Apparatus, method and system for determining magnet position

Abstract

The invention relates to a device, method and system for determining a position of a magnet. A position sensor device for determining a two-dimensional position of a magnet, the magnet being movable in a plane and the magnet generating a magnetic field; the position sensor device comprising: a semiconductor substrate comprising a plurality of magnetic sensors configured for determining three orthogonal magnetic field components (Bx, By, Bz) at a single location; and wherein the semiconductor substrate further comprises a processing circuitry configured for determining the two-dimensional position (R, θ; X, Y) based on the three orthogonal magnetic field components. A control rod assembly comprising such a position device. A method of determining the two-dimensional position.

Description

Technical Field

[0001] The present invention relates generally to the field of magnetic position sensor systems, devices, and methods, and more particularly to magnetic position sensor devices, systems, and methods for determining the 2D position of a magnet movable in a 2D plane. The present invention also relates to position sensor systems in which the magnet is attached to a thumbstick. Background Art

[0002] Magnetic position sensor systems, particularly linear position sensor systems or angular position sensor systems, are known in the art. Many variations of position sensor systems exist, addressing one or more of the following requirements: using a simple or inexpensive magnetic structure, using a simple or inexpensive sensor device, being able to measure over a relatively large range, being able to measure with high accuracy, requiring only simple arithmetic, being able to measure at high speed, being highly robust to positioning errors, being highly robust to external interference fields, providing redundancy, being able to detect errors, being able to detect and correct errors, having a good signal-to-noise ratio (SNR), having only one degree of freedom (translation or rotation), having two degrees of freedom (e.g., one translation and one rotation, or two rotations), etc.

[0003] In many known systems, the system has only one degree of freedom of motion, for example, rotation about a single axis, or translation along a single axis.

[0004] Magnetic position sensor systems in which a magnet has at least two degrees of freedom are also known in the art, for example from EP3875915 (A1), which discloses a magnet that is movable along an axis and independently rotatable about said axis, or from US2021 / 0110239 (A1), which discloses a circuit comprising at least one trained neural network for determining information about the position, attitude, or orientation of a magnet. These examples show that position sensor systems in which a magnet has at least two degrees of freedom are much more complex than systems with only one degree of freedom.

[0005] There is always room for improvement or substitution. Summary of the Invention

[0006] Embodiments of the present invention provide a position sensor device, a position sensor system, and a method for determining the two-dimensional position of a magnet movable in a two-dimensional plane. For example, the two-dimensional position can be expressed in the form of a distance D relative to a reference position and an angle θ relative to a reference direction, or in the form of two Cartesian coordinates X and Y.

[0007] It is an object of certain embodiments of the present invention to provide a position sensor device, a position sensor system and a method for determining the position using a relatively small number of sensor elements.

[0008] It is an object of particular embodiments of the invention to provide a position sensor device, a position sensor system and a method for determining the position in a simple manner, e.g. using relatively simple arithmetic (without using neural networks).

[0009] It is an object of particular embodiments of the invention to provide a position sensor device, a position sensor system and a method for determining the position using one or more analytical formulas.

[0010] It is an object of particular embodiments of the invention to provide a position sensor device, a position sensor system and a method for determining the position in a manner that only requires a small semiconductor substrate, e.g. less than 4.0 mm 2 , or less than 3.5 mm 2 , or less than 3.0 mm 2 , or less than 2.5 mm 2 , or less than 2.0 mm 2 , or less than 1.5 mm 2 .

[0011] It is an object of particular embodiments of the invention to provide a position sensor device, a position sensor system and a method for determining the position in a manner that is highly insensitive to temperature variations and / or demagnetization.

[0012] These and other objects are achieved by embodiments of the invention.

[0013] According to a first aspect, the invention provides a position sensor device for determining a two-dimensional position (e.g. R, Q or X, Y) of a magnet, the magnet being movable in a plane and the magnet generating a magnetic field; the position sensor device comprising: a semiconductor substrate comprising a plurality of magnetic sensors configured for determining three orthogonal magnetic field components (e.g. Bx, By, Bz) at a single position; and wherein the semiconductor substrate further comprises a processing circuitry configured for determining the two-dimensional position based on (e.g. only based on) the three orthogonal magnetic field components.

[0014] In embodiments, the plurality of magnetic sensor elements comprises four horizontal Hall elements arranged on a virtual circle, near an outer periphery of an integrated magnetic flux concentrator (IMC), e.g. having a disc shape.

[0015] In embodiments, the plurality of magnetic sensor elements comprises one horizontal Hall element having a maximum sensitivity axis in a first direction (e.g. Z) oriented perpendicular to the semiconductor substrate; and two vertical Hall elements having a maximum sensitivity axis in a second direction (e.g. X) parallel to the semiconductor substrate; and two vertical Hall elements having a maximum sensitivity axis oriented in a third direction (e.g. Y) parallel to the semiconductor surface and perpendicular to the second direction (e.g. X).

[0016] In case the sensor structure comprises one horizontal Hall element and two vertical Hall elements, the vertical Hall elements are preferably arranged on opposite sides of the horizontal Hall element, such that the horizontal Hall element is in between them, and preferably the signals from these vertical Hall elements are added to improve the signal-to-noise ratio (SNR).

