Temperature compensation type anti-crosstalk capacitive sensing array acquisition circuit and control method

Abstract

The invention belongs to the field of flexible microelectronic circuits, and provides a temperature compensation type anti-crosstalk capacitive sensing array acquisition circuit and a control method, and the circuit comprises an excitation signal driving source and a signal detection module. The excitation signal driving source comprises a main control unit, and the main control unit generates row gating signals and column gating signals; the capacitive sensing array performs temperature compensation based on the row gating signal to obtain a temperature compensation voltage signal; the signal detection module obtains capacitance signals of capacitance sensing units in columns in the capacitance type sensing array and converts the capacitance signals into modulation capacitance voltage signals. The temperature signal modulation module converts the temperature compensation voltage signal of the corresponding column into a modulation temperature voltage signal according to the column gating signal of the main control unit; the modulation capacitor voltage signal and the modulation temperature voltage signal are combined into a multiplexing signal through an analog adder, the multiplexing signal is transmitted to an upper computer through a main control unit for demodulation, and a compensated pressure signal is obtained; accurate temperature compensation and signal crosstalk suppression can be realized.

Description

Technical Field

[0001] This invention belongs to the field of flexible microelectronic circuit technology, specifically relating to a temperature-compensated anti-crosstalk capacitive sensing array acquisition circuit and control method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Capacitive pressure sensing arrays, with their high sensitivity, low power consumption, and excellent dynamic response characteristics, have shown great promise in high-precision pressure mapping fields such as robotic tactile perception, flexible electronic skin, and biomedical monitoring. However, as application scenarios increasingly demand higher measurement accuracy, reliability, and system integration, existing technologies face several key technical bottlenecks in practical deployments, particularly in areas such as measurement consistency under non-uniform temperature fields, signal crosstalk suppression in high-density integration, and high-integrity synchronous acquisition of multiple parameters.

[0004] First, under complex temperature field conditions, the spatial inhomogeneity of the temperature field poses a significant threat to the consistency of capacitance measurements, significantly affecting their consistency and stability. Although the temperature sensitivity of capacitance sensing units is generally lower than that of piezoresistive units, key parameters such as the dielectric constant of their dielectric layer material and electrode spacing still drift with changes in ambient temperature, leading to measurement errors in capacitance values. In practical applications, there is often a significant temperature gradient distribution on the surface of the sensing array, caused by factors such as local heat source contact or uneven power consumption within the array itself, resulting in sensing units in different regions operating under different temperature conditions. Traditional global temperature compensation strategies rely only on the temperature information of a single reference point, making it difficult to effectively perceive and respond to subtle differences in the spatial temperature distribution within the array. Therefore, they cannot achieve accurate differential correction for units in different temperature ranges, resulting in a decrease in overall measurement accuracy.

[0005] Secondly, with the continuous improvement of array integration, the resulting signal crosstalk problem severely restricts detection accuracy and reliability. To meet the requirements of high-density integration, capacitive sensing arrays generally adopt a row-column scanning architecture. However, in this architecture, unselected cells form parasitic capacitance paths with the measured (selected) cells through shared row and column traces, causing significant charge shunting and electric field coupling effects, resulting in signal crosstalk, which seriously interferes with the accurate extraction of the target cell signal. As the array size increases and the cell spacing decreases, the parasitic capacitance effect grows non-linearly, further aggravating signal distortion and severely restricting detection accuracy and reliability. Existing anti-crosstalk technologies, such as switch isolation, can suppress crosstalk to a certain extent, but often introduce additional parasitic parameters, or the sensor is limited by process and reliability in flexible substrate applications, making it difficult to achieve an effective balance between performance and integration.

[0006] Furthermore, existing systems suffer from architectural limitations in terms of multi-parameter synchronous acquisition and anti-interference capabilities. To achieve synchronous monitoring of pressure and temperature parameters, traditional solutions typically employ independent analog signal acquisition channels, performing signal conditioning and analog-to-digital conversion separately. This parallel architecture not only increases the number of system components, circuit board area, and overall cost, but also introduces additional channel mismatch errors due to the incomplete matching of analog front-end components between different channels in terms of gain, bias, and temperature drift characteristics. This disrupts the spatiotemporal synchronization and correlation accuracy of multi-parameter data, limiting the compensation effect based on multi-parameter fusion. In addition, regarding signal excitation and acquisition mechanisms, traditional DC or single-frequency AC excitation methods have concentrated spectrums, making them susceptible to low-frequency environmental noise and electromagnetic interference at specific frequencies. It is difficult to effectively avoid interference bands through frequency planning. Traditional single-carrier or time-division multiplexing acquisition methods have limitations in signal integrity and anti-interference capabilities, restricting the system's reliability and accuracy under dynamic operating conditions, leading to a significant decrease in the signal-to-noise ratio and reliability of the system in complex electromagnetic environments.

