Magnetic field sensor array and method for measuring a magnetic field, etc

Abstract

A method for determining a magnetic field around an object comprises the steps of: a) placing the object onto or near a surface of a magnetic field sensor; b) illuminating the object and the magnetic field sensor with a light source, in particular a mapping light source; c) determining a first intensity distribution, in particular a first intensity distribution at or near a surface layer of a semiconductor substrate (10, 10') comprised by the magnetic field sensor; d) determining a position and / or orientation of the object relative to the magnetic field sensor array based on the first intensity distribution; e) measuring a magnetic field distribution with the magnetic field sensor.

Description

[0001] Magnetic field sensor array and method for measuring a magnetic field, etc.

[0002] The invention pertains to the field of magnetic field cameras. It relates to a method for determining a magnetic field created by an object and a use of a magnetic field sensor array or magnetic field camera in accordance with the independent patent claims.

[0003] TECHNICAL BACKGROUND

[0004] In measuring and producing magnetic systems, it is often necessary to correlate magnetic field distributions around a system with the geometry of parts comprised by the system. For example, in a production, in particular an industrial production, of magnets, quantities like a magnetic field direction and strength and / or magnitude might be measured, in particular at a plurality of locations to obtain a spatial distribution of said quantities, and may be correlated with a position, orientation, shape and / or geometry of the magnets. If the field created by a particular magnet points too much in a wrong direction, is to weak or to strong, and / or has a spatial distribution that deviates too much from an expected and / or specified distribution, then this particular magnet might be treated as a reject.

[0005] Fast and accurate determination of a respective spatial correlation can be difficult, particularly for smaller magnets or magnetic systems, as minor misalignments between magnetic field and shape and / or geometry measurement systems can significantly affect the spatial correlation. It would be desirable to have simple and robust means of making such a correlation, especially under rough conditions, such as vibrations, on the factory floor.

[0006] For about ten years now, magnetic field cameras (also referred to as magnetic cameras) have been used to measure smaller magnetic field distributions. They are essentially sensor arrays comprising a plurality of magnetic field sensors (like, e.g., Hall sensors), often integrated into a semiconductor, that measure the magnetic field in a plane or along a line. To protect the sensors from an environment, all known existing magnetic camera systems are provided in a package or casing which is optically not transparent. As a consequence, the individual sensors and the sensor array are not visible, and may not be seen by any kind of optical camera operating in an UV-A, visible and / or nearinfrared spectral range, which significantly complicates an accurate determination of the spatial correlation.

[0007] A more recent type of magnetic field cameras is based on the principles described in international patent application publication WO 2022 / 136275 A1. This type of camera does generally not comprise discrete magnetic field sensors, which may also complicate an accurate determination of the spatial correlation between magnetic field distribution and geometry.

[0008] Therefore, it would be desirable to find new magnetic field sensor arrays and methods for measuring a magnetic field that overcome the disadvantages as detailed above.

[0009] SUMMARY OF THE INVENTION

[0010] The above objective and other objectives are achieved by a magnetic field sensor array and method for measuring a magnetic field. Preferred embodiments and / or variations of the invention are presented in dependent claims.

[0011] A method for determining a magnetic field around an object in accordance with the invention as hereinafter claimed may comprise the features of claim 1 below. Use of a magnetic field sensor array or a magnetic field camera in accordance with the invention as hereinafter claimed may comprise the features of claim 18 below.

[0012] The dependent patent claims specify detail related to preferred embodiments.

[0013] Under one aspect related to the present invention, the magnetic field sensor array may be covered with an optically transparent layer. This layer can be fully transparent or transparent in a wide or narrow wavelength band in the visible and IR parts of the spectrum. If the sensor has some visible micro- and / or mesostructures on its surface, the position of these structures can now be measured with an optical measurement system, such as an industrial camera with a telecentric lens. By design, the position of the magnetic field-sensitive volumes in the sensor is very well known in relation to the visible micro-Zmesostructures, very often with sub-micron accuracy. Supposing a magnetic object is placed close to the sensor, and an image is taken with a measurement camera. In that case, the optical measurement will directly reveal the relative position of the object’s outer shape to the magnetic sensor. The accuracy of this measurement is only limited by the lateral depth resolution of the optical system. The image from the magnetic sensor and the optical image can be very accurately superimposed, which is the final goal. Furthermore, if several micro- Zmesostructures are on the magnetic sensor surface, it is also straightforward to correct any optical distortion close to the sensor plane; these structures may work as an inbuilt scale in the optical image.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The subject matter of the invention will be explained with respect to further optional detail in the following text with reference to the above and further exemplary embodiments which are illustrated in the attached drawings.

[0016] Fig. 1 shows a top view of an exemplary magnetic field sensor array;

[0017] Fig. 2 illustrates an exemplary image of an object placed on the magnetic field sensor array; and

[0018] Fig. 3 illustrates the intensity distribution on the surface of a semiconductor substrate for an exemplary situation where an object is placed directly on the surface of a magnetic field sensor;

[0019] Fig. 4 illustrates an exemplary first intensity distribution on the surface of a semiconductor substrate 10’ for an exemplary situation where an object is placed above, adjacent to and / or opposite a semiconductor substrate and / or a magnetic field sensitive optical element .

[0020] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0021] The present invention may, in particular, be put into practice in the form of one or more of the following numbered embodiments:

[0022] 1 ) A magnetic field sensor array, in particular for measuring a magnetic field distribution, said magnetic field sensor array comprising: a) a semiconductor substrate; b) a plurality of magnetic field sensors, in particular Hall sensors, provided on and / or within a surface layer of the semiconductor substrate; characterized by c) an at least partially transparent protection layer, in particular a glass layer or plastic layer, covering the plurality of magnetic field sensors. 2) The magnetic field sensor array of embodiment 1 , wherein the at least partially transparent protection layer is at least partially transparent to at least a subrange of wavelengths from a UV-A, visible and / or near-infrared spectral range.

[0023] 3) The magnetic field sensor array of any preceding embodiment, wherein for at least one wavelength or range of wavelengths from a UV-A, visible and / or near-infrared spectral range, the at least partially transparent protection layer has a transmittance or a transmission coefficient of at least 0.2, preferably of at least 0.5, most preferably of at least 0.8.

[0024] 4) The magnetic field sensor array of any preceding embodiment, wherein a maximum transmittance or a maximum transmission coefficient of the at least partially transparent protection layer within the UV-A, visible and / or nearinfrared spectral range is 0.8, preferably 0.5, and most preferably 0.2.

[0025] 5) The magnetic field sensor array of any preceding embodiment, wherein the at least partially transparent protection layer is attached, in particular permanently and / or irreversibly attached, to the semiconductor substrate, in particular to the surface layer of the semiconductor substrate, in particular by gluing, pasting or casting.

[0026] 6) The magnetic field sensor array of any preceding embodiment, wherein the at least partially transparent protection layer is a cast layer, in particular formed from an epoxy resin.

[0027] 7) The magnetic field sensor array of any preceding embodiment, wherein at least a subset of the magnetic field sensors comprises a unique, visible identifier, in particular a combination of digits, numbers and / or letters, wherein each identifier is preferably different from any other identifier from the subset of magnetic field sensors.

[0028] 8) The magnetic field sensor array of any preceding embodiment, wherein the magnetic field sensors are arranged in an array having N lines or rows, and M columns of sensors.

[0029] 9) The magnetic field sensor array of any preceding embodiment, further comprising a plurality of light sensitive elements arranged on and / or within a surface layer of the semiconductor substrate.

[0030] 10) The magnetic field sensor array of any preceding embodiment, wherein a number Ni of light sensitive elements is equal to or larger than a number A / mof magnetic field sensors, in particular with Nm= N ■ M.

[0031] 11 ) The magnetic field sensor array of any preceding embodiment, wherein in each line and / or each column, a) at least one light sensitive element is interposed between any two adjacent magnetic field sensors; and / or b) exactly one magnetic field sensor is interposed between any two adjacent light sensitive elements.

[0032] 12) The magnetic field sensor array of any preceding embodiment, wherein the light sensitive elements and the magnetic field sensors are alternati ngly arranged in a checkerboard fashion.

[0033] 13) The magnetic field sensor array of any preceding embodiment, wherein at least some, in particular each, of the light sensitive elements comprise(s) a photodiode, in particular a CMOS cell, or a pixel of a charge-coupled device, CCD, image sensor. 14) The magnetic field sensor array of any preceding embodiment, wherein each of the light sensitive elements is a temperature sensor.

[0034] 15) The magnetic field sensor array of any preceding embodiment, wherein each temperature sensor is integrated with a different one of the plurality of magnetic field sensors, in particular with a number of temperature sensors equaling a number of magnetic field sensors.

[0035] 16) A method for determining a magnetic field around an object, in particular created by said object, comprising the steps of: a) placing the object onto or near a surface of a magnetic field sensor array, in particular a magnetic field sensor array according to one of the preceding embodiments, said magnetic field sensor array comprising a plurality of magnetic field sensors; b) obtaining an image showing at least a part of the object and at least a first subset of the magnetic field sensors, in particular by means of an optical camera; c) determining a position and / or orientation of the object relative to the magnetic field sensor array based on the image; d) measuring a magnetic field distribution with the magnetic field sensor array.

[0036] 17) The method of embodiment 16, wherein to determine the position and / or orientation of the object, the image is analyzed to identify a second subset of magnetic field sensors which are obstructed from the optical camera’s view by the object.

[0037] 18) The method of embodiment 16 or 17, wherein the object is placed between the magnetic field sensor array and the optical camera.

[0038] 19) The method of any preceding method embodiment, wherein the magnetic field sensor array and the optical camera are positioned on opposite sides with respect to the object.

[0039] 20) A method for determining a magnetic field around an object, in particular created and / or generated by said object, comprising the steps of: a) placing the object onto or near a surface of a magnetic field sensor, in particular a magnetic field sensor array according to one of embodiments 1 to 15; b) illuminating the object and the magnetic field sensor with a light source, in particular a mapping light source; c) determining a first intensity distribution, in particular a first intensity distribution at or near a surface layer of a semiconductor substrate comprised by the magnetic field sensor; d) determining a position and / or orientation of the object relative to the magnetic field sensor array based on the first intensity distribution; e) measuring a magnetic field distribution with the magnetic field sensor .

[0040] 21) The method of embodiment 20, wherein the magnetic field sensor is a or comprises a magnetic field sensor array, in particular a magnetic field sensor array according to one of the preceding embodiments, and / or with said magnetic field sensor array in particular comprising a plurality of magnetic field sensors, in particular Hall sensors.

[0041] 22) The method of embodiment 20, wherein the magnetic field sensor comprises: a) a magnetic field sensitive optical element, in particular layer, configured to generate a photocurrent, luminescence and / or an electromagnetic radiation, wherein i) the photocurrent, luminescence and / or an electromagnetic radiation is dependent on and / or varies with the magnetic field; ii) the magnetic field sensitive optical element is provided in proximity to the semiconductor substrate, in particular the surface layer of the semiconductor substrate;

[0042] Hi) the semiconductor substrate is configured to measure the photocurrent, luminescence and / or electromagnetic radiation generated by the magnetic field sensitive optical element, in particular to determine a spatial distribution of said photocurrent and / or electromagnetic radiation.

[0043] 23) The method of embodiment 22, wherein the semiconductor substrate comprises a plurality of photodetectors, in particular photodiodes or an image sensor, in particular a CMOS or CCD image sensor comprising a plurality of pixels.

[0044] 24) The method of embodiment 22 or 23, wherein the magnetic field sensitive optical comprises a layer consisting of or comprising a crystalline structure having at least one defect, wherein the crystalline structure is diamond, silicon (Si) or SiC, and the defect a colour center, in particular a nitrogen defect and / or a nitrogen-vacancy center, and with said layer preferably being provided adjacent to, adjoining and / or in direct contact with th semiconductor substrate.

[0045] 25) The method of any preceding method embodiment, wherein a) the first intensity distribution is obtained while the light source is operated at a first, relatively higher output level of the light source, in particular a maximum output level; b) a second intensity distribution is obtained while the light source is operated at a second, relatively lower output level of the light source, in particular a minimum or zero output level, and / or is obscured; wherein c) the position of the object relative to the magnetic field sensor array is based on the first intensity distribution in combination with the second intensity distribution; in particular on a difference between the first intensity distribution and the second intensity distribution.

[0046] 26) The method of any preceding method embodiment, wherein a known geometry of the object is taken into account in determining the position and / or orientation of the object relative to the magnetic field sensor, in particular the magnetic field sensor array.

[0047] 27) The method of any of method embodiments 20, 21 , or 25 to 26 in combination with 20 or 21 , wherein the object is placed on the protection layer, preferably with a detachable protective foil interposed between the object and the protection layer.

[0048] 28) The method of any preceding method embodiment, wherein a) the object is placed on an object support, in particular an at least approximately horizontal object support surface; and b) the magnetic field sensor, in particular the magnetic field sensor array, is mounted above the object support, in particular at a known distance from the object support, and / or with a surface of the magnetic field sensor , in particular of an at least partially transparent protection layer comprised by the magnetic field sensor, at least approximately parallel to the object support surface. 29) The method of the preceding embodiment, wherein a light source is integrated with the object support, wherein, in particular, the object support surface is a light emitting surface, in particular configured to emit diffuse light.

[0049] 30) The method of any preceding method embodiment, further comprising correlating the position and / or orientation of the object relative to the magnetic field sensor, in particular the magnetic field sensor array, with magnetic field distribution as measured with the magnetic field sensor, in particular the magnetic field sensor array.

[0050] 31) The method of any preceding method embodiment, further comprising providing a dataset representative of the magnetic field distribution relative to object, in particular a) to one or more surfaces, edges, corners, and / or a center of gravity of the object, and / or b) to one or more markers, in particular fiducials, provided on the object.

[0051] 32) The method of any preceding method embodiment, further comprising the step of generating a 2-dimensional graphical representation of the magnetic field in which an indication of the position and / or orientation of the object is provided, in particular as an overlay.

[0052] 33) The method of any of embodiments 20, 21 , or 25 to 32 in combination with 20 or 21 , wherein the magnetic field sensor is a magnetic field sensor array according to one of embodiments 9 to 15, and the first intensity distribution is determined by means of the plurality of light sensitive elements.

[0053] 34) The method of any of embodiments 20 to 33, wherein the first and / or second intensity distribution is determined by evaluating signals from at least a subset of the magnetic field sensors, or from the plurality of photodetectors or the image sensor comprised by the semiconductor substrate.

[0054] 35) The method of any of embodiments 20 to 34, wherein the first and / or second intensity distribution is used to determine which ones of the plurality of magnetic field sensors, the plurality of photodetectors or which pixels of the image sensor comprised by the semiconductor substrate are completely obstructed from illumination by the light source, in particular the mapping light source, by the object.

[0055] 36) The method of any of embodiments 20, 21 , or 25 to 35 in combination with 20 or 21 , wherein the first and / or second intensity distribution is used to determine which ones of the plurality of magnetic field sensors are unobstructed from illumination by the light source.

[0056] 37) The method of any of embodiments 20 to 35, wherein the first and / or second intensity distribution is used to determine for which ones of the plurality of magnetic field sensors, the plurality of photodetectors or which pixels of the image sensor comprised by the semiconductor substrate illumination by the light source, in particular the mapping light source, is not obstructed through or by the object.

[0057] 38) The method of any of embodiments 20 to 37, wherein the first and / or second intensity distribution is used to determine which ones of the plurality of magnetic field sensors, the plurality of photodetectors or which the pixels of the image sensor comprised by the semiconductor substrate are partially obstructed from illumination by the light source, wherein, in particular, it is determined for each partially obstructed sensor, photodetector or pixel what percentage of a surface area of said sensor, photodetector or pixel, respectively, is obstructed by the object.

[0058] 39) Use of a magnetic field sensor array or a magnetic field camera, in particular for measuring a magnetic field distribution, said magnetic field sensor array or magnetic field camera comprising: a) a semiconductor substrate; b) a plurality of magnetic field sensors, in particular Hall sensors, provided on and / or within a surface layer of the semiconductor substrate; c) to determine an intensity distribution of a radiation, in particular electromagnetic radiation, in particular light from the UV-A, visible and / or near-infrared spectral ranges, impinging onto the surface layer of the semiconductor substrate.

[0059] 40) Use of a magnetic field sensor array or a magnetic field camera according to any preceding use embodiment, wherein the intensity distribution is determined by evaluating signals from at least a subset of the magnetic field sensors.

[0060] 41 ) Use of a magnetic field sensor array or a magnetic field camera according to any preceding use embodiment, wherein an intensity of the radiation varies or is varied over time, and the intensity distribution is determined by evaluating a variation of the signals from at least a subset of the magnetic field sensors over time.

[0061] 42) Use of a magnetic field sensor array or a magnetic field camera according to any preceding use embodiment, wherein a) the first set of signals from at least a subset of the magnetic field sensors is obtained while the radiation is at a first, relatively higher intensity level, in particular a maximum intensity level; b) a second set of signals from at least the subset of the magnetic field sensors is obtained while the radiation is at a second, relatively lower intensity level of the light source, in particular a minimum or zero output level , and / or is obscured; wherein c) the intensity distribution is determined by evaluating a change and / or difference between the signals in the first and second set.

[0062] 43) A magnetic field camera comprising a magnetic field sensor array according to one of embodiments 1 to 15.

