WO2003081175A1

WO2003081175A1 - Tilt sensor

Info

Publication number: WO2003081175A1
Application number: PCT/EP2003/002975
Authority: WO
Inventors: Heinz KÜCK; Daniel Warkentin; Daniel Benz
Original assignee: Hahn-Schickard-Gesellschaft für angewandte Forschung e.V.
Priority date: 2002-03-22
Filing date: 2003-03-21
Publication date: 2003-10-02
Also published as: DE10261961A1

Abstract

The invention relates to a tilt sensor comprising a path (20) made of an injection molded polymer plastic, an element (10) movable along said path, wherein a position of the movable element (10) along said path (20) is dependent upon a tilt of the path relative to a reference position. The tilt sensor also comprises a detection device (50) for detecting the position of the movable element (10) along the path (20) and/or a temporary change of the position of the movable element (10) along said path (20). This tilt sensor structure can be produced economically and provides flexibility in the use thereof.

Description

tilt sensor

description

The present invention relates to tilt sensors, and more particularly to inexpensive tilt sensors for a variety of applications.

In general, inclination sensors can be used for a variety of household, industrial and research applications. Examples of this are rollover sensors in motor vehicles, monitoring sensors for alarm systems in vehicles and buildings, position sensors for automated machines, irons, washing machines etc. Tilt sensors are known in the prior art, the mode of operation of which is based on various principles. For example, inclination sensors are known in order to carry out a capacitance measurement in the event of a change due to inclination.

DE 35 45 630 C2 describes, for example, an acceleration and inclination sensor in which a magnetic material is arranged on a flat surface which is divided into four capacitor plate sectors, the magnetic material no longer lying in the middle of the flat surface depending on the inclination, but shifts and deforms in the direction of the incline, so that capacitance changes occur, which are formed by two of the four capacitor plates.

DE 41 06 932 AI discloses an inclination sensor with an asymmetrical ro- gate, which always remains parallel to gravity, while a housing in which the rotor is suspended rotates at an incline. The position shift of the rotor to capacitor electrodes on the housing provides a measure of the inclination of the inclination sensor.

Additional inclination sensors carry out a capacitance measurement when there is a change in an area covered by a dielectric.

There are also inclination sensors which carry out thermal detection of the inclination by means of a temperature difference (convection) which arises when the inclination is tilted. Other inclination sensors, in turn, measure the inclination-dependent conductivity of a liquid with its height variation. This principle is also referred to as the conductometric principle.

Still other inclination sensors detect a tilt by measuring a mechanical tension resulting therefrom. This principle is also called the piezoresistive principle.

Still other inclination sensors carry out an optical measurement of the inclination by refraction or reflection at interfaces.

Finally, there are also inclination sensors which carry out an inclination measurement by changing the inductance of a coil when the position of a ferrofluid changes. Although some inclination sensors provide very precise measured values, they are sometimes too expensive for a wide range of use and too complicated to set up.

DE 1790620 Ul shows an inclination sensor with a metal ball that runs on a curved path. The curved track is provided on the one hand with a resistance layer and on the other hand with a contact rail. The metal ball can also be replaced by a drop of mercury. The position of the metal ball or the drop of mercury is measured with a detection circuit of the bridge circuit type based on the ohmic resistance between the resistance layer and the contact bar.

DE 8806850 Ul discloses a passive electrical component for obtaining an inclination-dependent ohmic resistance value. In particular, ohmic resistance layers are arranged along a curved path, on which there is a movable electrical contact in the form of a drop of mercury. Depending on the position, an electrical bridge is formed between the two ohmic resistance layers.

DE 4238930 AI discloses a position change sensor integrated in a printed circuit board. In particular, a disk-shaped movement space is provided for the ball, into which various electrodes protrude. Depending on a change in position of the sensor, the ball moves to a different location in the disk-shaped movement space due to gravity and therefore short-circuits a different pair of electrodes than before the change in position. DE 4114992 C1 discloses an acceleration and inclination sensor which consists of a cavity which is formed in a conical shape in the sensor housing with the tip pointing downward, with contact pieces arranged on the interior surfaces of the cavity, and a contact body which is positioned in the cavity according to the inclination of the sensor housing.

DE 4031344 AI discloses an electronic inclination measuring device with a ceramic substrate on which three electrodes are shown in a comb-like engagement situation. Furthermore, a vessel with a liquid is shown, in which an electrode is partially immersed. The liquid can be an electrical conductor or a dielectric, different liquid levels leading to different electrical properties of the comb-like interdigitated electrode pairs.

