DE202005016333U1 - Hall-effect sensor for determination of motor vehicle seat position, has actuator including actuating surfaces that are moved in direction of track and are guided over sensor coils whose change in inductance corresponds to actuator position - Google Patents

Abstract

The sensor has sensor coils provided on a printed circuit board (3), and an actuator (7) is provided at a distance from a track from the coils. The actuator has actuating surfaces (9, 9`) that are moved in the direction of the track and are guided over the coils. An electrical evaluation circuit determines the change in inductance of the coils corresponding to a track position of the actuator and transmits a seat position signal.

Description

The The invention relates to an inductive sensor unit, in particular for the Position detection of a vehicle seat or for a gate circuit of a automatic transmission (selector lever module) suitable is. The field of application of the invention also includes a Distance measurement on spring elements of a chassis.

The Invention is embedded in the development of fault-tolerant, safer control systems in vehicles where electronic cables are the conventional ones replace hydraulic and mechanical connections (X-By-Wire). The invention is particularly suitable for Tasks of displacement measurement, where distances of more than 30 mm to be determined.

The described sensor system can also be used for angle measurements to detect a circular segment or a complete revolution. Applications for this are in the automotive sector, for example, the measurement of the seat back position or measuring the position of a foot pedal.

The inductive sensor unit has a plurality of sensor coils, which are applied planar on a printed circuit board. These sensor coils work with a conductive actuator together, spaced on a predetermined path across the Leaded away sensor coils becomes. The conductive actuator triggers due eddy current effects inductance changes in the sensor coils out. The inductance a sensor coil is all the more reduced by the eddy currents, the more adjacent the actuator is located on the sensor coil. Also part of the inductive sensor unit an electrical evaluation circuit that these inductance changes the sensor coils according to the track position and accordingly the distance of the actuating element detected by the sensor coil and converted into electrical signals. The electrical signals are in particular seating position signals or Gear shift signals or suspension spring signals.

A Such sensor unit, of which the invention in the preamble of Claim 1, is known from the publication WO 2004/027994 A1 known.

Out In this state of the art, it is further known that the distance measuring signals distance-dependent are, i. when the actuator on one by mechanical tolerances relative to the circuit board level curved Track led or if the circuit board is not flat, then changes in distance will occur into the measuring signals. The circuit board can in a predetermined manner bent or it can be a big, planar circuit board have unintentional curvatures. In the state the technique becomes the distance dependence by standardization and calibration in the electronic evaluation circuit balanced.

Further In the prior art, the position detection of the electrical Actuator along the Train that over the majority of the sensor coils leads, realized so that the inductance changes each adjacent Sensor coils are compared. This evaluation allows only a position resolution according to the grid of adjacent sensor coils.

From the prior art according to the German patent DE 103 19 720 B3 is a link switching unit for generating gearshift signals for an automatic transmission of a motor vehicle known. In this gate switching unit, a shift shaft is mounted with a selector lever in a switch block. The selector lever can be pivoted in a first plane S, but also perpendicular thereto in a second plane T. For this purpose, it is hinged to the switching shaft. The movement of the selector lever often corresponds to the positions P, R, N and D for the park, reverse, neutral and driving position of the selector lever. The selector lever pivots a rotor with a shift finger housed in a module housing. The shift finger pivots over a printed circuit board with an inductive sensor unit and represents an embodiment in which the shift finger can carry the still to be described actuator according to the present invention. Other spatial associations and other paths of the conductive actuator relative to the circuit board are also possible.

Out Laid-open publication US 2003/0169033 A1 is also a sensor field for non-contact Position measurement known. This sensor field is for determination used the Wegposition a vehicle seat. Each sensor element produces an output signal that coincides with a position from the set the possible Seat positions correlated. For the sensors use the Hall effect. For controlling the Hall sensors either a magnet is provided, which is guided past the sensors, or a magnetic shielding member is provided by a magnetic field acting on the sensors is guided. Also allowed here the signal evaluation only a limited position resolution according to the grid the neighboring sensors. From this state of the art goes the Invention in the preamble of the independent claim 17.

