POTENTIOMETER CONTROLLABLE BY A REDUCED MECHANICAL CONSTRAINT

Abstract

The potentiometer includes a resistive track 1 elongated in one direction, a collector 4 elongated in the same direction, disposed opposite the track and made of a strip 8 of electrically conductive fabric, a movable member in the direction of elongation of the track and the collector to bring the collector and the track into electrical contact in a reduced area 8d, and means 11a for keeping a first longitudinal edge 12a of the collector away from the first corresponding longitudinal edge 13a of the track, while the second longitudinal edge 12b of the collector is free to move relative to the second longitudinal edge 13b of the track and come into contact with it under the control of the movable member.

Description

i "Potentiometer controllable by a reduced mechanical constraint" The invention relates to potentiometers, that is- that is to say, devices comprising: - static components, consisting of a resistive track, a conductive collector and connections, namely generally two initial connections linked to the ends of the resistive track and a third connection linked to the conductive collector; and a moving component, generally consisting of a cursor, which controls the electrical contact of the collar reader with a reduced area of ​​the resistive track, an area which corresponds to the position of the moving part. Following a conventional circuit, the first two connections are subjected to a determined potential difference, fixed or variable, while on the third connection a voltage is available which is a fraction of this potential difference, a fraction which depends on the position of said reduced area on the resistive track and therefore depends on the position of the moving part. Therefore, a potentiometer can serve, for example, as a control device, an adjustment device, or a sensor. position or displacement sensor. The reliability and lifespan of a potentiometer classic sliding friction mechanisms are limited by the friction - 30% of the cursor and the wear that this friction causes. Furthermore, it is difficult to achieve a potential- waterproof timeter of this type, due to the need for allow cursor movement and control of this de- placement, unless the Hall effect or other factors are implemented opto-electronic means, which present other incons- Venients. These two drawbacks of classic potentiometers problems can be addressed by implementing the de- French patent application published no. 2,578,321 of the applicant- deresse describing, in particular, a potentiometer- sensor a circuit in which the resistive track is protected by a membrane carrying the collector track, and in which the two tracks are pressed against each other by an element that can be either a human finger, a solid slider, or a fluid jet. Such a structure, which defines a "Membrane potentiometer", requires, in order to put into operation electrical contact between the two tracks, the implementation of a certain mechanical constraint, exceeding the value of 0.1 N and most often several N. It should also be noted that the potentiometers of the previous techniques exhibit a certain amount of electrical "noise" that, which results from variations in contact resistance between the conductor collector and the resistive track in the contact area, and a lack of regularity in the output voltage through the third connection, which is the voltage of useful output of the potentiometer. The invention according to the main patent aims to pala- linking these disadvantages of potentiometers from previous techniques (of the classic type or of the membrane type depending on patent application no. 2,578,321) by allowing to realize- A potentiometer that is controllable by reduced mechanical stress, exhibits low electrical noise, determines a regular output voltage, is reliable, has a long lifespan thanks to very low component wear, and can be made waterproof, or at least easily protected against external aggressions, such as dust. These objects are accessed using the potentiometer according to the main patent, which includes a resistive track. with an electrical connection at each end, a collar- driver with a third connection and a slider, characterized in that the collector is made by a strip of electrically conductive fabric. In the potentiometer of the main patent, this fabric can be made either of conductive fibers, or of fi- non-conductive fibers made conductive by a treatment appropriate surface area, over all or part of their surface. Advantageously the fabric can be made of - a fabric of polyester fibers covered by a thin film of nickel; - a fabric of stainless steel fibers; - a fabric of copper fibers; - a conductive carbon fiber fabric. The purpose of this addition is to improve- modifications and variants to the potentiometer controllable by a reduced mechanical constraint according to the main patent, that is to say to a potentiometer in which the collector consists of a strip of electrically conductive fabric tricity in accordance with claim 1 of the principal patent cipal. The present invention consists of creating a potential- a timer controllable by a reduced mechanical constraint, comprising: a resistive track elongated in one direction, with an electrical