Variable area capacitive sensor displacement and spacing measurement device and method

Abstract

The application discloses a variable-area capacitive sensor displacement and interval measuring device and method, which comprises the following steps: S1, arranging at least two groups of capacitive units in the same plane along a direction, initially locating a moving electrode plate at a middle position between two fixed electrode plates, and making the facing areas of left and right capacitors equal; S2, applying a load wave excitation on the moving electrode plate, collecting modulation signals output by the left and right fixed electrode plates, multiplying the modulation signals with the carrier wave respectively, and obtaining voltage signals proportional to the left and right capacitance values through low-pass filtering after demodulation; S3, calculating the capacitance change ΔC and the total capacitance ΣC according to the left and right capacitance values obtained in step S2; and S4, calling a proportional coefficient and an initial interval parameter obtained through calibration, calculating a horizontal direction displacement x based on ΔC, calculating a vertical direction displacement y based on ΣC, and outputting x and y.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a device and method for measuring displacement and spacing using a variable area capacitive sensor. Background Technology

[0002] Capacitive sensors, a common sensing technology that detects physical quantities (such as displacement, pressure, and acceleration) based on changes in capacitance, work by utilizing how changes in the measured physical quantity alter the geometric parameters of the capacitor (such as plate area, spacing, or dielectric properties), thereby causing a change in capacitance. With advantages such as simple structure, non-contact measurement, low power consumption, and fast response speed, capacitive sensors are widely used in numerous fields including consumer electronics, industrial control, medical equipment, and aerospace.

[0003] Among various capacitive sensors, variable-area capacitive sensors are commonly used for precision displacement measurement due to their sensitivity to displacement changes. These sensors consist of a fixed electrode and a movable electrode. When an external physical quantity acts on the movable electrode, the overlapping area between the two electrodes changes, causing a change in capacitance. The magnitude of the displacement can be deduced by measuring the change in capacitance.

[0004] However, traditional single-capacitive sensors have many problems in practical applications. With the increasing precision requirements of modern manufacturing, the demand for high-precision measurement of minute displacements is growing. Traditional displacement sensors mostly use a single degree of freedom measurement method, which is insufficient to meet the need for simultaneous sensing of motion states in multiple directions.

[0005] Currently, common capacitive displacement sensors include variable area and variable spacing types, but most can only measure displacement in one direction. Some studies have employed dual-capacitor differential structures to improve sensitivity, but these still cannot distinguish the effects of horizontal and vertical displacement, lacking effective decoupling mechanisms or mathematical models. Therefore, there is an urgent need to provide a novel capacitive sensor structure that is simple in structure, has high measurement accuracy, and can simultaneously acquire horizontal and vertical displacement information, along with corresponding data processing methods. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a displacement and spacing measurement device and method of a variable area capacitive sensor, which can calculate the displacement of the measured object in the horizontal and vertical directions in real time and accurately by means of the change in capacitance value.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A displacement and spacing measurement device for a variable area capacitive sensor includes:

[0009] The capacitor structure consists of N sets of capacitor units arranged in parallel along a straight line on the same plane. Each set of capacitor units consists of a fixed plate and a moving plate arranged opposite and parallel to each other. The fixed plate consists of a left fixed plate and a right fixed plate arranged symmetrically. The area of ​​the moving plate is smaller than that of the fixed plate, and the moving plate can move relative to the fixed plate. In the initial state, the area of ​​the moving plate facing the left and right fixed plates is equal. The moving plate and the left fixed plate form the left capacitor, and the moving plate and the right fixed plate form the right capacitor. The initial capacitances of the left and right capacitors are equal.

[0010] The calibration module is used to change the horizontal displacement x of the moving plate under the condition that the vertical displacement y=0, record the correspondence between the capacitance change ΔC of the capacitor unit and the horizontal displacement x, and fit the area change coefficient k; under the condition that the horizontal displacement x=0, change the vertical displacement y of the moving plate, record the correspondence between the total capacitance ΣC of the left and right capacitors and the vertical displacement y, verify the linearity and determine the initial spacing parameters.

