WO2021178868A1 - Optimisations de dispositif de réseau de capteurs magnétiques et caméra magnétique hybride - Google Patents

Optimisations de dispositif de réseau de capteurs magnétiques et caméra magnétique hybride Download PDF

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Publication number
WO2021178868A1
WO2021178868A1 PCT/US2021/021177 US2021021177W WO2021178868A1 WO 2021178868 A1 WO2021178868 A1 WO 2021178868A1 US 2021021177 W US2021021177 W US 2021021177W WO 2021178868 A1 WO2021178868 A1 WO 2021178868A1
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Prior art keywords
sensor
row
magnetic
array
sensor array
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PCT/US2021/021177
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English (en)
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James Howard ELLIS, Jr.
Keith Bryan Hardin
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Lexmark Internation, Inc.
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Publication of WO2021178868A1 publication Critical patent/WO2021178868A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0094—Sensor arrays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/07—Hall effect devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
    • G01R33/0035—Calibration of single magnetic sensors, e.g. integrated calibration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/007—Environmental aspects, e.g. temperature variations, radiation, stray fields
    • G01R33/0082—Compensation, e.g. compensating for temperature changes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/0206—Three-component magnetometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/07—Hall effect devices
    • G01R33/077—Vertical Hall-effect devices

Definitions

  • This invention relates generally to a magnetic sensor array device comprised of an array of magnetic sensors arranged on a common semiconductor substrate in order to measure the multi-axis magnetic field of an arbitrary sized region with high spatial resolution, reduced sensing distance, higher measurement throughput, motion tolerance, temperature tolerance, and improved manufacturing yield.
  • a further invention disclosed is the utilization of a central area of a surface to measure the normal magnetic field using Hall effect plates that are on the surface of the area.
  • the authentication system disclosed in US 9,553,582 is based on a unique physical object, where the unique physical object is a PUF (Physical Unclonable Function) that contains magnetic particles that are random in size, shape and orientation, which when magnetized generate a complex and random (in amplitude and direction) magnetic field near the surface of the PUF object.
  • PUF Physical Unclonable Function
  • This magnetic field may be measured, either at discrete points, along a path, or in additional manners, and the data corresponding to the magnetic field components recorded for later comparison and authentication of the PUF object.
  • a magnetic field measurement system can be constructed using a single discrete magnetic field sensor device (1 sensor/device), such as a Hall effect sensor, where the sensor and the PUF part are moved relative to one another along a path (e.g., linear, parabolic, circular, etc.) in order to record the magnetic field over the surface of the PUF object.
  • sensor/device such as a Hall effect sensor
  • a magnetic field measurement system can be constructed using more than one discrete magnetic sensor device arranged in a one or more-dimensional array where the magnetic sensor array and the PUF object are moved relative to one another along a path (e.g., linear, parabolic, circular, etc.) in order to record the magnetic field over the surface of the PUF object.
  • a path e.g., linear, parabolic, circular, etc.
  • U.S. Pat. App. Nos. 17/012,456; 17/012,474; and 17/012,483 described a multi-axis magnetic sensor array device fabricated on a common semiconductor substrate using a one or more-dimensional array of multi-axis magnetic sensors (such as Hall effect sensors) by either sawing out of a semiconductor wafer more than one discrete multi-axis magnetic sensor die (where each die consists of one standalone multi-axis magnetic sensor) or by fully integrating into a single die more than one multi-axis magnetic sensor.
  • An improvement of such a magnetic sensor array device is that it can measure the multi-axis magnetic field over the entire surface area of a PUF object with very high spatial and magnetic resolution without the need for any motion control system.
  • the reduction in measurement time provides a manufacturing cost benefit when faced with the problem of enrolling a very large volume of PUF parts in the shortest amount of time.
  • the improvement in measurement accuracy provides a security benefit as it reduces the probability that a legitimate PUF object fails to be authenticated as genuine (i.e., false negative) or that an illegitimate PUF object (cloned copy or reuse of an original) is authenticated as genuine (i.e., a false positive).
  • Another sensor disclosed herein has an array of cells that measure a surface magnetic field.