[0017] In embodiments, the two-dimensional position is determined as a lateral distance (e.g. R) from a predefined position; and an azimuth angle (e.g. Θ) with respect to a predefined direction (e.g. X); and wherein said distance is determined as a first function of a first numerator and a first denominator; and at least one of the following options: i) wherein each of the first numerator and the first denominator is a function or expression of at least one magnetic field component (e.g. Bx, By, Bz); ii) wherein the first numerator is a function of in-plane magnetic field components (e.g. Bx, By) and the denominator is a function of an out-of-plane magnetic field component (e.g. Bz); iii) wherein the first numerator is a function of a sum of squares of in-plane magnetic field components (e.g. Bx, By) and the denominator is a function of an out-of-plane magnetic field component (e.g. Bz); and wherein said azimuth angle (e.g. Θ) is determined as a second function of a second numerator and a second denominator; and at least one of the following options: iv) wherein each of the second numerator and the second denominator is a function or expression of at least one in-plane magnetic field component (e.g. Bx, By); v) wherein the second numerator is one of the in-plane magnetic field components (e.g. Bx) and the second denominator is the other one of said in-plane magnetic field components (e.g. By).

[0018] In embodiments, the two-dimensional position is determined as a lateral distance R from a predefined position; and an azimuth angle Θ with respect to a predefined direction (e.g. X); wherein said distance R is determined according to the following formula:

[0019] R = K5 * atan2[√(sqr(Bx) + sqr(By)), K2 * (Bz - K3)], wherein K2, K3, K5 are predefined constants; and wherein said azimuth angle Θ is determined according to the following formula: Θ = atan2(By, Bx).

[0020] The advantage is that the azimuth angle can be calculated as the ratio of the two magnetic field components, as this ratio is highly insensitive to demagnetization, temperature changes, and axial position shifts.

[0021] The advantage of this embodiment is that the result is more accurate, but at the expense of a slightly more complex formula, which involves the square root of the sum of two squares. The advantage is that the formula for the distance is based on the ratio of the numerator and denominator (implicit in the atan2 function), both of which will vary in the same way with changes in temperature, demagnetization, etc.

[0022] If desired, the R and θ values ​​can be converted to Cartesian coordinates (X, Y) using the following formulas: X = R*cos(θ), Y = R*sin(θ).

[0023] In a particular embodiment, the value of K2 is equal to 1.0 and the value of K3 is equal to 0.0, in which case the formula can be simplified to: R = K5*atan2[√(sqr(Bx)+sqr(By)),Bz]. This formula is particularly advantageous and provides highly accurate results, moreover over a relatively large range of up to 2.0 times the magnet radius or even up to 2.5 times the magnet radius.

[0024] In an embodiment, the two-dimensional position is determined as a lateral distance R from a predefined position; and an azimuth angle θ about a predefined direction (e.g., X); wherein the distance R is determined according to the following formula: R=K1*arccos(K2*(Bz-K3)), where K1, K2, K3 are predefined constants that can be determined by design, by simulation, or by calibration; and wherein the azimuth angle θ is determined according to the following formula:

[0025] θ=atan2(By,Bx).

[0026] The advantage of this distance formula is that it can be used over a larger range.

[0027] The advantage is that the azimuth angle can be calculated as the ratio of the two magnetic field components, because this ratio is highly insensitive to demagnetization, temperature changes, and axial position offsets. If desired, the R and θ values ​​can be converted to Cartesian coordinates (X, Y) using the following formulas: X = R * cos (θ), Y = R * sin (θ).

[0028] In an embodiment, the magnet is a two-pole axially magnetized cylindrical magnet.

[0029] The advantage of using an axially magnetized cylindrical magnet is that rotation of the magnet about its magnetization axis does not change the magnetic field.

[0030] In an embodiment, the magnet may be moved or displaced laterally in a plane with its axis perpendicular to the semiconductor surface.

[0031] For the sake of completeness, it is noted that the magnet can be able to rotate around its axis, or can not be able to rotate around its axis, but because the magnet is axially magnetized, this does not change the magnetic field.

[0032] According to a second aspect, the application also provides a position sensor system, the system comprising: a position sensor device according to the first aspect; said magnet, said magnet being movably mounted in a plane parallel to a semiconductor substrate of the position sensor device.

[0033] In embodiments, the position sensor system further comprises a mechanical assembly comprising or connected to said magnet and configured for allowing the magnet to move in a direction parallel to said semiconductor substrate while keeping the axis of the magnet substantially perpendicular to the semiconductor substrate.

[0034] The mechanical assembly can comprise an elastic material, such as silicone or a polymer. The mechanical assembly can further comprise a rod or control rod.

[0035] According to a third aspect, the application also provides a control rod assembly, the control rod assembly comprising a position sensor system according to the second aspect, wherein the mechanical assembly further comprises a control rod.

[0036] According to a fourth aspect, the application also provides a method of determining a two-dimensional position (e.g. R, Θ; or X, Y) of a magnet that is movable in a plane parallel to a semiconductor substrate, the method comprising the steps of: a) measuring three orthogonal magnetic field components (e.g. Bx, By, Bz) at a single location on said semiconductor substrate; b) determining said two-dimensional position (e.g. R, Θ; or X, Y) based on (e.g. only on) said three orthogonal magnetic field components (e.g. Bx, By, Bz).

[0037] In embodiments, step b) comprises: i) determining a lateral distance R from a predefined reference position according to the following formula: R = K1 * arccos(K2 * (Bz - K3)), wherein K1, K2, K3 are predefined constants; and ii) determining an azimuth angle Θ with respect to a predefined direction (e.g. X) according to the following formula: Θ = atan2(By, Bx).

[0038] The values of the predefined constants can be determined by design, by simulation or by calibration, and can be hardcoded in a software program, or can be stored as parameters in a non-volatile memory during calibration, from which they can be retrieved during actual use of the sensor device. This also applies when using other formulas.

