DE4447294A1 - Method and device for determining a respective local position of a body - Google Patents

Description

State of the art

The invention relates to a method according to the preamble of claim 1 and a device according to the preamble of claim 2 and relates generally to possible abilities to record the position, the path or the angle of moving bodies.

In most cases, tension is used for this purpose divider circuits based on the well-known potentiometer principle used as displacement transducers, variable resistors or Potentiometers are designed and in which on a Voltage divider, which is also sprayed on or evaporated precipitate is formed on a substrate can be a grinder that slides in contact contact thereby being able to, depending on his Position different DC potentials of the Tap resistance path and usually over a  collector grinder directly connected to it on a To transfer collector path, from which the tapped Potential is then available for evaluation. Such Potentiometers used in certain embodiments extraordinarily high precision as path or measured value can be used under certain Conditions due to the constant contact that ultimately also wear and tear on fast grinders movements, problems that have a touch Loose detection of the sensors at the measured values is desirable do.

So it is also known that inductors are also used as displacement sensors in the form of, for example, differential coils, differences tial transformers or inductors with short circuit use winding in the form of a tube, but what in in many cases a certain measurement inaccuracy or under May also result in non-linearities.

On the other hand, the voltage tap is non-contact a capacitive position sensor or displacement sensor made, as for example from DE 28 26 398 C2 is known, then result from stray capacities and leakage resistances, the total as disturbance variables significant falsifications of the Measured value, which are mostly unacceptable. So there is the capacitive displacement sensor of DE 28 26 398 C2 from one Pair of diagonally divided, isolated from each other Capacitor plates connected to an AC voltage source with a serving as a tap between the Adjust capacitor plates by the path to be tapped removable intermediate plate. The intermediate plate is over  Connection cable with the input of an evaluation circuit connected, being due to the movements of the tap the connecting cable and its connection points constantly changing forces are exercised, not only cause accelerated aging of the displacement sensor, but by the position and path changes of the cable at the same time to capacity changes and changing Forming stray capacities that are undefined and above all, the disturbance variable that cannot be compensated for mean.

Another encoder (DE 34 41 217 A1) a tightly packed, meandering or zigzag shape resistance track on a Substrate surface, being at a distance from this Resistor conductor track a movable tap element is located, which is formed like a circular ring and capacitively decouples the respective potential and via a connecting line one from a Voltme supplies existing measuring circuit. Because the track is on a DC supply voltage, one can capacitive measured value acquisition only in the course of a ver detect shift so that a stationary position of the Tap due to a missing measured value is valuable. In addition, the same result Way from stray capacities and leakage resistances existing disturbance variables that cannot be eliminated.

Finally, it is known (US 3,636,449) the position to determine a movable galvanometer pointer men that an AC voltage grounded on one side is connected to the pointer via an intermediate capacitor  its potential capacitive to a resistance track couples, so that at one end of the resistance track one determined by the respective tap position Acquire accordingly damped AC signal and rectifies. From this, the tap posi tion, where the tap is the pointer of a Galvanometer is the at a predetermined distance over the Resistance track slides.

The invention has for its object a touch to create a position sensor without any problems, which in Ver use of uncritical and inexpensive components only one has very low sensitivity to disturbance variables or so is designed that by appropriate evaluation circuit against the influence of the disturbance variable, for example the influence of Stray capacities and leakage resistances, practically too Can be made zero.

Advantages of the invention

The invention solves this problem with the features of Claim 1 or claim 2 and has the advantage that extremely frequent activities over long periods of time me, other mechanical influences such as vibrations u. the like does not affect the flawless accuracy and precision can flow, on the other hand it succeeds in the given the basic principle of capacitive sensing if disturbances occur, based on stray capacities or other leakage resistances, can easily be switched off or by the basic concept of the position sensor on which the invention is based Not to appear from the start.  

It is also of particular advantage that due to the Acquisition of the respective relative position of a Potential measuring probe with reference to a voltage distribution element - this will be discussed further below gen -, an average of the voltage amplitude distribution at the respective measuring point, which is derived from a sum of individual potentials. On such, by the respective potential probe position certain mean value reacts to the smallest shift and depends linearly on the relative position of the potentiometers alsonde, so that on the one hand the advantages of a kapazi tive scanning, namely in particular freedom of contact and freedom from mechanical wear and tear, to be maintained, on the other hand that with a capacitance ven sampling occurring, sometimes considerable falsification scattering quantities causing the measurement output voltage is met safely, and because of the reason principle of measurement is not based on a change in capacity there is - the capacity between the potential probe on the one hand and the voltage divider element, of which the potential probe taps the measuring voltage remains each potential probe position essentially the same.