  • Each cell contains Hall effect sensor plates in the 3 cartesian coordinate planes to measure magnetic field components Bx, By, and Bz. By locating the Bx and By adjacent to each Bz the resolution of the Bz component is reduced.
  • the problem to be solved is how to pack the Bz Hall effect sensor plates as close as possible without the presence of the Bx and By Hall effect sensor plates. It is known that the Bx and By components can be calculated from this surface data.
  • there are at least two problems that arises from this technique First, there are errors introduced by the truncations of the field values, and second, a magnetic field from a source that does not penetrate through the measurement plane will not be measured.
  • the magnetic field component Bz will be zero. However, there will be Bx and By components within measurement surface that only tangentially directed. Having the perimeter of the measurement surface with tangential measurement devices allows a direct measurement of the in-plane components.
  • FIG. 1 shows a fully integrated multi-axis magnetic array sensor device.
  • FIG. 2 shows a sensor response stage and sensor readout stage
  • FIG. 3 shows a magnetic sensor array divided into two parts with each array part measured in parallel using the serial measurement method.
  • FIG. 4 shows a sensor response stage and sensor readout stage with one or more analog sample and hold registers between the sensor response stage and the amplifier stage.
  • FIG. 5 shows a magnetic sensor array divided into two-parts with each array part measured in parallel using the serial pipelined measurement method.
  • FIG. 6A shows a magnetic sensor array with a staggered row and inline column.
  • FIG. 6B shows a magnetic sensor array with an inline row and a staggered column.
  • FIG. 7 shows a magnified view of an inline row and inline column arrangement of magnetic sensors.
  • FIG. 8 shows a magnified view of an inline row and staggered column arrangement of magnetic sensors.
  • FIG. 9 shows a measurement system
  • FIG. 10 shows a sensor integrated circuit authentication method by a reader.
  • FIG. 11 shows a method of securing from tampering data transferred across an interface through the use of a standard message authentication code or digital signature.
  • FIG. 12 shows the measurement surface with Bz measurement Hall plates.
  • FIG. 13 shows Hall plates with a magnetic concentrator ring.
  • FIG. 14 shows Hall plates with magnetic concentrator rings around the edge elements.
  • This monolithic integrated circuit is fabricated on a common semiconductor substrate 1005 and consists of a two-dimensional array of multi-axis magnetic sensors 1007 arranged horizontally as an arbitrary number of rows (e.g., 1-Rl - 1-R8) and vertically as an arbitrary number of columns (e.g., 1-Cl - 1-C8) along with all the analog and digital circuitry necessary for a fully integrated device with a single digital interface (such as a I 2 C, but not limited to such) to a host computer system.
  • the two dashed lines 1051 and 1055 divides the sensors into groups shown here as four quadrants.
  • the groups are arbitrary for creating repeated patterns to easily replicate sections of the design. For example, cells created in the box bounded by rows 1-Rl through 1-R4 and columns 1-Cl through 1-C4 are replicated as a copy to the other three quadrants. This replication will translate all of the physical characteristics of the first quadrant to the other three.
  • the circuitry includes a sensor array row and column readout control 1011, a host computer control interface 1013, a calibration memory 1015, a sensor array bias timing control 1021, analog current bias generator 1023, an analog voltage regulator 1025, a memory buffer 1031, a sensor analog voltage sample and hold circuit 1041, an amplification with noise cancellation circuit 1043, an analog voltage digitization circuit 1045, a thermal compensation circuit 1047, and a row digital capture register 1049.
  • U.S. Pat. App. Nos. 17/012,456; 17/012,474; and 17/012,483 disclose methods to decrease the measurement time of the monolithic magnetic sensor array by measuring one or more axes of each sensor in each column of one or more rows and then incrementing through the one or more rows one at a time until the entire magnetic sensor array had been measured.
  • These measurement methods can be called the serial (e.g., one row at a time) measurement method and the parallel (e.g., more than one row at a time) measurement method where each measurement method consists of a sensor response stage and a sensor readout stage as shown in FIG. 2. Shown in FIG.
  • the magnetic sensor array device 2001 has a sensor readout stage 2041 and a sensor response stage 2031.
