Angular displacement measuring device
By setting a magnetoresistive element design with specific spatial position difference and phase relationship on the magnetic gate, combined with the Wheatstone bridge circuit, the problem of insufficient origin signal reading error and anti-interference ability of traditional angular displacement measuring devices at small magnetic pole distances is solved, and high-precision Z-phase magnetic pole recognition and origin signal detection are achieved.
Patent Information
- Application Number
- CN202510765300.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2025-08-15
AI Technical Summary
Under the condition of small magnetic pole distances, it is difficult for traditional angular displacement measurement devices to accurately distinguish the boundaries between Z-phase magnetic poles and other magnetic poles, resulting in errors in the reading of origin signals, poor anti-interference ability and limited resolution.
The magnetic sensor arranged on the magnetic gate is adopted, including the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element and the fourth magnetoresistive element. Through the specific spatial position difference and phase relationship design, an orthogonal signal detection unit and a reference reference signal are formed to enhance the recognition ability of Z-phase boundaries, and a differential signal is outputted using the Wheatstone bridge circuit.
Under the condition of small magnetic pole distance, accurate identification of Z-phase magnetic poles and stable detection of origin signals are achieved, measurement accuracy and anti-interference ability are improved, and magnetic charging difficulty and manufacturing cost are reduced.
Smart Images
Figure CN120488936A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of magnetic field detection, and in particular to an angular displacement measuring device. Background Art
[0002] In existing angular displacement measurement devices, magnetic sensors typically generate orthogonal signals (phases A and B) by detecting periodically arranged magnetic pole signals, and combine these with a specific Z-phase signal to indicate the origin position. However, under small magnetic pole pitch conditions (e.g., ≤0.5mm), the Z-phase magnetic pole easily diffuses into the unwritten magnetic area, resulting in a blurred magnetic field distribution. In this case, traditional sensor designs have difficulty effectively distinguishing the boundary between the Z-phase magnetic pole and other magnetic poles, making it impossible to accurately read the origin signal of the magnetic grid. Summary of the Invention
[0003] The present invention aims to improve at least one technical problem in the background technology.
[0004] The present invention provides an angular displacement measuring device, comprising: A magnetic grid having a magnetic field distribution that varies along its length; a magnetic sensor, which is arranged on the magnetic grid and slides along the length direction of the magnetic grid; The magnetic sensor includes a first magnetoresistive element, a second magnetoresistive element, a third magnetoresistive element, and a fourth magnetoresistive element electrically connected to each other; The spatial position difference between the first magnetoresistive element and the third magnetoresistive element is half of the magnetic pole pitch of the magnetic grid; the spatial position difference between the second magnetoresistive element and the fourth magnetoresistive element is half of the magnetic pole pitch of the magnetic grid; the spatial position difference between the second magnetoresistive element and the third magnetoresistive element is zero; and the spatial position difference between the first magnetoresistive element and the fourth magnetoresistive element is the magnetic pole pitch of the magnetic grid; The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element are used to read the origin signal of the magnetic grid according to the change of the magnetic field distribution.
[0005] The beneficial effects of the present invention are as follows: the first magnetoresistance element and the third magnetoresistance element, the second magnetoresistance element and the fourth magnetoresistance element respectively constitute a half-pole pitch position difference layout, forming two groups of orthogonal signal detection units, and realizing the subdivision identification of the magnetic field distribution through the phase difference characteristics of their detection signals; the second magnetoresistance element and the third magnetoresistance element constitute a zero position difference layout, ensuring that the two synchronously sample the same magnetic field area to form a benchmark reference signal for noise suppression; the first magnetoresistance element and the fourth magnetoresistance element constitute a pole pitch position difference layout, so that when sliding over the Z-phase magnetic pole area, a complete periodic response contrast is formed, thereby enhancing the ability to identify the Z-phase boundary; when the magnetic sensor slides over the Z-phase magnetic pole area, each magnetoresistance element generates an electrical signal response with a clear phase relationship based on the preset spatial position difference. This phase relationship enables the magnetoresistance element array to accurately distinguish the magnetic field change characteristics of the Z-phase magnetic pole, thereby realizing stable detection of the origin signal.
[0006] As some sub-solutions of the above technical solution, the first magnetoresistance element and the third magnetoresistance element have the same size, and have the same positional relationship in the direction perpendicular to the magnetic field distribution, and the spatial position difference in the direction parallel to the magnetic field distribution is half of the magnetic pole pitch of the magnetic grid; the second magnetoresistance element and the fourth magnetoresistance element have the same size, and have the same positional relationship in the direction perpendicular to the magnetic field distribution, and the spatial position difference in the direction parallel to the magnetic field distribution is half of the magnetic pole pitch of the magnetic grid.
