Absolute planar two-dimensional time grating sensor and measurement method thereof

Abstract

The application relates to the technical field of precision displacement measurement, and discloses an absolute planar two-dimensional time grating sensor and a measurement method thereof. The sensor comprises a fixed scale base and a moving scale base. Two layers of excitation electrodes are arranged on the fixed scale base and are periodically arrayed along the X direction and the Y direction, and the two layers have different period structures. The moving scale base is provided with differential induction electrodes corresponding to the excitation electrodes. During measurement, time-sharing on-off of the excitation electrodes is realized through an analog switch. In a first time period, an excitation signal is only applied to one layer and output is collected; in a second time period, the excitation signal is switched to the other layer and output is collected. The signals collected in the respective time periods are subjected to phase detection and calculation, and joint processing is carried out based on the period number difference of the two layers, so that absolute displacement in the X and Y directions is obtained. The application realizes planar two-dimensional absolute position positioning without additionally adding code channels under a single measurement structure, reduces the system complexity, and improves the overall integration performance.

Description

Technical Field

[0001] This invention relates to the field of precision displacement measurement technology, specifically to an absolute planar two-dimensional time grating sensor and its measurement method. Background Technology

[0002] Two-dimensional planar displacement measurement technology has important applications in precision machining equipment, semiconductor manufacturing, and high-end positioning systems. As systems develop towards higher precision, miniaturization, and higher integration, displacement measurement devices not only need to have high resolution and stability, but also need to be able to directly acquire absolute position information after power-on, thereby avoiding the impact of accumulated errors and zero-return operations in incremental measurements, and meeting the rapid positioning requirements under complex working conditions.

[0003] Existing absolute planar two-dimensional displacement measurement schemes typically introduce multiple sets of measurement units with different spatial periods or coding characteristics to jointly calculate displacement information and achieve unique position determination. In such schemes, different measurement units often require independent signal channels for acquisition and processing, thus placing high demands on the system's structural layout, channel consistency, and synchronization control. In practical applications, as the measurement dimension and the amount of coded information increase, the system complexity also increases, and matching errors between multiple channels may affect the measurement results. On the other hand, when integrating multiple periodic structures or coding units within a limited space, the coupling relationship between different signals gradually strengthens, which may affect the signal extraction and calculation process, thus placing higher demands on measurement stability. Furthermore, if a single measurement channel is used to achieve absolute displacement detection, reasonable design is required in the signal acquisition method and coding construction mechanism to ensure the distinguishability and uniqueness of the position information.

[0004] Therefore, effectively acquiring multiple sets of coded information and achieving unique displacement determination without significantly increasing the system's structural complexity and limiting measurement channels has become a problem that needs to be solved in current planar two-dimensional absolute displacement measurement technology. Summary of the Invention

[0005] To address the problem that existing technologies struggle to achieve high-precision planar absolute two-dimensional measurement and positioning with a single sensing structure, the present invention aims to provide an absolute planar two-dimensional time grating sensor and its measurement method. This addresses issues in existing absolute planar displacement measurement technologies, such as reliance on multiple measurement channels for acquiring encoded information, complex system structures, high requirements for channel consistency, and the impact of multi-signal coupling on measurement stability.

[0006] The technical solution of the present invention is as follows: The first aspect of this invention provides an absolute planar two-dimensional time grating sensor, comprising a fixed-scale substrate and a movable-scale substrate. The fixed-scale substrate has two layers of arrayed excitation electrodes, namely a first layer of excitation electrodes and a second layer of excitation electrodes. Each layer of excitation electrodes is periodically distributed along the X and Y directions, and different layers of excitation electrodes have different periodic structures. The movable-scale substrate has sensing electrodes corresponding to each layer of excitation electrodes, namely a first layer of sensing electrodes and a second layer of sensing electrodes, arranged differentially.

[0007] Preferably, the first layer of excitation electrodes is continuous. Each excitation electrode constitutes one spatial period, and the number of periods is... The second layer of excitation electrodes is continuous. One or Each excitation electrode constitutes one spatial period, and the number of periods is... The number of cycles and the internal structure of a single cycle of each excitation electrode layer are mathematically correlated. and All are positive integers greater than or equal to 3. , All are positive integers greater than 1, and and They are not equal and none of them are equal to 1.

[0008] In one specific embodiment, the number of cycles of the first layer of excitation electrodes Number of cycles with the second layer of excitation electrodes The difference is 1 or they are both prime numbers.