[0007] In summary, existing capacitive sensing arrays still need to achieve technological breakthroughs in key areas such as temperature gradient compensation, crosstalk suppression, and multi-parameter synchronous acquisition in order to meet the increasingly complex application scenarios and higher performance requirements of sensing systems. Summary of the Invention

[0008] To address the aforementioned issues, this invention proposes a temperature-compensated anti-crosstalk capacitive sensing array acquisition circuit and control method. Through element-based integrated design and dual-carrier frequency division multiplexing technology, this invention significantly improves the accuracy, integration, and anti-interference capability of the capacitive sensing system. Each capacitive sensing element has a built-in independent temperature compensation module that can sense local temperature in real time and generate a compensation signal. This signal is then modulated onto an auxiliary carrier by an analog multiplier, separating it from the modulated capacitor pressure signal carried by the main carrier in the frequency domain. The two signals are combined into a single composite signal by an analog adder, enabling synchronous acquisition with only a single ADC channel, effectively overcoming multi-channel mismatch and simplifying the system structure. The receiving end employs a digital quadrature demodulation algorithm to accurately separate and restore pressure and temperature information, achieving real-time and accurate compensation in the digital domain. Simultaneously, a symmetrical circuit design based on the virtual short characteristics of operational amplifiers ensures that all unselected row and column terminals remain at the same potential, fundamentally eliminating parasitic charge transfer paths and providing high-reliability crosstalk suppression capabilities for high-density arrays without relying on switching devices.

[0009] According to some embodiments, the first aspect of the present invention provides a temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit, which adopts the following technical solution: A temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit includes an excitation signal driving source and a signal detection module, wherein the excitation signal driving source is connected to a column gating module and a temperature signal modulation module, respectively. The excitation signal driving source includes a main control unit, which generates row gating signals and column gating signals to activate specific rows and columns in the capacitive sensor array; The capacitive sensing array is based on row gating signals, which convert the temperature signals of the capacitive sensing units in the corresponding row into temperature-compensated voltage signals. The signal detection module is connected to the capacitive sensing array and the column gating module respectively. Based on the column gating signal transmitted by the column gating module, the capacitance signal of the capacitive sensing unit in the corresponding column is converted into a modulated capacitor voltage signal. The temperature signal modulation module converts the temperature compensation voltage signal of the corresponding column into a modulated temperature voltage signal according to the column selection signal of the main control unit. The modulated capacitor voltage signal and the modulated temperature voltage signal are combined into a multiplexed signal by an analog adder, and the multiplexed signal is transmitted to the host computer through the main control unit for demodulation to obtain the compensated pressure signal.

[0010] Furthermore, the excitation signal driving source also includes a first direct digital frequency synthesizer and a row strobe bus; The main control unit controls the first direct digital frequency synthesizer to generate an excitation signal, which is then used to excite the capacitive sensing array via a row strobe bus.

[0011] Furthermore, the row strobe bus determines the corresponding row strobe signal line based on the row strobe signal, and a voltage divider resistor is connected in series at the rear end of each row strobe signal line, with one end of the voltage divider resistor connected to the corresponding row line in the capacitive sensing array. All row strobe signal lines are connected to a pull-down resistor, with one end of the pull-down resistor connected to the system ground potential.

[0012] Furthermore, the capacitive sensing array comprises m×n capacitive sensing units, and any 2×2 capacitive sensing units are combined with a temperature compensation module to form a capacitive sensing array element; the voltage input terminal of the temperature compensation module is connected to a DC power supply module, and the voltage output terminal of the temperature compensation module is connected to a temperature compensation circuit. The temperature compensation module performs temperature compensation on the temperature signal of the capacitive sensing unit in the capacitive sensing array to obtain a temperature compensation voltage signal, which is then sent to the temperature signal modulation module via a temperature compensation line.

[0013] Furthermore, the temperature compensation module adopts a Wheatstone bridge circuit structure, which includes a reference arm connected in parallel and a fixed resistor arm. The reference arm includes a temperature sensor and a precision adjustable resistor connected in series, and the temperature sensor and the precision adjustable resistor are also connected to a DC power supply module. The fixed resistor arm includes a first fixed resistor and a second fixed resistor connected in series, and the first fixed resistor and the second fixed resistor are grounded. The two output terminals of the Wheatstone bridge circuit are respectively connected to the non-inverting input terminal and the inverting input terminal of the first operational amplifier.

[0014] Furthermore, the signal detection module includes multiple signal detection units, each of which includes a second operational amplifier, a feedback capacitor, and a feedback resistor; The inverting input of the second operational amplifier is connected to each column of the capacitive sensor array, the non-inverting input of the second operational amplifier is grounded, and the output of the second operational amplifier is connected to the column gating module. The feedback capacitor and the feedback resistor are connected in parallel and then connected between the inverting input and output of the second operational amplifier.

[0015] Furthermore, the column gating module includes a column gating bus, which is connected to the signal detection module; The column gating bus acquires the column gating signal generated by the main control unit and activates the corresponding column in the capacitive sensing array; The column strobe bus is also connected to the analog adder, sending the modulation capacitor voltage signal generated by the signal detection module to the analog adder.

