Capacitance detection circuit and detection equipment

Abstract

The invention discloses a capacitance detection circuit and detection equipment. The capacitance detection circuit comprises a state conversion module, an integrated conversion module and a detection module. The state conversion module is connected between the first power supply end and the to-be-tested capacitor, and the state conversion module controls the first power supply end to charge the to-be-tested capacitor; the state conversion module is connected between the to-be-tested capacitor and the integrated conversion module, and the state conversion module controls the to-be-tested capacitor to be connected with the integrated conversion module; the state conversion module is connected between the second power supply end and the integrated conversion module; the state conversion module is also used for controlling the second power supply end to supply power to the integrated conversion module; the integrated conversion module accesses a first voltage signal and is used for converting the first voltage signal into a first digital signal; and the detection module is connected with the integrated conversion module and is used for monitoring the capacitance change of the to-be-detected capacitor according to the first digital signal. The capacitance detection circuit provided by the invention can shorten the measurement time and save the application cost.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit design, and in particular to a capacitance detection circuit and detection equipment. Background Art

[0002] In recent years, with the rapid development of automotive electronics, buttons with different functions have been integrated into vehicles. Traditional mechanical buttons are easily damaged after long-term use due to the characteristics of their physical structure, and their appearance cannot meet the needs of today's young people. For the above reasons, more and more automobile manufacturers use capacitive touch buttons to replace traditional mechanical buttons.

[0003] The traditional capacitance detection circuit includes a sampling capacitor, a comparator, a counter, and a switching element. The capacitor to be measured charges the sampling capacitor multiple times until the comparator output changes. The counter counts the number of charges to detect the capacitance change of the capacitor to be measured, and the count value is used to reflect the capacitor to be measured, which increases the measurement time. Summary of the invention

[0004] The invention provides a capacitance detection circuit and a detection device to solve the problem of long measurement time in the prior art.

[0005] According to one aspect of the present invention, there is provided a capacitance detection circuit, characterized in that it comprises a state conversion module, an integrated conversion module and a detection module;

[0006] The state conversion module is connected between the first power supply terminal and the capacitor to be measured, and the state conversion module is used to control the first power supply terminal to charge the capacitor to be measured;

[0007] The state conversion module is connected between the capacitor to be measured and the integrated conversion module, and the state conversion module is also used to control the capacitor to be measured to be connected to the integrated conversion module;

[0008] The state conversion module is connected between the second power supply terminal and the integrated conversion module, and the state conversion module is also used to control the second power supply terminal to supply power to the integrated conversion module;

[0009] The integrated conversion module is connected to a first voltage signal, and the integrated conversion module is used to convert the first voltage signal into a first digital signal;

[0010] The detection module is connected to the integrated conversion module, and the detection module is used to monitor the capacitance change of the capacitor to be measured according to the first digital signal.

[0011] Optionally, the integrated conversion module includes a successive approximation analog-to-digital converter, the input end of the successive approximation analog-to-digital converter is connected to the input end of the integrated conversion module, the output end of the successive approximation analog-to-digital converter is connected to the output end of the integrated conversion module, and the successive approximation analog-to-digital converter is used to sample and convert the first voltage signal to obtain the first digital signal.

[0012] Optionally, the state conversion module includes a first switching unit, a second switching unit and a third switching unit, the first end of the first switching unit is connected to the first power supply end, the second end of the first switching unit is connected to the first end of the capacitor to be measured, the second end of the capacitor to be measured is grounded, the first switching unit is used to control the first power supply end to charge the capacitor to be measured, the first end of the second switching unit is connected to the first end of the capacitor to be measured, the second end of the second switching unit is connected to the input end of the integrated conversion module, the second switching unit is used to control the capacitor to be measured to be connected to the integrated conversion module, the first end of the third switching unit is connected to the second power supply end, the second end of the third switching unit is connected to the integrated conversion module, and the third switching unit is used to control the second power supply end to power the integrated conversion module.

[0013] Optionally, the first switching unit includes a first switch, a first end of the first switch is connected to a first end of the first switching unit, and a second end of the first switch is connected to a second end of the first switching unit.

