LVDT (Linear Variable Differential Transformer) sensor based on multilayer stacked PCB (Printed Circuit Board)
By adopting a multi-layer stacked PCB design in the LVDT sensor and integrating electromagnetic shielding layer and high-precision coil, the traditional LVDT sensors have solved the shortcomings in volume and performance, and achieved the improvement of miniaturization, high precision and good anti-interference performance.
Patent Information
- Application Number
- CN202411953425.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-04-11
AI Technical Summary
Traditional LVDT sensors are difficult to take into account both the dual requirements of volume and performance, especially in miniaturized and high-precision application scenarios, and structural optimization methods have problems such as spatial limitations and manufacturing difficulty.
Using a multi-layer stacked PCB design, the coil, shielding layer and circuit are integrated, and the anti-interference ability is improved through the electromagnetic shielding structure, and the coil is formed through a high-precision etching process to ensure consistency and symmetry.
It realizes the miniaturization of the sensor, improves the anti-interference ability and measurement accuracy, enhances electromagnetic compatibility, and provides good heat dissipation performance, improving the stability and reliability of the sensor.
Smart Images
Figure CN119803255A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of linear variable differential transformers and relates to an LVDT sensor based on a multi-layer stacked PCB. Background Art
[0002] In today's era of rapid technological development, many fields have put forward urgent demands for high-precision, miniaturized and reliable displacement measurement technology. In the field of industrial automation, the precise operation of automated production lines depends on the precise monitoring and control of the displacement of various mechanical parts. Whether it is the displacement adjustment of tools in precision machine tools or the precise feedback of robot joint movement, displacement sensors are required to be able to work stably in complex electromagnetic environments and limited spaces. Traditional displacement sensors often find it difficult to meet the dual requirements of size and performance.
[0003] In the field of aerospace, aircraft attitude control, wing deformation monitoring, and displacement detection of engine components require sensors to have extremely high reliability, anti-interference ability, and lightweight and miniaturization to adapt to harsh space and environmental conditions while ensuring the accuracy and timeliness of measurement data. In the field of medical devices, such as minimally invasive surgical instruments, prosthetic joint motion sensing and other application scenarios, there are special requirements for the size, accuracy and biocompatibility of displacement sensors. Traditional linear variable differential transformer (LVDT) sensors are subject to many limitations in these miniaturized, high-precision medical equipment applications due to their large size and relatively complex structure.
[0004] Mainstream LVDT sensors are exploring various optimization methods to improve their performance. Among them, signal processing and circuit design use amplifiers, filters, and demodulation circuits to process the weak and easily interfered signals output by LVDT sensors, filter out noise and amplify effective signals. At the algorithm level, the nonlinear characteristics of the sensor are accurately corrected through complex digital compensation algorithms, thereby enhancing the measurement accuracy and linearity of the LVDT. However, it cannot be ignored that such optimization methods based on signal processing, circuit design, and algorithms require high costs and have limited adaptability. In contrast, the structural design method shows unique advantages in improving the performance of LVDT sensors. Structural design mainly covers several key components of LVDT, such as coils, cores, skeletons, etc. Fundamentally speaking, the optimization of structural design can directly act on the physical properties and working principles of the sensor, so it has broad application potential and development prospects.
[0005] Currently, LVDT sensors based on structural optimization generally use coil optimization, winding optimization, and core optimization to improve sensor performance. However, all of these methods have certain limitations.
[0006] In the traditional LVDT sensor structure optimization, whether increasing the number of coil turns, adjusting the winding method or optimizing the shape and size of the core, it will be limited by space. For example, increasing the number of coil turns in a limited skeleton space may cause the wire diameter to become smaller, thereby increasing resistance and affecting sensor performance; changes in the core size may also be difficult to achieve the ideal optimization effect due to space limitations, and it cannot fully exert its enhancement and coupling effects on the magnetic field, thereby limiting the further improvement of sensor performance.
[0007] High-precision optimization of coils, windings, and cores often requires complex manufacturing processes. For example, precise control of the number of turns of the coil, uniform winding of the windings, and manufacturing of cores of special shapes all increase the difficulty and cost of production. Moreover, complex processes may make it difficult to ensure product consistency, thus affecting the performance stability of the sensor and the quality control of mass production.