[0007] As some sub-solutions of the above technical solution, the magnetic sensor also includes a substrate and at least four electrodes; the first magnetoresistance element, the second magnetoresistance element, the third magnetoresistance element, the fourth magnetoresistance element and the electrodes are arranged on the substrate; the first magnetoresistance element, the second magnetoresistance element, the third magnetoresistance element, the fourth magnetoresistance element and the electrodes together constitute a differential circuit; the differential circuit is used to receive electrical signals from the magnetoresistance elements and output differential signals.
[0008] As some sub-solutions of the above technical solution, the differential circuit is a Wheatstone bridge circuit; the first magnetoresistance element, the second magnetoresistance element, the third magnetoresistance element, and the fourth magnetoresistance element respectively constitute four bridge arms of the Wheatstone bridge circuit.
[0009] As some sub-solutions of the above technical solution, the electrodes include a Z-phase positive electrode, a Z-phase negative electrode, a power supply electrode and a ground electrode; the Z-phase positive electrode is connected to the first magnetoresistance element and the third magnetoresistance element; the Z-phase negative electrode is connected to the second magnetoresistance element and the fourth magnetoresistance element; the power supply electrode is connected to the first magnetoresistance element and the second magnetoresistance element; and the ground electrode is connected to the third magnetoresistance element and the fourth magnetoresistance element.
[0010] As some sub-solutions of the above technical solution, the first magnetoresistance element, the second magnetoresistance element, the third magnetoresistance element and the fourth magnetoresistance element each include a plurality of magnetoresistance strips connected in series; the width of each magnetoresistance strip is consistent, and the total length of each magnetoresistance strip after being connected in series is consistent.
[0011] As some sub-solutions of the above technical solution, the magnetoresistive strip has an easy magnetization characteristic along its long axis, and when the direction of the external magnetic field is perpendicular to the long axis of the magnetoresistive strip, the resistivity change value of the magnetoresistive strip reaches a maximum.
[0012] As some sub-solutions of the above technical solution, the magnetoresistive strips of the second magnetoresistive element and the third magnetoresistive element are nested with each other.
[0013] As some sub-solutions of the above technical solution, as some sub-solutions of the above technical solution, the magnetic grid includes an AB phase magnetic scale and a Z phase magnetic scale; the AB phase magnetic scale and the Z phase magnetic scale are arranged opposite to each other.
[0014] As some sub-solutions of the above technical solution, the AB phase magnetic scale has multiple magnets arranged along its length direction, the pole directions of adjacent magnets are arranged alternately, the N pole and S pole of each magnet are respectively located at the two ends of the width direction of the AB phase magnetic scale, and the multiple magnets form a periodically arranged magnetic pole array; the Z phase magnetic scale has a magnet, and the N pole and S pole of the magnet are respectively located at the two ends of the width direction of the Z phase magnetic scale. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 A schematic structural diagram of an angular displacement measuring device provided in an embodiment of the present invention; Figure 2 Schematic diagram of the magnetic sensor circuit structure; Figure 3 Schematic diagram of the magnetic sensor structure; Figure 4 This is a simulation diagram of the electrical signal response of the magnetoresistive element under the first position difference relationship; Figure 5 This is a simulation diagram of the electrical signal response of the Z-phase signal under the first position difference relationship; Figure 6 The figure shows the test results of the magnetic sensor for the A, B, and Z phase signals under the first position difference relationship; Figure 7 This is the signal amplification diagram of the magnetic sensor's test results for the A, B, and Z phase signals under the first position difference relationship; Figure 8 This is a simulation diagram of the electrical signal response of the magnetoresistive element under the second position difference relationship; Figure 9This is a simulation diagram of the electrical signal response of the Z-phase signal under the second position difference relationship; Figure 10 This is a simulation diagram of the electrical signal response of the magnetoresistive element under the third position difference relationship; Figure 11 This is a simulation diagram of the electrical signal response of the Z-phase signal under the third position difference relationship; Figure 12 This is a simulation diagram of the electrical signal response of the magnetoresistive element under the fourth position difference relationship; Figure 13 This is a simulation diagram of the electrical signal response of the Z-phase signal under the fourth position difference relationship.
[0016] In the accompanying drawings: 1-magnetic sensor; 2-AB phase magnetic scale; 3-Z phase magnetic scale; 4-magnetoresistive strip; R1-first magnetoresistive element; R2-second magnetoresistive element; R3-third magnetoresistive element; R4-fourth magnetoresistive element. DETAILED DESCRIPTION
[0017] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.
[0018] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.
[0019] In the description of the present invention, "several" means an indefinite quantity, "multiple" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, and "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" is solely for the purpose of distinguishing technical features and should not be understood to indicate or imply relative importance, or to implicitly indicate the number or order of the technical features indicated. "And / or" throughout the text represents three parallel solutions. For example, "A and / or B" means a solution where A satisfies, a solution where B satisfies, or a solution where both A and B satisfy.
