Magnetic revolution counter and method for determining numbers of revolutions that can be determined by means of said revolution counter

Abstract

A magnetic revolution counter, and method for determining a predefinable number n of revolutions to be determined of a rotating magnetic field, generated by a magnetic system includes a revolution sensor, which includes magnetic domain wall conductors composed of open spirals or closed, multiply-wound loops, which are formed by a GMR layer stack or a soft magnetic layer comprising locally present TMR layer stacks and in which magnetic 180 domain walls can be introduced and located by measuring the electrical resistance of predefinable spiral or loop sections, wherein a single domain wall is, or at least two magnetic domain walls are, introduced into the domain wall conductors such that the at least two domain walls are brought into a defined separation of greater than 360 with respect to one another, based on the change in location thereof from a first to a second position, with a rotation of the outer magnetic field by the angle of greater than 360, and are permanently thus spaced apart from one another, and electrical contacts, which are disposed in a defined manner on the domain wall conductors, are provided.

Claims

1. A magnetic revolution counter for determining a predefinable number n of revolutions to be determined of an outer magnetic field, comprising a revolution sensor and a magnetic system configured to generate a rotating magnetic field and comprising an element comprising a pair of magnetic poles mounted to be rotatable about an axis situated between the magnetic poles, or a rotatable magnetic wheel comprising a plurality of magnetic poles situated around an axis of rotation of the magnetic wheel, or a linear scale comprising a plurality of magnetic poles and arranged to be movable in directions of a length of the linear scale, wherein the magnetic system is arranged relative to the revolution sensor so that the rotating magnetic field moves past the revolution sensor whereby the revolution sensor senses the rotation of the rotating magnetic field, and wherein the revolution sensor includes magnetic domain wall conductors composed of at least one open spiral or closed, multiply-wound loops, which are formed by a GMR (giant magnetoresistive) layer stack or a soft magnetic layer comprising locally present TMR (tunnel magnetoresistive) layer stacks and in which magnetic 180 domain walls can be introduced and located by measuring the electrical resistance of predefined spiral or loop sections, wherein a single domain wall is, or at least two magnetic domain walls are, introduced into the domain wall conductors and the at least two domain walls, by way of means for generating, pinning or deleting, in a defined manner, domain walls, are brought into a defined separation of greater than 360 with respect to one another, based on a change in location thereof from a first to a second position, with a rotation of the rotating magnetic field by the angle of greater than 360, and are permanently thus spaced apart from one another, and electrical contacts, comprising GND (ground) contacts, VCC (higher voltage relative to ground) and additional contacts, are provided on the domain wall conductors such that the domain wall conductors, located diagonally opposed, are captured by a respective GND contact and VCC contact collectively, or in VCC contact groups and GND contact groups with a multiplex read-out, and additional contacts are provided on each individual domain wall conductor section solely on one side and substantially centered between the GND contacts and VCC contacts, or, with a multiplex read-out, in groups of contacts that contact a plurality of windings as Wheatstone half bridge center contacts, and said electrical contacts, together with associated domain wall conductor sections captured thereby, are interconnected to form the Wheatstone half bridges that are separate from each other, but can be read out together, wherein the electrical resistance conditions ascertained by the Wheatstone half bridges are all stored as a signal level in a first memory in the form of a table, which for the determination of a present revolution number can be continuously compared to sub-tables of target value patterns stored in a second memory for each permissible revolution i (0in), and a processing unit is provided for determining for output the revolution number i for which the measured electrical resistance conditions in the table in the first memory agree with the target value pattern in the second memory.

2. A magnetic revolution counter for determining a predefinable number n of revolutions to be determined of an outer magnetic field, comprising a revolution sensor and a magnetic system configured to generate a rotating magnetic field and comprising an element comprising a pair of magnetic poles mounted to be rotatable about an axis situated between the magnetic poles, or a rotatable magnetic wheel comprising a plurality of magnetic poles situated around an axis of rotation of the magnetic wheel, or a linear scale comprising a plurality of magnetic poles and arranged to be movable in directions of a length of the linear scale, wherein the magnetic system is arranged relative to the revolution sensor so that the rotating magnetic field moves past the revolution sensor whereby the revolution sensor senses the rotation of the rotating magnetic field, and wherein the revolution sensor includes magnetic domain wall conductors composed of at least one open spiral or closed, multiply-wound loops, which are formed by a GMR (giant magnetoresistive) layer stack or a soft magnetic layer comprising locally present TMR (tunnel magnetoresistive) layer stacks and in which magnetic 180 domain walls can be introduced and located by measuring the electrical resistance of predefined spiral or loop sections, wherein a single domain wall is, or at least two magnetic domain walls are, introduced into the domain wall conductors and the at least two domain walls, by way of means for generating, pinning or deleting, in a defined manner, domain walls, are brought into a defined separation of greater than 360 with respect to one another, based on the change in location thereof from a first to a second position, with a rotation of the outer magnetic field by the angle of greater than 360, and are permanently thus spaced apart from one another, and electrical contacts comprising GND (ground) contacts, VCC (higher voltage relative to ground) and additional contacts, are provided on the domain wall conductors such that the domain wall conductors, located diagonally opposed, are captured by a respective GND contact and a respective VCC contact per winding or, with a multiplex read-out, are captured by a shared GND contact and a respective VCC contact per winding, or by a shared VCC contact and a respective GND contact per winding, and the electrical resistance conditions ascertained by way of these contacts are all stored as a signal level in a first memory in the form of a table, which for the determination of the present revolution number can be continuously compared to tabular target value patterns stored in a second memory for each permissible revolution i (0in), and a processing unit is provided for determining for output the revolution number i for which the measured electrical resistance conditions in the table in the first memory agree with the target value pattern in the second memory.

3. The magnetic revolution counter according to claim 1, further comprising a rotation angle sensor, or a quadrant sensor, wherein a signal of the rotation angle sensor, or of the quadrant sensor, determines the sub-table in the second memory to which the measured resistance conditions in the table of the first memory are compared.