The object of the present invention is to provide an inexpensive and simple inclination sensor.

This object is achieved by an inclination sensor according to claim 1.

The present invention is based on the knowledge that an inclination sensor with a path along which a movable element can move depending on the inclination of the inclination sensor and with a detection device for detecting the position of the movable element along the path and / or a change over time the position of the movable element along the track is inexpensive to manufacture and simple to assemble. As a movable element, a rolling element, such as. B. used a ball or a cylinder, its position on the curved path indicates the tilt of the sensor to the gravitational field with respect to an axis. It is further preferred to determine the position either capacitively or galvanically using an electrode structure.

According to a preferred embodiment, the path is designed as a curved path. However, the same effect can also be achieved by a straight track and a curved rolling element or by both the track and the rolling element having curved surfaces.

The tilt sensor principle according to the invention is advantageous in that it can be easily constructed from a few components. Due to this uncomplicated sensor design, the inclination sensor according to the invention can be flexibly scaled for any application. In this way, larger inclination sensors can be produced in order to detect the inclination of larger objects, or else small inclination sensors to detect the inclination of smaller objects.

Another advantage of the present invention is that the curved path can be carried out inexpensively in plastic, and that standardized and inexpensive plastic injection molding production processes in particular can be used without further ado.

Another advantage of the present invention is that no temperature compensation device is required for the inclination sensor according to the invention. Another advantage of the present invention is that the inclination sensor is independent of changes in the amount of gravitational acceleration.

Preferred embodiments of the present invention are explained in detail below with reference to the accompanying drawings. Show it:

1 shows a three-dimensional schematic view of an inclination sensor according to a preferred exemplary embodiment of the present invention;

2 shows a schematic illustration to explain the achievable resolution of an inclination sensor with an incremental electrode arrangement;

3 shows a schematic illustration of an electrode arrangement for detecting the inclination of the inclination sensor and also the direction of inclination;

4 shows a basic circuit diagram of evaluation electronics;

5 shows an alternative exemplary embodiment of an electrode arrangement for absolute inclination measurement;

6 shows a basic circuit diagram for measuring the inclination as an analog output signal;

7 shows a schematic basic illustration for the arrangement of two conductor structures, which are formed by means of a

Liquid film are electrically connected, the resistance changes depending on the inclination; 8 shows a schematic illustration of a tilt sensor with an electrode arrangement for capacitive tilt detection; and

Fig. 9 shows a preferred embodiment of line electrodes and reference electrodes which can be arranged in repeating groups in the path of the movable element.

1 shows an inclination sensor according to the invention in accordance with a preferred exemplary embodiment. The inclination sensor according to the invention comprises a movable element 10 in the form of a rolling element. The rolling element 10 is accommodated in a curved path 20, the curved path 20 having a radius of curvature with respect to an inclination axis 12. The curved path 20 is accommodated in a housing which has an upper housing part 30 and a lower housing part 40. Alternatively, the sensor can also be designed such that the housing is constructed from one or more side parts.

1 also shows a detection device 50 which is designed to detect the position of the movable element along the path and / or to change the position of the movable element along the path over time.

In a preferred embodiment of the present invention, in which the housing, which consists of the upper housing part 30 and the lower housing part 40, is formed from plastic and in particular from polymer plastic, both the upper housing part 30 and the lower housing part 40 being plastic injection molded parts. In the embodiment shown in Fig. 1, the movable element is shown as a rolling element and in particular as a ball. Matching the ball, the curved path is designed as a groove, the cross section of which is shown at 14. The upper housing part 30 and the lower housing part 40 are preferably designed such that half of the groove is formed in one housing part, in such a way that the assembly is simple since the movable element can simply be placed in the lower housing part and then to place the upper part of the housing on the lower part of the housing together with the gutter. Alternatively, however, the channel can also be provided entirely in a housing part, the movable element, such as. B. a ball can be inserted laterally into the channel, after which the insertion opening can be closed by means of a plug for operation of the inclination sensor.

Although the curved track 20 is shown as a gutter in FIG. 1, this is not necessarily the case. The curved path could also simply be a curved flat surface on which the ball can move depending on the inclination, but on which there is also a cylindrical rolling element or even a drop of a conductive liquid with a high surface tension, such as e.g. B. mercury could move.

