EP0391267A1 - Variable resistance - Google Patents

Variable resistance Download PDF

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Publication number
EP0391267A1
EP0391267A1 EP90106098A EP90106098A EP0391267A1 EP 0391267 A1 EP0391267 A1 EP 0391267A1 EP 90106098 A EP90106098 A EP 90106098A EP 90106098 A EP90106098 A EP 90106098A EP 0391267 A1 EP0391267 A1 EP 0391267A1
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EP
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Prior art keywords
hard coating
potentiometer
layer
potentiometer according
grinder
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German (de)
French (fr)
Inventor
Hans Hohmann
Ernst Halder
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Horst Siedle KG
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Horst Siedle KG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C10/00—Adjustable resistors
    • H01C10/30—Adjustable resistors the contact sliding along resistive element
    • H01C10/308—Adjustable resistors the contact sliding along resistive element consisting of a thin film

Definitions

  • the invention is based on a potentiometer according to the preamble of claim 1.
  • Potentiometers are known in a variety of forms, so that the following is only representative of a publication for many in the form of DE-OS 32 24 069, which describes the basic structure of a precision rotary potentiometer in more detail.
  • a carrier flange supports a plate on which a resistive ground path interrupted to supply the voltage applied to the potentiometer, usually based on conductive plastic, and optionally a continuous collector ring ground path are applied.
  • the carrier flange also supports, possibly via ball bearings, a shaft which in turn carries the tap that leads in the transverse direction from the shaft a grinder attached to it over the resistance track or track and possibly the collector track or track.
  • the grinder can be a one-piece metallic sliding part and usually consists of a number of individual grinder fingers arranged side by side, which slide on the resistance track and the collector track, so that the tapped voltage can be transferred to the collector and then removed from it.
  • the invention is not limited to such a precision rotary potentiometer, but is suitable for all types of variable resistors, linear series resistors and potentiometers, in particular for those in which very rapid movements can be implemented, for example when they are used as sensors or actual value transmitters in machines or overrun controls are used or in the form of rotary potentiometers for example for generating sawtooth voltages and.
  • Special embodiments of such precision potentiometers which additionally have a damping plastic coating in the grinder area, are able to carry out rotational or longitudinal movements which can be repeated millions of times, sometimes at very high speeds, with the need for the original linearization and to maintain the voltage gradient as pristine as possible over the life of the element, even with appropriate aging, wear and tear.
  • the abrasive wear that usually occurs is linear wear and can be more or less predicted in relation to the service life, i.e. over time, also in its effects and in the changes that are likely to result from the data of the potentiometer.
  • a second, much more unpleasant wear effect is the so-called adhesive wear, which results in a pairing of grinder and piste material, for example, in that one of the partners picks up material from the other partner and attaches itself to it, so that it sticks, for example, to this receiving partner.
  • this adhesive wear closes a qualified forecast, since it occurs more or less statistically and it is not always guaranteed that it is the "hard" partner in the material pairing that is stronger is affected.
  • the adhesive wear is therefore based on transport mechanisms between the two partners and probably depends mainly on metallic surface tensions, for example of the grinder material, so that in the event of an unfortunate pairing, instead of the usual interface ratio of grinder material / runway, a double transition must be expected, i.e. grinder / runway material / runway . Due to its metallic surface tension, the grinder tries to coat itself with other, available material, and this is then usually the slope material of the conductive plastic base. This can result in significantly changed resistance conditions in the transition area between runway and tap.
  • the invention has for its object to remedy this situation and to ensure with a potentiometer of any kind that, while generally avoiding signs of wear, so-called adhesive wear can be avoided.
  • the invention solves this problem with the characterizing features of the main claim and has the advantage that usually very thin, applied on the basis of plasma technology processes Hart layers, preferably with a metal additive, have both very good wear and sliding properties and, as tests have shown, are protected against any type of adhesive wear and can therefore also protect grinders, on the sliding surfaces of which they are preferably applied.
  • a grinder coated in this way can, for example, run through with a rotary potentiometer in the order of magnitude of 10 million until a removal of this plasma-coated hard coating layer occurs approximately in the more protruding central region of the sliding finger sliding surface. It can then be ascertained that after only a further shorter operating time, there are again signs of wear and tear on the actual grinding material exposed by the removal of the hard coating layer, i.e. an accumulation of conductive plastic material here, while the adjacent surfaces, which still have the hard coating coating, are completely clean and remain unaffected. This also clearly gives the advantage that can be realized on the basis of such a coating in the sliding range of potentiometers.
  • the hard coating layer can also be applied to the conventional resistance element, that is to say to the conductive plastic base, which results in the advantages mentioned in connection with suitable grinding systems; in preferred Embodiment of the invention, however, are the grinder systems themselves, which are coated by plasma technology alone or in addition to a hard coating layer on the resistance element, so that, in addition to the general reduction in wear, substantial improvements in the area of the required torque grinder / runway can be achieved.
  • the advances made in the field of plasma technology mean that hard coating layers can be applied in the region or at least close to room temperature ( ⁇ 200 ° C.), so that plastic materials, which can also be used, are noticeably influenced, for example also the already mentioned conductive plastic material for the resistance and collector slopes can be excluded.