[0039] In an embodiment, step b) comprises: i) determining a lateral distance R from a predefined reference position according to the following formula: R = K4*arcsin(√[sqr(Bx)+sqr(By)]), where K4 is a predefined constant; and ii) determining an azimuth angle θ with respect to a predefined direction (e.g., X) according to the following formula: θ = atan2(By,Bx).

[0040] The same comments about predefined constants apply here as well.

[0041] In an embodiment, step b) comprises: i) determining a lateral distance R from a predefined reference position according to the following formula:

[0042] R=K5*atan2(√[sqr(Bx)+sqr(By)],K2*(Bz-K3)), where K2, K3, K5 are predefined constants; and ii) determining the azimuth angle θ relative to a predefined direction (e.g., X) according to the following formula: θ=atan2(By,Bx).

[0043] The same comments about predefined constants apply here as well.

[0044] In a particular embodiment, the value of K2 is equal to 1.0 and the value of K3 is equal to 0.0, in which case the formula can be simplified to: R=K5*atan2[√(sqr(Bx)+sqr(By)),Bz].

[0045] According to a fifth aspect, the present invention further provides a method for determining a two-dimensional position (e.g., R, θ; or X, Y) of a magnet movable in a plane parallel to a semiconductor substrate, the method comprising the following steps: a) measuring a first magnetic field component (e.g., Bz1) oriented in a direction perpendicular to the semiconductor substrate at a first sensor position on the semiconductor substrate; b) measuring a second magnetic field component (e.g., Bz2) oriented in the direction perpendicular to the semiconductor substrate at a second sensor position different from the first sensor position; c) determining which of the first magnetic field component and the second magnetic field component (e.g., Bz1, Bz2) is the largest, and selecting the corresponding position as the selected sensor position. device position; d) also measuring a third magnetic field component (e.g., Bx) parallel to the semiconductor substrate and a fourth magnetic field component (e.g., By) parallel to the semiconductor substrate and perpendicular to the third magnetic field component (e.g., Bx) at the selected sensor position; e) determining a two-dimensional offset of the magnet relative to the selected sensor position based on the largest magnetic field component of the first magnetic field component (e.g., Bz1) and the second magnetic field component (e.g., Bz2), and based on the third magnetic field component and the fourth magnetic field component (e.g., Bx, By); f) determining a two-dimensional position (e.g., R, θ; or X, Y) of the magnet relative to the sensor device by combining the two-dimensional offset and the selected sensor position.

[0046] Step f) may comprise determining said two-dimensional position using a method according to the fourth aspect.

[0047] In a preferred embodiment, the position sensor device is an integrated semiconductor device comprising a semiconductor substrate (e.g., a silicon substrate comprising a plurality of magnetic sensors), and the virtual plane in which the magnet is movable is preferably a plane parallel to the semiconductor substrate and located at a predetermined distance from the semiconductor substrate in the range from 1.0 to 8.0 mm (e.g., approximately 3.5 mm from the substrate).

[0048] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate, and not merely as explicitly set out in the claims.

[0049] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic block diagram of a sensor structure (also referred to herein as a "3D magnetic pixel") that can be used in embodiments of the present invention. The sensor structure includes an integrated magnetic flux concentrator (IMC) and four horizontal Hall elements arranged near the periphery of the IMC and angularly spaced apart by multiples of 90°.

[0051] Figure 2 shows a cross-sectional view of a structure of a pointing device known in the art. The structure comprises a magnet that is movable in a plane parallel to the substrate.

[0052] Figure 3(a) is a schematic representation of a position sensor system including a sensor device and a magnet. The sensor device includes a semiconductor substrate, and the magnet is movable in a plane parallel to the semiconductor substrate. A reference frame having three orthogonal axes, X, Y, and Z, is attached to the semiconductor device. A reference frame having three orthogonal axes, UV, and W, is attached to the magnet.

[0053] FIG3( b ) is a schematic representation of the relative positions of the magnets and a reference position in a plane parallel to the magnets.

[0054] Figure 3(c) is a schematic representation (in top view) showing that the 2D position of a magnet relative to a sensor device can be indicated, for example using polar coordinates (R, θ) or using Cartesian coordinates (x, y). Formulas for converting these coordinates are shown.

[0055] Figure 4(a) gives an impression of the orientation of the magnetic field lines of the magnetic field created by the magnet. The field has circular symmetry. Figure 4(a) shows a cross section through a plane containing the central axis of the magnet. This figure also gives a rough impression of the magnitude and orientation of the magnetic field vector at various locations in a plane parallel to the magnet.

[0056] 4( b ) is a graph showing the amplitudes of the magnetic field components Bx and Bz as a function of radial displacement, as may be obtained by computer simulation, which amplitudes may be measured in plane γ at a distance “g” from the magnet.

[0057] FIG4(c) is a graph showing the result of the function atan2[√(sqr(Bx)+sqr(By)),Bz].

[0058] Figure 5(a) is a schematic representation of a sensor device comprising a 3D magnetic pixel as may be used in embodiments of the present invention.The 3D magnetic pixel comprises an IMC and four horizontal Hall elements.

[0059] FIG5( b ) is a variation of FIG5( a ) including a plurality of 3D magnetic pixels.

[0060] Figure 6 is a schematic representation of another sensor device comprising a 3D magnetic pixel as may be used in embodiments of the present invention.The 3D magnetic pixel comprises one horizontal Hall element and four vertical Hall elements.