[0063] 44) The magnetic field sensor array, method or magnetic field camera according to any respective one of embodiments 1 to 15, 20, 21 , 25 to 38 in combination with 20 or 21 , or 43, wherein at least one, in particular all of the Hall sensors of the magnetic field sensor array comprise a) a sensor body made of electrically conducting material; b) at least three, in particular four, terminals for electrically contacting said sensor body; c) said sensor being configured to i) when a current and / or voltage is applied between a first pair of terminals from a first set of pairs of terminals, ii) produce a voltage between a conjugated pair of terminals different from the first pair of terminals,

[0064] Hi) said voltage indicative of, in particular at least approximately linearly dependent on or at least approximately proportional to, a magnitude of a magnetic flux density penetrating the sensor body.

[0065] 45) The magnetic field sensor array, method or magnetic field camera according to any respective one of embodiments 1 to 15, 20, 21 , 25 to 38 in combination with 20 or 21 , or 43, wherein at least one, in particular all of the Hall sensors of the magnetic field sensor array comprise a) a sensor body made of electrically conducting material; b) at least three, in particular four, terminals for electrically contacting said sensor body; c) said sensor being configured to produce a voltage i) between a first pair of terminals from a first set of pairs of terminals, ii) when a current and / or voltage is applied between a conjugated pair of terminals different from the first pair of terminals,

[0066] Hi) said voltage indicative of, in particular at least approximately linearly dependent on, a magnitude of a magnetic flux density penetrating the sensor body.

[0067] 46) The magnetic field sensor array, method or magnetic field camera according to any respective one of embodiments 1 to 15, 20, 21 , 25 to 38 in combination with 20 or 21 , or 43, wherein at least one, in particular all of the Hall sensors of the magnetic field sensor array comprise a) a sensor body made of electrically conducting material; b) four terminals for electrically contacting said sensor body, comprising i) a first and a second terminal, in particular located at a distance from one another, ii) a third and a fourth terminal, in particular located at a distance from one another; c) said sensor being configured to produce a voltage i) between the third and fourth terminals when a current and / or voltage is applied between the first and second terminals, and / or ii) between the first and second terminals when a current and / or voltage is applied between the third and fourth terminals,

[0068] (1 ) said voltage indicative of, in particular at least approximately linearly dependent on or at least approximately proportional to, a magnitude of a magnetic flux density penetrating the sensor body.

[0069] 47) The magnetic field sensor array, method or magnetic field camera according to any respective one of embodiments 1 to 15, 20, 21 , 25 to 38 in combination with 20 or 21 , or 43 to 46, wherein at least one, in particular all of the Hall sensors of the magnetic field sensor array are comprised by a magnetometer as described in Appendix II, wherein each Hall sensor may in particular be comprised by a different magnetometer.

[0070] A magnetic field sensor array (not comprised by the literal scope of the current claims) as described, in particular, in embodiments 1 ) to 15) as set forth above may comprise a plurality of magnetic field sensors integrated in and / or arranged or otherwise provided on a semiconductor substrate. The (individual) magnetic field sensors may in particular be Hall sensors but may also function according to different principles. In particular, some or all of the sensors may be coils, in particular pick-up coils, which may, in particular, produce a voltage in the presence of a time varying magnetic field.

[0071] More specifically, such magnetic field sensors may be configured to measure one or more spatial components of a (local) magnetic flux density, commonly denoted by vector quantity B, and sometimes also referred to as magnetic induction; and / or a variation or change of the magnetic flux density over time.

[0072] A Hall sensor (sometimes also called Hall effect sensor) generally comprises a sensor body made of an electrically conducting material, which sensor body may also be referred to as a Hall element, as exemplary described in Wikipe- dia-Article “Hall effect sensor” in its version of 03 April 2023 (available at The electrically conducting material may in particular be a doped semiconductor material, preferably with a high electron mobility as e.g. provided by GaAs, InAs, InP, InSB, etc; and may in particular be provided as a doped region in the semiconductor substrate, in particular a surface layer of the semiconductor substrate. To detect a magnetic field and / or measure a magnitude of a magnetic flux density with a Hall sensor, a current, sometimes also referred to as biasing current, is imposed to flow in the sensor body. When a sufficiently strong magnetic field is present, charge carriers providing said current are deflected due to Lorentz force, which will give rise to a voltage between to properly chosen points on the sensor body, said voltage, which would not be present in the absence of the magnetic field, is generally referred to as Hall voltage. In general, the voltage will at least approximately be linearly dependent on the magnitude of the magnetic flux density, in particular at least approximately proportional to the magnitude of the magnetic flux density but for an offset voltage (which may at least approximately be zero, in particular under ideal circumstances).

[0073] The magnetic field sensors may be integrated into and / or with electric or electronic circuitry provided in and / or on the same semiconductor substrate, which circuitry may comprise active and passive elements comprising, inter alia, interconnects, resistors, capacitors, inductors, transistors, amplifiers, signal processing elements, etc.

[0074] The plurality of magnetic field sensors may be arranged as a matrix or an array comprising N lines and M columns, where N = M may hold. Typical values for N and M may be 16 or larger, in particular 128, 256 or even larger. The arrangement may be regular and / or uniform, with a constant distance between two adjacent lines and / or columns of sensors. Alternatively, the arrangement may also be irregular. The plurality of magnetic field sensors may comprise two or more subsets of sensors, wherein the sensors within in each subset are identical, but different from the sensors from any other subset. In particular, a first subset may comprise so called lateral Hall sensors, which may comprise a Hall element that extends essentially parallel to a surface and / or the surface layer of the semiconductor substrate, in particular with a depth or thickness of the Hall element in a direction perpendicular to the surface and / or the surface layer being much smaller than both a width and a length of the Hall element in directions parallel to the surface and / or the surface layer. Lateral Hall sensors may, in particular, be configured to measure magnetic fields and / or magnetic field components in directions at least essentially perpendicular to the surface and / or the surface layer of the semiconductor substrate. A second subset may, in particular, comprise vertical Hall sensors, which may in particular be configured to measure magnetic fields and / or magnetic field components in directions at least essentially parallel to the surface and / or the surface layer of the semiconductor substrate.

[0075] The plurality of magnetic field sensors of the magnetic field sensor array may be employed to measure and / or capture a (spatial) magnetic field distribution, wherein one or more quantities characterizing the (local) magnetic field at each of the sensors may be measured at least essentially simultaneously. The one or more quantities may in particular comprise (spatial) components of the (local) magnetic flux density vector. The magnetic field sensor array may thus be used as a or as part of a magnetic field camera. As the surface and / or the surface layer of the semiconductor substrate are, at least in general, at least essentially planar, such a magnetic camera may, in particular, measure and / or capture a two-dimensional, planar magnetic field distribution.

[0076] In accordance with the invention, an at least partially transparent protection layer may be provided to cover the plurality of magnetic field sensors. Such a protection layer me, in particular, be provided or formed on or above the semiconductor substrate, in particular on or above the surface layer of the semiconductor substrate, and may be of adequate size and shape to cover all the magnetic field sensors comprised by the magnetic field sensor array.

[0077] The at least partially transparent protection layer may allow for the plurality of magnetic field sensors - or at least a subset thereof - and / or other structures, features, elements etc., which may be arranged or otherwise provided on the semiconductor substrate, in particular on or in the surface layer of the semiconductor substrate, to remain visible, in particular to optical detection and / or inspection, in particular by means of an optical camera. Such an optical camera may be configured to deliver images obtained by it, and showing at least a subset of the plurality of magnetic field sensors and / or said other structures, features, elements etc., to an image processing system, unit, etc. This may significantly facilitate a determination and / or establishment of a (spatial) correlation between a magnetic field measured and / or captured using the magnetic field sensor array and a position, orientation, shape and / or geometry of an object, in particular a magnet, generating said magnetic field. The at least partially transparent protection layer may be of sufficient optical quality to allow for a sufficient visibility at the subset of the plurality of magnetic field sensors and / or said other structures, features, elements etc. In particular, it may be sufficiently homogenous, uniform, planar, thin, and / or have sufficiently smooth and parallel front and back surfaces.

[0078] The at least partially transparent protection layer may comprise or be made from tempered Glass as exemplary described in Wikipedia article https: / / en. Wikipedia. orq / w / index.php?title=Tempered qlass&oldid=1162627401 , and / or from Gorilla Glass™ as exemplary described in Wikipedia article :itle=Gorilla Glass&oldid:1167611796 It may also comprise or be made from polycarbonate.

[0079] For the plurality of magnetic field sensors - or at least a subset thereof - and / or other structures, features, elements etc. to be visible, in particular to optical detection and / or inspection, the magnetic field sensor array or any magnetic field camera in which it may be deployed should be free of any opaque layers or other opaque elements in front of and / or above the semiconductor substrate, in particular the plurality of magnetic field sensors. In particular, such layer or objects should not be present either below or behind the protection layer, nor above or in in front of it. Likewise, if the protection layer is only partially transparent, the magnetic field sensor array or any magnetic field camera in which it may be deployed should be free of any partially transparent layers or other partially transparent elements in front of and / or above the semiconductor substrate, which together with the partially transparent protection layer effectively form an at least essentially opaque element or layer.

[0080] For optimum protection, the at least partially transparent protection layer may be permanently attached to the semiconductor substrate and / or the surface layer. In particular, the at least partially transparent protection layer may be glued, bonded, cemented to the surface layer and / or the semiconductor substrate, in particular by means of a transparent adhesive.

[0081] Alternatively or in addition, the semiconductor substrate and the at least partially transparent protection layer may be cast together or potted together, in particular using a polymer, in particular an epoxy resin, which preferably remains at least partially transparent after curing. The polymer, together with the at least partially transparent protection layer, may thus form and / or provide an encapsulation which seals the plurality of magnetic field sensors and / or the surface layer and any further features possibly provided thereon off against an environment.

[0082] In certain embodiments, the at least partially transparent protection layer may be provided by a cast layer in itself. This may, in particular, be achieved by casting a polymer layer, in particular an epoxy resin layer, over at least the plurality of magnetic field sensors, and subsequently curing and / or hardening said polymer layer.

[0083] The at least partially transparent protection layer may only be transparent to wavelengths, in articular one or more isolated wavelengths, from one or more wavelength bands, and may be at least essentially opaque to other wavelengths, in particular wavelengths from outside said one or more wavelength bands. Said wavelength bands may, in particular, be subranges of wavelengths from a UV-A, visible and / or near-infrared spectral range. Bands and / or subranges may be relatively narrow, and only extend over a single up to a few nanometers. This may, in particular, be achieved by providing an interference filter as or as part of the partially transparent protection layer.

[0084] Alternatively or in addition, a maximum transparency of the partially transparent protection layer in the UV-A, visible and near-infrared spectral ranges may be limited at 80%, preferably 50%, and most preferably 20%. More specifically, a maximum of a transmittance or transmission coefficient of the at least partially transparent protection layer within the UV-A, visible and near-infrared spectral ranges may be 0.8, preferably 0.5, and most preferably 0.2, wherein the transmittance and / or transmission coefficient may, in particular, be defined as respectively described in Wikipedia articles https: / / en.wi kipedia.org / w / index.php?title=Transmittance&oldid=1105538040 and https: / / en.wi kipedia.org / w / index.php?title=Transmission coefficient&oldid=1114311821 .

[0085] A limited and / or restricted transparency may have advantages at least for certain configurations and / or under certain conditions, as will be explained in more detail below.

[0086] At least a some of the magnetic field sensors may comprise, in particular be marked with, a unique, visible identifier, wherein each identifier is different from any other identifier. Each visible identifier may comprise a symbol, in particular a combination of symbols, each of which may in turn comprise digits, numbers and / or letters. The unique identifiers may, in particular, be (consecutive) numbers. All identifiers may have, in particular consist of, the same number of symbols, in particular the same number of digits, numbers and / or letters.

[0087] Fig. 1 shows a top view of an exemplary magnetic field sensor array 1 , as seen when looking onto the surface layer of the semiconductor substrate 10 through the at least partially transparent protection layer (which is thus not shown in Fig. 1 ), i.e. in a direction corresponding to a -z-direction as indicated in Fig. 1. A total of 144 magnetic field sensors 11 are arranged in a regular array comprising A / = 12 lines and M = 12 columns, extending respectively in +x- and +y- directions. Lines and columns may be consecutively numbered using indices n and m, respectively, and beginning with n = 1 for the bottommost line 12, and m = 1 for the leftmost column 13. The magnetic field sensors may then be numbered using an index s, which may be defined according to s = 12 (n -1) + m. Said index may be reproduced (not shown in Fig. 1) on or next to at least some, in particular each, magnetic field sensor(s), e.g. in a three-digit format.

[0088] For illustration, magnetic field sensors with 001 , 052, 082, 088, 093 and 101 are identified in Fig. 1 (wherein the index s is reproduced in parentheses to avoid confusion with reference signs).

[0089] A method (not comprised by the literal scope of the current claims) in accordance with a first basic embodiment of the invention for determining a magnetic field around an object in accordance with a first basic embodiment of the invention, as in particular set forth in numbered embodiments 16 to 19 above, may comprise the steps of: a) placing the object onto or near a surface of a magnetic field sensor array, in particular a magnetic field sensor array according to one of embodiments 1 to 15 as detailed above, said magnetic field sensor array comprising a plurality of magnetic field sensors; b) obtaining an image showing at least a part of the object and a first subset of the magnetic field sensors, in particular by means of an optical camera; c) determining a position and / or orientation of the object relative to the magnetic field sensor array based on the image; d) measuring a magnetic field distribution with the magnetic field sensor array. The magnetic field may be created by the object, which may be a magnetic system as described initially, and / or, in particular, a permanent magnet or an electromagnet. The object may be brought into a vicinity of the magnetic field sensor array, in particular a surface of the magnetic field sensor array. More specifically, the object may be brought into physical contact with, in particular be placed on the surface of the magnetic field sensor array. If the magnetic field sensor array is a magnetic field sensor array according to one of embodiments 1 to 15 further above, the object may be placed on or onto the protection layer, wherein with a detachable and / or replaceable protective foil may be interposed between the object and the protection layer. Alternatively, the object may be placed onto and held in place by a support, which may in particular be configured to fix and / or support the object in a defined position relative to the magnetic field sensor array, in particular at a defined distance from the latter.

[0090] Once the object is in place, an image may be captured by means of an optical camera such that said image shows at least a part of the object, and at least some of the plurality of magnetic field sensors. Preferably, the image may show the whole object and all the magnetic field sensors that are not obstructed from the optical camera’s view by the object.

[0091] The optical camera, may, in particular be positioned opposite the magnetic field sensor array, in particular with an image plane of the optical camera at least essentially parallel to the surface layer of the semiconductor substrate and / or the at least partially transparent protection layer, in particular a surface of said at least partially transparent protection layer, said surface facing away from the semiconductor substrate; with the object located between the camera, in particular the image plane, and the magnetic field sensor array; and / or with an optical axes of the camera extending through the object.

[0092] The optical camera may, in particular, be equipped with a telecentric lens as exemplary described in Wikipedia article https: / / en.wi kipedia.orq / w / index.php?title=Telecentric lens&oldid=1126854072, and / or may in particular be configured to produce an image which is an orthographic projection of the object and the magnetic field sensor array, or at least of the portions imaged thereof, as exemplary described in Wikipedia article https: / / en.wi kipedia.orq / w / index.php?title=Orthoqraphic proiection&oldid=1148760590.

[0093] From the image, a position and / or orientation of the object relative to the magnetic field sensor array may be determined.

[0094] To simplify the determination of the position, at least a some of the magnetic field sensors may be marked with a unique, visible identifier as described above. To avoid any potential mixing up of identifiers, in particular when (automated) image processing means are employed to analyze the image, all identifiers may have, in particular consist of, the same number of symbols, in particular the same number of digits, numbers and / or letters. This may, in particular, avoid confusion when one or more identifiers are partially obstructed from the optical camera’s view by the object and / or the support.

[0095] An approximate position, in particular with respect to x- and y-directions, and / or orientation may rapidly and efficiently be determined by determining which magnetic field sensors from the magnetic field sensor array are obstructed from the optical camera’s view by the object, and which ones are not. If all the sensors comprise a unique, visible identifier, a respective process may easily be simplified and / or automized by means of image processing algorithms and / or an image processing system or unit employing such algorithms. Applying these, the image may be searched for identifiers, in particular numbers, the identifiers found are extracted and aggregated in a list or a table, which list or table may then be compared with another list or table comprising all know and / or used identifiers. In particular, if the identifier comprises only numbers, digits and / or text symbols, optical character recognition (OCR) methods as, for example, described in Wikipedia article https: / / en.wikipedia.orq / wZindex. php?title=Optical character recoqni- tion&oldid:1167300974 may be employed to search for, find, and / or extract the identifiers.

[0096] In a specialized and / or industrial production or manufacture of magnets and / or magnetic systems, geometry and / or dimensions of the object are generally known with high accuracy and / or well-defined tolerances. Respective data and / or information may be employed in determining the position and / or orientation, in particular to speed up a determination of the approximate position and / or orientation, and / or enhance an accuracy of said determination.

[0097] Fig. 2 illustrates an exemplary image 100 of an object 2 placed on the magnetic field sensor array 1 , in particular on semiconductor substrate 10 as may be obtained by means of an optical camera. As may be seen, magnetic field sensors numbered 052 to 058, 064 to 070, 078 to 081 , and 089 to 092 are completely obstructed from the optical camera’s view by object 2, and thus not visible in the image. Magnetic field sensors 082, 088, 093, and 101 to 104 are partially obstructed, so that a portion of each of said latter sensors remains visible in the image.