[0020] In the description of the present invention, if there is a short sentence containing multiple parallel features, the attributive defines the closest feature. For example, "B, C, and E are arranged on A, and are connected to D" means that B is arranged on A and E is connected to D, and does not constitute a limitation on C. However, attributives that express the relationship between features, such as "spaced arrangement" or "circular arrangement", do not fall into this category. If the word "all" is preceded by an attributive, it means that all features in the short sentence are limited. For example, "B, C, and D are all arranged on A" means that B, C, and D are all arranged on A. In a sentence with an omitted subject, the omitted subject is the subject of the previous sentence, that is, "B is arranged on A, including C" means that B is arranged on A and A includes C.
[0021] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.
[0022] The following combination Figures 1 to 13 Embodiments of the present invention are described.
[0023] This embodiment relates to the field of magnetic field measurement, in which a magnetic sensor 1 is a widely used tool for measuring angular displacement. Its core principle is to generate orthogonal signals (phases A and B) by detecting periodically arranged magnetic pole signals, and combine them with a specific Z-phase signal to indicate the origin position. However, under conditions of small magnetic pole pitch (e.g., pole pitch ≤ 0.5 mm), the design of traditional magnetic sensor 1 faces significant technical challenges, specifically the following: Diffusion of the Z-phase magnetic pole leads to blurred magnetic field distribution: The Z-phase magnetic pole easily diffuses into the unwritten magnetic area. This diffusion phenomenon causes the actual magnetic field distribution of the Z-phase magnetic pole to become irregular and the boundary to become unclear, making it difficult for the sensor to accurately distinguish the boundary between the Z-phase magnetic pole and other magnetic poles. For example, when the magnetic pole pitch is 0.4mm, the Z-phase magnetic pole may diffuse 0.1mm or more to each end, causing the magnetic pole pitch to expand from 0.4mm to 0.6mm or even larger. This diffusion phenomenon significantly affects the peak width and shape of the Z-phase signal, resulting in errors in the reading of the origin signal. Conventional designs struggle to adapt to small pole-pitch conditions: Conventional magnetic sensors 1 typically use a pair of magnetic poles (NS or SN) as the structural foundation of the Z-phase magnetic scale 3, determining the origin by detecting the boundary between the two poles. However, magnetizing the poles is difficult under small pole-pitch conditions, requiring precise control of the pole spacing and strength. They also have poor anti-interference capabilities, and due to pole diffusion or asymmetry, conventional designs are susceptible to external interference. Furthermore, their resolution is limited, making it inadequate to distinguish the boundary between the Z-phase pole and other poles. Synchronicity between the Z-phase signal and the A / B-phase signal: Under conditions of small magnetic pole pitch, the diffusion of the Z-phase magnetic pole may cause its magnetic field distribution to exceed the range of one A-phase or B-phase sinusoidal wave signal cycle. This not only increases the complexity of signal processing but may also cause the synchronization between the Z-phase signal and the A / B-phase signal to decrease, further affecting measurement accuracy.
[0024] An angular displacement measuring device in this embodiment includes: A magnetic grid having a magnetic field distribution that varies along its length; A magnetic sensor 1 is provided on the magnetic grid and slides along the length direction of the magnetic grid; The magnetic sensor 1 includes a first magnetoresistive element R1, a second magnetoresistive element R2, a third magnetoresistive element R3, and a fourth magnetoresistive element R4 electrically connected to each other; The spatial position difference between the first magnetoresistive element R1 and the third magnetoresistive element R3 is half of the magnetic pole pitch of the magnetic grid; the spatial position difference between the second magnetoresistive element R2 and the fourth magnetoresistive element R4 is half of the magnetic pole pitch of the magnetic grid; the spatial position difference between the second magnetoresistive element R2 and the third magnetoresistive element R3 is zero; and the spatial position difference between the first magnetoresistive element R1 and the fourth magnetoresistive element R4 is the magnetic pole pitch of the magnetic grid; The first magnetoresistive element R1 , the second magnetoresistive element R2 , the third magnetoresistive element R3 and the fourth magnetoresistive element R4 are used to read the origin signal of the magnetic grid according to the change of the magnetic field distribution.
