Bimodal magnetoelastic sensor and digital writing input device

Abstract

This invention discloses a dual-modal magnetoelastic sensor and a digital writing input device. The sensor incorporates an elastic micropillar and an elastic base on a single-piece elastic substrate. The micropillar is magnetized to form a directional and stable intrinsic magnetic moment. On one hand, when the micropillar deforms under external force, its spatial magnetic field distribution changes, inducing a current in the induction coil below. On the other hand, when the micropillar deforms under external force, the resistance-sensitive structure on the elastic base is stretched or compressed, resulting in a change in resistance. Therefore, this invention can simultaneously respond to normal pressure and shear force on a single elastic structure, triggering changes in magnetic field and resistance to achieve dual-modal sensing. This improves the sensor's integration and allows for more accurate sensing and differentiation of mechanical signals in different dimensions without the need for complex decoupling algorithms.

Description

Technical Field

[0001] This invention belongs to the field of sensor and digital writing technology, and particularly relates to a dual-modal magnetoelastic sensor and a digital writing input device. Background Technology

[0002] With the rapid development of digital writing and human-computer interaction technologies, digital writing pens have gradually evolved from simple coordinate input tools to multimodal interactive terminals. They have been widely used in various application scenarios such as digital painting, smart education, remote collaboration, and immersive interaction, and the market's demand for more refined perception of writing behavior is also constantly increasing.

[0003] From the perspective of the mechanical characteristics of actual writing, the writing process is a typical multi-dimensional coupling process. The force applied by the writer at the pen tip not only includes the normal pressure perpendicular to the writing surface, but also includes shear force components that change in multiple directions. The magnitude, direction and rate of change of these forces change in real time with the writing trajectory. This kind of multi-dimensional mechanical information directly determines the thickness of the strokes, the shape of the beginning and ending strokes, and the overall writing style, which is the key to realizing the restoration of the real writing experience.

[0004] However, the sensing mechanisms of existing mainstream digital writing pens still rely heavily on touch screen arrays or single pressure sensing units. Existing sensors have limited information dimensions and can only roughly sense normal pressure, unable to distinguish shear forces in all directions. This results in a significant difference between digital writing and real writing experiences, making it difficult to meet the needs of refined writing perception.

[0005] To address the aforementioned issue of insufficient multidimensional mechanical information sensing, some existing technologies attempt to achieve multidirectional sensing by integrating multiple strain gauges, capacitive sensors, or force-sensitive resistors within the pen tip. However, these solutions suffer from several drawbacks: First, they require complex sensor array layouts, which not only complicate the pen tip structure but also hinders compact design due to the miniaturization requirements of digital writing pens. Second, signal coupling easily occurs between different sensing channels, necessitating complex decoupling algorithms for post-processing. This "coupling first, then decoupling" approach not only increases system power consumption and computational burden but also affects system real-time performance and stability. Third, traditional sensors based on resistance or capacitance changes are prone to signal drift or sensitivity degradation under prolonged repeated loading, changes in environmental humidity, or significant variations in writing posture, failing to meet the high reliability and stability requirements of digital writing pens.

[0006] In summary, existing digital writing pens and digital writing input devices struggle to acquire multi-dimensional mechanical information during the writing process and suffer from problems such as complex sensing structures, severe signal coupling, insufficient stability, and limitations in miniaturization. These issues fail to meet the demands for refined and highly reliable writing perception. Therefore, developing a sensor structure that can achieve self-decoupling of multi-dimensional mechanical sensing signals at the structural level, while also possessing good stability and environmental adaptability, has become a pressing technical problem in this field. Summary of the Invention

[0007] The purpose of this invention is to provide a sensor structure that can achieve self-decoupling of multidimensional mechanical sensing signals at the structural level, while also possessing good stability and environmental adaptability.

[0008] To achieve the objectives of this invention, the following technical solution is adopted:

[0009] A dual-mode magnetoelastic sensor includes an elastic matrix, which is integrally formed by blending and curing an elastic material with magnetic particles, and the elastic matrix includes an elastic base and elastic micropillars erected on the elastic base.

