阅读说明：本技术 校正磁场产生装置及其磁场传感器与校正方法 (Correction magnetic field generating device, magnetic field sensor and correction method thereof ) 是由 傅乃中 郭明谕 汪大镛 于 2019-04-30 设计创作，主要内容包括：本发明公开了一种具校正磁场产生装置及其磁场传感器与校正方法,通过内建可以产生相互正交或接近正交且均匀的三轴向磁场的结构,使得磁场传感器可以得到三轴磁场校正信息,达到随时可以自我校正磁场感测能力的效果。其后,磁场传感器在实际进行测量时,可以通过此校正信息量对测量的结果进行校正,以提升测量三轴磁场信息的准确性。(The invention discloses a device with a correction magnetic field generating function, a magnetic field sensor and a correction method thereof, wherein a structure capable of generating mutually orthogonal or nearly orthogonal and uniform triaxial magnetic fields is built in the device, so that the magnetic field sensor can obtain triaxial magnetic field correction information, and the effect of self-correcting the magnetic field sensing capability at any time is achieved. And then, when the magnetic field sensor actually measures, the measurement result can be corrected through the correction information quantity, so that the accuracy of measuring the triaxial magnetic field information is improved.)

1. A corrective magnetic field generating device for generating a three-dimensional corrective magnetic field, comprising:

a first conductive plate for generating a first axial magnetic field of a known magnitude by a first current;

a second conductive plate disposed parallel or nearly parallel to one side of the first conductive plate, the second conductive plate generating a second axial magnetic field of a known magnitude orthogonal or nearly orthogonal to the first axial magnetic field by a second current; and

a conductive coil surrounding the first and second conductive plates for generating a third axial magnetic field of known magnitude orthogonal or nearly orthogonal to the first and second axial directions by a third current.

2. The apparatus of claim 1, comprising a power module, further comprising:

a power source; and

the multiplexer is used for switching the electric connection between the power supply and the first conductive plate, the second conductive plate or the conductive coil according to a control signal, so that the power supply provides the first current, the second current and the third current respectively.

3. The apparatus of claim 1, wherein the first current has a first direction and the second current has a second direction orthogonal or nearly orthogonal to the first direction.

4. The aligning magnetic field generating apparatus of claim 3, wherein the conductive coil is formed by a conductive wire wound around the first and second conductive plates to form at least one turn, the conductive coil having a vertical axis direction orthogonal or nearly orthogonal to the first and second flow directions.

5. The aligning magnetic field generating apparatus of claim 1, wherein the first conductive plate further has a plurality of first conductive plates juxtaposed with each other, wherein a space is provided between adjacent first conductive plates.

6. The aligning magnetic field generating apparatus of claim 1, wherein the second conductive plate further has a plurality of second conductive plates juxtaposed with each other, wherein a space is provided between adjacent second conductive plates.

7. A magnetic field sensor having the capability of self-correcting magnetic fields, comprising:

a first correction magnetic field generating device for generating a three-dimensional correction magnetic field, the correction magnetic field generating device comprising a first conductive plate, a second conductive plate and a conductive coil, wherein the first conductive plate generates a first axial magnetic field with a known magnetic field magnitude by a first current, the second conductive plate is arranged at one side of the first conductive plate in parallel or approximately in parallel, the second conductive plate generates a second axial magnetic field with the known magnetic field magnitude orthogonal or approximately orthogonal to the first axial direction by a second current, the conductive coil is arranged around the first and second conductive plates, and generates a third axial magnetic field with the known magnetic field magnitude orthogonal or approximately orthogonal to the first and second axial directions by a third current; and

the magnetic field sensing unit is arranged on one side of the first conductive plate and generates corresponding sensing information according to the first axial magnetic field, the second axial magnetic field and the third axial magnetic field;

and the control module is electrically connected with the magnetic field sensing unit to receive the sensing information and compare the sensing information corresponding to each axial magnetic field with the known magnetic field strength in the axial direction so as to determine the correction information corresponding to each axial magnetic field.

8. The magnetic field sensor of claim 7, comprising a power module, further comprising:

a power source; and

the multiplexer is used for switching the electric connection between the power supply and the first conductive plate, the second conductive plate or the conductive coil according to a control signal, so that the power supply provides the first current, the second current and the third current respectively.

9. The magnetic field sensor according to claim 7, wherein the first current has a first direction and the second current has a second direction orthogonal or nearly orthogonal to the first direction.

10. The magnetic field sensor of claim 9, wherein the conductive coil is formed by a conductive wire wound around the first and second conductive plates to form at least one turn, the conductive coil having a vertical axis oriented orthogonal or nearly orthogonal to the first and second flow directions.

11. The magnetic field sensor according to claim 7, wherein the first conductive plate further comprises a plurality of first conductive plates juxtaposed with each other, wherein a space is provided between adjacent first conductive plates.

12. The magnetic field sensor according to claim 7, wherein the second conductive plate further has a plurality of second conductive plates juxtaposed with each other, wherein a space is provided between adjacent second conductive plates.

13. The magnetic field sensor according to claim 7, further comprising a second calibration magnetic field generator disposed at a side of the first calibration magnetic field generator such that the magnetic field sensing unit is located between the first and second calibration magnetic field generators.

