WO2021105741A1

WO2021105741A1 - Multi-turn contactless position sensing system and method

Info

Publication number: WO2021105741A1
Application number: PCT/IB2019/060137
Authority: WO
Inventors: Sylvain Guy Bertrand; Antoine Jean-Michel Lanot; Sebastien Jean Robert Marchio
Original assignee: Vishay S.A.
Priority date: 2019-11-25
Filing date: 2019-11-25
Publication date: 2021-06-03

Abstract

Systems and methods for high-resolution multi-turn non-contact rotary sensing are disclosed herein. A position sensing device may include a first rotary shaft coupled to a second rotary shaft such that a rotation of the first rotary shaft causes the second rotary shaft to rotate. First and second magnets may be coupled to the first and second rotary shafts, respectively. The first and second rotary shafts may move angularly relative to at least one magnetic sensor circuit that is not in contact with the first or second rotary shafts. The at least one magnetic sensor circuit may measure angular positions of the first and second magnets to determine the angular position and number of rotations by the first rotary shaft.

Description

MULTI -TURN CONTACTLESS POSITION SENSING SYSTEM AND

METHOD

FIELD OF INVENTION

[0001] The disclosure relates generally to position sensors, and more particularly, to systems and methods for high-resolution multi-turn non-contact rotary sensing.

BACKGROUND

[0002] Position sensors are used for example in mechanical and electromechanical applications to provide absolute position or displacement measurement information of an object. Angular or rotary sensors measure the angular mechanical position of a rotating object (e.g., by measuring position of a shaft connected to the rotation object), which can be used to determine other useful information such as frequency and speed of the object. Multi-turn rotary position sensors are used in variety of applications including automotive and electric motor applications, consumer electronics and appliances, industrial applications, wind generators, solar energy systems, test and measurement equipment, robotics, and medical equipment.

[0003] An example of a position sensor is a potentiometer that measures a voltage drop as electrical contact(s) slides along a resistive track, such that the (linear or rotational) position is proportional to voltage output. Although potentiometers are typically low cost, simple to produce and lightweight, they are susceptible to high vibration environments and the presence of foreign particles such as dust. Optical sensors, also referred to as encoders, operate by measuring a light beam through a grating using a photo detector to generate a position signal. Optical sensors can provide high resolution position measurements but are highly susceptible to foreign particles such that measurement fails if the lens or grating system becomes obscured.

[0004] Magnetic sensors use a magnetic detector to measure the change in magnetic field of a magnet as it moves relative to the magnetic detector, such that the magnetic field changes in proportion to their relative displacement. Magnetic sensors are contactless (non-contact) sensors because there is no contact between the detector and the rotor axis. An example of a magnetic angular position sensor is a Hall Effect sensor that generates, from a bar-shaped conducting material known as a Hall element, a voltage proportional to the intensity of a rotating magnet’s magnetic field passing through it. An existing non-contact multi-turn rotary position sensing device disclosed in U.S. Patent Publication No. US 2013/0015844 Al uses a single shaft and two magnetic sensor assemblies to generate two output values: a number of turns made by the shaft, and an angular position of the shaft within a given turn.

[0005] There is a desire for multi-turn rotary sensor system design that provides a single output measurement of object rotation over multiple turns with high resolution, and that is low cost, compact and low power.

SUMMARY

[0006] Systems and methods for high-resolution multi-turn non-contact rotary sensing are disclosed herein. A position sensing device may include a first rotary shaft coupled to a second rotary shaft such that a rotation of the first rotary shaft causes the second rotary shaft to rotate. First and second magnets may be coupled to the first and second rotary shafts, respectively. The first and second rotary shafts may move angularly relative to at least one magnetic sensor circuit that is not in contact with the first or second rotary shafts. The at least one magnetic sensor circuit may measure angular positions of the first and second magnets to determine the angular position and number of rotations by the first rotary shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 shows a high-level block diagram of an example contactless angular position sensing system, in accordance with the disclosures herein;

[0008] FIG. 2 shows cross-sectional diagrams of an example contactless angular position sensing system with perpendicular shafts and illustrating shaft rotation over time, in accordance with the disclosures herein; [0009] FIG. 3 shows cross-sectional diagrams of an example contactless angular position sensing system with parallel shafts, in accordance with the disclosures herein;

[0010] FIG. 4 shows a three-dimensional (3D) diagram of an example contactless angular position sensing system with perpendicular shafts, in accordance with the disclosures herein;