It is under one at this point and also in repeatedly used as voltage ver Partition designated component a stationary, in To understand the measuring direction extending counter element, which is designed so that it is in the measuring direction, ie seen in the direction of displacement of the potential measuring probe this one at each different position different amplitude distribution pattern for sampling  offers, with certain embodiments of a voltage distribution element, the respective measuring point potential only through a functional connection with the surface structure of the potential measuring probe itself results, namely when the voltage ver divider element specifically around two adjacent, however oppositely tapered opposite tapered fende electrode plates, each with one Pole of the AC supply voltage are connected. Also such an embodiment of a voltage distributor elements falls under the scope of the present Invention, although this as a specific design of a Voltage distribution element a real voltage divider preferably in the form of a resistance track, just as it is common with potentiometers.

Furthermore, the basic principle according to the invention enables Realization of evaluation circuits on electronic Basis by which disturbance influences are practically Eliminate the table completely, at least keep it to a minimum because it is part of the basic principle of the invention that the position of a movable body with the help of a first potential working on a capacitive basis measuring probe detected and from this to a potential coupling probe is transmitted with the potential measuring probe is at least electrically connected and in the preferred Embodiment with this a single component forms. The potential coupling probe is then in turn again with a stationary coupling electrode capacitive active connection, so that in the equivalent circuit image the sensor as a first measuring capacity represents that of the voltage (distributor) element itself  alternating AC amplitude depending on the position taps - in fact, a kind of measuring capacitor from the potential measuring probe together with the voltage divider element formed - whereupon the tapped potential via an additional "coupling capacitor" an amplifier is supplied, this coupling capacitor physika is formed from one with the potential measuring probe physically connected potential coupling probe and that of Coupling probe associated coupling electrode, the one spatially extended shape with main extension direction in the measuring direction, and at which the detected measuring pots tial is then tapped for evaluation. It is therefore possible on any connection cable or other mechanical, live components that move be subjected - with the exception of the unit Potential measuring probe and potential coupling probe, complete to waive, so that no variable stray capacity or occur due to the relocation Connection cable subjected to mechanical stress are still corresponding changes in capacity can influence the measured value obtained.

A preferred design contains on a suitable one The substrate isolates each other from the voltage (distributed) Element and spatially parallel to it, however in The coupling electrode runs at a distance, the common component from potential measuring probe and potential coupling probe mechanically safely in a suitable manner Voltage (distributor) element and coupling electrode is, so that overall no changes in capacity can kick.  

It is possible to change the design in terms of a potentiometer meters rotationally symmetrical or as a linear encoder in the manner of a linear longitudinal potentiometer.

In this respect, the has a measuring capacitor, for example preferably constant capacitance forming first measuring con capacitor device via a stationary voltage divider element and the one movable plate (potential measuring probe) of the common component from the potential probe and Potential coupling probe, including the coupling capacitor device from a stationary part, namely the Coupling electrode, and a movable body, namely the other partial plate of the common component, which forms the potential coupling probe. With constant Capacity here means that capacity in any case during a measuring cycle, for example from measuring and Reference phase exists, is constant. Otherwise there is one Change in capacity, of course not with a Change in measured value is correlated, possible. In the equivalent circuit image appear measuring capacitor device and Coupling capacitor device connected in series, whereby the detached from the movable potential probe constant AC amplitude measurement at the station Ren coupling electrode is removed.

It is also possible that the common component, which the common structure of potential measuring probe and potentiometer alkoppelsonde represents these two probes le diglich electrically connected to each other, however are always arranged so that they are one synchronous shifting movement for data acquisition experienced so that deformations or changes  existing electrical connection paths excluded and there are always linear relationships.

It is possible to place the measuring capacitor device on the one side and the coupling capacitor device against overlying on the other side of a substrate or of a carrier body - it is also possible both in the form of concentric circles or circles on a common, then circular support surface like this build that central axis the common Component from potential measuring probe and potential coupling probe in constant rigid distance to the voltage (distributor) element and to the coupling electrode.

