Capacitive touch detection circuit

Abstract

The invention discloses a capacitive touch detection circuit. The capacitive touch detection circuit comprises a detection circuit and a reference circuit, the detection circuit is electrically connected with the reference circuit through the processor control circuit; the detection circuit comprises a first interface electrically connected with the capacitive sensing electrode, a first capacitive oscillation circuit and a first counter, and the capacitive sensing electrode is electrically connected with the processor control circuit through the first capacitive oscillation circuit and the first counter in sequence. According to the main technical scheme and effects, two capacitance oscillation circuits are designed, the structures and parameters of the two capacitance oscillation circuits are completely consistent, when the oscillation frequency of the capacitance oscillators changes due to power supply interference or other environment interference, the changes of the two capacitance oscillators are synchronous, so that the count value of the first counter is kept stable, and the count value of the second counter is kept stable. Therefore, errors caused by inconsistent capacitance oscillation frequencies are avoided, and the anti-interference capability of the system is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to a capacitive touch detection circuit. Background Art

[0002] Capacitive touch buttons are widely used in home appliances, fitness equipment, smart homes, industrial control and other fields.

[0003] At present, when performing capacitive touch detection, the interference problem of the capacitor oscillation circuit is a common and critical challenge in the design of electronic equipment, especially in systems that require high precision and stability, such as capacitive touch sensors. Interference usually comes from power supply noise, electromagnetic interference (EMI), temperature changes, etc., all of which may affect the performance of the circuit. In the capacitor oscillation circuit, interference mainly disturbs the stability and accuracy of the system by affecting the oscillation frequency. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to solve the interference problem generated during touch detection in the prior art, and to provide a capacitive touch detection circuit to achieve effective anti-interference capability.

[0005] Technical solution:

[0006] The present application proposes a capacitive touch detection circuit, including a detection circuit and a reference circuit;

[0007] The detection circuit is electrically connected to the reference circuit via a processor control circuit;

[0008] The detection circuit includes a first interface electrically connected to the capacitive sensing electrode, a first capacitive oscillation circuit and a first counter, and the capacitive sensing electrode is electrically connected to the processor control circuit in sequence through the first capacitive oscillation circuit, the first counter and the processor control circuit;

[0009] The reference circuit includes a second interface electrically connected to the reference capacitor, a second capacitor oscillation circuit and a second counter, and the reference capacitor is electrically connected to the processor control circuit in sequence through the second capacitor oscillation circuit, the second counter and the processor control circuit;

[0010] The first capacitor oscillation circuit and the second capacitor oscillation circuit have the same structure and parameters.

[0011] Preferably, the first capacitor oscillation circuit includes a power supply, a first current source, a second current source and a logic control circuit, the power supply is grounded through the first switch, the first current source, the second switch and the second current source in sequence, the logic control circuit is electrically connected to the control ends of the first switch and the second switch, the output ends of the first reference voltage comparator and the second reference voltage comparator, and the input end of the first counter, respectively, and the first comparator and the second comparator are electrically connected to the capacitor sensing electrode, respectively.

[0012] Preferably, the reference capacitor is a clock capacitor, and the second capacitor oscillation circuit is grounded through the clock capacitor.

[0013] Preferably, the reference capacitor is configured as a sensing ring that can surround the capacitive sensing electrode.

[0014] Preferably, the first counter, the second counter, the capacitive sensing electrode and the reference capacitor have the following relationship when in use:

[0015] C1×T cyc =C pad ×Cnt samp ;

[0016] Where C1 is the capacitance value of the reference capacitor, T cyc is the predetermined count number of the second counter, C pad is the capacitance value of the capacitive sensing electrode, Cnt samp is the count value of the first counter.

[0017] Preferably, when the capacitance value of the capacitive sensing electrode changes, the processor control circuit can obtain the touch status of the capacitive sensing electrode through the change of the count value of the first counter.

[0018] Preferably, the voltage waveform of the end of the first capacitor oscillation circuit connected to the capacitor sensing electrode is a triangular wave, and the voltage waveform of the end of the first capacitor oscillation circuit connected to the first counter is a square wave.