[0009] The sensor structure provided in the first aspect of this invention, by embedding two layers of excitation electrodes with independent and distinct period numbers within a single physical plane, can construct an alternating electromagnetic field distribution with dual spatial periods during sensor operation. This arrangement utilizes the difference in the number of periods among the different electrode layers within their spatial overlap range to directly establish a vernier effect in the physical dimension. This hardware-level vernier amplification correspondence allows the subsequently calculated continuous relative phase difference to be mapped to uniquely determined spatial absolute coordinates, thus providing a substantial physical basis for realizing large-range two-dimensional absolute displacement measurements.

[0010] A second aspect of the present invention provides a measurement method for an absolute planar two-dimensional time grating sensor, applied to the aforementioned absolute planar two-dimensional time grating sensor, comprising the following steps: S1. The first and second excitation electrodes on the fixed scale substrate are switched on and off in a time-division manner by the switch control signal. During the first period when the sensor is powered on, an excitation signal is applied to one of the first and second excitation electrodes, and the corresponding first or second sensing electrode on the moving scale substrate is put into working state, while the other excitation electrode and the corresponding sensing electrode are turned off. S2. After the first time period ends, switch the switch control signal, turn off the second layer excitation electrode (1-2) and the second layer sensing electrode (2-2) during the second time period, turn on the first layer excitation electrode (1-1) and the first layer sensing electrode (2-1), and apply an excitation signal to the first layer excitation electrode (1-1); S3. Collect the signals output by the first layer of sensing electrodes and the second layer of sensing electrodes during the first time period and after the first time period, respectively, and perform phase detection on the signals to obtain the phase information of the output signals of the first layer of sensing electrodes and the second layer of sensing electrodes. S4. Based on the difference in the number of cycles of the first and second excitation electrodes in their physical arrangement, the phase information is jointly calculated to obtain the absolute displacement of the moving scale substrate in the X and Y directions.

[0011] Preferably, during the measurement process, the first and second excitation electrodes apply excitation signals with corresponding phase differences according to the number of cycles. When one spatial cycle contains... When there are one excitation electrode, continuous The phase difference between the excitation signals applied by the excitation electrodes is a full circle (2π) and The ratio, i.e. When a spatial period contains When there are one excitation electrode, continuous The phase difference between the excitation signals applied by each excitation electrode is a full circle and The ratio, i.e. .

[0012] In one specific embodiment, the specific method for performing phase detection on the signal in step S3 above includes: converting the acquired signal into a corresponding square wave shape, receiving the shaped square wave signal and the reference reference signal generated by the same source in the system, and performing phase detection by calculating the number of high-frequency clock pulses filled between the edges of the square wave.

[0013] In one specific embodiment, the joint solution in step S4 above includes: performing joint solution on the obtained continuous relative phase difference, and obtaining the absolute displacement based on the vernier amplification correspondence generated by the difference in the number of periods.

[0014] The measurement method provided in the second aspect of this invention employs time-division isolation logic in the time domain. By controlling the alternating on and off of different levels of electrode systems through analog switches, the electromagnetic coupling path that is easily generated when the double-layer nested electrode structure is simultaneously excited is completely cut off, effectively eliminating the pollution of the original electrical signal by interlayer electromagnetic crosstalk. On this basis, the method combines high-frequency pulse interpolation counting technology to perform high-precision square wave phase extraction, and performs joint calculation based on the coprime or phase difference of the number of cycles of the aforementioned sensor hardware construction, enabling a single sensor to simultaneously acquire high-precision absolute displacement in the X and Y directions without increasing the hardware size.

[0015] The absolute planar two-dimensional time grating sensor and its measurement method provided by this invention have the following beneficial effects: The absolute planar two-dimensional time grating sensor of the present invention has a first layer of excitation electrodes and a second layer of excitation electrodes with different spatial periodic structures on the same fixed-scale substrate, and differential sensing electrodes corresponding to the two excitation electrodes are set on the moving-scale substrate, so that the same sensing structure can form and acquire two sets of displacement information with different periodic characteristics. By using the difference in the number of periods M1 and M2 of the two excitation electrodes, a hardware basis is provided for establishing a unique mapping between phase information and absolute position, without the need for additional independent code tracks, thereby helping to reduce the complexity of the sensor structure and improve the integration of the two-dimensional displacement measurement device.

