Magnetic position sensor systems

Abstract

In a first aspect, the present invention relates to a magnetic position sensor system (10) for a magnetic target (20), comprising: (i) a first sensor (50) for measuring a first magnetic field component B along a direction x in a first sensing area (53) x,1 And the second magnetic field component B along the z direction orthogonal to x z,1 (ii) A second sensor (60) for measuring a first magnetic field component B along the x-direction in a second sensing region (63) aligned with the first sensing region (53) along the x-direction. x,2 and the second magnetic field component B along the z-direction z,2 ; and (iii) an axially magnetized annular magnet (70) arranged below the first sensing region (53) and the second sensing region (63) so that the axial direction (71) of the annular magnet (70) is substantially parallel to the z-direction, and in operation, the position of the annular magnet (70) relative to the first sensing region (53) and the second sensing region (63) is fixed.

Description

Technical Field

[0001] This invention relates to magnetic position sensor systems, and more particularly to magnetic position sensor systems suitable for reducing the influence of magnetic noise on the output signal. Background Technology

[0002] Various magnetic position sensor systems have been described previously, some of which include provisions for reducing the influence of magnetic noise on the output signal. For example, US10718634B2 discloses a rotation angle detector comprising a magnet arranged to rotate about a rotation axis, the magnetic detection circuit including a first pair and a second pair of magnetic detection elements arranged away from the rotation axis, with a predetermined interval between the first and second pairs of magnetic detection elements. Each of the first and second pairs of magnetic detection elements is sensitive to a first magnetic field in the circumferential direction and a second magnetic field in the normal direction. An output signal representing the rotation angle of the magnet is then based on the outputs of the first pair and the second pair of magnetic detection elements.

[0003] Therefore, in US10718634B2, the target to be detected is a magnet. In contrast, US10527456B2 discloses a displacement detection device comprising a rotating measuring target, a sensor, and a magnet (relative to the target) behind the sensor. The rotating measuring target has concave or convex portions on its circumferential surface, and the sensor has detection elements arranged in pairs at predetermined intervals. The detection elements detect the displacement of the concave or convex portions as changes in magnetic flux density in the direction of the rotating axis and radial direction of the measuring target.

[0004] However, there remains a need in the art for magnetic position sensor systems capable of detecting targets without specific surface features (e.g., concave or convex portions); and this is preferably within a fairly large spatial range. Summary of the Invention

[0005] The object of this invention is to provide a good magnetic position sensor system for ferromagnetic targets. A further object of this invention is to provide a good method and use thereof. This object is achieved by the system, method, and use according to the invention.

[0006] The advantage of the embodiments of the present invention is that they have a relatively large target sensing range.

[0007] An advantage of embodiments of the present invention is that the sensing topology used (e.g., using gradient sensing) reduces the influence of magnetic noise. A further advantage of embodiments of the present invention is that it reduces or even eliminates the influence of magnetic noise (e.g., protecting the magnetic position sensor system from stray fields).

[0008] An advantage of embodiments of the present invention is that sensors can be implemented using various sensor elements and their arrangements.

[0009] An advantage of embodiments of the present invention is that the sensor output can be easily converted into a position signal.

[0010] The advantage of the embodiments of the present invention is that, relatively speaking, they can be implemented in a relatively simple and economical manner.

[0011] In a first aspect, the present invention relates to a magnetic position sensor system for a magnetic target, comprising: (i) a first sensor for measuring a first magnetic field component B along the direction x in a first sensing region. x,1 And the second magnetic field component B along the z direction orthogonal to x z,1 (ii) A second sensor for measuring a first magnetic field component B along the x-direction in a second sensing region aligned with the first sensing region along the x-direction. x,2 and the second magnetic field component B along the z-direction z,2 (iii) an axially magnetized annular magnet arranged below the first and second sensing regions such that the axial direction of the annular magnet is substantially parallel to the z-direction, and the position of the annular magnet relative to the first and second sensing regions is fixed during operation.