[0019] Preferably, the time formula for charging and discharging the capacitive sensing electrode each time is:

[0020] t=2*C*(V H -V L ) / I;

[0021] Where I is the charge and discharge current source, C is the capacitance detected by the capacitive sensing electrode, and V H The reference voltage set for the first comparator, V L a reference voltage set for the second comparator;

[0022] In a certain period T, the counting formula of the first counter is:

[0023] N=T / t=T*I / (2*C*(V H -V L ));

[0024] Where t is the capacitance C from V L Charge to V H , and then discharge back to V L single cycle time.

[0025] Preferably, the first capacitor oscillation circuit is configured as follows:

[0026] The first switch is turned on, the second switch is turned off, the first current source charges the capacitor sensing electrode, when the capacitor sensing electrode voltage reaches the reference voltage of the first reference voltage comparator, the first switch is turned off, the second switch is turned on, the second current source discharges the capacitor sensing electrode, when the capacitor sensing electrode voltage reaches the reference voltage of the second reference voltage comparator, the first switch is turned on, the second switch is turned off, and the above charging and discharging process is repeated.

[0027] Beneficial effects:

[0028] By designing two capacitor oscillation circuits (one for detecting capacitance and the other as a reference clock), and the structures and parameters of the two capacitor oscillation circuits are completely consistent, when the oscillation frequency of the capacitor oscillator changes due to power supply interference or other environmental interference, the changes of the two capacitor oscillators are synchronized, so that the count value of the first counter remains stable, which avoids the error caused by the inconsistency of the capacitor oscillation frequency and significantly improves the anti-interference ability of the system. By using two capacitor oscillation circuits with the same structure, the complexity caused by the difference in component parameters is eliminated, the cost of debugging and calibration is reduced, and higher reliability and lower cost are achieved through the same circuit structure, which has obvious cost advantages in product manufacturing;

[0029] Traditional anti-interference methods usually reduce power supply interference by adding a linear voltage regulator circuit (LDO), but this not only increases circuit complexity and cost, but also has limited effect. This invention eliminates interference through a synchronous oscillation circuit, avoiding the need for additional circuits, thereby reducing costs and improving circuit stability.

[0030] By adding a sensing ring to the outer circle of the sensing electrode, the problem of false detection caused by water droplets covering the sensing electrode is solved. When the water covers a large area, the capacitance of the sensing electrode will change. However, due to the combined effect of the sensing ring and the electrode, the effect of water on the capacitance value is effectively offset. In this way, the system can avoid misjudging the effect of water as a finger touch action, thereby improving the accuracy of touch detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a circuit structure block diagram of the present invention;

[0032] Figure 2 It is a schematic diagram of the circuit structure of the first capacitor oscillation circuit of the present invention;

[0033] Figure 3 This is a waveform diagram of the first capacitor oscillation circuit of the present invention;

[0034] Figure 4 It is a schematic structural diagram of an embodiment of the present invention when the waterproof effect is achieved.

[0035] Reference numerals:

[0036] 1. Detection circuit; 101. Capacitive sensing electrode; 102. First capacitor oscillation circuit; 103. First counter; 2. Reference circuit; 201. Reference capacitor; 202. Second capacitor oscillation circuit; 203. Second counter; 3. Processor control circuit. DETAILED DESCRIPTION

[0037] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the specific embodiments of the accompanying drawings.

[0038] Example 1

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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 are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0040] In view of the problems existing in the existing technology, such as Figure 1-4 As shown, a capacitive touch detection circuit includes a detection circuit 1 and a reference circuit 2;

[0041] The detection circuit 1 is electrically connected to the reference circuit 2 via the processor control circuit 3;

[0042] The detection circuit 1 includes a first interface 101 electrically connected to the capacitive sensing electrode, a first capacitive oscillation circuit 102 and a first counter 103, and the capacitive sensing electrode 101 is electrically connected to the processor control circuit 3 through the first capacitive oscillation circuit 102, the first counter 103 and the processor control circuit 3 in sequence;

[0043] The reference circuit includes a second interface electrically connected to the reference capacitor, a second capacitor oscillation circuit 202 and a second counter 203, and the reference capacitor 201 is electrically connected to the processor control circuit 3 through the second capacitor oscillation circuit 202, the second counter 203 and the processor control circuit 3 in sequence;

[0044] The first capacitor oscillating circuit 102 and the second capacitor oscillating circuit 202 have the same structure and parameters.