Another advantage is that the voltage (ver) divider element a variety of different embodiments can have, starting with one by itself seen known resistance path, like this one at Potentiometers, for example through a resistance Plastic covering (sprayed on, steamed on or otherwise applied) is formed, via which the potential measuring probe as a plate-shaped surface element without contact in constant distance is led up to itself in oblique Displacement of mutually extending electrode plates, which carry different AC voltage potential and so arranged and geometrically extended in Meßrich tion that depending on the displacement the plate of the Potential measuring probe each different area of such a voltage distributor element covered and in the sense of averaging here also a certain one, following the displacement path  finest resolution changing total voltage potenti al is detected.

In between, voltage (distribution) devices can be installed lying in the direction of displacement from each other bordering individual electrode plates exist that each have different voltage potential and for this purpose with a resistor chain circuit are connected, the area of the potential measuring probe depending according to their position over the counter electrode plates such voltage (distribution) element different covering large areas and integrating them fine on resolved amplitude signal of the change voltage potential detected and on the coupling capacitor device, namely the associated potential measurement transfers from which the tapped potential reaches the coupling electrode.

Thus, in the first embodiment, the voltage includes (Distribution) element a resistance track or potentioms terbahn, which is connected to an alternating voltage, whereby the potential measuring probe is a constantly changing Voltage amplitude curve is offered for sampling.

A "voltage divider" with a stepped voltage curve can be formed in that one behind the other in the measuring direction other arranged, substantially rectangular Kon capacitor plates are provided against each other are insulated and being each of the capacitor plates that in its entirety the stationary voltage divider element form, each with the connection terminal one Series resistor circuit are connected. Despite  step-like voltage curve over such a voltage generated by individual electrodes lereinrichtung is the voltage curve of the Potential measuring probe formed linear, where it it is understood that the geometry of the potential measurement probe, d. H. their plate shape, the geometry of the respective con capacitor plates is adapted. Because the distance between the respective plate shape of the potential measuring probe and the Electrode or "capacitor" plates of voltage divider is preferably kept constant when the Potential measuring probe moved in the measuring direction also occurs here no change in capacity as a disturbance variable.

It is also possible to use the voltage (distribution) distribution device in the form of two or preferably three, crosswise extending to the measuring direction and extending in the measuring direction tapering or widening capacitor plates or better to train electrode plates against each other are insulated, with adjacent electrode plates in same direction of measurement one against each other set rejuvenation or widening structure exhibit. Since each of the electrode plates on one different voltage connection, where one middle electrode plate for example with the change voltage and the other two adjacent electrodes plates can be connected to ground, of course at the same time the other AC voltage connection is closed, the capacitor plate becomes the potential measuring probe depending on position and direction of displacement ever larger or smaller part of the full bill voltage amplitude leading a plate and correspond an ever smaller or larger part of the  the other or further connected to the ground connection cover other plates so that at the potential measuring probe changes in the direction of displacement AC voltage amplitude pattern results in corresponding finest resolution in the direction of displacement, which unadulterated via the potential coupling probe to the stationary coupling electrode is transmitted.

It is also possible to use the plate shape of the potential measuring probe de a special, combating the influence of disturbances Give shape; so with another execution Example, the voltage divider device again a sequence arranged one behind the other in the measuring direction for example, essentially rectangular elec tread plates exist, each different Have potential or already through the above explained each tapering or widening Electrode plates while the potential probe is on opposite sides seen in the measuring direction ent opposite, each tapering or widening de approaches that are acute-angled in the measuring direction adjacent electrode plates of the stationary voltage cover the divider device additionally. At such a capacitive sensor structure results in a high sensitivity with little influence from edge effects at the transitions of the rectangular electrodes plates.

Basically, the one recorded by the potential measurement probe Voltage curve essentially linear if their physical shape is rectangular-plate-shaped and has an extension in the measuring direction, which in  essentially the extent of the rectangular elec tread plates of the voltage divider device corresponds The triangular approaches on both sides allow the Further increase the linearity of the voltage curve, whereby such, always an average of the tapped Voltage-forming potential measuring probe is both usable with adjacent electrode plates in the measuring direction as well as in such voltage divider devices from tapering or widening in the measuring direction Electrode plates exist, with combinations in Construction of such a voltage divider device possible are by on one side of a dielectric the adjacent electrode plates and on the on the other hand, the tapering or widening Electrode plates are arranged.

