A circuit and method for improving touch measurement sensitivity

Abstract

The application provides a circuit and method for improving touch measurement sensitivity, a first end of a first switch is connected with an external touch capacitor, a second end of the first switch is connected with an upper plate of a first capacitor; a lower plate of the first capacitor is grounded; a first end of a second switch is connected with the first end of the first switch, a second end of the second switch is connected with a power supply; a first end of a third switch is connected with a second end of the first switch, a second end of the third switch is connected with the power supply; an inverting input end of a comparator is connected with the second end of the first switch, a non-inverting input end of the comparator is connected with a reference voltage; a fourth switch and a second capacitor are connected in parallel between the inverting input end and an output end of the comparator; an analog-to-digital converter and a data processing module. In the circuit for improving touch measurement sensitivity, the closer the two adjacent sampling values of the analog-to-digital converter are, the closer the capacitance of the touch capacitor and the first capacitor is. Therefore, the first capacitor can be corrected according to the difference between the two adjacent sampling values.

Description

Technical Field

[0001] This invention relates to the field of touch control, and in particular to a circuit and method for improving touch detection sensitivity. Background Technology

[0002] Existing charge transfer-based touch detection circuits typically include capacitors, switches, comparators, and digital-to-analog converters (DACs). Charge transfer is generally accomplished through a series of operations such as charging, discharging, and connection, followed by sampling the capacitance signal using an DAC. However, due to the large parasitic capacitance inherent in PCB manufacturing and numerous external interferences, the sensitivity of touch circuits in practical applications is insufficient, failing to detect touch actions. Conversely, increasing sensitivity can easily lead to false alarms due to external interference.

[0003] Therefore, improving the accuracy of touch detection and reducing the false alarm rate has become one of the urgent problems to be solved in this field. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a circuit and method for improving touch detection sensitivity, in order to solve the problems of low detection accuracy and high false alarm rate of touch circuits in the prior art.

[0005] To achieve the above and other related objectives, the present invention provides a circuit for improving touch detection sensitivity, comprising: a first switch, a second switch, a third switch, a first capacitor, a second capacitor, a fourth switch, a comparator, an analog-to-digital converter, and a data processing module;

[0006] The first end of the first switch is connected to an external contact capacitor, and the second end is connected to the upper plate of the first capacitor; the lower plate of the first capacitor is grounded.

[0007] The first end of the second switch is connected to the first end of the first switch, and the second end is connected to the power supply.

[0008] The first end of the third switch is connected to the second end of the first switch, and the second end is connected to the power supply.

[0009] The inverting input terminal of the comparator is connected to the second terminal of the first switch, and the non-inverting input terminal is connected to the reference voltage.

[0010] The fourth switch and the second capacitor are respectively connected in parallel between the inverting input terminal and the output terminal of the comparator;

[0011] The input terminal of the analog-to-digital converter is connected to the output terminal of the comparator for sampling electrical signals;

[0012] The data processing module is connected to the output of the analog-to-digital converter and is used to process the sampled signal output by the analog-to-digital converter.

[0013] Optionally, the reference voltage is 0V or half of the power supply voltage.

[0014] Optionally, the first switch, the second switch, the third switch, and the fourth switch are CMOS analog switches.

[0015] A system for improving touch measurement sensitivity includes: a touch capacitor and the circuit for improving touch measurement sensitivity;

[0016] The lower plate of the contact capacitor is grounded, and the upper plate is connected to the first terminal of the first switch, which is used to convert the touch action signal into an electrical signal.

[0017] Optionally, the contact capacitor is a parallel structure of multiple capacitors; wherein, the circuit for improving touch measurement sensitivity further includes a selector, and the multiple capacitors are respectively connected to the selection terminal of the selector inside the chip through pins, and the output terminal of the selector is connected to the first terminal of the first switch.