[0045] Specifically, when a human body or other object approaches the capacitive sensing electrode 101, the capacitance value (C pad ) will change, and the change in capacitance will affect the oscillation frequency of the first capacitor oscillation circuit 102;

[0046] The oscillation signal generated by the first capacitor oscillation circuit 102 is counted by the first counter 103 to obtain a count value Cnt. samp , this count value is proportional to the capacitance change of the capacitive sensing electrode 101;

[0047] The function of the reference circuit 2 is to provide a stable reference signal. In the reference circuit 2, the capacitance of the reference capacitor 201 remains fixed, and the oscillation signal generated by the second capacitor oscillation circuit 202 is counted by the second counter 203;

[0048] Since the structures and parameters of the first capacitor oscillation circuit 102 and the second capacitor oscillation circuit 202 are completely the same, when the external environment (such as temperature, power supply, etc.) changes, the frequency changes of the two circuits are synchronous, so the count values ​​of the two counters will also change synchronously, which makes the circuit have a good anti-interference ability, that is, when interference occurs in the external environment, the responses of the detection circuit and the reference circuit are similar, thereby being able to eliminate the influence of the interference;

[0049] The processor control circuit 3 calculates the capacitance values ​​of the detection electrode and the reference circuit respectively according to the count values ​​of the first counter 103 and the second counter 203. Through the first counter, the processor can determine whether a touch or human body approaching event occurs;

[0050] If the difference between the capacitance value of the capacitive sensing electrode 101 and the reference capacitance 201 is detected to exceed a predetermined threshold, the processor will output a touch signal, indicating that there is a touch or proximity action;

[0051] By comparing with the reference circuit 2, the capacitance change of the capacitance sensing electrode 101 can be accurately detected, thereby accurately determining the touch or proximity action;

[0052] Enhanced anti-interference capability: since the capacitive sensing electrode 101 and the reference capacitor 201 have the same structure and parameters, the responses of the two circuits under interference are consistent, thereby effectively eliminating the influence of external interference on touch detection;

[0053] Cost and complexity optimization: using capacitor oscillation circuits and capacitors with the same structure reduces the complexity of circuit design and production costs. At the same time, it avoids the use of complex anti-interference circuits (such as additional voltage stabilization circuits or filters) and improves the reliability and stability of the system.

[0054] Exemplary: Effect of Capacitor Oscillator Frequency Variation:

[0055] Scenario description: Assume that the system consists of two capacitor oscillators. The first capacitor oscillator circuit 102 is associated with the first counter 103, and the second capacitor oscillator circuit 202 is associated with the second counter 203. The interference causes the frequency of oscillator A to increase by 20%, and the frequency of oscillator B to increase by 10%. The second counter 203 has a fixed sampling time: because the second counter 203 is timed to a fixed value T cyc , the increase of 10% in the frequency of the second capacitor oscillation circuit 202 results in the actual sampling time being shortened to 1 / (1+10%)=0.909 times of the original.

[0056] The count value of the first counter 103 changes:

[0057] In the shortened sampling time determined by the second counter 203, the count value Cnt_samp of the first counter 103 will increase relatively due to the 20% increase in frequency. Specifically, the increase percentage is (1+20%) / (1+10%)-1=0.0909 or about 9.09%.

[0058] Impact of Synchronous Oscillator Structure:

[0059] If the structures and parameters of the first counter 103 and the second counter 203 are exactly the same, and both are subjected to the same amplitude (20%) of frequency increase, then in fact their count values ​​Cnt_samp will remain unchanged, because the increase rates of the two are the same, which offset each other's influence. This synchronization helps to eliminate errors caused by asymmetric interference.

