MAGNETOSTRICTIVE POSITION SENSOR WITH DETECTOR COIL IN A CHIP

Abstract

To reduce the construction effort and also to make it smaller, the detector coil (6) is formed in the detector head (7) of a magnetostrictive position sensor (100) in a semiconductor chip (2), in which at the same time also the evaluation circuit (16) is formed and—if biased electrically and by means of direct current—also the then necessary separate bias coil (18).

Claims

1. A magnetostrictive position sensor (100) according to the time-of-flight principle of a mechanically-elastic density wave comprising: a waveguide unit (1) with a magnetoelastic waveguide (1a), a position-transmitting encoder magnet (21), which can be moved without contact, along the waveguide (1a) in its running direction (1′), a detector unit (15) arranged at a defined longitudinal position of the waveguide unit (1) with a detector coil (6) and an electronic evaluation circuit (16), characterized in that the detector coil (6) is formed in or on a semiconductor chip substrate (2), preferably the detector coil (6) comprises several (6a, b), or better only one flat coil.

2. The position sensor according to claim 1, characterized in that the electronic evaluation circuit (16) is formed in or on the same semiconductor substrate (2) as the detector coil (6), wherein the evaluation circuit (16) is arranged as close as possible, parallel to and spaced from, the coil plane (6″), to the detector coil (6).

3. The position sensor according to claim 1, characterized in that at least one bias coil is arranged in the semiconductor chip substrate (2), the axial direction of the bias coil is transverse to the waveguide direction, and the bias coil is arranged at a longitudinal position close to the detector unit.

4. The position sensor according to claim 1, characterized in that a bias magnet (4) is arranged on the detector unit, on the front side of the board (14) facing the waveguide, one bias magnet (4a, b) each is arranged on both sides of the waveguide (1) as viewed in plan view of the board (14).

5. The position sensor according to claim 1, characterized in that the width or thickness of a strip conductor in the semiconductor chip, in particular a winding of the detector coil (6), is less than 0.1 μm.

6. The position sensor according to claim 1, characterized in that the detector coil (6), in particular the semiconductor chip (2), is arranged at a distance from the magnetoelastic element to be scanned which is less than 200 μm, and the distance is ensured by an electrically non-conductive separating foil (13), in the form of a separating hose (13), placed therebetween, which surrounds the waveguide.

7. The position sensor according to claim 1, characterized in that the detector coil (6) consists of several sub-coils lying one above the other in parallel planes, or the detector coil (6) has at least 50 turns.

8. The position sensor according to claim 1, characterized in that the detector coil (6) has, in the top view of its coil plane (6″), a maximum diameter of at most 2 mm.

9. The position sensor according to claim 1, characterized in that the chip (2) has a maximum extension of not more than 2.5 mm in the top view of its main plane.

10. The position sensor according to claim 1, characterized in that the detector coil (6) is arranged with its coil plane (6″) parallel to the running direction of the waveguide (1a) or a villary tape attached to it.

11. The position sensor according to claim 1, characterized in that the semiconductor substrate (2) is silicon, or the semiconductor chip (2) is embodied and mounted as a bare chip.

12. The position sensor according to claim 1, characterized in that in the case of several part coils (5a, b), these are electrically connected in series.

13. The position sensor according to claim 1, characterized in that the semiconductor chip (2) is arranged on the rear side of a circuit board (14) facing away from the waveguide, with the outer side of the chip (2) nearest to the detector coil (6) facing the circuit board (14), or the board (14) is a flexible, semi-flexible or rigid board, or the semiconductor chip (2) is arranged at the opposite end of the board with respect to its electrical contact surfaces (17), in particular a connector arrangement (17), for forwarding the signals.

14. The position sensor according to claim 1, characterized in that the board (14) is a composite board consisting of two partial boards (14a, b) bonded to each other, wherein in at least one of the two partial boards (14a, b) there is a longitudinal groove in which the waveguide is arranged, wherein the semiconductor chip (2), is arranged on one of the outer sides of the printed circuit board composite.

15. The position sensor according to claim 1, characterized in that a base body (9), in which the waveguide (1a) is located, is fastened in the length region of the chip (2) on the front side of the board (14) opposite the chip (2), the base body (9) comprises two boundary bodies (8), extending in the main direction of extension (14′) of the board (14), with a waveguide channel (12) therebetween, in which the waveguide (1a) lies, a bridge plate (10) extending over the waveguide channel (12) and mechanically stabilizing the base body (9) is fastened to the sides of the two boundary bodies (8) facing away from the board (14).

16. The position sensor according to claim 1, characterized in that a bias magnet (4) is arranged on or in at least one boundary bodies (8) or the bridge plate (10).

17. A method of operating a position sensor according to claim 1, characterized in that the magnetically restrictive material, in particular the waveguide, is brought into a suitable magnetic operating point for measuring the position of the encoder magnet by means of electrical premagnetization, in that either alternating current is introduced into the detector coil (6) simultaneously with the measurement, the frequency of which is preferably higher than the frequency of the useful electrical signal to be expected during the measurement, or direct current is introduced into a separate bias coil, in particular the direct current is introduced into the detector coil with decoupling from the useful signal.