It should also be pointed out that there is not necessarily a spherical rolling element in the channel 20 of FIG. 1, but that a cylindrical body can also be provided which does not roll along the channel, but rather because of the channel gravity is pushed back and forth. Furthermore, the gutter can be carried out that any rotationally symmetrical body can roll in it. Other rolling elements that are not rotationally symmetrical, such as, for. B. a rolling element with a curved surface, which is in the form of a segment of a circle in cross section and with its curved surface can roll back and forth on the track over a limited area.

The electrode arrangement 50 in FIG. 1 is schematically outlined as parallel individual electrodes. In the simplest embodiment, voltage can always be applied to two adjacent individual electrodes, and the rolling element is made of a conductive material or has a conductive surface, so that, depending on its position, two adjacent electrodes are short-circuited in such a way that the position of the rolling element can be determined by a current flow through two adjacent electrodes.

In this case, the individual electrodes, a cross section of which is shown schematically in FIG. 2, are applied in the guide trough which has a curved surface which has a direct influence on the resolution and the measuring range of the sensor. As shown in FIG. 2, the curvature is represented by a _path radius r _path .

In general, the electrode structure 50 can be designed in such a way that individual electrodes are arranged inside the channel. Depending on the arrangement of the electrodes, different sensor principles can be implemented. B. an incremental counting of the short circuits to detect the position of the movable element along the path, a measurement of the times between the short circuits by one to record a change in the position of the movable element along the track over time, a measurement of the change in resistance via the short circuit, or a measurement of the change in capacitance due to a displacement of the rolling element along the track.

It is further preferred to set a damping of the movable element with a fluid introduced into the channel in order to positively influence the sensor characteristic. In principle, a liquid or a gas under pressure can be used here.

In the simple electrode structure variant shown in FIG. 1, which enables incremental detection, the individual electrodes of the electrode arrangement 50 are arranged in such a way that when the rolling element 10 takes on the lowest possible position within the groove 20 due to gravity in the earth's magnetic field, two electrodes lying in the groove are electrically connected by the rolling element. An electrical current can thus flow through this connection, which is detected by suitable electronics, as is shown, for example, in FIG. 4. If the distance between two adjacent electrodes is known, the respective inclination of the sensor can thus be determined by counting the short-circuit current pulses.

If, as shown in FIG. 2, the inclination sensor is designed as an incremental sensor, this means that a single current pulse corresponds to the minimum detectable angle, which is determined by the structural distances between the electrodes and the radius r _{path of} the channel. The minimum angle is as follows: c _ml "= 2 ^• arcsini

V ^ ^'r Bahπ J

In the above equation, Sπά _{n is} the pitch of the electrode structure produced. s _min is measured as the distance between the centers between two individual electrodes of the electrode arrangement 50.

In the following, reference is made to FIG. 3 in order to present an alternative electrode arrangement with which both the direction of inclination and the rest position of a rolling element 20 can be detected. In particular, the electrode arrangement comprises a central electrode 51, which extends along the curved path and only at a rest position 60, which the rolling element 20 assumes when no inclination is applied, is interrupted by a reference electrode 52 and is located on the other side of the Rest position 60 extends continuously in the channel.

The electrode arrangement further comprises a first comb-like electrode arrangement 53 and a second comb-like electrode arrangement 54, the first comb-like electrode arrangement 53 being also referred to as L2, while the second comb-like electrode arrangement 54 is also referred to as L3.

The single electrodes extending across the curved path 20, with the curved path along the electrode

51 is aligned with respect to the individual electrodes of the other comb electrode so that an offset x e- xist, which is between 0 and 0.5 Smin. It is thus possible to determine on the basis of the chronological sequence of a short circuit between L1 and L3 or between L1 and L2 whether the ball 20 moves to the left or to the right with reference to FIG. 3.

If the ball moves to the right, there will be a short circuit between line L1 and line L3. After a short period of time there will be a short circuit between Ll and L2. If the ball continues to move, a short circuit between L1 and L3 will occur again after a long time. When moving to the right, the time span between two short circuits of line L1 and line L3 or L2 is therefore shorter than a short circuit between line Ll and L3 and line Ll and L2.