[0014] Optionally, the second switching unit includes a second switch, a first end of the second switch is connected to the first end of the second switching unit, and a second end of the second switch is connected to the second end of the second switching unit.

[0015] Optionally, the third switching unit includes a third switch, a first end of the third switch is connected to the first end of the third switching unit, and a second end of the third switch is connected to the second end of the third switching unit.

[0016] Optionally, the successive approximation analog-to-digital converter includes a capacitor array, a comparator, a successive approximation register and a digital-to-analog converter, the first end of the capacitor array inputs a first reference voltage, the second end of the capacitor array is grounded, the third end of the capacitor array is connected to the input end of the successive approximation analog-to-digital converter, the output end of the capacitor array is connected to the first input end of the comparator, the second input end of the comparator inputs a second reference voltage, the output end of the comparator is connected to the input end of the successive approximation register, the output end of the successive approximation register is connected to the output end of the successive approximation analog-to-digital converter and the input end of the digital-to-analog converter, and the output end of the digital-to-analog converter is connected to the control end of the capacitor array.

[0017] Optionally, the capacitor array includes a number of capacitors and a fourth switch corresponding to the number of bits of the successive approximation analog-to-digital converter, the fixed end of the fourth switch is connected to the first end of the corresponding capacitor, the second end of the capacitor is connected to the output end of the capacitor array, the first end of the fourth switch is connected to the first end of the capacitor array, the second end of the fourth switch is connected to the second end of the capacitor array, and the third end of the fourth switch is connected to the third end of the capacitor array.

[0018] Optionally, the first reference voltage is equal to the voltage of the first power supply terminal, and the second reference voltage is equal to the voltage of the second power supply terminal.

[0019] According to another aspect of the present invention, a detection device is provided, comprising the capacitance detection circuit.

[0020] The technical solution of the embodiment of the present invention provides a capacitance detection circuit, including a state conversion module, an integrated conversion module and a detection module; the state conversion module is connected between a first power supply terminal and a capacitor to be measured, and the state conversion module is used to control the first power supply terminal to charge the capacitor to be measured; the state conversion module is connected between the capacitor to be measured and the integrated conversion module, and the state conversion module is also used to control the capacitor to be measured to be connected to the integrated conversion module. By adopting the integrated conversion module, the first voltage signal is converted into a first digital signal, and the detection module monitors the capacitance change of the capacitor to be measured according to the first digital signal, thereby shortening the measurement time. In addition, the integrated conversion module is used to replace the sampling capacitor and the comparator in the traditional capacitance detection circuit, saving the application cost and solving the problem of long measurement time in the prior art.

[0021] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 It is a capacitance detection circuit provided in the related art;

[0024] Figure 2 is a structural schematic diagram of a capacitance detection circuit provided by an embodiment of the present invention;

[0025] Figure 3is a circuit diagram of a capacitance detection circuit provided by an embodiment of the present invention;

[0026] Figure 4 It is a structural schematic diagram of a detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] In recent years, with the rapid development of automotive electronics, buttons with different functions have been integrated into vehicles. Due to the characteristics of their physical structure, traditional mechanical buttons are easily damaged during long-term use, and their appearance cannot meet the needs of today's young people. For the above reasons, more and more automobile manufacturers are using capacitive touch buttons to replace traditional mechanical buttons. The principle of capacitive touch buttons is to use a capacitive detection circuit to identify the touch action of a finger. Therefore, the sensitivity of the detection determines whether the button action can be accurately identified. Figure 1 It is a capacitance detection circuit provided in the related art, such as Figure 1As shown, CX is the touch button equivalent capacitor. One end of the touch button equivalent capacitor CX is connected to GND, and the other end is connected to one end of the switch S01. The other end of the switch S01 is connected to the power supply VDD. One end of the switch S02 is connected to the switch S01 and the touch button equivalent capacitor CX, and the other end of the switch S02 is connected to the sampling capacitor CS. The other end of the sampling capacitor CS is connected to GND. Switch S03 is connected in parallel with the sampling capacitor CS. One end of the switch S03 is connected to the sampling capacitor CS, switch S02 and the positive end of the comparator COMP, and the other end is connected to GND. The negative end of the comparator is connected to the reference voltage Vref, and the output is COMP_OUT. The working timing of the circuit is as follows Figure 2 As shown, the working process is as follows:

[0030] Step 1: S01 is disconnected, S02 and S03 are closed, and the charges on CX and CS are released to GND through S03, V CX =V CS =0V, Vref is 0.5*VDD, and the comparator output is 0.

[0031] Step 2: S03, S02 is disconnected, S01 is closed, VDD charges CX, making V CX = VDD, since S02, S03 are disconnected, V CS Still 0V.

[0032] Step 3: S01 is disconnected, S02 is closed, S03 remains disconnected, and the charge is transferred between CX and CS. CX =V CS =(CX / (CX+CS))*VDD.

[0033] Repeat steps 1 and 2, and finally V CS =(1-(CS / (CX+CS)) N )*VDD, N is the number of repetitions, when V CS If it is greater than Vref, the comparator outputs 1. At this time, the counter obtains the value of N, which reflects the size of CX. When a touch action occurs, N will change, and the touch action can be identified based on the change of N. CX is the voltage across CX, V CS is the voltage across CS.

[0034] This structure measures capacitance by charge transfer and comparison, but the measurement accuracy of this structure depends entirely on the size of CS and CX. When CS = 10nF, CX = 10pF, Vref = 0.5VDD, and the comparator outputs 1, N = 694. Assuming that touch causes CX to increase by 1pF, when touch occurs, N = 630. Delta N before and after touch = 694-630 = 64. This value is an ideal case. In actual use, due to the size of the button and the thickness of the cover, delta N will be smaller, resulting in a decrease in detection sensitivity, which affects the sensitivity of the button. In addition, since CS is relatively large, generally at the nF level, it needs to be integrated off-chip, which will cause it to occupy IO resources and increase application costs. In addition, this method reflects the size of CX through counting values, which greatly increases the measurement time and poses a great challenge to fast-response application scenarios.

[0035] In order to solve the above problems, an embodiment of the present invention provides a capacitance detection circuit. Figure 2 is a schematic diagram of a capacitance detection circuit provided by an embodiment of the present invention, such as Figure 2 As shown, the capacitance detection circuit 100 includes a state conversion module 110, an integrated conversion module 120 and a detection module 130; the state conversion module 110 is connected between the first power supply terminal V1 and the capacitor to be measured Cs, and the state conversion module 110 is used to control the first power supply terminal V1 to charge the capacitor to be measured Cs; the state conversion module 110 is connected between the capacitor to be measured Cs and the integrated conversion module 120, and the state conversion module 110 is also used to control the capacitor to be measured Cs to be connected to the integrated conversion module 120; the state conversion module 110 is connected between the second power supply terminal V2 and the integrated conversion module 120, and the state conversion module 110 is also used to control the second power supply terminal V2 to supply power to the integrated conversion module 120; the integrated conversion module 120 is connected to the first voltage signal Vin, and the integrated conversion module 120 is used to convert the first voltage signal Vin into a first digital signal Dout; the detection module 130 is connected to the integrated conversion module 120, and the detection module 130 is used to monitor the capacitance change of the capacitor to be measured Cs according to the first digital signal Dout.

[0036] In this embodiment, the capacitance detection circuit 100 is a circuit for identifying touch signals by detecting changes in capacitance values, and the state conversion module 110 is a module for controlling the working state of the capacitance detection circuit. For example, the state conversion module 110 includes a switch element, and the integrated conversion module 120 is a module for converting and processing input analog signals and outputting digital signals. The integrated conversion module 120 integrates multiple internal components to improve circuit stability and reduce application costs. The detection module 130 is a module for detecting the digital signal output by the integrated conversion module 120, for example, the detection module 130 includes a controller, etc.