  • metal additives with very good wear and tear Sliding properties can be used, for example, tungsten (W), tantalum (Ta) and niobium (NB).
  • metal-containing hydrocarbon compounds metal-containing hydrogenated carbon films
  • coatings or films which are applied to carriers on the basis of plasma-technological processes are already known per se, for example from the publication: Appl. Phys. Lett. 50 (16), April 20, 1987 as an essay by H. Dimigen, H. Hübsch and R. Memming from the Philips GmbH Research Laboratory Hamburg.
  • the drawing shows a top view in a special application on a rotary potentiometer parallel resistance and collector slopes, which are swept by a common grinder.
  • the basic idea of the present invention is to include at least one of the sliding partners that result from a variable resistor or potentiometer, that is to say wipers and / or the conductive plastic base to provide a hard coating layer produced according to plasma technology aspects, so that, in addition to a general reduction in abrasive wear, mainly adhesive wear is eliminated.
  • a carrier plate 10 is provided, on which a resistance track 12 and a collector track 14 are located.
  • a central axis 15 supports, for example fastened via a snap ring 16, a (metallic) tap 17, which in turn supports a grinder consisting of several individual grinder fingers 18 and 19 in such a way that its resilient end regions on the resistance track 12 and the collector track 14 lies on.
  • the resistance track is interrupted at 20, that is to say has end regions which serve for the external supply of voltage.
  • Resistance track or track and collector track or track usually consist of a special conductive plastic material on which the wiper fingers slide, which are usually made of an alloy of certain noble metals such as palladium gold, platinum and the like. can exist, but as a result of this coating can now also consist of less expensive materials, such as copper beryllium or stainless steel.
  • the underside of the grinder fingers in the front attachment i.e. where these grinder fingers with their contact surfaces on the conductive plastic layers slide from resistance and collector slopes, is provided according to the present invention with the hard coating layers, which are applied on a plasma-technological basis, so that layers result in so-called metal-carbon hydrogens or graphite-carbon hydrogens, but also insulating polyamide layers.
  • the hard coating layers are applied on a plasma-technological basis, so that layers result in so-called metal-carbon hydrogens or graphite-carbon hydrogens, but also insulating polyamide layers.
  • the graphite-carbon hydrogen layers gain the electrical conductivity that is required, while insulating polyamide layers in the form of hard coatings preferably work with very thin layer thicknesses, for example in the range of 10 nanometers. This small layer thickness makes it possible to make the polyamide insulation layer electrically invisible, the conductivity being able to be taken over, for example, by tunnel electrodes.
  • the other and preferred type of hard coating layer formation comprises the metal or. Graphite hydrocarbons.
  • Plasma technology enables the production of such layers by physically making homogeneous layer deposits from a plasma cloud.
  • This mainly includes the so-called high-vacuum sputtering technique, which can be used to apply extremely dense and smooth, very thin layers in the range between 10 nanometers to about 2000 nanometers, consisting of different types of materials, such as metal compounds, oxides, nitrides or carbides .
  • plastics can also be metallized in this way.
  • the basic form of a plasma-technological layer application takes place in such a way that a highly ionized vapor is assumed (plasma).
  • plasma a highly ionized vapor
  • This can be achieved by applying a bias or by supplying a beam of accelerated particles, in the first case a decomposition of hydrocarbons into the plasma form caused by the bias or in the second case an ion beam decomposition. By doing so, thin films with the desired properties can be deposited.
  • plasma technology processes are known per se, they are not dealt with in more detail below; for example, reference is made to the publication mentioned.
  • the known separation processes for the extraction of hydrocarbons can be divided into the separation of hydrocarbon gases and those in which solid carbon is used as the carbon source itself.
  • methane, ethane or the like can be broken down by glow discharge and carbon ions can be formed. These ions are then accelerated towards an electrically biased substrate.
  • Laser or arc vaporization of hydrocarbons may be considered when using solid hydrocarbon. It is also possible to work in combination, i.e. both fixed Use carbon as well as a hydrogen carbon gas or hydrogen as a source of jet particles.
  • the main plasma technology manufacturing processes therefore include physical vapor deposition, ion implantation, and possibly thermal spray processes, i.e. wherever surface modification of materials results in the formation of special hard-coating layers on the basis of plasma technology.
  • these layers are then to be determined or selected such that adhesive wear possibilities are excluded. This can be achieved, for example, by applying diamond-like and graphite-like hydrocarbon layers (DLC; GLC) - supplemented by metal additives where this makes sense due to the required conductivity.
  • DLC diamond-like and graphite-like hydrocarbon layers
  • metal additives where this makes sense due to the required conductivity.
  • metal-carbon hydrogens and graphite-carbon hydrogens which are mainly used as coatings for grinding surfaces in potentiometers and the like. Like systems come into question.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Adjustable Resistors (AREA)
  • Details Of Resistors (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

In a potentiometer, especially in the form of a precision potentiometer which can be rotated rapidly, or of a linear movement sensor for generating feedback parameters in the case of machines, it is proposed that the resistor track or collector track on the one hand and/or the sliding surfaces, facing these tracks, of a wiper or of wiper fingers be coated with an additional hard coating layer, produced on the basis of a plasma-technology process, so that diamond-like carbon- or graphite-like carbon coatings are produced, preferably with metal additives, or also very thin insulating polyamide layers. This counteracts, in particular, adhesive wear. <IMAGE>

Description

Stand der TechnikState of the art

Die Erfindung geht aus von einem Potentiometer nach dem Oberbegriff des Anspruchs 1.The invention is based on a potentiometer according to the preamble of claim 1.