[0011] FIG. 5 shows an example integral housing that may be used contactless angular position sensing system, in accordance with the disclosures herein;

[0012] FIG. 6 shows a functional block diagram of example internal electronics that may be used in a contactless angular position sensing system, in accordance with the disclosures herein;

[0013] FIGs. 7A-7C show a set of example measurement signals over N turns of the entry shaft, in accordance with the disclosures herein;

[0014] FIGs. 8A-8C show another set of example measurement signals over N turns of the entry shaft, in accordance with the disclosures herein; [0015] FIGs. 9A-9E show different views of an example worm screw that can be used on the input shaft, in accordance with the disclosures herein; and [0016] FIGs. 10A-10E show different views of an example sprocket wheel that can be used as a gear, in accordance with the disclosures herein. [0017] These and other aspects, advantages, and novel features of the disclosed teachings will become apparent upon reading the following detailed description and upon reference to the accompanying drawings. In the drawings, similar elements have similar reference numerals.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Embodiments disclosed herein include contactless angular position sensing systems and methods for measuring the position of an object by measuring the rotation of an entry shaft connected to the object. The disclosed contactless angular position sensing systems and methods employ shaft-mounted magnets and one or more magnetic circuits to measure the rotation of the shafts over several turns. In an example, two magnets are mounted to two respective shafts such that the magnetic circuit measures the magnetic field of the magnets in two directions, longitudinally and transversely. In an example, the main shaft coupled to the external object drives, via a worm screw, the second shaft consisting of a sprocket wheel. The worm screw and sprocket wheel function as a reduction gear, where the larger sprocket wheel causes the second shaft to turn more slowly than smaller worm screw and hence the main shaft. Thus, the speed reduction in rotation between the main shaft and the second shaft is proportional to the ratio in diameters of the worm screw and the sprocket wheel. The reduction ratio between the two shafts makes it possible to determine the number of turns possible by the sensor and the sensor’s electric current. The magnetic circuit produces one or more sensor output signals (e.g., combined or separate signals) providing the angle of rotation of the external object coupled to the position sensor and the number of completed rotations by the external object. [0019] In the following, example contactless angular position sensing systems are shown and described including some, but not all, possible components. The example contactless angular position sensing systems described and illustrated herein may include other components not shown such as external objects, external systems, housings, shafts, gears, magnets, circuits, protection shields, sources of power etc. Moreover, the components and arrangements of components described are provided as examples and may be substituted with other components or arrangements with equivalent or similar functionality. Moreover, any of the components shown or described may be omitted.

[0020] FIG. 1 shows a high-level block diagram of an example contactless angular position sensing system 100, in accordance with the disclosures herein. The contactless angular position sensing system 100 receives as input the entry movement of the rotating object 102 that is subject to measurement and generates one or more output signals indicating the angular position and the number of turns of the rotating object. In an example, the measurement signal 115 may provide the turn count, and the measurement signal 113 may provide the accurate angular position within the current turn (e.g., the angular position of the object between the 4^th and 5^th turn). FIG. 1 shows three alternative example outputs based on the output signal 113 from magnetic circuit 112 (e.g., representing the rotational position of the object) and the output signal 115 of magnetic circuit 114 (e.g., representing the number of turns of the object): combined output signal 116A generated by modulating the output signal 113 using the output signal 115; combined output signal 116B generated by modulating the output signal 115 using the output signal of magnetic circuit 113; or two separate output signals 113 and 115 (i.e., no combining of the signals). The movement of the rotating object 102 may be input to the system by coupling or connecting the rotating object to a first rotary shaft 104 that follows the movement of the rotating object. The first rotary shaft 104 is further coupled to a second rotary shaft 106 such that the rotation of the first shaft 104 causes the second shaft 106 to rotate.

[0021] A first magnet 108 is coupled to the first shaft 104 and has a magnetization axis integral with the first shaft 104 such that the angular movement of the first shaft 104 gives rise to an angular rotation of the first magnet 108. For example, the first magnet 108 may be oriented such that the (first) magnetization axis of the first magnet 108 is coincident, or approximately coincident, with the (first) longitudinal axis of the first shaft 104. In this case, the north and south poles of the first magnet 108 are perpendicular to the axis of rotation of the first shaft 104. Similarly, a second magnet 110 is coupled to the second shaft 106 and has a magnetization axis integral with the second shaft 106 such that the angular movement of the second shaft 106 gives rise to an angular rotation of the second magnet 110. For example, the second magnet 110 may be oriented such that the (second) magnetization axis of the second magnet 110 is coincident, or approximately coincident, with the (second) longitudinal axis of the second shaft 106. In this case, the north and south poles of the second magnet 110 are perpendicular to the axis of rotation of the second shaft 106.