[0018] A method for improving touch measurement sensitivity includes the following steps:

[0019] S1: First sampling operation: close the second switch, after a first preset time, open the second switch and close the first switch, and calculate the change value of the voltage at the input terminal of the analog-to-digital converter through the data processing module, as the first sampling value;

[0020] The second sampling operation involves closing the third switch, then, after a second preset time, opening the third switch and closing the first switch. The data processing module calculates the change in voltage at the input terminal of the analog-to-digital converter, which is then used as the second sampling value.

[0021] S2: Repeat step S1 n times to obtain 2n+2 sample values; where n is a natural number greater than or equal to 0;

[0022] S3: The data processing module calculates the absolute difference between adjacent sampled values ​​and calculates the sum of 2n+1 absolute differences as the first change value;

[0023] S4: Repeat steps S1-S3 to obtain the second change value;

[0024] S5: Calculate the difference between the second change value and the first change value, and determine whether the difference is within a preset fluctuation range; if the difference is not within the preset fluctuation range, the data processing module sends a touch action signal to the next-level circuit; if the difference is within the preset range, the data processing module sends a no-action signal to the next-level circuit.

[0025] Optionally, a reset step is included before sampling: with the first switch, the second switch, and the third switch all open, the fourth switch is closed, and after a third preset time, the fourth switch is opened; wherein the third preset time is greater than or equal to the reset time of the comparator.

[0026] Optionally, the first sampled value satisfies formula (1):

[0027]

[0028] Where ΔV1 represents the first sampled value; C represents the capacitance of the contact capacitor; C1 represents the capacitance of the first capacitor; V CM This represents the voltage value at the non-inverting input of the comparator; V OS Vn represents the fixed offset voltage of the integrating circuit formed by the second capacitor and the comparator; VDD represents the power supply voltage; and C2 represents the capacitance value of the second capacitor.

[0029] Optionally, the second sampled value satisfies formula (2):

[0030]

[0031] Where ΔV2 represents the second sampled value; C represents the capacitance of the contact capacitor; C1 represents the capacitance of the first capacitor; V CM This represents the voltage value at the non-inverting input of the comparator; V OS Vn represents the fixed offset voltage of the integrating circuit formed by the second capacitor and the comparator; VDD represents the power supply voltage; and C2 represents the capacitance value of the second capacitor.

[0032] Optionally, when there is no touch, the first capacitor is corrected according to the capacitance value of the touch capacitor so that the first sampled value is equal to the second sampled value.

[0033] Optionally, when the contact capacitor is a parallel structure of multiple capacitors, each capacitor is connected to the selection terminal of the selector in the circuit for improving touch measurement sensitivity through a pin; each capacitor and the subsequent circuit form a sampling channel, and the average value of multiple sampling values ​​of multiple sampling channels is used as a virtual reference channel.

[0034] Optionally, step S2 can be replaced with:

[0035] If the first sampled value is closer to the midpoint of the range of the analog-to-digital converter than the second sampled value is closer to the midpoint of the range of the analog-to-digital converter, then the first sampling method is selected as the subsequent sampling method;

[0036] If the second sampled value is closer to the midpoint of the analog-to-digital converter's range than the first sampled value is closer to the midpoint of the analog-to-digital converter's range, then the second sampling method is selected as the subsequent sampling method.

[0037] As described above, the circuit and method for improving touch measurement sensitivity of the present invention have the following beneficial effects:

[0038] 1. In the circuit for improving touch measurement sensitivity of the present invention, the closer the sampled values ​​of different sampling methods of the analog-to-digital converter are, the closer the capacitance of the touch capacitor is to the capacitance of the first capacitor. Therefore, the first capacitor can be corrected based on the difference between the sampled values ​​of different sampling methods. When the circuit contains multiple channels of touch capacitors, each channel has a different correction value. The first capacitor can be corrected based on the average of multiple correction values, thereby improving the accuracy and sensitivity of the channel.

[0039] 2. In the circuit for improving touch measurement sensitivity of the present invention, the non-inverting input terminal of the comparator is connected to half of the power supply voltage, which optimizes its performance and makes the measurement results more accurate. Attached Figure Description

[0040] Figure 1 The diagram shows the structure of a touch detection circuit.

