A planar two-dimensional time grating displacement sensor based on electric field modulation

Abstract

This invention discloses a planar two-dimensional time-grating displacement sensor based on electric field modulation, belonging to the field of measurement and sensing technology. A sensing unit group consisting of four sensing units is disposed on a moving scale substrate. Each sensing unit comprises an excitation electrode and a sensing electrode. The excitation electrodes are staggered along the X and Y directions and connected to form an N-phase excitation electrode group. The sensing electrode is arranged in the gaps formed by the excitation electrodes, and all sensing electrodes within the same sensing unit are electrically connected to form a sensing signal output terminal. Multiple modulation units are disposed on a fixed scale substrate, forming a planar capacitive coupling structure with the excitation and sensing electrodes. When the moving scale substrate moves relative to the fixed scale substrate, the modulation units cause the capacitance value of the planar capacitor to change alternately. In this invention, both the input and output signals are located on the moving scale substrate, eliminating the need for leads on the fixed scale substrate. This effectively reduces signal attenuation problems caused by lead resistance, capacitance, and parasitic parameters, improving the sensor signal stability and transmission efficiency.

Description

Technical Field

[0001] This invention relates to precision displacement measurement, specifically to a planar two-dimensional time-grating displacement sensor based on electric field modulation, belonging to the field of measurement and sensing technology. Background Technology

[0002] Two-dimensional planar displacement sensors are widely used in CNC machine tools, precision machining platforms, semiconductor manufacturing equipment, and high-end testing equipment. Currently, two-dimensional planar displacement measurement mainly employs grating or magnetic grating sensing technologies. Grating measurement technology obtains position information by detecting the relative displacement between grating lines, offering high resolution and good repeatability. However, this technology relies on high-precision grating manufacturing processes, and its measurement performance is limited by the grating period and the precision of the subdivision circuit. It also requires high standards for installation parallelism, orthogonality, and environmental cleanliness, and is susceptible to the effects of dust, oil, vibration, and temperature changes, limiting its long-term stability in complex industrial environments. Magnetic grating measurement technology achieves displacement measurement by detecting changes in the magnetic field between a magnetic pole array and a magnetic sensing element, offering advantages such as relatively simple structure and strong resistance to contamination. However, its measurement accuracy is limited by the precision of magnetic pole machining, magnetic field uniformity, and the performance of the magnetic sensing element, posing certain limitations in high-precision two-dimensional planar measurement applications. Furthermore, external magnetic field interference and temperature drift can also affect the stability of the measurement results. The capacitive planar two-dimensional time grating sensor (publication number CN109631735A) has the potential to overcome the limitations of traditional optical gratings and magnetic gratings in terms of processing technology and environmental adaptability due to its non-contact measurement, relatively simple structure and strong environmental adaptability. It has the potential to achieve high-resolution measurement.

[0003] However, capacitive planar two-dimensional time grating sensors still have shortcomings in terms of signal coupling efficiency, structural layout, and adaptability to large-stroke applications. Therefore, it is extremely important to propose a capacitive planar time grating sensing scheme that is structurally sound, provides stable signals, and is suitable for large-range, high-precision planar two-dimensional displacement measurement. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a planar two-dimensional time-grating displacement sensor based on electric field modulation. This invention only requires the detection of the output signal of the sensing electrode on the moving scale substrate, eliminating the need to establish a complex capacitive coupling network between the moving and fixed scales. This reduces the dependence on multiple sets of signal leads and effectively reduces the signal attenuation problem caused by lead resistance, capacitance, and parasitic parameters, thereby improving the signal stability and transmission efficiency of the sensor under long-stroke measurement conditions.

[0005] The technical solution of this invention is implemented as follows:

[0006] A planar two-dimensional time-grating displacement sensor based on electric field modulation includes a moving scale base and a fixed scale base, which are installed parallel to each other with a gap. A sensing unit group is arranged on the upper surface of the moving scale base. The sensing unit group consists of four identical sensing units arranged in a 2×2 array. The sensing units are arranged in a differential structure in space to construct a differential signal, thereby realizing the decoupled calculation of displacement in the X and Y directions.