[0037] In this embodiment, in the first state, the state conversion module 110 controls the first power supply terminal V1 to charge the capacitor Cs to be measured, the capacitor Cs to be measured is disconnected from the integrated conversion module 120, and the second power supply terminal V2 supplies power to the integrated conversion module 120. In the second state, the state conversion module 110 controls the first power supply terminal V1 to be disconnected from the capacitor Cs to be measured, the capacitor Cs to be measured is connected to the integrated conversion module 120, and the second power supply terminal V2 supplies power to the integrated conversion module 120. According to the conservation of charge in the first state and the second state, the voltage value (i.e., the first voltage signal Vin) at the input end of the integrated conversion module 120 can be obtained. The integrated conversion module 120 processes the input first voltage signal Vin and outputs a first digital signal Dout corresponding to the first voltage signal Vin. Since the first voltage signal Vin is related to the capacitor Cs to be measured, the detection module 130 can detect the capacitance change of the capacitor Cs to be measured according to the first digital signal Dout, thereby identifying the touch signal.

[0038] The technical solution of this embodiment provides a capacitance detection circuit, including a state conversion module, an integrated conversion module and a detection module; the state conversion module is connected between a first power supply terminal and a capacitor to be measured, and the state conversion module is used to control the first power supply terminal to charge the capacitor to be measured; the state conversion module is connected between the capacitor to be measured and the integrated conversion module, and the state conversion module is also used to control the capacitor to be measured to be connected to the integrated conversion module. By adopting the integrated conversion module, the first voltage signal is converted into a first digital signal, and the detection module monitors the capacitance change of the capacitor to be measured according to the first digital signal, thereby shortening the measurement time. In addition, the integrated conversion module is used to replace the sampling capacitor and the comparator in the traditional capacitance detection circuit, saving the application cost and solving the problems of high cost and long measurement time in the prior art.

[0039] Figure 3 is a circuit diagram of a capacitance detection circuit provided by an embodiment of the present invention, such as Figure 3 As shown, the integrated conversion module 120 includes a successive approximation analog-to-digital converter, the input end of the successive approximation analog-to-digital converter is connected to the input end of the integrated conversion module, the output end of the successive approximation analog-to-digital converter is connected to the output end of the integrated conversion module, and the successive approximation analog-to-digital converter is used to sample and convert the first voltage signal Vin to obtain a first digital signal Dout.

[0040] In this embodiment, the successive approximation analog-to-digital converter is a device that converts an analog signal into a digital signal by a successive approximation method. Its working principle is to gradually reduce the numerical range of the input signal (i.e., the first voltage signal Vin) by binary division to determine the digital representation of the signal (i.e., the first digital signal Dout). The resolution of the successive approximation analog-to-digital converter is generally 8-16 bits, and it has the characteristics of low power consumption and small size.

[0041] Referring to the above embodiment, the state conversion module 110 includes a first switching unit, a second switching unit, and a third switching unit. The first end of the first switching unit is connected to the first power supply terminal V1, the second end of the first switching unit is connected to the first end of the capacitor Cs to be measured, and the second end of the capacitor Cs to be measured is grounded. The first switching unit is used to control the first power supply terminal V1 to charge the capacitor Cs to be measured, the first end of the second switching unit is connected to the first end of the capacitor Cs to be measured, the second end of the second switching unit is connected to the input end of the integrated conversion module 120, and the second switching unit is used to control the capacitor Cs to be measured to be connected to the integrated conversion module 120. The first end of the third switching unit is connected to the second power supply terminal V2, the second end of the third switching unit is connected to the integrated conversion module 120, and the third switching unit is used to control the second power supply terminal V2 to supply power to the integrated conversion module 120.

[0042] On the basis of the above embodiment, in the first state, the first switching unit is turned on, the first power supply terminal V1 charges the capacitor Cs to be measured, the second switching unit is turned off, that is, the capacitor Cs to be measured is disconnected from the integrated conversion module 120, the third switching unit is turned on, and the second power supply terminal V2 supplies power to the integrated conversion module 120. In the second state, the first switching unit is turned off, that is, the first power supply terminal V1 is disconnected from the capacitor Cs to be measured, the second switching unit is turned on, the capacitor Cs to be measured is connected to the integrated conversion module 120, the third switching unit is turned on, and the second power supply terminal V2 supplies power to the integrated conversion module 120.