[0041] Figure 2 The diagram shown is a schematic representation of the circuit for improving touch measurement sensitivity according to the present invention.

[0042] Figure 3 The diagram shown illustrates the structure of the circuit for improving touch measurement sensitivity according to the present invention, which employs multiple sampling channels.

[0043] Component designation explanation

[0044] 1. Contact Capacitor

[0045] 2 First capacitor

[0046] 3 Comparators

[0047] 4. Analog-to-Digital Converter

[0048] 5. Data Processing Module

[0049] 6 Second capacitor

[0050] 7 Selectors Detailed Implementation

[0051] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0052] Please see Figures 1-3 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0053] like Figure 1 The diagram shown is a circuit structure diagram for touch detection, mainly including capacitor C. P Switch S1, Switch S0, Capacitor C S Capacitor C f Comparator and analog-to-digital converter. Closing switch S0 affects capacitor C. S During charging, after a certain period of time, switch S0 is disconnected and switch S1 is closed, and the comparator and capacitor C... f An integrating circuit is used to integrate the data. After the circuit stabilizes, the output of the integrating circuit is measured by the analog-to-digital converter. This process is repeated multiple times, measuring the output of the integrating circuit repeatedly and comparing the difference between two adjacent outputs to determine if there is a fluctuation, thus indicating whether an external touch action has occurred. This method has the following drawbacks: 1. The PCB board has large parasitic capacitance, and there is considerable external interference, which can lead to insufficient sensitivity in practical applications, making it impossible to detect touch; 2. If the sensitivity is increased, external interference can cause false alarms. Based on these reasons, this invention proposes a circuit to improve the sensitivity of touch measurement and solve the above problems.

[0054] Example 1

[0055] like Figure 2 As shown, this embodiment provides a circuit for improving touch measurement sensitivity, including a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first capacitor 2, a comparator 3, an analog-to-digital converter 4, a data processing module 5, and a second capacitor 6.

[0056] like Figure 2As shown, the first terminal of the first switch S1 is connected to an external contact capacitor 1, and the second terminal is connected to the upper plate of the first capacitor 2. The lower plate of the first capacitor 2 is grounded. In this embodiment, the first switch S1 is a CMOS analog switch. In actual production, other types of switches that perform turn-off operations based on control signals can also be selected as needed, and are not limited to this embodiment.

[0057] like Figure 2 As shown, the first terminal of the second switch S2 is connected to the first terminal of the first switch S1, and the second terminal is connected to the power supply VDD. The first terminal of the third switch S3 is connected to the second terminal of the first switch S1, and the second terminal is connected to the power supply VDD. In this embodiment, both the second switch S2 and the third switch S3 are CMOS analog switches. In actual production, other types of switches that perform turn-off operations based on control signals can be selected as needed, and this embodiment is not the limitation. It should be noted that the types of the first switch S1, the second switch S2, and the third switch S3 can be the same, different, or partially the same, which will not be elaborated here.

[0058] like Figure 2 As shown, the inverting input of the comparator 3 is connected to the second terminal of the first switch S1, and the non-inverting input is connected to the reference voltage.

[0059] Specifically, as an example, the reference voltage is 0V or half of the power supply voltage VDD. When the reference voltage is 0V, the non-inverting input of the comparator 3 is connected to the chip's ground; when the reference voltage is half of the power supply voltage VDD (i.e., the common-mode voltage Vcm), the circuit for improving touch measurement sensitivity performs optimally, resulting in more accurate measurement results.

[0060] like Figure 2 As shown, the fourth switch S4 and the second capacitor C2 are connected in parallel between the inverting input and output terminals of the comparator 3, respectively. It should be noted that the fourth switch S4 is a CMOS analog switch, and its type can be the same as or different from the first switch S1, the second switch S2, and the third switch S3. In actual production, other types of switches that perform turn-off operations based on control signals can also be selected as needed, not limited to this embodiment.