[0025] In this embodiment, the first magnetoresistance element R1 and the third magnetoresistance element R3, the second magnetoresistance element R2 and the fourth magnetoresistance element R4 respectively constitute a half-pole pitch position difference layout, forming two groups of orthogonal signal detection units, and realizing the subdivision identification of the magnetic field distribution through the phase difference characteristics of their detection signals; the second magnetoresistance element R2 and the third magnetoresistance element R3 constitute a zero position difference layout, ensuring that the two synchronously sample the same magnetic field area to form a baseline reference signal for noise suppression; the first magnetoresistance element R1 and the fourth magnetoresistance element R4 constitute a one-pole pitch position difference layout, so that when sliding over the Z-phase magnetic pole area, a complete periodic response contrast is formed, thereby enhancing the ability to identify the Z-phase boundary; when the magnetic sensor 1 slides over the Z-phase magnetic pole area, each magnetoresistance element generates an electrical signal response with a clear phase relationship based on the preset spatial position difference. This phase relationship enables the magnetoresistance element array to accurately distinguish the magnetic field change characteristics of the Z-phase magnetic pole, thereby realizing stable detection of the origin signal.
[0026] Magnetic sensor 1 reads magnetic pole signals based on the AMR (anisotropic magnetoresistance) effect. As magnetic sensor 1 moves relative to the Z-phase magnetic pole on the magnetic grid, each magnetoresistive element generates an electrical signal response. Due to the spatial position difference of each magnetoresistive element, their electrical signal responses have corresponding phase differences. Refer to the conversion formula of spatial position difference and phase difference: , where λ is the magnetic pole pitch, is the phase difference, is the spatial position difference; taking the standard magnetic pole pitch (λ) as an example, that is, when the Z-phase magnetic pole pitch is λ, the phase difference characteristics between the magnetoresistive elements are as follows: The phase difference of the electrical signal responses of the first magnetoresistive element R1 and the third magnetoresistive element R3 is π; The phase difference of the electrical signal response between the second magnetoresistive element R2 and the fourth magnetoresistive element R4 is π; The phase difference of the electrical signal responses of the second magnetoresistive element R2 and the third magnetoresistive element R3 is 0; The phase difference between the electrical signal responses of the first magnetoresistive element R1 and the fourth magnetoresistive element R4 is 2π; Taking the pole pitch (1.5λ) in the case of pole diffusion as an example, assuming that the Z-phase magnetic pole diffuses by 0.25λ to both ends, that is, the Z-phase magnetic pole pitch is 1.5λ, the phase difference characteristics between the magnetoresistive elements are as follows: The phase difference between the electrical signal responses of the first magnetoresistive element R1 and the third magnetoresistive element R3 is 2π / 3; The phase difference of the electrical signal response between the second magnetoresistive element R2 and the fourth magnetoresistive element R4 is 2π / 3; The phase difference of the electrical signal responses of the second magnetoresistive element R2 and the third magnetoresistive element R3 is 0; The phase difference of the electrical signal response between the first magnetoresistive element R1 and the fourth magnetoresistive element R4 is 4π / 3; See also Figure 4 and Figure 5 , Figure 4 The simulation of the electrical signal response of the magnetoresistive element at different positions is given; Figure 5 The electrical signal response simulation of Z-phase positive signal (Z+), Z-phase negative signal (Z-) and Z-phase signal at different positions is given; Figure 5 The electrical signal response simulation of the Z+, Z- and Z-phase signals at different positions is given. Among them, R1, R2, R3 and R4 are the resistance values of the first magnetoresistive element R1, the second magnetoresistive element R2, the third magnetoresistive element R3 and the fourth magnetoresistive element R4 respectively. is the Z phase positive signal (Z+), is the Z phase negative signal (Z-), is the Z phase signal, then: ; ; ; Depend on Figure 5 It can be seen that regardless of whether the Z-phase magnetic pole is diffused (i.e., when the magnetic pole pitch is λ and 1.5λ), the origin position of the Z-phase signal read by the angular displacement sensor remains unchanged; when the magnetic pole pitch is λ, the peak width of the Z-phase signal is λ, which is completely within one cycle of the A-phase and B-phase sinusoidal wave signals; when the magnetic pole pitch is 1.5λ, the peak width of the Z-phase signal is 1.5λ, but most of its signal peaks are still within one cycle of the A-phase and B-phase sinusoidal wave signals. This test result shows that based on the phase difference design of the magnetoresistive element in the magnetic sensor 1 of the present application, accurate reading of the Z-phase signal can be achieved.
[0027] The magnetic sensor 1 in the above embodiment is used to read the magnetic signal of the magnetic grid with a magnetic pole pitch λ of 0.4 mm. The test results of the A, B, and Z phase signals are as follows: Figure 6 As shown; further convert the time axis into a displacement axis and zoom in, as shown Figure 7 shown; according to Figure 6 and Figure 7 , it can be seen that the Z-phase signal peak of the magnetic sensor 1 prepared in the embodiment is completely within one cycle of the A-phase or B-phase sinusoidal wave signal; It can be seen that the magnetic sensor 1 proposed in the present invention can accurately read the magnetic signal of the Z-phase magnetic pole composed of only a single-sided magnetic pole under the condition of λ ≤ 0.5 mm. Even when the Z-phase magnetic pole is diffused and widened (for example, the magnetic pole pitch is 1.5λ), it can still accurately read the origin signal, ensuring that the peak width of the Z-phase signal is as close as possible to within one cycle of the A-phase and B-phase sinusoidal wave signals.