  • an entire magnetic sensor array row is selected and biased with current (or voltage bias depending on the sensor design) and then the magnetic field induced analog voltage (or current depending on the sensor design) for each sensor in the selected row is amplified with noise cancellation, digitized, thermally compensated and captured in digital registers.
  • next sensor row is selected, and the process repeats row by row until the entire magnetic sensor array is measured.
  • the magnetic field measurement result can be transferred immediately to a host computer over a digital interface or buffered in an on-chip memory until the entire array is read before being bulk transferred to a host computer over a digital interface.
  • the magnetic sensor array is divided into parts with a dedicated readout channel (amplifier, digitizer, compensation, and capture) for each array part that enables each selected sensor row in each array part to be measured in parallel. The next sensor row in each array part is then selected and the process repeats row by row in each array part in parallel until the entire magnetic sensor array is measured.
  • a dedicated readout channel amplifier, digitizer, compensation, and capture
  • the magnetic sensor array device 3001 is divided into two parts with each array part measured in parallel using the serial measurement method.
  • two, two-dimensional magnetic sensor arrays 301 la and 301 lb that may be arranged in rows and columns (not shown) along with all the analog and digital circuitry necessary for a fully integrated device with a single digital interface (such as a I 2 C, but not limited to such) to a host computer system for each two-dimensional magnetic sensor arrays is provide.
  • the circuitry includes amplification with noise cancellation circuits 3021a, 3021b, analog voltage digitization circuits 3022a, 3022b, thermal compensation circuits 3023a, 3023b, digital capture registers 3024a, 3024b, memory buffers 3025a, 3025b, and components for transfer to a host computer 3026a, 3026b.
  • the magnetic sensor array device 3001 has a sensor readout stage 3041 and a sensor response stage 3031.
  • the parallel measurement method can be extended by dividing the array into an arbitrary number of parts each having a dedicated readout channel.
  • the parallel measurement method provides a measurement time speedup over the serial measurement method that is equivalent to the number of divided array parts (e.g., 2X, 4X, 8X, 16X, etc.)
  • serial and parallel measurement methods are summarized in Table 1 for an example 8-row x 8-column magnetic sensor array having a sensor response time and sensor readout time approximately equal.
  • the parallel measurement method provides a speedup of two times the serial measurement method. As stated, additional speedup can be obtained by dividing the array into additional parts with a dedicated readout channel per part.
  • the serial measurement method results in the lowest current (best case) to bias the sensors and the longest time (worst case) to readout the result and the parallel measurement method results in the highest current (worst case) to bias the sensors and the shortest time (best case) to readout the result. It is desirable to find a measurement method that provides the lowest current (best case) of the serial measurement method with the shortest measurement time (best case) like the parallel measurement method and this method is described as follows.
  • a serial pipeline measurement method is disclosed to reduce the total magnetic sensor array measurement time by a factor of approximately two as compared to the serial measurement method without increasing the current by a factor of approximately two as the parallel measurement method.
  • This optimization is enabled by inserting one or more analog sample and hold registers 4015 between the magnetic sensor array and the amplifier as shown in FIG. 4.
  • Shown in FIG. 4 is a two-dimensional magnetic sensor array 4011 that may be arranged in rows and columns (not shown) along with all the analog and digital circuitry necessary for a fully integrated device with a single digital interface (such as a I 2 C, but not limited to such) to a host computer system.
  • the circuitry includes a sample and hold circuit 4015 (for a selected row), along with an amplification with noise cancellation circuit 4021, an analog voltage digitization circuit 4022, a thermal compensation circuit 4023, a digital capture register 4024, a full array buffer 4025, and a component for transfer to a host computer 4026.
  • the magnetic sensor array device 4001 has a sensor readout stage 4041 and a sensor response stage 4031.
  • an entire magnetic sensor array row is selected and biased with current (or voltage bias depending the sensor design) and then the magnetic field induced analog voltage (or current converted to a voltage) for the selected row is captured in a sample and hold analog register decoupling the sensor response stage from the sensor readout stage and allowing the selected row to be incremented to the next row before the current row is readout.
