 3 loose fits, dielectric ring 3 and loop column type electrode 2 wringing fits.
During test, should remove the non-conductive layer of sample surfaces, the conductive rubber layer 11,12 of inside and outside two electrodes 1,2 all should all contact the sample surface, after two screws 51,52 (or 53) of internal and external electrode 1,2 locate to put the contact chip (not shown), the lead that clamping is connected with direct current bridge or dc digital voltmeter reads R on direct current bridge or dc digital voltmeter
sBe worth, and obtain surface resistivity ρ by formula (8)
s, obtain SE by (5) formula again.
Embodiment 1
Screw is unclamped, two little contact chips of direct current bridge are enclosed within respectively on the screw, clamp, then screw is screwed.
Inside and outside two electrodes of glasses for preventing electromagnetic radiation electromagnetic shielding performance testing device are placed on the surface of tested glasses, and the conductive rubber layer of inside and outside two electrodes contacts the surface of tested glasses.
Regulate direct current bridge, behind bridge balance, read R
sBe worth, and obtain surface resistivity ρ by formula (8)
s, obtain SE by (5) formula again.
More than show and described ultimate principle of the present invention, principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that describes in the foregoing description and the instructions just illustrates principle of the present invention; the present invention also has various changes and modifications without departing from the spirit and scope of the present invention, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.
Claims (9)
1, the method for testing of glasses for preventing electromagnetic radiation electromagnet shield effect is characterized in that, may further comprise the steps:
1) measures the surface resistance R of the anti-electromagnetic radiation coating of described glasses for preventing electromagnetic radiation
S, draw the surface resistivity ρ of described anti-electromagnetic radiation coating
s
2) with resulting surface resistivity in the step 1), the following formula of substitution obtains shield effectiveness SE
Z in the formula
oBe the space wave impedance, its value is 377 Ω.
2, the method for testing of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 1 is characterized in that, draws the surface resistivity ρ of the anti-electromagnetic radiation coating of described glasses for preventing electromagnetic radiation by following steps
s:
1) preparing a bottom surface is the external electrode of annular, and the annular internal diameter of bottom surface is r
1One bottom surface is circular interior electrode, and the diameter of the circle of bottom surface is r
2r
2＜r
1
2) described external electrode and described interior electrode are pressed on the anti-electromagnetic radiation coating surface of described glasses for preventing electromagnetic radiation, and make described external electrode concentric with described interior electrode; Utilize direct current bridge or dc digital voltmeter to measure the surface resistance R of the anti-electromagnetic radiation coating between described external electrode and the described interior electrode
S
3) with step 2) in the surface resistance R measured
SThe substitution following formula is tried to achieve the surface resistivity ρ of described anti-electromagnetic radiation coating
s
3, a kind of proving installation of realizing the glasses for preventing electromagnetic radiation electromagnet shield effect of the described method of claim 2 is characterized in that, comprising:
One bottom surface is the external electrode of annular;
The bottom surface that one diameter is littler than the internal radius of the bottom surface of described external electrode is circular interior electrode; Described external electrode is concentric with described interior electrode;
One direct current electric bridge or dc digital voltmeter.
4, the proving installation of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 3 is characterized in that: described external electrode is loop column type, and described interior electrode is column type.
5, the proving installation of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 4, it is characterized in that: also comprise the dielectric ring that an insulating material is made, electrode is assemblied in the ring of described dielectric ring in described, and described dielectric ring is assemblied in the ring of described external electrode.
6, the proving installation of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 5, it is characterized in that: also comprise the press strip that an insulating material is made, have three mounting holes in alignment on the described press strip, have two corresponding mounting holes on the described external electrode, have a corresponding mounting hole on the electrode in described, pass above-mentioned mounting hole by screw press strip and described external electrode, interior electrode are assembled.
7, the proving installation of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 5 is characterized in that: the material of making described dielectric ring is a teflon.
8, the proving installation of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 5 is characterized in that: the material of making described press strip is phenoplast.
9, the proving installation of glasses for preventing electromagnetic radiation electromagnet shield effect according to claim 5 is characterized in that: described external electrode comprises layer of brass and conductive rubber layer, and described interior electrode also is like this.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007100476465A CN101424719A (en) | 2007-10-30 | 2007-10-30 | Method for shielding capacity test of glasses for preventing electromagnetic radiation and device for implementing the method |
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|---|---|---|---|
| CNA2007100476465A CN101424719A (en) | 2007-10-30 | 2007-10-30 | Method for shielding capacity test of glasses for preventing electromagnetic radiation and device for implementing the method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105812071A (en) * | 2014-12-30 | 2016-07-27 | 展讯通信（上海）有限公司 | Wireless signal penetration test system, penetration test device therefor and wireless signal penetration test method |
| CN109640613A (en) * | 2018-12-12 | 2019-04-16 | 许露敏 | A kind of reply New-energy electric vehicle EMC way to solve the problem |
-
2007
- 2007-10-30 CN CNA2007100476465A patent/CN101424719A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105812071A (en) * | 2014-12-30 | 2016-07-27 | 展讯通信（上海）有限公司 | Wireless signal penetration test system, penetration test device therefor and wireless signal penetration test method |
| CN109640613A (en) * | 2018-12-12 | 2019-04-16 | 许露敏 | A kind of reply New-energy electric vehicle EMC way to solve the problem |
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Open date: 20090506 |