[0022] In an example, the rotary shafts 104 and 106 may be positioned not parallel (e.g., at a non-zero angle) relative to one another so that that the magnetic fields generated by the first and second magnets 108 and 110 are in different directions. For example, the first rotary shaft 104 may be positioned perpendicularly (at a 90 degree angle) to the second rotary shaft 106. In this case, a first magnetic field generated by the first magnet 108 is in a longitudinal direction relative to the first shaft 104 and the rotating object, while a second magnetic field generated by the second magnet 110 is in a transverse direction relative to the first shaft 104 and the rotating object. [0023] The shaft-mounted first and second magnets 108 and 110 move angularly with respect to the magnetic sensor circuits 112 and 114, which may be formed for example on one or more printed circuit boards (PCBs). The magnetic sensor circuits 112 and 114 comprise processing electronics and/or protection electronics to measure the angular position of the rotary shafts 104 and 106, and may perform additional processing including, but not limited to, signal amplification and/or analog-to-digital conversion. Although two magnetic sensor circuits 112 and 114 are shown, any number of magnetic sensor circuits (e.g., one or more than two) may be used similarly.

[0024] Magnetic sensor circuit 112 measures the rotational position of the first shaft 104 (and hence the object), by sensing a magnetic field of the first magnet 108, to generate a first rotational measurement signal indicating the rotation of the first shaft 104 over multiple turns of the first shaft 104. The output 113 of the magnetic sensor circuit 112 may be in analog format, such as a voltage signal, or in digital format, such as a pulse-width modulation (PWM) signal generated from the voltage signal. Magnetic sensor circuit 114 measures the rotational position of the second shaft 106, by sensing a magnetic field of the second magnet 110, to generate a second rotational measurement signal 115 of the second shaft 106 representing the number of turns of the first shaft 104, and hence the object. The magnetic sensor circuit 114 may generate an analog signal in volts tracking the number of turns of the first shaft 104, and may convert the analog signal into a digital format. In an example, either or both of the magnetic sensor circuits 112 and 114 may use any of the following types of magnetic sensor to measure the magnetic fields of the corresponding magnets 108 and 110: Hall effect sensors, anisotropic magnet resistance (AMR) sensor, giant magnetoresistance (GMR) sensor, tunnel magneto resistance (TMR) sensor. Although magnetic sensors are discloses, non-magnetic sensors may be used, such as absolute optical encoders. For example an optical encoder may be used in sensor circuit 112 or

114 to count the number of turns of the first shaft 104.

[0025] As discussed above, one or more output signals may be generated by the example contactless angular position sensing system 100, and three examples are shown. In an example, the first rotational measurement signal 113 of the first shaft 104 modulates the second rotational measurement signal

115 of the second shaft 106 to generate a single combined output signal 116A indicating the angle rotation and the number of rotations or turns of the rotating object (e.g., see example in FIG. 8C). In another example, the second rotational measurement signal 115 of the second shaft 106 modulates the first rotational measurement signal 113 of the first shaft 103 to generate a single combined output signal 116B indicating the angle rotation and the number of rotations or turns of the rotating object (e.g., see example in FIG. 7C). In another example, the signals 113 and 115 are provided as two separate outputs without combining them (e.g., see example in FIGs. 7A and 7B, or FIGs. 8A and 8B).

[0026] In an example, the analog measurement signal 115 provides the turn count, and the analog measurement signal 113 provides the accurate angular position within the current turn (e.g., the angular position of the object between the 4^th and 5^th turn). The resolution of the output signal (s) (e.g., combined signal 116A, combined signal 116B or signal 113 and signal 115) is determined on the basis of the magnetic sensor circuits 112 and 114 and the rotary shafts 104 and 106. In an example, the resolution the digital output (116A, 116B, or 113 and 115) of contactless angular position sensing system 100 is 12 bits per turn of the object plus a turn counter. In an example, if the magnetic sensor 112, measuring the angular position of the object, is a 10 turn sensor, the resolution is log₂(10 _* 2¹²) = 15.32 bits, which is equivalent to 40960 output values over 3600°. In another example, if the magnetic sensor 112 is a 16 turn sensor, the resolution is log₂(16 _* 2¹²) = 16 bits, which is equivalent to 65536 output values over 5760°. Thus, the disclosed contactless angular position sensing system 100 is able to achieve high resolution and high accuracy of the rotational measurement.