connection at each end; - a collector elongated in the same direction, disposed opposite said conductive track and made of a strip of electrically conductive fabric, with a third connection; and - a movable member, in the direction of the lengthening of the resistive track and the collector con- conductor and capable of controlling the electrical contact of the collector and the track in a reduced area whose position in said direction is a function of the position of the moving part; and characterized in that it includes means for maintaining The first longitudinal edge of the conductive collector is positioned away from the corresponding first longitudinal edge of the resistive track, while the second longitudinal edge of the conductive collector is free to move relative to the second longitudinal edge of the resistive track and come into contact with it under the control of the moving member. The invention can be better understood with the aid of the Further description follows, along with drawings attached hereto, which supplement and drawings are, well understood, given mainly as an indication. Figure 1 is a perspective view of a potentiometer according to a first embodiment of the invention. Figure 2 is a section II-II of Figure 1. Figure 3 is a perspective view of a po- tentiometer according to a second embodiment of the in- convention. Figure 4 is a section IV-IV of Figure 3. Finally, Figure 5 is a cross-section, similar to that of Figure 4, illustrating a third embodiment. of a potentiometer according to the invention. According to the invention, and more specifically according to one of its modes of application, as well as according to those of the modes of the realization of its various parts, to which it seems. If preference should be given, proposing, for example, to create a potentiometer controllable by a reduced mechanical constraint, the procedure is as follows: or in a similar manner. Referring to figures 1 and 2, on the one hand, and In figures 3 and 4, on the other hand, we see that a potential- meter according to the first or second embodiment of the invention comprises firstly, in the known manner and according to the main patent: a resistive track 1 with two electrical connections 2,3 electrically linked res- specifically at the ends 2a and 3a of track 1; a col- driver reader 4 with a third connection 5 connected electrically to this conductive collector; and a slider 6. As in the main patent, the conductive collector 4 is constituted, in the embodiments figures 1-2 and 3-4, by a strip of fabric 8 conduct- electricity generator. In particular, as can be seen in Figures 2 and 4, the fabric 8 constituting the conductive collector 4 is made up of interwoven conductive fibers 8a and 8b. One of the advantages of fabrics over solid films, for constituting the conductive collector, is their much greater flexibility, which can be even better exploited if they are used along their bias; in addition, fabrics work, in response to pressure applied by the slider, in bending and not in tension, as is the case for a solid film, hence a greater elastic and reversible deformation requiring a reduced mechanical stress on the slider. In the first embodiment of Figures 1 and 2, in order to control the electrical contact, in a reduced area, between the fabric strip 8 constituting the conductor collector 4 and resistive track 1, under the ef- Given a pressing force F1 (that of the slider 6), weaker than the pressing force applied by the slider in the main patent, the potentiometer of the present invention is made to include means, consisting of a fixed wedge 11, for maintaining a first longitudinal edge 12a of the conductive collector 4, i.e., of the fabric strip 8, separated, in a fixed position, from the corresponding first longitudinal edge 13a of the resistive track 1, while the second longitudinal edge 12b of collector 4 can move cer in relation to the second longitudinal edge 13b of track 1. Wedge 11 is formed, in the realization method- The application illustrated in Figures 1 and 2, by a self-adhesive strip on both sides, having for example a thickness between approximately 0.01 mm and approximately 5 mm. This wedge 11 and the resistive track i are supported by a support 10 made of an electrically insulating material cited. As the cursor 6 passes over it, and under the pressure exerted by it, the fibers 8a, 8b of the fabric 8 straighten at at the level of their multiple elbows and they lie down in labor- lant & flexion and not tension. Furthermore, each convex bend of the zig-zag of each Fiber 8a,8b is likely to constitute an electrical contact tric with resistive track 1, hence a multiplicity of effective contacts with this lead, which is believed to be based on the name- fiber mesh size per centimeter. Therefore, there is an interest to have a mesh as small as possible. The big name- number of contact points between a conductive fiber 8a,8b and resistive track 1 ensures low electrical resistance contact resistance. This resistance can still be reduced. coated and stabilized by a noble metal coating (gold, silver, platinum, palladium or an alloy of two or several of these metals) on fabric 8, an inter- layer a nickel intermediary may be placed between the fabric and the noble metal coating. The