Single code channel absolute displacement sensor with series structure

Abstract

The invention discloses a single code channel absolute displacement sensor with a series structure, which is characterized in that excitation electrodes are arranged on the upper surface of a fixed ruler base body, induction electrodes are arranged on the lower surface of a movable ruler base body, the upper surface of the fixed ruler base body is uniformly divided into at least two areas along the length direction, and a group of excitation electrodes are arranged in each area; all the excitation electrodes are located on the same straight line to form a single-row structure. Each group of exciting electrodes consists of a plurality of exciting pole pieces which are uniformly distributed, the number of the exciting pole pieces is integral multiple of 4, four adjacent exciting pole pieces form an antipode, and the number of antipodes of the exciting electrodes in each area on the sizing base body is sequentially increased by one from one end to the other end. And four groups of induction electrodes with the same structure are uniformly distributed on the same straight line on the lower surface of the movable ruler base body. According to the absolute displacement time grating sensor, absolute displacement measurement can be achieved, meanwhile, a sensor structure occupying a small longitudinal space is provided, and the application field of the absolute displacement time grating sensor is widened.

Description

Technical Field

[0001] The invention relates to an improvement on the structure of a linear displacement sensor, in particular to a single-code channel absolute displacement sensor with a series structure, belonging to the field of displacement sensors. Background Art

[0002] Traditional precision linear displacement measurement is mainly based on grating sensors, which are typically represented by grating, magnetic grating, capacitive grating and other grating sensors. Their common feature is that they use spatially evenly divided grating lines as the measurement reference. In order to improve the measurement accuracy and resolution, these grating sensors use precision engraving and need to rely on high-precision electronic subdivision technology. The complex and rigorous engraving process and electronic subdivision circuit cause the sensor to be expensive and have poor anti-interference ability. In recent years, a time-grating sensor that uses clock pulses as the displacement measurement reference has been developed in China, and on this basis, a time-grating displacement sensor based on an alternating electric field has been developed (see Chinese invention patent No. 201110145967.5). In subsequent research, a Chinese invention patent named "Electric field time-grating linear displacement sensor based on single-row multilayer structure" and patent No. 201410102437.6 was applied for. This sensor uses high-frequency clock pulses as the measurement reference and uses an alternating electric field constructed by parallel capacitor plates for precision displacement measurement. Although these two electric field time-grating displacement sensors can achieve precise measurement, they use incremental counting methods, which have cumulative errors and can only identify the displacement within one cycle. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a single-channel absolute displacement sensor with a series structure. The present invention can provide a sensor structure that occupies a smaller longitudinal space while realizing absolute displacement measurement, thereby broadening the application field of absolute displacement time-grating sensors.

[0004] The technical solution of the present invention is achieved in this way: A single-code channel absolute displacement sensor with a serial structure comprises a movable ruler substrate and a fixed-length substrate which are parallel and opposite to each other with a gap, an excitation electrode is arranged on the upper surface of the fixed-length substrate, and a sensing electrode is arranged on the lower surface of the movable ruler substrate, and the sensing electrode on the movable ruler substrate faces the excitation electrode on the fixed-length substrate; the upper surface of the fixed-length substrate is evenly divided into at least two areas along the length direction, the excitation electrodes have the same number of groups as the number of divided areas and are arranged in each area in a one-to-one correspondence, and all the excitation electrodes are located on the same straight line to form a single-row structure; each group of excitation electrodes is composed of a number of evenly arranged excitation pole pieces, the number of excitation pole pieces is an integer multiple of 4, wherein four adjacent excitation pole pieces form a pole pair, thereby obtaining a plurality of pole pairs; the number of pole pairs of the excitation electrodes in each area on the fixed-length substrate increases by one from one end to the other end; the sensing electrodes are four groups with the same structure and are evenly distributed on the same straight line on the lower surface of the movable ruler substrate.

[0005] Furthermore, each group of sensing electrodes is composed of at least one sensing electrode piece; if each group of sensing electrodes has multiple sensing electrode pieces, all the sensing electrode pieces in each group of sensing electrodes are evenly arranged along the length direction of the moving ruler substrate; the shape of the sensing electrode piece is a fully closed figure surrounded by two sinusoidal curves with equal amplitudes and a phase difference of 180° in the interval [0, π].