[0060] In some specific embodiments, Figure 2 The first capacitor oscillation circuit 102 includes a power supply, a first current source, a second current source and a logic control circuit. The power supply is grounded through the first switch, the first current source, the second switch and the second current source in sequence. The logic control circuit is electrically connected to the control ends of the first switch and the second switch, the output ends of the first reference voltage comparator and the second reference voltage comparator, and the input end of the first counter 103, respectively. The first comparator and the second comparator are electrically connected to the capacitor sensing electrode 101, respectively.

[0061] Specifically, the first capacitor oscillation circuit 102 and the second capacitor oscillation circuit 202 have the same functions, and the power supply and current source are:

[0062] The power supply provides necessary power for the whole circuit. The first current source I1 and the second current source I2 are responsible for providing different currents during the charging and discharging process of the capacitance sensing electrode 101, respectively controlling the charging and discharging speed of the capacitor, thereby affecting the voltage change of the capacitance sensing electrode 101. The charging and discharging speed will affect the oscillation frequency, thereby affecting the count value of the counter. The first switch SW1 and the second switch SW2 are used to control the on and off of the current source, thereby controlling the charging and discharging process of the capacitor. The first switch controls the current source 1 (charging), and the second switch controls the current source 2 (discharging). Through the logic control of the two switches, the charging and discharging cycle of the capacitor can be accurately controlled. The current source is connected to the ground through the switch to form a charging and discharging loop of the capacitor. The first reference voltage comparator and the second reference voltage comparator are electrically connected to the capacitance sensing electrode 101, and are used to compare the voltage value of the capacitance sensing electrode 101 with the reference voltage. When the capacitor voltage reaches a certain threshold, the comparator will output a signal to the logic control circuit to inform that the capacitor has reached a predetermined voltage.

[0063] The first comparator is used to detect whether the voltage of the capacitive sensing electrode 101 when being charged reaches the upper limit reference voltage VH;

[0064] The second comparator is used to detect whether the voltage of the capacitive sensing electrode 101 during discharge reaches the lower limit reference voltage VL;

[0065] The logic control circuit controls the opening and closing of the first switch and the second switch according to the output signal of the comparator, thereby controlling the charging and discharging process of the capacitor, ensuring that the capacitive sensing electrode 101 is charged and discharged according to the set cycle;

[0066] The logic control circuit also transmits a control signal to the first counter 103 so that the counter starts counting the charge and discharge cycles. The count value of the counter is closely related to the change of the capacitance, and the count value is finally processed and analyzed by the processor control circuit 3.

[0067] In some specific embodiments, the reference capacitor 201 is a clock capacitor, and the second capacitor oscillation circuit 202 is grounded through the clock capacitor.

[0068] Specifically, in some embodiments, the clock capacitor 201 is used as a reference capacitor, providing a stable reference capacitor. In a conventional capacitive touch detection circuit, the reference capacitor is usually used to generate a standard charge and discharge cycle for comparison with the capacitance change of the capacitive sensing electrode;

[0069] By using the clock capacitor as a reference capacitor, the circuit is able to achieve a more stable and consistent periodic oscillation, which is essential for accurately measuring changes in the sensing electrode capacitance;

[0070] The second capacitor oscillation circuit 202 is grounded through the clock capacitor 201, which means that the operation of the second capacitor oscillation circuit 202 will be closely related to the charging and discharging characteristics of the clock capacitor. This configuration helps standardize the oscillation process and ensures that the charging and discharging cycles of the two oscillation circuits (detection circuit and reference circuit) are consistent; in this way, the clock capacitor not only serves as a reference capacitor, but also serves as the power supply of the oscillation circuit, providing a uniform oscillation frequency. This can reduce errors and fluctuations in the circuit, thereby enhancing anti-interference performance and stability.

[0071] In some specific embodiments, the reference capacitor 201 is configured as a sensing ring that surrounds the capacitive sensing electrode.

