A magnetic sensing device

Abstract

The utility model provides a kind of magnetic sensing device, it includes: piezoelectric substrate;First interdigital transducer, it is set on the piezoelectric substrate;Second interdigital transducer, it is set on the piezoelectric substrate and mutually spaced with the first interdigital transducer;Magnetic sensor, it is set on the piezoelectric substrate, and located between the first interdigital transducer and second interdigital transducer.Compared with prior art, the utility model is set by interdigital transducer and magnetic sensor on piezoelectric substrate, not only can realize integrated, low power consumption, and can generate enough power SAW, to improve the working performance of magnetic sensor, meet the need of detection.

Description

[Technical Field]

[0001] This utility model relates to the field of magnetic sensor technology, and in particular to a magnetic sensing device. [Background Technology]

[0002] A magnetic field sensor is a device that converts an external magnetic field and its changes into a measurable electrical signal response. This conversion allows magnetic field information to be recognized and processed by electronic systems, leading to the widespread application of magnetic field sensors in various fields, including navigation and positioning, safety monitoring, automotive driving assistance, scientific research, industrial automation, medical diagnostics, and medical equipment. Existing magnetic sensors have evolved into various types based on the Hall effect, AMR (Anisotropic Magnetoresistance), and TMR (Tunnel Magnetoresistance), but they still suffer from limitations such as single operating modes, limited detection range, and high power consumption, failing to simultaneously meet the demands for small size, integrability, a wide operating range, and high sensitivity.

[0003] Therefore, it is necessary to propose a new technical solution to overcome the above problems. [Utility Model Content]

[0004] The purpose of this invention is to provide a magnetic sensing device that is not only integrable and low-power, but also generates SAW (surface acoustic wave) with sufficient power to improve the working performance of the magnetic sensor and meet the detection requirements.

[0005] To achieve the purpose of the invention, according to one aspect of the present invention, a magnetic sensing device is provided, comprising: a piezoelectric substrate; a first interdigital transducer disposed on the piezoelectric substrate; a second interdigital transducer disposed on the piezoelectric substrate and spaced apart from the first interdigital transducer; and a magnetic sensor disposed on the piezoelectric substrate and located between the first interdigital transducer and the second interdigital transducer.

[0006] Compared with existing technologies, this invention, by setting interdigital transducers and magnetic sensors on a piezoelectric substrate, can not only achieve integrability and low power consumption, but also generate sufficient power SAW to improve the working performance of the magnetic sensor and meet the detection requirements. [Attached Image Description]

[0007] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Among them:

[0008] Figure 1 This is a cross-sectional schematic diagram of the magnetic sensing device in one embodiment of the present invention;

[0009] Figure 2 As in the first embodiment of this utility model Figure 1 Top view of the magnetic sensing device shown;

[0010] Figure 3 As in the second embodiment of this utility model Figure 1 Top view of the magnetic sensing device shown;

[0011] Figure 4 As in the third embodiment of this utility model Figure 1 Top view of the magnetic sensing device shown;

[0012] Figure 5 As shown in one embodiment of the present invention Figure 1-4 The diagram shows the workflow of the magnetic sensing device in enhanced mode.

Detailed Implementation Methods

[0013] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0014] The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Unless otherwise specified, the terms coupling, connection, linking, and interconnection used herein to indicate electrical connection mean direct or indirect connection. For example, A being connected to B includes both a direct electrical connection between A and B and a connection between A and B via electrical components or circuits.

[0015] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "back", "positive", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0016] Magnetoelectric (ME) devices combining piezoelectric and magnetostrictive materials have become powerful tools for miniaturization, enhanced sensing, and communication technologies. For geomagnetic sensors, parameters such as the temperature coefficient and linear region width of the magnetic layer largely depend on factors like material, size, and thin-film quality, and these parameters remain unchanged after film formation. However, by applying an alternating voltage to the piezoelectric material, causing lattice vibrations that generate surface acoustic waves (SAWs) that act on the magnetic layer, the parameters of existing magnetic sensors can be altered under different frequencies or amplitudes of alternating voltage. This allows for temperature coefficient compensation and sensitivity adjustment under varying operating environments.