[0016] The measurement method of this invention uses a switch control signal to alternately conduct the first and second electrode groups at different time periods, avoiding the simultaneous operation of the two excitation electrodes, thereby reducing the impact of interlayer electromagnetic coupling and signal crosstalk on the induced signal. The first and second layer induced signals obtained in time division are shaped and subjected to high-frequency pulse interpolation phase detection based on the same source reference signal, and then jointly calculated according to the difference in the number of cycles of the two layers. This can obtain the absolute displacement of the moving scale substrate in the X and Y directions, and reduce the synchronization and matching requirements caused by simultaneous multi-channel acquisition. Attached Figure Description

[0017] Figure 1 This is a schematic diagram showing the spatial correspondence between the fixed-length base and the moving-length base in Example 1.

[0018] Figure 2 This is a schematic diagram of the fixed-length base in Example 1.

[0019] Figure 3 This is a schematic diagram showing the spatial positions of the first layer of excitation electrodes and corresponding induction electrodes on the fixed-length substrate in Example 1.

[0020] Figure 4 This is a schematic diagram showing the spatial position of the induction electrode corresponding to the second layer of excitation electrode on the fixed-length substrate in Example 1.

[0021] Figure 5 This is a schematic diagram of the moving ruler base in Example 1.

[0022] Figure 6 The waveform diagram shows the switching on and off of the analog switch signal, the application of the excitation electrode signal, and the reception of the signal by the induction electrode in Example 1.

[0023] Figure 7 This is a flowchart illustrating the signal processing flow and displacement calculation principle of the sensing electrode in Example 1.

[0024] Figure 8 This is a schematic diagram of the arrangement of excitation electrodes on the fixed-length substrate in Example 2.

[0025] Figure 9 This is a schematic diagram of the arrangement of the second layer of excitation electrodes on the fixed-length substrate in Example 2.

[0026] Figure 10 This is a schematic diagram of the arrangement of the first layer of excitation electrodes on the fixed-length substrate in Example 3.

[0027] Figure 11 This is a schematic diagram of the arrangement of the second layer of excitation electrodes on the fixed-length substrate in Example 3.

[0028] Among them, 1, fixed-length substrate; 1-1, first-layer excitation electrode; 1-2, second-layer excitation electrode; 2, moving-length substrate; 2-1, first-layer induction electrode; 2-2, second-layer induction electrode. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: See appendix Figure 1 This embodiment provides an absolute planar two-dimensional time grating sensor, the overall hardware structure of which includes a fixed-scale base 1 and a movable-scale base 2 arranged in parallel. A predetermined distance is maintained between the fixed-scale base 1 and the movable-scale base 2. Two independent excitation electrodes are disposed on the surface of the fixed-length substrate 1, namely the first excitation electrode 1-1 and the second excitation electrode 1-2. Each excitation electrode layer is periodically distributed along the X and Y directions of the sensor plane. Furthermore, different excitation electrode layers have different periodic structures in physical dimensions. The surface of the movable-length substrate 2 is provided with sensing electrodes corresponding to the spatial positions of the excitation electrodes of the fixed-length substrate 1, specifically including the first sensing electrode 2-1 corresponding to the first excitation electrode 1-1, and the second sensing electrode 2-2 corresponding to the second excitation electrode 1-2. The first sensing electrode 2-1 is divided into four independent sensing blocks A1, B1, C1, and D1 in the plane; similarly, the second sensing electrode 2-2 is also divided into four independent sensing blocks A2, B2, C2, and D2 in the plane.

[0031] See appendix Figure 2 The two layers of excitation electrodes on the fixed-length substrate 1 are nested and distributed on the same physical plane. The array period number of the first layer of excitation electrodes 1-1 is set to... The corresponding spatial period width is indicated as The array cycle number of the second-layer excitation electrodes 1-2 is set to... The corresponding spatial period width is indicated as The number of array cycles for the two-layer excitation electrodes. and The physical parameter difference satisfies the mathematical relationship that the two signals are coprime; this difference is used to subsequently establish the spatial mapping equation between the phase and absolute displacement of the two layers of signals. Note that, within the same spatial length... Inside, guarantee .