[0072] Specifically, in another embodiment, the relationship between the capacitance and the formula is: Formula 1 represents the relationship between the capacitance and the sampling value:

[0073] C1·T cyc =C pad ·Cnt samp ;

[0074] Among them, C1 is the parasitic capacitance of the inductive ring, T cyc is the predetermined count number of the second counter, Cpad is the capacitance of the sensing electrode, and Cnt_samp is the count value obtained by sampling.

[0075] It can be concluded that:

[0076]

[0077] In this formula, C1 (parasitic capacitance of the sensing ring) and Cpad (capacitance of the capacitive sensing electrode) are two key factors that determine the sampling value Cnt_samp.

[0078] When there is enough water 4 covering the surface of the sensing electrode and the sensing ring, the presence of water 4 will increase the capacitance value of the electrode (that is, both Cpad and C1 will increase). If the water coverage is large enough, the conductivity of the water will affect the capacitance measurement;

[0079] Since C1 and Cpad are in a division relationship in the formula, when C1 and Cpad increase at the same time, the value of Cnt_samp may remain unchanged or change slightly, thereby reducing the impact of water on the sampling results;

[0080] By adding a sensing ring to the outer circle of the sensing electrode, the sensing ring and the capacitive sensing electrode form a larger electric field sensing area. The capacitance changes of the sensing ring and the capacitive sensing electrode are synchronized. Therefore, when water covers the sensing electrode and the sensing ring, the changes of the two capacitances are consistent.

[0081] The presence of the sensing ring balances or offsets the impact of water coverage because the parasitic capacitance (C1 and Cpad) of the sensing electrode and the sensing ring changes at the same time. The processor can recognize this synchronous change instead of mistaking it for a capacitance change from touch. This design helps improve the system's ability to suppress false detection, especially in humid environments.

[0082] In some specific embodiments, the first counter 103, the second counter 203, the capacitive sensing electrode 101 and the reference capacitor 201 have the following relationship when in use:

[0083] C1×T cyc =C pad ×Cnt samp ;

[0084] Wherein, C1 is the capacitance value of the reference capacitor 201, T cyc is the predetermined count number of the second counter 203, C pad is the capacitance value of the capacitive sensing electrode 101, Cnt samp is the count value of the first counter 103.

[0085] Specifically, when an object approaches or touches the capacitive sensing electrode 101, C pad will change;

[0086] The reference capacitor C1 and the predetermined count number T of the second counter 203 cyc The reference circuit is set and monitored by the second counter 203, which ensures the stability and consistency of the system time reference. The first counter 103 records the number of charge and discharge times of the capacitive sensing electrode 101 in this cycle, i.e., Cnt samp ;

[0087] In specific implementation, C1 and T cyc They are fixed, and C1 and T are not considered in actual touch judgment. cyc , through the above power-on Cnt sam As the judgment standard, when Cnt sam When the count decreases by a certain number Sen (Sen is the sensitivity setting parameter), it is considered that there is a touch action.

[0088] In some specific embodiments, when the capacitance value of the capacitance sensing electrode 101 changes, the processor control circuit 3 can obtain the touch status of the capacitance sensing electrode 101 through the change of the count value of the first counter 103 .

[0089] Specifically, the main function of the capacitive sensing electrode 101 is to sense the capacitance change caused by the proximity or contact of a touch object (such as a human finger or a conductive pen). The change in capacitance is usually caused by the change in the electric field between the contact object and the electrode. The first counter 103 is responsible for calculating or recording the number of charge and discharge cycles of the capacitive sensing electrode 101 within a fixed sampling period Tcyc. Each charge and discharge cycle represents a complete change in capacitance, from charging to discharging. The processor control circuit 3 analyzes the change in capacitance based on the data received from the first counter 103. When the capacitance value of the capacitive sensing electrode 101 changes, the corresponding charge and discharge cycle will change, thereby affecting the count value Cntsamp of the counter.

[0090] In some specific embodiments, Figure 3 The voltage waveform at one end of the first capacitor oscillation circuit 102 connected to the capacitor sensing electrode 101 is a triangular wave, and the voltage waveform at one end of the first capacitor oscillation circuit 102 connected to the first counter 103 is a square wave.