14. The magnetic field sensor of claim 7, further comprising a temperature sensing unit.

15. The magnetic field sensor according to claim 7, wherein the calibration information comprises one-axis magnetic field sensing sensitivity information and one-axis cross-axis orthogonality information.

16. A magnetic field calibration method for performing a self-calibration procedure, comprising the steps of:

providing a magnetic field sensor with a built-in correction magnetic field generating device, wherein the magnetic field sensor is provided with a magnetic field sensing unit;

the correction magnetic field generating device is used for generating magnetic fields with known magnetic field intensity and three different axial directions which are mutually orthogonal or nearly orthogonal in magnetic field direction;

the magnetic field sensing unit respectively senses the three magnetic fields in different axial directions to respectively generate corresponding sensing information; and

and comparing the sensed information of each axial direction with the known magnetic field strength of the corresponding axial direction to determine correction information of the magnetic field corresponding to each axial direction.

17. The method of claim 16, wherein the calibration information comprises magnetic field sensing sensitivity information and cross-axis orthogonality information for each axis.

18. The method of claim 16, further comprising the step of initiating the self-calibration procedure in response to a triggering event.

19. The method of claim 18, wherein the triggering event is turning on an application device with a magnetic field sensor, turning on an application associated with the magnetic field sensor, or a temperature detecting change.

Technical Field

The present invention relates to a magnetic field calibration technique, and more particularly, to a calibration magnetic field generating device with a built-in calibration magnetic field generating platform for generating a three-axis uniform calibration magnetic field, a magnetic field sensor with self-calibration magnetic field capability, and a calibration method.

Background

With the advance of technology, the application field of smart handheld devices (such as mobile phones or wearable devices) is gradually increasing. Generally, a magnetic field sensor is configured in the smart handheld devices for positioning the position and orientation, such as: electronic compass, geomagnetic fingerprint, indoor navigation, etc.

Magnetic field sensors typically use the magneto-resistive effect for magnetic field sensing. The magneto-resistance Effect (MR) refers to an Effect in which the resistance of a particular magneto-resistive material changes with a change in an applied magnetic field. It is thus possible to arrange materials with a magnetoresistive effect in the sensing device, exploiting this effect for various applications. At present, devices for magnetic sensing with magnetoresistive materials are more commonly used, such as Giant Magnetoresistive (GMR) magnetic sensors and Anisotropic Magnetoresistive (AMR) magnetic sensors.

Although the application fields of the magnetoresistive element are wide, there are some problems to be overcome. For example: in the context of applications, the sensing capability of a magnetoresistive element can be affected by many environmental factors, such as: temperature, or a magnetic field generated by its peripheral electronic components. In addition, the information sensed by the magnetoresistive element is also affected by the manufacturing process, such as: during the process of soldering the package on the circuit board, stress variation is generated (both hall effect and magneto-resistive sensors are stress sensitive). In addition, the sensing capability is degraded (aging) due to the use time, so that the information of the three-axis sensing magnetic field is not changed uniformly.

Because of the above-described problems, it is an important issue to correct a magnetic field sensor having a magnetoresistive element. In the prior art, compensation is performed by using a magnetoresistive sensing unit with a compensation coil on one side to conduct a compensation current. A compensation current is passed through the compensation coil to establish a compensation magnetic field to the magnetoresistive sensing unit. The compensation magnetic field can be used to correct the effect of the external interference magnetic field on the magnetoresistive sensing unit, and the correction effect can be controlled by the current magnitude of the compensation current. Further, for example, U.S. patent publication No. US5,532,584 discloses a parallel conductor for producing a calibrated magnetoresistive sensor for conducting a current to generate a magnetic field to be sensed by the magnetoresistive sensor. The sensed signals are used to correct for errors in the MR sensor due to temperature or prolonged use.

In addition, in the prior art, if the problem of inaccurate measurement of the magnetic field sensor is to be solved, the manufacturing procedure of the magnetic field sensor is usually adjusted and changed to improve the measurement accuracy of the magnetic field sensor, however, this method needs to spend many resources to adjust and improve the manufacturing procedure, resulting in the problem of increased production cost or yield, even if the chip manufacturer finishes the chip calibration, the stress variation (both the hall effect and the magnetoresistive sensor are stress sensitive) is generated due to the following processes of packaging and welding on the circuit board, or the time effect makes the three-axis variation different, or the temperature effect of each chip different, which cannot be compensated accurately, resulting in the accuracy deviation. Based on the current situation that the chip cannot be effectively and accurately corrected for the three axes after being installed, if the measurement accuracy cannot be effectively improved, the subsequent application troubles can be caused due to the fact that the chip does not have the accurate self-correction capability.

Therefore, how to improve the accuracy of the magnetic field sensor during use is a problem that needs to be improved urgently, and therefore, a calibration magnetic field generating device, a magnetic field sensor with self-calibration magnetic field capability and a calibration method thereof are needed to solve the defects of the prior art.