4. The magnetic revolution counter according to claim 1, wherein the at least one open spiral or the closed, multiply-wound loops forming the domain wall conductors each have a substantially rhombus shape, wherein said electrical contacts capture the corner regions of the rhombuses.

5. The magnetic revolution counter according to claim 1, wherein the defined separation between the at least two neighboring domain walls is established at 540.

6. The magnetic revolution counter according to claim 1, wherein the domain wall conductors are formed by open spirals both ends of which are pointed.

7. The magnetic revolution counter according to claim 1, wherein the means for generating, pinning or deleting domain walls, in a defined manner, are formed by an additional conductor, which captures at least one winding of the domain wall conductor and is tapered at a contact point bridging the domain wall conductor and which ensures that an Oersted field having a sufficient magnitude is generated when a current is applied.

8. A method for determining integral revolution numbers by using a magnetic revolution counter according to claim 1, comprising first impressing a domain pattern including only a single domain wall or having a defined separation of domain walls into the domain wall conductors, wherein the separation of at least two neighboring domain walls is established at greater than 360, based on a change in location thereof from a first to a second position, with a rotation of the rotating magnetic field by an angle of greater than 360, and corresponding to the impressed domain wall pattern, storing all signal level target values to be expected from the Wheatstone half bridges or domain wall conductors as the sub-tables of target value patterns in the second memory for all possible fall 360 revolutions (0in) ascertainable by way of the magnetic revolution counter and all associated changed domain wall positions, and storing all the associated values of the revolution sensor presently ascertained by the Wheatstone half bridges or domain wall conductors during the present count in the table in the second memory, and continuously comparing the measured values in the table in the first memory to the respective signal level target values in the second memory, and wherein the ascertained revolution number i is output when the tabular values in the two memories agree with one another.

9. The method according to claim 8, wherein the apparatus further comprises a rotation angle sensor or a quadrant sensor, signal level target values are stored in at least four said sub-tables for four field angle quadrants in the second memory for each individual revolution i countable by way of the revolution counter, the measured value from the angle sensor, or from the quadrant sensor, determines which table of said sub-tables to which signal levels in the table of the first memory are continuously compared so as to ascertain the associated revolution number.

10. The magnetic revolution counter according to claim 2, further comprising a rotation angle sensor, or a quadrant sensor, wherein a signal of the rotation angle sensor, or of the quadrant sensor, determines the sub-table in the second memory to which the measured resistance conditions in the table of the first memory are compared.

11. The magnetic revolution counter according to claim 2, wherein the at least one open spiral or the closed, multiply-wound loops forming the domain wall conductors each have a substantially rhombus shape, wherein said electrical contacts capture the corner regions of the rhombuses.

12. The magnetic revolution counter according to claim 2, wherein the defined separation between the at least two neighboring domain walls is established at 540.

13. The magnetic revolution counter according to claim 2, wherein the domain wall conductors are formed by open spirals both ends of which are pointed.

14. The magnetic revolution counter according to claim 2, wherein the means for generating, pinning or deleting domain walls, in a defined manner, are formed by an additional conductor, which captures at least one winding of the domain wall conductor and is tapered at a contact point bridging the domain wall conductor and which ensures that an Oersted field having a sufficient magnitude is generated when a current is applied.

15. A method for determining integral revolution numbers by using a magnetic revolution counter according to claim 2, comprising first impressing a domain pattern including only a single domain wall or having a defined separation of domain walls into the domain wall conductors, wherein the separation of at least two neighboring domain walls is established at greater than 360, based on a change in location thereof from a first to a second position, with a rotation of the rotating magnetic field by an angle of greater than 360, and corresponding to the impressed domain wall pattern, storing all signal level target values to be expected from the Wheatstone half bridges or domain wall conductors as the sub-tables of target value patterns in the second memory for all possible full 360 revolutions (0in) ascertainable by way of the magnetic revolution counter and all associated changed domain wall positions, and storing all the associated values of the revolution sensor presently ascertained by the Wheatstone half bridges or domain wall conductors during the present count in the table in the second memory, and continuously comparing the measured values in the table in the first memory to the respective signal level target values in the second memory, and wherein the ascertained revolution number i is output when the tabular values in the two memories agree with one another.

16. The method according to claim 15, wherein the apparatus further comprises a rotation angle sensor or a quadrant sensor, signal level target values are stored in at least four said sub-tables for four field angle quadrants in the second memory for each individual revolution i countable by way of the revolution counter, and the measured value from the angle sensor, or from the quadrant sensor, determines which table of said sub-tables to which signal levels in the table of the first memory are continuously compared so as to ascertain the revolution number.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The following advantageous exemplary embodiments and figures are intended to provide a more detailed description of the above and of the invention, without thereby limiting the invention. In the drawings:

(2) FIG. 1 shows the essential components of a revolution counter according to the present invention;

(3) FIG. 2 shows a first general example of the design of the required sensor element having the contact arrangement according to the invention;

(4) FIG. 3a shows the writing-in of a preferred provided magnetization pattern according to the invention based on FIG. 2;

(5) FIG. 3b shows the writing-in of a likewise possible magnetization pattern according to the invention based on FIG. 2, comprising only one domain wall;

(6) FIG. 4 shows a second general example of the design of the required sensor element having a contact arrangement according to the invention;

(7) FIG. 5 shows an example of the achieved bond contact savings based on FIG. 4 in a more complete view of the chip in the revolution sensor;

(8) FIG. 6 shows the interconnection of the contacts that are provided according to the invention and disposed on the revolution sensor for forming Wheatstone bridges according to the example of FIG. 4;

(9) FIG. 7 shows a third general example of the design of the required sensor element having the contact arrangement according to the invention and a starting domain wall position;

(10) FIG. 8 shows the domain wall position according to FIG. 7 after three revolutions of the outer magnetic field;

(11) FIG. 9 shows signal level sequences, obtained from the provided 360 Wheatstone contacts for four exemplary quadrants according to FIGS. 7 and 8;

(12) FIG. 10 shows a flow chart of the procedure of determining a revolution correlated with the associated assemblies;

(13) FIG. 11 shows a revolution counter according to FIG. 1 combined with a magnet wheel;

(14) FIG. 12 shows a revolution counter according to FIG. 1 combined with a linear scale;

(15) FIGS. 13a and 13b, by way of example, show a design according to FIG. 4, here comprising TMR contacts and the 360 contacting according to the invention; and

(16) FIG. 14 shows the sensor element of FIG. 13a having a contact arrangement according to the invention for resistance measurement.

