DE19809808B4 - screen wall - Google Patents

Abstract

Screen wall, especially for the shielding of ladders, cables, busbars, Assemblies, devices, housings, rooms Plug or electrical connections, characterized the screen wall has at least one electrically insulating bonding layer or plastic or resin layer which is interspersed with electrically conductive Particles, such that the particles under themselves no electrical Contacts and the overall layer is an electrically insulating and reflective Screen wall forms.

Description

The The invention relates to a screen wall, a method and the use in particular for the shielding of conductors, cables, busbars, Assemblies, devices and rooms.

The whole shielding technology has become a complex field of expertise. On the one hand was the quality the signal transmission with as possible Higher tensions increased enormously. On the other hand, however, are the sources of interference Increased to an extent that often disturbed the signal reception and even can be questioned. The most important way out of this dilemma are optical fibers, which prevail increasingly with longer transmission lines. The whole electronics builds however on the electronic signal processing on. This means that probably between the electronic processing sites Optical fibers can be used, which are insensitive to electrical or magnetic interference fields. However, this requires a double signal conversion in each case from the electrical side to the light signal and vice versa. These it is only short signal conductors of less than a meter or only a few meters as in house installations, so is the corresponding two-fold implementation in many applications not economically viable. Decisive is also the nature of the interference field conditions, it is it bothers about a far field or a near field. In the case of magnetic Near fields outweighs mostly inductive interference. For shielding here steel sheet and highly permeable materials used. Cables, lines, assemblies and devices are made by ferromagnetic Umbrellas like pipes, metal hoses and steel plate vessels protected against low frequency magnetic fields. Such as Faraday cages trained umbrellas conduct the magnetic field to be protected Object over.

• – Innerhalb einer metallisierten, elektrisch leitfähigen Gehäusehaut werden durch die Abschirmung Resonanzeffekte erzeugt, da die leitfähigen Wände einen Hohlraumresonator bilden.
• – Besonders bei Leitern und Kabeln können Reflexionserscheinungen aus einer metallisierten Abschirmung zu Reflexionserscheinungen führen. Diese sind eine Folge von nicht idealen Leitungseigenschaften und können ganz besonders bei pulsartigen Signalen zu Verzerrungen der Nutzsignale führen.

In the case of electric near fields, the capacitive influence predominates. In contrast, especially copper and aluminum coatings are used as screen material. Especially when it comes to high-frequency fields, non-magnetic screens are used. These are aluminum and copper wire mesh. Housing made of plastic-metal composite materials or coated with conductive paint plastic housing in which form eddy currents, the interference field is attenuated by energy extraction. A conductive connection between these electrically conductive shields and the reference potential or the conductive shields and the earth is not absolutely necessary to achieve the shielding effect, but always recommended for the elimination of capacitive coupling. This is especially true for longer lines outside the home. Grounding also prevents electrostatic charge. The new invention in itself deals in particular with non-magnetic screens. Furthermore, the radiation influence by high-frequency interference fields or electromagnetic waves, be it from near fields or far fields, is very much in the foreground. The occurrence of electromagnetic waves on electrically conductive arrangements caused by antenna effect high-frequency (RF) - voltages that affect the circuits directly or in rectified form as interference voltages, and in extreme cases can not only lead to deterioration of the signal transmission but possibly to tragic false signals. The best known practice for shielding entire housings is to metallize most of the inner surface. In this case, copper, zinc, nickel, aluminum, etc. can be used. Two disadvantages must be taken into account:

• Within a metallized, electrically conductive housing skin, resonance effects are produced by the shield, since the conductive walls form a cavity resonator.
• - Especially with ladders and cables reflections from a metalized shield can lead to reflection phenomena. These are a consequence of non-ideal line characteristics and can especially lead to distortion of the useful signals in the case of pulse-like signals.

Everyone Developer and professional installer of electronic components or the laying of ladders and components knows from experience, that every specific shielding technique has both special advantages as well as special disadvantages. In practice, given locally, very often the disadvantages are also very significant for specific conditions.

