Micro displacement measuring device based on parallel plate capacitor

Abstract

The utility model discloses an infinitesimal displacement measuring device based on a parallel plate capacitor, and aims to overcome the defect of poor precision of a conventional capacitive displacement sensing device. The device comprises a capacitor plate, a fixing clamp, a supporting rod, a sliding rail sliding block, a sliding rail and a propelling micrometer. A capacitor plate is connected with a supporting rod through a fixing clamp, the lower end of the supporting rod is connected with a sliding rail sliding block, the sliding rail sliding block is matched with a sliding rail, and a propelling micrometer is arranged on the sliding rail. The fixing clamp stabilizes the polar plate, the supporting rod guarantees rigidity, the sliding rail sliding block and the sliding rail guarantee stable movement of the polar plate, the micrometer is pushed to accurately control displacement, and the infinitesimal displacement measurement precision is improved.

Description

Technical Field

[0001] This utility model relates to the field of micro-displacement measurement technology, specifically to a micro-displacement measurement device based on a parallel plate capacitor. Background Technology

[0002] High-precision measurement of micro-displacements has important applications in precision manufacturing, microelectromechanical systems (MEMS), high-precision 3D printing nozzle positioning, optical alignment, and vibration monitoring. Real-time measurement of micrometer- to nanometer-level displacements has a decisive impact on process accuracy. Currently, commonly used displacement sensing technologies include optical methods such as laser interferometry, inductive sensing, and capacitive sensing. While optical measurement methods offer high accuracy, they suffer from complex measurement devices, susceptibility to environmental influences, and high costs. In contrast, capacitive displacement sensing, with its advantages of simple structure, fast dynamic response, high sensitivity, and non-contact measurement, is widely used for nanometer- to micrometer-level displacement detection. However, it has significant shortcomings in measurement accuracy, specifically including less than ideal measurement accuracy, weak anti-interference capability, and poor data processing convenience.

[0003] Patent CN114111550A discloses a micro-displacement measuring device based on the voltage integration flip-capacitance method. It converts capacitance changes into a frequency signal via an operational amplifier circuit, which is then processed by a microcontroller to obtain the displacement. While this solution optimizes measurement linearity by converting the measured capacitance into a measured frequency signal and incorporating linear regression, it still suffers from key limitations affecting measurement accuracy: the detection accuracy is difficult to improve due to the voltage integration method's susceptibility to analog circuit noise; insufficient capacitance resolution leads to large displacement measurement errors; the capacitance-to-frequency conversion process is susceptible to electromagnetic interference; a temperature compensation module is not integrated to control errors caused by temperature drift; and there is no technology for real-time verification of reference accuracy during use. These factors collectively prevent it from meeting the accuracy requirements of more demanding application scenarios. Utility Model Content

[0004] The purpose of this invention is to provide a micro-displacement measuring device based on a parallel plate capacitor, so as to overcome the shortcomings in accuracy of existing capacitive displacement sensing devices.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A micro-displacement measuring device based on a parallel plate capacitor includes capacitor plates. The capacitor plates are connected to a support rod via a fixing clamp. The upper end of the support rod is connected to the fixing clamp, and the lower end is connected to a slide rail slider. The slide rail slider is connected to a slide rail, and a micrometer is fixed on the slide rail.

[0007] The capacitor plates include fixed plates and variable plates. The fixed plates are arranged on one side of the variable plates, and a micrometer is fixed on the other side.

[0008] A parallel plate capacitor is formed by fixed plates and variable plates that are parallel to each other.

[0009] The capacitor plates are circular.

[0010] The fixed fixture is equipped with a push plate and a push knob, with one end of the push knob passing through the fixed fixture and connecting to the push plate.

[0011] The bottom of the fixing fixture has a first screw hole, and the upper end of the support rod is connected to the first screw hole by a screw.

[0012] An adjustment sleeve is fitted onto the support rod, and an adjustment knob is arranged on the adjustment sleeve.

[0013] The slide rail slider is provided with a second screw hole, and the lower end of the support rod is connected to the second screw hole by a screw.

[0014] The slider of the slide rail is equipped with a fixed knob.

[0015] It also includes a data acquisition and processing system, which is connected to the capacitor plates to collect capacitance values.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] This invention provides a micro-displacement measuring device based on a parallel-plate capacitor. A robust measuring structure is constructed through the stable connection of the capacitor plates with a fixing clamp and a support rod. The fixing clamp firmly secures the capacitor plates, preventing loosening or wobbling during measurement and reducing capacitance measurement fluctuation errors caused by plate position deviations. The upper and lower ends of the support rod connect the fixing clamp and the slide rail slider, forming a rigid support to prevent deformation of the support structure from affecting the relative position of the plates and ensuring the stability of the plate spacing measurement. The cooperation between the slide rail slider and the slide rail ensures that the plate movement path is straight, preventing plate offset or tilting during displacement, maintaining the parallelism and consistent facing area of ​​the two plates, and reducing measurement errors caused by changes in the relative position of the plates. Simultaneously, the micrometer on the slide rail can precisely control the micro-displacement of the plates, providing an accurate benchmark for the correspondence between capacitance and displacement, thus effectively overcoming the accuracy deficiencies of existing capacitive displacement sensing devices. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a micro-displacement measuring device based on a parallel plate capacitor according to an embodiment of this utility model.