[0017] In existing geomagnetic sensors (including Hall sensors, AMR sensors, and TMR sensors), surface acoustic waves (Rayleigh waves, Leff waves) have a modulating effect on the coercivity of Hall sensors and the linear range of AMR / TMR. When equipment containing sensors enters application environments where the geomagnetic field strength is greatly reduced, such as underground parking garages and shopping malls, magnetic field direction detection may fail. When surface acoustic waves propagate through the magnetic layer, magnetic atoms absorb some energy, and the sensitivity of the magnetic layer changes to varying degrees, allowing it to still function normally in environments with low geomagnetic field strength.

[0018] Furthermore, existing methods for generating surface acoustic waves (SAWs) include harmonic generation and delay line generation. Energy loss during SAW transmission is a significant issue, primarily stemming from edge radiation, lateral energy leakage, viscous losses in the piezoelectric crystal itself, and ohmic losses due to electrode heating. Therefore, this invention provides a magnetic sensing device that is not only integrable and low-power, but also capable of generating sufficiently powerful SAWs to enhance the sensitivity of the magnetic sensor and meet detection requirements.

[0019] Please refer to Figure 1 As shown, it is a cross-sectional schematic diagram of the magnetic sensing device in one embodiment of the present invention. Figure 1The magnetic sensing device shown includes a piezoelectric substrate 110, a first interdigital transducer 120, a second interdigital transducer 130, and a magnetic sensor 140.

[0020] The first interdigital transducer 120 is disposed on the piezoelectric substrate 110; the second interdigital transducer 130 is disposed on the piezoelectric substrate 110 and spaced apart from the first interdigital transducer 120; the magnetic sensor 140 is disposed on the piezoelectric substrate 110 and located between the first interdigital transducer 120 and the second interdigital transducer 130.

[0021] The first interdigital transducer 120 and the second interdigital transducer 130 can be made of common conductive metals (such as gold, copper, chromium, aluminum, etc.). The magnetic sensor 140 can be a conventional magnetic sensor.

[0022] exist Figure 1 In the embodiment shown, the piezoelectric substrate 110, the first interdigital transducer 120, the second interdigital transducer 130, and the magnetic sensor 140 are integrated into the same chip.

[0023] The piezoelectric substrate 110 includes a piezoelectric layer 112, a first interdigital transducer 120, a second interdigital transducer 130, and a magnetic sensor 140 disposed on the piezoelectric layer 112. The piezoelectric layer 112 is required to have a strong piezoelectric effect, such as quartz, PZT, PVDF, ZnO, and AlN, LiNbO3 (lithium niobate) with different tangential orientations, LiTaO3 (lithium tantalate) with different tangential orientations, etc.

[0024] The piezoelectric substrate 110 also includes a bonding layer 114 and a support layer 116. The piezoelectric layer 112, the bonding layer 114, and the support layer 116 are stacked sequentially. The bonding layer 114 is generally SiO2, and its function is to bond the piezoelectric layer 112 to the support layer 116. The support layer 116 can be made of a substrate widely used in industry (such as Si, SiC, SiN, etc.). In this case, the entire piezoelectric substrate 110 is a composite substrate consisting of the piezoelectric layer 112, the bonding layer 114, and the support layer 116.

[0025] To better illustrate the structure of the magnetic sensing device shown in this utility model, a three-dimensional rectangular coordinate system can be established. Figure 1 In the illustrated embodiment, the X-axis and Y-axis are perpendicular to each other and define the plane containing the piezoelectric substrate 110. The Z-axis is perpendicular to the plane defined by the X-axis and Y-axis. A three-dimensional Cartesian coordinate system is established using the X-axis, Y-axis, and Z-axis. Figure 1 This is reflected in the diagram, where the X-axis runs along the left-right direction, the Z-axis runs along the up-down direction, and the Y-axis runs perpendicular to the paper.

[0026] Please refer to Figure 2 As shown, this is the first embodiment of the present invention. Figure 1A top view of the magnetic sensing device shown. Figure 2 In the embodiment shown, the piezoelectric substrate is 210, the first interdigital transducer is 220, the second interdigital transducer is 230, and the magnetic sensor is 240.

[0027] Among them, piezoelectric substrate 210 and Figure 1 The piezoelectric substrate 210 shown has the same structure, so it will not be described again here.