Potentiometer sind in vielfältiger Form bekannt, so daß im folgenden lediglich stellvertretend auf eine Veröf­fentlichung für viele in Form der DE-OS 32 24 069 verwiesen wird, die den grundsätzlichen Aufbau eines Präzisions-Drehpotentiometers genauer beschreibt.Potentiometers are known in a variety of forms, so that the following is only representative of a publication for many in the form of DE-OS 32 24 069, which describes the basic structure of a precision rotary potentiometer in more detail.

Üblicherweise sind daher Präzisions-Drehpotentiometer im Grundaufbau so getroffen, daß ein Trägerflansch eine Platte lagert, auf welcher eine zur Zuführung der am Potentiometer anliegenden Spannung unterbroche­ne Widerstandsmassebahn, üblicherweise auf Leitplastik­basis sowie gegebenenfalls eine durchlaufende Kollek­torring-Massebahn aufgebracht sind. Der Trägerflansch lagert ferner, gegebenenfalls über Kugellager, eine Welle, die ihrerseits den Abgriff trägt, der in Querrichtung von der Welle ausgehend einen an ihm befestigten Schleifer über die Widerstandspiste oder -bahn und gegebenenfalls die Kollektorpiste oder -bahn führt. Der Schleifer kann ein einstückiges metallisches Gleitteil sein und besteht üblicherweise aus einer Anzahl nebeneinander angeordneter einzelner Schleiferfinger, die auf der Widerstandspiste und der Kollektorpiste gleiten, so daß die abgegriffene Spannung auf den Kollektor übertragen und dann von diesem abgenommen werden kann.Usually, therefore, precision rotary potentiometers are made in the basic structure in such a way that a carrier flange supports a plate on which a resistive ground path interrupted to supply the voltage applied to the potentiometer, usually based on conductive plastic, and optionally a continuous collector ring ground path are applied. The carrier flange also supports, possibly via ball bearings, a shaft which in turn carries the tap that leads in the transverse direction from the shaft a grinder attached to it over the resistance track or track and possibly the collector track or track. The grinder can be a one-piece metallic sliding part and usually consists of a number of individual grinder fingers arranged side by side, which slide on the resistance track and the collector track, so that the tapped voltage can be transferred to the collector and then removed from it.

Die Erfindung ist nicht auf ein solches Präzisions-­Drehpotentiometer beschränkt, sondern für alle Arten von Stellwiderständen, linearen Längswiderstän­den und Potentiometer geeignet, insbesondere für solche, bei denen sehr schnell ablaufende Bewegungen zu realisieren sind, etwa wenn sie als Sensoren oder Istwertgeber bei Maschinen oder Nachlaufregelun­gen eingesetzt werden oder in Form von Drehpotentiome­tern beispielsweise zur Erzeugung von Sägezahnspannun­gen u. dgl. Spezielle Ausführungsformen solcher Präzisionspotentiometer, die beispielsweise im Schleiferbereich eine dämpfende Kunststoffbeschich­tung zusätzlich tragen, sind in der Lage, mit unter­schiedlichen, zum Teil sehr hohen Geschwindigkeiten sich unter Umständen millionenfach wiederholende Arbeitsdreh- oder Längsbewegungen durchzuführen, wobei die Notwendigkeit besteht, die ursprüngliche Linearisierung und den Spannungsgradienten möglichst unverfälscht über die Lebensdauer des Elementes aufrecht zu erhalten, auch bei entsprechender Alte­rung, bei auftretendem Verschleiß u. dgl. Ein solcher Verschleiß ergibt sich deshalb, weil der auf der Leitplastikbasis gleitende Schleifer mit seinen Fingern (gegenseitigen) Abrieb verursacht, was zu Linearitätsveränderungen und auch zu einer Änderung des Übergangswiderstandes zwischen Schleifer und Piste im Sinne einer Erhöhung führen kann. Die Wirkung des Verschleißes und die Änderung der Lineari­tätsverhältnisse können bis zum Ausfall des Poten­tiometers führen.The invention is not limited to such a precision rotary potentiometer, but is suitable for all types of variable resistors, linear series resistors and potentiometers, in particular for those in which very rapid movements can be implemented, for example when they are used as sensors or actual value transmitters in machines or overrun controls are used or in the form of rotary potentiometers for example for generating sawtooth voltages and. Special embodiments of such precision potentiometers, which additionally have a damping plastic coating in the grinder area, are able to carry out rotational or longitudinal movements which can be repeated millions of times, sometimes at very high speeds, with the need for the original linearization and to maintain the voltage gradient as pristine as possible over the life of the element, even with appropriate aging, wear and tear. The like Wear occurs because the grinder sliding on the conductive plastic base causes (mutual) abrasion with its fingers, which can lead to changes in linearity and also to a change in the contact resistance between grinder and runway in the sense of an increase. The effect of wear and the change in linearity can lead to the failure of the potentiometer.

Hier sind noch genauere Untersuchungen von Bedeu­tung, die auf die spezielle Art des Verschleißes abstellen. Der üblicherweise auftretende abrasive Verschleiß ist ein linearer Verschleiß und kann in seiner Beziehung zur Lebensdauer, also über der Zeit mehr oder weniger vorausgesagt werden, auch in seinen Wirkungen und in den Änderungen, die sich an den Daten des Potentiometers voraussicht­lich ergeben.Here, more precise investigations are important, which focus on the special type of wear. The abrasive wear that usually occurs is linear wear and can be more or less predicted in relation to the service life, i.e. over time, also in its effects and in the changes that are likely to result from the data of the potentiometer.