[0012] In a second aspect, the present invention relates to a method for determining the position of a magnetic target using a magnetic position sensor system as defined in any of the preceding claims, comprising: (a) measuring a first magnetic field component B along the direction x in a first sensing region. x,1 And the second magnetic field component B along the z direction orthogonal to x. z,1 (b) Measure the first magnetic field component B along the x-direction in a second sensing region aligned with the first sensing region along the x-direction. x,2 and the second magnetic field component B along the z-direction z,2 (c) Calculate B x,1 and B x,2 The difference between dB x And B z,1 and B z,2 The difference between dB z ; and (d) from dB x and dB z Determine the location of the magnetic target.

[0013] In a third aspect, the present invention relates to the use of an axially magnetized ring magnet in a magnetic position sensor system for magnetic targets, for extending the range in which the magnetic position sensor system can sense magnetic targets.

[0014] Specific and preferred aspects of the invention are set forth in the appended independent and dependent claims. Features from the dependent claims may be suitably combined with features of the independent claims and other dependent claims, and not merely as expressly set forth in the claims.

[0015] Although devices in the field are constantly being improved, changed, and developed, it is believed that the concepts of this invention represent a sufficiently novel and original advancement, including deviations from prior practice, thereby providing devices with this property that are more efficient, stable, and reliable.

[0016] The above and other features, characteristics, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate the principles of the invention by way of example. This description is given for illustrative purposes only and does not limit the scope of the invention. The accompanying drawings are referenced below. Attached Figure Description

[0017] Figure 1 A magnetic position sensor system and a magnetic target according to an embodiment of the present invention are schematically depicted.

[0018] Figure 2 , Figure 3 and Figure 4 Sensor chips with different arrangements of sensor elements according to embodiments of the present invention are schematically depicted.

[0019] Figure 5 A signal processing circuit according to an embodiment of the present invention is schematically depicted.

[0020] Figure 6 and Figure 7 It is a graph of atan2-angle (dependent on the target travel (i.e., displacement in the x direction)) based on Examples 1 and 2.

[0021] In different accompanying drawings, the same reference numerals refer to the same or similar elements. Detailed Implementation

[0022] The invention will be described with respect to specific embodiments and with reference to certain accompanying drawings, but the invention is not limited thereto, but is defined only by the claims. The described drawings are illustrative only and not restrictive. In the drawings, some elements may be enlarged and not drawn to scale for illustrative purposes. Dimensions and relative dimensions do not correspond to an actual reduction in practice of the invention.

[0023] Furthermore, the terms first, second, third, etc., used in the specification and claims are used to distinguish similar elements and are not necessarily used to describe a temporal, spatial, ranking, or any other order of precedence. It should be understood that the terms thus used are interchangeable where appropriate, and the embodiments of the invention described herein can be operated in a different order than that described or illustrated herein.

[0024] Furthermore, the terms top, bottom, above, below, etc., used in the specification and claims are for descriptive purposes and not necessarily for describing relative positions. It should be understood that these terms, as used so, can be interchanged with their antonyms where appropriate, and the embodiments of the invention described herein can operate in orientations other than those described or illustrated herein.

[0025] It should be noted that the term "comprising" as used in the claims should not be construed as limiting itself to the devices listed thereafter; it does not exclude other elements or steps. Therefore, the term should be interpreted as specifying the presence of the stated 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 term "comprising" covers the case where only the stated feature is present, as well as the case where these features are present along with one or more other features. Therefore, the scope of the statement "an apparatus comprising devices A and B" should not be construed as limited to an apparatus consisting only of components A and B. This means that for the present invention, the only relevant components of the apparatus are A and B.

[0026] Similarly, it should be noted that the term "coupling" as used in the claims should not be construed as limited to direct connection. The terms "coupling" and "connection" may be used together with their derivatives. It should be understood that these terms are not intended to be synonyms with each other. Therefore, the scope of the phrase "device A coupled to device B" should not be limited to devices or systems in which the output of device A is directly connected to the input of device B. This implies the existence of a path between the output of device A and the input of B, which may include other devices or apparatuses. "Coupling" may mean two or more elements in direct physical or electrical contact, or it may mean two or more elements that are not in direct contact with each other but still cooperate or interact with each other.