[0061] like Figure 2 As shown, the input terminal of the analog-to-digital converter 4 is connected to the output terminal of the comparator 3 for sampling electrical signals.

[0062] like Figure 2As shown, the data processing module 5 is connected to the output terminal of the analog-to-digital converter 4 and is used to process the sampled signal output by the analog-to-digital converter 4. The data processing module 5 includes, but is not limited to, storing sampled data or calculating the sum, difference, and absolute value between sampled values. The data processing module 5 stores each sampled data in its memory chip. According to actual needs, the processor in the data processing module 5 calculates the average value of the samples, the absolute difference between adjacent sampled values, and the sum of the sampled values. It should be noted that the data processing module 5 also includes other data processing functions, specifically processed according to actual needs, which are not listed here.

[0063] Example 2

[0064] like Figure 2 As shown, this embodiment provides a system for improving touch measurement sensitivity, including a touch capacitor 1 and the circuit for improving touch measurement sensitivity described in Embodiment 1.

[0065] like Figure 2 As shown, the lower plate of the contact capacitor 1 is grounded, and the upper plate is connected to the first terminal of the first switch S1, used to convert the touch action signal into an electrical signal. When a human touches the contact capacitor 1, the capacitance value of the contact capacitor 1 will change. If we can detect this change, we will naturally know that a touch action has occurred.

[0066] As another implementation of this embodiment, such as Figure 3 As shown, the contact capacitor 1 is a parallel structure of multiple capacitors. Each capacitor is connected to the selection terminal of the selector 7 inside the chip via pins, and each capacitor forms a sampling channel with the internal circuitry of the chip.

[0067] Example 3

[0068] This embodiment provides a method for improving touch measurement sensitivity, based on the circuit for improving touch measurement sensitivity described in Embodiment 1 or the system for improving touch measurement sensitivity described in Embodiment 2, including the following steps:

[0069] S1: First sampling operation, close the second switch S2, after a first preset time, open the second switch S2 and close the first switch S1, and calculate the change value of the voltage at the input terminal of the analog-to-digital converter 4 through the data processing module 5 as the first sampling value;

[0070] In the second sampling operation, the third switch S3 is closed, and after a second preset time, the third switch S3 is opened and the first switch S1 is closed. The data processing module 5 calculates the change in voltage at the input terminal of the analog-to-digital converter 4, which is then used as the second sampling value.

[0071] Specifically, the first sampled value satisfies formula (1):

[0072]

[0073] Where ΔV1 represents the first sampled value; C represents the capacitance of contact capacitor 1; C1 represents the capacitance of the first capacitor 2; V CM This represents the voltage value at the non-inverting input terminal Vcm of comparator 3; V OS Vn represents the fixed offset voltage of the integrating circuit formed by the second capacitor 6 and the comparator 3; VDD represents the low-frequency noise voltage of the comparator 3; C2 represents the voltage of the power supply VDD; and C2 represents the capacitance value of the second capacitor 6.

[0074] Specifically, the second sampled value satisfies formula (2):

[0075]

[0076] Where ΔV2 represents the second sampled value; C represents the capacitance of the contact capacitor; C1 represents the capacitance of the first capacitor; V CM This represents the voltage value at the non-inverting input of the comparator; V OS Vn represents the fixed offset voltage of the integrating circuit formed by the second capacitor 6 and the comparator 3; VDD represents the power supply voltage; and C2 represents the capacitance value of the second capacitor.

[0077] It should be noted that the sampling order of the first and second sampling operations is not fixed; the first sampling operation can be performed first, followed by the second sampling operation, or the second sampling operation can be performed first, followed by the first sampling operation.

[0078] As one implementation of the present invention, a reset step is included before sampling: with the first switch S1, the second switch S2, and the third switch S3 all open, the fourth switch S4 is closed, and after a third preset time, the fourth switch is opened; wherein, the third preset time is greater than or equal to the reset time of the comparator 3. In actual production, the third preset time can be selected as needed, and will not be elaborated here.