Eine zweite, wesentlich unangenehmere Verschleißwir­kung ist der sogenannte adhäsive Verschleiß, der sich bei einer Paarung von Schleifer und Pistenmate­rial beispielsweise dadurch ergibt, daß einer der Partner Material von dem anderen Partner aufnimmt und an sich anlagert, so daß es beispielsweise an diesem aufnehmenden Partner festklebt. Dieser adhäsive Verschleiß verschließt sich allerdings einer qualifizierten Voraussage, da er mehr oder weniger statistisch auftritt und auch nicht immer sichergestellt ist,daß es nun gerade der "harte" Partner bei der Materialpaarung ist, der stärker in Mitleidenschaft gezogen wird.A second, much more unpleasant wear effect is the so-called adhesive wear, which results in a pairing of grinder and piste material, for example, in that one of the partners picks up material from the other partner and attaches itself to it, so that it sticks, for example, to this receiving partner. However, this adhesive wear closes a qualified forecast, since it occurs more or less statistically and it is not always guaranteed that it is the "hard" partner in the material pairing that is stronger is affected.

Der adhäsive Verschleiß beruht also auf Transportme­chanismen zwischen den beiden Partnern und hängt vermutlich hauptsächlich von metallischen Oberflächen­spannungen zum Beispiel des Schleifermaterials ab, so daß bei unglücklicher Paarung statt des üblichen Grenzflächenverhältnisses Schleifermaterial/­Piste mit einem doppelten Übergang gerechnet werden muß, also Schleifer/Pistenmaterial/Piste. Durch seine metallischen Oberflächenspannungen versucht der Schleifer sich mit anderem, verfügbarem Material zu überziehen, und dies ist dann üblicherweise das Pistenmaterial der Leitplastikbasis. Hierdurch können sich im Übergangsbereich zwischen Piste und Abgriff erheblich veränderte Widerstandsverhält­nisse ergeben.The adhesive wear is therefore based on transport mechanisms between the two partners and probably depends mainly on metallic surface tensions, for example of the grinder material, so that in the event of an unfortunate pairing, instead of the usual interface ratio of grinder material / runway, a double transition must be expected, i.e. grinder / runway material / runway . Due to its metallic surface tension, the grinder tries to coat itself with other, available material, and this is then usually the slope material of the conductive plastic base. This can result in significantly changed resistance conditions in the transition area between runway and tap.

Der Erfindung liegt die Aufgabe zugrunde, hier Abhilfe zu schaffen und bei einem Potentiometer beliebiger Art dafür zu sorgen, daß unter allgemeiner Vermeidung von Verschleißerscheinungen insbesondere der sogenannte adhäsive Verschleiß vermieden werden kann.The invention has for its object to remedy this situation and to ensure with a potentiometer of any kind that, while generally avoiding signs of wear, so-called adhesive wear can be avoided.

Vorteile der ErfindungAdvantages of the invention

Die Erfindung löst diese Aufgabe mit den kennzeichnen­den Merkmalen des Hauptanspruchs und hat den Vorteil, daß üblicherweise sehr dünne , auf der Basis plasmatechnologischer Vorgänge aufgebrachte Hart­ schichten, vorzugsweise mit Metallzusatz, sowohl sehr gute Verschleiß- als auch Gleiteigenschaften aufweisen und, wie Versuche ergeben haben, gegen jede Art von adhäsivem Verschleiß geschützt sind und daher entsprechend auch Schleifer schützen können, auf deren Gleitflächen sie bevorzugt aufge­bracht werden.The invention solves this problem with the characterizing features of the main claim and has the advantage that usually very thin, applied on the basis of plasma technology processes Hart layers, preferably with a metal additive, have both very good wear and sliding properties and, as tests have shown, are protected against any type of adhesive wear and can therefore also protect grinders, on the sliding surfaces of which they are preferably applied.

Hierbei hat sich herausgestellt, daß ein solchermaßen beschichteter Schleifer beispielsweise Durchläufe bei einem Drehpotentiometer in der Größenordnung von 10 Millionen zurücklegen kann, bis ein Abtrag dieser plasmatechnologisch aufgebrachten Hartcoating-­Schicht etwa im stärker vorspringenden Mittenbereich der Schleiferfinger-Gleitfläche auftritt. Es läßt sich dann feststellen, daß nach nur weiterer kürzerer Betriebsdauer an dem durch den Abtrag der Hart­coating-Schicht freigelegten eigentlichen Schleifer­material wieder adhäsive Verschleißerscheinungen auftreten, also eine Anlagerung hier von Leitplastik­material, während die angrenzenden, noch die Hart­coating-Beschichtung aufweisenden Flächen völlig sauber und unbeeinflußt bleiben. Hieraus ergibt sich auch deutlich der Vorteil, der sich aufgrund einer solchen Beschichtung im Gleitbereich von Potentiometern realisieren läßt.It has been found here that a grinder coated in this way can, for example, run through with a rotary potentiometer in the order of magnitude of 10 million until a removal of this plasma-coated hard coating layer occurs approximately in the more protruding central region of the sliding finger sliding surface. It can then be ascertained that after only a further shorter operating time, there are again signs of wear and tear on the actual grinding material exposed by the removal of the hard coating layer, i.e. an accumulation of conductive plastic material here, while the adjacent surfaces, which still have the hard coating coating, are completely clean and remain unaffected. This also clearly gives the advantage that can be realized on the basis of such a coating in the sliding range of potentiometers.