  • This pipeline stage allows the current sensor row to be read out (amplified with noise cancellation, digitized, thermally compensated and captured in digital registers) while the next sensor row is selected and biased with current (or voltage) and responds to the magnetic field with an induced analog voltage (or current).
  • This pipelined process repeats row by row until the entire magnetic sensor array is measured. After each row is read out, the magnetic field measurement result can be transferred immediately to a host computer over a digital interface or buffered in an on-chip memory until the entire array is read out before being bulk transferred to a host computer over a digital interface.
  • sample and hold circuit 4015 can be placed at other points in the readout pipeline or duplicated at multiple points in the readout pipeline to optimize measurement time.
  • the sample and hold circuit could be placed before the amplification stage (as shown) or after the amplification stage (not shown) or both before and after the amplification stage (not shown).
  • serial pipelined measurement method provides a total magnetic sensor array measurement time speedup of two times the serial measurement method while maintaining the same current to bias the sensors as the serial measurement method.
  • the magnetic sensor array is divided into two parts with each array part measured in parallel using the serial pipelined measurement method.
  • FIG. 5 Shown in FIG. 5 is two, two-dimensional magnetic sensor arrays 501 la and
  • the circuitry includes a sample and hold circuits 5015a, 5015b (for a selected row), along with amplification with noise cancellation circuits 5021a, 5021b, analog voltage digitization circuits 5022a, 5022b, thermal compensation circuits 5023a, 5023b, digital capture registers 5024a, 5024b, full array buffers 5025a, 5025b, and components for transfer to a host computer 5026a, 5026b.
  • the magnetic sensor array device 5001 has a sensor readout stage 5041 and a sensor response stage 5031.
  • the parallel pipelined measurement method can be extended by dividing the array into an arbitrary number of parts each having a dedicated readout channel with the speedup equivalent to the number of parts.
  • the parallel pipelined measurement method provides a measurement time speedup over the parallel measurement method of approximately two times which is illustrated in Table 3.
  • the parallel and parallel pipelined measurement methods are summarized in Table 3 for an example 8-row x 8-column magnetic sensor array having a response time and readout time approximately equal. In the example where the array is divided into two parts with a dedicated readout channel for each part.
  • the parallel pipelined measurement method is approximately twice as fast as the parallel measurement method.
  • This staggered magnetic sensor arrangement provides a more uniform two- dimensional spatial resolution over the surface to be measured and higher density per magnetic sensor per unit area that benefits both measurement accuracy and manufacturing cost of the device.
  • the individual magnetic sensors 1007 e.g., are arranged in horizontal rows (1-Rl - 1-R8) and vertical columns (1-Cl - 1-C8) where each sensor in a row is aligned horizontally with every sensor in the same row and each sensor in a column is aligned vertically with every sensor in the same column.
  • This inline row and inline column arrangement of magnetic sensors can be modified to stagger every other sensor in the same row (staggered row) or every other sensor in the same column (staggered column).
  • the staggered row arrangement 6011 A is shown in FIG. 6A and the staggered column arrangement 601 IB is shown in FIG. 6b.
  • the stagger in the row, 6A-R1 A and 6A- R1B in FIG. 6A or in the column, 6B-C1L and 6B-C1R in FIG. 6B for example, introduces a spatial offset in the position of each sensor to the adjacent sensor in the next row (staggered row) or next column (staggered column) as illustrated.
  • the columns, 6A-C1 and 6A-C2 for example, remain inline, but the rows, 6A-R1 A and 6A-R1B in FIG.
  • 6A for example, are staggered with half the sensors spatially offset above and half the sensors spatially offset below.
  • the rows, 6B-R1A and 6B-R2A for example, remain inline, but the columns, 6B-C1L and 6B-C1R, for example, are staggered with half the sensors spatially offset left and half the sensors spatially offset right.
  • FIG. 7 illustrates a magnified view of an inline row and inline column arrangement of magnetic sensors, 7011, 7021-7028 that are spaced 100 pm center-to-center (100 pm spacing only for illustration), i.e., 100 pm center-to-center measured horizontally 7031-7036, and 100 pm center-to-center measured vertically 7041-7046.