[0028] The first interdigital transducer 220 includes a first group of metal fingers 222, a second group of metal fingers 224, a first arm (or first busbar) 226, and a second arm (or second busbar) 228. The first group of metal fingers 222 includes multiple metal fingers, and the second group of metal fingers 224 includes multiple metal fingers. The metal fingers of the first group of metal fingers 222 and the second group of metal fingers 224 are interleaved, spaced apart, and periodically distributed. The metal fingers of the first group of metal fingers 222 are connected to the first arm 226, and the metal fingers of the second group of metal fingers 224 are connected to the second arm 228. The metal fingers of the first group of metal fingers 222 extend from the first arm 226 to the second arm 228 at a predetermined distance from the second arm 228, and the metal fingers of the second group of metal fingers 224 extend from the second arm 228 to the first arm 226 at a predetermined distance from the first arm 226.

[0029] The second interdigital transducer 230 includes a first group of metal fingers 232, a second group of metal fingers 234, a first arm (or first busbar) 236, and a second arm (or second busbar) 238. The first group of metal fingers 232 includes multiple metal fingers, and the second group of metal fingers 234 includes multiple metal fingers. The metal fingers of the first group of metal fingers 232 and the second group of metal fingers 234 are interleaved, spaced apart, and periodically distributed. The metal fingers of the first group of metal fingers 232 are connected to the first arm 236, and the metal fingers of the second group of metal fingers 234 are connected to the second arm 238. The metal fingers of the first group of metal fingers 232 extend from the first arm 236 to the second arm 238 at a predetermined distance from the second arm 238, and the metal fingers of the second group of metal fingers 234 extend from the second arm 238 to the first arm 236 at a predetermined distance from the first arm 236.

[0030] exist Figure 2In the specific embodiment shown, the first interdigital transducer 220, the second interdigital transducer 230, and the magnetic sensor 240 are sequentially distributed along the X-axis. The first interdigital transducer 220 and the second interdigital transducer 230 are symmetrical about a straight line parallel to the Y-axis. Both the first interdigital transducer 220 and the second interdigital transducer 230 are double-interdigital transducers, wherein the metal fingers of the first group of metal fingers 222 and 232 and the metal fingers of the second group of metal fingers 224 and 234 are all straight and elongated strips; in the first interdigital transducer 220, each pair of adjacent metal fingers in the first group of metal fingers 222 and each pair of adjacent metal fingers in the second group of metal fingers 224 are staggered, spaced apart, and periodically distributed; in the second interdigital transducer 230, each pair of adjacent metal fingers in the first group of metal fingers 232 and each pair of adjacent metal fingers in the second group of metal fingers 234 are staggered, spaced apart, and periodically distributed. Compared to the first interdigital transducer 220, the magnetic sensor 240 is closer to the second interdigital transducer 230; or compared to the second interdigital transducer 230, the magnetic sensor 240 is closer to the first interdigital transducer 220. The first arms 226 and 236 of the interdigital transducers are parallel to each other with respect to the second arms 228 and 238. Thus, Figure 2 The configuration of the first interdigital transducer 220 and the second interdigital transducer 230 shown can cancel out the reflected SAW, and is therefore also called a non-reflective configuration.

[0031] Please refer to Figure 3 As shown, this is the second embodiment of the present invention. Figure 1 A top view of the magnetic sensing device shown. Figure 3 In the embodiment shown, the piezoelectric substrate is 310, the first interdigital transducer is 320, the second interdigital transducer is 330, and the magnetic sensor is 340.

[0032] Among them, the piezoelectric substrate 310 and Figure 1 The piezoelectric substrate 110 shown has the same structure, so it will not be described again here.

[0033] The first interdigital transducer 320 includes a first group of metal fingers 322, a second group of metal fingers 324, a first arm (or first busbar) 326, and a second arm (or second busbar) 328. The first group of metal fingers 322 includes multiple metal fingers, and the second group of metal fingers 324 includes multiple metal fingers. The metal fingers of the first group of metal fingers 322 and the second group of metal fingers 324 are interleaved, spaced apart, and periodically distributed. The metal fingers of the first group of metal fingers 322 are connected to the first arm 326, and the metal fingers of the second group of metal fingers 324 are connected to the second arm 328. The metal fingers of the first group of metal fingers 322 extend from the first arm 326 to the second arm 328 at a predetermined distance from the second arm 328, and the metal fingers of the second group of metal fingers 324 extend from the second arm 328 to the first arm 326 at a predetermined distance from the first arm 326.