Disclosure of Invention

The invention provides a correction magnetic field generating device, a magnetic field sensor with self-correction magnetic field capability and a correction method, which can generate a three-dimensional orthogonal or nearly orthogonal, uniform and stable high-precision magnetic field through structural design so as to be beneficial to timely calibrating the magnetic field sensor, have the defects different from the prior design, and can not replace the problems of ex-factory verification, production uniformity and the like. In addition, in order to provide stable current, the invention further utilizes a single power supply module to provide a three-axis stable field, the accuracy and the feasibility of the application end are greatly improved after correction, and the proportion of the three-axis magnetic field can be maintained even if the power supply module is changed, so that the aim of accurate correction is fulfilled.

The invention provides a correction magnetic field generating device, a magnetic field sensor with self-correction magnetic field capability and a correction method thereof, which can perform self-correction at any time before delivery or after being installed in an application device, thereby achieving the effects of reducing the influence of environmental magnetic field, temperature effect, packaging effect and measurement capability attenuation caused by long-term use, and further achieving the effect of providing accurate magnetic field measurement results at any time.

In one embodiment, the present invention provides a calibration magnetic field generating device for generating a three-dimensional calibration magnetic field, including a first conductive plate, a second conductive plate, and a conductive coil. The first conductive plate generates a first axial magnetic field of a known magnitude by a first current. The second conductive plate is disposed parallel or nearly parallel to one side of the first conductive plate, and generates a second axial magnetic field of a known magnitude orthogonal or nearly orthogonal to the first axial magnetic field by a second current. The conductive coil is arranged around the first conductive plate and the second conductive plate in a surrounding mode, and a third axial magnetic field with the known magnetic field size, which is orthogonal or approximately orthogonal to the first axial direction and the second axial direction, is generated by a third current.

In one embodiment, the present invention provides a magnetic field sensor with self-calibration capability, which includes a first calibration magnetic field generating device, a magnetic field sensing unit and a control module. The first correction magnetic field generating device is used for generating a three-dimensional correction magnetic field and comprises a first conducting plate, a second conducting plate and a conducting coil, wherein the first conducting plate generates a first axial magnetic field with the known magnetic field size through a first current, the second conducting plate is arranged on one side of the first conducting plate in parallel or approximately in parallel, the second conducting plate generates a second axial magnetic field with the known magnetic field size which is orthogonal or approximately orthogonal to the first axial direction through a second current, the conducting coil is arranged around the first conducting plate and the second conducting plate, and a third axial magnetic field with the known magnetic field size which is orthogonal or approximately orthogonal to the first axial direction and the second axial direction is generated through a third current. The magnetic field sensing unit is arranged on the first conductive plate and generates corresponding sensing information according to the first axial magnetic field, the second axial magnetic field and the third axial magnetic field. The control module is electrically connected with the magnetic field sensing unit to receive the sensing information and compare the sensing information corresponding to each axial magnetic field with the known magnetic field strength in the axial direction to determine the correction information corresponding to each axial magnetic field.

In one embodiment, the present invention provides a magnetic field calibration method, which includes the following steps, first, providing a magnetic field sensor with a magnetic field sensing unit, wherein the magnetic field sensor is provided with a calibration magnetic field generating device. Then, the correction magnetic field generating device sequentially generates three magnetic fields with different axial directions, wherein the magnetic field intensity is known and the magnetic field directions are mutually orthogonal or nearly orthogonal. Then, the magnetic field sensing units respectively sense the three magnetic fields in different axial directions to respectively generate corresponding sensing information. Finally, the sensing information of each axial direction is compared with the known magnetic field strength of the corresponding axial direction to determine the correction information of the magnetic field corresponding to each axial direction.

In one embodiment, the calibration information includes one-axis magnetic field sensing sensitivity information and one-axis cross-axis orthogonality information.

Drawings

Fig. 1A is a schematic view of a calibration magnetic field generating device according to an embodiment of the present invention.

Fig. 1B and 1C are schematic cross-sectional views of AA and BB of the structure shown in fig. 1A, respectively.

FIG. 2 is a block diagram of an embodiment of generating a constant current.

Fig. 3A is a schematic view of a calibration magnetic field generating device according to an embodiment of the present invention.

Fig. 3B and 3C are schematic diagrams of the AA and BB cross-sections of the structure shown in fig. 3A.

FIG. 4 is a schematic view of another embodiment of the calibration magnetic field generating device of the present invention.

FIGS. 5A and 5B are schematic diagrams of different embodiments of the magnetic field sensor with self-calibration capability according to the present invention.

FIG. 6 is a diagram illustrating a magnetic field sensor with self-calibration capability according to the present invention.

FIG. 7 is a flowchart illustrating a magnetic field calibration method according to an embodiment of the present invention.

FIG. 8 is a flowchart illustrating a magnetic field calibration method according to another embodiment of the present invention.

Fig. 9A and 9B are schematic flow diagrams illustrating a magnetic field calibration method according to different embodiments of the present invention.

FIG. 10 is a flowchart illustrating a magnetic field calibration method according to another embodiment of the present invention.

FIG. 11 is a schematic diagram of a sensing curve of a magnetoresistive sensor.