[0061] Figure 7 shows a 3D magnetic pixel (such as FIG. 5 or Figure 6 Block diagram of a sensor device with a 3D magnetic pixel (as shown in FIG).

[0062] Figure 8 Shown as can be Figure 7 Flowchart of a method for determining the 2D position of a magnet used by a sensor device, the magnet being movable in a plane parallel to a semiconductor device.

[0063] The drawings are illustrative only and non-limiting. In the drawings, the dimensions of some elements may be exaggerated and not drawn to scale for illustrative purposes. Any reference numerals in the claims should not be construed as limiting the scope. The same reference numerals in different drawings refer to the same or similar elements. DETAILED DESCRIPTION

[0064] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims.

[0065] The terms first, second, etc. in the specification and claims are used to distinguish between similar elements and not necessarily to describe a sequence in time, space, level, or in any other manner. It is understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in a sequence different from that described or illustrated herein.

[0066] The terms top, bottom, etc. in the description and claims are used for descriptive purposes and are not necessarily used to describe relative positions. It is understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein are capable of operation in orientations other than those described or illustrated herein.

[0067] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Thus, the term should be interpreted as specifying the presence of the recited features, integers, steps, or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to a device consisting solely of components A and B. It means that, for the purposes of the present invention, the only relevant components of the device are A and B.

[0068] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure.

[0069] Similarly, it should be understood that in the description of exemplary embodiments of the present invention, various features of the present invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding understanding of one or more of the various inventive aspects. However, this disclosure method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, inventive aspects lie in fewer features than all of the features of a single preceding disclosed embodiment. Accordingly, the claims appended to the detailed description are hereby expressly incorporated into this detailed description, with each claim itself representing a separate embodiment of the present invention.

[0070] Furthermore, although some embodiments described herein include some features included in other embodiments but do not include other features included in those other embodiments, as will be appreciated by those skilled in the art, combinations of features from different embodiments are intended to fall within the scope of the present invention and to form different embodiments. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0071] In the description provided herein, numerous specific details are set forth. However, it is to be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques are not shown in detail to avoid obscuring an understanding of this description.

[0072] In this document, unless explicitly mentioned otherwise, the term "magnetic sensor device" or "sensor device" refers to a device comprising at least one "magnetic sensor" or at least one magnetic "sensor element", which is preferably integrated in a semiconductor substrate. The sensor device may be included in a package (also referred to as a "chip"), but this is not absolutely necessary.

[0073] In this document, the term “sensor element” or “magnetic sensor element” or “magnetic sensor” may refer to a component or group of components or a subcircuit or structure capable of measuring magnetic quantities, such as, for example, a magnetoresistive element, a GMR element, an XMR element, a horizontal Hall plate, a vertical Hall plate, a Wheatstone bridge comprising at least one (but preferably four) magnetoresistive elements, etc., or a combination thereof.

[0074] In certain embodiments of the present invention, the term "magnetic sensor" or "magnetic sensor structure" may refer to an arrangement including one or more integrated magnetic concentrators (IMCs) (also called integrated flux concentrators) and one or more horizontal Hall elements arranged near the periphery of the IMC, for example, a disk-shaped IMC with two horizontal Hall elements spaced 180° apart from each other, or a disk-shaped IMC with four horizontal Hall elements spaced 90° apart from each other.

[0075] In this document, the expressions "in-plane components of the magnetic field vector" and "projection of the magnetic field vector in the sensor plane" are used synonymously. If the sensor device is or includes a semiconductor substrate, this also means "components of the magnetic field parallel to the semiconductor plane." These components may be labeled Bx and By.

[0076] In this document, the expressions "out-of-plane component of a vector" and "Z component of a vector" and "projection of the vector onto an axis perpendicular to the sensor plane" are used synonymously. This component may be denoted as Bz.

[0077] Embodiments of the invention are generally described using an orthogonal coordinate system fixed to the sensor device and having three axes X, Y, Z, where the X and Y axes are parallel to the substrate, and the Z axis is perpendicular to the substrate.

[0078] In this application, horizontal Hall plates are generally referred to by H1, H2, etc., signals from these horizontal Hall plates are generally referred to by h1, h2, etc., vertical Hall plates are generally referred to by V1, V2, etc., and signals from these vertical Hall plates are generally referred to by v1, v2, etc.

[0079] In the context of the present invention, the formulas arctan(x / y), atan2(x,y), arccot(y / x) are considered equivalent.

[0080] The present invention relates to a magnetic position sensor system, device and method for determining the two-dimensional position of a magnet that is movable in a 2D plane. The invention further relates to a position sensor system in which the magnet is connected to a control rod.

[0081] Reference is made to the accompanying drawings.

[0082] Fig. 1 shows a sensor structure comprising an integrated magnetic concentrator (IMC) structure and four horizontal Hall elements H1 to H4 as can be used in embodiments of the invention. The four horizontal Hall elements are arranged near the outer periphery of the integrated magnetic concentrator IMC and are angularly spaced by multiples of 90°. Two of the Hall elements are on the X axis, the other two elements are on the Y axis perpendicular to the X axis.

[0083] Such a sensor structure is described, for example, in EP 3783316 (A1) and therefore need not be explained in more detail herein. For the understanding of the present invention it can be said that the IMC can be a circular disk with a diameter in the range from about 150 to about 250 pm or from about 175 to about 225 pm; and that the sensor structure is capable of measuring a magnetic field component Bx1 oriented in the X direction, a magnetic field component By1 oriented in the Y direction, and a magnetic field component Bz1 oriented in the Z direction perpendicular to X and Y.

