Array type capacitive pressure sensing device and pressure detection method thereof

Abstract

The application discloses an array type capacitive pressure sensing device and a detection method thereof, and belongs to the technical field of pressure sensing. The device forms independent coupling capacitors at each intersection of the intersection array, scans the driving lines and reads the sensing line signals in parallel to construct a full-plane capacitive change distribution map, and realizes multi-point pressure detection. The application provides two electrode layout schemes of vertical overlap and coplanar. Both schemes adopt a signal processing mode of sequentially scanning the driving lines and reading the sensing line signals in parallel, and output pressure values and position coordinates of each effective intersection. As a preferred embodiment, multiple independent pressure action areas can also be identified and separated from the capacitive change distribution map through connected domain analysis to improve detection robustness. The sensing point density is determined by the electrode arrangement pitch, and the typical pitch is 1mm to 10mm. The application has a simple structure and can realize high-density multi-point pressure distribution detection.

Description

Technical Field

[0001] This invention relates to the field of pressure sensing technology, specifically to a capacitive pressure distribution sensing device and its detection method based on a cross-electrode array, which can be widely used in fields such as robot tactile sensing, smart wearable devices, industrial pressure distribution measurement, medical and health monitoring, and pressure input interfaces of electronic devices. Background Technology

[0002] Pressure sensing technology is an important means of obtaining information about external physical contact. Traditional pressure sensors are mainly classified into resistive, piezoelectric, and capacitive types.

[0003] Resistive pressure sensors detect pressure by measuring changes in the resistance of a pressure-sensitive material, but they suffer from high power consumption, large temperature drift, and difficulty in achieving high-density arraying. Piezoelectric sensors, while having a fast dynamic response, are only suitable for dynamic pressure detection and cannot accurately measure static or quasi-static pressure.

[0004] Capacitive pressure sensors typically sense pressure by detecting changes in capacitance between electrodes. Their advantages include simple structure, low power consumption, and good stability. However, most existing capacitive pressure sensors are single-point or single-channel designs, requiring independent electrode pairs and signal conditioning circuits for each detection point. When multi-point pressure distribution detection on a two-dimensional plane is required, traditional solutions necessitate a large number of independent sensor units, leading to system complexity, high cost, and difficulty in achieving high-density integration and miniaturization.

[0005] Therefore, there is an urgent need in the field for a novel pressure sensing device that can achieve high-density, multi-point pressure distribution detection with a simple structure, in order to overcome the above-mentioned deficiencies of the prior art. Summary of the Invention

[0006] This invention aims to provide an array-type capacitive pressure sensing device and its detection method. It employs a cross-electrode array structure and a scanning detection mechanism, enabling simultaneous detection of the position and magnitude of multiple pressure points on a single plane. The device is simple in structure, low in cost, and easily scalable to high-density arrays. This invention provides two electrode layout schemes to adapt to different application scenarios and manufacturing process requirements.

[0007] To achieve the above objectives, the present invention provides the following technical solution: An array-type capacitive pressure sensing device includes: The first electrode group includes a plurality of drive lines extending along a first direction; The second electrode group includes multiple sensing lines extending along a second direction, the first direction intersecting the second direction, such that the driving line and the sensing line form multiple intersection points on the projection. A sensing layer is disposed near the drive line and the sensing line to convert external pressure into a change in the coupling capacitance between the drive line and the sensing line. A substrate for supporting the first electrode group and / or the second electrode group; And a signal processing control unit, electrically connected to the drive line and the sensing line respectively, for applying an excitation signal to the drive line and receiving a coupling signal from the sensing line.

[0008] The drive line and the sensing line form a coupling capacitance at each intersection. When external pressure is applied to the surface of the device, the sensing functional layer responds, causing a change in the coupling capacitance value at the corresponding intersection. The signal processing control unit uses a time-division scanning method to sequentially apply excitation signals to each drive line (the scanning order can be row-by-row, interlaced, random, or other preset order), and simultaneously reads the coupling signals from all sensing lines when each drive line is excited, thereby obtaining a two-dimensional capacitance data matrix corresponding to all intersections. This matrix is ​​compared with a reference matrix under no-pressure conditions to obtain a full-plane capacitance change distribution map. Based on this full-plane capacitance change distribution map, the location of each pressure application point can be identified; for each intersection where capacitance changes, the corresponding pressure value can be calculated based on its capacitance change. When multiple effective change points exist, simultaneous detection of multi-point pressure distribution is achieved.

[0009] As the core method of multi-point pressure detection in this invention, the signal processing and control unit realizes the detection and positioning of multi-point pressure through the following steps: (1) Establishing a reference matrix: Under the initial state without external pressure, complete a full array scan to obtain the initial capacitance value of each intersection point and form a reference matrix C0(i,j), where i=1,2,...,M, j=1,2,...,N, M is the total number of driving lines, and N is the total number of sensing lines.

[0010] (2) Real-time data acquisition and differential calculation: In the working state, the full array scan is continuously performed at the predetermined scanning frame rate to obtain the real-time capacitance matrix C1(i,j). The difference between the real-time matrix and the reference matrix is ​​calculated point by point to obtain the difference matrix ΔC(i,j) = C1(i,j) – C0(i,j). This difference matrix is ​​the full-plane capacitance change distribution map.