[0016] Furthermore, the temperature signal modulation module includes a temperature gating bus, a second direct digital frequency synthesizer, and an analog multiplier; The temperature gating bus acquires the column gating signal generated by the main control unit, selects the temperature compensation voltage signal of the corresponding column in the capacitive sensing array, and sends it to the analog multiplier. The second direct digital frequency synthesizer generates an auxiliary carrier based on the control signal from the main control unit and sends it to the analog multiplier; The temperature compensation voltage signal and the auxiliary carrier are multiplied by an analog multiplier to obtain a modulated temperature voltage signal, which is then sent to an analog adder.

[0017] According to some embodiments, the second aspect of the present invention provides a control method for a temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit, employing the following technical solution: The control method for a temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit includes: The main control unit in the excitation signal drive source generates column gating signals and row gating signals, and sends the column gating signals to the column gating module and the temperature signal modulation module respectively; The column gating module activates the corresponding column in the capacitive sensor array according to the column gating signal; the excitation signal drive source activates the corresponding row in the capacitive sensor array according to the column gating signal. The temperature compensation module acquires the temperature signals of the capacitive sensing units in the active row and active column, performs temperature compensation on the temperature signals to obtain the temperature compensation voltage signal of the active row, and sends the temperature compensation voltage signal of the active row to the temperature signal modulation module through the temperature compensation line. The signal detection module acquires the capacitance signal of the capacitance sensing unit in the active column, performs modulation conversion to obtain the modulated capacitor voltage signal, and sends it to the column gating signal line of the active column in the row gating module. The temperature signal modulation module multiplies the temperature compensation voltage signal of the active row with the auxiliary carrier generated by the second direct digital frequency to obtain the modulated temperature voltage signal. The analog adder receives the modulated capacitor voltage signal and the modulated temperature voltage signal from the column gating module and combines them into a multiplexed signal. The multiplexed signal is transmitted to the host computer through the main control unit for demodulation to obtain the compensated pressure signal.

[0018] Further, the process of transmitting the multiplexed signal to the host computer via the main control unit for demodulation to obtain the compensated pressure signal includes: The main control unit sends the multiplexed signal to the digital quadrature demodulation module in the host computer after ADC conversion; The digital quadrature demodulation module preprocesses the multiplexed signal to obtain the preprocessed multiplexed signal; The pressure amplitude is obtained by multiplying the preprocessed multiplexed signal with the pressure reference signal and then filtering it. The preprocessed multiplexed signal is multiplied with the temperature reference signal and then filtered to obtain the temperature amplitude. The actual pressure value is obtained after linear correction of the pressure amplitude. The actual temperature value is determined by looking up a table based on the temperature amplitude. The compensated pressure signal is obtained based on the temperature compensation coefficient, the actual temperature value, and the actual pressure value.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The core of the acquisition circuit proposed in this invention lies in an array-based capacitive sensing structure, in which four capacitive sensing units are integrated into a basic array element, and an independent temperature compensation module is embedded within it. This module can sensitively sense local temperature fluctuations within the array element and convert them into a corresponding compensation voltage signal; this DC voltage signal is then modulated to a preset auxiliary carrier frequency via an analog multiplier.

[0020] This invention enables efficient synchronous signal acquisition by employing a dual-carrier frequency division multiplexing strategy: the modulation capacitor voltage signal is carried by the main carrier frequency, while the auxiliary carrier carrying temperature information is separated from it in the frequency domain. The two are combined into a single composite signal using an analog adder, allowing synchronous acquisition to be completed using only a single ADC channel. This greatly simplifies the system architecture and improves consistency between channels. In the signal processing backend, an algorithm based on digital quadrature demodulation is used to accurately separate and recover the amplitude information of the pressure and temperature signals from the composite signal, ultimately achieving real-time and accurate temperature compensation for pressure readings in the digital domain.