By the measures listed in the subclaims are advantageous developments and improvements of Invention possible.

drawing

Embodiments of the invention are in the drawing are shown and are described in the following description explained in more detail. Show it:

Figure 1 is a schematic representation of a first embodiment of a linear displacement sensor on a capacitive basis on the basis of a voltage divider device with a constant voltage curve.

Fig. 2 shows a further embodiment of a straight-line displacement sensor on a capacitive basis, here also each consisting of the measuring sensor and the coupling area, the voltage divider being formed from individual, but mutually insulated, electrode plates, each of which is formed by a chain resistor series circuit different AC potential;

Fig. 3 shows, also schematically, a third embodiment of a linear displacement sensor on a capacitive basis with such a formation from the voltage (distribution) distribution circuit that, in conjunction with the associated counterplate of the potential measuring probe, amplitudes different AC voltages seen by the capacitive tapping effect over the measuring direction taps;

FIG. 4 schematically shows an embodiment of a position sensor on a capacitive basis with a combination of the voltage (distribution) distributor device from the assembly structures of FIGS . 2 and 3, while the

Fig. 5 shows a last embodiment of a position sensor on a capacitive basis, in which two rotary measuring systems are arranged on a common substrate; the

Fig. 6 and Fig. 7 show schematically for a better understanding of the invention representations of a voltage (distribution) divider element, wherein Fig. 7 shows the capacitive functional relationship between the potential measuring probe and the voltage (distribution) divider element, here in the form of a resistance path;

Fig. 8 finally shows a preferred Ausgestal device in a schematic representation, in which a bilateral tap is provided.

Description of the embodiments

The basic idea is to use a position Capacitive-based sensor a potential measurement provide rich, which by capacitive detection of a changing AC voltage Ver pattern as a voltage amplitude Function of the potential probe position recorded and with the Potential measuring probe at least electrically, preferred at the same time mechanically a potential coupling area connect through which, also on capacitive Basis of the measured voltage amplitude measured value overall contactless, but without changing the capacitive elements involved, an evaluation is fed. This makes it possible to move away with linear movement, the angle with a rotating movement tion or the position taken in each case to determine the movable body very precisely.

The first embodiment of a position sensor 10 shown in FIG. 1 comprises a potential measuring area 11 and a potential coupling area 12 , in this exemplary embodiment the potential measuring area being a real voltage divider element 13 with a constant voltage curve, for example a resistance path, as is usually the case with sensors on a potentiometric basis (DC-fed ) or tern are common with rotary potentiometers.

The two end connections 13 a, 13 b of the resistance path of the voltage divider are supplied by a supply and, if desired, at the same time evaluation circuit 14, a supply change voltage of predetermined constant or controllable amplitude, one of the connections, for example 13 b is connected to ground.

The resistance path of the voltage part is non-contact, i.e. assigned a potential measuring probe 15 at a predetermined distance, which is in this way in a capacitive operative connection with the resistance path and is therefore also capable of changing the AC voltage potential via the path s (in the measuring direction) Resistance path to tap, which in this case rectangular plate-shaped potential measuring probe 15 has an integrating or averaging effect and always taps such an alternating voltage amplitude as results from the position of the potential measuring probe.

The height of the plate of the potential measuring probe should correspond approximately to the width of the stationary resistance path, the resistance path can be arranged on a suitable carrier substrate, in parallel (or on the other side) to the course of an (also rectangular) electrode surface 16 of the Potential coupling area 12 . It is understood that the potential measuring area 11 and the potential coupling area 12 are electrically insulated from one another, which can be done in a suitable manner and need not be explained further. Electrical insulation is already given, for example, when the two areas 11 and 12 are on opposite sides of an insulating carrier substrate or, in the case of a parallel arrangement, on the same side, the coating of the carrier substrate, if one is provided, and for example from Leitsilber can be formed, is continuously interrupted between the two areas.

As the Potentialmeßbereich 11 has also the Potenti alkoppelbereich 12 via a movable probe part, namely the potential of the coupling probe 17, which moves also at a predetermined distance, so contact-free via the consistently electrically conductive electrode surface 16 of the potential coupling portion 12 in synchronization with the potential measuring.

The each in the illustrated embodiment rectangular areas of potential measuring probe and Potential coupling probes are at least electrically included connected - preferably they form a common, electrically conductive and with the assigned tracks in capacitive active connection standing common component for example, a double copper plate assembly, which by a suitable one, not shown in the embodiments put storage together over the assigned areas  of resistance path or electrode surface in the measuring direction is moved.