[0043] Specifically, the first switching unit includes a first switch S1, a first end of the first switch S1 is connected to a first end of the first switching unit, and a second end of the first switch S1 is connected to a second end of the first switching unit. The second switching unit includes a second switch S2, a first end of the second switch S2 is connected to a first end of the second switching unit, and a second end of the second switch S2 is connected to a second end of the second switching unit. The third switching unit includes a third switch S3, a first end of the third switch S3 is connected to a first end of the third switching unit, and a second end of the third switch S3 is connected to a second end of the third switching unit.

[0044] With reference to the above embodiment, in the first state, the first switching unit is turned on, the first switch S1 is closed, the first power supply terminal V1 charges the capacitor Cs to be measured, the second switching unit is turned off, the second switch S2 is turned off, that is, the capacitor Cs to be measured is disconnected from the integrated conversion module 120, the third switching unit is turned on, the third switch S3 is closed, and the second power supply terminal V2 supplies power to the integrated conversion module 120. In the second state, the first switching unit is turned off, the first switch S1 is turned off, that is, the first power supply terminal V1 is disconnected from the capacitor Cs to be measured, the second switching unit is turned on, the second switch S2 is turned on, the capacitor Cs to be measured is connected to the integrated conversion module 120, the third switching unit is turned on, the third switch S3 is turned on, and the second power supply terminal V2 supplies power to the integrated conversion module 120.

[0045] Continue to refer Figure 3 The successive approximation analog-to-digital converter includes a capacitor array Cn, a comparator U1, a successive approximation register U2 and a digital-to-analog converter U3. The first end of the capacitor array Cn inputs a first reference voltage Vref1, the second end of the capacitor array Cn is grounded, the third end of the capacitor array Cn is connected to the input end of the successive approximation analog-to-digital converter, the output end of the capacitor array Cn is connected to the first input end of the comparator U1, the second input end of the comparator U1 inputs a second reference voltage Vref2, the output end of the comparator U1 is connected to the input end of the successive approximation register U2, the output end of the successive approximation register U2 is connected to the output end of the successive approximation analog-to-digital converter and the input end of the digital-to-analog converter U3, and the output end of the digital-to-analog converter U3 is connected to the control end of the capacitor array Cn. The first reference voltage Vref1 is equal to the voltage of the first power supply terminal V1, the second reference voltage Vref2 is equal to the voltage of the second power supply terminal V2, and the voltage of the second power supply terminal V2 is equal to 0.5V1.

[0046] Specifically, the capacitor array Cn includes a number of capacitors and a fourth switch corresponding to the number of bits of the successive approximation analog-to-digital converter, the fixed end of the fourth switch is connected to the first end of the corresponding capacitor, the second end of the capacitor is connected to the output end of the capacitor array, the first end of the fourth switch is connected to the first end of the capacitor array, the second end of the fourth switch is connected to the second end of the capacitor array, and the third end of the fourth switch is connected to the third end of the capacitor array.