18. A method of making a position sensor according to claim 1, characterized in that the semiconductor chip (2) is produced using exposure masks with the extreme ultraviolet (EUV) method, or is produced without the use of exposure masks by a respective applied layer, for example of photoresist layer, selectively removed in certain areas by means of one or a plurality of high-energy beams simultaneously, in particular an electron beam, in particular by means of the electron beam lithography (EBL) method, or a photoresist layer is applied only in certain areas only in the area to be coated by means of an application nozzle.

Description

C) EXAMPLES OF EMBODIMENTS

[0069] Embodiments according to the invention are described in more detail below by way of examples, which are showing

[0070] FIG. 1a, b: a position sensor with waveguide unit, detector unit and encoder magnet, in perspective view and in longitudinal section,

[0071] FIG. 1c: the position sensor of FIGS. 1a, b in perspective view, but without the protective tube,

[0072] FIG. 2a-c: a first embodiment of the detector unit in perspective view obliquely from above, side view and top view,

[0073] FIG. 3a-c: the detector unit of FIGS. 2a to c in perspective view obliquely from below as well as matching side view and view from below,

[0074] FIG. 4a-c: a second embodiment of the detector unit in perspective view obliquely from above and side view and top view,

[0075] FIG. 5: a front view of the detector unit,

[0076] FIG. 6a-c: the semiconductor chip of the detector unit in perspective view, side view and top view.

[0077] FIGS. 1a, b show the entire position sensor 100 consisting of the waveguide unit 1—shown in a shortened form—in which the waveguide 1a runs as a magnetostrictive element, and the detector unit 15, as well as the encoder magnet 21, which is movable along the waveguide unit 1 and whose position is detected in the axial direction 1′, the direction in which the waveguide 1a or the waveguide unit 1 runs.

[0078] The encoder magnet 21 may annularly surround the waveguide unit 1, as shown in FIG. 1b, or may be present in only a portion of the circumference of the waveguide unit 1 as viewed in the circumferential direction, as shown in FIG. 1a, but is generally not adjacent to the waveguide unit 1.

[0079] The waveguide unit 1 includes a support tube 19 in which the waveguide 1a extends, generally centrally, and with respect to which it is fixed and supported in a special manner, but this is of no consequence to the present invention.

[0080] At the detection end shown, a head sleeve 20 is plugged onto the support tube 19, which together form a protective unit 19+20, the head sleeve 20 projecting axially beyond the support tube 19 and having a larger internal diameter in this projection than the support tube 19, the detector unit 15 being partially located, namely with the detector head 7, still in the region of the head sleeve 20, but projecting out of its end open at the measuring end.

[0081] At the opposite end, on the other hand, the support tube 19 of the waveguide unit 1 is mostly closed.

[0082] The head sleeve 20 also simplifies assembly, since it can be brought into position and connected to the support tube 19 only after the waveguide 1a projecting from the end face of the support tube 19 has been connected to the detector head 7, for example by being slid onto the support tube 19 before assembly and slid over the waveguide 1a after it has been fastened to the detector head 7 and connected to the support tube 19 in this protective position, for example by being glued or encapsulated.

[0083] FIG. 1c shows, in the same perspective view as FIG. 1a, the position sensor 100 without the protective unit, from which it can be seen that the waveguide 1a not only projects into the detector head 7, but preferably passes through it over its entire axial length.

[0084] The following FIGS. 2a to 4c show the detector unit 15 separately and without the waveguide attached to it:

[0085] FIGS. 2a to 3c show a 1st embodiment of the detector unit 15 on the one hand in views from above, and on the other hand in views from below, as well as the corresponding side views.

[0086] From this it is clear that the detector unit 15 consists of a strip-shaped, preferably semi-flexible or flexible, electronic circuit board 14, i.e. a PCB 14, at one end of which, the measuring end, the detector head 7 is formed by means of further components, and at the other end of which, by means of corresponding contact surfaces, the detector head 7 is formed as a connector 17, which may also comprise a plate applied to the circuit board 14 for stabilizing the semi-flexible circuit board 14 in this plug area.

[0087] Detector head 7 and connector 17 are electrically connected to each other via electrically conductive tracks 14a, b, c printed on board 14, which can be formed on the upper side as well as on the lower side or only one of the two sides.

[0088] The detector head 7 is formed in that two, in this case cuboid, boundary bodies 8 are placed on the measuring end of the strip-shaped board 14 on its upper side and along its longitudinal edges and are fixed to the board 14 so that a waveguide channel 12 is formed between them which is wide enough for the waveguide 1a to extend into it.

[0089] For stabilization—see in particular FIG. 5—a bridge plate 10 is attached to the boundary bodies 8 across the upper sides of the boundary bodies 8 facing away from the board 14 and across the waveguide channel 12, thus forming a portal-shaped base body 9 of the detector head 7.