[0011] (3) Screening of effective change points and pressure detection: A preset noise threshold T is set, and each element in the difference matrix ΔC(i,j) is judged: if |ΔC(i,j)|≥T, the intersection is determined as an effective change point, and pressure acts at this intersection; for each intersection determined to be effective, the corresponding pressure value is directly calculated according to its capacitance variation through a pre-stored mapping relationship, and its plane coordinates are determined according to the row and column positions of the intersection in the array; when multiple intersections are determined to be effective at the same time, the pressure values and coordinate information of all effective points are output synchronously, that is, multi-point pressure detection is realized. If |ΔC(i,j)|<T, it is determined as an invalid point and no response is made. The threshold T is preset according to the noise level of the device and the required sensitivity, and can be adaptively adjusted according to environmental changes.

[0012] The above steps (1) to (3) are executed cyclically at a frame rate of no less than 50Hz, so as to realize real-time multi-point pressure detection. The signal processing and control unit can directly output the pressure value and position coordinates of each effective intersection, and each point is detected independently without mutual interference.

[0013] In a preferred embodiment, to further improve the accuracy and anti-interference capability of multi-point detection, the signal processing and control unit can also perform connected domain analysis on the difference matrix, which is specifically as follows: (4) Connected domain analysis: Perform connected domain analysis on all intersections marked as effective change points (i.e., |ΔC(i,j)|≥T) in the difference matrix. Through the 4-neighborhood or 8-neighborhood connectivity rule, a plurality of mutually connected effective intersections are merged into one connected domain, and each connected domain represents an independent pressure action area. Specifically, if there are other effective effective intersections in the up, down, left, and right (or including diagonal directions) directions of a certain effective intersection, these intersections belong to the same connected domain. After connected domain marking, k independent connected domains are effectively marked in the difference matrix, and each connected domain corresponds to an actual pressure action point.

[0014] (5) Precise positioning of each pressure action point (preferred embodiment): For each connected domain, the weighted average value of the position coordinates of all effective intersections contained therein is calculated as the precise position coordinate of the pressure action point. The weight is preferably the absolute value of the capacitance variation ΔC of the intersection. Use (X k , Y k ) to represent the coordinates of the pressure action point of the k-th connected domain, and the calculation formula is: ;

[0015] where X i is the position coordinate of the i-th drive line, Y jLet be the position coordinates of the j-th induction line, and the summation range is all valid intersections within this connected region. Through weighted averaging, sub-pitch level positioning accuracy can be achieved, meaning the positioning accuracy is better than the arrangement pitch of the drive lines and induction lines.

[0016] (6) Pressure value calculation at each pressure point (preferred implementation): For each connected region, the pressure value corresponding to the connected region is calculated based on the capacitance change at each intersection it contains, combined with a pre-calibrated pressure-capacitance mapping relationship. Specifically, one of the following methods can be used: take the pressure value corresponding to the maximum capacitance change among all effective intersections in the connected region as the pressure value of that point; or take the average or weighted average of the capacitance changes at all effective intersections in the connected region, and then map it to the pressure value. The pressure-capacitance mapping relationship is obtained through calibration experiments under known pressure and stored in the processor in the form of curve fitting or lookup table.

[0017] (7) Multi-point output (preferred implementation): The position coordinates and pressure values ​​of the K pressure application points identified in the above steps are output in the form of data frames. Each data frame contains K sets of data, and each set of data contains the planar coordinates (X, Y, X) of the point. k ,Y k ) and pressure value F k This enables simultaneous detection of multi-point pressure distribution.

[0018] Steps (4) to (7) of the preferred embodiment described above can be selectively performed after step (3) to replace or supplement the method of directly outputting valid intersection points point by point in step (3).

[0019] The number of drive lines M and the number of sensing lines N are determined based on the required sensing area and spatial resolution. The spatial density of sensing points is jointly determined by the pitch (i.e., center distance) between adjacent drive lines and the pitch between adjacent sensing lines. Typically, the pitch ranges from 1 mm to 10 mm, corresponding to a sensing point density of 1 to 100 sensing points per square centimeter. The smaller the pitch and the larger M and N are, the higher the spatial resolution, but the higher the requirements for the scanning speed and data processing capability of the signal processing control unit. M and N are each independently selected from 4 to 512, preferably from 8 to 256. It should be noted that the linewidth and line spacing of the electrodes are only manufacturing process parameters; the difference between the two is the gap between adjacent electrodes, while the actual density of sensing points is determined by the arrangement pitch of the drive lines and sensing lines.

[0020] In one embodiment of the present invention (first embodiment, vertically overlapping electrode scheme), the driving line and the sensing line are respectively disposed in two independent electrode layers that are vertically opposite each other, that is, the first electrode group and the second electrode group are opposite to each other and spaced apart. The conductive layer where the driving line is located and the conductive layer where the sensing line is located are two separate layers, vertically separated from each other. The sensing functional layer is a compressible dielectric layer sandwiched between the first electrode group and the second electrode group. At each intersection, the driving line and the sensing line are vertically opposite each other, and a vertical coupling capacitance is formed between them through the compressible dielectric layer. When external pressure is applied to the device, the compressible dielectric layer undergoes local compression deformation at the pressure position, resulting in a decrease in the distance between the driving line and the sensing line at that point, thereby causing a change in the coupling capacitance value at the intersection. In this embodiment, the substrate includes a rigid substrate and a flexible substrate. Specifically, the first electrode group is disposed on a rigid substrate, which can be selected from a PCB rigid circuit board or a glass substrate; the second electrode group is disposed on a flexible substrate, which is a flexible circuit board. The driving lines in the first electrode group and the sensing lines in the second electrode group are both formed by etching or electroplating processes. The compressible dielectric layer is sandwiched between the first electrode group on the rigid substrate and the second electrode group on the flexible substrate. The flexible circuit board is electrically connected to the signal processing and control unit by pressing, welding, or bonding with conductive adhesive.