[0032] See appendix Figure 3 The first layer of excitation electrodes 1-1 are continuous Each excitation electrode constitutes one complete spatial period, and the total number of array periods is [number missing]. The width of each independent excitation electrode in the first layer is... The physical spacing between two adjacent excitation electrodes is Therefore, the calculation relationship for the single-cycle width of the first-layer excitation electrode is determined as follows: Along the X and Y direction boundaries of the fixed-length substrate 1, the signal input terminals of the first layer of excitation electrodes are marked. Four orthogonal excitation signals are sequentially connected according to the spatial period, namely... , , and The first layer of sensing electrodes 2-1 on the moving scale substrate 2 has a corresponding period width. The internal arrangement is based on differential method, with its four sensing blocks A1, B1, C1 and D1 each covering a specific spatial phase region to obtain induced electromotive force containing precise displacement information.

[0033] See appendix Figure 4 The second layer of excitation electrodes 1-2 are continuous Each excitation electrode constitutes one complete spatial period, and the total number of array periods is [number missing]. The width parameter of each independent excitation electrode in the second layer is... The physical spacing parameter between two adjacent excitation electrodes is Therefore, the calculation relationship for the single-cycle width of the second-layer excitation electrode is determined as follows: Along the X and Y direction boundaries of the fixed-length substrate 1, the signal input terminals marked with the second layer of excitation electrodes are sequentially connected to three AC excitation signals with a phase difference of two-thirds of a circle's diameter (i.e., a phase difference of π / 3). = The three induction electrodes 2-2 on the moving scale substrate 2 are S1, S2, and S3, respectively. The second layer of induction electrodes 2-2 on the moving scale substrate 2 has a corresponding period width... The internal arrangement is based on differential, with its four sensing blocks A2, B2, C2 and D2 respectively used to receive the electromagnetic induction generated potential in the corresponding area, and then output a differential signal containing coarse displacement information.

[0034] See appendix Figure 5 The surface of the moving scale base 2 is provided with a first layer of induction electrodes 2-1 and a second layer of induction electrodes corresponding to the excitation electrodes of each layer of the fixed scale base 1. In the spatial arrangement structure of the induction electrodes, each layer of induction electrodes is arranged differentially within the period width of its corresponding excitation electrode.

[0035] Specifically, the first-layer sensing electrode 2-1, corresponding to the first-layer excitation electrode 1-1, is divided into four independent sensing blocks in the plane, labeled A1, B1, C1, and D1, respectively. The first-layer sensing electrode 2-1 has a spatial period width of [missing information]. Differential arrangement is implemented within. In the X and Y directions, the overall width occupied by the four sensing blocks is... Equal, wherein the physical size width of a single internal sensing block is limited to .

[0036] The second-layer sensing electrode 2-2, corresponding to the second-layer excitation electrode 1-2, is also divided into four independent sensing blocks in the plane, labeled A2, B2, C2, and D2, respectively. The second-layer sensing electrode 2-2 has a period width of [missing information - likely a specific width within a second-layer space]. Differential arrangement is implemented internally, and the physical size and width of a single sensing block within it are limited to [specific dimensions]. Based on the aforementioned size constraints and differential arrangement, each layer of sensing electrodes, when receiving the corresponding alternating electromagnetic field, utilizes four sensing blocks to acquire the instantaneous potential of different spatial phase regions, and then outputs the differential induced voltage signal of that layer through circuit combination.

[0037] During system operation, the control unit uses analog switch control signals to perform time-division multiplexing control on each layer of excitation electrodes on the fixed-length substrate 1. After the sensor is powered on, the analog switch sequentially activates the excitation electrodes of a specific layer and the corresponding sensing electrode pairs according to the timing sequence.

[0038] The excitation electrode on the fixed-scale base 1 generates an electromagnetic field upon receiving an excitation signal. The induction electrode on the moving-scale base 2, in an activated state, generates and outputs an AC signal carrying displacement information using the principle of electromagnetic induction. The control unit processes the time-division acquired induction signals from each layer via a shaping circuit, and then performs phase detection using high-frequency pulse interpolation in conjunction with a reference signal. Finally, the measurement system uses the extracted phase information to perform simultaneous calculations based on the inherent spatial period number difference between the two excitation electrode layers, thereby obtaining the two-dimensional absolute displacement in the X and Y directions under a single sensor hardware structure.

[0039] See appendix Figure 6 After the system is powered on, based on the aforementioned hardware structure of the fixed-scale base 1 and the moving-scale base 2, the control unit executes the measurement method according to the preset timing logic. The system uses analog switch control signals to implement time-division switching of the excitation electrodes of each layer in the time domain, thereby cutting off the electromagnetic coupling path between different spatial periodic structures. Specifically, this includes the following steps: S1, see appendix Figure 6 The switching signal waveform diagram shown in (a) has the vertical axis representing the control voltage amplitude and the horizontal axis representing the running time. This waveform is generated on the [number]th day after the sensor is powered on. During the time period, the switching signal is in a negative level state, and the control unit performs time-division switching control on each layer of excitation electrodes on the fixed-length substrate 1 accordingly.