[0027] Throughout this specification, the reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Therefore, the phrase "in one embodiment" or "in an embodiment" appearing in various places throughout this specification does not necessarily refer to all of the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, as will be obvious to those skilled in the art from this disclosure, particular features, structures, or characteristics can be combined in any suitable manner.

[0028] Similarly, it should be understood that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, drawing, or description for the purpose of simplifying the disclosure and aiding in the understanding of one or more inventive aspects. However, this method of disclosure should not be construed as reflecting an intention to claim more features than are expressly recited in each claim. Rather, as reflected in the appended claims, inventive aspects exist in fewer features than all the features of a single foregoing disclosed embodiment. Therefore, the claims appended following the detailed description are thus explicitly incorporated into this detailed description, wherein each claim itself represents a separate embodiment of the invention.

[0029] Furthermore, while some embodiments described herein include features that are included in other embodiments but not others, it will be understood by those skilled in the art that combinations of features from different embodiments are intended to fall within the scope of the invention and form different embodiments. For example, any embodiment of the claimed embodiments in the appended claims can be used in any combination.

[0030] Numerous specific details are set forth in the description provided herein. However, it should be understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this description.

[0031] The following items are provided separately to facilitate understanding of the invention.

[0032] As used herein, and unless otherwise specified, a magnetic material is a material that is strongly magnetized in an applied magnetic field; for example, a material with a magnetic susceptibility χ of 50 or more (in SI), preferably 200 or more, more preferably 500 or more, such as 1000, 10000, or 100000 or more. Magnetic materials can be hard magnetic materials (e.g., materials with an intrinsic coercivity H of 1000 A / m or more). ci ) or soft magnetic materials (e.g., those with an intrinsic coercivity H less than 1000 A / m).ci Generally, in the absence of a magnetic field, a magnetic material can exhibit bulk magnetization (i.e., it can be a permanent magnet), but typically it does not. Therefore, in the absence of a magnetic field, a magnetic material is typically not magnetized or has magnetic domains that are oriented (e.g., randomly) so that they cancel each other out, thus not exhibiting any significant bulk magnetization. In a preferred embodiment, the magnetic material can be a ferromagnetic material (e.g., a soft ferromagnetic material).

[0033] As used herein, and unless otherwise specified, a toroidal magnet is a magnet having a hole (i.e., a through-hole) therein along its axial direction. Most typically, a cross-section through a toroidal magnet perpendicular to its axial direction may have a circular inner boundary and a circular outer boundary; in other words, the cross-section may be a ring. Nevertheless, the inner and outer boundaries of the cross-section can more generally have any shape, such as polygonal or even irregular. The inner and outer boundaries also do not need to have the same shape, but can be chosen independently; for example, the outer boundary may be circular, while the inner boundary may be polygonal. Similarly, the height (H) of a toroidal magnet generally does not need to remain constant across its diameter (e.g., a toroidal magnet may have a torus shape), but is generally kept constant in embodiments. It will be noted that in the case of non-circular inner and / or outer boundaries, it may be more natural to speak more generally of the (inner / average / outer) width along the x-direction rather than the (inner / average / outer) diameter. In this case, these terms can therefore be used interchangeably.

[0034] As used herein, and unless otherwise specified, if the angle between the first direction and the second direction is between -10° and 10°, preferably between -5° and 5°, more preferably between -2° and 2°, even more preferably between -1° and 1°, and most preferably (excellently) parallel (i.e., 0°), then the first direction can be considered substantially parallel to the second direction.

[0035] In a first aspect, the present invention relates to a magnetic position sensor system for a magnetic target, comprising: (i) a first sensor for measuring a first magnetic field component B along the direction x in a first sensing region. x,1 And the second magnetic field component B along the z direction orthogonal to x. z,1 (ii) A second sensor for measuring a first magnetic field component B along the x-direction in a second sensing region aligned with the first sensing region along the x-direction. x,2 and the second magnetic field component B along the z-direction z,2(iii) an axially magnetized annular magnet arranged below the first and second sensing regions such that the axial direction of the annular magnet is substantially parallel to the z-direction, and the position of the annular magnet relative to the first and second sensing regions is fixed during operation.