If, on the other hand, the ball moves to the left with respect to FIG. 3, there will be a short circuit between lines L1 and L2 and then, after a short period of time, there will be a short circuit between lines L1 and L3. The time interval between a short circuit of lines L1 and L2 and a short circuit between lines L1 and L3 is thus longer than the time interval between short circuits of the respective other lines.

The processor unit shown in FIG. 4 comprises inputs 62 for lines 51, 52, 53 and 54, a counter 63 for counting the short circuits, preferably between line L1 and either line L2 or line L3, in order to determine the absolute position, and an arithmetic unit 64 and a memory 65 in order to carry out the described algorithm for determining the direction of the ball. As shown in FIG. 3, the reference line 52 is also present, with a short circuit in which the reference line 52 is involved, such as. z. B. A short circuit between line 52 and line 53 indicates that the ball is in its reference position, which is, for example, a horizontal state of the tilt sensor of FIG. 1, in which the ball is positioned in the "valley" of the curved path.

It should be noted that the reference electrode 52 of FIG. 3 can also be used for sensor calibration. The reference electrode 52, which is installed in a precisely defined position in the inclination sensor, is used to calibrate the sensor zero point during operation. In the event of a pulse through this electrode, the measured value can thus be reset by the electronics of FIG. 4.

The electronics evaluate the current pulses in several steps. The counter 63 first registers the incoming pulses. Each pulse corresponds to the given by the dimensioning of the sensor size and the line width of the electrode result incremental angle O _m i _n, which is shown in Fig. 2. For each pulse measured, the total measured value is therefore adapted in accordance with the direction of inclination, ie incremented or decremented. The direction of inclination, as has been stated, is determined by the electronics recognizing the sequence of the conductor tracks contacted and thus determining the direction of the inclination on the basis of the algorithm stored in the memory. It should be noted that malfunctions can occur continuously during operation, such as. B. a power failure of the electronics, a skipping of impulses due to strong vibrations etc. It is therefore preferred to read out at least the reference electrode 52 which, when contacted, causes the current measured value to be compared with the value stored in the memory and, if there is a deviation, accordingly is corrected.

In a preferred embodiment, the processor system described can be, for example, a high-frequency clocked microprocessor to which the electrodes are connected individually. To reduce the number of connections, the electrodes can be combined into suitable groups, as shown for example in FIG. 9. Thus, FIG. 9 shows a first group of so-called line electrodes L1, L2, L3, L4, which extend over the web and which intermesh with reference electrodes L _Ref ι, L _ef2 , L _Ref3 and L _Ref4 . Such groups of line electrodes L1 to L4 and reference electrodes L _Re n to L _Ref4 can be arranged one after the other in order to fill up an entire path of a movable element.

In particular, the arrangement of the line electrodes and the reference electrodes is such that always with reference to a

Short circuit between a lead electrode and a reference electrode can be determined where the movable element is within a group. If, for example, there is a short circuit between the reference electrode L _Ref ι and the line electrode L4, it is immediately known that the movable element, such as a ball that short-circuits the two electrodes mentioned, is arranged at the top in FIG. 9, since only on this Position a short circuit between the first reference electrode and the fourth lead electrode is possible. If, on the other hand, it is found that there is a short circuit between, for example, the third reference electrode L _Ref3 and the third line electrode, it is also known exactly where the ball is, since this short circuit is only possible at a specific position along the path shown in FIG ,

In general, therefore, a group of line electrodes and reference electrodes is arranged so that they engage in one another in such a way that the absolute position of the ball within a group of line electrodes and reference electrodes can be precisely determined on the basis of a short circuit between a specific line electrode and a specific reference electrode.

Typically, the distance covered by the interlocking line electrodes and reference electrodes from FIG. 9, that is to say the distance from the lowest line electrode L1 to the uppermost reference electrode L _Ref i _{/, will} not be large enough to equip a complete inclination sensor. For longer trajectories, it is therefore preferred to arrange the group shown in FIG. 9 several times in succession, and to connect each of the first power electrodes, all second lead electrodes, all third lead electrodes and all fourth lead electrodes to the individual groups arranged in the trajectory of the movable element connect, and at the same time to connect the reference electrodes of the individual groups and the corresponding valency. The position of the ball, for example in the path of movement, is then determined by firstly detecting between which reference electrode and which line electrode there is a short circuit. If in this case many groups are arranged along the movement path, it is initially only known at which position within a group the ball is located. However, it is not yet known in which of the different groups the ball is located. However, this information can easily be obtained from the fact that previous position information of the ball is taken into account if it is also taken into account that the ball cannot, for example, jump over a complete group of lead electrodes and interlocking reference electrodes, but that it can, if at all, at most one skipped a few electrodes within a group. Therefore, if the short-circuit situation of the ball is monitored while the ball is rolling from one group to another group, a complete "group sweep" of the ball will be detected, so that it is easily possible due to this "history information", not just the position a sphere within a group, but also to determine the actual group in which the sphere is located.