The fault tolerant mentioned above, si Chere control electronic systems in vehicles require in principle an increased redundancy. Some components must be duplicated to avoid malfunction with certainty. For example, it is known from the inductively operating selector lever module according to WO 2004/027994 A1 to provide two sensor units per switching position, ie the printed circuit board is additionally equipped with safety sensor units and a second actuating element. Similarly, a lever module operating with Hall sensors is known, which is equipped with a larger number of Hall sensors so that each position is detected twice by the sensor. Since the sensors represent a considerable part of the system costs, the object of the invention is to meet the redundancy requirements which protect this sensor unit against the failure of a sensor element as cost-effectively as possible.

The solution succeeds according to the independent claims 1 and 17 in that the (conductive or permanent magnetic) actuator two or more base areas wearing, offset in the direction of the trajectory via the sensors (i.e. Sensor coils or Hall sensors).

The Principle of the invention is to provide the necessary redundancy to provide the actuator instead of the sensors. This will be explained below mainly on Example of an actuating element with conductive Bedding surfaces for sensor coils described.

Thereby, that two or more damping surfaces in Rail direction are offset, even in case of failure of a sensor coil the position of the actuator provided with more than one cushioning surface be determined with sufficient accuracy.

Appropriate further education go from the subclaims out. Preferably, the actuating element two or three staggered bases on, the contactless over led the circuit board become. Depending on the available standing space can the bases either on one side over slide the circuit board or they can fork-shaped over the circuit board. The first possibility leads to a lower height, while the second possibility the influence of the distance between the respective base area and the printed circuit board is reduced.

The Invention makes u.a. of it use that by a doubling of the (usually diamond-shaped) damping element the distance dependence the measuring signals is reduced if (i) a one-sided planar Sensor coil forked through the actuator swept over or (ii) a double-sided planar coil pair is forked over and in the evaluation circuit, the inductances of the opposite Sensor coils are serially connected to each other or computationally added. By this measure the standardization of the measuring signals is facilitated and thus also the spatial resolution between specified adjacent sensor coils. Because of this measure can be made more secure in the evaluation circuit, whether the conductive actuator rather one sensor coil or rather the other sensor coil covers.

to Invention belongs also that the inductors all sensor coils - serial in time multiplex or also detected in parallel - detected and by means of an algorithm in a current track position of the measuring element (Operation member) be implemented. The algorithm can be local, for example Determine the focus of all inductance changes or he can in another variant a quadratic interpolation along the Calculate coil order. Both variants reflect the maximum the signal distribution the track position of the actuator more accurate than in the prior art again. For example, with 15 coils, 300 positions of a vehicle seat dissolved become. At the same time by such evaluation algorithms also the distance dependence of the generated position signal, because the different, each distance-dependent Measurements longitudinal the train by the offset in their distance dependence less important.

The Evaluation algorithms also contribute to the failure of a sensor coil to compensate. If at a certain track position a sensor coil (or a series-connected coil pair) fails, so can the missing signal be replaced by interpolation. Because the neighboring signals are more reliable due to the offset bedding surfaces become.

embodiments The invention will be explained with reference to figures. It shows:

1 a side view of a printed circuit board with a plurality of sensor coils and a plan view of a fork-shaped actuator;

2 a perspective view of the circuit board, the sensor coils and the actuating element according to 1 ;

3 a graphical representation of a normalized attenuation value of a sensor signal generated by a single coil in dependence on the degree of coverage with which the sensor coil is covered by the actuator;

4 a graphical representation of the normalized attenuation value of the sensor signal of 3 depending on the distance between the sensor coil and the actuator;

5 a hardware concept for measuring the inductive resistance (reactance measurement) of, for example, four adjacent sensor coils;

6 a perspective view of a circuit substrate (in particular a printed circuit board) and the structure of a double-sided planar applied and connected in series coil;