[0036] Figure 1 An example of such a magnetic position sensor system 10 is schematically depicted, showing a magnetic target 20, a first sensor 50 and a second sensor 60 (in a sensor chip 40 having a chip substrate 41 and a package 42), and a ring magnet 70 having an axial direction 71. The sensing region 53 of the first sensor 50 and the sensing region 63 of the second sensor 60 are also depicted.

[0037] The sensing areas of the first and second sensors are those in which they sense their respective magnetic field components B. x,1 |B z,1 and B x,2 |B z,2 The sensing area is the region where the magnetic field components in the x and z directions within a sensor are measured at (essentially) the same point or spot in space. However, each sensor can also include different sensing elements for determining the magnetic field components in the x and z directions. For example, in… Figure 2 and Figure 3 This is schematically depicted in the diagram, where the first sensor 50 has a function for measuring B. x,1 The first sensing element 51 and the element for measuring B z,1 The second sensing element 52. Similarly, the second sensor 60 has a second sensing element 52 for measuring B. x,2 The first sensing element 61 and the element for measuring B z,2 The second sensing element 62. For example, the first sensing elements 51 and 61 may have a maximum sensitivity axis perpendicular to the z-direction; they may be, for example, vertical Hall elements or magnetoresistive elements. For example, the second sensing elements 52 and 62 may have a maximum sensitivity axis parallel to the z-direction; they may be, for example, horizontal Hall elements. When the sensor contains different sensing elements, these sensing elements may not measure at the same point / spot in space, but at two points / spots separated by a short distance (typically on the order of magnitude of the size of the sensing element, i.e., tens to hundreds of micrometers; for example, between 10 and 200 μm, or, for example, between 30 and 100 μm). In this case, the sensing area is the region (e.g., a 1D or 2D region) defined and formed by these sensing points or spots.

[0038] Figure 4A further illustrative setup is schematically depicted, which has different sensing elements but does not directly measure B. x,1 、B z,1 、B x,2 and B z,2 Instead, each of sensors 50 and 60 consists of two distinct sensing elements, but both sensors 50 and 60 have a maximum sensitivity axis parallel to the z-direction (e.g., a horizontal Hall element), along with a magnetic concentrator 54 (e.g., a floppy disk). The magnetic concentrator 54 bends the magnetic field lines and allows the sensing elements to measure both in-plane and out-of-plane magnetic field components. The sensing elements then output the measured field component B. l,1 、B r,1 、B l,2 and B r,2 These field components can be linearly combined into x and z field components: B x,1 = (B l,1 -B r,1 ) / 2, B z,1 = (B l,1 +B r,1 ) / 2, B x,2 = (B l,2 -B r,2 ) / 2 and B z,2 = (B l,2 +B r,2 ) / 2.

[0039] The first and second sensors, and therefore the first and second sensing areas, are typically spaced apart by a predetermined distance (usually on the order of mm, such as about 1 to 3 mm). Generally, B x,1 and B x,2 The distance between points / spots being measured can be called dx1, while B z,1 and B z,2 The distance between the points / spots being measured can be called dx2. In specific cases, dx1 = dx2 = dx; for example, when the first and second sensing areas are sensing points / spots (see above), or simply when the sensing elements are specifically arranged to have such an effect (e.g., they are aligned along the y-direction). Figure 2 The latter is depicted schematically in the text, while Figure 3 The diagram illustrates the case where dx1≠dx2.

[0040] In an embodiment, the magnetic position sensor system may further include a substrate arranged such that the first and second sensors are above the substrate, and a ring magnet is below the substrate. For example, as Figure 1As schematically depicted, a first sensor 50 and a second sensor 60 (e.g., sensor chip 40 integrated therein; see below) may be mounted above a substrate 30, and a ring magnet 70 may be mounted below a substrate 30. In an embodiment, the substrate may be a printed circuit board (PCB).

[0041] In an embodiment, the axial direction of the ring magnet can (substantially) bisect the line segment connecting the first sensing region and the second sensing region (e.g., the center connecting the two regions). In other words, the axial direction of the ring magnet can be the perpendicular bisector of the line segment. In an embodiment, if the distance from the intersection of the axial direction and the line segment to the center of the line segment is 10% or less of the total length of the line segment, preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less, then the axial direction can be considered to substantially bisect the line segment.