[0021] In terms of crosstalk prevention, this invention adopts a symmetrical design based on the virtual short characteristics of operational amplifiers to ensure that the row and column terminals of all unselected capacitive sensing units are simultaneously maintained at the same reference potential. This eliminates the parasitic charge transfer path caused by potential difference in principle, providing high-reliability crosstalk suppression capability for high-density arrays that is independent of the performance of switching devices. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is an overall architecture diagram of a temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit according to an embodiment of the present invention; Figure 2 This is a diagram showing the physical layout and topology of the capacitive sensor array in an embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit structure of the temperature compensation module in an embodiment of the present invention; Figure 4 This is a schematic diagram of the circuit structure of the capacitive sensing array element in an embodiment of the present invention; Figure 5 This is the signal processing and temperature compensation process architecture for capacitive sensing arrays in this embodiment of the invention; In the picture: 1-Excitation signal driver source; 101-First direct digital frequency synthesizer; 102-Row gating bus; 103-Row gating signal; 104-Voltage divider resistor; 105-Pull-down resistor; 2-Capacitive sensor array; 201-Temperature compensation module; 202-Voltage input terminal; 203-Temperature compensation circuit; 204-Temperature sensor; 205-Precision adjustable resistor; 206-First operational amplifier; 207-First fixed resistor; 208-Second fixed resistor; 209-Capacitive sensing unit; 3-Signal detection module; 301-Second operational amplifier; 302-Feedback capacitor; 303-Feedback resistor; 4-Column gating module; 401-Column gating bus; 402-Column gating signal; 5-Temperature signal modulation module; 501-Temperature gating bus; 502-Second direct digital frequency synthesizer; 503-Analog multiplier; 6-Analog adder. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0028] Example 1 Existing capacitive sensor arrays suffer from the following problems in applications: First, temperature drift and local compensation are challenging. The capacitance value is affected by the temperature sensitivity of parameters such as dielectric constant and electrode spacing, leading to measurement errors. This is especially true when there is a temperature gradient on the array surface. Traditional global temperature compensation strategies struggle to detect and compensate for such localized and differentiated temperature changes, resulting in a decrease in overall measurement accuracy. Second, signal crosstalk makes it difficult to guarantee detection accuracy. In row and column scanning architectures, unselected cells and selected cells can form parasitic capacitance paths through shared traces, causing charge shunting or electric field coupling, resulting in signal crosstalk that severely interferes with the accurate detection of minute capacitance changes. Third, multi-parameter synchronous acquisition and system anti-interference capabilities are insufficient. To achieve synchronous temperature and pressure measurements, traditional solutions often require independent signal acquisition channels. This not only increases system complexity and cost but also introduces new errors due to inconsistencies between multiple channels. Furthermore, in complex electromagnetic environments, sensor arrays are susceptible to external interference, and traditional single-carrier or time-division multiplexing acquisition methods have limitations in signal integrity and anti-interference capabilities, restricting the reliability and accuracy of the system under dynamic operating conditions.

[0029] Based on the above problems, this embodiment provides a temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit, such as... Figure 1 As shown, it includes an excitation signal drive source 1, a capacitive sensor array 2, a signal detection module 3, a column gating module 4, a temperature signal modulation module 5, and an analog adder 6.

[0030] The excitation signal driving source 1 is connected to the column selection module 4 and the temperature signal modulation module 5, respectively. The excitation signal driving source 1 includes a main control unit, which generates a row selection signal 103 and a column selection signal 402 to activate specific rows and columns in the capacitive sensor array. The capacitive sensing array 2 converts the temperature signal of the capacitive sensing unit 209 in the corresponding row into a temperature compensation voltage signal based on the row selection signal 103. The signal detection module 3 is connected to the capacitive sensing array 2 and the column gating module 4 respectively. Based on the column gating signal 402 transmitted by the column gating module 4, the capacitance signal of the corresponding column's capacitive sensing unit 209 is converted into a modulated capacitor voltage signal. The temperature signal modulation module 5 converts the temperature compensation voltage signal of the corresponding column into a modulated temperature voltage signal according to the column selection signal 402 of the main control unit. The analog adder 6 combines the modulation capacitor voltage signal and the modulation temperature voltage signal into a multiplexed signal, and then transmits the multiplexed signal to the host computer through the main control unit for demodulation to obtain the compensated pressure signal.

[0031] In a specific embodiment, the excitation signal driving source 1 includes a main control unit (MCU), a first direct digital frequency synthesizer (DDS) 101, a first serial communication interface (SPI-01), a second serial communication interface (SPI-02), a row strobe bus 102, and a row strobe signal 103. The MCU, as the control core of the system, controls the first DDS 101 via the SPI-01 serial communication interface to generate a 100kHz sine wave signal as the excitation source for the capacitive sensing array 2. Simultaneously, the MCU generates the row strobe signal 103 through binary encoding, controlling the row strobe bus 102 to activate a specific row. It should be noted that the first DDS 101 can be a 100kHz sine wave generator; and the row strobe bus 102 is controlled by a row multiplexer to activate a specific row, where the row multiplexer is set to m rows.

[0032] In the excitation signal driving source 1, a voltage divider resistor 104 is connected in series at the end of each row selection signal line, and a pull-down resistor 105 is configured for all row selection signal lines to connect to the system ground potential. One end of the voltage divider resistor 104 is connected to the corresponding row line in the capacitive sensing array; the other end of the pull-down resistor 105 is connected to the system ground potential. When a row selection signal line is selected, an excitation signal is applied to its corresponding row selection signal line; while for all unselected row selection signal lines, the driving end of its row selection signal line is stably maintained at the system ground potential through the pull-down resistor 105.

[0033] In this embodiment, the excitation signal drive source 1 effectively suppresses signal crosstalk by providing a clear and stable low-impedance reference potential for the unselected signal lines, thereby ensuring the integrity and measurement accuracy of the excitation signal along the selection path. In other words, this embodiment constructs a crucial potential management mechanism by connecting voltage divider resistors 104 in series at the rear end of all row selection signal lines and uniformly configuring pull-down resistors 105 to the system ground potential for them: when a row is selected, the excitation signal can be effectively applied to the target cell; while for all unselected rows, their drive terminals are forced to stabilize at the system ground potential due to the pull-down resistors 105. This is equivalent to establishing a low-impedance "discharge" path for potential parasitic capacitance and electric field coupling paths, rapidly guiding the charge that has entered the unselected lines due to coupling to the system ground potential, greatly reducing charge shunting and electric field coupling effects. The result is a significant reduction in signal crosstalk from the source, ensuring the accuracy and reliability of detecting minute capacitance changes in target cells in high-density arrays.