[0011] The carrier excitation module is used to apply a carrier wave to the moving electrode plate;

[0012] The capacitance detection and synchronous demodulation circuit is used to multiply and demodulate the modulation signals output from the left and right fixed plates and then perform low-pass filtering to obtain a voltage that is proportional to the left and right capacitors.

[0013] The processor is used to calculate the capacitance change ΔC and the total capacitance ΣC, and to calculate the horizontal displacement x and vertical displacement y based on the parameters obtained from the calibration module.

[0014] Where N≥2, the total plate area composed of all fixed and moving plates remains unchanged, in order to improve the relative capacitance change rate and measurement sensitivity.

[0015] Furthermore, the processor is configured to normalize ΔC when outputting horizontal displacement x to offset the influence of vertical displacement y, and to suppress the influence of horizontal displacement x by utilizing the sum of capacitances ΣC when outputting vertical displacement y.

[0016] Furthermore, the capacitance detection and synchronous demodulation circuit includes a multiplier, a low-pass filter, and a C / V conversion unit, which can suppress the carrier wave and output a DC signal proportional to the capacitance value.

[0017] The present invention also provides a displacement and spacing measurement method based on a variable area capacitive sensor, wherein the displacement and spacing measurement device based on the above-mentioned variable area capacitive sensor includes:

[0018] S1. Arrange at least two sets of capacitor units in one direction on the same plane. Initially, the moving plate is located in the middle of the two fixed plates, so that the facing areas of the left and right capacitors are equal.

[0019] S2. Apply carrier excitation to the moving plate, collect the modulation signals output from the left and right fixed plates, multiply and demodulate them with the carrier respectively, and then filter them with a low-pass filter to obtain voltage signals that are proportional to the capacitance values ​​of the left and right plates.

[0020] S3. Calculate the capacitance change ΔC and the total capacitance ΣC based on the capacitance values ​​on the left and right sides obtained in step S2;

[0021] S4 calls the area change coefficient k and initial spacing parameters obtained through calibration, calculates the horizontal displacement x based on ΔC, calculates the vertical displacement y based on ΣC, and outputs x and y.

[0022] Furthermore, in step S1, the total plate area remains unchanged, and the original single capacitor pair is split into N groups of parallel capacitor units, so as to increase the relative change rate of each group of capacitor units to N times the original under the same displacement conditions.

[0023] Furthermore, step S2 synchronous demodulation includes: multiplying the left and right modulation voltage signals by the inverted carrier to suppress the carrier component, and then passing them through a low-pass filter to obtain a DC quantity proportional to the capacitor C.

[0024] Furthermore, the calculation process in step S4 satisfies the following: the horizontal displacement x is determined by the linear relationship between the capacitance change ΔC and the area change coefficient k, the vertical displacement y is determined by the functional relationship between the capacitance and ΣC and the distance between the plates, and the influence of x on y is canceled out by normalization.

[0025] Furthermore, the calibration includes: changing x under the condition of y=0, recording the correspondence between the capacitance change ΔC and x to obtain k; changing y under the condition of x=0, recording the correspondence between capacitance and ΣC and y to verify linearity and determine the initial spacing parameter.

[0026] Furthermore, by utilizing the fact that the sensitivity of capacitance change ΔC to the horizontal direction is independent of the sensitivity of capacitance and ΣC to the vertical direction, interference of vertical displacement on horizontal measurement under vibration environment can be suppressed.

[0027] Furthermore, it is used for precision displacement detection and adapted to high-speed dynamic measurement scenarios.

[0028] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0029] 1. N sets of capacitor units are connected in parallel on the same plane (total area remains unchanged); traditional single large capacitors have small ΔC / C ratios and are difficult to detect at small displacements; after being split into N sets of capacitor units, the original total capacitance C is reduced to C / N but ΔC remains unchanged, increasing the relative change rate to N·(ΔC / C), significantly enhancing the response capability, detectability and overall sensitivity of small displacements, and making the sensor sensitivity increase linearly with the increase of the number of capacitor pairs; effectively solving the problem of insufficient sensitivity of traditional capacitive sensors and meeting the application requirements of high-precision displacement measurement.