Grundsätzlich kann die Hartcoating-Schicht auch auf das herkömmliche Widerstandselement, also auf die Leitplastikbasis aufgebracht werden, wodurch sich in Verbindung mit geeigneten Schleifersystemen die erwähnten Vorteile ergeben; in bevorzugter Ausgestaltung der Erfindung sind es aber die Schleifer­systeme selbst, die allein oder zusätzlich zu einer Hartcoating-Schicht auf dem Widerstandselement plasmatechnologisch beschichtet werden, so daß neben der allgemeinen Verschleißreduzierung auch wesentliche Verbesserungen im Bereich der erforder­lichen Drehmomente Schleifer/Piste erzielt werden können.In principle, the hard coating layer can also be applied to the conventional resistance element, that is to say to the conductive plastic base, which results in the advantages mentioned in connection with suitable grinding systems; in preferred Embodiment of the invention, however, are the grinder systems themselves, which are coated by plasma technology alone or in addition to a hard coating layer on the resistance element, so that, in addition to the general reduction in wear, substantial improvements in the area of the required torque grinder / runway can be achieved.

Vorteilhaft ist ferner, daß durch die erreichten Fortschritte im Bereich der Plasmatechnologie das Aufbringen von Hartcoating-Schichten im Bereich oder jedenfalls nahe Raumtemperatur (< 200 °C) durchgeführt werden kann, so daß eine merkliche Beeinflussung von Plastikmaterialien, die ebenfalls Verwendung finden können, beispielsweise auch das schon erwähnte Leitplastikmaterial für die Wider­stands- und Kollektorpiste, ausgeschlossen werden kann.It is also advantageous that the advances made in the field of plasma technology mean that hard coating layers can be applied in the region or at least close to room temperature (<200 ° C.), so that plastic materials, which can also be used, are noticeably influenced, for example also the already mentioned conductive plastic material for the resistance and collector slopes can be excluded.

Durch die in den Unteransprüchen aufgeführten Maßnah­men sind vorteilhafte Weiterbildungen und Verbesse­rungen der Erfindung möglich. Besonders vorteilhaft ist die Ausbildung der Hartcoating-Schichten in Form sogenannter Diamond-like-Carbon(DLC)- bzw. Graphite-like-Carbon(GLC)-Beschichtungen, die Metall­zusätze enthalten, so daß sich bestimmte Leitfähig­keiten ergeben, die bis zu 10⁻⁴ Ohm⁻¹ m⁻¹ betragen können. Es ist dann möglich, solche Schichten auch dicker aufzubringen, so daß sich besonders günstige Arbeitsbedingungen für den Dauerbetrieb ergeben.Advantageous further developments and improvements of the invention are possible through the measures listed in the subclaims. The formation of the hard coating layers in the form of so-called diamond-like-carbon (DLC) or graphite-like-carbon (GLC) coatings, which contain metal additives, is particularly advantageous, so that certain conductivities result, which can be up to 10⁻ ⁴ Ohm⁻¹ m⁻¹ can be. It is then possible to apply such layers thicker, so that there are particularly favorable working conditions for continuous operation.

Als Metallzusätze mit sehr guten Verschleiß- und Gleiteigenschaften können beispielsweise verwendet werden Wolfram (W), Tantal (Ta) und Niob (NB).As metal additives with very good wear and tear Sliding properties can be used, for example, tungsten (W), tantalum (Ta) and niobium (NB).

In diesem Zusammenhang ist noch darauf hinzuweisen, daß Metall enthaltende Kohlenwasserstoffverbindungen (metal-containing hydrogenated carbon films) in Form von Beschichtungen oder Filmen, die auf der Basis plasmatechnologischer Verfahren auf Träger aufgebracht werden, für sich gesehen schon bekannt sind, beispielsweise aus der Veröffentlichung: Appl. Phys. Lett. 50(16), 20. April 1987 als Aufsatz von H. Dimigen, H. Hübsch und R. Memming aus dem Philips GmbH Forschungslaboratorium Hamburg.In this connection it should also be pointed out that metal-containing hydrocarbon compounds (metal-containing hydrogenated carbon films) in the form of coatings or films which are applied to carriers on the basis of plasma-technological processes are already known per se, for example from the publication: Appl. Phys. Lett. 50 (16), April 20, 1987 as an essay by H. Dimigen, H. Hübsch and R. Memming from the Philips GmbH Research Laboratory Hamburg.

Zeichnungdrawing

Ausführungsbeispiele der Erfindung sind in der Zeichnung dargestellt und werden in der nachfolgenden Beschreibung näher erläutert. Die Zeichnung zeigt in Draufsicht in spezieller Anwendung auf ein Drehpoten­tiometer parallel nebeneinanderliegende Widerstands- und Kollektorpisten, die von einem gemeinsamen Schleifer überstrichen werden.Embodiments of the invention are shown in the drawing and are explained in more detail in the following description. The drawing shows a top view in a special application on a rotary potentiometer parallel resistance and collector slopes, which are swept by a common grinder.