[0047] In this embodiment, the weight w of the capacitors in the capacitor array Cn is N =2 N , N is the number of bits of the successive approximation analog-to-digital converter, and the capacitor array Cn includes capacitors C, C, 2C…capacitor 2 N-1 C, and fourth switches S40, S41, S42, S43, S44, S45 connected one by one to the capacitors. N The operation process of the successive approximation analog-to-digital converter is divided into two stages: sampling and conversion. During sampling, the lower plates of the capacitors in the capacitor array are all connected to the input end of the successive approximation analog-to-digital converter through the corresponding fourth switch, and the upper plates of the capacitors are connected to the second power supply terminal V2 through the third switch S3. During conversion, the upper plates of the capacitors in the capacitor array are disconnected from the second power supply terminal V2, and the capacitors 2 N-1 The lower plate of the capacitor C is connected to the first reference voltage Vref1, and the lower plates of the other capacitors are grounded. At this time, the comparator U1 compares the first input terminal with the second reference voltage Vref2. If the voltage value of the first input terminal is greater than the second reference voltage Vref2, the comparator U1 outputs a logic 0 and stores it in the successive approximation register U2. The digital-to-analog converter U3 controls the potential of the lower plate of the capacitor array according to the digital signal in the successive approximation register, for example, the control capacitor 2 N-1 C and capacitor 2 N-2The lower plate of C is connected to the first reference voltage Vref1, and the lower plates of the other capacitors are grounded... until the approximation is completed. At this time, the accumulated output result of the comparator U1 is stored in the successive approximation register U2, which is the digital signal corresponding to the input voltage (first voltage signal Vin).

[0048] Exemplarily, the successive approximation analog-to-digital converter is 12 bits, that is, N=12. The working process includes two stages: sampling and conversion. In the sampling stage: in the first state, the first switch S1 and the third switch S3 are closed, the second switch S2 is open, and the capacitor 2 N-1 The lower plate of C is connected to Vref1, and the lower plates of the other capacitors are connected to GND. At this time, the charge on the capacitor Cs to be measured is Q1 = V1*Cs, and the charge on the capacitor array is Q2 = (V1-0.5V1)*2 N-1 C+(0-0.5V1)*(C+C+2C+…+2 N-2 C)=0.

[0049] In the second state, the first switch S1 is open, the second switch S2 is closed, the third switch S3 is closed, and the lower plate of the capacitor in the capacitor array is connected to Vin. At this time, the charge on the capacitor Cs to be measured Q3 = Vin*Cs, and the charge on the capacitor array Q4 = (Vin-0.5V1)*2 N C. According to the charge conservation of the first state and the second state, Q1+Q2=Q3+Q4, at this time Vin=((Cs+0.5*2 N C) / (Cs+2 N C))*V1.

[0050] Conversion stage: the first switch S1, the second switch S2 and the third switch S3 are disconnected, and the capacitor 2 in the capacitor array is N-1 The lower plate of C is connected to Vref1, and the lower plates of the other capacitors are connected to GND. At this time, the comparator outputs the comparison result, and the successive approximation register and the digital-to-analog converter begin to perform successive approximation, and finally output the first digital signal Dout corresponding to the first voltage signal Vin. When a touch action occurs, the capacitance value of the capacitor Cs to be measured will change, causing the value of the first voltage signal Vin to change, and the first digital signal Dout can reflect the generation of the touch. Compared with the traditional structure using a counting method, this circuit structure uses a successive approximation analog-to-digital converter to convert the capacitance value into a digital signal, which can more conveniently perform digital filtering processing, improve the signal-to-noise ratio, thereby improving the robustness of the button and greatly improving the user experience. In addition, the circuit in this embodiment only needs one conversion to obtain the capacitance value, which greatly improves the detection speed compared to the traditional result. Furthermore, the circuit structure in this embodiment does not require external devices to cooperate, reducing the application cost.

[0051] The embodiment of the present invention further provides a detection device, Figure 4 is a schematic diagram of the structure of a detection device provided by an embodiment of the present invention, such as Figure 4 As shown, the detection device 10 includes a capacitance detection circuit 100 .

[0052] In this embodiment, the capacitance detection circuit 100 uses a successive approximation analog-to-digital converter for analog-to-digital conversion, which improves the detection sensitivity while reducing the application cost. The successive approximation analog-to-digital converter, as a universal module, can be integrated in a chip without increasing any peripheral cost and application cost. Therefore, the capacitance detection circuit is set in the detection device, so that the detection device has the advantages of short measurement time and low application cost.