[0028] In the actual Z-phase signal processing process, we can first build an amplification circuit through a high-gain, low-noise operational amplifier, and reasonably design the feedback resistor network to amplify the amplitude of the weak Z-phase signal to meet the subsequent processing requirements.
[0029] Specifically, the first magnetoresistance element and the third magnetoresistance element have the same size, and have the same positional relationship in the direction perpendicular to the magnetic field distribution, and the spatial position difference in the direction parallel to the magnetic field distribution is half of the magnetic pole pitch of the magnetic grid; the second magnetoresistance element and the fourth magnetoresistance element have the same size, and have the same positional relationship in the direction perpendicular to the magnetic field distribution, and the spatial position difference in the direction parallel to the magnetic field distribution is half of the magnetic pole pitch of the magnetic grid.
[0030] In this embodiment, refer to Figure 2 , Figure 2As shown in the figure, the first magnetoresistance element R1 and the third magnetoresistance element R3 have the same size and are positioned in the same direction perpendicular to the magnetic field distribution direction (i.e., the y direction in the figure), and the second magnetoresistance element R2 and the fourth magnetoresistance element R4 have the same size and are positioned in the y direction. This layout design ensures the balance and phase accuracy of the bridge arms between the first magnetoresistance element R1 and the third magnetoresistance element R3, and between the second magnetoresistance element R2 and the fourth magnetoresistance element R4, and can effectively offset errors and improve measurement accuracy even in the presence of external interference or temperature changes.
[0031] Specifically, the magnetic sensor 1 also includes a substrate and at least four electrodes; the first magnetoresistance element R1, the second magnetoresistance element R2, the third magnetoresistance element R3, the fourth magnetoresistance element R4 and the electrodes are arranged on the substrate; the first magnetoresistance element R1, the second magnetoresistance element R2, the third magnetoresistance element R3, the fourth magnetoresistance element R4 and the electrodes together constitute a differential circuit; the differential circuit is used to receive electrical signals from the magnetoresistance elements and output differential signals.
[0032] In this embodiment, the array of magnetoresistive elements (i.e., the first magnetoresistive element R1, the second magnetoresistive element R2, the third magnetoresistive element R3, and the fourth magnetoresistive element R4) and the electrodes are all processed and formed on the same substrate; a permalloy (Ni81Fe19) thin film material is sputter-deposited on the substrate using magnetron sputtering; a metal thin film material with excellent conductive properties (such as Au, Ag, Cu, etc.) is then deposited, and the circuit and electrode patterns are photoetched; the magnetoresistive elements and electrodes are integrated on the same substrate, which simplifies the manufacturing process and improves system reliability; the differential circuit composed of the magnetoresistive elements and electrodes reads the magnetic field signal based on the AMR effect, and the differential signal output by the circuit can effectively suppress common-mode interference, improve the anti-interference capability of the system, and ensure the stability of the measurement results.
[0033] Specifically, the differential circuit is a Wheatstone bridge circuit; the first magnetoresistance element R1 , the second magnetoresistance element R2 , the third magnetoresistance element R3 , and the fourth magnetoresistance element R4 respectively constitute four bridge arms of the Wheatstone bridge circuit.
[0034] In this embodiment, the differential circuit is a Wheatstone bridge circuit, which is composed of four magnetoresistive elements (a first magnetoresistive element R1, a second magnetoresistive element R2, a third magnetoresistive element R3, and a fourth magnetoresistive element R4) forming four bridge arms respectively. Since the first magnetoresistive element R1, the second magnetoresistive element R2, the third magnetoresistive element R3, and the fourth magnetoresistive element R4 have phase difference characteristics, when the external magnetic field changes, the resistance value of each magnetoresistive element changes accordingly, causing the voltage difference at the output end of the bridge to change, thereby generating a stable differential signal. This change is further amplified and processed, and ultimately used to read the origin signal of the magnetic grid. The design of the Wheatstone bridge circuit fully utilizes the resistance change characteristics of the magnetoresistive elements, thereby achieving high-precision signal detection.
[0035] Specifically, the electrodes include a Z-phase positive electrode, a Z-phase negative electrode, a power supply electrode and a ground electrode; the Z-phase positive electrode is connected to the first magnetoresistance element R1 and the third magnetoresistance element R3; the Z-phase negative electrode is connected to the second magnetoresistance element R2 and the fourth magnetoresistance element R4; the power supply electrode is connected to the first magnetoresistance element R1 and the second magnetoresistance element R2; and the ground electrode is connected to the third magnetoresistance element R3 and the fourth magnetoresistance element R4.