[0040] In During the time period, the analog switch is turned on, causing the second-layer induction electrode 2-2 corresponding to the second-layer excitation electrode 1-2 to be in working state, while simultaneously cutting off and turning off the first-layer excitation electrode 1-1 and its corresponding first-layer induction electrode 2-1 corresponding to other layers. Under the condition that only the second-layer electrode system is independently turned on, the system applies excitation signals to the second-layer excitation electrode 1-2 according to the number of cycles. In this embodiment, one cycle of the second-layer excitation electrode is set to include the number of electrodes... See attached document Figure 6 (f) in Figure 6 (g) and Figure 6(h) shows the waveforms of the three excitation signals applied to the second-layer excitation electrodes 1-2, respectively. It exhibits a continuous sinusoidal variation over a period of time. The amplitude returns to zero after the time period. The system applies a phase difference of [value] to the corresponding excitation electrodes. The AC excitation signal applied to the second layer excitation electrodes 1-2 is given by the following formula: ; ; ; In the formula, , and The three AC excitation signals are applied to the second layer excitation electrodes 1-2; The excitation voltage amplitude is set to 26V; Let ω be the angular frequency of the excitation signal, given by the relationship... Therefore, the set value is 8×10. 4 ; This refers to the system uptime.

[0041] While applying the excitation signal, the analog switch activates the second-layer sensing electrode 2-2 corresponding to that layer, simultaneously deactivating the first-layer excitation electrodes and corresponding first-layer sensing electrodes for other layers. (See appendix) Figure 6 The waveform shown in (i) indicates that the second-layer sensing electrode 2-2, in its active state, outputs a sensing signal. .exist During the period, It presents a continuous alternating waveform, while The amplitude is zero after the time period. The formula for the second-layer induction signal is: ; In the formula, This is the second layer of sensing signal; , , and The instantaneous potential of each sensing block corresponding to the second layer; The signal amplitude received by the second layer of sensing electrodes; and These are the coarse displacement values ​​of the sensor in the X and Y directions at the current moment, respectively; The spatial period width of the second-layer excitation electrode.

[0042] S2, Powering on the sensor After the time period ends, please refer to the appendix. Figure 6 In (a), the switching signal is... At any given moment, a level flip occurs, and the system switches the control signal to a positive level. The analog switch responds to the new state, closing the second-layer excitation electrode 1-2 and the second-layer sensing electrode 2-2, while simultaneously activating the first-layer excitation electrode 1-1 and the first-layer sensing electrode 2-1. The system applies a phase difference of [value missing] to the first-layer excitation electrode 1-1 according to the number of cycles. The excitation signal. To set parameters. For example, see the appendix. Figure 6 (b) Figure 6 (c) Figure 6 (d) and Figure 6 Figure (e) shows the waveforms of the four orthogonal excitation signals applied to the first layer of excitation electrodes. The amplitude was zero before the period, and in The signal then exhibits a sinusoidal change after a certain period. The formula for the applied first-layer excitation signal is: ; ; ; ; In the formula, , , and These are four orthogonal excitation signals applied to the first layer of excitation electrodes.

[0043] During this operating period, the analog switch simultaneously activates the first-layer sensing electrode 2-1 corresponding to that layer, while deactivating the second-layer excitation electrodes 1-2 and their corresponding second-layer sensing electrodes 2-2 for the remaining layers. The first-layer sensing electrode 2-1 outputs a sensing signal. See attached document. Figure 6 (j) in the middle, the induced signal exist It was zero before the time period, and in A continuous alternating waveform appears after the time period. The formula for the first layer of inductive signal is: ; In the formula, This is the first layer of sensing signal; , , and The instantaneous potential of each sensing block corresponding to the first layer; The amplitude of the signal received by the first layer of sensing electrodes; and These are the precisely measured displacement values ​​in the X and Y directions, respectively. This represents the period width of the first layer of excitation electrodes.