[0019] Figure 2 This is a schematic diagram of the capacitor plate structure in an embodiment of this utility model.

[0020] Figure 3 This is a schematic diagram of the fixing clamp structure in an embodiment of this utility model.

[0021] Figure 4 This is a top view of the fixing clamp in an embodiment of this utility model.

[0022] Figure 5 This is a schematic diagram of the slide rail slider structure in an embodiment of this utility model.

[0023] Figure 6 This is a schematic diagram of the adjusting sleeve structure in an embodiment of this utility model.

[0024] Figure 7 This is a schematic diagram showing the installation position of the capacitor plates in an embodiment of this utility model.

[0025] Figure 8 This is a schematic diagram of measurement data fitting in an embodiment of this utility model.

[0026] Figure 9 This is a schematic diagram of the data processing software in an embodiment of this utility model.

[0027] In the diagram, 1-capacitor plate, 2-fixed clamp, 3-support rod, 4-slide rail, 5-slide rail slider, 6-advance micrometer, 7-advance plate, 8-advance knob, 9-first screw hole, 10-fixed base, 11-second screw hole, 12-fixed knob, 13-adjusting sleeve, 14-adjusting knob, 15-variable plate, 16-fixed plate. Detailed Implementation

[0028] High-precision measurement of micro-displacements has important applications in precision manufacturing, microelectromechanical systems (MEMS), high-precision 3D printing nozzle positioning, optical alignment, and vibration monitoring. Real-time measurement of micrometer- to nanometer-level displacements has a decisive impact on process accuracy. Currently, commonly used displacement sensing technologies include optical methods such as laser interferometry, inductive sensing, and capacitive sensing. While optical measurement methods offer high accuracy, they suffer from complex measurement devices, susceptibility to environmental influences, and high costs. In contrast, capacitive displacement sensing, with its advantages of simple structure, fast dynamic response, high sensitivity, and non-contact measurement, is widely used for nanometer- to micrometer-level displacement detection. However, it has significant shortcomings in measurement accuracy, specifically including less than ideal measurement accuracy, weak anti-interference capability, and poor data processing convenience.

[0029] Patent CN114111550A discloses a micro-displacement measuring device based on the voltage integration flip-capacitance method. It converts capacitance changes into a frequency signal via an operational amplifier circuit, which is then processed by a microcontroller to obtain the displacement. While this solution optimizes measurement linearity by converting the measured capacitance into a measured frequency signal and incorporating linear regression, it still suffers from key limitations affecting measurement accuracy: the detection accuracy is difficult to improve due to the voltage integration method's susceptibility to analog circuit noise; insufficient capacitance resolution leads to large displacement measurement errors; the capacitance-to-frequency conversion process is susceptible to electromagnetic interference; a temperature compensation module is not integrated to control errors caused by temperature drift; and there is no technology for real-time verification of reference accuracy during use. These factors collectively prevent it from meeting the accuracy requirements of more demanding application scenarios.

[0030] Therefore, this utility model proposes a micro-displacement measuring device based on a parallel plate capacitor. By fixing the micrometer and the optical bench slide rail with a rigid bracket, precise micron-level displacement control is achieved, ensuring measurement accuracy from the mechanical structure level.

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "several" means two or more, unless otherwise explicitly specified.

[0035] Reference Figure 1 The figure shows a specific embodiment of the micro-displacement measuring device based on parallel plate capacitor provided by this utility model, including capacitor plate 1, capacitor plate 1 is connected to support rod 3 through fixing clamp 2, the upper end of support rod 3 is connected to fixing clamp 2, the lower end is connected to slide rail slider 5, slide rail slider 5 is connected to slide rail 4, and a micrometer 6 is fixed on slide rail 4.

[0036] The capacitor plate 1 includes a fixed plate 16 and a variable plate 15. The fixed plate 16 is arranged on one side of the variable plate 15, and a micrometer 6 is fixed on the other side. The fixed plate 16 is fixed in position by a corresponding fixing clamp 2, support rod 3, and slide rail slider 5. The variable plate 15 is mounted on a slide rail 4 by its matching fixing clamp 2, support rod 3, and slide rail slider 5, and can slide along the slide rail 4 under the action of the micrometer 6, thereby changing the distance between it and the fixed plate 16.