[0008] In addition, as the number of coil turns increases or the size of the core increases, the heat generated by the sensor during operation will also increase accordingly. The traditional structure of the LVDT sensor has limited heat dissipation channels. The heat dissipation difficulty will cause the sensor temperature to rise, which in turn affects its performance parameters, such as increased resistance, changes in the core magnetic permeability, etc., reducing the accuracy and stability of the sensor. Summary of the invention
[0009] The purpose of the present invention is to provide an LVDT sensor based on a multi-layer stacked PCB. The technical solution adopted by the present invention is:
[0010] An LVDT sensor based on a multi-layer stacked PCB, comprising: a top shielding layer, a bottom shielding layer, an upper coil layer, a lower coil layer and an iron core;
[0011] The iron core is centrally arranged between the upper coil layer and the lower coil layer, the top shielding layer is arranged above the upper coil layer, and the bottom shielding layer is arranged below the lower coil layer;
[0012] The upper coil layer and the lower coil layer each include an isolation layer and a coil, the coil is arranged on the isolation layer, and the iron core is arranged between the isolation layers;
[0013] The top shielding layer and the bottom shielding layer are connected through vias, and the upper coil layer and the lower coil layer are connected through vias.
[0014] In one embodiment of the present invention, the upper coil layer includes an upper primary coil layer and an upper secondary coil layer, and the lower coil layer includes a lower primary coil layer and a lower secondary coil layer;
[0015] The upper primary coil layer is arranged above the upper secondary coil layer, and the lower primary coil layer is arranged below the lower secondary coil layer;
[0016] The upper primary coil layer is connected to the lower primary coil layer through a via hole, and the upper secondary coil layer is connected to the lower secondary coil layer through a via hole.
[0017] In one embodiment of the present invention, the upper secondary coil layer and the lower secondary coil layer are both composed of several layers, and the upper secondary coil layers of different layers are connected through vias, and the lower secondary coil layers of different layers are connected through vias.
[0018] In one embodiment of the present invention, different parts of the upper secondary coil layer and the lower secondary coil layer are connected via vias.
[0019] In one embodiment of the present invention, the upper primary coil layer and the lower primary coil layer are both composed of several layers, and the upper primary coil layers of different layers are connected through vias, and the lower primary coil layers of different layers are connected through vias.
[0020] In one embodiment of the present invention, different parts of the upper primary coil layer and the lower primary coil layer are connected through vias.
[0021] In one embodiment of the present invention, the coils are arranged in a spiral rectangular shape.
[0022] In one embodiment of the present invention, the material of the isolation layer is epoxy glass cloth laminate.
[0023] In one embodiment of the present invention, the materials of the top shielding layer and the bottom shielding layer are both copper foil.
[0024] In one embodiment of the present invention, the material of the iron core is Permalloy, and the shape of the iron core is cylindrical.
[0025] Beneficial effects of the present invention:
[0026] 1. The LVDT sensor of the present invention can integrate multiple circuit layers in the vertical direction, so that the coil, shielding layer, connecting line, etc. are integrated in a compact space to achieve miniaturization of the sensor;
[0027] 2. The LVDT sensor of the present invention improves the anti-interference ability of the sensor by designing an electromagnetic shielding structure in a multi-layer printed circuit board (PCB), arranges a metal shielding layer between the PCB layers, and uses electromagnetic shielding vias to ground the shielding layer, forming a closed electromagnetic shielding environment. This shielding structure can effectively reduce the influence of external electromagnetic interference on the internal magnetic field of the sensor, thereby improving the stability and reliability of the sensor;
[0028] 3. The LVDT sensor of the present invention can form a coil through a high-precision etching process, ensuring the consistency and symmetry of the coil, and can accurately control the number of turns, line width and other parameters of the coil, thereby improving the measurement accuracy and linearity of the sensor;
[0029] 4. The LVDT sensor of the present invention has a large heat dissipation area and good thermal conductivity, which can effectively dissipate the heat generated when the sensor is working, thereby providing support for the advancement of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 A longitudinal cross-sectional schematic diagram of an LVDT sensor based on a multi-layer stacked PCB provided in an embodiment of the present invention;
[0031] Figure 2 A schematic diagram of the structure of an LVDT sensor based on a multi-layer stacked PCB provided in an embodiment of the present invention;
[0032] Figure 3 The magnetic flux density of the iron core at different positions according to the embodiment of the present invention;
[0033] Figure 4 A schematic diagram of a PCB coil design provided in an embodiment of the present invention.
[0034] In the figure: 1. Top shielding layer, 2. Upper coil layer, 3. Iron core, 4. Lower coil layer, 5. Bottom shielding layer, 6. Isolation layer, 7. Coil, 8. Via. DETAILED DESCRIPTION
[0035] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.