[0007] Each sensing unit consists of several excitation electrodes and sensing electrodes, all of the same shape and size. The excitation electrodes are staggered along the X and Y directions, with uniform and equal spacing in both directions. Several excitation groups formed by the X-direction excitation electrodes and several excitation groups formed by the Y-direction excitation electrodes are connected to each other, thereby forming an N-phase excitation electrode group of the sensing unit, where N is an integer greater than or equal to 3. All N-phase excitation electrode groups of the sensing units are connected in the same phase to form an N-phase excitation electrode group of the sensing unit group. The sensing electrodes are arranged in at least part of the gaps formed by the excitation electrodes. The distance between any sensing electrode and its adjacent excitation electrode is I. All sensing electrodes in the same sensing unit are electrically connected to form a sensing signal output terminal, thus forming four sensing signal output terminals in one sensing unit group. The excitation electrodes and sensing electrodes constitute a capacitive coupling structure to form an electric field distribution that varies with displacement.

[0008] The lower surface of the fixed-length substrate is provided with multiple modulation units of the same shape and size arranged in an array. The modulation units are used to form a planar capacitive coupling structure with the excitation electrode and the sensing electrode, so as to cause a change in coupling capacitance when the moving scale substrate moves relative to the fixed-length substrate. The length and width of each sensing unit are both W, and the distance between adjacent sensing units is L, L=(k+0.5)W, where k is a non-negative integer, and the value of k satisfies that the overall size of the sensing unit group is less than or equal to the overall size of all modulation units.

[0009] Furthermore, there are multiple identical sensing unit groups. Among the sensing units included in all sensing unit groups, the interval L between any two sensing units satisfies L=(k+0.5)W. The sensing signal output terminals of the sensing units corresponding to the array positions in all sensing unit groups are connected together to serve as the sensing output of that array position. The N-phase excitation electrode groups of the sensing units corresponding to the array positions in all sensing unit groups are connected together to serve as the corresponding phase excitation input.

[0010] Furthermore, the sensing electrodes are arranged in all the gaps formed by the excitation electrodes, including the edge gaps, and all the sensing electrodes and excitation electrodes are arranged uniformly in a matrix as a whole, with a spacing of I between any two adjacent electrodes.

[0011] Furthermore, in each sensing unit, the excitation electrodes are arranged in 8m rows along the upper surface of the fixed-length substrate, with a distance of I between adjacent rows of excitation electrodes; each row of excitation electrodes consists of 4n identical excitation plates evenly arranged along the X direction, the excitation plates being squares with a side length of W1, and the distance between two adjacent excitation plates in each row being W1+2I; the starting positions of adjacent rows of excitation electrodes are staggered along the X direction by a distance of W1+I; the starting positions of odd-numbered rows of excitation electrodes are the same along the X direction, and the starting positions of even-numbered rows of excitation electrodes are the same along the X direction; where n and m are both positive integers;

[0012] In the excitation electrode array consisting of all even-numbered rows of excitation electrodes, all excitation electrodes in each row are connected to form a row excitation group; thus forming a 4m row excitation group; starting from the first row, every 4 rows form a cycle, which are respectively called the Y1 row excitation group, the Y2 row excitation group, the Y3 row excitation group, and the Y4 row excitation group;

[0013] In the excitation electrode array consisting of all odd-numbered rows of excitation electrodes, all excitation electrodes in each column are connected to form a column excitation group; thus forming 4n column excitation groups; starting from the first column, every 4 columns form a cycle, which are respectively called the X1 column excitation group, X2 column excitation group, X3 column excitation group and X4 column excitation group;

[0014] All X1 column excitation groups and all Y1 row excitation groups are connected to form phase A excitation electrode group; all X2 column excitation groups and all Y2 row excitation groups are connected to form phase B excitation electrode group; all X3 column excitation groups and all Y3 row excitation groups are connected to form phase C excitation electrode group; all X4 column excitation groups and all Y4 row excitation groups are connected to form phase D excitation electrode group.

[0015] Furthermore, the modulation unit is square with a side length of W / 2; the spacing between adjacent modulation units is W / 2.

[0016] Furthermore, the modulation unit is made of a different material than the fixed-length substrate, and the upper surface of the modulation unit is flush with the upper surface of the fixed-length substrate.

[0017] Furthermore, the upper surface of the modulation unit is higher than the upper surface of the fixed-length substrate.