(17) Embodiments according to the invention of revolution counters having the 360 contacting according to the invention are described hereafter based on accompanying figures, and allow a bijective read-out of integral revolution numbers at any field angle.

(18) First, FIG. 1 shows the essential components of such a revolution counter system 1 comprising a revolution counter 1a according to the invention and a magnetic system 4 having a magnetic north (N) and a magnetic south (S) mounted to a rotating shaft 5. The revolution counter 1a comprises the following main components: a revolution sensor US 2, a 360 angle sensor WS 3, and electronics 6. The sensors 2 and 3 are mounted in a stationary manner and detect the angular position and the number of revolutions of the rotating magnetic field. The electronics 6 includes power supply units 7 for the sensor 2 and 3 and for processing the measured values, a memory 8 for the measured values of the angle sensor 3 and a memory 9 for the measured values of the revolution sensor 2, a memory 10 for target values of the revolution sensor 2 stored in tabular form, and a processing unit 11, which compares the measured values from the memories 8 and 9 to the tabular values of the memory 10 and outputs the result of each measurement.

(19) The first special characteristic of the present invention is the design according to the invention of the revolution sensor 2, which will be described based on an exemplary and simplified illustration in FIG. 2. In particular, the design according to the invention with respect to the new manner of the contact connection will be described here.

(20) In this example, the sensor element 2 is formed by a three-turn, square spiral 20 having pointed ends. The one tip 21 is the end of the outer winding, and the other tip 22 is the end of the innermost winding. In the example, corresponding to the known prior art, the spiral is composed of a magnetic layer stack, which exhibits the GMR effect. The reference direction 28 is diagonal with respect to the square windings. The first, outermost winding is composed of webs 31, 32, 33 and 34, the second, center winding is composed of webs 41, 42, 43 and 44, and the third, innermost winding is composed of webs 51, 52, 53 and 54. Each of the aforementioned webs is positioned at an angle of 90 with respect to the respective neighboring, adjoining web. Solely for the purpose of illustration of the actual conditions, it is shown that the connections between the webs are quarter circles or quarter circle-like polygonal lines 302 (shown in the zoomed-in circle 301), which are composed of the same layer stack as the webs. These polygonal lines form the corners of the square spiral, while also forming the above-mentioned domain wall positions (DW positions). Domain walls for large field angle ranges of the outer rotating magnetic field, according to FIG. 1 generated by the magnetic system 4, remain in the DW positions. So as to transport a DW through a quarter circle, the outer magnetic field must rotate by 90, plus a hysteresis angle of typically 5 to 20. During the transport through a web, there is basically almost no rotation of the magnetic field since the DW traverses the webs at several 100 m/sec. Accordingly, the DW moves from one quarter circle to the next quarter circle within less than 100 ns. From a time perspective, the domain walls thus essentially remain the entire time in the DW positions. The first, outermost winding thus includes the DW positions 35, 36, 37 and 38, the second winding includes the DW positions 45, 46, 47 and 48, and the third winding includes the DW positions 55, 56, 57 and 58.

(21) The exemplary spiral is provided with electrical contacts, and more particularly with a shared GND contact 70 at the top left, a shared VCC contact 80 at the bottom right, and according to the invention exclusively three center contacts 91, 93 and 95 in FIG. 2 at the top right. According to the claim, this means on a spiral half, which is formed by an imaginary diagonal extending through the VCC and GND contacts. FIG. 2 furthermore shows a conductor 25 having a constriction 26 for initializing the sensor element. The magnetization state of the sensor element 2 is read out by way of potential measurement and interconnection to form three Wheatstone half bridges: The Wheatstone half bridge W1 is formed by the webs 33 and 34 together with the center contact 91, the GND contact 70 and the VCC contact 80.

(22) The Wheatstone half bridge W2 is formed by the webs 43 and 44 together with the center contact 93, the GND contact 70 and the VCC contact 80.

(23) The Wheatstone half bridge W3 is formed by the webs 53 and 54 together with the center contact 95, the GND contact 70 and the VCC contact 80.

(24) Initially, the sensor element 2 according to FIG. 2 is to be completely filled with six domain walls (black circles), which were generated, for example, following a field pulse having a field strength exceeding the nucleation field strength of the sensor element 2 in the direction of the magnetization of the reference direction 28.

(25) In the first, outermost winding, the DW 111 is located in the DW position 36, and the DW 112 is located in the DW position 38.

(26) In the second, center winding, the DW 113 is located in the DW position 46, and the DW 114 is located in the DW position 48.

(27) In the third, innermost winding, the DW 115 is located in the DW position 56, and the DW 116 is located in the DW position 58.

(28) The aforementioned three half bridges are at the center potential due to these DW positions and the position of the reference direction 28. The magnetization direction in the cw direction is shown in dark gray, and the magnetization direction in the ccw direction is shown in light gray. Additionally, the magnetization direction is identified in each web by a arrow. The reference direction 28 of the GMR layer stack is diagonal with respect to the square spiral and, in the example, is oriented from the bottom left to the top right.

(29) So as to achieve the proviso underlying the present invention of a defined separation for two neighboring domain walls of >360, at least two DW still have to be deleted. This will be described hereafter based on FIGS. 3a, 3b.

(30) For the sake of clarity, the spiral shown in FIG. 2 includes only three windings. Actual sensor elements typically include ten to thirty such windings if a spiral design is selected.