[0021] In another embodiment of the present invention (a second embodiment, a coplanar electrode scheme), the driving line and the sensing line are disposed in the same electrode layer and arranged at intervals between each other. That is, the electrodes in the first electrode group and the second electrode group are located in the same conductive layer, and the driving line and the sensing line are located in the same plane and arranged alternately. Each driving line forms an edge coupling capacitance with its adjacent sensing line in the horizontal direction. The sensing functional layer is a sensitive dielectric layer covering the driving line and the sensing line. When external pressure is applied to the sensitive dielectric layer, the dielectric constant of the sensitive dielectric layer at the pressure location changes, causing the coupling capacitance value between the driving line and the adjacent sensing line in that region to change. In this embodiment, the substrate can be a glass substrate, and the conductive layer is a metal coating layer disposed on the surface of the glass substrate. The driving lines and the sensing lines can be patterned by photolithography on the metal coating layer. Using a glass substrate combined with metal coating and photolithography can achieve higher electrode pattern precision and finer line width and spacing, thereby providing greater electrode design freedom at the same sensing point pitch (e.g., making the electrodes into an interdigitated structure to increase edge length and improve coupling capacitance strength). However, this is only a preferred implementation method of this embodiment, not a necessary one. In an alternative embodiment, the substrate can also be a rigid PCB or a flexible PCB, and the conductive layer can also be copper foil formed by etching. The sensitive dielectric layer is coated on top of the patterned electrode layer.

[0022] In both of the above implementation schemes, the scanning and detection mechanism of the signal processing control unit is exactly the same: each driving line is driven sequentially (the specific order can be set as row by row, intermittent, random or skipping rows, etc.), all sensing lines are read in parallel, a full-plane capacitance change distribution map is constructed, and the pressure magnitude and position coordinates of each pressure point are calculated accordingly to achieve multi-point detection.

[0023] Furthermore, in the first embodiment, the compressible dielectric layer is composed of an elastic foam material or a dielectric elastomer, such as polyurethane, polyester, polypropylene, acrylic acid, silicone rubber, etc., and its thickness is preferably in the range of 10 μm to 5 mm.

[0024] Furthermore, in the second embodiment, the sensitive dielectric layer is made of a material whose dielectric constant changes significantly under pressure, such as an elastomeric composite material doped with conductive particles or high dielectric constant fillers.

[0025] Further, the signal processing control unit includes: an excitation signal generator for sequentially providing AC excitation signals to each drive line; a signal receiving and conditioning module for receiving and amplifying the coupled signals on all induction lines in parallel when each drive line is excited; an analog-to-digital conversion module for converting analog signals into digital signals; and a processor for performing data processing tasks such as benchmark comparison, variation distribution map construction, and pressure and coordinate calculation. In a preferred embodiment employing connected component analysis, the processor is also used to perform data processing tasks such as connected component analysis and position weighting calculation.

[0026] Furthermore, the scanning frame rate of the signal processing control unit is not less than 50Hz.

[0027] (III) Beneficial Effects Compared with the prior art, the present invention has the following outstanding advantages: Multi-point pressure detection: Each electrode intersection is an independent pressure-sensitive unit. By constructing a full-plane capacitance change distribution map and synchronously determining and outputting all effective change points, this invention can simultaneously capture the position and pressure information of multiple pressure points, truly realizing two-dimensional pressure imaging.

[0028] Flexible Detection Methods: This invention provides two multi-point detection methods, which can be flexibly selected according to specific application requirements. The basic detection method directly outputs the pressure value and coordinate information of each valid intersection point, which is simple to calculate and fast, suitable for scenarios that require knowing the pressure at the location of each intersection point; in the preferred embodiment, adjacent valid intersection points are merged into the same pressure application area through connected component analysis, which can effectively suppress local noise interference, improve the robustness of detection, and achieve sub-pitch level positioning accuracy through weighted average positioning.

[0029] The test results are accurate and reliable: the capacitance change at each intersection point is independently measurable and corresponds one-to-one with a fixed planar position, and there is no problem of ambiguity in coordinate combination.

[0030] Simple structure and easy to manufacture: Only two sets of cross-arranged electrodes and corresponding substrates are needed to form a sensing array. It is compatible with mature PCB, FPC and semiconductor lithography processes. There is no need to make a separate sensor for each detection point, which significantly reduces manufacturing costs and process difficulty.

[0031] The two implementation schemes are suitable for different scenarios: the vertically overlapping electrode scheme combines a rigid substrate with a flexible substrate, which is structurally stable and highly sensitive, and is suitable for scenarios with high pressure sensitivity requirements; the coplanar electrode scheme adopts a single-layer conductive layer structure, which has lower manufacturing cost and thinner overall thickness. When using a glass substrate in conjunction with photolithography, more flexible electrode pattern design can be achieved with the same sensing point pitch.