  • the center-to-center horizontal measurements 7031 and 7033 are 100 pm
  • the center-to-center vertical measurements 7041 and 7042 are 100 pm between the four orthogonal neighbors
  • the center-to-center diagonal measurement 7051 between magnetic sensors 7021 and 7011 is 142.42 pm, which would be the same between 7022 and 7024 (not shown).
  • FIG. 8 illustrates a magnified view of an inline row and staggered column arrangement (corresponding to FIG. 6B) of magnetic sensors, 8011, 8021-8027 that are uniformly spaced 8041-8046 at 100 pm center-to-center from any sensor to any adjacent sensor.
  • Distances 8031, 8033, 8034, 8035, 8037 are the same as 8036 by symmetry.
  • Distances 8051 and 8052 are 86.8 pm for this example.
  • the completely uniform spatial characteristics with reduced area per sensor of the staggered layout optimizes the magnetic sensor array device in terms of magnetic measurement uniformity and manufacturing cost for an equivalent number of sensors in the array.
  • the type of thermal compensation algorithm and compensation parameters are both determined by experimentation during the development of the sensor by testing the sensor performance across the operating temperature range to find a combination of algorithm and parameters that eliminate the thermal distortion on the magnetic field measurement.
  • the parameters will be unique for each chip so a method is required to calibrate each individual chip during manufacturing test to determine its unique parameters and store them in a location where they can be retrieved and used when it is time to perform a thermal compensation on a magnetic field measurement.
  • FIG. 9 Illustrated in FIG. 9 is an authentication measurement system 9001.
  • the magnetic sensor array device 9011 of FIG. 1 is assembled onto a printed circuit card 9021 and interfaced 9061 with a host system controller 9041 on a printed circuit card 9081 over a digital interface such as a I 2 C interface block 9054.
  • the host system controller 9041 manages the magnetic field measurement process by instructing the magnetic sensor array device 9011 to make a magnetic field measurement and when complete it retrieves the data from the device.
  • the host system controller 9041 has a microcontroller 9051, a memory 9052, a network interface 9053, and a display 9055.
  • the host system controller 9041 may also interface with cloud or other network connected storage 9071 through any available connectivity path 9062.
  • the hardware on the chip or software running on the host system controller needs: (1) the thermal compensation algorithm (programmed in the hardware or software); (2) the thermal compensation parameters (measured and associated with an individual chip at manufacturing time); and (3) the actual temperature on-chip at the time of the measurement (read from a thermal diode(s) on-chip).
  • the thermal compensation algorithm programmed in the hardware or software
  • the thermal compensation parameters measured and associated with an individual chip at manufacturing time
  • the actual temperature on-chip at the time of the measurement read from a thermal diode(s) on-chip.
  • the first method is to store the unique thermal compensation parameters in a non-volatile memory (NVM) on the chip 9015 so that the parameters are included with each chip.
  • NVM non-volatile memory
  • the hardware or the software can read the parameters from the on-chip NVM and use them to perform the thermal compensation as previously described.
  • the on-chip thermal diodes can be placed by each cell but this would take too much space so typically they are placed to cover regions. For example, the quadrants designated by 1051 and 1055 may only have one on chip thermal diode for each of these areas. Each of these diodes would need to have calibration curves stored to correctly compensate the IC.
  • the second method stores the thermal compensation parameters off-chip in a very low-cost discrete NVM device 9031 that is paired with the magnetic sensor array device by physical and/or logical association.
  • Physical association is accomplished by including both the magnetic sensor array device and its associated NVM together by packaging the two devices together in shipping package or by assembling them into a multi-chip module (MCM).
  • Logical association is accomplished by writing the unique serial number (burned into electronic fuses at manufacturing) of the magnetic sensor array into the NVM and vice- versa if desired.
  • the third method stores the thermal compensation parameters off-chip in a cloud database 9071 that is indexed by the unique serial number (e.g., burned into electronic fuses at manufacturing) of the magnetic sensor array.