[0036] See attached Figure 1 and attached Figure 2 The present embodiment provides an LVDT sensor based on a multi-layer stacked PCB, and the LVDT sensor based on the multi-layer stacked PCB includes: a top shielding layer 1, a bottom shielding layer 5, an upper coil layer 2, a lower coil layer 4 and an iron core 3. The iron core 3 is centrally arranged between the upper coil layer 2 and the lower coil layer 4, the top shielding layer 1 is arranged above the upper coil layer 2, and the bottom shielding layer 5 is arranged below the lower coil layer 4. The upper coil layer 2 and the lower coil layer 4 both include an isolation layer 6 and a coil 7, the coil 7 is arranged on the isolation layer 6, and the iron core 3 is arranged between the isolation layers 6. The top shielding layer 1 and the bottom shielding layer 5 are connected through a via 8, and the upper coil layer 2 and the lower coil layer 4 are connected through a via 8.
[0037] The LVDT sensor of the present invention can integrate the coil, shielding layer, circuit, etc. into a compact structure, which can not only effectively reduce the volume, but also take advantage of the high precision advantage of the printed circuit board (PCB) manufacturing process to improve the consistency and reliability of the sensor, enhance electromagnetic compatibility, and have a large heat dissipation area and good thermal conductivity.
[0038] In one embodiment of the present invention, the upper coil layer 2 includes an upper primary coil layer and an upper secondary coil layer, and the lower coil layer 4 includes a lower primary coil layer and a lower secondary coil layer. The upper primary coil layer is arranged above the upper secondary coil layer, and the lower primary coil layer is arranged below the lower secondary coil layer. The upper primary coil layer is connected to the lower primary coil layer through a via, and the upper secondary coil layer is connected to the lower secondary coil layer through a via.
[0039] For ease of presentation, Figure 1 and attached Figure 2 In the example, the upper primary coil layer and the lower primary coil layer are one layer, and the upper secondary coil layer and the lower secondary coil layer are two layers. The vias in and between the upper secondary coil layer and the lower secondary coil layer (see Appendix Figure 1 The black vertical part in the figure) is used to connect different parts of the upper secondary coil layer with the lower secondary coil layer.
[0040] In one embodiment of the present invention, the upper secondary coil layer and the lower secondary coil layer can be composed of several layers, and the upper secondary coil layers of different layers are connected through vias to form a group of secondary coils in series, and the lower secondary coil layers of different layers are connected through vias to form another group of secondary coils in series. The upper secondary coil layer and the lower secondary coil layer are connected by vias between different parts in the layer. The coil of the upper secondary coil layer will receive the magnetic field generated by the upper primary coil layer, and will also respond to the excitation signal of the upper primary coil and generate a voltage induced by the upper secondary coil, and the lower secondary coil layer will be consistent with the upper secondary coil layer.
[0041] In one embodiment of the present invention, the upper primary coil layer and the lower primary coil layer are each composed of several layers, and the upper primary coil layers of different layers are connected through vias to form a group of upper primary coils in series, and the lower primary coil layers of different layers are connected through vias to form another group of upper primary coils in series. Different parts of the upper primary coil layer and the lower primary coil layer in the layer are connected through vias.
[0042] The upper primary coil layer and the lower primary coil layer both have windings of the primary coil, and the primary coil windings of the upper primary coil layer are connected to the primary coil windings of the lower primary coil layer. This ensures that the current can flow from the end of the coil of the upper primary coil layer to the beginning of the coil of the lower primary coil layer, thereby forming a complete primary coil circuit. When an external AC power source is connected to the primary coil vias located in the upper primary coil layer and the lower primary coil layer, the AC current flows in the primary coil. According to the principle of electromagnetic induction, the energized primary coil will generate an alternating magnetic field in the space around it. Since the primary coil adopts a spiral rectangular design and is distributed in a specific layer of the multi-layer PCB, the alternating magnetic field can evenly cover the entire internal area of the multi-layer PCB and effectively penetrate the intermediate layers.
[0043] On the upper secondary coil layer and the lower secondary coil layer within the layer, due to the limitation of PCB wiring, the layers are divided into several parts, and the vias connect these parts to form a complete secondary coil segment. Between layers, vias play the role of connecting the secondary coils of different layers. The secondary coil windings of different upper secondary coil layers are connected through vias to form a complete secondary coil. In this way, the secondary coil windings between different layers work together to respond to the excitation of the primary coil.
[0044] Due to the design and connection of the secondary coils, their induced electromotive force will show a differential change relationship. That is, when the iron core moves in a certain direction, the coils of the upper secondary coil layer and the coils of the lower secondary coil layer respectively output differential signals. The two pairs of coils are synthesized through a differential amplifier and a signal processing circuit, and the output difference has a linear relationship with the displacement of the iron core. The displacement of the iron core can be accurately calculated based on the measured voltage difference, thereby realizing the high-precision measurement function of the displacement. The magnetic flux density of the iron core at different positions refers to the attached Figure 3 Attached Figure 3 In the figure, (a) the core is at the left end, (b) the core is in the middle, and (c) the core is at the right end.