[0042] Nevertheless, if the offset within the target sensing range is desired, the offset in the x-direction between the toroidal magnet and the first and second sensing areas can be considered. In practice, this offset of the toroidal magnet can shift the target sensing range in the same direction, but typically in a non-linear (and unpredictable) manner. Therefore, finding a suitable toroidal magnet offset may require some trial and error to achieve the desired target sensing range.

[0043] In this embodiment, the top of the ring magnet can be located at a height (h) below the first sensing area and the second sensing area. m At point ) and height (h) m ) at the average diameter (D) of the toroidal magnet m That is, inner diameter D i and outer diameter D o The percentage of the average value is between 5% and 100%, preferably between 10% and 80%, more preferably between 15% and 60%, and even more preferably between 20% and 40%.

[0044] In the embodiment, the inner diameter (D) of the ring magnet i ) can be on the outer diameter (D) of the toroidal magnet o The content of ) is between 25% and 95%, preferably between 30% and 85%, more preferably between 35% and 75%, even more preferably between 40% and 65%, and most preferably between 45% and 55%.

[0045] In one embodiment, the magnetic position sensor system may further include signal processing circuitry. In another embodiment, the signal processing circuitry may include circuitry for outputting B. x,1 and B x,2 The difference between dB x The first interpolation module, and the module used to output B. z,1 and B z,2The difference between dB z The second difference module. In an embodiment, the signal processing circuit may further include a method for calculating the difference from dB. x and dB z The module that generates the output signal. Figure 5 The image schematically depicts such a signal processing circuit 80, showing difference modules 81 and 82, which are used to output B from sensor elements 51, 52, 61, and 62. x,1 、B x,2 、B z,1 and B z,2 Calculate the output dB x and dB z Further shown is the output generation module 83, used for example, using dB x and dB z Calculate atan2 or include a lookup table (LUT), and then send the result off-chip via output / interface 90.

[0046] In an embodiment, the first and second sensors, as well as signal processing circuitry (if present), may be integrated into a single integrated circuit (IC); for example, on a single IC substrate.

[0047] Although the magnetic position sensor system of the present invention is typically used with a toroidal magnet fixed in position relative to a first sensing region and a second sensing region, it will be apparent that one can always make the toroidal magnet movable (e.g., possibly allowing some adjustments between measurements), but simply not use it in operation (e.g., when performing the method according to the second aspect). In other embodiments, the position of the toroidal magnet may be permanently fixed relative to the first sensing region and the second sensing region.

[0048] In the embodiments, any feature of any embodiment of the first aspect may be independently identical to the corresponding description for any embodiment of any other aspect.

[0049] In a second aspect, the present invention relates to a method for determining the position of a magnetic target using a magnetic position sensor system as defined in any of the preceding claims, comprising: (a) measuring a first magnetic field component B along the direction x in a first sensing region. x,1 And the second magnetic field component B along the z direction orthogonal to x. z,1 (b) Measure the first magnetic field component B along the x-direction in a second sensing region aligned with the first sensing region along the x-direction. x,2 and the second magnetic field component B along the z-direction z,2 (c) Calculate B x,1 and B x,2 The difference between dB x And B z,1and B z,2 The difference between dB z ; and (d) from dB x and dB z Determine the location of the magnetic target.

[0050] In this embodiment, the width (W) of the magnetic target along the x-direction can be equal to the average diameter (D) of the toroidal magnet. m The percentage is between 1% and 300%, preferably between 5% and 200%, and more preferably between 10% and 100%. The target to be detected is generally not particularly limited by its shape. However, the method of the present invention is particularly suitable for detecting magnetic targets whose size does not exceed much of the size of a toroidal magnet. In fact, once the target becomes very large, displacement in the x-direction is likely to not change the magnetic field component that can be measured by the magnetic position sensor system, thus hindering the detection of the target and / or motion. In such cases, methods such as those in US10718634B2 may prove to be more efficient.