The arrangement of intermeshing electrodes shown in FIG. 9, which can be read out selectively, thus represents, as it were, a mixed absolute / relative sensor. If, for example, the exemplary embodiment of the invention shown in FIG. 3 is considered, in which the ball, for example, is set up of the continuous electrode L1 rolls and whenever it also touches a partial electrode of the other line electrode L2, it generates a short circuit, so starting from an "original reference point" which is determined for example by the reference electrode 52, always based on the number of short circuits that a ball had triggered while it was rolling from one rest point to the next rest point, and the original reference information, a current position of the ball can be determined without the need for pure absolute information become. The same situation could be obtained if the ball does not run on the electrode 51, but if the electrode Ll is designed in exactly the same way as the electrode L2, and partial electrodes of the electrode L1 extend into spaces between partial electrodes of the electrode L2. This would be the case if all reference electrodes in FIG. 9 and all lead electrodes in FIG. 9 were short-circuited to one another. Even then, only a relative sensor would be created, in which a reference starting point is required to determine the absolute position of the ball along the track and thus to determine the inclination, which on the one hand can be generated directly by a reference electrode as shown in FIG. 3, or which also determines the position can be from the previous measurement.

In this case, that is, when all line electrodes are connected to one another and all reference electrodes in FIG. 9 are connected to one another, the case discussed in FIG. 3 arises. The microprocessor that is shown in FIG. 4 would then only have one line connection L 1 and one line connection LRef, and a position determination would take place based on the counting of the short circuits between the line L1 and the line LRef, whereby the history is still required, i.e. the position of the movable element in the path before the current change in inclination or the previous inclination before the change current inclination. In the case of FIG. 9, the wiring complexity increases since now four line electrodes L1 to L4 and four reference electrodes have to be read out selectively in order to always determine where the short circuit is in a group. The selection of the group again takes place on the basis of a history value, and if the ball moves over several groups during a change in inclination, the sequence of the short circuits between the line and reference electrodes can be evaluated, for example by counting, to determine how many groups the ball has moved based on the number of short circuits counted.

At this point it should be pointed out that the number of line electrodes can be as large as desired. It should also be pointed out that the number of reference electrodes can also be arbitrary, the number of line electrodes and the number of reference electrodes need not necessarily be the same. In any case, a number of at least two line electrodes and a number of at least two reference electrodes are required for a hybrid sensor, that is to say for a mixed absolute / relative determination, which are arranged such that at every position of the movable element within the Group is always shorted another pair of a lead electrode and a reference electrode.

This embodiment has the disadvantage, on the one hand, that more electrodes have to be evaluated, but has the advantage of greater robustness compared to a jumping of the ball on the track, in that a ball passes through two electrodes, but does not trigger a short-circuit situation when it is jumping. So it turned out emphasized that the distance a ball jumps is always relatively limited. If, therefore, the area of the track covered by a group is larger than the average "jumping distance" of the ball, reliable inclination detection can be carried out easily even under harsh environmental conditions.

In the following, reference is made to an absolute inclination sensor with reference to FIG. 5. The inclination sensor corresponds to the previously described inclination sensor with regard to the characteristics of the curved path and the movable element. However, the electrode arrangement shown in FIG. 5 is preferred as the detection device. The electrode arrangement again comprises a first electrode 51 'which, for. B. has a meandering shape as shown in FIG. 5, and a second electrode 53 ', which also has an example of a meandering shape as shown in FIG. 5. Both electrodes L1, L2 have partial electrodes projecting into the curved path 20, the movable element 10 always short-circuiting between two successive partial electrodes of L1 and L2. The rolling element 10 thus contacts two adjacent electrodes, which run transversely to the track 20. Here, as shown in FIG. 5, the supplying conductor tracks are arranged in such a way that the total length of the supplying and discharging conductor tracks becomes longer by a certain amount Δl for a subsequent contact. A suitable arrangement is, for example, the meandering shape shown in FIG. 5. The inclination of the sensor housing and the resulting change in position of the movable element 10 thus allow the resistance or the change in resistance of the conductor to be measured and the absolute position of the rolling element to be determined due to the change in the length of the conductors contacted. This Relationship is shown by the following equation:

A p

In the above equation, R is _Le i _t e _{r is} the resistance of the contacted conductor, p is the resistivity of the conductor material. 1 is the length of the conductor track and A is the cross section of the conductor track.