Description of reference numerals: 2. 2a, 2 b-corrective magnetic field generating means; 20-a first conductive plate; 200-a conductive sheet; 21. 21 a-a second conductive plate; 210-a conductive sheet; 22. 22 a-a conductive coil; 220-top surface; 221-bottom surface; 222-medial side; 223-outer side; 23-a power supply module; 230-a power supply; 231-a multiplexer; i1-first constant current; i2-second constant current; i3-third constant current; b1, B2, B3-magnetic field; 3. 3 a-a magnetic field sensor; 30-a magnetic field sensing unit; 31-a control module; 32-a temperature sensing unit; 4. 4 a-calibration method; 40-46-step; 5-a calibration method; 500-514-step; 90. 91-curve.

Detailed Description

Various exemplary embodiments may be described more fully hereinafter with reference to the accompanying drawings, in which some exemplary embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout. The calibration magnetic field generating apparatus, the magnetic field sensor with self-calibration capability and the calibration method thereof will be described with reference to the drawings by various embodiments, which are not intended to limit the invention. The angle of the difference between the nearly parallel and parallel ranges between plus or minus 2 degrees, i.e., -2 to 2 degrees, can be regarded as nearly parallel; the angle difference between near-orthogonal and orthogonal ranges between about plus or minus 2 degrees, i.e., 88-92 degrees, can be considered near-orthogonal. The error range is determined by the conditions and precision of the process, and is not limited.

Referring to fig. 1A to 1C, fig. 1A is a schematic diagram of a calibration magnetic field generating device according to an embodiment of the present invention; FIGS. 1B and 1C are schematic diagrams of the AA and BB cross-sections of the structure shown in FIG. 1A. In this embodiment, the calibration magnetic field generating device 2 is used to generate a three-dimensional calibration magnetic field, and includes a first conductive plate 20, a second conductive plate 21, and a conductive coil 22. Wherein the first conductive plate 20 and the second conductive plate 21 are disposed approximately parallel or approximately parallel to each other. The conductive coil 22 is disposed around the first and second conductive plates 20 and 21, wherein the conductive coil 22 may be formed by a conductive wire and wound into a coil, and two free ends of the conductive coil 22 are not directly connected.

In the present embodiment, the first conductive plate 20 and the second conductive plate 21 may comprise a combination of rectangular plate, a metal wire with a hollow line, a thick plate conductor, or a metal-layer ion implantation. In the present embodiment, a gap height H1 is formed between the bottom surface of the first conductive plate 20 and the top surface of the second conductive plate 21; the conductive coil 22 has a top surface 220, a bottom surface 221, an inner side surface 222 close to the first conductive plate 20, and an outer side surface 223 opposite to the inner side surface, wherein the top surface 220 of the conductive coil 22 and the top surface of the first conductive plate 20 are located on the same horizontal plane, and the bottom surface 221 of the conductive coil 22 can also be aligned with the bottom surface of the first conductive plate 20. In addition, the conductive plate spacing H1 or the conductive plate size, the spacing length G1 between the conductive coil 22 and the first conductive plate 20 can be designed according to the application requirement, and is not limited.

Next, the magnetic field generated by the structure shown in fig. 1A is described, and the first conductive plate 20 generates a first axial (X) magnetic field B1 with a known magnetic field magnitude by a first constant current I1. The second conductive plate 21 is disposed parallel or nearly parallel to one side of the first conductive plate 20, and the second conductive plate 21 generates a second axial (Y) magnetic field of a known magnetic field magnitude orthogonal or nearly orthogonal to the first axial (X) by a second constant current I2. The conductive coil 22 is disposed around the first and second conductive plates 21, and generates a third axial (Z) magnetic field of a known magnetic field magnitude orthogonal or nearly orthogonal to the first and second axial directions (X, Y) by a third constant current I3. For example, the first constant current I1 flows into the first conductive plate 20 in the positive direction of the second axis (Y axis) to generate the uniform magnetic field B1 in the first axis (X axis), the second constant current I2 flows into the second conductive plate 21 in the negative direction of the first axis (X axis) to generate the uniform magnetic field B2 in the second axis (Y axis), the third constant current I3 flows along the conductive coil 22 to generate the uniform magnetic field B3 in the third axis (Z axis). Through the structural design, a three-axis orthogonal or nearly orthogonal, uniform and stable high-precision correction magnetic field can be provided to facilitate timely calibration of the magnetic field sensing unit, wherein the first conductive plate 20, the second conductive plate 21 and the conductive coil 22 can provide a highly orthogonal or nearly orthogonal field by using integrated circuit process precision, a uniform field is provided by avoiding process variation in design, a three-axis stable field is provided by using a single power supply module, the accuracy and feasibility of an application end are greatly improved after correction, and the three-axis magnetic field proportion can be maintained even if the power supply module is changed, so that the purpose of improving the sensing accuracy of the magnetic field sensing unit is achieved.