7 a perspective view of the structure of an inductive sensor unit with, for example, 15 double-sided coil and a fork-shaped double actuator;

8th a graphical representation of the voltage signal values of the 15 coils according to 7 as a function of the index of the 15 coils or as a function of the travel of the actuating element along the 15 coils;

9 a graphical representation in which the in 8th voltage values converted by zero normalization into values suitable for the application of a centroid formula;

10 alternatively to the center of gravity calculation according to 9 a quadratic interpolation of the normalized signals by means of a parabola;

11a an inductive sensor unit according to the invention, wherein the sensor inductances are mounted on a plate side;

11b an inductive sensor unit according to the invention, in which two planar sensor inductances are accommodated on opposite sides of a printed circuit board and connected in series;

11c an inductive sensor unit according to the invention, in which opposing sensor coils are evaluated separately with respect to their inductance;

12 the top view of an embodiment of the inductive sensor unit, in which two Bedämpfungsflächen of the actuating element are arranged offset in the web direction;

13 a side view of the embodiment according to 12 ;

14 an actuator similar 12 with a third offset cushioning surface; and

15 a plan view of another form of inductive sensor unit, are guided in the three offset Bedämpfungsflächen circular arc on one side of a curved sensor array.

• – die Spulenanordnungen gemäß den 1, 2, 6, 7, 11a, 11b und 11c;
• – die Dämpfungskurven gemäß den 3, 4, 8, 9 und 10; und
• – die Auswerteschaltung gemäß 5.

The invention is structurally based on a sensor arrangement, as described in the earlier utility model 20 2004 019 489.9. For a better understanding of the environment of the present invention, reference will accordingly be made to

• - The coil assemblies according to the 1 . 2 . 6 . 7 . 11a . 11b and 11c ;
• - The damping curves according to 3 . 4 . 8th . 9 and 10 ; and
• - The evaluation circuit according to 5 ,

These components of the sensor arrangement can equally be used in the embodiments of the present invention. Is further developed in the 1 . 2 and 7 illustrated double actuator, according to the examples in the 12 to 15 is extended in the web direction.

While the redundancy of the double operator according to the 1 . 2 and 7 an increase in the measurement accuracy in the distance direction to good, the multi-actuator ensures according to 15 for greater functional reliability in the web direction. The transition between the effects, however, is fluent, ie in the forked and offset multiple actuators according to 12 and 14 the redundancy is used for both effects.

In 1 is the view of an inductive sensor unit 1 shown. It is used for precise position determination in inductive sensors Li. An inductive sensor L is a coil that consists of several turns of a conductor on a printed circuit board 3 consists. To increase the inductance, a circuit board 3 be used with multiple layers. The inductance is matched with a suitable electronic circuit such as in 5 shown measured. A microcontroller 5 evaluates the measured voltages and calculates a path information. If you put a conductive actuator 7 , In particular, a metal plate, on the sensor L, so a lower voltage is output than in the case in which there is no metal plate 7 located near. The voltages can be normalized such that the high voltage corresponds to an attenuation value of 0% and the low voltage corresponds to an attenuation value of 100% (cf. 3 ).

If you drive a single actuator 7 via the sensors Li and records the damping values above the path, you get the in 3 illustrated waveform. It can thus according to any attenuation value in a certain range 3 be assigned a waypoint.

However, the waveform applies only if the distance a of the actuator 7 to the sensor Li is constant. If you change the distance at a certain position, the attenuation value changes accordingly 4 , Increasing the distance a, for example, from 0 mm to 0.1 mm, the normalized damping changes from 100% to 91%.

Allowing for a change in distance, which always occurs in practice because of mechanical tolerances, so a clear assignment between the sensor signal and path is difficult. To eliminate or significantly reduce this effect, a bifurcated actuator according to 1 and 2 used. In 1 and 2 is also shown that the circuit board 3 coated on both sides with sensors Li and Li '. The principle of the forked actuator 7 However, it also works with a single-sided printed circuit board 3 (see. 11a unlike the 11b and 11c ).