[0006] Furthermore, all the excitation electrodes on the fixed-size substrate are in the shape of rectangles; the excitation electrodes are in three groups, the two ends are called the first group and the third group, and the middle one is called the second group; The width of the excitation electrode corresponding to the first group of excitation electrodes is R w1 , the distance between two adjacent excitation pole pieces is R i1 , the first group of excitation electrodes has a width of W1=4*(R w1 +R i1 The width of the excitation electrode corresponding to the second group of excitation electrodes is R w2 , the distance between two adjacent excitation pole pieces is R i2 , the second set of excitation electrodes has a width of W2 = 4*(R w2 +R i2 The width of the excitation electrode corresponding to the third group of excitation electrodes is R w3 , the distance between two adjacent excitation pole pieces is R i3 , the width of the third group of excitation electrodes is W3=4*(R w3 +R i3 ); and satisfy 2*(R w3 +R i3 )≥2*R w1 +R i1 ; The width of the induction electrode is R w5 ; R w5 =2*(Rw3 +R i3 ).

[0007] Furthermore, all the excitation electrode groups at odd positions on the fixed-length substrate are connected through metal leads so that all the excitation electrode groups at odd positions are synchronously connected or disconnected from the excitation signals; all the excitation electrodes at even positions on the fixed-length substrate are connected through metal leads so that all the excitation electrode groups at even positions are synchronously connected or disconnected from the excitation signals.

[0008] In all pairs of each group of excitation electrodes, all the excitation pole pieces in the first sequence are connected through the intermediate metal lead to form an A1 excitation phase, all the excitation pole pieces in the second sequence are connected through the intermediate metal lead to form a B1 excitation phase, all the excitation pole pieces in the third sequence are connected through the intermediate metal lead to form a C1 excitation phase, and all the excitation pole pieces in the fourth sequence are connected through the intermediate metal lead to form a D1 excitation phase; four sinusoidal excitation signals with equal amplitudes and periods and a phase difference of 90° are applied to the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase, respectively, so as to form an alternating electric field distributed along the length direction of the fixed-length substrate; the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase of all the excitation electrodes in odd positions are connected together correspondingly through leads; the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase of all the excitation electrodes in even positions are connected together correspondingly through leads.

[0009] Furthermore, the four groups of sensing electrodes on the movable scale substrate respectively form sensing group a, sensing group b, sensing group c and sensing group d with all the excitation electrodes on the fixed scale substrate; When the movable scale substrate undergoes linear displacement along the length direction of the fixed scale substrate, sensing group a, sensing group b, sensing group c and sensing group d generate induction, and generate traveling wave signals G1, traveling wave signals G2, traveling wave signals G3 and traveling wave signals G4 with displacement information on the four groups of sensing electrodes respectively; the four traveling wave signals with displacement information are processed by the front circuit board and the FPGA system to obtain the absolute displacement value.

[0010] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention realizes the measurement of absolute displacement through the principle of differential pole positioning.

[0011] 2) The present invention improves the excitation electrodes from the existing two rows arranged side by side (called parallel connection) to a structure in which only one row is arranged in the same straight line (called series connection), thereby realizing the integration of the sensor structure, reducing the longitudinal size of the sensor, and achieving absolute positioning.

[0012] 3) The present invention designs the sensing electrodes of the moving ruler into four groups, thereby ensuring that the moving ruler always has two groups of normally working electrodes in any posture within the measuring range. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a positional relationship diagram of a fixed-length substrate and a movable-length substrate when the present invention is in state one.

[0014] Figure 2 This is a positional relationship diagram of the fixed-length base and the movable-length base when the present invention is in state two.