[0027] FIG. 2 shows cross-sectional diagrams of an example contactless angular position sensing system 200 showing shaft rotation over time, in accordance with the disclosures herein. The contactless angular position sensing system 200 includes the first magnet 208 mounted on and aligned longitudinally with the first rotary input shaft 204 and the second magnet 210 mounted on and aligned longitudinally with a second rotary shaft, not visible, but located behind (similar to the system 100 described in FIG. 1). The first rotary shaft 204 is the input or entry shaft connected to the rotating object (not shown). The transverse axis of the first rotary shaft 204 is perpendicular to the transverse axis of the second rotary shaft 206, which is coupled gear 207 (the second rotary shaft 206 is located behind magnet 210 in FIG. 2). The first rotary shaft 204 further includes a worm screw 205 that rotates, via gear 207, the second rotary shaft 206. The diameter of the gear 207 is greater than the diameter of the first rotary shaft 204 so that multiple turns of the first rotary shaft 204 corresponds to a single turn of the second rotary shaft 206. In an example, the ratio of the dimensions of the first rotary shaft 204 to gear 207 is such that the secondary rotary shaft 206 completes one turn for every ten turns completed by the first rotary shaft 204. FIG. 2 illustrates the rotating positions of the shafts 204 and 206 and the magnets 208 and 210 over time (shown at three example time instances, ti, ti+t2 and ti+t2+t3, where ti, t2, t3 > 0).

[0028] The contactless angular position sensing system 200 includes a magnetic sensor circuit 212 to measure the angular position of the first rotary shaft 204, by sensing the magnetic field of the corresponding magnet 208. In this example, the magnetic sensor circuit 212 is located opposite the longitudinal axis of the first rotary shaft 204 (e.g., so that the conductor of a Hall effect sensor is perpendicular to the direction of electron flow of the magnetic field of magnet 208), however the magnetic sensor circuit 212 may be positioned in other locations in the contactless angular position sensing system 200. The contactless angular position sensing system 200 includes a second magnetic sensor circuit, not shown in FIG. 2, that measures the angular position of the second rotary shaft 206. The second magnetic sensor circuit may be located opposite the longitudinal axis of the second rotary shaft 206 (i.e., opposite magnet 210). Although two magnetic sensor circuits are described, any number of magnetic sensor circuits (e.g., one or more than two) may be used similarly.

[0029] In the example of FIG. 2, the shafts 204 and 206 are perpendicular to one another. FIG. 3 shows a cross-sectional diagram of an example contactless angular position sensing system 300 where the shafts 304 and 306 are parallel, in accordance with the disclosures herein. The contactless angular position sensing system 300 includes the first magnet 308 mounted on and aligned longitudinally with the first rotary input shaft 304 and the second magnet 310 mounted on and aligned longitudinally with the second rotary shaft 306. The first rotary shaft 304 is the input or entry shaft connected to the rotating object (not shown). In this case, the transverse axis of the first rotary shaft 304 is parallel to the transverse axis of the second rotary shaft 306.

[0030] A gear 307 (e.g., cogwheel, sprocket) centered on and coupled to the second rotary shaft 306 is turned by the worm screw 305 on the first rotary shaft 304, for example by interlocking the threads of the worm screw 305 with the teeth of the gear 307. In an example, the diameter of the gear 307 may be greater than the diameter of the first rotary shaft 304 so that multiple turns of the first rotary shaft 304 corresponds to a single turn of the second rotary shaft 306. In an example, the ratio of the dimensions of the first rotary shaft 304 to the gear 307 is such that the secondary rotary shaft 306 completes one turn for every ten turns completed by the first rotary shaft 304. In order to achieve a ratio of ten turns (or any number of turns, such as 3, 5, or 16 turns) of input shaft 304 for one turn of the gear 307, a mechanical matching may be created between the diameter of the threaded part of the input shaft 304 (e.g., a worm screw) and aspects of the gear 307 such as number of teeth, module and/or pitch. FIGs. 9A-9E show different views of an example worm screw that can be used on the input shaft 304, and FIGs. 10A- 10E show different views of an example sprocket wheel that can be used as gear 307. FIG. 9A shows the side cross-sectional view of the worm screw; FIG. 9B shows the side-view of the worm screw; FIG. 9C shows the front cross- sectional view of the worm screw; and FIGs. 9D and 9E shows three- dimensional (3D) diagrams of the worm screw from two different angles. FIG. 10A shows the side cross-sectional view of the sprocket wheel; FIG. 10B shows the side-view of the sprocket wheel; FIG. IOC shows the front cross-sectional view of the sprocket wheel; and FIGs. 10D and 10E show 3D diagrams of the sprocket wheel from two different angles. FIGs. 9A-9E and 10A-10E serve only as examples, and other types of gears may similarly be used.