Recognizable form the respective areas of potential measuring probe 15 and potential coupling probe 17 with the respective mating surfaces of the resistive path or the electrode surface 16 a capacitor (measuring capacitor or coupling capacitor) whose capacitance remains unchanged over the displacement path s, so that changes in capacitance in the Do not include measured value formation.

The electrode surface 16 of the potentiometer coupling region 12 therefore extends over the length of the displacement path s parallel to the voltage divider device so that the two capacitor parts moving with the measuring path, namely the potential measurement probe 15 and the potential coupling probe 17 , can move together and synchronously with one another and are preferred can form a common, one-piece component with then corresponding mechanical storage.

In this way, the potential coupling probe 17 transfers the tapped from the potential measuring probe 15 and in this respect also applied to it itself alternating voltage amplitudes capacitive to the electrode surface 16 of the potential coupling region 12 , which only requires a single connection 16 a, of which the tapped voltage amplitude signal on the input 18 of the feed / evaluation circuit 14 arrives. It is understood that an appropriate coupling or shielding prevents electrical coupling between the voltage divider element 13 and the electrode surface 16 of the potential coupling region 12 .

The carrier and insulating substrate can be one Small expansion epoxy or ceramic circuit board be coefficient and is connected to ground.

Ultimately, it is also possible to take into account a dependency of such a position sensor on the ambient temperature by providing the carrier substrate with a temperature sensor, the signal of which is also fed to the evaluation circuit 14 .

The operation of such a position sensor is then identifiable so that the voltage applied to the resistor sheet 13 AC (or a corresponding AC frequency mixture) rising as linearly or falling signal, as further shown below in Fig. 2, picked up by the potential measuring 15 on the Transfer potential coupling probe and from this capacitively coupled to the electrode surface 16 , so that the capacitively tapped signal reaches the evaluation circuit 14 without any falsification and other interference.

It goes without saying that the electrode surface 16 transmits the signal without resistance, for example it can be formed by a suitable copper cladding on the carrier substrate or consists of a conductive silver coating of the appropriate size and shape.

The potential tapped by the potential measuring probe 15 results from the sum of the partial voltages at the position assumed by the potential measuring probe (measuring path s). One of the partial voltages depends on the position (measuring path s) assumed by the potential measuring probe. One partial voltage is generated by the input voltage at the beginning of the stationary resistance path and is proportional to the difference between the measuring position s and the length of the resistance path. The other partial voltage is generated by the (antiphase) input voltage at the end of the resistance path and is proportional to the position s.

Even the smallest displacements of the plate of the potential measuring probe are included in the tapped alternating voltage amplitude, since the ratio of the partial stresses naturally changes with a shift by δs. The recording of the measurement signal is contact-free, as is its transmission to the stationary electrode surface 16 , so that such a position sensor is not exposed to mechanical wear and no variable disturbances such as, for example, variable scattering capacities occur, which are caused by the bending of connecting lines or contact resistances during grinding contacts can be generated.

The previous explanations can be specified more precisely by the following considerations carried out with reference to the representations of FIGS. 6 and 7:
On the "potentiometer" resistance track corresponding to FIG. 6, a potential distribution is established in the case of AC power supply according to the following formula:

or expressed as an electrical field distribution

Here, as also shown in FIG. 6,

ϕ₁ <ϕ₂ <ϕ₃ <ϕ₄ <. . .

Since it is an AC voltage, it can Potential can be represented as follows:

ϕ = ϕo · sign [sin (ω · t)]

With
ϕo = amplitude of the potential
ω = angular frequency 2 π
= Frequency
t = time.

The entire system can be understood as a capacitor, which is composed of nothing but small capacitors, as shown in detail in FIG. 7.

The capacitor equation is:

C = εr · εo · A / α

With
C: capacity
εr: relative dielectric constant
A: area of the capacitor
d: distance (of the plates).

The capacity results from

The following should apply to the capacities:

The tapped potential depends on the location x in a linear relationship. → ϕ = ϕ (x). Displacement currents I _i flow into the probe via the partial capacitances ΔCi, the following applies:

The following then applies to the entire displacement current I:

d. H. the individual voltage amplitudes are added up to a total displacement current I.