[0053] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0054] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A capacitance detection circuit, characterized in that: It includes a state conversion module, an integrated conversion module and a detection module; The state conversion module is connected between the first power supply terminal and the capacitor to be measured, and the state conversion module is used to control the first power supply terminal to charge the capacitor to be measured; The state conversion module is connected between the capacitor to be measured and the integrated conversion module, and the state conversion module is also used to control the capacitor to be measured to be connected to the integrated conversion module; The state conversion module is connected between the second power supply terminal and the integrated conversion module, and the state conversion module is also used to control the second power supply terminal to supply power to the integrated conversion module; The integrated conversion module is connected to a first voltage signal, and the integrated conversion module is used to convert the first voltage signal into a first digital signal; The detection module is connected to the integrated conversion module, and the detection module is used to monitor the capacitance change of the capacitor to be measured according to the first digital signal.

2. The capacitance detection circuit according to claim 1, characterized in that: The integrated conversion module includes a successive approximation analog-to-digital converter, the input end of the successive approximation analog-to-digital converter is connected to the input end of the integrated conversion module, the output end of the successive approximation analog-to-digital converter is connected to the output end of the integrated conversion module, and the successive approximation analog-to-digital converter is used to sample and convert the first voltage signal to obtain the first digital signal.

3. The capacitance detection circuit according to claim 1, characterized in that: The state conversion module includes a first switching unit, a second switching unit and a third switching unit. The first end of the first switching unit is connected to the first power supply end, the second end of the first switching unit is connected to the first end of the capacitor to be measured, and the second end of the capacitor to be measured is grounded. The first switching unit is used to control the first power supply end to charge the capacitor to be measured. The first end of the second switching unit is connected to the first end of the capacitor to be measured, and the second end of the second switching unit is connected to the input end of the integrated conversion module. The second switching unit is used to control the capacitor to be measured to be connected to the integrated conversion module. The first end of the third switching unit is connected to the second power supply end, and the second end of the third switching unit is connected to the integrated conversion module. The third switching unit is used to control the second power supply end to power the integrated conversion module.

4. The capacitance detection circuit according to claim 3, characterized in that: The first switching unit includes a first switch, a first end of the first switch is connected to a first end of the first switching unit, and a second end of the first switch is connected to a second end of the first switching unit.

5. The capacitance detection circuit according to claim 3, characterized in that: The second switching unit includes a second switch, a first end of the second switch is connected to a first end of the second switching unit, and a second end of the second switch is connected to a second end of the second switching unit.

6. The capacitance detection circuit according to claim 3, characterized in that: The third switching unit includes a third switch, a first end of the third switch is connected to the first end of the third switching unit, and a second end of the third switch is connected to the second end of the third switching unit.

7. The capacitance detection circuit according to claim 2, characterized in that: The successive approximation analog-to-digital converter includes a capacitor array, a comparator, a successive approximation register and a digital-to-analog converter. The first end of the capacitor array inputs a first reference voltage, the second end of the capacitor array is grounded, the third end of the capacitor array is connected to the input end of the successive approximation analog-to-digital converter, the output end of the capacitor array is connected to the first input end of the comparator, the second input end of the comparator inputs a second reference voltage, the output end of the comparator is connected to the input end of the successive approximation register, the output end of the successive approximation register is connected to the output end of the successive approximation analog-to-digital converter and the input end of the digital-to-analog converter, and the output end of the digital-to-analog converter is connected to the control end of the capacitor array.

8. The capacitance detection circuit according to claim 7, characterized in that: The capacitor array includes capacitors and a fourth switch having a number corresponding to the number of bits of the successive approximation analog-to-digital converter, wherein a fixed end of the fourth switch is connected to a first end of the corresponding capacitor, a second end of the capacitor is connected to an output end of the capacitor array, a first end of the fourth switch is connected to a first end of the capacitor array, a second end of the fourth switch is connected to a second end of the capacitor array, and a third end of the fourth switch is connected to a third end of the capacitor array.

9. The capacitance detection circuit according to claim 7, characterized in that: The first reference voltage is equal to the voltage of the first power supply terminal, and the second reference voltage is equal to the voltage of the second power supply terminal.

10. A detection device, characterized in that: The invention comprises a capacitance detection circuit as described in any one of claims 1 to 9.

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