For example, if in 1 the distances a of the two surfaces 9 and 9 ' the fork-shaped actuator 7 of the two sides of the PCB have an amount of 0.1 mm, both sensors Li and Li 'show an attenuation of 91%, with addition of 182%. Now approaches the actuator 7 one pcb side to 0 mm (100% damping), it will be 0.2 mm (82% damping) on the other side. By adding the sensor signals, the change in distance is compensated. In both cases a signal value of 182% results.

The adding of the signals can be done in the microcontroller 5 take place (vg. 11b ). However, the two sensors Li and Li 'can also be connected in series, so that only one signal is produced (cf. 11b ). By the series connection according to 11b the inductances add up, which has the same effect as the signal addition.

5 shows an execution concept for the sensor unit according to the invention 1 , A sine wave oscillator 11 generates an alternating current with constant amplitude and constant frequency (eg f = 12 MHz). This high-frequency alternating current is amplified at 13 and successively (multiplexer 17 ) in each one of the sensor coils L1, L2, L3, L4 fed. In 5 For example, four sensor coils L1 - L4 are shown while in 7 . 8th and 9 For example, 15 sensor coils L1 - L15 are shown.

The number of sensor coils results from the measuring range, the required resolution and the required reliability in conjunction with the separation of the operating element 7 and the evaluation algorithm.

If you move an actuator 7 , which consists of good conductive material such as copper or brass, on the coils L1 - L4, so reduced by eddy current losses, the inductance L of the coils. This reduces the inductance (reactance) of the coils proportionally. Is the actuator located? 7 with its center over a coil center, so the coil Li has a maximum attenuation. The minimum inductive resistance results in a minimal voltage drop (with impressed current).

The voltage drop across coils L1-L4 is rectified at 15 and a microcontroller 5 fed for further processing. It can be worked in a known manner with impressed voltage or detuning of resonant circuits.

An example of the structure of a sensor coil L is shown in FIG 6 shown. The selected parameters are not fixed quantities and are for illustrative purposes only. The coils L and L 'are located on a circuit carrier (eg a circuit board 3 or an equivalent circuit carrier) and are arranged double-sided planar. They are electrically connected with each other (cf. 11b ) and have a helical winding sense. By this arrangement, the number of turns increases, which has a higher inductance result.

From these elements, an inductive sensor unit 1 according to 7 be built. In this embodiment, there are 15 coils L1 - L15 on the circuit carrier 3 , The geometric dimensions of the coils depend on the desired inductance and on the material. In a 25 mm × 10 mm rectangular coil L with 40 turns, an inductance of approximately 14 μH is obtained. The coils Li are arranged side by side and have a distance of 25 mm. The coils are dampened by a diamond-shaped double actuator 7 according to 7 (see also 2 ).

Is a sensor Li not from the actuator 7 covered, the attenuation is 0%; with fully covered sensor Li, it is 100% (cf. 3 ). The damping is also the distance a of the actuator 7 dependent on the sensor coils Li; at a greater distance a the maximum damping decreases, as in 4 you can see.

Through the double actuator 7 according to 7 a distance deviation is compensated and the attenuation is kept constant with suitable evaluation. The signal evaluation is in the 8th and 9 shown. By way of example, the actuator is located 7 at a mark of 200 mm.

The microcontroller 5 cyclically measures, at fixed intervals, the voltages of the sensors L1 - L15, which are proportional to their inductances. These voltages are in the microcontroller 5 converted to binary values and stored in memory with run index 0-14. In 8th the measured voltages are shown as a function of the index 0 - 14.

In the next step, a zero normalization according to 9 performed. This is done by the microcontroller 5 from the points according to 8th the sensor signal with the highest voltage (the highest binary value) is determined. In the example, this is the binary number 1024. Thereafter, the highest voltage is subtracted from each of the 15 sensor values. The normalized diagram is in 9 to see.