[0034] In a specific embodiment, the capacitive sensor array 2 includes m×n capacitive sensing units 209. Any 2×2 capacitive sensing units 209 and a temperature compensation module 201 are combined to form a capacitive sensing array element. The central region of the capacitive sensing array element integrates a temperature compensation module 201 for real-time sensing of local temperature changes in the array element. A capacitive sensing unit 209 is arranged around the temperature compensation module 201. It can be understood that the capacitive sensor array 2 adopts a unique array element design, with 2×2 capacitive sensing units 209 and a temperature compensation module 201 combined to form a capacitive sensing array element.

[0035] In a specific embodiment, the signal detection module 3 includes multiple signal detection units, each of which is essentially a capacitor-to-voltage conversion circuit, including a second operational amplifier 301, a parallel feedback capacitor 302, and a feedback resistor 303, which is a standard charge amplifier configuration. The inverting input terminal of the second operational amplifier 301 is connected to each column of the capacitive sensing array 2, the non-inverting input terminal of the second operational amplifier 301 is grounded, and the output terminal of the second operational amplifier 301 is connected to the column selection module 4; the feedback capacitor 302 and the feedback resistor 303 are connected in parallel between the inverting input terminal and the output terminal of the second operational amplifier 301; this capacitor-to-voltage conversion circuit design has dual functions: First, in the non-selected state, based on the virtual short characteristic of the second operational amplifier 301, its inverting input terminal (i.e., the column line connection point) is forced to maintain the same potential as its non-inverting input terminal (grounded), i.e., the system ground potential. Since all row strobe signal lines are also placed at the system ground potential through pull-down resistors 105 at this time, there is no potential difference across all unselected capacitive sensing units 209, achieving effective charge clearing and thus inherently suppressing crosstalk from the circuit principle.

[0036] Secondly, in the gating state, a 100kHz excitation signal is applied to the row gating signal line of the selected capacitance sensing unit 209. The current caused by the change in its charge is integrated / converted by the operational amplifier, and a voltage is accumulated on the feedback capacitor 302. Thus, the change in the capacitance value of the capacitance sensing unit 209 is linearly converted into a change in the amplitude of the output voltage, completing the signal detection and outputting a 100kHz modulated pressure signal.

[0037] Specifically, the column gating module 4 includes a column gating bus 401 and a column gating signal 402. The column gating bus 401 is controlled by the column gating signal 402 generated by the main control unit MCU. It is used to select the target column from multiple column detection signals and output the modulation capacitor voltage signal of the target column to the subsequent processing link—the analog adder 6. It can be understood that the column gating bus 401 uses a column multiplexer to achieve the selection of the target column; the column multiplexer is set to n columns here.

[0038] It is understandable that the voltage signal path is formed by the main control unit MCU, the row selection bus 102 and the column selection bus 401, while the temperature signal path is processed independently but synchronously. For details, please refer to the temperature signal modulation module 5, which includes the temperature selection bus 501, the second direct digital frequency synthesizer 502 and the analog multiplier 503. The temperature compensation voltage signal (essentially a DC voltage signal) output by the temperature compensation module 201 in each capacitive sensing element is sent to the temperature signal modulation module 5 via the temperature compensation line 203 and guided to the temperature gating bus 501. The temperature gating bus 501 is also coordinated and controlled by the column gating signal 402 to ensure that when the pressure signal of a certain column is selected, the temperature compensation voltage signal of the corresponding capacitive sensing element in that column can be selected simultaneously.

[0039] The selected temperature compensation voltage signal is then sent to an analog multiplier 503. Simultaneously, the main control unit (MCU) controls a second direct digital frequency synthesizer 502 via the second serial communication interface SPI-02 to generate a 45kHz sine wave as an auxiliary carrier wave. This auxiliary carrier wave is multiplied by the DC temperature voltage signal in the analog multiplier 503, modulating the temperature information onto the auxiliary carrier wave to form a modulated temperature voltage signal.

[0040] Finally, the 100kHz modulated capacitor voltage signal and the 45kHz modulated temperature voltage signal are input together into an analog adder 6 for frequency division multiplexing, merging them into a composite signal. This composite signal is synchronously sampled and digitized by a high-precision analog-to-digital converter (ADC) within the main control unit MCU.

[0041] In the digital domain, the main control unit (MCU) uses a digital quadrature demodulation algorithm to separate and demodulate the digital quantities of pressure and temperature information from the composite signal in real time, and performs real-time digital compensation on the pressure reading based on the temperature reading, finally outputting a pressure measurement value with accurate temperature correction.