Beschreibung der Ausführungsbeispiele
der Grundgedanke vorliegender Erfindung besteht darin, mindestens einen der Gleitpartner, die sich bei einem Stellwiderstand oder Potentiometer ergeben, also Schleifer und/oder die Leitplastikbasis mit einer nach plasmatechnologischen Gesichtspunkten hergestellten Hartcoating-Schicht zu versehen, so daß neben einer allgemeinen Reduzierung des abrasiven Verschleißes hauptsächlich der adhäsive Verschleiß beseitigt ist.Description of the embodiments
The basic idea of the present invention is to include at least one of the sliding partners that result from a variable resistor or potentiometer, that is to say wipers and / or the conductive plastic base to provide a hard coating layer produced according to plasma technology aspects, so that, in addition to a general reduction in abrasive wear, mainly adhesive wear is eliminated.

In Fig. 1, die zum allgemeinen Verständnis des Grundanwendungsgebiets vorliegender Erfindung angege­ben ist, ist eine Trägerplatte 10 vorgesehen, auf welcher sich eine Widerstandsbahn 12 und eine Kollektor­bahn 14 befinden.In Fig. 1, which is given for a general understanding of the basic field of application of the present invention, a carrier plate 10 is provided, on which a resistance track 12 and a collector track 14 are located.

Eine zentrale Achse 15 lagert, beispielsweise über einen Sprengring 16 befestigt, einen (metallischen) Abgriff 17, der seinerseits wieder einen aus mehreren einzelnen Schleiferfingern 18 und 19 bestehenden Schleifer so lagert, daß dieser mit seinen federnden Endbereichen auf der Widerstandsbahn 12 und der Kollektorbahn 14 aufliegt. Die Widerstandsbahn ist bei 20 unterbrochen, weist also Endbereiche auf, die der äußeren Spannungszuführung dienen.A central axis 15 supports, for example fastened via a snap ring 16, a (metallic) tap 17, which in turn supports a grinder consisting of several individual grinder fingers 18 and 19 in such a way that its resilient end regions on the resistance track 12 and the collector track 14 lies on. The resistance track is interrupted at 20, that is to say has end regions which serve for the external supply of voltage.

Widerstandsbahn oder -piste und Kollektorbahn oder -piste bestehen üblicherweise aus einem speziellen Leitplastikmaterial, auf welchen die Schleiferfinger gleiten, die üblicherweise aus einer Legierung bestimmter edler Metalle wie Palladium Gold, Platin u.dgl. bestehen können, aber infolge dieser Beschichtung nunmehr auch aus kostengünstigeren Materialien, wie Kupfer-­Beryllium oder Edelstahl,bestehen können.Resistance track or track and collector track or track usually consist of a special conductive plastic material on which the wiper fingers slide, which are usually made of an alloy of certain noble metals such as palladium gold, platinum and the like. can exist, but as a result of this coating can now also consist of less expensive materials, such as copper beryllium or stainless steel.

Die Unterseite der Schleiferfinger im vorderen Ansatz, also dort, wo diese Schleiferfinger mit ihren Auflageflächen auf den Leitplastikschichten von Widerstands- und Kollektorpiste gleiten, wird entsprechend vorliegender Erfindung mit den Hartcoating-­Schichten versehen, die auf plasmatechnologischer Grundlage aufgebracht werden, so daß sich als Schichten sogenannte Metall-Carbon-Wasserstoffe oder Graphit-­Carbon-Wasserstoffe, aber auch isolierende Polyamid­schichten ergeben. Durch Metallzusätze zu den Metall-­Carbon-Wasserstoff-bzw. den Graphit-Carbon-Wasserstoff­schichten gewinnt man die elektrische Leitfähigkeit, die erforderlich ist, während man bei isolierenden Polyamidschichten in Form von Hartcoatings bevorzugt mit sehr dünnen Schichtdicken arbeitet, die beispiels­weise im Bereich von 10 Nanometer liegen. Durch diese geringe Schichtdicke gelingt es, die Polyamid-­Isolationsschicht elektrisch unsichtbar zu machen, wobei die Leitfähigkeit beispielsweise von Tunnel­elektroden übernommen werden kann.The underside of the grinder fingers in the front attachment, i.e. where these grinder fingers with their contact surfaces on the conductive plastic layers slide from resistance and collector slopes, is provided according to the present invention with the hard coating layers, which are applied on a plasma-technological basis, so that layers result in so-called metal-carbon hydrogens or graphite-carbon hydrogens, but also insulating polyamide layers. Through metal additives to the metal-carbon-hydrogen or. The graphite-carbon hydrogen layers gain the electrical conductivity that is required, while insulating polyamide layers in the form of hard coatings preferably work with very thin layer thicknesses, for example in the range of 10 nanometers. This small layer thickness makes it possible to make the polyamide insulation layer electrically invisible, the conductivity being able to be taken over, for example, by tunnel electrodes.

Die andere und hier bevorzugte Art einer Hartcoating-­Schichtausbildung umfaßt die schon genannten Metall-­bzw. Graphit-Kohlenwasserstoffe.The other and preferred type of hard coating layer formation comprises the metal or. Graphite hydrocarbons.