[0037] Fixed plate 16 and variable plate 15 are parallel to each other to form a parallel plate capacitor. The area of ​​their facing plates remains constant during measurement to ensure that the capacitance change is only related to the distance between the plates. The capacitor plates 1 are circular, and this shape design helps to ensure the uniformity of the electric field distribution between the plates, thereby improving the stability of the capacitance measurement.

[0038] The fixing clamp 2 is equipped with a push plate 7 and a push knob 8. One end of the push knob 8 passes through the fixing clamp 2 and is connected to the push plate 7. When it is necessary to fix the capacitor plate 1, by rotating the push knob 8, the push plate 7 can be moved towards the capacitor plate 1 until the push plate 7 is in close contact with the capacitor plate 1, thus achieving a stable clamping of the capacitor plate 1. When the push knob 8 is released, the push plate 7 moves away from the capacitor plate 1, making it easier to replace or adjust the position of the capacitor plate 1.

[0039] The bottom of the fixing clamp 2 is provided with a first screw hole 9, and the upper end of the support rod 3 is connected to the first screw hole 9 by a screw. This threaded connection method makes the fixing clamp 2 and the support rod 3 detachable, which facilitates the assembly, maintenance and replacement of parts of the device.

[0040] An adjusting sleeve 13 is fitted onto the support rod 3, and an adjusting knob 14 is arranged on the adjusting sleeve 13. By loosening the adjusting knob 14, the position of the adjusting sleeve 13 on the support rod 3 can be adjusted, thereby changing the height and angle of the fixing clamp 2 and the capacitor plate 1; after adjusting to the appropriate position, tightening the adjusting knob 14 can fix the adjusting sleeve 13 relative to the support rod 3, ensuring the stability of the position of the capacitor plate 1.

[0041] The slide rail slider 5 is provided with a second screw hole 11. The lower end of the support rod 3 is connected to the second screw hole 11 by a screw. This connection method is also a threaded connection, which realizes the detachable connection between the support rod 3 and the slide rail slider 5, making it convenient to replace the support rod 3 of different lengths or specifications according to actual measurement needs.

[0042] The slide rail slider 5 is equipped with a fixing knob 12. When it is necessary to adjust the position of the slide rail slider 5 on the slide rail 4, the fixing knob 12 is loosened and the slide rail slider 5 can slide freely along the slide rail 4. After the slide rail slider 5 moves to the target position, the fixing knob 12 is tightened to fix the slide rail slider 5 and the slide rail 4 relative to each other, preventing the slide rail slider 5 from shifting during the measurement process and affecting the measurement accuracy.

[0043] It also includes a data acquisition and processing system, which is connected to the capacitor plate 1 to acquire capacitance values. This system can acquire the capacitance change of the parallel plate capacitor formed between the fixed plate 16 and the variable plate 15 in real time, and calculate the minute displacement of the variable plate 15 based on the relationship between the capacitance and the distance between the plates, thereby realizing the measurement of minute displacement.

[0044] To make the micro-displacement measuring device based on parallel plate capacitors provided by this utility model easier to understand, another specific implementation method is provided below in conjunction with actual use to achieve further explanation.

[0045] In actual operation, the device is first initialized and debugged: the micrometer 6 is zeroed and the position of the micrometer thimble is recorded. By loosening the fixing knob 12 of the slide rail slider 5, the slide rail slider 5 is moved so that the fixed electrode plate 16 and the variable electrode plate 15 are completely in contact, ensuring that the area of ​​the two electrodes facing each other is the complete area of ​​a single circular electrode plate. Then, the base corresponding to the variable electrode plate 15 is moved to be close to the pushing end of the micrometer 6, while the other electrode plate serves as the fixed electrode plate 16, and its base position remains fixed. Since the base is made of rigid material and is not easily deformed, the displacement change of the distance between the two bases is measured to replace the actual movement distance of the electrode plate. After recording the initial distance reading between the two bases, the base of the fixed electrode plate 16 is moved outward so that the caliper reading reaches the preset initial electrode plate distance and is locked in place; at the same time, the fixing knob of the base of the variable electrode plate 15 is adjusted so that it can just be pushed by the micrometer, ensuring that the electrode plate remains parallel and stable during the movement.

[0046] After completing the mechanical structure debugging, connect the data acquisition and processing system: Connect one end of the DuPont wire used for capacitance measurement to the electrode pin of capacitor plate 1. In the experiment, it is preferable to connect the other end to the C3 and C4 ports of the STM32 microprocessor. Then, connect the 3.3V power supply terminal and ground terminal of the CH340E module to the corresponding ports of the microcontroller, and connect the transmitter TH2 of the microcontroller to the receiver RXD of the CH340E module to form a complete data transmission link. After connecting the module to the computer via USB interface, open the accompanying measurement software, set the serial port parameters, and set the baud rate to 115200 to start the real-time capacitance value acquisition function.