The three constant currents I1-I3 may originate from the same constant power module, or utilize the same mirror amplification, and are switched by the multiplexer only to maintain the three-axis current ratio. For example, fig. 2 is a block diagram of an embodiment of generating a constant current. In this embodiment, the power module 23 is implemented by a power module 23, wherein the power module 23 includes a power source 230 and a multiplexer 231 for switching the current, wherein the power source 230 is electrically connected to the multiplexer 231, and the multiplexer 231 is electrically connected to the first conductive plate 20, the second conductive plate 21 and the conductive coil 22 of the calibration magnetic field generating device 2. The multiplexer 231 is used for switching the power module 20 to be electrically connected to the first conductive plate 20, the second conductive plate 21 or the conductive coil 22 according to a control signal, so as to provide the first current I1-I3 respectively.

Referring to fig. 3A to 3C, fig. 3A is a schematic diagram of a calibration magnetic field generating device according to an embodiment of the present invention; fig. 3B and 3C are schematic diagrams of the AA and BB cross-sections of the structure shown in fig. 3A. The main structure of the calibration magnetic field generating device 2a of the present embodiment is substantially the same as that of the previous embodiment, and the difference is that the first and second conductive plates and the conductive coil structure are slightly different. In the present embodiment, the first conductive plate 20a is divided into a plurality of first conductive plates 200, and the plurality of first conductive plates 200 are arranged at intervals, and the number of the first conductive plates 200 is four; the second conductive plate 21a is divided into a plurality of second conductive plates 210, and the second conductive plates 210 are arranged at intervals, and the number of the second conductive plates 210 is four. It is noted that the number of the conductive sheets 200 or 210 is not limited to the number of the embodiments in the drawings, and may be determined as needed. The conductive coil 22a further extends from the conductive wire and then surrounds the first conductive plate 20a to form a coil structure with more than two turns, i.e. the conductive coil 22a surrounds the first conductive plate 21a with two turns by the conductive wire, and the first turn is adjacent to the first conductive plate 20a, and the second turn is located outside the first turn.

Please refer to fig. 4, which is a schematic diagram of another embodiment of the calibration magnetic field generating apparatus according to the present invention. The difference between this embodiment and the previous embodiments is that this embodiment is composed of two magnetic field generating devices 2 a. The two magnetic field generating devices 2a have a space in the Z direction, and a magnetic field sensing unit can be placed in the space between the two magnetic field generating devices to achieve a two-axis double parallel plate and one-axis solenoid design, thereby further providing a more stable uniform magnetic field. It should be noted that although the magnetic field sensor 2a shown in fig. 4 has the structure shown in fig. 3A, in another embodiment, it may be implemented by the structure shown in fig. 1A, or by a combination of the structures shown in fig. 1A and fig. 3A.

Please refer to fig. 5A, which is a diagram illustrating a magnetic field sensor with self-calibration capability according to an embodiment of the present invention. In the present embodiment, the magnetic field sensor 3 has a power module 23, a calibration magnetic field generating device 2, a magnetic field sensing unit 30 and a control module 31. The magnetic field sensor 3 can be applied to a reading head of a magnetic disk, an accelerometer (accelerometer), a gyroscope (gyroscope), an electronic compass for measuring geomagnetic angle change and the like, and can be widely applied to the fields of storage equipment, intelligent devices, the Internet of Things (IOT), automobile parts, equipment control, biomedical science and the like. The power module 23 is used to provide a stable current, and in one embodiment, may be configured as shown in fig. 2. The calibration magnetic field generating device 2 is electrically connected to the power module 23, the calibration magnetic field generating device 2 is configured to generate a three-dimensional calibration magnetic field, the calibration magnetic field generating device 2 may be as shown in fig. 1A, 3A or 4, and the embodiment is described with reference to the structure shown in fig. 1A. The first conductive plate 20 generates a first axial magnetic field B1 with a known magnetic field magnitude and magnetic field direction by a first current I1 generated by the power module, the second conductive plate 21 generates a second axial magnetic field B2 with a known magnetic field magnitude and magnetic field direction orthogonal or nearly orthogonal to the first axial direction by a second current I2 generated by the power module, and the conductive coil 22 generates a third axial magnetic field B3 with a known magnetic field magnitude and magnetic field direction orthogonal or nearly orthogonal to the first and second axial directions by a third current I3.

Referring to fig. 5A and fig. 6, the magnetic field sensing unit 30 is disposed at one side of the first conductive plate 20, and the magnetic field sensing unit 30 generates corresponding sensing information according to the first axial magnetic field, the second axial magnetic field and the third axial magnetic field. The magnetic field sensing unit 30 may be a magnetic sensing element such as a Hall effect (Hall effect) magnetic field sensor, an Anisotropic Magnetoresistive (AMR) sensor, a Giant Magnetoresistive (GMR) sensor, a Tunnel Magnetoresistive (TMR) sensor, or a flux gate (fluxgate) sensor. Since the calibration magnetic field generating device 2 is close to the magnetic field sensing unit 30, a close uniform field with a known magnetic field magnitude and direction can be provided, and the magnetic field sensing unit 30 can obtain corresponding sensing information by detecting the magnetic field.