[0010] The elastic micro-pillar forms a directional and stable intrinsic magnetic moment after being magnetized; an induction coil is arranged below the elastic base to generate an induced current when the elastic micro-pillar is deformed by an external force, causing the spatial magnetic field distribution to change accordingly.

[0011] The elastic base is provided with a resistance-sensitive structure, which is used to generate a change in resistance when the elastic micro-column is deformed by an external force and the resistance-sensitive structure is stretched or compressed.

[0012] The induced current generated by the induction coil serves as the first mode sensing output; the resistance value of the resistance-sensitive structure serves as the second mode sensing output.

[0013] According to a specific embodiment, in the dual-mode magnetoelastic sensor provided by the present invention, the resistance-sensitive structure is a conductive layer formed by conductive particles sprayed on the surface of the elastic base, and when the conductive layer is stretched or compressed and deformed, the change in its internal conductive path causes a change in the conduction resistance.

[0014] According to a specific embodiment, in the dual-modal magnetoelastic sensor provided by the present invention, a strain concentration microstructure is provided on the elastic base near the root of the elastic micropillar, and the strain concentration microstructure is located below the conductive layer; when the elastic micropillar is deformed by an external force, the strain concentration effect generated by the strain concentration microstructure is transmitted to the conductive layer, causing the conductive layer to be stretched or compressed and deformed.

[0015] According to one specific embodiment, in the dual-modal magnetoelastic sensor provided by the present invention, the strain concentration microstructure is a V-shaped microgroove formed on the surface of the elastic base, and the conductive layer is attached to the inner surface of the V-shaped microgroove.

[0016] According to one specific embodiment, in the dual-modal magnetoelastic sensor provided by the present invention, the elastic base is L-shaped, and the elastic micro-pillar is disposed at the L-shaped bend of the elastic base.

[0017] According to one specific embodiment, in the dual-mode magnetoelastic sensor provided by the present invention, the conductive layer extends to the ends of the two straight edges of the elastic base and is electrically connected to electrodes disposed at the ends of the two straight edges of the elastic base.

[0018] According to one specific embodiment, in the dual-modal magnetoelastic sensor provided by the present invention, the elastic material is polydimethylsiloxane, the magnetic particles are neodymium iron boron powder, and the conductive particles are carbon black particles.

[0019] Based on the same inventive concept, the present invention also provides a digital writing input device, which includes:

[0020] Pen tip structure;

[0021] At least one dual-mode magnetoelastic sensor provided by the present invention, wherein the elastic micropillar of the dual-mode magnetoelastic sensor abuts against the pen tip structure, for sensing the force applied to the pen tip structure by the writer during writing;

[0022] The resistance detection unit is used to generate a corresponding resistance detection current signal based on the on-resistance of each of the dual-mode magnetoelastic sensors.

[0023] The signal acquisition unit is used to synchronously acquire the induced current signal and the resistance detection current signal of each of the dual-mode magnetoelastic sensors, amplify the acquired induced current signal and the resistance detection current signal, convert the amplified induced current signal and the resistance detection current signal into induced voltage signal and resistance detection voltage signal respectively, and perform analog-to-digital conversion on the induced voltage signal and the resistance detection voltage signal to obtain induced voltage data and resistance detection voltage data.

[0024] The writing result recognition unit is used to perform time series analysis on the induced voltage data and the resistance detection voltage data, extract multi-dimensional feature information, and recognize the writing result based on the multi-dimensional feature information; the writing result includes writing direction and writing force.

[0025] According to a specific embodiment, in the digital writing input device provided by the present invention, the writing result recognition unit is preset with a trained convolutional neural network. The convolutional neural network is configured to: perform convolutional feature extraction on the input multidimensional feature information to obtain a multidimensional feature vector, and then perform fusion processing on the multidimensional feature vector to output the writing direction corresponding to the writing result.