[0034] The second interdigital transducer 330 includes a first group of metal fingers 332, a second group of metal fingers 334, a first arm (or first busbar) 336, and a second arm (or second busbar) 338. The first group of metal fingers 332 includes multiple metal fingers, and the second group of metal fingers 334 includes multiple metal fingers. The metal fingers of the first group of metal fingers 332 and the second group of metal fingers 334 are interleaved, spaced apart, and periodically distributed. The metal fingers of the first group of metal fingers 332 are connected to the first arm 336, and the metal fingers of the second group of metal fingers 334 are connected to the second arm 338. The metal fingers of the first group of metal fingers 332 extend from the first arm 336 to the second arm 338 at a predetermined distance from the second arm 338, and the metal fingers of the second group of metal fingers 334 extend from the second arm 338 to the first arm 336 at a predetermined distance from the first arm 336.

[0035] exist Figure 3In the specific embodiment shown, the first interdigital transducer 320, the second interdigital transducer 330, and the magnetic sensor 340 are sequentially distributed along the X-axis. The first interdigital transducer 320 and the second interdigital transducer 330 are symmetrical about a straight line parallel to the Y-axis. Both the first interdigital transducer 320 and the second interdigital transducer 330 are arc-shaped interdigital transducers, wherein the metal fingers of the first group of metal fingers 322 and 332 and the metal fingers of the second group of metal fingers 324 and 334 are arc-shaped. In the first interdigital transducer 320, the metal fingers of the first group of metal fingers 322 and the metal fingers of the second group of metal fingers 324 are interlaced, spaced apart, and periodically distributed. Furthermore, the metal fingers of the first group of metal fingers 322 and the metal fingers of the second group of metal fingers 324 are... The metal fingers of 324 are arranged concentrically from the magnetic sensor 340 in a direction away from the magnetic sensor 340. In the second interdigital transducer 330, the metal fingers of the first group of metal fingers 332 and the metal fingers of the second group of metal fingers 334 are interlaced, spaced apart, and periodically distributed. Furthermore, the metal fingers of the second group of metal fingers 332 and the metal fingers of the second group of metal fingers 334 are arranged concentrically from the magnetic sensor 340 in a direction away from the magnetic sensor 340. The first arms 326 and 336 of the interdigital transducer form a certain angle with the second arms 328 and 338, such as an acute angle.

[0036] exist Figure 3 In the specific embodiment shown, in the first interdigital transducer 320, the lengths of each metal finger of the first group of metal fingers 322 and each metal finger of the second group of metal fingers 324 gradually increase from the direction away from the magnetic sensor 340; in the second interdigital transducer 330, the lengths of each metal finger of the first group of metal fingers 332 and each metal finger of the second group of metal fingers 334 gradually increase from the direction away from the magnetic sensor 340. In the first interdigital transducer 320, the centers of the metal fingers of the first group of metal fingers 322 and the metal fingers of the second group of metal fingers 324 are called the first equivalent center (not shown) magnetic sensing. In the second interdigital transducer 330, the centers of the metal fingers of the first group of metal fingers 332 and the metal fingers of the second group of metal fingers 334 are called the second equivalent center (not shown). The fan-shaped region formed by the first interdigital transducer 320 with the first equivalent center overlaps with the fan-shaped region formed by the second interdigital transducer 330 with the second equivalent center, and the first equivalent center is closer to the second interdigital transducer 330, while the second equivalent center is closer to the first interdigital transducer 320 (for example, the equivalent center of the first interdigital transducer 320 is to the right of the equivalent center of the second interdigital transducer 330). Thus, Figure 3 The configuration of the first interdigital transducer 320 and the second interdigital transducer 330 shown has a certain focusing effect on SAW energy, which corresponds to a smaller magnetic sensor processing area.

[0037] Please refer to Figure 4 As shown, this is the third embodiment of the present invention. Figure 1 A top view of the magnetic sensing device shown. Figure 4 In the embodiment shown, the piezoelectric substrate is 410, the first interdigital transducer is 420, the second interdigital transducer is 430, and the magnetic sensor is 440.