[0030] 2. A synchronous demodulation link employing carrier excitation, multiplication demodulation, and low-pass filtering is used; after multiplication with the inverted carrier, low-pass filtering is performed to retain only the DC component proportional to the capacitance, suppressing the carrier and high-frequency harmonics, and improving the signal-to-noise ratio and stability; this solves the problems of interference from carrier and environmental noise and carrier leakage when directly measuring capacitance.

[0031] 3. Based on geometric relationships and capacitance models, the capacitance change ΔC is determined to mainly represent the change in the area x, the capacitance and ΣC change y with the distance, and the mutual interference is canceled by normalization to achieve synchronous measurement of two degrees of freedom. It can calculate the displacement of the measured object in the horizontal and vertical directions in real time and accurately, and solve the problem of the coupling of horizontal and vertical displacements, which makes it difficult to solve accurately at the same time.

[0032] 4. Under the univariate condition of horizontal displacement x (reflecting the change in the facing area) or vertical displacement y (reflecting the change in the distance between the fixed and moving plates), the ΔC / ΣC curve is recorded and fitted to obtain parameters such as the proportional coefficient and the initial distance, making the online solution stable and reproducible. This solves problems such as quantization errors caused by parameter uncertainty.

[0033] 5. The capacitor structure is initially symmetrical and has equal area; in the initial state, the area of ​​the moving plate, the left fixed plate, and the right fixed plate is equal, so that the initial capacitance of the left and right capacitors is equal, the zero point of ΔC is clear, the zero bias is easy to correct, the long-term stability is improved, and the zero point drift caused by the initial imbalance is avoided.

[0034] 6. Measurement strategy to resist vertical interference: By focusing on the change in capacitance ΔC (area change) and the change in capacitance and ΣC (distance change), the x / y cross term is normalized and suppressed in the calculation, improving the measurement accuracy in vibration environments. This avoids interference from vertical displacement caused by mechanical vibration on horizontal measurements. Attached Figure Description

[0035] Figure 1a This is a schematic diagram of a single capacitor unit.

[0036] Figure 1b yes Figure 1a A side view of a single capacitor unit.

[0037] Figure 1c It is a schematic diagram of a structure in which multiple capacitor units are connected in parallel in the same plane and in the same direction.

[0038] Figure 2 This is a diagram showing the working principle and structure of a variable area capacitive sensor. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0040] Example 1

[0041] This embodiment provides a displacement and spacing measurement device using a variable area capacitive sensor. See Figure 1c ,include:

[0042] Capacitor structure, such as Figure 1a and Figure 1b As shown, the capacitor consists of N sets of capacitor units arranged in parallel along a straight line on the same plane. Each set of capacitor units consists of a fixed plate 1 and a moving plate 2 arranged opposite and parallel to each other. The fixed plate 1 consists of a left fixed plate 101 and a right fixed plate 102 arranged symmetrically. The area of ​​the moving plate 2 is smaller than that of the fixed plate 1, and the moving plate 2 can move relative to the fixed plate 1. In the initial state, the area of ​​the moving plate 2 facing the left fixed plate 101 and the right fixed plate 102 is equal. The moving plate 2 and the left fixed plate 101 form the left capacitor, and the moving plate 2 and the right fixed plate 102 form the right capacitor. The initial capacitances of the left capacitor and the right capacitor are equal. All fixed plates 1 are fixed on the same fixed plate 3.

[0043] The calibration module is used to change the horizontal displacement x of the moving plate under the condition that the vertical displacement y=0, record the correspondence between the capacitance change ΔC of the capacitor unit and the horizontal displacement x, and fit the area change coefficient k; under the condition that the horizontal displacement x=0, change the vertical displacement y of the moving plate, record the correspondence between the capacitance and ΣC of the left and right capacitors and the vertical displacement y, verify the linearity, and determine the initial spacing parameters.