[0018] Furthermore, a recess is formed on the fixed-length substrate at a position corresponding to the modulation unit. The depth of the recess is greater than the thickness of the modulation unit. The modulation unit is installed in the recess, and the upper surface of the modulation unit is lower than the upper surface of the fixed-length substrate.

[0019] Furthermore, a through hole is made on the fixed-length substrate at the position corresponding to the modulation unit, and the air in the through hole constitutes the modulation unit.

[0020] Furthermore, a recess is formed on the fixed-length substrate at the position corresponding to the modulation unit. The portion of the fixed-length substrate corresponding to the orthographic projection of the recess constitutes the modulation unit, or the air inside the recess constitutes the modulation unit, or the portion of the fixed-length substrate corresponding to the orthographic projection of the recess and the air inside the recess together constitute the modulation unit.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] In this invention, the signal transmission units of the sensor are all located on the moving scale substrate, enabling passive sensing of the fixed scale. This invention only requires detection of the output signal from the sensing electrodes on the moving scale substrate, eliminating the need for a complex capacitive coupling network between the moving and fixed scales. This reduces reliance on multiple signal leads and effectively mitigates signal attenuation caused by lead resistance, capacitance, and parasitic parameters, thereby improving the sensor's signal stability and transmission efficiency under long-stroke measurement conditions.

[0023] This invention achieves non-contact measurement based on a planar capacitor structure, without relying on optical or magnetic components. This avoids the problems of optical systems being susceptible to interference from dust, oil, and ambient light, and also avoids the problem of magnetic field measurement being susceptible to interference from external magnetic fields, thereby improving the environmental adaptability and operational reliability of the sensor.

[0024] The present invention has a relatively simple structure, and the electrode structure is easy to implement using printed circuit boards or micro / nano fabrication processes, which helps to reduce manufacturing costs and improve the consistency and repeatability of the sensor. At the same time, this structure facilitates large-area array deployment, thereby enabling two-dimensional displacement measurement over a large range.

[0025] The sensor of this invention has the advantages of simple structure, stable signal, strong anti-interference ability, suitability for long-stroke measurement and easy implementation of high-precision measurement, and has good prospects for engineering application. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the installation of the moving scale base and the fixed scale base in Example 1.

[0027] Figure 2 This is a schematic diagram showing the spatial positional correspondence between the moving scale base and the fixed scale base in Example 1.

[0028] Figure 3 This is a schematic diagram of the structure of the moving ruler base in Example 1.

[0029] Figure 4 This is a schematic diagram of the structure of the fixed-length base in Example 1.

[0030] Figure 5 This is a flowchart of the signal processing in Example 1.

[0031] Figure 6This is a schematic diagram of the structure of the fixed-length base in Example 2.

[0032] Figure 7 This is a schematic diagram of the structure of the fixed-length base in Example 3.

[0033] Figure 8 This is a schematic diagram of the structure of the fixed-length base in Example 4.

[0034] Figure 9 This is a schematic diagram of the structure of the fixed-length base in Example 5.

[0035] Figure 10 This is a schematic diagram of the structure of the fixed-length base in Example 6.

[0036] Figure 11 This is a schematic diagram of the structure of the fixed-length base in Example 7.

[0037] Figure 12 This is a schematic diagram showing the full coverage arrangement of the sensing electrodes in the sensing unit in Example 8.

[0038] Figure 13 This is a schematic diagram of the shape of the modulation unit on the fixed-length substrate in Example 9.

[0039] Figure 14 This is a schematic diagram of the shape of the modulation unit on the fixed-length substrate in Example 10.

[0040] Figure 15 This is a schematic diagram of the shape of the modulation unit on the fixed-length substrate in Example 11.

[0041] Figure 16 This is a schematic diagram of the shape of the modulation unit on the fixed-length substrate in Example 12.

[0042] Figure 17 This is a schematic diagram of the shape of the modulation unit on the fixed-length substrate in Example 13.

[0043] Figure 18 This is a schematic diagram of the shapes of the excitation electrode and the induction electrode on the moving scale substrate in Example 14.

[0044] Figure 19 This is a schematic diagram of the shapes of the excitation electrode and the induction electrode on the moving scale substrate in Example 15.