[0038] Among them, piezoelectric substrate 410 and Figure 1 The piezoelectric substrate 110 shown has the same structure, so it will not be described again here.

[0039] The first interdigital transducer 420 includes a first group of metal fingers 422, a second group of metal fingers 424, a first arm (or first busbar) 426, and a second arm (or second busbar) 428. The first group of metal fingers 422 includes multiple metal fingers, and the second group of metal fingers 424 includes multiple metal fingers. The metal fingers of the first group of metal fingers 422 and the second group of metal fingers 424 are interleaved, spaced apart, and periodically distributed. The metal fingers of the first group of metal fingers 422 are connected to the first arm 426, and the metal fingers of the second group of metal fingers 424 are connected to the second arm 428. The metal fingers of the first group of metal fingers 422 extend from the first arm 426 to the second arm 428 at a predetermined distance from the second arm 428, and the metal fingers of the second group of metal fingers 424 extend from the second arm 428 to the first arm 426 at a predetermined distance from the first arm 426.

[0040] The second interdigital transducer 430 includes a first group of metal fingers 432, a second group of metal fingers 434, a first arm (or first busbar) 436, and a second arm (or second busbar) 438. The first group of metal fingers 432 includes multiple metal fingers, and the second group of metal fingers 434 includes multiple metal fingers. The metal fingers of the first group of metal fingers 432 and the second group of metal fingers 434 are interleaved, spaced apart, and periodically distributed. The metal fingers of the first group of metal fingers 432 are connected to the first arm 436, and the metal fingers of the second group of metal fingers 434 are connected to the second arm 438. The metal fingers of the first group of metal fingers 432 extend from the first arm 436 to the second arm 438 at a predetermined distance from the second arm 438, and the metal fingers of the second group of metal fingers 434 extend from the second arm 438 to the first arm 436 at a predetermined distance from the first arm 436.

[0041] exist Figure 4In the specific embodiment shown, the first interdigital transducer 420, the second interdigital transducer 430, and the magnetic sensor 440 are sequentially distributed along the X-axis. The first interdigital transducer 420 and the second interdigital transducer 430 are symmetrical about a straight line parallel to the Y-axis. Both the first interdigital transducer 420 and the second interdigital transducer 430 are trapezoidal interdigital transducers, wherein the metal fingers of the first group of metal fingers 422, 432 and the metal fingers of the second group of metal fingers 424, 434 are all straight elongated strips. In the first interdigital transducer 420, the metal fingers of the first group of metal fingers 422 and the metal fingers of the second group of metal fingers 424 are interlaced, spaced apart, and periodically distributed. Furthermore, the metal fingers of the first group of metal fingers 422 and the metal fingers of the second group of metal fingers 424 are parallel to each other, and from the magnetic sensor 440 in the direction away from the magnetic sensor 440, the first The lengths of the metal fingers in the first group of metal fingers 422 and the metal fingers in the second group of metal fingers 424 gradually increase. In the second interdigital transducer 430, the metal fingers in the first group of metal fingers 432 and the metal fingers in the second group of metal fingers 434 are interlaced, spaced apart, and periodically distributed. Furthermore, the metal fingers in the first group of metal fingers 432 and the metal fingers in the second group of metal fingers 434 are parallel to each other, and the lengths of the metal fingers in the first group of metal fingers 432 and the metal fingers in the second group of metal fingers 434 gradually increase from the magnetic sensor 440 away from the magnetic sensor 440. Figure 4 In the specific embodiment shown, the magnetic sensor 440 is closer to the second interdigital transducer 430 than the first interdigital transducer 420; or the magnetic sensor 440 is closer to the first interdigital transducer 420 than the second interdigital transducer 430. The first arms 426 and 436 of the interdigital transducers form a certain angle with the second arms 428 and 438, such as an acute angle.

[0042] It should be noted that this utility model Figure 1-4 The magnetic sensors 140, 240, 340, and 440 shown can be geomagnetic sensors or linear magnetic sensors; this utility model Figure 1-4 The magnetic sensors 140, 240, 340, and 440 shown can also be angle sensors, magnetic encoders, etc. Thus, the magnetic sensing device provided by this utility model can also reduce the saturation magnetic field for angle sensors, magnetic encoders, etc.