[0084] It is noted that the magnetic field components measured in this way correspond to the magnetic field values at the center of the disk. In other words, the structure allows Bx1, By1 and Bz1 to be measured at a single sensor location located at the center of the disk.

[0085] Figure 2 is a copy of Figure 12A of US7388574 (B2) and shows a cross-sectional view of a pointing device structure. The structure contains a magnet 202 that is movable in a plane parallel to the substrate 201. While Figure 2 shows movability in the left-right direction only, it allows for two-dimensional movement in a plane parallel to the substrate 201 when the structure has a circular shape. The structure is provided as an example of a possible mechanical arrangement of a magnet with respect to a sensor device, but the invention is not limited to this particular example and other suitable mechanical arrangements can also be used.

[0086] Figure 3(a) is a schematic representation of a position sensor system 300 comprising a sensor device 301 and a magnet 302. The sensor device 301 comprises a semiconductor substrate (e.g. a silicon substrate) that comprises a sensor structure and processing circuitry, as will be described in further detail. Preferably, the magnet 302 is an axially magnetized disc-shaped magnet that is oriented such that its main axis 303 is perpendicular to the semiconductor substrate.

[0087] As indicated by the arrows in Figure 3(a), the magnet 302 is movable in two directions in a plane parallel to the semiconductor substrate (e.g. a virtual plane). This can be achieved, for example, by mounting the magnet in an assembly as shown in Figure 2, but the invention is not limited to this particular assembly and other mechanical mounting techniques or mounting structures that allow the magnet 302 to move in a plane parallel to the sensor device can also be used.

[0088] Figure 3(b) is a schematic representation of the position of the magnet 302 with respect to the semiconductor substrate 304 of the sensor device. As mentioned above, three orthogonal axes X, Y, Z are fixedly connected to the semiconductor substrate 304. The X and Y axes are parallel to the semiconductor substrate. The Z axis is oriented perpendicular to the substrate. The magnet is positioned at a distance "g" from the semiconductor substrate. When the magnet is in its "default position", its axis 303 passes through a reference point "ref" having coordinates (X=0, Y=0).

[0089] The magnet 302 preferably has a cylindrical shape with a height "H" and an outer diameter "D". In a plane containing the axis 303, the magnet 302 can have a rectangular cross-section (see, for example, Figure 4(a)), or the cross-section can be a rectangle with rounded corners.

[0090] In envisaged applications, the outer diameter "D" of the magnet can be in the range from 2.0 mm to 8 mm, or from 3.0 mm to 6.0 mm, for example equal to about 4.0 mm, or equal to about 5.0 mm. The height "H" of the magnet can be in the range from 0.5 mm to 1.5 mm, for example equal to about 0.8 mm, or equal to about 1.0 mm, or equal to about 1.2 mm. The value of the distance "g" between the semiconductor substrate 304 and the magnet 302 can be in the range from 1.0 mm to 8.0 mm or from 2.0 mm to 6.0 mm, for example equal to about 3.5 mm.

[0091] For the sake of completeness, it is noted that the magnet 302 can or can not be able to rotate around its axis 303, but the magnetic field does not change due to such a rotation (see also Fig. 4(a)). The magnet can be made of any suitable material, for example ferrite, SmCo, NdFeB or plastic bonded magnets.

[0092] Fig. 3(c) is a schematic representation (in top view) of an arrangement in which the magnet 302 is offset from its reference position "ref". Since the magnet is moved in a virtual plane 305 at a distance "g" from the semiconductor substrate 304, its Z coordinate is known (and fixed). For example, the two-dimensional position of the magnet 302 in the plane 305 relative to the axes X, Y of the sensor device can be indicated using polar coordinates (R, Θ) or using Cartesian coordinates (x, y). The formulas to convert polar coordinates to Cartesian coordinates or vice versa are shown. Thus, if at least one set of coordinates is known, the position of the magnet 302 is uniquely defined.

[0093] The inventors of the present invention were faced with the specific task of designing a sensor device that is able to determine the two-dimensional position of a magnet relative to the sensor device. More specifically, they had to find a suitable sensor structure to measure the characteristics of the magnetic field generated by the magnet 302 at a particular position, and find a relationship (for example a function or a formula) between these characteristics and the position from which the above-mentioned coordinates (R, Θ) or (x, y) can be derived. Preferably, of course, the function is as simple as possible, easy to calculate, and provides accurate results over a relatively large range.

[0094] Fig. 4(a) gives an impression of the orientation of the magnetic field lines of the magnetic field created by the magnet 302. Since the magnet is axially magnetized and has a cylindrical shape (for example a disc shape (with sharp or rounded edges)), the magnetic field has circular symmetry around the central axis 303 of the magnet 302. Fig. 4(a) shows a cross-section through a plane containing the central axis 303 of the magnet, which coincides with one of the field lines. The figure also gives a rough impression of the magnitude and orientation of the magnetic field vector at various positions in a plane at a predefined distance "g" from the magnet, which is also the position of the semiconductor substrate.

[0095] FIG4( b ) is a graph showing two simulation curves:

[0096] The first curve (marked with a black square) shows the amplitude of the magnetic field component Bz as a function of the radial distance "R" from the main axis of the magnet 303 in any radial direction. Therefore, for movement parallel to the X axis, this curve also represents Bz(x) as a function of x, and for movement parallel to the Y axis, this curve also represents Bz(y) as a function of y.

[0097] The second curve (marked with black circles) shows the amplitude of the magnetic field component Bx(x) as a function of x for movements parallel to the X axis, and By(y) as a function of y for movements parallel to the Y axis.