[0045] Figure 20 This is a schematic diagram of the shapes of the excitation electrode and the induction electrode on the moving scale substrate in Example 16.

[0046] Figure 21 This is a schematic diagram of the shapes of the excitation electrode and the induction electrode on the moving scale substrate in Example 17.

[0047] Wherein, 1 is the moving scale substrate; 1-1 is the excitation electrode; 1-2 is the sensing electrode; 2 is the fixed scale substrate; and 2-1 is the modulation unit. Detailed Implementation

[0048] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0049] Example 1: As Figure 1 and Figure 2 As shown, a planar two-dimensional time-grating displacement sensor based on electric field modulation includes a fixed-scale base 2 and a movable-scale base 1. The upper surface of the fixed-scale base 2 is installed parallel to and directly opposite the lower surface of the movable-scale base 1, with a gap of Z=3mm.

[0050] like Figure 3 As shown, a sensing unit group is arranged on the upper surface of the moving scale base 1. The sensing unit group consists of four identical sensing units arranged in a 2×2 array. The sensing units are arranged in a differential structure in space to construct a differential signal, thereby realizing the decoupled calculation of displacement in the X and Y directions. The length and width of each sensing unit are both W, and the distance between adjacent sensing units is L, so that they form a differential structure, where L=(k+0.5)W, and k is a non-negative integer.

[0051] Each sensing unit consists of several excitation electrodes and sensing electrodes, all of which are identical in shape and size. In Example 1, both the excitation and sensing electrodes are square with a side length of W1. The excitation electrodes are staggered along the X and Y directions, with uniform and equal spacing in both directions. Several excitation groups formed by the X-direction excitation electrodes and several excitation groups formed by the Y-direction excitation electrodes are connected to each other, thereby forming an N-phase excitation electrode group, where N is an integer greater than or equal to 3. The N-phase excitation electrode groups of all sensing units are connected in the same phase to form the N-phase excitation electrode group of the sensing unit group. The sensing electrodes are arranged in at least part of the gaps formed by the excitation electrodes, with a spacing of I between any sensing electrode and its adjacent excitation electrode. All sensing electrodes within the same sensing unit are electrically connected to form a sensing signal output terminal, thus forming four sensing signal output terminals in one sensing unit group. The excitation electrode 1-1 and the sensing electrode 1-2 constitute a capacitive coupling structure to form an electric field distribution that varies with displacement.

[0052] In Example 1, see Figure 3 Each sensing unit has 8 rows of excitation electrodes arranged side by side along the upper surface of the fixed-length substrate, with a distance of I between two adjacent rows of excitation electrodes. Each row of excitation electrodes consists of 4 identical excitation plates evenly arranged along the X direction, with a distance of W1+2I between two adjacent excitation plates in each row. The starting positions of two adjacent rows of excitation electrodes are staggered along the X direction by a distance of W1+I. The starting positions of the excitation electrodes in odd-numbered rows are the same along the X direction, and the starting positions of the excitation electrodes in even-numbered rows are the same along the X direction.

[0053] In the excitation electrode array consisting of all even-numbered rows of excitation electrodes, all excitation electrodes in each row are connected to form a row excitation group; thus forming 4 rows of row excitation groups; starting from the first row, every 4 rows form a cycle, which are respectively called the Y1 row excitation group, the Y2 row excitation group, the Y3 row excitation group and the Y4 row excitation group.

[0054] In the excitation electrode array consisting of all odd-numbered rows of excitation electrodes, all excitation electrodes in each column are connected to form a column excitation group; thus forming 4 column excitation groups; starting from the first column, every 4 columns form a cycle, which are respectively called the X1 column excitation group, the X2 column excitation group, the X3 column excitation group, and the X4 column excitation group.

[0055] All X1 column excitation groups and all Y1 row excitation groups are connected to form phase A excitation electrode group; all X2 column excitation groups and all Y2 row excitation groups are connected to form phase B excitation electrode group; all X3 column excitation groups and all Y3 row excitation groups are connected to form phase C excitation electrode group; all X4 column excitation groups and all Y4 row excitation groups are connected to form phase D excitation electrode group.