In practice, noise occurs in the signal detection of the coils Li. The coils Li without damping do not have a very constant value. This noise can be suppressed, for example by taking into account only the three smallest voltage values and with the maximum of these three voltages according to the zero standardization 9 performs.

Another possibility for position detection is to interpolate with a quadratic function by three points, as in 10 is shown.

For this, the maximum value of the parabola is searched for after the zero normalization. In the example, the maximum has the value 768 and is at the index coil 8th , As second and third point, the value left and right of the maximum is needed to perform the interpolation. In the example, the voltage to the left of the maximum has the value 256 and is located at the index coil 7 while the numerical value to the right of the maximum is 256 at the index coil 9 lies. The interpolation can be done according to known mathematical algorithms. The three points in the diagram according to 10 and the interpolation parabola show that the vertex of the parabola is the sought position of the actuator 7 is.

Based on 12 and 13 is an inventive modification of the fork-shaped actuating element 7 explains, whose two diamond-shaped Bedämpfungsflächen 9 . 9 ' are arranged offset in the direction of the trajectory. Again, the actuator slides 7 contactless via the linear arrangement of sensor coils Li. The sensor coils Li are on a printed circuit board 3 or applied to a comparable circuit carrier made of plastic. The coil signals arrive at a transmitter 19 on the same circuit board 3 can lie. The evaluation electronics 19 consists of transistors, resistors and capacitors, for example, the assemblies 13 . 15 and 17 according to 5 form. Via a serial interface 21 The sensor signals are sent to the AD converter of the microcontroller 5 (in 5 to see) forwarded. These sensor signals take the form of analog DC voltages, but can also be analog pulse width modulated.

One of the sensor coils Li or individual components of the transmitter 19 may fail under certain circumstances. In this case, the invention provides a remedy. The damping surfaces 9 and 9 ' of the actuating element 7 lie on the one hand opposite, ie the actuating surface 9 will be on top of the circuit board 3 moved and the actuating surface 9 ' is moved to the bottom of the circuit board (like 13 shows). By this arrangement in two levels, the mechanical tolerances, the distance changes of the Bedämpfungsflächen 9 . 9 ' lead, be compensated.

On the other hand shows 12 a displacement of the Bedämpfungsflächen 9 . 9 ' in the railway direction. The position of the double executed actuator 7 is mediated by calculation. Because each sensor signal is measured analogously, intermediate positions with high resolution can also be detected. Due to the fact that two staggered damping elements 9 . 9 ' can be used, even with failure of a sensor coil or the associated electronic components, the position can still be determined with sufficient accuracy. If, for example, the damping surface 9 encounters a failed sensor coil, then experiences an intact sensor coil maximum attenuation by the remaining Bedämpfungsfläche 9 ' ,

In the embodiment according to 14 comes in comparison to 12 a third staggered damping surface 9 '' on the actuator 7 added. The result is an arrangement with two Bedämpfungsflächen 9 and 9 '' in a plane and an opposite damping surface 9 ' , The algorithms for determining the web position x (see, for example, in 10 ) are sufficiently sharp enough to calculate the desired path position x from patchy sensor signals.

15 shows opposite 14 two modifications that can be made individually or together.

Three staggered damping surfaces 9 . 10 and 9 '' lie in a plane on top of the actuator 7 , This arrangement is advantageous if the distance tolerances did not matter len or if the bottom of the circuit board 3 should remain free.

Furthermore, in 15 the sensor coils Li lined up in a circular arc and the actuator 7 becomes a rotation axis 23 pivotally guided over the sensor coils Li. With this feature, the described redundant sensor principle is also suitable for angle measurements. In 15 a circle segment can be detected; However, it is also a full turn of the actuator 7 possible. Exemplary applications in the vehicle sector are an angle measurement of the seat back position or the accelerator pedal.