[0043] To facilitate understanding of this utility model, the following detailed description is provided. Figure 1-4 The working principle of the magnetic sensing device shown is illustrated, with magnetic sensors 140, 240, 340, and 440 being geomagnetic sensors as an example.

[0044] Interdigital transducers (IDTs) 120, 130, 220, 230, 320, 330, 420, and 430, fabricated based on piezoelectric substrates 110, 210, 310, and 410, can generate surface acoustic waves (SAWs) through the inverse piezoelectric effect under alternating voltage at a certain frequency. When the SAW propagates through magnetic sensors 140, 240, 340, and 440, part of the energy of the lattice vibration is absorbed by the magnetic layer, thereby modulating parameters such as hysteresis, sensitivity, and linear range of the magnetic layer. Since the IDTs 120, 130, 220, 230, 320, 330, 420, and 430 can realize the excitation-propagation-absorption process of SAW, their impact on the performance of the entire system is crucial. SAW is an elastic wave; vibrations propagate along the crystal surface. The characteristics of SAW are determined by the properties and structure of the piezoelectric crystal, and the frequency and propagation speed of SAW are influenced by the properties of the piezoelectric material and the electrode design.

[0045] When the chip is operating, under normal conditions (such as in an unobstructed outdoor plaza), the interdigital transducers (IDTs) 120, 130, 220, 230, 320, 330, 420, and 430 do not need to work. In this case, the magnetic sensing device operates in normal mode, and the magnetic sensors can detect the Earth's magnetic field normally. However, when entering indoor environments with weaker Earth magnetic fields, such as shopping malls or underground parking garages, the normal operating mode may not accurately reflect the true magnetic field information through electrical signals. In this case, the magnetic sensing device can enter enhancement mode. At this time, the interdigital transducers (IDTs) 120, 130, 220, 230, 320, 330, 420, and 430 need to be activated to generate SAW (Supervisory Wave) signals, thereby increasing the sensitivity of the magnetic sensors 140, 240, 340, and 440 and enabling them to detect weak magnetic field signals. In addition, the temperature coefficient of a device is also an important indicator in traditional magnetic sensors. The performance parameters reflected will deviate under different temperature conditions. When the magnetic sensors 140, 240, 340, and 440 mentioned in this invention are working below room temperature, the magnetic sensing device can enter an enhancement mode. At this time, even after the interdigital transducers (IDTs) 120, 130, 220, 230, 320, 330, 420, and 430 are working, they still maintain a small deviation, reducing the difficulty of compensation required and correspondingly having a wider low-temperature operating range.

[0046] In one embodiment, the magnetic sensing device provided by this invention has an enhanced mode and a conventional mode. In the enhanced mode, an alternating voltage of a certain frequency is applied to the first interdigital transducers 120, 220, 320, and 420. The corresponding regions of the piezoelectric layer below the first interdigital transducers 120, 220, 320, and 420 will generate SAW (i.e., surface acoustic waves). The SAW (i.e., surface acoustic waves) propagate through the magnetic sensors 140, 240, 340, and 440, and then reach the second interdigital transducers 130, 230, 330, and 430, where they are detected to obtain sensing signals. In the enhanced mode, the performance of the magnetic sensors 140, 240, 340, and 440 can be improved, such as their operating range, thus making them suitable for some special situations. In normal mode, no alternating voltage of a certain frequency is applied to the first interdigital transducers 120, 220, 320, and 420. That is, in enhanced mode, interdigital transducers 120, 130, 220, 230, 320, 330, 420, and 430 are operational; in normal mode, interdigital transducers 120, 130, 220, 230, 320, 330, 420, and 430 are not operational.

[0047] In one embodiment, when the detected geomagnetic signal is weaker than a predetermined magnetic signal threshold or the operating temperature is lower than a predetermined temperature threshold, the magnetic sensing device provided by this invention enters an enhanced mode; otherwise, the magnetic sensing device operates in a normal mode. Alternatively, the magnetic sensing device provided by this invention is controlled to operate in either an enhanced mode or a normal mode.