The control module 31 is electrically connected to the magnetic field sensing unit 30 to receive the sensing information and compare the sensing information corresponding to each axial magnetic field with the known magnetic field strength in the axial direction, so as to determine the calibration information corresponding to each axial magnetic field. In the present embodiment, the calibration magnetic field generating device 2, the magnetic field sensing unit 30 and the control module 31 can be fabricated as an Integrated Circuit (IC) by an IC process. In the present embodiment, the three-dimensional coordinates include a first axial direction (X-axis), a second axial direction (Y-axis) and a third axial direction (Z-axis) perpendicular to each other. It should be noted that although the above-mentioned embodiment illustrates that the calibration magnetic field generating device 2, the magnetic field sensing unit 30 and the control module 31 can be fabricated as an Integrated Circuit (IC) by using an integrated circuit process, the invention is not limited thereto, for example: the control module 31 may be an external operation processing element or device, such as: the notebook computer or the desktop computer receives the information sensed by the magnetic field sensing unit.

Further, referring to fig. 5B, in the present embodiment, basically similar to fig. 5A, the difference is that a temperature sensing unit 32 is added, the temperature sensing unit 32 is electrically connected to the control module 31, the temperature sensing unit 32 is used for sensing the temperature or temperature variation information of the magnetic field sensor, and the temperature or temperature variation information may include the internal temperature variation and the external environment temperature during the operation of the magnetic field sensor, or a combination thereof. The sensed temperature or temperature change information is transmitted to the control module 31. The correction magnetic field generating device 2 generates a uniform correction magnetic field, the magnetic field sensing unit 30 senses the uniform magnetic field, and the sensed information is transmitted to the control module 31 for processing. In the present embodiment, the calibration magnetic field generating device 2, the magnetic field sensing unit 30, the temperature sensing unit 32 and the control module 31 can be fabricated as an Integrated Circuit (IC) by using an IC process. It should be noted that, although the above-mentioned embodiment is that the calibration magnetic field generating device 2, the magnetic field sensing unit 30, the temperature sensing unit 32 and the control module 31 can be fabricated as an Integrated Circuit (IC) by using an integrated circuit process, the invention is not limited thereto, for example: the control module 31 may be an external operation processing element or device, such as: the notebook computer or the desktop computer receives the information sensed by the magnetic field sensing unit.

Please refer to fig. 7, which is a flowchart illustrating a magnetic field calibration method according to an embodiment of the present invention. In the present embodiment, the magnetic field calibration method 4 includes the following steps. First, step 40 is performed to provide a magnetic field sensor with a magnetic field sensing unit, which is built with a calibration magnetic field generating device. In this step, the magnetic field sensor may be the magnetic field sensor 3 shown in fig. 5A, and the magnetic field sensor of fig. 5A may use the correction magnetic field generating device 2, 2a or 2b shown in fig. 1A, 3A or 4. Then, step 41 is performed to start the adaptive self-calibration procedure. It is noted that since the magnetic field sensor 3 may be provided in an application device, for example: smart handheld devices, or measuring devices, etc. Therefore, in one embodiment, the starting time may be when the application device is powered on, before the application device is used or measured each time, when the application program is started, or when the temperature or the magnetic field changes greatly. After the procedure of step 41 is started, step 42 is followed, in which the calibration magnetic field generating device 2 sequentially generates magnetic fields with known magnetic field strength and three different axial directions orthogonal or nearly orthogonal to each other. In step 42, the power module 23 shown in fig. 2 may be used to sequentially provide constant currents to the magnetic field induction generating device 2, for example: the uniform magnetic field B1 can be generated in the first axial direction (X axis) by flowing a first constant current I1 into the first conductive plate 20 along the positive direction of the second axial direction (Y axis), the uniform magnetic field B2 can be generated in the second axial direction (Y axis) by flowing a second constant current I2 into the second conductive plate 21 along the negative direction of the first axial direction (X axis), and the uniform magnetic field B3 can be generated in the third axial direction (Z axis) by flowing a third constant current I3 along the conductive coil 22.

Then, step 43 is performed to make the magnetic field sensing unit 30 respectively sense the three magnetic fields with different axial directions to respectively generate corresponding sensing information. Steps 42 and 43 may be performed in one embodiment by first flowing a first constant current I1 into the first conductive plate 20 in the positive direction of the second axial direction (Y-axis) to generate the uniform magnetic field B1 in the first axial direction (X-axis). The magnetic field sensing unit is then caused to modify the magnetic field B1. Then, a second constant current I2 is switched and supplied to the second conductive plate 21 in the negative direction of the first axial direction (X axis) at the power module, so as to generate the uniform magnetic field B2 in the second axial direction (Y axis). The magnetic field sensing unit is then caused to modify the magnetic field B2. Finally, the power module switches to supply a third constant current I3 to flow along the conductive coil 22 to generate the uniform magnetic field B3 in the third axial direction (Z axis). The magnetic field sensing unit is then caused to modify the magnetic field B3. It should be noted that, in another embodiment, the steps 42 to 43 may also include the power module providing the currents in three directions simultaneously, so that the calibration magnetic field generating device generates the magnetic fields in three axes simultaneously, and the magnetic field sensing unit 30 generates the magnetic field sensing information corresponding to the three axes.