[0091] Specifically, when the first capacitor oscillation circuit 102 is connected to the capacitor sensing electrode 101, the generated voltage waveform is a triangular wave, which indicates that the circuit design is a linear charge and discharge circuit, in which the capacitor voltage increases or decreases with time in a linear manner. The generation of the triangular wave involves a continuous charge and discharge cycle. The capacitor is charged by a constant current source until an upper limit voltage is reached, and then discharged by a constant current until a lower limit voltage is reached. This waveform is particularly useful for capacitance measurement because it provides clear information about the change in capacitance value, and the charge and discharge rate (slope) can be directly related to the size of the capacitor;

[0092] The connection end between the first capacitor oscillation circuit 102 and the first counter 103 outputs a square wave voltage waveform; a square wave generally refers to a voltage waveform having two fixed levels, high and low. The transition point of this waveform (from high to low or from low to high) is used to trigger the counter to count. In a capacitive touch system, a square wave can be used to represent a complete charge and discharge cycle. Whenever the square wave jumps from a high level to a low level or from a low level to a high level, the first counter 103 records it once, thereby calculating the number of charge and discharge cycles completed within a given time window. The use of square waves simplifies the design and triggering logic of the counter because the counter can simply increase the count when the voltage jumps. This design improves the response speed and reliability of the system.

[0093] In some specific embodiments, the time formula for charging and discharging the capacitive sensing electrode 101 each time is:

[0094] t=2*C*(V H -V L ) / I;

[0095] Where I is the size of the charging and discharging current source, C is the capacitance detected by the capacitive sensing electrode, VH is the reference voltage set by the first comparator, V L a reference voltage set for the second comparator;

[0096] In a certain period T, the counting formula of the first counter is:

[0097] N=T / t=T*I / (2*C*(V H -V L ));

[0098] Where t is the capacitance C from V L Charge to V H , and then discharge back to V L single cycle time.

[0099] In some specific embodiments, the first capacitor oscillation circuit is configured to perform the following steps:

[0100] The first switch is turned on, the second switch is turned off, the first current source charges the capacitor sensing electrode, when the capacitor sensing electrode voltage reaches the reference voltage of the first reference voltage comparator, the first switch is turned off, the second switch is turned on, the second current source discharges the capacitor sensing electrode, when the capacitor sensing electrode voltage reaches the reference voltage of the second reference voltage comparator, the first switch is turned on, the second switch is turned off, and the above charging and discharging process is repeated.

[0101] Specifically, the first switch is turned on and the second switch is turned off:

[0102] When the system starts working, the first switch is turned on, and the current source 1 (the first current source) starts to charge the capacitive sensing electrode (the capacitive sensing electrode 101). In this stage, the voltage of the capacitive sensing electrode 101 gradually rises until it reaches the set reference voltage.

[0103] The capacitance sensing electrode voltage reaches the first reference voltage:

[0104] When the voltage of the capacitive sensing electrode reaches the reference voltage (e.g., reference voltage VH) of the first reference voltage comparator, the first reference voltage comparator sends a signal to the logic control circuit to notify that the voltage of the capacitive sensing electrode has reached the upper limit;

[0105] The first switch is turned off and the second switch is turned on:

[0106] After receiving the first reference voltage comparator signal, the first switch is turned off, disconnecting the charging path of the current source 1 to the capacitive sensing electrode, and at the same time the second switch is turned on, and the current source 2 (the second current source) starts to discharge to the capacitive sensing electrode;

[0107] The capacitance sensing electrode voltage reaches the second reference voltage:

[0108] When the capacitance sensing electrode voltage drops to the reference voltage (e.g., reference voltage VL) of the second reference voltage comparator, the second reference voltage comparator sends a signal to the logic control circuit to inform that the capacitance sensing electrode voltage has reached the lower limit;

[0109] The first switch is on and the second switch is off:

[0110] After receiving the second reference voltage comparator signal, the first switch is turned on, and the current source 1 starts to charge the capacitive sensing electrode again. At the same time, the second switch is turned off, and the current source 2 stops discharging and restarts the charging process.