[0036] In this embodiment, refer to Figure 2 , the Z-phase positive electrode (Z+) is connected to the connection node of the first magnetoresistance element R1 and the third magnetoresistance element R3; the Z-phase negative electrode (Z-) is connected to the connection node of the second magnetoresistance element R2 and the fourth magnetoresistance element R4; the power supply electrode (Vcc) is connected to the input terminals of the first magnetoresistance element R1 and the second magnetoresistance element R2; the ground electrode (Gnd) is connected to the input terminals of the third magnetoresistance element R3 and the fourth magnetoresistance element R4; The Z-phase positive electrode and the Z-phase negative electrode respectively collect the differential signals (Z+ and Z-) at the output end of the bridge for further processing and calculation of the origin signal; the power electrode (Vcc) and the ground electrode (Gnd) provide power to the circuit to ensure the normal operation of the Wheatstone bridge circuit.
[0037] Specifically, the first magnetoresistance element R1 , the second magnetoresistance element R2 , the third magnetoresistance element R3 and the fourth magnetoresistance element R4 each include a plurality of magnetoresistance strips 4 connected in series; the width of each magnetoresistance strip 4 is consistent, and the total length of each magnetoresistance strip 4 after being connected in series is consistent.
[0038] In this embodiment, each magnetoresistive element is composed of several magnetoresistive strips 4 connected in series. This design ensures that the zero-field resistance of each magnetoresistive element is consistent, thereby improving the balance of the Wheatstone bridge circuit; the width of each magnetoresistive strip 4 is consistent, ranging from 5 to 20 μm, the length of an individual magnetoresistive strip 4 is 120 to 400 μm, and the total length of the magnetoresistive strips 4 connected in series is consistent, ranging from 1000 to 2400 μm; the consistency of the size of the magnetoresistive strips 4 ensures that the electrical signal response characteristics of the magnetoresistive elements are consistent under the same external magnetic field conditions, avoiding measurement errors caused by size differences.
[0039] Specifically, the magnetoresistive strip 4 has an easy magnetization characteristic along its long axis direction, and when the direction of the external magnetic field is perpendicular to the long axis direction of the magnetoresistive strip 4 , the resistivity change value of the magnetoresistive strip 4 reaches a maximum.
[0040] In this embodiment, the easy magnetization axis of the magnetoresistive strip 4 is arranged along its long axis. This is determined by the physical properties of AMR materials such as Permalloy (Ni81Fe19). When the external magnetic field is parallel to the in-plane and perpendicular to the long axis of the magnetoresistive strip 4, the electron scattering effect inside the magnetoresistive strip 4 is most significant, causing the resistivity change to reach a maximum value, thereby maximizing the electrical signal response amplitude of the magnetoresistive element. The easy magnetization axis design of the magnetoresistive strip 4 fully utilizes the AMR effect, achieving high-resolution detection of the magnetic field distribution, ensuring the stable response of the magnetoresistive strip 4 to magnetic field changes, and avoiding measurement errors caused by deviations in the magnetic field direction.
[0041] Specifically, the magnetoresistive strips 4 of the second magnetoresistive element R2 and the third magnetoresistive element R3 are nested with each other.
[0042] In this embodiment, see Figure 2 The magnetoresistive strips 4 of the second magnetoresistive element R2 and the third magnetoresistive element R3 are nested with each other. The nested design makes the magnetoresistive strips 4 of the second magnetoresistive element R2 and the third magnetoresistive element R3 staggered in space, but maintain the same easy magnetization axis direction and size characteristics, ensuring that the phases of the electrical signal changes of the two are consistent, thereby ensuring that the responses of the second magnetoresistive element R2 and the third magnetoresistive element R3 in the same magnetic field area are more consistent, thereby enhancing the noise suppression capability.
[0043] Specifically, the magnetic grid includes an AB phase magnetic scale 2 and a Z phase magnetic scale 3 ; the AB phase magnetic scale 2 and the Z phase magnetic scale 3 are arranged opposite to each other.
[0044] Specifically, the AB phase magnetic scale 2 has multiple magnets arranged along its length direction, and the pole directions of adjacent magnets are arranged alternately. The N pole and S pole of each magnet are respectively located at the two ends of the width direction of the AB phase magnetic scale 2, and the multiple magnets form a periodically arranged magnetic pole array; the Z phase magnetic scale 3 has a magnet, and the N pole and S pole of the magnet are respectively located at the two ends of the width direction of the Z phase magnetic scale 3.