[0032] High-density integration and real-time detection are possible: By reducing the pitch of the drive and sensing lines, detection resolution can be linearly improved without significantly increasing hardware complexity. Combined with a scan frame rate of at least 50Hz and an efficient data processing flow, real-time output of multi-point pressure can be achieved, meeting the needs of dynamic interactive applications. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the first embodiment of the present invention (vertical overlapping electrode scheme); Figure 2 This is a schematic diagram illustrating the principle of vertical coupling capacitance change caused by dielectric layer pressure in the first embodiment. Figure 3 This is a structural block diagram of the signal processing control unit (applicable to the first and second embodiments). Figure 4 This is a flowchart illustrating the pressure detection method of the present invention (applicable to the first and second embodiments). Figure 5 This is a schematic diagram of the algorithm flow for multi-point pressure identification and separation in a preferred embodiment of the present invention (illustrating the complete data processing link from the difference matrix to the multi-point output; this process is an optional step and can be executed or not executed according to application requirements). Figure 6 This is a schematic diagram of the structure of the second embodiment (coplanar electrode scheme) of the present invention; Figure 7 This is a schematic diagram illustrating the principle of horizontal coupling capacitance change caused by pressure on the dielectric layer in the second embodiment. Detailed Implementation

[0034] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0035] Example 1 (Vertical Overlapping Electrode Scheme) like Figure 1 , Figure 2 As shown, the array-type capacitive pressure sensing device provided in this embodiment mainly consists of a rigid substrate 5a, a first electrode group 1 disposed on the rigid substrate 5a, a flexible substrate 5b, a second electrode group 2 disposed on the flexible substrate 5b, a compressible dielectric layer 3, and a signal processing and control unit 4.

[0036] The rigid substrate 5a is selected from a rigid PCB circuit board or a glass substrate, providing stable support for the device. The first electrode group 1 is disposed on the upper surface of the rigid substrate 5a, and has multiple parallel driving lines 11 extending along a first direction (e.g., the X-axis direction). The driving lines 11 are formed by etching or electroplating. The flexible substrate 5b is a flexible circuit board, and its base film is selected from polyimide or polyester film, with a preferred thickness range of 12.5 μm to 125 μm. The second electrode group 2 is disposed on the lower surface of the flexible substrate 5b, and has multiple parallel sensing lines 21 extending along a second direction (e.g., the Y-axis direction). The sensing lines 21 are also formed by etching or electroplating. The first direction and the second direction are preferably perpendicular, such that the driving lines 11 and the sensing lines 21 form an M-row × N-column intersection array (e.g., ...) in the vertical projection direction. Figure 1 (As shown). The number of drive lines M and the number of sensing lines N are determined based on the required sensing area and spatial resolution. The pitch (center-to-center distance) between adjacent drive lines and the pitch between adjacent sensing lines determine the density of sensing points. Typically, the pitch ranges from 1 mm to 10 mm, corresponding to a sensing point density of 1 to 100 sensing points per square centimeter. Preferably, for conventional pressure distribution detection applications, the pitch is 5 mm, and M and N are each 16 to 64; for applications requiring higher resolution, the pitch can be reduced to 1 mm, and M and N can each be increased to 64 to 256.

[0037] A compressible dielectric layer 3 is sandwiched between the first electrode group 1 and the second electrode group 2, with an initial thickness of d0. This layer is made of a dielectric material with good elasticity and insulation properties, such as polyurethane foam with low compression set, and its thickness is preferably in the range of 10 μm to 5 mm. The flexible substrate 5b is electrically connected to the signal processing control unit 4 by pressing, welding or bonding with conductive adhesive, transmitting the signal from the induction line 21 to the signal processing control unit 4.

[0038] When a glass substrate is used as the rigid substrate 5a, the first electrode group 1 can form a metal thin film on the glass surface through magnetron sputtering or vapor deposition, and then pattern it to form the driving lines 11 through photolithography and etching. When a PCB rigid circuit board is used as the rigid substrate 5a, the driving lines 11 are formed through conventional PCB etching processes. The second electrode group 2 on the flexible substrate 5b is formed by laminating or electroplating copper foil on the surface of polyimide or polyester film, and then etching it to form the sensing lines 21.

[0039] like Figure 2As shown, the pressure detection principle of this embodiment is as follows: At each intersection, the drive line 11 and the sensing line 21 are perpendicularly aligned, forming a vertical coupling capacitor between them. In the initial state without pressure, this coupling capacitor value C0 is determined by the dielectric constant ε of the compressible dielectric layer 3 and the initial thickness d0, satisfying C0 = ε·S / d0 (where S is the area of ​​the electrodes facing each other). When an external pressure P is applied above the intersection, the compressible dielectric layer 3 in that area is compressed, and its thickness decreases from d0 to d1 (d1 < d0). Since the area of ​​the electrodes facing each other S and the dielectric constant ε remain unchanged, according to the parallel plate capacitance formula, the coupling capacitor value at this intersection increases to C1 = ε·S / d1. This capacitance change ΔC = C1 – C0 is monotonically correlated with the applied pressure, and a precise mapping relationship can be established through calibration.

[0040] Because the compressible dielectric layer 3 deforms only locally in the pressure area, the capacitance change is limited to the vicinity of the intersection point and does not significantly affect other intersection points at a distance. Therefore, the planar position of the pressure application point can be accurately located by identifying the intersection point where the capacitance change occurs. When multiple pressures act simultaneously on different positions of the device, each intersection point experiences independent capacitance changes, and the system can simultaneously detect the position and pressure magnitude of all pressure points, achieving multi-point pressure detection.

[0041] like Figure 3 As shown, the signal processing control unit 4 includes an excitation signal generator 41, a receiving conditioning module 42, an analog-to-digital converter 43, and a processor 44. Combined with... Figure 4 and Figure 5 The specific steps of the pressure detection method in this embodiment are as follows: Step S0 (Reference Establishment): In the initial state without external pressure, the processor 44 controls the excitation signal generator 41 and the receiving conditioning module 42 to complete a full array scan, obtain the initial capacitance value of each intersection point, and store it as a reference capacitance matrix C0(i,j) (i=1,2,...,M; j=1,2,...,N).