To achieve a continuous analog inclination signal, an electrode structure can also be used in which the sensor contacts both conductor tracks continuously at the same time. 6, the first conductor 51 ″ and the second conductor 53 ″ are both arranged on the curved path 20, for example running parallel to one another at the bottom of the curved path or running parallel to one another laterally on the curved path, in any case in this way that the movable element is in constant contact with the two conductors Ll and L2. The change in resistance of the circuit consisting of L1, L2 and the movable element 10 or the absolute resistance of this circuit again determines the position, which can be converted into an inclination angle α, for example using a table or an analytical function. The equation given above in connection with FIG. 5 can also be applied to the exemplary embodiment of the detection device shown in FIG. 6. In addition to the simultaneous contacting of both conductor tracks, there can also be permanent contact with only one conductor track, the contacting of the second conductor track, which typically runs at an angle to the first conductor track, can consist of a liquid which is introduced into the housing and which does not provide contact between the ball and the second Conductor bridged with high resistance. For this purpose, reference is made to FIG. 7. It should be noted that the arrangement shown in Fig. 7 is only schematic. Depending on the application, it is preferred in FIG. 7 that either the first conductor track L1 or the second conductor track L2 is insulated in a region 68, so that the current flow mainly over the rolling element 10 and over the region of the liquid which is between the rolling element per 10 and the second conductor track is taking place. The contacting of the second conductor track L2, which runs obliquely to the first conductor track L2, thus takes place via the liquid introduced into the housing of the inclination sensor, which bridges the non-existent contact between the ball and the second conductor structure with high resistance. As a result, the resulting resistance, which is mainly dependent on the distance between the rolling element 10 and the second conductor track L2, is used to detect the inclination. Expressed in equal terms, this is:

In the above equation, the total resistance R _{ges is} the resistance that results from the series connection of the inclination-dependent resistors R _L i _ter and R _f iu _s sig. In contrast to the other exemplary embodiments, FIG. 8 shows a detection device which works on a capacitive detection principle. In particular, a cross section through a curved web 20 is shown, a first electrode 80 being attached to the bottom of the web, while second electrodes 81, 82 are arranged at lateral boundaries of the web 20. If the movable element 10, which is shown in FIG. 8 as a sphere, is conductive, a capacitance is formed between the first electrode 80 and the sphere 10 as the first capacitor electrode and the electrode 82 as the second capacitor electrode. For incremental detection, as seen along the path, the second electrode 82 is designed as a plurality of discrete sub-electrodes insulated from one another, so that when the ball moves past a sub-electrode there is an increase in capacitance which results in a Decreases in capacity when the ball moves away from the electrode 82 again. It should be noted that it is not absolutely necessary for the rolling element 10 to be electrically conductive. Is the same formed from a dielectric that has a different dielectric constant to the surrounding medium, such as. B. air or an insulating liquid, there will also be a capacity increase or decrease.

Alternatively, it is preferred to realize capacitive detection in that an electrode structure attached to the web is covered by a dielectric. An electrode structure is applied to the rolling element essentially transversely to its rolling direction. The bottom electrodes are designed in such a way that there are opposite electrode fingers arranged transversely to the rolling direction. Due to the inclination-dependent movement of the rolling element The electrode fingers isolated by the dielectric are then detected on the basis of the maximum and maximum capacitance and the inclination of the housing. In particular, there is a maximum if the rolling element is arranged directly above the fingers. On the other hand, there is a minimum if the body is arranged between two adjacent pairs of fingers, the rolling element not influencing the dielectric between the opposing fingers.

At this point it should also be pointed out that the arrangement shown in FIG. 8 can also be used as an alternative if the ball 10 moves along a direction which is represented by an arrow 83. If the ball 10 moves to the left, the capacitance between the ball and the left electrode 82 will increase, while the capacitance between the ball and the right electrode 81 will decrease. If, on the other hand, the ball moves to the right, the capacitance between the electrode 82 and the ball 10 will decrease, while the capacitance between the ball 10 and the right electrode 81 will increase. In this case, it is preferred to use differential detection to achieve higher sensitivity.