(31) With reference to FIG. 2, FIG. 3a shows the sensor element 2 in which a magnetization pattern having 540 angular separation between two neighboring domain walls was initialized, which enables 360 contacting according to FIG. 2 for bijective revolution counting. While full occupancy of the spiral with domain walls is not suitable for bijective revolution counting with the provided contacting, an option for initializing a magnetization pattern that is required according to the invention shall be described in slightly greater detail based on FIG. 3a, which takes place in six steps: 1. Prior to installing the sensor system for counting n revolutions (three revolutions in the example here), a mechanical end stop, which is not shown here, is unlocked, and the outer magnetic field is rotated n+1 revolutions (four here) in the ccw direction, whereby all potentially present domain walls, or the six domain walls shown in FIG. 2, leave the spiral via the tip 21. Thereafter, the sensor element is rotated into the desired zero position (the center position here for counting n/2 revolutions in the cw direction and n/2 revolutions in the ccw direction), and the end stop is locked. 2. This is followed by the nucleation of two domain walls by way of a current flow over a conductor 25 in the winding beneath the constriction 26. The current-induced Oersted field is above the nucleation field strength of the sensor element 2. The nucleated two domain walls are transported by the magnetic field of the magnet 4 oriented in the reference direction 28 (corresponding to FIG. 1) into the DW position 46 and into the DW position 48. 3. When the flow of current through the conductor 25 is deactivated, the outer magnetic field is rotated by 360 in the ccw direction, whereby the two nucleated DW are transported out of the DW position 46 into the DW position 36, and out of the DW position 48 into the DW position 38. 4. This is again followed by the nucleation of two domain walls by way of current flow over the conductor 25 in the winding beneath the constriction 26. The current-induced Oersted field is above the nucleation field strength of the sensor element 2. One DW is transported into the DW position 46, and the other DW is transported into the DW position 48 by the magnetic field of the magnet 4 pointing in the reference direction 28 (corresponding to FIG. 1). 5. The flow of current through the conductor 25 is reduced until, beneath the constriction 26, the resulting magnetic field of the sensor system and of the Oersted field (which is present parallel to the web 42 and points to the DW position 46) is below the minimum movement field strength of the sensor element. By way of a 270 cw rotation, the DW is transported out of the DW position 46, and the DW is transported out of the DW position 38 to the constriction 26, where they annihilate. At the same time, the DW is transported out of the DW position 36 into the DW position 45, and the DW is transported out of the DW position 48 into the DW position 57. 6. After the Oersted field has been deactivated, a 90 ccw rotation takes place, whereby the DW is transported out of the DW position 45 into the DW position 38, and the DW is transported out of the DW position 57 into the DW position 56. These domain walls are denoted as DW 111 (in the DW position 38) and as DW 112 (in the DW position 56) FIGS. 3a, 3b. The DW gaps DWL 221 and DWL 222 that arose are denoted by a cross.

(32) As required within the scope of the invention, the two domain walls 111 and 112 provided in this example are spaced apart from one another by 540, based on a cw rotation of the outer magnetic field.

(33) In a further embodiment of the invention, FIG. 3b shows the sensor element according to FIG. 2, which has a magnetization pattern including only a single domain wall. The domain wall conductor of the spiral 20 shown in FIG. 3b is identical to the domain wall conductor illustrated in FIG. 3a. The 360 contacting shown in FIG. 3b, comprising the GND contact 70, the VCC contact 80 and the center contacts 91, 93 and 95 is identical to the 360 contacting according to FIG. 2. In contrast to the designs according to FIGS. 2 and 3a, the conductor 25 comprising the constriction 26 is not required for initializing the magnetization pattern MP using a single DW in the example according to FIG. 3b. The initialization takes place in four steps, for example, in this example: 1. Prior to installing the sensor system for counting n revolutions (three revolutions in the example here), the sensor element is exposed to a magnetic field that is above the nucleation field strength and, for example, points in the direction of the reference magnetization 28. As a result, two DW nucleate in each winding, which assume the DW positions located on the diagonal from the bottom left to the top right. These DW positions (six here) are already shown in FIG. 2. 2. Thereafter, the mechanical end stop, which is not shown here, is unlocked, and the outer magnetic field (of the magnet 4 shown in FIG. 1) is rotated by 270 in the cw direction. In this way, the DW 116 shown in FIG. 2 and positioned in the DW position 58 leaves the spiral via the tip 22. At the same time, the DW 115 shown in FIG. 2 is transported out of the DW position 56 and into the DW position 65, so as to be positioned in front of the last straight segment comprising the tip 22. 3. By way of three ccw rotations, the DW is positioned out of the DW position 65 and into the DW position 35, wherein during this transport all domain walls positioned in front of this DW successively leave the spiral via the tip 21. When the DW is positioned in the DW position 35, it is the only DW remaining in the spiral. This DW is referred to as DW 111a in FIG. 3b. 4. This DW 111a is subsequently transported into the zero position of the sensor element. When the zero position is the DW position 35 (for counting three cw revolutions), the initialization is concluded by locking the end stop. When the zero position is the DW position 47 for counting 1.5 revolutions in the cw direction and 1.5 revolutions in the ccw direction, the DW 111a is transported with 1.5 cw revolutions out of the DW position 35 and into the DW position 47, and the end stop is locked. For counting three ccw revolutions, the DW 111a is transported with three cw revolutions out of the DW position 35 and into the DW position 65.

(34) The advantage of the design according to FIG. 3b is that the conductor 25, and thus the associated two bond contacts, are dispensed with. The disadvantage, however, is the purely mechanical initialization, which must take place with high angular precision. Mispositioning during the DW nucleation and/or during the rotation of the spiral until cleared may easily cause either all DW to leave the spiral, whereby revolution counting is not possible, or two domain walls having an angular separation of 180 with respect to one another, instead of one DW, to remain in the spiral, whereby bijective revolution counting is not possible. In principle, however, a design according to FIG. 3b is possible, including with provided numbers of windings that are higher than those cited in the example. The means to be provided within the scope of the invention for generating or, in a defined manner, deleting domain walls in this embodiment are formed by an outer magnetic field, which during the DW generation has a field strength above the nucleation field strength, and the mechanical means for driving out undesirable domain walls from the spiral which is open at both ends.

(35) A second general exemplary embodiment according to FIG. 4 shall serve to demonstrate the multivalency of the designs of the revolution sensor 2 used within the scope of the invention, regarding domain wall conductors used.