[0044] S3, see appendix Figure 7 The figure illustrates the signal conditioning and data processing architecture within the FPGA processing circuit. The acquisition front end acquires the aforementioned data. Signal output during the time period and and Signal output after the time period The acquired analog sinusoidal signal is fed into the square wave shaping module and converted into the corresponding square wave shape. The high-frequency pulse interpolation square wave phase counting module in the processing circuit receives the shaped square wave signal and the reference signal generated by the system. Phase detection is performed by calculating the number of high-frequency clock pulses filling the edges of the square wave, thereby obtaining the phase information of the output signal of the corresponding sensing electrode in each layer.

[0045] After acquiring the phase information of each layer, the system enters... Figure 7 The phase calculation step is shown. Figure 7 The phase calculation in the middle section is illustrated in three waveform evolution diagrams. The first diagram reflects the sawtooth wave characteristics of the spatial phase change with displacement corresponding to the induced signals of each layer, where the solid and dashed lines correspond to the phase information of the first layer, respectively. Second layer phase information The second figure shows the waveform after directly subtracting the phases of the two layers, exhibiting discontinuous abrupt changes. The third figure shows the continuous phase difference curve formed after piecewise compensation processing. The relative phase difference is defined as... Taking X-direction measurement as an example, the formula for the relative phase difference between the two layers of signals is: ; In the formula, To calculate the relative phase difference between the two layers of signals in the X direction.

[0046] Similarly, the formula for the relative phase difference between the two layers of signals extracted in the Y direction is: ; In the formula, To calculate the relative phase difference between the two layers of signals in the Y direction.

[0047] S4. Based on the difference in the number of cycles of the excitation electrodes in each layer of the fixed-length substrate in their physical arrangement, the system performs a joint calculation on the acquired continuous relative phase difference to obtain the final absolute displacement of the moving-length substrate in the measurement direction, and in Figure 7 The displacement value is output at the bottom. Taking the X-direction measurement process as an example, the formula for the absolute position in the X-direction is: ; In the formula, This represents the final calculated absolute displacement value in the X direction. For integer operations; This represents the precisely measured displacement value in the X direction corresponding to the first layer of induction signal. This represents the precisely measured displacement value in the X direction; This represents the period width of the first layer of excitation electrodes. The system reuses this calculation logic on the sensing data in the Y direction to calculate the overall two-dimensional absolute displacement.

[0048] ; To meet the engineering requirements of different measurement accuracies and ranges, there is a predetermined mathematical correlation between the number of cycles of the two layers of excitation electrodes on the length-fixed substrate 1 and the internal structure of a single cycle. The following detailed description of different embodiments of the present invention is provided in conjunction with the accompanying drawings.

[0049] Example 2: See appendix Figure 3 Appendix Figure 8 , Figure 9 A specific implementation method is provided in which the number of cycles of the two excitation electrodes differs by 1 (Example 2). Figure 8 This shows an overall view of the nested distribution of two layers of excitation electrodes on a fixed-length substrate 1. In this arrangement, the array period number of the first layer of excitation electrodes 1-1 is set to... The array period number of the second-layer excitation electrodes 1-2 is set to The number of periods of the two are strictly related by a physical difference of 1 (i.e. This periodic arrangement with a phase difference of 1 can construct a vernier effect with a single mapping relationship within its spatial overlap range, so that the subsequent calculated relative phase difference can directly correspond to a uniquely determined absolute displacement.

[0050] The first layer of excitation electrodes 1-1 is continuous. Each excitation electrode represents one spatial period, corresponding to the total number of array periods. . Figure 3 The details of each physical parameter are clearly marked: the width of each independent excitation electrode in the first layer is... The physical spacing between two adjacent excitation electrodes is Therefore, the single-cycle width of the first layer of excitation electrodes is determined as follows: The system applies phase differences sequentially along the arrangement direction of the first layer of excitation electrodes, with a spatial period. The orthogonal excitation signals are respectively , , and The first layer of sensing blocks A1, B1, C1, and D1 are arranged in the central region of the fixed-length substrate 1, and are used for differential reception of the corresponding period width. The induced electromotive force within.

[0051] See appendix Figure 10 ,Should Figure 10 The underlying structure of the accompanying second-layer excitation electrodes 1-2 is shown. The second-layer excitation electrodes 1-2 are arranged in a continuous manner. Each excitation electrode constitutes one complete spatial period, and the total number of array periods is [number missing]. . Figure 10 In the middle, the width parameter of each independent excitation electrode in the second layer is... The physical spacing parameter between two adjacent excitation electrodes is The single-cycle width of the second-layer excitation electrode is The system is connected sequentially to three input channels along the peripheral input terminals. The phase difference AC excitation signals are S1, S2, and S3, respectively. The corresponding second-layer induction blocks A2, B2, C2, and D2 are also arranged at the center position to receive the induction signals of the coarse measurement frequency band.