[0031] With reference to FIG. 3, magnetic sensor circuits 312 and 314, respectively located opposite the longitudinal axes of the first and second rotary shafts 304 and 306, measure the angular position of the shafts 304 and 306 by sensing the magnetic field of the corresponding magnets 308 and 310. The example contactless angular position sensing system 300 further includes a housing 320, and a shield 322 to provide protection between the magnets 308 and 310 and/or protection between the sensor circuits 312 and 314. For example, the shield 322 may be made of a specific material, such as soft iron, and may have a specific shape and thickness in order to block external magnetic fields. Unwanted magnetic fields that should be shielded may include parasitic magnetic fields or magnetic fields imposed by other nearby components in the same or neighboring systems (e.g., generated by magnets of a nearby direct current (DC) motor).

[0032] FIG. 4 shows a 3D diagram of an example contactless angular position sensing system 400 with perpendicular shafts, in accordance with the disclosures herein. The configuration of the example contactless angular position sensing system 400 generally corresponds to the example contactless angular position sensing system 200 shown in FIG. 2. FIG. 4 shows the components of the system 400 separated out into two parts under housing 420a and housing 420b in order to illustrate the internal components, whereas in implementation housing 420a and housing 420b is one integral continuous housing (see housing 420 in FIG. 5) and the worm screw 405 interlocks with the sprocket wheel 407 (equivalent to the arrangement of the housing 220, worm screw 205 gear 207 and other components shown in FIG. 2). In an example, the housing 420a and 420b may be manufactured in two parts containing a joint plane then may be assembled together to form the final integral housing 420. More generally, the housing 420 can be made in one or several pieces.

[0033] The angular position of an external object (not shown) is defined by the rotation of the entry shaft 404 coupled to a second shaft 406 inside the housing 420a and 420b and by internal electronic including magnetic sensor circuits 412 and 414. At least a portion (e.g., all) of the entry shaft 404 is located in housing 420a and at least portion (e.g., all) of the second shaft 406 is located in housing 420a and 420b. The entry shaft 404 and/or the second shaft 406 may be, for example, cylindrical or cubic in shape. Mounting of the housing parts 420a and 420b may provide guiding for the second shaft 406. [0034] The entry shaft 404 may comprise a portion with a worm screw

405, and the second shaft 406 may comprise a portion with a sprocket wheel 407 (e.g., mounted to the end of the second shaft 406). In an example, the entire entry shaft 404 may be a worm screw 405, and/or the entire second shaft 406 may be a sprocket wheel 407. The entry shaft 404 is coupled to the external object and drives, through the worm screw 405, the second shaft 406 by turning the sprocket wheel 407 . The central axis of the sprocket wheel 407 may be positioned in any position relative to the worm screw 405 by correctly choosing the angle of inclination of the teeth of the sprocket wheel 407 and the nets of the worm screw 405. In one example, the central axis of the sprocket wheel 407 may at a 90° angle to the worm screw 405 (as shown in FIGs. 2, 4, 5), however any other mechanically feasible angle is possible assuming the desired reduction ratio is achieved. The reduction ratio between the entry shaft 404 and the second shaft 406 is determined by the reduction ratio between the worm screw 405 and the sprocket wheel 407, and more particularly by the ratio of the number of threads on the worm screw 405 to the number of teeth on the sprocket wheel 407. Thus, the reduction ratio can be set by selecting the threads on the worm screw 405 relative to the teeth on

-li the sprocket wheel. The reduction ratio enables the internal electronics to determine the number of turns of the object as well as the electric stroke of the magnets 408 and 410.