[0044] The carrier excitation module is used to apply a carrier wave to the moving electrode plate;

[0045] The capacitance detection and synchronous demodulation circuit is used to multiply and demodulate the modulation signals output from the left and right fixed plates and then perform low-pass filtering to obtain a voltage that is proportional to the left and right capacitors.

[0046] The processor is used to calculate the capacitance change ΔC and the total capacitance ΣC, and to calculate the horizontal displacement x and vertical displacement y based on the parameters obtained from the calibration module.

[0047] Where N≥2, the total plate area composed of all fixed and moving plates remains unchanged, in order to improve the relative capacitance change rate and measurement sensitivity.

[0048] For details, see Figure 1c and Figure 2 The connection relationships and principles of each device in this embodiment are as follows:

[0049] In this embodiment, N sets of capacitor units are connected in parallel to keep the total area unchanged. A single large capacitor is divided into N sets of capacitor units arranged in the same plane and in the same direction to improve the response under small displacement.

[0050] Drive end: The carrier generator produces -V0 (negative phase carrier), which is directly connected to the moving plate of all capacitor units.

[0051] Sensing end: When the moving electrode plate moves, it simultaneously changes the relationship with the left fixed electrode plate array (L1…L…). n ) and the right-side fixed plate array (R1…R n The capacitors between the two electrodes (C_left and C_right) form a differential pair: as one increases, the other decreases. All left-side stationary plates are connected together to form the left-channel detection node; all right-side stationary plates are connected together to form the right-channel detection node.

[0052] Signal detection and demodulation (two symmetrical paths):

[0053] Left channel: All current / voltage signals induced on the left fixed plate and modulated by the capacitor enter the multiplier ⊗, are demodulated by the low-pass filter LPF to filter out the high-frequency components of the carrier, and then sent to amplifier A for amplification. Finally, the output is a voltage signal +Vout that is proportional to (C_left - C_right).

[0054] Right channel: All signals on the right-side fixed plate undergo the same process as the left channel (multiplier ⊗ → low-pass filter LPF → amplifier A), outputting a voltage signal -Vout that is inversely phase to the left channel signal.

[0055] Final Output: The final output of the circuit is a pair of differential signals, +Vout and -Vout. Subtracting these two signals (+Vout - (-Vout) = 2Vout) yields double the output amplitude and a higher common-mode rejection ratio, further improving measurement accuracy and anti-interference capability.

[0056] Brief description of working principle: The circuit uses carrier modulation technology to encode minute changes in capacitance into the amplitude of a high-frequency carrier signal, and then decodes the information using synchronous demodulation (multiplier + LPF) technology. This method can greatly suppress the amplifier's own DC drift and external interference.

[0057] Specifically:

[0058] In a variable-area capacitive displacement sensor, it consists of a fixed electrode and a movable electrode, such as... Figure 1a and Figure 1b As shown. Two fixed plates, with the moving plate connected to a +V signal. When the moving plate is in the center position, the capacitance expression is:

[0059] ;

[0060] The total dielectric constant is Let d be the area of ​​the fixed plate and the moving plate facing each other on one side, d be the initial plate spacing, L be the length of the moving plate, and W be the width of the moving plate.

[0061] A set of capacitor units is arranged in a straight line on the same plane. Initially, the moving plate is located at the center, with an area equal to that of the two fixed plates on the left and right. At this time, the capacitance values ​​of the left and right capacitors are:

[0062] ;

[0063] When the moving plate moves to the right If the area of ​​the two capacitors facing each other is changed, the area changes linearly:

[0064] ;

[0065] ;

[0066] This represents the area of ​​the left-side fixed plate and moving plate facing each other. This represents the area of ​​the right-side fixed plate and moving plate facing each other.