[0056] Each sensing unit's excitation electrode is connected as described above to form four-phase excitation electrode groups (A, B, C, and D). The sensing unit group thus obtains four A-phase excitation electrode groups, four B-phase excitation electrode groups, four C-phase excitation electrode groups, and four D-phase excitation electrode groups. These four A-phase, B-phase, C-phase, and D-phase excitation electrode groups are connected together with corresponding phases to ultimately form the A-phase, B-phase, C-phase, and D-phase excitation electrode groups of the sensing unit group. Specifically, four A-phase excitation electrode groups are connected together to form the A-phase excitation electrode groups of the sensing unit group; four B-phase excitation electrode groups are connected together to form the B-phase excitation electrode groups of the sensing unit group; four C-phase excitation electrode groups are connected together to form the C-phase excitation electrode groups of the sensing unit group; and four D-phase excitation electrode groups are connected together to form the D-phase excitation electrode groups of the sensing unit group.

[0057] like Figure 4 As shown, the lower surface of the fixed-length substrate 2 is provided with multiple modulation units 2-1 of the same shape and size, arranged in an array. The value of k must simultaneously satisfy the condition that the overall size of the sensing unit group is less than or equal to the overall size of all modulation units. In Embodiment 1, there are 9 modulation units arranged in a 3×3 array. The modulation unit 2-1 is square with a side length of W / 2, and the spacing between adjacent modulation units is W / 2. The excitation electrode, sensing electrode, and modulation unit form a planar capacitive coupling structure.

[0058] The size and spacing of the modulation units ensure that their spatial period exactly covers half of the spatial period of the sensing units. This allows for periodic, stable differential electric field modulation with consistent characteristics in both directions during relative movement between the fixed and moving scale substrates. Because the modulation units and gaps are of equal width, the modulation structure exhibits half-cycle complementary symmetry, which enhances the fundamental modulation component and suppresses even-order spatial harmonics, thereby improving the sinusoidal nature of the induced signal and reducing periodic measurement errors caused by harmonics. More importantly, the spatial period of the modulation units and the spatial periods of adjacent sensing units are mapped onto the plane as overlapping areas, creating a half-cycle phase difference between the differentially arranged sensing units. This facilitates the acquisition of inverted signals and differential processing, improving the output signal amplitude, common-mode interference suppression capability, and the stability and accuracy of two-dimensional displacement measurement.

[0059] During measurement, four equal-amplitude, same-frequency sinusoidal excitation signals S+=A, with a phase difference of π / 2, are sequentially applied to the four-phase excitation electrode groups A, B, C, and D. m sin(2πωt), C+=A m cos(2πωt), S-=-A m sin(2πωt), C - = -A m cos(2πωt), where A m Let ω be the amplitude of the excitation signal, ω be the frequency of the excitation signal, and t be time. At this time, the excitation electrode 1-1, the sensing electrode 1-2, and the modulation unit 2-1 form a planar capacitive coupling structure. When the moving scale base 1 is displaced relative to the fixed scale base 2 in the X and / or Y directions, the four sensing signal output terminals formed by the connection of the sensing electrodes 1-2 of each sensing unit output corresponding sensing signals U1, U2, U3, and U4. The phase of the sensing signals output by each sensing unit changes with the displacement value.

[0060]

[0061] Where A o y is the voltage amplitude of the output signal coupled between the excitation electrode 1-1 and the modulation electrode 2-1 of the sensing electrode 1-2; x and y are the displacements of the moving scale base 1 relative to the fixed scale base 2 in the X and Y directions, respectively.

[0062] The induction signals U1, U2, U3, and U4 output from the four sets of sensing units are combined, decoupled, and processed to obtain the displacement output signal U when the moving scale base 1 moves along the X and Y directions. X and U Y :

[0063]

[0064] like Figure 5 As shown, the displacement output signal UX and U Y After being shaped into a square wave by the shaping circuit, the phase is interpolated and counted by the high-frequency pulse signal. After the displacement is converted by the phase interpolation number, the displacement measurement values ​​of the moving scale base 1 in the X and Y directions can be obtained.

[0065] Example 2: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 6 As shown, the material of the modulation unit 2-1 is different from that of the fixed-length base 2, and the upper surface of the modulation unit 2-1 and the upper surface of the fixed-length base 2 are not on the same plane. The upper surface of the modulation unit 2-1 has an outward convex structure relative to the upper surface of the fixed-length base 2. In this embodiment, the outward convex structure can be achieved by directly mounting the modulation unit on the upper surface of the fixed-length base.