From the DE 41 28 908 C2 is a coaxial cable with at least one inner conductor, an insulation and a latter surrounding flexible metal braid for radio frequency (RF) shielding known, wherein the Abschirmnetlecht consists of metallic wires and is provided with a metallic solder layer to ensure the RF-tightness, wherein the Lotschicht predominantly covers the outwardly facing surfaces of the Abschirmgeflechtes and fills the gaps between the wires forming the Abschirmgeflecht, while the contours of the wires are kept free of solder for insulation, so that the flexibility of Abschirmgeflechtes is largely maintained.

From the DE 43 21 719 C1 a shielding is known, wherein in the implementation region of the connector parts from the housing an insulating film is arranged, which comprises the plug connection parts annularly on the peripheral surfaces, wherein in the insulating oxidized metal particles are embedded, and the insulating foil in contact with the metalli inside the housing.

From the DE 195 39 473 A1 For example, a shielding wall is known that reflects electromagnetic waves.

Of the Invention has now been the task, especially at higher frequencies to improve your own signal transmission with simple means, safer against disturbances, Losses to reduce this especially in combination with known Shielding techniques while avoiding their disadvantages. Further Part of the task was also passive shielding, ie the interference effect external interfering signals into the interior, be it from housings or rooms, though also of conductors, cables, busbars, assemblies, devices, plugs and to improve electrical connections.

The invention solution is characterized in that the screen wall at least one electrically insulating bonding layer or plastic or resin layer which is interspersed with electrically conductive particles, such that the particles do not have any electrical contacts and the overall layer is an electrically insulating and reflective Screen wall forms.

• – einer elektrisch isolierenden Schutzschicht
• – der Reflexionswirkung ohne Resonanzeffekt und
• – einer metallischen Reflexion, potentialfrei ohne elektrische Leiterwirkung

The new invention solves the problem very simply and effectively, by the combinatorial effect of:

• - An electrically insulating protective layer
• - The reflection effect without resonance effect and
• - A metallic reflection, potential-free without electrical conductor effect

Already first attempts with a signal transmission cable from a computer to a sound and picture station showed one like that big effect, that this in the blind attempt of present persons beyond doubt approved could become. In the example, the sound image has been improved significantly. The new invention further allows a number of particular preferred embodiments. The electrically conductive particles are preferred Metal particles, especially non-magnetizable particles, in particular Aluminum or copper particles and form particularly preferably a multi-layer reflector wall. The invention requires that metallic particles, which in themselves are ideal electrical conductors, At least not touching each other to a greater extent metallic. Would the Directly produce metallic contacts, such as sintered metals, would the conductivity be almost the same as the compact metal material itself Particles can Dimensions in the range of a thousandth of a millimeter (μm) up to 10 to 20 μm or have more. The size refers primarily to the areal extent. The corresponding Thickness of the particles may e.g. between 1 .mu.m and a few microns. Assuming a thickness of the screen wall of e.g. 10 to 100 microns, then arise, over seen the thickness, many levels of reflection. Every level of reflection for themselves is like holes, as the particles pass through the filler are separated from each other. The "reflection holes" of a first adopted Layer are themselves by a second, third, etc., so at the latest lifted in several layers. The reflection effect can ever be made equivalent to layer thickness, as in the usual surface metallization with layer thicknesses of e.g. 2 μm up to 100 μm.