[0067] At this point, the left capacitor and the right capacitor are respectively:

[0068] ;

[0069] ;

[0070] When the moving plate moves downwards simultaneously The spacing between the two capacitors was changed, and now the capacitances of the left and right capacitors are respectively:

[0071] ;

[0072] ;

[0073] When the displacement change is small, the change in capacitance also decreases, resulting in a weak measurement signal, which poses a significant challenge to subsequent signal processing.

[0074] To address this problem, this embodiment proposes a detection method to improve sensitivity: while maintaining the total area of ​​the electrodes, the original single-group fixed-plate-moving-plate structure is divided into N groups of independent small capacitor units, and these N groups are arranged in a straight line on the same plane, such as... Figure 1c As shown, the left and right capacitors are as follows:

[0075] ;

[0076] ;

[0077] By setting multiple sets of capacitor pairs, this invention can increase the relative rate of change of capacitance by N times under the same displacement conditions. In traditional variable area differential capacitive displacement sensors, if the total capacitance is C, the corresponding capacitance change is ΔC, and the sensor's sensitivity is mainly determined by the ratio ΔC / C. When the total capacitance C is large (e.g., C=10pF), the ΔC caused by the same displacement is small (e.g., ΔC=0.1pF), and the relative change is only 1%, making it difficult for the detection circuit to achieve high-precision resolution. By splitting the original single large capacitor structure into N parallel small capacitor units, the capacitance value of each unit is C / N, while the absolute capacitance change ΔC caused by displacement remains unchanged. Thus, the relative rate of change of each small capacitor unit is increased to N times, i.e., N·(ΔC / C), thereby significantly enhancing the detectability of capacitance changes, obtaining more obvious output signal changes under the same displacement, and effectively improving the sensor's sensitivity and measurement accuracy.

[0078] That is, with the total area remaining constant and readouts being combined in parallel, ΔC / C remains unchanged; if independent readouts are used for individual cells and combined at the signal level, the output signal-to-noise ratio is expected to improve by approximately N times, assuming noise is approximately independent. Cellular readouts can also lead to uniformity in process / stress / edge field and improved manufacturability of layout routing.

[0079] The advantage of this structure is that, theoretically, the relative rate of change of each small capacitor unit can be N times that of the original single large capacitor structure when a tiny displacement occurs. This significantly enhances the signal strength detected by subsequent circuits, thereby improving the response capability (i.e., sensitivity) to tiny displacements.

[0080] In the calibration module, the horizontal displacement x and vertical displacement y are decoupled through calibration, and the capacitance expression is:

[0081] ;

[0082] ;

[0083] ;

[0084] ;

[0085] , , and These are the calibration values ​​for the left and right capacitors under the conditions of x=0 and y=0 for the moving plate, respectively.

[0086] It can be seen that the vertical displacement y is caused by The decision is made because the effect of x is canceled out; the horizontal displacement x is determined by... The decision is made by normalizing the effect of y, where k is the area variation coefficient and d is the initial electrode spacing.

[0087] Through experimental calibration, the relationship between horizontal displacement x and differential capacitance signal, and the relationship between vertical displacement y and total capacitance are established.

[0088] With the moving plate fixed at y=0 in the vertical direction, move the moving plate horizontally and record the values ​​corresponding to different x. and Fit x and The relationship curve is used to determine the proportionality coefficient k:

[0089] ;

[0090] With the horizontal displacement x=0, move the moving plate only vertically and record the displacement y and the corresponding value. ,verify and Linear relationship:

[0091] ;

[0092] Determined by fitting The accurate value.

[0093] Simultaneously apply known x and y displacements, and record... and Calculate x and y using the calibration formula:

[0094] ;

[0095] ;

[0096] The circuit section employs coherent demodulation technology to completely eliminate the carrier component while amplifying the displacement-related useful signal. A high-frequency carrier is applied to the moving electrode, and the modulation signals output by the left and right fixed electrodes are:

[0097] ;

[0098] ;

[0099] Where m is the C / V conversion gain, the C / V conversion unit converts the weak AC current signal induced by the stationary plate into a voltage signal, and the conversion gain m is determined by the carrier excitation amplitude, frequency, and feedback resistor.