[0015] Figure 3 This is a sensor data processing block diagram of the present invention. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] See also Figure 1 and Figure 2 The single-code channel absolute displacement sensor of the present invention has a series structure, including upper and lower parallel and opposite and with a gap d The movable ruler substrate 21 and the fixed-length substrate 11 are provided with an excitation electrode on the upper surface of the fixed-length substrate 11, and an induction electrode on the lower surface of the movable ruler substrate 21, and the induction electrode on the movable ruler substrate is directly opposite to the excitation electrode on the fixed-length substrate. The upper surface of the fixed-length substrate is evenly divided into at least two regions along the length direction, and the excitation electrodes have the same number of groups as the number of divided regions and are arranged in each region one by one, and all the excitation electrodes are located on the same straight line to form a single-row structure; each group of excitation electrodes is composed of a number of evenly arranged excitation pole pieces, and the number of excitation pole pieces is an integer multiple of 4, wherein four adjacent excitation pole pieces form a pair of poles, thereby obtaining multiple pairs of levels; the number of pairs of excitation electrodes in each region on the fixed-length substrate increases by one from one end to the other end; the induction electrodes are four groups with the same structure and are evenly distributed on the same straight line on the lower surface of the movable ruler substrate.

[0018] The four groups of sensing electrodes on the lower surface of the moving ruler substrate of the present invention are respectively referred to as sensing electrode I 211, sensing electrode II 212, sensing electrode III 213 and sensing electrode IV 214. Each group of sensing electrodes is composed of at least one sensing electrode piece; if each group of sensing electrodes has multiple sensing electrode pieces, all the sensing electrode pieces in each group of sensing electrodes are evenly arranged along the length direction of the moving ruler substrate; the shape of the sensing electrode pieces is a double sinusoidal electrode; that is, a fully closed figure surrounded by two sinusoidal curves with equal amplitudes and a phase difference of 180° in the interval [0, π]. The sensing electrode piece is a double sinusoidal shape, so that when the variable area is integrated, the output traveling wave signal is smoother.

[0019] In the present invention, all the excitation electrode groups at odd positions on the fixed-length substrate are connected through metal leads so that all the excitation electrode groups at odd positions are synchronously connected or disconnected from the excitation signal; all the excitation electrodes at even positions on the fixed-length substrate are connected through metal leads so that all the excitation electrode groups at even positions are synchronously connected or disconnected from the excitation signal.

[0020] In all pairs of each group of excitation electrodes, all the excitation pole pieces in the first sequence are connected through the intermediate metal lead to form an A1 excitation phase, all the excitation pole pieces in the second sequence are connected through the intermediate metal lead to form a B1 excitation phase, all the excitation pole pieces in the third sequence are connected through the intermediate metal lead to form a C1 excitation phase, and all the excitation pole pieces in the fourth sequence are connected through the intermediate metal lead to form a D1 excitation phase; four sinusoidal excitation signals with equal amplitudes and periods and a phase difference of 90° are applied to the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase, respectively, so as to form an alternating electric field distributed along the length direction of the fixed-length substrate; the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase of all the excitation electrodes in odd positions are connected together correspondingly through leads; the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase of all the excitation electrodes in even positions are connected together correspondingly through leads.

[0021] Furthermore, the four groups of sensing electrodes on the movable scale substrate respectively form sensing group a, sensing group b, sensing group c and sensing group d with all the excitation electrodes on the fixed scale substrate; When the movable scale substrate undergoes linear displacement along the length direction of the fixed scale substrate, sensing group a, sensing group b, sensing group c and sensing group d generate induction, and generate traveling wave signals G1, traveling wave signals G2, traveling wave signals G3 and traveling wave signals G4 with displacement information on the four groups of sensing electrodes respectively; the four traveling wave signals with displacement information are processed by the front circuit board and the FPGA system to obtain the absolute displacement value.

[0022] The following is a detailed description using an example where the excitation electrodes are divided into three groups.