  • the magnetic sensor array serial number is read by the host system controller and used as an index to read the parameters for that specific device from the cloud database or from a locally buffered version of the cloud database in a memory 9052 on the host system controller 9041.
  • the thermal compensation parameters are then used by the hardware or the software to perform the thermal compensation as previously described.
  • the fourth method applies a compression algorithm (such as run length encoding but not necessarily limited to such) to the thermal compensation parameters before storing the parameters on-chip in a memory 9015 integrated with the sensor array or off-chip in a discrete memory device 9031 or off-chip in a cloud database 9071.
  • a compression algorithm such as run length encoding but not necessarily limited to such
  • the thermal compensation algorithm is executed on-chip with the sensor array, the compressed parameters can be decompressed on-chip (in hardware or software) before they are used as input to the thermal compensation algorithm (executed in hardware or software).
  • the thermal compensation algorithm is executed off-chip, the compressed parameters can be decompressed off-chip (in hardware or software) before they are used as input to the thermal compensation algorithm (executed in hardware or software).
  • the fifth method reduces the total storage by sharing the same thermal compensation parameters across multiple sensors.
  • each sensor will have its own thermal calibration parameters, but in the case where sensors are closely packed together on a common semiconductor substrate the thermal variation in the sensor performance may not vary greatly in local areas of the semiconductor. This means that the thermal compensation parameters can be shared across multiple sensors located in the same region without impacting the quality of magnetic field measurement result due to thermal variation.
  • the thermal compensation parameters can be associated with each magnetic sensor array device individually and when used by the compensation process, the magnetic field measurements from each individual magnetic array device is made intolerant to thermal distortion.
  • the compensation parameters for the thermal distortion will be compressed to save space and cost of the NVM. This compression can take many forms, but the preferred methods would be to fit the compensation curves by low order polynomials for each region around a thermal diode sensor. The preferred polynomial would be a third-order system but can be reduce to a second-order system in instances where a lower accuracy is acceptable.
  • the inputs would be the relative locations of the sensors relative to each of the individual magnetic sensors 1007 and the output would be the offset of the temperature compensation due to location.
  • Another compensation technique would be dynamic compensation for real time heating that takes place when each magnetic sensor 1007 location is energized.
  • the heat transfer is modeled by state machine with a thermal time constant and forcing function for each time the sensing element 1007 is energized.
  • the preferred state machine predicts next temperature x(t+l) at a sampled time to be current temperature state x(t) times the cooling coefficient “A” plus the forcing function u(t) that is proportional to the heat added to the system due to the Hall effect plate bias current.
  • the cooling coefficient “A” and forcing function u(t) would be common values for most of the interior elements but would different for elements near the edges.
  • the NVM would also contain compensation for the amplifiers and digitizers. These values would also need to be compressed by a similar curve fitted polynomial to compensate for both linear and higher order affects.
  • the positional resolution of the sensor is used to control the response time of the sensor depending on the read situation. For example, if the sensor is being positioned over the target then a faster/lower resolution read is needed to confirm that the rim of the sense area has a significant field compared to the interior.
  • the sensor receives a command sent to set the scan mode; simple scan modes could have a skip number to advance the scan index sequence. If the skip is set to 0, then all the cells are read as discussed above. If the skip is set to 1, then every other cell is measured.
  • the command may also limit the measurement to a particular magnetic field direction read to increase the speed of the response. During the positioning of the sensor only one direction is needed.
  • a second read is needed at higher resolution for predetermined locations.
  • a method to allow fast arbitrary path reads is needed.
  • One method is to create a mask that is formed in memory to determine the locations and directions to read for a skip.
  • Another method is to have a command sequence that routes the read direction and locations. Table 4 shows a number of commands that sequences the read locations in a predetermined order. The initial location may be at X and Y locations 0 and 0 respectively or any location set by another command.
  • the Field Direction (“FD”) part of the command is the directions of the magnetic field to be measured.
  • the Next Read Direction (“NRD”) is the direction to move in the X or Y direction (positive or negative) with respect to the current location.
  • the Index Count (“IC”) is a binary number ranging from 0 to 15 that represents a move of 1 to 16 locations, respectively, in the direction indicated by NRD.