[0026] According to one specific embodiment, the digital writing input device provided by the present invention further includes: a writing result transmission unit, used to transmit the writing result to a digital writing presentation device.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. The dual-mode magnetoelastic sensor provided by this invention features an elastic micropillar and an elastic base designed on a single-piece elastic substrate. The elastic micropillar, after magnetization, forms a directional and stable intrinsic magnetic moment. On one hand, when the elastic micropillar deforms under external force, its spatial magnetic field distribution changes, causing an induced current to be generated in the induction coil below. This induced current is then used as the first sensing mode output. On the other hand, when the elastic micropillar deforms under external force, the resistance-sensitive structure on the elastic base is stretched or compressed, resulting in a change in resistance. The resistance value of this resistance-sensitive structure is used as the second sensing mode output. Therefore, this invention can simultaneously respond to normal pressure and shear force on a single elastic structure, jointly triggering changes in magnetic field and resistance to achieve dual-mode sensing, thus improving the sensor's integration.

[0029] At the structural level, the deformation of the elastic micro-pillar under external force forms the first mode of sensing output through the induced current. The resistance-sensitive structure undergoes tensile or compressive deformation under the influence of the elastic micro-pillar deformation, forming the second mode of sensing output through its resistance value. This makes the dual-mode sensing mechanism independent yet cooperative. Therefore, the dual-mode magnetoelastic sensor provided by this invention can effectively achieve self-decoupling of sensing signals at the structural level, and can more accurately sense and distinguish mechanical signals of different dimensions without the need for complex decoupling algorithms.

[0030] 2. The dual-mode magnetoelastic sensor provided by the present invention designs the resistance-sensitive structure as a conductive layer formed by conductive particles sprayed on the surface of an elastic base, and sets a strain concentration microstructure on the elastic base. The strain concentration microstructure generates a strain concentration effect, enabling the conductive layer to obtain a significant resistance change rate (ΔR / R0), thereby greatly improving the sensor's sensitivity to shear force response in various directions.

[0031] 3. The digital writing input device provided by this invention, by employing the dual-modal magnetoelastic sensor provided by this invention as the mechanical sensor for the pen tip structure, facilitates the miniaturization of the digital writing input device. Furthermore, because this dual-modal magnetoelastic sensor can effectively achieve self-decoupling of the sensing signal at the structural level, it can more accurately sense and distinguish mechanical signals of different dimensions without the need for complex decoupling algorithms. Thus, this invention can achieve mechanical sensing of normal pressure and shear force in various directions within a single pen tip structure, significantly reducing the system's structural complexity and signal processing burden. Simultaneously, because the magnetic induction signal is insensitive to environmental humidity and contact medium, it exhibits good stability and environmental adaptability, effectively improving the reliability of the digital writing input device in complex application scenarios. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the dual-modal magnetoelastic sensor provided by the present invention;

[0033] Figure 2 This is an enlarged schematic diagram of the conductive trench structure in the dual-modal magnetoelastic sensor provided by the present invention;

[0034] Figure 3 A schematic diagram of the structure of the digital writing input device provided by the present invention;

[0035] Figure 4 This is a schematic diagram of the signal response of the dual-mode magnetoelastic sensor provided by the present invention under different writing directions. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] refer to Figure 1 The dual-modal magnetoelastic sensor 10 provided by the present invention, shown herein, includes:

[0038] The elastic matrix 100 is integrally formed by blending and curing elastic materials and magnetic particles, and the elastic matrix 100 includes an elastic base 101 and elastic micropillars 102 erected on the elastic base 101.

[0039] After being magnetized, the elastic micro-pillar 102 forms a directional and stable intrinsic magnetic moment; an induction coil 200 is arranged below the elastic base 101 to generate an induced current when the elastic micro-pillar 102 is deformed by an external force and its spatial magnetic field distribution changes accordingly.

[0040] The elastic base 101 is provided with a resistance-sensitive structure 103, which is used to generate a change in resistance when the elastic micro-pillar 102 is deformed by an external force and the resistance-sensitive structure is stretched or compressed.