edge 12b of the fabric 8 may also be coated with an electrically conductive polymer composition (silver- or carbon-filled polymer). The fabric 8 is made either of conductive fibers or of non-conductive fibers made conductive by appropriate treatment, over all or part of their surface. Advantageously, fabric 8 can be made up of - a “tergal” fabric made of coated polyester fibers green by a thin film of nickel, of the commercial type specialized under the name "Metalen" and manufactured by the "Zurich Gauze Factory in Bluter", Ruschlikon (Switzerland); - a stainless steel fiber fabric of the type marketed under the name "Bopp-SD" by the company "Bachmannweg Metal Fabric Factory" of Zurich (Switzerland); - a copper or mild steel fiber fabric; - a conductive carbon fiber fabric. Note that it is possible to waterproof the fabric 8, which constitutes the conductive collector 4, in bou- partially singing the stitches without covering the con- vexed 8c of the bends directed towards the resistive track 1 (which must remain conductive), by application of a coating or a plastic film, referenced 7 on the figure 2, capable of maintaining the fabric's flexibility; by par- In particular, waterproofing can be achieved using a photoresist emulsion or film, depending on the techniques well known in screen printing art. Because the edge 12b of the conductive collector 4 remains free, the force F1 concentrated there under the effect of the slider 6, even if very small, causes contact electric in 8d, frank, stable and exhibiting a conduc- sufficient electrical activity. A second embodiment of the invention is illustrated in figures 3 and 4, on which we have used- use the same references as in figures 1 and 2 for designate the corresponding elements. In this embodiment, one takes advantage not only the flexibility of the fabric 8 constituting the collection conductor 4, following the direction of elongation of the resistive track 1 and the conductive collector 4, but equally element of a balancing scourge effect. In the embodiment shown in Figures 3 and 4, the substrate 10, with the resistive track 1, carries a piece of support 14 via a spacer 15, in for- This creates a U-shaped channel, referenced 16, of height h. Within this channel 16 is arranged an elastic element or spring 17, consisting, in the illustrated embodiment, of a part having the shape of a rectangular parallelepiped. foam made of a synthetic material fixed to the sup- piece port 14, the edge 12a of the conductor manifold 4 being solid- area of ​​the lower surface 17i (in figure 4) of the spring 17, in particular of the foam piece, opposite the upper surface 17s (in figure 4) integral with the support piece 14, while a wedge lla, which can tilt The first, on its edge 11c, is arranged between the edge 12a of the conductive collector 4 and the resistive track 1, being attached to collector 4. As illustrated in Figure 4, at least the greater part of face lld of wedge 11 is located to the right (in the figure) of the center of gravity 4f of collector 4. In other words, part of the hold is available see between the barycenter 4f and the resistive track 1. More specifically, arrangements are made so that the ba- The center of gravity 4f of the section (in the plane of figure 4) of the conducting collector 4 is located in the vicinity of the face lld of hold 11. Due to this structure, the wedge lla is, as illustrated in Figure 4, pressed, in the absence of the pressing force F1 of the slider 6, against the resistive track 1 or its substrate 10 by the spring 17, thus maintaining the conductor collector 4 is removed from this track. Under the action of the force F1 applied by the cur- seur 6 on the conductor manifold 4, the wedge pivots around its edge 11c, partially compressing the spring 17 by the edge 12b of the manifold 4 which comes into contact in 8d with resistive track 1. The distance d (in the direction perpendicular to the direction of the lateral edge lld of the wedge 11 which contains the edge 11c) between the centroid 4f and the edge 11c is chosen to be significantly less than the distance p between the area of ​​application of the force F1 and the edge llc (considered in the same direction as the distance d) so that a acceleration, shock, displacement or weight- effect The potentiometer should not cause an unintended contact between the collector conductor 4 and the resistive track i in the absence of force F1, while not preventing not this contact under the effect of even a weak force F1. The mechanical links between the different elements The components ensure that the rotating part is immobilized in translation around the edge llc of the potentiometer relative to the fixed support 10 with its resistive track 1, thus preventing, among other things, mechanical contact and therefore blocking. elements lia, 12a and 17 against the spacer 15. The potentiometer according to the embodiment shown in Figures 3 and 4 has numerous parameters that can be adjusted according to the application, namely - the aforementioned distances d and p, as well as the dis- tance e between the centroid 4f and the point 4g of application of the force of spring 17 (in the same direction as the determination of distances d and p), - the force of spring 17, - the thickness of the wedge