[0098] As a non-limiting example, simulations may be carried out, in particular on a computer which may employ ray-tracing methods, algorithms and / or software as exemplary described in Wikipedia article https: / / en.wiki pedia.orq / w / in- to determine, from the data and or information on the known geometry and / or dimensions of the object, and, in particular, information, in particular parameters, regarding the illumination and / or the light source, an expected image for each of a plurality of hypothetical positions and / or orientations of the object 2. An actual image obtained by the optical camera may then be compared with each of the plurality of expected images and a difference and / or deviation be determined and / or measured. An actual position and / or orientation of the object may then be assumed to correspond to that hypothetical position and / or orientation of the object for which the difference and / or deviation is smallest as compared to the expected images for all other hypothetical positions and / or orientations.

[0099] In addition to being used for determining a position and / or orientation of the object relative to the magnetic field sensor array, the image may be used to verify a physical integrity of the object and / or detect any physical and / or mechanical damage, e.g. due to so called edge chipping. This may in particular be done by comparing an actual shape of the object as visible in the actual image obtained by the optical camera with an expected shape based on and / or derived from the known geometry and / or dimensions of the object. If a deviation between the actual and expected shape exceeds an acceptable level, which may be represented by a predetermined threshold, the object may be considered (physically or mechanically) defective, and may accordingly be sorted out.

[0100] A method in accordance with a second basic embodiment of the invention for determining a magnetic field around an object, as in particular set forth in numbered, above embodiments 20, 21, and 25 to 38 in as far the latter refer to any one of the former, may comprise the steps of: a) placing the object onto or near a surface of a magnetic field sensor; b) illuminating the object and the magnetic field sensor with a light source; c) determining a first intensity distribution, in particular a first intensity distribution at or near a surface layer of a semiconductor substrate comprised by the magnetic field sensor; d) determining a position and / or orientation of the object relative to the magnetic field sensor based on the first intensity distribution; e) measuring a magnetic field distribution with the magnetic field sensor. In the method in accordance with the second basic embodiment, the magnetic field sensor may be a or comprise a magnetic field sensor array, in particular a magnetic field sensor array according to one of the respective embodiments as set forth above.

[0101] More specifically, a method for determining a magnetic field around an object in accordance with a second basic embodiment of the invention may comprise the steps of: a) placing the object onto or near a surface of a magnetic field sensor array according to one of the respective embodiments as set forth above; b) illuminating the object and the magnetic field sensor array with a light source; c) determining a first intensity distribution, in particular a first intensity distribution at or near the surface layer of the semiconductor substrate; d) determining a position and / or orientation of the object relative to the magnetic field sensor array based on the first intensity distribution; e) measuring a magnetic field distribution with the magnetic field sensor array.

[0102] This method variant has the advantage that no separate or external optical camera is required to determine the position and / or orientation of the object relative to the magnetic field sensor array, by making use of the fact that the object, when placed close to the magnetic field sensor array, in particular in physical contact with the magnetic field sensor array, will cast a shadow onto the magnetic field sensor, and / or at least partially obscure and / or obstruct an illumination and / or environmental lighting.

[0103] Since semiconductor materials like e.g. silicon are sensitive to light, the magnetic field sensor array may also function as a replacement for an optical camera. Each pixel may accordingly contain light-sensitive components that produce a grayscale image resembling the object captured by the magnetic field sensor array and / or magnetic camera consisting of or comprising said array. Essentially, optical means are used to measure the object's shadow. By illuminating the object appropriately, its shadow can provide accurate information about its size, position, and orientation.

[0104] In manufacturing scenarios, one typically only needs to determine the object's geometric position, and often the ideal shape of the object is already known. Therefore, a low-resolution image may be sufficient to ascertain the object's position and orientation sufficiently precisely. For instance, the light-sensitive elements in each pixel can be photodiodes or even temperature sensors. To enhance the contrast of the signal, it may be necessary to employ a controlled light source and measure the difference between images captured with the light turned on and off.

[0105] There are two advantages to utilizing the magnetic camera as replacement for an optical camera:

[0106] Firstly, there is no need to install a separate optical camera since the magnetic camera can serve both purposes.

[0107] This eliminates the requirement for additional equipment and simplifies the setup.

[0108] Secondly, there is no necessity to separately correlate the optical image with the magnetic image. Both images are captured within the same coordinate system, ensuring the measurements are inherently aligned. Consequently, the system's design already ensures that the measurements from both the optical and magnetic perspectives are fully synchronized, eliminating the need for any further alignment or correlation procedures.

[0109] Illumination may, in particular, be provided in the form of a collimated beam, that may be directed at least essentially parallel to a surface normal of a surface of the semiconductor substrate and / or the at least partially transparent protection layer. In particular, when the object is located on the surface of the magnetic field sensor array, in particular on the protection layer, a diffuse lighting and / or illumination may also be used.

[0110] A light source for providing such illumination, may, in particular be positioned opposite the magnetic field sensor array, with the object located between the light source and the magnetic field sensor array.

[0111] Fig. 3 illustrates an intensity distribution on the surface of the semiconductor substrate 10 for an exemplary situation where object 2 (not shown in Fig. 3) is placed directly on the surface of the magnetic field sensor or the at least partially transparent protection layer. Under collimated or diffuse illumination / lighti ng as described above, the presence of the object gives rise to a shaded area 21 in which the intensity is at least essentially equal to zero. Outside said shaded are 21 , light from the illumination and / or lighting will reach the surface of the semiconductor substrate 10 at least essentially unobstructed by the object 2, so that intensity in this area will be given by an intensity of the illumination and / or lighting - as transmitted by a partially transparent protection layer if such a layer is present. The shaded area 21 is thus indicative of the position and / or orientation of the object relative to the magnetic field sensor array.

[0112] As may be seen from Fig. 3, magnetic field sensors numbered 052 to 058, 064 to 070, 078 to 081 , and 089 to 092 are completely obstructed and / or shaded off from illumination by object 2. Thus, essentially no light at all from any illumination source will reach said sensors.

[0113] The method in accordance with the second basic embodiment of the invention may, in particular, be carried out in a first variant using a magnetic field sensor array according to one of embodiments 9 to 15 as set forth above, wherein the plurality of light sensitive elements may be used to determine, in particular measure, the first light intensity distribution, from which in turn information on a position and / or orientation of the shadow and / or an area of the magnetic field sensor array obscured by the object may be obtained and / or derived.

[0114] The method may, however, also be carried out using a magnetic field sensor array without any dedicated and / or specific light sensitive elements, in particular with a magnetic field sensor array free of photodetectors, photodiodes and / or CCD cells.

[0115] In a second variant of the method in accordance with the second basic embodiment of the invention, this may be done by using temperature sensors to determine the first intensity distribution. Temperature sensors may be provided with at least some, in particular all, of the magnetic field sensors. As a characteristic of Hall sensors is generally temperature dependent, at least a single temperature sensor is provided as part of most magnetic field sensor arrays comprising or made up of Hall sensors. Highly accurate Hall sensor arrays generally comprise one temperature sensor for each Hall sensor, wherein each temperature sensor may in particular be arranged closely, in particular as closely as physically possible, to a sensor body and / or the Hall element of each respective Hall sensor. The temperature sensors may be semiconductor temperature sensors, and may be integrated with the semiconductor substrate of the magnetic field sensor array and / or the electric or electronic circuitry, both in accordance with the principles as set forth in Wikipedia article https: / / de.wi kipedia.orq / w / index.php?title=Temperatursensor&oldid=233732527.

[0116] It has been observed that typical semiconductor temperature sensors also react to illumination, in particular with near-infrared radiation, but also with light from the visible and / or near UV-A spectrum if an intensity of the illumination is sufficiently high. The first intensity distribution may thus be determined based on the signals, in particular ordinary signals, delivered by the temperature sensors under adequate illumination conditions, wherein said signals may, in particular, be regarded as intensity signals, possibly containing an at least essentially constant and / or uniform offset. An appropriate illumination wavelength or wavelength range or ranges and a sufficient illumination intensity may easily be determined by a person skilled in the art by way of experimentation. In respective experiments, a dependence of ordinary signals provided by the temperature sensors to changing illumination wavelength, wavelength range and / or intensity may be observed, wherein, in particular, any other parameters and / or environmental influence factors may be left unchanged. In the present context, the term “ordinary signal(s)” of a sensor may be understood to refer to such signal(s) and / or measurements as are normally considered indicative of a quantity the sensor is destined to sense and / or measure, and / or analyzed and / or otherwise evaluated to determine and / or obtain such quantity. An ordinary signal of a temperature sensor may thus in particular be a temperature signal or measurement.

[0117] When carrying out experiments to refine the second variant of the method as described above, it has been found with surprise that the Hall sensors themselves exhibit a light sensitivity which may be sufficiently strong to determine the first intensity distribution with sufficient accuracy from measurements with the magnetic field sensors themselves. In a third variant of the second basic embodiment, the first intensity distribution may in particular be determined based on signals, in particular ordinary signals, provided by the plurality of magnetic field sensors under illumi nation / lightni ng. An ordinary signal of a Hall sensor may accordingly be a magnetic field signal or measurement. The signals may, in particular, be regarded as intensity signals, possibly containing an at least essentially constant and / or uniform offset. A more detailed description as to how Hall sensors or elements may be used to determine the first intensity distribution is provided in Appendix I below. Alternatively or in addition, the first intensity distribution may also be determined by employing a method for testing a Hall sensor as described in Swiss patent application CH000620 / 2023 filed 12 June 2023, to which some modifications may be made. Said testing method and possible modifications will be described in detail in Appendix II further below.

[0118] A light sensitivity of a temperature sensor or a Hall sensor may be determined by observing and / or determining how much an ordinary signal, in particular an amplitude thereof, provided by the respective sensors changes when an intensity and / or amplitude of the illumination changes by one or more known amounts or factors. The light sensitivity may then be defined as a ratio of the change(s) in signal relative to the change(s) in illumination intensity and / or amplitude. Light sensitivities of both temperature sensors and Hall sensor will in general significantly depend on a wavelength or wavelength range or distribution of the illumination, and may accordingly be determined for a plurality of wavelength and / or wavelength ranges. Light sensitivity may, in particular, be expressed as a function of wavelength.

[0119] In semiconductor sensor arrays as described above, the at least partially transparent protection layer may have a maximum transmittance and / or transmission coefficient at a wavelength or in a wavelength range for which a light sensitivity of the temperature sensors and / or Hall sensors is significantly smaller than a maximum light sensitivity, in particular a maximum of the light sensitivity within the UV-A, visible and / or near-infrared spectral ranges. Alternatively or in addition, a transmittance and / or transmission coefficient at a wavelength or in a wavelength range for which a light sensitivity of the temperature sensors and / or Hall sensors is at a maximum may be significantly smaller than a maximum transmittance and / or transmission coefficient of the at least partially transparent protection layer. This may, inter alia, reduce a negative impact of ambient light from the UV-A, visible and / or near-infrared spectral ranges on temperature and / or magnetic field measurements. An approximate position and / or orientation of the object may rapidly and efficiently be determined by determining for which magnetic field sensors from the magnetic field sensor array illumination is obstructed by the object, and for which ones it is not.

[0120] In particular in combination with the third variant, this determination may be carried out directly on the intensity distribution as determined based on signals, in particular ordinary signals, provided by the plurality of magnetic field sensors. In particular, no spatial offset needs to be accounted for, as may, in particular, be the case with the first variant due to the fact that the light sensitive elements need to be provided apart from the magnetic field sensors for elementary reasons. An analogous approach may be taken for the second variant, when a distance between magnetic field sensors and respective, associated temperature sensors may be neglected.

[0121] As may be seen from Fig. 3, magnetic field sensors 082, 088, 093, and 101 to 104 are partially obstructed and / or shaded off. Under ill umi nation / lighting, said sensors will thus receive some light, albeit with an amount of light reduced as compared to completely unobstructed sensors like, e.g. 001 , 0051 , 083, 087, etc. It was found that this has the effect that the partially obstructed sensors see an effectively reduced intensity / amplitude as compared to fully unobstructed sensors, wherein a degree and / or amount of reduction is indicative of, in particular corresponds at least approximately to, what percentage of a surface area of a partially obstructed sensor is obstructed by the object.

[0122] In particular when illumination is sufficiently uniform, it is thus possible to determine for each sensor whether it is completely obstructed and / or shaded off from illumination by object 2, completely unobstructed, or partially obstructed and / or shaded off from illumination by object 2, wherein in the latter case, a percentage of the surface area of the respective sensor which is obstructed.

[0123] Knowledge of which sensors are partially obstructed, in particular together with knowledge of what percentage of a respective surface area of each of said sensors, may be used to enhance an accuracy of the determination of the position and / or orientation of the object.

[0124] As a sensitivity of temperature and / or magnetic field sensors to illumination with wavelengths from the UV-A, visible and / or near-infrared spectral range may be low, a second intensity distribution may be obtained with different illumination conditions present, in particular without illumination. A differential intensity distribution may then be obtained by subtracting the first intensity distribution from the second intensity distribution or vice versa. The differential intensity distribution may have significantly enhanced contrast, as the difference in illumination level or obscuring the illumination will only affect temperature sensors or magnetic field sensors not fully obstructed by the object. As such, the differential intensity distribution may in particular allow for a more accurate determination of what percentage of the surface area of a partially obstructed sensor is obstructed.

[0125] A respective process may again easily be simplified and / or automized by means of image processing algorithms and / or an image processing system or unit employing such algorithms. These may, in particular be applied to the first intensity distribution as obtained according to the second and third variants as described further above or to the differential intensity distribution, in particular to carry out a number of image corrections and / or enhancements, as for example offset correction, binarization, thresholding, sharpening (in particular of edges), smoothing (in particular of areas), and / or image analysis methods as for example image segregation, object recognition and / or localization, etc.

[0126] As already mentioned above, geometry and / or dimensions of the object are generally known with high accuracy and / or well-defined tolerances in a specialized and / or industrial production or manufacture of magnets and / or magnetic systems. Respective data and / or information may again be employed in determining the position and / or orientation, in particular to speed up a determination of the approximate position and / or orientation, and / or enhance an accuracy of said determination.

[0127] As a non-limiting example, simulations may be carried out, in particular on a computer which may employ ray-tracing methods, algorithms and / or software as exemplary described in Wikipedia article https: / / en.wiki pedia.orq / w / in- dex. php?title= lid=1149518029 to determine, from the data and or information on the known geometry and / or dimensions of the object, and, in particular, information, in particular parameters, regarding the illumination and / or the light source, an expected position and / or orientation of the shaded area 21 for a plurality of hypothetical positions and / or orientations of the object 2. Alternatively or in addition, information on which sensors would be fully or partially obstructed, in particular together with knowledge of what percentage of a respective surface area of each of said sensors, and / or which ones are fully unobstructed, may be derived for each of the hypothetical positions and / or orientations of the object 2. An actual position and / or orientation of the shaded area 21, and / or knowledge of which sensors are actually fully or partially obstructed (and to what percentage), and / or which ones are fully unobstructed, may then be compared with respective expected data / information for each of the hypothetical positions and / or orientations of the object 2 and a difference and / or deviation be determined and / or measured. An actual position and / or orientation of the object may then be assumed to correspond to that hypothetical position and / or orientation of the object for which the difference and / or deviation is smallest as compared to all other hypothetical positions and / or orientations.

[0128] A method in accordance with a third basic embodiment of the invention for determining a magnetic field around an object, as in particular set forth in numbered embodiments 22 to 25 above and any embodiments referring thereto, may comprise the steps of: a) placing the object onto or near a surface of a magnetic field sensor; b) illuminating the object and the magnetic field sensor array with a light source, in particular a mapping light source; c) determining a first intensity distribution, in particular a first intensity distribution at or near a surface layer of a semiconductor substrate comprised by the magnetic field sensor; d) determining a position and / or orientation of the object relative to the magnetic field sensor based on the first intensity distribution; measuring a magnetic field distribution with the magnetic field sensor.

[0129] The magnetic field sensor may, in particular, comprise a magnetic field sensitive optical element, in particular layer, configured to generate a photocurrent and / or an electromagnetic radiation, wherein a) the photocurrent and / or an electromagnetic radiation is dependent on and / or varies with a magnetic field, in particular a magnetic flux density at or within the magnetic field sensitive optical element; b) the magnetic field sensitive optical element is provided in proximity to the semiconductor substrate, in particular the surface layer of the semiconductor substrate; c) the semiconductor substrate is configured to measure the photocurrent and / or electromagnetic radiation generate by the magnetic field sensitive optical element, in particular to determine a spatial distribution of said photocurrent and / or electromagnetic radiation.

[0130] The method in accordance with the third basic embodiment of the invention may in particular be applied when using magnetic field sensors and / or cameras as described in or based on the principles described in WO 2022 / 136175 A1 (cf. , in particular, claims 1 and 10), albeit without necessarily making use of all features in any one of the claim, comprised by any one of the embodiments described, and / or of the teachings contained in said document. In contrast to the magnetic field sensor arrays of embodiments 1 to 15 and the method embodiments 20, 21 and the method embodiments as referring thereto, the semiconductor substrate of such magnetic field sensors and / or cameras in itself is, in general, not configured to determine magnetic fields, in particular magnetic flux densities, i.e. without the magnetic field sensitive optical element. In particular, the semiconductor substrate of such magnetic field sensors and / or cameras may be free of Hall-sensors and / or pick-up coils.

[0131] Accordingly, the magnetic field sensitive optical element may comprise or consist of a first material which, when subjected to a physical excitation and / or physical activation, generates a luminescence or a photocurrent, wherein said luminescence or photocurrent depends on the magnetic flux density. The semiconductor substrate, in turn, may comprise or constitute means for measuring the luminescence, in particular, but not necessarily, by means of a detection signal representing and / or reflecting the strength of the detected luminescence signal or photocurrent signal. Physical excitation may be provided electrically or electromagnetically, inter alia optically, in particular by illumination with an appropriate wavelength. Illumination for excitation purposes may also be referred to as excitation illumination and may, in particular, be provided by an excitation light source.