[0042] like Figure 2The figure shows the physical layout and topology of the capacitive sensor array 2 in this embodiment of the invention. The figure clearly shows the basic array element organization of the capacitive sensing array, consisting of 2×2 capacitive sensing units 209. Each capacitive sensing array element integrates an independent temperature compensation module 201. Each temperature compensation unit has a unified DC power supply module, meaning that the voltage input terminals 202 of all temperature compensation modules 201 can be excited by the DC power supply module. When a column is selected, the specific temperature compensation module 201 can be located through the coordinated selection of the column selection bus 401 (column multiplexer). The temperature compensation voltage signal output by the temperature compensation module 201 is transmitted via the temperature compensation line 203 to the subsequent analog multiplier 503, where it is modulated into a 45kHz modulated temperature signal, thereby providing real-time and accurate temperature compensation for the capacitive sensing units 209 in the currently selected capacitive sensing array element.

[0043] This embodiment integrates an independent temperature compensation module 201 within each capacitive sensing element and uses a unified DC power supply module and column selection bus 401 for coordinated addressing. This achieves differentiated, real-time temperature compensation for each sensing unit in the array, effectively overcoming the problem of inaccurate sensing and correction failure when faced with temperature gradient distribution on the array surface, a problem inherent in traditional global temperature compensation strategies. Simultaneously, this design modulates the temperature compensation signal into a specific frequency AC signal via a subsequent analog multiplier 503. This allows for frequency division multiplexing with the pressure sensing signal during transmission and processing, enabling synchronous acquisition of multiple parameters in a single acquisition channel. This avoids the channel mismatch error and increased system complexity introduced by traditional multi-channel parallel architectures. Furthermore, it leverages the inherent anti-interference advantages of AC excitation, effectively avoiding low-frequency noise and specific electromagnetic interference in the environment through frequency planning. Therefore, it significantly improves the overall measurement accuracy, synchronization, and reliability of the system in complex temperature and electromagnetic environments.

[0044] like Figure 3 The diagram shows a schematic of the circuit structure of the temperature compensation module in an embodiment of the present invention. It can be seen that the temperature compensation module 201 internally adopts a Wheatstone bridge circuit structure and compensation mechanism. The Wheatstone bridge circuit structure includes a parallel reference arm and a fixed resistor arm. The reference arm includes a temperature sensor 204 and a precision adjustable resistor 205 connected in series. The temperature sensor 204 and the precision adjustable resistor 205 are also connected to a DC power supply module. The fixed resistor arm includes a first fixed resistor 207 and a second fixed resistor 208 connected in series. The first fixed resistor 207 and the second fixed resistor 208 are grounded. The two output terminals of the Wheatstone bridge circuit structure are respectively connected to the non-inverting input terminal and the inverting input terminal of the first operational amplifier 206.

[0045] A key feature of this Wheatstone bridge is the presence of a precision adjustable resistor 205 (R) on its reference arm.ref The resistance value of the precision adjustable resistor 205 is pre-calibrated and set according to the drift characteristics of each capacitive sensing unit 209 under typical temperature conditions. Through this preset, the Wheatstone bridge can accurately convert the ambient temperature change sensed by the Pt100 temperature sensor 204 into a compensation voltage signal that is opposite in direction and matches the amplitude of the temperature drift of each capacitive sensing unit 209.

[0046] like Figure 4 As shown, the specific internal structure of the capacitive sensing array element in the embodiment of the present invention is illustrated, and the specific integration position and wiring scheme of the temperature compensation module 201 in the capacitive sensing array element are presented. Specifically, each capacitive sensing element includes four capacitive sensing units (here, the sensing capacitance C is used). 11 C 12 C 21 C 22 This includes the spatial layout and electrical interconnection topology between each capacitive sensing unit 209 and the temperature compensation module 201. The capacitor-to-voltage conversion circuit is used to linearly convert the induced current generated by the capacitive sensing elements under 100kHz DDS AC excitation into the amplitude change of the output voltage, complete the signal detection, and obtain a 100kHz modulated capacitor voltage signal.

[0047] Among them, the second operational amplifier 301 operates in a virtual ground state, so that all the displacement current caused by the change in array element capacitance flows into the feedback network; the feedback capacitor 302 (C f The input current is integrated to convert the capacitance change into the output voltage amplitude, achieving high-sensitivity linear detection; feedback resistor 303 (R f This provides a DC discharge path to prevent charge accumulation from causing output saturation, and is connected to C. f Together, they form a phase compensation network to ensure the stability of the circuit at a 100kHz operating frequency. Simultaneously, the temperature compensation module 201 applies DC excitation to the Wheatstone bridge via the DC power supply module, and outputs a temperature compensation voltage signal V corresponding to the ambient temperature after sensing the surrounding capacitor temperature field. tn It is used for subsequent temperature compensation or independent temperature monitoring.