[0052] Example 3: See appendix Figure 2 , Figure 10 and Figure 11 This provides a specific implementation method where the number of cycles for the two excitation electrode layers are coprime numbers. For example... Figure 2 As shown in the overall plan view, the number of cycles for the first layer of excitation electrodes 1-1 on the fixed-length substrate 1 is set to... The number of cycles for the second-layer excitation electrodes 1-2 is set to... Parameters 3 and 5 are coprime numbers. This coprime periodic combination can expand the measurement range while maintaining the uniqueness of the spatial absolute coordinates during difference frequency calculation. Figure 10 This embodiment shows the detailed arrangement of the first layer excitation electrodes 1-1, including the number of electrodes per cycle. Number of cycles Electrode width and interval Together they constitute the period width The applied signals remain orthogonal. , , and .

[0053] Example 4: Within the framework of the aforementioned coprime numbers, the electrode driving mode within a single cycle can also be adjusted synchronously. (See appendix.) Figure 11 ,Should Figure 11 Another signal-driven configuration for the second layer of excitation electrodes 1-2 on the fixed-length substrate 1 is shown. In this configuration, the second layer of excitation electrodes contains within one spatial cycle... One excitation electrode, number of array cycles The width of the second layer of independent excitation electrodes is... , interval is At this time, the single-cycle width of the second-layer excitation electrode is Correspondingly, the system applies a phase difference of to four consecutive excitation electrodes. Alternating excitation signal. Figure 11 The edge input terminals clearly indicate these four signals, namely S1, S2, S3, and S4. The second layer of sensing blocks A2, B2, C2, and D2 on the moving ruler substrate are within this period width. The system internally performs differential signal reception. By expanding the number of driving phases of the bottom electrode from 3 to 4, the system can process the second-layer signal using the same orthogonal solution logic as the first layer. This achieves high module reuse in the hardware driver and back-end signal conditioning links, further optimizing the overall measurement performance and circuit complexity of the sensor.

[0054] 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. An absolute planar two-dimensional time grating sensor, characterized in that, It includes a fixed-length base (1) and a movable-length base (2) arranged parallel to the fixed-length base (1); The fixed-length substrate (1) is provided with a first layer of excitation electrodes (1-1) and a second layer of excitation electrodes (1-2) arranged in a periodic array along the X and Y directions. The first layer of excitation electrodes (1-1) and the second layer of excitation electrodes (1-2) have different spatial periodic structures. The moving scale base (2) is provided with a first layer sensing electrode (2-1) corresponding to the first layer excitation electrode (1-1) and a second layer sensing electrode (2-2) corresponding to the second layer excitation electrode (1-2). The first layer sensing electrode (2-1) and the second layer sensing electrode (2-2) are arranged in a differential manner.

2. The absolute planar two-dimensional time grating sensor according to claim 1, characterized in that, The first layer of sensing electrodes (2-1) includes four independent sensing blocks, A1, B1, C1, and D1, arranged in a 2×2 array. The four sensing blocks are located within the first layer spatial period width. Inside; The second layer of sensing electrodes (2-2) includes four independent sensing blocks, A2, B2, C2, and D2, arranged in a 2×2 array. The four sensing blocks are located within the second layer spatial period width. Inside; The dimensions of each sensing block in the first layer along the X and Y directions are: The dimensions of each sensing block in the second layer along the X and Y directions are: .

3. The absolute planar two-dimensional time grating sensor according to claim 2, characterized in that, The first layer of excitation electrodes (1-1) is continuous. Each excitation electrode constitutes one spatial period, and the number of array periods is [number missing]. ; The second layer of excitation electrodes (1-2) are continuous One or Each excitation electrode constitutes one spatial period, and the number of array periods is [number missing]. ; in and All are positive integers greater than or equal to 3. , All are positive integers greater than 1, and .

4. The absolute planar two-dimensional time grating sensor according to claim 3, characterized in that, The and The difference is 1 or they are both prime numbers.