(36) FIG. 4 shows a further general design according to the invention of a revolution sensor 2, composed of a four-turn, closed loop 27 here. A magnetization pattern including the two domain walls DW 111 and DW 112 having an angular separation of 540 was initialized by way of the conductor 25 comprising the constriction 26. The reference direction 28 of the GMR layer stack forming the loop 27 is diagonal with respect to the square spiral and points from the bottom left to the top right. Electrical contact with this loop is made analogously to the spiral in FIG. 2 by way of a shared GND contact 70, a shared VCC contact 80 and four center contacts 91, 93, 95 and 97, which are located in a half at the top right above the diagonal between the VCC contact and the GND contact.

(37) The magnetization state of the sensor element is again read out by way of potential measurement using four Wheatstone half bridges:

(38) The Wheatstone half bridge WHB1 is formed by the webs 33 and 34 together with the center contact 91, the GND contact 70 and the VCC contact 80.

(39) The Wheatstone half bridge WHB2 is formed by the webs 43 and 44 together with the center contact 93, the GND contact 70 and the VCC contact 80.

(40) The Wheatstone half bridge WHB3 is formed by the webs 53 and 54 together with the center contact 95, the GND contact 70 and the VCC contact 80.

(41) The Wheatstone half bridge WHB4 is formed by the webs 63 and 64 together with the center contact 97, the GND contact 70 and the VCC contact 80.

(42) Each winding is connected to a Wheatstone half bridge.

(43) In this example as well, the separation between the two neighboring domain walls DW 111 and DW 112 is 540, as viewed in the cw direction.

(44) FIG. 5 shows an example of the reduction in bond contacts sought according to the object and achieved, based on FIG. 4, in a more complete view of the chip in the revolution sensor. FIG. 5 shows the revolution sensor 2 from FIG. 4 on a chip 202 comprising bond contacts. The reference direction 28 of the GMR layer stack is diagonal with respect to the square spiral and points from the bottom left to the top right. The bond contact 270 connects the GND contact 70, the bond contact 291 connects the center contact 91, the bond contact 293 connects the center contact 93, the bond contact 295 connects the center contact 95, the bond contact 297 connects the center contact 97, the bond contact 280 connects the VCC contact 80, the bond contacts 225a and 225b connect the ends of the conductor 25 to the constriction 26. The size and number of the bond contacts essentially determine the chip size. Due to the 360 contacting according to the invention, four bond contacts were saved in this example. This effect becomes more apparent when a higher number of windings is provided in the sensor 2 for counting larger revolution numbers. In a revolution counter for 30 revolutions, only a maximum of 32 bond contacts (VCC+GND+30 center contacts) are required with the new kind of contacting, which is to say the 360 contacting according to the invention, instead of 62 bond contacts, as was required heretofore according to the prior art (namely: VCC+GND+60 center contacts), and with 5multiplexing only 16 (namely: 5 VCC+5 GND+6 center contacts) instead of 22 bond contacts (namely: 5 VCC+5 GND+12 center contacts) are required. The multiplex read-out of the Wheatstone half bridge signals, which is not described in more detail here, takes place successively using a clock frequency in the MHz range, while the measuring intervals are in the kHz range, and essentially simultaneous. This is accompanied by a reduction in the bond contacts to 48% or 27%, respectively. Since the chip surface is essentially determined by the size and the number of the bond contacts connected to the spiral contacts, this minimizes the chip surface per sensor element by 25% or 10%, respectively, as was ascertained by way of example based on layout simulations.

(45) FIG. 6 shows the interconnection of the revolution sensor 2 according to FIGS. 4 and 5 to form four Wheatstone bridges WB1 to WB4, wherein the web resistors were numbered with Rij, according to the web numbers used in FIG. 2. The web resistors form a Wheatstone half bridge. To yield a Wheatstone full bridge, these web resistors are interconnected, for example, with two additional fixed resistors, which are external and not contained in the sensor element and which are not magnetoresistive and provided with the addendum ref for reference resistor in FIG. 6.

(46) The Wheatstone bridge WB1 is composed of the resistors 133 (R33), 134 (R34), 233 (Rref33) and 234 (Rref34). The resistors 133 and 134 are webs from the first, outermost winding of the loop 27. The reference resistors 233 and 234 are fixed resistors located outside the sensor element.

(47) The Wheatstone bridge WB2 is composed of the resistors 143 (R43), 144 (R44), 243 (Rref43) and 244 (Rref44). The resistors 143 and 144 are webs from the second winding of the loop 27. The reference resistors 243 and 244 are fixed resistors located outside the sensor element.

(48) The Wheatstone bridge WB3 is composed of the resistors 153 (R53), 154 (R54), 253 (Rref53) and 254 (Rref54). The resistors 153 and 154 are webs from the third winding of the loop 27. The reference resistors 253 and 254 are fixed resistors located outside the sensor element.

(49) The Wheatstone bridge WB4 is composed of the resistors 163 (R63), 164 (R64), 263 (Rref63) and 264 (Rref64). The resistors 163 and 164 are webs from the fourth, innermost winding of the loop 27. The reference resistors 263 and 264 are fixed resistors located outside the sensor element.

(50) As in all other examples, within the scope of the invention the signal levels of all Wheatstone bridges are now detected essentially simultaneously and stored continuously in a memory 9 in tabular form, and are thus available for the subsequent comparison to the target values stored for the quadrants in the memory 10.

(51) A third general exemplary embodiment of the invention is shown in FIG. 7. FIG. 7 shows a revolution sensor 2, composed of a spiral 20 formed of two approximately equally sized sub-spirals having the same direction of rotation. The ends of the spiral are formed by the tips 21 and 22 in this example. The reference direction 28 of the GMR layer stack is oriented diagonally with respect to the square spiral and points from the bottom left to the top right (see arrow at the center of the spiral). The spiral in this example is read out electrically using five Wheatstone half bridges WHB1 to WHB5: WHB1 comprising the webs between the GND contact 71, the center contact 91 and the VCC contact 81 (winding 1); WHB2 comprising the webs between the GND contact 71, the center contact 93 and the VCC contact 81 (winding 2); WHB3 comprising the webs between the GND contact 72, the center contact 95 and the VCC contact 82 (winding 3); WHB4 comprising the webs between the GND contact 72, the center contact 97 and the VCC contact 82 (winding 4); WHB5 comprising the webs between the GND contact 72, the center contact 99 and the VCC contact 82 (winding 5).