[0045] In this embodiment, see Figure 3 The AB-phase magnetic scale 2 has multiple magnets arranged along its length, with the poles of adjacent magnets arranged in an alternating pattern (NSNS...), forming a periodic array of magnetic poles. This periodic array of magnetic poles generates a sinusoidal signal for detecting changes in angular displacement. The Z-phase magnetic scale 3 has a magnet with either its north or south pole facing the magnetic sensor 1, providing a single magnet signal for determining the origin position. When the north pole faces the magnetic sensor 1, the north pole is used as the Z phase; when the south pole faces the magnetic sensor 1, the south pole is used as the Z phase. Conventional solutions typically use a pair of magnetic poles (NS or SN) on the Z-phase magnetic scale 3 to determine the origin position by detecting the boundary between the two poles. However, this design is only suitable for magnetic sensors 1 with a large pole pitch (pole pitch ≥ 2 mm). When the pole pitch is reduced, such as the pole pitch of less than 0.5 nm involved in this embodiment, the following difficulties arise: Magnetization technology is demanding, requiring precise control of the magnetic pole spacing and strength. It is easily affected by external interference (such as temperature changes and electromagnetic noise), resulting in measurement errors. Pole diffusion or asymmetry may cause the origin signal to drift. Therefore, the technical solution of precisely magnetizing a pair of magnetic poles requires high requirements for magnetization technology and manufacturing processes, is easily affected by external interference, and it is difficult to ensure accurate reading of the origin (Z phase) signal. The Z-phase magnetic scale 3 design provided in this embodiment utilizes only one magnetic pole (N or S) to detect the origin signal. Its core principle is based on the AMR (anisotropic magnetoresistance) effect, which states that magnetoresistive elements can respond with high sensitivity to changes in magnetic field distribution. By properly setting the spatial position difference of the magnetoresistive elements, when the magnetic sensor 1 slides over the Z-phase magnetic pole region, each magnetoresistive element generates an electrical signal response with a clear phase relationship based on the preset spatial position difference. This phase relationship enables the magnetoresistive element array to accurately distinguish the magnetic field variation characteristics of the Z-phase magnetic pole. Further processing of these electrical signal responses generates stable Z+ and Z- differential signals, thereby achieving accurate detection of the origin signal. In this embodiment, the design of using a single magnetic pole to complete the Z-phase signal reading reduces the error caused by magnetic pole asymmetry or uneven magnetization. Only a single magnetic pole (N pole or S pole) on the Z-phase magnetic scale 3 can be used to detect the origin signal, which improves the accuracy and reliability of Z-phase signal detection and significantly reduces the magnetization difficulty and manufacturing cost of the Z-phase magnetic scale 3.
[0046] See also Figures 8 to 13 , Figures 8 to 13 The simulation of the Z-phase reading signal of the magnetoresistive elements based on other phase difference arrangements is shown; When the spatial position difference between the first magnetoresistance element R1 and the third magnetoresistance element R3 is λ / 4, the spatial position difference between the second magnetoresistance element R2 and the fourth magnetoresistance element R4 is λ / 4, the spatial position difference between the second magnetoresistance element R2 and the third magnetoresistance element R3 is 0, the spatial position difference between the first magnetoresistance element R1 and the fourth magnetoresistance element R4 is λ / 2, and the Z-phase magnetic pole pitch is λ, the electrical signal change is simulated as follows Figure 8 and Figure 9 shown by Figure 8 and Figure 9 It can be seen that although this phase difference design can read the Z-phase origin signal, the signal amplitude is weak, which is not conducive to subsequent circuit signal processing; When the spatial position difference between the first magnetoresistance element R1 and the third magnetoresistance element R3 is λ, the spatial position difference between the second magnetoresistance element R2 and the fourth magnetoresistance element R4 is λ, the spatial position difference between the second magnetoresistance element R2 and the third magnetoresistance element R3 is 0, the spatial position difference between the first magnetoresistance element R1 and the fourth magnetoresistance element R4 is 2λ, and the Z-phase magnetic pole pitch is λ, the electrical signal change is simulated as follows Figure 10 and Figure 11 shown by Figure 10 and Figure 11 It can be seen that this design cannot read the origin signal when the Z-phase magnetic pole is unipolar; When the spatial position difference between the first magnetoresistive element R1 and the third magnetoresistive element R3 is 3λ / 2, the spatial position difference between the second magnetoresistive element R2 and the fourth magnetoresistive element R4 is 3λ / 2, the spatial position difference between the second magnetoresistive element R2 and the third magnetoresistive element R3 is λ, and the spatial position difference between the first magnetoresistive element R1 and the fourth magnetoresistive element R4 is 2λ, the electrical signal changes are simulated as follows: Figure 12 and Figure 13 shown by Figure 12 and Figure 13 It can be seen that this design can read the Z-phase origin signal when the magnetic pole pitch is λ, but if the Z-phase magnetic pole pitch spread is 1.5λ, this design cannot read the origin signal.