[0041] In the dual-mode magnetoelastic sensor 10 provided by the present invention, the induced current generated by the induction coil 200 is used as the first mode sensing output; the resistance value of the resistance-sensitive structure 103 is used as the second mode sensing output.

[0042] The dual-mode magnetoelastic sensor provided by this invention features an elastic micropillar and an elastic base designed on a single-piece elastic substrate. The elastic micropillar is magnetized to form a directional and stable intrinsic magnetic moment. On one hand, when the elastic micropillar deforms under external force, its spatial magnetic field distribution changes, inducing a current in the induction coil below. This induced current is used as the first sensing mode output. On the other hand, when the elastic micropillar deforms under external force, the resistance-sensitive structure on the elastic base is stretched or compressed, resulting in a change in resistance. The resistance value of this resistance-sensitive structure is used as the second sensing mode output. This invention enables simultaneous response to normal pressure and shear force on a single elastic structure, triggering both magnetic field and resistance changes to achieve dual-mode sensing, thus improving the sensor's integration.

[0043] Meanwhile, at the structural level, the deformation of the elastic micro-pillar under external force forms the first mode of sensing output through the induced current, and the resistance-sensitive structure undergoes tensile or compressive deformation under the influence of the elastic micro-pillar deformation, forming the second mode of sensing output through its resistance value. This makes the dual-mode sensing mechanism independent yet cooperative. Therefore, the dual-mode magnetoelastic sensor provided by this invention can effectively achieve self-decoupling of sensing signals at the structural level, and can more accurately sense and distinguish mechanical signals of different dimensions without the need for complex decoupling algorithms.

[0044] In one specific embodiment, the elastic matrix 100 is integrally molded by co-curing the elastic material and magnetic particles: first, the elastic material (such as polydimethylsiloxane PDMS) and magnetic particles (such as neodymium iron boron powder) are thoroughly mixed in a predetermined ratio; then, the mixed matrix is ​​poured into a specially made mold and cured by heating to obtain the elastic matrix 100. Taking polydimethylsiloxane as the elastic material and neodymium iron boron powder as the magnetic particles as an example, the mass ratio of the flexible material to the magnetic particles is 100:50 to 100.

[0045] After the elastic matrix 100 is prepared, it is placed in a magnetizer and directionally magnetized under a transient high-voltage magnetic field, so that the magnetic particles inside the elastic micropillar 102 acquire stable remanence and magnetic moment direction. The magnetic field strength for directional magnetization is 1T to 5T, and the angle between the magnetization direction and the micropillar axis is 30° to 90°. Preferably, in the elastic matrix 100 prepared by a specific mold, the elastic micropillar 102 is cylindrical, which can ensure uniform stress in all directions, and can be freely bent, tilted, and torsional deformed with external force, without rigid structural stress concentration dead angles, and adaptable to complex angular deformation and irregular external forces.

[0046] Therefore, the dual-mode magnetoelastic sensor provided by the present invention can highly concentrate the surrounding magnetic field on the elastic micro-cylinder 102 by performing directional magnetization treatment on the elastic micro-cylinder 102. When the elastic micro-cylinder 102 is tilted or bent by external force, its magnetic field distribution changes drastically with displacement or deformation, thereby significantly improving the generation efficiency of induced current. At the same time, since the elastic micro-cylinder 102 is tilted or bent by external force, the position and orientation of its internal magnetic particles change, resulting in the reconstruction of the surrounding magnetic field distribution directly related to the deformation direction. This causes the magnetic flux in the area surrounded by the induction coil to change, thereby generating an induced current signal in the induction coil. The amplitude of the induced current signal is related to the amplitude of the magnetic flux change, and the polarity of the induced current signal is related to the direction of the magnetic flux change. That is, the induced current signal, as the sensing output of the sensor, can accurately characterize the motion vector characteristics of the elastic micro-cylinder when subjected to external force.