[0023] The upper surface of the fixed-length substrate 11 is evenly divided into three regions A, B, and C. The lengths of the three regions A, B, and C are all W. The three excitation electrodes contain a total of 3N+3 pairs of electrodes. N pairs of electrodes occupy the A region of the fixed-length substrate 11. The N pairs of electrodes constitute the excitation electrode I111, which is composed of 4N rectangular excitation pole pieces of the same size arranged evenly. The width of the excitation pole piece is R w1 , the distance between two adjacent excitation pole pieces is R i1 , the width of the pole is W1=4*(R w1 +R i1); N+1 pairs of electrodes occupy the B area of ​​the fixed-size substrate 11, and the N+1 pairs of electrodes constitute the excitation electrode II 112, which is composed of 4N+4 rectangular excitation pole pieces of the same size arranged evenly, and the width of the excitation pole piece is R w2 , the distance between two adjacent excitation pole pieces is R i2 , the width of the pole is W2=4*(R w2 +R i2 ); N+2 pairs of electrodes occupy the C area of ​​the fixed-size substrate 11, and the N+2 pairs of electrodes constitute the excitation electrode III 113, which is composed of 4N+8 rectangular excitation pole pieces of the same size arranged evenly, and the width of the excitation pole piece is R w3 , the distance between two adjacent excitation pole pieces is R i3 , the width of the pole is W3=4*(R w3 +R i3 ). There should be a relationship 2*(R w3 +R i3 )≥2*R w1 +R i1 The width of the sensing electrode is R w5 ; R w5 =2*(R w3 +R i3 ). The four groups of sensing electrodes are evenly distributed along the positive direction of X, with a spacing of W / 2. Limiting the maximum width of the excitation pole piece can make one sensing pole piece cover at least the gap between two excitation pole pieces plus two excitation pole pieces.

[0024] The four adjacent excitation pole pieces in each pair of excitation electrodes on the fixed-size substrate are respectively S+, S-, C+ and C- excitation phases. Starting from any excitation pole piece of the fixed-size substrate, the excitation electrode I111 and the excitation electrode III113 connect the excitation pole pieces separated by three excitation pole pieces through the intermediate layer metal lead; the excitation electrode II112 connects the pole pieces separated by three excitation pole pieces through the intermediate layer metal lead; thereby constructing an alternating electric field along the positive direction of X, and the signals of the excitation electrode I111, the excitation electrode III113 and the excitation electrode II112 are transmitted respectively. The sensing electrode I 211 on the movable ruler substrate and all the excitation electrodes on the fixed-length substrate constitute a sensing group a; the sensing electrode II 212 on the movable ruler substrate and all the excitation electrodes on the fixed-length substrate constitute a sensing group b; the sensing electrode III 213 on the movable ruler substrate and all the excitation electrodes on the fixed-length substrate constitute a sensing group c; the sensing electrode IV 214 on the movable ruler substrate and all the excitation electrodes on the fixed-length substrate constitute a sensing group d.

[0025] Four sinusoidal excitation signals with equal amplitude and period and 90° phase difference are applied to the S+, S-, C+ and C- excitation phases to form a coupling capacitor between the excitation unit on the fixed-length substrate and the induction unit on the movable-length substrate. During measurement, there is an alternating electric field along the positive direction of length (X-axis) on the fixed-length substrate. When the movable-length substrate undergoes a linear displacement along the X-axis direction of the fixed-length substrate, sensing group a, sensing group b, sensing group c, and sensing group d generate induction. The coupled electric field between the three groups of excitation electrodes and the sensing electrode Ⅰ211 generates a traveling wave signal G1 with displacement information on the sensing electrode Ⅰ211; the coupled electric field between the three groups of excitation electrodes and the sensing electrode Ⅱ212 generates a traveling wave signal G2 with displacement information on the sensing electrode Ⅱ212; the coupled electric field between the three groups of excitation electrodes and the sensing electrode Ⅲ213 generates a traveling wave signal G3 with displacement information on the sensing electrode Ⅲ213; the coupled electric field between the three groups of excitation electrodes and the sensing electrode Ⅳ214 generates a traveling wave signal G4 with displacement information on the sensing electrode Ⅳ214; the four traveling wave signals with displacement information can obtain absolute displacement values ​​after being processed by the front circuit board and the FPGA system.