It should be noted that in all the exemplary embodiments described above, in addition to measuring the incoming signals, the times of their changes can also be measured and evaluated, thereby increasing the sensor resolution and in particular also detecting the change in the position of the movable element along the path over time to reach. In a preferred embodiment, the time signal is measured in addition to the path signal using a suitable circuit the location and the course of movement of the rolling element are reconstructed. As a result, a higher resolution than would be possible using the measured signals alone can also be achieved by means of interpolation, ie by means of tracking and predicting the movement path.

As an independent check of the sensor during operation, the element 10 can be moved briefly out of its current position by means of energy coupling via the detection device. Appropriate electronics then monitor the reaction of the element 10 by means of the detection device. If the reaction of the element 10 matches an expected reaction, the sensor is functional. However, if there is a deviation from the expected target value, the electronics can conclude that the sensor is malfunctioning.

Finally, it should be pointed out that the inclination sensor can also be designed in such a way that inclinations with respect to a second inclination axis are measured simultaneously with inclinations with respect to a first inclination axis. For this, it is necessary that the groove, as the curved track in the embodiment shown in FIG. 1, is modified into a two-dimensionally curved plane, and that a further wiring structure in the form of further electrode structures is realized along the plane , so that the movable element 10 can not only move about the inclination axis 12, but also can move about a second inclination axis perpendicular to the inclination axis 12. The position of the movable element with respect to the curved path in the form of a two-dimensional curved surface can then be determined by means of the further electrode structure.

Claims

claims

1. Tilt sensor with the following. features:

a web (20) formed from an injection molded polymer plastic;

an element (10) movable along the path (20), a position of the movable element along the path (20) depending on an inclination of the path (20) with respect to a reference position (60); and

a detection device (L1, L2, L3, Lref) for detecting the position of the movable element along the path and / or a temporal change in the position of the movable element along the path.

2. inclination sensor according to claim 1,

wherein the sheet (20) is a curved sheet, the sheet is a straight sheet, and the movable member has a curved surface that engages the sheet, or both the sheet and a surface of the movable member , which is in engagement with the web, have different curvatures so that the element is movable depending on the inclination.

Tilt sensor according to claim 1 or 2,

in which the detection device is designed to detect the position or a change in the position of the movable element by means of an electrode arrangement (80, 81, 82) capacitively.

4. tilt sensor according to claim 3,

in which the detection device has the following features:

a first electrode (80) along the path on which the movable member is movable; and

at least one second electrode (81, 82) which is arranged such that the movable element does not touch it, the first and the at least one second electrode forming a capacitor.

5. Inclination sensor according to claim 3 or 4, in which the movable element (10) is wholly or partly conductive and, together with an electrode (80) of the electrode arrangement, forms a capacitor whose capacitance depends on a position of the movable element along the path ( 20) depends.

6. inclination sensor according to one of the preceding claims,

in which the movable element (10) is a rolling element or a drop of a liquid with a surface tension force which is selected such that the drop does not split up when moving along the track (20).

7. inclination sensor according to claim 6, in which the rolling element (10) has a plurality of electrodes arranged transversely to a rolling direction,

in which a dielectric is arranged on the electrodes, on which the rolling element is arranged, and

in which a movement of the rolling element can be detected by ascertaining capacitance maxima and capacitance minima between the electrodes.

8. inclination sensor according to claim 1 or 2,

in which the movable element (10) is wholly or partly electrically conductive, and

in which the detection device has the following features:

a first electrode arrangement (L1);

a second electrode arrangement (L2);

in that the movable element ^', the first and second electrode assembly shorting means for applying a voltage between the first and the second electrode arrangement, wherein the first and the second electrode arrangement are configured so depending on the position.

Tilt sensor according to claim 8, in which the first electrode arrangement (51 ') has a plurality of first partial electrodes extending transversely to the path;

in which the second electrode arrangement (51) is continuous; and

wherein the detection device further comprises a device for counting (63) short circuits between the first and the second electrode arrangement or for determining (64) a time between two short circuits.