(52) In the example, a magnetization pattern including two domain walls having an angular separation of 540, as was already described, were initialized via the electrical contact 25 comprising the constriction 26. The positions of the domain walls DW 111 and DW 112 shall represent the revolution number zero in this example. Two DW gaps DWL 221 and DWL 222 are present between the DW 111 and the DW 112, which arose due to the annihilation of two domain walls, so that a separation of >360, again 540 here, is set between the neighboring domain walls DW 111 and DW 112 in the cw direction.

(53) The magnetization direction of the webs in the WHB1 and the WHB2 is ccw, and that of the webs in the WHB3, the WHB4 and the WHB5 is cw. Due to the reference direction 28 of the GMR layer stack, the signal levels of the five Wheatstone half bridges in the example are: WHB1 (winding 1): L WHB2 (winding 2): L WHB3 (winding 3): H WHB4 (winding 4): H WHB5 (winding 5): H

(54) The processing unit 11 processes all measured signal levels of the five half bridges simultaneously, for example as a signal level sequence (SLS) from winding 1 to winding 5, and compares these to target values stored in the memory 10. The SLS for FIG. 7 in the illustrated example is: L/L/H/H/H. What is decisive for the detection of the counted revolutions is the portion of the SLS which correlates with the magnetization pattern MP, which is to say with the positions of the DW 111 and the DW 112. This portion is referred to hereafter as SLS-MP and has the two signal levels L/L. As the MP is transported through the spiral due to the revolutions that occur, the SLS-MP is also bijectively repositioned within the SLS (see FIG. 9). It is possible to bijectively count three revolutions using the sensor element according to the illustrated example from FIG. 7.

(55) For illustration, FIG. 8 shows the domain wall position after three cw revolutions. The DW 111 and the DW 112 and the interposed DW gaps DWL 221 and DWL 222 were transported twelve DW positions, which is to say three windings, further, and more particularly into the positions shown in FIG. 8. The positions of the DW 111 and DW 112 thus represent revolution number three. The magnetization direction of the webs in the WHB4 and the WHB5 is ccw, and that of the webs in the WHB1, the WHB2 and the WHB3 is cw, again indicated here by arrows on the domain wall conductors. The signal levels of the Wheatstone half bridges after three 360 revolutions are: WHB1 (winding 1): H WHB2 (winding 2): H WHB3 (winding 3): H WHB4 (winding 4): L WHB5 (winding 5): L

(56) The SLS after three revolutions is thus H/H/H/L/L. Compared to the SLS of FIG. 7 (L/L/H/H/H), the SLS-MP having the levels UL has been transported one position further to the right within the SLS with each counted revolution. This correlates with the further transport of the domain walls DW 111 and DW 112 into the next winding with each counted revolution. Designing the sensor element 2 in the form of two sub-spirals having the same winding direction of rotation has the advantage that it is possible to design the overall spiral to be smaller, for example compared to a design according to FIG. 3, and thereby reduced the required chip surface.

(57) FIG. 9 is intended to help illustrate the evaluation and assessment of the signal level sequences that have been ascertained during the count, in keeping with the impressed domain wall pattern in correlation with each quadrant, and have been stored, and essentially illustrates the evaluation method according to the invention in more detail, based on the example according to FIGS. 7 and 8.

(58) FIG. 9 shows the target value signal level sequences for the revolutions 0, 1, 2and 3 for the five windings W1 to W5 according to FIG. 7 for the sensor element from FIG. 7 and FIG. 8 in tabular form, for the field angle quadrant 1 (FIG. 9a), the field angle quadrant 2 (FIG. 9b), the field angle quadrant 3 (NG. 9c) and the field angle quadrant 4 (FIG. 9d) predefined by the quadrant sensor or angle sensor 3. For the specific sensor used, a bijective pattern thus always exists. For each quadrant, a dedicated significant SLS-MP exists, and a respective dedicated bijective SLS exists for each revolution. The significant SLS-MP for quadrant Q1 is for Q2 it is M/L, for Q3 it is L, and for Q4 it is L, wherein H denotes a high, M a medium, and L a low Wheatstone half bridge signal level. The above-described significant SLS-MP are each highlighted in medium or dark gray in the tables of FIG. 9. As a result, at least one sub-table comprising all SLSs for all permissible (which is to say countable) revolutions is kept available according to the invention for each individual quadrant, which are listed by way of example in FIGS. 9a to 9d. The processing unit 11 first determines the field angle quadrant in which the system is presently located, which is to say the position of the rotating element 4 (according to FIG. 1, for example). Following this determination, the processing unit 11 searches the sub-table associated with the selected quadrant, and thereafter compares the measured SLS to the SLS target values of the corresponding quadrant. In the example, this would be the quadrant 1 (FIG. 9a) By comparing the measured values in the memory 9 to the target value signal level sequences kept available in the memory 10, from this sub-table the processing unit 11 immediately thereafter ascertains the associated revolution number (agreement of the SLSs), which can then be output/displayed. In the example, the signal level sequence according to FIG. 7 corresponds to the revolution number zero, and the signal level sequence according to FIG. 8 corresponds to the revolution number three, as is easily apparent from a comparison to the above description. If a different field angle quadrant predefines the selection of the associated sub-table, the procedure is analogous.