The embodiment of FIG. 2 is similar to the exemplary embodiment of FIG. 1 except for the fact that the voltage divider element 13 'in this case does not have the shape of a resistance track, but rather individual, lined up but mutually insulated electrode plates 19 which have a predetermined one Have extension B in the measuring direction and are supplied with partial voltages of the supply voltage present via a "resistance" voltage divider 20 . The voltage division can be brought about by any impedances, such as resistors, inductors or capacitors, which are connected in series and whose connection points are each connected to the individual electrode plates 19 . In this case it is advisable to in any case the extent of the area of the potential measuring probe de 15 'equal to or at least equal to the width dimension B of the individual electrode plates, because a movement of the plate of the potential measuring probe along a given electrode plate 19 would then not be fixed if the width of the potential measuring probe is smaller than the width of one of the electrode plates.

Such a connection of the individual electrode plates 19 results in a step-like voltage curve on this and over the entire sequence of the electrode plates; Despite this step-shaped voltage curve of the AC voltage present, however, the voltage tapped from the plate of the potential measuring probe 15 'is linear due to the integrating effect of the capacitive coupling, neglecting edge effects, and in turn corresponds to the voltage curve shown in FIG. 2 below over the measuring distance s.

A further embodiment of the invention with an otherwise identical design in principle relates in turn to the wiring of the voltage divider device according to FIG. 3, which in this case consists of, for example, two, as shown, but preferably three, arranged transversely to the measuring direction and tapering or widening in the measuring direction surfaces 21 exists.

In this case, the two outer, in the drawing plane of FIG. 3 to the right, acute-angled measuring electrode surfaces can be connected to the one terminal 13 a of the feed / evaluation circuit 14 , while the middle measuring electrode surface is connected to the other terminal 13 b, the is simultaneously at ground. The voltage divider properties or better the voltage distribution properties of such a voltage (ver) tei lerelements 13 'result from the combined overall effect of the constant voltage across the entire length of the individual strips of the measuring electrode surfaces, but this is due to the integrating effect of all surfaces in the transverse direction each concurrently overlapping plate of the potential measuring probe 15 'come into effect only in accordance with their respective relatively covered area proportion. Here, too, there is exactly the same linearly scanned voltage curve of the highest resolution as shown in FIG. 2 below, with the further advantage that the influence of edge effects is minimized, it being sensible to dimension the plate of the potential measuring probe 15 in the transverse direction 'To be designed so that it overlaps the electrode surfaces of the measuring electrode.

Fig. 4 shows a combination of the design of the voltage divider element from the two variants shown in Figs. 2 and 3, wherein the carrier plate can be formed by a double-sided dielectric, on one side, the potential measuring probe 15 '' facing side as in Fig. 2 shown in the measuring direction one behind the other electrode plates 19 'of the width B are arranged, while on the opposite side of the dielectric in this case le diglich two in the measuring direction opposite to each other tapering or widening Meßelek electrode surfaces 25 , 25 ' are arranged , which are each connected to the opposite connections of the feed / evaluation circuit 14 . A corresponding connection is also shown in Fig. 4 exactly as shown in Fig. 2, with respect to the electrode plates 19 ', but is no longer shown in Fig. 4 for reasons of clarity.

In addition to this, the linearity conditions and the freedom from interference can be improved even further by the fact that, as also shown in FIG. 4, the plate of the potential measuring probe 15 '' consists of an inner rectangular part of the extent B in the measuring direction corresponding to the rectangular electrode plates 19 ' and from two further, preferably triangular parts, which are attached to the two sides and also take up a width B in the tapering direction. This can reduce the cracks on the edges, tailored to the geometry of the panels.

In Fig. 5 is finally a basic principle like the embodiments of FIGS. 1 to 4 working position sensor is shown, which is constructed in the manner of a rotary potentiometer and comprises a double system, so that only one of the embodiments needs to be discussed in more detail. There is an outer resistance track or resistance path 13 '''shown with an annular shape and AC connections 13 a', 13 b 'at the respective ends, whereby, following a concentric inner circle segment, the coupling electrode surface 16 ' is provided with only one external connection 16 a .

The two stationary surfaces of the potential measuring and potential coupling area 11 , 12 are coated by a common component 20 from the potential measuring probe and the potential coupling probe, which is rotatably mounted, the component being punched, for example, in one piece from a shape shown in FIG. 5 Copper plate can exist, the potential coupling probe part 17 'transfers the tapped potential to the coupling electrode surface 16 '.