[0047] According to the above arrangement scheme, for the case where a single magnetic pole is used in the Z phase and the Z phase magnetic scale 3 adopts a single magnetic pole design, the spatial position difference and phase difference design of the magnetoresistive element in the present invention is unique and necessary, and is the key technical guarantee for achieving stable and accurate reading of the Z phase origin signal.
[0048] The above specifically describes the preferred embodiments of the present invention, but the present disclosure is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present disclosure.
Claims
1. An angular displacement measuring device, characterized in that: include: A magnetic grid having a magnetic field distribution that varies along its length; a magnetic sensor, which is arranged on the magnetic grid and slides along the length direction of the magnetic grid; The magnetic sensor includes a first magnetoresistive element, a second magnetoresistive element, a third magnetoresistive element, and a fourth magnetoresistive element electrically connected to each other; The spatial position difference between the first magnetoresistive element and the third magnetoresistive element is half of the magnetic pole pitch of the magnetic grid; the spatial position difference between the second magnetoresistive element and the fourth magnetoresistive element is half of the magnetic pole pitch of the magnetic grid; the spatial position difference between the second magnetoresistive element and the third magnetoresistive element is zero; and the spatial position difference between the first magnetoresistive element and the fourth magnetoresistive element is the magnetic pole pitch of the magnetic grid; The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element are used to read the origin signal of the magnetic grid according to the change of the magnetic field distribution.
2. The angular displacement measuring device according to claim 1, characterized in that: The first magnetoresistance element and the third magnetoresistance element have the same size, and have the same positional relationship in the direction perpendicular to the magnetic field distribution, and the spatial position difference in the direction parallel to the magnetic field distribution is half of the magnetic pole pitch of the magnetic grid; the second magnetoresistance element and the fourth magnetoresistance element have the same size, and have the same positional relationship in the direction perpendicular to the magnetic field distribution, and the spatial position difference in the direction parallel to the magnetic field distribution is half of the magnetic pole pitch of the magnetic grid.
3. The angular displacement measuring device according to claim 1, wherein: The magnetic sensor further includes a substrate and at least four electrodes; the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, the fourth magnetoresistive element, and the electrodes are disposed on the substrate; the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, the fourth magnetoresistive element, and the electrodes together constitute a differential circuit; The differential circuit is used to receive an electrical signal from a magnetoresistive element and output a differential signal.
4. The angular displacement measuring device according to claim 3, characterized in that: The differential circuit is a Wheatstone bridge circuit; the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element respectively constitute four bridge arms of the Wheatstone bridge circuit.
5. The angular displacement measuring device according to claim 3, characterized in that: The electrodes include a Z-phase positive electrode, a Z-phase negative electrode, a power supply electrode and a ground electrode; the Z-phase positive electrode is connected to the first magnetoresistance element and the third magnetoresistance element; the Z-phase negative electrode is connected to the second magnetoresistance element and the fourth magnetoresistance element; the power supply electrode is connected to the first magnetoresistance element and the second magnetoresistance element; and the ground electrode is connected to the third magnetoresistance element and the fourth magnetoresistance element.
6. The angular displacement measuring device according to claim 1, wherein: The first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element and the fourth magnetoresistive element each include a plurality of magnetoresistive strips connected in series; the width of each magnetoresistive strip is consistent, and the total length of each magnetoresistive strip connected in series is consistent.
7. The angular displacement measuring device according to claim 6, characterized in that: The magnetoresistive strip has an easy magnetization characteristic along its long axis direction, and when the direction of the external magnetic field is perpendicular to the long axis direction of the magnetoresistive strip, the resistivity change value of the magnetoresistive strip reaches a maximum.
8. The angular displacement measuring device according to claim 6, characterized in that: The magnetoresistive strips of the second magnetoresistive element and the third magnetoresistive element are nested with each other.
9. The angular displacement measuring device according to claim 1, wherein: The magnetic grid includes an AB phase magnetic scale and a Z phase magnetic scale; the AB phase magnetic scale and the Z phase magnetic scale are arranged opposite to each other.
10. The angular displacement measuring device according to claim 9, characterized in that: The AB phase magnetic scale has a plurality of magnets arranged along its length, with the poles of adjacent magnets arranged alternately, and the N pole and S pole of each magnet are respectively located at the two ends of the width direction of the AB phase magnetic scale, and the plurality of magnets form a periodically arranged magnetic pole array; The Z-phase magnetic scale has a magnet, and the N pole and S pole of the magnet are respectively located at two ends of the Z-phase magnetic scale in the width direction.