42-43, proceeding to step 44, the sensed information of each axial direction is compared with the known magnetic field strength of the corresponding axial direction to calculate the measurement information about the change rate of the magnetic field of each axial direction. In one embodiment, the measurement information includes magnetic field sensing sensitivity information (the ratio between the known magnetic field strength and the sensed magnetic field strength) for each axis and cross-axis orthogonality. The cross-axis orthogonality represents the maximum azimuth angle of each axial magnetic field of the magnetic field sensing unit and the offset angle of the magnetic field direction of the correction magnetic field generating device. It should be noted that, in this step, the magnetic field sensing unit 30 respectively senses the uniform magnetic fields in different axial directions, and then transmits the sensed data and information to the control module 31 or an external operation processing device for processing, and when the current is reversed, the two-fold change amount can be obtained, so that a more accurate result can be obtained, and therefore, the application in the positive and negative directions of the constant current supplied by the power module 23 is not limited.

Since the calibration magnetic field generated by the calibration magnetic field generating device 2 is a uniform magnetic field with a known magnetic field strength and mutually orthogonal or nearly orthogonal axial directions, when the magnetic field strength sensed by the magnetic field sensing unit for each axis is Bs1 (corresponding to the calibration magnetic field X axial magnetic field B1), Bs2 (corresponding to the calibration magnetic field Y axial direction B2) and Bs3 (corresponding to the calibration magnetic field Z axial direction B3), after the control module 31 obtains Bs1, Bs2 and Bs3, it can calculate with the known B1, B2 and B3 to obtain the measurement information about the change rate of each axial magnetic field.

Please refer to fig. 8, which is a flowchart illustrating a magnetic field calibration method according to another embodiment of the present invention. In the present embodiment, the magnetic field calibration method 4a is substantially similar to the flow of fig. 7, except that the magnetic sensor of the present embodiment uses the structure of fig. 5B, that is, a temperature sensing unit 32 is provided in the magnetic sensor, which can correct the temperature influence on the measured magnetic field according to the temperature or the temperature variation. Because the magnetic field sensing unit, for example: since the magnetoresistive sensor may have a change in sensing output due to a temperature change, a database may be first established for output information sensed by the magnetic field sensing unit in an environment with a temperature change. Then, in the process shown in fig. 8, when measuring the magnetic field, step 46 may be performed to read the sensing signal of the temperature sensing unit, and then step 44 is performed, and step 45 is performed to correct the measured magnetic field by the temperature change to obtain the corrected magnetic field sensing information with temperature correction.

It should be noted that when a temperature sensing unit 32 is installed, the current temperature can be read before each measurement, and it is determined whether to restart the adaptive self-calibration procedure to reduce the time of the adaptive self-calibration procedure and increase the output frequency, or when the adaptive self-calibration procedure is started to be used, the adaptive self-calibration procedure is started once again and the initial temperature is recorded, and then the temperature change is observed, and the sensitivity formula related to the corrected temperature is directly introduced to achieve the highest output frequency, so that the convenience of application can be greatly improved, and the situation of large temperature change can be dealt with. Or when the electronic compass is used, the three-axis magnetic field sensing unit can ignore the temperature change when the three-axis sensitivity is consistent with the temperature change, and the angle can be accurate.

Please refer to fig. 9A and 9B, which are schematic flow charts of different embodiments of the magnetic field calibration method according to the present invention, respectively. The flow of fig. 9A is basically similar to the flow of fig. 7, except that the flow further includes a step 40a of setting the direction of the magnetic field generated by the correction magnetic field generating device and the positive and negative magnetic fields. Similarly, the flow of fig. 9B is basically similar to the flow of fig. 8, except that the present flow further includes a step of setting the direction and positive and negative magnetic fields generated by the correction magnetic field generating device in step 40 a. It should be noted that, in one embodiment, in the step 40a, the magnitude of the magnetic field generated by the calibration magnetic field generating device for each axial direction (X, Y and Z) can be changed by the magnitude of the constant current value supplied. And the positive and negative directions of the magnetic field can be changed by controlling the flow direction of the set current. It should be noted that, when the current passes through the forward direction and the reverse direction, the two times of variation can be obtained, so as to obtain a more precise result, and the same current magnitude can be changed or different current gears can be used, so as to improve the precision of the actual application range, so that the positive and negative currents and the magnitude can generate different magnetic fields, so as to facilitate the application range, and the design is not limited thereto.

In the magnetic field sensor corrected by the correction flow shown in fig. 7-8 and fig. 9A-9B, the acquired correction information, including the magnetic field sensing sensitivity information of each axial direction and the cross-axis orthogonality information, can be used to correct the measured magnetic field information during actual measurement, so as to maintain the accuracy of the measured magnetic field at any time.

Please refer to fig. 10, which is a flowchart illustrating a magnetic field calibration method according to another embodiment of the present invention. In this embodiment, it is an integrated application of the magnetic field sensor. The magnetic field sensor has a correction magnetic field generating device, a magnetic field sensing unit, and a temperature sensing unit. The magnetic field sensor is arranged in an application device, such as: smart handheld devices, such as: such as a cell phone or tablet computer. The calibration method 5 includes first performing step 500, and initiating a trigger event, where the trigger event is to start an application device with a magnetic field sensor, start an application program associated with the magnetic field sensor, or detect a change in temperature. After a trigger event occurs, step 501 is performed to start a self-calibration procedure. After the self-calibration procedure is started, first, in step 502, information of temperature or temperature variation is obtained to determine parameters affecting the magnetic field. In this step, the variation of the magnetic field sensitivity with temperature change can be corrected by reading the sensing information of the temperature sensing unit and using the sensing information.