Die Plasmatechnologie ermöglicht die Herstellung solcher Schichten, indem physikalisch aus einer Plasmawolke heraus homogene Schichtablagerungen vorgenommen werden. Hierzu gehört hauptsächlich die sogenannte Hochvakuum-Sputtering-Technik, durch welche extrem dichte und glatte, sehr dünne Schichten im Bereich zwischen 10 Nanometer bis etwa 2000 Nano­meter aufgebracht werden können, bestehend aus verschiedenen Arten von Materialien, wie beispielsweise Metallverbindungen, Oxyde, Nitride oder Carbide.Plasma technology enables the production of such layers by physically making homogeneous layer deposits from a plasma cloud. This mainly includes the so-called high-vacuum sputtering technique, which can be used to apply extremely dense and smooth, very thin layers in the range between 10 nanometers to about 2000 nanometers, consisting of different types of materials, such as metal compounds, oxides, nitrides or carbides .

Da wie erwähnt die Temperaturen bei diesen Vorgängen niedrig liegen, können auch Kunststoffe auf diese Weise metallisiert werden.As the temperatures in these processes are low, as mentioned, plastics can also be metallized in this way.

Die Grundform einer plasmatechnologischen Schichtauf­bringung läuft so ab, daß von einem hochionisierten Dampf ausgegangen wird (Plasma). Man kann dies realisieren durch Anlegen einer Vorspannung oder durch Zuführen eines Strahls beschleunigter Partikel, wobei im ersten Fall eine durch die Vorspannung verursachte Zerlegung von Kohlenwasserstoffen in die Plasmaform oder im zweiten Fall eine Ionenstrahl­zerlegung erfolgt. Durch ein solches Vorgehen lassen sich dünne Filme mit den gewünschten Eigenschaften ablagern. Da solche plasmatechnologischen Vorgänge für sich gesehen bekannt sind, wird im folgenden hierauf nicht genauer eingegangen; es wird beispiels­weise verwiesen auf die genannte Veröffentlichung. Die bekannten Zerlegungsverfahren zur Gewinnung von Kohlenwasserstoffen können unterteilt werden in die Zerlegung von Kohlenwasserstoffgasen und solche, bei denen fester Kohlenstoff als Kohlenstoff­quelle selbst verwendet wird. Im ersten Fall kann beispielsweise Methan, Äthan o. dgl. durch Glimment­ladung zerlegt und Kohlenstoffionen gebildet werden. Diese Ionen werden dann in Richtung auf ein elektrisch vorgespanntes Substrat beschleunigt.The basic form of a plasma-technological layer application takes place in such a way that a highly ionized vapor is assumed (plasma). This can be achieved by applying a bias or by supplying a beam of accelerated particles, in the first case a decomposition of hydrocarbons into the plasma form caused by the bias or in the second case an ion beam decomposition. By doing so, thin films with the desired properties can be deposited. Since such plasma technology processes are known per se, they are not dealt with in more detail below; for example, reference is made to the publication mentioned. The known separation processes for the extraction of hydrocarbons can be divided into the separation of hydrocarbon gases and those in which solid carbon is used as the carbon source itself. In the first case, methane, ethane or the like can be broken down by glow discharge and carbon ions can be formed. These ions are then accelerated towards an electrically biased substrate.

Bei der Verwendung von festem Kohlenwasserstoff kann eine Laser- oder Lichtbogenverdampfung von Kohlenwasserstoffen in Frage kommen. Es ist auch möglich, kombiniert zu arbeiten, also sowohl festen Kohlenstoff als auch ein Kohlenstoffwasserstoffgas oder Wasserstoff als Quelle für Strahlpartikel zu verwenden.Laser or arc vaporization of hydrocarbons may be considered when using solid hydrocarbon. It is also possible to work in combination, i.e. both fixed Use carbon as well as a hydrogen carbon gas or hydrogen as a source of jet particles.

Zu den plasmatechnologischen Hauptherstellungsverfah­ren zählt daher die physikalische Dampfablagerung, die Ionenimplantation, gegebenenfalls thermische Spray­vorgänge, also überall dort, wo sich auf plasmatechno­logischer Grundlage eine Oberflächenmodifikation von Materialien im Sinne der Bildung von speziellen Hart­coating-Schichten ergibt. Diese Schichten sind dann zur Realisierung vorliegender Erfindung so zu bestim­men bzw. auszuwählen, daß adhäsive Verschleißmöglich­keiten ausgeschlossen sind. Dies erreicht man bei­spielsweise speziell durch Aufbringen von diamant­ähnlichen und graphitähnlichen Kohlenwasserstoff­schichten (DLC; GLC) - dort ergänzt durch Metallzu­sätze, wo dies aufgrund der erforderlichen Leitfähig­keiten sinnvoll ist. Es ergeben sich dann Metall-­Carbon-Wasserstoffe und Graphit-Carbon-Wasserstoffe, die hauptsächlich als Beschichtungen für Schleiferflä­chen bei Potentiometern u. dgl. Systemen in Frage kommen.The main plasma technology manufacturing processes therefore include physical vapor deposition, ion implantation, and possibly thermal spray processes, i.e. wherever surface modification of materials results in the formation of special hard-coating layers on the basis of plasma technology. In order to implement the present invention, these layers are then to be determined or selected such that adhesive wear possibilities are excluded. This can be achieved, for example, by applying diamond-like and graphite-like hydrocarbon layers (DLC; GLC) - supplemented by metal additives where this makes sense due to the required conductivity. There are then metal-carbon hydrogens and graphite-carbon hydrogens, which are mainly used as coatings for grinding surfaces in potentiometers and the like. Like systems come into question.