[0066] Example 3: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 7 As shown, the material of the modulation unit 2-1 is different from that of the fixed-length base 2, and the upper surface of the modulation unit 2-1 and the upper surface of the fixed-length base 2 are both located on the same plane. In this embodiment, a recess can be made on the fixed-length base at the position corresponding to the modulation unit, the depth of the recess being equal to the thickness of the modulation unit, and then the modulation unit can be installed in the recess to be flush with the surface of the fixed-length base.

[0067] Example 4: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 8 As shown, the material of the modulation unit 2-1 is different from that of the fixed-length base 2, and the upper surfaces of the modulation unit 2-1 and the fixed-length base 2 are not on the same plane. The upper surface of the modulation unit 2-1 has a concave structure relative to the upper surface of the fixed-length base 2. In this embodiment, a recess can be made on the fixed-length base at the position corresponding to the modulation unit, the depth of the recess being greater than the thickness of the modulation unit. Then, the modulation unit is installed in the recess, so that the surface of the modulation unit is lower than the surface of the fixed-length base.

[0068] Example 5: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 9 As shown, a through hole is directly opened on the fixed-length base at the position corresponding to the modulation unit. The air in the through hole constitutes the modulation unit. In this way, the material of the modulation unit 2-1 is different from the material of the fixed-length base 2.

[0069] Example 6: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 10 As shown, the modulation unit 2-1 is made of the same material as the fixed-length base 2, and the upper surface of the modulation unit 2-1 and the upper surface of the fixed-length base 2 are not on the same plane. The upper surface of the modulation unit 2-1 has an outward convex structure relative to the upper surface of the fixed-length base 2. In this embodiment, the modulation unit can be integrally formed with the fixed-length base, or the modulation unit can be processed first and then installed on the upper surface of the fixed-length base.

[0070] Example 7: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 11 As shown, the material of the modulation unit 2-1 is the same as that of the fixed-length base 2, and the upper surface of the modulation unit 2-1 and the upper surface of the fixed-length base 2 are not on the same plane. The upper surface of the modulation unit 2-1 has a concave structure relative to the upper surface of the fixed-length base 2. With this structure, a recess can be directly made on the fixed-length base, and the modulation unit is the part of the fixed-length base corresponding to the orthographic projection of the recess.

[0071] Example 8: This example describes a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that: Figure 12 As shown, the sensing electrodes 1-2 are arranged in all the gaps formed by the excitation electrodes 1-1, including the edge gaps, and the sensing electrodes 1-2 constitute the complete arrangement of the gaps between adjacent excitation electrodes. All sensing electrodes and excitation electrodes are arranged uniformly in a matrix as a whole, and the distance between any two adjacent electrodes is I.

[0072] The induction electrodes are arranged throughout the gaps formed by the excitation electrodes, ensuring stable capacitive coupling between all excitation electrodes and adjacent induction electrodes, thus significantly improving the induction area and electric field utilization. Simultaneously, the full-coverage array makes the planar electric field distribution more continuous and uniform, reducing the impact of edge electric field distortion and local electric field abrupt changes on the measurement results, and improving the output signal amplitude, signal-to-noise ratio, and spatial potential waveform quality. Furthermore, the full-gap arrangement enhances the spatial sampling density, provides a certain averaging filtering effect on higher-order spatial harmonics, and improves the sinusoidal nature of the output signal as well as the stability and consistency of two-dimensional displacement measurements.

[0073] Examples 9-13: Examples 9-13 describe a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that the cross-sectional shape of the modulation unit 2-1 is a centrally rotationally symmetric figure. Specifically, the modulation unit 2-1 in Example 9 is circular in shape, as shown below. Figure 13 As shown; in Example 10, the modulation unit 2-1 is rhomboid in shape, as... Figure 14 As shown; in Embodiment 11, the modulation unit 2-1 has a regular octagonal shape, as... Figure 15 As shown; in Example 12, the modulation unit 2-1 is shaped like a petal formed by rotating a semicircle 90°, as shown. Figure 16 As shown; in Example 13, the modulation unit 2-1 has a rectangular cross-sectional shape and is arranged in a Z-shape at intervals of W / 2, as shown. Figure 17 As shown, the same function as in Example 1 can be achieved.