[0132] More specifically, the first material may comprise or be constituted by a crystalline structure having at least one defect, wherein the first material may, in particular, be diamond, silicon (Si) or SiC, and the defect a colour center - in particular as described in lines 8 to 25 on p. 5 of WO 2022 / 136175 A1 and the further references cited therein.

[0133] The magnetic field sensitive optical element may, in particular, consist of or comprise a layer of the first material, in particular a diamond layer having nitrogen defects and / or nitrogen-vacancy centers, which exhibits a luminescence which significantly depends on magnetic flux density (cf, WO 2022 / 136175 A1 , p. 3, first paragraph), in particular decreases with increasing magnetic flux density. Excitation may efficiently be provided by excitation illumination with light having wavelengths between 500 and 600nm, while luminescence may occur at wavelengths between 600 and 800nm.

[0134] The semiconductor substrate may, in particular, comprise a photodetector, preferably a plurality of photodetectors, in particular (a) photodiode(s). More specifically, the semiconductor substrate may comprise an image sensor, in particular a CMOS image sensor or a charge-coupled device, CCD, image sensor.

[0135] The magnetic field sensitive optical element may be arranged in proximity to the semiconductor substrate, in particular on the semiconductor substrate, and / or the image sensor. Where the optical element is or comprises a layer of the first material, said layer may preferably be arranged in parallel to a surface of the semiconductor substrate and / or the image sensor, in particular with one or both surfaces of the layer at least essentially parallel to the surface of the semiconductor substrate and / or with the semiconductor substrate located on a first side of the layer. The layer and the semiconductor substrate may be arranged in a stacked fashion, and / or in such a way that the layer covers the plurality of photodetectors or the image sensor, preferably the entire image sensor. The optical element, in particular the layer, may be attached to the semiconductor substrate, in particular in a temporary, releasable and / or separable manner, which may, in particular, allow for the optical element or layer to be separated from the semiconductor substrate without damage to either of them.

[0136] Where the optical element is or comprises a layer of the first material, excitation illumination may, in particular, be applied laterally, in particular at and / or through one or more edges of the layer, rather than through one (or both) of the layer’s surfaces, in particular by means of LEDs arranged one or more edges. Attenuation means for preventing wavelengths other than those of the electromagnetic radiation generated by the magnetic field sensitive optical element, in particular due to luminescence as described above, may be provided between the optical element and the semiconductor substrate, and may, in particular, cover the plurality of photodetectors or the image sensor. Such means may in particular be configured to prevent light having wavelengths used for (optical) excitation of luminescence or photocurrent in the optical element from reaching the photodetectors or the image sensor.

[0137] With such an arrangement, the plurality of photodetectors or the image sensor may be used to capture an image or a spatial distribution of an intensity of the luminescence, which may be referred to as an activated intensity distribution or luminescence intensity distribution. Each signal provided by one of the plurality of the photodetectors or from a pixel of the image sensor may be regarded as a detection signal as mentioned above. The image or spatial distribution of the intensity of the luminescence may be considered representative of a spatial distribution of the magnetic field, in particular the magnetic flux density, within the layer of the first material, albeit with in inverse relation, i.e. with regions of relatively low intensities corresponding to regions with relatively strong magnetic field and vice versa.

[0138] A position and / or orientation of the object a magnetic field around which shall be determined may, in particular, be obtained in a manner following the principles as detailed in combination with the second basic embodiment of the invention as detailed above. Once the object has been placed or otherwise disposed on or near a surface of a magnetic field sensor, which surface may in particular be a surface of the magnetic field sensitive optical element, in particular of the layer which may constitute the optical element or be comprised by it, the object and the magnetic field sensor comprising the magnetic field sensitive optical element and the semiconductor substrate are illuminated by means of a light source. Where excitation is done optically, a light source other than the (excitation) light source used for excitation may advantageously be used, in particular a mapping light source. Illumination by a mapping light source may be referred to as mapping illumination to allow for better distinction from excitation illumination, at least in the general case when the two are different and / or separate.

[0139] (Mapping) illumination may, in particular, be provided in the form of a collimated beam, that may be directed at least essentially parallel to a surface normal of a surface of the semiconductor substrate, in particular the image sensor, and / or the layer which may constitute the optical element or be comprised by it. In particular, when the object is located on the surface of the layer or any further layer disposed on said former layer, diffuse lighting and / or illumination may also be used to advantage. A light source for providing such illumination, in particular a mapping light source, may, in particular, be positioned opposite the semiconductor substrate, with the object located between the light source and the magnetic field sensor array.

[0140] Mapping illumination may in particular employ wavelengths suitable for physical excitation and / or physical activation of the first material, and or corresponding to wavelengths generated by the first material following physical excitation, in particular when attenuation means as described above are present in the magnetic field sensor.

[0141] Fig. 4 illustrates an exemplary first intensity distribution on the surface of the semiconductor substrate 10’ for an exemplary situation where object 2 (not shown in Fig. 4) is placed above, adjacent to and / or opposite the semiconductor substrate and / or the magnetic field sensitive optical element (not shown in Fig. 4). A plurality of pixels 31 is formed in the semiconductor substrate and arranged in lines and columns. A total of 144 pixels 31 are arranged in a regular array comprising A / = 12 lines and M = 12 columns, extending respectively in +x- and +y-directions. Lines and columns may be consecutively numbered using indices n and m, respectively, and beginning with n = 1 for the bottommost line 312, and m = 1 for the leftmost column 313. The pixels may then be numbered using an index s, which may be defined according to s = 12 (n -1 ) + m. For illustration, pixels corresponding to indices 001 , 052, 082, 088, 093 and 101 are identified in Fig. 4 (wherein each index s is reproduced in parentheses to avoid confusion with reference signs).

[0142] Under collimated or diffuse illumination / lighting as described above, the presence of the object gives rise to a shaded area 21 ’ in which a first or obstructed intensity is at least essentially equal to zero. Outside said shaded area 21 ’, light from the illumination and / or lighting will reach the surface of the semiconductor substrate 10 at least essentially unobstructed by the object 2, so that a second or unobstructed intensity in this area will be given by an intensity of the illumination and / or lighting - as possibly attenuated by the attenuation means or other means if present. The shaded area 2T is thus indicative of the position and / or orientation of the object relative to the magnetic field sensor array. Notably, the second or unobstructed intensity may at least partially be contributed to by luminescence, which may occur outside shaded area 2T when mapping illumination contains wavelengths capable of exciting electromagnetic radiation from the magnetic field sensitive optical element. Within shaded area 2T, on the other hand, no luminescence is received in general.

[0143] An approximate position and / or orientation of the object may rapidly and efficiently be deter-mined by determining for which of the plurality of photodetectors or for which pixels of the image sensor illumination is obstructed by the object, and for which ones it is not.

[0144] As may be seen from Fig. 4, pixels numbered 052 to 058, 064 to 070, 078 to 081 , and 089 to 092 are completely obstructed and / or shaded off from illumination by object 2. Thus, essentially no light at all from any illumination source will reach said sensors.

[0145] As may be seen from Fig. 4, pixels 082, 088, 093, and 101 to 104 are partially obstructed and / or shaded off. Under illumination / lighting, said pixels will thus receive some light, albeit with an amount of light reduced as compared to completely unobstructed sensors like, e.g. 001 , 0051 , 083, 087, etc. It was found that this has the effect that the partially obstructed pixels see an effectively reduced intensity / amplitude as compared to fully unobstructed pixels, wherein a degree and / or amount of reduction is indicative of, in particular corresponds at least approximately to, what percentage of a surface area of a partially obstructed pixels is obstructed by the object 2.

[0146] In particular when illumination is sufficiently uniform, it is thus possible to determine for each pixel whether it is completely obstructed and / or shaded off from illumination by object 2, completely unobstructed, or partially obstructed and / or shaded off from illumination by object 2, wherein in the latter case, a percentage of the surface area of the respective pixel which is obstructed.

[0147] Knowledge of which pixels are partially obstructed, in particular together with knowledge of what percentage of a respective surface area of each of said pixels, may be used to enhance an accuracy of the determination of the position and / or orientation of the object.

[0148] As an effective sensitivity of the plurality of photodetectors or the pixels of the image sensor to mapping illumination may be relatively low for various reasons that will be explained in more detail further below, a second intensity distribution may be obtained with different illumination conditions present, in particular without illumination. A differential intensity distribution may then be obtained by subtracting the first intensity distribution from the second intensity distribution or vice versa. The differential intensity distribution may have significantly enhanced contrast, as the difference in illumination level or obscuring the illumination will only affect pixels not fully obstructed by the object. As such, the differential intensity distribution may in particular allow for a more accurate determination of what percentage of the surface area of a partially obstructed sensor is obstructed.

[0149] A respective process may again easily be simplified and / or automized by means of image processing algorithms and / or an image processing system or unit employing such algorithms. These may, in particular be applied to the first intensity distribution, in particular to carry out a number of image corrections and / or enhancements, as for example offset correction, binarization, thresholding, sharpening (in particular of edges), smoothing (in particular of areas), and / or image analysis methods as for example image segregation, object recognition and / or localization, etc.

[0150] As already mentioned above, geometry and / or dimensions of the object are generally known with high accuracy and / or well-defined tolerances in a specialized and / or industrial production or manufacture of magnets and / or magnetic systems. Respective data and / or information may again be employed in determining the position and / or orientation, in particular to speed up a determination of the approximate position and / or orientation, and / or enhance an accuracy of said determination.

[0151] As already described further above, simulations may be carried out, in particular on a computer which may employ ray-tracing methods, algorithms and / or software to determine, from the data and or information on the known geometry and / or dimensions of the object, and, in particular, information, in particular parameters, regarding the illumination and / or the light source, an expected position and / or orientation of the shaded area 21 or 2T, in particular an expected shaded area, for a plurality of hypothetical positions and / or orientations of the object 2. Alternatively or in addition, information on which sensors would be fully or partially obstructed, in particular together with knowledge of what percentage of a respective surface area of each of said sensors, and / or which ones are fully unobstructed, may be derived for each of the hypothetical positions and / or orientations of the object 2. An actual position and / or orientation of the shaded area 21 or 2T, in particular an actual shaded area 21 or 2T, and / or knowledge of which sensors are actually fully or partially obstructed (and to what percentage), and / or which ones are fully unobstructed, may then be compared with respective expected data / information for each of the hypothetical positions and / or orientations of the object 2 and a difference and / or deviation be determined and / or measured. An actual position and / or orientation of the object may then be assumed to correspond to that hypothetical position and / or orientation of the object for which the difference and / or deviation is smallest as compared to all other hypothetical positions and / or orientations.

[0152] As also described in WO 2022 / 136175 A1 , the magnetic field sensor and / or camera may, in addition to the semiconductor substrate and the magnetic field sensitive optical element, comprise means for physical excitation integrally formed with the magnetic field sensitive optical element. Where the optical element is or comprises a (first) layer of the first material, such means may be provided on a second side of said layer, in particular opposite and / or across from the semiconductor substrate, and / or with said second side facing away from the semiconductor substrate, and may also consist of or comprise a (second) layer. Such means for means for physical excitation may, in particular, comprise an LED structure as described on p. 14 of WO 2022 / 136175 A1. The object a magnetic field around which shall be determined may then be placed adjacent to the means for physical excitation, in particular onto or on said means.

[0153] Means for physical excitation as described in the preceding paragraph may complicate mapping illumination, as they may substantially obstruct and / or absorb light emitted from the mapping light source, and thus reduce the effective sensitivity of the plurality of photodetectors or the pixels of the image sensor to mapping illumination. This may, e.g., be overcome by obtaining a differential intensity distribution as described further above. The shaded area may further used to verify a physical integrity of the object and / or detect any physical and / or mechanical damage, e.g. due to so called edge chipping. This may in particular be done by comparing (actual) shaded area 21 or 2T produced by the object with the respective expected shaded area, which expected area may in particular be determined based on and / or derived from the known geometry and / or dimensions of the object, and / or illumination parameters. If a deviation between expected shape and actual shape 21 or 2T exceeds an acceptable level, which may be represented by a predetermined threshold, the object may be considered (physically or mechanically) defective, and may be sorted out.

[0154] This description - including the one in the appendices - and any accompanying drawings that illustrate aspects and embodiments of the present invention should not be taken as limiting the claims defining the protected invention. In other words, while the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Various mechanical, compositional, structural, electrical, and operational changes may be made without departing from the spirit and scope of this description and the claims. In some instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure the invention. Thus, it will be understood that changes and modifications may be made by those of ordinary skill within the scope and spirit of the following claims. In particular, the present invention covers further embodiments with any combination of features from different and / or individual embodiments as described above and below. Embodiments in accordance with the invention may, in particular, include further and / or additional features, elements, aspects, etc. not shown in the drawings or described above.

[0155] The disclosure also covers all further features shown in any Figure, individually, although they may not have been described in the afore or following description. Also, individual alternatives of the embodiments described in any Figure and the description and individual alternatives of features thereof can be disclaimed from the subject matter of the invention or from disclosed subject matter. The disclosure comprises subject matter consisting of the features defined in the claims or the exemplary embodiments as well as subject matter comprising said features.

[0156] The present disclosure also includes embodiments with any combination of features which are mentioned or shown above and / or below, in various embodiments or variants. It also includes individual features as shown in the Figures, even if they are shown there in connection with other features and / or are not mentioned above or below. The disclosure comprises embodiments which exclusively comprise the features described in the claims or the exemplary embodiments, as well as those which comprise additional other features. The steps of any method disclosed above or claimed below may preferably be carried out according to the order in which they are presented, but may also be carried out in a different order.

[0157] Furthermore, in the claims the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single unit or step may fulfil the functions of several features recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The terms "essentially", “substantially”, "about", "approximately" and the like in connection with an attribute or a value particularly also define exactly the attribute or exactly the value, respectively. The term "about" in the context of a given numerate value or range refers to a value or range that is, e.g., within 20%, within 10%, within 5%, or within 2% of the given value or range. Components described as coupled or connected may be electrically or mechanically directly coupled, or they may be indirectly coupled via one or more intermediate components. Any reference signs in the claims should not be construed as limiting the scope. Unless stated otherwise, it shall be assumed throughout this entire document that a statement a ~ b may imply that |a- b| / (|a|+|b|) < 0.2, preferably | a-b\ / ( |a| + |b| ) < 0.01 , wherein a and b may represent arbitrary quantities, parameters and / or variables as described and / or defined anywhere in this document, or as otherwise known to a person skilled in the art. Further, a statement that a is at least approximately equal or at least approximately identical to b may imply that a ~ b, and not exclude that a = b. Further, unless stated otherwise, throughout this entire document, a statement a » b may imply that a > 5b, preferably a > 100b; and statement a « b may imply that 5a < b, preferably 100a < b. A statement that a is significantly larger than b may imply that a » b. A statement that a is significantly smaller than b may imply that a « b.

[0158] Features, properties, etc. mentioned in the description but placed in parentheses may, but do not necessarily have to, be present and / or required, and are thus to be regarded as optional in principle. Such features, properties, etc. may serve the better understanding of the invention by hiding implicit, but non-essential aspects of the invention. Such features, properties, etc. may, in articular, be preferred and / or advantageous.

[0159] Unless specified otherwise, a connection, in particular between any two entities, including in particular nodes, points, terminals, elements, devices, etc. or combinations thereof, may refer to an electrically conductive connection, as in particular established by a wire, cable, busbar, a conductive track, trace or line on e.g. a (printed) circuit board, solder, etc. The electrically conductive connection is preferably at least substantially direct, in particular without any discrete elements, as, in particular, resistors, capacitors, inductors, or other passive or active elements or devices connected between the connected entities. The electrically conductive connection thus has at least essentially negligible resistance, capacitance and inductance, preferably at least essentially zero resistance, capacitance and inductance. In particular, resistance, capacitance and inductance of the electrically conductive connection are exclusively parasitic by nature. Further, resistance, capacitance and inductance of the electrically conductive connection significantly smaller (preferably by a factor of 1 / 100, 1 / 1000 or 1 / 10000) than resistances, capacitances and impedances of resistors, capacitors or inductors, respectively, connected by the electrical conductive connection, and / or comprised by an electric circuit or network which comprises the electrically conductive connection.

[0160] Unless specified otherwise, any one of an electric connection, electrical connection, conductive connection, conducting connection may be identical to a connection as defined above.

[0161] Unless specified otherwise, if two entities, including in particular nodes, points, terminals, elements, devices, etc. or combinations thereof, are said to be connected, electrically connected or to be (electrically) connected together, a connection as defined above may exist between the two entities.

[0162] All documents mentioned and / or referred to in this patent application, in particular all patent documents and any Wikipedia articles, are included by reference in their entirety. APPENDIX I

[0163] In a magnetic field camera made of integrated Hall elements on a semiconductor plate (e.g. silicon), Hall elements are arranged in the form of a matrix as shown in Fig. 1 on the surface of the semiconductor plate. Above the matrix of Hall elements, there is usually a protective layer that can be separated or in contact with the semiconductor plate. It is necessary for this protective layer to be transparent or partially transparent for the applied light, which in this case can be ambient diffuse light. If the semiconductor wafer is made of silicon then it is best to use near infrared light. It is usually desirable that the thickness of the protective layer be relatively small, preferably approximately equal to the distance between the pixels. Only in that case, the magnetic field can be mapped with the spatial resolution provided by the matrix of magnetic sensors.

[0164] The pixels of the magnetic camera can be horizontal or vertical Hall elements. Horizontal Hall elements sense a magnetic field whose lines of force are perpendicular to the surface of the semiconductor wafer.