[0100] Multiplying the output signals of the left and right fixed plates by the inverted carrier wave yields:

[0101] ;

[0102] ;

[0103] The carrier fundamental frequency ω is completely eliminated, retaining only the DC component and the second harmonic. A low-pass filter (cutoff frequency ≪ 2ω) filters out the 2ω high-frequency components, resulting in the final output:

[0104] ;

[0105] ;

[0106] At this point, the carrier wave disappears completely, and the signal is only proportional to the capacitance C.

[0107] A multiplier is used to multiply the voltage modulation signal output from the capacitor detection by an inverse carrier wave. When a positive voltage is applied to the plates, the voltage modulation signals output from the left and right stator boards are multiplied by the signal with the inverse positive voltage, thus suppressing the carrier wave and amplifying the beneficial signal.

[0108] Example 2

[0109] This embodiment provides a displacement and spacing measurement method based on a variable area capacitive sensor, including:

[0110] S1. Arrange at least two sets of capacitor units in one direction on the same plane. Initially, the moving plate is located in the middle of the two fixed plates, so that the facing areas of the left and right capacitors are equal. The total plate area remains unchanged. The original single capacitor pair is split into N sets of parallel capacitor units, so that the relative change rate of each set of capacitor units is increased to N times the original under the same displacement conditions.

[0111] S2. Apply carrier excitation to the moving plate, collect the modulation signals output from the left and right fixed plates, and multiply and demodulate them with the carrier, then pass them through a low-pass filter to obtain voltage signals proportional to the capacitance values ​​of the left and right plates; multiply the left and right modulation voltage signals with the inverted carrier to suppress the carrier component, and then pass them through a low-pass filter to obtain DC signals proportional to the capacitance C.

[0112] S3. Calculate the capacitance change ΔC and the sum of capacitance ΣC based on the left and right capacitance values ​​obtained in step S2;

[0113] S4 calls the calibrated proportional coefficient and initial spacing parameters, calculates the horizontal displacement x based on ΔC, and the vertical displacement y based on ΣC, and outputs x and y. The horizontal displacement x is determined by the linear relationship between the capacitance change ΔC and the area change coefficient k, while the vertical displacement y is determined by the functional relationship between capacitance, ΣC, and the plate spacing. Normalization is used to cancel out the influence of x on y. Calibration includes: changing x with y=0, recording the correspondence between capacitance change ΔC and x to fit k; changing y with x=0, recording the correspondence between capacitance, ΣC, and y to verify linearity and determine the initial spacing parameters.

[0114] In this embodiment, the sensitivity of capacitance change ΔC to the horizontal direction is independent of the sensitivity of capacitance and ΣC to the vertical direction, thereby suppressing the interference of vertical displacement on horizontal measurement under vibration environment.

[0115] In one embodiment, the variable area capacitive sensor displacement and spacing measurement device and method are used for precise displacement detection and are adapted to high-speed dynamic measurement scenarios.