[0047] In one specific embodiment, the dual-mode magnetoelastic sensor provided by the present invention provides a resistance-sensitive structure 103 on the elastic base 101. Since the elastic base 101 and the elastic micro-pillar 102 are integrally formed, when the elastic micro-pillar 102 is deformed by external force, its root is transmitted to the elastic base 101 through stress, and further transmitted to the resistance-sensitive structure 103 on the elastic base 101, causing the resistance-sensitive structure 103 to be deformed by stretching or compression, resulting in a change in resistance.

[0048] In some alternative embodiments, the resistance-sensitive structure 103 may be a strain gauge-type resistance-sensitive structure made of metal material into a specific shape by photolithography, etching or other processes, or a resistance-sensitive structure made by utilizing the piezoresistive effect of semiconductor material, or a thin film-type resistance-sensitive structure made of materials such as carbon nanoparticles, carbon nanotubes and graphene-based materials.

[0049] Considering that the process of forming a strain gauge-type resistance-sensitive structure of metal material into a specific shape through photolithography, etching and other processes, or the resistance-sensitive structure made by using the piezoresistive effect of semiconductor material, is complex and the stress transmission effect by the elastic base is not good; therefore, in this embodiment, the resistance-sensitive structure 103 is a conductive layer formed on the surface of the elastic base by spraying conductive particles, and when the conductive layer is deformed by stretching or compression, the change in its internal conductive path causes the conduction resistance to change; preferably, the conductive particles are carbon black particles (CBNPs) with a particle size of 10nm to 100nm, of course, those skilled in the art should know that carbon nanoparticles, carbon nanotubes and graphene-based materials can be used instead.

[0050] In one specific embodiment, in order to improve the sensitivity of the resistance-sensitive structure 103 to shear force response, a strain-concentrating microstructure 104 is provided on the elastic base 101 near the root of the elastic micro-pillar 102, and the strain-concentrating microstructure 104 is located below the conductive layer (i.e., the resistance-sensitive structure 103); when the elastic micro-pillar 102 is deformed by external force, the strain concentration effect generated by the strain-concentrating microstructure 104 is transmitted to the conductive layer, causing the conductive layer to be stretched or compressed and deformed.

[0051] In fact, the design of the strain-concentrated microstructure 104 serves a specific mechanical logic: since the external forces on the elastic micropillar 102 include normal pressure and shear forces in various directions, the strain-concentrated microstructure 104 is placed at a lateral position near the root of the elastic micropillar 102. The elastic micropillar 102 transmits the shear forces it receives to the area near its root and directly acts on the strain-concentrated microstructure 104, generating a strain concentration effect in the strain-concentrated microstructure 104. This causes the strain-concentrated microstructure 104 to produce maximum tensile or compressive deformation. At the same time, since the conductive layer is attached to the strain-concentrated microstructure 104, the conductive layer will also undergo a large degree of tensile or compressive deformation, which in turn causes a drastic change in the internal conductive path of the conductive layer, resulting in a drastic change in the conductivity of the conductive layer. That is, a significant resistance change rate (ΔR / R0) can be obtained, thereby greatly improving the sensitivity of the sensor to shear forces in various directions.

[0052] In some alternative embodiments, the strain concentration microstructure 104 can be disposed on the surface or inside the elastic base 101. For example, microstructures such as microholes, microcracks, and microgrooves that can generate strain concentration effects can be formed on the surface of the elastic base 101, or microchannels can be formed inside the elastic base 101.