In the case of high linearity requirements, linearity adjustment may be necessary in all of the illustrated embodiments. For example, in resistance elements in a known manner, an adjustment by changing the width of the resistance track is possible, while in the embodiments of FIGS. 2, 3 and 4, the linearity adjustment by adjusting the voltage divider resistors or by correcting the width of the tapering or widening conductor tracks is possible.

Regarding the embodiments of FIG. 4, it is also worth mentioning that the contour of the conductor tracks on the back, that is, the measuring electrode surfaces 25 , 25 'can be arbitrary per se, it should only be ensured that the capacitance between the capacitor surfaces on the front and the rear Subareas is in a predetermined division ratio. This can be done by comparing the partial areas behind the individual electrode plates 19 on the front.

Finally, it is pointed out that the embodiment shown schematically in FIG. 8 of a double-sided tap, in which two potential measuring probes, a first probe I and a second probe 11 are located on opposite sides of a resistance track, is particularly suitable in order to thereby To reduce the influence of distance variations and at the same time to minimize the influence of a local or global change in the relative dielectric constant. It can be seen that a change in the distance of one of the probes to the resistance path scanned by it, for example in the sense of increasing the distance, necessarily leads to a simultaneous reduction in the distance of the other probe to the resistance path, so that these two influences cancel each other out .

The usual displacement transducers can be used as evaluation circuits assigned and known evaluations circuits are used in which the way pickup tapped signal in a suitable manner is increasingly processed and displayed. Especially but are suitable evaluation circuits in which Avoidance of interference caused by the output of the displacement transducer or at the input of the evaluation circuit leakage resistances and stray capacities stand by the signal tapped at the displacement transducer suitable means at a potential level of zero is set, namely by corresponding legs flow of the supply voltage of the potential measuring range.  

In conclusion, it is pointed out that the claims and in particular the main claim attempts at formulation the invention without extensive knowledge of the state of the Technology and therefore without restrictive prejudice.

Therefore, it is reserved, all in the description, the claims and the drawing features shown both individually and in any comm combination with each other as essential to the invention and lay down in the claims as well as the main claim to reduce its feature content.

Claims (15)

1. A method for determining a respective local position, the displacement or the angle of a movable body, wherein a probe is guided along a predetermined potential distribution and the measured value detected by the probe is evaluated, characterized in that

• a) an at least spatially extended voltage (divider) element is fed with an alternating voltage, such that there is in at least one direction on the voltage (divider) element an AC voltage amplitude distribution pattern with different AC amplitudes in the at least one direction shows that
• b) a potential measuring probe is guided along the at least one direction in accordance with the path (s) to be recorded, the angle or the position and is held at such a contact-free distance from the voltage (distributor) element that the potential measuring probe depends on it assumed position under different AC amplitudes of the AC amplitude distribution pattern detected by capacitive coupling, the capacitance relationships over the potential probe displacement are kept substantially constant that
• c) the potential measuring probe is connected to a potential coupling probe which works capacitively on a coupling electrode, of which
• d) the alternating voltage amplitude measured value detected by the potential measuring probe, which is independent in the measuring direction of the respective relative position between coupling probe and coupling electrode, is transmitted for evaluation.