[0079] In another implementation of the present invention, when there is no touch input, the closer the sampled values ​​ΔV1 and ΔV2 of the analog-to-digital converter 4 are in two consecutive samples, the closer the capacitance values ​​of the touch capacitor 1 and the first capacitor 2 are. Therefore, the first capacitor 2 can be corrected based on the difference between two consecutive sampled values. Completing the correction before performing touch detection can greatly improve the detection accuracy. Figure 3As shown, when the circuit contains multiple channels of contact capacitor 1, each channel has a different correction value, which can improve the accuracy and sensitivity of the channel.

[0080] S2: Repeat step S1 n times to obtain 2n+2 sample values; where n is a consecutive natural number greater than or equal to 0.

[0081] Specifically, repeat the loop of "perform the first sampling operation first, then the second sampling operation"; or repeat the loop of "perform the second sampling operation first, then the first sampling operation".

[0082] S3: The absolute difference between adjacent sampled values ​​is calculated by the data processing module 5, and the sum of 2n+1 absolute differences is calculated as the first change value.

[0083] Specifically, the absolute difference satisfies formula (3):

[0084] Δ1=|ΔV2-ΔV1| (3)

[0085] Where Δ1 is the first absolute difference; ΔV1 represents the first sampled value; and ΔV2 represents the second sampled value.

[0086] More specifically, Δ1 satisfies formula (4):

[0087]

[0088] As can be seen from formula (4), the change in the output voltage of the circuit is unrelated to the voltage Vcm at the non-inverting input terminal of the comparator 3, the fixed offset voltage Vos, and the low-frequency noise voltage Vn. It is only related to the capacitance values ​​of the contact capacitor 1, the first capacitor 2, and the second capacitor 6. This means that the non-inverting input voltage of the comparator 3 generated by the equivalent resistance voltage divider, the fixed offset of the comparator 3, and the low-frequency noise have no effect on the output, thus resulting in higher accuracy.

[0089] When the analog-to-digital converter performs 2n+2 samplings

[0090] Δ1=|ΔV2-ΔV1|; Δ2=|ΔV3-ΔV2|;...Δ2n +1 =|ΔV2n +2 -ΔV2n+1|.

[0091] The first change value is Δ = Δ1 + Δ2 + Δ3 + ... + Δ2n +1 The accumulation process is also a kind of moving average algorithm, which plays a certain filtering role.

[0092] S4: Repeat steps S1-S3 to obtain the second change value.

[0093] S5: Calculate the difference between the second change value and the first change value, and determine whether the difference is within a preset fluctuation range; if the difference is not within the preset fluctuation range, the data processing module 5 sends a touch action signal to the next-level circuit; if the difference is within the preset range, the data processing module 5 sends a no-action signal to the next-level circuit.

[0094] As one implementation of this embodiment, step S2 is replaced with:

[0095] If the first sampled value is closer to the midpoint of the range of the analog-to-digital converter 4 than the second sampled value is closer to the midpoint of the range of the analog-to-digital converter 4, then the first sampling method is selected as the subsequent sampling method. That is, the third, fourth to nth sampling methods are the same as the first sampling method, so as to make the sampled value more accurate.

[0096] If the second sampled value is closer to the midpoint of the range of the analog-to-digital converter 4 than the first sampled value is closer to the midpoint of the range of the analog-to-digital converter 4, then the second sampling method is selected as the subsequent sampling method. That is, the third, fourth to nth sampling methods are the same as the second sampling method, so as to make the sampled value more accurate.

[0097] In another implementation of this embodiment, when the contact capacitor 1 is a parallel structure of multiple capacitors, each capacitor is connected to the selection terminal of the selector 7 through a pin. Each capacitor and the subsequent circuit form a sampling channel. The average value of the samples from multiple sampling channels is used as a virtual reference channel and together with the real reference channel as the final reference to correct the first capacitor C1. This effectively eliminates external interference to the first capacitor C1 and reduces the false alarm rate of touch detection. The real reference channel is located outside the chip and is not sensed by the capacitor. When there is no touch, if the system is subjected to external interference, the sampling values ​​of the reference channel and the sampling real channel fluctuate synchronously within a certain range. The data processing module outputs a no-action signal, thereby reducing the false alarm rate of touch detection.