10. inclination sensor according to claim 8,

in which the first electrode arrangement has a plurality of first sub-electrodes extending transversely to the path;

in which the second electrode arrangement has a plurality of second sub-electrodes extending transversely to the path, and

in which the detection device is designed to detect short circuits between the first electrode arrangement (51 ') and the second electrode arrangement (53').

11. Tilt sensor according to claim 8,

in which the first electrode arrangement has a plurality of first partial electrodes extending transversely to the path, in which the second electrode arrangement has a plurality of second partial electrodes extending transversely to the path,

two adjacent partial electrodes of the first and / or the second electrode arrangement being connected to one another in a meandering manner,

wherein the detection device is designed to determine a position of the movable element via an ohmic resistance between the first electrode arrangement and the second electrode arrangement.

12. Tilt sensor according to claim 9,

in which the detection device further comprises a third electrode arrangement (54) which has a plurality of third sub-electrodes extending transversely to the web, which is offset from the plurality of first sub-electrodes extending transversely to the web by less than half a sub-electrode width are,

so that an inclination direction can be determined whether a short circuit between the second electrode arrangement and the first electrode arrangement follows in time rather than a short circuit between the second electrode arrangement and the third electrode arrangement or not.

13. Tilt sensor according to claim 8, in which the detection device further comprises a third electrode arrangement (54) which has a plurality of third sub-electrodes extending transversely to the web, which are offset by half an electrode gap from the plurality of first sub-electrodes extending transversely to the web.

14. Tilt sensor according to claim 9,

in which a reference electrode (52) is also provided at the reference position (60) of the movable element (10), by means of which a signal can be output when the movable element is in the reference position (60).

15. inclination sensor according to claim 1,

in which the movable element (10) is electrically conductive,

in which a first electrode arrangement (51 '') is provided,

in which a second electrode arrangement (53 '') is provided;

wherein the first electrode arrangement and the second electrode arrangement are arranged in such a way that the movable element either contacts both electrode arrangements at the same time or only contacts one electrode arrangement and is in conductive contact with the other electrode arrangement via a conductive medium, and wherein a device for determining an ohmic resistance between the first and the second electrode arrangement is further provided, which depends on a position of the movable element (10).

16. Tilt sensor according to one of the preceding claims,

in which the track (20) is designed as a trough with lateral boundaries for the movable element (10) in order to detect an inclination according to an axis of inclination.

17. inclination sensor according to one of claims 1 to 12,

in which the path is designed to allow movement of the element along two different axes of inclination.

18. Tilt sensor according to one of the preceding claims,

in which a damping medium is arranged along the path in order to dampen a movement of the movable element (10).

19. inclination sensor according to one of the preceding claims,

- in which the movable element is completely or partially electrically conductive, in which the detection device has the following features:

a plurality of lead electrodes (L1, L2, L3, L4) extending across the track;

a plurality of reference electrodes (L _Ref i, L _Re f ₂ , L _Ref3 , L _re f ₄ ) extending over the path, the electrodes engaging in one another in such a way that a ball at one position short-circuits an electrode pair consisting of a lead electrode and a reference electrode and in another position short-circuits another line pair with a line electrode and a reference electrode, the line electrode and / or the reference electrode of the other line pair differing from the line electrode and / or the reference electrode of the one line pair; and

wherein the detection device is further designed to determine between which line pair there is a short circuit and to obtain inclination information on the basis of the determined line pair.

20. inclination sensor according to claim 19,

in which a plurality of groups of line electrodes and reference electrodes are arranged one after the other along the track, line electrodes of the same

Valence in all groups and reference electrodes of the same valence in all groups are connected to each other, and wherein the detection means is further configured to identify a group in which the movable element triggers a short, on the basis of a monitoring of short circuits which the movable element triggers when it moves along the path from one position to one next position moves, wherein the first position corresponds to a first inclination and wherein the second position corresponds to a second inclination.

21. Tilt sensor according to one of the preceding claims,

in which the detection device or the element (10) has electrodes which are selectively metallized on the plastic.

22. inclination sensor according to one of the preceding claims,

in which the movable element is made of plastic and has a metal material.

23. Tilt sensor according to one of the preceding claims, further comprising a device for causing a deflection of the element (10) and a monitoring device which is designed such that an actual deflection of the element caused by the device for causing with a predetermined target Deflection is compared to conclude that the inclination sensor is functional.

4. Tilt sensor according to one of the preceding claims, further comprising an electronic circuit integrated in a housing of the tilt sensor for determining the tilt.