[0111] The charging and discharging process will be repeated periodically according to the above steps.

[0112] The above is only a specific implementation of the embodiment of the present invention, but the protection scope of the embodiment of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiment of the present invention should be included in the protection scope of the embodiment of the present invention. Therefore, the protection scope of the embodiment of the present invention should be based on the protection scope of the claims.

Claims

1. A capacitive touch detection circuit, characterized in that: including a detection circuit and a reference circuit; The detection circuit is electrically connected to the reference circuit via a processor control circuit; The detection circuit includes a first interface electrically connected to the capacitive sensing electrode, a first capacitive oscillation circuit and a first counter, and the capacitive sensing electrode is electrically connected to the processor control circuit in sequence through the first capacitive oscillation circuit, the first counter and the processor control circuit; The reference circuit includes a second interface electrically connected to the reference capacitor, a second capacitor oscillation circuit and a second counter, and the reference capacitor is electrically connected to the processor control circuit in sequence through the second capacitor oscillation circuit, the second counter and the processor control circuit; The first capacitor oscillation circuit and the second capacitor oscillation circuit have the same structure and parameters.

2. A capacitive touch detection circuit according to claim 1, characterized in that: The first capacitor oscillation circuit includes a power supply, a first current source, a second current source and a logic control circuit. The power supply is grounded through a first switch, a first current source, a second switch and a second current source in sequence. The logic control circuit is electrically connected to control ends of the first switch and the second switch, output ends of the first reference voltage comparator and the second reference voltage comparator, and an input end of the first counter, respectively. The first comparator and the second comparator are electrically connected to the capacitor sensing electrodes, respectively.

3. A capacitive touch detection circuit according to claim 1, characterized in that: The reference capacitor is a clock capacitor, and the second capacitor oscillation circuit is grounded through the clock capacitor.

4. A capacitive touch detection circuit according to claim 1, characterized in that: The reference capacitor is configured as a sensing ring that surrounds the capacitance sensing electrode.

5. A capacitive touch detection circuit according to claim 1, characterized in that: The relationship between the first counter, the second counter, the capacitance sensing electrode and the reference capacitor during use is as follows: C1×T cyc =C pad ×Cnt samp ; Where C1 is the capacitance value of the reference capacitor, T cyc is the predetermined count number of the second counter, C pad is the capacitance value of the capacitive sensing electrode, Cnt samp is the count value of the first counter.

6. A capacitive touch detection circuit according to claim 5, characterized in that: When the capacitance value of the capacitive sensing electrode changes, the processor control circuit 3 can obtain the touch status of the capacitive sensing electrode through the change of the count value of the first counter.

7. A capacitive touch detection circuit according to claim 2, characterized in that: The voltage waveform of the end of the first capacitor oscillation circuit connected to the capacitor sensing electrode is a triangular wave, and the voltage waveform of the end of the first capacitor oscillation circuit connected to the first counter is a square wave.

8. A capacitive touch detection circuit according to claim 7, characterized in that: The time formula for charging and discharging the capacitive sensing electrode each time is: t=2*C*(V H -V L ) / I; Where I is the charge and discharge current source, C is the capacitance detected by the capacitive sensing electrode, and V H The reference voltage set for the first comparator, V L a reference voltage set for the second comparator; In a certain period T, the counting formula of the first counter is: N=T / t=T*I / (2*C*(V H -V L )); Where t is the capacitance C from V L Charge to V H , and then discharge back to V L single cycle time.

9. A capacitive touch detection circuit according to claim 2, characterized in that: The first capacitor oscillation circuit is configured as follows: The first switch is turned on, the second switch is turned off, the first current source charges the capacitor sensing electrode, when the capacitor sensing electrode voltage reaches the reference voltage of the first reference voltage comparator, the first switch is turned off, the second switch is turned on, the second current source discharges the capacitor sensing electrode, when the capacitor sensing electrode voltage reaches the reference voltage of the second reference voltage comparator, the first switch is turned on, the second switch is turned off, and the above charging and discharging process is repeated.

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