[0053] In a specific embodiment, such as Figure 2As shown, in this embodiment, the strain-concentrating microstructure 104 is a V-shaped microgroove formed on the surface of the elastic base 101. Since the resistance-sensitive structure 103 is a conductive layer formed on the surface of the elastic base by spraying carbon black particles (CB NPs), the inner surface of the V-shaped microgroove of the strain-concentrating microstructure 104 is also sprayed with carbon black particles (CB NPs), that is, the conductive layer is attached to the inner surface of the V-shaped microgroove. When the strain-concentrating microstructure 104 is stretched, the state of the conductive channel changes as follows: the number of conductive paths formed between the carbon black particles decreases and the conductive paths become longer, the resistivity increases, and the on-resistance of the conductive layer increases; while when the strain-concentrating microstructure 104 is compressed, the state of the conductive channel changes as follows: the number of conductive paths formed between the carbon black particles increases and the conductive paths become shorter, the resistivity decreases, and the on-resistance of the conductive layer increases.

[0054] Experiments revealed that the strain-concentrating microstructure 104, employing a V-shaped microgroove, exhibits a significantly higher sensitivity to shear force responses in all directions compared to other microstructures. Furthermore, regarding the V-shaped microgroove itself, as its depth increases to 200 μm, the deformation consistency between the elastic micropillar and the V-shaped microgroove structure improves, leading to a gradual increase in the response to changes in conduction resistance. If the depth of the V-shaped microgroove is too shallow, even slight deformation can cause the conduction resistance change to reach its saturation limit. When the depth of the V-shaped microgroove exceeds 200 μm, the deformation of the V-shaped microgroove cannot effectively reach its bottom due to the localized obstruction of the elastic base, resulting in a gradual decrease in the response to changes in conduction resistance. Therefore, a depth of 200 μm is preferred for the V-shaped microgroove.

[0055] Furthermore, the distance between the V-shaped microgroove and the root of the elastic micropillar also affects the response to changes in conduction resistance. Since the greater the distance, the smaller the response to changes in conduction resistance caused by the V-shaped microgroove, the distance between the V-shaped microgroove and the root of the elastic micropillar is adjusted to be between 1.0 mm and 4.0 mm by the engraving machine, with 1.0 mm being the preferred distance. The extension direction of the V-shaped microgroove also affects the response to changes in conduction resistance. Setting the extension direction of the V-shaped microgroove to have an angle of 0° to 60° with the magnetic moment direction of the elastic micropillar can enhance the ability to distinguish the response direction of the magnetic induction signal from that of the conductive groove.

[0056] In a specific embodiment, such as Figure 1 As shown, in this embodiment, in order to improve the stability of the sensor during installation, the elastic base 101 is L-shaped, and the elastic micro-pillars 102 are disposed at the bend of the elastic base 101.

[0057] Furthermore, such as Figure 1In one specific embodiment shown, in order to improve the stability of the sensor during installation, the elastic base 101 is L-shaped, and the elastic micro-pillars 102 are disposed at the bend of the elastic base 101, which can effectively transfer the shear force it receives to the elastic base.

[0058] In this embodiment, considering that the dual-mode magnetoelastic sensor provided by the present invention uses the induced current generated by the induction coil as the first mode sensing output and the resistance value of the resistive sensing structure as the second mode sensing output; as for the wiring of the sensor, the induction coil only needs to be led out at both ends, while the wiring of the resistive sensing structure is more complicated. First, the resistance of the resistive sensing structure is based on the resistance change generated by deformation. Second, the resistive sensing structure is set on an elastic base. Regardless of the type of resistive sensing structure, directly connecting the two ends of the conduction resistance of the resistive sensing structure through wires may affect the stability of the wire connection due to long-term deformation.

[0059] Since the resistance-sensitive structure 103 is a conductive layer formed on the surface of the elastic base by spraying conductive particles, the conductive layer can be further extended to the ends of the two straight edges of the elastic base 102, and electrodes can be set at the ends of the two straight edges of the elastic base 102 respectively. The two ends of the conductive layer are electrically connected to the electrodes set at the ends of the two straight edges of the elastic base 102, thus realizing the wiring of the resistance-sensitive structure 103. In this way, since the connection point between the conductive layer and the electrode is at the ends of the two straight edges of the elastic base 102, the deformation transmission of the elastic micro-pillar 102 is minimized, which not only simplifies the sensor wiring, but also improves the stability of the sensor line connection.