[0045] See attached Figure 4 The coils 7 of this embodiment are arranged in a spiral rectangular shape. The number of turns of the coils 7 can be flexibly adjusted according to practical conditions, and the spacing of the coils 7 is close to the diameter of the coils 7 to ensure that a suitable inductance value and magnetic field strength are obtained in a limited space.
[0046] In one embodiment of the present invention, the material of the isolation layer 6 is epoxy glass cloth laminate (FR-4), which can not only ensure the electrical insulation between the layers and effectively prevent the occurrence of short circuits, but also reduce the electromagnetic coupling between the layers to a certain extent and avoid mutual interference between circuits in different layers.
[0047] The materials of the top shielding layer 1 and the bottom shielding layer 5 are both copper foil. The top shielding layer 1 effectively blocks the influence of external electromagnetic interference on the internal circuit and coil by laying copper over a large area and grounding, providing the first electromagnetic protection barrier for the entire sensor. The bottom shielding layer 2 is similar to the top shielding layer 1, made of copper foil and grounded over a large area, which further enhances the electromagnetic shielding performance of the entire multi-layer PCB, and works in synergy with the top shielding layer 1 to create a stable, low-interference electromagnetic environment for the internal coils and circuits.
[0048] In one embodiment of the present invention, the material of the iron core 3 is Permalloy, and the shape of the iron core 3 is cylindrical. The iron core is made of Permalloy material with high magnetic permeability, and the relative magnetic permeability is 8000-12000, ensuring that the iron core can move freely and smoothly in the channel. When the iron core is displaced in the channel, due to the high magnetic permeability of the iron core, the magnetic flux passing through the upper secondary coil layer and the lower secondary coil layer will change significantly. According to the law of electromagnetic induction, an induced electromotive force will be generated in the upper secondary coil layer and the lower secondary coil layer.
[0049] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by the terms "upper", "lower", "top", "bottom", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. All contents that do not deviate from the technical solution of the present invention should be included in the protection scope of the present invention.
Claims
1. An LVDT sensor based on a multi-layer stacked PCB, characterized in that: include: Top shield layer, bottom shield layer, upper coil layer, lower coil layer and iron core; The iron core is centrally arranged between the upper coil layer and the lower coil layer, the top shielding layer is arranged above the upper coil layer, and the bottom shielding layer is arranged below the lower coil layer; The upper coil layer and the lower coil layer each include an isolation layer and a coil, the coil is arranged on the isolation layer, and the iron core is arranged between the isolation layers; The top shielding layer and the bottom shielding layer are connected through vias, and the upper coil layer and the lower coil layer are connected through vias.
2. The LVDT sensor based on a multi-layer stacked PCB according to claim 1, characterized in that: The upper coil layer includes an upper primary coil layer and an upper secondary coil layer, and the lower coil layer includes a lower primary coil layer and a lower secondary coil layer; The upper primary coil layer is arranged above the upper secondary coil layer, and the lower primary coil layer is arranged below the lower secondary coil layer; The upper primary coil layer is connected to the lower primary coil layer through a via hole, and the upper secondary coil layer is connected to the lower secondary coil layer through a via hole.
3. The LVDT sensor based on a multi-layer stacked PCB according to claim 2, characterized in that: The upper secondary coil layer and the lower secondary coil layer are both composed of several layers, and the upper secondary coil layers of different layers are connected through vias, and the lower secondary coil layers of different layers are connected through vias.
4. The LVDT sensor based on a multi-layer stacked PCB according to claim 2, characterized in that: Different parts of the upper secondary coil layer and the lower secondary coil layer are connected through vias.
5. The LVDT sensor based on a multi-layer stacked PCB according to claim 2, characterized in that: The upper primary coil layer and the lower primary coil layer are both composed of several layers, and the upper primary coil layers of different layers are connected through vias, and the lower primary coil layers of different layers are connected through vias.
6. The LVDT sensor based on a multi-layer stacked PCB according to claim 2, characterized in that: Different parts of the upper primary coil layer and the lower primary coil layer are connected through vias.
7. An LVDT sensor based on a multi-layer stacked PCB according to any one of claims 1 to 6, characterized in that: The coils are arranged in a spiral rectangular shape.
8. The LVDT sensor based on multi-layer stacked PCB according to claim 7, characterized in that: The material of the isolation layer is epoxy glass cloth laminate.
9. The LVDT sensor based on a multi-layer stacked PCB according to claim 7, characterized in that: The top shielding layer and the bottom shielding layer are both made of copper foil.
10. The LVDT sensor based on multi-layer stacked PCB according to claim 7, characterized in that: The material of the iron core is Permalloy, and the shape of the iron core is cylindrical.