[0047] The experimental data acquisition process was conducted as follows: Three different initial electrode spacings of 10mm, 15mm, and 20mm were selected. For each spacing, minute displacement changes of 0.5mm, 0.1mm, and 0.05mm were measured. Fifteen to twenty capacitance readings were continuously collected for each parameter, with the first data point excluded due to potential initial leveling errors. The movement distance of the variable electrode 15 was controlled by rotating the micrometer 6, ensuring consistent displacement changes each time. The capacitance readings and calculated electrode displacement values ​​were recorded synchronously after each movement.

[0048] After data collection, the experimental data were organized and analyzed. Each set of data was compiled into a table showing the correspondence between capacitance value C and the reciprocal of displacement x. A scatter plot was then drawn with capacitance value C as the ordinate and reciprocal of displacement x as the abscissa. A linear fitting method was used to obtain the linear equation C=ax+b corresponding to the nine sets of experimental data, as shown below. Figure 8 As shown in the figure. The physical meaning of the fitting parameter 'a' is the theoretical capacitance reading of the device when the plate spacing is 1 mm, while parameter 'b' reflects systematic errors such as parasitic capacitance. Correcting the intercept 'b' can effectively reduce the impact of systematic errors on the measurement results. Based on the above linear relationship, supporting data processing software can be developed to automatically calculate and output the corresponding displacement change by inputting the capacitance values ​​from two measurements, such as... Figure 9 As shown, this further enhances the ease of use of the device.

[0049] This invention provides a micro-displacement measuring device based on a parallel plate capacitor. Through a rigid base design, the change in base spacing displacement replaces the distance the plates move, reducing errors caused by deformation during direct plate measurement and ensuring the stability of the displacement measurement benchmark. Simultaneously, a micrometer is used to precisely control the movement of the variable plates, and a fixed knob on the slide rail ensures stable positioning, guaranteeing the accuracy of plate spacing adjustment. Multiple sets of experimental data are collected, and a linear equation C=ax+b is obtained through linear fitting, effectively identifying and correcting systematic errors such as parasitic capacitance, improving the accuracy of capacitance-displacement conversion. A circular plate design ensures the consistency of the facing area of ​​the two plates, and a fixed clamp with a push plate and push knob provides stable clamping of the plates, reducing capacitance fluctuations caused by plate offset or loosening during measurement, further improving measurement accuracy, and thus overcoming the shortcomings of existing capacitive displacement sensing devices.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A micro-displacement measuring device based on a parallel-plate capacitor, characterized in that, It includes a capacitor plate (1), which is connected to a support rod (3) via a fixing clamp (2). The upper end of the support rod (3) is connected to the fixing clamp (2), and the lower end is connected to a slide rail slider (5). The slide rail slider (5) is connected to a slide rail (4), and a micrometer (6) is fixed on the slide rail (4).

2. The micro-displacement measuring device based on a parallel plate capacitor according to claim 1, characterized in that, The capacitor plate (1) includes a fixed plate (16) and a variable plate (15). The fixed plate (16) is arranged on one side of the variable plate (15), and a micrometer (6) is fixed on the other side.

3. The micro-displacement measuring device based on a parallel plate capacitor according to claim 2, characterized in that, The fixed plate (16) and the variable plate (15) are parallel to each other to form a parallel plate capacitor.

4. The micro-displacement measuring device based on a parallel plate capacitor according to claim 1, characterized in that, The capacitor plate (1) is a circular capacitor plate.

5. A micro-displacement measuring device based on a parallel-plate capacitor according to claim 1, characterized in that, The fixed clamp (2) is provided with a push plate (7) and a push knob (8), one end of which passes through the fixed clamp (2) and is connected to the push plate (7).

6. The micro-displacement measuring device based on a parallel plate capacitor according to claim 1, characterized in that, The bottom of the fixing clamp (2) is provided with a first screw hole (9), and the upper end of the support rod (3) is connected to the first screw hole (9) by a screw.

7. A micro-displacement measuring device based on a parallel-plate capacitor according to claim 1, characterized in that, An adjusting sleeve (13) is fitted onto the support rod (3), and an adjusting knob (14) is arranged on the adjusting sleeve (13).

8. A micro-displacement measuring device based on a parallel-plate capacitor according to claim 1, characterized in that, The slide rail slider (5) is provided with a second screw hole (11), and the lower end of the support rod (3) is connected to the second screw hole (11) by a screw.

9. A micro-displacement measuring device based on a parallel-plate capacitor according to claim 8, characterized in that, The slide rail slider (5) is equipped with a fixing knob (12).

10. A micro-displacement measuring device based on a parallel-plate capacitor according to claim 1, characterized in that, It also includes a data acquisition and processing system, which is connected to the capacitor plate (1) to collect capacitance values.

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