[0060] like Figure 3 As shown, the present invention also provides a digital writing input device 1, which includes:

[0061] Pen tip structure 20;

[0062] At least one dual-modal magnetoelastic sensor 10 provided by the present invention, wherein the elastic micro-pillar of the dual-modal magnetoelastic sensor 10 abuts against the pen tip structure 20, for sensing the force applied to the pen tip structure 20 by the writer during writing;

[0063] The resistance detection unit is used to generate a corresponding resistance detection current signal based on the on-resistance of each of the dual-mode magnetoelastic sensors.

[0064] The signal acquisition unit is used to synchronously acquire the induced current signal and the resistance detection current signal of each of the dual-mode magnetoelastic sensors, amplify the acquired induced current signal and the resistance detection current signal, convert the amplified induced current signal and the resistance detection current signal into induced voltage signal and resistance detection voltage signal respectively, and perform analog-to-digital conversion on the induced voltage signal and the resistance detection voltage signal to obtain induced voltage data and resistance detection voltage data.

[0065] The writing result recognition unit is used to perform time series analysis on the induced voltage data and the resistance detection voltage data, extract multi-dimensional feature information, and recognize the writing result based on the multi-dimensional feature information; the writing result includes writing direction and writing force.

[0066] In one specific embodiment, in the digital writing input device provided by the present invention, the resistance detection unit is connected to the sensing port of the dual-mode magnetoelastic sensor and provides a constant excitation voltage, thereby using the change in resistance detection current to characterize the change in resistance value of the resistance-sensitive structure in the dual-mode magnetoelastic sensor.

[0067] In a specific embodiment, the digital writing input device provided by the present invention has a signal acquisition unit with multiple analog signal acquisition channels. The built-in signal conditioning circuit amplifies and filters the analog signals in each acquisition channel. Since the acquired induced current signal and resistance detection current signal are both current signals, while the input requirement of the high-speed analog-to-digital converter is a voltage signal, the induced current signal and resistance detection current signal need to be converted into induced voltage signal and resistance detection voltage signal by a current-to-voltage conversion circuit before analog-to-digital conversion.

[0068] In one specific embodiment, the digital writing input device provided by the present invention, such as Figure 4 As shown, through testing of the dual-modal magnetoelastic sensor provided by this invention, the induced voltage data and resistance detection voltage data obtained when the elastic micro-cylinder is subjected to force in different directions exhibit different characteristics and can be accurately distinguished. Therefore, by constructing a convolutional neural network to identify the corresponding writing direction in the writing results, the efficiency and accuracy of writing direction recognition can be improved.

[0069] In implementation, the first step is to determine the feature information to be extracted through time series analysis of induced voltage data and resistance detection voltage data. This includes multidimensional feature information such as the amplitude and rate of change characteristics of induced voltage and resistance detection voltage, the sign characteristics of induced voltage, and other statistical characteristics. Then, based on the design of corresponding convolutional layers and fully connected layers, the initial configuration of the convolutional neural network is completed. Next, the convolutional neural network is trained using manually tested data. After training, when the convolutional neural network is working, it extracts multidimensional feature vectors from the input multidimensional feature information through convolutional layers. Then, it fuses these multidimensional feature vectors through fully connected layers to output the corresponding writing direction in the writing result. It should be noted that the design and configuration of convolutional layers and fully connected layers in the convolutional neural network, as well as the training of the convolutional neural network, can be adjusted and optimized by those skilled in the art according to actual needs, and will not be elaborated further here.

[0070] Furthermore, the most direct way to determine the writing force corresponding to the writing result is to determine the writing force corresponding to the writing result based on the amplitude characteristics of the induced voltage and the resistance detection voltage.