[0026] When measuring, the present invention first determines the working position of the sensor, and then obtains the correct absolute displacement value through encoding and decoding after determining the position state. The specific measurement conditions can be divided into the following two types: First, four sinusoidal excitation signals with equal amplitudes and periods and a phase difference of 90° are applied to the S+, S-, C+ and C- excitation phases of the excitation electrodes I111 and III113 on the fixed-length substrate 11, and no excitation signal is applied to the excitation electrode II112. At this time, the induction electrode I211 generates induction through the sensing group a to obtain the traveling wave signal G1; the induction electrode II212 generates induction through the sensing group b to obtain the traveling wave signal G2; the induction electrode III213 generates induction through the sensing group c to obtain the traveling wave signal G3; and the induction electrode IV214 is not induced. Then, four sinusoidal excitation signals with equal amplitude and period and 90° phase difference are applied to the S+, S-, C+ and C- excitation phases of the excitation electrode II112. No excitation signals are applied to the excitation electrodes I111 and III113. At this time, the induction electrode I211 is not induced; the induction electrode II212 is not induced; the induction electrode III213 is induced through the sensor group c to obtain the traveling wave signal G3; the induction electrode IV214 is induced through the sensor group d to obtain the traveling wave signal G4. Then, all the excitation electrodes are energized at the same time. After the above steps, the front circuit board and the FPGA system judge the current position as state 1 (as shown in the attached figure). Figure 1 As shown), at this time, the traveling wave signals G2 and G4 are processed by the front circuit board and the FPGA system to obtain the absolute displacement value S.

[0027] First, four sinusoidal excitation signals with equal amplitudes and periods and a phase difference of 90° are applied to the S+, S-, C+ and C- excitation phases of the excitation electrodes I111 and III113 on the fixed-length substrate 11, and no excitation signal is applied to the excitation electrode II112. At this time, the induction electrode I211 generates induction through the sensing group a to obtain the traveling wave signal G1; the induction electrode II212 generates induction through the sensing group b to obtain the traveling wave signal G2; the induction electrode III213 is not induced; the induction electrode IV214 generates induction through the sensing group d to obtain the traveling wave signal G4. Then, four sinusoidal excitation signals with equal amplitude and period and 90° phase difference are applied to the S+, S-, C+ and C- excitation phases of the excitation electrode II112. No excitation signal is applied to the excitation electrode I111 and the excitation electrode III113. At this time, the induction electrode I211 is not induced; the induction electrode II212 is induced through the sensor group b to obtain the traveling wave signal G2; the induction electrode III213 is induced through the sensor group c to obtain the traveling wave signal G3; the induction electrode IV214 is induced through the sensor group d to obtain the traveling wave signal G4. Then, all the excitation electrodes are energized at the same time. After the above steps, the front circuit board and the FPGA system judge the current position as state two (as shown in the attached Figure 2 As shown), at this time, the traveling wave signals G1 and G3 are processed by the front circuit board and the FPGA system to obtain the absolute displacement value S.

[0028] The above two states are the two main states during the operation of the sensor. The significance of judging the state is that when the sensing electrode is in the connection of two excitation electrodes, the traveling wave signal generated by the sensing electrode is meaningless, so it is screened out through the front circuit board and the FPGA system, and the traveling wave signal generated by another group of sensing electrodes is used as the correct output traveling wave signal. Figure 3 This is a sensor data processing block diagram of the present invention.

[0029] The present invention uses a single-row sensing structure with a pole number of 3N+3 to achieve high-precision measurement of linear displacement; four groups of sinusoidal sensing electrodes are designed to achieve position judgment across the excitation electrodes, achieve absolute measurement of linear displacement, and obtain an absolute displacement value S; the sensing electrodes divided into four groups on this single-row sizing machine can achieve absolute measurement of linear displacement.

[0030] It should be noted that the interval between the two groups of excitation electrodes shown in the figure is exaggerated, and the actual interval is smaller; at the same time, the two states described above are general states, which are mainly intended to determine whether the sensing electrodes are in normal working condition.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the applicant has described the present invention in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that modifications or equivalent substitutions of the technical solution of the present invention without departing from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A single-code channel absolute displacement sensor of a serial structure, comprising a movable ruler substrate and a fixed-length substrate which are parallel and opposite to each other with a gap, an excitation electrode is arranged on the upper surface of the fixed-length substrate, and a sensing electrode is arranged on the lower surface of the movable ruler substrate, and the sensing electrode on the movable ruler substrate is opposite to the excitation electrode on the fixed-length substrate; characterized in that: The upper surface of the fixed-length substrate is evenly divided into at least two areas along the length direction. The excitation electrodes have the same number of groups as the number of divided areas and are arranged in each area in a one-to-one correspondence. All the excitation electrodes are located on the same straight line to form a single-row structure; each group of excitation electrodes is composed of a number of evenly arranged excitation pole pieces, and the number of excitation pole pieces is an integer multiple of 4, wherein four adjacent excitation pole pieces form a pair of poles, thereby obtaining multiple pairs of levels; the number of pairs of poles of the excitation electrodes in each area on the fixed-length substrate increases by one from one end to the other end; the induction electrodes are four groups with the same structure and are evenly distributed on the same straight line on the lower surface of the moving ruler substrate.