[0074] Examples 14-17: Examples 14-17 describe a planar two-dimensional time-grating displacement sensor based on electric field modulation. Its measurement principle and most of its structure are the same as in Example 1, except that the cross-sectional shapes of the excitation electrode 1-1 and the sensing electrode 1-2 of the moving scale substrate 1 are centrally rotationally symmetric. Specifically, in Example 14, the cross-sectional shapes of the excitation electrode 1-1 and the sensing electrode 1-2 are circular, such as... Figure 18 As shown; in Example 15, the cross-sectional shape of the excitation electrode 1-1 and the sensing electrode 1-2 is rhomboid, as shown... Figure 19 As shown; in Example 16, the cross-sectional shape of the excitation electrode 1-1 and the sensing electrode 1-2 is a regular octagon, as shown. Figure 20 As shown; in Example 17, the cross-sectional shape of the excitation electrode 1-1 and the sensing electrode 1-2 is a petal shape formed by rotating a semicircle by 90°, as shown. Figure 21 As shown.

[0075] The sensing unit groups described in this invention can be multiple identical. In all sensing unit groups, the distance L between any two sensing units satisfies L = (k + 0.5)W. The value of k must simultaneously satisfy the condition that the overall size of all sensing unit groups is less than or equal to the overall size of all modulation units. The sensing signal output terminals of the sensing units corresponding to the array positions in all sensing unit groups are connected together to form the sensing output for that array position. For example, the sensing signal output terminals of all left-hand sensing units are connected together as one sensing output, and the sensing signal output terminals of all right-hand sensing units are connected together as one sensing output, ultimately resulting in four sensing signal output terminals. The A-phase excitation electrode groups of all sensing unit groups are connected together to form the final A-phase excitation electrode group of the sensor. Similarly, the B, C, and D phases are connected in the same way, thus obtaining the final A, B, C, and D four-phase excitation electrode groups of the sensor.

[0076] By setting up multiple identical sensing unit groups and connecting the output terminals of the corresponding array positions in each sensing unit group, similar sensing signals generated at different spatial locations can be superimposed, thereby expanding the effective sensing area and improving the output signal amplitude and signal-to-noise ratio. Simultaneously, multiple sensing unit groups can reduce the impact of local processing errors, substrate surface shape errors, and local gap variations on the measurement results through array averaging, improving the consistency, stability, and repeatability of the output signal. Furthermore, maintaining the same differential structure and excitation electrode connection relationship among the sensing unit groups can enhance the four sensing signals without altering the two-dimensional displacement decoupling principle, improving the sensor's anti-interference capability and measurement reliability.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the applicant has described the present invention in detail with reference to preferred embodiments, those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A planar two-dimensional time-grating displacement sensor based on electric field modulation, comprising a moving scale base and a fixed scale base, wherein the moving scale base and the fixed scale base are installed parallel to each other with a gap between them, characterized in that: A sensing unit group is provided on the upper surface of the moving scale substrate. The sensing unit group consists of four identical sensing units arranged in a 2×2 array. The sensing units are arranged in a differential structure in space to construct differential signals, thereby realizing the decoupled calculation of displacement in the X and Y directions. Each sensing unit consists of several excitation electrodes and sensing electrodes, all of the same shape and size. The excitation electrodes are staggered along the X and Y directions, with uniform and equal spacing in both directions. Several excitation groups formed by the X-direction excitation electrodes and several excitation groups formed by the Y-direction excitation electrodes are connected to each other, thereby forming an N-phase excitation electrode group of the sensing unit, where N is an integer greater than or equal to 3. All N-phase excitation electrode groups of the sensing units are connected in the same phase to form an N-phase excitation electrode group of the sensing unit group. The sensing electrodes are arranged in at least part of the gaps formed by the excitation electrodes. The distance between any sensing electrode and its adjacent excitation electrode is I. All sensing electrodes in the same sensing unit are electrically connected to form a sensing signal output terminal, thus forming four sensing signal output terminals in one sensing unit group. The excitation electrodes and sensing electrodes constitute a capacitive coupling structure to form an electric field distribution that varies with displacement. The lower surface of the fixed-length substrate is provided with multiple modulation units of the same shape and size arranged in an array. The modulation units are used to form a planar capacitive coupling structure with the excitation electrode and the sensing electrode, so as to cause a change in coupling capacitance when the moving scale substrate moves relative to the fixed-length substrate. The length and width of each sensing unit are both W, and the distance between adjacent sensing units is L, L=(k+0.5)W, where k is a non-negative integer, and the value of k satisfies that the overall size of the sensing unit group is less than or equal to the overall size of all modulation units.