[0098] In summary, this invention provides a circuit and method for improving touch measurement sensitivity, comprising: a first switch, a second switch, a third switch, a first capacitor, a second capacitor, a fourth switch, a comparator, an analog-to-digital converter (ADC), and a data processing module; the first terminal of the first switch is connected to an external contact capacitor, and the second terminal is connected to the upper plate of the first capacitor; the lower plate of the first capacitor is grounded; the first terminal of the second switch is connected to the first terminal of the first switch, and the second terminal is connected to a power supply; the first terminal of the third switch is connected to the second terminal of the first switch, and the second terminal is connected to a power supply; the inverting input terminal of the comparator is connected to the second terminal of the first switch, and the non-inverting input terminal is connected to a reference voltage; the fourth switch and the second capacitor are respectively connected in parallel between the inverting input terminal and the output terminal of the comparator; the input terminal of the ADC is connected to the output terminal of the comparator for sampling electrical signals; the data processing module is connected to the output terminal of the ADC for processing the sampled signals output by the ADC. In the circuit for improving touch measurement sensitivity of this invention, the closer the sampling values ​​of two consecutive samples from the ADC are, the closer the capacitance values ​​of the contact capacitor and the first capacitor are. Therefore, the first capacitor can be corrected based on the difference between two adjacent sample values. When the circuit contains multiple channels of contact capacitors, each channel has a different correction value, thereby improving the accuracy and sensitivity of the channels. Thus, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A circuit for improving touch measurement sensitivity, characterized in that, The circuit for improving touch measurement sensitivity includes at least: a first switch, a second switch, a third switch, a first capacitor, a second capacitor, a fourth switch, a comparator, an analog-to-digital converter, and a data processing module; The first end of the first switch is connected to an external contact capacitor, and the second end is connected to the upper plate of the first capacitor; the lower plate of the first capacitor is grounded. The first end of the second switch is connected to the first end of the first switch, and the second end is connected to the power supply. The first end of the third switch is connected to the second end of the first switch, and the second end is connected to the power supply. The inverting input terminal of the comparator is connected to the second terminal of the first switch, and the non-inverting input terminal is connected to the reference voltage. The fourth switch and the second capacitor are respectively connected in parallel between the inverting input terminal and the output terminal of the comparator; The input terminal of the analog-to-digital converter is connected to the output terminal of the comparator for sampling electrical signals; The data processing module is connected to the output terminal of the analog-to-digital converter and is used to process the sampled signal output by the analog-to-digital converter; The data processing module is further used to calculate the first absolute difference Δ1 between the first sampled value ΔV1 and the second sampled value ΔV2; The first sampled value ΔV1 is: the change in the input voltage of the analog-to-digital converter calculated by the data processing module after closing the second switch, opening the second switch and closing the first switch after a first preset time in the first sampling operation. The second sampled value ΔV2 is: during the second sampling operation, after closing the third switch and after a second preset time, opening the third switch and closing the first switch, the change in the input voltage of the analog-to-digital converter is calculated by the data processing module. The first absolute difference Δ1 satisfies: Wherein, C represents the capacitance of the contact capacitor, C1 represents the capacitance of the first capacitor, C2 represents the capacitance of the second capacitor, and VDD represents the voltage of the power supply.

2. The circuit for improving touch measurement sensitivity according to claim 1, characterized in that: The reference voltage is 0V or half of the power supply voltage.

3. The circuit for improving touch measurement sensitivity according to claim 1, characterized in that: The first switch, the second switch, the third switch, and the fourth switch are CMOS analog switches.

4. A system for improving touch measurement sensitivity, characterized in that, The system for improving touch measurement sensitivity includes: a touch capacitor and the circuit for improving touch measurement sensitivity as described in any one of claims 1-3; The lower plate of the contact capacitor is grounded, and the upper plate is connected to the first terminal of the first switch, which is used to convert the touch action signal into an electrical signal.