[0035] The contactless angular position sensing system 400 measures the rotation of the shaft 404 over several turns. The internal electronics, comprising magnetic sensor circuits 412 and 414, are coupled with magnets 408 and 410 integral with shafts 404 and 404, in order to measure a magnetic field in two directions, longitudinally and transversely with respect to shaft 404 and hence the rotating object. The degrees of rotation of the second shaft 406, N degrees, is proportional to the number of turns of the first shaft 404. [0036] The main shaft 404 is integral with the magnet 408 having a magnetization axis coincident with the longitudinal axis of the main shaft 404. The secondary shaft 406 is integral with the magnet 410 having a magnetization axis perpendicular to the longitudinal axis of the main shaft 404. The housing 420a and 420b comprises a threaded fastening system (or bushing) 434 at the main shaft 404 to secure, guide and/or hold the main shaft 404 to the housing 420a. The threaded fastening system 434 allows adjustment and coaxiahty of the external rotating object or system and the entry shaft 404 and can be configured or adjusted by the user. The threaded fastening system 434 can be used to mount the contactless angular position sensing system 400 to an external structure or system.

[0037] The magnetic circuits 412 and 414 may be respectively mounted to the housing 420a and 420b at locations 430 and 432 and generate and provide the output signal to the user (for example to a user processor and/or user interface) via terminals 426. One or more screws 423 may be used to fix the two parts of the housing 420a and 420b together (other mechanisms other than screws may be used, such as ultrasonic welding).

[0038] The housing 420a and 420b may correspond to the example integral housing 420 shown in FIG. 5. The housing 420 may have curved surfaces (e.g., if a molding process is used to form the housings 420a and 420b) on the outside and/or inside to match the manufacturing process. The housing 420 includes location 442 for mounting the bushing 434, location 444 for mounting the second shaft 406, and locations 446 for mounting the output terminals 426. In an example, housing 420 may be a molded plastic part and may be made by 3D-printing or assembly of several parts. In an example, the bushing 434 may be embedded in the housing 420, or over-molded with a plastic housing piece 420a, or crimped.

[0039] With reference to FIG. 4, the magnetic circuits 412 and 414 may be formed on separate PCBs and mounted at different locations 430 and 432 opposite the respective shafts 404 and 406. Magnetic sensor circuit 412 measures the rotational position of the first shaft 404 (and hence the object), by sensing a magnetic field of the first magnet 408, to generate a first rotational measurement signal. Magnetic sensor circuit 414 measures the rotational position of the second shaft 406, by sensing a magnetic field of the second magnet 410, to generate a second rotational measurement signal of the second shaft 406 representing the number of turns of the first shaft 404, and hence the object.

[0040] Additional circuitry (not shown) connecting magnetic circuits 412 and 414 enables the magnetic circuit 412 to provide to the second magnetic sensor circuit 114 the first rotational measurement signal of the first shaft 404. The second magnetic sensor circuit 414 combines the first rotational measurement signal of the first shaft 404 and the second rotational measurement signal of the second shaft 404 to generate a combined output signal indicating the angle rotation and the number of rotations or turns of the rotating object. The second magnetic sensor circuit 414 may provide the combined output signal to the user via output terminals 426. Although magnetic sensor circuits 412 and 414 are shown in FIG. 4 as being located in two locations 430 and 432 and on separate PCBs, the complete magnetic sensor circuit may be implemented for example on a common PCB or on more than two PCBs (e.g., the circuit for combining the first and second rotational measurement signals may be located on a third PCB).

[0041] FIG. 6 shows a functional block diagram of example internal electronics 600 that may be used in a contactless angular position sensing system, in accordance with the disclosures herein. For example, the internal electronics 600 may be implemented in the magnetic sensor circuits shown in FIGs. 1-4 and on one or more PCBs. The internal electronics 600 measure the magnetic fields of the shaft-mounted magnets, process the measurements (e.g., combine measurements, convert signals from analog to digital, etc.), protect the sensor circuits and generate and provide the output signal 616 indicating the objects rotation. Power is provided to data processing microcircuits 652 and 662, where V+ is the high input voltage (e.g., +5V or + 10V) and V- is low input voltage (e.g., 0V equal to ground or -5V).