2. The planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: The sensing unit groups are multiple identical. In all sensing unit groups, the interval L between any two sensing units satisfies L=(k+0.5)W. The sensing signal output terminals of the sensing units corresponding to the array positions in all sensing unit groups are connected together to serve as the sensing output of that array position. The N-phase excitation electrode groups of the sensing units corresponding to the array positions in all sensing unit groups are connected together to serve as the corresponding phase excitation input.

3. The planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: The sensing electrodes are arranged in all the gaps formed by the excitation electrodes, including the edge gaps. All sensing electrodes and excitation electrodes are arranged uniformly in a matrix as a whole, and the distance between any two adjacent electrodes is I.

4. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: In each sensing unit, the excitation electrodes are arranged in 8m rows along the upper surface of the fixed-length substrate, with a distance of I between two adjacent rows of excitation electrodes. Each row of excitation electrodes consists of 4n identical excitation plates evenly arranged along the X direction. The excitation plates are squares with a side length of W1, and the distance between two adjacent excitation plates in each row is W1+2I. The starting positions of two adjacent rows of excitation electrodes are staggered along the X direction by a distance of W1+I. The starting positions of the excitation electrodes in odd-numbered rows are the same along the X direction, and the starting positions of the excitation electrodes in even-numbered rows are the same along the X direction. Wherein, n and m are both positive integers. In the excitation electrode array consisting of all even-numbered rows of excitation electrodes, all excitation electrodes in each row are connected to form a row excitation group; thus forming a 4m row excitation group; starting from the first row, every 4 rows form a cycle, which are respectively called the Y1 row excitation group, the Y2 row excitation group, the Y3 row excitation group, and the Y4 row excitation group; In the excitation electrode array consisting of all odd-numbered rows of excitation electrodes, all excitation electrodes in each column are connected to form a column excitation group; thus forming 4n column excitation groups; starting from the first column, every 4 columns form a cycle, which are respectively called the X1 column excitation group, X2 column excitation group, X3 column excitation group and X4 column excitation group; All X1 column excitation groups and all Y1 row excitation groups are connected to form phase A excitation electrode group; all X2 column excitation groups and all Y2 row excitation groups are connected to form phase B excitation electrode group; all X3 column excitation groups and all Y3 row excitation groups are connected to form phase C excitation electrode group; all X4 column excitation groups and all Y4 row excitation groups are connected to form phase D excitation electrode group.

5. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: The modulation unit is square with a side length of W / 2; the spacing between adjacent modulation units is W / 2.

6. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: The modulation unit is made of a different material than the fixed-length base, and the upper surface of the modulation unit is flush with the upper surface of the fixed-length base.

7. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: The upper surface of the modulation unit is higher than the upper surface of the fixed-length substrate.

8. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: A recess is formed on the fixed-length base at the position corresponding to the modulation unit. The depth of the recess is greater than the thickness of the modulation unit. The modulation unit is installed in the recess, and the upper surface of the modulation unit is lower than the upper surface of the fixed-length base.

9. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: A through hole is made on the fixed-length substrate at the position corresponding to the modulation unit, and the air in the through hole constitutes the modulation unit.

10. A planar two-dimensional time-grating displacement sensor based on electric field modulation according to claim 1, characterized in that: A recess is formed on the fixed-length substrate at the position corresponding to the modulation unit. The portion of the fixed-length substrate corresponding to the orthographic projection of the recess constitutes the modulation unit, or the air inside the recess constitutes the modulation unit, or the portion of the fixed-length substrate corresponding to the orthographic projection of the recess and the air inside the recess together constitute the modulation unit.

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