[0042] In step S1, the processor 44 controls the excitation signal generator 41 to sequentially apply AC excitation signals (such as sine waves or square waves) to each drive line 11 in a time-division multiplexing manner. The scanning order can be progressive, interlaced, random, or other preset orders, which can be preset by the processor 44 according to the actual application requirements.

[0043] In step S2, during the period when each drive line is excited, the receiving conditioning module 42 synchronously and in parallel collects the coupled signals on all sensing lines 21 to obtain a signal vector of length N.

[0044] In step S3, after completing the scanning of all M drive lines, the obtained M×N data are organized into a real-time capacitance matrix C1(i,j). The processor 44 performs point-by-point subtraction between the real-time matrix and the reference matrix to obtain a difference matrix ΔC(i,j) = C1(i,j) – C0(i,j), which is the full-plane capacitance change distribution map.

[0045] Step S4 (Effective change point screening and pressure detection): The processor 44 compares each element in the difference matrix ΔC(i,j) with a preset noise threshold T. If |ΔC(i,j)|≥T, the intersection is determined as an effective change point, and there is a pressure action at this intersection; for each intersection determined to be effective, the pressure value F(i,j) is directly calculated according to its capacitance change ΔC(i,j) through a pre-stored calibration curve, and its plane coordinates (X i ,Y j ). Multiple effective intersections output their respective pressure values and coordinate information at the same time, that is, multi-point pressure detection is realized. If |ΔC(i,j)|<T, it is determined as an invalid point and no response is made. The threshold T is preset according to the noise level of the device and the required sensitivity.

[0046] The above steps S0 to S4 are executed cyclically at a frame rate of no less than 50Hz, so as to realize real-time multi-point pressure detection. This step S4 directly outputs the pressure value and position coordinates of each effective intersection, each point is detected independently without mutual interference, and it is suitable for application scenarios that need to obtain the pressure at each intersection position.

[0047] In a preferred embodiment, in order to further improve the accuracy and anti-interference ability of multi-point detection, the following connected domain analysis step can be selectively executed after step S4 to replace or supplement the direct point-by-point output mode of step S4: Step S5 (Connected domain analysis and multi-point separation): The processor 44 performs connected domain analysis on all intersections marked as effective change points in the difference matrix (that is, intersections where |ΔC(i,j)|≥T). Through the four-neighborhood connectivity rule (that is, if there are other effective intersections in the four directions of up, down, left and right of a certain effective intersection, these intersections belong to the same connected domain), a plurality of mutually connected effective intersections are merged into one connected domain. After connected domain marking, K independent connected domains are effectively marked in the difference matrix, and each connected domain corresponds to an actual pressure action point. When K=0, it means there is no pressure action; when K≥1, each connected domain represents an independent pressure action point. This connected domain analysis step can be selectively executed or not according to specific application requirements.

[0048] Step S6 (Location of each pressure point and pressure calculation): For each connected component (numbered p = 1, 2, ..., k), processor 44 performs the following calculations: Calculate the weighted average position of all valid intersections within the connected component, with the weight being the capacitance change |ΔC| at each intersection, to obtain the precise position coordinates (X) of the pressure point. k Y k This achieves sub-pitch level positioning; simultaneously, it comprehensively processes the capacitance changes at each intersection point within the connected domain (taking the maximum value or weighted average), and calculates the pressure value F at the pressure application point by combining it with the pre-calibrated pressure-capacitance mapping relationship. k .

[0049] Step S7 (Multi-point Output): The processor 44 outputs the position coordinates and pressure values ​​of the identified K pressure application points in the form of data frames. Each data frame contains K sets of data, and each set of data contains the planar coordinates (X, Y, X) of the point. k Y k ) and pressure value F k This enables simultaneous detection of multi-point pressure distribution.

[0050] In the preferred embodiment described above, steps S5 to S7 are executed in a synchronized loop with steps S0 to S4 at a frame rate of not less than 50Hz, thereby achieving real-time multi-point pressure detection using connected component analysis. Users can choose between the direct point-by-point output method (step S4) and the connected component analysis method (steps S5 to S7), or use both methods simultaneously, to obtain detection results of different granularities, depending on specific application requirements.

[0051] To ensure smooth real-time detection, the scanning frame rate of the signal processing control unit 4 is no less than 50Hz. The analog-to-digital converter 43 preferably uses a resolution of 12 bits or more to distinguish minute capacitance changes caused by minute pressure.

[0052] The preferred materials and parameters of each component in this embodiment are as follows: the rigid substrate 5a is selected from FR-4 grade PCB board or soda-lime glass substrate, with a thickness of 0.5mm to 2mm; the flexible substrate 5b is a polyimide film with a thickness of 25μm or 50μm; the driving line 11 and the sensing line 21 are copper foils with a line width of 50μm to 200μm and a line spacing of 100μm to 500μm; the sensing point pitch is 1mm to 10mm, preferably 5mm; the compressible dielectric layer 3 is polyurethane foam with a thickness of 100μm to 500μm, and has good linear deformation characteristics in the pressure range of 0.1N to 20N; the scanning frame rate is 60Hz; and the analog-to-digital conversion resolution is 12 bits.

[0053] This embodiment can be applied to scenarios requiring high sensitivity, such as robotic tactile skin, intelligent mattress body pressure monitoring, and industrial pressing uniformity detection.

[0054] Example 2 (Coplanar Electrode Scheme) This embodiment shares the same core inventive concept as Embodiment 1, namely, achieving multi-point pressure detection through a cross-electrode array and scanning mechanism. The differences from Embodiment 1 lie in the electrode arrangement, the material and working mechanism of the sensing functional layer, and the manufacturing processes of the substrate and electrodes. The following description focuses only on the differences between this embodiment and Embodiment 1.