[0051] Furthermore, although not strictly limited thereto, the method of the present invention is particularly applicable to detecting linear motion of a target (parallel to the x-direction). In this respect, the magnetic position sensor system may also be referred to as a magnetic linear position sensor system.

[0052] In this embodiment, the magnetic target can be located at a fixed height (h) above the first sensing area and the second sensing area. t At a fixed height (h). In the embodiment, the height is fixed. t The average diameter (D) of the toroidal magnet can be... m The percentage is between 1% and 100%, preferably between 3% and 50%, and more preferably between 2% and 35%.

[0053] In this embodiment, the position determined in step d may be related to...

[0054]

[0055] In an embodiment, the position may be linearly related to (e.g., proportionally) to one of the expressions above. Wherein, dB x It's B x,1 –B x,2 dB z equals B z,1 –B z,2 dx1 is the magnetic field component B x,1 and magnetic field component B x,2 The distance between the two sensing spots at the point of measurement, and dx2 is the magnetic field component B. z,1 and magnetic field component B z,2 The distance between the two sensing spots at the point of measurement. If dx1 = dx2, the above expression can be simplified to dB.x / dB z and k.dB x / dB z Furthermore, k is an optional factor that allows amplitude correction between field gradients. However, note that since k is a simple multiplication factor in the above expression, it is related to... The relevant location is also related to dB x / dx1 / dB z / dx2 related.

[0056] In an embodiment, the location determined in step d may be more specifically related to... Relatedly, atan2(y,x) is a function that modifies the arctangent atan(y / x) based on the signs of x and y (i.e., based on quadrant detection form) so that the function's range becomes [0°, 360°]. Similarly, if dx1 = dx2, the expression simplifies to atan2(dB) z / k.dB x Note that choosing which term to use as x and which term to use as y (i.e., choosing the numerator and denominator in the atan function) only changes the position of 0°, while the signs of these terms only change the slope (rising or falling) of the atan2 output, so both can be chosen arbitrarily. Therefore, the position determined in step d can also be compared with... or Related.

[0057] In an embodiment, determining the position in step d may further include determining the intermediate result (e.g., dB). x / dx1 and dB z / dx2, therefore, the ratio of the two or the atan2 of the two are linearized to obtain the position. In some embodiments, linearization of intermediate results can be performed using a linearization function. For example, such a linearization function can be derived from the measured response of the intermediate results of the position function (see, for example, Examples 1 and 2). In other embodiments, linearization of intermediate results can be performed using a lookup table, optionally using interpolation between lookup table data points. In embodiments, the lookup table may be based on dB x / dx1 and dB z Any one of / dx2, therefore, the ratio of the two or the atan2 of the two. Using this ratio (or indirectly using the atan2 of the ratio) is advantageous because it reduces or eliminates the effect of temperature; in fact, the effect in dB... x / dx1 and dB z The temperature effect of / dx2 is usually proportional, making dB x / dx1 and dB z The ratio of / dx2 tends to remain essentially unaffected.

[0058] In the embodiments, any feature of any embodiment of the second aspect may be independently identical to the corresponding description for any embodiment of any other aspect.

[0059] In a third aspect, the present invention relates to the use of an axially magnetized ring magnet in a magnetic position sensor system for magnetic targets, for extending the range in which the magnetic position sensor system can sense magnetic targets.

[0060] For example, Examples 1, 2, and the comparative examples below illustrate the effect of a toroidal magnet on the range in which a magnetic position sensor system can sense magnetic targets (e.g., detect and / or determine the position of a magnetic target). It is evident that using a toroidal magnet (i.e., with an aperture along the axial direction) produces a significantly higher-performing magnetic position sensor system than using a similar disk magnet (i.e., without an aperture). In the embodiments, this range can be extended compared to a disk magnet having the same external dimensions (e.g., the same outer diameter and the same height) and made of the same material as the toroidal magnet, or compared to a disk magnet having the same external dimensions and the same remanent magnetic flux density (also referred to as "remanence") as the toroidal magnet. Without being constrained by theory, it is believed that the aperture in the toroidal magnet diffuses the spatial gradient over a longer distance, resulting in a considerably longer sensing range.