lia, - the stiffness or flexibility of the fabric 8 forming the conducting collector 4, the weft and warp yarns being able to have different stiffnesses, which allows choosing a certain flexibility in the elongation axis of the conducting collector 4 and a certain stiffness in the perpendicular direction. These parameters are adjusted in particular according to... tion of the characteristics of the force F1 applied in the embodiment illustrated by a mo- control element solid slider type 6; however, this combining element mobile control could be made up of either an element solid other than a slider; either by a fluid jet (jet li- guide or gas jet), or by an immaterial resulting means so many phenomena acting at a distance, such as a field at localized action. Because the potentiometer, according to the two embodiments shown in Figures 1 and 2, on the one hand, and 3 and 4, on the other, on the other hand, is thus actionable by a resulting force F1- In particular, for a field with localized action, it can be implemented as a completely sealed assembly due to the absence of a dynamic seal; it can be controlled by a very weak force F1 and it can be released re of any physical contact with the control unit created- field tester with localized action. A variant of the method of realizing figures 3 and 4 is illustrated in figure 5 which is an ana- section log to figure 4 and in which we find all the elements of figure 4, except for the replacement of the pressure force F1, resulting from the pressure of the slider 6, by a traction force F2 obtained by means of a movable magnet 6a. In addition, the entire substrate 10, the spacer 15 and the support 14a constitutes a housing- closed, thus ensuring the potentiometer's seal, the gold- mobile gane, namely magnet 6a, and the means which com- command its movement being external to the said shoemaker. In order to benefit from the magnetic field produced by the magnet 6a, the conductive collector 4 is made by means of a fabric consisting of threads 8a and / or 8b of a magnetic material, the conductive collector having, opposite resistive track 1, a surface suitable for as- to ensure a conductive and stable electrical contact with it. In the potentiometer shown in Figure 5, the permanent magnet 6a can be replaced by a solenoid through which the magnet passes. by an electric current and constituting an electromagnet. In another variant of the potentiometer according to figure 5, instead of making the wires 8a and / or 8b from a magnetic material, wires 8a and 8b can be made of an electrically conductive, non-magnetic material. as in the case of figures 1-2 and 3-4, and provide for at- above (in the direction of Figure 5) the non-magnetic fabric 8 a pressure element made of a magnetic material, this element, which is the only one subjected to the magnetic field produced by the magnet 6a or the electromagnet provided in its place, being for example a strip, a fabric, a wire longitudinal or a ball; in particular a magnetic ball tic moving on the fabric 8 to follow the displacements cements of the magnet 6a or the electromagnet, has the advantage of localizing the effects of the magnetic field on a very small surface area and consequently to improve the resolution potentiometer resolution. As an example, we can make the 8a wires and / or 8b or the pressing element in one or more of the ma- The following "soft" magnetic materials: pure iron, mild steel, iron-silicon alloy, iron-nickel alloy, iron- cobalt, nickel, magnetic grades of stainless steels and to constitute the magnet 6a one or more of the magnetic materials the following "hard" materials: ferrite, iron-nickel alloy aluminium-cobalt, iron-neodyne-boron alloy, cobalt- rare earths, especially those with high induction remanent, a high coercive field and magnetic energy intense tick. Finally, we will give an example of a potential- tiometer according to figure 5: height h of channel 16: 4.6 mm thickness of shim lia: 0.4 mm width of shim l1a: 6 mm collector 4: fabric 8 in annealed mild steel fibers 8a, 8b, nickel-plated and gold-plated, 80 mesh (32 meshes / cm, weft pitch 318 µm, wire diameter 140 µm, thickness 0.3 mm); total width 11 mm, free edge width 12b 5 mm; spring 17: synthetic organic foam elas- 6 mm thick tic before com- pressure and width 4 mm; parameters of the beam: e = 2 mm, p = 2.5 mm, d = 0.5 mm; magnetic field produced by the permanent magnet 6a in neodymium-iron-boron alloy of the type Neomax-27H of the Japanese company Sumitomo, remanence 1.06 tesla, in the shape of a rectangular parallelepiped with face 17a of 5 x 15 mm and of thickness 3 mm; field perpendicular to face 17a: coer- field active energy of 811 kA / m, magnetic energy tick 215 kJ / m3; distance between face 6b of magnet 6a and the neck- reader 4: 0.95 mm before attraction and 0.55 mm during attraction; resistive track 1 in a conductive plastic material 544 ohm / Ω resistor, 10 mm wide and 455 mm usable electrical length; output signal linearity: 1%; dynamic contact resistance: 150 ohms; noise resistance: 100 ohms; backlash: 1% As one might expect, invention is not limited by anything- ment to the methods of application and implementation that have been more specifically considered; on the contrary, it embraces them re, all the variants.