Alle in der Beschreibung, den nachfolgenden Ansprüchen und der Zeichnung dargestellten Merkmale können sowohl einzeln als auch in beliebiger Kombination miteinander erfindungswesentlich sein.All features shown in the description, the following claims and the drawing can be essential to the invention both individually and in any combination with one another.

Claims (10)

1. Potentiometer, insbesondere durchdrehbares Präzi­sionspotentiometer oder linearer Weggeber, mit Widerstands- und gegebenenfalls Kollektorbahn und auf diesen gleitendem (mehrfingerigem) Schleifer, dadurch gekennzeichnet, daß auf mindestens einer der einander zugewandten und aufeinander gleitenden Flächen von Widerstands- bzw. Kollektorbahn einer­seits und/oder des Schleifers bzw. der Schleifer­finger andererseits eine durch einen plasmatech­nologischen Vorgang gewonnene (dünne) Hartbeschich­ting (Hartcoating) aufgebracht ist.1. Potentiometer, in particular rotatable precision potentiometer or linear displacement sensor, with a resistance and possibly collector path and on this sliding (multi-finger) grinder, characterized in that on at least one of the mutually facing and sliding surfaces of the resistance or collector path on the one hand and / or of the grinder or the grinder finger, on the other hand, a (thin) hard coating (hard coating) obtained by a plasma-technological process is applied. 2. Potentiometer nach Anspruch 1, dadurch gekennzeich­net, daß lediglich die auf Widerstandsbahn und/­oder Kollektorbahn (12, 14) gleitende Schleifer­fingerunterseite mit der Hartcoating-Schicht verse­hen ist.2. Potentiometer according to claim 1, characterized in that only the sliding finger on the resistance track and / or collector track (12, 14) is provided with the hard coating layer. 3. Potentiometer nach Anspruch 1 oder 2, dadurch ge­kennzeichnet, daß die Hartcoating-Schicht aus einer diamantähnlichen Kohlenstoffschicht (DLC = Diamond-­like-Carbon Coating) besteht.3. Potentiometer according to claim 1 or 2, characterized in that the hard coating layer consists of a diamond-like carbon layer (DLC = Diamond-like-Carbon Coating). 4. Potentiometer nach Anspruch 1 oder 2, dadurch ge­kennzeichnet, daß die Hartcoating-Schicht aus einer graphitähnlichen Kohlenstoffschicht (GLC = Graphit-­like-Carbon Coating) besteht.4. Potentiometer according to claim 1 or 2, characterized in that the hard coating layer consists of a graphite-like carbon layer (GLC = graphite-like-carbon coating). 5. Potentiometer nach Anspruch 1 oder 2, dadurch ge­kennzeichnet, daß die Hartcoating-Schicht eine Silizium-Carbid-Schicht ist.5. Potentiometer according to claim 1 or 2, characterized in that the hard coating layer is a silicon carbide layer. 6. Potentiometer nach Anspruch 3, 4 oder 5, dadurch gekennzeichnet, daß zur Erhöhung der Leitfähigkeit die in den Ansprüchen 3, 4 und 5 angegebenen Hart­coating-Schichten Metallzusätze aufweisen und ins­gesamt eine Schichtdicke zwischen 10 - 2000 nm haben.6. Potentiometer according to claim 3, 4 or 5, characterized in that to increase the conductivity, the hard coating layers specified in claims 3, 4 and 5 have metal additives and have a total layer thickness between 10 - 2000 nm. 7. Potentiometer nach Anspruch 6, dadurch gekenn­zeichnet, daß die Metallzusätze Wolfram (W), Tan­tal (Ta) und Niob (NB) sind.7. Potentiometer according to claim 6, characterized in that the metal additives are tungsten (W), tantalum (Ta) and niobium (NB). 8. Potentiometer nach Anspruch 1 oder 2, dadurch gekenn­zeichnet, daß die Hartcoating-Schicht eine isolie­rende, elektrisch unsichtbare Polyamid-Schicht ist mit Leitfähigkeit über Tunnelelektroden und einer Schichtdicke im Bereich von 10 nm.8. Potentiometer according to claim 1 or 2, characterized in that the hard coating layer is an insulating, electrically invisible polyamide layer with conductivity via tunnel electrodes and a layer thickness in the range of 10 nm. 9. Potentiometer nach einem der Ansprüche 1 bis 8, da­durch gekennzeichnet, daß als die Beschichtung tragendes Material (Schleifergrundmaterial) Edelmetalle (Palladium, Gold, Platin, Iridium) oder deren Legierung vorgesehen sind.9. Potentiometer according to one of claims 1 to 8, characterized in that noble metals (palladium, gold, platinum, iridium) or their alloy are provided as the coating-bearing material (wiper base material). 10. Potentiometer nach einem der Ansprüche 1 bis 8, da­durch gekennzeichnet, daß als die Beschichtung tragendes Trägermaterial (Schleifergrundmaterial) kostengünstigere Metalle, wie Kupfer-Beryllium oder Edelstahl, vorgesehen sind.10. Potentiometer according to one of claims 1 to 8, characterized in that less expensive metals, such as copper beryllium or stainless steel, are provided as the carrier material carrying the coating (grinder base material).
EP90106098A 1989-04-06 1990-03-30 Variable resistance Withdrawn EP0391267A1 (en)

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US11225885B2 (en) * 2017-08-01 2022-01-18 Eaton Intelligent Power Limited Rocker arm motion detection for diagnostic feedback and control

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