[0048] Example 2 This embodiment provides a control method for a temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit, including: The main control unit MCU in the excitation signal drive source 1 generates column gating signal 402 and row gating signal 103, and sends column gating signal 402 to column gating module 4 and temperature signal modulation module 5 respectively. The column gating module 4 activates the corresponding column in the capacitive sensor array 2 according to the column gating signal 402; the excitation signal drive source 1 activates the corresponding row in the capacitive sensor array 2 according to the column gating signal 402. The temperature compensation module 201 acquires the temperature signals of the capacitive sensing units 209 in the active row and active column, performs temperature compensation on the temperature signals, obtains the temperature compensation voltage signal of the active row, and sends the temperature compensation voltage signal of the active row to the temperature signal modulation module 5 via the temperature compensation line 203. The signal detection module 3 acquires the capacitance signal of the capacitance sensing unit 209 in the active column, performs modulation conversion to obtain the modulated capacitor voltage signal, and sends it to the column gating signal line of the active column in the row gating module. The temperature signal modulation module 5 multiplies the temperature compensation voltage signal of the active row with the auxiliary carrier generated by the second direct digital frequency to obtain the modulated temperature voltage signal. The analog adder 6 receives the modulation capacitor voltage signal from the column gating module 4 and the modulation temperature voltage signal from the temperature signal modulation module 5, and combines them into a multiplexed signal. The multiplexed signal is transmitted to the host computer through the main control unit for demodulation to obtain the compensated pressure signal.

[0049] Further, the process of transmitting the multiplexed signal to the host computer via the main control unit for demodulation to obtain the compensated pressure signal includes: The main control unit sends the multiplexed signal to the digital quadrature demodulation module in the host computer after ADC conversion; The digital quadrature demodulation module preprocesses the multiplexed signal to obtain the preprocessed multiplexed signal; The pressure amplitude is obtained by multiplying the preprocessed multiplexed signal with the pressure reference signal and then filtering it. The preprocessed multiplexed signal is multiplied with the temperature reference signal and then filtered to obtain the temperature amplitude. The actual pressure value is obtained after linear correction of the pressure amplitude. The actual temperature value is determined by looking up a table based on the temperature amplitude. The compensated pressure signal is obtained based on the temperature compensation coefficient, the actual temperature value, and the actual pressure value.

[0050] like Figure 5 The diagram illustrates the signal processing and temperature compensation architecture for a capacitive sensing array in an embodiment of the present invention. This process uses an MCU as the core control unit, synchronously samples the composite signal through an ADC channel, and performs separation, demodulation, and compensation processing of the pressure and temperature signals in the digital domain.

[0051] Specifically, the MCU generates row and column gating timings and controls the loading of excitation signals. The acquired raw data (multiplexed signals) is converted by the ADC and then sent to the digital quadrature demodulation module. At the demodulation end, the system generates a 100kHz pressure reference signal and a 45kHz temperature reference signal, respectively, as local carriers for quadrature demodulation.

[0052] The ADC data from the pressure and temperature channels are digitally multiplied with their corresponding reference signals, and then low-pass filtered by averaging to extract the in-phase and quadrature components of each channel. Amplitude calculations are performed based on the sum of squares and the square root to obtain the amplitudes of the pressure and temperature signals.

[0053] The pressure amplitude is linearly corrected to obtain the actual pressure value; the temperature amplitude is mapped using a lookup table to determine the actual temperature value. The system further calls a preset temperature compensation coefficient k, and based on the mathematical model "compensated pressure = actual pressure - k × actual temperature," performs temperature drift compensation in the digital domain, outputting the final compensated pressure result. This entire processing flow achieves coordinated execution of high-precision pressure signal detection and dynamic temperature compensation, effectively improving the sensor's measurement stability and accuracy in complex environments.

[0054] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit, characterized in that, It includes an excitation signal driving source and a signal detection module, wherein the excitation signal driving source is connected to the column gating module and the temperature signal modulation module, respectively; The excitation signal driving source includes a main control unit, which generates row gating signals and column gating signals to activate specific rows and columns in the capacitive sensor array; The capacitive sensing array is based on row gating signals, which convert the temperature signals of the capacitive sensing units in the corresponding row into temperature-compensated voltage signals. The signal detection module is connected to the capacitive sensing array and the column gating module respectively. Based on the column gating signal transmitted by the column gating module, the capacitance signal of the capacitive sensing unit in the corresponding column is converted into a modulated capacitor voltage signal. The temperature signal modulation module converts the temperature compensation voltage signal of the corresponding column into a modulated temperature voltage signal according to the column selection signal of the main control unit. The modulated capacitor voltage signal and the modulated temperature voltage signal are combined into a multiplexed signal by an analog adder, and the multiplexed signal is transmitted to the host computer through the main control unit for demodulation to obtain the compensated pressure signal.

2. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 1, characterized in that, The excitation signal driving source also includes a first direct digital frequency synthesizer and a row strobe bus; The main control unit controls the first direct digital frequency synthesizer to generate an excitation signal, which is then used to excite the capacitive sensing array via a row strobe bus.

3. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 1, characterized in that, The row selection bus determines the corresponding row selection signal line based on the row selection signal. Each row selection signal line has a voltage divider resistor connected in series at the end, and one end of the voltage divider resistor is connected to the corresponding row line in the capacitive sensing array. All row strobe signal lines are connected to a pull-down resistor, with one end of the pull-down resistor connected to the system ground potential.

4. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 1, characterized in that, The capacitive sensing array contains m×n capacitive sensing units. Any 2×2 capacitive sensing units and a temperature compensation module are combined to form a capacitive sensing array element. The voltage input terminal of the temperature compensation module is connected to a DC power supply module, and the voltage output terminal of the temperature compensation module is connected to a temperature compensation circuit. The temperature compensation module performs temperature compensation on the temperature signal of the capacitive sensing unit in the capacitive sensing array to obtain a temperature compensation voltage signal, which is then sent to the temperature signal modulation module via a temperature compensation line.

5. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 4, characterized in that, The temperature compensation module adopts a Wheatstone bridge circuit structure, which includes a reference arm connected in parallel and a fixed resistor arm. The reference arm includes a temperature sensor and a precision adjustable resistor connected in series, and the temperature sensor and the precision adjustable resistor are also connected to a DC power supply module. The fixed resistor arm includes a first fixed resistor and a second fixed resistor connected in series, and the first fixed resistor and the second fixed resistor are grounded. The two output terminals of the Wheatstone bridge circuit are respectively connected to the non-inverting input terminal and the inverting input terminal of the first operational amplifier.

6. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 1, characterized in that, The signal detection module includes multiple signal detection units, and each signal detection unit includes a second operational amplifier, a feedback capacitor, and a feedback resistor. The inverting input of the second operational amplifier is connected to each column of the capacitive sensor array, the non-inverting input of the second operational amplifier is grounded, and the output of the second operational amplifier is connected to the column gating module. The feedback capacitor and the feedback resistor are connected in parallel and then connected between the inverting input and output of the second operational amplifier.

7. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 1, characterized in that, The column gating module includes a column gating bus, which is connected to the signal detection module. The column gating bus acquires the column gating signal generated by the main control unit and activates the corresponding column in the capacitive sensing array; The column strobe bus is also connected to the analog adder, sending the modulation capacitor voltage signal generated by the signal detection module to the analog adder.

8. The temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 1, characterized in that, The temperature signal modulation module includes a temperature gating bus, a second direct digital frequency synthesizer, and an analog multiplier. The temperature gating bus acquires the column gating signal generated by the main control unit, selects the temperature compensation voltage signal of the corresponding column in the capacitive sensing array, and sends it to the analog multiplier. The second direct digital frequency synthesizer generates an auxiliary carrier based on the control signal from the main control unit and sends it to the analog multiplier; The temperature compensation voltage signal and the auxiliary carrier are multiplied by an analog multiplier to obtain a modulated temperature voltage signal, which is then sent to an analog adder.

9. A control method based on the temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit according to any one of claims 1-8, characterized in that, include: The main control unit in the excitation signal drive source generates column gating signals and row gating signals, and sends the column gating signals to the column gating module and the temperature signal modulation module respectively; The column gating module activates the corresponding column in the capacitive sensor array according to the column gating signal; the excitation signal drive source activates the corresponding row in the capacitive sensor array according to the column gating signal. The temperature compensation module acquires the temperature signals of the capacitive sensing units in the active row and active column, performs temperature compensation on the temperature signals to obtain the temperature compensation voltage signal of the active row, and sends the temperature compensation voltage signal of the active row to the temperature signal modulation module through the temperature compensation line. The signal detection module acquires the capacitance signal of the capacitance sensing unit in the active column, performs modulation conversion to obtain the modulated capacitor voltage signal, and sends it to the column gating signal line of the active column in the row gating module. The temperature signal modulation module multiplies the temperature compensation voltage signal of the active row with the auxiliary carrier generated by the second direct digital frequency to obtain the modulated temperature voltage signal. The analog adder receives the modulated capacitor voltage signal and the modulated temperature voltage signal from the column gating module and combines them into a multiplexed signal. The multiplexed signal is transmitted to the host computer through the main control unit for demodulation to obtain the compensated pressure signal.

10. The control method for the temperature-compensated anti-crosstalk capacitive sensor array acquisition circuit as described in claim 9, characterized in that, The process of transmitting the multiplexed signal to the host computer via the main control unit for demodulation to obtain the compensated pressure signal includes: The main control unit sends the multiplexed signal to the digital quadrature demodulation module in the host computer after ADC conversion; The digital quadrature demodulation module preprocesses the multiplexed signal to obtain the preprocessed multiplexed signal; The pressure amplitude is obtained by multiplying the preprocessed multiplexed signal with the pressure reference signal and then filtering it. The preprocessed multiplexed signal is multiplied with the temperature reference signal and then filtered to obtain the temperature amplitude. The actual pressure value is obtained after linear correction of the pressure amplitude. The actual temperature value is determined by looking up a table based on the temperature amplitude. The compensated pressure signal is obtained based on the temperature compensation coefficient, the actual temperature value, and the actual pressure value.

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