[0165] The Hall element may be made in the N-well layer while the substrate is P-type. The junction of the substrate and the N-well layer represents a diode that is inversely polarized in application.

[0166] A magnetic field camera is described above may also be used as an optical camera in one of the following ways:

[0167] A) If some additional photo-sensitive element, for example a photo-diode or a photo-resistor, is installed in the pixels with Hall-elements; and the signal from that photo element is preferably processed by the same circuits that process the Hall signal.

[0168] B) If the Hall elements present in the camera are occasionally connected so that each given Hall element (HE) may play the role of the photo-sensitive element from A).

[0169] In a first variant of option B), the HE is employed as a photodiode is exemplary illustrated in Fig. 5:

[0170] - The area of the N-well H-element (HE) is the side of the N-type photodiode, and its side P is the P-type substrate (S) in which that HE lies.

[0171] - Fig. 7 shows an example of an electrical scheme for extracting and amplifying the signal from such a photodiode.

[0172] Labels:

[0173] Vdd - the positive supply voltage of the entire camera chip,

[0174] Vss - the negative supply voltage of the entire camera chip,

[0175] Vref - reference voltage, which maintains a suitable input voltage level of amplifiers A, Vss < Vref < Vdd, HE - N-well of H-element,

[0176] S - P-type substrate,

[0177] L - load, which can be a resistor or a source of constant current,

[0178] C - coupling capacitor (optional),

[0179] A - amplifier,

[0180] Vpd - the voltage at the output of the photo-diode, Vout - output voltage.

[0181] The principle of working:

[0182] - If the HE is not illuminated, only the inverse leakage current towards the substrate flows through it, which is negligibly small, so Vpd = approximately = Vdd. - If the HE is illuminated, then there is a considerable photo-current pn-junction HE / substrate, which also flows through the load, where the voltage drop appears, so now Vpd < Vdd.

[0183] If light is allowed to fall on the interior of the Hall element, ionization occurs in the body of the semiconductor in the N- well layer, the depleted region and in the P-type substrate. The carriers generated in the semiconductor, with few exceptions, soon recombine due to the high concentration of the main carriers. Exceptions refer to the carriers that arise near the p-n junction, at a distance smaller than the diffusion length, for which the probability of reaching the junction is high. Carriers generated within the depleted region are accepted by the electric field at the junction and form a current. In order for this current to be dominant, the junction must be inversely polarized.

[0184] The photodiode current has two components. The first, the dark current, is determined by the well-known characteristic of the diode. l=l_S (eA(W_T )-1 ) (1 )

[0185] The second, photocurrent, is determined by generation. Based on the theoretical consideration, it is obtained that the photocurrent is directly proportional to the light flux.

[0186] Therefore, the total photodiode current is given by: l= -l_F+l] _S (eA(V / V_T )-1 ) (2)

[0187] The characteristic of the photodiode is given in Figure 6, which shows: a) Characteristics of the photodiode for two values of illumination (principal current) and b) characteristics with inverse polarization of the silicon photodiode. Usually, we simulate the Hall element in the simplest way with a Wheatstone bridge. Figure 6 shows a Hall element in the form of a Wheatstone bridge with inversely polarized diodes towards the substrate (which is usual for the application of integrated Hall elements).

[0188] The polarization of the Hall element is performed as in the so-called "test mode" illustrated in see Fig. 3.

[0189] If an object, in particular a magnet, is placed above the magnetic field camera , and then a recording is made with light and without light, and the difference between the two images is made, an image is obtained which is a shadow, i.e. one of the orthogonal projections of the magnet. Since the 3D model of the magnet under test is usually known in the industry, the orientation and position of the magnet in relation to the magnetic camera can be easily recognized. Image recording implies that the output voltages from all sensors (pixels) are memorized in the form of a matrix. It is common for each value in the matrix to be graphically represented by a corresponding color / shade according to the given color legend. By image subtraction, we consider the generation of a new matrix and its graphic representation as the subtraction of two previously given matrices.

[0190] In a second variant of option B), the HE is employed as a photoresistor.

[0191] In addition to the photo-diode effect described in connection with the first variant of option B), there is also the photoconductivity effect, which is caused by "carriers generated in the semiconductor" before they can recombine. Figure 8 shows the scheme of the simplest electrical model of the Hall element in the form of a Wheatstone bridge when it is polarized to work as a magnetic field sensor. The diodes in the schematic represent an inversely polarized PN junction between the Hall element and the substrate.

[0192] Here is the result of a simple analysis. The output voltage from the sensor is given by the following equations:

[0193] Vs = C * Rh * lb * Gt (there is no illumination, the sensor is in shadow) (3)

[0194] Where is C - numerical coefficient, Rh - resistance of the Hall element, lb - polarization current, Gt - gain of the amplifiers in the given operating mode.

[0195] Vi = C * (Rh - ARi) * (lb - Ali) * Gt (with illumination) (4) Where is ARi - reduction of Rh due to illumination (photo-conductive effect), Ali - change in the effective polarization current (due to the leakage current of the inverno-polarized PN junction between the Hall element and the substrate) caused by illumination (photo-diode effect). Note that ARi and Ali are proportional to the lighting intensity.

[0196] The difference of the output voltages given by equations 3 and 4 is AVo = C * ( ARi * It - Ali * Rh ) * Gt (5)

[0197] For small values of ARi and Ali, their product can be neglected.

[0198] The relative contrast of the shadow image can be expressed as a ratio

[0199] AVo / Vs = ARi / Rh + Ali / lt (6)

[0200] Based on the previous analysis, it can be concluded that the relative contrast of the magnet shadow image can be improved:

[0201] - increase in lighting intensity

[0202] - reduction of lb (we cannot change Rh).

[0203] In addition, by applying synchronous detection (when the light is alternately turned on and off), the optical detectability can be significantly increased. This requires a connection between the magnetic camera and the driver of the cor- responding electric lamp.

[0204] APPENDIX II

[0205] The invention pertains to the field of magnetic field sensors, in particular Hall sensors. It relates to a method and a device for testing a Hall sensor, in particular without applying a magnetic field for test purposes, and to a magnetometer.

[0206] TECHNICAL BACKGROUND: Hall sensors are components that are widely used in various applications today, like e.g position and velocity sensing, current sensing, contactless switching, or as part of a general purpose magnetometer for measuring, in particular, a magnetic flux density. The possibility of integrating Hall sensors in and / or with a semiconductor chip and / or an integrated circuit provided on said chip, as well as the wide dynamic measurement range (from pT to several tens of T) contributed to their mass use. Modern Hall sensors are provided in the form of an integrated circuit, consisting of Hall elements and electronics for signal processing, which together may constitute a magnetometer, as exemplary described in the respective in the respective Wikipedia article of 12 April 2023, available from https: / / en.wikipedia.orq / w / index.php?title=Maqnetometer&oldid=1149526729, which is hereby included by reference in its entirety. Therefore, there is a significant need for testing an integrity and / or the correctness of Hall sensors. It is common to apply a magnetic field to the sensor during testing. However, generating a large magnetic field when testing Hall sensors at the wafer level is not a simple task at all. The presence of prober testing pins prevents a close access of the magnet or electromagnet. The presence of magnets or electromagnets prevents the optical visibility of the chip under test. In addition, today there are so-called 3D Hall sensors that measure the magnetic field in three mutually perpendicular spatial axes. This requires the application of test magnetic fields at different angles.

[0207] Standards related to the automotive or aviation industries may also require Hall sensors, in particular magnetometers employing such Hall sensors, to have a self-test function to increase their reliability.

[0208] Several methods have been developed for testing Hall elements that require the application of a magnetic field. In general, we the following options are of relevance:

[0209] • the source of the magnetic field can be a permanent magnet (it can also be the Earth's magnetic field) or a current-carrying conductor (e.g. in the form of a solenoid or an electromagnet);

[0210] • the source of the magnetic field (e.g. in the form of an electromagnet) can be integrated on the chip or it can be external.

[0211] Application of permanent magnets requires their mechanical movement (rotational and / or translational). That is why an additional electromechanical assembly is required, which complicates the set-up for testing. The application of a mechanical system limits the speed of testing.

[0212] On the other hand, electromagnets are purely electrically controllable. However, usually electromagnets have a significantly larger volume compared to permanent magnets to generate the same magnetic flux density. The control of the electromagnet (conductor with current) is performed via a controlled power source.

[0213] In general, significantly higher magnetic flux densities are generated with the help of external magnetic field sources. However, for the sake of self-testing and self-calibration, devices with an integrated magnetic field source were developed. It is usually a planar coil on the surface of a semiconductor wafer. Potential disadvantages of this method of testing are: generation of relatively weak magnetic fields, field generation is usually pulsed in order to limit thermal dissipation on the chip, due to the generation of a current pulse on the chip, interference occurs due to the capacitive coupling between the coil for generating the magnetic field and the rest of the electronics.

[0214] Therefore, it would be desirable to find new methods for testing Hall sensors that does not require the application of a magnetic field but is nevertheless capable of detecting the sensor malfunction with a high probability, specificity, and / or reliability.

[0215] The above objective and other objectives are solved by a method for testing a Hall sensor, a Hall sensor test device, and a magnetometer as detailed in Swiss patent application CH000620 / 2023 filed 12 June 2023.

[0216] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS: A Hall sensor (sometimes also called Hall effect sensor) generally comprises a sensor body made of an electrically conducting material, which sensor body may also be referred to as a Hall element. The electrically conducting material may in particular be a doped semiconductor material, preferably with a high electron mobility as e.g. provided by GaAs, InAs, InP, InSB, etc. as described in Wikipedia-Article

[0217] “Hall effect sensor” in its version of 03 April 2023 (available at which is hereby included by reference in its entirety, Hall sensors and / or elements generally come in one of two different basic types, namely discrete or integrated Hall sensors and / or elements

[0218] The simplest (discrete) Hall element may be implemented in the form of a thin parallelepiped, as in Figure 9, with four contacts. Power may be supplied through two opposite contacts (current contacts), in particular by means of a current and / or voltage source. An output voltage may be taken from the other two opposite contacts (measuring contacts), which output voltage may be a sum of a Hall voltage and an offset voltage.

[0219] It may be applied as a single Hall element or a group of Hall elements connected in parallel, so that they work together as a single Hall element. In its simplest form, the Hall element may act as an analog converter, directly out- putting a voltage that is proportional to the magnetic flux density, also referred to as magnetic induction.

[0220] Typical Hall plates for the practical magnetic field sensing purposes are plane, simply-connected regions with peripheral contacts. The output voltage is the sum of the offset and the Hall voltage. Modern circuits of the smart Hall sensor extract the Hall voltage using a so called “spinning current” mode of operation of the Hall sensor, which allows to effectively cancel and / or compensate the offset voltage.

[0221] Sensitivity, offset and its temperature drift are important figures of merit in Hall sensor performance evaluation. There is a strong relationship between the geometry and performance of Hall effect sensors. Many authors have dealt with this topic, for example the paper “Geometry Influence on the Hall Effect Devices Performance” by Maria-Alexandra PAUN, Jean-Michel Sallese and Maher Kayal, published in UPB Scientific Bulletin Series A, vol. 72, no. 4, pp. 257- 271 , 2010, which is hereby included by reference in its entirety. The dependence of the resistance between the contacts of Hall elements and its geometry for a given technology is also described in the literature. For example, in the paper in Philips Research Reports, Vol. 13 (1958), “A Method of Measuring Specific Resistivity and Hall Effect of Discs of Arbitrary Shape” by Leo J. van der Pauw, which is hereby included by reference in its entirety. Accordingly, there is a correlation between magnetic sensitivity and the resistance between contacts. Therefore, it can be determined experimentally for a given technology (a given sensor), how much the resistance can vary in order for the magnetic sensitivity to remain within the given limits (in the formulas, the so-called geometrical correction is often used). Integrated Hall sensors comprise a sensor body which is formed in a (portion of a) semiconducting substrate which semiconducting substrate also comprises circuitry and / or more complex integrated circuits. Integrated Hall sensors and / or their respective Hall elements may in general be categorized into lateral Hall sensors or elements configured to detect a magnetic field component perpendicular to a surface of the semiconducting substrate, and vertical Hall sensors or elements configured to measure a magnetic field component in a direction parallel to a surface of the semiconducting substrate. Lateral Hall sensors or elements are sometimes also referred to as horizontal Hall sensors or elements, respectively. More specifically, such Hall sensors may be used to measure a respective component of a magnetic flux density, commonly denoted by vector quantity B. An integrated Hall sensor may also comprise combinations of one or more of the former.

[0222] To detect a magnetic field and / or measure a magnitude of a magnetic flux density, a current, sometimes also referred to as biasing current, is imposed to flow in the sensor body. When a sufficiently strong magnetic field is present, charge carriers providing said current are deflected due to Lorentz force, which will give rise to a voltage between to properly chosen points on the sensor body, said voltage, which would not be present in the absence of the magnetic field, is generally referred to as Hall voltage. In general, the voltage will at least approximately be linearly dependent on the magnitude of the magnetic flux density, in particular at least approximately proportional to the magnitude of the magnetic flux density but for an offset voltage (which may at least approximately be zero, in particular under ideal circumstances).

[0223] To be able to impose a current in the sensor body, at least a first and a second contact are generally required, each of which may in particular be a metal-semiconductor junction as exemplary described in Wikipedia article https: / / en.wikipedia.orq / w / index.php?title=Metal%E2%80%93semiconductor iunction&oldid=1154105455.

[0224] First and second contact may respectively constitute a or be comprised by a first and second terminal, wherein said terminal may comprise additional features which may facilitate establishment of an electrically conductive connection between said contact and external equipment like, e.g., a current source, a voltage source, and / or a measurement device, in particular a voltmeter. The additional features may, in particular, comprise a port, a bushing, a plug, a socket, or a clamp.

[0225] Particular Hall sensors may comprise Hall elements which have 3 contacts only, wherein at least two of such Hall elements are electrically connected in a cluster such that this cluster has four terminals for external connection and then it is used as it is the same configuration as

[0226] To be able to measure the (Hall) voltage caused by the magnetic field as described above, at least one third contact is required, which may constitute a or be comprised by a third terminal. The (Hall) voltage may then be measured between third and first or third and second contacts and / or terminals. In general, a Hall sensor will also comprise a fourth contact, which may constitute a or be comprised by a fourth terminal.

[0227] In a discrete Hall sensor or a lateral Hall sensor, first and second contacts are generally located at a first distance in a first direction from one another, with third and fourth contacts located at a second distance in a second direction from one another, wherein the second direction is at least approximately perpendicular to the first direction, the third and fourth contacts are located between the first and second contacts with respect to the first direction, and the first and second contacts are located between the third and fourth contacts with respect to the second direction. First and second contacts may then be regarded as non-adjacent to or non-neighboring one another; as may third and fourth contacts, in particular when first and second distances are at least approximately identical. All other pairs of contacts (i.e. first and third, first and fourth, second and third, second and fourth) may be regarded as adjacent to or neighboring one another.

[0228] A Hall sensor having a Hall element electrically contacted by four, i.e. first to fourth, contacts and / or terminals as described above may be represented by an equivalent electric circuit having two parallel legs, each of which having two resistors connected in series, resulting in a total of four resistors; wherein the first and second contact electrically connect the two legs in parallel, with the third contact provided between the two resistors in a first one of the two parallel legs and the fourth contact provided between the two resistors in a second one of the two parallel legs. Resistors may be named R13, 14, R23, and R24, wherein for / e {1 , 2} and j e {3, 4} resistor Rj is connected between the / -th and the j-th contact, and may be representative of a resistance of a path, in particular a shortest path, in the Hall element between said / -th and the j-th contacts. When first and second contacts are electrically connected to respective poles of a current and / or voltage source, and a voltage measurement device, in particular a voltmeter, between the third and fourth contacts, the equivalent circuit represents a so called Wheatstone bridge as described in the respective Wkipedia article in the version of 14 October 2022, available at https: / / en.wikipedia.0rg / w / index.php2ti tle=Wheat- stone 15964157 Having regard to the equivalent circuit, any two contacts of the Hall sensor between which a path and / or connection with only a single resistor exists may be regarded as neighboring or adjacent to one another. Any two contacts between which no such path or connection exists may be regarded as non-neighboring, non-adjacent, and / or opposite from one another. For an ideal Hall sensor and / or Hall element design, resistances of all the resistors may preferably be at least approximately identical, i.e. R13 = 14 = R23 = 24, ideally with R13 = 14 = R23 = R24.

[0229] The invention is at least in part based on the idea to test a Hall sensor by imposing a current between two neighboring or adjacent contacts, to measure a voltage between two different contacts, in particular between two other neighboring or adjacent contacts, and to decide whether the sensor is faulty based on a comparison between the measured voltage and an expected voltage, which may be specific for the particular (pairs of) contacts chosen.

[0230] This invention may, in particular, be put into practice in the form of one of the following numbered embodiments:

[0231] 1) A method for testing a Hall sensor, said Hall sensor comprising, in particular, a) a sensor body made of electrically conducting material; b) at least three, in particular four, terminals for electrically contacting said sensor body; c) said sensor being configured to i) when a current and / or voltage is applied between a first pair of terminals from a first set of pairs of terminals, ii) produce a voltage between a conjugated pair of terminals different from the first pair of terminals,

[0232] Hi) said voltage indicative of, in particular at least approximately linearly dependent on or at least approximately proportional to, a magnitude of a magnetic flux density penetrating the sensor body; the method comprising the steps of: d) applying a current and / or voltage between a second pair of terminals and measuring a voltage, wherein i) the second pair of terminals is not within the first set of pairs of terminals, in particular not identical to the first pair of terminals, and / or ii) the voltage is measured between a third pair of terminals not conjugated to the second pair of terminals, in particular, does not comprise any of the terminals from the second pair of terminals; e) comparing the measured voltage with an expected voltage. 2) The method of embodiment 1 , further comprising the step of a) applying a current and / or voltage between at least one further second pair of terminals and measuring a further voltage, wherein i) the further second pair of terminals is not within the first set of pairs of terminals, and in particular not identical to the first or second pair of terminals, and / or ii) the further voltage is measured between a further third pair of terminals not conjugated to the further second pair of terminals, in particular, does not comprise any of the terminals from the further second pair of terminals; b) comparing the measured further voltage with a further expected voltage.