[0042] Magnetic sensor circuit 612 may be an integrated circuit and may include a data processing microcircuit 652 to measure the rotation of the entry shaft and provide a first rotational measurement signal 653 in digital format representing the angular position of the entry shaft as it rotates over time. For example, data processing microcircuit 652 may include a Hall effect sensor that generates a voltage proportional to the magnetic field of the magnet passing through it and circuitry to convert the measured voltage into an electrical signal 653 (e.g., a PWM signal) representing the angular position of the entry shaft as it rotates over time.

[0043] Magnetic sensor circuit 614 may be an integrated circuit and may include a data processing microcircuit 662 to measure the rotation of the second shaft and provide a second rotational measurement signal 663 in analog format. For example, data processing microcircuit 662 may include a Hall effect sensor that generates an analog voltage signal 663 proportional to the magnetic field of the magnet passing through it from the second sensor on the second shaft. The sensor protection circuits 654 and 664 may provide protection against deleterious effects such as reverse polarity, overvoltage, or transients

[0044] Assembly circuit 615 may combine the PWM signal 655 of the rotation on the main axis of the entry shaft with the analog signal 665 representing the number of rotations of the entry shaft by taking the product (e.g., Boolean multiplication, where the PWM signal at low level, such as 0V, is treated as logic Ό’ and at high level, such as IV or 5V, logic T) of the two signals to generate combined output signal 616 indicating the angle rotation and the number of rotations or turns of the rotating object. The combined output signal 616 may be read by a user interface to provide the user with the angle rotation of the rotating object coupled to the position sensor. Examples of the PWM signal 655, analog signal 665, and combined output signal 616 over N turns of the entry shaft are shown FIGs. 7A-7C. In an example, the PWM signal 655 may have a range of 360° and a resolution of 0.09°, the analog signal 665 may have a range of 3600° and a resolution of 1°, and the combined signal 616 may have a range of 3600° and a resolution of 0.09°. Although a combined output 616 is shown, signals 655 and 665 may be provided as separate outputs (in analog form or converted to digital form). [0045] The duty cycle of the PWM signal 655 gives the angular position of the entry shaft with high accuracy (due to the high resolution and fine mechanics). The amphtude of the analog signal 665 (in volts) is proportional to the number of turns completed by the entry shaft, where 1/N turns of the second shaft corresponds to 1 turn of the entry shaft (i.e., N is the gear ratio or reduction ratio). The analog signal 665 is modulated by the PWM 655 to generate the combined output signal 616 that gives angular position information as well as the number of rotations.

[0046] FIGs. 7A-7C show one example of the shape and type (analog versus digital) of signals coming from the sensing circuits (analog / analog for example) such that other combinations of shapes and types of signals can be mixed with a suited electronic device in order to get a single output signal containing several pieces of information including the number of turns already completed and angular position with good resolution of the ongoing turn. FIGs. 8A-8C show another set of example measurement signals over N turns of the entry shaft for an alternate configuration to that shown in FIG. 6. In the example of FIGs. 8A-8C, a magnetic circuit coupled with the magnet of the entry shaft supplies an analog signal 855 (in volts). The amplitude of the analog signal 855 provides the angular position of the entry shaft within each turn of the entry shaft with high accuracy. A magnetic circuit coupled with the magnet of the second shaft supplies a PWM signal 865, such that the duty cycle of the PWM signal 865 provides the number of turns of the first shaft. The analog signal 855 is modulated by the PWM signal 865 (i.e., the product of the PWM signal 865 and the analog signal 855) to generate the combined output signal 816 including the precision of angular position and number of turns of the first shaft (and correspondingly the rotating object). As explained above, the combining the PWM signal and analog signal is optional, and separate signals may be provided as output.

[0047] In any of the examples, disclosed herein, redundant sensor circuits may be used to provide more robust measurement information. For example, two separate magnetic sensing circuits (i.e., each magnetic sensing circuit independently measures the rotation of both shafts) can be used

the housing of the contactless position sensing system thus supplying two independent and redundant output signals each indicating angular position with good resolution of the ongoing turn and the number of turns completed. In another example, different combinations of different types of magnetic sensing circuits may be implemented within the same contactless angular position sensing system, such as using both Hall effect sensors and magnetoresistance sensors. In the example disclosures herein, the size and combinations of components may be adaptable according to user requirements such as size, length, and mode of attachment. k k k

Claims

CLAIMS What is claimed is:

1. A position sensing device, comprising: a first rotary shaft having a first longitudinal axis; a second rotary shaft having a second longitudinal axis, the first rotary shaft coupled to the second rotary shaft such that a rotation of the first rotary shaft causes the second rotary shaft to rotate; a first magnet coupled to the first rotary shaft and having a first magnetization axis aligned with the first longitudinal axis of the first rotary shaft; a second magnet coupled to the second rotary shaft and having a second magnetization axis aligned with the second longitudinal axis of the second rotary shaft; and at least one magnetic sensor circuit that is not in contact with the first rotary shaft and is not in contact with the second rotary shaft, wherein the first rotary shaft and the second rotary shaft move angularly relative to the at least one magnetic sensor circuit, and wherein the at least one magnetic sensor circuit is configured to: measure angular position of the first magnet to generate a first angular measurement, measure angular position of the second magnet to generate a second angular measurement representing a number of rotations by the first rotary shaft, and combine the first angular measurement and the second angular measurement to generate a combined angular measurement indicating the angular position of the first rotary shaft and the number of rotations of the rotary shaft.

2. The position sensing device of claim 1, wherein the first rotary shaft is coupled to an external rotating object that drives the rotation of the first rotary shaft.

3. The position sensing device of claim 1, wherein the first rotary shaft comprises a portion with a worm screw, the second rotary shaft comprises a portion with a sprocket wheel, and wherein the rotation of the worm screw causes the rotation of the sprocket wheel.

4. The position sensing device of claim 3, wherein a reduction ratio between the first rotary shaft and the second rotary shaft is proportional to the ratio of a number of threads of the worm screw to a number of teeth on the sprocket wheel.

5. The position sensing device of claim 4, wherein a resolution of the combined angular measurement is determined based on the reduction ratio between the first rotary shaft and the second rotary shaft.

6. The position sensing device of claim 1, the at least one magnetic sensor circuit comprising data processing circuitry and sensor protection circuitry.

7. The position sensing device of claim 1, the at least one magnetic sensor circuit comprising at least one microcircuit.

8. The position sensing device of claim 1, the at least one magnetic sensor circuit located on at least one printed circuit board (PCB).

9. The position sensing device of claim 1, the at least one magnetic sensor circuit comprising at least one Hall effect sensor configured to measure magnetic fields of the first magnet and the second magnet.

10. The position sensing device of claim 1, the at least one magnetic sensor circuit comprising: a first magnetic sensor circuit located opposite the first longitudinal axis of the first rotary shaft and configured to measure the angular position of the first magnet by sensing a magnetic field of the first magnet; and a second magnetic sensor circuit located opposite the second longitudinal axis of the second rotary shaft and configured to measure the angular position of the first magnet by sensing a magnetic field of the second magnet.

11. The position sensing device of claim 10, wherein the first magnetic sensor circuit is configured to generate a digital electrical pulse width modulation (PWM) signal proportional to rotation of the first rotary shaft based on the angular position of the first magnet.

12. The position sensing device of claim 11, wherein the second magnetic sensor circuit is configured to generate an analog electrical signal proportional to rotation of the second rotary shaft based on the angular position of the second magnet.

13. The position sensing device of claim 12, wherein the second magnetic sensor circuit is further configured to combine the first angular measurement and the second angular measurement by taking a product of the digital electrical pulse width modulation (PWM) signal with the analog electrical signal.

14. The position sensing device of claim 10, wherein the first magnetic sensor circuit is configured to generate an analog electrical signal proportional to rotation of the first rotary shaft based on the angular position of the first magnet.

15. The position sensing device of claim 14, wherein the second magnetic sensor circuit is configured to generate a digital electrical pulse width modulation (PWM) signal proportional to rotation of the second rotary shaft based on the angular position of the second magnet.

16. The position sensing device of claim 15, wherein the second magnetic sensor circuit is further configured to combine the first angular measurement and the second angular measurement by taking a product of the digital electrical pulse width modulation (PWM) signal with the analog electrical signal.

17. The position sensing device of claim 1, further comprising a housing encompassing at least in part the first rotary shaft, the second rotary shaft, the first magnet, the second magnet, and the at least one magnetic sensor circuit.

18. The position sensing device of claim 17, wherein the housing further comprises a threaded end configured to guide and hold the first rotary shaft.

19. The position sensing device of claim 17, wherein the housing further comprises curved walls.

20. The position sensing device of claim 1 further comprising: at least one output terminal to provide the combined angular measurement to a user.