[0055] In terms of device structure, such as Figure 6 , Figure 7 As shown, the device in this embodiment mainly consists of a substrate, a coplanar electrode layer 6, a sensitive dielectric layer 7, and a signal processing and control unit 4. Unlike the structure in Embodiment 1 where the driving line 11 and the sensing line 21 are located on separate upper and lower layers and perpendicularly opposite each other, in this embodiment, the driving line 61 and the sensing line 62 are disposed in the same plane. In other words, in this embodiment, the electrodes in the first electrode group and the second electrode group are both located in the same conductive layer (i.e., the coplanar electrode layer 6), and they are physically on the same level rather than being on separate layers. Specifically, the coplanar electrode layer 6 is disposed on the upper surface of the substrate. This layer simultaneously contains multiple driving lines 61 extending along a first direction (e.g., the X-axis direction) and multiple sensing lines 62 extending along a second direction (e.g., the Y-axis direction). These lines are arranged in an alternating pattern, forming a driving line-sensing line pair (e.g., ...) near each intersection area. Figure 6 (As shown). The number of driving lines M and the number of sensing lines N are determined based on the required sensing area and spatial resolution. The pitch between adjacent driving lines and the pitch between adjacent sensing lines determine the density of sensing points. Typically, the pitch ranges from 1 mm to 10 mm, corresponding to a sensing point density of 1 to 100 sensing points per square centimeter. It should be noted that although photolithography can achieve finer linewidths and smaller line spacings, the density of sensing points is determined by the arrangement pitch of the driving and sensing lines, not by the linewidth or line spacing. For example, the above design can also employ an interdigitated electrode structure, which can improve the strength and sensitivity of the coupling capacitance by increasing the edge length of the electrode pairs without changing the sensing point pitch. Preferably, for conventional pressure distribution detection applications, the pitch is 5 mm; for applications requiring higher resolution, the pitch can be reduced to 1 mm.

[0056] Unlike Embodiment 1, which uses a rigid substrate plus a flexible substrate, this embodiment uses only a single substrate as the carrier base. The substrate can be a glass substrate, a rigid PCB, or a flexible PCB, with a glass substrate 8 being preferred to achieve optimal flatness and process compatibility. When using a glass substrate 8, it can be selected from soda-lime glass, borosilicate glass, or alkali-free glass, and its thickness is preferably in the range of 0.1 mm to 3 mm.

[0057] Unlike the electrode formation by etching copper foil in Embodiment 1, the fabrication method of the coplanar electrode layer 6 in this embodiment depends on the substrate type. When a glass substrate is used, a metal coating layer can first be formed on the surface of the glass substrate 8 by magnetron sputtering, evaporation, or chemical vapor deposition. The material can be selected from copper, aluminum, molybdenum, chromium, titanium, or a combination of the above metals. The coating thickness is preferably in the range of 50 nm to 500 nm. Then, the metal coating layer is patterned by photolithography and etching processes to form the patterns of driving lines 61 and sensing lines 62. Photolithography can achieve higher pattern precision. The linewidth of the driving lines and sensing lines is preferably 5 μm to 100 μm, and the line spacing is preferably 5 μm to 100 μm. Finer linewidths and line spacing can provide greater freedom in electrode design without changing the sensing point pitch. For example, the electrodes can be made into an interdigitated structure to increase the edge length between adjacent driving lines and sensing lines, thereby improving the strength and sensitivity of the edge coupling capacitance. When a rigid PCB substrate is used, the coplanar electrode layer 6 can be formed by conventional PCB etching processes; when a flexible substrate is used, the coplanar electrode layer 6 can be formed by laminating copper foil onto the surface of a polyimide or polyester film and then etching. The above-described method of using a glass substrate in conjunction with photolithography is only a preferred implementation of this embodiment, and not a necessary one.

[0058] Unlike the compressible dielectric layer 3 sandwiched between two electrode layers in Embodiment 1, the sensing functional layer in this embodiment is a sensitive dielectric layer 7 covering the coplanar electrode layer 6. This sensitive dielectric layer 7 is made of a material whose dielectric constant changes significantly under pressure, such as an elastomeric composite material doped with high dielectric constant fillers (e.g., barium titanate nanoparticles), and is coated on top of the patterned electrode layer. The signal processing control unit 4 is electrically connected to the drive line 61 and the sensing line 62 via metal leads, COG (Chipon Glass), or COF (Chip on Film).

[0059] Regarding the principle of pressure detection, such as Figure 7As shown, in the coplanar electrode scheme, the driving line 61 and the sensing line 62 form an edge coupling capacitance (i.e., horizontal electric field coupling E), rather than the vertical coupling capacitance in Embodiment 1. In the initial state without pressure, the edge coupling capacitance value C0 is determined by the initial dielectric constant ε0 of the sensitive dielectric layer 7, as well as the geometric spacing and linewidth between the electrodes. When external pressure P is applied to a certain location of the sensitive dielectric layer 7, the sensitive dielectric layer 7 at that location is compressed, and its density and molecular polarization characteristics change, causing the dielectric constant of that region to change from ε0 to ε1 (ε1>ε0). Since the capacitance value of the edge coupling capacitance is proportional to the dielectric constant of the dielectric layer (C∝ε), the edge coupling capacitance value between the driving line 61 and the adjacent sensing line 62 in that region increases accordingly. This capacitance change ΔC is monotonically correlated with the magnitude of the applied pressure, and a mapping relationship can be established through calibration. Similar to Example 1, since the capacitance change only occurs between electrode pairs near the pressure area, the planar coordinates of the pressure point can be determined by identifying the location of the changed intersection. Simultaneous detection of multiple pressure points enables multi-point pressure detection.