[0090] The waveguide 1a is not fastened directly to this base body 9, but indirectly by means of a fastening element in the form of a fastening bracket 11, which in this case is hat-shaped—as can best be seen in FIG. 5—and rests with its freely projecting ends on the upper sides facing away from the board 14—axially away from the bridge plate 10—of each of the boundary bodies 8, while the central part extends downwards into the waveguide channel 12 until at or near the upper side of the board 14.

[0091] The waveguide 1a lies in this U-shaped, upwardly open central part of the fastening bracket 11 and is connected, in particular firmly connected, in particular glued or clamped, to the fastening bracket 11 and thereby occupies a defined distance from the upper side of the board 14, but is not connected to any of the strips 14a, b c of the board 14 in a contacting and thus electrically conductive manner. The same applies to the mounting bracket 11.

[0092] For this purpose, in the area of the detector head 7, i.e. in the length area of the semiconductor chip 2 and/or the mounting bracket 11, a separating tube 13 with a defined wall thickness made of electrically non-conductive material is arranged around the waveguide 1a, as can also be seen in FIG. 1b.

[0093] A semiconductor chip 2—preferably made of silicon as substrate—is fixed on the underside of the board 14 facing away from the waveguide 1a as well as the limiting bodies 8 and thus the base body 9, in that the chip 2 is soldered to matching soldering areas 3 on the underside of the board 14 by means of the so-called solderballs present on it, namely raised soldering points 5, which are formed on one side of the board-shaped chip 2.

[0094] As indicated in FIGS. 6a to c, electronic components connected to one another to form electronic circuits are formed inside the plate-shaped semiconductor substrate as known—usually in several layers one above the other—to realize an electronic chip 2.

[0095] In the present case, at least one detector coil 6 is formed in the semiconductor substrate 2, preferably as a flat coil lying only in one plane, and on the other hand an evaluation circuit 16, which can be located in another plane or also in the same plane next to the detector coil 6. In this case, the detector coil 6 is of course connected to the evaluation circuit 16 in terms of signals, preferably in an electrically conductive manner, within the semiconductor substrate 2, and the evaluation circuit 16 passes on the processed signals to a component connected to the connector 17, for example an electronic controller, via the connector surfaces 17.

[0096] Due to the defined position of the solder points 5 on the semiconductor chip 2 on the one hand and the corresponding solder pads 3 on the underside of the board 14 on the other hand, as well as the defined distance between the board 14 and the chip 2, the detector coil 6, which is also arranged in a defined position within the semiconductor chip 2, is also in a defined position, in particular a defined distance, to the fastening bracket 11 and thus to the waveguide 1a.

[0097] This exact spatial assignment is of great importance for the quality and strength of the useful signal obtainable by the detector head 7 from the mechanical, in particular longitudinal, wave arriving along the waveguide 1a at the measuring end and thus at the detector head 7, which was triggered by the encoder magnet 21.

[0098] To improve the quality of the useful signal or to obtain a usable useful signal at all, a defined premagnetization of the waveguide 1a must take place before or during the measurement.

[0099] In the 1st embodiment of the detector unit 15 according to FIGS. 2a to 3c, a so-called electrical biasing, namely a premagnetization by means of direct current, is carried out, for which purpose a bias coil 18 is formed in the semiconductor substrate which, when acted upon by direct current, generates a magnetic field which causes the desired premagnetization of the waveguide 1a extending at a small distance above it.

[0100] Preferably, the bias coil 18 is energized by the evaluation circuit 16, preferably in a pulsed manner and in time with the measurements, and for this purpose the bias coil 18 must be electrically connected to the evaluation circuit 16.

[0101] FIGS. 4a to c, on the other hand, show the classic type of premagnetization by means of a permanent magnet as the 2nd embodiment.

[0102] Therefore, a bias magnet 4a, b is arranged there in each of the two boundary bodies 8, in particular on or in its respective outer surfaces, which permanently effects this bias magnetization of the waveguide 1a.

[0103] For this purpose, among others, the boundary bodies 8 consist of a non-magnetic and preferably also non-magnetizable material, and/or also not of electrically conductive material, for example plastic.

[0104] With this 2nd embodiment, of course, no additional bias coil is then necessary in chip 2.

REFERENCE LIST ales klein !

[0105] 1 waveguide unit [0106] 1a waveguide [0107] 1′ running direction [0108] 2 semiconductor substrate, chip [0109] 3 soldering area [0110] 4a, b bias magnet [0111] 5 soldering point, solder ball [0112] 6 detector coil [0113] 6″ coil plane [0114] 7 detector head [0115] 8 boundary body [0116] 9 base body [0117] 10 bridge plate [0118] 11 fastening element, fastening bracket [0119] 12 waveguide channel [0120] 13 separating foil, separating hose [0121] 14 electronic board, PCB [0122] 14a, b, c strip conductor, PCB conductor [0123] 15 detector unit [0124] 16 evaluation circuit [0125] 17 connector, connector plate, contact surface [0126] 18 DC bias coil, bias coil [0127] 19 support tube [0128] 20 head sleeve [0129] 19+20 protection unit [0130] 21 encoder magnet [0131] 100 position sensor