  • the authentication system shown in FIG. 9, consists of a reader device 9001
  • the sensor integrated circuit should use secure cryptographic methods to protect the information being sent to and from the sensor IC and the reader device. These methods may include cryptographic protocols for device authentication, data integrity and data confidentiality.
  • FIG. 10 shows the sensor IC 10021 should be provisioned at the factory with a public/private key pair and/or a secret key and/or one or more digital certificates and/or a reader secret key that may be stored in the sensor IC non-volatile memory or electronic fuses and be used to protect the information and force each sensor to be paired with the reader system at the factory.
  • the reader host system controller 10011 may also be similarly provisioned with encryption keys and digital certificates.
  • the sensor IC 10021 may be authenticated by the reader, 10011 (one-way device authentication) by using a standard asymmetric authentication protocol with a public/private key pair 10015 and/or a digital certificate 10016 or by using a standard symmetric authentication protocol and shared secret key and/or a digital certificate where the keys and certificates are stored in the sensor IC when provisioned.
  • the reader may be authenticated by the sensor IC (two-way mutual authentication) using either a standard asymmetric or symmetric protocol and keys and/or certificates as just described. This system is illustrated in FIG.10.
  • a second factor authentication may be used to verify that a specific reader and a specific sensor IC have been cryptographically paired together when assembled at the factory.
  • the pairing is verified by using a standard or non-standard challenge/response protocol 10017 that proves that the sensor IC has possession of the reader secret key that it was provisioned with at the factory. This is also illustrated in FIG. 10.
  • the system may be considered genuine, but the data transferred across the interface may be further secured from tampering through the use of a standard message authentication code (“MAC”) or digital signature (“DS”).
  • MAC message authentication code
  • DS digital signature
  • the sensor IC may support the generation and verification of message authentication codes and/or digital signatures 1151 for some or all types of data transmission using a shared secret key (“SK”) stored in each device or derived using a secret key derivation algorithm.
  • SK shared secret key
  • the data transferred across the interface may be secured from eavesdropping by the use of standard encryption.
  • the sensor IC may support standard symmetric or asymmetric encryption and decryption 1161 for some or all types of data transmission using a shared secret key (“SK”) stored in each device or derived using a secret key derivation algorithm.
  • SK shared secret key
  • 3026b), 4 (4026), and 5 (5026a, 5026b) is the component that authenticates, encrypts or decrypts, and verifies the information.
  • This block can be integrated into the same IC as the sensor, or it can be a separate IC that is packaged together with the sensor IC in a multi-chip module.
  • any number of cryptographic protocols, cryptographic ciphers, and key generation and derivation methods may be used in the sensor IC to provide the features described.
  • the senor may also incorporate other tamper detection methods including thermal, voltage, or frequency variation to suspend operation.
  • the IC may have a detector that requires some minimum amount of magnitude and direction variation before a reading can commence. This would make it difficult to probe during operation for an attack method. For example, there must be at least ten different areas on the sensor with a minimum field level of 0.5, 1, 2, 4, 8 or 16 gauss depending on the application.
  • the threshold level set at the factory makes certain that the sensor is in the presence of a PUF before full operation may be established.
  • a challenge and response password system would allow a number of attempts to communicate with the sensor before the interface is permanently disabled.
  • a further invention shown in FIG. 12 is made by arranging the central regions of an Integrated Circuit (IC) with an N-row x M-column array (“N” along the Y-axis and “M” along the X-axis 1201, according to the coordinate-directions 1211) that are preferred to be horizontal Hall effect plates 1251 that measure the Z-directed magnetic field component Bz only.
  • Each central square is a Hall effect plate 1251 that is used to measure the Bz.
  • the Bx and By components can be computed in the interior region using known techniques.
  • additional Hall effect elements 1231, 1241 are arranged to measure the Bx and By components by using vertical elements, a method that is known in the art.
  • the area in the dashed box 1261 that show one arrangement of vertical and horizontal Hall effect elements that create a 3D (three-dimensional) measurement.
  • each Bz element 1251 have a Bx element 1231 or By element 1241 around the edge.