[0233] 3) The method of embodiment 1 or 2, wherein the first set of pairs of terminals comprises all pairs of non-neighboring terminals.

[0234] 4) The method of one of embodiments 1 to 3, wherein for each pair from the first set of pairs of terminals, the conjugated pair of terminals is also part of said first set.

[0235] 5) A method for testing a Hall sensor, in particular according to one of the previous embodiments, said Hall sensor comprising, in particular, a) a sensor body made of electrically conducting material; b) four terminals for electrically contacting said sensor body, comprising i) a first and a second terminal, in particular located at a distance from one another, ii) a third and a fourth terminal, in particular located at a distance from one another; c) said sensor being configured to produce a voltage i) between the third and fourth terminals when a current and / or voltage is applied between the first and second terminals, and / or ii) between the first and second terminals when a current and / or voltage is applied between the third and fourth terminals,

[0236] (a) said voltage indicative of, in particular at least approximately linearly dependent on or at least approximately proportional to, a magnitude of a magnetic flux density penetrating the sensor body; the method comprising the steps of d) selecting a first selected terminal from the first and second terminals and a second selected terminal from the third and fourth terminals; e) applying a current and / or voltage between the first selected terminal and the second selected terminal; f) choosing two measurement terminals comprising at least one terminal not selected in step d), in particular two terminals not selected in step d); g) measuring a voltage between said two measurement terminals; h) comparing the measured voltage with an expected voltage.

[0237] 6) The method of embodiment 5, further comprising the steps of a) selecting a third selected terminal from the first and second terminals and a fourth selected terminal from the third and fourth terminals, wherein i) the third selected terminal is different from the first selected terminal and / or ii) the fourth selected terminal is different from the second selected terminal; b) applying a current and / or voltage between the third selected terminal and the fourth selected terminal; c) choosing another two measurement terminals comprising at least one terminal not selected in step a), in particular two terminals not selected in step a); d) measuring a further voltage between said another two measurement terminals; e) comparing the measured further voltage with a further expected voltage.

[0238] 7) The method of any one of the preceding embodiments, further comprising a) providing a notification, in particular raising an alarm if a difference between the measured voltage and the expected voltage and / or between the measured further voltage and the further expected voltage exceeds a predetermined threshold; and / or if the measured voltage or the further measured voltage is at least approximately zero.

[0239] 8) A Hall sensor test device configured to be connected to a Hall sensor, said Hall sensor comprising, in particular, a) a sensor body made of electrically conducting material; b) at least three, in particular four, terminals for electrically contacting said sensor body; c) said sensor being configured to i) when a current and / or voltage is applied between a first pair of terminals from a first set of pairs of terminals, ii) produce a voltage between a conjugated pair of terminals different from the first pair of terminals

[0240] Hi) said voltage indicative of, in particular at least approximately linearly dependent on, a magnitude of a magnetic flux density penetrating the sensor body said test device comprising d) a current and / or voltage source configured to be connected between a second pair of terminals of the Hall sensor for imposing a current to flow between said second pair of terminals; e) a voltage measurement device configured to be connected between a third pair of terminals of the Hall sensor for measuring a voltage between said third pair of terminals; wherein i) the second pair of terminals is not within the first set of pairs of terminals, in particular not identical to the first pair of terminals, and / or ii) the third pair of terminals not conjugated to the second pair of terminals, in particular, does not comprise any of the terminals from the second pair of terminals; f) voltage comparison means for comparing a measured voltage, in particular between the third pair of terminals of the Hall sensor, with an expected voltage; and, in particular g) configured to test the Hall sensor in accordance with the method of one of the preceding embodiments.

[0241] 9) The method of one of embodiments 1 to 5 or the Hall sensor test device of embodiment 8, wherein the first set of pairs of terminals comprises all pairs of non-neighboring terminals.

[0242] 10) The method one of embodiments 1 to 5 or the Hall sensor test device of one of embodiments 8 or 9, wherein for each pair from the first set of pairs of terminals, the conjugated pair of terminals is also part of said first set.

[0243] 11) A Hall sensor test device configured to be connected to a Hall sensor, said Hall sensor comprising, in particular a) a sensor body made of electrically conducting material; b) four terminals for electrically contacting said sensor body, comprising i) a first and a second terminal, in particular located at a distance from one another, ii) a third and a fourth terminal, in particular located at a distance from one another; c) said sensor being configured to produce a voltage i) between the third and fourth terminals when a current and / or voltage is applied between the first and second terminals, and / or ii) between the first and second terminals when a current and / or voltage is applied between the third and fourth terminals,

[0244] (a) said voltage indicative of, in particular at least approximately linearly dependent on, a magnitude of a magnetic flux density penetrating the sensor body; said test device further comprising: d) a current and / or voltage source configured to be connected between a first selected terminal selected from the first and second terminals and a second selected terminal selected from the third and fourth terminals for imposing a current to flow between said first and second selected terminals; e) a voltage measurement unit configured to be connected between a third selected terminal different from the first and second selected terminal, and a fourth selected terminal, different from the third selected terminal, and preferably different from the first and second selected terminals, for measuring a voltage between said selected third and fourth terminals; f) voltage comparison means for comparing the measured voltage with an expected voltage; g) said test device in particular configured to test the Hall sensor in accordance with the method of one of embodiments 1 to 7.

[0245] 12) The Hall sensor test device of one of embodiments 8 to 11 , further comprising a) terminal selection means for selecting, in particular repeatedly selecting, the first selected terminal and the second selected terminal; wherein, in particular b) a different first and / or second terminal is selected in each subsequent selection; in particular c) until all possible combinations of a first selected terminal selected from the first and second terminals and a second selected terminal selected from the third and fourth terminals have been selected once, in particular exactly once.

[0246] 13) The Hall sensor test device of embodiment 12, wherein the terminal selection means are further configured to select, in particular repeatedly select, the selected third and fourth terminal.

[0247] 14) The Hall sensor test device of any of embodiments 8 to 13, further comprising switching means for selectively connecting the current and / or voltage source between the first selected terminal and the second selected terminal; and the voltage measurement unit between the third and fourth selected terminal.

[0248] 15) A magnetometer comprising a) a Hall sensor, said Hall sensor comprising, in particular, i) a sensor body made of electrically conducting material; ii) four contacts formed on said sensor body, each in electric contact with said sensor body;

[0249] Hi) which Hall sensor may in particular be represented by an equivalent electric circuit having a first and a second leg electrically connected in parallel, each of said legs having two resistors electrically connected in series, wherein first and second contacts of the four contacts electrically connect the two legs in parallel, a third contact of the four contacts is provided between the two resistors in the first leg; and the fourth contact of the four contacts is provided between the two resistors in the second leg; said magnetometer comprising: b) a current and / or voltage source configured to be connected between a first selected contact and a second selected contact of the four contacts for imposing a current to flow between said selected contacts, wherein i) in a measurement mode, said first and second selected contacts are non-neighboring contacts; ii) in a test mode, said first and second selected contacts are neighboring contacts; c) a voltage measurement unit configured to be connected between a third selected contact and a fourth selected contact of the four contacts for measuring a voltage between said third and fourth selected contacts, wherein at least one, in particular each, of the third and fourth selected contacts is different from both the first and second selected contacts, and wherein, in particular i) in the measurement mode, said third and fourth selected contacts are non-neighboring contacts; ii) in the test mode, said third and fourth selected contacts are neighboring contacts; d) voltage comparison means configured to, in the test mode, compare the voltage measured between the third and fourth selected contacts with an expected voltage. ) The magnetometer of embodiment 15, further comprising a) contact selection means configured to select, in particular repeatedly select, the first and second selected contact; wherein, in particular i) in the measurement mode and / or the test mode, a different first and / or second selected contact is selected from the three, in particular four, contacts in each subsequent selection; in particular until ii) in the test mode, all neighboring contacts, in particular all combinations of first and second selected contacts wherein said selected contacts are neighboring contacts, have been selected once, in particular exactly once; and / or

[0250] Hi) in the measurement mode, all non-neighboring contacts, in particular all combinations of first and second selected contacts wherein said selected contacts are non-neighboring contacts, have been selected once, in particular exactly once. ) The magnetometer of embodiment 15 or 16, further comprising switching means, in particular a switching network, configured to connect the current and / or voltage source between the first and second selected terminals and the voltage measurement unit between the third and fourth selected terminals, in particular after each repeated selection. ) A magnetometer comprising a) a Hall sensor, said Hall sensor comprising, in particular, i) a sensor body made of electrically conducting material; ii) four terminals for electrically contacting said sensor body, comprising

[0251] (1) a first and a second terminal, in particular located at a distance from one another,

[0252] (2) a third and a fourth terminal, in particular located at a distance from one another;

[0253] (3) said Hall sensor being configured to produce a voltage

[0254] (a) between the third and fourth terminals when a current and / or voltage is applied between the first and second terminals, and / or

[0255] (b) between the first and second terminals when a current and / or voltage is applied between the third and fourth terminals, said voltage indicative of, in particular at least approximately linearly dependent on, a magnitude of a magnetic flux density penetrating the sensor body; b) a current and / or voltage source configured to be selectively connected between two terminals selected from the first to fourth terminal; c) a voltage measurement unit configured to be selectively connected between two further terminals selected from the first to fourth terminal, wherein at least one of, preferably both the two further terminals is / are different from the terminals selected in step b); d) terminal selection means configured to, in a test mode of the magnetometer, select, in particularly repeatedly select, i) a first selected terminal from the first and second terminals and a second selected terminal from the third and fourth terminals for imposing a current to flow between said first and second selected terminals, ii) a third selected terminal different from the first and second selected terminal, and

[0256] Hi) a fourth selected terminal, different from the third selected terminal, and preferably different from the first and second selected terminals; e) switching means configured to i) in a measurement mode of the magnetometer, either and / or alternati ngly , connect

[0257] (1 ) the current and / or voltage source between the first and second terminals and the voltage measurement unit between the third and fourth terminals, or

[0258] (2) the current and / or voltage source between the third and fourth terminals and the voltage measurement unit between the first and second terminals ii) in the test mode, connect the current and / or voltage source between the first and second selected terminals and the voltage measurement unit between the third and fourth selected terminals. ) The magnetometer of any of embodiments 15 to 18, further comprising voltage comparison means for comparing a voltage measured by the voltage measurement unit in the test mode of the magnetometer with an expected voltage, and preferably a warning means for providing a notification, in particular for generating an alarm, if a difference between the measured voltage and the expected voltage exceeds a predetermined threshold, and / or if the measured voltage is at least approximately zero. ) The magnetometer of one of embodiments 15 to 19, further comprising evaluation means for determining a magnitude of a magnetic flux density based on a voltage measured by the voltage measurement unit in the measurement mode of the magnetometer. ) The magnetometer of any of embodiments 18 to 20, wherein the switching means are configured to, in particular in the measurement mode, alternati ngly connect the current and / or voltage source between a) between the first and second terminals or b) between the third and fourth terminals i) in a spinning current technique, in particular according to a switching scheme of the spinning current technique. ) The magnetometer of embodiment 21 , configured to apply the switching scheme of the spinning current technique also in the test mode. ) The magnetometer of any of embodiments 15 to 22, configured to, in the test mode, test the Hall sensor in accordance with the method of one of embodiments 1 to 7, in particular under control of a control unit integrated with the magnetometer. ) A method for testing a Hall sensor, said Hall sensor comprising, in particular, a) a sensor body made of electrically conducting material; b) at least three, in particular four, terminals for electrically contacting said sensor body; c) said sensor being configured to produce a voltage i) between a first pair of terminals from a first set of pairs of terminals, ii) when a current and / or voltage is applied between a conjugated pair of terminals different from the first pair of terminals,

[0259] Hi) said voltage indicative of, in particular at least approximately linearly dependent on, a magnitude of a magnetic flux density penetrating the sensor body; the method comprising the steps of d) measuring a voltage between a second pair of terminals, wherein i) the second pair of terminals is not within the first set of pairs of terminals, in particular not identical to the first pair of terminals, and / or ii) a current and / or voltage is applied to a pair of terminals not conjugated to the second pair of terminals, in particular, does not comprise any of the terminals from the second pair of terminals; e) comparing the measured voltage with an expected voltage. ) The method of embodiment 24, further comprising the step of a) measuring a further voltage between at least one further second pair of terminals, wherein i) the further second pair of terminals is not within the first set of pairs of terminals, and in particular not identical to the first pair of terminals, and / or ii) a current and / or voltage is applied to a pair of terminals not conjugated to the further second pair of terminals, in particular, does not comprise any of the terminals from the further second pair of terminals. b) comparing the measured further voltage with a further expected voltage. ) The method of embodiment 24 or 25, wherein the first set of pairs of terminals comprises all pairs of non-neigh- boring terminals. ) The method of one of embodiments 24 to 26, wherein for each pair from the first set of pairs of terminals, the conjugated pair of terminals is also part of said set. ) A method for testing a Hall sensor, said Hall sensor comprising, in particular, a) a sensor body made of electrically conducting material; b) four contacts formed on said sensor body, each in electric contact with said sensor body; c) which Hall sensor may in particular be represented by an equivalent electric circuit having a first and a second leg electrically connected in parallel, each of said legs having two resistors electrically connected in series, wherein first and second contacts of the four contacts electrically connect the two legs in parallel, a third contact of the four contacts is provided between the two resistors in the first leg; and the fourth contact of the four contacts is provided between the two resistors in the second leg; d) selecting two neighboring contacts from the four contacts; e) applying a current and / or voltage between the selected neighboring contacts; f) measuring a voltage between two different contacts, in particular between the two contacts not selected in step d); g) comparing the measured voltage with an expected voltage. 29) The method of embodiment 28, wherein steps d) to g). are repeated with at least one different contact being selected in step d).

[0260] 30) The method of embodiment 28, wherein steps d) to g) are repeatedly repeated with at least one different contact being selected in step d) until all pairs of neighboring contacts have been selected exactly once.

[0261] 31 ) A Hall sensor test device configured to be connected to a Hall sensor, said Hall sensor comprising, in particular, a) a sensor body made of electrically conducting material; b) four contacts formed on said sensor body, each in electric contact with said sensor body; c) which Hall sensor may in particular be represented by an equivalent electric circuit having a first and a second leg electrically connected in parallel, each of said legs having two resistors electrically connected in series, wherein first and second contacts of the four contacts electrically connect the two legs in parallel, a third contact of the four contacts is provided between the two resistors in the first leg; and the fourth contact of the four contacts is provided between the two resistors in the second leg; said test device comprising: d) a current and / or voltage source configured to be connected between first two neighboring contacts selected from the four contacts for imposing a current to flow between said two neighboring contacts; e) a voltage measurement device configured to be connected between two measurement contacts selected from the four contacts for measuring a voltage between said measurement contacts, said two measurement contacts comprising at least one contact, in particular two contacts, not comprised by the first two neighboring contacts; said two measurement contacts in particular being second two neighboring contacts; f) voltage comparison means for comparing a measured voltage, in particular between the two measurement contacts, with an expected voltage; and, in particular g) configured to test the Hall sensor in accordance with the method of one of the preceding method embodiments.

[0262] 32) The Hall sensor test device of embodiment 31 , further comprising a) contact selection means for selecting, in particular repeatedly selecting, the first two neighboring contacts; wherein, in particular, b) at least one different contact is selected in each subsequent selection; in particular c) until all pairs of neighboring contacts, have been selected once, in particular exactly once.

[0263] 33) The method, device or magnetometer of one of embodiments 15 to 17 or 28 to 32; wherein any two of the four contacts are neighboring contacts, in particular form a pair of neighboring contacts, if they are connected by a single resistor in the equivalent circuit; and / or non-neighboring contacts if they are not connected by a single resistor in the equivalent circuit.

[0264] 34) The Hall sensor test device or magnetometer of any of the previous embodiments, further comprising discrimination means for determining whether the Hall sensor is defective based on the comparison of the measured voltage with the expected voltage, in particular when a difference between the measured voltage with the expected voltage exceeds a predetermined threshold. 35) The Hall sensor test device or magnetometer according to the previous embodiment, wherein the discrimination means are configured to raise an alarm when the Hall sensor is defective.

[0265] 36) The method of any of the above method embodiments, wherein radiation, in particular light from the UV-A, visible and / or near-infrared spectral range, is inhibited from falling onto and / or entering the Hall sensor while measuring the voltage and / or obtaining the measurement voltage, in particular by placing the Hall sensor in a dark space, covering the Hall sensor with an at least substantially opaque cover, and / or directing any bright radiation sources away from the Hall sensor, in particular from the surface of its semiconducting substrate, or vice versa.

[0266] 37) The method of any of the method embodiments from embodiments 1 to 30, wherein a comparison, in particular a difference, between the measured voltage with an expected voltage is used to determine an intensity and / or amplitude of a radiation, in particular light from the UV-A, visible and / or near-infrared spectral range, falling onto and / or entering the Hall sensor while measuring the voltage and / or obtaining the measurement voltage,

[0267] In embodiments 1), 8), and related embodiments, in particular, the first set of pairs of terminals may comprise all pairs of terminals of a Hall sensor between which a current is or may be imposed in order to measure a magnetic flux density.