[0048] Please refer to Figure 5 As shown, this is one embodiment of the present invention. Figure 1-4 The diagram shows the workflow of the magnetic sensing device in enhanced mode. Figure 5 The workflow of the magnetic sensing device shown in enhanced mode includes the following steps.

[0049] Step 510: Given the known center frequencies f0 of the interdigital transducers (IDTs) 120, 130, 220, 230, 320, 330, 420, and 430, apply alternating voltages of the corresponding frequencies.

[0050] In step 520, the piezoelectric crystal undergoes mechanical vibration under the alternating voltage of the interdigital transducers 120, 130, 220, 230, 320, 330, 420, and 430, generating surface acoustic waves that propagate along the surface, with the energy almost concentrated on the surface of the piezoelectric crystal material.

[0051] In step 530, the energy passing through magnetic sensors 140, 240, 340, and 440 will be absorbed by the magnetic layers of magnetic sensors 140, 240, 340, and 440, changing their temperature coefficient, sensitivity, operating range, and other parameters.

[0052] In summary, the magnetic sensing device provided by this utility model has the following technical features and beneficial effects:

[0053] 1. The magnetic sensing device provided by this utility model is integrated by a single chip, which includes a magnetic sensor (algorithm module, storage module, magnetoresistive module), an interdigital transducer and a piezoelectric substrate.

[0054] 2. The magnetic sensing device provided by this utility model can ensure both the high quality of the magnetic part of the sensor and the generation of SAW with sufficient power.

[0055] 3. The magnetic sensing device provided by this utility model has a magnetic modulation effect on the vibration direction and propagation direction of sound waves.

[0056] 4. The magnetic sensing device design provided by this utility model includes, but is not limited to, modulation functions for temperature coefficient and sensitivity, and can realize other detection optimizations based on this structure and principle according to the algorithm.

[0057] 5. The magnetic sensing device provided by this utility model generates SAW-enhanced sensitivity in weak magnetic field environments where traditional magnetic sensors are difficult to detect, which is sufficient to meet the detection needs.

[0058] 6. The magnetic sensing device provided by this utility model increases the effective temperature of the magnetic moment of the magnetic layer at different temperatures, and has a certain temperature coefficient correction effect on the sensor.

[0059] 7. The magnetic sensing device provided by this utility model has high requirements for the fabrication process of the interdigital transducer (IDT), which directly affects the variable range of sensor sensitivity.

[0060] 8. The magnetic sensing device provided by this utility model designs a compensation modulation scheme between the magnetic sensor and the waveform characteristics generated by interdigital transducers of different configurations.

[0061] It should be noted that any modifications made by those skilled in the art to the specific embodiments of this utility model do not depart from the scope of the claims of this utility model. Accordingly, the scope of the claims of this utility model is not limited to the foregoing specific embodiments.

Claims

1. A magnetic sensing device, characterized in that, It includes: piezoelectric substrate; A first interdigital transducer is disposed on the piezoelectric substrate; The second interdigital transducer is disposed on the piezoelectric substrate and spaced apart from the first interdigital transducer. A magnetic sensor is disposed on the piezoelectric substrate and located between the first interdigital transducer and the second interdigital transducer.

2. The magnetic sensing device according to claim 1, characterized in that, The piezoelectric substrate, the first interdigital transducer, the second interdigital transducer, and the magnetic sensor are integrated into the same chip.

3. The magnetic sensing device according to claim 1, characterized in that, The first interdigital transducer and the second interdigital transducer are symmetrical about a straight line.

4. The magnetic sensing device according to any one of claims 1-3, characterized in that, Both the first interdigital transducer and the second interdigital transducer are referred to as interdigital transducers. The interdigital transducer includes a first set of metal fingers, a second set of metal fingers, a first arm, and a second arm. The first group of metal fingers includes multiple metal fingers, and the second group of metal fingers includes multiple metal fingers; the metal fingers of the first group of metal fingers and the metal fingers of the second group of metal fingers are interlaced, spaced apart from each other, and periodically distributed; the metal fingers of the first group of metal fingers are connected to the first arm, and the metal fingers of the second group of metal fingers are connected to the second arm; the metal fingers of the first group of metal fingers extend from the first arm to the second arm and are spaced apart from the second arm by a predetermined distance; the metal fingers of the second group of metal fingers extend from the second arm to the first arm and are spaced apart from the first arm by a predetermined distance.