[0061] In an embodiment, this range can be extended to the average diameter (D) of the toroidal magnet. m The percentage is between 80% and 200%, preferably between 95% and 180%, more preferably between 110% and 160%, and even more preferably between 125% and 140%.

[0062] The extension of the sensing range is typically determined by the inner diameter (D) of the toroidal magnet. i ) and outer diameter (D) o The interaction between the aperture and the inner diameter (D) determines this range. On the one hand, the effect of the spatial gradient propagating over a long distance leads to this range being related to the inner diameter (D). i Related to ) On the other hand, outer diameter (D o This indirectly determines the amount of magnetic material, and thus also the strength of the magnet, which in turn affects the sensing range.

[0063] In the embodiments, any feature of any embodiment of the third aspect may be independently identical to the corresponding description for any embodiment of any other aspect.

[0064] The invention will now be described in detail through several embodiments thereof. It will be apparent that other embodiments of the invention can be configured based on the knowledge of those skilled in the art without departing from the true technical teachings of the invention, which is limited only by the terms of the appended claims.

[0065] Example 1

[0066] refer to Figure 1 The schematic depiction illustrates how a magnetic position sensor system 10 according to the invention is fabricated by mounting a Melexis MLX90371 dual-disk sensor chip 40 (MLX90371GDC-BCC-200-RE) onto a printed circuit board 30 (PCB), and then attaching an axially magnetized annular magnet 70 beneath the sensor chip 40 on the opposite side of the PCB 30. The axially magnetized annular magnet 70 is a 1.35T NdFeB annular magnet with an annular cross-section and an outer diameter D. o It is 10mm, with an inner diameter D. i It is 5mm (therefore the average diameter D) m The ring magnet 70 is 7.5mm in diameter and 5mm in height (H). It is positioned such that its axial direction is substantially perpendicular to the PCB 30 (i.e., substantially parallel to the z-direction) and substantially aligned with the sensing areas 53 and 63 of the first sensor 50 and the second sensor 60 of the sensor chip 40 (i.e., the axial direction of the ring 70 substantially bisects the line segment connecting the first sensing area 53 and the second sensing area 63). The height difference h between the top of the ring magnet 70 and the first sensing area 53 and the second sensing area 63 is... m It is approximately 2mm.

[0067] To test the magnetic position sensor system 10, the magnetic position sensor system 10 was mounted on an adjustable stage and coupled to a Melexis daughterboard (PTC04-DB-HALL06) to interface with the sensor chip 40. A ferromagnetic helical head was then positioned above (in front of) the magnetic position sensor system 10 as a magnetic target 20.

[0068] Next, the magnetic target 20 is positioned at a fixed distance h from the first sensing area 53 and the second sensing area 63. t The magnetic target 20 remains in place while the magnetic position sensor system 10 moves in the x-direction, thus simulating the linear motion of the magnetic target 20 relative to the magnetic position sensor system 10. This results in the magnetic field component B measured by the first sensor 50. x,1 and B z,1 And the magnetic field component B measured by the second sensor 60 x,2 and B z,2 The change. Using the equation when dx1 = dx2.

[0069]

[0070] The outputs of the first sensor 50 and the second sensor 60 can be converted into angles that depend on the stroke (i.e., displacement in the x-direction). Figure 6The typical response of the helical head target 20 is presented, showing the variation with different fixed distances h for 0.5 mm, 1.5 mm, and 2.5 mm. t The angle of the applied stroke is calculated from the measured magnetic field component (with k set to 1).

[0071] Based on this response, one or more lookup tables and / or linearization functions can be formulated to target distances of up to a predefined distance h. t The target 20 is inferred to have an (unknown) position from the calculated angle. Therefore, the current magnetic position sensor system 10 can detect the linear displacement of the target within a range of about 10 mm (between -5 and 5 mm relative to the center between the first sensing area 53 and the second sensing area 63).

[0072] Example 2

[0073] Repeat Example 1, but use a ferromagnetic nut instead of a ferromagnetic screw head for target 20. Figure 7 The text presents the concept of a single fixed distance h. t The typical response obtained for the nut target 20. Therefore, the current magnetic position sensor system 10 is also capable of detecting the linear displacement of the nut target 20 within a range of approximately 10 mm.