[0071] Furthermore, in order to facilitate the transmission of writing results from the digital writing input device provided by the present invention to the digital writing presentation device, the digital writing input device provided by the present invention further includes: a writing result transmission unit, used to transmit the writing results to the digital writing presentation device.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dual-mode magnetoelastic sensor, characterized in that, It includes an elastic matrix, which is integrally formed by blending and curing elastic materials and magnetic particles, and the elastic matrix includes an elastic base and elastic micro-pillars erected on the elastic base; The elastic micro-pillar forms a directional and stable intrinsic magnetic moment after being magnetized; an induction coil is arranged below the elastic base to generate an induced current when the elastic micro-pillar is deformed by an external force, causing the spatial magnetic field distribution to change accordingly. The elastic base is provided with a resistance-sensitive structure, which is used to generate a change in resistance when the elastic micro-column is deformed by an external force and the resistance-sensitive structure is stretched or compressed. The induced current generated by the induction coil is used as the first mode sensing output; The resistance value of the resistance-sensitive structure is used as the second mode sensing output.

2. The dual-mode magnetoelastic sensor as described in claim 1, characterized in that, The resistance-sensitive structure is a conductive layer formed by conductive particles sprayed on the surface of the elastic base. When the conductive layer is stretched or compressed and deformed, the change in its internal conductive path causes a change in the conduction resistance.

3. The dual-mode magnetoelastic sensor as described in claim 2, characterized in that, A strain concentration microstructure is provided on the elastic base near the root of the elastic micro-pillar, and the strain concentration microstructure is located below the conductive layer; when the elastic micro-pillar is deformed by external force, the strain concentration effect generated by the strain concentration microstructure is transmitted to the conductive layer, causing the conductive layer to be stretched or compressed and deformed.

4. The dual-mode magnetoelastic sensor as described in claim 3, characterized in that, The strain-concentrating microstructure is a V-shaped microgroove formed on the surface of the elastic base, and the conductive layer is attached to the inner surface of the V-shaped microgroove.

5. The dual-mode magnetoelastic sensor as described in any one of claims 2 to 4, characterized in that, The elastic base is L-shaped, and the elastic micro-columns are located at the bend of the elastic base.

6. The dual-mode magnetoelastic sensor as described in claim 5, characterized in that, The conductive layer extends to the ends of the two straight edges of the elastic base and is electrically connected to the electrodes disposed at the ends of the two straight edges of the elastic base.

7. The dual-mode magnetoelastic sensor as described in claim 5, characterized in that, The elastic material is polydimethylsiloxane, the magnetic particles are neodymium iron boron powder, and the conductive particles are carbon black particles.

8. A digital writing input device, characterized in that, include: Pen tip structure; At least one dual-mode magnetoelastic sensor as described in any one of claims 1 to 7, wherein the elastic micropillar of the dual-mode magnetoelastic sensor abuts against the pen tip structure for sensing the force applied to the pen tip structure by the writer during writing; The resistance detection unit is used to generate a corresponding resistance detection current signal based on the on-resistance of each of the dual-mode magnetoelastic sensors. The signal acquisition unit is used to synchronously acquire the induced current signal and the resistance detection current signal of each of the dual-mode magnetoelastic sensors, amplify the acquired induced current signal and the resistance detection current signal, convert the amplified induced current signal and the resistance detection current signal into induced voltage signal and resistance detection voltage signal respectively, and perform analog-to-digital conversion on the induced voltage signal and the resistance detection voltage signal to obtain induced voltage data and resistance detection voltage data. The writing result recognition unit is used to perform time series analysis on the induced voltage data and the resistance detection voltage data, extract multi-dimensional feature information, and recognize the writing result based on the multi-dimensional feature information; The writing results include the writing direction and the writing pressure.

9. The digital writing input device as described in claim 8, characterized in that, The writing result recognition unit is pre-trained with a convolutional neural network, which is configured to: perform convolutional feature extraction on the input multidimensional feature information to obtain a multidimensional feature vector, then perform fusion processing on the multidimensional feature vector, and output the writing direction corresponding to the writing result.

10. The digital writing input device as claimed in claim 9, characterized in that, Also includes: The writing result transmission unit is used to transmit the writing result to the digital writing presentation device.

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