In 15 is the actuator 7 according to the arc arrangement of the coil Li swings and carries diamond-shaped Bedämpfungsflächen 9 . 10 , For larger bends better results are obtained with round or circular damping surfaces, ie better intermeshing damping curves.

For linear movements, the actuator 7 conductive damping surfaces 9 on, which are conveniently rhombic. Each diamond-shaped cushioning surface 9 preferably has a length in the web direction, are damped by the three coils Li simultaneously (see. 8th ). For example, the attenuation range of the fourth coil L4 adjoins the attenuation range of the first coil L1. In addition, the width dimension of the rhombus is adjusted so that the attenuation curve of a coil closely resembles a parabola. Due to the resulting superposition of three parabolas per rhombus, the computational interpolation towards a fictional parabola, whose vertex lies at the x-sign of the rhombus, is supported.

If two rhombuses 9 . 10 offset in the web direction, for example by the distance of two coils L8 and L10, the damping effect extends over five coils. Then the quadratic interpolation according to 10 are based on five measured values, so that the failure of a coil measured value can not only be reliably detected, but can also be bridged by the program.

All the design features and features of the invention can be realized with a series of Hall sensors instead of a series of sensor coils Li. The actuator 7 carries in this case bases 9 made of permanent magnetic material and the evaluation electronics 19 is suitable in this case in a known manner for processing the Hall sensor signals. Under the permanent-magnetic actuator is both a movable permanent magnet and a magnetic shielding to understand, which is guided by the field of a fixed permanent magnet.

In a known electronic selector lever module are currently 20 Hall sensors used, each switching position is double detected for safety reasons. With the principle of the offset actuator, the number of Hall sensors on 10 , in the worst case 12 to be reduced. Although the sensor positions are simply occupied, an adjacent sensor receives a maximum signal due to the offset surface 9 ' , Since the sensors make up a considerable part of the system costs, the solution according to the invention leads to a significant cost saving.

L

inductive sensor

L '

opposed inductive sensor

L1

first inductive sensor

Li

i.induktiver sensor

i

coils Index

a

distance

x

milestone of the center of gravity

1

inductive sensor unit

3

circuit board

5

microcontroller

7

conductive actuator

9,9 ', 9' '

diamond-shaped base surfaces, damping surfaces

10

offset Bedämpfungsfläche

11

sinusoidal oscillator

13

Current amplifier and Current-voltage converter

15

RF rectifier

17

multiplexer

19

evaluation

21

interface

23

axis of rotation

Claims (19)