[0116] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A displacement and spacing measurement device for a variable area capacitive sensor, characterized in that, include: The capacitor structure consists of N sets of capacitor units arranged in parallel along a straight line on the same plane. Each set of capacitor units consists of a fixed plate and a moving plate arranged opposite and parallel to each other. The fixed plate consists of a left fixed plate and a right fixed plate arranged symmetrically. The area of ​​the moving plate is smaller than that of the fixed plate, and the moving plate can move relative to the fixed plate. In the initial state, the area of ​​the moving plate facing the left and right fixed plates is equal. The moving plate and the left fixed plate form the left capacitor, and the moving plate and the right fixed plate form the right capacitor. The initial capacitances of the left and right capacitors are equal. The calibration module is used to change the horizontal displacement x of the moving plate under the condition that the vertical displacement y=0, record the correspondence between the capacitance change ΔC of the capacitor unit and the horizontal displacement x, and fit the area change coefficient k; under the condition that the horizontal displacement x=0, change the vertical displacement y of the moving plate, record the correspondence between the total capacitance ΣC of the left and right capacitors and the vertical displacement y, verify the linearity and determine the initial spacing parameters. The carrier excitation module is used to apply a carrier wave to the moving electrode plate; The capacitance detection and synchronous demodulation circuit is used to multiply and demodulate the modulation signals output from the left and right fixed plates and then perform low-pass filtering to obtain a voltage that is proportional to the left and right capacitors. The processor is used to calculate the capacitance change ΔC and the total capacitance ΣC, and to calculate the horizontal displacement x and vertical displacement y based on the parameters obtained from the calibration module. Where N≥2, the total plate area composed of all fixed and moving plates remains unchanged, so as to improve the relative capacitance change rate and measurement sensitivity. The processor is configured to normalize ΔC when outputting horizontal displacement x to offset the influence of vertical displacement y, and to suppress the influence of horizontal displacement x by using the sum of capacitance ΣC when outputting vertical displacement y.

2. The displacement and spacing measuring device of a variable area capacitive sensor according to claim 1, characterized in that, The capacitance detection and synchronous demodulation circuit includes a multiplier, a low-pass filter, and a C / V conversion unit, which can suppress the carrier wave and output a DC signal proportional to the capacitance value.

3. A method for measuring displacement and spacing based on a variable-area capacitive sensor, wherein the method is based on the variable-area capacitive sensor displacement and spacing measuring device according to any one of claims 1-2, characterized in that, include: S1. Arrange at least two sets of capacitor units in one direction on the same plane. Initially, the moving plate is located in the middle of the two fixed plates, so that the facing areas of the left and right capacitors are equal. S2. Apply carrier excitation to the moving plate, collect the modulation signals output from the left and right fixed plates, multiply and demodulate them with the carrier respectively, and then filter them with a low-pass filter to obtain voltage signals that are proportional to the capacitance values ​​of the left and right plates. S3. Calculate the capacitance change ΔC and the total capacitance ΣC based on the capacitance values ​​on the left and right sides obtained in step S2; S4 calls the calibrated area change coefficient k and initial spacing parameters, calculates the horizontal displacement x based on ΔC, calculates the vertical displacement y based on ΣC, and outputs x and y. The calculation process satisfies the following: the horizontal displacement x is determined by the linear relationship between the capacitance change ΔC and the area change coefficient k, the vertical displacement y is determined by the functional relationship between the capacitance, ΣC and the plate spacing, and the influence of y on x is canceled out by normalization.

4. The displacement and spacing measurement method based on a variable area capacitive sensor according to claim 3, characterized in that, In step S1, the total plate area remains unchanged, and the original single capacitor pair is split into N groups of parallel capacitor units, so that the relative change rate of each group of capacitor units is increased to N times the original under the same displacement conditions.

5. The displacement and spacing measurement method based on a variable area capacitive sensor according to claim 3, characterized in that, Step S2 synchronous demodulation includes: multiplying the left and right modulation voltage signals by the inverted carrier to suppress the carrier component, and then passing them through a low-pass filter to obtain a DC signal proportional to the capacitor C.

6. The displacement and spacing measurement method based on a variable area capacitive sensor according to claim 3, characterized in that, Calibration includes: With y=0, change x and record the correspondence between the capacitance change ΔC and x to obtain k; with x=0, change y and record the correspondence between capacitance and ΣC and y to verify linearity and determine the initial spacing parameter.

7. The displacement and spacing measurement method based on a variable area capacitive sensor according to claim 3, characterized in that, By utilizing the fact that the sensitivity of capacitance change ΔC to the horizontal direction is independent of the sensitivity of capacitance and ΣC to the vertical direction, interference of vertical displacement on horizontal measurement under vibration environment can be suppressed.

8. The displacement and spacing measurement method based on a variable area capacitive sensor according to claim 3, characterized in that, Used for precision displacement detection and adapted to high-speed dynamic measurement scenarios.

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