[0074] Comparative examples

[0075] Repeat Example 1, but replace the toroidal magnet with an axially magnetized disk magnet (which has similar properties to a toroidal magnet). However, this change results in a significant decrease in the sensitivity of the setup, reducing the detectable range to approximately 1 mm.

[0076] It should be understood that although preferred embodiments, specific constructions, configurations, and materials have been discussed herein for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes or modifications in form and detail may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A magnetic linear position sensor system (10) for a magnetic target (20), comprising: i. A first sensor (50), the first sensor (50) being used to measure in a first sensing area (53): – The first magnetic field component B along the direction x x,1 ,as well as – The second magnetic field component B along the z direction orthogonal to x z,1 ; ii. A second sensor (60), the second sensor (60) being used to measure in a second sensing region (63) aligned with the first sensing region (53) along the x-direction: – The first magnetic field component B along the x-direction x,2 ,as well as – The second magnetic field component B along the z-direction z,2 ; as well as iii. An axially magnetized annular magnet (70) arranged below the first sensing region (53) and the second sensing region (63) such that the axial direction (71) of the annular magnet (70) is parallel to the z-direction, and in operation, the position of the annular magnet (70) relative to the first sensing region (53) and the second sensing region (63) is fixed.

2. The magnetic linear position sensor system (10) of claim 1, further comprising a substrate (30) arranged such that the first sensor (50) and the second sensor (60) are above the substrate, and the annular magnet (70) is below the substrate.

3. The magnetic linear position sensor system (10) as described in any of the preceding claims, characterized in that, The axial direction (71) of the ring magnet (70) bisects the line segment connecting the first sensing area (53) and the second sensing area (63).

4. The magnetic linear position sensor system (10) as described in claim 1, characterized in that, The top of the ring magnet (70) is located at a height h below the first sensing area (53) and the second sensing area (63). m At the height h m The average diameter D of the ring magnet (70) m Between 5% and 100%.

5. The magnetic linear position sensor system (10) as described in claim 1, characterized in that, The inner diameter D of the ring magnet (70) i The outer diameter D of the ring magnet (70) o Between 25% and 95%.

6. The magnetic linear position sensor system (10) as claimed in claim 1, further comprising a signal processing circuit (80).

7. The magnetic linear position sensor system (10) as described in claim 6, characterized in that, The signal processing circuit (80) includes: – Used to output B x,1 and B x,2 The difference between dB x The first difference module (81), and – Used to output B z,1 and B z,2 The difference between dB z The second difference module (82).

8. The magnetic linear position sensor system (10) as described in claim 7, characterized in that, The signal processing circuit (80) further includes a function for processing signals from dB. x and dB z The module that generates the output signal (83).

9. The magnetic linear position sensor system (10) as described in claim 1, characterized in that, The first sensor (50) and the second sensor (60) are integrated into a single integrated circuit.

10. A method for determining the position of a magnetic target (20) using a magnetic linear position sensor system (10) as described in any of the preceding claims, comprising: a. Measurement in the first sensing area (53): – The first magnetic field component B along the direction x x,1 ,as well as – The second magnetic field component B along the z direction orthogonal to x z,1 ; b. Measurement in a second sensing region (63) aligned with the first sensing region (53) along the x-direction: – The first magnetic field component B along the x-direction x,2 ,as well as – The second magnetic field component B along the z-direction z,2 ; c. Calculate B x,1 and B x,2 The difference between dB x And B z,1 and B z,2 The difference between dB z ; as well as d. From dB x and dB z Determine the position of the magnetic target (20).

11. The method as described in claim 10, characterized in that, The location determined in step d is related to 12. The method according to any one of claims 10 to 11, characterized in that, The magnetic target (20) is located at a fixed height h above the first sensing area (53) and the second sensing area (63). t Place.

13. The method according to any one of claims 10 to 11, characterized in that, The width W of the magnetic target (20) along the x-direction is in the average diameter D of the annular magnet (70). m Between 1% and 300%.

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