Inductive sensor unit ( 1 ), for example, for a position detection of a vehicle seat, - with a plurality of sensor coils (L1 ... Li), the planar on a printed circuit board ( 3 ) are applied, - with a conductive actuator ( 7 ), which is spaced (a) on a path over the sensor coils (L1 ... Li) is guided, - and with an electrical evaluation circuit ( 5 . 11 - 17 ; 19 ), the inductance changes of the sensor coils (L1 ... Li) corresponding to a track position (x) of the actuator ( 7 ) and converted into electrical signals, in particular in sitting position signals, characterized in that - the actuating element ( 7 ) with conductive base surfaces offset in the direction of the track ( 9 . 9 ' . 9 '' . 10 ) is guided over the sensor coils (L1 ... Li). Inductive sensor unit ( 1 ) according to claim 1, characterized in that the conductive actuating element ( 7 ) bifurcated with two mutually spaced bases ( 9 . 9 ' ) the printed circuit board ( 3 ) overlaps. Inductive sensor unit ( 1 ) according to claim 2, characterized in that the conductive actuating element ( 7 ) with another base ( 9 '' ) bifurcated the circuit board ( 3 ) overlaps. Inductive sensor unit ( 1 ) according to claim 1, characterized in that the conductive actuating element ( 7 ) with two ( 9 . 10 ) or three ( 9 . 10 . 9 '' ) one-sided spaced bases over the printed circuit board ( 3 ) to be led. Inductive sensor unit ( 1 ) according to one of the preceding claims, characterized in that the conductive actuating element ( 7 ) on one side or on both sides of the circuit board ( 3 ) diamond-shaped bases ( 9 . 9 ' . 9 '' . 10 ) having. Inductive sensor unit ( 1 ) according to one of the preceding claims, characterized in that the printed circuit board ( 3 ) with the planar applied sensor coils (L1 ... Li) is flat. Inductive sensor unit ( 1 ) according to one of claims 1 to 5, characterized in that the printed circuit board ( 3 ) is curved with the planar applied sensor coils (L1 ... Li). Inductive sensor unit ( 1 ) according to one of the preceding claims, characterized in that the plurality of sensor coils (L1 ... Li) linearly on the circuit board ( 3 ) is strung and the actuator ( 7 ) is guided over the sensor coils (L1 ... Li) for path measurement on a straight path. Inductive sensor unit ( 1 ) according to one of claims 1 to 7, characterized in that the plurality of sensor coils (L1 ... Li) circular arc on the circuit board ( 3 ) is strung and the actuator ( 7 ) for the purpose of measuring the angle about an axis of rotation ( 23 ) is pivotally guided over the sensor coils (L1 ... Li). Inductive sensor unit ( 1 ) according to one of the preceding claims 1 to 8, characterized in that the plurality of planar sensor coils (L1 ... Li) on one side (sensor L) of the printed circuit board ( 3 ) (Figure 11a). Inductive sensor unit ( 1 ) according to one of the preceding claims, characterized in that the plurality of planar sensor coils (L1 ... Li) on the other side (L ') of the printed circuit board ( 3 ) (Figures 11b and 11c). Inductive sensor unit ( 1 ) according to claim 11, characterized in that two sensor coils (L, L ') located on the two sides of the printed circuit board ( 3 ) are planar, are connected in series (Figures 6 and 11b). Inductive sensor unit ( 1 ) according to claim 11, characterized in that the measuring signals of two sensor coils (L, L ') located on the two sides of the printed circuit board ( 3 ) are planar opposite, in the evaluation circuit ( 5 . 11 - 17 ) (Figure 11 c). Inductive sensor unit ( 1 ) according to one of the preceding claims, characterized in that the electrical evaluation circuit ( 19 ) comprises one or more resonant circuits whose resonant frequency is determined by the inductance of the sensor coils (L1 ... Li). Inductive sensor unit ( 1 ) according to claim 1 to 13, characterized in that the electrical evaluation circuit ( 5 . 11 - 17 ) a Reaktanzmessung the sensor coils (L1 ... Li) at Stromeinprägung ( 11 . 13 ). Inductive sensor unit ( 1 ) according to claim 1 to 13, characterized in that the electrical evaluation circuit ( 19 ) comprises a Reaktanzmessung the sensor coils (L1 ... Li) at voltage impressions. Hall sensor unit ( 1 ), for example, for a position detection of a vehicle seat, - with a plurality of Hall sensors mounted on a printed circuit board ( 3 ) are applied, with a permanent magnetic actuator ( 7 ), which is spaced (a) guided on a path over the Hall sensors, - and with an electrical evaluation circuit ( 19 ), the signal changes of the Hall sensors according to a track position (x) of the actuating element ( 7 ) and converted into electrical signals, in particular in sitting position signals, characterized in that the permanent magnetic actuator ( 7 ) spaced on both sides (9, 9 ') and / or with offset in the direction of the web bases ( 9 . 9 ' . 9 '' . 10 ) is passed over the Hall sensors. Hall sensor unit ( 1 ) according to claim 17, characterized in that the plurality of Hall sensors on both sides of the printed circuit board ( 3 ) is applied. Hall sensor unit ( 1 ) according to claim 17 or 18, characterized in that the electrical evaluation circuit ( 19 ) detects the signals of all Hall sensors and by means of an algorithm in a current track position (x) of the Betätigungsele ment ( 7 ).