(59) FIG. 10 schematically shows the determination of the revolution number in a flow chart 400 when the revolution counter system 1 ascertains an arbitrary, but unknown revolution number. After the start of the measuring cycle, the electronics 6, in the first step, reads out the angle sensor (WS) 2 and the revolution number sensor (US) 3, and stores the values in the memories 8 and 9 as the value W8 (8a) and the table T9 (9a); in step 2, the processing unit 11 ascertains the associated field angle quadrant Q1, Q2, Q3 or Q4 from the angle sensor measured value W8 (8a); for the ascertained quadrant (such as Q1), in step 3 the sub-table for the ascertained quadrant (such as sub-table S1 Q1 (10a)) is loaded from the memory 10 comprising the target value signal level tables for the permissible revolutions i (0in); in step 4, the processing unit 11 sets the continuous index i to 0; step 5 is an iterative comparison by the processing unit 11 between the measured SLS in the table T9 (9a) and the target value SLS (for example, from sub-table S1 Q1 (10a)) for the revolution i: if the values agree, the processing unit 11 in step 6 outputs the revolution number i, or if the values do not agree, the continuous index i is increased by one in step 6, and in step 7 it is checked whether i>n: if i>n, the processing unit 11 in step 8 outputs an error value; otherwise step 5 is repeated for the revolution i+1.

(60) The measuring cycle is completed with the output of a revolution number or of an error value. An error value is only output if no agreements whatsoever can be observed between the measured signal level sequences and those stored as the target values. This is synonymous with the domain wall pattern impressed into the revolution sensor having changed due to external conditions, such as excessive external disturbance magnetic fields and the like. In such an extremely rare case, the desired magnetization pattern would have to be re-written into the revolution sensor 2.

(61) The entire procedure of determining countable revolution numbers by way of the above-described electronic components takes place over times that are substantially shorter than those during which the direction of the outer magnetic field acting on the revolution sensor 2 has changed. Typically, the measurement and evaluation of an SLS takes place using MHz clock frequencies (which is to say within one s), while the magnetic field is rotating at a maximum of 1 KHz. In one s, the direction of the magnetic field thus rotates by a maximum of 0.3. As a result of these high evaluation speeds, it is also possible to display the found revolution numbers, which during the currentless operation shifted the magnetization pattern in the sensor 2, in several 10 ns to a maximum of 1 s.

(62) While all assemblies essential to the invention are contained in the actual revolution counter, which is enclosed in a frame-like manner in FIG. 1 and denoted by reference numeral 1a, figures hereafter shall illustrate the broad field of application of the solution according to the invention.

(63) FIG. 11, for example, shows the revolution counter 1a from FIG. 1 combined with a magnet wheel 5a comprising magnetic poles 4a to 4l instead of a magnet 4 on a shaft 5 according to FIG. 1. When the magnet wheel 5a is rotated, it generates a magnetic rotating field at the location of the angle sensor WS 3 and of the revolution sensor US 2 which moves the domain walls of the magnetization pattern in the sensor element 2. Each magnet wheel position thus corresponds to an angle sensor measured value and a revolution counter measured value. The revolution counter counts the number of the magnetic pole pairs that are moved past. This is analogous to the counting of revolutions of the magnet 4 according to FIG. 1.

(64) FIG. 12 shows the revolution counter 1a from FIG. 1 combined with a linear scale 5b comprising magnetic poles 4a to 4l instead of a magnet 4 on a shaft 5 according to FIG. 1. The linear scale 5b comprising twelve magnetic poles in the example (6 magnetic north poles alternatingly with 6 magnetic south poles) 4a to 4l also represents other linear scales having more or fewer magnetic poles. When the scale 5b is moved past relative to the revolution counter 1a, the scale generates a magnetic rotating field at the location of the angle sensor WS 3 and of the revolution sensor US 2, which moves the domain walls of the impressed magnetization pattern in the sensor element 2. Each scale position thus corresponds to an angle sensor measured value and a revolution counter measured value. The revolution counter counts the number of the magnetic pole pairs that are moved past. This is analogous to the counting of revolutions of the magnet 4 according to FIG. 1.

(65) Finally, FIGS. 13a+b, by way of example, show the use of a sensor element 2 comprising TMR contacts having the 360 contacting according to the invention. The spiral 27 is made of a soft magnetic material, such as permalloy, in this case.

(66) FIG. 13a shows an exemplary four-turn, closed loop 27 in a top view. The sensor element 2 is read out by way of potential measurements using four Wheatstone half bridges WHB1 to WHB4: WHB1 is composed of the web 33 comprising the GND tunneling contact 71, and the web 34 comprising the VCC tunneling contact 81 and the center contact 91, which covers the quarter circle-shaped corner between the web 33 and the web 34 and parts of these webs. WHB2 is composed of the web 43 comprising the GND tunneling contact 72, and the web 44 comprising the VCC tunneling contact 82 and the center contact 93, which covers the quarter circle-shaped corner between the web 43 and the web 44 and parts of these webs. WHB3 is composed of the web 53 comprising the GND tunneling contact 73, and the web 54 comprising the VCC tunneling contact 83 and the center contact 95, which covers the quarter circle-shaped corner between the web 53 and the web 54 and parts of these webs. WHB4 is composed of the web 63 comprising the GND tunneling contact 74, and the web 64 comprising the VCC tunneling contact 84 and the center contact 97, which covers the quarter circle-shaped corner between the web 63 and the web 64 and parts of these webs. (Reference numerals not denoted in FIG. 13a are apparent from FIG. 14).

(67) FIG. 13b shows the web 33 in a lateral section through FIG. 13a representatively for all webs comprising a tunneling contact. The web 33 is made of a soft magnetic material 501, for example permalloy, and protected with an oxide layer 504a and 504b. The GND tunneling contact 71 is positioned in the web center. The tunneling contact comprises a permalloy layer 501, a tunnel barrier 502 (such as Al.sub.2O.sub.3 or MgO), a hard magnetic layer stack 503, into which the reference direction (28 in FIG. 13a) is written, and a gold electrode 505. The center contact 91, which is made of gold, is located directly on the permalloy 501 on the right of the web 33. The flow of current on the tunneling contact takes place from the electrode 505, through the hard magnetic layer stack, and through the barrier 502, into the permalloy 501. Typical TMR contacts reach changes in resistance of >100% between a parallel and an anti-parallel magnetization of the soft magnetic and the hard magnetic layers in the TMR contact, which is to say as a function of the respective position of the domain walls 111, 112. The initialization of the domain wall pattern according to the invention, and the evaluation and the determination of the present revolution number, in this example take place analogously to the proviso already described with respect to FIG. 5 and others and consequently need not be repeated here.