[0098] These curves can be obtained by simulation using commercially available software tools.

[0099] As can be appreciated, in region 420 (-5.0 to +5.0 mm in this example), the Bx, By and Bz curves move away from quadrature signals, especially when the radial displacement X is greater than the radius R of the magnet (in this example: 2.0 mm).

[0100] However, the inventors have discovered that, with appropriately chosen constants c1 and c2, a scaled and shifted version of Bz (i.e., c1*(Bz-c2)) behaves very similarly to a cosine function, and with an appropriately chosen constant c3, scaled versions of Bx and By (e.g., c3*Bx) behave very similarly to a sine function, particularly in region 410 (from -2.5 to +2.5 mm in this example). Thus, in region 410, the scaled and shifted version of Bz, on the one hand, and scaled versions of Bx and Bz, on the other hand, behave very similarly to quadrature signals. In this region, the R-dependent Bz component can be approximated by the function Bz(R)≈c1*(R-c2); the X-dependent Bx component can be approximated by the function Bx(x)≈c3*(x); and the function By(y) can be approximated by the function By(y)≈c3*(y), with errors of less than 10%, or even less than 8%, or even less than 6%, or even less than 5% for each function. Unfortunately this doesn't work with range 420.

[0101] The inventors continued to experiment and were very surprised to find that the function atan2[√(sqr(Bx)+sqr(By)),Bz] shown in Figure 4(c) and based on the original Bx, By and Bz signals without scaling and shifting is not only highly linear, but also highly linear in the region 415 from -4.0 to +4.0 mm, that is, highly linear for radial displacements up to twice (2.0 times) the magnet radius (in this example, the magnet diameter is 4.0 mm), with an error of less than about 3%, and highly linear even in a larger region, for example, highly linear in the region from -5.0 to +5.0 corresponding to 2.5 times the magnet radius, with an error of less than about 8%.

[0102] This accuracy is good enough for many applications (e.g. for control rod applications), but can be further improved if desired by post-processing, for example using a multi-point linearization function, which can be implemented, for example, by a piecewise linear approximation function or using a lookup table with interpolation.

[0103] FIG5( a ) is a schematic representation of a sensor device 500 comprising a sensor structure S1 (also referred to herein as a “3D magnetic pixel”) comprising an integrated magnetic concentrator and four horizontal Hall elements H1 to H4. In the example shown, the X and Y axes form a 45° angle with the semiconductor substrate, but this is not critical for the invention to work. The magnetic sensor structure is capable of measuring Bx1, By1, and Bz1 of the magnetic field at a single location at the center of the disk (i.e., at locations X=0 and Y=0).

[0104] If h1, h2, h3, and h4 represent the signals provided by Hall elements H1, H2, H3, and H4, respectively, then Bx can be determined as (h2-h1), By can be determined as (h4-h3), and Bz can be determined as (h2+h1), (h3+h4), or (h1+h2+h3+h4). In reality, a scaling factor related to the sensitivity of the Hall element, etc., is always involved, but to keep the description simple, this scaling factor is ignored here because the signal obtained from the Hall element needs to be amplified regardless. Any of the following formulas can be used to calculate the distance R from the main axis:

[0105] R=K1*arccos(K2*(Bz-K3))[1]

[0106] R=K4*arcsin(√[sqr(Bx)+sqr(By)][2]

[0107] R=K5*atan2[√(sqr(Bx)+sqr(By)),K2*(Bz-K3)][3]

[0108] R = K5 * atan2[√(sqr(Bx) + sqr(By)), Bz] [4]

[0109] And the following formula can be used to calculate the azimuth angle Θ relative to the X axis:

[0110] Θ = atan2(By, Bx) [5]

[0111] It is advantageous to use formula [1] rather than [2] or [3] because it is less computationally intensive and only requires the value Bz.

[0112] It was found that formula [2] provides excellent results for displacements up to about 125% of the magnet radius (i.e. in region 410).

[0113] It was found that formula [1] provides excellent results for displacements up to about 125% of the magnet radius (i.e. in region 410), but also provides good results for radial displacements up to 200% of the magnet radius, or even up to 250% of the magnet radius.

[0114] In an embodiment, formula [3] was used, where K2 is equal to about 0.33, and where K3 is equal to about 15. It was found that this formula also provides highly accurate values for displacements up to about 125% of the magnet radius (i.e. in region 410), and provides acceptable results for up to 150% of the radius.

[0115] However, in a preferred embodiment, formula [4] was used, which is a special case of formula [3] where K2 = 1.0 and K3 = 0. It is advantageous to use this formula rather than [1] or [2] or [3] because it involves the division of two values that both increase or decrease with changes in the magnet strength, so this value is less sensitive to demagnetization effects, temperature variations, etc. Furthermore, as illustrated in Fig. 4(c), this formula provides excellent results for radial displacements up to about 200% of the magnet radius (i.e. in region 415), or even up to 250% of the radius (i.e. in region 420). The accuracy and simplicity of this formula is almost unbelievable, especially when one considers that outside of region 410, the Bz value no longer behaves at all like a cosine function, and the Bx, By values no longer behave at all like sine functions. It is pure coincidence that both the numerator and denominator and the arctangent function appear to cooperate to provide excellent results over such a large region.

[0116] It is advantageous to use formula [5] because it involves the division of two values that are proportional to the magnet strength, so this ratio is highly insensitive to demagnetization effects, temperature variations, etc.