[0268] In a common discrete Hall sensor 1 comprising a sensor body 10 as shown in Fig. 9 with first, second, third and fourth terminals 11 , 12, 13, 14, and / or corresponding first, second, third and fourth contacts 11’, 12’, 13’, 14’, the first set of pairs of terminals may be considered to consist of two (unordered) pairs of terminals, namely a pair consisting of the first and second terminals, which may be denoted using the respective reference signs 11 and 12 by {11 ; 12}; and a pair consisting of the third and fourth terminals, which may analogously denominated by {13; 14}. Given that the pairs are unordered pairs, denominations {12; 11} and {14; 13} would equal {11 ; 12} and {13; 14}, respectively. It should be kept in mind though, that for each unordered pair of terminals, current may flow in two different directions. For first and second terminals 11 , 12, e.g., (positive) current may either flow from the first to the second terminal, or vice versa. First, second, third and fourth terminals 11 , 12, 13, 14, may be considered to comprise and / or correspond with / to contacts 11’, 12’, 13’, 14’, respectively.

[0269] Alternatively, the first set of pairs of terminals may be considered to consist of four ordered pairs of terminals, namely a pair consisting of the first and second terminals, which may be denoted using the respective reference signs 11 and 12 by (11 ; 12); a pair consisting of the second and first terminals, which may be denoted by (12; 11 ); a pair consisting of the third and fourth terminals, which may denominated by (13; 14), and a pair consisting of the fourth and third terminals, which may denominated by (14; 13). In the case of ordered pairs, (11 , 12) and (12, 11 ) are considered different from one another, as are pairs (13; 14) and (14; 13). The order of terminals forming an ordered pair may be indicative of a direction of (positive) current flow; or of an increase in potential, in particular when a current source is connected between two terminals of a pair.

[0270] As may clearly be seen from Fig. 9, the first set of pairs of terminals may be defined or considered to comprise all pairs of non-neighboring, non-adjacent, and / or opposite terminals; and / or all pairs of terminals for which the corresponding contacts are non-neighboring, non-adjacent and / or opposite, in particular separated from one another by at least one interposed contact and / or terminal on any path along any edge 101 of the sensor body 10. In a common integrated lateral Hall sensor 2 comprising a sensor body 20 as shown in Fig. 10 with first, second, third and fourth terminals 21, 22, 23, 24, and / or corresponding first, second, third and fourth contacts 21’, 22’, 23’, 24’, the first set of pairs of terminals may be considered to consist of two (unordered) pairs of terminals, namely a pair consisting of the first and second terminals, which may be denoted using the respective reference signs 21 and 22 by {21 ; 22}; and a pair consisting of the third and fourth terminals, which may analogously denominated by {23; 24}. Given that the pairs are unordered pairs, denominations {22; 21} and {24; 23} would equal {21 ; 22} and {23; 24}, respectively. It should be kept in mind though, that for each unordered pair of terminals, current may flow in two different directions. For first and second terminals 21 , 22, e.g., (positive) current may either flow from the first to the second terminal, or vice versa. First, second, third and fourth terminals 21 , 22, 23, 24, may be considered to comprise and / or correspond with / to contacts 2T, 22’, 23’, 24’, respectively.

[0271] Alternatively, the first set of pairs of terminals may be considered to consist of four ordered pairs of terminals, namely a pair consisting of the first and second terminals, which may be denoted using the respective reference signs 21 and 22 by (21 ; 22); a pair consisting of the second and first terminals, which may be denoted by (22; 21); a pair consisting of the third and fourth terminals, which may denominated by (23; 24), and a pair consisting of the fourth and third terminals, which may denominated by (24; 23). In the case of ordered pairs, (21 , 22) and (22, 21) are considered different from one another, as are pairs (23; 24) and (24; 23). The order of terminals forming an ordered pair may be indicative of a direction of (positive) current flow; or of an increase in potential, in particular when a current source is connected between two terminals of a pair.

[0272] Again, the first set of pairs of terminals may be defined or considered to comprise all pairs of non-neighboring, non- adjacent and / or opposite terminals; and / or all pairs of terminals for which the corresponding contacts are non-neigh- boring, non-adjacent and / or opposite as exemplary described further above, in particular based on equivalent circuits.

[0273] For / e {1 , 2} and j e {3, 4} resistors Rj comprised by the equivalent circuit Wheatstone bridge are also indicated in Fig. 10.

[0274] In a common integrated vertical Hall sensor 3 comprising a sensor body 30 as shown in Fig. 11 with first, second, third and fourth terminals 31, 32, 33, 34, and / or corresponding first, second, third and fourth contacts 3T, 32’, 33’, 34’, the first set of pairs of terminals may be considered to consist of two (unordered) pairs of terminals, namely a pair consisting of the first and second terminals, which may be denoted using the respective reference signs 31 and 32 by {31 ; 32}; and a pair consisting of the third and fourth terminals, which may analogously denominated by {33; 34}. Given that the pairs are unordered pairs, denominations {32; 31} and {34; 33} would equal {31 ; 32} and {33; 34}, respectively. It should be kept in mind though, that for each unordered pair of terminals, current may flow in two different directions. For first and second terminals 31 , 32, e.g., (positive) current may either flow from the first to the second terminal, or vice versa. First, second, third and fourth terminals 31 , 32, 33, 34, may be considered to comprise and / or correspond with / to contacts 3T, 32’, 33’, 34’, respectively.

[0275] Alternatively, the first set of pairs of terminals may be considered to consist of four ordered pairs of terminals, namely a pair consisting of the first and second terminals, which may be denoted using the respective reference signs 31 and 32 by (31 ; 32); a pair consisting of the second and first terminals, which may be denoted by (32; 31); a pair consisting of the third and fourth terminals, which may denominated by (33; 34), and a pair consisting of the fourth and third terminals, which may denominated by (34; 33). In the case of ordered pairs, (31 , 32) and (32, 31) are considered different from one another, as are pairs (33; 34) and (34; 33). The order of terminals forming an ordered pair may be indicative of a direction of (positive) current flow; or of an increase in potential, in particular when a current source is connected between two terminals of a pair.

[0276] Again, the first set of pairs of terminals may be defined or considered to comprise all pairs of terminals for which the corresponding contacts are non-neighboring, non-adjacent and / or opposite as exemplary described further above, in particular based on equivalent circuits.

[0277] For / e {1 , 2} and j e {3, 4}, resistors R,y comprised by the equivalent circuit Wheatstone bridge are again indicated in Fig. 11.

[0278] To measure a magnetic flux density with any of the Hall sensors 1 , 2 or 3 to which the test method of the above-mentioned embodiments shall be applied, a current may be imposed to flow between a first pair of terminals which may be (arbitrarily) selected from the first set of pairs of terminals. This is usually achieved by connecting a current source between the two terminals from the first pair, said current source capable of providing a known, predetermined or preset, current to flow between said pair of terminals. Alternatively, a voltage source may be connected between said two terminals, preferably with a current measurement device, in particular an Amperemeter, connected in series with the voltage source for providing an indication of an amount of current flowing between said two terminals. A voltage may then be measured between a conjugated pair for the (selected) first pair of terminals, which voltage is indicative of, in particular (for a given current) at least approximately proportional to, a magnitude of a magnetic flux density penetrating the sensor body. The conjugated pair of terminals normally consist of the remaining two terminals of the Hall sensor which are not part of the selected pair.

[0279] To actually test the sensor as described above, a current may be imposed between a properly chosen, second pair of terminals, and a voltage measured between a further properly chosen, third pair of terminals not identical with the second pair. A proper selection may be achieved by either selecting a second pair of terminals which is not in the first set of pairs of terminals; or by choosing the second pair of terminals from the first set, but then choosing a third pair of terminals which is not the conjugated pair of terminals for the second pair of terminals.

[0280] The second and third pair of terminals may, in particular, each consist of two neighboring terminals, in particular with no terminal in common. The measured voltage may then be compared with an expected voltage, which may depend on the exact selection of terminals. If a difference between the measured voltage with the expected voltage exceeds a (predetermined) threshold the Hall sensor may be considered faulty, and an alarm may be raised.

[0281] In embodiments 5), 11), 18), and related embodiments, in particular, the first and second terminal may be neighboring terminals and / or comprise respective first and second contacts which are non-neighboring or non-adjacent as described further above. Likewise, the third and fourth terminal may be non-neighboring terminals and / or comprise respectively the third and fourth contacts which are non-neighboring or non-adjacent as described further above. By selecting a first selected terminal from the first and second terminals and a second selected terminal from the third and fourth terminals, first selected terminal and second selected terminal may be neighboring terminals as described above. To actually test the Hall sensor, a current may then be imposed to flow between the selected first and second terminals. This is usually achieved by connecting a current source between the said selected terminals, said current source capable of providing a known, predetermined or preset, current to flow between said selected terminals. Alternatively, a voltage source may be connected between said selected terminals, preferably with a current measurement device, in particular an Amperemeter, connected in series with the voltage source for providing an indication of an amount of current flowing between said selected terminals. Two measurement terminals are then chosen, which comprise at least one terminal other than the selected first and second terminals. In general, for a Hall sensor having four terminals, the two terminals remaining after the selection of the selected first and second terminals are chosen as measurement terminals. A voltage may then be measured between the measurement terminals and compared with an expected voltage, which expected may depend on the exact selection of terminals. If a difference between the measured voltage with the expected voltage exceeds a (predetermined) threshold, in particular if the measured voltage is at least substantially zero, the Hall sensor may be considered faulty, and an alarm may be raised.

[0282] In embodiments 15), 18) and / or related embodiments, in particular, the magnetometer comprises a Hall sensor with a Hall element, which, when properly biased in the measurement mode of the magnetometer, may provide a voltage indicative of, in particular at least approximately linearly dependent on, a magnitude of a magnetic flux density penetrating a sensor body of the Hall element in a way known as such to a person skilled in the art and / or as described above. The magnetometer may comprise evaluation means for determining the magnitude of the magnetic flux density based on said voltage as measured by the voltage measurement unit in the measurement mode of the magnetometer. In the test mode, any one of the methods in accordance with the invention as described further above may be applied to provide a self-test function and / or capability of the magnetometer. The evaluation means, the current and / or voltage source, the voltage measurement unit, the voltage comparison means, contact selection means, and / or the switching means may be integrated with the magnetometer, in particular on a single semiconductor substrate together with the Hall sensor and / or the Hall element.

[0283] Fig. 12 illustrates a normal operation of a Hall sensor and / or element when used to measure a magnetic flux density according to the so called spinning current technique on the basis of an equivalent circuit comprising a Wheatstone bridge: in each of the four phases TMI to ®M4 the Hall element - represented by resistors / resistances R14, R13, R23, R24 electrically connected together on the edges of a square - is biased by a constant current IM via two non-neighboring contacts and / or terminals, and the output voltage is measured between the other two non-neighboring contacts and / or terminals. This is subsequently repeated for each (ordered) pair of non-neighboring contacts and / or terminals. Nodes I, II, III, and IV correspond to the first, second, third and fourth contact, respectively, and / or to the first, second, third and fourth terminal, respectively, as described further above, and / or are electrically connected to said first, second, third and fourth contacts, respectively, and / or to the first, second, third and fourth terminals, respectively. Said normal operation may also be referred to as operation in a measurement mode, or simply a measurement mode.

[0284] Fig. 13 illustrates a Hall sensor and / or element subjected to an exemplary embodiment of the method in accordance with the invention, on the basis of the same equivalent circuit comprising the Wheatstone bridge as shown in Fig. 12: in each of the four phases TTI to ®T4 the Hall element is biased by a constant current via two neighboring contacts, and the output voltage is measured between two other neighboring contacts.

[0285] In step 1 of Fig. 13 corresponding to phase <3>TI , a current / T may be imposed between nodes III and II of the equivalent circuit, corresponding to third and second terminals of resistor R23. A voltage (A is measured between nodes I and IV, corresponding to first and second terminals of resistor R14. When the values of all resistors are known, an expected value for said voltage may be determined according to

[0286] (A = / T R14 R23 / (R14 + R13 + R23 + R24) (1 ).

[0287] In optional step 2 corresponding to phase ®T2, current / T may be imposed between nodes II and VI of the equivalent circuit, corresponding to first and second terminals of resistor R24. A voltage U2 is measured between nodes I and IV, corresponding to first and second terminals of resistor R13. When the values of all resistors are known, an expected value for said voltage may be determined according to

[0288] U2 = / T R24 R131 ( R14 + R13 + R23 + R24) (2).

[0289] In optional step 3 corresponding to phase TTS, current / T may be imposed between nodes IV and I of the equivalent circuit, corresponding to first and second terminals of resistor R14. A voltage U3 is measured between nodes II and III, corresponding to first and second terminals of resistor R23. When the values of all resistors are known, an expected value for said voltage may be determined according to

[0290] U3 = / T R14 R231 ( R14 + R13 + R23 + R24) (3).

[0291] In optional step 4 corresponding to phase ®T4, current h may be imposed between nodes I and III of the equivalent circuit, corresponding to first and second terminals of resistor R13. A voltage UA is measured between nodes II and IV, corresponding to first and second terminals of resistor R24. When the values of all resistors are known, an expected value for said voltage may be determined according to

[0292] UA = / T R13 R241 ( R14 + R13 + R23 + R24) (4).

[0293] If the voltage measured in one or more of the steps detailed above deviates significantly from the respective expected value, in particular when a difference between the measured voltage and the expected voltage exceeds a predetermined threshold, and / or the measured voltage is at least approximately equal to zero, this may be seen as an indication that the Hall sensor and / or the Hall element is defective.

[0294] Hall elements and / or Hall sensors are often designed in such a way that all resistors in the equivalent circuit have identical resistances, i.e. R14 = R13 = R23 = R24. If this is the case, voltages C / 1, U2, U3 and UA, should be equal, i.e. stay within limits corresponding to the tolerances allowed by the applied sensor manufacturing technology for the desired resistances. Also, voltages U , U2, U3 and UA should all have non-zero values. If, by way of example, one or more of the voltages are equal to zero, this may indicate that the Hall sensor and / or element is faulty, in particular that there is a break or a short circuit.

[0295] In embodiments of the methods, devices and magnetometers as described above, the test current / T may be generated by the same current and / or voltage source which is used for the generation of the normal Hall biasing current IM as may be used in / for the measurement mode of operation.

[0296] Alternatively and / or in addition, voltages U , U2, U3 and UA may be processed by an identical signal processing chain both during normal operation, i.e. in the measurement mode of the (integrated) magnetic sensor and / or magnetometer, and in the test mode, including an electric circuitry for generating the spinning current, amplifiers, filters, ADC (if any), and so on.

[0297] A current and / or voltage used to power and / or bias the Hall sensors and / or elements in the measurement mode of operation may be higher than the current required for operation in the test mode, i.e., in particular, / T « I . When working in the measurement mode, the voltage is measured on the Wheatstone bridge, which normally is at least substantially nearly balanced, giving rise to a relatively low voltage. When it works in test mode, the voltage drop over the resistance between two neighboring contacts and / or terminals is measured, which is comparatively large. Applying a relatively high current in test mode (due to relatively high resistances) may push a voltage amplifier into saturation. That is why current reduction in test mode is advantageous, which is a better solution than reducing the gain of the amplifiers, in particular because the test mode allows for checking the entire measuring channel from the Hall element, through the amplifiers to the output filter.

[0298] In any of the methods for testing the integrity and / correctness of a Hall Sensor as described or referred to above or further below, in particular in the numbered embodiments laid out above in this appendix, radiation, in particular light from the UV-A, visible and / or near-infrared spectral ranges, may be inhibited from falling onto and / or entering the Hall sensor while measuring the voltage and / or obtaining the measurement voltage, in particular by placing the Hall sensor in a dark space, covering the Hall sensor with an at least substantially opaque cover, and / or directing any bright radiation sources away from the Hall sensor, in particular from the surface of its semiconducting substrate, or vice versa. In the same manner, radiation, may be inhibited from falling onto and / or entering a Hall sensor subjected to a test with a Hall sensor test device, or when using the test mode of a magnetometer as described above.

[0299] The methods and devices (including the magnetometers) as described in this appendix may also be used to determine intensity and / or amplitude of a radiation, in particular of an illumination, incident and / or impinging on(to) the Hall sensor and / or element described. This may in particular be achieved by determining the expected voltage at a first intensity and / or amplitude, which first intensity and / or amplitude may at least be approximately zero. A result of the comparison between the measured voltage with the expected voltage as referred to in the above embodiments and related explanations, in particular a difference between the measured voltage with the expected voltage, may then be regarded as indicative of the intensity and / or amplitude of the radiation, wherein the measured voltage may, in particular, be determined at a second intensity and / or amplitude, which may in particular be higher and / or larger than the first one. The difference between the measured voltage with the expected voltage, may, in particular be regarded as proportional or linearly dependent upon the (second) intensity and / or amplitude of the radiation. The test that the Hall sensor and / or element is subjected to may then be considered as a test for (the second) intensity and / or amplitude incident and / or impinging on(to) the Hall sensor and / or element, rather than for integrity of the Hall sensor and / or element. Where the device is configured with and / or may be operated in both measurement and test modes, the measurement mode may accordingly be used to measure a magnetic field, and the test mode to determine the (second) intensity and / or amplitude incident and / or impinging on(to) the Hall sensor and / or element.

[0300] As mentioned further above, in a well manufactured, horizontal Hall element, the following condition is given:

[0301] Rt~ R2~ R, ~ R, (5)

[0302] In the test mode of operation (as indicated by index T) and exemplary shown in Fig. 13 for a first phase (wherein for horizontal Hall elements; the similar considerations apply mutatis mutandis for the other three phases

[0303] - Based on equation (1), the output voltage between nodes I and IV is:

[0304] Ut= / TRi4 / 4 (6) where / Tis the excitation and / or biasing current in test mode.