The proportion of the metal particles should be at least 10%, preferably more than 20%, and the layer thickness of the screen wall particularly preferably 10 μm to 100 μm. At least a large proportion of the particles advantageously has a two-dimensional shape, wherein they occupy a preferred coplanar position relative to the areal extent of the screen wall. The reflection effect is much more determined by the areal extent of the screen wall than by the thickness of the particles. The more the particles have a platelet structure and, when applied, are aligned coplanar with the surface of the screen, the smaller the proportion of the particles can be. The more particles that are on top of each other, the better the positive effect. Depending on the application, the reflective screen wall can be applied liquid or dry, for example sprayed on, or be applied by dipping or powder coating or screen printing or applied as a film or compact material of any thickness. If the screen wall is applied over the liquid form, for example in a spray or spray process, the solvent volatilizes after application. Very good results have been achieved when the screen wall after volatilization of a solvent has a mixing ratio of synthetic resin to aluminum particles in the range of preferably 30 to 70 and when coated has a glossy reflective surface. The glossy surface is mainly due to flat parallel to the layer lying particles to conditions. In the case of cables, the inventive reflective screen wall can also be applied by means of previously coated paper or plastic films or tapes. Very good screen effects were achieved when the screen wall is designed as a protective screen for a signal transmission conductor and is mounted as a reflective insulation directly on the signal transmission conductor or dielectric or in the case of a multi-layered screen structure as a closed cladding layer within the multi-layer structure. This is especially true when the shield is designed for a coaxial cable or other cable where in addition, at least one shielding braid should be present in the protective screen. It has not been possible to clarify for sure whether the good effect is achieved by the fact that the reflection wall acts inwards or outwards. But both are also possible as a collaboration. After one effect, the reflector would have as it were a holding function for the signal transmission, since almost no energy emitted from the signal voltage waveform to the outside or builds secondary voltages in a conductive jacket. Conversely, from the outside, very less RF interference fields, be it near fields or far fields, can pass through the reflection wall into the sensitive area of the signal conductor. Most preferably, the inventive screen wall is used as a whole in combination with known shielding techniques or shielding. This can also be mounted directly above or below a conductive grid, since the reflective screen wall is electrically non-conductive.

The Invention relates, as stated, a coaxial cable with a multi-layered screen, in particular for connecting electronic components and / or computers, and is characterized in that the screen at least one electrically insulating Binding layer or plastic or resin layer has completely penetrated is with electrically conductive Particles, such that the particles have no electrical contacts and the overall layer has an electrically insulating and reflective screen wall forms.

Further The invention relates to a plug connection for the digital or analog transmission of Signals with at least one shielding layer, and is characterized in that the plug connection has at least one electrically insulating binding layer as a plastic or resin layer which completely penetrates is with electrically conductive Particles, such that the particles have no electrical contacts and the overall layer is an electrically insulating and reflective Screen wall forms. The simplest solution is that the Plug connection before the encapsulation the reflective screen wall, whether applied by dipping, spraying or painting, since the invention Umbrella material has an insulating effect. You can do this too apply directly to the bare signal conductor. But it can too previously a non-conductive resist and only then the reflective Screen wall are applied. As the outermost layer can still a conductive Ground or earth-connectable jacket can be attached.

The The invention further relates to a printed circuit board, in analogy to Plug connection is proceeded and is characterized that it has at least one electrically insulating binding layer as the screen or plastic or resin layer which completely penetrates is with electrically conductive particles, such that the particles have no electrical contacts and the overall layer forms an electrically insulating and reflective screen wall.

All the reflective screen wall according to the invention is particularly preferred e.g. in combination with a much thinner layer of a purely metallic one Order or used in combination with a shielding braid. It can be as before sheet metal panels of the device housing or made of plastic-metal fiber composite materials use. It can be the intrusion of foreign fields as well the emission of RF fields are greatly reduced. The starting from the outside Electromagnetic waves are partially absorbed in the housing walls and radiated through the reflective layer. In many cases will the reflective screen wall preferably attached outside to a harmful Reflection inside or to prevent a harmful resonator effect. Further leaves the reflective screen wall even with a sonnenstorenartigen screen wall as an external one Reflector or fine tissue as tissue screen or on apply to the appropriate blades. Thus, special spaces, e.g. Laboratory or measuring rooms but also rooms in the private sector such as living spaces especially bedrooms be shielded in the presence of extreme radio frequency interference.

In the consequence of the invention will now be based on some examples explained.

It demonstrate:

the 1 schematically a cut end of a coaxial cable;

the 1a a section II the 1 ;

the 2 a micrograph of the reflective screen wall;

the 2a a slightly larger section;

the 3 an example of an antenna signal cable;

the 4 a connection monitor printer;

the 5 a connection DA converter amplifier;

the 6 and 6a two examples of printed circuit boards;

the 7 a partial section of an apparatus housing;

the 8a - 8d different room screens in buildings.