[0117] A sensor device with only one 3D pixel, as illustrated in Figure 5(a), is advantageous because the area of ​​the silicon substrate can be very small. In this regard, it should be noted that a typical diameter of an IMC is about 150 to about 250 μm, and a typical width of a horizontal Hall plate is about 15 to about 25 μm.

[0118] As described above, formula [4] provides highly accurate results (with an error of less than about 3%) for radial displacements up to 2.0 times the magnet radius, and provides accurate results (with an error of less than about 8%) for radial displacements up to 2.5 times the magnet radius.

[0119] If you want to measure larger displacements with similar accuracy, you can use the following options:

[0120] a) Use formulas [4] and [5] with post-processing;

[0121] b) Using multiple 3D pixels, such as shown in FIG5(b), the 3D pixel providing the highest value for Bz is selected to determine which of the IMC centers the magnet is closest to, and then using the signals (Bx, by, Bz) from the selected 3D pixel to determine the position of the magnet relative to the selected 3D pixel, and combining the (known) position of the selected pixel with the position provided by the formula. These 3D pixels can be implemented on a single semiconductor substrate, or can be implemented on multiple semiconductor substrates, which can be packaged in a single semiconductor device.

[0122] c) Use a different magnet, for example with a larger diameter D and / or a larger height H.

[0123] Figure 5(b) is a schematic representation of a sensor device comprising four 3D magnetic pixels spaced apart on a 2x2 grid.But of course the invention is not limited thereto and sensor devices with fewer than four or more than four 3D pixels may also be used.

[0124] In a specific embodiment (not shown), the sensor device comprises seven 3D pixels, one located at a central position and the other six located on a virtual circle having the central position as its center and angularly spaced apart by multiples of 60°.

[0125] In the example of FIG. 5( b ) having only four 3D pixels, the distance between the center of S1 and the center of S3 can be a value in the range from about 5.0 mm to about 10.0 mm, and the distance between the center of S1 and the center of S2 can be a value in the range from about 3.5 mm to about 7.0 mm, but the present invention will also work if the distance between the sensor locations is slightly larger.

[0126] Figure 6FIG2 is a schematic representation of another sensor device including a sensor structure S2 (also referred to herein as a "3D magnetic pixel"), which includes a central horizontal Hall element H1 and four vertical Hall elements V1, V2, V3, and V4 located around the horizontal Hall element. Two of these vertical Hall elements, V1 and V2, have their axes of maximum sensitivity oriented in the X direction. The other two Hall elements, V3 and V4, have their axes of maximum sensitivity oriented in the Y direction.

[0127] The signal Bx can be obtained by summing the values ​​v1 and v2 obtained from the vertical Hall elements V1 and V2, respectively. As mentioned above, any scaling is ignored here because the signals obtained from the Hall elements need to be amplified anyway. The signal (v1+v2) is equivalent to the signal Bx measured at the center where H1 is located. By providing two vertical Hall elements on opposite sides of the horizontal Hall element, the signal Bx can be measured at the same position as Bz (measured by H1) without stacking multiple substrates. In addition, the signal-to-noise ratio (SNR) of the signal Bx can be improved. Similarly, the signal (v3+v4) is equivalent to the signal By measured at the center where H1 is located.

[0128] After the values ​​of Bx, By, Bz have been determined, the distance R and the azimuth angle θ can be determined using the same formulas [1] to [5] mentioned above.

[0129] All other matters mentioned above for the sensor device of FIG. 5( a ) or FIG. 5 ( b ) or variants thereof also apply mutatis mutandis here.

[0130] For example, in an embodiment, the sensor device may include a plurality of 3D pixels (eg, three or four or seven 3D pixels), each 3D pixel having a horizontal Hall element and four vertical Hall elements.

[0131] Of course, a magnetoresistive MR element may also be used instead of the vertical Hall element.

[0132] Figure 7 A block diagram of a sensor device 710 is shown, which includes one or more 3D magnetic pixels (such as FIG. 5( a) or FIG. Figure 6 3( a ) and further includes processing circuitry 730. The sensor device 710 may be used in a position sensor system 300, such as the position sensor system shown in FIG. 3( a ).

[0133] Figure 7 The position sensor device 710 shown in FIG. 7 includes a plurality of magnetic sensor elements M1, M2, etc., such as four horizontal Hall elements (e.g., as illustrated in FIG. 5( a )), or one horizontal Hall element and four vertical Hall elements (e.g., as illustrated in FIG. 5( a )).Figure 6 ).

[0134] The sensor device 710 may optionally further comprise at least one temperature sensor 721, or in the case of a plurality of 3D magnetic pixels, one temperature sensor per 3D pixel, for measuring the substrate temperature at the sensor location to allow compensation of the measured signals m1, m2, etc. in a manner known in the art.

[0135] Although not explicitly shown, the sensor circuitry also typically includes biasing and readout circuitry, including at least one amplifier, an analog-to-digital converter (ADC), etc. Such circuitry is well known in the art but is not the focus of the present invention and therefore does not need to be described in further detail here.

[0136] The sensor device 710 further includes a processing circuit 730 configured to determine the two-dimensional position based on the signals obtained from the sensor elements. The processing circuit 730 may include a programmable processor configured to calculate one or more of the above formulas [1] to [5] and provide polar coordinates R and θ, or may convert the polar coordinates to Cartesian coordinates and provide values ​​x, y.

[0137] Figure 8 It is shown that Figure 7 Flowchart of a method for determining the 2D position of a magnet, which is movable in a plane parallel to a semiconductor device, performed by a sensor device.