5. The magnetic sensing device according to claim 4, characterized in that, Both the first and second interdigital transducers are biinterdigital transducers. In the bifid transducer, the metal fingers of both the first group and the second group are straight and elongated strips; the two adjacent metal fingers in the first group and the two adjacent metal fingers in the second group are staggered, spaced apart, and periodically distributed. The first arm and the second arm of the interdigital transducer are parallel to each other.

6. The magnetic sensing device according to claim 5, characterized in that, Compared to the first interdigital transducer, the magnetic sensor is closer to the second interdigital transducer; or Compared to the second interdigital transducer, the magnetic sensor is closer to the first interdigital transducer.

7. The magnetic sensing device according to claim 4, characterized in that, Both the first and second interdigital transducers are arc-shaped interdigital transducers. In the arc-shaped interdigital transducer, both the metal fingers of the first group of metal fingers and the metal fingers of the second group of metal fingers are arc-shaped; the metal fingers of the first group of metal fingers and the metal fingers of the second group of metal fingers are distributed in concentric circles from the magnetic sensor in a direction away from the magnetic sensor. The first arm and the second arm of the interdigital transducer form a certain angle.

8. The magnetic sensing device according to claim 7, characterized in that, In the interdigital transducer, the lengths of the metal fingers in the first group of metal fingers and the metal fingers in the second group of metal fingers gradually increase from the direction away from the magnetic sensor.

9. The magnetic sensing device according to claim 7, characterized in that, In the first interdigital transducer, the center of each metal finger of the first group of metal fingers and the center of each metal finger of the second group of metal fingers is called the first equivalent center. In the second interdigital transducer, the center of each metal finger of the first group of metal fingers and the center of each metal finger of the second group of metal fingers is called the second equivalent center. The fan-shaped region formed by the first interdigital transducer with the first equivalent center overlaps with the fan-shaped region formed by the second interdigital transducer with the second equivalent center, and the first equivalent center is closer to the second interdigital transducer, and the second equivalent center is closer to the first interdigital transducer.

10. The magnetic sensing device according to claim 4, characterized in that, Both the first and second interdigital transducers are trapezoidal interdigital transducers. In the trapezoidal interdigital transducer, the metal fingers of the first group of metal fingers and the metal fingers of the second group of metal fingers are both straight and elongated strips; the metal fingers of the first group of metal fingers and the metal fingers of the second group of metal fingers are parallel to each other; the length of the metal fingers of the first group of metal fingers and the metal fingers of the second group of metal fingers gradually increases from the magnetic sensor away from the magnetic sensor. The first arm and the second arm of the interdigital transducer form a certain angle.

11. The magnetic sensing device according to claim 1, characterized in that, The piezoelectric substrate includes a piezoelectric layer that exhibits the piezoelectric effect. The first interdigital transducer, the second interdigital transducer, and the magnetic sensor are disposed on the piezoelectric layer.

12. The magnetic sensing device according to claim 11, characterized in that, The piezoelectric substrate further includes a bonding layer and a support layer. The piezoelectric layer, bonding layer, and support layer are stacked sequentially. The bonding layer bonds the piezoelectric layer and the support layer.

13. The magnetic sensing device according to claim 11, characterized in that, It has enhanced mode and normal mode. In enhanced mode, when an alternating voltage of a certain frequency is applied to the first interdigital transducer, a surface acoustic wave (SAW) is generated in the corresponding region of the piezoelectric layer beneath the first interdigital transducer. The SAW propagates through the magnetic sensor, and then reaches the second interdigital transducer, where it is detected to obtain a sensing signal. In normal mode, no alternating voltage of a certain frequency is applied to the first interdigital transducer.

14. The magnetic sensing device according to claim 13, characterized in that, When the detected geomagnetic signal is weaker than a predetermined magnetic signal threshold or the operating temperature is lower than a predetermined temperature threshold, the magnetic sensing device enters an enhanced mode; otherwise, the magnetic sensing device operates in normal mode; or... The magnetic sensing device is controlled to operate in either enhanced or normal mode.

15. The magnetic sensing device according to any one of claims 1-3, 5-14, characterized in that, The magnetic sensor is a geomagnetic sensor or a linear magnetic sensor.

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