[0060] In terms of signal processing, the signal scanning and data processing methods in this embodiment are exactly the same as in Embodiment 1. Both employ a time-division scanning method that sequentially drives each driving line and reads all sensing lines in parallel (the scanning order can be set as needed, such as line-by-line, interlaced, or random), constructing a full-plane capacitance change distribution map, and then calculating the pressure magnitude and position coordinates of each pressure point. The basic method for multi-point detection (directly outputting the pressure value and coordinates of effective intersection points point-by-point) is described in steps S0 to S4 of Embodiment 1; the preferred implementation method using connected component analysis is described in steps S5 to S7 of Embodiment 1. Figure 4 , Figure 5 This preferred method can be selected to be executed or not, depending on the specific application requirements. Further details will not be provided here.

[0061] Regarding materials and parameters, the main difference between this embodiment and Embodiment 1 lies in the substrate and electrode manufacturing. In the preferred embodiment using a glass substrate and photolithography: the glass substrate 8 is borosilicate glass with a thickness of 0.3 mm to 1.1 mm; the metal coating layer is a copper / molybdenum stack with a total thickness of 200 nm to 300 nm, formed by magnetron sputtering; the electrode pattern is formed by photolithography and wet etching, with a linewidth of 20 μm and a line spacing of 20 μm; the sensing point pitch is 1 mm to 10 mm, preferably 5 mm, and can be reduced to 1 mm when higher resolution is required; the sensitive dielectric layer 7 is a silicone rubber composite material doped with barium titanate nanoparticles, with a coating thickness of 50 μm to 200 μm; the scanning frame rate is not less than 50 Hz; and the analog-to-digital conversion resolution is 12 bits or higher. When a non-preferred embodiment using a rigid PCB substrate combined with etched copper foil is adopted, lower costs can be obtained, but the electrode precision is relatively lower.

[0062] The preferred solution, which combines a glass substrate with metal coating and photolithography, offers higher dimensional stability and pattern accuracy compared to the PCB / flexible circuit board solution in Example 1, making it particularly suitable for applications requiring high-density arrays and high spatial resolution. Furthermore, since it requires only a single conductive layer, its manufacturing cost is lower and its overall thickness is thinner.

[0063] This embodiment is particularly suitable for scenarios requiring high-density pressure distribution detection, such as high-precision industrial pressure distribution measurement, micro tactile sensor arrays, and wearable devices requiring ultra-thin structures.

Claims

1. An array-type capacitive pressure sensing device, characterized in that, include: The first electrode group includes a plurality of drive lines extending along a first direction; The second electrode group includes multiple sensing lines extending along a second direction. The first direction intersects the second direction, such that the driving line and the sensing line form multiple intersection points on the projection, and a coupling capacitor is formed between the driving line and the sensing line at each intersection point. A sensing layer is disposed near the drive line and the sensing line, and is used to convert external pressure into a change in the capacitance value of the coupling capacitor; A substrate for supporting the first electrode group and / or the second electrode group; And a signal processing control unit, electrically connected to the drive line and the sensing line, for applying an excitation signal to the drive line and receiving a coupling signal from the sensing line; The signal processing and control unit constructs a full-plane capacitance change distribution map by sequentially scanning each drive line and reading the signals of all sensing lines in parallel. Based on this distribution map, it determines the capacitance change at each intersection point and uses each valid intersection point as an independent pressure sensing point. It directly outputs the pressure value and position coordinates of each valid intersection point to achieve multi-point pressure detection.

2. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The number of drive lines M and the number of induction lines N are each independently selected from 4 to 512.

3. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The pitch between adjacent drive lines and the pitch between adjacent induction lines are 1 mm to 10 mm.

4. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The signal processing control unit determines the intersection points in the full-plane capacitance change distribution map where the capacitance change is greater than or equal to a preset threshold as valid change points, and determines the intersection points where the capacitance change is less than the threshold as invalid points.

5. The array-type capacitive pressure sensing device according to claim 4, characterized in that, For each intersection point that is determined to be valid, the signal processing control unit directly calculates the corresponding pressure value based on the capacitance change of the intersection point through a pre-stored mapping relationship, and determines its planar coordinates based on the row and column position of the intersection point. Multiple valid intersection points synchronously output their respective pressure values ​​and coordinate information.

6. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The signal processing control unit also includes a connected component analysis module, which performs connected component analysis on the full-plane capacitance change distribution map, merges multiple interconnected effective change intersections into the same connected component, and each connected component corresponds to an independent pressure application area, thereby realizing the identification and separation of multiple pressure application points in the preferred embodiment.

7. The array-type capacitive pressure sensing device according to claim 6, characterized in that, The signal processing control unit compares the capacitance change at each intersection point in the full-plane capacitance change distribution map with a preset threshold. Intersection points with capacitance changes greater than or equal to the threshold are determined as valid change points, while intersection points with capacitance changes less than the threshold are determined as invalid points. Subsequently, connected component analysis is performed on all intersection points determined as valid change points.

8. The array-type capacitive pressure sensing device according to claim 6, characterized in that, For each identified connected component, the signal processing control unit calculates the weighted average of the position coordinates of all valid intersections within the connected component as the position coordinates of the pressure application point, with the weight being the absolute value of the capacitance change at each intersection. The signal processing control unit calculates the corresponding pressure value based on the capacitance change at each intersection within the connected component, specifically by taking the pressure value corresponding to the maximum capacitance change among all valid intersections within the connected component as the pressure value of the pressure application point, or by taking the average or weighted average of the capacitance changes at all valid intersections within the connected component and mapping it to the pressure value.

9. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The signal processing control unit completes a full array scan in the initial state without external pressure, obtains the initial capacitance value of each intersection point, and stores it as a reference capacitance matrix; in the working state, the capacitance matrix obtained in real time is subtracted from the reference capacitance matrix point by point to obtain the difference matrix, which serves as the full-plane capacitance variation distribution map.

10. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The first electrode group and the second electrode group are arranged opposite to each other and spaced apart. The conductive layer where the driving line is located and the conductive layer where the sensing line is located are two separate layers, separated from each other in the vertical direction. The substrate includes a rigid substrate and a flexible substrate. The first electrode group is disposed on the rigid substrate and the second electrode group is disposed on the flexible substrate. The sensing functional layer is a compressible dielectric layer sandwiched between the first electrode group and the second electrode group. At each intersection, the driving line and the sensing line are perpendicular to each other in the vertical direction to form a vertical coupling capacitor. When the external pressure causes the compressible dielectric layer to undergo local compression deformation, the coupling capacitance value at the corresponding intersection changes.

11. The array-type capacitive pressure sensing device according to claim 10, characterized in that, The rigid substrate is selected from rigid PCB circuit boards or glass substrates, and the flexible substrate is a flexible circuit board. The flexible circuit board is electrically connected to the signal processing control unit by pressing, welding or conductive adhesive bonding. The compressible dielectric layer is made of elastic foam material or dielectric elastomer. The material includes at least one of polyurethane, polyester, polypropylene, acrylic acid and silicone rubber, and its thickness is 10μm to 5mm.

12. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The electrodes in the first electrode group and the second electrode group are located in the same conductive layer, and the driving line and the sensing line are located in the same plane and are arranged in an alternating manner; the substrate is a glass substrate, a rigid PCB circuit board, or a flexible circuit board; the sensing functional layer is a sensitive dielectric layer covering the driving line and the sensing line; when external pressure is applied to the sensitive dielectric layer, the dielectric constant of the sensitive dielectric layer at the pressure location changes, causing a change in the coupling capacitance value between the driving line and the sensing line at the corresponding location.

13. The array-type capacitive pressure sensing device according to claim 12, characterized in that, The substrate is preferably a glass substrate, and the conductive layer is a metal coating layer disposed on the surface of the glass substrate. The driving lines and the sensing lines are patterned by photolithography on the metal coating layer. The glass substrate is selected from soda-lime glass, borosilicate glass, or alkali-free glass, and its thickness is 0.1 mm to 3 mm. The metal coating layer is formed by magnetron sputtering, evaporation, or chemical vapor deposition, and its material is selected from copper, aluminum, molybdenum, chromium, titanium, or a combination of the above metals. The coating thickness is 50 nm to 500 nm. The linewidth of the driving lines and the sensing lines is 5 μm to 100 μm, and the line spacing is 5 μm to 100 μm.

14. The array-type capacitive pressure sensing device according to claim 12, characterized in that, The sensitive dielectric layer is composed of an elastomeric composite material doped with fillers of high dielectric constant.

15. The array-type capacitive pressure sensing device according to claim 1, characterized in that, The scanning frame rate of the signal processing control unit is not less than 50Hz.

16. An array-type capacitive pressure detection method, applied to the apparatus according to any one of claims 1-15, characterized in that, Includes the following steps: S1: Apply excitation signals to each drive line in the first electrode group in sequence; S2: When each drive line is energized, the coupling signal is read from all the induction lines in the second electrode group to obtain the coupling capacitance value at all intersections. S3: Construct a real-time capacitance matrix based on the coupling capacitance values ​​at each intersection point, and compare it with the pre-stored reference matrix to generate a full-plane capacitance variation distribution map; S4: Analyze the capacitance change distribution map, and determine the intersection points where the capacitance change is greater than or equal to a preset threshold as valid change points. For each valid change point, calculate the corresponding pressure value directly based on its capacitance change through a pre-stored mapping relationship, and determine its planar coordinates based on the row and column positions of the intersection point. Output the pressure value and coordinate information of each valid point simultaneously to achieve multi-point pressure detection. S5: Execute steps S1 to S4 in a loop at a frame rate of not less than 50Hz to achieve real-time multi-point pressure detection.

17. The array-type capacitive pressure detection method according to claim 16, characterized in that, Step S4 further includes the following preferred implementation: performing connected component analysis on all intersections determined to be valid change points, and merging multiple interconnected valid change points into a connected component using four-neighbor or eight-neighbor connectivity rules, with each connected component corresponding to an independent pressure application area; for each connected component, calculating the pressure value corresponding to the connected component based on the capacitance change of each valid change point it contains, and determining the position coordinates of the pressure application point based on the row and column positions of each valid change point within the connected component; multiple connected components simultaneously output their respective pressure values ​​and position coordinates to achieve multi-point pressure detection.

18. The array-type capacitive pressure detection method according to claim 17, characterized in that, For each connected component, its position coordinates are obtained by weighted averaging of the position coordinates of all valid change points within the connected component, with the weight being the absolute value of the capacitance change at each intersection point; its pressure value is calculated in the following ways: the pressure value corresponding to the maximum capacitance change among all valid change points within the connected component is taken as the pressure value of that point, or the average or weighted average of the capacitance changes of all valid change points within the connected component is taken and then mapped to the pressure value.

19. The array-type capacitive pressure detection method according to claim 16, characterized in that, The reference matrix is ​​pre-acquired and stored in the initial state without external pressure through steps S1 to S3.

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