The 1 shows a simple coaxial cable 1 with an inner conductor 2 that is directly connected to a first dielectric 3 is surrounded. Directly after the dielectric is a screen reflector or a reflective screen wall 4 to which an electrically conductive shielding braid or Foke 5 follows. To the outside, the coaxial cable is surrounded by an insulating protective jacket. Between the inner dielectric 3 and the shielding braid 5 is a second dielectric 7 arranged. The illustration is only schematic and, as in the prior art, may include the great majority of possible variations. It is also conceivable to combine the screen wall with a metallically conductive layer, especially if a separate function is sought inwardly for the signal conductor and to the outside against interference fields.

• – zwischen Metallpartikeln hat es im wesentlichen keine elektrischen Leiterkontakte;
• – die Austrittstiefe des Messsignals an dem Elektronenmikroskop;
• – die Reflexion.

The 2 is a micrograph with an electron microscope as a top view. With the scale specification 10 mm, the order of magnitude of the particles 10 and the black appearing carrier substance as a resin 11 be made apparent. It should be noted that in the case of 2 a radiation intensity Eo of 10 keV and at the 2a a radiation intensity Eo of 20 koV was chosen. An important parameter here is the range R in μm and the exit depth T also in μm. At carbon, the range at 10 keV is 2.69 μm, at 20 keV at 7.25 μm and the exit depth at 10 keV is 0.97 μm and at 20 keV is 2.82 μm. For aluminum, the range is 10 keV 10 μm. The images were sprayed with a mixture of aluminum pigments and a synthetic resin on a support, with a layer thickness of 20 to 50 microns. For the evaluation of the recordings three aspects are important:

• - Between metal particles, it has essentially no electrical conductor contacts;
• The exit depth of the measurement signal at the electron microscope;
• - the reflection.

The Exit depth for the aluminum is between 0.36 μm and 2.69 μm. This means that the detected Layer thickness is 1/100 to 1/10 of the total layer. With other words, that would be cut the spray layer into 10 or 100 layers of 0.36 to 2.69 μm thickness would have been you always get an analog picture. In fact, the shielding effect was in the illustrated pattern best. The chosen recording technique, namely electron microscopy is synonymous with the basic task of the invention. Also if the connections between the action of single electrons and an electrical one Interference field only As is well known, the relationship used becomes general accepted. Each microscopically recorded layer thickness shows very clearly the total reflection effect as white spots. The complete reflection effect from the total layer results from the sum of thought Layers of a few mm. The synthetic resin is the insulating material. At the low current of at most a few volts commonly present on signal lines, the resin acts as a very good insulator from particle to particle.

The 3 shows one of the most popular applications of coaxial cables 1 for televisions. In this case, a connection is made by an antenna 20 to a computer converter 21 to a screen 22 ,

The 4 shows an example of a coaxial cable connection between a monitor 30 and a printer 31 , In the 3 is only schematically a transmitter 23 shown, which may be a source of interference for the coaxial cable. The same is true for the monitor 30 as well as the pressure 31 , Depending on the quality of the shielding of each electrical-electronic device, these are at the same time sources of interference for other data processing, especially of data conductors, or they are disturbed even by third parties.

The 5 shows a drive 40 and DA converter and an amplifier 41 , Drive and DA converter are via an analog cable 42 connected to the amplifier, which also has a reflective screen wall. The reflective screen wall can also be used with test plates 50 eg one-sided like 6a or in a middle parting plane.

The 7 shows a device housing 60 , It can depending on the use and material of the housing reflective screen 4 inside or outside, as indicated by dash-dotted lines are arranged. Another possibility is that large openings through a gauze 61 be covered, which is treated on one or both sides according to the invention with reflective screen material.

In many cases, it is sufficient, especially in the case of highly sensitive measuring devices, that only the lower bottom area of the housing is provided with a housing wall according to the invention. As an example of a device screen, reference is made to WO96 / 35371 , which is fully explained as part of the present application. The point is that, as far as possible, the electronic part of individual measuring instruments is kept free from external interference fields, be it in the area of the printed circuit board or of the meter housing.