[0305] In the regular measurement mode (index: M) as shown the Figure 4 with (wherein for horizontal Hall elements; the similar considerations apply mutatis mutandis for the other three phases): - The input resistance ( / ?«_») (for example) between nodes I and III is:

[0306] Rr v— R , (7)

[0307] - The output (Hall) voltage is: wherein:

[0308] S . current-related magnetic sensitivity HE, biasing current in measurement mode,

[0309] B: vertical component of magnetic induction.

[0310] For all Hall elements (both for horizontal Hall elements and for vertical Hall elements), the following relationship of Hall element parameters applies:

[0311] , wherein:

[0312] Sv. voltage-related magnetic sensitivity of Hall element

[0313] It follows from equations (7) - (9):

[0314] If the output voltage in test mode shall be equal to that in measurement mode: then, based on equations (6) and (11), it should be:

[0315] Equation (12) shows how the biasing current should be chosen in the test mode, so that the voltage at the output of the Hall element is equal to the Hall voltage at some applied magnetic induction B.

[0316] For example, since the typical value of voltage-relied magnetic sensitivity in silicon Hall elements in CMOS technology is Sv- 0.04 0.16 ■ (for B= IT)

[0317] As the measurement range of B in integrated Hall magnetic sensors is usually less than IT, it will most often be:

[0318] For example, for a measurement range of lOmT IT- 0.0016 ■ / „ (for B= lOmT) (14)

[0319] A convenient way to ensure the correct ratio of ITand IM, for example as in equation (14), is that the Hall IC sensor, in which this test method is implemented, contains a suitable current mirror.

[0320] As there are Hall sensors with several measurement ranges, in which the biasing current of the Hall elements and the gain of the amplifiers in the signal processing circuit are changed, a test mode should be implemented for each measurement range. If the biasing current of the Hall elements changes depending on the measurement range, then it is good to change the biasing current of the Hall element in the test mode. It is desirable that the supply current in the test mode should give an output voltage corresponding to the average value of the magnetic field for the given measurement range.

[0321] The resistances in the sensor have a large temperature coefficient (for the technology used for the design of Hall elements). The magnetic sensitivity (when Hall elements are biased by current) has up to 10 times lower temperature coefficient. Therefore, if the testing is done through resistance, then the temperature of the chip should also be measured, because the reference values for resistors depend on the temperature T. Smart sensors usually have a built- in temperature sensor, so that it is possible to establish a relation between the resistor values and the temperature. Consequently, the sensor's test mode could also be used to measure the temperature (if the Hall elements are functional).

[0322] R^Tj = 7?1 0(l + crT)

[0323] Fig. 14a illustrates an exemplary Hall sensor test device in accordance with the invention as detailed above. In order to test a Hall sensor or Hall element, nodes I, II, III, and IV may be connected to first, second, third and fourth terminals 11, 12, 13, 14, respectively, and / or first, second, third and fourth contacts 11', 12', 13', 14', respectively,

[0324] Fig. 14b illustrates magnetometer in accordance with the invention as detailed above, with an integrated Hall sensor, comprising a Hall element having contacts denoted A, B, C, D which correspond respectively to first, third, second and fourth contacts as described above.

[0325] To allow for testing the Hall sensor and / or the Hall element, it is electrically connected with a first switching network 61 that distributes (biasing) current to the given contacts of the Hall element, a second switching network 62 that connects the measuring (sensing) contacts of the Hall element with an amplifier, a third switching network 63 which demodulates amplified signals from the Hall element and control logic (Spinning Current / Test Mode Timing Control) and (Self-)Diagnostic circuit .

[0326] Output voltage U from the Hall element may be measured with an external voltmeter or with an integrated A / D converter.

[0327] When the device works in "Measurement Mode", in particular under so-called "Spinning Current" operation, then a 4-phase sequence has the following steps: - M -

[0328] Step 1 - the bridge sensor is powered between opposite contacts B and D. The measuring contacts are A and C. The measuring voltage is proportional to the supply current (biasing) and the magnetic field,

[0329] Step 2 - the bridge sensor is powered between opposite contacts B and D. The measuring contacts are A and C. The measuring voltage is proportional to the supply current (biasing) and the magnetic field, i.e. Ui

[0330] Iblas ±,

[0331] Step 3 - the bridge sensor is powered between opposite contacts D and B. The measuring contacts are C and A. The measuring voltage is proportional to the supply current (biasing) and the magnetic field, i.e.

[0332] Step 4 - the bridge sensor is powered between the opposite contacts A and C. The measuring contacts are D and B. The measuring voltage is proportional to the supply current (biasing) and the magnetic field, i.e. U4 ~ IblasB b,

[0333] By adding the output voltages from all 4 phases, the total output voltage is obtained U = U- + U2+ U3+ U4, which is also proportional to the polarization current (biasing current) and the measured magnetic field. Adding these voltages can be done using an integrated analogue integrator (low pass filter) or digitally, using an A / D converter and a microcontroller, which may in particular be integrated in the test device or on the magnetometer .

[0334] The same structure of the sensor, but with the application of a different sequence for the switching networks operation enables the device to work in "Test Mode". Then a 4-phase sequence has the following steps:

[0335] Step 1 - the bridge sensor is powered between points A and B. The measuring contacts are between points C and D. The expected output voltage is (A = / TR-a R24 / (RM + R-a + R23 + R24);

[0336] Step 2 - The bridge sensor is powered between points D and A. The measuring contacts are between points B and C. The expected output voltage is

[0337] Step 3 - The bridge sensor is powered between points C and D. The measuring contacts are between points A and B. The expected output voltage is U3=

[0338] Step 4 - The bridge sensor is powered between points B and C. The measuring contacts are between points D and A. The expected output voltage is U4=

[0339] Resistors R4, R13, R23 and R24 are the resistances of the equivalent circuit Wheatstone bridge.

[0340] Voltage comparison (A to U4may be done internally in the test device or on the magnetometer using an integrated A / D converter and control logic or by using external devices.

[0341] This way of excitation and / or biasing with the current I and measurements of (A to U4is not the only possible one. So, in the example of Fig. 14:

[0342] - It is possible to pass the current through the Wheatstone bridge in different ways. Also , the voltage measuring contacts can be arranged differently. In particular, voltage drops may be measured between any two neighboring contacts, for example, between A and B, B and C, etc.; The solution described with the measurement of the voltage at the ends (contacts) opposite to the power supply (as illustrated in Figure 16 discussed further below) is preferred because a common mode voltage is maintained similar to the case of measuring the Hall voltage in the measurement mode (as illustrated in Figure 15 discussed further below). Achieving the same common mode voltage is advantageous in terms of the effect of this voltage on the amplifier. Also, resistors RM, R23 and R24 form a voltage divider so that the voltage measured in the test mode is as low as possible, i.e. a reduction of the Hall element supply current is smaller.

[0343] - Excitation with the current / Tcan be done as in the measurement operation mode - between opposite ends of the Hall element, and the voltage drops can be measured between any two adjacent contacts.

[0344] As illustrated in Figure 14, in the measurement operation mode the AC Hall voltage from the Hall element that is fed to the amplifier is converted to DC only by the demodulator. The voltage corresponding to the offset of the Hall element after the demodulator is AC, so it is cancelled out by filtering. Similarly, in the test mode, the voltage applied to the amplifier is AC. This voltage is converted to DC only by the demodulator.

[0345] Figure 15 illustrates switching means, in particular a switching network 71, which may be configured to selectively connect current and / or voltage source for providing bias current and voltage measurement unit to the various nodes I, II, III and IV of the equivalent circuit Wheatstone bridge as illustrated in Fig. 4 to carry out the measurement mode operation as illustrated in said Figure.

[0346] Figure 16 illustrates the switching means from Fig. 15, configured to selectively connect current and / or voltage source for providing bias current and voltage measurement unit to the various nodes I, II, III and IV of the equivalent circuit Wheatstone bridge as illustrated in Figs. 4 and 5 to carry out the test mode operation as respectively illustrated in said Figure 5.

[0347] The same configuration of analog switches used for "spinning current", i.e. the measurement mode may also be used for the test mode (without additional switches required). The only difference is the switching sequence (Timing Control). The test mode does not require any additional analog switches.

[0348] The measuring mode or "spinning current", apart from four-phase, can also be run in two-phases or eight-phases (generally multiphase). Accordingly, the test mode can be two-phase or multi-phase.

[0349] If a Hall element has more than 4 contacts, which may be the case, for example, in some variations of the vertical Hall-effect devices, the present testing method could be still applied, preferably by biasing the Hall element via a pair of neighboring contacts and measuring the voltage drop between another pair of neighboring contacts.

[0350] The described invention covers the case of wafer-level testing without the application of a magnetic field. If the sensor test results are within certain limits, the "GOOD / BAD" decision can be done automatically by a software program or by a person.

[0351] The described invention covers also the case when the smart sensor has a "self-test" function. That is why the "Self-diagnostic Circuit" block is built into the described system and decides whether the self-test results are good or not. This block (as "watch-dog") periodically checks that the sensor is functioning correctly. For example, this block can be an automated procedure that receives a clock and occasionally stops the measurement and conducts a test, compares the test results with the results stored in the memory and makes a decision, i.e. sends the appropriate signal to its output.

[0352] Further exemplary embodiments

[0353] The disclosure of this appendix will be explained with respect to further optional detail in the following text with reference to further exemplary embodiments which are illustrated in the attached drawings. la. A method for testing Hall magnetic sensors by biasing the Hall element via its first pair of contacts and measuring the voltage via its second pair of contacts, characterized by the fact that at least one of the said two pairs of contacts are mutually neighboring contacts of the Hall element.

[0354] 2a. Device for testing Hall sensors without the application of a magnetic field, indicated by the fact that it consists of a circuit for polarization of the Hall element, a switching network, a circuit for controlling switches and a circuit for diagnostics or self-diagnosis of a fault, whereby the polarization of the Hall element is performed sequentially between its two contacts in two or more phases, and the voltage measurement is performed between its two adjacent contacts, and the value of that voltage is compared with the reference value in the diagnostic circuit, and based on that, it generates a signal for reporting a fault.

[0355] 3a. Device according to embodiment 2a, wherein the polarization of the Hall element is performed between some of its two adjacent contacts, and the voltage measurement is performed between the other two adjacent contacts. (NOTE: this is the preferred solution)

[0356] 4a. Device according to embodiment 2a or 3a, wherein the diagnostic circuit is integrated on the same chip as part of the Hall sensor, providing an autonomous test / self-test function.

[0357] 5a. Device according to embodiment 2a or 3a, characterized by the fact that the diagnostic circuit is located outside the Hall sensor chip, providing the testing function, especially during "wafer-level testing".

Claims

Patent claims1 ) A method for determining a magnetic field around an object, in particular created by said object, comprising the steps of: a) placing the object onto or near a surface of a magnetic field sensor; b) illuminating the object and the magnetic field sensor with a light source, in particular a mapping light source; c) determining a first intensity distribution, in particular a first intensity distribution at or near a surface layer of a semiconductor substrate (10, 10’) comprised by the magnetic field sensor; d) determining a position and / or orientation of the object relative to the magnetic field sensor array based on the first intensity distribution; e) measuring a magnetic field distribution with the magnetic field sensor.2) The method of claim 1 , wherein the magnetic field sensor is a or comprises a magnetic field sensor array (1 ), in particular a magnetic field sensor array according to one of numbered embodiments 1 to 15, and / or with said magnetic field sensor array in particular comprising a plurality of magnetic field sensors (11 ), in particular Hall sensors.3) The method of claim 1 , wherein the magnetic field sensor comprises: a) a magnetic field sensitive optical element, in particular layer, configured to generate a photocurrent, luminescence and / or an electromagnetic radiation, wherein i) the photocurrent, luminescence and / or an electromagnetic radiation is dependent on and / or varies with the magnetic field; ii) the magnetic field sensitive optical element is provided in proximity to the semiconductor substrate, in particular the surface layer of the semiconductor substrate (10’);Hi) the semiconductor substrate (1 O’) is configured to measure the photocurrent, luminescence and / or electromagnetic radiation generated by the magnetic field sensitive optical element, in particular to determine a spatial distribution of said photocurrent and / or electromagnetic radiation.4) The method of claim 3, wherein the semiconductor substrate comprises a plurality of photodetectors, in particular photodiodes or an image sensor, in particular a CMOS or CCD image sensor comprising a plurality of pixels (31 ).5) The method of claim 3 or 4, wherein the magnetic field sensitive optical comprises a layer consisting of or comprising a crystalline structure having at least one defect, wherein the crystalline structure is diamond, silicon (Si) or SiC, and the defect a colour center, in particular a nitrogen defect and / or a nitrogen-vacancy center, and with said layer preferably being provided adjacent to, adjoining and / or in direct contact with th semiconductor substrate.6) The method of any preceding claim, wherein a) the first intensity distribution is obtained while the light source is operated at a first, relatively higher output level of the light source, in particular a maximum output level; b) a second intensity distribution is obtained while the light source is operated at a second, relatively lower output level of the light source, in particular a minimum or zero output level, and / or is obscured; whereinc) the position of the object relative to the magnetic field sensor array is based on the first intensity distribution in combination with the second intensity distribution; in particular on a difference between the first intensity distribution and the second intensity distribution.7) The method of any preceding claim, wherein a known geometry of the object is taken into account in determining the position and / or orientation of the object relative to the magnetic field sensor, in particular the magnetic field sensor array.8) The method of any preceding claim, wherein a) the object is placed on an object support, in particular an at least approximately horizontal object support surface; and b) the magnetic field sensor, in particular the magnetic field sensor array, is mounted above the object support, in particular at a known distance from the object support, and / or with a surface of the magnetic field sensor , in particular of an at least partially transparent protection layer comprised by the magnetic field sensor, at least approximately parallel to the object support surface, wherein, in particular, a light source is integrated with the object support, wherein the object support surface is preferably a light emitting surface.9) The method of any preceding claim, further comprising correlating the position and / or orientation of the object relative to the magnetic field sensor, in particular the magnetic field sensor array, with magnetic field distribution as measured with the magnetic field sensor, in particular the magnetic field sensor array.10) The method of any preceding claim, further comprising providing a dataset representative of the magnetic field distribution relative to object, in particular a) to one or more surfaces, edges, corners, and / or a center of gravity of the object, and / or b) to one or more markers, in particular fiducials, provided on the object.11) The method of any preceding claim, further comprising the step of generating a 2-dimensional graphical representation of the magnetic field in which an indication of the position and / or orientation of the object is provided, in particular as an overlay.12) The method of any preceding claim, wherein the magnetic field sensor is a magnetic field sensor array according to one of embodiments 9 to 15, and the first intensity distribution is determined by means of the plurality of light sensitive elements.13) The method of any preceding claim, wherein the first and / or second intensity distribution is determined by evaluating signals from at least a subset of the magnetic field sensors, or from the plurality of photodetectors or the image sensor comprised by the semiconductor substrate.14) The method of any preceding claim, wherein the first and / or second intensity distribution is used to determine which ones of the plurality of magnetic field sensors, the plurality of photodetectors or which pixels of the image sensor comprised by the semiconductor substrate are completely obstructed from illumination by the light source, in particular the mapping light source, by the object.15) The method of any preceding claim, wherein the first and / or second intensity distribution is used to determine which ones of the plurality of magnetic field sensors are unobstructed from illumination by the light source.16) The method of any preceding claim, wherein the first and / or second intensity distribution is used to determine for which ones of the plurality of magnetic field sensors, the plurality of photodetectors or which pixels of the image sensor comprised by the semiconductor substrate illumination by the light source, in particular the mapping light source, is not obstructed through or by the object.17) The method of any preceding claim, wherein the first and / or second intensity distribution is used to determine which ones of the plurality of magnetic field sensors, the plurality of photodetectors or which the pixels of the image sensor comprised by the semiconductor substrate are partially obstructed from illumination by the light source, wherein, in particular, it is determined for each partially obstructed sensor, photodetector or pixel what percentage of a surface area of said sensor, photodetector or pixel, respectively, is obstructed by the object.18) Use of a magnetic field sensor array or a magnetic field camera, in particular for measuring a magnetic field distribution, said magnetic field sensor array or magnetic field camera comprising: a) a semiconductor substrate (10, 10’); b) a plurality of magnetic field sensors, in particular Hall sensors (11), provided on and / or within a surface layer of the semiconductor substrate; c) to determine an intensity distribution of a radiation, in particular electromagnetic radiation, in particular light from the UV-A, visible and / or near-infrared spectral ranges, impinging onto the surface layer of the semiconductor substrate.19) Use of a magnetic field sensor array or a magnetic field camera according to the preceding claim, wherein the intensity distribution is determined by evaluating signals from at least a subset of the magnetic field sensors.20) Use of a magnetic field sensor array or a magnetic field camera according to any preceding use claim, wherein an intensity of the radiation varies or is varied over time, and the intensity distribution is determined by evaluating a variation of the signals from at least a subset of the magnetic field sensors over time.21) Use of a magnetic field sensor array or a magnetic field camera according to any preceding use claim, wherein a) the first set of signals from at least a subset of the magnetic field sensors is obtained while the radiation is at a first, relatively higher intensity level, in particular a maximum intensity level; b) a second set of signals from at least the subset of the magnetic field sensors is obtained while the radiation is at a second, relatively lower intensity level of the light source, in particular a minimum or zero output level, and / or is obscured; wherein c) the intensity distribution is determined by evaluating a change and / or difference between the signals in the first and second set.

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