Claims

DEMANDS 1. Potentiometer controllable by a me- constraint reduced mechanical, including: - a resistive track (1) elongated in a direction- tion, with an electrical connection (2, 3) at each end; - a collector (4) elongated in the same direction, disposed opposite said conductive track and consisting of a strip (8) of electrically conductive fabric, with a third connection (5); and - a movable part (6, 6a), which can be moved in the di- direction of the lengthening of the resistive track and the col- driver reader capable of controlling the ignition electrical collector and track in a re- zone conduit (8d) whose position in said direction is a function of the position of the moving part; and characterized in that it comprises means (11, 11a) to maintain a first longitudinal edge (12a) of the neck the conductive reader is offset from the first corresponding longitudinal edge (13a) of the resistive track, while the second longitudinal edge (12b) of the conductive collector is free to move relative to the second longitudinal edge nal (13b) of the resistive track and come into contact with this one under the control of the moving part.

2. Potentiometer according to claim 1, character- terized in that said means for maintaining the first longitudinal edge (12a) of the conducting collector (4) away from the corresponding first longitudinal edge (13a) of the resistive track (1) are made up of a longitudinal wedge- fixed nale (11) disposed between these two edges.

3. Potentiometer according to claim 1, character- terized in that said means for maintaining the first longitudinal edge (12a) of the conducting collector (4) away from the corresponding first longitudinal edge (13a) of the resistive track (1) are constituted by a wedge (11a) which can pivot about one of its edges (11c), which presses on the resistive track in the vicinity of the center of gravity (4f) of the conductor collector, against the action of an anti- spring goniste (17), the distance (d) between this edge and the ba- the center (4f) of the collector, considered in the direction perpendicular to that of the lateral face (11d) of the movable wedge (11a) which includes said edge (llc), being clearly less than the distance (p) between this edge and the application area of ​​the movable member, considered in the same direction as the distance between the edge and the bary- center, part of the wedge (11a) being arranged between the center of gravity (4f) and the resistive track (1).

4. Potentiometer according to any one of the following specifications indications 1 to 3, characterized in that the moving part is consisting of a cursor (6).

5. Potentiometer according to any one of the following specifications indications 1 to 3, characterized in that the moving part is a magnet (6a) or an electromagnet, the fabric (8) conti- killing the conductive collector being carried out at least in part made of a magnetic material.

6. Potentiometer according to any one of the following specifications: indications 1 to 3, characterized in that the moving part is a magnet (6a) or an electromagnet and in that an element of a magnetic material is associated with the non-magnetic tissue (8) forming the conducting collector (4).

7. Potentiometer according to claim 5 or 6, characterized in that the entire potentiometer, at the ex- The magnet (6a) or electromagnet and its means of movement are arranged inside a waterproof boot (10, 15, 14a).