5. The system for improving touch measurement sensitivity according to claim 4, characterized in that: The contact capacitor is a parallel structure of multiple capacitors; wherein, the circuit for improving touch measurement sensitivity also includes a selector, and the multiple capacitors are respectively connected to the selection terminal of the selector inside the chip through pins, and the output terminal of the selector is connected to the first terminal of the first switch.

6. A method for improving touch measurement sensitivity, implemented based on the system for improving touch measurement sensitivity as described in claim 4 or 5, characterized in that, Includes the following steps: S1: First sampling operation: close the second switch, after a first preset time, open the second switch and close the first switch, and calculate the change value of the voltage at the input terminal of the analog-to-digital converter through the data processing module, as the first sampling value; The second sampling operation involves closing the third switch, then, after a second preset time, opening the third switch and closing the first switch. The data processing module calculates the change in voltage at the input terminal of the analog-to-digital converter, which is then used as the second sampling value. S2: Repeat step S1 n times to obtain 2n+2 sample values; where n is a natural number greater than or equal to 0; S3: The data processing module calculates the absolute difference between adjacent sampled values ​​and calculates the sum of 2n+1 absolute differences as the first change value; S4: Repeat steps S1-S3 to obtain the second change value; S5: Calculate the difference between the second change value and the first change value, and determine whether the difference is within a preset fluctuation range; if the difference is not within the preset fluctuation range, the data processing module sends a touch action signal to the next-level circuit; if the difference is within the preset range, the data processing module sends a no-action signal to the next-level circuit.

7. The method for improving touch measurement sensitivity according to claim 6, characterized in that: Before sampling, a reset step is also included: with the first switch, the second switch, and the third switch all open, the fourth switch is closed, and after a third preset time, the fourth switch is opened; wherein, the third preset time is greater than or equal to the reset time of the comparator.

8. The method for improving touch measurement sensitivity according to claim 6, characterized in that, The first sampled value satisfies formula (1): （1） in, C represents the first sampled value; C represents the capacitance of the contact capacitor; C1 represents the capacitance of the first capacitor; V CM This represents the voltage value at the non-inverting input of the comparator; V OS Vn represents the fixed offset voltage of the integrating circuit formed by the second capacitor and the comparator; VDD represents the power supply voltage; and C2 represents the capacitance value of the second capacitor.

9. The method for improving touch measurement sensitivity according to claim 6, characterized in that: The second sampled value satisfies formula (2): （2） in, This represents the second sampled value; C represents the capacitance of the contact capacitor; C1 represents the capacitance of the first capacitor; V CM This represents the voltage value at the non-inverting input of the comparator; V OS Vn represents the fixed offset voltage of the integrating circuit formed by the second capacitor and the comparator; VDD represents the power supply voltage; and C2 represents the capacitance value of the second capacitor.

10. The method for improving touch measurement sensitivity according to claim 6, characterized in that: When there is no touch, the first capacitor is corrected according to the capacitance value of the touch capacitor so that the first sampled value is equal to the second sampled value.

11. The method for improving touch measurement sensitivity according to claim 6, characterized in that: When the contact capacitor is a parallel structure of multiple capacitors, each capacitor is connected to the selection terminal of the selector in the circuit that improves the sensitivity of touch measurement through a pin; each capacitor and the subsequent circuit form a sampling channel, and the average value of multiple sampling values ​​of multiple sampling channels is used as a virtual reference channel.

12. The method for improving touch measurement sensitivity according to any one of claims 6-11, characterized in that: Replace step S2 with: If the first sampled value is closer to the midpoint of the range of the analog-to-digital converter than the second sampled value is closer to the midpoint of the range of the analog-to-digital converter, then the first sampling method is selected as the subsequent sampling method; If the second sampled value is closer to the midpoint of the analog-to-digital converter's range than the first sampled value is closer to the midpoint of the analog-to-digital converter's range, then the second sampling method is selected as the subsequent sampling method.

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