Claims

1. A position sensor device for determining the two-dimensional position (R, θ) of a two-pole magnet, the two-pole magnet being movable in a plane parallel to a semiconductor substrate and generating a magnetic field; The position sensor device comprises: the semiconductor substrate comprising a plurality of magnetic sensors configured to determine three orthogonal magnetic field components (Bx, By, Bz) at a single predefined location; and wherein the semiconductor substrate further comprises a processing circuit configured to determine the two-dimensional position (R, θ) based on the three orthogonal magnetic field components (Bx, By, Bz); It is characterized in that The processing circuit is configured to determine the two-dimensional position as a lateral distance (R) from the single predefined position and an azimuth angle (θ) about a predefined direction (X); and wherein the distance (R) is determined as a first function of a ratio of a first numerator and a first denominator, each of the first numerator and the first denominator being a function or expression of at least one magnetic field component (Bx, By, Bz); And wherein the azimuth angle (θ) is determined as a second function of a ratio of a second numerator and a second denominator, each of the second numerator and the second denominator being a function or expression of at least one in-plane magnetic field component (Bx, By).

2. The position sensor device according to claim 1, It is characterized by: The plurality of magnetic sensors include four horizontal Hall elements arranged on a virtual circle near an outer periphery of an integrated magnetic flux concentrator (IMC).

3. The position sensor device according to claim 1, It is characterized in that The plurality of magnetic sensors includes a horizontal Hall element having an axis of maximum sensitivity in a first direction (Z) oriented perpendicular to the semiconductor substrate; and the plurality of magnetic sensor elements include two perpendicular Hall elements having axes of maximum sensitivity in a second direction (X) parallel to the semiconductor substrate; And the plurality of magnetic sensor elements include two perpendicular Hall elements having axes of maximum sensitivity oriented in a third direction (Y) parallel to the semiconductor surface and perpendicular to the second direction (X).

4. The position sensor device according to any one of claims 1 to 3, wherein the first numerator is a function of the in-plane magnetic field components (Bx, By), and the denominator is a function of the out-of-plane magnetic field component (Bz); Or wherein the first numerator is a function of the sum of the squares of the in-plane magnetic field components (Bx, By) and the denominator is a function of the out-of-plane magnetic field component (Bz).

5. The position sensor device according to any one of claims 1 to 3, wherein the second numerator is one of the in-plane magnetic field components (Bx, By), and the second denominator is the other in-plane magnetic field component (By) of the in-plane magnetic field components (Bx, By).

6. The position sensor device according to any one of claims 1 to 3, The distance (R) is determined according to the following formula: R = K5*atan2[√((Bx) 2 +(By) 2 ),K2*(Bz-K3)], wherein K2, K3, K5 are predefined constants; and wherein the azimuth angle (θ) is determined according to the following formula: θ=atan2(By,Bx).

7. The position sensor device according to any one of claims 1 to 3, The distance (R) is determined according to the following formula: R=K5*atan2[√(sqr(Bx)+sqr(By)),Bz], where K5 is a predefined constant; and wherein the azimuth angle (θ) is determined according to the following formula: θ=atan2(By,Bx).

8. The position sensor device according to any one of claims 1 to 3, It is characterized in that The two-pole magnet is an axially magnetized cylindrical magnet.

9. The position sensor device according to claim 8, It is characterized by: The two-pole magnet is movable or displaceable laterally in a plane, with the axis of the magnet being perpendicular to the semiconductor surface.

10. A position sensor system comprising: The position sensor device as claimed in any one of the preceding claims, The magnet is movably mounted in a plane parallel to the semiconductor substrate of the position sensor device.

11. The position sensor system according to claim 10, Further included is a mechanical assembly that includes or is connected to the magnet and is configured to allow the two-pole magnet to move in a direction parallel to the semiconductor substrate while maintaining an axis of the magnet substantially perpendicular to the semiconductor substrate.

12. A control rod assembly comprising the position sensor system according to claim 11, The mechanical assembly further comprises a control rod.

13. A method for determining the two-dimensional position (R, θ) of a two-pole magnet, the two-pole magnet being movable in a plane parallel to a semiconductor substrate, the method comprising the steps of: a) measuring three orthogonal magnetic field components (Bx, By, Bz) at a single predefined location on the semiconductor substrate; b) determining the two-dimensional position (R, θ) based on the three orthogonal magnetic field components (Bx, By, Bz); It is characterized by Step b) comprises: i) determining the lateral distance (R) from the single predefined position as a first function of the ratio of a first numerator and a first denominator, each of the first numerator and the first denominator being a function or expression of at least one magnetic field component (Bx, By, Bz); and Step b) comprises: ii) determining the azimuth angle (θ) about the predefined direction (X) as a second function of the ratio of a second numerator and a second denominator, each of the second numerator and the second denominator being a function or expression of at least one in-plane magnetic field component (Bx, By).

14. The method according to claim 13, wherein Step b) comprises: i) determining the lateral distance (R) from the single predefined position according to the following formula: R = K5*atan2[√((Bx) 2 +(By) 2 ),K2*(Bz-K3)], where K2, K3, K5 are predefined constants; and ii) Determine the azimuth angle (θ) with respect to the predefined direction (X) according to the following formula: θ= atan2(By, Bx).

15. The method according to claim 13, wherein Step b) comprises: i) determining the lateral distance (R) from the single predefined location according to the following formula: R=K5*atan2(√[sqr(Bx)+sqr(By)],Bz), where K5 is a predefined constant; and ii) determining the azimuth angle (θ) with respect to the predefined direction (X) according to the following formula: θ= atan2(By, Bx).

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