  • the vertical Hall effect plate density only needs to be enough for the resolution needed for the application.
  • the minimum vertical Hall effect plates per side would be one for Bx and one for By.
  • the preferred number would be N x (Bx and By) sensors per Y direction and M x (Bx and By) sensors per X direction.
  • the horizontal Hall effect plates to measure Bz 1311 are covered by a magnetic concentrator 1311 over the edge plates only 1312, 1321 for example.
  • the drawing is not drawn to scale and the interior plates 1311, for example, may be in far greater numbers than shown.
  • the coordinate system 1301 shows that the Bz direction is perpendicular to the surface of Hall effect plate 1311.
  • the technique was shown in the prior art for a single measurement element.
  • the concentrator may also be a square ring over the outer rows and columns of the array. The concentrator in this case diverts Bx and By field components and creates a low reluctance path to divert the flux through edge horizontal Bz Hall effect plates.
  • the Bx and By are estimated by taking the difference between the reading of the ring location and the adjacent Hall effect plate just inside the ring. This is fundamentally different than the assumptions made in the prior art that assume that the field is uniform over the surface of the entire sensor. The assumption here is that the field is similar over two adjacent cells.
  • FIG. 14 shows an array 1401 of 15 x 15 Hall effect plates 1421, for example, with concentrator rings 1441, for example, around the edge Hall effect plate elements 1431, for example, to extract the Bx and By pre-referral field components. This is preferred arrangement over the design in FIG. 13.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Hall/Mr Elements (AREA)

Abstract

L'invention concerne un dispositif de capteur magnétique doté d'un réseau de capteurs magnétiques disposés sur un substrat à semi-conducteur ordinaire pour mesurer le champ magnétique à axes multiples d'une région arbitraire avec une résolution spatiale élevée, une distance de détection réduite, un débit de mesure supérieur, une tolérance au mouvement, une tolérance à la température, et un rendement de fabrication amélioré. L'invention concerne également un dispositif de réseau de capteurs magnétiques à axes multiples fabriqué sur un substrat à semi-conducteur ordinaire qui est optimisé en offrant des améliorations supplémentaires pour réduire le temps de mesure, augmenter l'uniformité de résolution spatiale et réduire le coût de compensation thermique. En outre, la zone centrale d'une surface est utilisée pour mesurer le champ magnétique normal. L'invention concerne également un périmètre de plaques à effet Hall mesurant les composantes du champ magnétique dans le plan de la surface de mesure, ce qui permet une très haute densité de mesures de champ normal qui permet le calcul des composantes de champ dans le plan. Une erreur le long des bords peut être atténuée avec les composantes mesurées dans le plan.
PCT/US2021/021177 2020-03-05 2021-03-05 Optimisations de dispositif de réseau de capteurs magnétiques et caméra magnétique hybride WO2021178868A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030136837A1 (en) * 2000-06-28 2003-07-24 Amon Maurice A. Use of communication equipment and method for authenticating an item, unit and system for authenticating items, and authenticating device
US20040263376A1 (en) * 2003-04-09 2004-12-30 Sony Corporation Comparator, sample-and-hold circuit, differential amplifier, two-stage amplifier, and analog-to-digital converter
US20050245811A1 (en) * 2004-04-30 2005-11-03 University Of Basel Magnetic field sensor-based navigation system to track MR image-guided interventional procedures
US20170195596A1 (en) * 2014-05-27 2017-07-06 Rambus Inc. Oversampled high dynamic-range image sensor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030136837A1 (en) * 2000-06-28 2003-07-24 Amon Maurice A. Use of communication equipment and method for authenticating an item, unit and system for authenticating items, and authenticating device
US20040263376A1 (en) * 2003-04-09 2004-12-30 Sony Corporation Comparator, sample-and-hold circuit, differential amplifier, two-stage amplifier, and analog-to-digital converter
US20050245811A1 (en) * 2004-04-30 2005-11-03 University Of Basel Magnetic field sensor-based navigation system to track MR image-guided interventional procedures
US20170195596A1 (en) * 2014-05-27 2017-07-06 Rambus Inc. Oversampled high dynamic-range image sensor

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