After step 502, step 503 is performed to set the calibration magnetic field information, including the set magnetic field directions (X, Y and Z), and the positive and negative magnetic fields. In one embodiment, the magnetic field in the X-axis direction may be set first, for example, the positive magnetic field in the X-axis direction may be set first. Then, step 504 is performed to generate a correction magnetic field in the X direction according to the setting of step 503. Then, step 505 is performed to measure the magnetic field signals in the three-axis directions. After the measurement is completed, in step 506, since the magnetic field in the negative direction of the X axis is not measured yet, the step 503 is returned to set the magnetic field in the X axis to be the negative direction, and the steps 504 and 505 are repeated. After completing the measurement of an axial magnetic field, step 507 calculates the correction information of the axial magnetic field, which includes the axial magnetic field sensing sensitivity information and a cross-axis orthogonality information. For example: taking this embodiment as an example, since the set axial direction is the X axial direction and is a known magnetic field magnitude, the measured information should be (Bx,0,0) theoretically. However, due to the influence of the environmental magnetic field or the aforementioned situations, the sensed information may be (Bx, by, bz), where by and bz represent the sensitivity change and cross-axis orthogonality information in the Y-axis direction and the Z-axis direction.

Similarly, after the measurement of the X-axis is completed, it is determined whether all the XYZ triaxial directions have been measured according to step 508, if not, the process returns to step 503 to set another axis, such as the Y axis or the Z axis, and then the steps 503 to 508 are repeated until all the corrected magnetic field information of the XYZ triaxial directions have been measured. Thereafter, step 509 is performed to end the self-calibration procedure. Then, step 510 is performed, which represents that after the magnetic field is measured in actual application, the actually sensed magnetic field readings are corrected according to the temperature influence of step 502 and the correction information of each axis obtained in step 507. Therefore, the accuracy of each magnetic field sensing can be ensured, and the sensing capability of the magnetic field sensor is prevented from being influenced by various environments.

And steps 511-514 represent a dynamic calibration procedure for the magnetic field sensor. That is, when the dynamic calibration is started, it can be determined whether there is a difference in the sensing, and if so, the self-calibration procedure is performed at any time. In one embodiment, a dynamic calibration procedure is initiated in step 511, such as: the period of correction is set. Then, step 512 is performed to determine whether the cycle time is up, and if so, the step returns to step 501 to start the self-calibration procedure. If not, the number of measurements and the corresponding measurement results are recorded in step 513, and then it is determined whether the measurement results are abnormal in step 514, if so, the self-calibration procedure is actively restarted in step 201 even if the cycle time has not yet come. Otherwise, if not, go back to step 510 to continue the normal sensing and the procedure of correcting the magnetic field sensing value with the previous correction information.

In summary, the calibration magnetic field sensing apparatus and the self-calibration magnetic field calibration method of the present invention can not only perform calibration before the magnetic field sensor leaves the factory, but also perform self-calibration procedures according to requirements and settings at any time in any situation of the magnetic field sensor after leaving the factory, so as to improve the accuracy of the magnetic field sensing unit in sensing magnetic field information and reduce errors. Therefore, the invention can solve the problem of cost increase caused by improving the measurement accuracy only by improving the manufacturing procedure, thereby achieving the purposes of improving the measurement accuracy and reducing the cost, and ensuring that the magnetic field sensor is more reliable and durable.

For example: as shown in fig. 11, the graph is a diagram illustrating a sensing curve of a normal magnetoresistive sensor. Normally, a general magnetic sensing unit, for example: the graph of the relationship between the intensity of the magnetic field sensed by the magnetoresistive sensor and the voltage or current output is shown as a curve 90 in fig. 11, and a linear regression line obtained after linear regression is a straight line denoted by reference numeral 91. It can be seen that the measurement interval available for a typical magnetic sensing unit (magnetoresistive sensor) is roughly the linear range of region D shown in fig. 11. Since the relationship between the measured voltage or current and the corresponding sensed magnetic field is no longer linear after exceeding the linear range, the error varies with the magnitude of the magnetic field. Therefore, the region D in fig. 11 can be regarded as a sensing region that can be used for a general magnetoresistive sensor.

However, the magnetic field sensor formed by integrating the magnetic sensing unit (magnetoresistive sensor) and the correction magnetic field generating device of the present invention can perform a self-correcting function at any time. Even under conditions that do not have linearity, for example: as long as the calibration information in the environment is found by the self-calibration method described above, a new sensing basis can be established based on the magnetic field in the environment, so that the magnetic field sensor can be used in an environment that affects the sensing accuracy, for example: temperature, or the environment of the magnetic field generated by its peripheral electronic components, or the situation of degraded sensing capability (aging) due to time of use, can still be used normally.

The above description is only for the purpose of describing preferred embodiments or examples of the present invention by means of solving the problems, and is not intended to limit the scope of the present invention. The scope of the invention is to be determined by the following claims and their equivalents.