5. A measurement method for an absolute planar two-dimensional time grating sensor, applied to the absolute planar two-dimensional time grating sensor according to any one of claims 1-4, characterized in that, Includes the following steps: S1. During the first time period, the second excitation electrode (1-2) and the second sensing electrode (2-2) are turned on by the switch control signal, an excitation signal is applied to the second excitation electrode (1-2), and the first excitation electrode (1-1) and the first sensing electrode (2-1) are turned off. S2. After the first time period ends, switch the switch control signal, turn off the second layer excitation electrode (1-2) and the second layer sensing electrode (2-2) during the second time period, turn on the first layer excitation electrode (1-1) and the first layer sensing electrode (2-1), and apply an excitation signal to the first layer excitation electrode (1-1); S3. Collect the second-layer sensing signal output by the second-layer sensing electrode (2-2) in the first time period and the first-layer sensing signal output by the first-layer sensing electrode (2-1) in the second time period, and obtain the phase information of the two respectively. S4. Based on the difference in the number of array cycles of the first layer excitation electrode (1-1) and the second layer excitation electrode (1-2), the phase information is jointly calculated to obtain the absolute displacement of the moving scale substrate (2) in the X and Y directions.

6. The measurement method of the absolute planar two-dimensional time grating sensor according to claim 5, characterized in that, Within a spatial period When there is one excitation electrode, according to the above The excitation electrodes are arranged sequentially within a single cycle to apply adjacent phase differences. The excitation signal; Within a spatial period When there is one excitation electrode, according to the above The excitation electrodes are arranged sequentially within a single cycle to apply adjacent phase differences. The excitation signal.

7. The measurement method of the absolute planar two-dimensional time grating sensor according to claim 5, characterized in that, The differential sensing signals in the X and Y directions of the first layer of sensing electrodes (2-1) respectively satisfy: ； In the formula, This is the first layer of sensing signal; , , and The instantaneous potential of each sensing block in the first layer; The amplitude of the signal received by the first layer of sensing electrodes (2-1); and These are the precisely measured displacement values ​​in the X and Y directions, respectively. The period width of the first layer excitation electrode (1-1); The differential sensing signals in the X and Y directions of the second layer sensing electrode (2-2) respectively satisfy: ； In the formula, This is the second layer of sensing signal; , , and The instantaneous potential of each sensing block in the second layer; The amplitude of the signal received by the second layer of sensing electrodes (2-2); and These are the coarse displacement values ​​of the sensor in the X and Y directions at the current moment, respectively; The spatial period width of the second-layer excitation electrode (1-2).

8. The measurement method of the absolute planar two-dimensional time grating sensor according to claim 5, characterized in that, The specific methods for performing phase detection on the output signal include: The first layer sensing signal and the second layer sensing signal are respectively shaped and converted into square wave signals; A reference signal that is of the same origin as the excitation signal For reference, the number of high-frequency clock pulses filling the gap between the edge of the square wave signal and the corresponding edge of the reference signal are counted to obtain the phase information of the first layer of sensing signal and the second layer of sensing signal.

9. The measurement method of the absolute planar two-dimensional time grating sensor according to claim 5, characterized in that, The phase information of the first layer of sensing signal and the second layer of sensing signal in the X direction are respectively and ; The phase information of the first layer sensing signal and the second layer sensing signal in the Y direction are respectively and ; The relative phase difference between the first layer sensing signal and the second layer sensing signal in the X direction is extracted, and the relative phase difference is compensated in segments to obtain the relative phase difference in the X direction. satisfy: ； Similarly, the relative phase difference in the Y direction satisfy: ； in, This represents the X-direction displacement value corresponding to the first layer of induction signal. This represents the X-direction displacement value corresponding to the second layer of sensing signal. The spatial period width of the first layer of excitation electrodes (1-1) The spatial period width of the second layer excitation electrode (1-2); This represents the Y-direction displacement value corresponding to the first layer of induction signal. This represents the Y-direction displacement value corresponding to the second layer of induction signal.

10. The measurement method of the absolute planar two-dimensional time grating sensor according to claim 9, characterized in that, Based on the difference in the number of array cycles of the first layer excitation electrode (1-1) and the second layer excitation electrode (1-2), the continuous relative phase difference is jointly calculated; The absolute displacement of the movable scale base (2) in the X direction satisfy: ； The absolute displacement of the movable scale base (2) in the Y direction satisfy: ； in, This represents the integer operation. The period width of the first layer of excitation electrodes. This represents the precisely measured displacement value in the X direction corresponding to the first layer of induction signal. The precise displacement value in the Y direction corresponding to the first layer of induction signal.

Images