(68) FIG. 14 shows the revolution sensor from FIG. 13a having modified contacting in which the resistances are read out. This loop is electrically contacted with the GND contacts 71, 72, 73 and 74, and the VCC contacts 81, 82, 83 and 84, a respective GND contact and a respective VCC contact being located on one winding. So as to utilize the TMR effect, the VCC contacts, for example, must contact the respective soft magnetic layer, and the GND contacts must contact the respective hard magnetic layer (analogous to FIG. 13b, in which the center contact 91 contacts the soft magnetic layer 501, and the GND tunneling contact 71 contacts the hard magnetic layer), or vice versa. Deviating from FIG. 14, the contacts may be positioned on the webs, instead of over the corners, and preferably on opposing webs. For example, the VCC contacts 81, 82, 83 and 84 can be positioned on the webs 31, 41, 51 and 61, and the GND contacts 71, 72, 73 and 74 can be positioned on the webs 33, 43, 53 and 63.

(69) The magnetization state of the sensor element is read out by way of resistance measurement of each individual winding here:

(70) The outer, first winding W1 is formed by the webs 31, 32, 33 and 34 comprising the GND contact 71 and the VCC contact 81.

(71) The second winding W2 is formed by the webs 41, 42, 43 and 44 comprising the GND contact 72 and the VCC contact 82.

(72) The third winding W3 is formed by the webs 51, 52, 53 and 54 comprising the GND contact 73 and the VCC contact 83.

(73) The fourth, innermost winding W4 is formed by the webs 61, 62, 63 and 64 comprising the GND contact 74 and the VCC contact 84.

(74) In this example as well, the separation between the two neighboring domain walls DW 111 and DW 112 is 540, as viewed in the cw direction.

(75) All features discernible from the description, the exemplary embodiments and/or the following drawings can be essential to the invention, both individually and in any arbitrary combination with each other.

LIST OF REFERENCE NUMERALS

(76) 1 revolution counter system

(77) 1a revolution counter

(78) 2 revolution sensor US

(79) 3 angle sensor WS

(80) 4 magnetic system

(81) 4a, 4c, 4e 4g, 4i 4k magnetic north poles

(82) 4b, 4d, 4f, 4h, 4j, 4l magnetic south poles

(83) 5 rotating shaft

(84) 5a magnet wheel

(85) 5b linear scale

(86) 6 electronics

(87) 7 power supply units

(88) 8 memory for the measured value of the angle sensor

(89) 8a measured value W8 of the angle sensor

(90) 9 memory for the measured values of the revolution sensor

(91) 9a table T9 containing measured values of the revolution sensor

(92) 10 memory for target value SLS (signal level sequences) of the revolution sensor stored in tabular form

(93) 10a-10d sub-tables containing target values for field angle quadrants 1 to 4

(94) 11 processing unit

(95) 20 spiral

(96) 21, 22 pointed ends of a spiral

(97) 25 conductor for initializing a magnetization pattern

(98) 26 constriction in conductor 25

(99) 27 multiply-wound, closed loop

(100) 28 direction of the reference magnetization

(101) 31, 32, 33, 34 webs of the outermost, first winding

(102) 35, 36, 37, 38 DW positions in the outermost, first winding

(103) 41, 42, 43, 44 webs of the second winding

(104) 45, 46, 47, 48 DW positions in the second winding

(105) 51, 52, 53, 54 webs of the third winding

(106) 55, 56, 57, 58 DW positions in the third winding

(107) 63, 64 webs of the fourth winding

(108) 65 DW position in the fourth winding

(109) 70, 71, 72, 73, 74 GND contacts

(110) 80, 81, 82, 83, 84 VCC contacts

(111) 91, 93, 95, 97, 99 center contacts of the different windings

(112) 111a 1st DW with an MP including 1 DW

(113) 111 1st DW with an MP including 2 or 6 domains walls

(114) 112 2nd DW with an MP including 2 or 6 domains walls

(115) 113 3rd DW with an MP including 6 domains walls

(116) 114 4th DW with an MP including 6 domains walls

(117) 115 5th DW with an MP including 6 domains walls

(118) 116 6th DW with an MP including 6 domains walls

(119) 133 resistor R33 (web 33) in the first winding

(120) 134 resistor R34 (web 34) in the first winding

(121) 143 resistor R43 (web 43) in the second winding

(122) 134 resistor R44 (web 44) in the second winding

(123) 153 resistor R53 (web 53) in the third winding

(124) 154 resistor R54 (web 54) in the third winding

(125) 163 resistor R63 (web 63) in the fourth winding

(126) 164 resistor R64 (web 64) in the fourth winding

(127) 202 chip comprising sensor element 2

(128) 221, 222 DW gaps

(129) 225a first bond contact connected to contact 25

(130) 225b second bond contact connected to contact 25

(131) 233 external resistor Rref33 for first winding

(132) 234 external resistor Rref34 for first winding

(133) 243 external resistor Rref43 for second winding

(134) 244 external resistor Rref44 for second winding

(135) 253 external resistor Rref53 for third winding

(136) 254 external resistor Rref54 for third winding

(137) 263 external resistor Rref63 for fourth winding

(138) 264 external resistor Rref64 for fourth winding

(139) 270 bond contact connected to GND contact 70

(140) 280 bond contact connected to VCC contact 80

(141) 291 bond contact connected to center contact 91

(142) 293 bond contact connected to center contact 93

(143) 295 bond contact connected to center contact 95

(144) 297 bond contact connected to center contact 97

(145) 301 zoomed-in corner between web 51 and web 44

(146) 302 quarter circle-like polygonal line

(147) 400 flow chart

(148) 501 soft magnetic layer

(149) 502 tunnel barrier

(150) 503 hard magnetic layer stack

(151) 504a insulating layer

(152) 504b insulating layer

(153) 505 gold electrode on tunneling contact