The 8th shows in each case with a thick, black line still another, very interesting field of application, namely the protection of larger spaces, as equipment or work, especially living room and bedroom. Here, the electrically insulating and reflective screen wall is applied to the building walls, building corners and floors. In the process, sensitive areas are primarily protected. Depending on the type and direction of the radiation from high frequency to the highest frequencies, for example, only the inside of the roof as in 8a or just a building side, as in the 8b is shown shielded. If the attic is not used, so can only one or more basement levels according to 8c or only a single room according to 8d For example, a bedroom to be shielded. Especially interesting is the arbitrary combinability of the base material according to claims 1 to 5. Since the material already has a sufficient proportion of plastic or resin fractions, it can additionally be dyed as a paint. The material can also be combined with a plastering material, whether it is mixed directly as a binder or applied as a separate layer or paint on building walls and ceilings. The screen wall can be mounted inside or outside the building and used for example as a layering of a wallpaper or fine fabric or textile material such as curtain or a heat insulating material or other covering materials such as ceramic or wall panels or powder coating. This makes it possible to form shielded cells within a building, without the disadvantages of electrically conductive layers. For this purpose, reference is made to claims 11 and 12. Depending on the material connection, the screen wall can be used completely concealed, ie not as a visible layer, but as any layering within the wall, floor or ceiling parts, for example, the adhesive side of wallpaper can be used.

Claims (12)

Umbrella wall, in particular for the shielding of conductors, cables, busbars, modules, devices, housings, rooms, plugs or electrical connections, characterized in that the shielding wall has at least one electrically insulating bonding layer or plastic or resin layer which is interspersed with electrically conductive particles, such that the particles do not form any electrical contacts and the overall layer forms an electrically insulating and reflective screen wall. Umbrella wall according to claim 1, characterized that the electrically conductive Particles Metal particles, non-magnetizable particles in particular Aluminum or copper particles, and preferably a multilayer Form reflector wall. Screen wall according to claim 1 or 2, characterized the proportion of the metal particles is preferably at least 10% more than 20% and the layer thickness of the screen wall particularly preferably 10 μm to 100 microns. Umbrella wall according to claim 1 to 3, characterized that at least a large proportion of the particles have a planar shape and this has a preferred coplanar position to the areal extent take the screen wall. Umbrella wall according to claim 1 to 4, characterized that the screen wall after volatilization of a solvent a mixing ratio from resin to aluminum particles in the range of preferably 30 to 70% and in the applied state has a shiny, reflective surface. Screen wall according to claims 1 to 5, characterized in that that they serve as a protective screen for a signal transmission conductor is formed and as a reflective insulation directly on the signal transmission conductor or dielectric or in the case of a multi-layered screen structure as a closed cladding layer within the multilayer construction is appropriate. Umbrella wall according to claims 1 to 6, characterized that they serve as a protective screen for a coaxial cable is formed, wherein the protective screen additionally at least a shielding braid. Coaxial cable with a multi-layered screen, in particular for the connection of electronic components and / or computers, thereby characterized in that the screen at least one electrically insulating Binding layer or plastic or resin layer has completely penetrated is with electrically conductive Particles, such that the particles have no electrical contacts and the overall layer an electrically insulating and reflective screen wall forms. Plug connection for digital or analog transmission of signals with at least one shielding layer, characterized in that the plug connection has at least one electrically insulating Bonding layer as a plastic or resin layer which passes completely is with electrically conductive Particles, such that the particles have no electrical contacts and the overall layer is an electrically insulating and reflective Screen wall forms. Printed circuit board, characterized in that it as Umbrella at least one electrically insulating bonding layer or Plastic or resin layer has completely penetrated is with electrically conductive Particles, such that the particles have no electrical contacts and the overall layer is an electrically insulating and reflective Screen wall forms. Use of the screen wall according to one of claims 1 to 5 for large screens especially in whole rooms by applying coated films, mats, wallpaper or paints or plaster on walls and / or floors and / or blankets. Method for creating a screen wall, characterized characterized in that the electrically insulating bonding layer or Plastic or resin layer as a mixture of a plaster or painting material is mixed and after application to the space boundary surfaces a forming reflective screen wall.