2.Contactless position sensor on a capacitive basis for determining a respective local position, the displacement or the angle of a movable body, a probe being guided along a predetermined potential distribution and the measured value detected by the probe being evaluated, characterized in that a flat voltage ( ver) tei ler element ( 13 , 13 ', 13 '', 13 ''') is provided with at least one main direction of extension in the measuring direction, to which an alternating supply voltage is supplied,
that a potential measuring probe ( 15 , 15 ', 15 '') is guided along the voltage (divider) divider element and without contact with it in the distance which does not change with the measuring movement,
that the potential measurement probe is at least electrically connected to a potential coupling probe and performs the measurement movement together and synchronously with it, whereby
the potential coupling probe is connected to a stationary coupling electrode surface ( 16 ) in a capacitive active connection, at which the potential measuring probe ( 15 , 15 ', 15 '') detected, the AC voltage amplitude changing linearly with the measured value is obtained for evaluation. 3. Position sensor according to claim 2, characterized in that the potential measuring probe ( 15 , 15 ', 15 '') and potential coupling probe ( 17 ) is a one-piece, electrically conductive, at least in the area of its counter surfaces (coupling electrode surface 16 ; voltage divider element 13 , 13 ' , 13 '', 13 ''') each have a flat expansion component, which has a uniform bearing for carrying out the measuring movement, which is so formed that the capacitance ratios in the potential measuring and potential coupling probe area to the respective counter surfaces (Coupling electrode surface; voltage divider element) behave essentially without change. 4. Position sensor according to claim 2 or 3, characterized characterized in that the potential measuring probe with its each assigned voltage divider element and Potential coupling probe with its assigned  Coupling electrode area in each case by the measuring movement not changeable, in series measuring and Form coupling capacitors. 5. Position sensor according to claim 4, characterized in that the moving parts (potential measuring probe 15 , 15 ', 15 ''; potential coupling probe 17 ) of the measuring or coupling capacitor can be driven in parallel and together in the measuring direction, while their respective capacitor counter surfaces (span nungs (ver) divider element 13 , 13 ', 13 '', 13 '''; coupling electrode surface 16 ) are mounted stationary on a carrier substrate. 6. Position sensor according to one of claims 2 to 5, characterized in that the potential measuring probe ( 13 , 13 ', 13 '', 13 ''') and potential coupling probe ( 17 ) are mechanically and electrically coupled to one another. 7. Position sensor according to one of claims 2 to 6, characterized in that the Potentialmeßson de and the associated voltage (ver) divider element comprehensive potential measuring area ( 11 ) and the potential coupling probe ( 17 ) with associated coupling electrode surface ( 16 ) comprehensive Potentialkoppelbe rich ( 12 ) are arranged on the same or on opposite surfaces of an insulating carrier substrate. 8. Position sensor according to one of claims 2 to 7, characterized in that the voltage (ver) divider element ( 13 ) is a voltage divider in the form of a potentiometer resistance track ( 13 ). 9. Position sensor according to one of claims 2 to 7, characterized in that the voltage (ver) tei ler element from one behind the other in the measuring direction, mutually insulated electrodes plates ( 19 , 19 '), each with the connection terminals of a chain resistor voltage divider circuit ( 20 ) are connected in such a way that a voltage divider with a stepped voltage curve results overall. 10. Position sensor according to one of claims 2 to 7, characterized in that the voltage (ver) tei ler element ( 13 '') from at least two, preferably three, arranged transversely to the measuring direction and tapering or widening measuring electrode surfaces in the measuring direction ( 21 ), with adjoining measuring electrode surfaces in the same measuring direction each having an opposite tapering or widening characteristic. 11. Position sensor according to one of claims 2 to 10, characterized in that the voltage (ver) tei ler element ( 13 '''') comprises a double-sided coated dielectric, on one of which the Potenti almeßsonde ( 15 '') facing Side in the measuring direction arranged one behind the other electrode plates ( 19 ') are provided, while on the opposite side two in the measuring direction tapering or widening measuring electrode surfaces ( 25 , 25 ') are formed. 12. Position sensor according to claim 9, characterized in that the extension of the plate of the potentiometer probe ( 15 ') in the measuring direction corresponds to the width (B) of each electrode plate ( 19 ) in the measuring direction. 13. Position sensor according to one or more of claims 2 to 12, characterized in that the plate of the potential measuring probe on its rectangular part with an extent (B) in the measuring direction corresponds to the width of each electrode plate ( 19 ) and composed of two triangular parts extend on both sides in the measuring direction. 14. Position sensor according to one or more of claims 2 to 13, characterized in that at least one measuring system consisting of a potential measuring region ( 11 ) and a potential coupling region ( 12 ) is provided on a common circular carrier substrate, with a resistance divider comprising a voltage divider element ( 13 ''') in the form of a circular segment and a concentric to this inner coupling electrode surface ( 16 '), which also follows a circular segment, and with a common electrically conductive component (stamped part), which surfaces from the two plate-shaped counter capacitor of the potential measuring probe ( 15 '''') and the poten tialkoppelsonde ( 17 '), which are mechanically and electrically connected by an integral intermediate web and are guided by a common bearing along the predetermined pitch circle movement of the measuring path. 15. Position sensor according to one or more of the An sayings 2 to 14, characterized in that a common voltage (divider) element (contr life cycle) to reduce the influence of a Distance variation from both sides at the same time Is sensed for a bilateral tap.