2. The single-channel absolute displacement sensor with a serial structure according to claim 1, characterized in that: Each group of sensing electrodes is composed of at least one sensing electrode piece; if each group of sensing electrodes has multiple sensing electrode pieces, all the sensing electrode pieces in each group of sensing electrodes are evenly arranged along the length direction of the moving ruler substrate; the shape of the sensing electrode piece is a fully closed figure surrounded by two sinusoidal curves with equal amplitudes and a phase difference of 180° in the interval [0, π].

3. The single-channel absolute displacement sensor with a serial structure according to claim 2, characterized in that: All the excitation electrodes on the fixed-length substrate are in the shape of rectangles; the excitation electrodes are in three groups, the two ends are called the first group and the third group, and the middle one is called the second group; The width of the excitation electrode corresponding to the first group of excitation electrodes is R w1 , the distance between two adjacent excitation pole pieces is R i1 , the first group of excitation electrodes has a width of W1=4*(R w1 +R i1 The width of the excitation electrode corresponding to the second group of excitation electrodes is R w2 , the distance between two adjacent excitation pole pieces is R i2 , the second set of excitation electrodes has a width of W2 = 4*(R w2 +R i2 The width of the excitation electrode corresponding to the third group of excitation electrodes is R w3 , the distance between two adjacent excitation pole pieces is R i3 , the width of the third group of excitation electrodes is W3=4*(R w3 +R i3 ); and satisfy 2*(R w3 +R i3 )≥2*R w1 +R i1 ; The width of the induction electrode is R w5 ; R w5 =2*(R w3 +R i3 ).

4. The single-channel absolute displacement sensor with a serial structure according to claim 1, characterized in that: All the excitation electrode groups at odd positions on the fixed-length substrate are connected through metal leads so that all the excitation electrode groups at odd positions can be synchronously connected or disconnected from the excitation signal; all the excitation electrodes at even positions on the fixed-length substrate are connected through metal leads so that all the excitation electrode groups at even positions can be synchronously connected or disconnected from the excitation signal.

5. The single-channel absolute displacement sensor with a serial structure according to claim 4, characterized in that: In all pairs of each group of excitation electrodes, all the excitation pole pieces in the first sequence are connected through the intermediate metal lead to form an A1 excitation phase, all the excitation pole pieces in the second sequence are connected through the intermediate metal lead to form a B1 excitation phase, all the excitation pole pieces in the third sequence are connected through the intermediate metal lead to form a C1 excitation phase, and all the excitation pole pieces in the fourth sequence are connected through the intermediate metal lead to form a D1 excitation phase; four sinusoidal excitation signals with equal amplitudes and periods and a phase difference of 90° are applied to the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase, respectively, so as to form an alternating electric field distributed along the length direction of the fixed-length substrate; the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase of all the excitation electrodes in odd positions are connected together correspondingly through leads; the A1 excitation phase, the B1 excitation phase, the C1 excitation phase and the D1 excitation phase of all the excitation electrodes in even positions are connected together correspondingly through leads.

6. The single-channel absolute displacement sensor with a serial structure according to claim 1, characterized in that: The four groups of sensing electrodes on the movable scale substrate respectively form sensing group a, sensing group b, sensing group c and sensing group d with all the excitation electrodes on the fixed scale substrate; When the movable scale substrate undergoes linear displacement along the length direction of the fixed scale substrate, sensing group a, sensing group b, sensing group c and sensing group d generate induction, and generate traveling wave signals G1, traveling wave signals G2, traveling wave signals G3 and traveling wave signals G4 with displacement information on the four groups of sensing electrodes respectively; the four traveling wave signals with displacement information are processed by the front circuit board and the FPGA system to obtain the absolute displacement value.

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